Monday, May 4, 2009
9-11
Application of Ceramic Membranes to Recover of High Value Hemicellulose from Alkaline Peroxide Pretreated Wheat Straw
Hong Lin1, Richard Gustafson2, Renata Bura2, and Shannon Ewanick1. (1) College of Forest Resources, University of Washington, Bloedel Hall 364, Seattle, WA 98195, (2) School of Forest Resources, University of Washington, Bloedel Hall 364, Seattle, WA 98195
The production of high value co-products will enhance the economic viability of any biorefinery process. Recovery of hemicellulose from biorefinery process streams enables the potential to produce high value chemicals such as water soluble polymers and neutraceuticals like xylitol and arabitol. Alkaline peroxide pretreatment of wheat straw results in a liquid phase comprised of dissolved lignin and hemicellulose polymers as well as a defiberized solid phase. The solid phase can be enzymatically broken down to yield fermentable sugars or is suitable for use in papermaking. The hemicellulose in the liquid phase is still in polymeric form because the mild conditions do not result in further degradation of these polymers to sugars or sugar acids. This stream is an ideal candidate feed stream to produce high value co-products provided the hemicellulose can be recovered in a cost effective fashion. In this project, the potential for use of ceramic membranes to recover the high value hemicelluloses is presented. It is found that good recovery, approximately 85%, of the hemicelluloses polymers can be achieved with 5,000 and 10,000 molecular weight cut-off ceramic membranes. The permeate flux of these membranes is thoroughly assessed as a function of temperature and pressure. The application of membrane back-flushing to enhance the permeate flux is also investigated. In addition, the efficacy of the membranes to remove potential fermentation inhibitors is presented. Finally, results of this study provide data for a techno/economic analysis of the potential for using these membranes in a commercial scale biorefinery.