Insights into the effects of operating parameters on sulfate reduction performance and microbial pathways in the...

Sulfate-reducing bacteria (SRB)-based anaerobic process has aroused wide concern in the treatment of sulfate-containing wastewater. Chemical oxygen demand-to-sulfate ratio (COD/SO₄^2-) and HRT are two key factors that affect not only the anaerobic treatment performance but also the activity of SRB. In this study, an anaerobic sequencing batch reactor was constructed, and the effects of different operating parameters (COD/SO₄^2-, HRT) on the relationship of sulfate (SO₄^2-) reduction performance, microbial communities, and metabolic pathways were comprehensively investigated. The results indicated that the SO₄^2- removal rates could achieve above 95% under different operating parameters. Bioinformatics analysis revealed that microbial community changed with reactor operation. At the genus level, the enrichment of Propionicclava and Peptoclostridium contributed to the establishment of a homotrophic relationship with Desulfobulbus, the dominant SRB in the reactor, which indicated that they took vital part in maintaining the structural and functional stability of the bacterial community under different operating parameters. In particular, an increasing trend of the relative abundance of functional genes encoding dissimilatory sulfate reduction was detected with the increase of COD/SO₄^2-, which indicated high SO₄^2- reduction potentials. This knowledge will help to reveal the mechanism of the effect of operating parameters on the anaerobic sulfate removal process, thus providing effective guidance for the targeted regulation of anaerobic sequencing batch bioreactors treating SO₄^2--containing wastewater.