Occurrence and fate of steroid estrogens in the largest wastewater treatment plant in Beijing, China Yiqi Zhou & Jinmiao Zha & Zijian Wang Received: 14 May 2011 /Accepted: 15 November 2011 /Published online: 3 December 2011 # Springer Science+Business Media B.V. 2011 Abstract Concern over steroid estrogens has increased rapidly in recent years due to their adverse health effects. Effluent discharge from wastewater treatment plants (WWTPs) is the main pollutant source for environmen- tal water. To understand the pollutant level and fate of steroid estrogens in WWTPs, the occurrence of estrone (E1), 17-β-estradiol (E2), estriol (E3), and 17-β- ethinylestradiol (EE2) was investigated in the Gaobei- dian WWTP in Beijing, China. Water samples from influent as well as effluent from second sedimentation tanks and advanced treatment processes were taken monthly during 2006 to 2007. In influent, steroid estrogen concentrations varied from 11.6 to 1.1× 10 2 ng/l, 3.7 to 1.4×10 2 ng/l, no detection (nd) to 7.6×10 2 ng/l and nd to 3.3×10 2 ng/l for E1, E2, E3, and EE2, respectively. Compared with documented values, the higher steroid estrogen concentrations in the WWTP influent may be due to higher population density, higher birthrate, less dilution, and different sampling time. Results revealed that a municipal WWTP with an activated sludge system incorporating anaerobic, anoxic, and aerobic processes could elim- inate natural and synthetic estrogens effectively. The mean elimination efficiencies were 83.2%, 96.4%, 98.8%, and 93.0% for E1, E2, E3, and EE2, respectively. The major removal mechanism for natural estrogens and synthetic estrogen EE2 were biodegradation and sorption on the basis of mass balance in water, suspension particles, and sludge. In the WWTP effluent, however, the highest concen- trations of E1, E2, E3, and EE2 attained were 74.2, 3.9, 5.1, and 4.6 ng/l, respectively. This is concerning as residual steroid estrogens in WWTP effluent could lead to pollution of the receiving water. Advanced flocculation treatment was applied in the WWTP and transformed the residual estrogen conjugates to free species, which were reduced further by filtration with removal shifting from 32% to 57% for natural estrogen, although no EE2 was removed. Keywords EDCs . Steroid estrogen . Wastewater . Presence . Removal Introduction Endocrine disrupters are exogenous agents that interfere with the synthesis, secretion, transport, binding, action, and elimination of natural hormones responsible for the maintenance of homeostasis, reproduction, development, and behavior (US Envi- ronmental Protection Agency 1997). Chemicals such as xeno-estrogens alkylphenols, bisphenol A, phtha- late, pesticides, polyaromatic compounds, and steroid estrogen are considered to be endocrine disrupters (Desbrow et al. 1998; Jobling et al. 1998). Natural Environ Monit Assess (2012) 184:6799–6813 DOI 10.1007/s10661-011-2459-y Y. Zhou : J. Zha : Z. Wang (*) State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, PO Box 2871, Beijing 100085, People’ s Republic China e-mail: wangzj@rcees.ac.cn