{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T05:19:34Z","timestamp":1788326374778,"version":"build-2803163510"},"reference-count":42,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T00:00:00Z","timestamp":1788134400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Key R&D Special Project of Henan Province","award":["241111320200"],"award-info":[{"award-number":["241111320200"]}]},{"DOI":"10.13039\/501100004543","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42477394"],"award-info":[{"award-number":["42477394"]}],"id":[{"id":"10.13039\/501100004543","id-type":"DOI","asserted-by":"publisher"}]},{"award":["42477394"],"award-info":[{"award-number":["42477394"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&D Program of China","doi-asserted-by":"crossref","award":["2024YFC13900"],"award-info":[{"award-number":["2024YFC13900"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxics"],"abstract":"<jats:p>As emerging persistent contaminants, microplastics (MPs) are ubiquitous in aquatic environments. Wastewater treatment plants (WWTPs) act as critical sinks and sources of MPs, and their MPs removal efficiency can strongly influence aquatic ecological safety. To investigate how different process configurations affect MPs occurrence and removal performance, four municipal WWTPs equipped with diverse biological and advanced treatment processes were sampled and analyzed. MPs were extracted via density flotation combined with H2O2 digestion, and their morphological and polymeric features were identified using stereomicroscopy and Fourier-transform infrared (FTIR) spectroscopy. The results revealed that MPs removal efficiencies differed significantly across treatment processes: WWTP4 exhibited the highest comprehensive removal efficiency of 63.89% in the operational situations, followed by WWTP1 of 56.25% and WWTP3 of 51.61%, while WWTP2 exhibited the weakest elimination capacity of 28.12%. It could also be concluded that the differences were primarily governed by biological adsorption and advanced filtration units. Meanwhile, Fragmented and pellet MPs showed higher removal efficiencies than fibrous and film-shaped MPs, while Polymers including PVC, PS, PTFE and PP were more resistant to removal. Longer hydraulic retention time (HRT) and a stable and sufficiently long sludge retention time (SRT) promoted the association of MPs with activated sludge, whereas excessive aeration induced MPs fragmentation and resuspension. Optimizing operational parameters and upgrading advanced filtration facilities could facilitate the regulation and management of MPs. This study provides a theoretical basis for mitigating MPs emissions from municipal WWTPs.<\/jats:p>","DOI":"10.3390\/toxics14090775","type":"journal-article","created":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T09:48:36Z","timestamp":1788256116000},"page":"775","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Impacts of Wastewater Treatment Processes on the Occurrence Characteristics of Microplastics\u2014Taking Four Wastewater Treatment Plants in Northern Henan Province as Examples"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2894-1174","authenticated-orcid":false,"given":"Yiping","family":"Guo","sequence":"first","affiliation":[{"name":"School of Ecology and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450046, China"},{"name":"Henan Engineering Research Center of Water Pollution and Soil Damage Remediation, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]},{"given":"Jinhong","family":"Li","sequence":"additional","affiliation":[{"name":"School of Ecology and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"given":"Shihang","family":"Ni","sequence":"additional","affiliation":[{"name":"School of Ecology and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"}]},{"given":"Qianqian","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Ecology and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"}]},{"given":"Li","family":"Guo","sequence":"additional","affiliation":[{"name":"Environmental Monitoring and Safety Center, Department of Ecology and Environment of Henan Province, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"}]},{"given":"Bingtao","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Ecology and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Peng","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Natural Resources and Environment, Northwest A&F University, Xianyang 712100, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4955-1626","authenticated-orcid":false,"given":"Weigao","family":"Zhao","sequence":"additional","affiliation":[{"name":"Department of Environmental Engineering, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Yupeng","family":"Li","sequence":"additional","affiliation":[{"name":"Henan Provincial Urban and Rural Water Affairs Research Institute Co., Ltd., Zhengzhou 450046, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"}]},{"given":"Hanzhong","family":"Jia","sequence":"additional","affiliation":[{"name":"College of Natural Resources and Environment, Northwest A&F University, Xianyang 712100, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1126\/science.1094559","article-title":"Lost at sea: Where is all the plastic?","volume":"304","author":"Thompson","year":"2004","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1596","DOI":"10.1016\/j.marpolbul.2011.05.030","article-title":"Microplastics in the marine environment","volume":"62","author":"Andrady","year":"2011","journal-title":"Mar. Pollut. Bull."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"21382","DOI":"10.1021\/acs.est.5c11689","article-title":"Transforming the Study of the Mechanical Degradation of Plastic: Advancing Microplastic Release Predictions through Quantitative Approaches","volume":"59","author":"Xiong","year":"2025","journal-title":"Environ. Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"483","DOI":"10.1016\/j.envpol.2013.02.031","article-title":"The physical impacts of microplastics on marine organisms: A review","volume":"178","author":"Wright","year":"2013","journal-title":"Environ. Pollut."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2588","DOI":"10.1016\/j.marpolbul.2011.09.025","article-title":"Microplastics as contaminants in the marine environment: A review","volume":"62","author":"Cole","year":"2011","journal-title":"Mar. Pollut. Bull."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"102410","DOI":"10.1016\/j.seares.2023.102410","article-title":"Microplastics in seafood: Implications for food security, safety, and human health","volume":"194","author":"Unuofin","year":"2023","journal-title":"J. Sea Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"169926","DOI":"10.1016\/j.scitotenv.2024.169926","article-title":"Understanding microplastic pollution: Tracing the footprints and eco-friendly solutions","volume":"914","author":"Bhatia","year":"2024","journal-title":"Sci. Total Environ."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1016\/j.marpolbul.2017.01.082","article-title":"The plastic in microplastics: A review","volume":"119","author":"Andrady","year":"2017","journal-title":"Mar. Pollut. Bull."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1016\/j.watres.2016.01.002","article-title":"Transport and fate of microplastic particles in wastewater treatment plants","volume":"91","author":"Carr","year":"2016","journal-title":"Water Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1016\/j.watres.2019.03.036","article-title":"Variable responses of dissolved organic carbon to precipitation events in boreal drinking water lakes","volume":"156","author":"Warner","year":"2019","journal-title":"Water Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"579","DOI":"10.1016\/j.jclepro.2019.03.321","article-title":"Microplastics in a municipal wastewater treatment plant: Fate, dynamic distribution, removal efficiencies, and control strategies","volume":"225","author":"Lv","year":"2019","journal-title":"J. Clean. Prod."},{"key":"ref_12","first-page":"133974","article-title":"Removal of microplastics by advanced tertiary treatment processes in municipal wastewater plants","volume":"373","author":"Sun","year":"2022","journal-title":"J. Clean. Prod."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1016\/j.watres.2019.02.028","article-title":"Microplastic abundance, characteristics, and removal in wastewater treatment plants in a coastal city of China","volume":"155","author":"Long","year":"2019","journal-title":"Water Res."},{"key":"ref_14","first-page":"100030","article-title":"Wastewater treatment plants as a source of microplastics to an urban estuary: Removal efficiencies and loading per capita over one year","volume":"3","author":"Conley","year":"2019","journal-title":"Water Res. X"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/j.watres.2018.05.034","article-title":"Microplastics in sewage sludge from the wastewater treatment plants in China","volume":"142","author":"Li","year":"2018","journal-title":"Water Res."},{"key":"ref_16","unstructured":"(2002). Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (Standard No. GB 18918-2002)."},{"key":"ref_17","unstructured":"(1989). Water Quality\u2014Determination of Chemical Oxygen Demand\u2014Dichromate Method (Standard No. GB 11914-89)."},{"key":"ref_18","unstructured":"(2012). Water Quality\u2014Determination of Total Nitrogen\u2014Alkaline Potassium Persulfate Digestion UV Spectrophotometric Method (Standard No. HJ 636-2012)."},{"key":"ref_19","unstructured":"(1987). Water Quality\u2014Determination of Ammonium\u2014Distillation and Titration Method (Standard No. GB 7478-87)."},{"key":"ref_20","unstructured":"(1989). Water Quality\u2014Determination of Total Phosphorus\u2014Ammonium Molybdate Spectrophotometric Method (Standard No. GB 11893-89)."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"113326","DOI":"10.1016\/j.envpol.2019.113326","article-title":"Pathway, classification and removal efficiency of microplastics in wastewater treatment plants","volume":"255","author":"Ngo","year":"2019","journal-title":"Environ. Pollut."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Dong, S., Gao, P., Li, B., Feng, L., Liu, Y., Du, Z., and Zhang, L. (2022). Occurrence and migration of microplastics and plasticizers in different wastewater and sludge treatment units in municipal wastewater treatment plant. Front. Environ. Sci. Eng., 16.","DOI":"10.1007\/s11783-022-1577-9"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"145113","DOI":"10.1016\/j.jclepro.2025.145113","article-title":"Removal of microplastics in sludge during intensive treatment processes in a wastewater treatment plant in China","volume":"496","author":"Li","year":"2025","journal-title":"J. Clean. Prod."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1016\/j.watres.2017.07.005","article-title":"Solutions to microplastic pollution\u2013Removal of microplastics from wastewater effluent with advanced wastewater treatment technologies","volume":"123","author":"Talvitie","year":"2017","journal-title":"Water Res."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1616","DOI":"10.1039\/D3VA00167A","article-title":"Fate and occurrence of microplastics in wastewater treatment plants","volume":"2","author":"Mesquita","year":"2023","journal-title":"Environ. Sci. Adv."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1016\/j.cej.2019.01.033","article-title":"Transfer and fate of microplastics during the conventional activated sludge process in one wastewater treatment plant of China","volume":"362","author":"Liu","year":"2019","journal-title":"Chem. Eng. J."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.psep.2020.08.039","article-title":"Microplastics in wastewater treatment plants: Occurrence, fate and identification","volume":"146","author":"Turan","year":"2021","journal-title":"Process Saf. Environ. Prot."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"126168","DOI":"10.1016\/j.jhazmat.2021.126168","article-title":"Atmospheric transport and deposition of microplastics in a subtropical urban environment","volume":"416","author":"Huang","year":"2021","journal-title":"J. Hazard. Mater."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"139875","DOI":"10.1016\/j.jhazmat.2025.139875","article-title":"Efficient removal of microplastic particles from wastewater through formation of heteroagglomerates during the activated sludge process","volume":"498","author":"Wiesner","year":"2025","journal-title":"J. Hazard. Mater."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1007\/s00449-022-02715-x","article-title":"Removing microplastics from wastewater using leading-edge treatment technologies: A solution to microplastic pollution\u2014A review","volume":"46","author":"Priya","year":"2023","journal-title":"Bioprocess Biosyst. Eng."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"e2018JC014719","DOI":"10.1029\/2018JC014719","article-title":"A global perspective on microplastics","volume":"125","author":"Hale","year":"2020","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"104200","DOI":"10.1016\/j.jwpe.2023.104200","article-title":"Abundance, characteristics and seasonal variation of microplastics in a domestic sewage treatment plant in Nanjing, China","volume":"55","author":"Huang","year":"2023","journal-title":"J. Water Process Eng."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"116411","DOI":"10.1016\/j.jenvman.2022.116411","article-title":"Research progress on microplastics in wastewater treatment plants: A holistic review","volume":"325","author":"Gao","year":"2023","journal-title":"J. Environ. Manag."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"119866","DOI":"10.1016\/j.watres.2023.119866","article-title":"Spectroscopic fingerprints profiling the polysaccharide\/protein\/humic architecture of stratified extracellular polymeric substances (EPS) in activated sludge","volume":"235","author":"Yu","year":"2023","journal-title":"Water Res."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Otieno, J.O., Nowak, Z.M., Parszuto, K., and Cydzik-Kwiatkowska, A. (2025). Impact of Tire Microplastics on Aerobic Granular Sludge Structure and EPS Composition Under Continuous and Intermittent Aeration. Appl. Sci., 15.","DOI":"10.3390\/app152312410"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1007\/s11270-023-06815-6","article-title":"Response of extracellular polymeric substances to high load shock in an aerobic granular sludge reactor performing simultaneous heterotrophic nitrification-aerobic denitrification","volume":"235","author":"Chen","year":"2024","journal-title":"Water Air Soil Pollut."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"119999","DOI":"10.1016\/j.jece.2025.119999","article-title":"Membrane bioreactor strategies for enhanced microplastic removal in wastewater: A review","volume":"13","author":"Zhan","year":"2025","journal-title":"J. Environ. Chem. Eng."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1045","DOI":"10.1016\/j.envpol.2016.08.056","article-title":"Microplastic pollution is widely detected in US municipal wastewater treatment plant effluent","volume":"218","author":"Mason","year":"2016","journal-title":"Environ. Pollut."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"685","DOI":"10.2166\/wst.2023.022","article-title":"Microplastics in wastewater treatment plants: Sources, properties, removal efficiency, removal mechanisms, and interactions with pollutants","volume":"87","author":"Acarer","year":"2023","journal-title":"Water Sci. Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"14455","DOI":"10.1021\/acs.langmuir.4c01216","article-title":"New insights into the formation of aggregates of bidisperse nano-and microplastics in water based on the analysis of in situ microscopy and molecular simulation","volume":"40","author":"Hammond","year":"2024","journal-title":"Langmuir"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"130219","DOI":"10.1016\/j.jhazmat.2022.130219","article-title":"A multi-scale framework for modeling transport of microplastics during sand filtration: Bridging from pore to continuum","volume":"443","author":"Lim","year":"2023","journal-title":"J. Hazard. Mater."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1038\/s41545-025-00531-w","article-title":"Microplastic removal across ten drinking water treatment facilities and distribution systems","volume":"8","author":"Balkenbusch","year":"2025","journal-title":"npj Clean Water"}],"container-title":["Toxics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2305-6304\/14\/9\/775\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T04:28:47Z","timestamp":1788323327000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2305-6304\/14\/9\/775"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,31]]},"references-count":42,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["toxics14090775"],"URL":"https:\/\/doi.org\/10.3390\/toxics14090775","relation":{},"ISSN":["2305-6304"],"issn-type":[{"value":"2305-6304","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,31]]}}}