短程硝化启动运行中功能菌群变化研究

【目的】短程硝化-厌氧氨氧化是可实现的最短生物脱氮工艺,短程硝化是实现该工艺的重要环节和必要条件。【方法】采用序批式反应器(SBR)来实现短程硝化过程的启动和稳定运行,并对该过程中的相关功能菌群变化进行检测分析。【结果】通过控制低DO浓度(<1 mg/L)和逐步提高氨氮进水负荷,可抑制氨氧化细菌(NOB)菌群增殖并促进亚硝酸氧化菌(AOB)菌群规模显著扩大,实现短程硝化过程的启动和稳定运行。在氨氮进水负荷为0.055 kg/(m3.d)时,平均氨氮去除容积负荷和污泥负荷可达到0.043kg/(m3.d)和0.16 kg/(kg.d),平均亚硝酸盐积累率可达到83.4%。在短程硝化启动和稳定运行过程中,NOB菌群密度从2.0×105CFU/mL降至1.5×104CFU/mL,相对丰度从5.51%降至2.14%;AOB菌群密度从4.5×104CFU/mL增加至1.5×107CFU/mL,相对丰度从0.18%增加至7.25%。【结论】AOB菌群规模的扩大是实现短程硝化和氨氮去除能力提高的主要原因,同时较高的进水氨氮浓度和负荷也会造成亚硝化活性的抑制。

Variation of functional bacteria during start-up and operation of partial nitrification process

Objective] Partial nitrification-anammox is considered as the shortest?process for biological nitrogen removal and partial nitrification is the important part of this process. Methods] The variation of functional bacteria during start-up and stable operation of partial nitrification process was investigated in a SBR bioreactor in this study. Results] The results indicated that ammonia-oxidizing bacteria (AOB) population was expanded significantly and nitrite-oxidizing bacteria (NOB) population was inhibited when DO concentration was controlled lower than 1 mg/L and ammonia loading of the influent increased gradually. As a result, start-up and stable operation of partial nitrification process was realized. When ammonia volumetric loading of the influent was 0.055 kg/(m3·d), the average ammonia removal volumetric loading and sludge loading were 0.043 kg/(m3·d) and 0.16?kg/(kg·d), respectively. In addition, the average nitrite accumulation rate was 83.4% at this time. AOB population density and relative abundance increased from 4.5×104 CFU/mL to 1.5×107CFU/mL and from 0.18% to 7.25%, respectively, during start-up and stable operation of partial nitrification process. At the same time, NOB population density and relative abundance decreased from 2.0×105 CFU/mL to 1.5×104 CFU/mL?and from 5.51% to 2.14%, respectively. Conclusion] The expansion of AOB population was responsible for realization of partial nitrification and ammonia removal. High ammonia concentration and loading?also caused the activity inhibition of partial nitrification.