Biohydrogen Production from Liquid and Solid Fractions of Sugarcane Bagasse After Optimized Pretreatment with Hydrochloric Acid

This work determined the optimal conditions to pretreat sucargane bagasse with HCl by using the liquid and the solid fractions resulting from the bagasse pretreament as substrate for fermentative hydrogen production by a mixed culture. A 2 3 full factorial central composite design (star configuration) helped to determine how temperature, time, and acid concentration affected the total monosaccharides (TM), total reducing sugars (TRS), and total inhibitors (TI) concentrations in the liquid fraction. Temperature, time, and acid concentration impacted the TRS and TM concentrations, but these variables did not influence the TI concentration significantly. The optimal pretreatment conditions were HCl at 7.36 % (v/v), 96.8 °C, and 441.6 min, which afforded the highest TRS concentration in the liquid hydrolysates. The liquid fraction obtained from the bagasse pretreated with acid under the optimal conditions (designated liq) was not suitable for H 2 production by the mixed culture before treatment of the fraction with activated carbon. The solid residual bagasse (designated sol) alone afforded 6.0 mL of H 2 /g of bagasse. Liq treated with 10 % (m/v) activated carbon, to give liq + C, and sol added with the enzyme Celluclast ® 10 U g −1 , to afford sol + E, yielded 45.3 and 7.8 mL of H 2 /g of bagasse respectively, which amounted to 53.1 mL of H 2 /g of bagasse. The volumetric productivities—1450 and 1423 mL of H 2 L −1 d −1 for liq + C and sol + E, respectively—are the highest ever reported in the literature for H 2 production from sugarcane bagasse by a microbial consortium.