Simultaneous organic and nitrogen removal from municipal landfill leachateusing an anaerobic-aerobic system

An anaerobic-aerobic system including simultaneous methanogenesis and denit rification was introduced to treat organic and nitrogen compounds in immatu re leachate from a landfill site. Denitrification and methanogenesis were s uccessfully carried out in the anaerobic reactor while the organic removal and nitrification of NH4+-N were carried out in the aerobic reactor when ri ch organic substrate was supplied with appropriate hydraulic retention time . The maximum organic removal rate was 15.2 kg COD/m(3) d in the anaerobic reactor while the maximum NH4+-N removal rate and maximum nitrification rat e were 0.84 kg NH4+-N/m(3)/d and 0.50 kg NO3--N/m(3)/d, respectively, in th e aerobic reactor. The pH range for proper nitrification was 6-8.8 in the a erobic reactor. The organic compounds inhibited nitrification so that the o rganic removal in the anaerobic reactor could enhance the nitrification rat e in the following aerobic reactor. The gas production rate was 0.33 m(3)/k g COD and the biogas compositions of CH4, CO2, and N-2 were kept relatively constant, 66-75, 22-32, and 2-3%, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.