Regulation of influent sulfide concentration on anaerobic denitrifying sulfide removal

ABSTRACT

The objective of this study is to find a comprehensive regulation for sulfide removal and elemental sulfur transformation based on the denitrifying sulfide removal process. The experiment was performed based on several influent sulfide concentrations (150–600 mg/L) and nitrate-to-sulfur (N/S) molar ratios (0.5–2.0) at reaction times of 24 and 48 h. Sulfide and nitrate removals were mainly dependent on the influent sulfide concentration at sulfide concentrations of 150–200 and 400–600 mg/L, but on the N/S ratio at sulfide concentrations of 250–350 mg/L. Up to 99.7% and 93.8% of sulfide and nitrate were removed, respectively, with 26.5% of elemental sulfur formed at sulfide concentrations of 250–350 mg/L (N/S of 1.0). Only 4–9.4% of elemental sulfur was formed, with sulfide and nitrate removals of 99.9% and 98.7%, respectively, at sulfide concentrations of 150–200 mg/L. Meanwhile, 46.9–94.7% of sulfate was formed with a nitrogen gas conversion rate of 18.2–57.1%. Fewer microorganisms were detected by fluorescence in situ hybridization (FISH) at high sulfide concentrations of 400–600 mg/L, suggesting that the processes of anaerobic denitrification and desulfurization were inhibited.

KEYWORDS:

• Anaerobic denitrifying sulfide removal
• influent sulfide concentration
• N/S molar ratio
• elemental sulfur
• FISH

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by National Natural Science Foundation of China [grant numbers 51368029, 51378413, 51778524]; Natural Science Foundation of Shaanxi Province [grant number 2016JM5038]; National Key Research and Development Program of China [grant number 2016YFC0400706].