Author(s)

M. Ntoampe, T. Matambo, D. Glasser & D. Hildebrandt

Abstract

Bioconversion of renewable resources into useful chemicals and fuels is of great interest in scientific research. This is mainly because of the gradual depletion of fossil fuels and the increasing price of oil. The objective of this research is to produce biologically based chemicals and fuels from sweet potatoes. The sweet potato is a crop of choice because it has a high starch content and is rich in β-amylase, which converts long chained starch into readily used maltose units, making it a good energy and carbon source for bacteria. A Fluidized Bed Bio-Reactor (FBBR) was used as a fermentation tank, in which bacteria were metabolizing and converting sweet potatoes into end products, such as fuel ethanol and hydrogen gas. On the other hand, plate counts were used to estimate the number of viable cells in a reactor. Any increase in the number of cells would be an indication of increasing cell density, which would imply increased microbial activity and hence elevated gas and chemical production by the microbes used in the reactor. Gas Chromatography (GC) was used to analyze the end products, i.e. in separating components of the liquid mixture into pure components. This was the key to establishing which gases and liquids were produced during FBBR operation. GC analysis revealed that 5% ethanol, 2.5% acetic acid, 2% propionic acid and 3% butyric acid were produced. Hydrogen and methane were also produced in amounts that were not measured. Keywords: sweet potato, fermentation, fluidized bed bio-reactor, ethanol, acetic acid, propionic acid, butyric acid, methane, hydrogen.

Keywords

sweet potato, fermentation, fluidized bed bio-reactor, ethanol, acetic acid, propionic acid, butyric acid, methane, hydrogen