EVALUATION OF THE FATE OF SYNTHETIC AND NATURAL HORMONES IN A FULL MUNICIPAL WASTEWATER TREATMENT PLANT Nazim Cicek *, Kathleen Londry, Jan A. Oleszkiewicz, Yoomin Lee *Department of Biosystem Engineering, University of Manitoba Winnipeg, MB, Canada. R3T 5V6 ABSTRACT The impact of a full-scale municipal wastewater treatment plant (WWTP), and each of the treatment units within the stream, on the removal of endocrine-disrupting compounds was evaluated by tracking three estrogenic compounds: 17-β-estradiol (E2, natural); estrone (E1, natural, metabolite of E2); and 17-α-ethinylestradiol (EE2, synthetic). The overall performance of the WWTP compared well with other plants, as 90.5% removal of E1+E2, and 76.4% removal of EE2 were observed. The activated sludge units reduced the concentration of E1+E2, and EE2 in the liquid phase by 88.2% and 44.6%, respectively. Additional removal of soluble phase estrogens (68% and 62% for E1+E2 and EE2, respectively) was observed in the equalization basin prior to UV disinfection. Although not statistically significant, the UV treatment process appeared to result in a slight increase in soluble phase estrogens. The aqueous phase of the tertiary lagoon sludge contained higher levels of estrogens compared to the lagoon influent. This was attributed to the possible de-sorption of particulate matter-bound estrogens during storage in the lagoon. KEYWORDS Estrogens, endocrine disrupting compounds, hormones, municipal wastewater treatment plant, activated sludge treatment, effluent INTRODUCTION There is a growing concern about the impact of natural and synthetic hormones on the safety of freshwater supplies. Hormones such as estrogens have been shown to be released from a wide variety of wastewater treatment plants (WWTPs), and although they are present in very low concentrations (ng/L), these amounts can be sufficient to disrupt endocrine systems of aquatic species such as fish (Johnson and Sumpter, 2001). EDCs released in domestic sewage treatment plant effluents are causing male fish, living immediately downstream of discharge, to be feminized through the development of unusual testes, production of an egg protein precursor normally found only in females, depressed circulating sex hormone levels, and reduced gonad sizes (Desbrow, et al., 1998, Purdom, et al., 1994, Snyder, et al., 2001). Estrogenic compounds include 17-β-estradiol (E2) which is the natural estrogen, and 17-α-ethynylestradiol (EE2) which is a synthetic estrogen and the main component of birth control pills, both of which are excreted in human urine and feces (Desbrow, 1998). In addition, E2 is transformed biologically and abiotically (in a reversible fashion) to estrone (E1) which is likewise estrogenic but of less