Effect of Extruder Compression Ratio on the Biomass Pretreatment

Abstract

Abstract: Although biomass pretreatment research is being done for more than two decades to enhance the enzymatic digestibility, still there is a need to develop a viable pretreatment method. Extrusion could be a viable continuous pretreatment method to be explored. This study was planned to investigate the effect of compression ratio (2:1 and 3:1), screw speed (50, 100 and 150 rpm), and barrel temperature (50, 100 and 150C) on the sugar recovery from switchgrass (SG) and prairie cord grass (PCG) over a range of moisture content (15, 25, 35, and 45% wb).The pretreated samples were subjected to enzymatic hydrolysis for sugar recovery measurement. From the statistical analysis, it was found that 3:1 screw compression ratio (compared to 2:1) increased glucose and combined sugar recovery by 12 and 8, 37 and 40% for SG and PCG, respectively. For SG, the highest sugar recovery (45.2%) was obtained at the lowest screw speed (50 rpm) and highest temperature (150C) with 15% moisture content of biomass. The highest glucose, xylose and combined recovery of 61.4, 84.3 and 65.8% were recorded for PCG extruded at a screw speed of 50 rpm and temperature of 50C with 25% moisture content. Glycerol and acetic acid were the byproducts found in low concentration (0.02- 0.18 g/l) for both biomasses.