[Effect of Free Hydroxylamine on the Activity of Two Typical Nitrite-oxidizing Bacteria].

The sludge from enrichment of and was used as a research object and batch tests were performed. The inhibitory effects of hydroxylamine on and under the same pH and different hydroxylamine concentration gradients, the same hydroxylamine concentration, and different pH gradients were investigated. The results showed that under the same pH condition, the activity of decreased with increasing hydroxylamine concentration. Under the same hydroxylamine concentration (HA=5 mg·L) at a higher pH environment (pH ≥ 7.5), hydroxylamine produced more free hydroxylamine (FHA) and the inhibitory effect on was improved. At a low pH environment (pH≤7), ionic hydroxylamine promoted the activity of . The inhibitory effect of hydroxylamine on was limited. When pH=7.5 and hydroxylamine concentration was 45 mg·L, the relative activity of was 82%. The NOB growth rate kinetics model and the non-substrate inhibition linear equation were used to describe the effect of FHA on and activity. The coefficient of determination was 0.90 and 0.94, respectively. FHA may be the main reason for inhibiting the activity of and .