Degradation of landfill leachate compounds by persulfate for groundwater remediation

In this study, batch and column experiments were conducted to evaluate the feasibility of using persulfate oxidation to treat groundwater contaminated by landfill leachate (CGW). In batch experiments, persulfate was compared with H₂O₂ and permanganate for oxidation of organic compounds in CGW. Complementary experiments were conducted to evaluate biodegradation (natural attenuation) potential for the system. Persulfate was observed to be superior to H₂O₂ and permanganate for degradation of total organic carbon (TOC) in the CGW. Conversely, biodegradation caused only partial removal of TOC in CGW. In contrast, persulfate caused complete degradation of the TOC in the CGW or aged CGW, showing no selectivity to the contaminants. Magnetite (Fe₃O₄) enhanced degradation of leachate compounds in both CGW and aged CGW with limited increase in persulfate consumption and sulfate production. Under dynamic flow condition in 1-D column experiment, both biodegradation and persulfate oxidation of TOC were enhanced by Fe₃O₄. The enhancement, however, was significantly greater for persulfate oxidation. In both batch and column experiments, Fe₃O₄ by itself caused minimal consumption of persulfate and production of sulfate, indicating that magnetite is a good persulfate activator for treating CGW in heterogeneous systems The results of the study show that the persulfate-based in-situ chemical oxidation (ISCO) method has great potential to treat the groundwater contaminated by landfill leachate.