Degradation of Landfill Leachate by Electro-Heterogeneous Catalytic Reactor

Abstract

Using granular activated carbon (GAC) as electric particle electrode and heterogeneous catalyst loaded metal oxide to replace insulated particle in bipolar packing bed cell (BPBC), the electro-heterogeneous catalytic oxidation system was constructed. Adopting impregnation method to prepare γ-Al2O3 supported catalysts containing Cu and Ce, it was evenly mixed with GAC to construct packing materials. Using stainless steel as anode, porous graphite as cathode and packing materials between them, landfill leachate was treated by an electro-catalytic oxidation process and COD removal efficiency was studied. The activity of catalysts was explored, and using scanning electron microscope (SEM) and X-ray diffraction (XRD), the microstructure and morphology were characterized. The operating parameters such as cell voltage, initial pH, airflow and inter-electrode distance were also investigated. The results showed that when the metal ion concentration in soaking solution was 2% for Cu, 9% for Ce, the activity of prepared catalyst was the highest. Under the conditions of an applied voltage of 15.0 V, pH of 7.0, airflow of 0.08 m3/h, and an inter-electrode distance of 3.0 cm, the removal efficiencies of COD reached 92.9%. Qualitative analysis of the interim products was carried out, adopting ultraviolet-visible spectrum, and the mechanism of electro-heterogeneous catalytic oxidation reaction was discussed. The whole degradation involves two main processes: electro-oxidation and electro-coagulation.