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EVALUATION OF THE REMOVAL OF ESTROGENS THROUGH THE COAGULATION PROCESS - PAPER
Citation:
WILLIAMS, D., K. M. SCHENCK, N. DUGAN, B. MERRIMAN, AND L. ROSENBLUM. EVALUATION OF THE REMOVAL OF ESTROGENS THROUGH THE COAGULATION PROCESS - PAPER. In Proceedings, AWWA Annual Conference and Exposition, San Antonio, TX, June 11 - 15, 2006. American Water Works Association, Denver, CO, -, (2006).
Impact/Purpose:
to provide 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. onsequently, 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) and oxidants such as chlorine 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, alone and in combination with PAC or chlorine, 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. In order to simulate full-scale treatment practice, the coagulants (alum or ferric chloride) were added at the lowest concentration necessary to achieve a settled turbidity between 1 and 5 nephelometric turbidity units (NTU). 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 estrogen removals following coagulation with either alum or ferric chloride were significantly different from zero. The addition of PAC resulted in removals ranging from approximately 20 to 80 percent. Variations in observed removals were due either to variations in water quality, and/or variations in the molecular weight, charge and hydrophobicity of the tested estrogens. Treatment of the estrogens with chlorine, either alone or with coagulant, resulted in removals of approximately 98 percent. This removal is due, at least in part, to chemical transformation of the estrogens.
