A feasibility study on the remediation of complex contaminated groundwater in landfill sites using advanced oxidation-permeable reactive barrier(PRB)approach
A feasibility study on the remediation of complex contaminated groundwater in landfill sites using advanced oxidation-permeable reactive barrier(PRB)approach
The complex contamination of COD,NH4+,and Mn2+in the groundwater of a landfill site in Hangzhou was investigated in this study.A combination of heterogeneous Fenton oxidation and a permeable reactive barrier(PRB)was applied.Three different catalytic oxidation catalyst combinations—activated carbon(AC),biochar(BC),and BC+Fe3O4—were designed and used as active filling materials in the oxidation layer of the PRB,followed by a downstream zeolite adsorption layer.Results from batch and column tests showed that 47％of COD was directly pre-oxidized by H2O2.COD in the oxidation layer was reduced through the combined effects of catalytic oxidation and adsorption.The transport of Mn2+was influenced by the ash content released from porous carbon materials,resulting in initial precipitation followed by dissolution and subsequent adsorption.Functional groups on the surfaces of AC and BC,such as-OH and-COOH,were involved in the reaction.In the adsorption layer,NH4+and Mn2+were exchanged with zeolite ions,leading to changes in the zeolite framework structure.The functional groups-NH and-OH on the zeolite surface were also involved in thorough adsorption.The series combination of the BC+Fe3O4 oxidation layer and the zeolite adsorption layer,with a length ratio of 1∶3,was found to exhibit higher removal rates for all three contaminants,the latest PRB breakthrough time(i.e.,when the effluent concentration was reduced to 10％of the influent concentration and exceeded the limit),and the highest utilization efficiency at breakthrough,making it the optimal process.
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