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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/1617

Title: EVALUATION OF ETHANOL PRODUCTION FROM INTERMEDIATE CANE MOLASSES BY YEAST (SACCHAROMYCES CEREVISIAE )
Authors: Fekadu, Abebe
Advisors: Dr. Eng. Shimelis Admassu
Copyright: 2007
Date Added: 7-Nov-2008
Publisher: Addis Ababa University
Abstract: The present study analyzes the influence of modification of sugar crystallization from three to two stages and tried to optimize both sugar and ethanol production from sugar cane source. The efficiency of sugar crystallization process was determined by simulation at Wonji Shoa Sugar Factory (WSSF). Economical advantages in optimizing the sugar and ethanol productions were compared with the factory’s existing working norms. Batch fermentation of molasses samples using saccharomyces cerevisiae was carried out at fermentation temperature of 30 (+1) o C, pH of 5.5 (+ 0.1) and ammonia supplement of 2 g/L in Erlenmeyer flask of 250 mL. The parameters varied were total sugar as invert (TSAI) in the fermentation broth of prepared molasses from both two and three crystallization stages and the amount of dry yeast in the inoculums (1,3,5 g/L). The measured values were concentration of the produced alcohol and the residual sugar. From the obtained data of alcohol concentration and residual sugar; the ethanol yield was calculated. All results obtained were subjected to SPSS and significance was set at 5% level. Alcohol concentration was found to vary from highest of 83 g/L to lowest of 36 g /L for molasses B (mB) and from highest of 53 g/L to lowest of 30 g/L for molasses final (mF), while residual sugar concentration varied from lowest of 26 to highest of 73 g/L for mB and 34 to 78 for mF. The calculated ethanol yield varied from highest of 0.47 g/g to 0.19 g/g and from 0.31 g/g to 0.16 g/g for mB and mF respectively. The variation was statistically significant (p 0.05).unfermentable sugar (%w/w) of 4.64 and 5.55 was obtained fro mB and mF respectively. Microorganisms’ results as total viable count were found as 378 CFU per 10 g of sample for mB and 428 CFU per 10 g of sample for mF. The net sugar produced was 12.61 % and 11.76 % cane from three and two crystallization system, whereas final molasses of 3.73 % and 4.79 % cane in three and two stage respectively were obtained. In the modification (from three to two stages), about 6.7% decreases in sugar product, an increase in molasses production quantity by about 28.4% and an increase in molasses TSAI content by about 28.8% respectively were obtained . The overall economic return by modification of the crystallization system indicates that there was additional income of 19.83 Eth. birr per ton of cane through optimum production of sugar and ethanol. The obtained results reveal that the modification in sugar crystallization system can bring over all improvement in both sugar and distillery plants and found economically feasible in the studied cases. Besides the economic return, the modification system tends to reduce the high recirculation of material, the energy utilization and the crystallization area capacity than the existing three crystallization system, with out affecting the product quality.
Description: A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Food Engineering
URI: http://hdl.handle.net/123456789/1617
Appears in:Thesis - Food Engineering

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