Effect of different pretreatment methods on lipid yield and biodiesel quality of Desmodesmus sp. isolated from Sri Lanka

Abstract

The present study investigates the growth rate and the effect of different pretreatment methods on lipid yield and biodiesel quality produced from Desmodesmus sp. isolated from Beira Lake, Colombo, Sri Lanka. Desmodesmus sp. was cultivated using photobioreactors providing the optimum cultivation conditions and growth was determined by measuring the optical density and direct cell count of the culture. Four different physical cell disruption methods including manual grinding, autoclaving, microwaving and water bath heating were carried out using chlorophyll removed microalgae biomass to investigate the effect of pretreatment on lipid yield and biodiesel quality. The highest lipid yield was obtained as 31.46 % for Desmodesmus sp. using water bath heating method. However, there was no significant impact on lipid yield after employing different cell disruption methods. In addition, chlorophyll removal reduced the lipid yield and increased the quality of the biodiesel produced from Desmodesmus sp. Furthermore, chlorophyll removal and cell disruption enhanced the quality of biodiesel by increasing the saturated fatty acid and monounsaturated fatty acid contents. Moreover, cetane number, higher heating value and iodine value of the biodiesel were within the acceptable range according to biodiesel quality standards. Therefore, Desmodesmus sp. can be identified as a potential source for microalgae biodiesel production