Co2 and Oxidants Method for in Situ Regeneration of Permeable Reactive Barriers for Leachate–Contaminated Groundwater

Groundwater contamination near landfills is commonly caused by leachate leakage, permeable reactive barriers (PRBs) are widely used for groundwater remediation, however, the deactivation and blockage of the reactive medium in PRBs limit their long-term effectiveness. In the current study, a new methodology was proposed for the in situ regeneration of PRB to remediate leachate-contaminated groundwater. CO2 coupled with oxidants was applied for the dispersion and regeneration of the fillers, by injecting CO2 to disperse the fillers, the permeability of the PRB was increased and the oxidants could flow evenly into the PRB. The results indicate that the optimum filler proportion was ZVI/zeolites/AC = 3:8:10, and the optimum oxidant proportion was COD/Na2S2O8/H2O2/Fe2+ = 1:5:6:5; the oxidation system of Fe2+/H2O2/S2O82- has a high oxidation efficiency and persistence. The average regeneration rate of zeolites was 72.71%, and the average regeneration rate of AC was 68.40%. The permeability of PRB increased from 67.74 m/d to 72.9 m/d. The present study could improve the activity and permeability of the reactive medium in the PRB simultaneously, which guarantees the long-term and stable performance of the PRB