Dynamics of N2O production from activated sludge

The dynamics of nitrous oxide emissions from activated sludge from a Danish wastewater treatment plant were investigated under anoxic and oxic conditions. No nitrous oxide emissions were detected from sterile controls. Ammonium oxidation was only detected in oxic experiments. The ammonium oxidation rate increased with increasing dissolved oxygen concentrations. Oxic conditions favoured nitrous oxide production. A coupling between ammonium oxidation and nitrite reduction was suggested as the likely mechanism. Under anoxic conditions only minor nitrous oxide production occurred. Most of the nitrous oxide produced was reduced to nitrogen under anoxic conditions. If ammonium was present, or if nitrous oxide residence time was shortened, nitrous oxide production increased. Increasing temperature and dissolved oxygen concentrations led to an increase in nitrous oxide production. There are 35 references.