Monday, April 29, 2013
Exhibit Hall
Steam explosion pretreatment of Eucalyptus chips previously soaked in dilute phosphoric acid produced a slurry that was used for ethanol production. Following previous pretreatment results considering fermentable sugars and inhibitor generation, a Liquefaction plus Simultaneous Saccharification and co-Fermentation (L+SScF) was performed. The selected pretreated slurries were obtained using dilute phosphoric acid with the following conditions: 200 °C, 10 min retention time, and 0.5% acid soak (Condition A); and 200 ºC, 5 min retention time, 0.8% acid soak (Condition B). The slurries were then diluted to obtain a 10% solids loading and submitted to a 6 h liquefaction step (50 °C, pH 5.0) using the commercial enzyme Cellic CTec2 from Novozyme (10% v/w of dry weight of biomass), followed by a simultaneous saccharification and co-fermentation. After the liquefaction step, the total sugar concentration in the slurry was for 47 g/L Condition A and 51 g/L for Condition B. The fermentation was performed by an ethanologenic Escherichia coli strain derived from the KO11 strain. The sugars were completely consumed in 96 h with an ethanol yield as high as 0.217 and 0.243 g of ethanol per g DW of biomass for Condition A and Condition B respectively. These results confirm the effectiveness of using phosphoric-acid-pretreated Eucalyptus for the production of ethanol via the L+SScF process.