A sequencing batch activated sludge reactor was used this study to investigate the effect of different carbon to nitrogen ratios(COD/N)(1,3,4,6)on pollutant removal performance and NO and N2O accumulation in the short-cut en-dogenous denitrification.The results showed that chemical oxygen demand and nitrite nitrogen removal were better when COD/N was greater than 3.The peak of NO accumulation increased first and then decreased with the increase of COD/N,and the maximum of 0.45 mg/L was achieved when COD/N was 4.While N2O accumulation showed a trend of decreasing first and then increasing.the peak of N2O accumulation was the smallest(3.7 mg/L)when COD/N was 3.The NO accumu-lation was related to the COD/N,anaerobic time,NO and free nitrous acid inhibition.The N2O accumulation was caused by COD/N,NO,and free nitrous acid.
carbon to nitrogenshort-cut endogenous denitrificationnitric oxidenitrous oxidedenitrifying reductase