Papers

61,005 results
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Article Tier 2

Factors affecting microplastic retention and emission by a wastewater treatment plant on the southern coast of Caspian Sea

Researchers measured microplastic removal efficiency at a wastewater treatment plant on the southern Caspian Sea coast, finding that MP concentrations dropped from 12,667 items/m3 at the grit chamber to 423 items/m3 at the clarifier outlet, representing 96.7% removal. Fibers dominated all treatment stages and MP shape, size, and polymer type influenced removal rates across treatment steps.

2020 Chemosphere 114 citations
Article Tier 2

No seasonal differences in the emission of microplastics from an urban wastewater treatment plant on the Southern Coast of the Caspian Sea

Researchers measured microplastic concentrations in treated wastewater discharged from a treatment plant near the Caspian Sea in two different seasons, finding no significant seasonal difference in pollution levels. This first study from the region establishes a baseline for how much microplastic enters the Caspian from this urban source.

2021 Data Archiving and Networked Services (DANS)
Article Tier 2

Microplastic particles in sediments and waters, south of Caspian Sea: Frequency, distribution, characteristics, and chemical composition

Researchers assessed microplastic occurrence in coastal sediments and surface waters along the southern Caspian Sea coast in Iran, finding mean concentrations of 15 items/kg in sediments and 710 items/m3 in coastal water. Fibers dominated at 97% of all MPs in both media and were predominantly black-colored, with smaller particles more prevalent in water than sediments.

2020 Ecotoxicology and Environmental Safety 90 citations
Article Tier 2

Abundance, characteristics, fate, and removal of microplastics during municipal wastewater treatment plant in the west of Iran: the case of Kermanshah city

A three-month study of a conventional activated sludge wastewater treatment plant in Kermanshah, Iran found that while the facility removed about 64% of incoming microplastics, large quantities still passed through into the effluent — making the plant a net source of microplastic pollution to the aquatic environment. Fibers dominated incoming samples while fragments were more prevalent in the treated effluent, and polyethylene was the most common polymer detected throughout.

2023 Environmental Monitoring and Assessment 11 citations
Article Tier 2

Microplastics in Mediterranean coastal wastewater treatment plants: Seasonal trends driven by tourism and weather conditions

Researchers monitored microplastics at two Mediterranean coastal wastewater treatment plants in Spain, finding influent concentrations of 30-75 particles/L with seasonal peaks in warmer months, removal efficiencies of 73-86%, and significant correlations between microplastic concentrations and both temperature and precipitation, with polypropylene and polyethylene dominating polymer profiles.

2025 Journal of Environmental Management
Article Tier 2

Microplastic distributions in a domestic wastewater treatment plant: Removal efficiency, seasonal variation and influence of sampling technique

A year-long study of a municipal wastewater treatment plant found 97% removal efficiency for microplastics overall, but fibers made up a larger proportion of remaining particles in treated water than in raw sewage, and winter samples had notably higher microplastic concentrations. The study highlights seasonal variation as an important factor in assessing wastewater microplastic loads.

2020 The Science of The Total Environment 220 citations
Article Tier 2

Microplastics in an urban wastewater treatment plant: The influence of physicochemical parameters and environmental factors

Microplastics were quantified across four treatment stages of an urban wastewater treatment plant, finding an overall 90.3% removal efficiency with fragments and fibers dominating the final effluent, and identifying rainfall events and seasonal variation as significant factors affecting MP concentrations. The study highlights the importance of environmental variables when monitoring MP removal at WWTPs.

2019 Chemosphere 419 citations
Article Tier 2

Characteristics and Seasonal Distribution of Microplastics in the Surface Waters of Southwest Coast of the Caspian Sea (Guilan Province, Iran)

Researchers measured microplastic concentrations in surface waters along the southwest coast of the Caspian Sea in Iran across four seasons, finding an average of over 1,000 microplastic particles per cubic meter. Concentrations varied by season and location, with fibers being the most common type found.

2021 Bulletin of Environmental Contamination and Toxicology 23 citations
Article Tier 2

An evaluation of microplastics fate in the wastewater treatment plants: frequency and removal of microplastics by microfiltration membrane

This study assessed microplastic removal efficiency at a wastewater treatment plant in Iran and tested microfiltration membrane performance, finding that the membrane significantly improved microplastic removal beyond conventional treatment steps.

2021 Water Practice & Technology 56 citations
Article Tier 2

Distribution and abundance of microplastics in urban and industrial wastewater treatment plants in Tabriz metropolis

Researchers assessed microplastic contamination in two urban and five industrial wastewater treatment plants in Tabriz, Iran, a city of 1.6 million people. Urban treatment plants removed less than 10% of microplastics, while industrial plants showed somewhat better removal rates. The study found that existing wastewater treatment infrastructure is largely ineffective at filtering out microplastics, meaning significant quantities are being released into surface waters.

2025 Scientific Reports 6 citations
Article Tier 2

Seasonal variation and removal of microplastics in a central Asian urban wastewater treatment plant

Researchers investigated microplastic presence and removal at a wastewater treatment plant in Astana, Kazakhstan, finding that the facility achieved 88 to 93 percent removal efficiency. Despite low concentrations in the treated water, the sheer volume of daily discharge means the plant still contributes meaningfully to microplastic pollution in nearby waterways. Polyethylene fragments were the most common type detected, with seasonal variation showing higher levels in summer influent.

2024 Marine Pollution Bulletin 17 citations
Article Tier 2

Wastewater treatment plants as a source of microplastics to an urban estuary: Removal efficiencies and loading per capita over one year

Three South Carolina wastewater treatment plants were monitored for microplastic loads and removal efficiencies monthly over a year, finding removal of 59–98% with concentrations in effluent varying 4.8-fold between samples and no seasonal trend. The study demonstrates that even large, well-operated WWTPs release substantial quantities of microplastics year-round to receiving estuaries.

2019 Water Research X 492 citations
Article Tier 2

Evaluation of microplastics removal efficiency at a wastewater treatment plant discharging to the Sea of Marmara

Researchers tracked microplastics through all compartments of a secondary wastewater treatment plant in Istanbul, finding that the plant removed about 86% of incoming microplastics but still discharged a substantial number to the Sea of Marmara, with fibers as the dominant form.

2021 Environmental Pollution 106 citations
Article Tier 2

Identification and Analysis of Plastic Microparticles in the Inlet and Outlet of the Wastewater Treatment Plant and Investigation of the Relationship between Different Seasons of the Year with the Amount of Production and Emission of Particles

Researchers identified and characterized microplastics at the inlet and outlet of a wastewater treatment plant across different seasons, finding that conventional treatment fails to fully remove microplastics and that particle concentrations and types varied with seasonal changes.

2022 Advances in Materials Science and Engineering 6 citations
Article Tier 2

Identification and distribution of microplastics in the sediments and surface waters of Anzali Wetland in the Southwest Caspian Sea, Northern Iran

Researchers documented the occurrence, abundance, and distribution of microplastics in sediments and surface waters of Anzali coastal wetland on the southwest Caspian Sea, finding concentrations between 140-2,820 items/kg dry weight in sediments and up to 4.41 items/m3 in surface water. Fibers were the most common shape and concentrations were higher in the dry season, with the wetland serving as a significant microplastic sink.

2020 Marine Pollution Bulletin 114 citations
Article Tier 2

Occurrence, identification, and discharge of microplastics from effluent and sludge of the largest WWTP in Iran—South of Tehran

Researchers quantified microplastics in Iran's largest wastewater treatment plant and found significant concentrations in both effluent and sludge, identifying the facility as a pathway for microplastic release into the environment despite treatment processes.

2022 Water Environment Research 24 citations
Article Tier 2

Influence of wastewater treatment process on pollution characteristics and fate of microplastics

Researchers investigated microplastic abundance and removal efficiency across four wastewater treatment plants using different treatment technologies, finding influent concentrations between 539 and 1,290 particles per liter that were reduced substantially by primary and secondary treatment. Smaller microplastic particles proved hardest to remove and most likely to persist in final effluent.

2021 Marine Pollution Bulletin 45 citations
Article Tier 2

Microplastics in an advanced wastewater treatment plant: sustained and robust removal rates unfazed by seasonal variations

Researchers evaluated microplastic removal at an advanced wastewater treatment plant discharging into the Mediterranean Sea across three seasonal campaigns. The plant achieved removal rates above 99% consistently, with efficiency remaining robust even during rainy and high-tourism periods. The study found that primary treatment stages, particularly coagulation and settling, were most effective at capturing microplastics, with polyester being the predominant polymer type detected.

2024 Microplastics and Nanoplastics 14 citations
Article Tier 2

Microplastic emission trends in Turkish primary and secondary municipal wastewater treatment plant effluents discharged into the Sea of Marmara and Black Sea

Researchers tracked microplastic emission trends from Turkish primary and secondary municipal wastewater treatment plant effluents, finding that while treatment reduces MP concentrations, significant quantities are still discharged into receiving water bodies.

2023 Environmental Research 50 citations
Article Tier 2

Identification, Quantification, and Evaluation of Microplastics Removal Efficiency in a Water Treatment Plant (A Case Study in Iran)

Researchers investigated microplastic occurrence and removal efficiency across treatment stages of a drinking water treatment plant in Iran, finding an influent concentration of 1597.7 MPs/L with an overall removal efficiency of 83.7%, yet still discharging an estimated 2.25 x 10^11 MPs daily into the distribution system, with PP, PE, and PET as the dominant polymers.

2022 Air Soil and Water Research 14 citations
Article Tier 2

Occurrence and Seasonal Variation of Microplastics in the Effluent from Wastewater Treatment Plants in Qingdao, China

Microplastic characteristics in effluents from five wastewater treatment plants in Qingdao, China were analyzed in winter and summer, finding fibers dominated by rayon and PET with average concentrations higher in winter, confirming WWTPs as a significant source of microplastics to the marine environment.

2022 Journal of Marine Science and Engineering 54 citations
Article Tier 2

Spatiotemporal Distribution Characteristics and Removal Efficiency of Microplastics in a Wastewater Treatment Plant

Researchers examined microplastic removal efficiency across three seasons at a wastewater treatment plant in Zhengzhou, China, sampling influent, process effluent, and final effluent. They found an overall removal efficiency of 86%, with polypropylene and polyethylene terephthalate as the dominant polymer types and fragment- and granule-shaped particles comprising over 80% of microplastics detected.

2025 Water
Article Tier 2

Distribution of microplastics in upstream and downstream surface waters of the Iranian rivers discharging to the southern Caspian Sea

This study mapped the spatial and seasonal distribution of microplastics in surface waters of 13 rivers discharging into the Caspian Sea in Iran, providing baseline contamination data for a region previously lacking systematic microplastic monitoring.

2023 Environmental Science and Pollution Research 23 citations
Article Tier 2

A study on characteristics of microplastic in wastewater of South Korea: Identification, quantification, and fate of microplastics during treatment process

Microplastics were tracked through three South Korean wastewater treatment plants with different tertiary treatment methods, finding 75–92% removal by primary and secondary treatment and over 98% removal after tertiary treatment. The study confirms that advanced treatment steps are necessary to approach near-complete microplastic removal from municipal wastewater.

2019 Marine Pollution Bulletin 555 citations