Amrita et al (2011)[1] produced economically
feasible cellulosic ethanol. Ethanol yield and
enzyme efficiency has to be improved by
optimizing all unit processes (pretreatments,
saccharification and ethanol fermentation). Most
of the pretreatments focused on low temperature
pretreatment to avoid degradation of
hemicellulose and to improve the pentose yield.
Impregnation by various chemical reagents such as sulfuric acid and application of microwave have
been tried to lower pretreatment temperatures
while maintaining high enzymatic digestibility. For
saccharification, the accessible surface area and
enzyme, reuses were key parameters. With regard
to surface area, xylanases addition was effective.
To prevent deactivation of cellulase by binding to
non-productive sites, the addition of surfactants
was the efficient method. Among various reagents,
PEG 6000 exhibited best performance. Co-
fermentation of glucose and xylose was key factor
in improving ethanol yield. Fed-batch and co
immobilization have been found to be the ideal
option for co-fermentation steps.