Evaluation of effective nutritional parameters for Scenedesmus sp microalgae culturing in a photobioreactor for biodiesel production

Recently, microalgae are considered as lipid sources for biodiesel production. A photobioreactor was designed and fabricated for Scenedesmus sp. microalgae cultivation. The effect of several nitrogen sources, light intensity, iron ions, silicon, magnesium sulfate and ethanol concentrations on Scenedesmus sp. microalgae growth were investigated. For incubation period of 8 days, sodium nitrate and ammonium carbonate were the best nitrogen sources with biomass concentrations of 2.373 and 2.254 g L-1, respectively. Microalgae growth was reduced using nitrogen concentrations above 0.7 g L-1. In the first 10 days of incubation, maximum cell dry weight (0.7 g L-1) was obtained with light intensity of 10,000 lx, whiles after that, the results were desired (1 g L-1) using interior lighting at 7500 lx. Magnesium sulfate had a positive effect on cell growth. The biomass concentration of 1.65 g L-1 was obtained using 0.06 g L-1 magnesium sulfate. Maximum obtained biomass with silicon (0.7 Mm), ethanol (1.8 mL L-1) and ferric ammonium citrate (0.02 g L-1) was 1.7 and 1.3 and 2.16 g L-1, respectively. Logistic model was found to be a suitable model for cell growth forecast. Fatty acid analysis showed that composition of the most dominant synthesized fatty acids, palmitic and oleic acids, was 21.16 and 33.58%, respectively. Oil produced by Scenedesmus sp. microalgae composed of 49.08% saturated and 43.53% unsaturated fatty acids has a suitable composition for a desired biodiesel.