(803d) Comparison of Different Process Configurations Using SSF At High Solid Loadings of Steam-Pretreated Corn Stover

Bondesson, P. M., Lund University
Zacchi, G., Lund University
Galbe, M., Lund University

The use of lignocellulosic biomass for ethanol reduces the dependency of fossil fuel and lowers the greenhouse gas emissions. A high ethanol concentration in the broth improves the economics of the ethanol production process. However, when working with high solid loadings, the ethanol yield may decrease due to difficulties to mix, which causes mass transfer limitations. Also, the effect of higher inhibitor concentrations becomes more pronounced. Some of the problems can be overcome by selecting proper configurations for enzymatic hydrolysis and the fermentation process.

In this work washed steam-pretreated fibres from corn stover was used to study the impact of a high solids loading using different process configurations with negligible amounts of inhibiting compounds. A prehydrolysis step prior to SSF or fed-batch SSF was investigated and compared with ordinary SSF using a water-insoluble solids (WIS) loading of 20%. Different variables, such as prehydrolysis time, temperature, feeding time and feeding interval as well as enzyme loading were investigated. The results showed that the inclusion of a prehydrolysis step did not increase the ethanol yield (70-75%) compared with SSF performed batchwise (75%). On the other hand, an improvement was found utilizing fed-batch, which increased the yield (79-82%). Results from this study will be presented.