Study On Removal Of Nitrogen From Groundwater By Loofah Sponge Solid Carbon As Simulate Permeable Reactive Barrier Media

With the rapid development of social industry and economy,China’s water environment has been seriously polluted,especially the problem of nitrate pollution in groundwater.In the technology of repairing groundwater nitrate pollution,Permeable Reactive Barrier(PRB)The utility model has the advantages of simple operation,low operating cost and small environmental disturbance,and gradually becomes a repairing technology with application prospects.Therefore,in this study,the solid carbon source loofah was used as the PRB filling medium,and the simulated PRB was used to remove the nitrate in groundwater.The effects of hydraulic retention time and influent nitrogen load on the denitrification effect of simulated PRB were investigated,and the effluent method and filling were studied.The effect of the method on the effluent quality of the simulated PRB system,and the mechanism of the simulated PRB denitrification and the microbial community structure of the loofah surface biofilm were investigated by means of SEM and high-throughput sequencing.The following conclusions were obtained:(1)Comparison of different pretreatment methods showed that NaOH pretreatment can not only reduce the release of nitrogen in loofah material,but also improve denitrification and denitrification;1.5% NaOH pretreatment of loofah is the most suitable as Denitrifying carbon source.(2)The results of simulated PRB test showed that compared with the original loofah,the loofah was pretreated with 1.5% NaOH as the simulated PRB filling medium,and the average TN removal rate could be increased by 5.15%-10.9%;whether the inoculated domesticated sludge was used to simulate the PRB The nitrogen effect has little effect.(3)The hydraulic retention time and influent nitrogen load have obvious effects on the denitrification effect of simulated PRB.Among them,when HRT is between 48 h and 36 h,the denitrification is more thorough,and the TN removal rate is between 94.37% and 97.95%.When the water nitrate nitrogen concentration was 40,80,120 and 20 mg/L,the average TN removal rates were 97.29%,73.69%,65.81% and 94.19%,respectively,indicating that loofah has long-term carbon release capacity.(4)The results of simulated PRB optimization test show that the effluent mode has little effect on the final effluent quality of the simulated PRB,and the filling method has a great influence on the final effluent quality of the simulated PRB.In order to ensure good effluent quality,in the actual engineering application,the direct effluent method and the sand filling method can be selected.Through the above experimental research,it is indicated that loofah is suitable as a filling medium for simulating permeable reactive wall.This study provides a new idea for the recovery of nitrate-contaminated groundwater and agricultural solid waste.