Papers

20 results
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Article Tier 2

Investigation of microplastics in sludge from five wastewater treatment plants in Nanjing, China

Microplastics were characterized in sludge from five wastewater treatment plants in Nanjing, China, with concentrations ranging widely across facilities and fibers as the dominant shape, highlighting sludge as a major reservoir and potential environmental release point for microplastic pollution.

2021 Journal of Environmental Management 67 citations
Article Tier 2

Microplastics in sewage sludge from the wastewater treatment plants in China

Researchers analyzed microplastics in sewage sludge from wastewater treatment plants across China, finding high concentrations of microplastics — predominantly fibers and fragments — raising concerns about their spread when sludge is applied to agricultural land.

2018 Water Research 1001 citations
Article Tier 2

Distribution of microplastics in the sludge of wastewater treatment plants in chengdu, China

Microplastics were found in sludge from all processing units at wastewater treatment plants in Chengdu, China, with the highest concentrations in thickened and dewatered sludge, indicating that sludge handling and land application represent a major pathway for microplastics to re-enter terrestrial environments.

2021 Chemosphere 72 citations
Article Tier 2

Microplastics in wastewater treatment plants and their contributions to surface water and farmland pollution in China

Researchers examined microplastic abundance in sewage and sludge at Shenzhen wastewater treatment plants, estimating that annual microplastic loading from WWTPs to surface water and farmland soil across China is substantial. WWTPs concentrate microplastics in sludge, which then becomes a major pathway for plastic contamination of agricultural land when applied as fertilizer.

2023 Chemosphere 17 citations
Article Tier 2

Occurrence and Characteristics of Microplastics in a Wastewater Treatment Plant

Researchers sampled the inflow, outflow, and sludge of a Chinese wastewater treatment plant, finding up to 44 microplastic particles per liter in incoming water — mostly polyester fibers. The plant removed about 96% of microplastics, but the remaining fraction was still discharged into receiving waterways.

2021 Bulletin of Environmental Contamination and Toxicology 24 citations
Article Tier 2

The Pollution Characteristics and Fate of Microplastics in Typical Wastewater Treatment Systems in Northern China

Researchers analyzed microplastic contamination at two wastewater treatment plants in Zhengzhou, China, finding overall removal efficiencies of about 93 and 96 percent respectively. Fibers and fragments were the most common microplastic shapes detected, with much of the removed material ending up concentrated in sewage sludge. The study raises concerns that while treatment processes are effective at reducing waterborne microplastics, the contaminated sludge may redistribute the pollution when applied to agricultural land.

2024 Separations 10 citations
Article Tier 2

Characteristics and removal efficiency of microplastics in sewage treatment plant of Xi'an City, northwest China

Researchers systematically tracked microplastic transport, characteristics, and removal through both the sewage and sludge treatment streams of a Chinese wastewater treatment plant. The study found that while most microplastics were removed from effluent, substantial quantities accumulated in sludge.

2021 The Science of The Total Environment 91 citations
Article Tier 2

Microplastics in real wastewater treatment schemes: comparative assessment and relevant inhibition effects on anaerobic processes

Researchers investigated microplastic occurrence and removal in an Italian wastewater treatment plant, finding 3.6 MPs/L in influent dominated by polyester fibers, with conventional activated sludge achieving 86% removal, and demonstrating that concentrated sludge-associated microplastics can inhibit downstream anaerobic digestion.

2021 Zenodo (CERN European Organization for Nuclear Research) 5 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

Effects of typical sludge treatment on microplastics in China—Characteristics, abundance and micro-morphological evidence

Different sludge treatment technologies used in China including anaerobic digestion, thermal drying, and composting were compared for their effects on microplastic characteristics and abundance, with results showing that treatment method significantly altered microplastic morphology but did not eliminate contamination. The study informs decisions about which treatment approaches best reduce microplastic transfer to soils when sludge is land-applied.

2022 The Science of The Total Environment 45 citations
Article Tier 2

Microplastics in real wastewater treatment schemes: Comparative assessment and relevant inhibition effects on anaerobic processes

Researchers studied the occurrence and removal of microplastics through different stages of a wastewater treatment plant in Central Italy. They found that while treatment processes removed a substantial portion of incoming microplastics, significant numbers still passed into the effluent, and microplastics also inhibited anaerobic digestion processes used for sludge treatment. The study highlights that wastewater treatment plants are both important barriers against and inadvertent sources of microplastic pollution in receiving waters.

2020 Chemosphere 129 citations
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

Wastewater treatment alters microbial colonization of microplastics

Analysis of microplastics and their biofilms across raw sewage, effluent, and sludge at two wastewater treatment plants found that >99% of influent MPs were retained in sludge, and that wastewater treatment substantially altered biofilm microbial composition, enriching bioflocculation-associated taxa.

2021 PLoS ONE 133 citations
Article Tier 2

Distribution and removal mechanism of microplastics in urban wastewater plants systems via different processes

Researchers compared the microplastic removal efficiency of three wastewater treatment technologies and found that the anaerobic-anoxic-oxic process achieved the highest removal rate at 83.9%. Most microplastics were transferred to sludge during primary and secondary treatment stages, with dehydrated sludge containing significant concentrations. The study highlights that while wastewater treatment plants effectively intercept most microplastics, they also redistribute contamination to sludge, which may become a secondary pollution source.

2023 Environmental Pollution 65 citations
Review Tier 2

A global review of microplastics in wastewater treatment plants: Understanding their occurrence, fate and impact

A global review of 121 wastewater treatment plants found that microplastics are consistently present in both influent and effluent, with WWTPs acting as major conduits delivering plastics into aquatic and terrestrial ecosystems. While removal efficiencies varied widely, the sludge produced by these plants represents a concentrated secondary pathway for microplastic release to land.

2022 Environmental Research 76 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

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

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

Assessment and accumulation of microplastics in sewage sludge at wastewater treatment plants located in Cádiz, Spain

Researchers sampled microplastics from primary, secondary, and digested sludge at seven wastewater treatment plants in southern Spain, finding sludge acts as a significant sink for microplastics. Fragments and fibers under 2 mm were dominant, and concentrations varied significantly between urban and industrial plant types.

2022 Environmental Pollution 57 citations
Article Tier 2

Study of occurrence, abundance, and characterization of microplastics in wastewater treatment plant in New Delhi, India

Researchers quantified microplastic prevalence in influent, treated effluent, and sludge from a wastewater treatment plant in New Delhi, finding that MPs are present throughout the treatment process and that the plant incompletely removes them, discharging MPs into receiving waters.

2025 Environmental Monitoring and Assessment