Antidepressants in wastewater treatment plants: Occurrence, transformation and acute toxicity evaluation

Antidepressants (ATDs) are one of the most prescribed medications for psychiatric conditions. The widespread presence in aquatic environment and demonstrated ecotoxicity make ATDs a class of concerning emerging contaminants. Municipal wastewater treatment plants (WWTPs) provide important connecting channel between wastewater and aquatic environment. Herein, we present a critical overview of the occurrence, transformation and toxicity of typical ATDs during water treatments. The total concentration of the detected ATDs and their metabolites in the WWTP influents and effluents are 72.62-5011.80 ng/L and 114.48-6992.40 ng/L, respectively, on a global scale. The frequently observed negative removal of ATDs in WWTPs indicates that some ATDs exist as conjugates in wastewaters. The biotic and abiotic transformation of ATDs and the generated transformation byproducts (TPs) were identified, which occurred in WWTPs worldwide along with ATDs. Acute toxicity of ATDs and their TPs was predicated using the ECOSAR model. Compared to ATDs, the demonstrated enhanced toxicity of several TPs to aquatic organisms necessitates more attention on TPs monitoring in WWTPs. This work provides scientific support for wastewater advanced treatment to alleviate ATDs pollution in effluents.