曝气强度对同时硝化反硝化(SND)脱氮过程中N_2O排放的影响

Effect of aeration strength on nitrous oxide emission during simultaneous nitrification and denitrification

为了控制污水脱氮中N2O排放,在不同曝气强度下研究了好氧硝化段同时硝化反硝化(SND)系统的N2O排放特性,并采用PCR-DGGE技术分析微生物群落特征。结果发现,随着曝气强度的增强,系统总氮去除率下降,但脱氮中N2 O-N所占比例则上升,实验中从低到高3个曝气强度下,总氮去除率分别为80.01%、65.28%和58.62%,脱氮中N2 O-N所占的比例为1.89%、7.84%和9.20%。PCR-DGGE分析显示,和低曝气强度下相比中、高曝气强度下系统微生物群落发生明显变化,但中曝气强度和高曝气强度下系统微生物群落表现出较高相似性。这表明,不同曝气强度下系统N2O排放受到氮素转化和微生物群落变化的影响。适宜曝气强度不仅提高总氮去除率,还可有效控制N2O排放。

For the purpose of controlling nitrous oxide （N2O） emission from wastewater treatment systems, the N2O emission under different aeration rates from a simultaneous nitrification and denitrification system were characterized. PCR-DGGE method was applied to characterize microbial communities in the system. Results showed that nitrogen removal efficiency of the system decreased as the increase of aeration rates, but the ratio of N2O to the total N removal increased. Three aeration rates were applied. From low to high aeration rate, nitrogen removal efficieneies were 80.01% , 65.28% and 58.62% , respectively. The amount of N：O emitted accounted for 1.89% , 7.84% and 9.20% of total N removal. PCR-DGGE analysis showed that microbial communities un- der low aeration rate were significantly different from those under medium and high aeration rates, but the com- munities under medium and high aeration rates were not significantly different. These data suggested that varia- tion ofN2O emission under different aeration rates was controlled by different microbial communities. Optimizing the aeration rates would lead to control of N2O emission from wastewater treatment systems.