Monday, May 4, 2009
9-53
Improvement of high-solid slurries mixing for enzymatic hydrolysis of pretreated rice straw
Sheng-Hsin Chou, Hung-Chang Huang, Deng-Chieh Hsu, and Gia-Luen Guo. Environment and Energy Technology Center, Institute of Nuclear Energy Research, no. 1000, Wenhus Road, Jiaan Village, Longtan,Taoyuan, Taoyuan, Taiwan
One of the prerequisites for the efficient utilization of lignocelluloses for ethanol production is to provide a hydrolysate with a high glucose concentration. This was shown significant benefits on capital costs and production cost due to reduction in size of equipment and energy utilization for distillation, respectively. To obtain a hydrolysate with high glucose concentration, high-solid substrate loading for enzymatic hydrolysis is necessary. However, high solid slurries often makes mixing problem associated with the decrease of sugar yield from enzymatic saccharification and causes the power consumption increase in reactors. In this study, a high solid processing approach was developed to provide the enzymatic hydrolysis of pretreated rice straw under a solid content at 25% and above. The pretreated solid residues were prepared by a twin-screw extrusion pretreatment with dilute sulfuric acid. The pretreated lignocellulosic residues were shown lower viscous heterogeneous substrates which sufficiently to perform in high-solids saccharification. The viscosity was in the range of 3500-4000 cp under a 25% of initial solid content. Moreover, a 100L horizontal reactor with a design of oblique-scraped blade was developed for enzymatic hydrolysis. The decrease of sugar yield was below 5% with the increase of initial solid content from 15% to 25%. Nearly 80g/L and above of finial glucose concentration were observed from enzymatic hydrolysis. The power consumption was further compared for enzymatic hydrolysis at batch or fed-batch mode. This was contributed to increase the potential of high-solid enzymatic hydrolysis under industrial interest.