ESTROGEN REDUCTION IN A COUPLED WETLAND AND GROUND WATER FLOW-THROUGH SYSTEM

In the last decade, the presence of endocrine-disrupting compounds (EDCs) has been reported in surface water, spring water, and overland flow systems. The most potent EDCs released into the aquatic system are steroid hormones, specifically 17b-estradiol (E2), which can be transformed to estrone (E1). Negative effects of E2 on fish, testicular abnormalities, feminization of male fish, and reduced spawning, have been documented at surface water concentrations below 10 ng/L. Effluent from wastewater treatment plants (WWTPs) serves as a major point source for hormones as humans excrete E2 and E1 in urine and in feces. Conventional WWTPs are not designed to remove either E2 or E1; consequently, concentrations of E2 and E1 as high as 55 ng/L and 180 ng/L, respectively, have been observed in treated effluent. Although not a focal point of treatment processes, removal of E2 and E1 via primary and secondary treatment has been documented. In addition to traditional primary and secondary treatment, WWTPs have been incorporating wetlands as a tertiary treatment, which have been documented to decrease the concentrations E2 up to 27%. The objective of this pilot project was to investigate the reduction of 17b-estradiol (E2) and estrone (E1) in treated wastewaters that were subjected to a tertiary treatment composed of a coupled wetland and ground water flow through system. E2 and E1 were measured in the treated effluent entering the wetland, the wetland waters, and in the ground water downgradient of the wetlands. Concentrations of E2 ranged from below detectable level (BDL) to 60 ng/L, and E1 concentrations measured from BDL to 178 ng/L of E2. Treated effluent had an average E2 and E1 concentrations of 20 ng/L and 76 ng/L, while the wetland had an average of 17 ng/L and 55 ng/L. E2 was observed in only 6 of the 13 wells, with concentrations below 17 ng/L. E1 was observed in only one well at a concentration of 58 ng/L. Higher concentrations of both E2 and E1 in the treated effluent than in the wetlands indicate that the wetlands are serving as a sink for E2 and E1. The absences of E2 and E1 within the ground water suggest that both are being effectively removed within the ground water system.