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.