Bioenergy Science and Technology

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    EVALUATION OF SEDGE GRASS (S. tabernaemotani) FOR BIOETHANOL PRODUCTION
    (Hawassa University College of Agriculture, 2021) FREWEYNI HAILU
    Biofuel production from first generation biomasses, basically human food, might lead to problem of food crisis. Non-edible lignocellulosic biomass which is abundant with low production cost would be considered as an appropriate feedstock for ethanol production. Sedge grass (Schoenoplectus tabernaemontani) is one of environmental friendly non-edible lignocellulosic grasses.However; there are no reports on the use of sedge grass for bioethanol production. Therefore, this study was conducted to investigate the yield of total reducing sugar from sedge grass for ethanol production, with three levels of hydrolysis time (40, 60 and 80 min), three levels of H2SO4 concentration (1.5, 2.5 and 3.5%) and three levels of temperature (115, 125 and 135oC) designed in Complete Randomized Design (CRD) with three replications. The chemical compositions (extractives, cellulose, hemicellulose and lignin) of the plant were also determined by using National Renewable Energy Laboratory (NREL) protocol. The reducing sugar yield was determined by Benedict’s solution using spectrophotometer. Simple distillation was carried out to separate ethanol from water and the functional group of the produced ethanol was analyzed using Fourier Transform Infrared (FTIR).To estimate the ethanol yield, potassium dichromate method was used. As the result indicated, the content of hemicellulose, cellulose, lignin and extractives were 42%, 39.87%, 13.07% and 5.06%, respectively. The two-way interaction of treatments exhibited significant differences on total reducing sugar yield. Concerning the three-way interaction, highest total reducing sugar was produced when the feedstock was hydrolyzed at a temperature of 1250C for 60 min by 2.5% dilute H2SO4 solution. However, the lower percent of total reducing sugar yield (38.29%) was recorded from hydrolyzed sample at a temperature of 1350c for 80min using 3.5% dilute H2SO4 solution. Eventually, the highest ethanol yield (51.02%) was recorded from 49.83% of hydrolyzed sample reducing sugar fermented by F. oxysporum for 7 days fermentation. Therefore, sedge grass biomass is recommended as raw materials for bioethanol production, which is a promising alternative energy source against the depleting petroleum.