What is Fermentation? What are the Key factors relating to improve the economic efficiency of Fermentation process?
The third situation is when the substrate is available in solid form, such as is the case with many organic residues, and it is economically advantageous to use it in this form rather than processing it for use in SLF. There are three main considerations here. First, additional costs are usually incurred in preprocessing the solid material into a form that is suitable for use in a liquid medium. Preprocessing for an SSF process is simpler, as it typically requires only a simple grinding to produce particles of an appropriate size. Second, the capital investment required for SLF bioreactors is higher than that required for SSF bioreactors. Third, large amounts of water need to be added in order to prepare a medium for a traditional SLF process. After the fermentation, the product is recovered from the fermentation broth and the spent broth then needs to be treated before disposal or recycling. Water additions are minimized in SSF and downstream processing is less costly. The ideal situation is when the fermented solid material can be used directly in the application for which it is intended, without the need for prior extraction of the product. One example of this is the production of fermented solids that contain enzymes. After a simple air drying to facilitate storage, these fermented solids can be added directly to an aqueous or organic reaction medium, to catalyze hydrolysis or synthesis reactions, respectively. In fact, SSF is a highly promising technology for application in biorefineries for processing plant biomass; in these biorefineries, many inputs and intermediates are in solid form and can be processed into value-added products using SSF.