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ORIGINAL RESEARCH article

Front. Bioeng. Biotechnol.
Sec. Bioprocess Engineering
Volume 13 - 2025 | doi: 10.3389/fbioe.2025.1475589

Groundwater Denitrification using Electro-Assisted Autotrophic Processes: Exploring Bacterial Community Dynamics in a Single-Chamber Reactor

Provisionally accepted
Javiera Toledo-Alarcón Javiera Toledo-Alarcón 1*Eduardo Ortega-Martinez Eduardo Ortega-Martinez 1Javier Pavez-Jara Javier Pavez-Jara 2Oscar Franchi Oscar Franchi 3Ivan Nancucheo Ivan Nancucheo 4Héctor Zuñiga-Barra Héctor Zuñiga-Barra 2José Luis Campos Gómez José Luis Campos Gómez 1David Jeison David Jeison 2
  • 1 Faculty of Engineering and Sciences, Adolfo Ibáñez University, Viña del Mar, Chile
  • 2 Escuela de ingeniería bioquímica, Pontificia Universidad Católica de Valparaíso, valparaiso, Chile
  • 3 Facultad de Ciencias Naturales, Matemática y del Medio Ambiente, Universidad Tecnológica Metropolitana, Ñuñoa, Chile
  • 4 Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Concepción, Chile

The final, formatted version of the article will be published soon.

    Nitrate, a major groundwater pollutant from anthropogenic activities, poses serious health risks when present in drinking water. Denitrification using bio-electrochemical reactors (BER) offers an innovative technology, eco-friendly solution for nitrate removal from groundwater. BER use electroactive bacteria to reduce inorganic compounds like nitrate and bicarbonate by transferring electrons directly from the cathode. In our work, two batch BER were implemented at 1V and 2V, using anaerobic digestate from a full-scale wastewater treatment plant as inoculum. Nitrate, nitrite, sulfate, total ammoniacal nitrogen, and 16S rRNA analysis of bacterial community, were monitored during BER operation. The results showed effective nitrate removal in all BERs, with denitrification rate at 1V and 2V higher than the Control system, where endogenous respiration drove the process. At 1V, complete nitrate conversion to N2 occurred in 4 days, while at 2V, it took 14 days. The slower rate at 2V was likely due to O2 production from water electrolysis, which competed with nitrate as final electron acceptor. Bacterial community analysis confirmed the electroactive bacteria selection like the genus Desulfosporosinus and Leptolinea, confirming electrons transfer without an electroactive biofilm. Besides, Hydrogenophaga was enhanced at 2V likely due to electrolytically produced H2. Sulfate was not reduced, and total ammoniacal nitrogen remained constant indicating no dissimilatory nitrite reduction of ammonia. These results provide a significant contribution to the scaling up of electro-assisted autotrophic denitrification and its application in groundwater remediation, utilizing a simple reactor configuration-a single-chamber, membrane-free design-and a conventional power source instead of a potentiostat.

    Keywords: Electroactive bacterial community, Desulfosporosinus genus, bioelectrochemical system, Autotrophic Denitrification, Nitrate removal

    Received: 04 Aug 2024; Accepted: 06 Jan 2025.

    Copyright: © 2025 Toledo-Alarcón, Ortega-Martinez, Pavez-Jara, Franchi, Nancucheo, Zuñiga-Barra, Campos Gómez and Jeison. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Javiera Toledo-Alarcón, Faculty of Engineering and Sciences, Adolfo Ibáñez University, Viña del Mar, Chile

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.