INDIRECT OXIDATION EFFECT IN ELECTROCHEMICAL OXIDATION TREATMENT OF LANDFILL LEACHATE

Treatment of a low BOD/COD ratio landfill leachate was conducted by me ans of electrochemical oxidation process in this investigation. Under the operating conditions of 15 A/dm(2) current density and 7500 mg/l a dditional chloride concentration, 92% of the COD in the landfall leach ate was removed after electrolysis for 240 min with a ternary Sn-Pd-Ru oxide-coated titanium (SPR) anode. At the same time, about 2600 mg/l of ammonium in the landfill leachate was also removed completely. Thes e results indicate that the electrochemical oxidation process is effec tive in removing pollutants from landfill leachate. In this investigat ion, the effects of operating parameters including anode material, cur rent density, and chloride concentration on both chlorine/hypochlorite production and landfill leachate treatment efficiency were studied. I t was found that the operating factors have the same effects on both c hlorine/hypochlorite production efficiency and landfill leachate treat ment efficiency. The results suggest that the removal of pollutants fr om landfill leachate by electrochemical oxidation process could be mai nly attributed to the indirect oxidation effect of chlorine/hypochlori te produced during the electrolysis. Among the four anode materials in vestigated in this study, including graphite, PbO2/Ti, DSA(R), and SPR anodes, the SPR anode having a high electrocatalytic activity gave th e best chlorine/hypochlorite production efficiency and landfill leacha te treatment efficiency. In addition, the increases in both operating current density and chloride concentration also enhanced the indirect oxidation effect in the electrochemical oxidation treatment of landfil l leachate.