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The environmental and economic strains associated with oil have created the need to explore alternate sources for fuel production and use. One such alternative is ethanol derived from cellulosic material. This report specifies the design of a process used for the conversion of pecan husks into fermentable sugars. The design consists of physical grinding of the raw material, acid pretreatment of the cellulosic powder resulting from grinding, and enzymatic hydrolysis of the remaining polymeric sugars. Enzymes were produced through the culturing of a fungus called T. reesei. Results of testing indicate that optimal conditions for fungus growth are a pH = 5.0, a temperature = 26°C, and a glucose concentration = 30g/L. The optimal conditions determined for acid pretreatment are 1% HCl [w/w], a temperature of 200°C, and a residence time of 5 minutes. For enzymatic hydrolysis, a temperature of 60°C, Enzyme/Pecan Ratio of 5 ml/g, and a pH of 6.0 were chosen as the optimal operating conditions. Finally, an economic analysis of the large-scale ethanol production process was conducted. This analysis was based on the performance of the final design, and results indicate that a plant producing ethanol derived from pecan husks could produce ethanol at a cost of $1.81 per gallon.


ENGR 4382

Dr. Collins, Advisor