In this book the treatment of landfill leachate by ozonation process was investigated. For this purpose, the ozonation experiments were carried out at high pH on the effluent of pretreated with lime. The chemical oxygen demand removal efficiencies of 43% and 55% were obtained for pre-treated with lime and ozonation processes, respectively. Following this, the authors review the application of AnSBBR for the treatment of landfill leachate focusing on the selection of the biomass type, biomass acclimation strategy, treatment under different biodegradability conditions, kinetic studies, growth of biomass and its behavior on the inert support. Lastly, the results obtained in the oxidation of a concentrate from reverse osmosis of a sanitary landfill leachate are discussed. A combined treatment of electrocoagulation followed by electro-fenton was applied using iron consumable anodes and the influence of the applied current intensity, process duration, initial pH and stirring speed was assessed.