Partial Nitrification to Nitrite at Low DO

Partial nitrification to nitrite was reported to be technically feasible and economically favorable, which can be obtained by selectively inhibiting nitrite oxidizing microorganisms through many ways. This paper studied the effect of low DO(dissolved oxygen) concentration and the variation modes of DO on nitritation in SBR The results showed that low DO concentration throughout the SBR cycle led to the failour of partial nitrification. While the mode of variable DO concentrations in one cycle can achieve nitritation in SBR. The variable DO mode was that 0.4 mg/L of DO concentration in feast period and 6 mg/L of DO concentration in famine period. In this DO mode, the ratio of NO₂ ^--N to the sum of NO₂ ^--N and NO₃ ^--N in effluent can reach over 80%.