Optimal particle size for fermentable sugar production from Miscanthus sacchariflorus var. No. 1 (Goedae-Uksae 1) considering energy consumption for comminution

Abstract

In this study, energy consumption for two stages of comminution of M. sacchariflorus and fermentable sugar production by hydrothermal pretreatment and enzymatic hydrolysis are investigated. Biomass comminution is carried out in two stages, which are chopping (18, 40, 80, and 160 mm length) and grinding using three screen sizes (3, 5, and 7 mm). In the chopping process, the highest total specific net energy efficiency is 17.35 kJ/kg when the biomass is chopped to 18 mm length. In the grinding process with chopped biomass, the total specific net energy efficiency ranges from 18.49 to 38.38 kJ/kg. In summary, the highest total specific net energy efficiency during the two stages of comminution is 44.58 kJ/kg when the biomass is chopped to 80 mm length and is sequentially ground to pass a screen size of 3 mm. The total fermentable sugar production ranges from 64.76 to 76.27 g/L, which is obtained from hydrolysate and enzymatic hydrolysis, depending on the biomass particle size. The highest fermentable sugar production is 76.27 g/L when hydrothermal pretreatment and enzymatic hydrolysis is performed with the ground biomass (chopping to 18 mm and sequentially ground to pass 3 mm screen). Considering the total fermentable sugar production and the total specific net energy efficiency, 18 mm length and less than 7-mm screen size is considered suitable for the chopping and the grinding, respectively, for the comminution of M. sacchariflorus.