We are still learning about the exact triggers for N2O production from activated sludge. However, the predominant emission of N2O comes from the aerated nitrification, mainly from the metabolism of NH4 by ammonium oxidizing bacteria.
Especially, the lack of sufficient oxygen during the nitrification process has resulted in high levels of N2O production. Due to the simultaneous aeration, the N2O is stripped into the atmosphere. Generally, sudden perturbations of the bioprocesses, such as changes in dissolved oxygen, NH4+ shock loads, or NO2- spikes, also lead to immediate increases in N2O emissions.
