Bioelectrochemically-assisted nitrogen removal in osmotic membrane bioreactor.

ABSTRACT

Nitrogen removal in osmosis membrane bioreactor (OMBR) is important to its applications but remains a challenge. In this study, a bioelectrochemically-assisted (BEA) operation was integrated into the feed side of OMBRs to enhance nitrogen removal, and sodium acetate was served as a draw solute and supplementary carbon source for the growth of denitrifying bacteria due to reversed-solute. The effects of operation mode and influent ammonium (NH4 +) concentration were systematically examined. Compared to a conventional OMBR, the integrated BEA-OMBR achieved higher total nitrogen removal efficiency of 98.13%, and chemical oxygen demand removal efficiency of 95.83% with the influent NH4 +-N concentration of 39 mg L-1. The sequencing analyses revealed that ammonia-oxidizing bacteria (0-0.04%), nitrite-oxidizing bacteria (0-0.16%), and denitrifying bacteria (1.98-8.65%) were in abundance of the microbial community in the feed/anode side of integrated BEA-OMBR, and thus BEA operation increased the diversity of the microbial community in OMBR. Future research will focus on improving nitrogen removal from a high ammonium strength wastewater by looping anolyte effluent to the cathode. These findings have demonstrated that BEA operation can be an effective approach to improve nitrogen removal in OMBRs toward sustainable wastewater treatment.