溶解氧对碳氮硫共脱除工艺中微生物群落影响解析

为了研究溶解氧对碳氮硫共脱除工艺中微生物群落的影响,探索供氧条件下提高单质硫转化率的机制,实验采用基因芯片GeoChip技术来解析不同曝气量下采集的污泥样品中的微生物群落结构特征.研究结果表明,微量的溶解氧能显著影响工艺中的微生物群落结构(P<0.001),相对较高浓度的溶解氧可以增加微生物的多样性但是却抑制了对溶解氧比较敏感的反硝化微生物的活性,导致工艺硝酸盐去除率下降.与反硝化微生物相比硫酸盐还原菌(sulfate-reducing bacteria,SRB)能抵抗更高浓度的溶解氧,因此工艺的硫酸盐还原过程未受到影响,一直保持较高的硫酸盐去除率.当曝气量为20 mL·min-1时单质硫的转化率最高,通过对sox(sulfur-oxidation)基因丰度分析和聚类分析发现,在该曝气量条件下sox基因的丰度最高,与厌氧条件相比有极其显著的差异.此外,GeoChip还检测到一些硫氧化细菌(sulfur-oxidizing bacteria,SOB)的丰度明显提高,证明适量的溶解氧能够刺激一部分SOB的生长与代谢.

Effect of Dissolved Oxygen on Microbial Community in Simultaneous Removal of Carbon, Nitrogen and Sulfur Process

In order to investigate the effect of dissolved oxygen (DO) on microbial community in simultaneous removal of carbon, nitrogen and sulfur process and reveal the mechanism of high elemental sulfur conversion rate under aerobic condition, GeoChip was employed to characterize the structure of microbial community. The results indicated that the microbial community structure significantly changed with different aerobic conditions (P<0.001). Diversity indices of microbial community increased at relatively high DO level. However, denitrifiers were greatly inhibited at this level due to the high sensitivity to DO. There was no significant change detected in the abundance of sulfate-reducing bacteria (SRB) with the changing DO. The relative abundance of sox gene showed significant difference between aeration rate of 20 mL·min^-1 and aeration rate of 0 mL·min^-1, which might suggest that the activity of sulfur-oxidizing bacteria (SOB) was obviously improved by DO. Moreover, cluster analysis of sox gene confirmed this suggestion, with higher signal intensity found in numbers of probes derived from SOB under such aerobic conditions. Overall, the results revealed a positive effect of micro-aerobic conditions on the simultaneous removal of carbon, nitrogen and sulfur process.