ABSTRACT
Effect of C/N (COD/NO3(-) -N) ratio on nitrite accumulation during denitrification process was investigated in a sequencing batch reactor (SBR) with acetic sodium as the electron donor. The nitrite accumulation ratio was 45% at a C/N ratio of 3 during operation in SBR with HRT at 6 h. According to the results of batch experiments, Nitrite accumulation ratios were higher at C/N ratios of 2.5 and 3.0, and the values were 47.50% +/- 1.005% and 45.28% +/- 5.469%, respectively. The nitrite specific accumulation rate was (30.17 +/- 1.70) mg x (g x h)(-1) at a C/N ratio of 2.5, and was (29.92 +/- 1.90) mg x (g x h)(-1) at a C/N ratio of 3.0. C/N ratios of 2.5-4.0 did not affect the nitrate reduction rate but obviously affected the nitrite accumulation rate. C/N ratios of 2.5 and 3.0 were favorable for nitrite accumulation, and a C/N ratio > or = 3.5 would lead to decrease in nitrite accumulation (SBR).
