Removal of COD from landfill leachate by advanced Fenton process combined with electrolysis

Zero valent iron (ZVI) was used as the iron source for the advanced Fenton treatment of landfill leachate in an electrochemical cell. In this process, Fe-0 was dissolved from the surface of ZVI powder and then the generated Fe2+ would activate the added H2O2 to produce hydroxyl radical ((OH)-O-center dot), which is a strong oxidant and can lead to the removal of COD from landfill leachate. The effect of initial pH, H2O2 dosage, Fe-0 dosage, current density and inter-electrode gap on the COD removal of landfill leachate was investigated. The results indicate that COD removal followed pseudo-second order kinetic model. The rate constant and efficiency of COD removal increased with Fe-0 dosage being increased from 0.524 to 1.745 g/L, but decreased when initial pH rose from 2 to 4. The optimal conditions of H2O2 dosage, current density and inter-electrode gap were determined to be 0.187 mol/L, 20.6 mA/cm(2) and 1.8 cm, respectively. The humic acid-like organics in the leachate were effectively degraded and over 70% of COD could be removed from the leachate, showing high efficiency of the electro-advanced Fenton process.