Arosha Loku Umagiliyage

Optimization of Lime Pretreatment of Sweet Sorghum Bagasse for Enzymatic Saccharification

With recent emphasis on development of alternatives to fossil fuels, sincere attempts are being made on finding suitable lignocellulosic feedstocks for biological conversion to fuels and chemicals. Sweet Sorghum is among the most widely adaptable cereal grasses, with high drought resistance, and ability to grow on low quality soils with low inputs. It is a C4 crop with high photosynthetic efficiency and biomass yield. Our research objective is to optimize lime pretreatment of sweet sorghum bagasse for its enzymatic conversion into fermentable sugars for biofuels. Sweet sorghum biomass was ground and passed through a 35 mesh screen. Moisture content of the biomass was approximately 12%. It had 32.3% cellulose, 21.2% hemicelluloses, and 8.3% acid detergent lignin on dry matter basis. Lime pretreatment was provided in atmospheric pressure at 100oC. The lime concentration was varied from 0.05 g/g biomass to 0.2 g/g biomass; reaction time was 1 hour to 3 hours, and liquid loading was varied from 7 to 20 ml lime solution /g biomass sample. Pretreated biomass was hydrolyzed with mixture of two enzymes, Accellerase® 1500 (Cellulase) at 0.24 mL/g of SSB and Accellerase® XC (xylanase) at 0.25 ml/g of SSB, and measured for total reducing sugars by DNS (1,3-dinitrosalicylic acid) reagent.