Papers

61,005 results
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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
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 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

[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

Establishment and application of standard analysis methods for microplastic samples: Urban sewage and sewage sludge as a source of microplastics in the environment

Researchers developed a standardized method for measuring microplastics in wastewater treatment plants and found that treated wastewater still releases an estimated 14.2 billion microplastic particles per day into the environment. While treatment plants remove most microplastics from the water, many end up concentrated in sewage sludge, which is often spread on farmland. The findings highlight that wastewater treatment is a major pathway for microplastics to reach rivers and agricultural soil.

2025 Environmental Research 6 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

Circulation of microplastics in a municipal wastewater treatment plant with multiphase activated sludge

Researchers tracked the circulation of microplastics through a municipal wastewater treatment plant, from raw wastewater through sludge processing. They found that most microplastics accumulated in sewage sludge at high concentrations, and that leachate from sludge treatment recycled microplastics back into the treatment process. The study highlights how wastewater treatment plants can inadvertently redistribute microplastics rather than fully removing them from the waste stream.

2024 Desalination and Water Treatment 10 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

Tracing and Quantifying Microplastics in Bristol’s Urban Water System

Researchers built a mass balance model of microplastic flows through Bristol's entire urban water system and found that households are the primary source feeding the system, while wastewater treatment plants intercept about 99.8% of microplastics before they reach rivers. However, the concentrated microplastics captured in sewage sludge re-enter the environment if sludge is spread on agricultural land as fertilizer. The model provides a template applicable to other cities for identifying where interventions would have the greatest impact on reducing environmental microplastic loads.

2026
Article Tier 2

Wastewater treatment plant as microplastics release source – Quantification and identification techniques

This review examines wastewater treatment plants as sources of microplastic release into the environment, along with current methods for separating and identifying these particles. While conventional treatment plants remove over 90% of incoming microplastics, they remain major point sources due to the enormous volumes of effluent they discharge. The review also highlights that over 80% of microplastics entering treatment plants become trapped in sewage sludge, which when used as agricultural fertilizer represents a potential pathway for soil contamination.

2019 Journal of Environmental Management 216 citations
Article Tier 2

Microplastics in sewage sludge: Distribution, toxicity, identification methods, and engineered technologies

This review examines how microplastics accumulate in sewage sludge from wastewater treatment plants, which then becomes a major pathway for spreading these particles into the environment. Researchers found that sludge can contain extremely high concentrations of microplastics, ranging from thousands to hundreds of thousands of particles per kilogram. The study evaluates current detection methods and emerging technologies for removing microplastics from sludge before it is applied to agricultural land or disposed of.

2022 Chemosphere 106 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

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

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

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

Identification and quantification of microplastics in wastewater treatment plant effluent: Investigation of the fate and biological effects

This study identified and quantified microplastics in wastewater treatment plant effluents and sludge, finding particles in all samples with fibers being the dominant type. The research contributes to understanding how much microplastic reaches surface waters via wastewater discharge and how much is captured in sludge that is subsequently applied to agricultural land.

2018 Griffith Research Online (Griffith University, Queensland, Australia) 4 citations
Article Tier 2

Microplastic Pollution via Wastewater Effluent and Sewage Sludge: Special Focus on Microplastic Fibres in Compost

Researchers measured microplastic concentrations in treated wastewater effluent and sewage sludge from treatment plants, finding that despite high MP removal rates, large daily discharge volumes still release substantial quantities of MPs into the environment. Sludge applied to agricultural land was identified as a major secondary MP pollution pathway.

2025 Water Air & Soil Pollution 2 citations
Article Tier 2

Sources, fate, effects, and analysis of microplastic in wastewater treatment plants: A review

This review examines how wastewater treatment plants handle microplastics, finding that while they can remove over 90% of particles, the sheer volume of water processed means billions of microplastics still escape into waterways daily. The remaining microplastics also concentrate in sewage sludge, which is often spread on agricultural land. Wastewater treatment plants are both a filter for and a redistribution point of microplastic pollution.

2023 Environmental Engineering Research 31 citations
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

Combined application of analytical techniques for microplastic determination to achieve comprehensive results for sewage sludge samples

Researchers combined multiple analytical techniques for comprehensive microplastic determination in sewage sludge samples, addressing the challenge that more than 90% of microplastics entering wastewater treatment plants are retained in sludge and require robust multi-method characterization.

2024 Zenodo (CERN European Organization for Nuclear Research)
Article Tier 2

Wastewater Treatment Plants as a Key Source of Secondary Microplastic in the Urban Environment

Researchers investigated the occurrence, distribution, and characteristics of microplastics in sewage sludge from two wastewater treatment plants in Uttarakhand, India, finding that WWTPs act as a key source of secondary microplastic pollution in the urban environment as sludge concentrates particles removed during treatment.

2024 1 citations
Article Tier 2

Occurrence of microplastics in influent, sewage sludge and effluent of municipal wastewater treatment plant, A case study center of Iran, Qom city

A study of a municipal wastewater treatment plant found microplastics in the influent, sewage sludge, and effluent, confirming that treatment processes do not fully remove plastic particles before water is discharged. This matters because treated wastewater and sludge applied to agricultural land are significant pathways through which microplastics enter rivers, soils, and ultimately the food supply.

2023 2 citations
Article Tier 2

Understanding microplastic presence in different wastewater treatment processes: Removal efficiency and source identification

Researchers tracked microplastic removal across different treatment stages at two wastewater treatment plants and found overall removal rates of 90% and 97%. They discovered that population density in the served area was a bigger driver of influent microplastic levels than sewage volume, and that activated sludge served as the primary trap for captured particles. The study identified laundry washing and daily consumer products as the main sources of microplastics entering the treatment plants.

2024 The Science of The Total Environment 22 citations