In vitro bioanalytical assessment of the occurrence and removal of bioactive chemicals in municipal wastewater treatment plants in Korea

Effluents of wastewater treatment plants (WWTPs) contain various organic micropollutants, some of which can exert negative effects on the quality of receiving waters or drinking water sources. This study monitored two full-scale WWTPs in Korea for the occurrence and removal of bioactive chemicals for a one-year period using a battery of in vitro bioassays as a complementary approach to chemical analysis. Bioassays covering different endpoints were em-ployed, such as hormone receptor activation (AR and ER alpha), xenobiotic metabolism (PAH and PXR), oxidative stress response (Nrf2), and cytotoxicity. The WWTP influents showed AR, ER alpha, and PAH activities at ng/L -mu g/L and PXR and Nrf2 activities at mu g/L -mg/L as bioanalytical equivalent concentrations of a reference compound for each bioas-say. These bioactivities decreased along with the WWTP treatment train, with significant removals achieved by the secondary biological treatment processes. Cytotoxicity was observed only for some municipal wastewater (M-WWTP) influents but was below the limit of quantification for most cases. The influent and effluent bioactivities observed in this study were mostly comparable to those reported in other WWTPs in the literature. Comparison of the bioactivities with the effect-based trigger (EBT) values indicates that the impact of WWTP effluents on receiving water quality was low for most endpoints. For Nrf2, however, further investigation is required to evaluate the observed high bioactivities compared with the current EBT. The observed ER alpha activity could partly be explained by the presence of some steroid estrogens. Overall, our results contribute to an important database for the concentrations and removal efficiencies of bioactive chemicals in WWTPs and demonstrate bioassays as a useful tool for urban water quality monitoring.

Automated summary

This study monitored the occurrence and removal of bioactive chemicals in two full-scale wastewater treatment plants in Korea using in vitro bioassays as a complementary approach. The bioactivities decreased along with the treatment train of the plants, with significant removal achieved by the secondary biological treatment processes. Most of the influent and effluent bioactivities observed in this study were comparable to those reported in other wastewater treatment plants.