选择性排泥改善颗粒污泥亚硝化性能的研究

通过好氧颗粒污泥反应器160d的运行,考察了选择性分离颗粒污泥对改善短程硝化工艺长期稳定运行的有效性.反应器整个运行过程分3个阶段,在第一阶段污泥停留时间(SRT)仅通过出水中携带的污泥自行调控,SRT极高,造成颗粒污泥的解体以及短程硝化性能的恶化.阶段2和阶段3中通过排出颗粒污泥床顶部污泥,控制SRT分别为(45±5),(30±5)d,氨氧化细菌(AOB)活性有明显提升.NO2--N比累积速率由阶段1运行时的7.44mg/(g·h)上升至阶段2时的8.08mg/(g·h)和阶段3时的9.14mg/(g·h);相反,NO3--N比产生速率从3.01mg/(g·h)下降至SRT为(30±5)d时的1.54mg/(g·h);阶段3出水中亚硝化率达80%以上.以上结果表明,通过选择性分离颗粒污泥控制SRT是实现短程硝化颗粒污泥工艺长期稳定运行的一种有效调控策略.另外,分析认为反应器高径比越大以及引入与NOB竞争亚硝酸盐基质的微生物均有利于该策略的实施.

Improved nitritation performance by selective sludge discharge in aerobic granular sludge process

An aerobic granular sludge reactor was run for 160 days to study the effectiveness of selective sludge discharge as a control strategy to improve the long-term stability of nitritation process. The reactor operation could be divided into three phases. During phase one the solid retention time (SRT, was extremely high) was controlled by sludge washed-out spontaneously with effluent withdrawal, leading to granules disaggregated and nitritation performance deteriorated. Sludge was selectively removed from the top of the settled sludge bed to control SRT which resulted in an increased specific NO2--N accumulation rate from 7.44 to 8.08mg/(g·h) in phase two SRT=(45±5) d], and then reached as high as 9.14mg/(g·h) in phase three SRT=(30±5)d]. On the contrary, the specific NO3--N production rate decreased from 3.01mg/(g·h) to 1.54mg/(g·h) when SRT was (30±5) days. The ratio of nitrite accumulation in effluent reached above 80% during phase three. All these results demonstrated that controlling SRT by selectively biomass discharge was an effective strategy to improve the long-term stability of nitritation process. Additionally, analysis suggest that using reactor with large height-diameter ratio and introducing competitors with nitrite oxidizing bacteria (NOB) for nitrite can both improve the implementation of selective sludge discharge-control strategy for nitritation.