Coupling ARB-based biological and photochemical (UV/TiO2 and UV/S2O8(2-)) techniques to deal with sanitary landfill leachate.

Abstract The aim of this study was to provide an alternative way to remove bio-refractory organics and ammonical-nitrogen from mature municipal solid waste (MSW) landfill leachate by combining biological and photochemical processes. To achieve this objective, the effectiveness of anoxic aged refuse-based bioreactor (ARB) for biological leachate pretreatment followed by Advanced Oxidation Processes (AOPs) by heterogeneous photocatalysis (TiO 2 /UV) and persulfate (S 2 O 8 2− ) oxidation were tested. The results obtained after ARB based pre-treatment demonstrated a mean 72%, 81% and 92% degradation of COD, NH 4 N and TN, respectively. However, this treated leachate cannot be discharged without another treatment; hence, it was further treated by UV-mediated TiO 2 photocatalysis and S 2 O 8 2− oxidation. An average 82% of COD was abated at optimum condition (1 g L −1 TiO 2 ; pH 5) whereas, using an optimum 1.5 g L −1 persulfate at pH 5, 81% COD reduction occurred. Acidic and alkaline pH favored COD and NH 4 N removal respectively. The results of this study demonstrated that coupling ARB with AOPs is potentially applicable process to deal with bio-recalcitrant compounds present in mature landfill leachate.