Papers

61,005 results
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Article Tier 2

Configuration-driven microplastic fate in full-scale sewage sludge treatment and opportunities for system-level mitigation

Researchers examined how different treatment configurations in wastewater plants shape the types and concentrations of microplastics that end up in sewage sludge — the solid byproduct that is frequently spread on agricultural land as fertilizer. Microplastic concentrations in final sludge ranged from 617 to 936 particles per gram of dry solids, with fine fragments under 100 micrometers dominating, and the specific sequence of thickening, digestion, and dewatering steps significantly influenced which polymer types were retained. Since sludge application is a major route for microplastics to enter farmland, optimizing treatment processes could meaningfully reduce environmental contamination.

2026 Journal of Environmental Management
Article Tier 2

Fate of microplastics in sewage sludge and in agricultural soils

Researchers reviewed how microplastics accumulate in sewage sludge at wastewater treatment plants and then spread into agricultural soils when that sludge is applied as fertilizer, finding that sludge treatment processes can alter microplastic size and shape but do not eliminate them. The review calls for standardized methods to study how different sludge treatments affect microplastic properties and their downstream risks to soil health.

2023 TrAC Trends in Analytical Chemistry 52 citations
Article Tier 2

The occurrence and fate of microplastics in a mesophilic anaerobic digester receiving sewage sludge, grease, and fatty slurries

Researchers analyzed microplastic loads entering and leaving a mesophilic anaerobic digester at a wastewater treatment plant serving nearly 800,000 people. They found that the digester received approximately 7,326 kg of microplastics per year, with digested sludge containing about 30% less, though this reduction was within the variability of the measurements. The study provides important data on the fate of microplastics during sewage sludge treatment processes.

2021 The Science of The Total Environment 52 citations
Article Tier 2

Systematic study of microplastics on methane production in anaerobic digestion: Performance and microbial response

Microplastics are increasingly found in wastewater treatment systems, and this study systematically examined how different types, concentrations, and sizes of microplastics affect the anaerobic digestion process used to break down sewage sludge and generate biogas. Polyethylene microplastics were found to inhibit methane production, with finer particles and higher concentrations causing greater disruption to the microbial communities driving digestion. The findings matter because microplastics in sewage sludge can impair the treatment process and also end up spread on agricultural land when sludge is used as fertilizer.

2025 Journal of environmental chemical engineering 1 citations
Article Tier 2

A method for the characterisation of microplastics in sludge

Researchers developed a method for detecting and characterizing microplastics in sewage sludge, which concentrates the majority of microplastics removed during wastewater treatment. This method is important because sludge is widely spread on agricultural land, making it a key pathway for microplastics entering soils.

2019 MethodsX 23 citations
Article Tier 2

Distribution characteristics of microplastics in typical organic solid wastes and their biologically treated products

Researchers extracted and characterized microplastics from food waste, livestock manure, sludge, and their composted or digested products, finding MPs in all organic waste types with concentrations varying by matrix. The study highlights organic waste management pathways as an understudied route for microplastic transfer to agricultural soils.

2022 The Science of The Total Environment 40 citations
Article Tier 2

Tracing the fate of microplastic in wastewater treatment plant: A multi-stage analysis of treatment units and sludge

Researchers tracked microplastics through every stage of a wastewater treatment plant and found that while treatment removes many particles from the water, most end up concentrated in the leftover sludge. Fibers and fragments were the most common shapes, made primarily of polyester and polyethylene. Since treated sludge is often spread on farmland, this creates a pathway for microplastics to enter soil and potentially the food chain.

2023 Environmental Pollution 60 citations
Article Tier 2

Microplastics in an anaerobic digester treating sewage sludge: Occurrence and factors affecting their identification with Raman spectroscopy

Researchers tracked microplastic levels through an anaerobic digester used to treat sewage sludge and its subsequent separation into solid and liquid fractions. They found that the digestion process stabilized the fluctuating microplastic concentrations found in raw sludge, and that the vast majority of particles ended up in the solid fraction. Since this solid material is often applied to farmland, the findings raise concerns about sewage-derived microplastics entering agricultural soils.

2025 Journal of Hazardous Materials 11 citations
Article Tier 2

Transport and accumulation of microplastics through wastewater treatment sludge processes

Researchers tracked microplastic concentrations through each stage of wastewater treatment sludge processing — including thickening, anaerobic digestion, and dewatering — finding that each step altered MP abundance and size distribution, with digestion fragmenting some particles into smaller pieces rather than eliminating them.

2021 Chemosphere 169 citations
Article Tier 2

Microplastics removal from a primary settler tank in a wastewater treatment plant and estimations of contamination onto European agricultural land via sewage sludge recycling

Researchers found that primary settling in wastewater treatment removes significant microplastics from sewage, but these particles concentrate in sludge that is often recycled onto agricultural land, creating a pathway back into the environment.

2022 Environmental Pollution 99 citations
Article Tier 2

Investigation and analysis of microplastics in sewage sludge and biosolids: A case study from one wastewater treatment works in the UK

Researchers investigated microplastic contamination in sewage sludge and biosolids at a UK wastewater treatment plant and found significant quantities of microplastics persisting through the treatment process. Since millions of tonnes of biosolids are applied to farmland annually in the UK, this represents a major pathway for microplastic pollution entering agricultural soils. The study highlights the need for better monitoring and treatment methods to reduce microplastic transfer from wastewater to the terrestrial environment.

2022 The Science of The Total Environment 175 citations
Article Tier 2

Occurrence of macroplastics and microplastics in biogenic waste digestate: Effects of depackaging at source and dewatering process

Researchers investigated plastic debris in digestate from anaerobic digestion of biogenic waste, finding that both preprocessing and dewatering steps significantly influence the quantity of macroplastics and microplastics in the resulting material used as a soil conditioner.

2022 Waste Management 27 citations
Article Tier 2

Fate of microplastics in wastewater treatment plants and their environmental dispersion with effluent and sludge

Researchers tracked microplastics through a wastewater treatment plant and found 12 different polymer types in effluents and sludge, with smaller particles (25–104 μm) most abundant and fibres displaying lower sizes than fragments. The study demonstrates that WWTPs do not fully remove microplastics and that processed sludge marketed as soil amendment carries plastic contamination.

2019 Environmental Pollution 589 citations
Article Tier 2

Investigation and analysis of microplastics in sewage sludge and biosolids: A case study from one wastewater treatment works in the UK (article)

This UK case study tracked microplastics through an entire sewage sludge treatment stream at one wastewater works, from raw influent through to biosolids applied to agricultural land. Microplastics were present at every stage and concentrated in biosolids, suggesting land application of biosolids is a significant pathway for introducing microplastics into agricultural soils.

2025 Figshare
Article Tier 2

Digestate from Biowaste and Sewage Sludge as Carriers of Microplastic into the Environment: Case Study of a Thermophilic Biogas Plant in Ostrobothnia, Finland

This Finnish study found microplastics in every waste fraction sampled from a thermophilic biogas plant — including reject water and digestate from both biowaste and sewage sludge digestion. Because digestate is commonly spread on agricultural land as a fertilizer, biogas plants represent an underappreciated pathway for microplastics to enter soil ecosystems at scale. The findings highlight a critical gap in microplastic regulation: current wastewater treatment frameworks do not adequately address plastic contamination in biogas waste streams.

2023 Water Air & Soil Pollution 11 citations
Article Tier 2

[Microplastics in wastewater treatment: current status and future trends].

This review summarizes current research on microplastic occurrence, removal, and fate in wastewater treatment plants, noting that while plants capture most microplastics in activated sludge, significant numbers still escape into effluent. The sludge itself then becomes a major pathway for microplastics to enter agricultural soils when applied as fertilizer. Future treatment improvements and sludge management policies are needed to reduce these release pathways.

2022 PubMed 4 citations
Article Tier 2

Occurrence, effect, and fate of residual microplastics in anaerobic digestion of waste activated sludge: A state-of-the-art review

This review assessed the occurrence, behavior, and fate of microplastics in anaerobic digestion of waste activated sludge, finding that MPs survive digestion largely intact but can affect methane production and microbial community composition, and that digestate land application remains a major pathway for releasing sludge-retained MPs to soil.

2021 Bioresource Technology 100 citations
Article Tier 2

Seasonal Variation, Distribution and Characteristics of Microplastic in Sewage Sludge

Researchers investigated seasonal variation in microplastic concentration, distribution, and characteristics within sewage sludge at wastewater treatment plants, examining how precipitation patterns and sludge treatment processes influence microplastic retention and the pathways by which sludge-borne microplastics enter agricultural soils upon land application.

2022 Zenodo (CERN European Organization for Nuclear Research)
Article Tier 2

Impact of micro-nanoplastics on biochemical phases of anaerobic digestion in sewage sludge treatment: mechanistic insights and future prospects

Micro- and nanoplastics were found to disrupt the biochemical phases of anaerobic digestion, affecting the efficiency of the biological process used to treat organic waste. Understanding these impacts is important because anaerobic digestion is a common wastewater and sludge treatment method that may both receive and process microplastic-contaminated materials.

2025 International Journal of Theoretical and Applied Research 1 citations
Article Tier 2

Variation in microplastic concentration, characteristics and distribution in sewage sludge & biosolids around the world

Researchers systematically reviewed 65 studies on microplastics in sewage sludge and biosolids from wastewater treatment plants around the world. They found that while treatment processes remove 57% to 99% of microplastics from wastewater, the removed particles concentrate in sludge that is often applied to agricultural land. The review highlights that land application of biosolids may be a significant, underappreciated pathway for microplastic pollution in soils.

2023 The Science of The Total Environment 95 citations
Article Tier 2

Aging and mitigation of microplastics during sewage sludge treatments: An overview

Researchers reviewed how microplastics change and break down during sewage sludge treatment processes such as composting, anaerobic digestion, and thermal treatment. They found that while some treatment methods can reduce microplastic levels, others may actually fragment particles into smaller, potentially more harmful sizes. The study highlights the importance of optimizing sludge treatment to prevent microplastics from reaching agricultural soils when sludge is applied as fertilizer.

2024 The Science of The Total Environment 24 citations
Article Tier 2

The fate of microplastic in sludge management systems

This review assessed the fate of microplastics in sewage sludge management systems, finding that standard stabilization processes including anaerobic digestion and composting do not substantially reduce MP concentrations. Land application of MP-rich sludge was identified as a major pathway for plastic particles entering agricultural soils, with the review calling for alternative sludge disposal strategies aligned with circular economy principles.

2022 The Science of The Total Environment 62 citations
Article Tier 2

Transport and fate of microplastic particles in wastewater treatment plants

Researchers tracked microplastic particles through multiple stages of a wastewater treatment plant, finding that particles were concentrated in sludge but that a fraction passed through each treatment stage and remained in the final effluent.

2016 Water Research 1704 citations
Article Tier 2

Microplastics in Sewage Sludge: A Known but Underrated Pathway in Wastewater Treatment Plants

This review finds that wastewater treatment plants effectively transfer microplastics from effluent into sewage sludge, creating a significant but underrated pathway for MP contamination when sludge is applied to agricultural soils.

2021 Sustainability 46 citations