Heterotrophic cultivation of microalgae in photobioreactor using low cost crude glycerol for enhanced biodiesel production

Abstract

This integrated approach first time investigates the use of crude glycerol (CG), a primary by product of the biodiesel production, for heterotrophic cultivation of microalgae (namely, Chlorella sp.) in photobioreactor (PBR) to enhance biodiesel production. The glycerol was reported 28.5 ± 0.70% in CG, causing nearly two folds increase in biomass productivity (446.50 ± 1.50 mg L−1day−1) and nearly four folds enhanced lipid productivity (165.15 ± 0.55 mg L−1 day−1) for the algal cells cultivated in PBR with addition of CG (PBR+CG) system as compared to Bold's Basal media (BBM) used as control. The total lipid content (34.36 ± 0.51%) was also doubled for the cells grown in PBR+CG system than in BBM. The analysis of fatty acid methyl esters (FAMEs) profile by GC-MS showed reduction in total unsaturated fatty acids and poly unsaturated fatty acids, and increase in total saturated fatty acids (SFAs) for the biodiesel obtained from algal cells grown in PBR+CG system. Moreover, the physical properties estimation also specified higher cetane number (53.89) and average oxidative stability (3.41 h), which are comparable with ASTM D6751 and EN 14214 fuel standards. This study demonstrates the potential of the use of CG for enhancing the low cost biodiesel production for vehicular transportation.