Qualitative biodiesel production from a locally isolated chlorophycean microalga Scenedesmus obliquus (Turpin) Kützing GA 45 under closed raceway pond cultivation

Abstract

The energy security scenario in the world would remain at high risk until non-conventional, indigenously produced renewable biofuels replace/supplement petroleum-based conventional fossil fuels. In the present study, an indigenously isolated chlorophycean microalga, Scenedesmus obliquus (Turpin) Kützing GA 45, was explored under raceway pond cultivation to assess its potential for production of lipids for qualitative biodiesel purpose. Microalgal cultivation was carried out in closed raceway ponds (14 × 4 × 0.75 m) with a capacity of 40,000 L each. The maximum areal biomass and lipid productivities were recorded to be 13.12 and 1.39 g m−2 day−1 at 30 cm culture depth during winter season followed by summer and rainy seasons. Under biphasic nitrogen starvation strategy, the maximum lipid productivity increased up to 2.29, 1.88, and 2.43 g m−2 day−1, respectively during summer, rainy, and winter seasons. The average lipid productivity was consequently calculated to be 2.2 g m−2 day−1, thus projecting an approximate annual lipid productivity of 7.04 t ha−1 y−1, assuming 10 cultivation cycles per year. Characterization of various fuel properties of the biodiesel produced, were found to be within the specified limits of national and international biodiesel standards, thus signifying the potential of the new isolate S. obliquus GA 45 for qualitative biodiesel production.