Study On The Fate Of Endocrine Disrupting Chemicals BPA And Steroids In The Land Treatment System

Bisphenol A (BPA) and hormone (E1,E2,EE2,E3) which widely existed in wastewater threat the environment by independent or synergistic effect. Wastewater land treatment system was a suitable technology which would be popularized in areas of non-point source pollution, and its effect in removing bisphenol A and steroid treatment was an environmental problem worthy of study.Five typical EDCs including bisphenol A, estrone, 17β-estradiol, 17α-ethynylestradiol, and estriol were selected as the target compounds. Solid phase extraction (SPE) and gas chromatography (GC) coupled with mass spectra (MS) analysis was applied to detect the concentration of EDCs.First, adsorption isotherms and adsorption kinetics of endocrine disrupting chemicals on soils were studied. The sorption experiments of endocrine disrupting chemicals bisphenol A (BPA) and hormone (E1,E2,EE2,E3) on two soils with different physicochemical properties were conducted using batch equilibrium methods, effects of temperature and ion strength on sorption were also investigated. The results show that a fast adsorption and slow balance take place in the adsorption process, and the sorption behaviors of selected EDCs on soils may be well described by Freundlich model. The adsorption of BPA and steroids on the tested soils is an exothermic process, the adsorption capacity of BPA and steroids on soils decreases as temperature rises and increases with water ionic strength or soil organic matter increasing.Secondly, based on small-scale wastewater land treatment system - soil purification trough technology, five wastewater land treatment systems were established. Different hydraulic loading were controled, monitoring conventional pollutants and endocrine disrupting chemicals removal situation. The results showed the equipments had good performance in removing conventional pollutants and endocrine disrupting chemicals. The removal efficiency of COD, P, NH4+ increased at first and reached equilibrium in 30-40days. The removal efficiency of EDCs kept relatively high, and reached more than 70% when it reached equilibrium. The removal efficiency of both conventional pollutants and endocrine disrupting chemicals increased as the hydraulic loading increase.For further study, the soil organic matter and the concentration of EDCs remained were analysed to find the ratio between adsorption and biodegradation. It showed that in the land system, there was little concentration difference in soils of different depth and different load, which meant that the vertical transference of EDCs in soil was relatively slow. The main removal pathway of EDCs in land system was biodegradation. After a three-month run, the remain rate was only 10-7 of the total removal amount. The biodegradation rate of BPA,E1,E2,EE2,E3 were 1150.9μg/(g Soil·d),1812.2μg/(g Soil·d),608.7μg/(g Soil·d),1563.5μg/(g Soil·d),763.1μg/(g Soil·d).