Reduction of N₂O emission from biological nitrogen removal processes by Alcaligenes faecalis augmentation

Immobilized Alcaligenes faecalis gels were augmented into an intermittent aeration reactor treating wastewater to control the emissions of N₂O gas. An increase in the hydraulic retention time (HRT) in response to an applied loading caused a significant increase in N₂O production. Through A. faecalis augmentation, the N₂O conversion per influent total nitrogen (T-N) was reduced to 50 % of that in a control reactor. Although dissolved oxygen (DO) affected the N₂O emission in both the activated sludge and the A. faecalis-sagmented culture, the emission in the A. faecalis-augmented reactor at a low DO level was much lower than that in the control activated sludge reactor.