Enhanced bio-hydrogen production from corncob by a two-step process: Dark- and photo-fermentation

Enhanced bio-hydrogen production from pretreated corncob by integrating dark-fermentation with photo-fermentation process was investigated in this study. In the first step, the maximum bio-hydrogen yield and rate from corncob by dark-fermentation was 120.3 ± 5.2 mL H2/g-corncob and 150 mL H2/(L h), respectively. In the second step, a hydrogen yield of 713.6 ± 44.1 mL H2/g-COD was obtained from digesting the effluent of dark-fermentation by photosynthetic bacteria. Meanwhile, COD removal efficiency achieved 90%. Bio-hydrogen production in the first step was mainly attributed to the bioconversion of the reducing sugars and oligosaccharides in the hydrolyzate of corncob. Bio-hydrogen production in the second step was due to the biodegradation of acetic acid, butyric acid, butyl alcohol and ethanol in the effluent of dark-fermentation.