The Behavior Of Typical Sulfanomides In Soil By Groundwater Recharge With Reclaimed Water

China is in great shortage of freshwater. Waste water reuse has become an important strategy for China to solve water inefficiency. Reclaimed water is among one of them.Antibiotics in reclaimed water which is used for recharge has attracted more and more attention. Therefore there is an urgent need for research on migration and transformation of antibiotics in groundwater recharge process, in order to prevent groundwater from pollution and protect groundwater resources, which is of great significance.In this study, two typical sulfanomideswere chosen- sulfamethoxazole(SMZ) and trimethoprim(TMP). Efficient and sensitive detection method of SMZ and TMP was developed. Outdoor sampling was carried out aiming to investigate the concentration and spatial distribution of two antibiotics in reclaimed water recharge site, as well as indoor static experiment, trying to analyze their adsorption, desorption and biodegradation in the sediment, the vadose zone media from the recharge site and reclaimed water. Combining with column test,all those experiments would serve as a scientific basis for the evaluation of the risk in reclaimed water recharge.Through optimized UPLC gradient function, MS conditions and soil extraction methods, the method of simultaneously detecting concentration of SMZ and TMP in soil and reclaimed water was developed, whose detection limits for SMZ and TMP reached 0.4μg/L and 0.3μg/L, respectively.Three sections of Beijing Chaobai reclaimed recharge site were selected to detect the concentration of SMZ and TMP. In the reclaimed water,det ection rates of SMZ and TMP were 100%, the average concentration of SMZ> TMP.In the adsorption and desorption experiments of SMZ and TMP in sediment and vadose zone media, that SMZ and TMP adsorption was much stronger in the sediment than the vadose zone media in the single solution. This was positively correlated with soil content of organic matter. In the dual-solute system, the exigstance of TMP suppressed absorption of SMZ greatly, while the exigstance of SMZ would promote the adsorption of TMP.The degradation of SMZ and TMP in sediment, vadose zone media and reclaimed water were studied. The degradti on of SMZ and TMP in diffferen media well fitted the first-order kinetics. Half life of SMZ and TMP in the non-sterilization group was significantly longger than sterilization group. In the column experiments, the permeation rate was declin ing in the beginning, later it became stable during the reclaimed water recharge. Based on the parameters gained from static and dynamic experiments, an one-dimensional equation was built, finding the predicted breakthrough time for SMZ and TMP was 69 d and 1858 d for column1, respectively, while in the experiment, no detection of SMZ and TMP was found during the 15 d reclaimed water recharge period. The predicted breakthrough time for SMZ and TMP was 0.95 d and 15.3d for column2, respectively, while in the experiment, no detection of TMP and earlier detection of SMZ in 0.5h was found.