Papers

61,005 results
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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

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

The course of microplastics before and after UK WWTPs and their release into the environment.

This study tracked microplastics through UK wastewater treatment plants from influent to effluent and biosolids, finding that while treatment removes the majority of microplastics from the water stream, significant quantities are concentrated in biosolids spread on agricultural land.

2024
Article Tier 2

An audit of microplastic abundance throughout three Australian wastewater treatment plants

Microplastic abundance was audited throughout three Australian wastewater treatment plants, tracking particles from influent through all treatment stages and into both effluent and biosolids. While treatment removed most microplastics from effluent, the majority were captured in biosolids — which are often land-applied — highlighting biosolids as the primary pathway for microplastics leaving wastewater treatment systems.

2020 Chemosphere 284 citations
Article Tier 2

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

This review synthesizes global data on microplastic concentrations, characteristics, and distribution in sewage sludge and biosolids, drawing on studies showing wastewater treatment works remove 57-99% of incoming microplastics, concentrating them in sludge byproducts. The review highlights the significance of this concentration pathway and what happens to these microplastics when sludge is applied to land or otherwise managed.

2025 Figshare
Article Tier 2

Sewage sludge as a source of microplastics in the environment: A review of occurrence and fate during sludge treatment

This review assessed how wastewater treatment plants concentrate microplastics from influent into sludge, estimating that sewage sludge applied to agricultural land represents a major secondary pathway for MPs entering terrestrial ecosystems, with estimated releases of millions to billions of particles per hectare.

2021 Journal of Environmental Management 139 citations
Meta Analysis Tier 1

Occurrence, spatiotemporal trends, fate, and treatment technologies for microplastics and organic contaminants in biosolids: A review

This meta-analysis examines how microplastics and organic pollutants end up in biosolids (treated sewage) and what happens when those biosolids are applied to farmland. The data show that microplastics are among the most common contaminants found in biosolids, raising concerns about long-term buildup in the soils where our food is grown.

2024 Journal of Hazardous Materials 25 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
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
Review Tier 2

Microplastics in Sewage Sludge: A review

This review examines the presence and fate of microplastics in sewage sludge from municipal wastewater treatment plants, a topic that has received less attention than microplastics in the water treatment line. The study highlights that agricultural application of sewage sludge is a primary source of microplastic contamination in soils, and provides a comprehensive overview of detection methods, concentrations, and the environmental implications of sludge-borne microplastics.

2023 Environmental Science and Pollution Research 64 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

Risk of re-release of microplastics from sewage fertilisers into the environment

This paper reviews the risk that microplastics in sewage sludge (biosolids used as agricultural fertilizer) will be re-released into soils and water when the sludge is land-applied. Microplastics from cosmetics and clothing fibers concentrate in sludge during wastewater treatment and persist because they resist biodegradation. Applying microplastic-contaminated biosolids to farmland is one of the major pathways through which microplastics enter agricultural soils.

2023 1 citations
Article Tier 2

Identification of microplastics extracted from field soils amended with municipal biosolids

Researchers developed a method for extracting and identifying microplastics from agricultural soils that had been treated with municipal biosolids, a common fertilizer derived from wastewater treatment. They found a variety of plastic polymer types in the soil, confirming that biosolid application is a pathway for microplastic contamination of farmland. The study provides a reliable technique for tracking how microplastics cycle through agricultural environments.

2023 The Science of The Total Environment 20 citations
Article Tier 2

Microplastics in Sewage Sludge: Worldwide Presence in Biosolids, Environmental Impact, Identification Methods and Possible Routes of Degradation, Including the Hydrothermal Carbonization Process

This review examines the worldwide presence of microplastics in sewage sludge and biosolids, along with their environmental impact when applied to agricultural land. Researchers found that wastewater treatment plants capture roughly 90% of incoming microplastics in sludge, but land application of biosolids then redistributes these particles into soils, highlighting the need for better degradation methods.

2024 Energies 15 citations
Article Tier 2

Sewage Sludge in Farmlands: A Gateway to Soil Microplastic Pollution?

Researchers analysed microplastic contamination in dewatered anaerobically digested sewage sludge and adjacent agricultural fields in the UK with varied sludge application histories, using fluorescence microscopy and FTIR/Raman spectroscopy to detect predominantly polyethylene, polyester, polypropylene, polystyrene, PVC, and polyamide particles.

2024
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
Systematic Review Tier 1

The overlooked pathway: A systematic review on sewage sludge treatment as a critical secondary source of terrestrial micro(nano)plastics

This systematic review examines sewage sludge as an overlooked pathway for microplastics to contaminate land, with concentrations reaching over 1,300 particles per kilogram. When this sludge is applied to farmland as fertilizer, aged and chemically modified microplastics enter agricultural soil, where they may be more toxic than fresh particles and can potentially be taken up by crops.

2025 The Science of The Total Environment
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

Behavior and flow of microplastics during sludge treatment in Japan

Sampling of two Osaka wastewater treatment plants found microplastics at every stage of the sludge treatment process, with 13 polymer types identified; concentration increased through dewatering, but the total MP load in final biosolids was lower than in raw sludge.

2024 The Science of The Total Environment 8 citations
Article Tier 2

Sewage sludge application as a vehicle for microplastics in eastern Spanish agricultural soils

Scientists measured microplastics in sewage sludge from Spanish wastewater treatment plants and in agricultural soils receiving sludge applications, finding that sludge application transferred hundreds to thousands of microplastic particles per kilogram into agricultural soil.

2020 Environmental Pollution 608 citations
Article Tier 2

Approaching the environmental problem of microplastics: Importance of WWTP treatments

This review examines the role of wastewater treatment plants as sources and sinks of microplastics, noting that while treatment removes significant quantities, remaining particles concentrate in sewage sludge which is then applied to agricultural land as fertilizer. The authors survey available technologies for improving microplastic removal and call for better policy to address this gap.

2020 The Science of The Total Environment 262 citations
Article Tier 2

Microplastics in sewage sludge: Captured but released?

This book chapter reviews how wastewater treatment plants capture microplastics from sewage but then release them back into the environment through the application of sewage sludge to agricultural land. Treating sewage sludge as a microplastic disposal route transfers the pollution problem from water to soil.

2019 IWA Publishing eBooks 9 citations
Article Tier 2

Fate of microplastics in a centralized biogas plant treating mainly sewage sludge

Researchers tracked the fate of microplastics through a centralized biogas plant treating sewage sludge, examining how anaerobic digestion and subsequent dewatering partition microplastics between solid and liquid digestate fractions. The study informs efforts to develop safer digestate-based recycled fertilizers that minimize microplastic introduction to agricultural soils, where 20-55% of microplastics entering wastewater treatment plants are estimated to end up in sludge.

2025 Journal of Environmental Management
Article Tier 2

Microplastics in an agricultural soil following repeated application of three types of sewage sludge: A field study

Researchers investigated microplastics in agricultural soil after repeated sewage sludge application, finding that sludge-amended soils contained significantly more small microplastic particles than unamended soils, with particle accumulation varying by sludge type.

2021 Environmental Pollution 171 citations