Hydrogen‐gas production with Citrobacter intermedim and Clostridium pasteurianum

Citrobacter intermedius and Clostridium pasteurianum were grown in 14‐dm3 batch reactors on glucose and measured for biomass and H2 production. Gas production with C. intermedius was found to be growth related, whereas that with C. pasteurianum was entirely produced during the stationary phase of growth. The maximum yield and productivity of H2 with C. intermedius was 60% H2 or 1 mol of H2 mol−1 of glucose at a maximum of 3.7 mmol of H2 h−1 and 85% H2 or 1.5 mol of Ha mol−1 of glucose at a maximum of 9.0 mmol of H2 h−1 with C. pasteurianum. The overall H2 productivity (QH2) was 2.5 mmol of H2 h−1 g−1 dry biomass for C. pasteurianum at a glucose concentration of 7.6 g dm−3. As the glucose concentration was increased from 7.6 to 15.4 g dm−3, up to 44% of the gas produced with C. pasteurianum was growth associated. The remainder of the gas was produced in the stationary phase. In this case the overall Ha productivity (QH2) was 1.2 mmol of H2 h−1 g−1 dry biomass. The comparative experiments indicate that maximum yields and rates of H2 production were achieved with C. pasteurianum.