ABSTRACT
Landfills and garbage dumps generate leachate when water passes through them due to precipitation, drainage or groundwater movement. The characteristics of this leachate vary according to the age of the landfill. The biological nitrification-denitrification process is one of the most promising methods available for removing ammonia from older landfill leachates. Due to the low biodegradable carbon content in these leachates, an external carbon source has to be added to facilitate denitrification. The leachate was collected from the landfill every two weeks and kept in closed containers at 4°C. The daily aliquot of feed, having been stored at 4°C, was allowed to acclimate to ambient temperature (approximately 20°C) before addition to the system. The primary purpose of the anoxic reactor was to denitrify the highly nitrified return sludge from the clarifier. The reactor was fed continuously with a carbon solution and tribasic sodium phosphate, together with the leachate feed.
