Estrogen reduction in a coupled wetland and ground water flow-through system

Abstract

Hormones, 17β-estradiol (E2) and estrone (E1), have been reported in surface water. Effluent from wastewater treatment plants (WWTPs) serves as a major point source as humans excrete E2 and E1 in urine and feces. WWTPs are not designed to remove the hormones, and elevated concentrations of E1 and E2 have been observed in treated eff luent. Recently, WWTPs have been incorporating wetlands as a tertiary treatment. The project objective was to investigate the reduction of E2 and E1 in treated wastewaters 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. Treated effluent had the highest mean concentrations of E2, 32 ng/L, and E1, 76 ng/L. Wetland waters had slightly lower concentrations of 27 ng/L for E2 and 55 ng/L for E1. Measurable concentrations of E2 were observed only once in five of the 13 wells at a maximum concentration of 18 ng/L, while E1 was observed only in two wells. Higher concentrations of both E2 and E1 were measured in the treated effluent than in the wetlands, indicating that the wetlands are serving as a sink for E2 and E1. The absences of E2 and E1 within the ground water indicate that both are being effectively removed within the groundwater system.