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EVALUATION OF THE REMOVAL OF ESTROGENS THROUGH THE COAGULATION PROCESS
Citation:
SCHENCK, K. M., N. DUGAN, D. WILLIAMS, B. MERRIMAN, L. ROSENBLUM, R. KRISHNAN, AND T. WIESE. EVALUATION OF THE REMOVAL OF ESTROGENS THROUGH THE COAGULATION PROCESS. Presented at Annual Meeting of the Society of Environmental Toxicology and Chemistry (SETAC), Baltimore, MD, November 13 - 17, 2005.
Impact/Purpose:
to present information
Description:
A number of estrogenic compounds have been shown to be present in surface waters in the U.S. These compounds have the potential to act as potent endocrine disrupting chemicals (EDCs), leading to a growing concern over the possible presence of EDCs in finished drinking waters. Consequently, it is prudent to explore if strategies already employed to manage other drinking water risks can also control risks associated with EDCs. Coagulation is a unit process used by the majority of surface water treatment plants in the U.S. Adsorbents such as powdered activated carbon (PAC) are commonly added during coagulation to enhance the removal of organic contaminants. Bench-scale studies (jar tests) were conducted to evaluate the ability of coagulation, with and without PAC, to remove three estrogens (estradiol, ethynylestradiol, and estriol) from Ohio River water. The estrogen to be evaluated was added to the river water prior to treatment with either aluminum sulfate (alum) or ferric chloride, with and without PAC. In order to simulate full-scale treatment practice, the coagulants were added at the lowest concentration necessary to achieve a settled turbidity between 1 and 5 nephelometric turbidity units (NTU). Control jars (no treatment) were sampled at the beginning and the end of treatment and verified the absence of biodegradation during the time course of the coagulation study. Removal of the estrogens was evaluated by comparing the concentrations in the control and treatment jars. The estrogen concentrations were determined analytically using solid phase extraction followed by liquid chromatography/mass spectroscopy. None of the estrogens were removed following coagulation with either alum or ferric chloride. The addition of PAC resulted in removals ranging from approximately 20-80%. Variations in observed removals were due either to variations in water quality, or variations in the molecular weight, charge and hydrophobicity of the tested estrogens. Some of the samples were also assayed in the MVLN assay, an estrogen-responsive reporter gene assay. The results of the MVLN assay were consistent with the analytical results for both the treated and untreated samples, indicating that removal of the estrogens was not due to chemical transformation into an alternate estrogenic compound.