Occurrence and Fate of Steroid Hormones in Sewage Treatment Plants

Abstract

Sewage treatment plants (STPs) are one of the crucial barriers for the environmental emission of steroid hormones. Insights into the occurrence and fate of different categories of steroid hormones in STPs could provide theoretical support for improving steroid removal by STPs. The present study investigated 22 steroid hormones in each treatment process of two STPs located in Wuxi via eight monthly sampling campaigns and compared the efficacy of Anaerobic-Anoxic-Aerobic (A2/O) and reversed A2/O treatments. The results showed that the total steroid concentrations in the influent and effluent were 27.7-256.8 ng·L-1 and 5.7-211.0 ng·L-1, respectively, and 36.3-123.6 ng·g-1 in the excess sludge. Androsterone, androstenedione, estrone, estriol, and progesterone were the main species detected in the STPs. The concentrations of most steroids increased with the rise of rainfall and temperature, whereas the removal rates were not significantly different between winter and summer. Secondary and tertiary treatment processes showed better performance in steroid removal compared with that in the primary treatment; however, reversed A2/O did not show advantages over traditional A2/O. The organic-normalized partition coefficients (lg Koc) of steroids ranged between 2 and 4.5. The values of lg Koc in STP A were slightly greater than those in STP B, indicating that the partition behavior of steroids may influence their treatment efficacies.