Biofuel conversion of Chlorococcum sp. and Scenedesmus sp. biomass by one- and two-step transesterification

The aim of this paper was to investigate the optimum transesterification method for the production of biodiesel from microalgae. Chlorococcum sp . and Scenedesmus sp . cultivated in secondary treated municipal wastewater and in 1/3N BG-11 medium, respectively, were selected for the conversion of their lipids by one- and two-step transesterification processes. Sulfuric acid and sodium hydroxide catalysts were separately employed in one-step transesterification process, and a two-stage process employing the basic catalyst followed by the acidic one in the second step was also used. The quality of the produced biodiesel was strongly determined by the catalyst used. The analysis of fatty acid methyl esters of the Chlorococcum sp. lipids showed that the two-step process has similar effects compared with one-step with acid (21.56 and 21.85 mg of fatty acid methyl esters (FAMEs), respectively). On the other hand, better results were obtained through the two-step process with the Scenedesmus sp. (40.51 mg of FAMEs), compared with one-step methods with acid and base catalysts (9.57 and 22.3 mg of FAMEs, respectively). The type of methyl esters produced is strongly depended on the type of algal species and growth conditions.