Treatment of landfill leachate membrane filtration concentrate by synergistic effect of electrocatalysis and electro-Fenton

Abstract To address the issues caused by the external addition of Fe in the electro-Fenton reaction, activated carbon catalysts loaded with Fe were prepared by an impregnation method with which a novel Fe-activated carbon-titanium mesh composite air cathode (Fe/AC/Ti cathode) was prepared. The preparation conditions were investigated and determined in terms of chemical oxygen demand (COD) removal efficiency of the nanofiltration concentrate of landfill leachate (LLC). An electrochemical system constructed using the Fe/AC/Ti cathode and a dimensional stable anode (DSA) was developed to treat the LLC. The electrochemical reaction conditions were studied by single-factor experiments and orthogonal array analysis. The highest COD removal (97.06 %) was obtained at an applied voltage of 10 V, initial pH of 7, and electrode distance of 1 cm. The optimum conditions were applied voltage of 8 V, initial pH of 3, and electrode distance of 3 cm for 61.24 % total organic carbon removal. BOD5/COD ratios of all tests increased from 0.03 to between 0.23 and 0.51. The effluent after the reaction was either neutral or weakly alkaline. Neither hydrogen peroxide nor Fe ions were added to the reaction system, and almost no Fe precipitation was produced. The system realized the co-treatment of Cl-containing wastewater by anodic electrocatalytic oxidation and cathode electro-Fenton in the same reactor. We also address this common problem in the electro-Fenton reaction utilizing a simple low-cost method with abundant source-material.