Co-existing anammox, ammonium-oxidizing, and nitrite-oxidizing bacteria in biocathode-biofilms enable energy-efficient nitrogen removal in bioelectrochemical desalination process

Authors: GHIMIRE, UMESH - Mississippi State University; GUDE, VEERA - Mississippi State University; Brooks, John; Smith, Renotta; Deng, Dewayne

Submitted to: Chemical Engineering Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2021
Publication Date: 3/30/2021
Citation: Ghimire, U., Gude, V.G., Brooks, J.P., Smith, R.K., Deng, D.D. 2021. Co-existing anammox, ammonium-oxidizing, and nitrite-oxidizing bacteria in biocathode-biofilms enable energy-efficient nitrogen removal in bioelectrochemical desalination process. Chemical Engineering Journal. 9(14):4967-4979. https://doi.org/10.1021/acssuschemeng.0c07883.
DOI: https://doi.org/10.1021/acssuschemeng.0c07883

Interpretive Summary: Biocathodes are systems of recovering biological energy from municipal wastewater systems. These systems also remove salt from wastewater systems. Because of the biological nature of these systems, they are a form of sustainable wastewater reclamation and energy production. Some of these systems have been investigated from a biological perspective to determine the populations that are most involved in an effective system. A system was investigated to determine the maximum capable power output and determine the effect on the biological community. Varying the aeration of the system achieved maximum nitrogen removal from the wastewater system. Microbial communities were investigated with DNA sequencing and demonstrated that specific bacterial families dominated the wastewater and indicated that nitrogen removal was most likely associated with these families. Additionally, bacteria related to nitrogen oxidizing processes were found and thus this study demonstrated that both families coexist in the same system.

Technical Abstract: A nitration-anammox biocathode microbial desalination cell (NiAmoxMDC) was investigated for resource-efficient wastewater treatment and desalination. A maximum power density of 1.007 W/m3 with an average TDS removal of 53.9 ± 4.1 % was accomplished. The average COD removal in each cycle was observed in the range of 72.1 ± 1.6% and the corresponding average CE of NiAmoxMDC was 25.6 ± 6.1%. The net energy produced by NiAmoxMDC at an aeration rate of 3 ml/min was 0.031 kWh/m3. The energy consumption by NiAmoxMDC was between 0.12 kWh/kg N and 0.58 kWh/kg N which is significantly lower than other convetional and bioelectrochemcial nitrogen removal processes. At an aeration rate of 3 ml/min, 97.7% of NH4+ - N removal and 74.7% of total nitrogen (TN) removal were achieved. Microbial community analysis of nitritation- anammox biofilm showed a relative abundance of 29.3% belonging to the order of Ignavibacteriales. The second most abundant phylum affiliated to Planctomycetes phylum (20.5%) belonging to the order Candidatus Brocadiales. Aerobic ammonium oxidizing bacteria (AOBs) Nitrospira multiformis, Nitrosomonas europaes genome sequence, and Nitrosomonas Sp. with a relative abundance of 0.1%, 0.05%, and 1.2% respectively were found. The co-existence of AOBs and anammox bacteria in the same biofilm of single-stage NiAmoxMDC was confirmed.