High-Risk Pollutants in Wastewater

High-Risk Pollutants in Wastewater presents the basic knowledge regarding the diversity, concentrations, and health and environmental impacts of HRPs in municipal wastewater. The book summarizes information on the types (e.g. heavy metals, toxic organics and pathogens) and toxicities of HRPs in wastewater. In addition, it describes ecological and health hazards arising from the living things’ direct/indirect contacts with the HRPs during their full lifecycles (generation, disposal, discharge and reuse) in wastewater or water environments. Sections cover the concepts of appropriate technology for HRP hazard/risk assessment and wastewater treatment/reuse and the issues of strategy and policy for increasing risk control coverage.

Finally, the book focuses on the resolution of water quality monitoring, wastewater treatment and disposal problems in both developed and developing countries.

• Presents information on HRPs and their risk assessment and control technologies
• Provides basic knowledge regarding the diversity, concentrations, and health and environmental impacts of HRPs in municipal wastewater
• Summarizes information on the types (e.g. heavy metals, toxic organics and pathogens) and toxicities of HRPs in wastewater

• Language: English
• Publisher: Elsevier Science
• Release date: Nov 1, 2019
• ISBN: 9780128175149

Book preview

High-Risk Pollutants in Wastewater

Editors

Hongqiang Ren

Professor and the Dean, School of the Environment, Nanjing University, Nanjing, China

Xuxiang Zhang

Professor, School of the Environment, Nanjing University, Nanjing, China

Table of Contents

Cover image

Title page

Copyright

Contributors

Chapter 1. Introduction

1.1. Environmental high-risk pollutants

1.2. Control of HRPs in wastewater

1.3. Objective and contents of this book

Chapter 2. Chemical HRPs in wastewater

2.1. Heavy metals

2.2. Persistent organic pollutants

2.3. Pharmaceutical and personal care products

2.4. Endocrine-disrupting chemicals

2.5. Other HRPs

2.6. Summary

Chapter 3. Biological HRPs in wastewater

3.1. Bacteria

3.2. Viruses

3.3. Protozoa

3.4. Helminths

3.5. Biotoxins

3.6. Antibiotic resistance

3.7. Summary

Chapter 4. Technologies for detection of HRPs in wastewater

4.1. Detection techniques of heavy metals in wastewater

4.2. Detection techniques of organic HRPs in wastewater

4.3. Detection of biological HRPs

4.4. Summary

Chapter 5. Ecological safety hazards of wastewater

5.1. Exposure pathways

5.2. Damage to organisms

5.3. Damage to populations and community

5.4. Damage to ecosystem

5.5. Summary

Chapter 6. Human health hazards of wastewater

6.1. Agricultural irrigation

6.2. Antibiotic wastewater

6.3. Oily wastewater

6.4. Aerosol from reclaimed water

6.5. Summary

Chapter 7. Assessment technologies for hazards/risks of wastewater

7.1. Toxicity evaluation of wastewater

7.2. Health and ecological risk assessment

7.3. Summary

Chapter 8. Physicochemical technologies for HRPs and risk control

8.1. Adsorption technologies

8.2. Advanced oxidation

8.3. Membrane separation technologies

8.4. Combination process technologies

8.5. Emerging technologies

8.6. Summary

Chapter 9. Biological technologies for cHRPs and risk control

9.1. Biological transformation of cHRPs in wastewater

9.2. Conventional biological technology

9.3. Biofiltration technology

9.4. Membrane biotechnology

9.5. Constructed wetland (CW) systems

9.6. Bioaugmentation technology

9.7. Integrated technologies for toxic organic wastewater treatment

9.8. Summary

Chapter 10. Technologies for bHRPs and risk control

10.1. Conventional disinfection technologies

10.2. Biological treatment progresses

10.3. AOPs

10.4. Natural disinfection

10.5. Other technologies for bHRPs removal

10.6. Summary

Chapter 11. Risk management policy for HRPs in wastewater

11.1. Risk thresholds and criteria for different disposal or reuse purposes

11.2. Risk management policies and regulations

11.3. Problems and future development of risk management of HRPs

11.4. Summary

Abbreviations

Index

Copyright

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High-Risk Pollutants in Wastewater

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Contributors

Jinju Geng, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Xiwei He, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Haidong Hu,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Hui Huang, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Kailong Huang, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Shuyu Jia,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Xiaofeng Jiang,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Kan Li,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Mei Li, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Ruxia Qiao,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Hongqiang Ren, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Cheng Sheng,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Jinfeng Wang,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Bing Wu, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Gang Wu,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Ke Xu,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Lin Ye, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Jinbao Yin, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Xuxiang Zhang, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Yan Zhang, PhD ,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Huajin Zhao,     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Chapter 1

Introduction

Xuxiang Zhang, PhD, and Hongqiang Ren, PhD     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

1.1 Environmental high-risk pollutants

1.2 Control of HRPs in wastewater

1.3 Objective and contents of this book

1.1. Environmental high-risk pollutants

In recent years, in addition to large quantities of pollutants such as COD and ammonia nitrogen, new problems regarding the toxic substances in the environment have been highlighted. In China, nearly 50,000 kinds of chemicals are produced and used for different purposes, and this number is still increasing, as many new drugs, antibiotics, and pesticides are being continuously synthesized for use. Besides the chemicals, some biological substances (e.g., bacterial pathogen, viruses, and antibiotic resistance genes) coming from living organisms can also lead to adverse effects on both human and the environment. Notably, wastewater is an important environmental reservoir for both the chemical and biological substances, which can introduce them into receiving water body along with wastewater discharge. Many of the chemicals are structurally complex and are stable and difficult to degrade. Owing to the cumulative and persistent characteristics, the substances cannot be completely removed in the existing conventional wastewater treatment systems; thus, considerable amount of the substances or their transformed products enter water and soil environments through the discharge from industrial or urban point sources, as well as urban or agricultural nonpoint sources. The substances entering the environment are called pollutants, and a variety of them have been frequently detected in natural waters such as rivers, lakes, oceans, and groundwater in recent years. It has been estimated that over 4000 kinds of trace organic pollutants are present in water environment in China, which have become an important factor endangering human and environmental health.

Although most of the pollutants have low concentrations or abundance in the environment, many of them can accumulate in organisms and spread and enrich through the food chain, leading to chronic poisoning of animals or human. The other part of pollutants is not stable, but they are continuously discharged into natural water due to continuous production and extensive use for human living and animal husbandry. After long-term even full-lifecycle exposure, the phenomenon of pseudopersistence is formed in animal or human bodies to induce toxicities. Therefore, the chronic toxicity, microbial resistance, and synergistic toxicity caused by the substances have received growing concerns.

High-risk pollutants (HRPs) are defined as the highly diverse chemical and biological matters with high toxicity and complicated toxicological mechanisms that can pose serious risks to ecosystems and human health even at low concentrations. HRP pollution is regarded by the United Nations Environment Program as an urgent issue that needs to be dealt with through global cooperation, and since the 1990s many developed countries have introduced regulations to control HRPs. In 2014, China also issued the High-Risk Pollutants Reduction Action Plan. European legislation follows the precautionary principle and has introduced stringent threshold limits (100   ng/L) for many chemical HRPs in water environments. Industrial and municipal wastewater contains a variety of HRPs including highly diverse chemical and biological substances with high toxicities, posing serious risks to ecosystems and human health even at low concentrations.

1.2. Control of HRPs in wastewater

Water shortage is one of today's grand challenges as many of the rivers or lakes in the world become polluted, and wastewater reuse or deep cleaning is considered effective in solving the problem. Presence of a variety of HRPs in industrial and municipal wastewater constrains the advanced treatment and reuse of the wastewater. Evaluation and control of HRPs in wastewater is an important issue for water pollution control, and only measuring quantitative integrated indices, such as CODCr and BOD5, is not sufficient for assessing and controlling the risk induced by wastewater discharge, so biotoxicity indices and standards have been recommended as alternatives in many countries.

Recently, advanced treatment and reuse of wastewater have been increasingly implemented in many countries to solve the problems of serious water shortage and pollution. The advanced physicochemical technologies include membrane filtration, activated carbon absorption, and advanced oxidation, but they are neither environmentally nor economically sustainable, which seriously constrains their practical application. As a sustainable and cost-efficient alternative, biodegradation of HRPs either by endogenous or bioaugmented microbiota is considered as promising technologies. However, various bottlenecks hamper the implementation of biodegradation as a robust HRP removal technology that combines removal efficacy, energy efficiency, and risk reduction, and the key problem to be solved is how to eliminate the microbial constraints that limit biodegradation of HRPs present as mixtures in wastewater. Therefore, application of appropriate hazard/risk assessment and treatment technologies, which are effective, low cost, and simple to operate, is a key component in any strategy aimed at reducing ecological and health risks arising from wastewater discharge and reuse.

1.3. Objective and contents of this book

Currently, many books on the market have been focused on the treatment technology and engineering of wastewater to meet the discharge or reuse standards required by the governments of different countries, but provide little information regarding HRPs and their risk assessment and control technologies. Therefore, the major objectives of this book entitled High-Risk Pollutants in Wastewater are as follows:

(1) This book presents the basic knowledge regarding the diversity, concentrations, and health and environmental impacts of HRPs in wastewater. The book summarizes the information of the types (e.g., heavy metals, toxic organics, and pathogens) and toxicities of HRPs in wastewater, and also describes ecological and health hazards or risks arising from the living things' direct/indirect contacts with the HRPs during their full lifecycles (generation, disposal, discharge, and reuse) in wastewater or water environments.

(2) This book presents the concepts of appropriate technology for HRP hazard/risk assessment and wastewater treatment/reuse and the issues of strategy and policy for increasing the risk control coverage. The book focuses on the resolution of water quality monitoring and wastewater treatment and disposal problems in both developed and developing countries, and the concepts presented are wished to be valid and applicable in risk warning and control for wastewater discharge into the environment and reuse for any purposes.

This book mainly includes 11 chapters: (1) Introduction; (2) Chemical HRPs in wastewater; (3) Biological HRPs in wastewater; (4) Technologies for detection of HRPs in wastewater; (5) Human health hazards of wastewater; (6) Ecological safety hazards of wastewater; (7) Assessment technologies for hazards/risks of wastewater; (8) Physicochemical technologies for HRPs and risk control; (9) Biological technologies for HRPs and risk control; (10) Wastewater disinfection technologies; and (11) Risk management policy for HRPs in wastewater.

This book delivers the idea of recognition, assessment, and control of HRPs, including highly diverse chemical and biological matters with high toxicity at low concentrations. The book was technologically written, and does not involve traditional pollutants that also affect environmental and ecological health, such as nitrogen and phosphorus in wastewater. This book is expected to be used as a textbook or reference book for the graduate students majoring in environmental science, environmental engineering, and civil engineering, and will also provide a useful reference for wastewater treatment plant personnel, industrial wastewater treatment professionals, government agency regulators, environmental consultants, and environmental attorneys.

Chapter 2

Chemical HRPs in wastewater

Gang Wu, Jinfeng Wang, and Jinju Geng, PhD     State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

Abstract

Chemical high-risk pollutants (HRPs) in wastewater have received growing concerns in recent years for their persistent input and potential threat to ecological environment and human health. Heavy metals, persistent organic pollutants (POPs), pharmaceutical and personal care products (PPCPs), endocrine disrupting chemicals (EDCs), and disinfection by-products (DBPs) are the most frequently detectable chemical HRPs in wastewater. Understanding the environmental behavior and transformation characteristic of chemical HRPs is important to their removal and risk reduction in environment. In this chapter, according to the different types of chemical HRPs in municipal wastewater and industrial wastewater, the source of different chemical HRPs are introduced at first. Then, the occurrence and contamination levels of chemical HRPs are summarized item by item. Furthermore, the migration and transformation processes of chemical HRPs and the major factors are described in detail. This information contributes not only to further understand the fate of chemical HRPs but also to control the HRPs in wastewater.

Keywords

Chemical HRPs; Occurrence; Source; Transformation; Wastewater

2.1 Heavy metals

2.1.1 Sources of heavy metals in wastewater

2.1.2 Occurrence and concentrations of heavy metals in wastewater

2.1.3 Migration and transformation of heavy metals in wastewater

2.2 Persistent organic pollutants

2.2.1 Sources of POPs in wastewater

2.2.2 Occurrence and concentrations of POPs in wastewater

2.2.3 Migration and transformation of POPs in wastewater

2.3 Pharmaceutical and personal care products

2.3.1 Sources of PPCPs in wastewater

2.3.2 Occurrence and concentrations of PPCPs in wastewater

2.3.3 Migration and transformation of PPCPs in wastewater

2.4 Endocrine-disrupting chemicals

2.4.1 Sources of EDCs in wastewater

2.4.2 Occurrence and concentrations of EDCs in wastewater

2.4.3 Migration and transformation of EDCs in wastewater

2.5 Other HRPs

2.5.1 Sources of other HRPs in wastewater

2.5.2 Occurrence and concentrations of other HRPs in wastewater

2.5.3 Migration and transformation of other HRPs in wastewater

2.6 Summary

References

Further Reading

In recent years, more and more chemicals are synthesized and used to meet people's rising living standards. It is reported that the chemicals registered under the Chemical Abstract Service (CAS) have been over 140 million (Li and Suh, 2019). Once they are used and discharged, these chemicals will exist in various environment medium. Human beings can be exposed to these chemicals. This raises a serious issue for people to pay more attention on the adverse effect of these chemicals on ecosystem. However, it is impractical to focus on all the chemicals registered in CAS (Whaley et al., 2016). Some prioritized chemicals, especially for the chemicals with high risk, should be given enough attention firstly.

Chemical high-risk pollutants (HRPs) refer to the chemicals with high ecological risk to ecosystem (Rasheed et al. 2019; Zhou et al., 2019). These HRPs (anthropogenic or natural) include but are not limited to heavy metals, persistent organic pollutants (POPs), pharmaceuticals and personal care products (PPCPs), and endocrine disrupting chemicals (EDCs) (Li and Suh, 2019). Generally, wastewater is one of the major sink for these HRPs once they become consumer products. The occurrence of these HRPs in wastewater will pose some potential adverse effect on the downside ecosystem inevitably (Tran et al. 2017). Therefore, chemical HRPs in wastewater should be given enough attention. Understanding the environmental behavior and transformation characteristics of chemical HRPs is important for their removal and risk reduction in environment. In this chapter, the category, source, concentrations, migration, and transformation of chemical HRPs in wastewater are summarized in detail. This is beneficial to fill the knowledge gap of chemical HRPs in wastewater.

2.1. Heavy metals

Heavy metals refer to any metallic element that has a relatively high atomic mass (＞5   g/cm³) and are toxic or poisonous even at a low concentration (Nagajyoti et al., 2010). Heavy metals, which are significantly toxic to environmental ecology, mainly include cadmium (Cd), chromium (Cr), nickel (Ni), mercury (Hg), lead (Pb), manganese (Mn), copper (Cu), and zinc (Zn). The source, occurrence and contamination level, and fate of heavy metals in wastewater, which will provide a clear understanding on ecological risk of metals in wastewater to readers, are summarized as follows.

2.1.1. Sources of heavy metals in wastewater

Industrial activities are a significant source of heavy metals (Santos and Judd, 2010). Mining operations and ore processing, textiles, metallurgy and electroplating, dyes and pigments, paper mills, tannery, and petroleum refining are the main sources of heavy metals in wastewater. Mine wastewater are often acidic and contain dissolved heavy metals, such as Cd, Cr, Zn, and Mn (Hedrich and Johnson, 2014), which mainly come from mineral processing and washing (Zaranyika et al., 2017). Plating rinsing process often introduces Cr, Cu, and Hg into metallurgy and electroplating wastewater (Hideyuki et al., 2003). Metallized complexed azo dye production contributes the presence of most of the heavy metals in textiles wastewater (Edwards and Freeman, 2010). Heavy metals in dyes and pigments mainly are derived from textile warp size, dye, and surface-active agents (Halimoon and Gohsoo Yin, 2010). Paper mills contribute to a high concentration of Hg in wastewater (El-Shafey, 2010). Cr is the dominant heavy metal in tannery wastewater (Mella et al., 2015). Heavy metals from petroleum refining are derived from waste oil-refining catalyst, which mainly include Ni, Hg, Pb, Cr, and Cd. In addition, some heavy metals, such as Cd, Cr, Hg, Ni, Pd, and As have also been recognized in municipal wastewater treatment plants.

2.1.2. Occurrence and concentrations of heavy metals in wastewater

Converging from different sources, heavy metals, for example, Cd, Cr, Ni, Hg, Pb, Mn, Cu, and Zn, have been frequently detected in municipal and industrial wastewater. For example, Ustun (2009) investigated nine metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in wastewater treatment plants (WWTPs) in Bursa (Turkey) for 23 months in 2002 and 2007 and found that all the metals were detectable. Teijon et al. (2010) assessed the contaminants level of four heavy metals (Cd, Ni, Hg, and Pb) in WWTPs and only Ag was occasionally under the detection limit. Despite of the wide distribution of different heavy metals in WWTPs in geologically different regions, the concentration levels of heavy metals show great variation. Tables 2.1–2.6 list the main heavy metals and their concentrations in both municipal wastewater and industrial wastewater located in different countries.

As listed in Table 2.1, Cd and Pb show high detection frequency in the WWTPs of 13 countries. Concentrations of Cd range from not detected (ND) to 220   μg/L, with the highest concentration in the WWTPs of Turkey. Meanwhile, concentrations of Pb range from ND to 6860   μg/L, with the highest concentration in the WWTPs of China. In addition, Ni and Cr were found to have high levels in the wastewater from Greece and Italy, respectively.

As listed in Table 2.2, Cd often occurs in the industrial wastewater generated from mining operations and ore processing, petroleum refining, textiles production, metallurgy and electroplating, dyes and pigments, paper mills, and tannery. Concentrations of Cd in industrial wastewater range from ND to 200   mg/L, and metallurgy and electroplating wastewater often contains high concentrations of Cd (up to 200   mg/L).

As shown in Table 2.3, Cr often occurs in the industrial wastewater generated from mining operations, ore processing, petroleum refining, textiles production, metallurgy and electroplating, paper mills, and tannery. Concentrations of Cr in industrial wastewaters vary greatly, ranging from 12   μg/L to over 1700   mg/L. Among the different types of industrial wastewater, tannery wastewater often contains the highest concentrations of Cr (sometimes over 500   mg/L).

Hg often occurs in the industrial wastewater generated from mining operations, ore processing, metallurgy, and electroplating. Concentrations of Hg in industrial wastewater are not very high, usually below 1   mg/L (Rahman et al., 2017; Chojnacka et al., 2004).

As shown in Table 2.4, Ni often occurs in the industrial wastewater generated from mining operations, ore processing, petroleum refining, textiles production, metallurgy and electroplating, paper mills, and tannery. Concentrations of Ni in industrial wastewater range from ND to over 50   mg/L, and metallurgy and electroplating wastewater often contain high concentrations of Ni.

Table 2.1

a  -: no data in the reference.

Table 2.2

a  Categorizing according to ISO 22447.

As shown in Table 2.5, Pb often occurs in the industrial wastewater generated from mining operations, ore processing, petroleum refining, textiles production, metallurgy and electroplating, paper mills, and tannery. Concentrations of Pb in industrial wastewater range from ND to over 60   mg/L, and metallurgy and electroplating wastewater contains high concentrations of Pd.

As often occurs in the industrial wastewater generated from mining operations, ore processing, and textiles production. Concentrations of As in industrial wastewaters range from ND to 54   mg/L (Doušová et al., 2005; Sekomo et al., 2012; Hedrich and Johnson, 2014; Lim et al., 2010).

2.1.3. Migration and transformation of heavy metals in wastewater

When heavy metals are discharged into wastewater, the distribution of metals between the aqueous and the solid phase of wastewater occurs inevitably (Karvelas et al., 2003; Shafer et al., 1998). Karvelas et al. (2003) investigated distribution of metals between the aqueous and the solid phase of wastewater, revealing high exponential correlation between the metal partition coefficient (logKp) and the suspended solids concentration. In addition, different transformation reactions can occur in wastewater treatment processes. Methylation is a common transformation reaction of heavy metals by microorganisms. For example, Mao et al. (2016) investigated the fate of Hg in WWTPs and found influent MeHg mass was degraded, indicating that WWTPs are an important sink for sewage-borne Hg. In addition, chelation reaction is another common reaction in WWTPs. Heavy metals in wastewater may occur as attached to suspended solids via surface bound organic ligands or adsorbed on to a major insoluble matrix component (e.g., iron(III) oxide, aluminum hydroxide etc.), insoluble salts, inorganic complex solids, or as free or organically bound soluble forms. Their speciation may depend on the influent metal concentration, influent chemical oxygen demand, hardness, alkalinity, and pH of the wastewater (Santos and Judd, 2010). Wang et al. (2003) investigated the interactions of silver in wastewater constituents and found that chloride, sludge particulates, and dissolved organic matter (DOM) had an interaction with silver and the volume of adsorption to DOM substantially affected by the value of pH.

Due to the toxicity effect of heavy metals toward ecosystem, the removal of heavy metals in WWTPs is needed (Qureshi et al., 2016). Generally, heavy metals are resistant to biodegrade in WWTPs, and some physicochemical treatment methods rather than traditional biological treatment have been verified to be effective in removal of heavy metals from wastewater (Karvelas et al., 2003). For example, Fu and Wang (2011) evaluated the current methods that have been used to treat heavy metal wastewater including chemical precipitation, ion-exchange, adsorption, membrane filtration, coagulation-flocculation, flotation, and electrochemical methods. They found that adsorption and membrane filtration are the most frequently studied processes for the treatment of heavy metals in wastewater. In addition, biosorption is another promising method to eliminate heavy metals in wastewater (Veglio and Beolchini, 1997).

2.2. Persistent organic pollutants

POPs refer to one group of organic compounds characterized with high toxicity, environmental persistence, transporting over a long distance through various environmental medium, and accumulating in biological bodies easily (Tieyu et al., 2005). The widely known adverse effects of POPs toward human beings are carcinogenesis, tetratogenesis, and mutagenesis effects (Dietz et al., 2018; Raffetti et al., 2018). Generally, POPs include polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), perfluorooctanoic acids (PFOA) and perfluorooctane sulfonate (PFOS), short-chain chlorinated paraffins (SCCPs), and organic pesticides (OCPs) (Bao et al., 2012; Gallistl et al., 2017; Mrema et al., 2013). Furthermore, 28 substances or substance groups of POPs listed in the Stockholm convention deserve more attention (Fernandes et al., 2019; Magulova and Priceputu, 2016; Wei et al., 2007; Zapata et al., 2018). In this section, the source, occurrence and contamination level, and fate of POPs in wastewater, which will provide a clear understanding on ecological risk of POPs in wastewater to readers, are summarized as follows.

Table 2.3

a  Categorizing according to ISO 22447.

Table 2.4

a  Categorizing according to ISO 22447.

2.2.1. Sources of POPs in wastewater

The sources of different categories of POPs are generally different. The presence of pesticides in WWTPs is mainly due to nonagricultural usages, such as grass-management (golf courses, educational facilities, parks, and cemeteries), industrial vegetation control (industrial facilities, electric utilities, roadways, railroads, pipelines), public health (mosquito-abatement districts, rodent-control areas, and aquatic areas), and nonagricultural crops such as commercial forestry and horticulture and plant nurseries (Kock-Schulmeyer et al., 2013).

Table 2.5

a  Categorizing according to ISO 22447.

The wide use of PCBs as paints, inks, lubricants, and other additives, as well as insulation fluids in transformers and capacitors during 1950–1983 is the dominant source of PCBs into various environmental medium, especially in wastewater (Rodenburg et al., 2011). It has been indicated that old WWTPs remain a dominant source of PCBs to the environment although the production has been banned for 4   decades (Needham and Ghosh, 2019).

The sources of PAHs are complex and can be divided into natural and anthropogenic ones. Generally, PAHs are formed by the incomplete combustion of coal, oil, tar, gas, wood,