Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation Strategies
The widespread implementation of anaerobic digestion (AD) systems for organic waste treatment is increasingly challenged by emerging contaminants, including microplastics (MPs), antibiotics, and heavy metals (HMs), which exhibit environmental persistence and pose risks to ecological and human health...
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MDPI AG
2025-06-01
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| Online Access: | https://www.mdpi.com/2313-4321/10/3/116 |
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| author | Hongbo Liu Xiang Yuan Yuxuan Yao Lijin Yao Junbo Zhang Claudia Maurer |
| author_facet | Hongbo Liu Xiang Yuan Yuxuan Yao Lijin Yao Junbo Zhang Claudia Maurer |
| author_sort | Hongbo Liu |
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| description | The widespread implementation of anaerobic digestion (AD) systems for organic waste treatment is increasingly challenged by emerging contaminants, including microplastics (MPs), antibiotics, and heavy metals (HMs), which exhibit environmental persistence and pose risks to ecological and human health. This review critically examines the sources, transformation pathways, and advanced mitigation strategies for these contaminants within AD systems. MPs, primarily derived from fragmented plastics and personal care products, accumulate in digestates and act as vectors for adsorbing toxic additives and pathogens. Antibiotics, introduced via livestock manure and wastewater, exert selective pressures that propagate antibiotic resistance genes (ARGs) while disrupting methanogenic consortia. HMs, originating from industrial and agricultural activities, impair microbial activity through bioaccumulation and enzymatic interference, with their bioavailability modulated by speciation shifts during digestion. To combat these challenges, promising mitigation approaches include the following: (1) bioaugmentation with specialized microbial consortia to enhance contaminant degradation and stabilize HMs; (2) thermal hydrolysis pretreatment to break down MPs and antibiotic residues; (3) chemical passivation using biochar or sulfides to immobilize HMs. Co-digestion practices inadvertently concentrate these contaminants, with MPs and HMs predominantly partitioning into solid phases, while antibiotics persist in both liquid and solid fractions. These findings highlight the urgency of optimizing mitigation strategies to minimize contaminant mobility and toxicity. However, critical knowledge gaps persist regarding the long-term impacts of biodegradable MPs, antibiotic transformation byproducts, and standardized regulatory thresholds for contaminant residues in digestate. This synthesis underscores the necessity for integrated engineering solutions and policy frameworks to ensure the safe resource recovery from AD systems, balancing energy production with environmental sustainability. |
| format | Article |
| id | doaj-art-327f98c040f34e948e4cdacd2bd4ffb4 |
| institution | Matheson Library |
| issn | 2313-4321 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
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| series | Recycling |
| spelling | doaj-art-327f98c040f34e948e4cdacd2bd4ffb42025-06-25T14:22:37ZengMDPI AGRecycling2313-43212025-06-0110311610.3390/recycling10030116Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation StrategiesHongbo Liu0Xiang Yuan1Yuxuan Yao2Lijin Yao3Junbo Zhang4Claudia Maurer5School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, ChinaSchool of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, ChinaSchool of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, ChinaSchool of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, ChinaSchool of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, ChinaWater Quality and Waste Management, Institute of Sanitary Engineering, University of Stuttgart, Bandtäle 2, 70569 Stuttgart, GermanyThe widespread implementation of anaerobic digestion (AD) systems for organic waste treatment is increasingly challenged by emerging contaminants, including microplastics (MPs), antibiotics, and heavy metals (HMs), which exhibit environmental persistence and pose risks to ecological and human health. This review critically examines the sources, transformation pathways, and advanced mitigation strategies for these contaminants within AD systems. MPs, primarily derived from fragmented plastics and personal care products, accumulate in digestates and act as vectors for adsorbing toxic additives and pathogens. Antibiotics, introduced via livestock manure and wastewater, exert selective pressures that propagate antibiotic resistance genes (ARGs) while disrupting methanogenic consortia. HMs, originating from industrial and agricultural activities, impair microbial activity through bioaccumulation and enzymatic interference, with their bioavailability modulated by speciation shifts during digestion. To combat these challenges, promising mitigation approaches include the following: (1) bioaugmentation with specialized microbial consortia to enhance contaminant degradation and stabilize HMs; (2) thermal hydrolysis pretreatment to break down MPs and antibiotic residues; (3) chemical passivation using biochar or sulfides to immobilize HMs. Co-digestion practices inadvertently concentrate these contaminants, with MPs and HMs predominantly partitioning into solid phases, while antibiotics persist in both liquid and solid fractions. These findings highlight the urgency of optimizing mitigation strategies to minimize contaminant mobility and toxicity. However, critical knowledge gaps persist regarding the long-term impacts of biodegradable MPs, antibiotic transformation byproducts, and standardized regulatory thresholds for contaminant residues in digestate. This synthesis underscores the necessity for integrated engineering solutions and policy frameworks to ensure the safe resource recovery from AD systems, balancing energy production with environmental sustainability.https://www.mdpi.com/2313-4321/10/3/116anaerobic digestionorganic wasteemerging contaminantsbiotreatmentresource utilization |
| spellingShingle | Hongbo Liu Xiang Yuan Yuxuan Yao Lijin Yao Junbo Zhang Claudia Maurer Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation Strategies Recycling anaerobic digestion organic waste emerging contaminants biotreatment resource utilization |
| title | Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation Strategies |
| title_full | Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation Strategies |
| title_fullStr | Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation Strategies |
| title_full_unstemmed | Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation Strategies |
| title_short | Microplastics, Antibiotics, and Heavy Metals in Anaerobic Digestion Systems: A Critical Review of Sources, Impacts, and Mitigation Strategies |
| title_sort | microplastics antibiotics and heavy metals in anaerobic digestion systems a critical review of sources impacts and mitigation strategies |
| topic | anaerobic digestion organic waste emerging contaminants biotreatment resource utilization |
| url | https://www.mdpi.com/2313-4321/10/3/116 |
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