Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
The objective of this work was to evaluate the hydrolysis and alcoholic fermentation stages of the sugar cane bagasse (SCB) for second generation ethanol production. Hydrolysis experiments were carried out employing 8, 10, 15 and 20 (m/v) solid loads. Samples of in natura and steam exploded SCB were submitted to different pretreatment sequences: water and 4.0% NaOH solution; 1.0% H2SO4 solution and 4.0% NaOH; 1.0% H2SO4 solution and 7.0% NaOH solution; only 7.0% NaOH solution; aqueous ammonia; only water. All samples were characterized (chemical analysis and SEM ). Hydrolysis experiments using different enzyme loads (33, 65 and 98 FPU/g-cellulose, Accelerase 1500) were carried out in three different configurations: SSF (Separated Saccharification and Fermentation), SHF (Simultaneous Hydrolysis and Fermentation), and FB (Fed-Batch). Concerning cellulose loss, SCB pretreated with water and 4.0% of NaOH solution presented the best result (23.9%). For this case, the hemicellulose and lignin removal was 73.7% and 79.1%, respectively. For the others pretreatment sequences the hemicellulose and lignin removal range from 72.3 to 92.2%. For lignin removal the values range from 60.0% and 88.9%. Experiments employing high solid load (20%) resulting in a more concentrated hydrolyzed (ca. 110 g/L). In this experiment it was achieved 64% of cellulose to glucose conversion (34 h). The fermentation experiments were carried out employing Saccharomyces cerevisiae (lyophilized commercial). Experiment conducted in the SSF configuration achieved 86.5% of cellulose to ethanol conversion in 14 h. Experiment carried out in SHF configuration achieved 63.2% of cellulose to ethanol conversion in 37 h.