was shorter and the bioethanol productivity was also higher than
that reported previously.
The high ethanol concentration and ethanol yield obtained here
in a short period from pretreated substrate can mainly be ascribed
to two factors. First, CHEMET pretreatment increased the biomass
surface by applying a high shearing force and results in increased
enzymatic digestibility. Second, the prehydrolysis step allowed
sufficient time by means of the continuous feeding system. The
continuous feeding system was connected to the bottom of the
bioreactor and could increase the biomass concentration from 0%
to a high concentration, allowing sufficient time for liquefaction
of the substrate by the enzyme. Furthermore, the angled-type of
impeller allowed more thorough mixing of the substrate with the
enzyme and the seed mash than could be achieved using the standard
type of impeller.