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

Abstract 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 Fe 2+ would activate the added H 2 O 2 to produce hydroxyl radical ( OH), which is a strong oxidant and can lead to the removal of COD from landfill leachate. The effect of initial pH, H 2 O 2 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 H 2 O 2 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.