Life cycle assessment of electrodialysis for sidestream nitrogen recovery in municipal wastewater treatment

Nitrogen is removed during municipal wastewater treatment to reduce eutrophication of waterways and preserve drinking water quality. Nitrification-denitrification and sidestream partial nitrification-anammox are state-of-the-art municipal N removal technologies, but they require energy for aeration and can release nitrous oxide as a fugitive greenhouse gas. An emerging sidestream electrodialysis technology is intended to both remove and recover N as ammonium-based fertilizer. This midpoint life cycle assessment compiles literature values to compare the state-of-the-art technologies of municipal wastewater nitrogen removal to the new electrodialysis nitrogen removal and recovery technology, accounting for the offset of Haber-Bosch-derived ammonia. Electrodialysis is projected to be environmentally favorable compared to the state-of-the-art, predicting electricity savings similar to anammox and, with the offset of industrial ammonia manufacture, net negative emissions in five of ten midpoint environmental impact categories, including global warming potential.