(245f) Anaerobic Fermentation of Hemicellulose Present in Pre-Pulping Extracts of Northern Hardwoods to Carboxylic Acids

Wood is composed primarily of cellulose, hemicellulose and lignin. In the paper industry the cellulose fraction is important as the major resource in paper production, whereas the hemi- cellulose and the lignin are usually burned for heat recovery. Recently the hemicellulose has received much attention for the production of different bioproducts. Varying amounts of hemicellulose and associated organic acids can be extracted from wood chips when they are subjected to pre-pulping extraction under different conditions of chemical loading and extraction severity. A major interest for use of the extract this is to convert the hemicellulose into valuable chemicals via fermentation.

Mixed-culture microbial ecosystems operated in acidogenic mode are capable degrading all sorts of biomass into mixtures of carboxylic acids. Such cultures were applied to the conversion of pre-pulping extracts, from the paper mill (green liquor extracts) and the panel board making industries (hot water extracts), especially derived from northern hardwoods. In this study, we determined the production levels of carboxylic acids using mesophilic and thermophilic cultures with green liquor salts and calcium carbonate as the buffering agents. Use of certain methane inhibiting chemicals might be helpful during the process, improving the product concentrations. Conditions of combined extraction and fermentations were assessed to determine the optimal yields of carboxylic acids for use as platform chemicals for further upgrading.