Estrogenic activity and identification of potential xenoestrogens in a coking wastewater treatment plant

• Estrogenic activity are present in influent and effluents of coking wastewater.
• The removal of estrogenic activity in coking wastewater was higher than 99.9%.
• Xenoestrogens are the derivatives of indenol, naphthalenol, indol, acridinone, fluorenone, and carbazole.

In this study, the estrogenic activities in influent and effluents of coking wastewater from different treatment stages were studied using Yeast Estrogen Screen (YES) bioassays. Raw extracts were further fractioned to identify the potential xenoestrogens combined with YES bioassays and gas chromatography–mass spectrometry analysis. Influent, primary effluent, and anaerobic effluent showed high estrogenic activities, with potencies of 1136±269, 1417±320, and 959±69 ng/L of 17β-estradiol (E2) equivalent (EEQ), respectively. The potency of estrogenic activity was gradually removed through the treatment processes. In the final effluent, the estrogenic activity was reduced to 0.87 ng EEQ/L with a total removal efficiency of more than 99%, suggesting that the estrogenic activity was almost completely removed in the coking wastewater. For the fractions of raw extracts, bioassay results showed that the estrogenic activities were mostly present in the polar fractions. Correlation analysis between estrogenic activities and responses of identified chemicals indicated that potential xenoestrogens were the derivatives of indenol, naphthalenol, indol, acridinone, fluorenone, and carbazole. The estrogenic activity in the final effluent was higher than the predicted no effect concentration (PNEC) for E2, implying that the discharged effluent would probably exert estrogenic activity risk to the aquatic ecosystem in “the worst-case scenario.”