In situ simultaneous organics and nitrogen removal from recycled landfill leachate using an anaerobic-aerobic process

An anaerobic-aerobic process including a fresh refuse landfill reactor as denitrifying reactor, a well-decomposed refuse reactor as methanogenesis reactor and an aerobic activated sludge reactor as nitrifying reactor was operated by leachate recirculation to remove organic and nitrogen simultaneously. The results indicated that denitrification and methanogenesis were carried out successfully in the fresh refuse and well-decomposed landfill reactors, respectively, while the nitrification of NH(4)(+)-N was performed in the aerobic reactor. The maximum organic removal rate was 1.78 kg COD/m(3)d in the well-decomposed refuse landfill reactor while the NH(4)(+)-N removal rate was 0.18 kg NH(4)(+)-N/m(3)d in the aerobic reactor. The biogas from fresh refuse reactors and well-decomposed refuse landfill reactors were consisted of mainly carbon dioxide and methane, respectively. The volume fraction of N(2) increased with the increase of NO(3)(-)-N concentration and decreased with the drop of NO(3)(-)-N concentration. The denitrifying bacteria mustered mainly in middle layer and the denitrifying bacteria population had a good correlation with NO(3)(-)-N concentration.