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โครงการหนังสืออิเล็กทรอนิกส์ด้านการเกษตร เฉลิมพระเกียรติพระบาทสมเด็จพระเจ้าอยู่หัว

pollution. As cassava ethanol is mainly produced from fresh cassava root and also the dried chip
processing step does not require water; therefore, the process of converting fresh cassava to dried

chips form is not accounted for in the study.

8.2.3 Water requirements for bioethanol conversion

8.2.3.1 Molasses ethanol
Molasses ethanol production consists of yeast preparation, fermentation, distillation

and dehydration. The study refers production data of molasses ethanol conversion from literature

(Silalertruksa and Gheewala, 2009; KAPI, 2007). To produce a litre of molasses ethanol, around
4.6 kilogram of molasses is required or equivalent to around 61 L of molasses ethanol/ton of
sugarcane. The water used at the ethanol conversion stage is about 8.6 L/L of molasses ethanol. It

is classified as “blue water” and the two main water-intensive processes are the fermentation and

the supporting process as steam generation.

8.2.3.2 Sugarcane ethanol
To produce sugarcane ethanol, sugarcane juice which is extracted from sugarcane
crushing process will be directly used to produce ethanol without the production of sugar. Bagasse

is used to produce steam and electricity. Based on the surplus electricity about 126 kWh would be

obtained for the production of 1,000 litre sugarcane ethanol (Silalertruksa and Gheewala, 2011),
the allocation factor can be derived for sugarcane ethanol. The blue water required at this stage is
estimated to be about 14.3 L/L sugarcane ethanol Blue water required at this stage is about 14.3

L/L sugarcane ethanol and it is mainly for steam production. Spent wash is sent to aerobic ponds

with biogas recovery system. To produce a litre of sugarcane ethanol, around 11.6 kilogram of
sugarcane is required or equivalent to around 86 L of sugarcane ethanol/ton of sugarcane.

8.2.3.3 Cassava ethanol
The cassava ethanol plant consists of five main processes i.e. (1) cassava

preparation including cleaning and milling; (2) liquefaction, (3) fermentation, (4) distillation and (5)

molecular sieve dehydration. In this industrial stage, water is used for mixing and liquefaction and
for industrial boilers for steam production. Thus, the water used in this stage is mainly classified as
“blue water”. About 6.2 kilogram cassava root is required to produce a litre ethanol or equivalent to

around 161 L cassava ethanol/ton of cassava root. Blue water use for cassava ethanol production

is referred from the literature i.e. around 11.1 L/L cassava ethanol (Silalertruksa and Gheewala,
2009; KAPI, 2007)

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