Determining the Kinetics of Biotransformation of Estradiol and Estrone during Transit in Sewage Collection Systems

Although wastewater treatment does remove a significant amount of estrogens, some estrogens survive wastewater treatment and enter surface water through wastewater treatment plant effluents. Estrogen concentrations in the ng/L range have been well documented in the effluents of sewage treatment plants all over the world. Estrogens are known to cause estrogenic responses in aquatic species, which have been observed in the wild. These observations include abnormalities that diminish the ability of aquatic species to reproduce.Models exist for the fate of estrogens within wastewater treatment plants (Joss et al, 2004; Johnson & Williams, 2004). However, only one model attempts to estimate influent estrogen concentrations at wastewater treatment plants (Johnson & Williams, 2004). The current model tends to under predict influent estrogen concentrations, and does not include any kinetic constants for the biodegradation of estrogens. Accurately predicting the removal of estrogens in wastewater systems depends upon developing a more accurate estimate of wastewater treatment plant influent concentrations. Due to time and cost constraints, influent estrogens are not normally measured as a part of the operational monitoring at wastewater treatment plants. Thus, a comprehensive model for the fate of estrogens within wastewater collection systems requires the determination of the kinetics of estrogen biotransformation during sewer transit.Data was provided by six municipalities throughout Europe and North America to aide in the calculation of the first order kinetic constant for the biotransformation of estradiol (E2) into estrone (E1), kE2; and the kinetic constant for the first order biodegradation of E1, kE1. The mean value calculated for kE2, was 0.030 hr−1 (ranging from −0.080 to 0.49 hr−1) and the mean value calculated for kE1, was −0.18 hr−1(ranging from −0.44 to 0.38 hr−1)