间歇曝气对硝化菌生长动力学影响及NO2^-积累机制

Effect of Intermittent Aeration on Growth Kinetics of Nitrifiers and Mechanism for NO_2^- Accumulation

采用间歇曝气方法处理低氨氮浓度生活污水,在SRT 10、5、2.5和1.25 d条件下,SBR反应器出水中NO2-含量(以N计,下同)为18、19、14和5 mg/L,积累率达到73%、85%、91%和78%,而连续曝气SBR仅为14%、21%、31%和34%;同时氨氮去除率维持在97%、95%、76%和39%,与连续曝气SBR的92%、97%、71%和47%相当.对硝化菌的生长动力学分析表明,在间歇曝气硝化系统中,氨氧化菌(AOB)可以通过产率系数(YAOB)的增加来提高自身在反应器中的绝对生物量,并补偿因间歇曝气引起的比底物利用速率下降,从而使比增殖速率(μm)和NH4+的氧化速率不变.与此相反,亚硝酸盐氧化菌(NOB)却不具备这种补偿特性,导致其μm和对NO2-氧化速率降低,引起了NO2-在出水中积累.

In order to investigate shortcut nitrification, an intermittent-aeration SBR was employed to treat the domestic wastewater containing low concentration of NH4^＋. The results shows that under the SRTs of 10, 5, 2.5 and 1.25 d, NO2^- 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 continuous-aeration SBR, however, the NO2^- accumulation ratios were only 14% , 21% , 31% and 34% . In addition, the corresponding removals of NH4^＋ 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 （ YSOB ）, which as a result compensated the decreased specific substrate utilization rate at low DO level and further led to the unchanged μm value and NH4^＋ oxidation rate. On the contrary, nitrite-oxidizin bacteria （NOB） was lack of the function of compensability, and it hence lowered the μm value and NO2^- oxidation rate, and therefore resulted in an accumulation of NO2^- in the effluent.