Integrated dark- and photo-fermentation: Recent advances and provisions for improvement

Biohydrogen production from waste materials has been recognized as the promising step towards bioremediation and green energy generation. A large number of microorganisms and diverse range of waste materials have been widely studied for H2 production. However, H2 production efficiencies vary depending upon the type of organism, type and composition of waste, physiological conditions, and the reactor used. Some research groups suggest integrated dark- and photo-fermentation processes for optimum utilization of the substrate and higher H2 yield per mol of substrate. Integration of these two processes increases the H2 yield, and seems suitable for commercial H2 production. Review and evaluation of the published data suggest that integrated system holds greater promise for commercial H2 production. The present review deals with the possibilities of enhancing H2 yield by integrating dark- and photo-fermentation for commercial use.