Ingenieur Vol. 75 ingenieur July 2018-FA | Page 60

INGENIEUR
Figure 1: Scheme of SSF where saccharification and fermentation occurs in the same tank.
juice, respectively. Since Malaysia has the same
geographic latitude and seasonal conditions as
Brazil, we could follow the same strategies in
utilising agricultural waste as a biofuel. However,
there are continuous debates about first
generation biofuel, which utilises food sources
as a fuel. The possible connection between
ethanol production and food price inflation
can occur in two ways, either by reallocating
produced food crops to fuel production (e.g.
sugarcane being allocated to ethanol rather
than to sugar), or by diverting agricultural land
from food crops to energy crops (e.g. rice crops
being substituted by corn or sugarcane). But if
the biofuel crops are cultivated only on unused
or marginal land, the impact on food prices
would be minimal. In Malaysia, the projected
biomass waste from palm oil plantations alone
is 100 million tonnes/year by 2020 (Malek et al.,
2017), while the production of rice husk is 0.44
million tonnes/year. Bioethanol production via a
second generation biofuel is also expected to be
economically preferable in the future due to low
feedstock cost. Lignocelluloses from agricultural,
industrial and forest residuals consist of lignin,
cellulose, hemicelluloses, and various other
extractives. It contains both cellulose and
hemicellulose that can be converted to ethanol
by hydrolysis and fermentation. Glucose
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(hexose sugar) and xylose (pentose sugar) are
hydrolysed from cellulose and hemicellulose,
respectively. The fermentation process would
only be economically viable if both hexose and
pentose sugars present in the lignocellulosic
hydrolysates are converted to ethanol. The
conventional Baker’s yeast, Saccharomyces
cerevisiae can only uptake glucose and ferment
it to ethanol, leaving behind the precious xylose.
To achieve this, a micro-organism capable of
utilising both glucose and xylose is very much
anticipated. To add to the cost of operation, the
addition of enzymes is needed to hydrolyse the
lignocellulose into sugars during pre-treatment.
This is where powerful genetic engineering tools
may be applied to produce a super microbe,
functioning as a factory that can cater to the
full range of hydrolysis including broad range
sugar consumption, ethanol production and, in
addition, has the ability to handle fermentation
stresses.
Consolidated Bioethanol Processing
Approach
Conventional ethanol production involves
separate hydrolysis and saccharification.
Simultaneous saccharification and fermentation