4. Conclusions
Membrane combined process for biogas recovery and nitrogen removal was applied to treat dual membrane concentrated municipal wastewater. Both AD and CANON were successfully started up using an MBR within the shorter period (respectively 37 d and 62 d) because of the complete retention of biomass. During the whole operation period, the COD removal efficiency of the whole system was about 96%, and most COD was converted into biogas in the AnMBR with a stable methane yield of 1672 mL/d, corresponding to 223 mL CH4/g COD under ambient temperatures. Meanwhile nitrogen removal was obtained in the sequential CANON MBR with a total nitrogen removal efficiency of 81%. Stable methane yield and energy analyses indicated the sustainability of the membrane combined process. Therefore, the proposed process is an efficient and economic approach for biogas recovery and nitrogen removal. It is a promising treatment process for energy-neutral municipal wastewater treatment.