Applied Energy, Vol.125, 76-83, 2014
Optimization of dilute-phosphoric-acid steam pretreatment of Eucalyptus benthamii for biofuel production
This work deals with the production of ethanol from phosphoric acid-impregnated, steam-exploded Eucalyptus benthamii. The whole conversion process, addressing pretreatment, enzymatic hydrolysis of the whole slurry, and fermentation of both C5 and C6-sugars including a presaccharification step, is covered in this study. Two separate models were developed to maximize sugar content and minimize inhibitor concentrations, resulting in xylose yields of 50% and 60% after pretreatment. In addition, a Liquefaction plus Simultaneous Saccharification and co-Fermentation (L+SScF) was performed to compare the fermentability of the resulting pretreated biomass. After the 6-h liquefaction step using the Celtic CTec2 enzyme from Novozyme and 10% DW pretreated biomass, the total sugar concentration in the slurry was 47 g/L and 51 g/L for the two conditions respectively. Enzymatic hydrolysis continued during fermentation using an ethanologenic derivative of Escherichia coli K011. The sugars were completely consumed in 96 h with product yields of 0.217 and 0.243 g ethanol/g DW biomass for each condition, respectively. These yields are equivalent to 275 and 304 L/tonne DW, confirming the effectiveness of the L+SScF process using phosphoric-acid-pretreated Eucalyptus. (C) 2014 Elsevier Ltd. All rights reserved.