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Evaluation of Drinking Water Treatment Technologies
Project Purpose:
The purpose of this project is to provide information necessary for the selection of drinking water treatment techniques that provide for optimal EDC removal and subsequently reduce human exposure to EDCs. In order to be able to evaluate the ability of conventional and advanced drinking water treatment processes to remove EDCs, appropriate analytical methods for the selected EDCs in several water matrices must be available or developed. Additionally, the applicability of bioassay(s) to evaluate the removal/presence of compounds with endocrine activity in water samples pre- and post-treatment will be evaluated.
Project Description(s):
This project investigates the efficacy of various drinking water treatment processes in removing EDCs from source waters. The project has three components. The first is the development of appropriate analytical methods for the EDCs being evaluated. Initially, a set of steroid hormones are being studied, followed by a group of alkylphenolic compounds. The second component is the application of a reporter gene assay, the MVLN assay, to evaluate the presence of estrogenic activity in water samples. The third part of the study is to conduct bench-scale experiments to evaluate the removal of EDCs by drinking water treatment processes.
The analytical method for the selected steroids has been developed and the method for the alkylphenols is currently being developed. Bench-scale studies are being conducted to evaluate the removal of steroid hormones by coagulation and granular activated carbon (GAC) adsorption. Jar tests have been conducted to evaluate the ability of coagulation, alone and in combination with powdered activated carbon (PAC) or chlorine, to remove three estrogens from Ohio River water. None of the estrogen removals following coagulation were significantly different from zero. The addition of PAC resulted in removals ranging from approximately 20 to 80 percent. Treatment of the estrogens with chlorine resulted in removals of approximately 98 percent. However, this removal is due, at least in part, to chemical transformation of the estrogens. GAC isotherm studies, using ethynylestradiol and three types of GAC, indicate that the steroids will be strongly adsorbed. However, the isotherm studies required long equilibrium times which suggest that the rate of adsorption was very slow. To further investigate the GAC adsorption kinetics, GAC column studies are currently being conducted. The results of the MVLN assay have been consistent with the analytical results for the isotherm samples, as would be expected following adsorption onto GAC.
Project Outcomes:
This ongoing research will provide information on the ability of various drinking water treatment technologies to remove EDCs that may be present in source waters. The initial phase of this work, the determination of the treatability of reproductive hormones, was conducted at the request of the Office of Ground Water and Drinking Water (OGWDW). The results of this research will be used by OGWDW, the states and municipalities, and drinking water utilities for selecting optimal EDC removal processes and subsequently reducing human exposures to EDCs.
Contact
Kathleen Schenck at schenck.kathleen@epa.gov