Coupling ARB-based biological and photochemical (UV/TiO and UV/SO) techniques to deal with sanitary landfill leachate.

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/UV) and persulfate (SO) oxidation were tested. The results obtained after ARB based pre-treatment demonstrated a mean 72%, 81% and 92% degradation of COD, NHN and TN, respectively. However, this treated leachate cannot be discharged without another treatment; hence, it was further treated by UV-mediated TiO photocatalysis and SO oxidation. An average 82% of COD was abated at optimum condition (1gL TiO; pH 5) whereas, using an optimum 1.5gL persulfate at pH 5, 81% COD reduction occurred. Acidic and alkaline pH favored COD and NHN 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.