Rapeseed is an important source of oil for biodiesel production. Nevertheless, the residues of the cultivation
are lacking of practical applications. As a lignocellulosic material, their conversion into ethanol can
be of interest. In this work, different process configurations, separate hydrolysis and fermentation (SHF),
simultaneous saccharification and fermentation (SSF), and prehydrolysis and simultaneous saccharification
and fermentation (PSSF), were compared at high solids loading (7.5%, 15% and 20% w/v) to produce
ethanol from rapeseed straw pretreated by sulfuric acid.
Results show that the highest ethanol concentration (39.9 g/L) was obtained from SHF configuration at
the highest substrate loading (20% w/v). This product concentration is high enough for distillation purposes
from an economic point of view. The final ethanol concentrations and yields did not differ significantly
between SSF and PSSF regardless of the solids loading and, for 7.5% and 15% (w/v) solids loading
were slightly higher than those attained in the SHF. However, at the highest solids loading the separate
process appears to be more favorable.