Tuesday, April 20, 2010
10-17

Method to obtain biomass hydrolyzate with high glucose concentration via enzymatic saccharification of cellulosic biomass

Makoto Ikeo, Daisuke Taneda, and Yoshiki Ueno. Research and Development Division, JGC Corporation, Higashi-ibaraki-gun Ooarai-chou Narita-Chou 2205, Ibaraki-ken, 311-1313, Japan

The energy consumption in the distillation step in the bioethanol production can be significantly reduced when the ethanol concentration after fermentation is higher than 10wt%. To obtain this ethanol concentration, the glucose concentration of the biomass hydrolyzate entering the fermentation step must be above 200g/L. This study focused on producing a biomass hydrolyzate with a glucose concentration of 200g/L by enzymatic hydrolysis of lignin-removed cellulosic biomass. In this study, filter paper and paper pulp were used to simulate the lignin removed cellulosic biomass, and the substrate concentration was increased under constant cellulase concentrations. The target value was achieved when 26wt% filter paper slurry was hydrolyzed for 20 days with the cellulase loading of 22.6FPU/g-cellulose. The glucose yield in this case was 61.8%. To economically produce the hydrolyzate with the target glucose concentration, the cellulase loading must be decreased and the yield must be increased. The glucose yield decreases linearly as the substrate concentration increases, and under the lower cellulase loadings, the glucose concentration will not reach 200g/L. Thus, the recycling of the cellulase was considered, and the adsorptive characteristics of cellulase were studied. The experiments showed that the cellulase adsorbed to the substrates desorbed as the saccharification progressed. The desorbed cellulase adsorbed again when a fresh substrate was added. From these data, we propose the counter current saccharification process. The proposed process involves recycling of the cellulase and the hydrolysis of residues, using a series of reactors and solid liquid separators.

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