Monday, May 4, 2009
5-93
Monitoring the rheological properties of pretreated biomass in high-consistency enzymatic liquefaction
Nóra Szijártó1, Matti Siika-aho2, and Liisa Viikari1. (1) Department of Applied Chemistry and Microbiology, University of Helsinki, P.O.Box 27, Helsinki, FIN-00014, Finland, (2) VTT Biotechnology, Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Espoo, Finland
Process to produce fuel ethanol from lignocellulosic biomass needs still to be improved to become economically viable. One of the single most important process parameters with regard to process efficiency is the overall substrate consistency; low carbohydrate levels not only increase the capital cost due to equipment size but they also result in excessive energy requirement of heating, cooling and distillation. Until recently, solid loadings of 10% or less were the standard applied. When aiming at e.g. 5% final ethanol concentration in the fermentation broth (considered as a prerequisite for a feasible large-scale distillation technology) the dry matter loading has to be over 20%. High-solid slurries, on the other hand, are difficult to handle because of the insufficient mass transfer conditions caused by the strong, if not complete, adsorption of process water by the pretreated material. One possibility to overcome this problem might be to include a pre-hydrolysis step in the process sequence aimed at the rapid liquefaction of the high-consistency slurry. Because of the more favorable rheological properties at higher temperatures, the use of thermostable enzymes may be of special importance in such technologies.
The goal of the present study was to evaluate the applicability of a short-time liquefaction using various enzyme preparations and purified enzyme components to increase the flowability of slurries at high solid loadings (up to 20% on dry basis). Liquefaction of pretreated spruce, corn stover and wheat straw substrates was followed via measuring the mechanical properties of slurries using a texture analyzer and a viscosimeter.
The goal of the present study was to evaluate the applicability of a short-time liquefaction using various enzyme preparations and purified enzyme components to increase the flowability of slurries at high solid loadings (up to 20% on dry basis). Liquefaction of pretreated spruce, corn stover and wheat straw substrates was followed via measuring the mechanical properties of slurries using a texture analyzer and a viscosimeter.