同步硝化反硝化(SND)过程污泥聚集状态对N2O释放的影响

Effect of Microbial Aggregation State on Nitrous Oxide Emission in Simultaneous Nitrification and Denitrification Nitrogen Removal Process

为实现SND高效生物脱氮及N2O减量化释放的双重目标,采用气升环流生物反应器,在实现SND高效脱氮的基础上研究了污泥的聚集状态与N2O释放特征之间的关系.采用关键酶酶促反应速率法评估了不同聚集状态污泥的硝化/反硝化活性,在相关理论分析的基础上,进行了污泥聚集状态的优化选择.结果表明,SND体系内活性污泥的聚集状态不同会造成脱氮过程N2O释放量的显著差异(≥40%).将污泥聚集体的结构控制在粒径较小(≤0.9 mm)、致密程度适中的状态,既能保持较高的SND效率(≥70%),又能实现N2O的减量化释放.在实验界定的体系内,将污泥聚集体的粒径优化控制在0.45～0.9 mm范围,能同时得到较高的硝化活性[氨氧化细菌活性为0.17 mg.(g.min)-1,亚硝酸盐氧化细菌活性为0.74 mg.(g.min)-1]和反硝化活性[NO 3--N的消耗速率为0.47 mg.(g.min)-1,NO 2--N的消耗速率为0.22 mg.(g.min)-1].与对照相比,实现N2O的减量化释放达32.55%.

In order to realize efficient nitrogen removal and N2 O emission reduction,air lift circulation bioreactors were applied to study the relationship between activated sludge aggregation state and N2 O emission characters on the basis of high nitrogen removal performance.The nitrification/denitrification activity of different microbial aggregates was evaluated by key enzyme action ratio method.Combined with correlative theoretical analysis,the optimal aggregation state with efficient nitrogen removal and N2O emission reduction was selected.According to the results,different activated sludge aggregation state in SND would lead to significant difference of N2 O emission amount（≥40%）.The smaller aggregates（≤0.9 mm） with moderate compactness could keep high SND efficiency（≥70%） and achieved N2 O emission reduction.In experimental defined system,the optimal diameter of aggregates was in the range of 0.45-0.9 mm,which could obtain higher nitrification activity [ammonia-oxidizing bacteria activity was 0.17 mg·（g·min）^-1,nitrite-oxidizing bacteria activity was 0.74 mg·（g·min）^-1] and denitrification activity ·（g·min）^-1,NO-2-N consumption rate was 0.22 mgmg·（g·min）^-1].Compared to the control group,N2O accumulated emission amount in the reactor with aggregates of 0.45-0.9 mm could be realized reduction more than 32.55%.