Effect of PHB and oxygen uptake rate on nitrous oxide emission during simultaneous nitrification denitrification process.

Simultaneous nitrification denitrification (SND) process was achieved in a SBR system to evaluate the impacts of intracellular carbon source PHB and oxygen uptake rate (OUR) on nitrous oxide (N(2)O) emission. Compared with the sequential nitrification and denitrification (SQND) process, SND process significantly improved the nitrogen removal. N(2)O emission during SND process was much higher than the SQND process. The amount of N(2)O emission was 26.85 mg N per cycle in SND process, which was almost four times higher than that in SQND process. About 7.05% of the removed nitrogen during SND process was converted to N(2)O-N. N(2)O emission had great relations with the OUR and the OUR could reflect the N(2)O emission trend more exactly than the DO concentration. At the aerobic stage of SND, the simultaneous denitrification could carried out using PHB as the carbon source and N(2)O emission increased because of the slow degradation of PHB.