Monday, May 4, 2009
9-13
Non-sterile fermentation of bioethanol
Jan Larsen and Laila Thirup. Inbicon, Klippehagevej 22, DK-7000 Fredericia, Denmark
Integrated Biomass Utilization System (IBUS) is a new process for converting lignocellulosic waste biomass to bioethanol. Inbicon has developed the IBUS process in a large-scale process development unit. This plant features new continuous and energy efficient technology developed for pretreatment, liquefaction and fermentation of lignocellulosic biomass. In the IBUS process biomass is converted using only steam and enzymes. The process is energy efficient due to very high dry matter content in all process steps. Cellulose is converted to bioethanol and lignin to a high-quality solid biofuel. Hemicellulose is used as feed molasses, but in the future it could also be used for additional ethanol production or other valuable products.
Another cost saving part of the IBUS process is a new discovered method by which long fermentations of up to 200 h can be conducted under non-sterile conditions without contamination of Lactobacillus. One problem typically encountered in second generation bioethanol fermentation is the presence of degradation products arising from pre-treatment of lignocellulosic feedstocks. These degradation products often act as fermentation inhibitors. A range of concentrations exists in which fermentation inhibitors derived from pre-treatments of lignocellulosic feed stocks will not affect fermentative yeast but will inhibit growth of lactic acid bacteria. By optimizing levels of fermentation inhibitors to fall within this range, yeast fermentations of lignocellulosic biomass can be conducted under non-sterile conditions with ethanol yields comparable to those achieved under sterile conditions. The concept has been proved for fermentations of pre-treated wheat straw, corn stover and bagasse.
Another cost saving part of the IBUS process is a new discovered method by which long fermentations of up to 200 h can be conducted under non-sterile conditions without contamination of Lactobacillus. One problem typically encountered in second generation bioethanol fermentation is the presence of degradation products arising from pre-treatment of lignocellulosic feedstocks. These degradation products often act as fermentation inhibitors. A range of concentrations exists in which fermentation inhibitors derived from pre-treatments of lignocellulosic feed stocks will not affect fermentative yeast but will inhibit growth of lactic acid bacteria. By optimizing levels of fermentation inhibitors to fall within this range, yeast fermentations of lignocellulosic biomass can be conducted under non-sterile conditions with ethanol yields comparable to those achieved under sterile conditions. The concept has been proved for fermentations of pre-treated wheat straw, corn stover and bagasse.
Web Page: www.inbicon.com