Bioethanol After decomposition process, cassava porridge becomes

Bioethanol
based on (Lamy, 2004) is ethanol which is the main ingredient using plants and
fermentation  process. Ethanol or ethyl
alcohol (C2H5OH) is biodegradable, low toxicity, colorless,
and non-polluted fluid when leaking. Ethanol is a high-octane fuel and can
replaced Pb (Lead), by mixing ethanol with gasoline it will oxygenate the fuel
mixture so that it can perfectly burn and reduce exhaust gas emissions such as
carbon monoxide (CO). based on (Wiratmaja,2011) the plant for making bioethanol
should have a high content of starch. In Indonesia, is many cassava skin waste from
household or industry, while cassava skin has a high content of about 25-30% of
starch, this is very suitable as an alternative energy material.  

            The steps for making bioethanol from
cassava skin is, first peeled the cassava skin and cut them into small pieces. Before
cassava skin is cut, clean the cassava skin using fresh water. After that, dried
the cassava skin that has been chopped to a maximum water content 16%. The purpose
of this step is to more durable so the bioethanol maker can save as raw
material reserves. Then, put 25kg of dried cassava skin to stainless steel tank
with capacity up to 120 liters, add 100 liters of water and heated it on 100oC
for 30 minutes. This step is for make cassava skin becomes porridge and
thickens the porridge.

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            After that, cooling the cassava
thick porridge and put that into the sacchafrification tank. Saccharification is
the process of decomposing starch into glucose. Once cool, add fungus (Aspergillus sp.). Aspergillus sp. will
break down starch into glucose. To decompose 100 liters of cassava starch
porridge need 10 liters of aspergillus sp. After decomposition process, cassava
porridge becomes two layers, water and sugar. Then, stir back the sugar starch,
then place it in

 

the
fermentation tank. Fermentation process is using saccharomyces sp. Seal tightly fermentation tank to prevent
contamination and saccharomyces work
optimally. Fermentation process is does not require oxygen (anaerobic). For
optimal fermentation, keep the temperature at 28-32oC and with pH
4,5-5,5.

            After 2-3 days, the starch solution
turns into 3 layers. The lower layer is a protein precipitate, middle layer is
ethanol, and top layer is water. The result of the fermentation is called beer
(contains 6-12% ethanol). Then, suck an ethanol layer with a plastic hose
through a one micron filter paper to filter out the protein precipitate. Although
it has been filtered, ethanol is still mixed with water. To separate it, we
need distillation process. The way to distillation is heat a mixture of water
and ethanol at a temperature 78oC or equivalent boiling point of
ethanol. The ethanol gas is flowed through a submerged tube so it becomes
condensed and returns into liquid ethanol.