Bio-Hydrogen Potential Of Easily Biodegradable Substrate Through Dark Fermentation

For hydrogen production through dark fermentation of glucose, a continuously stirred 1-liter bioreactor was inoculated with yard waste compost and operated at 55 °C with fed-batch runs. The reducing pH was regulated automatically by using pH transmitter and kept constant at 5.4. In this way, no methane was generated in any of the fed-batch runs and H2 yield in the range of 0.25 to 1.75 mol H2/mol glucose consumed was obtained by inhibiting methanogenic H2 consumption. Astonishingly, the highest H2 yield was achieved with fresh inoculum which was neither heat treated nor acclimated. However, yield was not steady and decreased due to shift in metabolic pathway from acidogenesis to ethanol fermentation subsequent to high H2 partial pressure. Effluent ethanol concentrations above 400 mg/l after high H2 yielding runs were indication of this metabolic shift.