Estrogens constitute a group of important contaminants that may contribute to low fish populations in freshwaters receiving discharges from municipal wastewater treatment facilities. Information on their biodegradation is needed to design effective treatment methods. This research project will conduct laboratory studies to understand the biodegradation mechanism for estrogen and the factors that affect estrogen biodegradation rates in nitrifying wastewater systems and advance methods to enhance estrogen degradation. Initial studies will involve fundamental investigations of EE2 degradation of the synthetic birth control pharmaceutical, 17a-ethynyl estradiol (EE2), by pure cultures of ammonium-oxidizing bacteria (AOB), N. europaea, Nitrosospira, and Nitrosomonas oligotropha. Studies of EE2 degradation mechanisms will increase understanding of the role of various enzymatic reactions and assess degradation products. Biodegradation rate data will be obtained for the estrogen compounds for a process model that includes the effects of estrogen, ammonium and dissolved oxygen concentration, and effects of mixtures of estrogens in the ng/L to ug/L range. The estrogen degradation/nitrification model will be used to design optimized activated sludge processes. The estrogen degradation ability of other cometabolic organisms, such as methane- and phenol-oxidizing bacteria also will be investigated.
