Coupling Microalgae Productivity to Wastewater Treatment and Biofuel Production

Microalgae are emerging as one of the most promising agents for bioremediation through their abilities to remove polluting nutrients while converting biomass produced into lipids. In this study, growth and biomass productivity by microalgae strains, Chlorella vulgaris, Scenedesmus obliquus and TG511 (Gloeocystis vesiculosa) were evaluated for coupling wastewater treatment to biodiesel production. The isolates were heterotrophically cultured in filter-sterilized defined medium (BG11) or secondary municipal wastewater that was fortified with NaNO3 (0.25, 0.5 and 1 mg/L) to find the levels of nitrogen at which biomass productivities of C. vulgaris, S. obliquus and G. vesiculosa (TG511) would be optimized. The result showed that the biomass productivities of C. vulgaris, S. obliquus and G. vesiculosa cultivated in 1 mg/L NaNO 3 of modified BG11 were 3.64, 3.37 and 4.11 gram per liter respectively. Corresponding biomass productivities by the isolates in wastewater were 2.31, 1.27 and 1.78 grams per liter respectively. The nitrate removal efficiency by C. vulgaris, S. obliquus and G. vesiculosa at concentration of 1 mg/L W were 23.43, 4.61 and 20.48%, respectively. In the three isolate used, the commonly dominant Fatty Acid Methyl Esters were Palmitic, Oleic, Linoleic and Linolenic acid which ranged from is similar 16% to 30%, 17% to 57%, 4% to 44% and 4% to 21%, respectively. The high Oleic acid contents suggest that the three isolates used under varying concentrations of nitrogen are potential candidates for biodiesel production