Dynamics of nitrogen transformation and bacterial community with different aeration depths in malodorous river

In this research, the dynamics of nitrogen transformation and bacterial community in malodorous river were investigated with different aeration depths. Computational flow dynamics (CFD) and Reynolds number (Re) were specially used to characterize the hydrodynamics condition under different aeration depths. The results indicated that aeration depth had vital impact on nitrogen transformation and bacterial community structure. It was found that a range of aeration depth (0.20-0.45 m above sediment-water interface) facilitated the removal of NH₄⁺-N and TN with Re ranging between 6211 and 8930. Proteobacteria took over Firmicutes to become the predominant phylum (36-78%) under aeration, and the main subdivisions of γ-, β- and δ-Proteobacteria also varied greatly with different aeration depths. Interestingly, there was a marked shift of the inferentially identified dominant functional role within Proteobacteria from organic-matter degradation to nitrogen metabolism and then to sulfur metabolism as well as the coupling of nitrogen and sulfur with the increase of disturbance. The redundancy analysis (RDA) further confirmed the importance of aeration disturbance in shaping bacterial community. These findings help to gain improved understanding of endogenous N-behavior and aquatic microbial ecology, and underline the need for integrating the hydrodynamics factors with microbial community.