短程硝化过程2种亚硝酸盐氧化菌抑制策略探讨

Discussion on inhibition strategies of two nitrite oxidizing bacteria in nitritation

为维持短程硝化稳定,保证亚硝酸盐高效积累,需要对污水处理系统亚硝酸盐氧化菌(NOB)的性质进行深入了解。分别对Nitrospira以及Nitrobacter的动力学参数,以及在活性污泥系统、生物膜系统、颗粒污泥系统中2菌属特性进行比较。经分析后认为,Nitrospira相对于Nitrobacter比增长速率较低,对O_2,NO_2^-底物亲和性较好,适宜生长于低浓度环境中,是A^2/O、短程硝化-厌氧氨氧化工艺中的主要NOB菌属;Nitrobacter则适宜在高浓度环境中生长。在颗粒污泥系统中,NOB主要处于污泥内部,由于缺乏O_2,NO_2^-更容易被淘汰出反应器。通过对比短程硝化主要控制参数,认为NOB的抑制策略包括:在活性污泥系统中维持合理的污泥龄(SRT)以及游离氨(FA)浓度;在生物膜系统中对溶解氧(DO)以及水力停留时间(HRT)进行联合控制;在颗粒污泥系统中维持适量剩余NH_4^+-N,并淘洗出掺杂其中的絮状污泥。此外,利用"饱食饥饿"效应间歇曝气并维持较低的曝停比同样有利于阻止亚硝酸盐被NOB进一步氧化,保证短程硝化稳定运行。

For purpose of maintaining the stability of nitritation, ensuring the efficiency of nitrite accumulation,it’s essential to have insight into the properties of ordinary nitrite oxidizing bacteria(NOB) species in wastewatertreatment systems. The kinetic parameters of Nitrospira and Nitrobacter, and the characteristics of the two genusbacteria in the activated sludge system, biofilm system, and granular sludge system were compared. Nitrospira had a lower specific growth rate and a better affinity for O2 and NO2- substrates than Nitrobacter. The formerbacteria were suitable for growth in low concentration of substrates, which was considered as the main NOB genusin A2/O and nitritation-anammox process, while the latter ones were suitable for growth in high concentration ofsubstrates. In granular sludge system, NOB mainly existed in the interior of the sludge, and were easy to beeliminated from the reactor due to the lack of O2,NO2- substrates. Through comparing the main controlparameters for nitritation, the NOB inhibition strategies were proposed as: maintaining a reasonable sludgeretention time(SRT) and free ammonia(FA) concentration in activated sludge system, adjusting dissolvedoxygen(DO) and hydraulic retention time(HRT) systematically in biofilm system, sustaining an appropriateamount of residual NH4+-N, and washing out the flocculation from granular sludge. Furthermore, using intermittentaeration based on'cyclic feeding'and maintaining lower ratio of aeration and anaerobic time were propitious toprevent further oxidation of nitrite by NOB, trigger the stability of nitritation.