Monday, April 19, 2010
LL Conference Facility (Hilton Clearwater Beach)
The aim of this work was to select an efficient impeller to be used in a stirred reactor for the enzymatic hydrolysis of sugar cane bagasse. Bagasse (100g/L d.w.), pretreated by steam for cattle feed, was used in all experiments. The process was studied concerning the rheological behavior of the biomass hydrolysate and the conversion of the bagasse polysaccharide part into glucose and total reducing sugars. These parameters were used to model the power required for the impeller operation at pilot (100L) scale using empiric correlations according to Nagata (1975). In all experiments, that were carried out with an enzyme load of 10 FPU/g of substrate, it was used a cellulolytic and xylanolytic enzymes blend produced by Aspergillus awamori and Trichoderma reesei RUT C30. Hydrolysis was performed during 36 hours with periodical sampling for the measurement of glucose, reducing sugar concentration and viscosity. The mixture presented pseudoplastic behavior. This rheological model allowed the comparison of disk flat blade (Rushton turbine) and pitched blade, 45° impellers performance. The simulation showed that the pitched blade 45° consumed 10 fold less energy than the Rushton turbine. Sugar syrups presented 22 g/L of glucose, corresponding to 45% cellulose conversion. In the continuation of this work the pitched blade, 45° impeller will be tested for the enzymatic hydrolysis of sugar cane bagasse pretreated by milling and steam explosion aiming the improvement of the hydrolysis yields. The separation of the sugar syrups from the lignin residue has been also studied.