Effect of ammonium on nitrous oxide emission during denitrification with different electron donors

Nitrous oxide (N₂O) emission during denitrification is receiving intensive attention due to its high potential to cause greenhouse effects. In this study, denitrifiers were acclimated in sequencing batch reactors with methanol or acetate as the electron donor and nitrate as the electron acceptor. The effects of ammonium on N₂O emission were examined in batch experiments with various electron donors. With the addition of ammonium, N₂O emission increased under all the examined conditions compared to experiments without ammonium addition. With different electron donors, the highest ratio of N₂O emission to the removed oxidized nitrogen was 0.70% for methanol, 5.34% for acetate, and 34.79% for polyhydroxybutyrate.