Development of emission factors to estimate discharge of typical pharmaceuticals and personal care products from wastewater treatment plants

Abstract

Due to the potential ecological and human health risks, pharmaceuticals and personal care products (PPCPs) are considered as contaminants of emerging concern. PPCPs can be discharged to the aquatic environment from various sources, including municipal wastewater treatment plants (WWTPs), animal feeding operations, hospitals, and pharmaceutical manufacturers. A major challenge to regional characterization of ecological and human health risks is identification of the environmental emissions of PPCPs. This study established a facile approach for calculation of PPCP emission factors from raw wastewater and wastewater effluent. Using reported concentrations from WWTPs, nine PPCPs, namely carbamazepine, ciprofloxacin, erythromycin, ibuprofen, ketoprofen, ofloxacin, sulfadiazine, sulfamethoxazole, and trimethoprim, were identified as priority contaminants based on environmental significance (i.e., high detection frequency and potential ecological risk) and data availability. Emission factors were calculated for the nine PPCPs in raw wastewater, secondary effluent, and tertiary effluent for low, medium and high emission scenarios according to the concentration distributions of these nine PPCPs. The emission factors were used to estimate the mass of the PPCPs discharged from the nine provinces and two municipalities of the Yangtze River valley. The total mass of the nine PPCPs emitted into the watershed was estimated as 3867 kg, 8808 kg and 21,464 kg for low, medium and high emission scenarios respectively in 2018. Although uncertainty is inevitable in the emission factors, the reported approach provides a viable alternative to top-down and multimedia fugacity estimation strategies that require an abundance of sewershed-, WWTP-, and compound-specific information that is difficult to collect in developing countries.