A Survey on Various Carbon Sources for Biological Hydrogen Production via the Water-Gas Reaction Using a Photosynthetic Bacterium (Rhodospirillum rubrum)

Growth model of anaerobic photosynthetic bacteria on various carbon sources for fermentative hydrogen production growth from synthesis gas was investigated. It was found that the rate of utilization of carbon monoxide (CO) by Rhodospirillum rubrum on acetate was growth related. A biologically based water-gas shift reaction was catalyzed by the specific bacterium at ambient temperature to convert the gaseous substrate, CO to carbon dioxide, while simultaneously convert water to a useful product, molecular hydrogen. Experiments were conducted to measure the specific CO uptake and hydrogen production rates. Also, effect of initial organic substrate concentration was investigated. The microorganism was grown on formate, acetate, malate, glucose, fructose, and sucrose. The modified Teissier and Contois equations were further developed for the growth model based on existing theory and experimental data. It was also found that the improvement in the yield of hydrogen production using acetate as a suitable substrate for R. rubrum, resulted in 0.87 mmole H ₂ /mmole CO. The obtained hydrogen yield of R. rubrum on acetate was 87% of stoichiometric conversion. The main objective of this research was to demonstrate that the biological hydrogen production may efficiently be implemented as an alternative energy for fossil fuel replacement in the future.

Keywords:

• biological hydrogen production
• growth models
• Rhodospirillum rubrum
• synthesis gas
• water-gas shift reaction

Acknowledgments

The present research was made possible through an IRPA grant No. 03-02-05-9016, by Universiti Sains Malaysia and Ministry of Science, Technology and Innovations (MOSTI). The authors wish to thank Research Creativity and Management Office (RCMO), University Science Malaysia and MOSTI for their financial support.