Bioaugmented cellulosic hydrogen production from cornstalk by integrating dilute acid-enzyme hydrolysis and dark fermentation

The cellulosic hydrogen production from cornstalk based on the integrating dilute acid with enzymatic hydrolysis was investigated using response surface methodology (RSM). The dilute acid pretreatment of cornstalk with the concentration of 1.5% H2SO4, 121 degrees C and 60 min was found to be most effective in the first prehydrolysis stage. Thereafter, the process parameters of enzymatic hydrolysis of the solid residue, which derived from acid-pretreated cornstalk, were further optimized by a three factor-five level central composite design (CCD) with temperature (X-1), pH (X-2), and enzyme loading (X-3) as the independent variables. The optimal parameters of enzymatic hydrolysis of substrate were observed to be 52 degrees C of temperature, pH 4.8 and 9.4 IU/g of enzyme loading. In this case, the total soluble sugar obtained in the hydrolysis stages was 562.1 +/- 6.9 mg/g-TVS, and the maximum hydrogen yield from cornstalk by anaerobic mixed microflora was 209.8 ml/g-TVS. Biodegradation mechanism of cornstalk for hydrogen production was further discussed based on analyzing changes in the physical structure and chemical composition of cornstalk during the hydrolysis and fermentation processes. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.