Previous studies have shown high ethanol yields for SSF run at 5% WIS (water insoluble solids). It is however important to run SSF at higher dry matter contents in order to achieve higher ethanol concentrations to lower the energy demand in the distillation needed in the post treatment and to reduce the production cost.  Previous studies of SSF with higher dry matter contents have however shown a decrease in ethanol yield due to poorer mass transfer and increased inhibition by toxic compounds present in the pretreated material.

SSF at high dry matter content was studied in batch and fed-batch mode. In particular, different feeding strategies for the enzymes used in the process were investigated. Furthermore, since the dry matter contents studied so far (i.e. about 10% WIS) reach a practical limit of stirring capacity in the fermentors used, a new kind of reactor more suited for high viscosity materials was used to further increase the dry matter content. The results from this study will be presented at the conference.