In Situ Chemical Oxidation Of Landfill Leachate Contaminated Groundwater By Persulfate

With the rapid development of the city,the total amount of waste and the types of pollutants are increasing and the pollution of landfill leachate to groundwater is becoming more and more serious.At present,the in-situ chemical oxidation of persulfate has a broad application prospect in remediation of organic compounds contaminated soil and groundwater.Based on the extensive literature,in this study,batch and column experiments were conducted to evaluate the feasibility of using persulfate oxidation method to treat landfill leachate contaminated groundwater(CGW).And the total organic carbon(TOC)was measured to characterize the leachate compounds of CGW.Comparison between oxidants for degradation of leachate TOC in batch experiment,persulfate was superior to hydrogen peroxide(H2O2)and permanganate(KMnO4)for the degradation of leachate compounds,which is demonstrated by the observation that the degradation rate of TOC in CGW was significantly higher with persulfate as the oxidant.Biodegradation could cause a degradation rate comparable to that for persulfate oxidation,however,it could not achieve complete TOC removal due to presence of refractory compounds in CGW.In contrast,the degradation of the contaminants by persulfate was complete,showing that the persulfate oxidation reaction has no selectivity to pollutants and is not restricted by the organic species.The presence of magnetite(Fe3O4)enhanced persulfate oxidation and increased the degradation rate of the leachate compounds in both young and aged leachate CGW with limited enhancement in persulfate consumption,indicating that magnetite can be used as a good material to activate persulfate for treating CGW in heterogeneous systems.In the sand column experiments,both biodegradation and persulfate oxidation were enhanced in the presence of the magnetite for degradation of organic pollutants in CGW indicated by lower TOC level at the plateau of breakthrough curves.The enhancement,however,was greater for persulfate oxidation.The refractory compounds still could not be biodegraded in column system.The results show that the persulfate-based in-situ chemical oxidation(ISCO)method has great potential to treat the groundwater contaminated by landfill leachate.