2-01: Optimization and modeling of phosphoric-acid-pretreated sugarcane bagasse

In order to make use of lignocellulose for the production of chemicals and fuels, it is necessary to disrupt its structure through pretreatment.  In this study, we looked at a wide range of conditions for steam explosion combined with dilute phosphoric acid in order to optimize the pretreatment of sugarcane bagasse.  A total of 25 different conditions were tested with varying acid concentrations, temperatures, and residence times to determine the best conditions to provide high sugar yields combined with low inhibitor concentrations.  The data was used to create a model for phosphoric acid pretreatment of sugarcane bagasse based on Chum, et al. (1990) calculations that gave a good fit and had a Pearson correlation coefficient of 0.875.  Of all the combinations tested, there were six conditions that resulted in >70% xylan solubilization.  Using furfural as an indicator of inhibitor concentration, the two with the lowest furfural concentrations were 180°C, 1.0% acid, 10 min (Condition A), and 190°C, 0.5% acid, 5 min (Condition B) with 6.91 and 4.15 g/kg respectively.  Those two conditions were selected for further studies involving the use of hydrolysate to simulate the seed train in a large scale operation.  Cultures grown using hydrolysate obtained from Condition A did not perform as well as those grown with hydrolysate obtained from Condition B after 24 h.  These results will be used for the seed train development at the University of Florida Stan Mayfield Biorefinery located in Perry, FL.