Electro bioremediation of nitrate contaminated groundwater: from laboratory to on site pilot plant

Water stands out as the most essential resource currently under serious threat. The combination of water scarcity and increasing pollution of available water poses significant challenges to governance and society. Typically, this problem is exacerbated in rural areas due to limited access to water management services. In these regions, modern agricultural and intensive livestock production practices contribute significantly to nitrate pollution of water bodies. In such scenarios, there is a pressing need for the development of sustainable decentralised treatment solutions. This Ph.D. thesis focuses on electro-bioremediation, which harnesses the ability of certain microorganisms to exchange electrons with a solid material. Specifically, nitrate removal is based on its reduction to dinitrogen gas using a cathode as an electron donor. This innovative process eliminates the need to introduce chemicals as reducing agents into the water, which is common in conventional treatments, and at the same time prevents the generation of any residue. This is the main advantage of the treatment, which requires minimal energy to achieve nitrate removal. This thesis describes the development of electro-bioremediation from laboratory experiments to constructing an on-site pilot plant. It was started with laboratory experiments to understand nitrate reduction in this system in order to optimise the process. In addition, the full potential of this technology to address other contaminants, such as arsenic and pathogens, was explored. Finally, the technology was validated through real treatment at an on-site pilot plant. The overall results demonstrate the economic competitiveness of this treatment and encourage further research in this area