Biomedical Engineering Reference
In-Depth Information
Fig. 8
Process engineering strategies for bioethanol production
reduce energy consumption for ethanol distillation as well as distillage treatment,
due to the significant reduction in the distillage discharged from the distillation
system. Such an idea was tested in the Iogen process, the first demonstration
plant established in the world for bioethanol production through the biochemical
conversion pathway [
51
].
However, the accumulation of glucose during the hydrolysis significantly
inhibits b-glucosidase, which sequentially results in the accumulation of cello-
biose that inhibits the activities of exo-b-glucanase or cellobiohydrolase (CBH)
and endo-b-glucanase (EG). Supplementation of b-glucosidase may be one of the
solutions to this problem if the cost of the enzyme is not too high--for example,
b-glucosidase from Aspergillus niger [
52
]. On the other hand, another concern
with the SHCF process is microbial contamination during the hydrolysis of
cellulose and the transport of the hydrolysate through pipelines, which can
deteriorate during ethanol fermentation and compromise ethanol yield, since
the bulk amount of medium for ethanol fermentation is never sterilized in the
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