Sources, fate, effects, and analysis of microplastic in wastewater treatment plants: A review

Microplastics (MPs) are tiny pieces of plastic smaller than 5mm that have raised concerns to aquatic organisms and human health due to their ubiquitous presence. Wastewater Treatment Plants (WWTPs) are a significant point source for aquatic MPs pollution, as millions of MPs with different characteristics reach WWTPs through the Sewage. Even though, WWTPs are not specifically designed to remove MPs, researchers report that more than 90% of MPs can be removed in WWTPs. However, given the huge volumes of effluent discharge into natural aquatic bodies, even small concentrations of MPs in the effluent would be significant. A typical WWTP consists of three key stages: primary, secondary and tertiary. Removal of MPs in these stages is reviewed. In addition, plastics can adsorb toxic chemical and biological pollutants on its surface and can lead to spread of toxic pollutants in the environment. Therefore, in this review we aim to provide comprehensive knowledge about the sources of MPs in wastewater, their fate and removal in WWTPs, their interactions with different chemical and biological pollutants, and their effects on environment. In addition, it also highlights the different methodologies used for sampling, sample preparation and physical and chemical identification of MPs found in the WWTPs.