Simultaneous removal of organics and ammonium-nitrogen from reverse osmosis concentrate of mature landfill leachate

Leachate treatment forms one of the main issues in landfill management. The recirculation of reverse osmosis (RO) concentrate of mature leachate, which is characterized by low biodegradability, into the landfill has not proven itself to be a sustainable treatment method. Hence alternate methods for the treatment of the concentrated leachate products have to be devised. In this work, the treatment of a mature leachate and its RO concentrate using different combinations of physico-chemical and biological treatment methods for the removal of organic carbon and ammonium-nitrogen (N-NH4+) were investigated. The coupling of electrocoagulation and ozonation with biological treatment was examined in this study. The combination of biological treatment with pretreatment processes like ozonation, electrocoagulation and adsorption proved to be a successful strategy for the removal of refractory organics as well as ammonium-nitrogen (N-NH4+). Ozonation led to a total organic carbon (TOC) removal of up to 12.5% whereas with electrocoagulation, up to 40% removal of TOC was observed. In combination with biological treatment, up to 90% TOC and 65% ammonium-nitrogen removals were observed during the experiments, all of which were performed in batch mode.