Papers

61,005 results
|
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

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

Fate of Microplastic Pollution Along the Water and Sludge Lines in Municipal Wastewater Treatment Plants

Researchers evaluated microplastic abundance and distribution across three municipal wastewater treatment plants using different treatment technologies. The study found that all three plants achieved greater than 97% microplastic removal along the water treatment line, with microplastics concentrating in the sludge fraction, underscoring the important role of sludge treatment in sequestering microplastics from wastewater.

2025 Microplastics 6 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

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

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
Article Tier 2

Improved methodology to determine the fate and transport of microplastics in a secondary wastewater treatment plant

An improved methodology was applied to track the fate and transport of microplastics through a wastewater treatment plant, measuring particle size, shape, and polymer type at multiple treatment stages. The study found that while most microplastics are removed during primary and secondary treatment, smaller particles persist into the effluent and sludge.

2020 Water Research 277 citations
Article Tier 2

Microplastics removal through water treatment plants: Its feasibility, efficiency, future prospects and enhancement by proper waste management

Researchers reviewed over 80 studies on water treatment plant performance and found microplastic removal ranges widely — from 16% in basic primary treatment up to near 100% with advanced membrane systems — but a major flaw is that removed microplastics concentrate in sludge, which can re-enter the environment. The review recommends optimizing coagulants and sludge treatment to prevent microplastics from simply being relocated rather than eliminated.

2021 Environmental Challenges 181 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

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

Fate of microplastics during conventional and hydrothermal treatments of sewage sludge: a short review

This review examines the fate of microplastics during conventional and hydrothermal treatment of sewage sludge, noting that approximately 90% of microplastics entering wastewater treatment plants are retained in sludge. Researchers found that while conventional disposal routes concentrate microplastics in sludge destined for land application, hydrothermal treatments offer potential pathways to degrade or transform microplastics, though the efficiency and byproducts of these processes require further investigation.

2025 IOP Conference Series Earth and Environmental Science
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

Tracking and risk assessment of microplastics in a wastewater treatment plant

This study tracked and assessed risks from microplastics through all stages of a wastewater treatment plant, quantifying plastic loads in influent, effluent, and sludge, and identifying which treatment steps provide the greatest removal.

2024 Water and Environment Journal 5 citations
Article Tier 2

Particle balance and return loops for microplastics in a tertiary-level wastewater treatment plant

Researchers tracked microplastics through 12 process steps in a tertiary-level wastewater treatment plant in Finland, finding that sludge treatment return loops represent a significant and underappreciated pathway for microplastics re-entering the water stream. The particle balance approach revealed that sludge processing stages deserve as much research attention as primary and secondary water treatment.

2021 Water Science & Technology 49 citations
Article Tier 2

Mesophilic anaerobic digestion of mixed sludge in CSTR and AnMBR systems: A perspective on microplastics fate

Researchers compared how two types of anaerobic digesters used in wastewater treatment affect the fate of microplastics in sewage sludge. They found that while digestion reduced some types of microplastics, it also fragmented larger particles into smaller ones, and a membrane bioreactor retained more microplastics than a conventional stirred tank. The study suggests that current wastewater treatment processes may not fully eliminate microplastics and could even create smaller, harder-to-remove particles.

2025 Journal of Environmental Management 11 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
Article Tier 2

Microplastic Degradation through Thermal Hydrolysis in Sewage Sludge and Its Impact on the Anaerobic Process

Researchers found that thermal hydrolysis pretreatment of sewage sludge reduced microplastic concentrations from 206 particles/g to lower levels, with approximately 54% of microplastics initially in solid phase, and examined the implications for sludge management and microplastic fate.

2025 ACS ES&T Water
Article Tier 2

Fate and behavior of microplastics in wastewater, accumulation in organisms and effects

This review examines the fate and behavior of microplastics through wastewater treatment plant (WWTP) unit processes, their accumulation in sludge, and their effects on aquatic organisms receiving treated effluent. The authors note that while conventional WWTPs remove 64-99% of microplastics, the remaining daily discharge still represents a substantial pathway for microplastic entry into aquatic environments.

2024 IWA Publishing eBooks
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

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

A review of the removal of microplastics in global wastewater treatment plants: Characteristics and mechanisms

This review analyzed data from 38 wastewater treatment plants across 11 countries to understand how effectively they remove microplastics. While treatment plants can remove the majority of microplastics from wastewater, significant quantities still pass through into waterways, and the microplastics captured in sewage sludge may re-enter the environment when that sludge is applied to farmland.

2020 Environment International 589 citations
Article Tier 2

Review on the occurrence and fate of microplastics in Sewage Treatment Plants

This review compiled occurrence and fate data for microplastics across influent, effluent, and sludge from sewage treatment plants, finding that concentrations range up to 3,160 particles/L in raw wastewater and that treatment achieves up to 98% removal, with the retained microplastics concentrated in sludge. The authors highlight that while WWTPs protect receiving waters, sludge disposal transfers the plastic burden to soils.

2018 Journal of Hazardous Materials 400 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

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