Show and explain the processing method of producing bio-ethanol from rice.
Rice straw consists of three main components, cellulose, hemicellulose
and lignin. Technologies for conversion of this feedstock
to ethanol have been developed on two platforms, which can be referred
to as the sugar platform and the synthesis gas (or syngas)
platform. The basic steps of these platforms are shown in Fig. 1.
In sugar platform, cellulose and hemicellulose are first converted
to fermentable sugars, which then are fermented to produce ethanol.
The fermentable sugars include glucose, xylose, arabinose, galactose,
and mannose. Hydrolysis of cellulose and hemicellulose to
generate these sugars can be carried out by using either acids or
enzymes (Drapcho et al., 2008).
In the syngas platform, the biomass is subjected through a process
called gasification. In this process, the biomass is heated with
no oxygen or only about one-third the oxygen normally required
for complete combustion. It subsequently converts to a gaseous
product, which contains mostly carbon monoxide and hydrogen.
The gas, which is called synthesis gas or syngas, can be fermented
by specific microorganisms or converted catalytically to ethanol. In
the sugar platform, only the carbohydrate fractions are utilized for
ethanol production, whereas in the syngas platform, all three components
of the biomass are converted to ethanol