[Effect of intermittent aeration on growth kinetics of nitrifiers and mechanism for NO2- accumulation].

In order to investigate shortcut nitrification,an intermittent-aeration SBR was employed to treat the domestic wastewater containing low concentration of NH_4~+.The results shows that under the SRTs of 10,5,2.5 and 1.25 d,NO_2~- produced in effluent were built up to 18,19,14 and 5(mg/L),respectively,with accumulation ratio of 73%,85%,91% and 78% respectively.As to the continuousaeration SBR,however,the NO_2~- accumulation ratios were only 14%,21%,31% and 34%.In addition,the corresponding removals of NH~+_4 in the intermittent-aeration SBR were maintained at a comparable level in contrast to those for the continuous-aeration SBR,i.e.,97%,95%,76% and 39% vs 92%,97%,71% and 47%.By exploring the growth kinetics of nitrifiers,ammonia-oxidizing bacteria(AOB) in the intermittent-aeration system was capable of increasing its biomass in the reactor by an elevation in growth yield(Y_(AOB)),which as a result compensated the decreased specific substrate utilization rate at low DO level and further led to the unchanged μ_m value and NH_4~+ oxidation rate.On the contrary,nitrite-oxidizin bacteria(NOB) was lack of the function of compensability,and it hence lowered the μ_m value and NO_2~- oxidation rate,and therefore resulted in an accumulation of NO_2~- in the effluent.