校园污水脱氮除磷处理系统的运行策略及其对污泥性能的影响

Operation strategies of nitrogen and phosphorus removal system for campus sewage and its influence on the performance of activated sludge

校园污水具有水量变化大、水质和污染物负荷不稳定的特点,如何维持污水处理系统的正常稳定运行是校园污水处理系统运行的关键。以西安市某大学校园污水处理站间歇式A2/O工艺为研究对象,提出了低负荷下增加厌氧好氧时间比的运行策略,以减缓暑期硝化菌的衰减,加快重新启动的进程。运行结果表明,假期期间污水处理站水量仅为非假期期间的5%~10%,污泥浓度由放假前的4 500 mg·L-1降低至假期(42 d)结束后的3 200 mg·L-1,仅衰减了29%;而对应的污泥释磷吸磷活性则分别衰减了77%和85.7%,AOB和NOB活性则衰减较小,分别衰减了64%和34%;FISH测定结果表明生物种群变化与活性变化相一致。维持假期运行策略可使污泥中的功能微生物在厌氧条件下以较低的速率衰减,从而为假期后的重新快速启动创造了良好的条件。以上结果可为大学校园污水处理站假期运行方式提供参考。

Campus sewage is characterized as large change in water volume, unstable water quality and pollutant loading. It is a key for the operation of campus sewage treatment system to maintain the sewage treatment system operating in a normal and stable way. In the study, the intermittent A2/O process of a university campus sewage treatment station in Xi’an was taken as the target, and the increase of the anaerobic-aerobic time ratio under low pollutant loading was proposed as the operation strategy in order to decline the decay of nitrifying bacteria and accelerate the restart of treatment process in summer holiday. The results show that the influent of the sewage treatment station during the holiday period was only 5%~10% of the normal treatment period, and the sludge concentration decreased from 4 500 mg·L-1 before the holiday to 3 200 mg·L-1 after the holiday(42 d), only decayed by 29%. The corresponding sludge activities of phosphorus release and absorption declined by 77% and 85.7%, respectively, while the activities of AOB and NOB presented smaller decays with64% and 34%, respectively. FISH measurement showed that the community structure analysis corresponded to the change in activities. The strategy in summer holiday allowed the functional microorganisms in the sludge to maintain a lower decay rate under anaerobic conditions, the nitrifying bacteria had a lower decay rate than PAOs, which was more conducive to the rapid restart of the activated sludge system after holiday. The results of the study can be used as a technical reference for the holiday operation strategy of the university campus wastewater treatment station.