Review paper Integration of Biodiesel and bioethanol processes: Convertion of low cost waste glycerol to bioethanol

• Main Authors: Nomanbhay, S., Hussain, R., Rahman, M.M., Palanisamy, K.
• Format: Article
• Language: en_US
• Published: 2017
• Institution: Universiti Tenaga Nasional

The once abundant petroleum reserves now dwindling and oil prices continue to rise; the search for alternative fuels becomes more vigorous. The paper reviews current growing attention focusing on ethanol as a renewable fuel to substitute and/or complement gasoline fuel. This trend is due to, among other aspects, the growth of oil prices in the international market, and the pressure to reduce atmospheric emissions of CO2 to mitigate the problem of global climate changes. Glycerol-rich streams generated in large amounts by during the production of biodiesel, present an excellent opportunity to establish biorefineries. This review covers the anaerobic fermentation of glycerol in microbes and the harnessing of this metabolic process to convert abundant and low-priced glycerol streams into higher value products, thus creating a path to viability for the biofuels industry. However, glycerol is rarely used as a carbon source in Escherichia coli fermentation because of its low yield of products. A native, nonpathogenic strain of E. coli, able to ferment glycerol to useful products under anaerobic condition is currently used by many researches. The key factor is not the type of strain, but rather on the appropriate environment including an acidic pH, avoiding accumulation of fermentation gas hydrogen and appropriate medium composition to achieve high yeilds. The process becomes increasingly attractive, using biocatalyst like (Alcohol Dehydrogenase) to metabolize these chemicals anaerobically to produce ethanol.