The Removal Of Typical EDCs In Reclaimed Water By Artificial Composite Soil Treatment System

Wastewater reclamation and reuse is an efficient way to solve water shortage problems in China. As the widespread use and their own persistent and cumulative, the micro-organic-pollutants have certain concentrations of detection in reclaimed water and even in groundwater, and could do harm to human health and the environment at very low concentrations. Artificial composite soil treatment system is able to remove pollutants from the wastewater, through the physical, chemical, or biological interactions between the filter materials and the contaminants. It has good removal on these micro-organic-pollutants, with less investment, low operating costs and simple operation advantages. This study structured an artificial composite soil treatment system, which had a stable and better removal of typical EDCs.A nation-wide survey of the pollution conditions of EDCs during the groundwater recharge process was conducted across China. The result showed that natural vadose zone had a limited removal of EDCs and these micro-organic-pollutants in reclaimed water could contami nate groundwater by spreading into aquifers for a long time.This study collected groundwater at depths of 30, 50 and 80 m, where reclaimed water was used to recharge groundwater through the permeable bed. The result showed that EDCs easily access ed the aquifers. The concentrations of EDCs in the 30, 50 and 80 meters gradually decreased by orders of magnitude. Theoccurrences and concentrations of EDCs in groundwater decreased with the increasing distance to the river bank.This paper selected two typical EDCs: 17α-Ethinyl Estradiol(EE2) and Bisphenol A(BPA). Studies have shown double-room first order kinetics can simulate the adsorption process of EE2 and BPA on soil and media fillers better. The adsorption isotherm indicated that the order of the adsorpti on capacity of EE2 on 4 selected media fillers was: volcanic > clay ceramisite ≈ shale ceramisite > zeolite; the adsorption capacity of BPA is: volcanic ≈ clay ceramisite > shale ceramisite > zeolite. Considering its physical properties such as compressive strength and appearance, clay ceramisite was selected as the filler of adsorption layer in the artificial composite soil treatment system.The biodegradations of EE2 and BPA in soil were well fitted with the first order kinetics. The degradation rates of EE2 and BPA at 4℃ were lower than that at 23℃. Temperature had a more significant effect on the degradation rate of BPA than that of EE2. After long term culture, the degradation rates of EE2 and BPA were improved because of the addition of gl ucose as carbon source.In this study, two kinds of artificial composite soil treatment system were structured with river sand, soil and zeolite. Column study showed that during the recharging by recycled water without spiked EDCs, both of the two artificial composite soil treatment system shad a good removal of EE2 and BPA. After 15 d, the removal rate of BPA was 99.56%in column 1 and it was 97.98% in column 2. After recharging by recycled water with 10 μg L-1 EE2 and BPA, it was found that the removal rate of EE2 was above 97.47% and that of BPA was above 92.93%. However, the removal rate of high concentration of EE2 and BPA in column 2 wassignificantly lower than that in column 1. After a long recharge, the concentrations of EE2 and BPA along the way of co lumn 2 were significantly increased.