Numerical modeling and performance evaluation of passive convergence-permeable reactive barrier(PC-PRB)

The passive convergence-permeable reactive barrier(PC-PRB)was proposed to address the limitations of traditional PRB configurations.To evaluate the hydraulic and pollutant removal performance of the PC-PRB system,we developed a simulation code named PRB-Trans.This code uses the two-dimensional(2D)finite element method to simulate groundwater flow and solute transport.Case studies demonstrate that PC-PRB technology is more efficient and cost-effective than continuous permeable reactive barrier(C-PRB)in treating the same contaminated plume.Implementation of PC-PRB technology results in a 33.3%and 72.7%reduction in PRB length(L_(PRB))and height(H_(PRB)),respectively,while increasing 2D horizontal and 2D vertical pollutant treatment efficiencies of PRB by 87.8%and 266.8%,respectively.In addition,the PC-PRB technology has the ability to homogenize the pollutant concentration and pollutant flux through the PRB system,which can mitigate the problems arising from uneven distribution of pollutants in the C-PRB to some extent.The L_(PRB)required for PC-PRB decreases as the water pipe length(L_(p))increases,while the H_(PRB)required initially decreases and then increases with increasing L_(p).The effect of passive well height(Hw)on H_(PRB)is not as significant as that of L_(p)on H_(PRB).Overall,PC-PRB presents a promising and advantageous PRB configuration in the effective treatment of various types of contaminated plumes.