2.3. Simultaneous saccharification filtration and fermentation (SSFF)
In SSFF, fermentation broth is circulated between the hydrolysis
and fermentation vessels. Pretreated slurry is mixed with enzymes
and pumped through a cross-flow membrane, so that a clear sugarrich
filtrate reaches the fermentation vessel. Simultaneously, the volumes are kept in balance by pumping fermented liquid back to
the hydrolysis vessel (Fig. 1). Retention of the fermenting culture is
necessary and is facilitated by the use of a flocculating yeast strain.
Through an internal settler (10 mL syringe of 1.5 cm internal diameter)
in the fermentation reactor for sedimenting the culture
(Fig. 1), the fermented liquid is pumped back to the hydrolysis
reactor. The SSFF is composed of three parts of hydrolysis, filtration
and fermentation (Fig. 1).