Performance and microbial mechanism in sulfide-driven autotrophic denitrification by different inoculation sources in...

To develop a reliable sulfide (S^2-) autotrophic denitrification (SAD) process under S^2- and SO₄^2- salinity stresses, the biofilm performance and microbial mechanisms were comparatively studied using different inocula of activated sludge (AS) and intertidal sediment (IS). Biofilm IS enriched more denitrification genes (0.34 %) and S^2- oxidation genes (0.29 %) than those with AS. Higher denitrification performance was obtained under S^2- (100 mg/L) and SO₄^2- (5-15 g/L Na₂SO₄) stresses, but no significantly differences were observed under levels of 0-200 mg/L S^2- and 30 g/L Na₂SO₄. Notably, biofilm samples in SAD systems with IS still had more S^2- oxidation genes at high S^2- levels of 100-200 mg/L and Na₂SO₄ level of 30 g/L. The key functional genus Thiobacillus accumulated well at 30 g/L Na₂SO₄, but was strongly inhibited at 200 mg/L S^2-. The findings were advantage to SAD application under sulfide and salinity stresses.