高溶解氧条件下不同曝气量对短程硝化性能及微生物特征的影响

Effects of aeration rates on the performance and microbial characteristics of partial nitrification under high dissolved oxygen condition

短程硝化过程是短程生物脱氮工艺中的限速步骤,在保证稳定亚硝化率的前提下,提高曝气量能够提高好氧氨氧化菌的活性,进而提高氨氧化速率.本文在序批式反应器中,通过改变曝气量,在高溶解氧条件下,考察不同曝气量对短程硝化的性能及微生物的影响.结果表明,随着曝气量的增大,氨氧化速率不断升高.单位体积曝气量为0.8、1.7、3.3、5.0 L·min^(-1)·L^(-1)时,氨氧化率维持在50%左右,亚硝酸盐氮积累率稳定在99%以上,平均氨氧化速率分别为0.88、0.96、1.29和1.32 mg·L^(-1)·min^(-1).高通量测序分析表明,不同曝气量条件下,反应器中好氧氨氧化菌的优势菌属均为Nitrosomonas,而亚硝酸盐氧化菌都被有效抑制,Nitrospira丰度很低.此外,检出Acidovorax、Denitratisoma、Hyphomicrobium、Ignavibacterium等多种反硝化细菌,这些反硝化菌能够与好氧氨氧化菌共同作用,使系统发生少量内源同步硝化反硝化.综合考虑曝气能耗和反应速率,曝气量为3.3 L·min^(-1)·L^(-1)时,可实现控制短程硝化工艺的低耗高效运行.

Partial nitrification is the rate-limiting step in the short-cut biological nitrogen removal process.On the premise of stable nitrite accumulation,increasing aeration rate can improve the activity of aerobic ammonia-oxidizing bacteria(AOB),and then accelerate the ammonia oxidation.In this study,the effects of aeration rates on the performance and microbial characteristics of partial nitrification in SBR under high dissolved oxygen conditions were investigated.The results showed that the ammonia oxidation rate increased with the elevation of the aeration rate.When the aeration rate per unit volume was 0.8,1.7,3.3 and 5.0 L·min^(-1)·L^(-1),the ammonia oxidation rate stayed at about 50%,the nitrite accumulation rate was stable above 99%,and the average ammonia oxidation rates were 0.88,0.96,1.29 and 1.32 mg·L^(-1)·min^(-1),respectively.The high-throughput sequencing results that Nitrosomonas was the dominant AOB under different aeration rates,while nitrite-oxidizing bacteria were effectively inhibited,with a very low abundance of Nitrospira.Additionally,a variety of denitrifying bacteria were detected,including Acidovorax,Denitisoma,Hypomicrobium and Ignavibacterium.These denitrifying bacteria can interact with AOB to make a small amount of endogenous simultaneous nitrification and denitrification in the system.Considering the aeration energy consumption and the reaction rate,when the aeration rate is 3.3 L·min^(-1)·L^(-1),the partial nitrification process can achieve prominent ammonia oxidation with low consumption.