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Poster Presentation 3-30
Progress in Softwood to Ethanol Process Design and Optimization
Olga Mirochnik, Eva Attenius, Bin Yang, David Gregg, Sheldon Duff and John N. Saddler
Forest Products Biotechnology, Department of Wood Science, University of British Columbia, 4041 - 2424 Main Mall, Vancouver, British Columbia V6T 1Z4 Canada
Telephone: (604) 822-2467; Fax: (604) 822-9104; Email: saddler@interchange.ubc.ca
Our research over the last 5 years has focused on process optimization for overall recovery of all three main feedstock components (cellulose, hemicellulose and lignin) from steam-exploded softwood, primarily Douglas fir. The optimization has included both manipulation of the various subprocess parameters as well as the addition or deletion of subprocess steps. Recovery of the feedstock components has been enhanced substantially (+90% for cellulose & lignin +80% for hemicellulose).
The robustness of the process, to handle various individual and mixed softwood feedstocks, was found to be good. These softwood recoveries also compare favorably to those previously reported for a hardwood (aspen), thus revealing the opportunity for a flexible and robust single process design for both hardwoods and softwoods.
Process optimization based on component recovery has come at an economic cost. For example, the lignin produced using the optimized SO2-catalyzed steam pretreatment conditions, due to condensation reactions, is likely only suitable for low-value uses such as burning for process heat and power. Furthermore, full fractionation of the components or maximum recovery is only attained through a substantial capital and operating cost. As a consequence of these economic issues we are now directing our attention to process design and optimization based on recovery of usable higher-value products. Current options and direction will be presented.
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