## 5 Application of eNO\({}_{3}\)R to Brackish Groundwater: A Case Study
### Sustainability Analysis
LCA evaluates the environmental emissions and impacts on human health associated with the entire life cycle of the process, from raw material extraction to final disposal [241; 242]. This analysis must consider factors such as energy consumption, emissions, and waste production. When comparing these impacts with those of conventional nitrate removal processes, i.e., ion exchange, reverse osmosis, or electrodialysis processes, we can better identify the relative advantages and limitations of electrocatalytic reduction. Furthermore, key sustainability metrics, such as carbon footprint and water use, can provide quantitative information on the environmental performance of the process and emphasize areas for enhancement and optimization. To the best of the authors' knowledge, there are no previous literature studies on the LCA of electrocatalytic nitrate reduction for brackish groundwater treatment. However, [PERSON] et al. [243] carried out a techno-economic analysis and an LCA of the electrochemical conversion of nitrate ions present in wastewater to hydroxylamine (NH2 OH), which is a valuable chemical intermediate. They calculated the NH2 OH production costs and determined the life cycle emissions for a small-scale facility (producing 1500 kgNH2 OH/day) and a large-scale facility (producing 50,000 kgNH2 OH/day) integrated into an Iowa wastewater treatment plant. Thus, they found that the NH2 OH production costs for the small- and large-scale facilities are estimated at $6.14/kg-NH2 OH and $5.37/kg-NH2 OH, respectively. The parameters dominating the electrochemical reactor cost are electrolyte, separations, and fixed cost. Meanwhile, LCA results revealed that the proposed electrochemical pathway to produce NH2 OH has lower life cycle impacts than the conventional pathway, especially when using solar energy. Bearing in mind that the Haber-Bosch process entails significant environmental impacts, such as high energy consumption and high CO2 emissions (400 t of CO2 per year, or 1.6% of global CO2 emissions), mostly due to the production of H2 by steam methane reforming (SMR), which releases CO2 stoichiometrically [244; 245]. In light of what has been described above, it can be deduced that a great deal of research is still required, both at the laboratory and pilot scale, to bring electrocatalytic processes to a high level of technological maturity, but they are also attractive in terms of prospects and applications. Accordingly, there are both challenges and opportunities in implementing renewable and sustainable energy solutions in electrocatalytic nitrate reduction processes. The major challenge is to scale up these systems to the industrial scale, whilst keeping economic feasibility by considering the initial costs of renewable energy infrastructure and storage technologies, which can be significant. Technological innovations, including advances in electrode materials, catalysts, and energy conversion systems, are key to enhancing efficiency, reducing costs, and making sustainable solutions economically viable. In the future, the integration of emerging trends in renewable energy and environmental regulations is likely to shape the future of sustainable nitrate reduction technologies, offering both opportunities for progress and challenges.