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AWWA WQTC65929
- The Impact of Co-contaminants in Septic Effluents on the Transport of Steroid Estrogens through Soil-Water Treatment
- Conference Proceeding by American Water Works Association, 11/01/2007
- Publisher: AWWA
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Measurable levels of endocrine disrupting compounds (EDCs) and pharmaceuticallyactive compounds in environmental waters have been reported in numerous studies and havebeen shown to cause sexual and developmental abnormalities in vertebrate and invertebrateaquatic species at environmentally relevant concentrations. Specifically, compounds such assteroid hormones and nonionic surfactant metabolites (nonylphenols) are of particular interestbecause of their prevalence, their high level of potency at low concentrations, their ubiquitouspresence in wastewater, and their potentially harmful effects on the environment. Although afew studies indicate that some of these EDCs could be partially removed or transformed duringseptic treatment, we have found the steroid hormones estrone and estradiol at nearly 250 ng/L inmain tank septic effluent and nonylphenols at nearly 300 µg/L, as measured by gaschromatography with mass spectrometry. These highly estrogenic compounds are then releasedwith the bulk effluent into the environment to percolate through soils into groundwater or, insome cases, are directly discharged into receiving surface waters. This study has isolated severalvariables that may impact the partitioning and transport of steroid estrogens and nonylphenolsbetween soil and aqueous phases through intensive batch and column studies. It washypothesized that the relatively high concentration of nonionic surfactants and their metabolitesdischarged from septic systems would impact the soil-water equilibrium of steroid estrogens,allowing them to spend more time in the aqueous phase and thereby increasing their rate oftransport towards groundwater. Though these co-contaminants appear to have some effect, theoverall quality of the final effluent (organic matter, turbidity, etc.) appears to be more of adetermining factor in overall transport. Results are presented from batch and column studiesthat investigated transport behavior with three soil types and several co-contaminant and septiceffluent combinations. Includes 25 references, figures.