초록
<P><B>Abstract</B></P> <P>This work describes improvements in the enzymatic hydrolysis of hydrothermally pretreated sugarcane straw. The experiments were performed in batch and fed-batch operation modes (50 mL and 3 L working volumes) with final solid loadings of 10, 20, and 30% (w/v) and enzyme dosage of 10 FPU/g<SUB>substrate</SUB>. The fed-batch assays showed the most promising results in terms of glucose production and cellulose-to-glucose conversion. In the experiments using a 3 L working volume, analysis of cellulose-to-glucose conversion, power consumption, and apparent viscosity showed that the best assays were those with smoother feed delivery (substrate plus enzyme) throughout the enzymatic hydrolysis. This strategy resulted in 108.8 g/L of glucose and cellulose-to-glucose conversion of 59.7%, corresponding to a final theoretical ethanol content of 55.6 g/L. The power consumption per unit volume and the apparent viscosity were less than 5 kW/m<SUP>3</SUP> and 35 mPa s, respectively, throughout the hydrolysis. Thus, a more concentrated liquor and a less powerful motor to deliver power during the hydrolysis process were obtained in fed-batch strategy reducing the process energy costs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fed-batch strategy allowed to increase solid loadings up to 30% (w/v) in enzymatic hydrolysis. </LI> <LI> Higher glucose concentrations were reached in fed-batch enzymatic hydrolysis operation. </LI> <LI> Less powerful motor is required in fed-batch enzymatic hydrolysis. </LI> <LI> Fed-batch operational mode presented better performance in cellulose hydrolysis. </LI> <LI> Rheological behavior and power consumption were optimized at 30% (w/v) of solid loadings. </LI> </UL> </P>