Toward energy-neutral wastewater treatment: A membrane combined process of anaerobic digestion and nitritation-anammox for biogas recovery and nitrogen removal

Energy-neutral wastewater treatment is increasingly emphasized in practice. In this study, a membrane combined process of a submerged anaerobic MBR and CANON MBR was investigated for biogas recovery and nitrogen removal by treating membrane concentrated municipal wastewater under ambient temperatures. Anaerobic digestion and nitritation-anammox were successfully started up in MBRs within a shorter period. During the sequential operation of 81 d, the COD removal efficiency of the whole system was about 96% and most CODs were converted into biogas in the anaerobic MBR with a stable methane yield of 1672 mL/d, corresponding to 223 mL CH4/g COD. Meanwhile nitrogen removal was obtained in the sequential CANON MBR with a total nitrogen removal efficiency of 81%. Furthermore, the net energy consumption estimated of membrane combined process was 0.09 kWh/m(3). These results indicated that the membrane combined process is a promising treatment process to achieve energy-neutral municipal wastewater treatment. (C) 2015 Elsevier B.V. All rights reserved.