Bioconversion of Glycerol from Biodiesel Production to Ethanol by Enterobacter aerogenes TISTR 1468

Abstract

The objective of this study is to examine the potential applications of glycerol, a by-product derived from jatropha biodiesel production, via bioconversion into ethanol by Enterobacter aerogenes TISTR 1468. The purity of crude glycerol sample can be enhanced using sulfuric acid in varying concentrations. It was found that the addition by weight of 5% sulfuric acid could increase the glycerol purity from 27.68% to 94.43% with 65.42% of glycerol yield. Once purified, the glycerol sample was applied at 30 g/L to form the carbon substrate required in the anaerobic fermentation process by which ethanol can be obtained through the use of E. aerogenes for 120 hours at a constant 37°C. Under these conditions, purified glycerol yielded 8.39 g/L ethanol while crude glycerol yielded 6.54 g/L ethanol. The ethanol produced via this approach was shown to be highly efficient in comparison with commercial glycerol with purity at 99.5%, which produced 7.46 g/L ethanol under the same condition.