Elucidating the effect of mixing technologies on dynamics of microbial communities and their correlations with granular sludge properties in a high-rate sulfidogenic anaerobic bioreactor for saline wastewater treatment

In this study, three lab-scale anaerobic sulfidogenic bioreactors were operated independently using three different mixing modes (hydraulic, mechanical and pneumatic). One-way ANOVA test indicated various performance parameters (e.g. sulfate reduction and sulfide production) and granular sludge properties (e.g. EPS and particle size) statistically different in three mixing modes. Principal component analysis (PCA) and OTUs-based network demonstrated bacterial composition greatly varied among the three mixing modes. The phylum Proteobacteria was predominant among the bacterial communities, and the genus Desulfobacter (35.1% in hydraulic, 31.1% in mechanical and 27.4% in pneumatic sample) was the most dominant SRB. The PCA/Pearson's correlation analysis confirmed SRB had significant positive relationship with sludge properties (e.g. particle size). PICRUSt data highlighted that bacterial communities contained diverse predicted functions including sulfur metabolism enzymes (sulfite reductase and adenylylsulfate reductase). The findings of this research could be helpful for selection of an appropriate mixing technology for anaerobic sulfidogenic or similar bioprocess.