生活污水常温处理系统中AOB与NOB竞争优势的调控

Competition and Optimization of AOB and NOB for Domestic Wastewater Treatment at Normal Temperatures

常温(19℃±1℃)条件下,采用SBR工艺处理低碳氮比(C/N)实际生活污水,研究氨氧化菌(AOB)与亚硝酸盐氧化菌(NOB)竞争优势的调控,在接种全程硝化污泥的系统中使AOB成为优势菌群,启动并维持常温短程硝化.通过控制曝气量为40 L/h使系统溶解氧处于较低水平(DOaverage<1.0 mg/L),同时结合好氧硝化时间的优化控制,即在pH值"氨谷"点前及时停止曝气的短周期定时控制,强化AOB的竞争优势.待AOB的竞争优势初步形成后(亚硝酸盐积累率NO-2-N/NO-x-N达到50%),每周期曝气时间随着NO-2-N/NO-x-N的提高由3 h逐步延长至4 h、5 h,从而提高NH+4-N去除率,进一步增强AOB在系统中的竞争优势,短程硝化成功启动,NO-2-N/NO-x-N稳定在95%以上.FISH检测结果表明AOB大约占总菌群的9.97%.在线控制好氧硝化时间可以很好地维持短程硝化效果,NH+4-N去除率达到97%以上.研究还表明,对于全程硝化污泥常温下如果不限制溶解氧,单纯依靠短周期定时控制无法使AOB成为优势硝化菌群.

At normal temperature of 19℃ ± 1 ℃ and seed sludge from the system of conventional nitrogen removal via nitrate composed of both ammonia oxidizing bacteria （AOB） and nitrite oxidizing bacteria （NOB）, the competition and optimization of AOB and NOB was investigated in a lab-scale SBR treating domestic wastewater. The reactor was operated under the aeration rate of 40 L/h with the average DO concentration below 1.0 mg/L, and combined with the control of aeration time, i.e., aeration was stopped before the pH ＂ammonia valley＂ was detected. After AOB became pre-dominant nitrifying bacteria （nitrite accumulation rate NO2^--N/NO^-x-N reached 50% ）, the aerobic durations were gradually prolonged from 3 h to 4 h and 5 h to improve the ammonia removal efficiencies and enhance AOB dominant. By the above operational pattern, nitrogen removal via nitrite was successfully achieved with NO2^--N/NO^x-N over 95 %. Fluorescence in-situ hybridization （FISH） analysis showed that AOB was accounted for 9.97% of total biomass. The on-line control of aerobic duration was an effective method to maintain the partial nitrification and the NH4^＋ -N removal efficiency was above 97%. The research results also proved that at normal temperatures, for the seed sludge from the conventional nitrogen removal via nitrate, AOB would not become dominant nitrifying bacteria only by the aeration time control without the DO restriction.