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A systematic review on the occurrence and removal of microplastics during municipal wastewater treatment plants

Environmental Engineering Research 2024 9 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Anvar Asadi, Faranak Khodadoost, Nebile Dağlıoğlu, Setareh Eris

Summary

This systematic review analyzed 54 wastewater treatment plants across 25 studies to determine how effectively they remove microplastics. The findings show an average removal rate of about 88%, but the remaining 12% passes through into waterways. This matters because the microplastics that escape treatment plants end up in rivers, lakes, and oceans, eventually entering our drinking water and food supply.

Study Type Review

This study uses a systematic review of Scopus, Web of Science, and ScienceDirect databases to investigate the removal rate of microplastics (MPs) at various stages of municipal wastewater treatment plants (WWTPs). In this context, 25 articles were included, which investigated 54 WWTPs. Results showed that the overall removal efficacy of MPs in studied WWTPs is about 88.1 (± 18.8) percent. The contribution of preliminary, primary, secondary, tertiary, and disinfection treatment in the removal of entry MPs are 37.4% (± 24), 62.7% (± 20.8), 63.7% (± 24.8), 62.8% (± 29.5), and 12.5% (± 15.7) (mean (± SD)), respectively. The critical aspects about MPs occurrence in WWTPs influent were summarized and on average 2267.2 (± 5376.4) MPs particles per liter (P/L) were present with a considerable wide range of 0.28 to 31400 P/L. In the next section, details about frequent shape (i.e., spherical (beads, pellets, granules), lines (filaments, fibers), films, fragments, and foams) of MPs in influent and effluent of included WWTPs and their removal efficacy during treatment steps are given. Finally, this study highlights future challenges in MP removal and suggests key areas for further research, such as improving treatment efficiency and understanding MP characteristics.

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