Biodegradation of Endocrine Disrupting Compounds by Ammonia Oxidizing BacteriaEPA Grant Number: F07A20018
Title: Biodegradation of Endocrine Disrupting Compounds by Ammonia Oxidizing Bacteria
Investigators: Gaulke, Linda S.
Institution: University of Washington
EPA Project Officer: Michaud, Jayne
Project Period: September 1, 2007 through August 31, 2010
RFA: STAR Graduate Fellowships (2007) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Environmental Engineering , Endocrine Disruptors
The environmental impacts of endocrine disrupting compounds (EDC) released into the environment are a global concern due to their abilities to have an effect on aquatic life at concentrations as low as 1 ng/L. Wastewater treatment facility (WWTF) effluents have been identified as a primary route for EDC to enter the environment, with the bulk of their EDC activity resulting from estrogenic compounds. Preliminary research suggests that ammonia oxidizing bacteria (AOB) in WWTF are able to cometabolically degrade these compounds. However, information is not yet known about how much estrogen degradation occurs by AOB in WWTFs, about the kinetics of estrogen degradation, estrogenic activity of degradation byproducts, and what design and operating conditions promote maximum estrogen degradation. This research is designed to investigate fundamental mechanisms of microbial degradation that could be applied toward enhanced biodegradation of estrogens in WWTF to provide an economical method of reducing EDC in the environment.
The experimental approach will employ the following four overarching and interrelated components: 1. determination of estrogen degradation kinetics; 2. verification of kinetics among AOB found in WWTF; 3. determination of estrogenic activity of degradation products; and 4. use of a kinetic model to evaluate AS designs. Batch tests will be conducted with AOB representative of those found at WWTF to determine the effects of estrogen on ammonia oxidizing kinetics, ammonia on estrogen degradation, multiple estrogens, and trace concentrations of estrogens. The estrogenic activities of estrogen degradation products will be evaluated using the yeast estrogen screen (YES) and correlated with degradation of estrogens quantified by LC-MS-MS. Kinetics information obtained from pure cultures will be validated with activated sludge (AS) field samples, employing molecular methods to confirm AOB populations. Kinetics will be used in simulation modeling software to evaluate WWTF reactor designs and configurations that achieve enhanced estrogen degradation.
This study will provide a fundamental understanding of mechanisms of estrogen degradation by AOB and their relative impact for estrogen removal in WWTFs, establish estrogenic activities of metabolic byproducts as determined by the YES, further scientific knowledge of AOB populations in WWTF, evaluate the validity of using AOB kinetics for modeling estrogen removal in AS and identify WWTF configurations which are able to achieve enhanced estrogen degradation by AOB.