Sunday, April 29, 2007

Comparing the fermentability of corn stover hydrolysate from Ammonia Fiber Expansion and Dilute Acid Pretreatment

Ming W. Lau1, Venkatesh Balan2, and Bruce E. Dale1. (1) Chemical Engineering and Materials Science, Michigan State University, 3270, Engineering Building, East Lansing, MI 48824, (2) Department of Chemical Engineering and Material Science, Michigan State University, 2527 Engineering building, East Lansing, MI 48824

The choice of feedstock pretreatment method is of paramount importance as it affects the efficiency of subsequent unit operations, enzymatic hydrolysis and fermentation. The need for detoxification and nutrient supplementation also varies depending on the pretreatment used.  Dilute acid pretreatment and ammonia fiber expansion (AFEX) are two promising pretreatment technologies. However, side-by-side comparisons of these two pretreatments have not been performed. Hence, we compare these two pretreatments for corn stover in terms of (1) the efficiency of hydrolysis at high solids loading (20-30% w/w), (2) their fermentation performance under baseline conditions (unwashed, undetoxified, unsupplemented), (3) the necessary detoxification and nutrient supplementation required to achieve satisfactory fermentation performance. Along these lines, we report the efficacy of minimal media as a supplement to improve fermentation performance. The pretreatment comparison is conducted through Separate Hydrolysis and Fermentation (SHF) using the ethanologen Escherichia coli KO11.

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