Sensitivity Analysis And Design Of Influencing Factors Of Nitrate Nitrogen PRB Remediation Based On Groundwater Numerical Simulation

The advantages of permeable reactive barrier?PRB?in in-situ groundwater remediation technology are obvious.PRB design research is becoming more and more perfect,but there is still a lack of sensitivity research on the influencing factors of PRB remediation effects.This article is based on the background of the nitrate nitrogen pollution of shallow groundwater in Fuyang City.By analyzing the geological environment data in the study area,the groundwater chemical characteristics and nitrogen pollution in the study area is described in four aspects:chemical main component of shallow groundwater,hydrochemical type,hydrochemical spatial distribution and water quality evaluation.The migration simulation of groundwater nitrate nitrogen pollution was carried out,and the spatial distribution characteristics and migration trend of nitrogen pollution were analyzed.Based on the PRB design,the Morris global sensitivity analysis method was employed to carry out the sensitivity study of the influencing factors,and the sensitivity research results were used to improve the design of PRB.Main conclusions are as follows:?1?The water quality grade is mainly class?in the dry season,and mainly grade?in the flood season.The concentration of inorganic nitrogen in groundwater is increasing year by year.?2?Morris sensitivity analysis was performed on the sensitive factors,which are hydraulic gradient I,PRB length L,PRB width W,distance from pollution source Dist.,pollution discharge rate DR and recharge concentration RC,PRB material permeability coefficient K_PRB,maximum adsorption capacity/Langmuir constant of PRB material Q_max/K_L,of the removal effect and the order of sensitivity from high to low was obtained.In the permeability homogeneous medium,removal efficiency is sensitive,form high to low,to I,W,DR,RC,L,Dist.,Q_max/K_L,K_PRB;capture width to L,I,DR,W,Dist.,K_PRB,RC,Q_max/K_L;residence time to W,I,DR,K_PRB,Dist.,L,Q_max/K_L,RC.In the permeability heterogeneous medium,removal efficiency is sensitive,form high to low,to Q_max/K_L,W,I,DR,L,K_PRB,RC,Dist.;capture width to L,Dist.,I,DR,K_PRB,W,RC,Q_max/K_L;residence time to W,I,Dist.,DR,K_PRB,L,RC,Qmax/KL.?3?In the process of implementing Morris increments,the trends of the removal rate, capture width and residence time of permeability homogeneous and heterogeneous media are generally consistent.The removal rate in permeability heterogeneous media is generally lower than that in permeability homogeneous media.The capture width in permeability heterogeneous media is generally higher than that in permeability homogeneous media.The residence time in permeability heterogeneous media is generally lower than in permeability homogeneous media.