Interactions between microplastics and unit processes of wastewater treatment plants: a critical review

Abstract

Microplastics are classified as emerging pollutants of the aquatic environment, necessitating a comprehensive understanding of their properties for successful management and treatment. Wastewater treatment plants (WWTPs) serve as point sources of microplastic pollution of the aquatic and terrestrial (eco)systems. The first part of this review explores the basic definitions of microplastics, sources, types, physical and chemical methods of identifying and characterizing microplastics in WWTPs. The next part of the review details the occurrence of microplastics in various unit processes of WWTPs and sewage sludge. Followed by this, various methods for removing microplastics from wastewater are presented. Finally, the research gaps in this area were identified, and suggestions for future perspectives were provided. HIGHLIGHTS Wastewater treatment plants act as point sources of microplastic pollution.; Microplastics in wastewater treatment plants are diverse in composition, size, shape and origin.; Microplastics are seen in all unit processes of wastewater treatment plants.; Wastewater treatment plants remove bulk of microplastics entering them.; Majority of microplastics enter the environment from sludge generated in wastewater treatment plants.;

Keywords

• microplastics
• unit process
• wastewater
• wastewater treatment plant
• water pollution