Microbial community structure and function in response to the shift of sulfide/nitrate loading ratio during the denitrifying sulfide removal process
Cong Huang, Zhi-ling Li, Fan Chen, Qian Liu, You-kang Zhao, Ji-zhong Zhou, Ai-jie Wang
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
Influence of acetate-C/NO3--N/S2- ratio to the functional microbial community during the denitrifying sulfide removal process is poorly understood. Here, phylogenetic and functional bacterial community for elemental sulfur (S0) recovery and nitrate (NO3−) removal were investigated with the switched S2−/NO3− molar ratio ranged from 5/2 to 5/9. Optimized S2−/NO3− ratio was evaluated as 5/6, with the bacterial genera predominated with Thauera, Enterobacter, Thiobacillus and Stappia, and the sqr gene highly expressed. However, insufficient or high loading of acetate and NO3− resulted in the low S0 recovery, and also significantly modified the bacterial community and genetic activity. With S2−/NO3− ratio of 5/2, autotrophic S2− oxidization genera were dominated and NO3− reduction activity was low, confirmed by the low expressed nirK gene. In contrast, S2−/NO3− ratio switched to 5/8 and 5/9 introduced diverse heterotrophic nitrate reduction and S0 over oxidization genera in accompanied with the highly expressed nirK and sox genes.
Keywords: Denitrifying sulfide removal process; Continuous stirred tank reactor (CSTR); Sulfide/nitrate loading ratio; Microbial community structure; Function.