Assessment of wastewater algae for use in biofuel production

Abstract

Although new technologies have allowed the attainment of previously untapped fossil fuels these practises are unsustainable and harmful to the environment. Part of the solution to ease the fuel burden is through renewable fuels derived from microalgae as they are a carbon neutral source of fuel. The aim of this research was to assess if algae derived from municipal wastewater sources could be potential biofuel feedstocks by assessing their growth and fatty acid accumulation. When comparing wastewater derived algae to culture collection strains there was no significant difference (p>0.05) in terms of growth rates under photoautotrophic and mixotrophic conditions. The strain Botrydiopsis B2N under mixotrophic (14mM glucose) possessed the highest growth rate (2.7x104 cells•L-1•day-1) of all the strains tested under the various conditions. It was noted that under mixotrophic growth (14mM glucose) non-axenic algae accumulated significantly higher concentrations of neutral lipids compared to the same algal strains under axenic conditions. The result of which is thought to be caused by bacteria creating a nutrient deprived media causing the algae to become stressed and accumulate fatty acids. Under mixotrophic growth (14mM glucose and 3mM acetate) the organic carbon in the media appeared to shift the composition of fatty acids in most cases increasing the likelihood of an even blend of saturated to unsaturated fatty acids.