Data underlying the publication: Toward Nitrous Oxide-Free Ammonium Treatment: Integrating Hydrogenotrophic Denitrification in Anoxic Bioanodes

Microbial electrolysis cells (MECs) offer a novel alternative to conventional biological ammonium (NH₄⁺) removal by using electrodes, rather than oxygen, as electron acceptors. However, NH₄⁺ oxidation at bioanodes can result in substantial nitrous oxide (N₂O) emissions—a potent greenhouse gas with significant climate impact. We investigated the potential of hydrogenotrophic denitrification within the anodic compartment to mitigate N₂O emissions during NH₄⁺ removal. In situ hydrogen (H₂) addition effectively reduced N₂O concentrations to below 0.01 mg-N/L, without nitrate or nitrite accumulation. Batch experiments demonstrated that the suspended biomass, exhibited a high capacity for N₂O reduction, which was strongly dependent on H₂ availability and linked to denitrification activities. Integrating hydrogenotrophic denitrification with NH₄⁺ oxidation in MECs presents a promising approach for sustainable nitrogen management with near-zero N₂O emission.