8-09: Influence of organosolv pretreatment conditions in glucose and ethanol production from sugar cane bagasse

The logistics of sugarcane industry makes its bagasse the most promising lignocellulosic raw material for ethanol production in Brazil. This material is composed by app. 40% of cellulose, 30% of hemicellulose and 30% of lignin. In this work, the influence of the Organolv pretreatment with ethanol, on the chemical composition and structure of sugarcane bagasse (SB) was evaluated. The efficiency of the enzymatic hydrolysis of cellulose and of the production of ethanol was assessed for all the pretreatment conditions, too. 

SB was treated in a 2.0L Parr® reactor with ethanol solutions (30-70% v/v), solid/liquid ratio of 1:10, at 150°C/30min; 170°C/60min and 190°C/90min. SB was characterized, chemically and by SEM, prior and after each pre-treatment. 20FPU/g of solid of Acellerase® 1500 were used for hydrolysis assays (in shaker at 200 rpm and 50°C). After that, ethanolic fermentations using commercial Saccharomyces cerevisiae were performed (30°C, 250rpm). Conditions with high degree of severity (DS 5,9) led to the lowest yields of solid (45.9-54.1%). With ethanol 50% v/v it was possible to extract between 88.1% and 89.1% of the initial lignin and hemicelullose, with almost complete preservation of the cellulosic fraction (less than 1% of loss). Preliminary hydrolysis assays had 60% of conversion and reached 82% of the theoretical fermentation yield. It can be inferred that even with a high extraction of lignin, the accessibility of the enzymes to the cellulose was still hindered.