High Productionof Nitrous Oxide (N₂O)via Acidic Denitrification

Nitrous oxide (N₂O) recovery in wastewater management offers a promising dual benefit of resource recovery and greenhouse gas reduction. This study demonstrates significant N₂O production via microbial denitrification under acidic conditions. Using a bioreactor maintained at pH 5, continuously fed with nitrite and acetate, an acidic microbial culture was cultivated with <i>Rhodanobacter</i> emerging as the dominant denitrifying genus. The culture achieved a nitrite-to-N₂O conversion efficiency exceeding 60%, with a production rate of 6.0 ± 0.2 mg of N₂O-N h^–1 (g volatile suspended solids)⁻¹. Stable acidic denitrification was sustained in semicontinuous operation, with liquid N₂O concentrations accumulating up to 150 mg of N/L. This discovery introduces a novel pathway for N₂O production and recovery, offering new possibilities for wastewater nitrogen management.