Waste Treatment in the Biotechnology, Agricultural and Food Industries : Volume 2 [27, 1 ed.] 9783031447679, 9783031447686

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Handbook of Environmental Engineering  27

Lawrence K. Wang Mu-Hao Sung Wang Yung-Tse Hung   Editors

Waste Treatment in the Biotechnology, Agricultural and Food Industries Volume 2

Handbook of Environmental Engineering 27 Series Editors Lawrence K. Wang PhD, Rutgers University, New Brunswick, New Jersey, USA MS, University of Rhode Island, Kingston, Rhode Island, USA MSCE, Missouri University of Science and Technology, Rolla, Missouri, USA BSCE, National Cheng Kung University, Tainan, Taiwan, ROC Mu-Hao Sung Wang PhD, Rutgers University, New Brunswick, New Jersey, USA MS, University of Rhode Island, Kingston, Rhode Island, USA BSCE, National Cheng Kung University, Tainan, Taiwan, ROC

The past over one-half century has seen the emergence of a growing desire worldwide to take positive actions to restore and protect the environment from the degrading effects of all forms of pollution: air, noise, solid waste, and water. The principle intention of the Handbook of Environmental Engineering (HEE) series is to help readers formulate answers to the fundamental questions facing pollution in the modern era, mainly, how serious is pollution and is the technology needed to abate it not only available, but feasible. Cutting-edge and highly practical, HEE offers educators, students, and engineers a strong grounding in the principles of Environmental Engineering, as well as providing effective methods for developing optimal abatement technologies at costs that are fully justified by the degree of abatement achieved. With an emphasis on using the Best Available Technologies, the authors of these volumes present the necessary engineering protocols derived from the fundamental principles of chemistry, physics, and mathematics, making these volumes a must have for environmental pollution researchers.

Lawrence K. Wang Mu-Hao Sung Wang  •  Yung-Tse Hung Editors

Waste Treatment in the Biotechnology, Agricultural and Food Industries Volume 2

Editors Lawrence K. Wang Lenox Institute of Water Technology Latham, NY, USA

Mu-Hao Sung Wang Lenox Institute of Water Technology Latham, NY, USA

Yung-Tse Hung Department of Civil and Environmental Engineering Cleveland State University Strongsville, OH, USA

ISSN 2512-1359     ISSN 2512-1472 (electronic) Handbook of Environmental Engineering ISBN 978-3-031-44767-9    ISBN 978-3-031-44768-6 (eBook) https://doi.org/10.1007/978-3-031-44768-6 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Paper in this product is recyclable.

Preface

The past over one half century has seen the emergence of a growing desire worldwide that positive actions be taken to restore and protect the environment from the degrading effects of all forms of pollution -- air, water, soil, thermal, radioactive, and noise. Since pollution is a direct or indirect consequence of waste, the seemingly idealistic demand for “zero discharge” can be construed as an unrealistic demand for zero waste. However, as long as waste continues to exist, we can only attempt to abate the subsequent pollution by converting it to a less noxious form, or reusable form. Three major questions usually arise when a particular type of pollution has been identified: (1) How serious are the environmental pollution and natural resources crisis? (2) Is the technology to abate them or recycle them available? and (3) Do the costs of abatement justify the degree of treatment achieved for environmental protection and resource conservation? This book is one of the volumes of the Handbook of Environmental Engineering series. The principal intention of this series is to help readers formulate answers to the above three questions. The traditional approach of applying tried-and-true solutions to specific environmental and natural resources problems has been a major contributing factor to the success of environmental engineering and has accounted in large measure for the establishment of a “methodology of pollution control.” However, the realization of the ever-increasing complexity and interrelated nature of current environmental problems renders it imperative that intelligent planning of pollution abatement systems be undertaken. A prerequisite to such planning is an understanding of the performance, potential, and limitations of the various methods of environmental protection and resource recovery available for environmental scientists and engineers. In this series of handbooks, we will review at a tutorial level a broad spectrum of engineering systems (natural environment, processes, operations, and methods) currently being utilized, or of potential utility, for pollution abatement, environmental protection, and natural resources conservation. We believe that the unified interdisciplinary approach presented in these handbooks is a logical step in the evolution of environmental engineering.

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Treatment of the various engineering systems presented will show how an engineering formulation of the subject flows naturally from the fundamental principles and theories of chemistry, microbiology, physics, and mathematics. This emphasis on fundamental science recognizes that engineering practice has, in recent years, become more firmly based on scientific principles rather than on its earlier dependency on an empirical accumulation of facts. It is not intended, though, to neglect empiricism where such data lead quickly to the most economical design. Certain engineering systems are not readily amenable to fundamental scientific analysis, and in these instances, we have resorted to less science in favor of more art and empiricism. Since a bio-environmental engineer must understand science within the context of applications, we first present the development of the scientific basis of a particular subject, followed by an exposition of the pertinent design concepts and operations, and detailed explanations of their applications to natural resources conservation or environmental protection. Throughout the series, methods of mathematical modeling, system analysis, practical design, and calculation are illustrated by numerical examples. These examples clearly demonstrate how organized, analytical reasoning leads to the most direct and clear solutions. Wherever possible, pertinent cost data or models have been provided. Our treatment of wastes from biotechnology, agricultural, and food industries is offered in the belief that the trained engineer should more firmly understand fundamental principles, be more aware of the similarities and/or differences among many of the bio-environmental engineering systems, and exhibit greater flexibility and originality in the definition and innovative solution of bio-environmental system problems. In short, bio-environmental engineers should, by conviction and practice, be more readily adaptable to change and progress. Coverage of the unusually broad field of environmental science, technology, engineering, and mathematics (STEM) has demanded expertise that could only be provided through multiple authorships. Each author (or group of authors) was permitted to employ, within reasonable limits, the customary personal style in organizing and presenting a particular subject area; consequently, it has been difficult to treat all subject materials in a homogeneous manner. Moreover, owing to the limitations of space, some of the authors’ favored topics could not be treated in great detail, and many less important topics had to be merely mentioned or commented on briefly. All authors have provided an excellent list of references at the end of each chapter for the benefit of interested readers. As each chapter is meant to be self-­ contained, some mild repetition among the various texts was unavoidable. In each case, all omissions or repetitions are the responsibility of the editors and not the individual authors. With the current trend toward metrication, the question of using a consistent system of units has been a problem. Wherever possible, the authors have used the British system (fps) along with the metric equivalent (mks, cgs, or SIU) or vice versa. The editors sincerely hope that this redundancy of units’ usage will prove to be useful rather than disruptive to the readers. The goals of the Handbook of Environmental Engineering (HEE) series are as follows: (1) to cover entire environmental fields, including air, land, water and noise

Preface

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pollution control, solid waste processing and resource recovery, physicochemical treatment processes, biological treatment processes, biotechnology, biosolids management, flotation technology, membrane technology, desalination technology, water resources, natural control processes, radioactive waste disposal, hazardous waste management, and thermal pollution control; and (2) to employ a multimedia approach to environmental conservation and protection since air, water, soil, and energy are all interrelated. This book (Waste Treatment in the Biotechnology, Agricultural and Food Industries, Volume 2) and its sister book (Waste Treatment in the Biotechnology, Agricultural and Food Industries, Volumes 1) of the Handbook of Environmental Engineering (HEE) series have been designed to serve as a mini-series of bio-­ environmental engineering and management textbooks as well as supplemental reference books. We hope and expect they will prove of equally high value to advanced undergraduate and graduate students, to designers of sustainable biological resources systems, and to scientists and researchers. The editors welcome comments from readers in all of these categories. It is our hope that the entire series of bio-­ environmental engineering and management books will not only provide information on agricultural science and biotechnologies but will also serve as a basis for advanced study or specialized investigation of the theory and analysis of various biological natural resources systems. This book, Waste Treatment in the Biotechnology, Agricultural and Food Industries, Volume 2, covers the topics on (a) application of secondary flotation-­ filtration and coagulant recycle for improvement of a pulp mill primary waste treatment facility; (b) management of various sources of hazardous waste; (c) microbial enzymes for wastewater treatment; (d) a multi-criteria approach to appropriate treatment technology selection for water reclamation; (e) chemicals used in agriculture: hazards and associated toxicity issues; (f) biochar for adsorptive removal of pharmaceuticals from environmental water; (g) treatment of palm oil mill effluent; (h) treatment and management of hazardous solid waste stream by incineration; and (i) technologies for removal of volatile organic compounds (VOC) from industrial effluents and/or potable water sources; and (j) various technologies in healthcare waste management and disposal. This book’s sister book, Waste Treatment in the Biotechnology, Agricultural and Food Industries, Volume 1, covers the topics on management and treatment of livestock wastes; waste treatment in the pharmaceutical biotechnology industry using green environmental technologies; vermicomposting process for treating agricultural and food wastes; the impacts of climate change on agricultural, food, and public utility industries; innovative PACT activated sludge, CAPTOR activated sludge, activated bio-filter, vertical loop reactor, and PHOSTRIP processes; agricultural waste treatment by water hyacinth aquaculture, wetland aquaculture, evapotranspiration, rapid rate land treatment, slow rate land treatment, and subsurface infiltration; production and applications of crude polyhydroxyalkanoate-­containing bioplastic from agricultural and food-processing wastes; optimization processes of biodiesel production from pig and neem (Azadirachta indica a.juss) seeds blend oil using alternative catalysts from waste biomass; castor oil: a promising source for

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the production of flavor and fragrance through lipase mediated biotransformation; and treatment and minimization of waste in baker’s yeast industry. The editors are pleased to acknowledge the encouragement and support received from Mr. Aaron Schiller, Executive Editor of the Springer Nature Switzerland AG, and his colleagues, during the conceptual stages of this endeavor. We wish to thank the contributing authors for their time and effort, and for having patiently borne our reviews and numerous queries and comments. We are very grateful to our respective families for their patience and understanding during some rather trying times. Latham, NY, USA Latham, NY, USA Strongsville, OH, USA

Lawrence K. Wang Mu-Hao Sung Wang Yung-Tse Hung

Contents

1

Application of Secondary Flotation-­Filtration and Coagulant Recycle for Improvement of a Pulp Mill Primary Waste Treatment Facility��������������������������������    1 Lawrence K. Wang and Mu-Hao Sung Wang

2

 Management of Various Sources of Hazardous Waste ������������������������   19 Nor Azalina Rosli, Hamidi Abdul Aziz, Leonard Lim Lik Pueh, Inawati Binti Othman, Mohd Hafiz Zawawi, and Yung-Tse Hung

3

Microbial Enzymes for Wastewater Treatment������������������������������������   65 Buse Çaloğlu, Kübra Laçın, Barış Binay, and Yung Tse Hung

4

A Multi-criteria Approach to Appropriate Treatment Technology Selection for Water Reclamation ��������������������  133 Ria Ranjan Srivastava, Prabhat Kumar Singh, and Yung-Tse Hung

5

Chemicals Used in Agriculture: Hazards and Associated Toxicity Issues������������������������������������������������  185 Awanish Kumar, Santosh Kumar Karn, and Yung-Tse Hung

6

Biochar for Adsorptive Removal of Pharmaceuticals from Environmental Water ��������������������������������������������������������������������  199 Mukarram Zubair, Qazi Saliq, Muhammad Saood Manzar, Hamidi Abdul Aziz, Hajira Haroon, Yung-Tse Hung, Lawrence K. Wang, and Mu-Hao Sung Wang

7

 Treatment of Palm Oil Mill Effluent������������������������������������������������������  227 Nor Habsah Md Sabiani, Rosnani Alkarimiah, Khairul Rahmah Ayub, Muaz Mohd Zaini Makhtar, Hamidi Abdul Aziz, Yung-Tse Hung, Lawrence K. Wang, and Mu-Hao Sung Wang

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Contents

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Treatment and Management of Hazardous Solid Waste Stream by Incineration������������������������������������������������������  285 Mohamad Anuar Kamaruddin, Wen Si Lee, Faris Aiman Norashiddin, Mohamad Haziq Mohd Hanif, Hamidi Abdul Aziz, Lawrence K. Wang, Mu-Hao Sung Wang, and Yung-Tse Hung

9

Technologies for Removal of Hazardous Volatile Organic Compounds from Industrial Effluents and/or Potable Water Sources����������������������������������������������������������������  337 Rosnani Alkarimiah, Nursyafi Amila Hilmy, Hamidi Abdul Aziz, Lawrence K. Wang, Mu-Hao Sung Wang, and Yung-Tse Hung

10 Various  Technologies in Healthcare Waste Management and Disposal����������������������������������������������������������������������������������������������  367 Wen Si Lee, Hamidi Abdul Aziz, Lawrence K. Wang, Mu-Hao Sung Wang, and Yung-Tse Hung List of Figures��������������������������������������������������������������������������������������������������  423 List of Tables����������������������������������������������������������������������������������������������������  427 Index������������������������������������������������������������������������������������������������������������������  431

Contributors

Rosnani  Alkarimiah  Environmental Engineering: School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Pulau Pinang, Malaysia Khairul Rahmah Ayub  River Engineering and Urban Drainage Research Centre (REDAC), Engineering Campus, Universiti Sains Malaysia, Pulau Pinang, Malaysia Hamidi  Abdul  Aziz  School of Civil Engineering/Solid Waste Management Cluster, Engineering Campus, Universiti Sains Malaysia, Pulau Pinang, Malaysia Barış  Binay  Department of Bioengineering, Faculty of Engineering, Gebze Technical University, Kocaeli, Turkey Gebze Technical University Technopark Region, BAUZYME Biotechnology Co., Kocaeli, Turkey Buse  Çaloğlu  Department of Bioengineering, Faculty of Engineering, Gebze Technical University, Kocaeli, Turkey Mohamad Haziq Mohd Hanif  School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia Hajira  Haroon  Department of Environmental Sciences, University of Haripur, KPK, Pakistan Nursyafi Amila Hilmy  Environmental Engineering, School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia Yung-Tse Hung  Department of Civil and Environmental Engineering, Cleveland State University, Strongsville, OH, USA Mohamad Anuar Kamaruddin  School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia Santosh  Kumar  Karn  Department of Biotechnology, Sardar Bhagwan Singh University, Former Sardar Bhagwan Singh Post Graduate Institute of Biomedical Science & Research, Dehradun, India xi

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Awanish Kumar  Department of Biotechnology, National Institute of Technology, Raipur, India Kübra  Laçın  Department of Bioengineering, Faculty of Engineering, Gebze Technical University, Kocaeli, Turkey Wen Si Lee  School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Pulau Pinang, Malaysia Muaz  Mohd  Zaini  Makhtar  School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia Muhammad  Saood  Manzar  Department of Environmental Engineering, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia Faris  Aiman  Norashiddin  School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia Inawati Binti Othman  Department of Civil Engineering, Unimas Water Centre, Universiti Malaysia Sarawak, Sarawak, Malaysia Leonard Lim Lik Pueh  Department of Civil Engineering, Unimas Water Centre, Universiti Malaysia Sarawak, Sarawak, Malaysia Nor  Azalina  Rosli  Department of Civil Engineering, Unimas Water Centre, Universiti Malaysia Sarawak, Sarawak, Malaysia Nor  Habsah  Md  Sabiani  School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Pulau Pinang, Malaysia Qazi  Saliq  Department of Environmental Sciences, University of Haripur, KPK, Pakistan Prabhat  Kumar  Singh  Department of Civil Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, Uttar Pradesh, India Ria  Ranjan  Srivastava  Department of Civil Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, Uttar Pradesh, India Mu-Hao Sung Wang  Lenox Institute of Water Technology, Latham, NY, USA Lawrence K. Wang  Lenox Institute of Water Technology, Latham, NY, USA United Nations Industrial Development Organization (UNIDO), Vienna, Austria Agricultural Engineering Department, University of Illinois, Urbana- Champaign, Urbana, IL, USA Mohd  Hafiz  Zawawi  Department of Civil Engineering, Engineering, Universiti Tenaga Nasional, Kajang, Selangor, Malaysia Mukarram  Zubair  Department of Environmental Engineering, Abdulrahman Bin Faisal University, Dammam, Saudi Arabia

Imam

About the Editors

Lawrence K. Wang has served the society as a professor, inventor, chief engineer, chief editor, and public servant (UN, USEPA, New York State) for 50+ years, with experience in the entire field of environmental science, technology, engineering, and mathematics (STEM). He is a licensed professional engineer, a certified laboratory director, a licensed water operator, and an OSHA hazardous waste management instructor. He has a special passion and expertise in developing various innovative technologies, educational programs, licensing courses, international projects, academic publications, and humanitarian organizations, all for his dream goal of promoting world peace. He is a retired acting president/professor of the Lenox Institute of Water Technology, USA; a senior advisor of the United Nations Industrial Development Organization (UNIDO), Vienna, Austria; and a former professor/visiting professor of Rensselaer Polytechnic Institute, Stevens Institute of Technology, University of Illinois, National Cheng-Kung University, Zhejiang University, and Tongji University. Dr. Wang is the author of 750+ technical papers and 50+ engineering books, and is credited with 29 invention patents. He holds a BSCE degree from National Cheng- Kung University, Taiwan, ROC; a MSCE degree from the University of Missouri; a MS degree from the University of Rhode Island; and a PhD degree from Rutgers University, USA.  Currently, he is the book series editor of CRC Press, Springer Nature Switzerland, Lenox Institute Press, World Scientific Singapore, and John Wiley. Dr. Wang has been a xiii

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delegate of the People to People International Foundation, a diplomate of the American Academy of Environmental Engineers, a member of ASCE, AIChE, ASPE, WEF, AWWA, CIE and OCEESA, and a recipient of many US and international engineering and science awards. Mu-Hao  Sung  Wang has been an engineer of the New  York State Department of Environmental Conservation, an editor of CRC Press, Springer Nature Switzerland, and Lenox Institute Press, and a university professor at the Stevens Institute of Technology, National Cheng-Kung University, and the Lenox Institute of Water Technology. Totally, she has been a government official and an educator in the USA and Taiwan for over 50  years. Dr. Wang is a licensed Professional Engineer and a Diplomate of the American Academy of Environmental Engineers (AAEE). Her publications have been in the areas of water quality, modeling, environmental sustainability, solid and hazardous waste management, NPDES permit management, flotation technology, industrial waste treatment, and analytical methods. Dr. Wang is the author of over 100 technical papers, and 16 books, and an inventor of 14 US and foreign patents. She holds a BSCE degree from National Cheng-Kung University, Taiwan, ROC; a MS degree from the University of Rhode Island, RI, USA; and a PhD degree from Rutgers University, NJ, USA.  She is the co-series editor of the Handbook of Environmental Engineering series (Springer Nature Switzerland), coeditor of the Advances in Industrial and Hazardous Wastes Treatment series (CRC Press of Taylor & Francis Group), and the coeditor of the Environmental Science, Technology, Engineering and Mathematics series (Lenox Institute Press). She is a member of AWWA, NYWWA, NEWWA, WEF, NEWEA, CIE, and OCEESA.

About the Editors

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Yung-Tse  Hung has been a professor of Civil Engineering at Cleveland State University, Cleveland, Ohio, USA, since 1981. He is a fellow of the American Society of Civil Engineers, a licensed professional engineer in Ohio and North Dakota, and a diplomate of American Academy of Environmental Engineers. He has taught at 16 universities in 8 countries. His research interests and publications have been involved with biological treatment processes, solid wastes, hazardous waste management, and industrial waste treatment. Dr. Hung is credited with over 470 publications and presentations, 28 books, 159 book chapters, in water and wastewater treatment. He received his BSCE and MSCE degrees from National Cheng-Kung University, Taiwan, ROC, and his PhD degree from the University of Texas at Austin, USA. He is the editor-in-chief of International Journal of Environmental Pollution Control and Management, International Journal of Environmental Engineering, and International Journal of Environmental Engineering Science, and co-editor of the Advances in Industrial and Hazardous Wastes Treatment series (CRC Press of Taylor & Francis Group), and the Handbook of Environmental Engineering series (Springer). Dr. Hung is also the chief editor of the Handbook of Environment and Waste Management series (World Scientific Singapore), and the permanent executive director and ex-president of OCEESA (Overseas Chinese Environmental Engineers and Scientists Association).

Chapter 1

Application of Secondary Flotation-­Filtration and Coagulant Recycle for Improvement of a Pulp Mill Primary Waste Treatment Facility Lawrence K. Wang and Mu-Hao Sung Wang

Acronym ADT BOD CMD COD DAF DAFF KEC LIWT MPW TSS WWT

Air dissolving tube Biochemical oxygen demand Cubic meter per day Chemical oxygen demand Dissolved air flotation Dissolved air flotation-filtration Krofta Engineering Corporation Lenox Institute of Water Technology Municipal potable water Total suspended solids Wastewater treatment

1.1 Introduction 1.1.1 General Introduction Under the sponsorship of Krofta Engineering Corporation (KEC), the Lenox Institute of Water Technology (LIWT) (formerly Lenox Institute for Research) has developed (a) a secondary dissolved air flotation-filtration (DAFF) process addition for improvement of the existing primary waste treatment facility of an Asian pulp mill; and (b) an innovative chemical coagulant recycle system for the same pulp L. K. Wang (*) · M.-H. S. Wang Lenox Institute of Water Technology, Latham, NY, USA e-mail: [email protected]; [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 L. K. Wang et al. (eds.), Waste Treatment in the Biotechnology, Agricultural and Food Industries, Handbook of Environmental Engineering 27, https://doi.org/10.1007/978-3-031-44768-6_1

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mill for sludge handling and cost saving. The pulp mill’s name and address are kept confidential upon requests from both the mill and the sponsor. In this research, the facilities and efficiencies of the existing pulp mill’s wastewater treatment plant are evaluated and introduced. Subsequently, an improved two-­ stage independent physicochemical wastewater treatment system is designed to: (a) use the existing primary coagulation-sedimentation wastewater treatment (WWT) facility to be the first stage WWT; and (b) adopt a new secondary dissolved air flotation (DAF) and filtration to be the second stage WWT. A complete sludge recycle system is developed for chemical sludge handling and cost-saving. The waste sludge recycle system emphasized here involves the following steps: (a) collecting and drying the waste sludge from flotation and/or sedimentation clarifiers, (b) dividing the dried combined sludge into two fractions for aluminum solubilization: one fraction in an acid treatment unit and another fraction in an alkaline treatment unit, (c) filtering the inert silts for ultimate disposal, and (d) returning the solubilized aluminum-containing chemicals from the acid and alkaline treatment units in proper proportions for reuse as primary coagulants. The newly developed two-stage independent physicochemical wastewater treatment (WWT) system and the chemical sludge recycle process have been designed to provide a cost effective solution for wastewater treatment, sludge treatment, chemical recycle and cost-saving. Experimental results tend to suggest that both the WWT process system and the coagulant recycle system are technically and economically feasible. This publication is one of the authors’ professional memoirs for documentation of the research and development (R&D) projects completed by LIWT and KEC.

1.1.2 Pulp Mill and Existing Wastewater Treatment Facilities The pulp mill uses the bleached Kraft pulping process, and already has an existing wastewater treatment system consisting of screening, grit removal, flocculation, and sedimentation. The sedimentation effluent is being discharged into the Pacific Ocean. There are three major wastewater streams generated at the pulp mill: (a) alkaline wastewater, FBE; (b) acidic wastewater, FAE; and (c) neutral wastewater, RWE. The local government effluent standards on pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) are presented here: (a) pH between 6.5 and 8.5; (b) COD below 100 mg/L; (c) BOD below 100 mg/L; and (d) TSS below 100 mg/L. The flow diagram of the existing wastewater treatment facility is a standard independent physicochemical wastewater treatment process system [1] consisting of one grit chamber (detention time = 1 min; volume = 12 m3) for preliminary treatment, a chemical feed and mixing system, one flocculator (detention time = 35 min; volume = 376 m3), and one circular sedimentation clarifier (detention time = 260 min; volume = 4503 m3; diameter = 43 m; surface loading rate = 14.5 m/day; depth = 4 m), one circular gravity sludge thickener (detention time = 24 h; volume = 1550 m3; diameter = 27 m; height = 4 m), and one vacuum filter for sludge dewatering.

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The treatment efficiency of the existing wastewater and sludge treatment facilities can be understood by examination of Tables 1.1 and 1.2. Tables 1.1 and 1.2 were compiled based on actual operational data of 12 consecutive working days. In the 12-day investigation period, the characteristics of acidic wastewater (FAE), alkaline wastewater (FBE), and neutral wastewater (RWE) were monitored for pH, color, TSS, BOD, COD, and temperature. In reviewing Table  1.1, it is understood that FBE has the highest color, TSS, BOD and COD. FAE’s color, BOD, and COD rank second. The RWE’s color, BOD, COD, and temperature are lowest among the three wastewater streams but its TSS exceeds the effluent limit of 100 mg/L. The major effort of the existing wastewater treatment facility has been aimed at treatment of FAE and FBE. FBE is treated by screens, grit chamber, flocculation, and sedimentation. FAE is initially neutralized by lime slurry in a neutralization tank and subsequently mixed with RWE in a mixing tank, from where the mixture of neutralized FAE and RWE is discharged into a final out-fall tank to meet with the clarified FBE. From the out-fall tank, the mixture of all three treated FAW, RWE, and FBE is discharged into the receiving ocean. The municipal potable water (MPW) is used for lime and polymer preparation, and for cleaning of the sludge dewatering facility.

Table 1.1  Treatment efficiency of pulp mill existing wastewater treatment system: influent wastewater characteristics Parameters Acidic wastewater pH, unit Color, unit TSS, mg/L BOD, mg/L COD, mg/L Temperature, °C Alkaline wastewater pH, unit Color, unit TSS, mg/L BOD, mg/L COD, mg/L Temperature, °C Neutral wastewater pH, unit Color, unit TSS, mg/L BOD, mg/L COD, mg/L Temperature, °C

Water quality data Range

Average

1.7–2.7 106–203 35–116 159–249 262–424 40–52

2.0 169 54 205 329 46

6.0–9.8 1108–5754 194–568 310–1283 525–1304 40–50

8.7 2495 335 528 688 45

7.7–8.6 73–308 67–330 10–109 24–129 17–36

8.3 127 169 48 71 24

(FAE)

(FBE)

(RWE)

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L. K. Wang and M.-H. S. Wang

Table 1.2  Treatment efficiency of pulp mill existing wastewater treatment system: effluent wastewater characteristics Parameters Sedimentation effluent pH, unit Color, unit TSS, mg/L BOD, mg/L COD, mg/L Temperature, °C Sludge thickener effluent pH, unit Color, unit TSS, mg/L BOD, mg/L COD, mg/L Temperature, °C Plant effluent pH, unit Color, unit TSS, mg/L BOD, mg/L COD, mg/L Temperature, °C

Water quality data Range

Average

9.5–1.1 241–1438 61–187 164–298 197–413 31–43

10.7 571 125 235 290 37

10.0–10.6 1066–1528 1171–2136 367–598 600–1389 34–39

10.3 1364 1703 501 930 36

5.9–8.1 390–1381 156–309 112–395 210–495 30–44

6.9 794 199 198 304 36

The settled chemical sludge at the bottom of the sedimentation basin is pumped to a sludge gravity thickener for thickening, and then conveyed to a vacuum filter for dewatering. The dewatered sludge cake is shipped out by trucks for ultimate disposal. Table 1.2 indicates the characteristics of sedimentation effluent, sludge thickener effluent, and the plant effluent at the out-fall, after the three wastewater streams (FAE, FBE, and RWE shown in Table 1.1) were treated by the existing wastewater and sludge treatment facilities in the 12-day investigation period. The effluent data in Table 1.2 clearly show that the organic loadings (in terms of BOD and COD) and solids loading (in terms of TSS) of sludge thickener effluent are very high, and must be taken into account for process improvement. The plant effluent’s TSS, BOD, and COD all exceeded the effluent standards of 100 mg/L for each. The high effluent color must be reduced. In summation, the existing waste treatment plant at the pulp mill must be upgraded. Section 2 introduces an improved wastewater treatment system involving the use of dissolved air flotation (DAF) and filtration for the selected pump mill. The combination of DAF and filtration is also known as the DAFF process system [2]. Although the evaluated DAFF is a KEC product (Sandfloat), any other manufacturer’s equivalent DAF, DAFF, or filtration facilities [3, 4] should be equally effective for WWT. Section 3 introduces the newly developed complete sludge recycle system for sludge handling, coagulant recovery, and cost-saving.

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1.2 Improved Wastewater Treatment System 1.2.1 Two-Stage Wastewater Treatment System The single-stage primary physical-chemical treatment introduced previously in Sect. 1.1 was not totally successful. It has been proven that dissolved air flotation and filtration (DAFF) are feasible for removal of high color [5], COD, BOD, and TSS [6, 7]. Accordingly, a two-stage physical-chemical process system was experimentally developed at the pulp mill. The two-stage system considers (a) the use of the existing wastewater treatment facility in the first stage (primary wastewater treatment) and (b) the use of dissolved air flotation and filtration (i.e. Krofta DAFF Sandfloat, or equivalent DAF and filtration facilities) in the second stage (secondary wastewater treatment). Specifically, the entire new two-stage wastewater treatment system consists of (a) the first stage (primary treatment) of raw wastewater by grit chamber, chemical feeding/mixing, flocculation, and sedimentation and (b) the second stage (secondary treatment) of the sedimentation effluent by dissolved air flotation and filtration, shown in Fig. 1.1. The sedimentation effluent is the primary effluent. The Lenox Institute of Water Technology (LIWT)  personnel conducted the process experiments for wastewater treatment, but the pulp mill’s own laboratory chemists took influent and effluent samples for water quality analyses at the mill. Tables 1.3 and 1.4 document the joint research effort of the LIWT engineers and the pulp mill chemists. The definitions of primary wastewater treatment, secondary wastewater treatment, and other related technical terms, can be found from the Glossary section. In all cases, the combined FAE and FBE wastewater was treated. Initial COD of the influent wastewater was 760 mg/L. Other influent characteristics are listed in Tables 1.3 and 1.4. Experimental conditions, chemical, dosages, sludge production, etc. of each stage are documented at the bottom of the two tables.

1.2.2 Alternative One Table 1.3 presents the treatment data when coagulants D101, D102, D103, and D104 were used. The experimental conditions of Alternative One (Test 3) are documented as follows: (a) combined FAE and FBE wastewater was prepared with 50% FAE and 50% FBE; small volume of distilled water was used to adjust the influent COD to 760 mg/L before treatment; (b) coagulants used in the first stage flocculation and sedimentation treatment = 200 mg/L D101, 50 mg/L D102, and 100 mg/L D103; sludge production by weight = 2430.5 mg dry sludge per liter of wastewater = 84,882 kg/day; sludge production by volume = 130 mL/1000 mL after 3 h of settling; and (c) coagulants used in the second stage Sandfloat treatment (flocculation, dissolved air flotation, and sand filtration)  =  40  mg/L D104 and 150  mg/L D103; sludge production by weight  =  464  mg dry sludge per liter of

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Fig. 1.1  Newly designed two-stage physical-chemical process system using dissolved air flotation and filtration in second stage

Table 1.3  Treatment of combined FAE and FBE wastewater by two-stage physical-chemical process system using settler, DAFF-Sandfloat, and Krofta Flocs D101, D102, D103, and D104 Water quality parameters pH, unit Color, unit TSS, mg/L COD, mg/L BOD, mg/L

Influent 2.4 1125 140 760 548

First stage effluent 5.5 290 210 150 108

Second stage effluent 7.5 55 80 87.5 63

Combined FAE and FBE wastewater was prepared with 50% FAE and 50% FBE. Small volume of distilled water was used to adjust the influent COD to 760 mg/L before treatment b Coagulants used in the first stage flocculation and sedimentation treatment = 200 mg/L D101, 50 mg/L D102, and 100 mg/L D103. Sludge production by weight = 2430.5 mg dry sludge per liter of wastewater  =  84,882  kg/day. Sludge production by volume  =  130  mL/1000  mL after 3  h of settling c Coagulants used in the second stage DAFF-Sandfloat treatment (flocculation, dissolved air flotation, and sand filtration)  =  40  mg/L D104 and 150  mg/L D103. Sludge production by weight = 464 mg dry sludge per liter of wastewater = 14,751 kg/day. Sludge production by volume = 90 mL/1000 mL after 10 min of flotation. 30% pressurized recycle flow at 45 psig was used in DAF.  Dilution factor by recycle flow was considered and corrected in effluent water quality determinations a

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Table 1.4  Treatment of combined FAE and FBE wastewater by two-stage physical-chemical process system using settler, DAFF-Sandfloat, and Krofta Flocs D103, D104, and D105 Water quality parameters pH, unit Color, unit TSS, mg/L COD, mg/L BOD, mg/L

Influent 2.4 1125 140 760 548

First stage effluent 5.0 350 170 162.5 117

Second stage effluent 6.7 75 70 81 58

Combined FAE and FBE wastewater was prepared with 50% FAE and 50% FBE. Small volume of distilled water was used to adjust the influent COD to 760 mg/L before treatment b Coagulants used in the first stage flocculation and sedimentation treatment = 100 mg/L D103 and 100  mg/L D105. Sludge production by weight  =  1012  mg dry sludge per liter of wastewater = 35,343 kg/day. Sludge production by volume = 140 mL/1000 mL after 3 h of settling c Coagulants used in the second stage DAFF-Sandfloat treatment (flocculation, dissolved air flotation, and sand filtration) = 54 mg/L D103 and 34 mg/L D104. Sludge production by weight = 907 mg dry sludge per liter of wastewater = 28,835 kg/day. Sludge production by volume = 115 mL/1000 mL after 10 min of flotation. 30% pressurized recycle flow at 45 psig was used in DAF. Dilution factor by recycle flow was considered and corrected in effluent water quality determination a

wastewater = 14,751 kg/day; sludge production by volume = 90 mL/1000 mL after 10 min of flotation. 30% pressurized recycle flow at 45 psig was used in DAF. Dilution factor by recycle flow was considered and corrected in effluent water quality determinations. It is clear from the results in Table 1.3 that the effluent of the first-stage treatment by the existing facility will not meet the effluent standards because TSS, COD, and BOD were all higher than 100 mg/L. The effluent quality of the second stage treatment by dissolved air flotation and filtration (DAFF; Sandfloat) was excellent. Residual color, TSS, COD, and BOD were all below 100 unit or mg/L. Effluent pH was near neutral (7.5). The sludge production was estimated as follows: By Weight First Stage Second Stage Total By- Volume First Stage Second Stage Total

84,882 kg/day 14,751 kg/day 99,633 kg/day 130 CMD/1000 CMD 90 CMD/1000 CMD 220 CMD/1000 CMD

It should be noted that the small scale dissolved air flotation unit was controlled at only 45 psig of air dissolving tube (ADT) pressure, thus there was an insufficient amount of fine air bubbles to concentrate the floating sludge. In the actual full-scale DAFF Sandfloat unit, the ADT pressure can be as high as 85 psig; therefore, much more air can be dissolved to form fine bubbles in turn, much more compact floating sludge can be produced. In normal Sandfloat operation, the volumetric sludge production rate is always lower than 5%.

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1.2.3 Alternative Two Table 1.4 presents the results of two-stage sedimentation-DAF-filtration treatment using flocculants D103, D104, and D105. The experimental conditions of Alternative Two (Test 4) are documented here: (a) combined FAE and FBE wastewater was prepared with 50% FAE and 50% FBE; small volume of distilled water was used to adjust the influent COD to 760 mg/L before treatment; (b) coagulants used in the first stage flocculation and sedimentation treatment = 100 mg/L D103 and 100 mg/L D105; sludge production by weight  =  1012  mg dry sludge per liter of wastewater = 35,343 kg/day; sludge production by volume = 140 mL/1000 mL after 3 h of settling; and (c) coagulants used in the second stage DAFF-Sandfloat treatment (flocculation, dissolved air flotation, and sand filtration)  =  54  mg/L D103 and 34 mg/L D104; sludge production by weight = 907 mg dry sludge per liter of wastewater  =  28,835  kg/day; sludge production by volume  =  115  mL/1000  mL after 10 min of flotation. 30% pressurized recycle flow at 45 psig was used in DAF. Dilution factor by recycle flow was considered and corrected in effluent water quality determination. It can be seen that when different chemicals and lower dosages were applied, treatment results were still excellent. The effluent quality of the first stage treatment was unable to meet the effluent standards, but the effluent quality of the second stage treatment did meet the standards for ocean disposal. More technical information concerning ocean disposal of wastewater and sludge can be found from the literature [8]. It is concluded that the newly developed two-stage physical-chemical process system (Fig. 1.1) is, indeed, technically and economically feasible for treatment of combined FAE and FBE wastewater generated from the pulp mill. Further research by the mill personnel will be able to further reduce chemical requirements, in turn, to reduce the O&M costs.

1.3 Total Sludge Recycle System 1.3.1 General Concepts The general public as well as the responsible government officials, and industrial management sectors are becoming increasingly conscious of the need to safeguard our environment. The development and implementation of pollution control techniques to minimize industrial waste discharges have made significant gains in recent years. Further efforts for environmental quality improvements by achieving “zero” waste discharges are being suggested. It is recognized that a major difficulty in achieving a “zero” discharge objectives lies in the lack of satisfactory technologies for ultimate disposal of liquid and solid waste residuals accumulated from pollution abatement controls. Since any further treatment of such residuals will introduce an

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endless cycle of air, water, or land contaminants, recovery and recycle of waste treatment reagents would have to be implemented if “zero” waste discharge is to be achieved. One of the most important water and waste treatment processes in which relatively large quantities of chemical reagents are expended is coagulation-clarification (by sedimentation or flotation). The coagulations containing aluminum are generally accepted as the primary coagulants in a wide range of physical-chemical treatment practices. Calcium hydroxide, calcium oxide, magnesium hydroxide, or magnesium oxide are frequently used as neutralization agents. Effective recycle of coagulants and neutralization agents would represent a major step in achieving “zero” waste discharge objectives. This study is therefore directed toward evaluating potential chemical recovery and reuse techniques. Waste sludge from a physical-­ chemical treatment plant was selected as study materials in order to conduct an investigation showing some possible realistic industrial waste management applications.

1.3.2 Two-Stage Sludge Recycle System The two-state wastewater treatment system presented in Fig. 1.1 and Table 1.4 is used for illustration of the two-stage sludge recycle system. Both the two-stage wastewater treatment system and the two-stage sludge recycle system were developed by the Lenox Institute of Water Technology (LIWT) and Krofta Engineering Corporation (KEC). LIWT is a non-profit organization with a goal of developing and distributing scientific technologies for the benefit of entire mankind. Accordingly, anyone is welcome to freely use or further improve the Lenox technologies. In the first-stage wastewater treatment (WWT), the raw pulp mill wastewater is treated by flocculation and sedimentation. The settled sludge from the sedimentation tanks is defined as the “first-stage WWT-settled sludge”. In the second-stage wastewater treatment, the sedimentation effluent is further treated by Krofta DAFF-Sandfloat process. The floated sludge from Krofta DAFF-­ Sandfloat clarifier is defined as the “second-stage WWT-floated sludge”. 1.3.2.1 First-Stage WWT-Settled Sludge Recycle In the first-stage of the two-stage wastewater treatment system, 100 mg/L of coagulant D103 (sodium aluminate as Al2O3) was used for flocculation and 100 mg/L of D105 (calcium hydroxide) was used for neutralization. The first-stage WWT-settled sludge is generated from the first-stage WWT, and contains calcium and aluminum flocs, as well as separated organic pollutants. In any sludge recycle system, the diluted sludge must be thickened and dewatered before processing because of economical reasons. In our demonstration research, the first-stage WWT settled sludge was thickened by the existing gravity

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thickener and then dewatered by a vacuum filter. The solid content of the dewatered first-stage WWT-settled sludge was over 50%. Since the first-stage WWT-settled sludge’s organic content was high, the dewatered sludge was sent to a muffle furnace for heating and oxidation at over 550 °C. The relevant chemical reactions of the first-stage WWT-settled sludge treatment are as follows:

Ca  OH 2  CaO  H 2 O



2 A1  OH 3  A12 O3  3H 2 O



Organic Solids  CO2  H 2 O  others



The processed first-stage sludge containing mainly CaO and A12O3 was treated with concentrated sodium hydroxide for conversion of A12O3 to sodium aluminate, and conversion of CaO to calcium hydroxide:

A12 O3  2 NaOH  2 NaA1O2  H 2 O



CaO  H 2 O  Ca  OH 2



In this stage, the first-stage WWT-settled sludge had been converted to highly concentrated sodium aluminate and calcium hydroxide, which both were successfully used again for the first-stage wastewater treatment. 1.3.2.2 Second-Stage WWT-Floated Sludge Recycle In the second-stage of the two-stage wastewater treatment system, the sedimentation effluent (or the first-stage effluent) was successfully treated by 54  mg/L of D103 (sodium aluminate as A12O3) and 34  mg/L of D104 (aluminum sulfate as Al2O3). The DAFF-Sandfloat effluent (or the second stage effluent) met the effluent discharge standards on color, total suspended solids (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD), and pH. The effluent color shall be below 100 color units, and the TSS, COD, and BOD concentrations shall all be below 100 mg/L prior to ocean disposal. The floated sludge from the DAFF-Sandfloat clarifier was called the second-­ stage WWT-floated sludge which contained mainly aluminum hydroxide flocs and organic substances. In this LIWT demonstration research, the second-stage sludge was thickened by a Krofta electroflotation system [9] to about 3% of solids, then dewatered by a vacuum filtration to over 50% of solids. The dewatered second-stage WWT-floated sludge was also oxidized in a muffle furnace at over 550 °C for drying, oxidization, and purification of sludge in accordance with the following chemical reactions:

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2 Al  OH 3  Al 2 O3  3H 2 O



Organic Solids  CO2  H 2 O  others

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A portion of the processed second-stage dry sludge containing mainly aluminum oxide (or alumina) was treated by various acids for re-production of alum (aluminum sulfate, aluminum chloride, or aluminum nitrate, depending on the acid used):

Al 2 O3  3H 2 SO 4  Al 2  SO 4 3  3H 2 O



Al 2 O3  6HC1  2 AlCl3  3H 2 O



Al 2 O3  6HNO3  2 A1  NO3 3  3H 2 O





The remaining portion of the second-stage dry sludge was treated by various concentrated alkaline solutions for reproduction of aluminate (sodium aluminate, potassium aluminate, etc., depending on the alkaline solution used):

Al 2 O3  2 NaOH  2 NaA1O2  H 2 O



Al 2 O3  2KOH  2KA1O2  H 2 O

Finally, the recovered alum (aluminum sulfate, aluminum chloride, or aluminum nitrate) and aluminate (sodium aluminate, or potassium aluminate) were successfully reused in the second-stage (i.e. DAFF-Sandfloat) of the two-stage wastewater treatment system.

1.3.3 Sludge Recovery Experiments Using Actual Pulp Mill Sludge 1.3.3.1 First Stage WWT-Settled Sludge Recovery with Caustic Soda Twenty (20) mL of distilled water and 20 mL of 10-N sodium hydroxide solution were added into an alkaline reactor containing 3.7133  g of dried and ignited (at 550 °C) first-stage WWT-settled sludge. The mixture was heated to 80 °C in the alkaline reactor and mechanically mixed for 15 min. The final solution was sampled by a Millipore filtration technique for aluminum and iron analyses. The results are presented here: (a) the recovered aluminum = 295.2 g/kg; and (b) the recovered iron = trace amount. The insoluble calcium substances separated by the Millipore filtration technique were washed with distilled water thoroughly and solubilized with acid before

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calcium analysis by atomic absorption spectrophotometry. The results are presented here: the recovered calcium = 301.1 g/kg. 1.3.3.2 Second-Stage WWT-Floated Sludge Recovery with Caustic Soda Ten (10) mL of distilled water and 10 mL of 10 normal sodium hydroxide solution were added into an alkaline reactor containing 1.8888  g of dried and ignited (at 550 °C) second-stage WWT-floated sludge. The mixture was heated to 80 °C in the alkaline reactor and mechanically mixed for 15  min. The final solution was sampled for aluminum and iron analyses by atomic absorption spectrophotometry. The results are presented here: (a) the recovered aluminum = 380.5 g/kg; and (b) the recovered iron = trace amount. 1.3.3.3 Second-Stage WWT-Floated Sludge Recovery with Sulfuric Acid Fifteen (15) mL of distilled- water and 10 mL of concentrated sulfuric acid were added into an acid reactor containing 1.8459 g of dried and ignited (550 °C) second-­ stage WWT-floated sludge. The mixture was heated to 82 °C in the acid reactor and mechanically mixed for 15 min. The final solution was sampled for aluminum and iron analyses by atomic absorption spectrophotometry. The experimental results are presented here: (a) the recovered aluminum = 198.44 g/kg and (b) the recovered iron = 9 g/kg. It is encouraging to note that iron was also recovered and can be reused.

1.3.4 Supplemental Experiments Using Lenox Sludge Additional supplemental research was conducted using local alum sludge near the Lenox Institute of Water Technology (LIWT) to determine suitable acids, alkaline solution, reaction temperature, and detention time for aluminum recovery. The local alum sludge was collected from the Lenox Water Treatment Plant, Lenox, Massachusetts, USA [10], where a Krofta DAFF-Sandfloat Type 22 (diameter = 22 ft; depth = 6 ft; design flow capacity = 1.2 MGD) was installed for water purification using aluminum sulfate and sodium aluminate. The Lenox Water Treatment Plant is the first dissolved air flotation-filtration plant installed in America Continents, and has been successfully in operation since 1982 [11]. Specific supplemental experiments are reported below. Fifteen gallons of alum sludge (TSS = 1850 mg/L) was collected from the Lenox Water Treatment Plant. The Lenox sludge was concentrated by means of gravity thickening. The concentrated sludges (TSS = 1.0564% and TSS = 1.9452%) were then used for alum sludge recovery tests under acids and alkaline conditions.

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Table 1.5  Alum sludge recovery with sulfuric acid Test #ooo. 1 2 3 4

TSS mg/L 10,564 10,564 19,452 19,452

mL sludge + mL conc. H2SO4 100 + 2.5 100 + 2.5 100 + 2.5 100 + 2.5

Reaction temp °C 50–60 50–60 50–60 50–60

Reaction time min. 15 240 15 240

Recovered Al mg/L 3792.5 4407.5 6765 7175

pH units 0.3 0.3 0.67 0.67

Reaction time min. 15 15 240 15 240

Recovered Al mg/L 3488 2943 4796 7085 7194

pH units 13.5 13.5 13.5 13.5 13.5

Table 1.6  Alum sludge recovery with sodium hydroxide Test #ooo. 5 6 7 8 9

TSS mg/L 10,564 10,564 10,564 19,452 19,452

mL sludge + mL 10-N NaOH 100 + 9 100 + 9 100 + 9 100 + 9 100 + 9

Reaction temp °C 50 32 50 50 50

The results of the supplemental experiments are documented in Tables 1.5 and 1.6. Both tables are self explanatory. It was observed that increasing the reaction time from 15 min to 4 h did increase the recovered aluminum in both acid reactor (Table  1.5) and alkaline reactor (Table  1.6). The optimum reaction time shall be chosen based on the facility costs and the recovered aluminum values. The effect of initial sludge concentrations (10,564 mg/L versus 19,452 mg/L, for example) on the recovered aluminum concentration is also significant. It appears that the higher the initial sludge concentration, the higher the recovered aluminum concentration. The recovered aluminum concentration will affect the sizing of the chemical feed pumps. Increasing the reaction temperature from 32 to 50 °C also increased the aluminum recovery in the alkaline reactor (Table 1.6) when the initial sludge concentration was 10,564 mg/L.

1.3.5 Summary The mixture of alum and lime sludges comes from the first-stage sedimentation basins. The alum/lime sludges can be recovered in an alkaline reactor. The recovered chemicals are sodium aluminate and calcium hydroxide. The major source of alum sludge will come from the WWT-floated sludges of the second-stage Krofta Sandfloat clarifier. In the second stage, part of the concentrated and processed raw alum sludge can be converted to aluminum sulfate by the addition of sulfuric acid in an acid reactor, and the remaining part of sludge can be converted to aluminate by adding caustic soda in an alkaline reactor. Each reactor

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consists of a mixing chamber and a solids separation chamber. The residual sludges are mainly inert materials which can be separated in the solids separation chambers. The two supernatants containing high concentrations of recovered aluminum coagulants can then be withdrawn for reuse either separately or combined at any desired ratio. Recycling both aluminum sulfate and sodium aluminate (or the like), at appropriate ratios, to the intake system for reuse would eliminate the additional pH adjustment requirement. This is due to the fact that the pH of the acid reactor effluent must be extremely low, and the pH of the alkaline reactor effluent must be extremely high. The optimum pH for alum coagulation, however, is about 6.3. It has been known that the existing pulp mill has its own lime recycle system. If the pulp mill decides to use lime, alum, and sodium aluminate for wastewater treatment, the lime sludge generated in the first stage WWT and the alum sludge generated in the second stage WWT can be recycled for reuse. The daily chemical treatment costs can be significantly reduced if the newly developed Two-Stage Sludge Recycle System can be adopted for full-scale operation.

1.3.6 Economics The purpose of sludge recovery is to solve a sludge disposal problem. Coagulant recovery offers added economic benefits. These benefits include less coagulation chemical cost, less neutralization chemical cost, and smaller amounts of inert solids for ultimate disposal. Most of the chemical cost saving involves the acid and caustic soda (or equivalent). The design engineer can be assured that there will always be a cost difference between processing chemicals (such as sulfuric acid, hydrochloric acid, nitric acid, etc.; or sodium hydroxide, potassium hydroxide, etc.) and between product chemicals (such as aluminum sulfate or sodium aluminate). There will be a big cost difference between caustic soda and sodium aluminate, because the former is the raw chemical and the latter is the product. White et al. [12] reported the annual operating costs from Study of Raw Water No. 3 where alum recovery was practiced. Raw Water No. 3 might be considered the typical raw water source with no unusual problems, so the economics are typical of what is to be expected. Annual costs include coagulation and stabilization chemicals, dewatering costs on a stationary horizontal vacuum bed, and hauling and disposal of the residue. Their annual costs showed a saving in favor of coagulant recovery of $48,350.00/year (1984 costs), representing some 20% coagulant cost saving if chemical sludge recovery is practiced. White et al. [12] also presented an excerpt of a bonded bid to design, construct, and operate a plant treating Water No. 4. A coagulant recovery system was bid against contract hauling and disposal of several years’ sludge accumulated in a large lagoon. Their cost comparison was calculated at a conservative annual inflation of 4% to show a cumulative saving of $20,079,000 in 20 years in favor of coagulant

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recovery. The annual saving of the 20th year was $1,928,000 (1984 cost data). For conversion of the 1984 cost data to the recent 2022 cost data, the readers can use a cost index table of the US Army Corps of Engineers [13]. Coagulant recovery systems are economically worthy of the design engineer’s consideration. Such systems can be properly designed and safely operated. With the extreme variability from one raw water or wastewater to another, it is highly recommended that pilot testing be undertaken before such a design is attempted. The readers are referred to the literature for more technical information on chemical coagulation, precipitation, flocculation, sedimentation, flotation, filtration, vacuum filtration, sludge thickening, etc [14–16].

Glossary [17–21] Clarification  It is a solid-water separation process unit such as (a) sedimentation clarification for settling the solids that have their specific gravity greater than one (heavier than water) or (b) flotation clarification for floating the solids that have their specific gravity less than one (lighter than water). Sometimes, membrane filtration is also considered to be a clarification process in case of the membrane bioreactor process. Primary clarification  It can be either primary sedimentation clarification, or primary flotation clarification to be used for treatment of preliminary effluent (i.e. raw wastewater just going through a preliminary wastewater unit). Primary flotation clarification  It is a flotation process to be used in a primary waste treatment stage for removal of mainly floatable total suspended solids, such as oil and grease (O&G), and floc-bubble (s.g. or specific gravity less than one) from wastewater. Partially, COD, BOD, heavy metals, and nutrients are also removed by primary flotation clarification. The flotation process can be either dissolved air flotation or induced air flotation (dispersed air flotation). Primary sedimentation clarification  It is a sedimentation process to be used in a primary waste treatment stage for removal of mainly settleable total suspended solids (s.g.or specific gravity greater than one) from wastewater. Partially, COD, BOD, heavy metals, and nutrients are also removed by primary sedimentation clarification. Primary waste treatment facility or plant  It is a wastewater treatment facility or plant consisting of mainly (a) preliminary treatment process units (such as bar screening, fine screening, comminution, grit chamber, equalization, neutralization, pre-aeration, etc.); (b) primary treatment process units (such as chemical feeding, mixing, coagulation/precipitation, primary clarification, etc.); and (c) sludge handling and treatment process units (such as sludge thickening, vacuum filtration, etc.). A primary waste treatment facility or plant removes from the wastewater those pollutants that will either settle out or float. Primary wastewater treatment  It is a wastewater treatment step or stage involving the use of either primary sedimentation clarification or primary flotation

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clarification for removal of mainly total suspended solids (TSS), and oil and grease (O&G), and partially chemical oxygen demand (COD), biochemical oxygen demand (BOD), and nutrients from influent wastewater. Secondary flotation clarification  It is a flotation process after a primary clarification and a bioreactor (or a physicochemical reactor) to be used in a secondary waste treatment stage for removal of mainly total suspended solids (s.g. less than one  due to air entrapment) from bioreactor effluent (or physicochemical reactor effluent). In case the bioreactor is an aeration basin of activated sludge process system, the TSS will be the mixed liquor suspended solids (MLSS) in the bioreactor effluent. In case a physicochemical reactor is to be used instead of a bioreactor, the TSS to be separated by secondary flotation clarification will be chemical flocs in combination with air bubbles. Secondary sedimentation clarification  It is a sedimentation process after a primary clarification and a bioreactor (or a physicochemical reactor) to be used in a secondary waste treatment stage for removal of mainly settleable total suspended solids (s.g. greater than one) from bioreactor effluent (or physicochemical reactor effluent). Secondary wastewater treatment It is a wastewater treatment step or stage involving the use of either biological reactors and/or physicochemical reactors for removal of mainly dissolved organic solids and some nutrients (such as phosphate and ammonia nitrogen) from the effluent of primary treatment. Additional secondary clarification (secondary sedimentation clarification, or secondary flotation clarification, or membrane filtration) is used for (a) separation of the sludge (biological sludge from the bioreactors, or chemical sludge from ­physicochemical reactors); (b) recycle of a portion of the sludge to bioreactors or physicochemical reactors; (c) discharge of the separated sludge to a sludge thickener, a sludge dewatering unit, or a sludge digester, or a storage lagoon; (d) discharge of the clarified secondary effluent to a tertiary treatment process unit or a receiving water after disinfection. Secondary wastewater treatment facility or plant  It is a complete wastewater plant including the treatment steps (or stages) of preliminary wastewater treatment, primary wastewater treatment, secondary wastewater treatment, disinfection, sludge thickening, sludge dewatering, sludge digestion, and ultimate sludge disposal.

References 1. Wang, L. K., Wang, M. H. S., Shammas, N. K., & Holtorff, M. S. (2021). Independent physicochemical wastewater treatment system consisting of primary flotation clarification, secondary flotation clarification and tertiary treatment. In L. K. Wang, M. H. S. Wang, N. K. Shammas, & D. B. Aulenbach (Eds.), Environmental flotation engineering (pp. 189–228). Springer Nature Switzerland. 2. Wang, L.  K., Wang, M.  H. S., & Fahey, E.  M. (2021). Innovative dissolved air flotation potable water filtration plant in Lee, Massachusetts, USA.  In L.  K. Wang, M.  H. S.  Wang,

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N. K. Shammas, & D. B. Aulenbach (Eds.), Environmental flotation engineering (pp. 73–94). Springer Nature Switzerland. 3. Wong, J. M., Hess, R. J., & Wang, L. K. (2021). Operation and performance of the AquaDAF process system for water purification. In L.  K. Wang, M.  H. S.  Wang, N.  K. Shammas, & D. B. Aulenbach (Eds.), Environmental flotation engineering (pp. 301–342). Springer Nature Switzerland. 4. Wong, J. M., Farmerie, J. E., & Wang, L. K. (2021). Operation and performance of the Clari-­ DAF process system for water purification. In L. K. Wang, M. H. S. Wang, N. K. Shammas, & D. B. Aulenbach (Eds.), Environmental flotation engineering (pp. 343–370). Springer Nature Switzerland. 5. Wang, L. K., & Wang, M. H. S. (2023). Removing high color of humic substances or neutralizing acidity of acid rain by flotation-filtration water treatment system. In L.  K. Wang, M. H. S. Wang, & Y. I. Pankivskyi (Eds.), Environmental science, technology, engineering, and mathematics (STEM) (Vol. 2023, Number 1A, p. 39). Lenox Institute Press. https://doi. org/10.17613/0zx4-­3946 6. Wang, L. K., & Wang, M. H. S. (2021). A new wave of flotation technology advancement for wastewater treatment. In L. K. Wang, M. H. S. Wang, N. K. Shammas, & D. B. Aulenbach (Eds.), Environmental flotation engineering (pp. 143–166). Springer Nature Switzerland. 7. Pankivskyi, Y.  I., & Wang, L.  K. (2021). Innovative wastewater treatment using activated sludge and flotation clarification under cold weather conditions. In L. K. Wang, M. H. S. Wang, N. K. Shammas, & D. B. Aulenbach (Eds.), Environmental flotation engineering (pp. 229–300). Springer Nature Switzerland. 8. Tay, K. L., Osborne, J., & Wang, L. K. (2008). Ocean disposal technology and assessment. In L. K. Wang, N. K. Shammas, & Y. T. Hung (Eds.), Biosolids engineering and management (pp. 443–478). Humana Press. 9. Wang, L.  K. (2021). Humanitarian engineering education of the Lenox Institute of Water Technology and its new potable water flotation processes. In L.  K. Wang, M.  H. S.  Wang, N. K. Shammas, & D. B. Aulenbach (Eds.), Environmental flotation engineering (pp. 1–72). Springer Nature Switzerland. 10. Krofta, M., & Wang, L.  K. (1985). Application of dissolved air flotation to the Lenox, Massachusetts water supply: Water purification by flotation. Journal New England Water Works Association, 99(3), 249–264. 11. Krofta, M., & Wang, L.  K. (1985). Application of dissolved air flotation to the Lenox, Massachusetts water supply: Sludge thickening by flotation and lagoon. Journal New England Water Works Association, 99(3), 265–284. 12. White, A. R., et al. (1984, May 18). Alum recovery, an aid to the disposal of water plant solids. Technical paper presented at the 1984 Spring Convention of the American Society of Civil Engineers, Atlanta, Georgia, USA. 13. Wang, L. K., Wang, M. H. S., & Shammas, N. K. (2022). Innovative PACT activated sludge, CAPTOR activated sludge, activated bio-filter, vertical loop reactor and PhoStrip processes. In L. K. Wang, M. H. S. Wang, & Y. T. Hung (Eds.), Waste treatment in the biotechnology, agricultural and food industries , volume 1 (pp. 241–275). Springer Nature Switzerland. 14. Wang, L.  K., Wang, M.  H. S., Shammas, N.  K., & Hahn, H.  H. (2021). Physicochemical treatment consisting of chemical coagulation, precipitation, sedimentation and flotation. In L.  K. Wang, M.  H. S.  Wang, & Y.  T. Hung (Eds.), Integrated natural resources research (pp. 265–398). Springer Nature Switzerland. 15. Wang, L. K., Shammas, N. K., Selke, W. A., & Aulenbach, D. B. (2010). Flotation technology. Humana Press, 680 pages. 16. Shammas, N.  K., & Wang, L.  K. (2016). Water engineering: Hydraulics, distribution, and treatment. Wiley, 806 pages. 17. Wang, L. K. (1974). Environmental engineering glossary. Calspan Corporation, 439 pages. 18. Wang, L. K., & Wang, M. H. S. (2015). Environmental engineering glossary (2nd ed.). Lenox Institute Press.

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19. Wang, M.  H. S., & Wang, L.  K. (2015). Environmental water engineering glossary. In C. T. Wang & L. K. Wang (Eds.), Advances in water resources engineering (pp. 471–556). Springer Nature Switzerland.  20. Wang, L. K., & Wang, M. H. S. (2023). Application of secondary flotation for improvement of conventional activated sludge process system. In L. K. Wang, M. H. S. Wang, & Y. I. Pankivskyi (Eds.), Environmental science, technology, engineering, and mathematics (STEM) (Vol. 2023, Number 3A). Lenox Institute Press, 80 pages. https://doi.org/10.17613/jwrp-­0e11 21. Pankivskyi, Y. I., & Oshurkevych-Pankivska, O. Y. (2023). Water supply and sewerage systems. In L. K. Wang, M. H. S. Wang, & Y. I. Pankivskyi (Series Eds.), Environmental science, technology, engineering, and mathematics (STEM). Lenox Institute Press, 261 pages. https:// doi.org/10.17613/x5qn-­d460

Chapter 2

Management of Various Sources of Hazardous Waste Nor Azalina Rosli, Hamidi Abdul Aziz, Leonard Lim Lik Pueh, Inawati Binti Othman, Mohd Hafiz Zawawi, and Yung-Tse Hung

Nomenclature RCRA HSC CCR UNEP HHW EPA CRT CFR CCP EQA DoE PCB

Resource Conservation Recovery Act Health and Safety Code California Code of Regulation United Nations Environment Program Household Hazardous Waste Environmental Protection Agency Cathode Ray Tubes Code of Federal Regulations Commercial Chemical Product Environmental Quality Act Department of Environment Polychlorinated biphenyls

N. A. Rosli (*) · L. L. L. Pueh · I. B. Othman Department of Civil Engineering, Unimas Water Centre, Universiti Malaysia Sarawak, Sarawak, Malaysia e-mail: [email protected]; [email protected]; [email protected]; [email protected] H. A. Aziz Environmental Engineering, School of Civil Engineering, Solid Waste Management Cluster, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia e-mail: [email protected] M. H. Zawawi Department of Civil Engineering, Engineering, Universiti Tenaga Nasional, Kajang, Selangor, Malaysia e-mail: [email protected] Y.-T. Hung Department of Civil and Environmental Engineering, Cleveland State University, Strongsville, OH, USA e-mail: [email protected]; [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 L. K. Wang et al. (eds.), Waste Treatment in the Biotechnology, Agricultural and Food Industries, Handbook of Environmental Engineering 27, https://doi.org/10.1007/978-3-031-44768-6_2

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PCT Polychlorinated triphenyl SW Scheduled Waste WFD Waste Framework Directive WtE Waste to Energy EPR Extended Producer Responsibility TWIR Toxic Industrial Waste Regulation TDI Toluene di-isocyanate MDI Methylene di-isocyanate TEL Tetraethyllead TML Tetramethyl lead PVC Polyvinyl Chloride PCD Pollution Control Department PPP Polluter Pay Principle MWEP Ministry of Water and Environmental Protection EPI Environmental Protection Inspectorate

2.1 Definition of Hazardous Waste Hazardous wastes are typically identified based on the potential threat they pose if exposed to the environment. As it was primarily produced by industry, it is sometimes referred to as industrial waste in some countries. Previously, the wastes that we know as “hazardous” were referred to by such terms as special industrial waste or chemical waste, which is still the often case in Europe. Regulations were developed to establish legal definitions for hazardous wastes in order to facilitate the management of hazardous wastes by industries, which typically target major industries in respective countries due to significant generation rates. Developing a legal definition of what is and what is not hazardous waste can take considerable effort with much disagreement. European Waste Catalogue (EWC) illustrates the fundamental concept of hazardous waste comprising three aspects, namely, waste, waste components, and waste properties (Fig. 2.1). Examples of hazardous waste properties include corrosivity, toxicity, flammability, reactivity, and any other prescribed properties. If a waste component possesses one or more of the specified properties, the waste will be identified as hazardous waste. Different countries define hazardous waste in different ways, as summarized in Table 2.1, with the similarities being in the properties that the waste carries that can endanger human health and the environment. The list of hazardous wastes is primarily intended to aid generators in identifying hazardous waste. The list may vary from country to country, as categorization can be based on waste properties, waste components, waste source or activities, and waste volume. Most Asian countries that have ratified the Basel Convention have national legislation that follows the convention’s definition, which states that hazardous waste is defined as falling into one of the waste categories listed in Annex 1 of the Convention and exhibiting one of the hazardous characteristics such as being explosive, flammable, toxic, or corrosive [2].

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Fig. 2.1  Concept of hazardous waste in European Waste Catalogue, EWC [1]

The extent of risk or threat that hazardous waste poses to the environment varies depending on the waste’s quantity, concentration, and management. In general, a hazardous waste generator is scaled as very small, small, or large based on the amount of waste generated per month: 1 MPa). Biomass is placed within the pyrolysis chamber, which applies a flash fire from the bottom up while maintaining a downward airflow. In this situation, the biomass is transformed into gaseous fuel, leaving the carbon as biochar [14]. Another method for making biochar is called microwave pyrolysis, which involves heating the biomass with intense radiations produced from a microwave source. It has several benefits, including a speedy heating process beginning and ending, noncontact heating, higher heating rate, and so on [15]. Another thermochemical conversion technique for producing biochar from different biomasses heated in confined environments at low pressure and temperatures between 200 and 300 °C is hydrothermal carbonization. Wet pyrolysis is the process term, and the resulting biochar is known as hydrochar [16]. The eco-friendly mechanochemical technique uses a high-energy ball mill to create biochar at the nanoscale. In this process, the ball mill and milling media are used to break down the cellulosic-type organic molecules into minute particles that are then collected as biochar [17]. Torrefaction is the conversion of biomass carbon-rich material under temperatures ranging from 200 to 300 °C. The products of torrefaction are used as biofuel. Torrefaction can be classified into three major classes according to the procedure: dry torrefaction, wet torrefaction, and steam torrefaction. In non-oxidative dry torrefaction, nitrogen and carbon dioxide are used as carrier gas. Similarly, air, flue gas, or any other gas having oxygen is known as oxidative dry torrefaction. In wet torrefaction, a wet medium is used to carbonize the biomass instead of dry. Water and diluted acids are used as torrefaction medium under a reaction temperature between 180 and 260 °C with reaction time ranging from 5 to 240 min. Torrefaction of the biomass in the explosion of high-pressure steam and high temperature is known as steam torrefaction [18].

6.2.3 Biochar Properties The physical and chemical qualities of biochar determine how well it can remove pollutants, and these properties may be controlled by adjusting the feedstock, manufacturing process, production parameters, and activation techniques. The physical and chemical characteristics of several types of biochar are listed in Table 6.1 and described in the following section. 6.2.3.1 Physical Properties Density and porosity are examples of physical qualities. The biochar’s mobility in the environment, interaction with the soil’s hydrologic cycle, and usefulness as a natural home for tiny soil bacteria will all depend on its density and porosity.

Pyrolysis

Pyrolysis

Hydrothermal method

Tube pyrolysis Heating rate(10 °C/ min) temp (300, 500, and 700 °C) time (2 h)

Potato stems and leaves

Municipal solid waste

Phragmites australis

Grape pomace

Heating rate(25 °C/ min) temp (500 °C) time (2.5 h) Heating rate(20 °C/ min) temp (500 °C) time (6 h) Heating rate(15 °C/ min) temp (450 °C) time (30 min) Temp (280 °C) time (30 min)

Production parameters Particle size (2.5 mm), temp (350–550 °C) Particle size (2.5 mm), temp (350–550 °C) Heating rate(10 °C/ min) temp(500 °C) Time(4 h)

Pyrolysis

Tube furnace pyrolysis

Pyrolysis

Production method Pyrolysis

Rabbit manure

Biochar feedstock Sugarcane (Saccharum officinarum) Neem (Azadirachta indica), Sewage sludge

Irregular shape, microspheres of different sizes Porous morphology

1.03 m2/g 3.35 m2/g 4.10 m2/g

22.385 m2/g

–

–

1.39 × 101 Å –NH3 and –COOH groups

3.59 m2/g

The irregular structures and numerous pores

>50 nm

30.995 m2/g

3.12 nm

3.13 × 101 Å

43.9 m2 g−1

[34]

[33]

References [32]

[36]

(continued)

[37] Hydroxyl, ether groups, carbonyl and carboxyl groups Carboxylic acid and [38] alcohol

O–H group

Carboxylic acid and [35] alcohols,

Carboxyl and ester and

Pore size/ volume Functional groups 2.57 × 101 Å

Surface area 2.29 m2 g−1

Smooth and porous on the 14.90 surface m2/g

Heterogeneous surface, different particle sizes, irregular surface morphology High C and lower H, O, and N content

Characterization

Table 6.1  Summary of biochar feedstock, production methods, and properties

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Temp (500 °C) Time (1 h)

Temp (800 °C) Time (30 min)

Hydrothermal

Microwave

Douglas fir biochar Oakwood char Pine bark char Waste cork

Saw dust

Plum kernels

Biosolids from the Microwave wastewater treatment plant

Temp (180 °C) Time (10 h)

Production parameters Heating rate(20 °C/ min) temp (300,700 °C) time (4 h) Fast pyrolysis Temp (900–1000 °C) time (1–10 s) Fast pyrolysis Temp (400 °C) Fast pyrolysis Temp (400 °C) Slow pyrolysis Temp (750 °C)

Production Biochar feedstock method Wheat straw Pyrolysis

Table 6.1 (continued)

Well-developed porous surface

Well-developed porous surface

Amorphous nature

Microporous surface texture with small canals Microporous surface Microporous surface –

Characterization Porous morphology

150.85 m2/g

601.9 m2/g

91.8 m2/g

0.730 (cm3/g) – 1.060 (cm3/g) – 0.238 (cm3/g) Hydroxyl carboxyl, groups Methyl 0.326 cm3/g Carboxyl and aliphatic amine group 0.26 cm3/ g Carboxylic, anhydrides, lactones, and phenols 0.182 cm3/g –

2.0 m2/g 1.0 m2/g 392.5 m2/g

–

[45]

[44]

[43]

[42]

[41]

[40]

Functional groups References Carboxylates, [39] ketones, and steroids

13.65 (Å)

Pore size/ volume –

745.0 m2/g

Surface area –

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However, the origin of the biomass, the pretreatment, and the circumstances of biochar formation have a significant impact on density and porosity. A pycnometer technique is used to calculate the mass of the biochar particles. The most popular and efficient method of enhancing biochar density and porosity, particularly in chemical synthesis, is activation [19]. The quantity of negatively and positively charged groups on the surface of the biochar and its porosity are the key determinants of its adsorption capability. The pretreatment stage’s torrefaction has little impact on the porosity of the activated carbon. Another typical method to enhance biochar porosity is hydrothermal treatment or oxygenation. The release of gas during the carbonization process alters the porosity of the biomass, which in turn affects its surface area [20]. Biochar exhibits a large specific surface area and a high cation exchange capacity. It is reported that, with increasing temperature, the specific surface area of biochar increases, and the physical or chemical modification of biochar further promotes the growth of the specific surface area [21]. The biochar pores range in size from micropores (0.001–0.05 m) and medium pores (0.002–0.05 m) to macropores (0.05–1000 m), spanning several orders of magnitude. Micropores constitute the biochar structure, and they get better as the pyrolysis temperature rises. According to reports, the micropores in charcoal made from safflower cakes at temperatures between 400 and 600  °C and charcoal at 450 and 550 °C, respectively, might occupy more than 80% of the total pore volume or more than 80% of the surface area. Similarly, it was discovered that less than 10% of the micropores in untreated agricultural waste (such as straw and stover) were present. The temperature of pyrolysis is negatively correlated with particle size. Long residence durations and moderate heating rates result in bigger biochar particles, whereas high heating temperatures generate smaller biochar particles [22]. Mechanical stability is biochar’s mechanical strength, primarily determined by density. The mechanical stability of the biochar is impacted by its density when chemicals are released, or water evaporates during the heating process. As a result, only raw feedstocks with high lignin and density content may be used to produce biochar with high compressive strength. Biomass orientation, nanocomposite characteristics, and moisture content can also impact the mechanical strength of biochar because these factors are mostly untouched by the pyrolysis process [23]. According to studies, the stability of biochar is greatly impacted by changes in the oxygen–carbon (O/C) and hydrogen–carbon (H/C) ratios as well as the loss of hydrophilic oxygen-containing functional groups on the surface of biochar when the temperature rises [24]. 6.2.3.2 Chemical Properties Chemical properties include the elemental composition of biochar. Biochar consists of both non-volatile compounds (e.g., aromatic substances) and volatile compounds (e.g., aliphatic substances), which have a high carbon and low oxygen content, and aliphatic substances are more affected by increasing production temperature [25]. The biochar’s hydroxide content is reduced, while its carbon concentration rises

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significantly during the synthesis process. The significant adjustments happened in the 200–400 °C production temperature range. Biochar produced at high temperatures has a carbon concentration that can exceed 95% and an oxygen level that is less than 5%. The hydrogen content of wood fluctuates from 5% to 7% and drops to less than 2% or even less than 1% in some situations after pyrolysis over 700 °C. Biochar has lower hydrogen–carbon and oxygen–carbon ratios when produced at higher pyrolysis temperatures [26]. The pH of the biomass material typically ranges from 5 to 7.5. The pH of the biochar ultimately rises as a result of the acidic functional groups, such as carboxyl, hydroxyl, or carbonyl groups, escaping from the biomass during pyrolysis. One of the most important factors influencing the pH of biochar is temperature. The breakdown and fracturing of weak links (such as hydroxyl bonds) in the biochar structure at high temperatures is the primary cause of the pH increase [27]. Similarly, the loss of biomass volatiles during carbonization, the rise in CEC (due to the presence of exchangeable ions on the biochar surface), and the increase in sufficient nutrients may all be factors in the increase in biochar electrical conductivity (EC) with rising temperature [28].

6.2.4 Factors Affecting Biochar Properties Production factors have significant effects on biochar properties. During the pyrolysis process, the reaction conditions are mainly responsible for producing biochar. Factors such as feedstocks, temperature, heating rate, particle size, and so on influence biochar properties [29]. These factors directly affect the yield of biochar and its quality. It is crucial to have a thorough understanding of the qualities of biochar in order to decide on the application. The preparation of biochar depends heavily on temperature as many of its features, including pore structure, surface characteristics, and nutrient content, are temperature-dependent. While the volatile components of biochar tend to decrease as pyrolysis temperature and retention time rise, the ash content of biochar often rises with these parameters. Between 300 and 500 °C, relative elementary material displayed a fast loss of O and H. The decreasing amount of O and H from the char causes the breakdown of organic components as the pyrolysis temperature rises. Biochar’s carbonized percentage and surface area may be increased through pyrolysis at high temperatures, increasing its ability for adsorption [30]. It is observed that biochar pyrolyzed at 300–350 °C has a specific surface area of 120 min

Spherical Short 60 min

Continuous Short 70–85 min

Double

Tilting Short 60– 80 min High 40– 45 psi Triple

Pressure

High 40 psi

High 30–40 psi

High 45 psi

Numbers of pressure peak cycles Steam consumption

Triple

Triple

High 360–400 kg/MT FFB

Moderate 305–355 kg/MT FFB

Low 220–250 kg/MT FFB No

Low 200 kg/MT FFB No

Moderate 300–360 kg/ MT FFB

Presence of cage

Yes

No

Atmospheric

Single

No

temperatures (80–90 °C) [19, 33]. Following clarification, high pressure and high temperature simultaneously ruptured the oil-bearing cells of the mesocarp, separating the mesocarp from the nuts and directing the mesocarp to a mechanical twin screw-press machine for CPO extraction [32].

7.3.5 Depericarping After being pressed using a screw press, a cake containing moisture, greasy fibre, and nuts is generated [33]. The materials are then sent to a depericarper for the segregation of fibre and nut. During depericarping, the nuts were extracted through the digesting and pressing operations for depericarp, and then the leftover fibres were sent to the nut-breaking machine or plant [32]. A hydrocyclone and clay bats were then used to separate the combination of cracked kernels and shells. The resulting fibre is then sent to the boiler house to be used as fuel.

7.3.6 Clarification of CPO Ahmed et  al. [33] reported that the digested CPO comprises 35–45% palm oil, 45–55% water, and the remaining fibrous components. It is pumped into a clarification tank to separate the oil from the CPO, and the temperature is maintained at 90 °C in order to enhance the oil separation. After the oil has been separated, it is continuously skimmed from the top of the tank. The remaining leftover oil from the bottom phase of the clarification tank was recycled through the sludge separator once more. The recovered oil is reintroduced to the clarification tank. The substance is next processed in a high-speed centrifuge and a vacuum dryer. Finally, it is delivered to the storage tanks. The opposite flow, which consists of water and fibrous

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material, is discharged as sludge waste. Sludge, a by-product of the clarification and purification processes, is the most significant contributor to POME in terms of both the intensity and the volume of pollution it causes [32]. Approximately 1.5 tonnes of sludge waste is produced for every tonne of CPO processed.

7.3.7 Kernel Separation and Drying In this procedure, the nut from the depericarping procedure will be sorted by winnowing and hydrocyclone [19]. Specific gravity (SG) differences will be used to separate palm kernels from their shell [33]. The kernel will be dried in silos, and the remaining effluent will be discharged. The shell waste was heaped in the boiler with the mesocarp fibres to produce energy [32].

7.3.8 Waste Oil palm processing mills produce several waste products, including empty fruit bunch (EFB), palm kernel shell (PKS), mesocarp fibre (MF), and palm oil mill effluent (POME) [6, 43, 44]. Typically, FFB is made up of palm oil, palm kernel, EFB, PKS, MF, and POME, and their weight percentages on a wet basis are shown in Fig. 7.3 [45]. According to the percentage composition, as shown in Fig. 7.3, the 95.38 million tonnes of FFB harvested in 2014 would have resulted in the production of 7.34 million tonnes of EFB, 4.46 million tonnes of PKS, and 7.72 million tonnes of MF dry weight basis from the biomass produced at the mill [46]. In 2014, almost 70.21 million tonnes of solid biomass were produced from oil palms; however, only 44.82 million tonnes were suitable for processing into value-added products; the remaining nearly 25.39 million tonnes were left to rot in the plantations [5]. Fig. 7.3  Component of FFB [45]

Palm oil 21%

POME 28%

EFB 23%

MF 15%

PK 7%

PKS 6%

Palm oil

EFB

PK

PKS

MF

POME

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Compared with Thailand, Malaysia has diverse palm varieties, growth conditions, and plantation management, which will lead to a distinction in solid waste [19]. The milling process in Thailand requires a greater quantity of water, resulting in a greater quantity of effluent output. Indirectly, the amount of waste generated will expand in tandem with the enormous palm oil production. Prasertsan and Prasertsan [47] reported that palm oil production by itself can generate more than 70% of waste. According to Pleanjai et al. [48], the fibre, shell, decanter cake, and EFB all make up 30%, 6%, 3%, and 28.3% of FFB, respectively. The chemical composition of EFB has been reported to consist of 42% carbon, 0.8% nitrogen, 0.006% potassium, 2.4% sodium, and 0.2% magnesium [49]. Without proper treatment, palm oil mill effluent (POME) can have devastating effects on the natural environment [50, 51]. In 2004, Malaysia produced around 30 million tonnes of POME and approximately 26.7 million tonnes of solid biomass [52]. Despite the existence of a modern ponding system to treat POME through a succession of anaerobic or aerobic ponds, these wastes, particularly POME, do not meet the specifications given by the Department of Environment (Malaysia), rendering the conventional technique of effluent treatment ineffective. This phenomenon is unquestionably destabilizing the aquatic ecology and, hence, jeopardizing its inhabitants. According to Abdullah and Sulaiman [14], the fundamentals of waste management include waste reduction and recycling, energy recovery, and waste disposal. Palm press fibre (PPF), EFB, and shell are all used as fuel in waste-fuel boilers to produce steam for processing and power generation with steam turbines, making the palm oil sector completely self-sufficient in energy. The palm oil industry in Thailand generates 0.87 m3/tonne FFB of specific wastewater, while Malaysia generates 0.6 m3/tonne FFB [53]. About 2.5 tonnes of POME, 0.9 tonnes of EFB, 0.6 tonnes of MF, and 0.27 tonnes of shells are released in Indonesia for every tonne of crude palm oil (CPO), as stated by Irvan [54]. Indonesia also generated 77.5 million tonnes of POME, 27.1 tonnes of EFB, 18.6 tonnes of MF, and 8.4 million tonnes of shells in 2015, in addition to 31 million tonnes of CPO. It is a massive amount of waste, and if it is not properly disposed of, it will pose a significant environmental threat. POME comprises 0.6–0.7% palm oil, 95–96% water, 4–5% solids total, and 2–4% suspended solids. Lagoon or pond systems (anaerobic, facultative, and aerobic) are the current approach for treating POME in palm oil mills. Before being discharged into the river, this treatment is intended to reduce the BOD, COD, and pH levels of the effluent. While this technique does successfully lower the quality of wastewater to 95%, it takes a very long time to accomplish. The disadvantages include a lengthy startup time (55–100 days), requiring a bigger area, and the emission of greenhouse gases (GHG) such as methane and carbon dioxide [54]. According to Kerdsuwan and Krongkaew [55], 100 tonnes of FFB processed in oil palm mills can yield between 20 and 22.5 tonnes of EFB.  It is projected that Indonesia generates 90.5 million metric tonnes of FFB annually, with a corresponding EFB waste of roughly 20.8 million metric tonnes [56]. Due to its high cellulose content, EFB can be easily broken down by a variety of chemical, physical, and biological methods [57]. The EFB was incinerated before 1996. Because it contains a high concentration of

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potassium (around 30%), EFB ash can be used as a fertilizer. However, the Minister of the Environment’s Decree No. 15 of 1996 on the blue-sky program forbids the combustion of EFB in an effort to reduce air pollution. The majority of EFB produced today is used as mulch on oil palm plantations. Mulch has several positive uses, including weed suppression, moisture retention, and soil erosion prevention, but its high labour and shipping costs are a drawback. Mulch composting is also a time-consuming process that can be affected by environmental factors. Using EFB in composting is an intriguing approach to dealing with the solid waste produced by palm oil mills. Open composting, on the contrary, is a slow process that also produces greenhouse gas emissions.

7.4 Palm Oil Mill Effluent (POME) 7.4.1 Introduction Demand for palm oil compared with other types of vegetable oil is increasing year by year. It is due to strong gross domestic product (GDP) growth, rising per capita income, rapid urbanization, and growing middle-class consumers in the major palm oil-consuming countries such as Malaysia, Indonesia, Thailand, India, China, Pakistan, Africa, and so on [58]. Palm oil production generates two types of waste which are solid and liquid waste known as palm oil mill effluent (POME). On a wet basis, total product stream distribution in oil palm mills is more than 100% due to extra water being added during the process, like sterilization, and most of this water ends up in POME. Due to the high demand for palm oil products, the amount of POME also increases proportionately. Two main stage processes that originate POME are sterilization and clarification. Sterilization is a process using pressurized steam at the high-temperature wet-heat treatment of loose fruit. This process helps to weaken the fruit stem and makes it easy to remove the fruit from bunches, while heat through high-pressure steam is used for sterilization, which may help to expand moisture in the nuts. The clarification process is driven to separate the oil from its entrained impurities [59].

7.4.2 Characteristics of POME Characterization of POME may differ due to the quality of the production process [19, 31, 60]. However, Hashiguchi et al. [61] also include climate factors as an influence on the quality of POME generated. It is related to the rainy season in which less amount of FFB is processed. It is also believed that POME’s final discharge should be diluted by rainwater. Three processes become sources of POME accumulation, namely clarification wastewater, sterilizer condensate, and hydrocyclone wastewater [31, 62] which contribute 17%, 75%, and 8% of POME wastewater

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[47], respectively. POME mainly consists of water (95–96%), total solids (4–5%), suspended solids (2%), and oils (0.6–0.7%) [14, 32]. Its pH value is about 4.5, which means acidic due to the complex form of content in organic acids. A comparison made by Osman et al. [63] between POME characteristics and rainwater found that the pH value of POME is in the range of 8.72 ± 0.35. POME has a different characteristic in every stage of treatment, as recorded by Ahmad et al. [60]. They found that only ammoniacal nitrogen was slightly higher after the pretreatment stage compared with raw POME, while other parameters’ concentration had significantly reduced, and some of it was not detectable by the end of the treatment stage, namely reverse osmosis (Table 7.2). Meanwhile, Hosseini and Wahid [64], in their study on pollutants in the palm oil production process, summarized the characteristics of POME from different parts of the palm oil process, namely sterilization condensate, separator sludge, and hydrocyclone wastewater (Table 7.3). It can be seen that six parameters, namely BOD3, COD, total suspended solids (TSS), total nitrogen (TN), ammoniacal nitrogen (AN), and oil and grease have the highest concentration at the end of the separator sludge process compared with other parts of palm oil mills. Many researchers agreed that POME has a colour of thick brownish due to humic acid and fulvic acid components, phenolic, lignin, pectin, carotene, and tannin [32, 65] and POME also has an unpleasant smell [19]. As depicted in Table 7.4, POME has a high concentration of BOD ranging from 10,250 to 43,000 mg/L, and COD Table 7.2  The POME characteristic in each treatment stage and the drinking water standard set by the US Environmental Protection Agency (USEPA) [60] Parameters (mg/L) COD Ammoniacal nitrogen Nitrogen (organic) Total dissolved solids Oil and grease pH Odour (threshold odour number) Colour (colour units) Turbidity (NTU) Zn Fe Mg Al Mn K Cu Ca

POME 50,000 35 750 20,500 4000 4.7 300

Pretreatment 15,000 37 748 8850 80 4.9 150

Ultrafiltration 12,400 30 710 6640 ND 5.7 70

Reverse osmosis 88 0.50 0.50 130 ND 6.6 ND

USEPA standard NR NR NR 500 0.3 6.5–8.5 3

151 11,000 2.3 46.5 615 3.9 2 2270 0.89 439

128 34 0.08 13.53 589 0.52 1.24 1169 0.11 421

54 0.65 0.04 0.07 181 0.34 0.44 360 0.11 129

ND 0.02 0.01 ND 2.74 ND ND 5.45 0.03 1.95

15 15–20 kHz), or it is simply mechanical waves at a frequency above the threshold of human hearing. Value-added products Any product that has undergone additional processes or been paired with additional products in order to increase the total value of the product. Waste-activated sludge (WAS)  The excess activated biological material produced by activated sludge plants that are removed from the treatment process to keep the ratio of biomass to food supplied in the wastewater in balance. Waste stabilization ponds  are ponds designed and built for wastewater treatment to reduce the organic content and remove pathogens from wastewater. Zero Liquid Discharge (ZLD) concept   Refers to a treatment process in which the plant discharges no liquid effluent into surface waters, in effect eliminating the environmental pollution associated with treatment.

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Chapter 8

Treatment and Management of Hazardous Solid Waste Stream by Incineration Mohamad Anuar Kamaruddin, Wen Si Lee, Faris Aiman Norashiddin, Mohamad Haziq Mohd Hanif, Hamidi Abdul Aziz, Lawrence K. Wang, Mu-Hao Sung Wang, and Yung-Tse Hung

Acronym BOD Biochemical oxygen demand CaO Calcium oxide CEWEP Confederation of European Waste-to-Energy Plants CHP Combined heat and power COD Chemical oxygen demand Cr Chromium C-S-H Calcium silicate hydrate CV Variation coefficient

M. A. Kamaruddin (*) · F. A. Norashiddin · M. H. M. Hanif School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia e-mail: [email protected]; [email protected]; [email protected] W. S. Lee School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Pulau Pinang, Malaysia e-mail: [email protected] H. A. Aziz School of Civil Engineering/Solid Waste Management Cluster, Engineering Campus, Universiti Sains Malaysia, Pulau Pinang, Malaysia e-mail: [email protected] L. K. Wang · M.-H. S. Wang Lenox Institute of Water Technology, Latham, NY, USA e-mail: [email protected]; [email protected] Y.-T. Hung Department of Civil and Environmental Engineering, Cleveland State University, Strongsville, OH, USA e-mail: [email protected]; [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 L. K. Wang et al. (eds.), Waste Treatment in the Biotechnology, Agricultural and Food Industries, Handbook of Environmental Engineering 27, https://doi.org/10.1007/978-3-031-44768-6_8

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DOT Dictionary of Occupational Titles EEB European Environmental Bureau EFW Energy from waste EPA Environmental Protection Agency FBF Fluidized bed incinerators H2NCSNH2 Thiourea Max maximum Min Minimum MSW Municipal solid waste MW Megawatt N2 Nitrogen gas NaH2PO4 Monosodium phosphate NOX Nitrogen oxides O2 Oxygen gas OSHA Occupational Safety and Health Administration PAH Polycyclic aromatic hydrocarbons PCDD/F Polychlorinated dibenzo-p-dioxins and dibenzofurans PM Particulate matter PVC Polyvinyl chloride RCRA Resource Conversation and Recovery Act RDF Refuse-derived fuel SAC Starved air combustion SD Standard deviation Si Silicon SNCR Selective non-catalytic reduction TCLP Toxicity Characteristic Leaching Procedure WtE Waste-to-energy

Nomenclature CO2 eq Carbon dioxide equivalent cm Centimeter o C Degree Celsius o F Degree Fahrenheit D Diameter GJ Gigajoule GWh Gigawatt hour Kg Kilogram kW Kilowatt L Liter MW Megawatt MWh Megawatt hour mm Millimeter mol Mole

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% Percent S Second Ton Tonnes wt% Weight percent

8.1 Introduction The basic goals of the thermal treatment technique known as incineration, which may be seen as a controlled combustion process, are to achieve volume reduction and energy recovery from the waste stream. Incineration is a form of waste treatment that uses heat [1]. When there is a need to handle bulky heterogeneous garbage, and there has been an accumulation of waste on a significant scale, this is the alternate option that is utilized the majority of the time. It is also a process that converts waste into ash, fly ash, a mixture of poisonous gases, heat, and wastewater. Examples of this type of technology include gasification and pyrolysis, among others. Both gasification and incineration functioned according to the same fundamental concept. However, incineration is a process that takes place at very high temperatures, whereas gasification primarily recovers energy through the combustion of combustible gases. Japan is attempting to alleviate the problem of plastic pollution by utilizing this technique [2]. This method is expensive because it generates a great deal of heat from the combustion of pure polyolefins. High-temperature furnaces and ceramic liners are required, in addition to transportation, gathering, sorting, and the construction of incinerators. In the process of incineration, harmful chemicals such as COx, NOx, and SOx are released into the atmosphere from plastic trash. These gases contribute to environmental pollution. Burning things results in the release of a significant amount of carbon dioxide. Communities must devise waste-management strategies using choices such as trash generation reduction, incineration, landfilling, recycling, reusing, and composting. The features of waste streams fed to incineration facilities will change when options, including recycling, are combined with burning, as shown by waste-­ management alternatives to combustion. The committee, however, was not mandated to conduct a comparative analysis of waste-management solutions [3]. In general, any facility that burned waste had to incorporate the following procedures: the storage and handling of waste, the preparation of waste through processing and combustion, the control of air pollution, and the handling of residue (ash). Incinerators, industrial boilers, furnaces, and kilns are the various devices that fall under the category of waste-incineration facilities. Mobile incinerators are used to remediate wastes from specific sites that are contaminated by hazardous waste. Stationary facilities are designed to combust millions of tonnes of waste per year collected from a broad geographical area. There is a large variety of technology, ranging from stationary facilities designed to combust waste to mobile incinerators [4]. Municipal solid waste, hazardous waste, and medical waste are the three categories of waste that are most frequently burned up by the process of incineration. The term “municipal solid waste” refers to the portion of nonhazardous or nontoxic trash that is solid in consistency and is produced by residential and commercial properties, as well as public and private institutions, government agencies, and other types

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of establishments and organizations [5]. In 1960, 31% of the municipal solid waste produced was burned by combustion in low-efficiency combustors. These combustors did not have energy recovery or improved pollution-control technologies. In 1980, only nine percent of waste was burned. Despite this, by the year 1990, the percentage of waste that was burned to produce energy had climbed to 16%, mostly as a result of the increasing emphasis placed on waste-to-energy conversion. The EPA projects that the rate of incineration will drop somewhat to 15.6% by the year 2000 [6]. According to the Resource Conservation and Recovery Act (RCRA), the Environmental Protection Agency (EPA) defines hazardous waste as any type of waste that may be regarded as having the potential to be harmful to either human health or the environment. Companies that make goods, businesses that provide services and wholesale goods, educational institutions, medical facilities, government buildings, and even private homes can all be sources of hazardous waste [7]. They are produced not only by companies that manufacture chemicals but also by people who utilize those chemicals. On the other hand, there is an explosion of pollution-prevention programs. The Environmental Protection Agency (EPA) believes that the implementation of legislation prohibiting the disposal of any hazardous waste that contains liquid on land will result in a significant rise in the amount of hazardous trash that is sent to incinerators, boilers, and furnaces. Even if there is a possibility that industrial growth would lead to an increase in the generation of hazardous waste, there is also a possibility that there will be more pressure to limit such generation as a result of increased attention to waste minimization and recycling. A wide variety of hazardous wastes are typically introduced into incinerators, boilers, and industrial furnaces in essentially the same form in which they were obtained. Because of the nature of these wastes, which can make it difficult to handle them due to their consistency or danger, the least amount of handling possible is preferable. However, pretreatment activities are beneficial whenever they are possible since they make homogeneity of the waste easier and ensure continuous feeding to the combustor. Medical (biomedical) wastes can contain infectious or poisonous properties, and if they are not disposed of correctly, they can be a threat to the general public’s health. Many kinds of activity result in the production of medical waste. Practically every facet of the system that provides medical care contributes, but hospitals are the primary generators of medical waste, producing up to around 26 pounds of garbage per bed, each day. According to the findings of a study that was conducted by Waste Energy Technologies, Inc., and the New York City Department of Sanitation, there is a significant amount of red-bag waste that is both recyclable and avoidable through the implementation of changes in procurement and good maintenance practices [8]. If recycling of this kind becomes commonplace, the number of incinerators required to dispose of medical waste could be cut down to the level that is equivalent to the volume of garbage contained in red bags.

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8.2 Hazardous Waste A waste that possesses features that make it dangerous or capable of harming human health or the environment is referred to as hazardous waste. Hazardous waste can be produced by a wide variety of processes and sources, including industrial manufacturing process wastes and batteries. It can also take on a variety of physical forms, such as liquids, solids, gases, and sludges [9, 10]. The Environmental Protection Agency (EPA) developed a regulatory definition and process that identifies specific substances known to be hazardous and provides objective criteria for including other materials in the regulated hazardous waste universe. These were accomplished through the creation of a regulatory definition and process. This process of identification can be somewhat complicated, which is why the EPA advises waste producers to address the problem by employing the following set of questions (Fig. 8.1): The individuals or organizations that produce hazardous waste are the very first link in the chain of hazardous waste management. Every producer of garbage is responsible for determining whether or not their trash is harmful and for monitoring what happens to it in the end. Furthermore, generators are responsible for ensuring that the hazardous waste that they produce is correctly recognized, managed, and treated before it is recycled or disposed of and they must provide complete documentation of this process [12]. The level of regulation that each generator is subject to is directly proportional to the amount of waste that that generator is responsible for producing.

Fig. 8.1  Question sequel for the hazardous waste identification process [11]

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8.2.1 Hazardous Waste Stream One type of hazardous waste is referred to as reactive if, for instance, it explodes in close proximity to another hazardous waste. This alone is reason enough to avoid mixing the two types of garbage. But on a more subtle level, if the appropriate social distance is not maintained, these hazardous wastes have the potential to become dangerously corrosive, poisonous, or ignitable [13]. The Environmental Protection Agency (EPA) is correct in its assessment that it is of the utmost importance that you maintain their distinct identities. This is due to the tendency of chemical waste for its toxic properties to intensify when combined with other waste. Therefore, you cannot permit individual workers to make ad hoc decisions about what to do with random chemical waste whenever it arises. It could make good financial sense to consolidate several trash streams as part of our efforts to get rid of hazardous garbage. However, to avoid legal and financial repercussions, unanticipated and uncontrolled chemical reactions need to be carefully carried out and accompanied by expert counsel. Also, putting aside concerns about acute corrosivity, toxicity, ignitability, or explosivity, if you do something wrong, the applicable fines and sanctions from the EPA, OSHA, and DOT will dwarf whatever economic gains you had hoped to obtain.

8.2.2 Hazardous Waste Composition When pollutants from hazardous waste are discharged into the environment, they can cause sickness, death, and other harm to humans, plants, animals, and ecosystems. Hazardous waste is defined as solid waste with a chemical composition that produces these effects (EPA, 2021). According to Alumur and Kara (2007) [14], any type of waste that exhibits ignition, flammability, corrosiveness, or poisonous properties is considered hazardous waste. These characteristics can be found in hazardous waste in varying degrees. Waste that poses a risk to human health and the environment can have devastating effects [15]. Because of their potentially destructive qualities, certain wastes are considered to fall under the category of hazardous waste. These wastes include asbestos, waste from thermoelectric power plants, waste from medical practices, and metallurgical slags. According to the report of Koolivand et al. (2017) [16], the chemical industry was responsible for 27.92% of the world’s hazardous waste. In this regard, the chemical industries produce the most hazardous waste as a percentage of their overall output. Waste from the medical and cosmetic sectors has an 18.23% proportion of all hazardous component-bearing waste. This makes it the second most dangerous type of waste. The energy industry, along with the wood and cellulose manufacturing industries, was found to produce the least hazardous waste overall. According to our findings, the daily production of hazardous waste across all sectors averaged around 266.59 kilograms. This amount represents approximately 6.85% of the total

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garbage that was produced. More than 363,000 metric tonnes of hazardous waste were produced by the Malaysian industry in the year 2002 [17]. The industrial sector in Spain was responsible for the generation of over 2 million tonnes of hazardous trash per year, which represented 8% of the country’s total garbage output [18]. In addition, China was responsible for the generation of 11.62 million tonnes worth of hazardous garbage in 2005, which was equivalent to 1.1% of the world’s total industrial waste [19].

8.2.3 Hazardous Waste Characterization Waste that poses a significant risk to public health or the environment is referred to as hazardous waste (often abbreviated as HHW). In general, it refers to substances that are known to exhibit, or have been tested and found to display, one or more of the following four dangerous characteristics: • • • •

Ignitability Reactivity Corrosivity Toxicity

The Basel Convention is an international convention that was created to restrict and regulate the transportation of hazardous waste between countries. As a result of its creation, the Basel Convention manages the international movement of hazardous waste. Over 170 nations are currently members of the Basel Convention, including Australia, which has been a signatory since the year 1992. The Basel Convention entered into force in the year 1992. The term “hazardous waste” refers to the solids, liquids, or enclosed gases that are produced as a byproduct of industrial processes and that if they are incorrectly managed, stored, or disposed of pose a considerable current or potential harm to human health or the environment. Expired vehicle batteries, spent solvents, and sludges from industrial wastewater treatment units are a few examples of the types of hazardous waste that are commonly seen. Ignitability  Ignitable wastes are defined as those that “may start flames under specific conditions,” “are spontaneously combustible,” or “have a flash point less than 60  °C (140  °F),” as stated by the Environmental Protection Agency (EPA). Waste oils and solvents that have already been utilized are two examples. The lowest temperature at which a substance can evaporate sufficiently to produce sufficient vapor to form an ignitable mixture with the air is referred to as the flash point of the substance. Solids and liquids are the two different classifications that can be used to classify ignitable trash. When it comes to ignitable liquids, the flash point is the single most crucial item to keep in mind, as was said previously. However, while dealing with solids, there are additional factors to take into consideration. Ignitable solids have the potential to start a fire under

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conditions of standard temperature and pressure due to friction, the absorption of moisture, or chemical reactions that occur on their own. If these wastes catch fire, they will do so with such ferocity and persistence that they will create a potentially dangerous situation. Reactivity  Reactive wastes are defined by the Environmental Protection Agency (EPA) as wastes “which are unstable under “normal” settings.” When heated, compressed, or mixed with water, they have the potential to generate explosions as well as hazardous fumes, gases, or vapors. Batteries that use lithium sulfur and explosives are two examples. Wastes that react are inherently unstable by their very nature. They have the capability of producing hazardous gases, vapors, or fumes, all of which can put a person’s health in jeopardy. Some D003 may combine with water to produce potentially explosive combinations. Reactive wastes have the potential to detonate or undergo explosive reactions. Wastes that are hazardous because of their reactivity may be unstable under normal conditions, may react with water, may give off toxic gases, and may be capable of detonation or explosion under normal conditions or when heated. In addition, wastes that are hazardous because of their reactivity may give off toxic gases. The waste code for reactive hazardous waste is D003, which was assigned by the EPA. Corrosivity  According to the Environmental Protection Agency (EPA), “corrosive wastes” are defined as acids or bases that have the potential to corrode metal containers. These metal containers include storage tanks, drums, and barrels. One example of this is battery acid. People can sustain skin injury from corrosives, and metal can be extensively corroded by them. A corrosive hazardous material can exist in either liquid or solid form. Aqueous wastes with a pH of less than or equal to 2, a pH of greater than or equal to 12.5, or based on the ability of the liquid to corrode steel are examples of hazardous wastes that exhibit the corrosivity feature. The Environmental Protection Agency (EPA) chose the waste code D002 for corrosive hazardous wastes. Toxicity  According to the Environmental Protection Agency’s (EPA) definition, toxic wastes are wastes that are “harmful or lethal when swallowed or absorbed” (e.g., containing mercury, lead). Contaminated liquid can leak from hazardous trash and harm groundwater when the waste is disposed of on land. When hazardous wastes, which are such because of their inherent toxicity, are swallowed or absorbed by the body, this causes injury. There is cause for concern regarding the potential for toxic wastes to leak from disposal sites and contaminate groundwater. The Toxicity Characteristic Leaching Procedure, also known as the TCLP, is used to evaluate the hazardous potential of waste (SW-846 Test Method 1311). The Environmental Protection Agency (EPA) designated trash codes D004 through D043, each of which corresponds to a specific contaminant and the TCLP concentration that is linked with it.

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8.3 Waste-Incineration Directive Energy recovery from waste is an interesting option for treating waste, particularly from the perspective of the safety of the supply of energy, which may be gained by looking at it from the opposite angle. In addition, the influence that an incinerator has on the surrounding environment can be significantly mitigated by utilizing cutting-­edge technologies for the treatment of flue gas. The waste-to-energy lobby additionally attempted to highlight the potentially beneficial contribution that these plants may make by lowering the reliance on landfills and fossil fuels (CEWEP, 2007). In response to this, environmentalist organizations argued that boosting incineration would have a negative impact on waste recycling for material recovery, which is the sole option that should be advocated and must be the foundation of the system for managing trash (EEB, 2008). Nevertheless, the European Union has announced the publication of the new Waste Framework Directive (WFD). It established new benchmarks in the field of waste management, such as setting lofty recycling goals for the entire EU and mandating the creation of national waste avoidance programs as a prerequisite for compliance. Additionally, the concepts of “recovery” and “disposal” were made more clear. In the new waste hierarchy, incineration can be counted as a recovery operation rather than a disposal one if the energy recovery efficiency is greater than a set threshold. However, this only applies in situations where the threshold has been established [20]. This change does not have any direct practical implications; rather, it has significant indirect implications from a strategic point of view. This is because it is anticipated that it will draw the attention of investors toward the waste-to-­energy (WtE) sector, which will be to the detriment of activities involving landfilling waste.

8.4 Incineration Systems Waste can be incinerated when it is burned at a high temperature, which results in fast oxidation. It is also known as controlled-flame combustion, and it is a method that eliminates organic elements in waste materials. Calcination is another name for this process. This burning process, which is employed as a way of producing energy, is undergoing the development of new procedures. Additionally, incineration is regarded as a volume-reducing measure that can be taken in order to cut down on the expense of landfilling. Industrial furnaces and boilers are two examples of the most popular types of equipment used in the incineration process [21]. The industrial furnace is a type of technology for treating hazardous waste that makes use of thermal energy to recover energy or materials from wastes that have been discarded. It consists of cement kilns, lime kilns, aggregate kilns, phosphate kilns, coke ovens, blast furnaces, and smelting furnaces, among other types of furnaces; a boiler is one sort of equipment that can be used to treat hazardous waste [22]. Boilers work by recovering thermal energy in the form of steam or hot gases through the utilization of controlled-flame combustion.

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8.4.1 Waste Delivery, Bunker, and Feeding System Transporters of hazardous waste are people or organizations that move hazardous waste from one location to another using modes of transportation such as automobiles, trains, boats, or aeroplanes. Transporters of hazardous waste are an essential component of the hazardous waste-management system. Their job is to deliver hazardous waste from the location where it was generated to the location where it will be disposed of permanently. This comprises moving hazardous trash from the location where it was generated to a facility that can recycle, treat, store, or dispose of the waste. It may also involve moving hazardous trash that has been processed to a location where it will either be further treated or disposed of. The waste storage bunker that is located in the reception hall of the EFW incineration plant is an important component of the facility. Its mission is to serve as a location for the storage, buffering, and uniform mixing of garbage that has been supplied, as well as to guarantee a constant supply of waste to an incinerator. The garbage is moved from the dump to the feed chute of the furnace by a grab crane. A level measuring system that is dependable and accurate is necessary to be installed in the waste storage bunker in order to guarantee the effective operation of the plant [23]. In addition, it is necessary to keep an eye on the water level in the feed chute in order to prevent a blowback of flue gas. The operators of the plant are attempting to generate a more homogeneous waste feed composition by mixing the waste in the waste-receiving bunker. This is considered essential for a “constant” operation of the plant, especially considering that the fuel-firing control system can only compensate for fluctuations in the feed composition to a certain extent [24]. Recent investigations into the data from the WtE plant carried out by the authors show that an increase in the variability of the feed waste composition (in terms of changes in biomass content, water content, and calorific value on a short-term basis) is associated with certain performance impairments at the plant. It is possible that the operation of the plant (in terms of steam production) will be less susceptible to periods of intensive trash deliveries and, as a result, less susceptible to potentially increasing changes in the waste feed composition [23]. In addition, the plant features not one but two bunkers, one of which is designated for the storage of garbage and the other for the delivery of waste. The feed of the hopper comes solely from the storage bunker, which means that the composition of the waste in the bunker is less likely to be changed by the delivery of the garbage.

8.4.2 Mass Burn Incineration The term “mass burn” refers to the process of incinerating waste without sorting it first. This can take place in a waste combustor or another type of incinerator designed specifically for burning waste from towns. This approach to managing waste eliminates the need for the time-consuming and laborious job of searching through the

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garbage in search of materials that cannot be burned [25]. The incinerator is fed all of the rubbish that has been received at the plant, which is then shredded into little bits. The steam that is created in the boiler of the incinerator can be used to generate power or to heat buildings in the surrounding area. The remaining ash and noncombustible elements are transferred to a landfill for disposal. Together, these two components account for around 10–20% of the waste’s initial volume [26]. Incineration through mass burn comes with a number of downsides as well. As a result of the garbage not being sorted, it frequently produces more emissions that contribute to air pollution than waste that has been sorted, and it also has a greater propensity to corrode burner grates and chimneys. The residual ash and the items that weren’t burned may be poisonous, so you’ll need to treat them uniquely. Incineration at high temperatures may be an efficient method for transforming hazardous waste into nonhazardous forms while also significantly reducing the amount of garbage. The garbage is burned, which results in the production of carbon dioxide, water, and various inorganic byproducts. The high capital and running costs of incineration, as well as the disposal of ash, which may contain dangerous compounds, are the challenges that are linked with the practice [27]. In addition, burning garbage can release toxic air pollutants such as mercury and dioxin into the atmosphere. With the help of microorganisms and other naturally occurring decomposition processes, bioremediation can be employed either in situ or ex situ to turn hazardous wastes into byproducts that are not poisonous. The biodegradation process takes a very lengthy amount of time to complete, and it can be challenging to exert control over or improve the efficiency of natural degradation processes. A developing method of pollution removal that is currently being researched is called phytoremediation. This is the process by which plants remove harmful compounds from the environment by absorbing them and, in some circumstances, degrading them. It has been demonstrated that poplar trees can degrade the pesticide atrazine, that mustard plants can remove lead from the soil, and that the alpine pennycress plant can remove substantial levels of heavy metals as well as uranium from soil [28]. The generator of trash is responsible for preparing a shipping document known as a manifest whenever hazardous material is going to be carried off-site for disposal. This form is required to be carried by the garbage to wherever it is ultimately disposed of, as it is used to keep track of the waste’s journey “from cradle to grave.”

8.4.3 Furnace The earliest incinerators could be broken down into several distinct categories, including continuous feed, batch feed, ram feed, metal conical, and waste heat recovery [29]. Further subcategorization of continuous-feed incinerators included travelling grate incinerators, reciprocating incinerators, rotary kilns, and barrel-­ grate incinerators. They were different from batch-feed incinerators in that the latter employed a method in which refuse was supplied at periodic intervals, which allowed the batch that had been fed before to almost entirely burn. This system was

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utilized by batch-feed incinerators. In comparison to batch incinerators, continuous-­ feed incinerators were able to process significantly greater quantities of waste because of this design feature. Incinerators with a ram feed and conical metal shapes were just two variants of incinerators with a batch feed. Low-pressure boilers, high-­ pressure boilers, and water wall furnaces were some of the earliest types of incinerators designed for the recovery of waste heat. Low-pressure boilers were the first to be developed, and the majority of them had boilers positioned in the combustion chamber, which resulted in lower combustion efficiency due to excessive cooling of the furnace. Low-pressure boilers were the first to be produced [30]. Later on, high-­ pressure boilers with refractory linings were created. These linings prevented the furnace from becoming overly cooled and had the added benefit of efficiently bringing the temperature of the flue gases down to the desired range of 250–300  °C (482–572 °F). Burning hazardous trash in furnaces is typically done because of the huge potential for energy and material recovery. Waste treatment is a secondary benefit of this practice. In most cases, garbage is burned so that energy may be recovered, whereas industrial furnaces often burn waste so that both energy and material can be recovered. The term “boiler” refers to an enclosed piece of equipment that recovers and exports energy in the form of steam, heated fluids, or heated gases through the use of a controlled-flame combustion process. A unit that is an essential component of a manufacturing process that makes use of thermal treatment to reclaim either materials or energy is referred to as a furnace. The following types of heating appliances are classified as furnaces: • • • • • • • • • • • •

Cement kilns Lime kilns Aggregate kilns Phosphate kilns Coke ovens Blast furnaces Smelting, melting, and refining furnaces Titanium dioxide chloride process oxidation reactors Methane reforming furnaces Halogen acid furnaces Pulping liquor recovery furnaces Combustion device used in the recovery of sulfur values from spent sulfuric acid

8.4.4 Heat Recovery Without taking into account the possibility of energy recovery, a significant amount of hazardous waste from industrial processes has been disposed of in landfills and by incineration. In many different processing plants, the energy that was formerly provided by fossil fuels has been replaced by the heat produced by the combustion

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of these waste products. This heat is used to generate steam and to preheat other process streams [31]. By carefully designing the combustion and heat recovery systems, these plants’ operating expenses can be kept to a minimum without sacrificing efficiency. It is essential to have hands-on experience at many sites where waste gas and liquids have been effectively disposed of through the process of incineration, and the energy values have been recovered for use inside the plant. While the majority of municipal solid waste incinerators are constructed with the primary goal of MSW volume reduction and waste incineration, waste heat recovery incinerators are the only ones that incorporate mechanisms to recover heat. In Europe, the practice of recovering heat from incinerators originated before the twentieth century. In the United States, the utilization of heat from incinerators to generate steam and power did not become necessary until about the middle of the twentieth century. This was due to the fact that growing oil prices pushed this requirement. Because of this, heat recovery finally became the most important consideration in the design of primary waste treatment systems. The first WtE plants were waterwall and modular incinerators, and they lacked flue gas treatment devices. These were the most basic forms of technology [30]. Later on, both the manufacture of refuse-derived fuel (RDF) and the recovery of methane through the simultaneous digestion of garbage and sewage sludge were put into motion. The possibility of long-term markets for steam has further accelerated the expansion of thermal municipal solid waste treatment combined with heat recovery.

8.4.5 Emissions Control The technology for preprocessing has been developed over the years to remove noncombustibles, hazardous compounds, and bulky materials from municipal solid waste. As a result, the combustibility of MSW has improved, as has the ability to manage emissions [32, 33]. Prior to incinerating municipal solid waste, it is possible to reduce the heterogeneity of the waste by screening it with trommel screens, air classifiers, magnetic separators, and eddy current separators, among other types of equipment. Trommel screens separate the different components of MSW by taking advantage of the interaction between MSW particle size, trommel aperture, declination angle, drum length, and rotation speed. Air classifiers, on the other hand, take advantage of differences in density to separate light fractions from the bulk of the MSW [34]. Optical sorting devices are utilized by more modern systems that are available today to separate waste materials based on the optical qualities of the waste materials themselves [35]. The removal of ferrous and nonferrous metals that are electrically conductive can be accomplished with magnetic separators and eddy current separators, respectively. Both of these types of separators use magnetic fields. All of these methods of separation are typically employed in conjunction with one another to accomplish the level of separation that is desired; therefore, it is unnecessary to compare them to one another.

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8.4.5.1 Dust or Particulate Matter When compared to the technology of incineration itself, the issue of air emissions control technology has unquestionably had a bigger degree of influence on the development of WtE.  This is because of the worries regarding air pollution that accompanied early incinerators. The first incinerators were hardly more than mass burn operations with limited ability to control air pollutants. As a direct consequence of this, they swiftly gained popular criticism, which ultimately led to the closure of several plants [30]. Around the same time as electrostatic precipitators were being developed, more sophisticated dust control systems weren’t coming into existence until the late 1980s [36]. It may be possible for plants that are equipped with ESPs and dust sprays to reduce the amount of particulate matter that is present in the flue gas. This would allow the plants to conform to the current emission standards. Incineration facilities that were constructed around the 1970s were required to have a feature known as an emergency bypass flue duct. This was a mechanism that allowed for the release of raw flue gas in the case of an extreme failure of the dust control system [29]. This characteristic is not typically found in contemporary incineration plants. As a direct result of rising levels of public anxiety around emissions from incineration, emission limitations have been tightened significantly. 8.4.5.2 Heavy Metals There is a trace number of heavy metals present in the raw waste stream. The high temperature of the combustion process has a tendency to cause the more volatile heavy metals in the combustion chamber to volatilize. After being cooled in the heat recovery system, the heavy metals are transferred to the fly ash particles, where they condense and are eventually removed together with the fly ash. The smaller the particle size of the ashes, the more likely it is that they will maintain a larger concentration of the heavy metals [37]; therefore, electrostatic precipitation is characterized as residues containing highly toxic substances such as heavy metals and organic compounds (e.g., chlorinated compounds) and is therefore regarded as a typical hazardous waste. This is because electrostatic precipitation involves the use of an electric field. In dry and semidry scrubber systems, the injection of an alkaline material (such as lime powder or slurry) is used to neutralize acidic gases, which are a source of air pollution [38]. Electrostatic precipitation is utilized in the process of landfilling in order to prevent pollution caused by heavy metals. This is due to the high accumulation and mobility of heavy metals. 8.4.5.3 Acidic and Corrosive Gases Within the raw waste stream, acid gases are produced when sulphides and chlorides react with one another. Acid gases do not constitute a direct threat to health, but they are irritants to the respiratory system and should be regulated. The system for the

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management of air emissions includes a system for the control of acid gases; in this system, a lime solution is employed to neutralize the acid gases. Oxides of nitrogen, often known as NOx, are produced during the burning of any substance. Despite the fact that they do not constitute a direct threat to health, they are irritants to the respiratory system and should be managed. A computer-based system optimizes the temperatures of the combustion process to reduce the number of nitrogen oxides (NOx) that are produced, and another system called a selective catalytic reduction system turns the majority of the NOx into elemental nitrogen. 8.4.5.4 Products of Incomplete Combustion: Polycyclic Aromatic Hydrocarbons, Dioxins, and Furans In this study, the emission of polycyclic aromatic hydrocarbons (PAHs) during the start-up, burning, and burnout of four municipal solid waste incinerators were analyzed. Because of the unstable combustion that occurred during start-up settings, PAH concentrations were found to be relatively high. PAH concentrations and the amount of organic carbon found in the dust were shown to have a positive association with one another. Incinerators produce polycyclic aromatic hydrocarbons (PAHs) when they burn municipal solid waste because PAHs are produced when municipal solid waste (MSW) is burned. The nature of the waste, the temperature of the furnace, and the amount of extra air all have a role in the emission of PAHs caused by MSW [39, 40]. Because an incinerator is constantly working under start­up, burning, and burnout conditions, these emissions could be influenced by operational parameters. PAH concentrations have been proven to be high during start-up conditions due to the unstable combustion that occurs during this time [41, 42]. It has been shown that the PAH concentrations in the dust have a positive link with the amount of organic carbon that is present in the dust. Incinerators used for municipal solid waste can have their PAH emissions better managed if the operating conditions are improved. In order to accomplish this goal, research should be conducted on PAH emissions under a variety of operating settings throughout the combustion cycle (start-up, burning, and burnout periods). Dioxins can be produced by any source of combustion, whether it be natural or anthropogenic in origin. They pose a significant threat to human health and require stringent regulation to ensure that as few emissions as possible are produced. Within the combustion chamber, the flue gas that is produced during the combustion process is heated to a temperature of 850 °C for at least two seconds. This ensures that the dioxins that are produced during the incineration of municipal solid waste are eliminated [43]. However, dioxins may reform in the energy recovery system in trace quantity when the temperature drops to the range of 400 to 200 °C. The flue gas is promptly cooled to below 200  °C to reduce this dioxin reformation [44]. Regular cleaning of the boiler tubes is also done to prevent the accumulation of fly ash, which, if left unchecked, can act as a catalyst for the reformation of dioxin. If dioxins are created during the energy recovery process, they are captured using a powdered activated carbon (PAC) injection system that works in parallel with the

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alarm warning system. This system is designed to remove any dioxins that are formed. After that, the used PAC is mixed with the fly ash for stabilization before being disposed of in a landfill.

8.4.6 Energy Recovery via District Heating, Electricity Generation, and Combined Heat and Power In order to properly evaluate the effects of waste incineration on the generation of heat, it is necessary, in the ideal case, to perform a comprehensive quantification of the heat supply generated by each plant that is part of the district heating network, the prices of heat, and the amount of heat that could potentially be replaced by heat generated by the waste incinerator. Due to the fact that many of the plants that generate heat also supply power and that each network for district heating is unique, completing this task may prove to be exceedingly challenging [45]. Even though district heating is most useful in more temperate countries, there are other ways in which the extra heat from a waste incinerator can be put to use, such as in district cooling systems, which are more applicable in hotter regions (in which a temperature difference is used to drive a cooling device). The system is made up of hundreds of independent networks, each of which can be any size and has its own unique set of technological and physical characteristics [46]. The utilization of inhomogeneous fuels like trash is made possible by the district heating network infrastructure, which also makes it possible to utilize the surplus heat produced by industry [47]. The network system receives heat from a wide variety of plants. In 2007, approximately fifty percent of the heat came from combined heat and power (CHP) plants that were large and centralized, thirty percent came from CHP plants that were smaller and decentralized, and the remaining portion came from plants that only produced heat [48]. Wind turbines and combined heat and power (CHP) facilities, both large and small, decentralized CHP plants, and huge central CHP plants are the primary generators of electricity. In 2007, cogeneration of electricity and heat accounted for almost half of the total output of combined heat and power (CHP) plants [44]. The nation’s power systems are interconnected with those of the countries in the immediate vicinity. The Nord Pool, which is a market for trading electricity, is where the vast majority of the transactions take place. As a consequence of this, the generation of electricity that is used in any nation may also be based on hydropower or nuclear power, even though these energy technologies are not found there. Because the heat and electricity created from municipal solid trash incineration are considered to be prioritized forms of energy, energy derived from waste is currently in the front of the queue to be sold at the market as an alternative to energy produced by conventional plants [47]. Because the demand for heat in some district heating networks is not strong enough to utilize all of the heat generated from garbage incineration, certain municipal solid waste incinerators are required to shut off their heat during the summer months.

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8.4.7 Other Types of Incineration 8.4.7.1 Fluidized Bed Incinerators The transfer of heat from the bed of hot sand or other granular material that is used in a fluidized bed incinerator to the garbage is called fluidization. It is frequently employed in the process of decomposing municipal sludge. • Fluidized bed incinerators can be constructed from the ground up or rebuilt using cutting-edge control technologies. Utilizing advanced process controls enables the system to be optimized for maximum product yield, product quality, and fuel savings, all of which can be achieved through optimization. • Control packages can be customized to give the customer a fully automated machine to a basic package that requires manual intervention at every step. • All systems can be automated (Fig. 8.2). In point of fact, it is a vertically oriented steel shell that has a cylindrical shape, is lined with refractory material, and has a sand bed along with a fluidizing air distributor. The FBF is typically offered in diameters ranging from 9 to 25 feet and heights ranging from 20 to 60 feet (1 foot equals 0.3048 meters). The bed of sand

Fig. 8.2  Fluidized bed incinerators [158]

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has a thickness of about 2.4 feet and is supported by a refractory-lined air distribution grid. In order to fluidize the bed, the air is fed into the grid at a pressure of 3–5 pounds per square inch. There is around an 80–90% enlargement in the bed. The temperature of the bed can be adjusted to be anywhere between 1400  °F and 1500 °F. Ash is collected from the top of the furnace by air pollution control equipment after being transported there by the conveyor belt. The combustion of “containerized” liquid hazardous waste can be accomplished with this method. The treatment of nonrecyclable industrial waste and sludge from industrial processes and water purification is accomplished by Indaver through the use of fluidized bed incinerators [49]. The technique can treat very big volumes thanks to its capacity for rapid incineration. Indaver and other parties make use of the steam and power generated from the conversion of the energy produced by the incineration process. In the process of designing the fluidized bed installation, the rational management of energy was the primary focus. Because of this, the furnaces are constructed to recover energy in an effective manner [50]. A vertical steam boiler is used to collect and reuse the heat that is produced by the thermal treatment. The created steam is then transported to a turbine generator, where it is transformed into energy and distributed to the public electrical system. 8.4.7.2 Starved Air Incinerators The process known as starved air combustion (SAC) or thermal gasification makes use of equipment and process flows that are comparable to those used in incineration; the only difference is that a quantity of air that is less than that which is required for complete combustion is provided. Auxiliary fuel may be necessary, depending on the volatile substances that are present in the polluted soil [51]. The harmful organic substances are either vaporized or decomposed as a result of the high temperature. The pyrolytic or oxidative nature of the gas-phase reactions that take place is determined by the amount of oxygen that is still present in the gaseous stream. The dirt, when it has been dried, or the solid residue, is dark brown. Because of the less amount of air that is needed for the SAC process, it has a higher thermal efficiency than the incineration method [52]. Because of the reduced need for gas-­ handling equipment, it may also be possible to obtain savings on capital expenditures. Once more, a system for treating the gases produced by the afterburner will be necessary to clean the air stream. After going through the SAC process, the soil is sterile, free of pathogens, and ready to be restored to its original location (Fig. 8.3). The process of starved air combustion results in the least amount of wasted energy. Bottom ash is produced as a byproduct of the process, and it typically consists of hazardous heavy metals and carbon that have been partially burned. Because of its extremely hazardous qualities, ash cannot be disposed of directly in land landfills. Therefore, an efficient solidification and stabilization of bottom ash were resorted to in order to change potentially hazardous solid wastes into less hazardous or nonhazardous solids before it is disposed of in the landfill. This was done in order to prevent the release of toxic chemicals into the environment [54]. The situation of

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450°C

Burner

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Secondary Chamber

Exhaust (flue) Gas 1000°C

Entrained Gases

Excess air blower

Primary Chamber To Primary Chamber

Compressed Air HTR

Fig. 8.3  A typical schematic diagram of a starved air incinerator [53]

starved air combustion was kept going by flushing the system with nitrogen in such a way that the oxygen content in the mixture was kept to a minimum of 10%. Because the amount of oxygen in the N2–O2 mixture used for starved air combustion was carefully chosen, there was no detectable amount of hexavalent chromium in the calcined sludge. Sludge from tanning operations was dried and powdered before being burnt at 800 °C in an oxygen-starved environment (the O2/N2 ratio was 0.11). The purpose of this is to avoid the oxidation of Cr3+ to Cr6+ while retaining the combustion of organic components in solid waste [52]. The following advantages are expected in starved air combustion: • Heat recovery from sludge. • The resulting residue will meet the requirement for solidification and stabilization using Portland cement. • Ash can be replaced for sand in concrete. • Disposal volume of sludge is reduced. 8.4.7.3 Rotary Kiln Incinerators In contrast to other types of incinerators, the rotary kiln furnace, also known as the rotary kiln incinerator, is one of a kind due to the fact that it is constructed in such a way as to enable the hazardous waste load to be loaded in batches rather than in a continuous manner. During this type of operation, known as batching, solid contaminated soils, solid wastes, and “containerized” liquid wastes are introduced by entrance chutes, often simultaneously with the flow of gas [55]. Kiln angle and rotation speed continuously expose a fresh surface for oxidation, regulate the residence durations of noncombustible materials, and provide for continuous ash removal. Kiln angle and rotation speed also influence the amount of ash that is continuously removed. The container for the liquid waste, which is commonly made of

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Fig. 8.4  A typical rotary kiln incinerator [57]

cardboard, plastic, or steel drums, bursts open or burns upon entering the incinerator, thereby exposing the contents to the extremely high temperatures inside the kiln [56]. The potentially dangerous liquid then rapidly vaporizes and reacts with the extra oxygen that is present in the combustion gases produced by the continuous primary flame. For the purpose of cleaning the gaseous streams that are created, an afterburner and many other supplementary pieces of air treatment equipment will be essential (Fig. 8.4). Because of its adaptability in processing solid waste, liquid waste, and containerized waste, the rotary kiln is frequently employed in the process of incinerating solid and liquid garbage. The interior of the kiln is lined with refractory. In order to promote the mixing of the waste materials, the shell is positioned at an angle that is five degrees off of the horizontal plane [58]. Feeding typically takes place via a ram or conveyor system for solid wastes and drummed wastes. A nozzle allows for the injection of hazardous wastes in liquid form (s). After the firing process, the noncombustible metal and other leftovers are released as ash from the kiln. In addition, rotary kilns are widely utilized for the burning of hazardous garbage. Incinerators, known as rotary kilns, have steel shells that are cylindrical and lined with refractory. These shells are supported by two or more steel trundles that ride on rollers, which allows the kiln to spin about its horizontal axis. The acid fumes that are produced during the incineration process do not corrode the refractory lining since it is resistant to corrosion. Incinerators that use rotary kilns typically have a length-to-diameter (L/D) ratio that falls somewhere between 2 and 8 [59]. Depending on where you are on the kiln’s edge, rotational speeds can be anything from 0.5 to

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2.5 cm/s. For wastes that require longer residence times, high L/D ratios and slower rotational speeds are utilized in the treatment process. Kilns typically measure from 8 to 40 meters in length and anywhere from 2 to 5 meters in diameter [60]. The rate of rotation of the kiln and the amount of time that solids spend in residence are inversely connected. When the rotation rate of the kiln is increased, the amount of time that solids spend in residence is decreased. The amount of time that the waste feeds stayed in the kiln ranged from 30 minutes to 80 minutes, and the rate at which the kiln rotated ranged from 30 revolutions to 120 revolutions per hour [61]. Kiln orientation is another aspect that might have an impact on the total amount of time spent in the chamber. Kilns are typically set up on a gentle slope, which is known as the rake position in the industry. In most cases, the rake is tilted at an angle of five degrees from the horizontal. Directly into the rotary kiln, hazardous or nonhazardous wastes are fed using arm feeders, auger screw feeders, or belt feeders to feed solid wastes. This can be done constantly or semicontinuously, depending on how quickly the waste needs to be processed. In addition to this, potentially harmful liquid wastes might be combined with solid wastes or injected using a waste lance. In order to guarantee that the hazardous waste is completely incinerated, rotary kiln systems often incorporate secondary combustion chambers and afterburners. Temperatures in the secondary combustion chamber or afterburner of the operating kiln can range from 800 °C to 1300 °C, depending on the type of waste being processed [62]. Liquid wastes are often injected into the kiln combustion chamber. 8.4.7.4 Liquid and Gaseous Waste Incinerators The method of activated sludge, the method of water treatment, and the method of incineration are all viable options for the treatment of waste liquid. If the COD or BOD value of the wastewater is too high for the activated sludge and water treatment method, then the incineration method should be used instead. This method is to be used when the wastewater can’t be treated by either of these methods [63]. The “Waste Disposal and Public Cleansing Law” outlines the structure of the incinerators and the maintenance management standards. The standard flow for processing is a combustion chamber → waste heat recovery boiler → dust collector [64]. Setting up an air preheater as part of the process flow allows for the recovery of even more heat from the exhaust while simultaneously lowering the amount of auxiliary fuel consumption. This additional option is available. The presence of nitrogen in the waste liquid results in the production of NOx emissions. At the output of the furnace is where the quencher that is filled with sealing water is installed. The flue gas that contains inorganic salt is guided to the dip tube, where it is cooled by passing through the cooling water. After a little while, the temperature of the gas begins to drop to somewhere near 90 °C. The rule requires that the particles in the exhaust gas be removed, and the dust collector (also known as a venturi scrubber) is responsible for capturing the vapors that are left over in the

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cooled gases. The exhaust gas, which does not contain any dust or fine particles, is discharged into the atmosphere via the stack or chimney. An auxiliary fuel can be either a liquid fuel, like heavy oil, or a gas fuel, like natural gas. Both types of fuel can be employed. The SNCR process can be carried out in the furnace if oil of poor quality or recycled oil is used [65]. Because of this technique, it is feasible to reduce the amount of “S” that is present in the fuel. As a result, these various kinds of oil may be utilized. In the event that the calorific value of wastewater is low but the capacity is high, a significant quantity of auxiliary fuel will be required, which will cause the operating costs to be problematic [66]. This system recycles the waste heat and preconcentrates the wastewater, which allows for a reduction in the amount of auxiliary fuel to be required. The heat or energy that is emitted from the waste liquid equipment is utilized and delivered to the evaporator [67]. However, when there is a high salt concentration in the waste liquid, the system needs to be thoroughly analyzed in order to identify the suitable range. This is because crystallization after pre-concentration can become an issue if it is not done properly. The gases of exhaust that are expelled from the stack are humidified and have an approximate temperature of 90 °C. This emission is in complete compliance with all rules and regulations pertaining to the environment; nonetheless, the water vapor condensation causes the emissions to take on a white smoke appearance. As a consequence of this, more installations might be necessary as a preventative step for the ecosystem that is around us.

8.5 Incineration Fly Ash The incineration fly ash can be classified as hazardous waste, which will bring side effects to the environment and human health. The incineration fly ash must be treated before disposing of in the landfill. Furthermore, various studies discovered that incineration fly ash could be utilized as construction material in cement production.

8.5.1 Treatment of Incineration Fly Ash The incineration fly ash is considered hazardous waste due to the high associated concentrations of heavy metals and soluble salts. Since the incineration fly ash has a high content of soluble salts, it cannot be disposed of directly into the landfill and pretreatment is required. The incineration fly ash-based geopolymers are utilized for disposal in flexible landfill because more than 77% of chloride ions and more than 64% of sulphate ions in the geopolymers could be eliminated through water-­ washing treatment when the addition of aluminosilicates exceeded 20  wt%. The alkali activation technique followed by the water-washing treatment was applied to

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extract the soluble salts effectively while inhibiting the heavy metals’ leaching [68]. Qin et al. (2022) mentioned that prewashing was recommended as pretreatment for the gasification fly ash carbonization because it could improve the adsorption of carbon dioxide, enhance the pH of carbonated gasification fly ash, and improve the immobilization of heavy metals. An optimum treatment period was necessary because a longer treatment period would reduce the performance of heavy metal immobilization. Due to the removal of chlorides by the prewashing treatment, the final pH of the carbonated gasification fly ash was in weak alkaline conditions, which is more favorable for the immobilization of heavy metals. Chen et al. (2022) [69] proposed a new technique for the incineration of fly ash carbonation treatment under room temperature and pressure and controlled by the calcium carbonate oligomers. The optimum operational conditions were 60 minutes at the temperature of 20 °C with a carbon dioxide flow rate of 200 mL/min, shaking speed of 600 rpm, and a liquid/solid ratio of 10 L/kg. The carbonation efficiencies would increase due to the increase of carbonate ions with the addition of alkaline. The leaching concentration of the heavy metals significantly decreased, and the curing efficiencies could obtain greater than 90% due to the conversion of heavy metals into carbonate by carbonation reaction. The addition of alkaline would hinder the formation of the calcium carbonate oligomers and increase the pH of the treated samples resulting in the leaching concentration of heavy metals to increase [69]. Due to the current carbonation technology of incineration fly ash having various weaknesses such as low carbon sequestration efficiency, harsh conditions, and complicated equipment, an ultrasonic chemical method coupled with a wet carbonation technique was proposed by Chen et  al. (2022) [70]. The ultrasonic carbonation enhanced the carbon dioxide capture capacity, and the carbonation efficiency improved to 18.8% due to the ultrasonic physical and chemical excitation boosting the mass transfer efficiency and strengthening the gas–liquid three-phase carbonation reaction. The ultrasonic carbonation also impeded the release of lead and zinc into the liquid phase and enhanced the solidification efficiency of lead and zinc in fly ash since the free lead and zinc converted carbonates completely. The ultrasonic carbonation fly ash had the ability as an economical, environmentally friendly, and resource-based application product because it had a single component, small particle size, high degree of homogenization, and low alkalinity and contained slender nano-calcium carbonate crystals [70]. Chen et al. (2022) [71] demonstrated that the washing of fly ash with deionized water and sodium carbonate solution could remove the soluble ions such as chloride and sulfate effectively. When the fly ash is washed by the deionized water, more than 90% of chloride can be removed. However, the removal of sulfate was low at an estimated 30%. On the other hand, there was high removal of sulfate when the fly ash was washed by sodium carbonate, and it hindered the release of calcium by preventing the formation of calcium sulfate precipitation. The sodium carbonate washing integrated washing with stabilization, and leaching of heavy metals was significantly decreased [71]. Chuai et al. (2022) [72] revealed that the incineration fly ash contained various pollutants such as heavy metals, mercury, chlorine minerals, and calcium minerals. The concentrations of heavy metals and mercury would

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initially increase and later decrease as the incineration fly ash particle size decreased. The injection of calcium oxide could convert the fly ash into alkaline conditions and aid in reducing the leaching rate of lead and arsenic. The stabilization/solidification of incineration fly ash with coal gangue-based geopolymer could be enhanced by adding the active calcium content. The calcium silicate hydrates and calcium aluminate silicate hydrate gels were formed when the active calcium content increased, which aided in immobilizing the heavy metals through physical encapsulation and chemical stabilization [73]. The microbial-induced calcium carbonate could be utilized to treat the incineration fly ash, which enhanced the immobilization of certain heavy metals of incineration fly ash, such as lead, cadmium, and zinc. The amount of zinc in the incineration fly ash was relatively high, and the immobilization of zinc could be obtained by the physical and chemical adsorption of gels that were produced with the addition of metakaolin. If without the addition of alkaline activators, the generation of gels would not be sufficient [74]. The anaerobic fermentation waste liquid could be utilized as an efficient and low-cost incineration fly ash washing because it could reduce the chlorine in the incineration fly ash up to 0.82%. The washing pretreatment could decrease the melting point of incineration fly ash, which is nearly 30 °C [75]. Guo et al. (2022) [76] indicated that when the temperature increased, most of the heavy metals would convert into a gas phase. The volatilization of the zinc was hindered in the water-washing incineration of fly ash. In the incineration fly ash melting process with an iron bath, most of the heavy metals might convert into the iron phase in the form of metallic elements. Yao et al. (2022) [77] indicated that the leaching of heavy metals from the carbonated incineration bottom ash and its associated toxicity could be reduced by utilizing the innovative accelerated carbonation of incineration bottom ash using simulated biogas composition from anaerobic digestion processes. The optimal reaction condition was at the temperature of 25  °C for 8  hours. The experiment found that fewer heavy metals were leached out in carbonated incineration bottom ash due to the locking of heavy metals in the calcite matrix [77]. The co-disposal of incineration fly ash with the electrolytic manganese residue could help to solidify or stabilie the heavy metals in the fly ash. The raw electrolytic manganese residue could not stabilize the incineration fly ash due to the manganese competition with other heavy metals complexing with stabilizer. Thus, sinter pretreated electrolytic manganese residue was applied to improve the stabilization/solidification of heavy metals of incineration fly ash with NaH2PO4 and H2NCSNH2 [78]. There are various reagents, such as ethylenediaminetetraacetic acid, oxalic acid, citric acid, and hydrochloric acid, that could aid in removing the heavy metals from the raw paper incineration fly ash. The simultaneous use of ethylenediaminetetraacetic acid and oxalic acid could help to enhance the removal efficiency of heavy metals. The eluted amount of heavy metals and chlorine was reduced when the incineration fly ash was treated with the simultaneous use of ethylenediaminetetraacetic acid and oxalic acid, while the calcium oxide content in the incineration fly ash increased; thus, the combined reagents could improve the solidification effect of the treated incineration fly ash [79]. Although the incineration fly ash could be

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recycled, pretreatment was needed before recycling could be implemented. Water washing and carbon dioxide-aided washing could eliminate the chloride salts in the fly ash effectively. The addition of carbon dioxide during the washing could improve the removal of chloride, while the injection of carbonate did not have any significant effect on removing the chloride. However, the water-washing methods had low efficiency in eliminating sulfate and heavy metals [80]. The microwave hydrothermal degradation coupled with geopolymer immobilization was utilized to enhance the degradation efficiency of persistent organic pollutants in the incineration fly ash, as well as to overcome the difficulties of subsequent hydrothermal liquid and hydrothermal slag treatment. The temperature of 220 °C in 1 hour reaction time with the 10 wt% NaOH addition was the optimal process condition for the microwave hydrothermal dichlorination. The microwave increased the hydroxide-mediated hydrolysis reactions and promoted the breaking of carbon– chlorine bonds, resulting in dichlorination. The microwave hydrothermal caused the environment to change into alkaline, promoting the formation of calcium hydroxide, which subsequently formed Friedel’s salt with chloride in geopolymer. The incineration fly ash-based geopolymer had good environmental safety and application potential due to the high immobilization efficiency of heavy metals and chloride [81]. The heavy metals in the incineration fly ash could stabilize with the coal fly ash through hydrothermal treatment. The chlorine could be removed by more than 95% by the water-washing pretreatment and hydrothermal treatment. Most of the heavy metals were stabilized in the hydrothermal product, and the stabilization of heavy metals was improved when the addition of coal fly ash increased. Thus, the addition of 30% coal fly ash was the optimum dosage with the lowest leaching concentrations of heavy metals [82]. Zhu et al. (2022) [83] implemented the wet treatment to treat the heavy metals and salts in the fly ash. In the batch leaching, most of the leaching concentration of heavy metals was reduced through the wet treatment under acidic conditions.

8.5.2 Application of Incineration Fly Ash The cement or sand in the cementitious materials could be replaced by the sugarcane bagasse ash. When 20% of ground sugarcane bagasse ash was substituted, the compressive strength of the mortars was increased, and the porosity was decreased. The resistance to the diffusion of chlorides and the chloride electrical resistivity was also improved. The interfacial transition zone was enhanced by substituting the ground sugarcane bagasse ash, in which the gap between aggregates and pastes was narrowed and closed. However, untreated sugarcane bagasse ash was not suitable for substitution due to its big porous particles content that reduced the workability of mortars and compressive strength and increased the water demand [84]. The mixture of soft marine clay and incineration bottom ash could be used as fill materials for the transportation infrastructure. When the ratio of soft marine clay and incineration bottom ash content increased, the water content, plastic limit, and

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liquid limit of the mixture of incineration bottom ash and soft marine clay decreased, by changing the classification from high plasticity clay to low plasticity clay. The increased ratio of the content of incineration bottom ash and soft marine clay could enhance the unconfined compressive strength and compatibility. The presence of soft marine clay would reduce the leaching of heavy metals from the incineration bottom ash [85]. The poultry manure ash contains necessary nutrients such as phosphorus and potassium, which could be used as fertilizer. The separated phosphorus concentrate from the ash had better biomass growth at a low dosage compared to raw poultry manure ash [86]. The aged incineration bottom ash could also be used as an alternative substrate for horizontal subsurface flow constructed wetlands. The aged incineration bottom ash in the horizontal subsurface flow constructed wetlands could enhance the removal efficiency of BOD and nitrogen species. The removal of total phosphorus was increased by releasing the calcium ions to form insoluble sediments [87]. The co-disposal of construction waste with incineration fly ash could enhance the compressive strength of the geopolymer and reduce the leaching concentrations of the heavy metals. The co-disposal of construction waste and incineration fly ash had lower energy consumption and carbon dioxide emissions than ordinary Portland cement [88]. The incineration fly ash could replace the partial fly ash in the alkali-activated mortars. The incorporation of incineration bottom ash resulted in a worsening of mechanical properties. However, most non-reinforced precast products did not need high mechanical properties; the substitution of fly ash with incineration bottom ash in combination with carbon dioxide-based curing was recommended so that it could reduce the use of ordinary Portland cement with the reduction of carbon dioxide emissions [89]. Irshidat et al. (2022) also stated that the alkali-activated binder had better quality in terms of strength, workability, density, and water absorption when a small dosage of incineration fly ash (5%) or sand (10%) replacement was added. The thermal conductivity of the binder would reduce when incorporated with incineration fly ash or sand. The micromorphology of the geopolymer mortar would turn weaker due to the increased incineration fly ash content. Increases in the incineration fly ash replacement rate would lead to a decrease in the microstructural compactness of geopolymer, and more pores and cracks occurred [90, 91]. The combination of the incineration of fly ash and aluminosilicate supplementary cementitious materials could increase the immobilization of heavy metals and improve the compressive strength of alkali-activated and geopolymer hybrid binders. The silica fume had better improvement of compressive strength compared to metakaolin and coal fly ash because the silica fume contributed to the degree of agglomeration and prevalence of relatively strong Si–O–Si bonds in the agglomerated tetrahedral aluminosilicate network. The high addition of incineration fly ash would bring a negative effect on the compressive strength because it could reduce the C–S–H hydration production [92]. The incineration of waste crop highland barley straw generated large amounts of ash that could be used in magnesium oxychloride cement. The water resistance and mechanical properties of the magnesium oxychloride cement were enhanced by

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adding the highland barley straw ash. The magnesium oxychloride cement had optimized pore structure and improved the water resistance due to the formation of magnesium silicate hydrate with 10% external addition of highland barley straw ash. However, with internal addition, the water resistance and mechanical properties of magnesium oxychloride cement were degraded [93]. The fine recycled aggregate in the cement mortar could be partially replaced by incineration bottom ash. The 10% of medium fraction (0.3–0.6 mm) was replaced with the recycled fine aggregates showing the best compressive and flexural strength. If the mortar is mixed with 1 mol/L sodium hydroxide solution, the mechanical properties will decrease due to the aluminium-induced hydrolysis reactions that could cause the production of hydrogen gas. The addition of incineration bottom ash increases would cause a reduction of the compressive strength [94]. In Vietnam, the incineration bottom ash was used to replace the natural crushed sand in cement-based mortar. There was increased porosity, water absorption, drying shrinkage, and reduction of compressive and bending strengths when the amount of incineration bottom ash increased. When the incineration bottom ash content increased, the chloride ion penetration was also increased due to high porosity and micro-cracks in the mortar, while the sulfate resistance was reduced [95]. Six percent replacement of incineration ash in the cement was the optimum content which resulted in high compressive strength and durability. The ultrasonic pulse velocity was the highest at 6% replacement of incineration ash in the cement which indicated that the concrete had better quality [96]. A cold-bonded fine aggregate could be used as sustainable concrete by using 60% incineration bottom ash, 10% ordinary Portland cement, 30% fly ash or ground granulated blast furnace slag, and 1% volume of polypropylene fiber as raw materials. By adding the ground granulated blast furnace slag compared to fly ash, the overall fluidity and mechanical properties were increased. The strength of cold-­ bonded fine aggregates with ground granulated blast furnace slag could achieve 96%. The use of polypropylene fiber on the cold-bonded fine aggregates was to hinder the cracking by bonding with the matrix. The cold-bonded fine aggregates could enhance the transition zone and the tensile bonding performance of the concrete interface zone, which the fibers helped to hinder the cracking damage when the transition zone extruded [97]. Liu et al. (2022) [98] mentioned that the compressive strength, water absorption, density, and moisture content were in good condition when the cold-bonded aggregates from the incineration bottom ash is applied. The compressive strength was increased by 74% to 113% and the water absorption was decreased by 3.4% to 8% under the 80 °C curing condition. The low-carbon cold-­bonded aggregate could reduce the leaching of copper and lead efficiently. The wastepaper fly ash could generate lightweight aggregates by granulating with water in the high-intensity granulator. The addition of water could promote rapid setting and hydration due to the presence of calcium oxide in the wastepaper fly ash. The carbonation process was required to increase the density and enhance the compressive strength with low porosity and water absorption in lightweight aggregates as well as increase the immobilization of heavy metals [99]. The sintered incineration fly ash could be used to produce lightweight

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aggregate by using silicon carbide as a bloating agent. The high addition of silicon carbide could lead to the shrinkage of the lightweight aggregates when the temperature was greater than 1160 °C. Thus, 0.1–0.5 wt% silicon carbide addition, 1100–1160 °C sintering temperature, and 4–60 minutes sintering duration were considered optimum parameters to produce high-quality lightweight aggregate [100]. A geopolymer brick was prepared by the incineration of fly ash and the carbide slag to produce high compressive strength and reduce the porosity at 30 MPa molding pressure. The molding pressure was applied to allow the particles to be tightly bound and enhance the geopolymerization reaction. The hydration reaction could be accelerated, and the compressive strength was increased at hightemperature curing [101]. The high-temperature-treated incineration fly ash could be used in ultrahigh-­performance concrete. With less than 20% incineration fly ash replacement, the hydration process of concrete was accelerated, fluidity was reduced, and the setting time was shortened. The compressive strength of the concrete for 28 days was enhanced because of the inclusion of high-temperature-treated incineration fly ash [102]. The fired bricks that were manufactured by the incineration fly ash had significant side effects on the environment and low product quality. By adding the electric arc furnace slag as a pore plugger, the water absorption and porosity decreased by more than 50%. With the addition of 30 wt% electric arc furnace slag, the compressive strength of the fire bricks had improved by 50%. Thus, the fire bricks manufactured by the incineration fly ash should incorporate with electric arc furnace slag to produce a better quality product and environmental safety [103]. Ceramic tiles could be produced by using high-calcium incineration fly ash. The ceramic tiles that contained incineration fly ash had better water absorption and mechanical strength. The presence of incineration fly ash could help to save energy by using a lower firing temperature. Since incineration fly ash consists of high calcium, it might increase the porosity of the tiles, which is beneficial for the thermal properties [104]. Porous glass ceramic could be manufactured by incineration fly ash through alkali activation–crystallization. Aluminium oxide and silicon oxide are co-treating as raw materials to produce a glass framework structure that can be found in the incineration fly ash. The alkali activation process represented the development of incineration ashes-based basic glass from monomer to silica aluminate gel under alkaline conditions. The porosity and bulk density were increased when 1–4  wt% hydrogen peroxide was added under the crystallization treatment at 1150 °C for 2 hours, while the compressive strength was also increased up to 3.85 MPa [105]. The paper mill ashes could be used as potential supplementary cementitious materials in the cement-based mortar, which could enhance the early hydration reactions and reduce the initial setting time. When the paper mill ashes replacement ratio increased, the compressive strength of the mortar would decrease, of which 10 wt% paper mill ashes were the optimum replacement ratio [106]. The

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waste newspaper ash could also be used as partial cement replacement in the treated cement cylinders with the optimum mix ratio of 7.5%. The treated cement cylinders incorporated with the waste newspaper ash had high compressive strength due to low average water absorption [106]. The microbially induced carbonate precipitation method was used to reduce the impact of incineration fly ash on the compressive strength. When the technique was applied, the leaching of the heavy metals was reduced by 70% to 90% by biomineralization. The compressive strength was enhanced when the biotreatment technique was applied, and the carbon dioxide emissions were reduced as well [107].

8.6 Co-incineration Co-incineration is one of the methods to handle hazardous waste during the emergency period to reduce the amount of waste in the surrounding. However, this method is not suitable for long periods to manage hazardous waste, and it might generate some hazardous residues in the environment.

8.6.1 Co-incineration in Cement Kiln The mono-incineration was the most environmentally unfriendly due to high cumulative energy demand and life cycle costing. Compared to the co-incineration in cement kiln, the cumulative energy demand, life cycle costing, and environmental burdens were the lowest [108]. The municipal solid waste and sewage sludge could be co-incinerated in the cement kilns. The polychlorinated dibenzop-dioxins and dibenzofurans (PCDD/F) would generate in the cement kiln. The formation of PCDD/Fs occurred at the preheater, kiln back-end boiler and humidifier tower, and bag filter at the kiln back end. The concentrations of PCDD/F in particulate samples from the major formation process sites would be affected by the co-incineration of municipal solid waste and sludge in the cement kiln [109]. According to the [110], the co-incineration of sewage sludge with other wastes in the cement kiln would not affect the emission of polychlorinated biphenyls. High concentrations of polychlorinated biphenyl could be mainly found in the suspension boiler and humidifier tower, kiln-end bag filter, and cyclone preheater; thus, the polychlorinated biphenyl concentrations at those stages should be controlled [111] mentioned that the highest concentration of polycyclic aromatic hydrocarbons could be found 1200  m downwind from the cement plant. The co-incineration of sludge, coal, and hazardous waste in the cement plant might cause potential risks to the population and the environment surrounding the cement plant due to the high levels of mercury determined in the surrounding soil at the cement plant.

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8.6.2 Co-incineration of Municipal Solid Waste and Sewage Sludge Municipal solid waste can also be co-incinerated with the sewage sludge in municipal solid waste incineration [112]. demonstrated that the combustion temperature of the furnace reduced significantly with the rise of the mixing proportion and moisture content of the sludge. This is because the sludge contains higher moisture content than municipal solid waste and has low calorific value. The optimum water content and mixing ratio of sludge was controlled below 40% and 7%, respectively. Thus, the sludge should be dehydrated before adding into the furnace [113]. indicated that the amount of amorphous increased with the increase of fraction sizes: the smallest the co-incinerated of municipal solid waste with sewage sludge, the more heavy metals were discharged. The finest fraction of co-incinerated municipal solid waste with sewage sludge had better hydraulic behavior due to the presence of high CaO content. According to the [114], the leaching of heavy metals from the co-­ incineration of municipal solid waste and sewage sludge was lower than the standards. However, the synergistic effects appeared during co-incineration, which could delay the pyrolysis and incineration of polymers and fixed carbon. The synergistic effects occurred due to the presence of copper, and the copper could be stabilized by the phosphorus in the sludge during the co-incineration [114]. The co-incineration of municipal solid waste and sewage sludge could cause slagging, corrosion, and deterioration of materials in the incineration due to the presence of high contents of alkali and alkaline earth metals. The alkali and alkaline earth metals normally exist as carbonates in the reaction tower, and the slagging processes were affected by the soda manufacturing process. The transformation and deposition of alkali and alkaline earth metals boost the slagging and hinder the heat transfer efficiency. Sludge granulation technology and longer furnace working times were employed during municipal solid waste and sludge co-incineration to lessen the discharge of alkali and alkaline earth metals [110]. The co-incineration of sewage sludge and municipal solid waste could increase the mercury content in the incineration ash and lower the amount of mercury emitted into the atmosphere. When the sewage sludge content increased to 50–75  wt% of the feedstock, the direct toxicity of mercury in incineration ash was decreased due to the presence of less hazardous chemical forms of mercury [115]. Sun et  al. [115] explained that more gaseous mercury would be oxidized to Hg2+ during the cooling process, which resulted in less environmental risk to the environment.

8.6.3 Co-incineration of Other Wastes During the Covid-19 pandemic era, a high number of medical wastes were generated, which mainly consisted of hazardous waste. Co-incineration could apply as an emergency disposal method to manage the high disposal of medical waste.

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Co-incineration of clinical waste with municipal solid waste in the municipal solid waste incinerator was applied as an emergency treatment method during the Covid-19 pandemic. When the clinical waste co-incineration ratio increased from 0 to 20 wt%, the ash contents and lower heating values of co-incinerated waste feedstock as well as the hydrochloric acid concentration in the flue gas were risen significantly. Although the contents of the major elements and nonvolatile heavy metals in the air pollution control residues rose during the co-incineration, they were still within the reported ranges. However, potential boiler corrosion might occur due to the increase in the alkali metals and hydrochloric acid [116]. According to the [117], the co-incineration of medical waste with municipal solid waste gave the lowest environmental impacts due to environmental benefits generated by power generation; however, the co-incineration of medical waste with hazardous waste gave the highest impacts due to high energy consumption. The co-incineration facilities need to be extensively redesigned to reduce the infectious danger and adapt to infectious healthcare waste. The fly ash emission factor increased when the waste ratio increased. The co-­ incineration of bituminous coal with PVC generated the highest fly ash emission factor and PM1. The co-incineration of all the wastes produced almost up to 100% [118]. Table 8.1 represents the fly ash emission factor, and different particulate matter shared in fly ashes when the bituminous coal was co-incinerated with different wastes. Polyvinyl chloride e-waste contains highly chlorinated thermoplastic, which generates toxic and harmful pollutants such as chlorinated organic compounds in the surrounding. Co-incineration of the PVC e-waste with the sewage sludge could reduce the emission of PCDD/F and dioxin-like polychlorinated biphenyl. If the inhibition ratio was increased to 0.75, the PCDD/F formation was fully inhibited and dioxin-like polychlorinated biphenyl formation was reduced to 95% [119].

Table 8.1  Fly ash emission factor (g/kgfuel) and PM1, PM2.5, and PM10 share in fly ashes (%) [118] Fuel/mixture EFash PM1 PM2.5 PM10 Fuel/mixture EFash PM1 PM2.5 PM10

PVC 5% 4.05 33.4 63.9 99.9 EPDM 5% 3.89 43.5 74.8 100

10% 5.93 36.8 68.0 99.9

15% 7.44 46.1 78.7 99.9

10% 5.01 37.8 62.1 99.3

15% 7.38 44.1 68.6 100

PE 5% 10% 3.43 4.25 40.1 42.1 83.0 81.5 100 100 Wastepaper 5% 10% 2.58 1.50 50.8 50.4 87.2 86.1 100 100

15% 4.51 37.7 76.7 100 15% 1.86 50.9 87.1 100

Tires 5% 1.65 42.3 67.0 100 Coal 100% 3.61 42.9 75.3 100

10% 1.96 48.4 72.1 100

15% 3.57 26.9 63.4 98.7

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8.7 Case Study of Waste Incineration 8.7.1 China In China, a separate collection method in the incineration had been applied, and those combustible wastes were sent to the incineration, while those noncombustible wastes were directly disposed of in the landfill. The separated collection of municipal solid waste in the incineration had the best performance in energy balance and greenhouse gas emission reduction. Although the semi-aerobic landfill structure had almost similar greenhouse gas emissions to separated collection incineration, the municipal solid waste incineration and the greenhouse gas emissions for the separated collection incineration were completed in the first 20-year period. In contrast, the greenhouse gas emissions of the semi-aerobic landfill would continue for approximately 50 years. Thus, separated collection incineration was considered an ideal waste management method due to low greenhouse gas emissions [120]. Chen et al. (2022) [121] proposed a hybrid design in which anaerobic digestion and incineration were used to dispose of the organic waste and municipal solid waste to achieve high-efficiency waste-to-energy and reduce costs. The mechanism of the hybrid design to obtain high-efficiency waste-to-energy was the utilization of the biogas generated from the anaerobic digestion by the gas turbine, and the hot exhaust of the gas turbine was used up to boost the steam cycle of the incineration plant through steam superheating, steam reheating, feedwater heating, and air preheating. Figure 8.5 shows the energy flow in the hybrid system.

Fig. 8.5  Energy flows in the hybrid system [121]

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Lhasa City has a special geographical distribution that caused the limitation of energy utilization of municipal solid waste. Separating food waste from municipal solid trash should be used since it might lower the moisture content of municipal solid waste, which would help to reduce the high energy consumption in garbage incineration. Food waste contains high moisture content, which requires high energy consumption [122]. Wen et al. (2019) [123] revealed that the landfilling, composting, and incineration methods produced 86–98% of carbon pollutants in the environment. The incineration technologies would produce flue gas as a secondary pollutant, and the carbon pollutant mitigation in the gas–liquid interface significantly increased when improving the incineration flue gas treatment if wastewater treatment facilities were not used or constructed; thus, it caused more serious environmental impacts [123]. Circulating fluidized bed incineration was utilized as a waste-to-energy system in China to achieve energy recovery from municipal solid waste. The incineration of waste-to-energy could obtain remarkable benefits by maximizing overall energy efficiency and reducing emissions. The municipal solid waste incinerators in China could be effectively enhanced by regulating a more stringent emission standard, as well as improving the level of source-separated collection [124]. A survey by Zhou et al. (2022) [125] found that those residents that stayed 6000 m away from waste-­ to-­energy incineration facilities had a higher level of perceived risk than those who stayed near the waste-to-energy incineration because those who stayed farther away had a higher level of education and were more concerned about the environment and health risks associated with the project. Zhang et  al. (2021) [126] revealed that waste incineration was unpleasant, dangerous, and destructive to the residents, while it was a mature technology which could convert the waste into energy to gain huge profits for enterprises. Waste incineration was preferred by the government because it could reduce waste effectively in a shorter time and given its low cost. Ji et al. (2022) [127] found that the toxic equivalent and major congeners of PCDD/Fs were much higher in the sera of the downwind residents than in the upwind. However, there was no significant difference between the PCDD/Fs concentrations between downwind and upwind and the samples of air, soil, and dust. The age-­ adjusted mortality was also much greater for residents downwind of municipal solid waste incinerators than upwind, which would increase the risk of dying from cancer for those who stayed near the incinerators. The metal concentrations and contamination levels were the highest near the center of the municipal solid waste incineration in northeast China and decreased away from the center. Titanium was found to have the highest value among other heavy metals in soils [128]. Table  8.2 shows the metallic concentrations and pH values in soils that are affected by municipal solid waste incineration in northeast China. Miao et al. (2022) [129] stated that the medical bottom ash from the mobile emergency incinerator contained high chlorine content due to the increasing usage of chlorinated disinfectants and physiological saline solutions during the Covid-19 pandemic. The medical bottom ash also contained a high amount of calcium when incinerated with polypropylene due to the added calcium carbonate, which caused the medical bottom ash to be in alkaline conditions and the leachability of heavy metals reduced.

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Table 8.2  Summary of metallic concentrations and pH values in soils [128] Program pH Li Cr Ti Ni Mn Zn Cu As Hg Cd Pb

Min (mg/ kg) 5.23 5.09 31.56 2422 12.32 284.5 26.14 7.86 6.84 0.010 0.029 20.06

Max (mg/ kg) 11.09 54.71 319.2 6128 55.83 1192 1997 533.6 67.65 0.350 11.89 479.8

Mean (mg/ kg) 7.05 22.65 84.89 3161 30.18 613.2 177.0 50.82 15.98 0.051 0.656 53.41

SD (mg/ kg) 1.35 7.21 56.90 681.8 8.30 155.3 425.7 111.4 11.88 0.050 1.97 90.55

CV 0.19 0.32 0.67 0.22 0.27 0.25 2.41 2.19 0.74 1.01 3.00 1.70

Grade II (mg/ kg) – – 200 – 50 – 250 100 30 0.3 0.3 300

BV (mg/ kg) 7.20 25.3 46.8 3900 22.8 620 55.9 21 8.9 0.08 0.075 19.6

Xu et al. (2019) [130] suggested a new solution to reduce the PCDD/Fs concentration emitted from municipal, medical, and hazardous waste incinerators by installing the REMEDIA™ Catalytic Filter System. There are some advantages to introducing the REMEDIA™ Catalytic Filter System in the incineration plant, such as the gas-phase PCDD/Fs are destroyed, the system is a passive solution, and PCDD/Fs-contaminated solid residues are reduced. With the REMEDIA™ Catalytic Filter System, the total PCDD/Fs could be eliminated up to 98.4% and the particulate matter could be removed up to 99.95% [130]. Yang et al. (2021) [131] redesigned the municipal solid waste supply chain by changing the collection and disposal method. The waste was sorted and separated before transferring it to the disposal site to reduce the mutual pollution between the wastes. The waste incineration could be enhanced by optimizing the collection and transportation mode.

8.7.2 South Korea Jung et al. (2022) [132] mentioned that incineration was not suitable for disposing of end-of-life vehicles from the automotive industry because it produced toxic chemicals in the environment. Pyrolysis was recommended by using carbon dioxide as a reaction medium to dispose of end-of-life vehicles. The harmful aromatic compounds produced during the pyrolysis process, such as benzene and aniline, were converted into value-added syngas (hydrogen gas and carbon monoxide), in which nickel was used as a catalyst. Kang et al. (2020) [133] revealed that the greenhouse gas emissions of waste incineration generated approximately 43% of the total greenhouse gas emissions, and carbon dioxide was mostly found from the waste incineration. There was no seasonal variation in the waste composition except for wood. The wood waste was high during autumn due to a large number of leaves and

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branches being generated in autumn. The seasonal impact on the municipal solid waste incinerators was low in Korea due to the high recycling rate of waste treatment, and the food waste was treated separately [133].

8.7.3 Europe In Spain, the source separation and biological treatments were considered to reduce the amount of municipal solid waste fed to the incineration resulting in protecting the environment and human health and promoting recycling. The incineration phaseout jeopardizes landfill reduction. Although enhancing the source separation and biological treatments to the detriment of incineration is not sufficient to reduce landfilling below the current rate, the phaseout incineration could decrease the impact on ecotoxicity, human toxicity cancer effects, ozone formation, photochemical, marine eutrophication, terrestrial eutrophication, and acidification [134]. Bandarra et al. (2021) [135] indicated that the waste-to-energy plant in Spain had generated approximately 474 kilotonnes/year of incineration bottom ash, of which 41% of the incineration bottom ash had been landfilled, and the remaining incineration bottom ash was majorly used as secondary material in civil engineering and the metals in the incineration bottom ash was recycled. In Italy, Pivato et  al. (2018) [136] revealed that incineration had generated a higher amount of global warming gases (methane, carbon dioxide, and nitrous oxide) into the atmosphere than landfill. The emission of toxic gases could be reduced by redesigning the afterburner chamber and involved installing an additional section (Fig. 8.6). When the afterburner chamber volume was increased, the residence time of flue gases and their circulation in the afterburner chamber increased, which could effectively reduce the emission of carbon compounds (carbon monoxide and total organic carbon) from the chamber [137]. However, incineration was not suitable for treating the sewage sludge because it could bring higher environmental impact and high operation cost, and it requires high energy compared to anaerobic digestion and material recovery methods [138].

8.7.4 Malaysia Lee et al. (2022) [139] indicated that waste-to-energy incineration had a negative net greenhouse gas emission when disposed of the plastic waste, which is more environmentally preferable compared to the sanitary landfill. The waste-to-energy incineration could achieve negative net greenhouse gas emissions due to higher greenhouse gas savings obtained through cleaner electricity generation as compared to conventional power production. The greenhouse gas saving could further enhance if the energy conversion efficiency of waste-to-energy could be increased to be greater than 30% for greater electricity generation. A proposed environmental sustainability

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Fig. 8.6  Rotary combustion chamber and afterburner chamber with additional section [137] may need permission

Customer/ Consumer 1. Bring reusable tumbler 2. Throw plastic cups into plastic waste bins 1. Use paper or biodegradable cups 2. Provide discount to encourage use of tumbler

Bubble Tea Vendors

1. Supply renewable source generated electricity to vendors

NGOs raise fund to provide financial support

1. Enforce regulation on plastic littering 2. Locate more plastic waste bins at bubble tea hotspots Sell renewable electricity from plastic waste

Government 1. Enforce regulation on air emission

2. Enforce regulation on sorting and disposal of plastic waste

Waste Management Company (WTE Incinerator)

2. Provide financial support 3. Do a contract agreement

Collect sorted plastic waste from bubble tea vendors

Transport plastic waste

Waste Collector Company

Fig. 8.7  Proposed environmental sustainability framework for plastic waste management in Malaysia [139]

framework for plastic waste management was applied by the Malaysian government to deal with the increasing solid waste issue (Fig. 8.7) [139]. Incineration was applied to treat the ammonia compound in the wastewater. Two processes caused the production of nitrous oxide, such as oxidation of nitrogen at high temperatures (thermal

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NOx) and the oxidation of liberated nitrogen from ammonia (fuel NOx). Thermal NOx had a greater effect than the fuel NOx due to the total liberated nitrogen molecules from the intended concentration of ammonia in the wastewater being less when compared with the number of nitrogen molecules in the combustion air. When the operating temperature of the incinerator reduced, and the ammonia concentration increased, the production of nitrous oxide decreased [140]. Paul (2021) [141] revealed that incineration is the best thermal technology for solid waste management in Malaysia due to it being capable of catering to the country’s highly heterogenous waste and financially feasible compared to pyrolysis and gasification.

8.7.5 India Yadav and Samadder (2018) [142] indicated that the applicability index of incineration was the highest for plastics, polystyrene, polythene, sugarcane bagasse, paper, cow dung, coconut shell, wood, cardboard, textile, and leather wastes due to high calorific value. Due to the high calorific value, volatile organic carbon, and low ash content in the waste components, incineration had high availability index and would be the most favorable municipal solid waste management for Dhanbad City. A new Pythagorean fuzzy-based decision-making methodology had been developed to determine which treatment technologies were suitable for medical waste management in India. The result showed that incineration could be an effective treatment method, but it requires high cost and has an adverse impact on the environment and public health; thus, it is not suitable for medical waste treatment technologies [143]. At Uttarakhand, the biomedical waste generated approximately 527 kg/day, and the common biomedical waste treatment facility requires to operate an incinerator for 3.30 hours, autoclaving machine for 4 hours, and a shredder for 20 minutes daily as per the calculated load [144]. During the Covid-19 pandemic, biomedical waste generation increased rapidly, especially the face mask in Maharashtra. Incineration was used as one of the waste management methods to dispose of biomedical waste, but the treatment facility had reached its limited capacity due to the high disposal of biomedical waste; thus, modification of incineration was needed. The PM10 generation from incineration was the highest, followed by nitrous oxide, carbon dioxide, and sulfur dioxide [145]. Manupati et al. (2021) [146] indicated that incineration was the most suitable treatment technology for healthcare waste disposal because it could reduce the waste volume and eliminate pathogens and hazardous waste organics as well. However, we cannot ignore the environmental impacts arising from incineration.

8.7.6 Iran The incineration and landfill with transportation consumed approximately 406.08 GJ of energy, and most of the energy consumption was related to transportation. The incineration had a lower rate of daily greenhouse gas emissions, which was

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Table 8.3  Thermodynamic performance of the combined heat and power landfill and incineration system [148] Parameter Total energy input to the system (MW) Total exergy input to the system (MW) Fuel consumption (kg/s) Net electric power generated (kW) Mass flow rate of produced steam (kg/s) Total energy efficiency (%) Total exergy efficiency (%)

Landfill system 3.047 3.183 0.172 946 0.485 76.7 73.4

Incineration system 12.1 19.12 2.314 1824 40 56 35.34

4499.07 kg CO2 eq, than the landfill. The incineration could reduce the release of toxic factors, resulting from the prevention of leaching of buried or abandoned toxic wastes [147]. Ghasemi and Moghaddam (2020) [148] revealed that the combined heat and power landfill had better thermal and exergy effectiveness than combined heat and power incineration (Table 8.3). Based on the environmental analysis, the landfill system had lower greenhouse gas emissions compared to the incineration plant. Zarea et al. (2019) [149] mentioned that the incineration and anaerobic digestion system in Ahvaz was the best waste management strategy due to the recovery of energy and low amount of final ecotoxic solid waste. However, the system had the highest photochemical oxidant impacts, which were influenced by the thermal treatment and anaerobic digestion due to the high emission of nitrous oxide and methane production.

8.7.7 Other Countries In Indonesia, incineration is not suitable for managing the polyethylene terephthalate bottle waste because it would be managed in a similar manner to other municipal solid waste, and high electricity resources were required. If the separation of polyethylene terephthalate bottle waste within the collection system was not possible and contaminated polyethylene terephthalate bottle waste could not be reused, the incineration could be accepted [150]. The incineration system was applied in Phuket, Thailand, to manage municipal solid waste (Fig.  8.8). The incineration required high operation and maintenance costs and professional workers to operate the system. The incineration emitted greenhouse gases at 776.30  kg CO2eq/ton; thus, energy recovery was needed to reduce greenhouse gas emissions [151]. In Brazil, the incineration associated with anaerobic digestion would produce the highest electricity generation, which can generate 6,651,349 MWh per year because a high number of papers and plastics were disposed of in this system. However, this system only achieved 7% avoided emissions. Although there was low electricity generation from the incineration associated with anaerobic digestion due to the low amount of paper and plastics, it had the highest avoided emissions, achieving 94%

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Fig. 8.8  Flow chart of the incineration process, the waste disposal center, Phuket [151] may need permission

of the maximum possible value [152]. Engelmann et al. (2022) [153] indicated that the anaerobic digestion and incineration system must be implemented for long-term solutions in Brazil because it could bring considerable gains, especially the energy performance. In Ghana, incineration was the most suitable waste-to-energy technique to manage municipal solid waste based on the analytical hierarchy process. The incineration had lower capital and operational costs compared to other thermochemical processes, such as pyrolysis and gasification [154]. In South Africa, a novel hybrid multicriteria method based on the IDOCRIW and TOPSIS was proposed to determine the appropriate waste-to-energy technologies for distributed generation. Based on this method, anaerobic digestion was the most favorable technology, with 0.9724 relative closeness to the ideal solution, while incineration was the worst technology, with a closeness of 0.6474. Due to excessive dioxin and furan emissions, incineration was not the best option [155]. In Japan, the total energy efficiency could be improved by using the exhaust heat produced in the incineration plant to dry sewage sludge in the companion wastewater treatment plant. When municipal solid waste was co-incinerated with sewage sludge, it could save up to 35% of total annual costs and reduce carbon dioxide emissions by up to 1% [156]. In Sri Lanka, the incineration had been approximated to produce 20.3 MW of total power generation capacity and 129.86 GWh of annual exported electricity. Only 27% of municipal solid waste would be incinerated via the proposed 500 tonnes to promote the circular economy, and the remaining would be recycled or used to generate biogas and organic fertilizer. Waste segregation and

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removal of nonflammable materials employed in the incineration could enhance the fuel feed quality; thus, the efficiency of the waste-to-energy plant would be enhanced, and the operational and maintenance cost would be reduced [157].

8.8 Challenges and Future Perspectives Although waste incineration can aid in reducing waste effectively, this method can also bring some side effects to human health and the environment. The most serious pollution that is produced from incineration is the emissions of toxic gases such as nitrous oxide and dioxin. The incineration bottom ash contains various toxic pollutants such as heavy metals, dioxin, and polycyclic aromatic hydrocarbons. Those contaminants in the bottom ash shall reduce to prevent serious pollution issues to happen. Since incineration decomposes waste through a thermal process, it will cause high greenhouse gas emissions and global warming. The operational and maintenance cost of incineration is high compared to the landfill. Further research needs to be done to reduce the operational cost of incineration and the greenhouse gas emissions from incineration. Pretreatment can be carried out on municipal solid waste incineration fly ash to improve the quality of the final products for construction applications. Those hazardous wastes shall undergo pretreatment before sending to incineration to prevent the leakage of pollutants into the environment. Co-incineration is one of the methods to overcome the high disposal of waste generated in the environment. Although co-incineration can reduce waste in the environment, the optimum mixing ratio must be determined to achieve high performance, and the method is not suitable for long-span service. Not all the waste can be sent for co-incineration; segregation must be implemented to reduce the burden of incineration. Various researchers indicated that incineration is one of the waste-­ to-­energy techniques that produces heat and power being supplied to the residents, but not all municipal solid waste can produce high energy generation. Energy recovery from incineration requires professional workers to operate. Thus, research on energy generation from different solid wastes in incineration needs to be conducted. Cost–benefit analysis and life cycle assessment can be carried out simultaneously for the incineration and the municipal solid waste incineration fly ash to achieve the maximum environmental and economic benefits. Lastly, robust guidelines and supportive policies, laws, and regulations shall be implemented to protect the environment and humans.

8.9 Conclusion The waste incineration technique is one of the waste-to-energy technologies that can reduce waste effectively and generate energy. However, the technology will generate high amounts of toxic gases such as dioxin and nitrous oxide, requiring

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high energy and operational cost as well. The residues that are generated from the incineration are incineration bottom ash or fly ash which can also be known as hazardous waste because it contains a high number of pollutants that will affect the environment and human health. Various studies have found a way to treat the incineration fly ash before discharging it to the landfill. Water-washing and carbonation treatments are common treatments to treat the leaching of heavy metals in incineration fly ash. The alkali activation with water washing can help remove the soluble salts and prevent the leaching of heavy metals from the incineration fly ash. Since the incineration fly ash contains a high concentration of heavy metals, stabilization and solidification of the heavy metals are needed to prevent the leaching of heavy metals. Most of the incineration fly ash can be used as a replacement in construction materials such as cement and fine aggregates to enhance the mechanical properties and reduce the leaching of heavy metals. Although incineration fly ash can be applied to construction materials, an optimum mixing ratio is required because a high replacement ratio will reduce the mechanical properties of the materials. Co-incineration is advised to reduce the overloaded of incineration, such as co-incineration in cement kilns, co-incineration of municipal solid waste with sludge, and co-incineration of municipal solid waste with other wastes, to overcome the high disposal of municipal solid waste through incineration. However, co-­ incineration is not suitable for long service; alternative techniques are needed to overcome the high disposal of waste. Many case studies indicated that the residents staying nearby the incineration plant are being affected due to the high emission of toxic gases generated from the plant. Thus, the laws and regulations for incineration need to be enforced to protect the environment and humans.

Glossary Combined heat and power  The concurrent production of electricity or mechanical power and useful thermal energy from a single source of energy Confederation of European Waste-to-Energy Plants  The umbrella association of the operators of waste-to-energy plants, representing about 400 plants from 22 countries Dictionary of Occupational Titles  A publication produced by the United States Department of Labor which helped employers, government officials, and workforce development professional Environmental Protection Agency An independent executive agency of the United States federal government tasked with environmental protection matters European Environmental Bureau  A network of around 170 environmental citizens’ organizations based in more than 35 countries Occupational Safety and Health Administration A large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces

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Resource Conservation and Recovery Act  The principal federal law in the United States governing the disposal of solid waste and hazardous waste Toxicity Characteristic Leaching Procedure  A chemical analysis process used to determine whether there are hazardous elements present in the waste

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Chapter 9

Technologies for Removal of Hazardous Volatile Organic Compounds from Industrial Effluents and/or Potable Water Sources Rosnani Alkarimiah, Nursyafi Amila Hilmy, Hamidi Abdul Aziz, Lawrence K. Wang, Mu-Hao Sung Wang, and Yung-Tse Hung

Acronyms VOCs MVOCs OVOCs VVOCs CFPPs PM NO2 CETPs RTO RCO

Volatile organic compounds Microbial volatile organic compounds Oxygenated volatile organic compounds Very volatile organic compounds Coal-fired power plant Particulate matter Nitrogen dioxide Common effluent treatment plant Regenerative thermal oxidation Regenerative catalytic oxidation

R. Alkarimiah (*) · N. A. Hilmy Environmental Engineering, School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia e-mail: [email protected]; [email protected] H. A. Aziz Environmental Engineering, School of Civil Engineering, Solid Waste Management Cluster, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia e-mail: [email protected] L. K. Wang · M.-H. S. Wang Lenox Institute of Water Technology, Latham, NY, USA e-mail: [email protected]; [email protected] Y.-T. Hung Department of Civil and Environmental Engineering, Cleveland State University, Strongsville, OH, USA e-mail: [email protected]; [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 L. K. Wang et al. (eds.), Waste Treatment in the Biotechnology, Agricultural and Food Industries, Handbook of Environmental Engineering 27, https://doi.org/10.1007/978-3-031-44768-6_9

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Hydrogen chloride Sulfur dioxide Vacuum ultraviolet Lower explosive limit Activated carbon Municipal solid waste

9.1 Introduction Volatile organic compounds, or VOCs, have a considerable impact on the production of both ozone and fine particles. VOCs are also responsible for a great deal of damage that is inflicted on human health and are essential components of the troposphere. Volatile organic compounds (VOCs), which are produced by a variety of industrial processes, are viewed as pollutants since they can have an adverse effect on one’s health and emit disagreeable odors when inhaled. Along with other pungent organics like amines, odorous VOCs like mercaptans pose a particular challenge in landfill sites, sewage treatment facilities, and sludge disposal areas. Chemicals known as volatile organic compounds (VOCs) easily vaporize or become gases at ambient temperature and pressure. Transportation and industries that use solvents, like printing and petrochemical processing, are the main sources of man-made VOC emissions into the atmosphere. Organic substances known as VOCs have the ability to volatilize and take part in photochemical processes when a gas stream is discharged into the surrounding air. VOCs make up almost all of the organic chemicals utilized as chemical feedstock and solvents. The vaporization of organic chemicals employed in industrial operations is the main source of VOC emissions. Water contains significant concentrations of a class of dangerous contaminants known as volatile organic compounds (VOCs). Urban activities and industrial processes, including those in the chemical, pharmaceutical, pesticide, and tanning industries, have employed a great deal of synthetically created VOCs. Water contains significant concentrations of a class of dangerous contaminants known as volatile organic compounds (VOCs) [1]. VOC emissions can be reduced using a variety of methods. Utilizing materials with naturally low concentrations of VOC components will limit the discharge of VOCs. Additionally, the processes can be altered to minimize the amounts lost as fugitive emissions. Mercaptans are removed from VOC streams using physical, chemical, and biological treatment methods such as chemical oxidants, acid–alkali scrubbing, and activated carbon adsorption. Add-on control systems, such as thermal oxidation, catalytic oxidation, adsorption, condensation and refrigeration, and biological oxidation, can be utilized when these techniques are not applicable or not sufficient. For VOC emissions reduction, an essential criterion is the identification of the emission source. The current conventional monitoring procedures involve installing

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atmospheric stations for long-term monitoring of the nearby VOCs and then modelling the VOC data for source inquiry. These techniques are used to monitor the regional features of VOCs and identify their pollutant sources. Despite being able to identify the type of pollutant emission source, this approach is unable to pinpoint the emission site [9]. There are already various “end-of-pipe” solutions that can successfully lower VOC emissions. Although this is the case, the implementation of these technologies will often lead to a marked rise in facility costs, downtime, and/or maintenance. Facilities managers learn after the deployment that they must devote a significant amount of time and resources to managing and running a system that, by itself, is not “a value-added” process and, as a result, does not increase the facility’s total productivity. The end result is the development of a technology that performs its intended functions but does not perform those activities in the most effective or productive manner possible.

9.2 Sources of VOCs Harmful aromatic hydrocarbons are chemicals that are released into the air at room temperature. Increased VOC emissions may result in dangerous concentrations of these poisons in the atmosphere, resulting in poor air quality, which could be detrimental to human health. There is a wide range of different emission sources at the commencement of VOCs. Each of them has its emission characteristics. These organic compounds are nearly prevalent. They are the results of other activities that are necessarily taken and are present in many of the items that millions of people consume regularly. Here are some of the different sources of emission: • VOCs in the indoor environment • VOCs in the outdoor environment • VOCs in nature

9.2.1 VOCs in the Indoor Environment The major VOC sources in the indoor environment are usually building-related materials such as furniture and equipment and household-related products. Some causes, such as human activity and the usage of office supplies, may potentially have an impact depending on spatial and temporal patterns [41]. The VOCs released by building materials may come from various sources of pollution. The first pollutant is the primary pollutant source that emits free (non-bound) VOCs. Low-molecular-weight VOCs, such as solvent residue, additives, and unreacted source chemicals, are typically the main pollutants. An example of this pollutant is monomers.

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Secondary pollutants include VOCs that are chemically or physically bonded. It is produced or released as a result of several reactions. The reactions include chain scission, desorption, oxidative degradation, acidity or basicity in the material, cleaning agents, mechanical wear and maintenance, and deco positions. Another instance of adsorbed VOCs is known as hydrolytic breakdown emissions. Examples of building materials related contributions of VOCs are carpets, rubber, vinyl (PVC), gypsum board, particle board, sealant, paint, lacquer, varnish, thermal insulation textile, vapor barrier, ventilation system, and wallpaper. There are some examples of building materials that contain VOCs. The material has a different class in emission testing and field investigation. A renovation like changing a new wallpaper or painting process will raise the level of VOCs, but it will return to a normal level within 4  months. After office refurbishment, it has also been demonstrated that the air quality will decline for 6–8 months. The emission degradation greatly depends on the types of the different materials, and it may continue for a year for some materials. The study by this research [37] stated that the average half-lives of several VOCs in new structures were measured to be between 2 and 8 weeks. The timescale for the emission of VOCs ranges from weeks but sometimes continues to years. After the VOC emission, some emissions occur, such as oxidation degradation and desorption. Table 9.1 lists the selected related human activities that contribute to the VOC emissions. The activities exhibit a wider range of VOC classes than construction material emissions. The impact of exposure is crucial in locations with a poor air exchange rate and low ventilation efficiency. The author [44] stated that the sources associated with human activity are point sources that are close to the inhabitants and create patterns of spatial and temporal concentration. The emission occurs within minutes or hours, depending on how many people are participating in the activities that can cause VOC emissions. Office works include photocopies and smoking, which can cause VOC emissions. Certain actions could have the long-term effect on emissions like painting. The emissions from using personal care products and fragrances may also add Table 9.1  Selected examples of VOC sources (human activity) Sources Correction fluid Dishwashing Dry cleaning Household products Painting Personal care products Room freshener Shampoo Showering Tobacco smoke (E.T.S.) Wax/polish

Typical VOCs emitted Chlorinated hydrocarbons Ethanol Chlorinated hydrocarbons A variety of different non-polar and polar VOCs including fragrances Alkanes, glycols, glycol ethers, Texanol Siloxanes oxygenates Alkanes, limonene, fragrances Ethylene glycol butyl ether Chlorinated hydrocarbons Aliphatic hydrocarbons. Aldehydes, benzene, styrene A variety of different VOCs

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considerably. The VOC emission can be absorbed by other materials and dust particles and can be handed over at a later stage, hang on the climatic conditions [30]. Only in North America do wet photocopying machines emit VOCs into the air [8]. Thirty-one VOCs were found to be released from paper processing by photocopiers, laser printers, and matrix printers, with a wide range of volatility and persistence [56]. Various emissions can be characterized as odors or contact allergens. The release of ozone and other particles from photocopying and laser printing equipment has received a lot of attention. The handling of carbonless copy paper is another potential VOC source. For up to 12 months, construction materials appear to be the dominant major source of pollution. The emission reduction depends on their emission characteristic. The constant usage of office supplies like photocopiers and printers results in daily pollution contributions. It has been suggested that these daily periodic sources are responsible for electronic device malfunctions. There are some VOCs that are thought to be produced microbiologically (MVOCs). Conversely, some of them may potentially have formed through the material degradation process. Alcohol, ethanol, and ketones are the major of MVOCs. Several MVOCs found have very low odor thresholds, for example, geosmin, unsaturated alcohol, and aldehydes [46]. Compared to reference buildings, the total MVOC concentrations in odor-­ problem buildings were greater. The ability of indoor microbes to produce volatile organic compounds (VOCs) has been demonstrated in cultivation studies, albeit substrate composition appears to be even more important than incubation time and microbial growth rates.

9.2.2 VOCs in the Outdoor Environment The places where harmful chemicals can be encountered outside the home are traffic and area that have a lot of cars, factories, other industrial buildings, and recycling areas. The combustion of gasoline gives off some harmful chemicals. Use the air filtering system in the vehicle and keep the windows rolled up when trapped in traffic. For the factories, living near the facility that makes products having to do with plastics or petroleum or that is involved in any form of large-scale industry, it is likely to emit high amounts of toxins into the air and maybe even the water. To ensure that this facility isn’t endangering nearby homes and other structures, it may be a good idea to test the area’s air and water quality, depending on how close it is to the facility. The recycling area usually has a burning center. The burning causes an increase in the volatility of these chemicals, increasing emission rates. So concentrations of toxic chemicals are likely to be higher in areas where incineration takes place.

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9.2.2.1 Traffic and the Area with a Lot of Cars The climatic conditions, notably wind speed and wind direction, have a significant impact on the VOC characteristics and sources. Generally, these two types of characteristics were connected to local transportation. VOCs are a wide range of typical organic compounds present in the atmosphere that may be harmful to human health either right away or over time. VOCs have various sources. Many of the sources at a certain place include both anthropogenic and biogenic emissions from things like factories, cars, and secondary formations brought on by oxidation [29]. Additionally, VOC travels regionally over distances of up to hundreds of kilometers [50]. In summer, VOCs in metropolitan Shanghai is mostly caused by vehicle emissions and chemical industry solvent use, which together account for more than 55% of VOCs. Other significant sources of VOCs included the secondary formation and regional transfer. The range of the contribution is 15–25%, depending on the weather. Biogenic emission is also considered a source of VOCs during summer [29]. 9.2.2.2 Factories and Other Industrial Buildings The industrial building that causes the high emission of VOC is the power plant. Power generation is crucial to the production of energy and power in China. Coal-­ fired power plants (CFPPs) were a major source of VOCs in China. About 4.1% of the industrial VOC emissions at the national level in 2016 were from CFPPs [21]. In light of the economy’s rapid expansion and people’s rising expectations for a high-quality existence, the demand for power produced by CFPPs will rise. Additionally, it will contribute to the development of PM 2.5 in the environment. The environment and human health suffer long-term detrimental consequences as a result of this. The study shows that VOC emissions from CFPPs are higher overall than those from only the stage of operation, including those from coal mining and waste disposal. This is a result of the role that coal mining and flue gas cleaning system procedures have played [42]. More organic chemicals, in the form of gaseous molecules, are released into the atmosphere. The organic substance that has a saturation vapor pressure above 133.32 Pa at ambient temperature or a saturated boiling point below 250 °C at atmospheric pressure will be exposed to the air. The pharmaceutical manufacturing facility was a significant source of VOCs in industrial activity [53]. The total value of VOC emission from the pharmaceutical factory was established to increase by 1.5 times from 0.26 Tg in 2010 to 0.43 Tg in 2015 [62]. The expansion of the pharmaceutical factory in China due to the rise in medical demand would eventually result in an increase in VOC emissions. Numerous investigations have demonstrated that VOCs from the pharmaceutical business were strong odorants or put people’s health in danger [28].

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9.2.2.3 Recycling Volatile organic compounds (VOCs) are a significant component of the emissions from waste sites and waste processing, such as landfills and recycling. Paper and cardboard, organic trash, and plastics from recycled garbage are the primary sources of VOCs in municipal solid waste facilities [18]. VOCs were primarily produced by mixed paper, food waste, and fresh trash in landfills and recycling facilities. The recycling process needs to burn the waste. Thus, the burning can cause air pollution that consists of VOCs, which can cause a health risk to factory workers and nearby dwellers [1, 18]. VOC-related health impacts can be classified as either carcinogenic or noncarcinogenic. In addition, exposure to VOCs released by solid waste can cause illnesses such as hypochromic anemia, respiratory problems, central nervous system problems, allergy skin reactions, and lung, brain, and kidney cancer [2, 36, 43]. Based on this study, the main species of VOCs that are released from the different processes of paper and cardboard solid waste recycling factories were m,p-­ xylene, limestone, 1,2,4-trimethyl benzene, 1-ethyl-3-methyl benzene, and toluene [38]. In factories that recycle paper and cardboard, workers may have short-term or long-term health impacts. Therefore, the primary sources of VOCs in the paper and cardboard solid waste recycling factory were recycled materials that included VOCs.

9.2.3 VOCs in Nature These poisons can sometimes be found naturally. It’s vital to comprehend how they develop in order to avoid overexposure. The most typical naturally occurring sources of hazardous organics are listed below: • Cattle farms • Plants • Anything burning 9.2.3.1 Cattle Farms Cow farms are one of the main sources of methane emissions. This organic component is particularly volatile in manure, which is a source of one of the most potent greenhouse gases. When compared to other professions like painters and cleaners, farmers had the highest incidence of asthma, according to a large-scale study on asthma in Europe that included over 15,400 participants [23]. It is established that respiratory problems may be brought on by volatile organic molecules. Symptoms of discomfort and irritation could already be present at a concentration of 200 μg mˉ3 of VOCs and above [6]. The measurement of VOCs

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usually focuses on swine production. This is due to the strong odor emissions [45, 55]. Dairy farming and keeping cattle are acknowledged risk factors for respiratory illnesses. This is because the farmers spend most of their time on the farm. The symptoms appeared when working in the stables as well as in residences. Due to the significant odor emissions, measurements of VOCs frequently concentrate on swine production [45, 55]. The concentration of VOCs in stables increases in the spring due to a decrease in air volume per animal. Thus, we might draw the conclusion that it’s conceivable that a substantial portion of the VOCs in the stables came from the animal. It can be acquired directly, such as through their excrement degrading, or indirectly, such as through breathing or sweating. In terms of health effects, most of the farmers complain of respiratory symptoms, such as asthma, rhinitis, or respiratory symptom. There is one link found between VOCs in indoor air and immediate health impacts. These effects often include reversible immune system responses as well as irritation of the cranial nerves for smell and chemical sense [37]. However, other claims suggest that exposure to VOCs can exacerbate preexisting chronic conditions like asthma, in which this irritant process may be involved [54]. The effects were often felt at levels of 25 mg m3 and above. In controlled chamber studies, VOCs caused acute respiratory symptoms in humans as well as mucosal irritation of the eye, throat, and nose [16, 40]. However, the chamber study does not accurately reflect the actual indoor atmosphere. This is due to the oxidants, like ozone, which is added and may react with the VOCs. In other research, it was mentioned that some of these VOCs can be found in common combination compositions. Every disease has a specific pattern of VOCs. Thus, the other disease kinds could not be concealed by the presence of one disease [20, 24, 41]. These diseases can be identified immediately from exhaled air, urine, or cultured cells. 9.2.3.2 Plants VOC defense plants by inducing microbial priming. Recent research has shown that root VOCs aid in drawing healthy microorganisms to soils. Fusarium culmorum-­ infected Carex arenaria roots produced a number of VOCs. This plant has a different profile than healthy ones. It was discovered that Fusarium culmorum-induced Carex arenaria VOCs attracted specific helpful bacteria from a distance of more than 12 cm. Since the translocation capacities of these VOCs were highly variable, it is possible that plants may alter their VOC composition to entice bacteria in a variety of soil situations. Thus, some VOCs are not good things for others, but VOCs are good for defensing plants.

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9.2.3.3 Burning VOCs released from anthropogenic and biogenic sources are crucial to understanding the chemistry of the atmosphere because they can produce ozone and other atmospheric oxidants when exposed to the UV component of sunlight in the presence of nitrogen oxide [5]. According to studies, biogenic sources contribute significantly to worldwide VOC emission, while tropical regions make up the majority of this contribution [10]. The air environment is significantly impacted by the burning of vegetated areas. This is because the important sinks of pollution are converted into sources of carbon, carbon dioxide, nitrogen oxide, volatile organic compound, and carbonaceous particles. Based on this study, the combustion of lignin is not the sole process that releases VOCs when burning biomass [10]. Since pine emissions contain isoprenoids in general and sesquiterpenes in particular, it is likely that evaporation from storage organs such as resin ducts inside the needles mostly determines the VOC pattern. The findings show that biomass is very effective at raising atmospheric acidity by emitting organic acids directly [26]. The generation of secondary organic aerosol and ground-level ozone is significantly influenced by VOCs in the atmosphere [20]. Biomass burning was estimated and more than half of the region’s total VOC emissions came from burning biomass. Transportation contributed approximately 25–30% [7, 43]. One of the biomasses burning sectors, the combustion of biomass as household fuel, was the primary contributor. Alkenes and halocarbons contributed the most to the total of each VOC compound’s mixing ratio. Sensory irritability, nervous system damage, asthma, and cancer are just a few of the acute and long-term health impacts that exposure to VOCs during burning can cause [37]. This study suggested that industrial emission, vehicular emission, and combustion processes are the main sources of anthropogenic VOC [62]. Open biomass burning is a regular activity in rural regions during the harvest season that generates significant VOC emissions. Biomass burning is a common activity because of the lack of suitable disposal methods in Beijing, China [31]. Several studies stated that in rural areas biomass burning is a significant source of VOCs [12, 51]. The health of people and ecosystems may be at risk from the VOC and NO2 emissions from burning biomass [31]. Back-trajectory calculations showed that a significant contributor to atmospheric VOCs is the impact of biomass burning on air masses arriving at the location [62]. As previously mentioned, emissions from biomass burning have a significant impact on local air quality and can travel far from the source [52]. According to some research, the majority of the non-methane organic carbon produced from burning biomass is made up of oxygenated volatile organic compounds (OVOCs) [19].

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9.3 Common VOC Removal Technologies The saved level of VOC depends on the health effect. Try lowering levels in your home if you are experiencing health issues brought on by VOCs. To rule out other significant health disorders that may have similar symptoms if they persist, speak with a doctor. The majority of health-related research has focused on a particular molecule. The negative effects of exposure to chemical mixtures on health are less well understood. There is no Minnesota or federal health-based criteria for VOCs collectively because the toxicity of a VOC differs for each component. The physical and chemical characteristics of VOCs that can affect how they behave include their boiling point, vapor pressure, ability to generate ozone, and their effects on the environment and human health. The raw effluent from the majority of industrial processes contains VOCs, and it is transferred to an effluent treatment facility for treatment and safe release [30]. Many of these small-scale enterprises send their effluent to common effluent treatment plants (CETPs), which collect it and treat it using a variety of techniques, including primary and secondary treatment for VOCs. In this plant, the major hazard to the residential areas around this area is the emission of toxic VOCs. The measurement of VOC emissions from CETPs is a soulless process. It required rigorous fieldwork. For VOC measurement, the estimation of VOC raw effluent and plant operational data was required. For the secondary treatment employing the activation sludge techniques, the removal of VOCs from effluent through air stripping, surface volatilization, adsorption to solids, and biodegradation has been viewed as a major sink (ASP) [39]. The study of biological purifiers has been conducted to remove the VOC. The biological purifier was defined as any VOC removal equipment with a biological component, whether it be microbial or botanical, while the term “botanical purifiers” is used to refer to equipment that uses plants and the accompanying microorganisms. Based on the study and supported by NASA, it has been demonstrated that plants have the potential to effectively remove volatile organic compounds (VOCs) in a sealed chamber [56]. The authors discovered that a number of plants could reduce formaldehyde levels from 19,000 to 46,000  g/m3 to less than 2500  g/m3 in 24 h. The other authors also found out that plants significantly reduced toluene and xylene at indoor air concentrations of 768–887 μg mˉ3 and even the total VOC concentration in an office building during field testing under real conditions [13, 57]. Thus, we can conclude that planting more trees around our house can help in the removal of the emission of VOC. A variety of commonly utilized VOC control methods, including adsorption, absorption, regenerative thermal oxidation (RTO), regenerative catalytic oxidation (RCO), and biofiltration, have emerged [15, 20, 60]. While the absorption approach requires additional wastewater treatment, which would increase the operational

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cost, RTO is not suitable for low-concentration VOCs because it requires large operating expenses to maintain the high temperature. RCO is cost-effective for low-temperature processes, but it would be significantly impacted by changes in the feed rate or concentration of VOCs. In order to reduce the emissions of VOCs, the author advised utilizing biochar. One of the most effective and affordable methods for removing VOCs is sorption. A significant member of the carbon family is biochar. The next common removal of VOC is proper storage and ventilation. Getting more fresh air into enclosed spaces, especially spaces where VOC emission is a risk, can remove pollutants. Air quality indoors is often worse than outdoor air quality under normal circumstances because of the lack of fresh air being allowed in. Opening windows or doors, running a ventilation system, and other simple steps can improve your home’s indoor ventilation. Any VOC concentration in the air in an enclosed environment, such as your house, office, place of business, or indoor public space, can be eliminated using activated carbon air purifiers and filters. It functions by chemically attracting organic pollutants so that the carbon within can absorb them.

9.3.1 Thermal Oxidation VOCs, or volatile organic compounds, are commonly classifiable into a variety of subgroups depending on the traits they exhibit. As shown in Fig. 9.1, according to the boiling point, they can be classified as very volatile organic compounds (VVOCs, e.g., methane, formaldehyde, methyl mercaptan, aldehyde, dichloromethane), volatile organic compounds (VOCs, e.g., ethyl acetate, ethyl alcohol, benzene, methyl

Fig. 9.1  The classification of VOCs [11]

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ethyl ketone, trichloromethane, xylene), or particulate organic matters (POMs, e.g., polychlorinated biphenyl, benzopyrene) [11]. The most common types of VOC reduction systems are those that focus on either destruction or recovery. The oxidation of volatile organic compounds (VOCs) to their most oxidized form—specifically, carbon dioxide and water (for hydrocarbons containing chlorine or sulfur, the exhaust will also include HCl and SO2)—is a key step in the destruction processes. Figure 9.2 shows the categorization of VOC reduction technologies. In a thermal oxidizer, the VOC-filled air stream is heated to gas temperatures that are hundreds of degrees above the organic compounds’ autoignition temperatures. Although they function at extremely high temperatures, thermal oxidizers feature refractory-lined combustion chambers (sometimes referred to as fume incinerators), which greatly increases their weight and dimensions. A fraction of a second to more than 2  s is spent maintaining this temperature in the VOC-filled gas stream. The exhaust gas from combustion chambers walled with refractory frequently has temperatures between 1000 and 2000 °F. VOC destruction efficiency provided by thermal oxidizers often exceeds 95% and frequently exceeds 99%. The substantial fuel consumption needed to heat the gas stream to the level required for high-efficiency VOC destruction is one of the main drawbacks of thermal oxidizers. A portion of this heat is recovered via heat exchangers. Depending on the size of the unit, the heat recovery efficiency of this type of heat exchanger ranges from 30% to 60%. Large regenerative beds are used for heat exchange in some types of thermal oxidizers. These beds offer up to 95% efficiency in heat recovery. These devices, known as regenerative thermal oxidizers (RTOs), require less fuel to maintain the combustion chamber at the required temperature because of the amount of heat that can be recovered and returned to the incoming gas stream. Among all of the VOC control technologies, thermal oxidizers have the greatest range of applications. They work with practically all VOC compounds. For gas streams with VOC contents ranging from extremely low levels (less than 10 ppm) to VOC Source

Source Reduction Adsorption

Add on Measures

Recovery

Condensation Absorption

Destruction

Biological Oxidation

Biofilter

Biotrickling Filter

Thermal Oxidation Bioscrubber

Catalytic

Fig. 9.2  Categorization of VOC reduction technologies [47]

Non-Catalytic

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extremely high levels (approaching 10,000  ppm), thermal oxidizers can also be employed. Rarely are thermal oxidizers employed on gas streams with VOC concentrations above about 25% of the lower explosive limit (LEL). Since it is possible for a short-term concentration surge to surpass the LEL and cause an explosion in the gas stream, this limit is established for safety reasons. The actual gas ingredients determine the 25% LEL limit, which is often in the 10,000–20,000  ppm range. Thermal oxidizers that process VOCs with chlorine, fluorine, or bromine atoms also produce HCl, Cl2, HF, and HBr as by-products of the oxidation process. Prior to the discharge of the gas stream into the atmosphere, these pollutants are collected using a gaseous absorber (scrubber) as part of the air pollution control system.

9.3.2 Catalytic Oxidation While the basic principles of catalytic thermal oxidation are the same as those of thermal oxidation, catalysts are used to improve the reaction kinetics, enabling combustion to occur at a lower temperature and for a shorter period of time. In comparison to thermal oxidizers, catalytic oxidizers work at significantly lower temperatures. At temperatures between 500 °F and 1000 °F, oxidation reactions occur because of the catalyst’s presence. Noble metals (such as platinum and palladium) and ceramic materials are frequent forms of catalysts. Catalytic oxidizers typically destroy more than 95% and frequently more than 99% of VOCs. The technology of catalytic oxidation is recognized as an effective method due to its high economic feasibility, cheap cost, and low levels of secondary pollutants generation. Additionally, it has controlled the selectivity of the by-products and can run at a lower temperature, making it more environmentally friendly [14]. A sketch of a typical catalytic oxidizer is shown in Fig. 9.3. Due to the relatively low gas temperatures in the combustion chamber, there is no need for a refractory liner to protect the oxidizer shell. This reduces the catalytic oxidizers’ overall weight and gives the option of putting the units on rooftops near the source of VOC production. By minimizing the distance, the VOC-laden stream must be conveyed via ductwork; this arrangement can lower the system’s overall cost. A variety of streams that are VOC-rich can use catalytic oxidizers, but they cannot be used for sources that also produce trace amounts of catalyst toxins. Catalyst poisons are chemicals that have an unregulated chemical reaction with the catalyst. Among the typical catalyst, poisons are phosphorus, tin, and zinc. Another potential operational problem is the sensitivity of catalytic oxidizers to chemicals and/or particulate debris that covers or clogs the catalyst surface. The research [14] in their study has been summarized that there is still a lot of scientific questions and obstacles regarding the use of catalytic oxidizers to overcome before VOCs may be removed effectively. In their research they simplify that:

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Burner (Normally Off)

Catalyst Bed

Tubular Heat Exchanger

Gas Inlet

Fig. 9.3  Typical catalytic oxidizer [14]

(i) VOC mixes are always released industrial pollutants. The majority of discussions on VOC catalytic elimination focus on single-component oxidation, whereas combinations of VOCs are rarely oxidized together. A deeper understanding of the interaction may help researchers create affordable catalytic reactors and effective catalysts for industrial applications. As a result, mutual influence on the catalytic oxidation of mixed VOCs should be taken into consideration. (ii) Catalytic oxidation is the most common and efficient VOC removal technology. High energy use must be addressed. A future study might focus on hybrid treatment methods such as adsorption–catalytic oxidation, photo–thermo catalytic oxidation, and plasma–catalytic oxidation for the effective removal of VOCs. (iii) The most common approach for eliminating VOCs is catalytic oxidation into H2O and CO2. This approach efficiently oxidizes VOCs, but it wastes energy and emits CO2. Selective catalytic oxidation of VOCs to usable compounds is a resource-efficient and economically beneficial approach for VOC control. (iv) In situ on-line characterizations using FTIR/DRIFTS, synchrotron radiation, isotopic tracer techniques, GC-MS, and PTR-TOF-MS are necessary for investigating oxidation pathways. A thorough understanding of the elimination pathways, catalyst poisoning, migration, and change of intermediate species during VOC degradation should be highlighted. (v) Most nanoparticle catalysts in the literature on VOC catalytic removal are utilized in industrial catalytic reactors. Preparing monolithic or honeycomb catalysts by depositing nanoparticle-shaped catalysts on suitable substrates while retaining activity, selectivity, and stability is difficult. Meanwhile, [58], the fundamentals of various techniques, methods for developing catalysts, reaction mechanisms, and potential future research directions in

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vacuum ultraviolet (VUV) catalytic oxidation of VOCs have been outlined. In their study, they found that various catalyst improvement strategies have been explored. Some of these can be used in VUV catalyst development. Catalyst immobilization on suitable substrates can increase surface area and VOC residence duration, and some substrates and reactive components have synergistic effects. This helps reduce VOCs. Developing catalysts that can perform both photocatalysis and ozonation is particularly important; considering that any operation can contribute to the oxidation of VOCs, this increases the efficiency of VOC degradation. Hence, VUV catalytic oxidation removes VOCs efficiently. Investigating the mechanism of the VUV catalytic oxidation system will help to improve its performance and design. Studies on the mechanisms underlying VUV photodegradation, photocatalytic oxidation, ozone catalytic oxidation, and their combinations are insufficient. Synergies between these mechanisms are also essential but rarely recorded. Therefore, mechanistic research should include all processes. Study VOC oxidation reaction routes and process synergy.

9.3.3 Adsorption In the realm of environmental research, the elimination of volatile organic compounds, such as hydrocarbons, solvents, hazardous gases, and organic-based odors, is the main use of vapor phase activated carbon. In addition, activated carbon that has been chemically saturated has the potential to reduce the emission of some inorganic contaminants, such as hydrogen sulfide, mercury, or radon. Due to low achievable discharge consents and its cheaper cost/energy treatment profile, activated carbon adsorption is the most used removal technology. Adsorption systems beds are generally used in the following two quite different situations: (i) When there are only one to three organic solvent chemicals in the VOC-laden gas stream, and it is cost-effective to recover and repurpose these molecules. (ii) Since the VOC-laden gas stream comprises numerous organic compounds at low concentrations, it is crucial to preconcentrate these organics before thermal or catalytic oxidation. When properly implemented, the adsorption process will eliminate contaminants to levels that are nearly undetectable. In fact, one of the earliest applications of activated carbon on a large scale was in military gas masks, where the elimination of all contaminants is required. Both simple pollutant mixtures and single-component emissions can be effectively reduced by carbon adsorption. The most common uses of activated carbon in the industrial sector are for the control of process off-gases, tank vent emissions, air purification in work areas, and odor control, either within the plant itself or in relation to plant exhausts. Activated carbon can also be used to purify tank vent emissions. Additionally, off-gases from air strippers and soil vapor extraction remediation operations are treated in the toxic waste treatment area using

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activated carbon. This is carried out to stop the release of dangerous substances into the environment. When analyzing a particular VOC issue in the environment, one of the most important questions that need to be answered right away is what kind of treatment technology should be considered. For a given condition, there are typically a number of therapy approaches that appear to have some benefit. Common activated carbon regeneration methods, including regeneration by hot gases or steam (thermal treatment), demand a lot of energy and reduce adsorption capacity through repeated adsorption/regeneration cycles. As a result, these techniques are not attractive from an environmental or economic point of view. During the adsorption process, molecules of a contaminated gas are drawn to the surface of the activated carbon and accumulate there. Because it has such a vast surface area, carbon is a popular choice for use as an adsorbent. It is created or activated through a process that involves high temperatures and controlled oxidation, and it can be made from a range of basic materials, including coal, wood, and the shells of coconuts. In the field of adsorption separation, zeolites, which are crystalline aluminosilicates with well-defined microporosities, have a pore structure that is one of a kind, as well as a large specific surface area and a high level of stability. This has led to a number of groundbreaking discoveries [32]. Another few examples of common adsorbents are carbon materials, zeolite, clay, silica gel, MOF, organic polymer, and composite materials. Figure 9.4 shows an artist’s impression of an activated carbon particle’s cross section. It’s crucial to remember that almost all of the surface area that is open to adsorption is connected to the makeup of the pores present inside the substance. Take note, as well, of the relative change in the diameters of the pore, which go from being extremely large at the granule surface border to being considerably smaller within the particle interior. During the activation process, different activated carbons are created by striking a balance between the big and small pore volumes in the carbon. This is what gives

Fig. 9.4  Cross section of an activated carbon particle [32]

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each activated carbon its unique ability to perform a specific function. The environment where the pore width of the adsorbent is relatively close to the molecular diameter of the chemical is where contaminants’ molecules tend to adsorb with the highest force. The primary component in the VOCs adsorption of porous carbon materials is their morphological structure, particularly the pore size distribution. According to earlier research, macropores and mesopores boost gas diffusion and speed up adsorption time while serving as the primary adsorption space [27, 32] stated in their study that the development of extremely hydrophobic zeolites with high VOC adsorption capacity is hampered by the fact that increased hydrophobicity is typically accompanied by lower adsorption capacity. New binder-free molding procedures must be developed to produce monolithic zeolite with excellent mechanical strength and unaltered adsorption properties. Despite major advancements in the synthesis of different zeolites, it is still difficult to produce zeolites with a well-­ defined macroscopic structure, sufficient mechanical strength, and high VOC adsorption capability in humid circumstances. Also, [32] found that, through the use of a citric acid sacrifice method, it was possible to create binder-free monolithic zeolite pellets with exceptional water tolerance. These pellets possessed robust mechanical strength, high adsorption capacity, and great water tolerance. Y zeolite pellets have undergone in situ dealuminization, which has resulted in a significant increase in both their specific surface area and their mesopore volume. This has led to better adsorption performance for acetone and toluene. Meanwhile, [61] have determined that NH4HF2 is an excellent dealumination agent that is capable of successfully removing the non-framework Al found in the ultra-stable Y (USY) zeolites. Given that the diameter of the majority of VOCs molecules is 1 nm, the creation of mesopores with diameters of 5 nm in USY will considerably improve the adsorption performance of VOCs molecules. Although the vast majority of organic compounds are capable of adsorbing to some degree on activated carbon, the adsorption process is at its most efficient when applied to substances with a high molecular weight and a high boiling point. A good candidate for adsorption is a compound with a molecular weight larger than 50 and a boiling point greater than 50 degrees Celsius. The following table provides a representative selection of organic compounds arranged according to the amount of adsorption capacity that each one possesses. Organic pollutants are frequently divided into three distinct adsorption categories: weakly, moderately, and strongly. You will notice that nitrobenzene is regarded as an extremely potent adsorber and has a molecular weight of 123 and a boiling temperature of 211 degrees Celsius. Other compounds with similar properties include benzene, which has a weight of 122. On the other hand, a substance that is only very weakly adsorbed is a chemical with a molecular weight of 16 and a boiling point of −161 degrees Celsius, such as methane. In point of fact, the removal of methane using activated carbon would not be cost-effective at this capacity, taking into account all of the practical considerations involved.

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In general, adsorption systems are restricted to sources that produce organic molecules with a molecular weight between 50 and 200. Typically, substances with a low molecular weight do not absorb adequately. During the desorption cycle, it is challenging to remove large-molecular-weight molecules from the adsorbent because they adsorb so strongly. These molecular weights are provided as a general guide, and each circumstance must be analyzed individually to see whether an adsorption system is appropriate. Adsorption systems are applicable for a wide range of VOC values, from less than 10 ppm to about 10,000 ppm. When the total VOC concentration surpasses 25% of the LEL, the upper concentration limit is imposed due to the potential for explosion. Table 9.2 shows the list of organic compounds with their molecular weight, boiling point, and carbon capacity. On the other hand, adsorption systems are not suggested for gas streams that have particle matter and/or high moisture concentrations. This is due to a competition between the gaseous pollutants and the particulate matter and moisture for pore space on the adsorbent material. The adsorption removal efficiency typically surpasses 95% and is frequently in the range of 98–99% for systems that are of the solvent recovery type as well as those that are of the preconcentrate type. When the temperature of the gas being removed is lowered, the efficiency of the removal process increases in both types of units. Table 9.2  Relative absorption rate for different organic compounds Relative absorption rate

Strong GGER

Molecular weight 123 166 165 104 105 128 92 78 88 86 100 99 72 84 53 58 62 64

Nitrobenzene Tetrachloroethane Tetrachloroethylene Styrene Xylene Naphthalene Toluene Benzene MTBE Hexane Ethyl acrylate Dichloroethane Methyl ethyl ketone Methylene chloride Acrylonitrile Acetone Vinyl chloride Weaker Chloroethane Bromotrifluoromethane 149 Methane 16

Boiling point (°c) 211 147 121 145 138 217 111 80 55 68 57 99 80 40 74 56 neg 14 12

Carbon capacity % 51 40 35 25 21 20 20 12 12 7 5 7 4 2 2 0.8 0.7 0.5

neg 58 neg 161

0.13 0.0003

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The features of the contaminant to be adsorbed, the temperature of the gas stream to be processed, and the concentration of the contaminant in the gas stream all have an impact on physical adsorption. The amount of a given pollutant that may be adsorbed on the unit weight of consumed activated carbon under the circumstances of the application is known as the adsorption capacity for that particular contamination. For highly adsorbed compounds, typical adsorption capabilities vary from 5% to 30% of the carbon’s weight. The adsorption condition and the characteristics of both the adsorbent and the VOCs are important factors that influence the behavior of VOC adsorption. The adsorption condition has a greater impact on the elimination of volatile organic compounds (VOCs) and is responsible for dictating both the type of adsorbent used and the layout of the adsorption apparatus. A large number of researchers have looked into how the operating circumstances affect the amount of VOCs that is absorbed [33]. [33] has also studied the use of activated carbon injection in conjunction with a bag filtration system to study the adsorption of VOCs in a coal combustion flue gas environment. The results showed that the micropore volume of AC pore size distribution and mesopore volume were related to how well the adsorption capacity of AC removed toluene and p-xylene. Waste air conditioning could be utilized without the need for desorption, and the removal efficiency of mixed ACs was nearly identical to that of fresh air conditioning when the proportion of waste air conditioning was 25%. They also found that greater mesopore volume and micropore size in activated carbon improved its ability to absorb VOCs. At this point in time, the adsorption process has reached a fairly advanced stage; it demonstrates high efficiency while requiring just a moderate amount of energy. In addition to this, it is able to thoroughly clean potentially hazardous organic waste gas and recover valuable VOCs. As a result, the adsorption of volatile organic compounds has garnered a lot of attention all around the world. The fact that an adsorption process offers passive on-line reserve capacity is another important benefit. In practice, the system is always ready to handle a variety of loads, but it only starts using carbon when there are impurities in the exhaust stream. Even when no pollutants are being treated, other operations may incur considerable fuel or chemical operational expenses. To assess the relative adsorption abilities of various activated carbons, the activated carbon production industry and ASTM have developed a number of standard tests. These tests can help identify the cost-effectiveness and quality of a product as well as if it contains virgin or reactivated carbon. In conclusion, it has been demonstrated that activated carbon can be used for the treatment of a wide variety of pollutants found in the environment. This technology has been tried and tested, and it is not only straightforward to set up but also uncomplicated to run and keep up with. Most alternative treatment methods have among the industry’s lowest average prices for capital expenditures. The amount of activated carbon that is used up in the adsorption process is the primary factor that determines the total amount of money spent on operational expenses.

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9.3.4 Biotreatment of VOC Volatile organic compounds (VOCs) are defined as “compounds having a vapor pressure exceeding 0.1 mmHg at standard conditions and inorganic odor compounds pose a threat to a global ecosystem, human health, and plant vegetation, constituting a significant part of indoor or outdoor pollutions created by gases emitted from certain solids or liquids” [4]. The anthropogenic activity or biogenic emissions of specific reactive hydrocarbon derivatives, which are generated as a chemical by-product of natural transformations, are the source of VOC and aromas in the atmosphere [34]. This can affect human health in long-term exposure. The term “biotreatment” refers to the use of live organisms like bacteria, fungi, or protozoa to process waste or potentially dangerous compounds. Biological air treatment often only works well with low-molecular-weight, highly soluble chemicals with straightforward bond configurations. The clean at the end-of-pipe performance criterion offered by biotechnology entails very low secondary emissions that do not transfer pollution issues from the air to other environmental compartments like water or soil. Bio purifications of off-gases with low volatile component concentrations. This process (Bio purifications) is attracting attention due to its cost-effectiveness, minimal investment and operating expenses, treatment efficiency, and environmental compatibility. Odorant removal procedures are based on microorganisms’ innate capacity to degrade odorous or toxic contaminants from industrial or municipal waste [3, 53]. Based on this study, the gas-phase biofilters used to treat waste gases were filled with compost or other naturally occurring filter beds containing local microorganisms [4]. Several decades ago, it was previously known that fungus in liquid batch cultures could degrade volatile contaminants, mostly non-aliphatic chemicals [21]. However, a thorough investigation into the elimination of volatile substances that fall under the category of non-oxygenated aromatic pollutants was just recently begun. In biofilters, fungi were used to treat air pollution. The capacity of fungi to breakdown the substrate under adverse environmental circumstances, such as high pH, low water content, and low nutrient concentration, makes them preferable to bacteria for the biofiltration of hydrophobic contaminants. More varieties of fungi would be very helpful for biological waste gas treatment because they have the ability to break down volatile organic molecules in harsh settings. Some pseudomonas and bacillus strains can breakdown alkylbenzenes at low pH, while some bacteria strains may effectively degrade VOCs in acidic media [8]. Maintaining a high enough amount of moisture is crucial for treating waste gases in gas-phase bioreactors to prevent performance degradation. As a fact, the growth of fungi in biofilters does not only present advantages but also has problems in terms of clogging problems [21]. But fungi are not harmful to humans. It is not at all pathogenic and does not result in diseases in healthy individuals. Even some yeast and fungus have long been shown to be quite beneficial to humans.

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Municipal solid waste (MSW) can undergo aerobic biotreatment to lower its water content and speed up stabilization in a relatively short amount of time [48]. Additionally, it can therefore increase sorting effectiveness and lessen the likelihood of leachate and landfill gas production. Volatile organic compounds are one of the main contaminants in exhaust gases in these MSW bio-treatment systems. VOC is the main contributor to odor emissions. Humans are harmful to some VOCs such as aromatic and halogenides [49]. Therefore, one of the crucial elements for the efficient operation of the MSW biotreatment facility is the management of VOC emissions. VOC released from the aerobic biotreatment process of MSW can be divided into two categories which are xenobiotic and biogenic. Alkanes, aromatic hydrocarbons, and halogenides, which make up xenobiotic VOC and are typically present in household garbage such as plastic packaging and used cooking oil, are volatile organic compounds that are not formed through biodegradation [17]. In the course of aerobic biological activity, it can also be volatized from MSW and typically persists in the exhausted air [46]. Alcohols, ketones, organic acids, sulfides, and terpenes are among the biogenic VOCs that are formed during the biodegradation of organic compounds in MSW. The concentration of biogenic VOC decreased as the biological process proceeded [17]. The biological stability of trash and the class of biogenic VOC were substantially associated. Intermittent ventilation was advised from the standpoint of VOC emissions, paying special attention to the air control during the commencing phases. A significant air pollution concern now is the removal of a volatile organic molecule from contaminated airstreams. The application of biofiltration can now be utilized to remove VOCs as well as odor compounds thanks to improvements made to the biofiltration technique that is frequently used to remove odor compounds. In addition, biofiltration relies on microorganisms’ capacity to break down a wide range of substances and is both practical and affordable [34]. In the biofilter, a layer of densely packed porous material is used to force the waste gas to rise. Two main occurrences serve as the foundation for the biofiltration process. The first concept is that pollutants are transferred from the air to the water phase or support medium, and the second principle is that pollutants are bio-­ converted to biomass, metabolic products, carbon dioxide, and water through biological processes. Volatile organic compound (VOC) removal from polluted airstreams has grown to be a significant air pollution concern. Because these pollutants have a detrimental effect on health, they are subject to strict environmental restrictions [24]. Key parameters can now be controlled more effectively thanks to advancements made to the biofiltration method that is frequently used to remove odor components. The parameters that have been analyzed are moisture content, temperature, and pH [25, 59]. The applications of biofiltration will be broadened to include VOC removal. When compared to physicochemical purification methods like combustion, condensation, absorption, and adsorption, biofiltration is based on microorganisms’ capacity to break down a wide range of substances [34].

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9.3.4.1 Biofiltration Mechanism The biofiltration process is based on two principal phenomena. The process by which pollutants are transferred from the air to the aqueous phase or support medium is the first phenomenon. According to physical rules, contaminants shift from the gas phase to the liquid phase. The ratio of the concentration in the water to those in the air will be determined by Henry’s constant. This is often supported by biofiltration models, which treat the biofilm-like water and anticipate mass transfer into the biofilm where degradation takes place by utilizing Henry’s law constant. It is likely that the concentrations in the air and water would be at balance throughout the biofilter because equilibrium is a local phenomenon, even if the height and depth of the two concentrations are very different [35]. Mass transfer additionally takes place in addition to the partial phenomenon. According to the mass transit rates of α-pinene as a model hydrophobic chemical through artificial biofilms and comparisons with those in water, α-pinene’s total apparent solubility or partitioning in biofilms that contain biomass and organics is greater than in water [35]. Thus, the transfer occurs easily from areas with a high concentration in the air to areas with low concentrations in the water. The second phenomenon is the bioconversion of contaminants to biomass, metabolic by-products, carbon dioxide, and water. In the biofilm, which has a variety of species growing on its surface, the pollutant gets biodegraded (Fig. 9.5). Where a = air regulator b = flowmeter c = syringe pump delivering the volatile organic compound mixture d = spray nozzle e = sample sports f = peristaltic pump g = nutrient solution There are several technologies available to reduce the emission of volatile organic compounds; however, not all of them are universal. VOC emissions from a variety of industrial operations can be significantly reduced using traditional techniques like burning, absorption, adsorption, condensation, and some more contemporary ones like membrane separation and electronic coagulation. According to its minimum product creation, low energy consumption, and generally affordable operating costs, biological treatment is a desirable solution for low-­ concentration gas streams. Low-molecular-weight and highly soluble organic chemicals are removed in gas-phase bioreactors with the greatest success, while compounds with complex bond structures required more energy to degrade. Thus, these sorts of biodegradation will not happen since microorganisms only break down readily accessible and simple-to-break-down chemicals [44]. Aldehydes, alcohol, ketones, and several simple aromatics are organic compounds that exhibit great biodegradability. Some compounds degrade slowly to moderately. These substances include polyaromatic hydrocarbons, chlorinated hydrocarbons, phenols,

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Fig. 9.5  Pilot scale unit [34]

and highly halogenated hydrocarbons. Table 9.3 shows the biodegradability of the substance. In the biodegradation process, the microbial attack takes place in an aqueous phase after the pollutants are sorbed from a gas phase there [22]. Through the process, the contaminants are changed into organic biomass, carbon dioxide, and water vapor. These air pollutants, which are exploited for energy, might be either organic or inorganic vapors. In general, naturally occurring microbes are used for biological treatment. Table 9.4 shows the differences between bioreactors for VOC and odor control.

9.4 Conclusion The removal and recovery of volatile organic compounds is a prominent topic in the environmental sector that has attracted a significant amount of attention from both the government and researchers. Because of the great industrial prospects that recovery methods, particularly adsorption and membrane separation procedures, provide for recycling volatile organic compounds (VOCs) and cutting carbon emissions, they have been the subject of a significant amount of research. The most current research successes in gas–liquid mass transfer, homogeneous oxidation,

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Table 9.3  Biodegradability of typical indoor VOC [44] Substance Acetaldehyde (ethanal; CH3CHO)

Biodegradability Good

Benzene (C6H6)

Moderate

Formaldehyde (methanal; HCHO)

Good

Naphthalene (C10H8)

Low

Tetrachlorethylene (tetrachloroethene; C2Cl3)

Low

Toluene (methylbenzene C6H5CH3)

Moderate

Trichlorethylene (trichloroethene; C2HCl3)

Low

Henry’s law constants (atm m3 molˉ1) 5.88 × 10−5 7.69 × 10ˉ5 5.88 × 10ˉ5 6.25 × 10ˉ3 5.55 × 10ˉ3 4.76 × 10ˉ3 3.33 × 10ˉ7 3.23 × 10ˉ7 3.13 × 10ˉ7 4.76 × 10ˉ4 4.76 × 10ˉ4 2.78 × 10ˉ2 1.69 × 10ˉ2 1.56 × 10ˉ2 6.67 × 10ˉ3 6.67 × 10ˉ3 9.09 × 10ˉ3 1.12 × 10ˉ2 1.00 × 10ˉ2

heterogeneous oxidation, electrochemical oxidation, and coupling technologies are among the most recent developments in the chemical oxidation of gaseous volatile organic compounds (VOCs) in a liquid phase. New compound absorbents and new reactors with the improved mass transfer of gaseous volatile organic compounds (VOCs) into the liquid phase were developed in order to obtain a high degradation and mineralization efficiency of gaseous volatile organic compounds (VOCs). Additionally, numerous volatile organic compounds were disposed of using photo/ electric coupling technologies as well as novel strong oxidants and catalysts. Future research into the topic could advance significantly with the creation of highly effective materials and techniques for activating oxidants as well as refractory VOC substrates and intermediates. This would make it possible for the area to advance more. In addition, combining chemical oxidation with biodegradation would be a highly appropriate strategy, and it would offer wonderful potential for the complete breakdown of these resistant VOCs and intermediates. Due to recent quick advancements in the sector, it is anticipated that the chemical oxidation of gaseous volatile organic compounds (VOCs) in the liquid phase will significantly aid in the treatment of complex industrial organic exhaust gas. At the same time, advancements should be made in disinfection technology in order to cut down on the production of disinfection by-products and, consequently, the risk that VOCs provide to human health. Even while VOCs in drinking water offer a minor health risk to humans (only individual compounds do), their presence indicates that the water environment is vulnerable to human-sourced contamination and may alter according to national standards and environmental laws. The future

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Table 9.4  Comparison of bioreactor for VOC and odor control [44] Bioreactor Biofilter

Application Removal of odor and low VOC Target VOC concentration is less than 1 gm−3

Advantages Low initial investment leads to a reduction in operating costs Impairs a variety of components Easy to operate and maintain There are no unneeded waste streams produced Low-pressure drop

Bio trickling filter

Low/medium VOC concentration Target VOC concentration is less than 0.5gmˉ3

Less operating and capital constraints Less relation time/ high volume throughput Capability to treat acid degradation product of VOC

Membrane bioreactor

Medium/high VOC concentration Target VOC concentration is less than 10 gmˉ3

No moving parts Process easy to scale up Flow of gas and liquid can be varied independently without the problems of flooding, loading, or foaming

Bioscrubber

Low/medium VOC concentrations Target VOC concentration less than 5gmˉ3

Capable of handling extreme variations and high flow rates Operational stability and greater management of operating parameters Relatively low-pressure drop Relatively smaller space requirements

Disadvantages Less treatment when contaminants are concentrated strongly The extremely huge size of the bioreactor presents space difficulties The operational condition must be closely controlled Packing has a limited life Particles clogging brought on by particulate medium Buildup of surplus biomass in the filter bed Design specifications for varying concentration Complexity of construction and use Secondary waste stream High construction cost Long-term operational stability Possible clogging of the liquid channels due to the formation of excess biomass Treat only water-soluble compounds Can be complicated to operate and maintain Extra air supply may be needed Excess sludge will require disposal Generation of liquid waste

implementation of long-term monitoring of volatile organic compounds (VOCs) in drinking water sources is therefore strongly advised. Long-term monitoring of VOCs in drinking water sources is necessary because the creation and use of new compounds will alter the content and amounts of VOCs in the water environment. On the other hand, the investigation of probable toxicity will also assist individuals in comprehending the risk posed by volatile organic compounds (VOCs). Each technological solution needs to be evaluated using essential operational aspects, which will ultimately define how successful the technology will be as a whole. This will make it possible to achieve the goal of selecting the appropriate technology for the evaluation that needs to be done. These operational parameters will be the result of the design criteria and restrictions, which will, in turn, largely

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depend on the characteristics of the process as well as the composition and type of the emission. In other words, the design criteria and restrictions will be the result of the design criteria and restrictions. The overall comparison will be conducted by ranking the different abatement methods according to criteria such as operating flexibility, cost-effectiveness over the course of the entire life cycle, and compliance with present and foreseeable future legal requirements.

Glossary VOC/VOCs Volatile organic compounds are organic chemicals that have a high vapor pressure at room temperature. Low boiling point and high vapor pressure are related to volatility, which is the proportion of the sample’s molecules in the surrounding air. End-of-pipe solution  The term “end-of-pipe solution” describes a pollution control approach that remediates contaminated flows of air just before the effluent can enter the environment. MVOCs  Microbial volatile organic compounds (MVOCs) are a variety of compounds formed in the metabolism of fungi and bacteria. None of the more than 200 substances that have been discovered as MVOCs in lab tests can be considered to be solely microbial in origin or to be exclusive to any one microbial species. CFPPs  A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide, there are about 8500 coal-­ fired power stations totaling over 2000 gigawatts of capacity. It produces higher VOC in China. CETPs  Common effluent treatment plants (CETPs) are treatment systems specifically designed for the collective treatment of effluent generated from small-scale industrial facilities in an industrial cluster. RTO A regenerative thermal oxidizer is a type of air pollution control equipment that destroys hazardous air pollutants (HAP), volatile organic compounds (VOC), and odorous emissions created during industrial processes. RTOs are the most common air pollution control technology in use today. RCO A regenerative catalytic oxidizer has been used to destroy VOC for over 25 years. RCO is more fuel efficient and has lower associated operating costs compared to RTO. LEL  The lower explosive limit (LEL) varies from gas to gas, but for most flammable gases, it is less than 5% by volume. This means that it takes a relatively low concentration of gas or vapor to produce a high risk of explosion. VUV Vacuum ultraviolet-based photocatalytic oxidation (PCO) is a promising technology for controlling VOCs. CeO2 is found to be a promising catalyst for the VUV-PCO technology possessing catalytic capacities in both the photocatalysis and ozonation processes.

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Chapter 10

Various Technologies in Healthcare Waste Management and Disposal Wen Si Lee, Hamidi Abdul Aziz, Lawrence K. Wang, Mu-Hao Sung Wang, and Yung-Tse Hung

Acronym Ag Silver Al2O3 Aluminium oxide As Arsenic Bi Bismuth BTEX Benzene, toluene, ethylbenzene, and xylene isomers CaO Calcium oxide Cd Cadmium Cl Chlorine Co Cobalt Cr Chromium Cu Copper e.g. Example EHS Environmental, health, safety EPA Environmental Protection Agency

W. S. Lee School of Civil Engineering, Universiti Sains Malaysia, Pulau Pinang, Malaysia e-mail: [email protected] H. A. Aziz (*) Environmental Engineering, School of Civil Engineering, Solid Waste Management Cluster, Universiti Sains Malaysia, Pulau Pinang, Malaysia e-mail: [email protected] L. K. Wang · M.-H. S. Wang Lenox Institute of Water Technology, Latham, NY, USA e-mail: [email protected]; [email protected] Y.-T. Hung Department of Civil and Environmental Engineering, Cleveland State University, Strongsville, OH, USA e-mail: [email protected]; [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024 L. K. Wang et al. (eds.), Waste Treatment in the Biotechnology, Agricultural and Food Industries, Handbook of Environmental Engineering 27, https://doi.org/10.1007/978-3-031-44768-6_10

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ER Equivalence ratio F Fluorine Fe Iron Fe2O3 Ferrous oxide GDP Gross domestic product H Hydrogen HCW Healthcare waste HCWGR Healthcare waste generation rate HIV Human immunodeficiency virus HW Hospital waste K2O Potassium oxide LOI Loss on ignition MgO Magnesium oxide MSW Municipal solid waste MSWIFA Municipal solid waste incinerator fly ash MWBA Medical waste bottom ash MWG Medical waste generation MWIFA Medical waste incinerator fly ash MWIS Medical waste incinerator sludge Na2O Sodium oxide ND Not determined Ni Nickel NT Not tested Pb Lead PPE Personal protective equipment Ref Reference S Sulfur SiO2 Silicon oxide SO2 Sulfur trioxide TEQ Toxic equivalents scheme Ti Titanium TiO2 Titanium oxide USA United States USD United States dollar WHO World Health Organization Zn Zinc

Nomenclature % Percentage °C Degree Celsius CO2e Carbon dioxide equivalent °F Degree Fahrenheit

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Kg Kilogram kPa kilopascal kW Kilowatt kWe Kilowatt-electric kWh Kilowatt-hour L Liter mg Milligram mg/L Milligram per liter MHz Megahertz min Minutes MJ Megajoule Nm3 Newton cubic meter Vol% Volume percent μg Microgram

10.1 Introduction The waste generation keeps rising in these few years, and the global waste generation believes it will reach 3.40 billion tonnes in 2050. Waste generation is likely to rise with economic development and population expansion, with regions with a high proportion of expanding low-income and low-middle-income countries facing a significant increase in waste generation [1]. The rise in healthcare waste (HCW) generation is progressively outstripping the load as the demand for health develops [2]. During the Covid-19 pandemic period, The use of personal protective equipment has resulted in a large increase in waste generation. Thus, the unexpected surge of HCW during the Covid-19 outbreak has overwhelmed the capacity of current facilities for disposal [3]. HCW, often known as pharmaceutical waste, contains dangerous compounds that can harm the environment by contaminating the land, air, and water. These compounds, which are explosive, corrosive, oxidizing infectious, combustible, and radioactive, can harm human health and the environment [4]. HCW is described as waste generated during the diagnosis, treatment, and vaccination of humans and animals, as well as accompanying research, biological manufacture, and testing [3, 5]. HCW often has a high concentration of organic components (e.g., human organs, plastics, cotton swabs, paper, and textiles) as well as inorganic chemicals (e.g., metal and glass). When HCW is exposed and degraded in the open air, it emits not only foul odors but also infections, organic compounds, and heavy metals that pollute surface water, soil, and groundwater [3]. During the Covid-19 epidemic, there was a lot of HCW, mainly personal protective equipment, including gloves, goggles, face masks, face shields, coverall suits, and other equipment [6]. According to the World Health Organization (WHO), approximately 85% of HCW created by healthcare operations is general and nonhazardous waste. The remaining 15% is classified as a hazardous substance, which might be infectious, radioactive, or poisonous.

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Since the dramatic increase in HCW generation during the Covid-19 outbreak, there has been worry about HCW management and treatment methods. The technologies used to treat the HCW include incineration, pyrolysis, gasification, and carbonization. Those final products after treatment will generate energy, electricity, and fuel for future use [5]. Other than those treatment methods, the HCW can also be treated through medium-temperature microwave technology, plasma technology, chemical disinfection technology, acid and enzymatic hydrolysis technique, and pressure steam sterilization technology [7]. However, some of the HCW can be recycled to produce useful materials; for example, the pharmaceutical blister can be used to replace the fine aggregates in the concrete [8]. Due to the generally large amount of HCW generated during the Covid-19 epidemic, emergency disposal and treatment technologies must be explored in order to limit waste in the environment. There are various challenges faced when managing the HCW, such as insufficient enforcement of HCW regulations, lack of awareness and knowledge, and waste segregation and disposal methods [9]. The employees or waste workers do not have proper attire while working during the collection or transportation of the HCW [10]. Due to a shortage of professional employees, HCW disposal units should provide training to workers and management people involved in HCW collection, transportation, storage, and disposal on associated legislation, emergency handling, professional practices, and safety protection [11]. A landfill is the common disposal method to manage the HCW due to its low cost, but it is not recommended because if used improperly it can pollute the environment and pose health issues to humans. Incineration can treat the HCW efficiently, but the secondary products contain high dioxin and toxic pollutants, which will contribute to environmental pollution [12]. Thus, strict HCW regulations must be established to ensure that the wastes can be handled in a proper way. This chapter will discuss the HCW generation by different types and characteristics of the HCW produced. Since HCWs exposed and disposed of in the open air have negative consequences for the environment and public health, the risks of HCW will be assessed. The treatment and disposal of HCW are studied. The co-­ disposal of HCW with other wastes or in the cement kiln will be discussed in this chapter. HCW case studies from various countries are addressed. Lastly, the challenges and future recommendations for the disposal and treatment of HCW will be discussed.

10.2 Generation and Types of Healthcare Waste HCW generation keeps increasing especially during the Covid-19 pandemic; there are different types of HCWs discharged from different sources such as general hospitals, private hospitals, and private clinics. Common HCWs can be found in the hospital using organic and inorganic materials such as personal protective equipment and surgery instruments.

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10.2.1 Healthcare Waste Generation The world produces around 0.74 kg of waste per capita per day. Municipal solid waste was estimated to have generated around 2.01 billion tonnes in 2016, with the figure expected to rise to 3.40 billion tonnes by 2050. The global average HCW generation was 0.25 kg/capita/day, which is much lower compared to other wastes produced by industrial, agricultural, and construction activities (Fig.  10.1) [1]. Adelodun et al. (2021) [13] mentioned that due to the widespread use of face masks during the Covid-19 epidemic in developing countries, the creation rate of face masks increased significantly (Table 10.1). Minoglou et al. (2017) [14] indicated that the production of healthcare waste was tied to the country’s gross domestic product (GDP). When countries have high GDP, there was high healthcare waste generated. Africa had a low healthcare waste generation rate compared to other countries, while those countries with high GDPs, such as Europe, the USA, and Canada, had higher healthcare waste generation rates (Fig. 10.2). Ma et al. (2022) [15] explained that HCW production was influenced by economic growth, with HCW generation steadily increasing with economic growth. When the aging degree increased, the demand for health and medical treatment also increased, as well as the utilization of medical resources; thus, high healthcare waste would be produced. The production of HCW increased from 2013 to 2019 in the top ten cities in China (Fig. 10.3). In India, about 619 tonnes/day of HCW were generated before the Covid-19 pandemic. The top five states in India that produced 47% of HCW were Tamil Nadu, Karnataka, Kerala, Uttar Pradesh, and Maharashtra (Figs. 10.4 and 10.5). The production of HCW in India began to rise during the Covid-19 outbreak, owing to a

Electronic waste

0.02

Medical waste

0.25

Hazardous waste

0.32

Construction and demolition waste

1.68

Agricultural waste

3.35 12.73

Industrial waste 0

2

4

Fig. 10.1  Global average special waste generation [1]

6

8

10

12

14

Table 10.1  Daily face mask usage estimated in several selected developing countries using the Covid-19 growth rate [13]

Population Country (million) India 1380.00 Brazil 212.56 Indonesia 273.52 Nigeria 206.14 Pakistan 220.89 Bangladesh 164.69 Iran 83.99 Philippines 109.58 Egypt 102.33 DR Congo 89.56 South 59.31 Africa Algeria 43.85 Iraq 40.22 Morocco 36.91 Ghana 31.07 Uzbekistan 33.47 Sudan 43.85 Cameroon 26.55 Ivory Coast 26.38 Afghanistan 38.81 Senegal 16.74 Oman 5.11 Argentina 45.20 Columbia 50.88 Bolivia 11.67

Covid-19 cases (May 1, 2020) 37,257 92,109 10,551 2170 18,092 8238 95,646 8772 5895 604 5951

Covid-19 cases (January 10, 2021) 10,451,346 8,075,998 45,891 19,808 176,617 112,306 1,280,438 30,052 53,758 5826 92,681

Percentage increase of confirmed cases (%) 27,962 8668 7656 4465 2677 6229 1239 5438 2424 3072 20,303

4154 2153 4569 2074 2086 442 1832 1333 2335 1024 2447 4532 7006 1167

11,631 29,222 9957 13,717 6272 8580 11,610 7276 28,833 5888 29,471 41,204 65,633 23,512

2353 27,876 9785 2589 3619 5175 1366 1662 2191 1951 5215 37,729 25,184 14,707

Estimated daily face mask usage (million) 772.80 299.28 245.08 171.51 123.70 102.77 102.14 82.40 70.41 65.92 63.58

Fig. 10.2  Healthcare waste generation rate for selected countries worldwide [14]

51.22 46.98 37.80 28.34 26.78 24.58 23.79 21.52 15.53 13.13 7.11 0.67 0.65 0.13

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Fig. 10.3  The amount and proportion of HCW generation in the top cities in China [15]

Fig. 10.4  HCW generation of different states in India in 2019 [16]

surge in the use of personal protective equipment. Within the first wave of the Covid-19 epidemic in India in September 2020, the average HCW production was 183 tonnes/day. The average HCW generation during the second wave in May 2021 was 203 tonnes/day, which was greater than the first wave in September 2020 (Figs. 10.6 and 10.7) due to the number of Covid-19 cases rising on a daily basis. Nonhazardous waste accounts for 70–80% of total waste produced by healthcare institutions. HCW includes waste produced during patient diagnosis and treatment [16]. In the Kingdom of Bahrain, a large amount of HCW was created during the

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Fig. 10.5  HCW generation of different states in India in 2019

Fig. 10.6  Average HCW generation by different states in India during the Covid-19 pandemic (kg/ day) [16]

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Fig. 10.7  Average HCW generation by different states in India during the Covid-19 pandemic (kg/ day) [16]

Covid-19 outbreak, approximated to be 35.48  kg/day (facial mask), 1894 kg/day (personal protective equipment), 16,633.51  kg (vaccination-related), and 53,551.24 kg (Covid-19 test) [17]. Chowdhury et al. (2022) [18] demonstrated that due to Covid-19, the HCW created in Bangladesh rose from 658.08 tonnes in March 2020 to 16,164.74 tonnes in April 2021. Since the cases of Covid-19 in Bangladesh increased, most of the HCW generated by hospitals, households, and clinics also increased (Table 10.2). Alazaiza et al. (2022) [19] demonstrated that throughout the Covid-19 epidemic, food waste and plastic waste surged during the lockdown period, with food waste accounting for 72% of waste production compared to other wastes created in Oman during the lockdown period. However, there was no notable difference in HCW production during the lockdown period. Due to the impact of Covid-19, Hubei Province in China created 0.5 kg/bed/day of HCW, resulting in a net rise in HCW volume of approximately 3366.99 tonnes [20]. In Malaysia, the clinical waste generation increased by 27% (by weight) in 2020, primarily due to Covid-19-related waste. About 80% of noninfectious waste had been produced, and it was the highest composition of waste generated in Malaysia compared to other HCWs [21]. According to the Ministry of Health of Singapore, the quantity of biohazardous waste created and disposed of rose from 4400 to 5700 tonnes between 2016 and 2020 due to an increase in the number of patients in hospitals and treatments. Nguyen et al. (2021) [22] reported that about 1486 tonnes of HCW were produced in a year during the Covid-19 pandemic. The hazardous HCW generated increased nearly double, 14.4%, from before the

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Table 10.2  Estimated monthly Covid-19 waste generation in Bangladesh [18] Infectious Year Month waste ton 2020 March 5.38 April 777.04 May 4161.82 June 10,029.66 July 10,123.46 August 8009.66 September 5224.54 October 4509 November 5767 December 5120.12 2021 January 2279.70 February 1054.53 March 6859.33 April 15,079.37 May 4364.40

Quarantine waste ton 614.33 707.68 615.65 640/20 581.31 534.18 427.45 206.43 249.9 251.72 148.34 89.81 223.56 614.58 364.26

Isolation patients waste ton 37.84 144.84 610.7 801.92 1929.87 2101.90 1535.81 476.95 522.44 535.85 29.87 15.58 44.47 178.25 124.19

Deceased waste ton 0.53 16.63 50.80 115.57 137.02 122.80 99.04 68.54 73.54 96.44 59.87 26.75 67.25 245.21 123.21

ICU waste ton NA NA NA NA 34.90 31.73 29.90 8.87 11.93 13.71 16.86 6.28 26.67 47.33 12.86

Total medical waste ton 658.08 1646.19 5438.97 11,587.35 12,806.56 10,800.27 7316.74 5269.79 6625.71 6017.84 2534.64 1192.95 7221.28 16,164.74 4988.92

Covid-19 pandemic generation value of 7.6%. Plastic waste was the most predominant HCW found during the Covid-19 pandemic, which was 76.7%, because most of the personal protective equipment was composed of high-density polyethylene [22].

10.2.2 Types of Healthcare Waste Different sources such as hospitals, private clinics, and households will generate different types of HCW. HCWs are the materials generated during human and animal therapy, diagnostics, pathology laboratory, operating rooms, or vaccination activities [23]. The HCW can be classified into a few groups chemical waste, pathological waste, sharps waste, pharmaceutical waste, and infectious waste (Table 10.3). Figure 10.8 shows the method of disposal based on the type of waste generated from different sources. 10.2.2.1 Infectious Waste Infectious waste is defined as waste infected with cultures, such as blood/bodily fluids, and waste from infected patients, such as swabs, disposable medical devices, and bandages. Households, farms, and agricultural activities, sites that provide sharps collection containers for the customer, public use, and employee, sites that find infectious waste in public areas, customers, or employees, vehicles during cleaning, and residential care facilities are all places where infectious waste can be found.

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10  Various Technologies in Healthcare Waste Management and Disposal Table 10.3  Type of HCW generated from different sources Sources Emergency room Blood sampling room Observation room Endoscopy room Dressing room Clinical laboratory Laboratory Pharmacy department Radiology department

Type of waste Sharp waste

Example Needle, blade, disposable syringe, glass slid, glass test tube, ampoule, infusion set needle

Infectious waste Pathological waste

Articles polluted with the patient’s blood, excreta, and bodily fluids, culture media, specimen, and pathogen strain Human waste and the carcasses of medical laboratory animals, as well as waste human tissue created after surgery

Pharmaceutical waste Chemical waste

Obsolete, deteriorated, or contaminated drugs Waste disinfectants Discarded mercury sphygmomanometers and thermometers

Fever clinic Observation wards Isolation wards Special examination room

Infectious waste Domestic waste

Medical laboratory

Injury waste

Blood, Secretions, Body fluids, Pathological specimens

Put into sharps box

Put into double-layered medical waste bag

Put into double-layered medical waste bag

High-pressure steam sterilization at 121 °C for 110 minutes

General department

Infectious waste

Injury waste

Put into sharps box

Put into single-layered medical waste bag

Spray disinfection Layered strapping, weighing, labelling ''COVID-19'' by specifically trained staff and put into medical waste bucket Handover record

Storage for less than 24h

Timely collection and transportation to medical waste disposal company for incineration though specifically trained staff, special vehicle and route Disinfection record Timely disinfection of transportation tools, and disinfection of the temporary storage area twice a day at least

Layered strapping, weighing, labelling ''General'' by special staff and put into medical waste bucket Handover record

Storage for less than 48h

Timely collection and transportation to medical waste disposal company for incineration or sanitary landfill though special staff, vehicle and route Disinfection record Timely disinfection of transportation tools, and disinfection of the temporary storage area once a day at least

Fig. 10.8  Disposal method based on the type of HCW generated from different sources [24]

Blood is one of the infectious wastes, and it also comprises blood products, such as those found in containers or possibly as saturated solid waste. Serum, plasma, and other blood components are among the blood products. Pathological waste is another sort of infectious waste that is classified as human or animal tissues or bodily parts. Some of the sharp wastes, such as needles and blades, which contain

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blood or are used on humans and animals also considered infectious waste. In Minnesota, blood-stained materials that do not leak blood or bodily fluid when crushed, teeth, organs, or other tissue given to patients are not considered infectious waste. The teeth and organs that are returned to the patient are not considered infectious waste [25]. During the Covid-19 outbreak, infectious waste production increased significantly, especially the personal protective equipment generated from hospitals, households, and clinics around the world. The personal protective equipment includes face mask, glove, gown, face shields, and goggles that are generated every day. In Malaysia, 20–40% of the infectious wastes produced during the Covid-19 outbreak were due to the high usage of face masks to protect from the virus [21]. Face mask is the most common infectious waste used by frontliners and citizens. Some citizens threw away their face masks in the general rubbish bin; however, face masks have the ability to transmit germs. As a result, effective waste disposal is critical. Peng et al. (2020) [24] recommended that face mask could be disposed of in the double-layered medical bag to prevent its pathogens from being exposed to the surrounding. The infectious waste should be handled properly to prevent any pollution to the environment. If the segregation process can be done before disposing of, it can save more cost in waste management. Before disposing of the infectious waste, the waste should be separated from other wastes at the time of production by placing it in separate containers. The containers used to keep the waste should be strategically placed to prevent unwanted access and properly labelled as carrying infectious waste. Handling pathological waste is different from the handling infectious waste. Pathological waste should be managed or disposed of within seven days of its creation or within 30 days if frozen. The waste needs to undergo the autoclaving process to make sure there is no hazardous microorganism exposed to the environment. 10.2.2.2 Chemical Waste Chemical waste includes reagents and solvents used in laboratory preparations, as well as sterilants, heavy metals, and disinfectants found in healthcare equipment [16]. When handling chemical waste, personal protective equipment, such as gloves and eye protection, must be utilized to protect employees from contact risks and splashes. Chemical waste can be divided into two categories: expired materials and extraneous materials. Expired materials are chemicals that have passed their expiration date and cannot be utilized, whereas extraneous materials are chemicals that are no longer employed in the process or experiment for which they were designed. Good disposal and management of handling chemical waste are of utmost concern because chemical waste has some hazardous characteristics that may affect the environment and human health (Table 10.4). All hazardous healthcare chemical wastes must be handled and disposed of in accordance with environmental, health, and safety regulations (EHS). The hazardous chemical wastes are managed and disposed of by collecting them in hard-­walled

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Table 10.4  Characteristics of chemical waste Characteristics Type of waste Ignitable Alcohols, organic solvents, stains

Corrosive

Reactive

Explanation The liquid compound has a flash point of less than or equal to 140 °F (60 °C). Under ordinary temperature and pressure, the solid chemical can cause fire by absorption, moisture, friction, or spontaneous chemical changes, and it burns vigorously when lit. Sodium hydroxide, Aqueous with a pH less than or equal to 2 and a pH hydrochloric acid, nitric more than or equal to 12.5 acid, sulfuric acid Sodium metal, sodium Unstable and capable of undergoing severe changes borohydride, organic without detonating under normal circumstances peroxides

containers with screw-top, sealable lids. The containers must be labelled with a hazardous waste label. When not in use, the containers must be closed to protect patients and personnel from inadvertent exposure. The containers must be stored in a designated chemical waste satellite accumulation area with supplementary containment to prevent leaks. Lastly, those wastes are requested to dispose of via EHS. 10.2.2.3 Sharp Waste Sharp waste, which includes shattered glass, syringes, lancets, needles, and other objects that can penetrate the skin, is a subset of infectious waste. Due to incorrect storage, sharp waste, particularly syringes, may cause millions of diseases each year, including hepatitis, HIV, and bacterial infections. Even if seroconversion does not occur, being hurt by sharps can have a psychological impact, causing debilitating post-injury morbidity and extreme stress/anxiety [26]. To avoid exposure of those sharp wastes to the public, sharp wastes must not be disposed of in the general waste bins or garbage cans. The sharp wastes must be segregated from other wastes, and specially dedicated containers must be used to dispose of these wastes. The collection container must be puncture-resistant and leak-tight [21]. There is a guideline for handling and disposing of the sharps (Table 10.5). Only one-fifth of type 2 diabetes patients in Malaysia were able to properly dispose of sharps at healthcare facilities. The majority of the patients did not use appropriate containers to store their sharps; they utilized plastic bags that were readily available in their homes. However, those containers did not fulfil the EPA’s fundamental requirements for a proper sharp disposal container [27]. In Turkey, over 75% of used sharps were discarded in the garbage, with roughly 6% possessing no tip protection [28]. Hussain et al. (2020) [29] observed that the percentage of sharps containers overfilled was reduced from 56% to 17% by increasing the number of sharps containers during the Covid-19 pandemic. This result showed a significant improvement, and public awareness in managing sharp wastes increased.

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Table 10.5  Handling and disposal guidelines of sharp waste Handling guidelines Use appropriate PPE Decontaminate by either chemical means or autoclave Store in a safe place with limited public access and protection from the environment and pests Sharps should not be disposed of in standard office or laboratory garbage cans Sharps should be stored in specially constructed plastic puncture-proof and biohazard-labelled sharps containers. Do not re-cap the needle on used hypodermic syringes

Disposal guidelines Do not use domestic household or food containers to hold biohazardous sharps Containers specifically designed for biohazard sharps can be used for chemically contaminated sharps Clean, uncontaminated broken glass and plastic sharps should be placed in a corrugated cardboard box or another strong disposable container Waste should be transported in a proper way

10.2.2.4 Pharmaceutical Waste Pharmaceutical waste includes unused, expired, and contaminated medications and vaccines. This waste can be classified as hazardous or nonhazardous based on its chemical qualities and the hazard it brings to humans and the environment. A small amount of pharmaceutical waste can be found in the home, and the garbage is disposed of with municipal solid waste. If pharmaceutical waste is disposed of inappropriately, harmful substances can leak into the surrounding environment and endanger drinking water, groundwater, and aquatic life. As a result, when handling and disposing of pharmaceutical waste, special care and precautions must be taken. The container used to dispose of pharmaceutical waste must be properly secured to minimize the possibility of the waste leaking, spilling, or polluting. Rogowska et al. (2019) [30] observed that more than 35% of respondents disposed of pharmaceuticals in any location. About 30% of respondents returned the expired pharmaceutical to the pharmacies. The majority of respondents stated that they were acquainted that pharmaceutical waste can be returned to pharmacies. In Ghana, over 75% of respondents disposed of pharmaceutical waste at home, such as leftover, unwanted, or expired drugs, in regular garbage cans, which ended up in landfills or disposal sites [31]. In Malaysia, approximately 2.9% of respondents dumped their home pharmaceutical waste directly down the drain, while 8.8% dumped it through the toilet or kitchen sink. Around 73.8% of Malaysian respondents agreed that domestic pharmaceutical waste should be segregated from another household solid waste, whereas only 25.2% returned the medicinal waste through the medication return-back scheme [32].

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10.3 Risk of Healthcare Waste The HCW contains different contaminants that will affect the environment and human health, such as heavy metals, pathogens, and dangerous contents. Those contaminants must be handled in the proper way to ensure the contaminants do not expose or spread to the surrounding. The following are the primary categories at risk: • Patients in healthcare facilities or providing home care; visitors to healthcare facilities • Healthcare staff, healthcare doctors, hospital maintenance workers, and nurses • Scavengers and employees at waste disposal facilities • Employees in support services related to healthcare facilities, such as laundry, waste disposal, and transportation

10.3.1 Contamination of Healthcare Waste HCW contains different hazards that may cause disease or injury to the humans such as infectious agents, genotoxins, hazardous chemicals, radioactives, and sharps. Nonetheless, 75–90% of HCW is nonhazardous waste, whereas the remainder 10–25% of HCW is hazardous waste and may pose a range of environmental and health problems [33]. The waste contains human tissue, blood, laboratory specimens or culture, animal tissue, and visible blood-stained body fluids, material, or equipment. According to the WHO, HCW may also contain bacteria or diseases that might endanger hospital patients, health personnel, and the general public. Ye et al. (2022) [20] demonstrated that the HCW might generate different contaminations through different disposal methods such as ammonia, mercury, phenol, heavy metals, toxic gases, and chloride. Those contaminations may infiltrate into the soil or discharged as wastewater, which will affect the water quality of groundwater and cause air pollution. Zhao et al. (2009) [34] studied heavy metals’ chemical properties of HCW generated from incineration. Several heavy metals from HCW were found in significant concentrations in bottom ash and fly ash when compared to general municipal solid waste (Table 10.6). Table 10.7 represents the chemical composition of HCW incineration fly ash. Shen et al. (2022) [35] observed that, in comparison to medical waste incineration sludge and solid municipal waste fly ash, medical waste incineration fly ash contained a high concentration of chloride and salt oxide. The medical waste incineration fly ash had high dioxin content due to incomplete combustion of the material (Table 10.8).

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Table 10.6  Comparison of heavy metal concentrations in municipal solid waste (MSW) ashes and hospital waste (HW) ashes (mg/kg) [34] Heavy metals Zn Ti

Bottom ash MSW Average Range 4510 2866– 9601 328 182–620

Sn

354

Pb

966

Ni Cu

279 2824

Cr

244

Co

17.1

29.5– 276 430– 1626 140–710 1169– 5251 44.0– 358 3.9–44.1

Cd Bi As Ag

14.1 1.5 5.8 1

82.31.2 0.85–2.6 0–93.0 0.57–1.6

HW Average Range 11,965 2571– 30,706 6095 1754– 15,518 285 170–406

Fly ash MSW Average Range 7656 400– 207,000 NT NT

HW Average Range 7868 28,775– 121,411 1940 92–8937

1836

0–5880

1149

592–1660

223– 79,500 0–186 316– 10,600 62–1170

3544

900–5363

36.0 1702

20.0–57.3 420–2907

65.2

3.5–264

23.8

14–36.9

5.4

0.58–23.8

132 ND 49.2 20.4

0.3–573 ND 0.5–37 11.8–29

237 165 170 113

29.0–635 38.9–275 69.3–237 40.5–222

795

68–2107 2883

111 487

10.7–667 62.4 68–2330 678

397

34.4–895 210

22.7

10.4– 49.9 1.4–10.2 13.2–489 4.9–50.9 2.1–24.2

5.3 103 27.8 8.4

Table 10.7  Chemical compositions of HCW incinerator fly ash (in %) SiO2 Al2O3 17.13 2.85 7.96 6.90 9.06 10.11 4.84 0.15

K2O CaO 2.80 24.42 3.29 38.53 1.64 5.37 2.22 1.46

MgO 1.80 2.29 3.48 0.37

Na2O 15.2 1.58 22.05 50.63

SO3 6.37 1.57 1.03 2.86

Fe2O3 1.78 1.10 1.49 –

TiO2 1.34 3.23 – –

Cl 20.43 30.75 17.07 32.85

F 2.59 – 0.75 –

LOI 11.10 – – –

References [36] [37] [38] [35]

10.3.2 Impact of Healthcare Waste In India, problems with HCW include the presence of open-sorting scavengers, the reuse of needles without adequate sanitation, and exposed medical waste without shoes, masks, or gloves for recycling [39]. Thus, the HCW will bring great impacts on the environment and human health if the waste is not handled with the proper disposal method. Table 10.9 shows the effects and solutions of HCW caused by different sources.

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Table 10.8  Characteristics of medical waste incinerator fly ash (MWIFA), municipal solid waste fly ash (MSWIFA), and medical waste incinerator sludge (MWIS) [35] Sample type Compound (%)

Organic element compositions (%)

Heavy metals (mg/kg)

MgO Al2O3 SiO2 K2O SO3 NaO Cl CaO S H C N Pb Zn Cu Cd

Dioxin content (μg TEQ/kg)

MWIFA 0.37 0.15 4.84 2.22 2.86 50.63 32.85 1.461 1.1254 1.1254 57.67 0.305 570.2 16,065.8 757 15.56 130.00

MSWIFA 1.67 1.77 5.24 5.61 7.03 13.39 20.94 39.82 2.3355 1.0605 2.535 0.125 565.82 4621.57 437.76 148.59 0.51

MWIS 1.33 9.45 42.46 1.07 4.82 9.14 3.27 18.96 / / / / 52.5 703.06 4168.79 20 0.19

Table 10.9  HCW: causes, effects, and solutions Causes Dentists Physicians Retail health Vets Urgent care Home healthcare Assisted living facilities Hospitals Research

Effects Meningitis Parasitic infections Blood poisoning Infections of the skin Candida albicans Hepatitis Sexual infections HIV Environmental impact

Solutions Appropriate disposal of healthcare waste Avoid healthcare waste Government regulations Subsidies Research Education

10.3.2.1 Health Risk HCW contains potentially dangerous bacteria or diseases that can endanger hospital patients, medical personnel, and the general public. The waste can cause sharps-­ inflicted injuries, radiation burns, poisoning, and pollution through the discharge of pharmaceutical compounds, as well as contamination through wastewater. Some sharp wastes, such as contaminated needles and syringes, can lead to hepatitis B infections, HIV infections, and hepatitis C diseases in humans. Workers at the disposal site are in imminent danger of needle-stick injuries and exposure to poisonous or infected materials. Improper disposal of HCW will cause health risks to the public (Table 10.10).

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Table 10.10  Public health impact of HCW [42] Type of wastes Sharps and infectious waste Chemical and pharmaceutical waste Genotoxic waste

Radioactive waste

Health risk Infections with viruses such as hepatitis B and C and HIV caused by sharps injuries Extensive intoxication caused by industrial chemical waste Exposure to chemicals such as aerosols, vapors, and liquids increases the risk of respiratory or skin illnesses Excessive urine levels of mutagenic chemicals among exposed employees Abortion risk increases Cancer disease

When pharmaceutical waste materials are dissolved in water, they form a combination of heavy metals and organic pathogens that are potentially mutagenic and genotoxic to living organisms [40]. Chamberlain (2019) [41] indicated that if sharp waste is not properly disposed of, the wastes sent to landfills may include tetanus spores or other blood-borne infections that can cause HIV and hepatitis. Improper disposal of laboratory HCW would cause parasitic infections to the hospital workers and the public, which would infect through skin contact and respiration. Another threat of transmission via blood fluids is meningitis, which is caused by bacteria that lead to inflammation of the membranes around the brain and spinal cord. Waste management must be applied in a proper way to reduce contamination from the HCW through landfill activities and incineration. The WHO has reported that landfill activities may cause different health risks such as cancer diseases (e.g., pancreas, liver, kidney) and non-Hodgkin lymphoma. If the residents stay near the landfill sites, it increases the risk for infants born to mothers. Other than landfill activities, incineration also will cause health risks to the public. HCW incineration at low temperatures releases harmful fumes that may contain dioxins and heavy metals. The remaining ash may potentially affect food and drinking water supplies. Incineration also emits toxic gases into the environment and causes respiratory disease in human when they inhale the air. Bhar et al. (2022) [23] stated that due to incomplete combustion, incineration may create a number of harmful chemicals. Dioxins are an unexpected by-product of waste combustion generated by incinerators. Metals in HCW operate as a catalyst for the creation of dioxins, which can harm the human immune and endocrine systems [39]. 10.3.2.2 Environmental Risk HCW treatment and disposal may cause indirect health issues by releasing infections and harmful substances into the environment. As an example, landfill activities can cause the drinking water and groundwater to be contaminated if the landfills are not properly constructed. Inadequate incineration causes the discharge of contaminants and ash residue into the atmosphere [33]. Improper segregation and disposal of HCW would cause significant environmental pollution. The Covid-19 pandemic

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has increased the usage of PPEs in daily life; some developing countries face problems in managing hazardous waste, which leads to threats to environmental pollution [43]. Adama et  al. (2016) [44] indicated that incineration would generate various heavy metals in bottom ash, such as zinc, mercury, chromium, lead, silver, and cadmium. Those heavy metals would contaminate the surrounding soil, and the polluted soil would cause harm to plants, animals, and humans. Zinc had the greatest metal concentration compared to other heavy metals, and soils within a 60-meter radius of the incinerator were polluted with heavy metals. These heavy metals will infiltrate groundwater or be transferred into bodies of water by runoffs, bioaccumulate in plants and animals that stray to the dump site, and be inhaled in dump dust. Some researchers had reported that toxic gases and compounds including dibenzofurans, polychlorinated dibenzo-p-dioxins, and airborne bacteria (Bacillus subtilis) were discharged from the stack gas produced by HCW incinerators [45, 46]. Landfill operations are commonly used to dispose of waste, and they are the easiest and most cost-effective way to manage HCW. However, a landfill liner system that is not properly designed or fails may release hazardous leachate and pollute groundwater [47]. During the incineration and post-combustion cooling, waste components dissociated and recombined, forming new particles known as products of incomplete combustion, which are toxic [39]. Liu et al. (2018) [48] stated that the HCW incineration activities would generate a high concentration of chlorides, heavy metals, and dioxins. The chlorines in plastics easily migrating to fly ash cause the high concentration of chloride. Thus, a high concentration of heavy metals and chloride in the incineration residues might cause potential environmental risks. In Mauritius, air pollution and water pollution always occur when incineration activities are carried out. Those ashes disposed of in landfill might contaminate the land and groundwater. The excessive heat and pollution generated from the incinerator would bring side effects to the humans and surrounding plants [49]. The disposal of nonbiodegradable biological waste (PPEs and other equipment) is the most concerning HCW created during the Covid-19 epidemic, which may have a negative influence on the environment. Although incineration has the ability to destroy pathogens and reduce volume, the incinerator operation might result in the generation of dioxins due to incomplete combustion [50]. Another challenge during the Covid-19 outbreak was the enormous burden on landfills in many countries, particularly developing countries, as a result of the increased disposal of HCW and hazardous waste in badly managed and exposed landfills, posing a risk to the environment and human health [43].

10.4 Treatment and Disposal of Healthcare Waste During the Covid-19 pandemic, the number of HCWs generated keep increasing, and proper treatment methods must be considered to ensure the reduction of HCWs exposure to the surrounding, which may affect humans and the environment. The

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Table 10.11  Advantages and disadvantages of HCW treatment [12, 39, 50] Treatment Landfill

Advantages Simple Low cost

Incineration

High reduction of waste volume Good disinfection and sterilization Stable operation Low cost Good disinfection effect Easy detection

Steam sterilization

Chemical disinfection

Microwave sterilization

Pyrolysis Plasma

Torrefaction

Simple and practical Rapid disinfection process Low cost High reduction of waste volume and no wastewater and toxic gases are produced in dry treatment Low environment pollution Fully automated and easy to operate High reduction of waste volume High reduction of waste volume Less harmful substances produced High waste volume reduction Less harmful substances are generated Heat energy may be recycled Enhanced energy production Reduced microbial activity

Disadvantages Generate a large number of harmful gases A large amount of land is needed; Soil and groundwater must be monitored throughout the time High cost Emission of toxic gases Air pollutant emissions Generate odor Appearance and volume remain almost unchanged Wastewater and toxic gases are produced in wet treatment Disinfectants are harmful to human

High operation cost Odour produced Not suitable for dangerous chemical Complex High cost High operation cost The system’s stability is easily influenced Self-heating High operation cost Emission of toxic gases

most common disposal of HCWs arethe sanitary landfill and incineration; however, these methods will cause risk to human health and environmental pollution. There are various advanced technologies that can be applied to treat the HCW efficiently and safely (Table 10.11).

10.4.1 Landfill Landfills can be used as the preferred method of waste disposal or for waste that has been processed in another technique. A landfill is a simple concept and low-cost waste management to dispose of the HCW, but proper management is necessary to avoid human health risks and environmental pollution [51]. A landfill is seen as an inefficient waste disposal option that necessitates waste segregation [42]. The leachate

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generated from the HCW contains high pollutants, such as heavy metals, which may contaminate the groundwater and soil [52]. Landfill activities also would generate dangerous gases such as volatile organic compounds and, particularly, ethylbenzene, toluene, benzene, and xylene isomers (BTEX). BTEX generated by the landfill may have an impact on air quality and be dangerous to human health [53]. Methane and carbon dioxide are the greenhouse gas emissions that are generated from the closed landfill site [54]. Regulated landfills, designed landfills, open landfills, and sustainable landfills are a few various types of landfill systems, each with its own unique procedures and features (Table 10.12). Improper landfill designs, such as the mixing of hazardous and nonhazardous wastes at healthcare facilities, as well as a lack of resources and skilled employees, limit its performance as a disposal method [55]. Landfill treatment design criteria should be based on the characteristics of HCW, combine soil and climate, choose a location with suitable geological conditions, and utilize appropriate civil technology to establish the site construction size [56]. Most countries have restricted the disposal of HCW in landfill unless that HCW is disinfected from infectious microorganisms [42]. As a result, the selection of HCW treatment Table 10.12  Characteristics of landfill designs [58] Type of landfills Open-dump landfills

Controlled landfills

Engineered landfills

Sustainable landfills

Explanation Inadequate dumpsite planning and management Waterlogging and leaching Inadequate or nonregulation of waste kinds accessing the site Lack of waste body confinement The public defecates openly No groundwater protection or drainage management Uncontrolled waste-materials combustion Do not follow the basic principles of waste compaction and covering The presence of an authoritative figure on the premises Basic waste management approaches to achieve waste control and consolidation Control of vehicle mobility and landfill access Excavation and dispersion of soil materials to bury the waste body Waste leachate discharged into lagoons Waste compacting into smaller layers Constructed by proper planning and the application of engineering procedures that provide waste control and surface water avoidance through the installation of well-designed and well-constructed surface drainage Venting of landfill gas out of wastes Location sitting, construction, and operational requirements are needed The process of waste decomposition is extremely slow Limited methane gas and odor production Aerobic biocell systems use air circulation to accelerate waste degradation. Produces less harmful leachate

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procedures must be based on economic, environmental, technical, and social considerations [57]. As landfill activities may have negative impacts on humans and the environment, as well as a lack of space in the future, alternate HCW treatment methods are required [12].

10.4.2 Incineration Incineration is a high-temperature oxidation process that converts waste into ash and smoke. To destroy dangerous or harmful germs, clinical waste must be thermally decomposed before disposal at a landfill [12]. HCW incineration has been the primary method used globally for disposing of HCW, including explosive compounds such as papers, polyvinyl chloride polymers, and abandoned items of equipment [51]. Since HCW mostly formed of organic hydrocarbons comprises more flammable elements and has a high calorific value, it may be degraded by incineration [56]. The temperature of the incinerator is greater than 800 °C. This high temperature might not only effectively destroy the germs but also incinerate and destroy the majority of organic matter, converting it to inorganic dust. The number of solid wastes might be decreased by 85–90% after incineration [59]. Furthermore, extensive oxidation of waste under high-temperature flame leads to the drying and combustion of the components, producing a residual mass that may be handled as a harmless material gas [7]. When setting up the incinerator to manage HCW, design elements such as turbulence and mixing degree must be addressed, as well as maintaining the waste’s existing moisture content. The filling condition of the combustion chamber, maintenance and overhaul, and temperature and residence time are also important incineration designs [56]. There are three incineration technologies used to decompose the HCW effectively (Table 10.13). In Malaysia, incineration is a preferred way of dealing with infectious and dangerous wastes. Its advantages include the elimination of pathogens and anatomic wastes, as well as the reduction of waste volume and energy resources [12]. Nonetheless, the possibility of secondary hazardous gas production remains the fundamental drawback of incineration, which leads to air pollution and poses health hazards [52, 61]. The HCW incinerator fly ash contains high contents of carbon constituents, dioxins, chlorides, and heavy metals [48]. HCW comprises a large proportion of chlorinated plastics, which easily transfer to fly ash after incineration, resulting in a high chlorine content in the fly ash. Hydrogen chloride is produced during HCW incineration as a result of an interaction between organic chlorides and hydrogen ions [62]. The hydrogen chloride is then evaporated and interacts with an alkali, such as calcium hydroxide or sodium hydroxide, in the flue. At last, the formation of sodium chloride and calcium chloride contributes to the high chlorine content of fly ash [63]. The dioxin emission from incineration is based on three theories (Table 10.14). Hydrogen chloride may combine with oxygen to create chlorine radicals with the assistance of formed catalysts, thereby indirectly increasing dioxin synthesis [64]. Fly ash from HCW incinerators also has a high concentration of

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Table 10.13  Incineration technologies Technologies Pyrolysis vaporization incineration

Rotary kiln incinerator

Plasma incinerator

Explanation Air detected below the theoretical chemical reaction is initially transported to the primary combustion chamber’s set furnace level for burning. The organic waste components are degraded into combustible gases to minimize dust created by turbulence induced by extra air. Therefore, particulate matter emissions are decreased, the residue is released constantly from the hearth’s end, and combustible gas is directed to the secondary combustion chamber. High temperatures exceeding 850 °C are required to completely destroy poisonous and dangerous components. Rotation in the incinerator not only allows wastes to be delivered automatically into the kiln but also enables wastes to be thoroughly mixed. Temperature can be as high as 1200 °C or more to destroy most hazardous substances. Transfer energy across the plasma, allowing waste to degrade fast into small molecules and even atoms. As a result, no intermediate products of large molecules exist. The majority of the gases generated are combustible and are directed to the secondary combustion chamber for final combustion. After basic purification, it is then released into the atmosphere.

References [59]

[59]

[60]

Table 10.14  Theories about incinerator dioxin emissions Theories De novo synthesis

Precursor synthesis

Incomplete combustion formation

Explanation Formed in the fly ash reaction by the reaction of a leftover carbon or metal catalyst in the post-combustion zone Solid-phase chlorides and gas-phase chlorines play dominant roles in the production of dioxin precursors. Heavy metals are vaporized in the incinerator and combined with chlorines to generate heavy metal chlorides in the flue at temperatures ranging from 180 to 600 °C, which function as catalysts in the creation of dioxins. Dioxin levels are strongly connected to other persistent organic pollutants such as chlorophenols, polychlorinated diphenyl ethers, chlorobenzenes, as well as a fraction of polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Produced as a by-product of the incomplete combustion of chlorinated plastics and the intermittent functioning of HCW incinerators.

References [66] [67, 68] [69]

[70]

[71]

carbon elements, such as unburned carbon and powder-activated carbon, which are the primary sources of dibenzofurans and polychlorinated dibenzo-p-dioxins in fly ash [36]. The fly ash from the HCW incinerator is additionally laden with heavy metals. A high concentration of zinc and chromium has been detected in HCW, perhaps from rubber, plastic wastes, syringes, and medical adhesive plaster [34]. Heavy

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metals are commonly found in HCW as volatile metallic chlorides, metal elements, metal oxides, and sulfates. Heavy metals are not eliminated during incineration; instead, a small proportion forms volatile metallic vapors and enters the flue gas, which may be released into the environment if not properly eliminated by washing and ball milling treatment. The majority of heavy metals relocate or concentrate in fly ash and bottom ash, based on the heavy metal complexes generated and their physiochemical characteristics during incineration [65].

10.4.3 Pyrolysis Pyrolysis is the process by which waste is destroyed in the absence of oxygen. This technique allows for significant waste volume reduction and is self-sustaining [52]; however, it needs high activation energy as well as the appropriate facilities [60]. The pyrolysis operates under high heat between 540 and 8300 °C. However, this technology requires high operation cost, high emission of toxic gases, and low energy output [72]. Pyrolysis disposal vehicles can be used to manage HCW that has been heated and distilled at high temperatures under anaerobic or anoxic conditions. Pyrolysis equipment must be minimized due to restricted space in the vehicle, requiring more compact structures and components [3]. The organic components of HCW can be disposed of through the pyrolysis method. The organic component of HCW is heated at a temperature between 600 and 900 °C under oxygen-depleted or oxygen-free conditions. Heat is utilized to break the bonds of the molecules, converting high-molecular-weight organics into flammable gases and liquid fuels. The pyrolysis will mainly generate some gases such as carbon dioxide, carbon monoxide, methane, hydrogen, and volatile organic compounds [7, 56]. Czajczyńska et al. (2017) [73] revealed that the temperature of about 400–500 °C and the heating rates of 5–20 °C/min under nitrogen flow is applied for the slow pyrolysis of organic waste like paper, food waste, wood, and natural textiles. Fast pyrolysis is more complex, although it is also utilized. Those inorganic waste may also be disposed of using the pyrolysis process, which produces a gas with less carbon dioxide and lighter hydrocarbons and a liquid with a higher oil fraction and a lower aqueous component. Pyrolysis is a sustainable and effective liquid fuel recovery process from fossil-based solid waste that can help solve landfilling issues and pollution management [74]. Thus, the pyrolysis technology has sufficient economics, minimal secondary pollution, and a high energy recovery rate. The pyrolysis technique may use the gas produced by HCW treatment to lower processing costs, lower energy consumption, accomplish energy circulation, and achieve economic viability [7].

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10.4.4 Steam Sterilization High-temperature steam disinfection is a moisture heat treatment technique that applies to the transmission medium with a high-temperature steam to kill pathogens [59]. Steam sterilization is preferred for the treatment of sharps and infectious HCW but not for the chemical and pharmaceutical HCW [3]. This method relies on the treatment of shredded HCW at 121 °C for more than 20 minutes with 100 kPa pressure. As a result of the pressure steam penetrating the insides of materials, the microbial protein is destroyed, denatured, and coagulated [7, 56]. The HCW is sterilized with saturated steam at temperatures exceeding 134 °C for 45 minutes before being broken down and packaged for disposal or incinerated. To assure that the emissions satisfy the requirement, the equipment is outfitted with a flue gas and water vapor purification system. The setup and operation of the device require only water and high voltage power, with a voltage of 380 V. The equipment’s working area for mobile steam sterilization is just 50 m2. The equipment is primarily made up of numerous systems, including crushing, steam generation and disinfection, feeding, waste gas, and wastewater treatment [3]. Steam quality, temperature, and action duration are key criteria to consider while developing a steam sterilization process. Insufficient air removal in the container might influence sterilizer temperature, treatment cycle length affects sterilization completeness, and the size of the waste feed impacts steam penetration [56]. Yaman (2020) [75] indicated that the efficient sterilization of HCW should be operated at a contact time of 45 minutes at a temperature of 150 °C under the steam pressure of 5 bar. During the steam treatment system operation, the number of active Bacillus sterothermophilus reduced dramatically. Steam sterilization is a safer and more cost-effective treatment method compared to incineration because steam sterilization releases fewer hazardous gases and greenhouse gases. To decrease greenhouse gas emissions, it is proposed that biodegradable HCW collection bags, solar energy panels on sterilizing facility roofs, and electric-powered HCW collecting vehicles be used. Maamari et al. (2016) [76] revealed that the efficient sterilization of dialysis cartridges in a pilot 60  L steam treatment system required more than 20 minutes at 144 °C without a premixing/fragmenting step. However, 10 minutes of contact time at 144 °C is sufficient to sterilize the HCW by using steam sterilization with premixing and pre-fragmenting paddles. High temperatures in the steam sterilization system are not recommended because it produces toxic volatile organic compounds and has a poor reduction rate [77].

10.4.5 Microwave Sterilization Microwaving is a steam-based technique that employs high-intensity radiation to heat the moisture in a waste sample or to add additional steam to sterilize infected and harmful elements [12]. Microwaves are electromagnetic waves with frequencies

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ranging from radio to infrared, which are 300 MHz to 3000 MHz [7, 52, 56]. Xu et al. (2020) [56] stated that the electromagnetic wave sterilizing theory is based on the fact that it may be absorbed by protein, fat, and water. It employs the properties of selective energy absorption by microbial cells and inserts it in the energy field of electromagnetic wave high-frequency oscillation, causing the liquid molecules of microorganisms to vibrate at the frequency of the electric field. The energy in the cell membrane rapidly grows, resulting in high temperature and, finally, cell death, which kills the pathogens in the HCW during the vibration. The microwave disinfection technique is distinguished by its energy efficiency, light damage, quick action, low heat loss, low action temperature, and low environmental pollution, with no residue or harmful wastes produced after disinfection [59]. A particularly designed microwave system can sufficiently inactivate the microorganisms; nonetheless, the operation must be tightly monitored by special microwave equipment [59, 78]. Banana et al. (2013) [79] indicated that the HCW could be sterilized sufficiently with 5  minutes of exposure to microwave irradiation, and the method is boosted with rising time and temperature. At long exposure time and high applied voltage, the harmful microbes are decreased below the detection limit. Although the microwave can kill pathogens, gram-negative bacteria that are resistant to microwave irradiation, and microbe regeneration ability is based on the moisture level of HCW [79]. During the COVID-19 pandemic, movable microwave sterilization is used to handle the HCW. The machine uses an automated disposal system that includes microwave disinfection, material crushing, hydraulic lifting, and spiral discharge. The system can achieve a sterilization rate above 99.99%. Due to the great degree of automation, the overall process only requires an electric drive and only one laborer to operate [3]. Mahdi and Gomes (2019) [80] mentioned that one of the important factors that might regulate the treatment process is the power of radiation. When the radiation strength is low, the time required to completely destroy germs is substantially longer than when the power is high.

10.4.6 Chemical Disinfection Technology Chemical disinfection is applied by adding the disinfectants such as chlorine dioxide, calcium hypochlorite, and sodium hypochlorite when mixed with the shredded HCW and stayed for a sufficient time [59]. Crushed HCW was combined with chemical disinfectants and was kept under negative pressure. Organics are decomposed, and pathogenic bacteria are either inactivated or destroyed. Chemical disinfectants end up leaving no residual hazards because both microorganisms and microbial spores are destroyed [7]. Giakoumakis et al. (2021) [7] revealed that chemical technology is a cheap, simple, and effective technique that results in quick disinfection and good deodorization of the finished product, as well as a high waste volume reduction with no waste liquid or gas waste formation. The effectiveness of the technology is mainly based on the chemical composition, temperature, quantity, and concentration of the disinfectants, the level of contamination, the type and biological characteristics of

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microorganisms, as well as the pH, exposure time, and the mixing requirements for every kind of waste [81]. Chlorine dioxide, calcium hypochlorite, and sodium hypochlorite are utilized because those chemicals are safe, noncorrosive to items, colorless, odorless, inflammable, tasteless, and easily soluble in water. The chemical disinfection technology can be considered when the quantity of HCW generated is low [59].

10.4.7 Plasma Technology Plasma technology is the use of an electric current that is conducted through an inert gas to ionize and induce an electric arc to generate high temperatures of up to 1700 °C, resulting in the breakdown of HCW [52]. The waste will be dried and heated rapidly because the process can achieve an extremely high temperature of 1200–3000  °C within 1/1000 seconds [56]. Plasma technology is not only used for highly cytotoxic drugs, but it is also used for both organic and inorganic materials [52]. The mixed combustion gases that are generated from the plasma technology are hydrogen gas, carbon monoxide, and alkanes. The process can kill the harmful microbes in the waste, and the finished products can be disposed of in landfill [7, 56]. The key parameters influencing plasma operation are the equipment’s power and the amount of energy available. Somehow, the characteristics of the HCW may affect the electromagnetic wave [56]. Figure 10.9 presents the flow diagram of the plasma gasification. When the equivalence ratio (ER) of HCW is low, the gases emitted could be up to 25.37% carbon monoxide, 32.78% hydrogen production, and 78.61% cold gas efficiency. Thus, the lower the ER values, the higher the content of hydrogen, carbon monoxide, and cold gas efficiency will be obtained. The ER values are known as the ratio of real and stoichiometric ratios between the mass flow rate of oxidizer and fuel feeds [82]. Erdogan and Yilmazoglu (2020) [82] indicated that the lower

Fig. 10.9  Plasma gasification process flow diagram [84]

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heating value of HCW is high, which is 5.640 MJ/Nm3, compared to lignite coal in plasma gasification. When the lower heating value is high, the exhaust temperature will be high. Cai and Xu (2021) [83] revealed that the thermal plasma treatment may be influenced by a few parameters, such as feed rate, residence time, reactor environment, temperature, and feed composition. During the Covid-19 pandemic, plasma gasification is one of the most suitable treatment technologies to treat and handle various HCWs, and the volume reduction postprocessing of HCW could be up to 95%. As a by-product of the process, vitrified slag can be utilized to make bricks, tiles, and aggregates [84].

10.4.8 Torrefaction Torrefaction is the process of depolymerizing biomass. The torrefaction is a biomass pretreatment process, which is mainly intended to enhance the fuel characteristics of the biomass by changing the physiochemical properties of biomass and finally enhance its applicability in the thermal conversion process [7, 85]. Torrefaction technology is often carried out at temperatures ranging from 200 to 300 °C in an inert environment with the goal of changing the chemical characteristics of biomass. This technique is an endothermic process that needs the energy to function and sustain. The products generated from the torrefaction contain a high calorific value and low moisture content. The torrefaction will improve the energy density, reduce microbial activity, and improve the grind ability [86, 87]. Various parameters will influence the torrefaction treatment process, such as volatile matter, moisture content, structural changes of biomass, hydrophobicity, ash content, energy density, and grind ability [85]. Hemicellulose is the element that destroys the most in torrefaction, whereas cellulose and lignin break down to a lesser level and generally occur at higher temperatures of 250 °C and beyond. When the temperature of torrefaction rises, the solid biochar production falls, and the volatile fraction yield rises [86]. Swiechowski et al. (2021) [88] demonstrated that the medical peat waste treated with the torrefaction could upcycle to carbonized solid fuel, which improved the fuel properties of peat from 19 to 21.3 MJ/kg. The peat decomposition mainly took place at 200–550 °C. Since the carbonized solid fuel has the same energetic properties as lignite, as a result, it can be considered as co-fuel to the lignite incineration plant or for gasification for energy [88]. Giakoumakus and Sidiras (2018) [89] indicated torrefaction might be achieved by decomposing medical cotton waste in a blast furnace. The circumstances applied were non-isothermal heating up to 340 °C for 20–50  minutes. The torrefied medical cotton became sterilized at the applied conditions with 26% higher gross heat of combustion compared to untreated medical cotton; thus, medical cotton is considered a recycled material with boosted heating value suitable for energy purposes through the torrefaction process. However, there are still some challenges that need to be faced when applying torrefaction

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technology, such as operation cost, emissions and ash-related issues, and self-­ heating [90].

10.5 Co-disposal of Healthcare Waste HCW may dispose of other solid wastes such as hazardous waste and municipal solid waste. HCW may also be disposed of it in the cement kiln as co-disposal. Those methods can be considered when a high amount of HCW is produced during the Covid-19 outbreak. The methods will help overcome the issue of overload capacity of the HCW incineration.

10.5.1 Co-disposal of Healthcare Waste and Municipal Solid Waste According to the technical standards, Ma et al. (2020) [91] revealed that the municipal solid waste incineration system’s core technological procedure is comparable to the HCW incineration system. The coronavirus is very sensitive to the temperature in the HCW incinerator system, and the virus can be killed at the temperature of 56 °C for 30 minutes. The temperature applied in the municipal solid waste incinerator system is above 850 °C, and the residence time of municipal solid waste in the furnace is normally 1–1.5 hours to completely inactivate the coronavirus. Thus, with an acceptable mixing ratio, HCW may be disposed of in municipal solid waste incinerator plants [92]. HCW rose from 40 tonnes/day to 200 tonnes/day during the Covid-19 outbreak. Due to a large number of HCWs discharged, the current HCW incineration system is inadequate [93]. Thus, municipal solid waste incinerator facilities have been effectively used in HCW emergency disposal in China and across the world. Though HCW can be treated in the municipal solid waste incineration system, the flue gas concentration of hydrogen chloride and dioxins will rise due to the high plastic component of the HCW [3]. Hence, when co-incinerating with municipal solid waste, chemical waste must be less than 5% of the total amount of mixed waste [92]. As incineration is a mature, robust, and adaptable technology, municipal solid waste grate incinerators might be utilized for emergency HCW disposal [91]. Other than chemical waste, sharps waste, pathological waste, and infectious waste can be disposed of with municipal solid waste [3, 92]. Six barriers such as negative pressure, better feeding process, disinfection, diversion, strengthened packaging, and sanitation protection can effectively prevent infections during the co-disposal of HCW and municipal solid waste [3, 91]. Figure 10.10 shows the co-disposal of HCW by municipal solid waste incineration technique.

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Fig. 10.10  Co-disposal of HCW by municipal solid waste incineration technique

Due to system adjustments, upgrades of delicate equipment, and higher activated carbon consumption for flue gas purification, co-incineration of HCW may be adverse to operating costs and equipment life management. As a result, municipal solid waste incinerators are suggested for short-term rather than long-term disposal, and future co-incineration of HCW needs additional study on enhanced municipal solid waste incineration technology.

10.5.2 Co-disposal of Healthcare Waste and Hazardous Waste Hazardous waste incineration facilities have the same operational and managerial criteria as HCW incineration facilities, and these facilities might be a preferable alternative option for HCW disposal. For many years, HCW has been co-­incinerated in hazardous waste incineration plants in China and worldwide. Flue gas purification, waste heat utilization, pretreatment, incineration, feed, and other auxiliary systems are all part of the hazardous waste incineration system [94]. The hazardous waste contains various harmful components, so the compatibility of waste needs to be concerned. To assure the kiln’s steady functioning, hazardous waste and HCW should be mixed in the incinerator according to their composition and calorific value. To avoid concentrated incineration of dangerous components and to manage the concentration of acidic pollutants, the waste composition should be regulated [3]. Zhao et al. (2022) [3] also revealed that both alkali metals and halogens should not be burnt at the same time because they can generate low melting salts, and large low melting salts can induce slag coking, affecting kiln operation and refractory material service life. Ma et al. (2020) [91] suggested that rotary kiln incineration can be used to dispose of hazardous waste and HCW due to the incinerator’s wide adaptability property and reliable operation. The temperature of the rotary kiln is

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Fig. 10.11  Hazardous waste incinerator systematic diagram [91]

maintained above 850 °C, and after approximately 60 minutes of high-temperature incineration, the hazardous material is completely incinerated into high-­temperature flue gas and slag residue [91]. Figure 10.11 shows the process of hazardous waste and HCW in the hazardous waste incinerator.

10.5.3 Co-disposal of Healthcare Waste in Cement Kiln A cement kiln can be applied to dispose of the HCW due to its strong alkaline atmosphere and 1500 °C high temperature that can instantly destroy microorganisms and viruses. Cement kiln co-incineration technology requires placing HCW that meets the standards into a cement kiln for disposal while also producing cement clinker. Few studies have shown that the co-disposal of HCW in cement kilns is safe, devoid of secondary pollution, and can eliminate the potential of HCW infection [3]. Li (2020) [95] reported that over 4 tonnes of HCW were carried to Yangxin County’s cement business for safe disposal. HCW would be quickly decomposed and gasified at a temperature of around 1150 °C. Throughout the process, the turbulent burning environment, strong alkaline, and high temperature prevent the formation of dioxins. Various countries have applied this practice to dispose of the HCW during the emergency phase. The co-disposal of HCW in cement kilns allows for the recovery of mineral value and energy from waste while producing cement [96]. Figure 10.12 shows the co-disposal of HCW in the cement kiln technique. Chen and Guo (2020) [11] indicated that HCWs normally consist of 3–5% of chlorine content, which is greater than that of raw materials and general hazardous wastes; as a result, it is critical to thoroughly mix the HCW and other wastes. As chlorine may have a corrosive impact on the kiln, the kiln condition, emissions, and clinker quality variations should be observed to assure proper operation of the cement kiln and clinker quality during the addition [11]. Liu et al. (2021) [97] suggested that household waste incineration, facilities for hazardous waste incineration, cement kiln coordinated disposal, and other facilities should be fully exploited for synergy disposal. Cleaning and disinfection equipment, special loading equipment, and specific unloading sites should be installed at these emergency disposal facilities.

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Fig. 10.12  Co-disposal of HCW in cement kiln technique [3]

There are various studies conducted to determine the quality of the concrete when the HCW is mixed with the cement in the cement kiln. Kumar et al. (2022) [98] demonstrated the strength of reinforced geopolymer concrete that is influenced by the incinerated HCW ash and waste glass powder. When the incinerated HCW ash and waste glass powder were added to the reinforced geopolymer concrete, the concrete compressive strength was increased, and the compressive strength achieved was 45.07% higher than reinforced cement concrete. Not only the compressive strength increased, but the ductility, serviceability, split tensile strength, as well as energy absorption properties, and flexural deflection were enhanced [98]. Nonetheless, Akyildiz et al. (2017) explained that the concrete compressive strength would reduce with the rise of the HCW incineration bottom ash (MWBA). The existence of MWBA in concrete would minimize heavy metal leach because the cement-based solidification process was able to inhibit the mobilization of heavy metals contained in MWBA except for Cr and Zn, where heavy metal immobilization increased with increasing curing time. Table 10.15 represents the heavy metal leaching and compressive strength of concrete under the different ratios of MWBA. Kumar et al. (2021) [99] explained that incinerated HCW ash is a toxic waste material with the ability to cause serious health damage to the environment and humans, and the most efficient approach to dispose it is to use it as a construction material, which may minimize the dangerous hazardous components. When the incinerated HCW ash was substituted with the ground granulated blast furnace slag, the flexural strength, compressive strength, and split tensile strength were increased up to 30% substitution. Beyond 30% replacement of incinerated HCW ash in the geopolymer concrete, that strength started to decrease due to high calcium concentration in the binder and less geopolymerization. The compressive and flexural strength of the concrete was increased with 30% of incinerated HCW ash replacement due to the micro-filler effect and the formation of calcium aluminosilicate hydrate gels and calcium silicate hydrate during the hydration process [99]. Mohan et al. (2022) [100] utilized personal protective equipment with manufactured sand and river sand as fillers to develop a new composite concrete. When compared to

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Table 10.15  Heavy metal leaching and compressive strength of concrete under the different ratios of MWBA [37] MWBA ratio (%) 0 5 10 15 20 25 30 40 50

Compressive strength (MPa) 37.98 37.97 36.17 31.26 29.43 25.21 23.71 14.70 11.31

Heavy metal (mg/L) Cd Fe Cu