The fate of estrogenic hormones in an engineered treatment wetland with dense macrophytes

Recently, the estrogenic hormones 17beta-estradiol (E-2) and 17alpha-ethinyl estradiol (EE2) have been detected in municipal wastewater effluent and surface waters at concentrations sufficient to cause feminization of mate fish. To evaluate the fate of steroid hormones in an engineered treatment wetland, lithium chloride, E-2, and EE2 were added to a treatment wetland test cell. Comparison of hormone and tracer data indicated that 36 % of the E-2 and 41 % of the EE2 were removed during the cell's 84-h hydraulic retention time (HRT). The observed attenuation was most likely the result of sorption to hydrophobic surfaces in the wetland coupled with biotransformation. Sorption was indicated by the retardation of the hormones relative to the conservative tracer. Biotransformation was indicated by elevated concentrations of the E-2 metabolite, estrone. It may be possible to improve the removal efficiency by increasing the HRT or the density of plant materials.