Monday, April 30, 2007

Succinic acid production as an integrated component of a forest products biorefinery

David B. Hodge1, Christian Andersson2, Ulrika Rova2, and Kris A. Berglund2. (1) Chem. Eng. & Mat. Sci.; Biosys. & Ag. Eng., Michigan State University, 2527 Engineering Building, East Lansing, MI 48824, (2) Luleň University of Technology, Luleň, Sweden

Hemicellulose from the forest products industry represents a large reservoir of sugars with the potential to be converted to higher value products. E. coli strain AFP184 is capable of producing succinic acid, a potentially important platform molecule in the synthesis of a number of commodity and specialty chemicals, simultaneously from glucose and xylose in a dual phase, aerobic/anaerobic fermentation. Our work will investigate the feasibility of integrating a birch hemicellulose sugar extraction step into an alkaline pulping process and the fermentation of these sugars to succinic acid.  Pulp strength is an important property for many paper applications, and acid hydrolysis can result in excessive cellulose depolymerization.  For this reason, both alkaline and acid hydrolysis will be implemented and compared.  Two-stage acid hydrolysis is performed with auto-hydrolysis (low severity factor) to solubilize oligomeric xylan followed by dilute sulfuric acid pretreatment to yield a relatively pure xylose stream.  Alkaline conditions use low-alkali or chip impregnation black liquors and hemicellulose is precipitated by ethanol and hydrolyzed with dilute sulfuric acid.   The fermentability and detoxification requirements of these resulting sugar streams will be investigated.