Optimization of Molasses Fermentation to Ethanol to Reduce Effluent Generation: The Case of Metahara Sugar Factory
No Thumbnail Available
Date
2014-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Distilleries are one of Agro based industries which produces several types of liquors to serve
communities as a drink, feedstock for other industries and power alcohol. While producing these
valuable products for consumption more than 6 times effluents with high COD and BOD values has
been produced. This effluent will cause huge disaster on environment if it is discharged without
treatment. On the other hand treating such huge quantity of effluent will incur additional cost to the
production processes of the distilleries. Therefore, this study is conducted with the view of reducing
the volume of effluent generated through proper nutrient application and optimum recirculation of
effluent to fermenters.
This study was conducted first by making an optimization of macronutrients for the existing
fermented wash sugar concentration of 15 brix and application of 62.51 and 14.51 mg/L of wash
for Urea and DAP respectively has been found an optimum. Using this optimum nutrient dosage test
for effluent recirculation were conducted for the existing fermentable sugar concentration of 8.67%
(15 brix). Data of alcohol% fermented wash, yeast cell mass count and residual sugar were generated
and analyzed using response surface methodology and application of 1% spent wash, 92% spent
lees and 99% of the generated effluents were found to be safely re-circulated to fermenters.
Anticipating future change in operating conditions of fermentation process the study has been
conducted at different fermentable sugar concentration of 8.67%(15 brix), 11.5%(20 brix) and 14.3%
(25 brix). Data are generated and analyzed using response surface methodology and it was found
that fermentable sugar concentration of 14.3%(25-brix), macro nutrients of 62.51mg/L Urea and
31.26 mg/L DAP, recirculation of the generated 50% of spent wash, 68.5% of spent lees and 85.83%
of process condensate taken as an optimum input and alcohol % fermented wash of 7.43, yeast cell
mass of 2.40674E+008 and residual sugar concentration of 0.417% are found as a response variable.
Determination of different attribute of rectified sprit produced by using an optimum recirculation
rate of effluent to fermenters and it is found in safe range from food safety and quality points of
view. Besides, sizing of equipments such as cooler, pump and piping required to handling effluent
recirculation were done. Moreover, financial analysis was carried out and it was found viable. The
study shows that the initial investment will be fully returned within eleven months.
Description
Keywords
Metahara Sugar Factory