Advanced treatment of aged landfill leachate through the combination of aged-refuse bioreactor and three-dimensional electrode electro-Fenton process.

A combined process of the aged-refuse bioreactor (ARB)/three-dimensional electrode electro-Fenton (3D-EF) system was developed at lab-scale to treat aged landfill leachate. The optimum operating conditions were found to be 15 L/m3•d hydraulic loading rate for ARB; Fe2+ concentration 1.0 mM, initial pH 3.0, current density 30 mA/cm2 and electrode distance 6 cm for 3D-EF. Under these conditions, the total removal ratios of chemical oxygen demand, NH3-N, total phosphorus and colour were 96.2%, 94.3%, 99.2% and 93.6%, respectively. The microtoxicity of the leachate was substantially reduced after undergoing the hybrid treatment. The ARB process removed a considerable proportion of organic matter, while the 3D-EF system played an important role in removing the residue of recalcitrant substances and post-polish of final effluent. The combined process showed a promising potential for treatment of aged landfill leachate.