Electrode-dependent ammonium oxidation with different low C/N ratios in single-chambered microbial electrolysis cells

• Published in: Bioelectrochemistry (Amsterdam, Netherlands) Netherlands), 2021-12, Vol.142, p.107889-107889, Article 107889
• Main Authors: Zhou, Qinmao, Yang, Nuan, Zheng, Decong, Zhang, Lixia, Tian, Chang, Yang, Qingzhuoma, Li, Daping
• Format: Article
• Language: English
• Subjects: Acetic acid; Ammonia; Ammonium; Anaerobic digestion; Anaerobic microorganisms; Bacteria - chemistry; Biodegradation, Environmental; Bioelectric Energy Sources - microbiology; Bioreactors - microbiology; Carbon/nitrogen ratio; Community structure; Denitrifying bacteria; Electric potential; Electrode-dependent ammonium oxidation; Electrodes; Electrolysis; Electrolytic cells; Low C/N ratios; Microbial electrolysis cell; Microbiota; Microorganisms; Nitrifying bacteria; Nitrogen; Nitrogen balance; Nitrogen removal; Organic carbon; Oxidation; Relative abundance; Sodium acetate; Voltage; Waste Water - chemistry
• ISSN: 1567-5394; 1878-562X
• DOI: 10.1016/j.bioelechem.2021.107889

[Display omitted] •Electrode-dependent ammonia oxidation with various C/N ratios was investigated.•Applying a voltage stimulated nitrogen removal under low C/N ratio of 0, 1, and 1.5.•Remaining acetate inhibited electrode-dependent autotrophic ammonium oxidation.•Nitrifying and denitrifying bacteria were enriched on both the anode and cathode.•The total OTU numbers in MECs were much more than that in controls. Alternative method should be found to solve the ammonia accumulation in anaerobic digestion. Herein, electrode-dependent ammonium oxidation was successfully achieved in anaerobic single-chambered microbial electrolysis cells (MECs)under different low C/N ratios (0, 1, and 1.5), with an applied voltage of 0.6 V as well as an initial NH4+-N and NO3–-N concentration of 500 and 300 mg/L. The nitrogen removal performance of MECs and the controls indicated that applying a voltage stimulated nitrogen removal under low C/N ratios of 0, 1, and 1.5. However, the remaining organic carbon in MEC with a relatively higher C/N ratio of 3 inhibited the ammonium oxidation. Current changes and cyclic voltammetry demonstrated that the bioanode with several bioelectrochemical activities could promote ammonium oxidation. The dominant genera Truepera, Aquamicrobium, Nitrosomonas, Arenimonas, Comamonas, and Cryobacterium enriched on both electrodes could be the key functional taxa in MECs with C/N ratios of 0, 1, and 1.5. The remaining sodium acetate in MEC with C/N ratio of 3 inhibits microbial community structure and relative abundance, which may adversely affected nitrogen removal. Further caculation showed that nitrogen balance was essentially achieved, while electron balance was disrupted since electrons may be consumed through NO3−-N recycle and cell synthesis, and finally caused low coulombic efficiency.