Coupling ARB-based biological and photochemical (UV/TiO2 and UV/S2O82−) techniques to deal with sanitary landfill leachate

•Coupling ARB and AOPs successfully treated mature MSW landfill leachate.•The ARB-based pretreatment removed an average 72% COD, 81% NH4N and 92% TN.•A mean 82 & 81% COD removed at optimum 1 g L−1 TiO2 & 1.5 g L−1 S2O8−2, respectively.•UV/persulfate oxidation abated a mean 90% NH4N at pH 9 under diffused aeration.•Acidic and alkaline pH favored COD and NH4N removal, respectively.

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 (TiO2/UV) and persulfate (S2O82−) oxidation were tested. The results obtained after ARB based pre-treatment demonstrated a mean 72%, 81% and 92% degradation of COD, NH4N and TN, respectively. However, this treated leachate cannot be discharged without another treatment; hence, it was further treated by UV-mediated TiO2 photocatalysis and S2O82− oxidation. An average 82% of COD was abated at optimum condition (1 g L−1 TiO2; 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 NH4N 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.

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