Effects of culture and medium conditions on hydrogen production from starch using anaerobic bacteria.

The influences of initial pH (4.0-9.0), iron concentration (1.2-100 mg/l), nitrogen concentration (NH4HCO3, 0.56-11.28 g/l) and starch concentration (2-32 g/l) on hydrogen production and volatile fatty acid (VFA) production were studied. Batch experiments using starch as a substrate and mixed bacteria were conducted at 35 degrees C. The optimum pH, iron concentration and nitrogen concentration for hydrogen production at a starch concentration of 15 g/l were 7.0-8.0, Fe2+ 10 mg/l and NH4HCO3 5.64 g/l, respectively. The typical VFAs were acetate, propionate and butyrate, with acetate as the major component. The maximum specific hydrogen production rate of 146 ml/g-VSS.d (volatile suspended solids, VSS) and the hydrogen yield of 178 ml/g-starch were obtained at a starch concentration of 15 g/l under optimum environmental conditions. The maximum hydrogen yield of 194 ml/g-starch was obtained at a starch concentration of 2 g/l. The maximum specific hydrogen production rate of 237 ml/g-VSS.d was found at a starch concentration of 24 g/l.