Synchronous removal of nitrogen and copper from biogas slurry by electrode-SBBR

For consideration of excessive ammonia nitrogen (NH4+-N) in concentrated biogas slurry, and copper (Cu2+) caused by additions of feed additives, a new system of electrode-sequencing batch biofilm reactor (SBBR) technique was constructed for simultaneously removing the NH4+-N and copper in concentrated biogas slurry, through integrating the advantages of two methods including electrode-biofilm and SBBR. Meanwhile, through simulated wastewater and biogas slurry, the both of pertinent parameters and effects of electrode-SBBR were also investigated. The results showed that the operating process of this technique was: adding water → anaerobic processing → aeration → anoxic or anaerobic processing → effluent dewatering → idle. The optimal conditions were suggested as follows: hydraulic retention time (HRT) was 7.0 h, anaerobic and aeration time was 0.5 h and 4.0 h respectively, and anoxia / anaerobic time was 2.5 h, furthermore, electric current ranged 30-60 mA, DO was 4.0-5.0 mg/L and C/N ratio was greater than 10.0. In summary, the removing efficiencies of total nitrogen, Cu2+ and COD from the biogas slurry could reach to 45.79%, 86.53% and 84.86% respectively by the electrode-SBBR system. The results indicate that the electrode-SBBR system can be considered as a new technique for removal of nitrogen and copper from the biogas slurry simultaneously.