Effect of Ni~(2+) Concentrations on Fermentative Hydrogen Production by Mixed Cultures

The effect of the Ni2+ concentrations on fermentative hydrogen production by mixed cultures was investigated.The results show that at 35 ℃ and initial pH 7.0,the hydrogen production rate can be enhanced with increasing Ni2+ concentrations from 0 to 0.2 mg/L.The cumulative hydrogen yield and specific hydrogen yield increase with increasing Ni2+ concentrations from 0 to 0.1 mg/L,with the maximums being 288.6 mL and 296.1 mL/g glucose respectively.When Ni2+ concentration ranges from 0 to 50 mg/L,the major aqueous metabolites produced by mixed cultures are ethanol,acetic acid and butyric acid,no propionic acid is detected.Ni2+ concentration has little effect on the glucose degradation efficiency with increasing concentrations from 0 to 50 mg/L.The biomass increases with increasing Ni2+ concentrations from 0 to 0.1 mg/L and the maximum specific biomass yield of 232.5 mg/g glucose is obtained.The final pH value is lower than the initial pH with increasing Ni2+ concentrations from 0 to 50 mg/L.