Occurrence, emissions, and risks of microplastics and plastic additives from typical municipal wastewater treatment plants effluents in China.

Abstract

Municipal wastewater treatment plants (WWTPs) are important pathways for microplastics (MPs), plastic additives, and other associated contaminants to enter receiving waters, yet their combined pollution and risks remain poorly constrained across broad geographic regions. Here, MPs and plastic additives were investigated in effluents from 46 typical WWTPs distributed across 31 provincial-level regions of China. MPs occurred in all effluents at 6.0-589.0 items L⁻¹ ; fragments dominated, 95.6% were < 1 mm, and polystyrene was the most abundant polymer. National emissions were estimated at 2.35 × 1015 particles yr-1, equivalent to 552 yr-1, with loads positively associated with served population. Sixty-four plastic additives and associated contaminants were detected at total organic concentrations of 799.54-5534.19 ng L⁻¹ . Bisphenols, phthalate esters, and organophosphate esters dominated the organic profile, contributing 58.9%, 26.5%, and 11.4%, respectively. Organic risks were driven mainly by bisphenols, whereas elevated Zn contributed to metal-related risk at some sites. Polymer-dependent co-occurrence patterns between MPs and additives indicated potential combined exposure. An ecological risk index integrating CRITIC-derived and expert-judgment weights classified all sites as moderate risk or higher. These findings provide broad geographic evidence from typical WWTPs and a tool for coordinated management of MPs, plastic additives, and associated contaminants in WWTP effluents.