Production of Acetic Acid by Repeated Batch Fermentation

Author : Macha, Bienvenido Alvarez
Major Adviser : Pham, Chay Binh
Committee Members : Acda, Reynaldo I.; Movillon, Jovita A. 
Year : 1993
Month : May
Type : Thesis
Degree: BS
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Acetic acid was produces in a stirred tank bioreactor using the repeated batch operation. The effects of ethanol concentration, agitation and yeast extract concentration on acetic acid production was investigated using repeated batch process.

Highest acetic acid concentration (63.396 g/l) was obtained at 20 g/l yeast extract,60 g/l ethanol concentration and 1000 rpm agitation. Maximum yield (1.18) and fermentation efficiency (90.19 %) were obtained at an ethanol concentration of 60 g/l, 20 g/l yeast extract and 800 rpm agitation. Average yield and fermentation efficiency were 1.032 and 79.67 % respectively.

An equation predicting the acetic acid concentration achievable as a function of ethanol concentration, yeast extract concentration and agitation was developed by regression and correlation analysis. This equation was used to determine the individual and interactive effects of ethanol, yeast extract, and agitation. It was found out that increasing the yeast extract concentration enhances maximum acetic acid production. Maximum acetic acid concentration of 55 g/l,15 g/l yeast extract at 800 rpm. Increase in agitation at constant ethanol concentration and yeast extract concentration caused n increase in acid production. At constant agitation increasing yeast extract and ethanol concentration resulted to an increase in acetic acid.

The regression equation has several critical points but none of them is an optimum. A wider range of ethanol concentration, yeast extract, and agitation were necessary to predict the optimum conditions for acetic acid production.

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