Estrogen degradation and sorption onto colloids in a constructed wetland with different hydraulic retention times

Endocrine disrupting compounds are a global concern, owing to their interference with the endocrine system of wildlife. In particular, natural estrogens at concentrations as low as ng/L level can interrupt the endocrine system of many organisms. A constructed wetland is an effective means of removing the residual levels of estrogen. This study investigates the estrogen degradation and sorption on colloids in a constructed wetland at hydraulic retention times (HRTs) of 27.5, 45.9, and 137.5 h. Three natural estrogens (i.e. estrone (E1), 17β-estradiol (E2), and estriol (E3)) are analyzed with liquid chromatography/tandem mass spectrometry. At HRT = 27.5 h, no degradation occurs; at HRT = 45.9 h, the degradation rates are 0-46.2%; and at HRT = 137.5 h, the degradation rates are 40-84.3%. Additionally, estrogen sorption coefficients (log KCOC values) range from 3.37 to 4.89. Average log KCOC values are 4.08 ± 0.33, 4.04 ± 0.34, and 4.11 ± 0.28 for E1, E2, and E3, respectively. At different HRTs, values of log KCOC increase with an increasing HRT. Analytical results indicate that constructed wetlands can remove residual natural estrogens. With an increasing HRT, the estrogen degradation rate increases as well as the estrogen sorption on colloids.