Influence of iron on sulfide inhibition in dark biohydrogen fermentation

Sulfide impact on biohydrogen production using dark fermentation of glucose at 37 °C was investigated. Dissolved sulfide (S2−) at a low concentration (25 mg/L) increased biohydrogen production by 54% relative to the control (without iron addition). Whereas on initial dissolved S2− concentration of 500 mg/L significantly inhibited the biohydrogen production with total cumulative biohydrogen decreasing by 90% compared to the control (without iron addition). At sulfide concentrations of 500 mg S2−/L, addition of Fe2+ at 3–4 times the theoretical requirement to precipitate 100% of the dissolved S2− entirely eliminated the inhibitory effect of sulfide.

► Sulfide inhibition on dark biohydrogen fermentation has been studied. ► Low sulfide concentration (25 mg/L) significantly enhanced the hydrogen production. ► High sulfide concentrations (500 mg/L) completely inhibited hydrogen production. ► Addition of ferrous iron entirely eliminated the inhibitory effect of sulfide.