Electrochemical enrichment of marine denitrifying bacteria to enhance nitrate metabolization in seawater. Issue 4 (August 2021)

• Record Type: Journal Article
• Authors: De La Fuente, María José; De la Iglesia, Rodrigo; Farias, Laura; Daims, Holger; Lukumbuzya, Michael; Vargas, Ignacio T.
• Is Part Of: Journal of environmental chemical engineering. Volume 9:Issue 4(2021)
• Publication Date: 2021-08
• Subjects: Microbial enrichment -- Marine denitrifying bacteria -- Bioelectrochemical denitrification system -- Nitrate; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2021.105604
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: High concentrations of nitrate from industrial discharges to coastal marine environments are a matter of concern owing to their ecological consequences. In the last years, Bioelectrochemical Denitrification Systems (BEDS) have emerged as a promising nitrate removal technology. However, they still have limitations, such as the enrichment strategy for specific microbial communities in the electrodes under natural conditions. In this study, three-electrode electrochemical cells were used to test microbial enrichment from natural seawater by applying three reported potentials associated with the dissimilatory denitrification process (−130, −260, and −570 mV vs. Ag/AgCl). The microbial community analysis showed that by applying −260 mV (vs. Ag/AgCl) to the working electrode, it was possible to significantly enrich denitrifying microorganisms, specifically Marinobacter, in comparison with the control. Furthermore, −260 mV (vs. Ag/AgCl) led to a significantly higher nitrate removal than other conditions, which, combined with cyclic voltammetry analysis, suggested that the polarized electrodes worked as external electron donors for nitrate reduction. Hence, this work demonstrates for the first time that it is possible to enrich marine denitrifying microorganisms by applying an overpotential of −260 mV (vs. Ag/AgCl) without the need for a culture medium, the addition of an exogenous electron donor (i.e., organic matter) or a previously enriched inoculum. Graphical Abstract: ga1 Highlights: Electrochemical enrichment of marine denitrifying bacteria was accomplished. Molecular tools, electrochemistry and nitrate removal in seawater were combined. Marine denitrifying bacteria can be enriched by applying −260 mVvs.Ag/AgCl. BEDS at −260 mVvs.Ag/AgCl showed the highest nitrate removal among treatments. Electrochemical enrichment as a strategy to accelerate the start-up of bioreactors.