Lime Pretreatment of Coastal Bermudagrass for Bioethanol Production

Coastal bermudagrass (CBG) is regarded as a potential lignocellulosic feedstock for bioethanol production in the southeast United States. Lime pretreatment of CBG for enhanced reducing sugar recovery was investigated in this study, which examined a variety of temperatures (21-121 degrees C) at a range of residence times with different lime loadings (0.02-0.20 g/g of dry biomass,). During pretreatment, 10-20% lignin was removed. After enzymatic :hydrolysis with excessive celluloses and cellobiase, the blest total reducing sugar yield for the lime-pretreated CBG was 78% of the theoretical maximum, which is over 2 times more than that front the untreated CBG. The recommended condition is 100 degrees C for 15 min with a lime loading of 0.1 g/g of dry biomass, under which 87% glucan and 68% xylan were converted to glucose and xylose, respectively. Fermentation tests of the hydrolyzates indicated that more than 99% glucose in the hydrolyzate was used by the yeast during the fermentation, with ethanol yields of 95% of the theoretical maximum for the hydrolyzate and 83% of the theoretical maximum for the raw biomass.