Estimating wastewater emissions and environmental levels of typical organic contaminants based on regionalized modelling.

Organic contaminants (OCs) are released into the environment through effluent discharges from wastewater treatment plants (WWTP), posing risks to environment health. However, emissions from various source, particularly large-scale investigations across different industries, remain poorly understood. Based on both sampling and statistical data, this study estimates the emissions of 10 OCs, including perfluorooctane acid (PFOA), perfluorooctane sulfonate (PFOS), 4-nonylphenol (4-NP), 4-tert-octylphenol (4-t-OP), dibutyl phthalate (DBP), di-iso-butyl phthalate (DIBP), dimethyl phthalate (DMP), butyl benzyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), and bisphenol A (BPA), from the effluents of 160 factories across 8 industries, 541 municipal wastewater treatment plants (MWWTPs), and 8 waste treatment plants (WTPs) in the upper Yangtze River Basin. A level III fugacity multimedia model was used to assess the impacts of these emissions on local watersheds. Among the 8 industries, paper production was the largest contributor, accounting for over 80% of total OC emissions, which amounted to 89.1 kg/yr. The contributions of domestic and industrial sources were 91.5% and 8.5%, respectively, underscoring the predominance of domestic sources in the release of the 10 OCs. PFOA emerged as the most dominant compound, with total emissions amounting to 4464 kg/yr from domestic sources and 170 kg/yr from industrial sources. The predicted concentrations of OCs in the receiving rivers closely aligned with values reported in existing literature, differing by no more than one order of magnitude. To our knowledge, this is the first comprehensive report on emissions from various sources in the upper Yangtze River Basin.