Sweet Sorghum Juice as an Alternate Substrate for Fermentative Hydrogen Production: Evaluation of Influencing Parameters Using DOE Statistical Approach

Biohydrogen production using agro-industrial by-products has considerable practical importance. Sweet sorghum is an ideal feedstock for biofuel production in the semi-arid and arid climatic regions. In the present investigation, the juice of SSV 74, a sweet sorghum variety, was examined as a novel substrate for biohydrogen production. The impact of medium pH, substrate, inoculum level and incubation temperature were analyzed at individual and interactive levels on biohydrogen production. Substrate level concentration and pH of the fermentation medium played a critical role on overall biohydrogen production at individual level, and indicated >90 % influence on product yield. On the other hand at interactive level; pH of the fermentation medium, inoculum and substrate concentrations revealed maximum severity index of 78 % (43 % for medium pH vs inoculum concentration and 35 % for inoculum vs substrate concentration). Overall, biohydrogen production yield was enhanced from 283 to 546 mL/3.25 g glucose equivalents of juice upon statistical optimization leading to a >190 % of H2 yield. Along with the H2 production, various acid intermediates were produced with acetate in maximum concentration indicating the occurence of acetogenic fermentation.