Improvement of Biohydrogen Production under Increased the Reactor Size by C. acetobutylicum NCIMB 13357

Problem statement: One of the main factors influenced the bacterial productivity and total yield of hydrogen is the partial pressure of produced gas. A novel solution to enhance the bacterial productivity was through reduction of gas pressure. Approach: Increasing the reactor size showed to enhance the bacterial production of hydrogen. Results: The technique of increasing reactor size resulted to enhance the hydrogen yield (Y_P/S) from 269 mL g^-1 glucose utilized to maximum yield of 448 mL g^-1 glucose utilized by using 125 mL and 2 L reactor size respectively. The hydrogen productivity was also enhanced from 71 mL^-1 h^-1 to maximum of 91 mL L^-1 h^-1 was obtained by using 125 mL and 1 L reactor size respectively. Biomass concentration was enhanced from 1.03 g L^-1 to maximum of 1.68 g L^-1 by using 125 mL and 2 L reactor size were used respectively, hydrogen yield per biomass (Y_P/X) of 267 mL g^-1 L^-1, biomass per substrate utilized (Y_X/S) of 0.336 and produced hydrogen in gram per gram of glucose utilized (Y_H2/s) of 0.04 when 2 L reactor size was employed. Conclusion: By using bigger reactor size, the effect of gaseous products in fermentation medium was reduced and enhanced both bacterial productivity and biomass concentration.