Papers

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Article Tier 2

The Effects of Microplastics on Floc Formation, Nutrient Removal and Settleability in Wastewater Treatment

Researchers investigated how microplastics affect floc formation, nutrient removal, and settleability in wastewater treatment systems, examining the mechanisms by which these ubiquitous anthropogenic pollutants entering via packaging, cosmetics, and other production sectors disrupt activated sludge processes.

2024
Article Tier 2

Effect evaluation of microplastics on activated sludge nitrification and denitrification

Researchers found that microplastics entering wastewater treatment plants interfere with the nitrification and denitrification processes carried out by activated sludge microbes, potentially reducing the effectiveness of nutrient removal in sewage treatment. This effect could undermine water quality if microplastic loads in wastewater continue to increase.

2019 The Science of The Total Environment 172 citations
Article Tier 2

Mechanisms underlying the detrimental impact of micro(nano)plastics on the stability of aerobic granular sludge: Interactions between micro(nano)plastics and extracellular polymeric substances

Researchers found that both micro- and nanoplastics at realistic concentrations harmed the performance of aerobic granular sludge, a technology used for wastewater treatment, by reducing its ability to remove nitrogen. The plastic particles interacted with the sticky substances that hold the sludge granules together, weakening their structural integrity. The study reveals a specific mechanism by which plastic pollution can undermine wastewater treatment systems that communities rely on for clean water.

2024 Journal of Hazardous Materials 31 citations
Article Tier 2

Effects of microplastics on granular sludge: A review

This review examined how microplastics affect granular sludge properties and wastewater treatment efficiency in biological treatment systems, with wastewater plants considered major sinks for microplastics. The review found that harmful effects on granular characteristics are closely associated with microplastic size and concentration, summarizing how MPs disrupt granule formation and settleability.

2024 E3S Web of Conferences
Article Tier 2

Efficient removal of microplastic particles from wastewater through formation of heteroagglomerates during the activated sludge process

Microplastic particles were efficiently removed from wastewater using a novel treatment process, demonstrating high removal rates across different plastic sizes and polymer types. The technology contributes to the toolkit for preventing microplastic discharge from wastewater treatment plants into receiving waters.

2025 Journal of Hazardous Materials 1 citations
Article Tier 2

Fate, characteristics, and potential threat of microplastics in sludge under various dewatering treatments

Researchers compared four different sludge dewatering treatments used at wastewater plants and examined how each process affected the microplastics trapped in the sludge. They found that advanced oxidation treatments altered the surface properties of the microplastics and increased their ability to absorb heavy metals. The findings raise concerns that certain sludge treatment methods could make microplastics more environmentally hazardous when the treated sludge is disposed of or reused.

2025 Journal of Environmental Management 3 citations
Article Tier 2

Effects of microplastics on the properties of different types of sewage sludge and strategies to overcome the inhibition: A review

This review examined how microplastics trapped in sewage sludge during wastewater treatment affect sludge properties, microbial communities, and treatment efficiency, while discussing strategies to overcome microplastic-induced inhibition of sludge processing.

2023 The Science of The Total Environment 44 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

Effects of microplastics on substance transformation, sludge characteristics, toxicological effect, and microbial communities in different biochemical sludge systems: A review

This review synthesizes evidence that microplastics impair the biological and physical processes in wastewater treatment sludge systems, inhibiting nutrient removal, disrupting microbial communities, and degrading sludge structure—with smaller particles and higher concentrations causing greater damage. Because sludge is widely applied to agricultural land, any microplastic-driven impairment of treatment efficiency also increases the risk of plastic particles and associated pollutants reaching soils and food crops.

2023 Critical Reviews in Environmental Science and Technology 10 citations
Article Tier 2

Effects of chronic exposure to different sizes and polymers of microplastics on the characteristics of activated sludge

Researchers studied how 60 days of exposure to different sizes and types of microplastics affected activated sludge at wastewater treatment plants. Millimeter-sized particles dramatically reduced sludge dewaterability by up to 47.7%, mainly through physical disruption of sludge flocs. Nano-sized particles also impaired sludge performance by inhibiting microbial activity and altering the composition of extracellular polymeric substances.

2021 The Science of The Total Environment 67 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

[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

Response of aerobic granular sludge under polyethylene microplastics stress: Physicochemical properties, decontamination performance, and microbial community

Researchers investigated the impact of polyethylene microplastics on aerobic granular sludge used in wastewater treatment. The study found that microplastics significantly disrupted sludge structure, settling properties, and enzyme activities related to denitrification and phosphorus removal, with increased reactive oxygen species and cell membrane damage at higher concentrations.

2022 Journal of Environmental Management 79 citations
Article Tier 2

Efficient removal of microplastic particles from wastewater through formation of heteroagglomerates during the activated sludge process

Researchers found that across diverse microplastic polymer types, shapes, and sizes, more than 90% of spiked microplastic particles were incorporated into activated sludge flocs within 15 minutes of aeration and mixing during the wastewater treatment process. The similar removal behavior across all MP variants was attributed to near-neutral zeta potentials in filtered wastewater, suggesting van der Waals forces drive heteroagglomerate formation regardless of microplastic properties.

2025
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

Influence of polystyrene microplastics on the structural stability of activated sludge microbial flocs in sequencing batch reactors

Researchers exposed sequencing batch reactors to polystyrene microplastics at 0, 10, and 100 mg/L and measured effects on activated sludge floc structure. Microplastic exposure caused a 7.8-13.3% reduction in floc density and a significant rise in effluent turbidity, impairing sludge settling and potentially reducing wastewater treatment efficiency.

2025 Environmental Pollution
Article Tier 2

Microplastics in granular sequencing batch reactors: Effects on pollutant removal dynamics and the microbial community

Researchers investigated how polyethylene and polyethylene terephthalate microplastics affect pollutant removal in granular sludge wastewater treatment reactors. They found that microplastic type and concentration influenced nitrogen, phosphorus, and organic compound removal rates, with PET particles showing a stronger tendency to accumulate within the biomass. The study indicates that microplastic contamination in wastewater treatment systems may compromise treatment efficiency and alter microbial community dynamics.

2024 Journal of Hazardous Materials 12 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

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

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

Understanding and Improving Microplastic Removal during Water Treatment: Impact of Coagulation and Flocculation

Researchers systematically tested coagulation and flocculation for removing microplastics from drinking water, finding that removal efficiency depended strongly on plastic particle size and whether particles had been weathered, with smaller pristine particles being the hardest to remove.

2020 Environmental Science & Technology 424 citations
Article Tier 2

[Change in Granulation Potential and Microbial Enrichment Characteristics of Sludge Induced by Microplastics].

This study found that polyethylene terephthalate (PET) microplastics accelerate the formation of granular sludge in wastewater treatment plants by increasing sticky protein secretions, but continuous exposure ultimately degrades treatment performance and disrupts the microbial communities responsible for removing nitrogen. This matters because it suggests microplastics entering sewage systems could compromise the efficiency of the very facilities designed to filter them out.

2023 PubMed
Article Tier 2

Leaching behavior of microplastics during sludge mechanical dewatering and its effect on activated sludge

Researchers studied how mechanical dewatering of sewage sludge affects the microplastics embedded within it, including their physical changes and leaching behavior. They found that the dewatering process roughened microplastic surfaces, reduced particle sizes, and altered their chemical properties due to dewatering agents and mechanical forces. The study also showed that leachates from these processed microplastics could negatively affect activated sludge performance in treatment systems.

2024 Water Research 14 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