Isolation, mass cultivation, and biodiesel production potential of marine microalgae identified from Bay of Bengal

In this study, marine microalgae were isolated from the Bay of Bengal, and their biodiesel production potential was investigated. Five different strains of microalgae were identified, viz. Nannochloropsis salina (N. salina), Dunaliella salina (D. salina), Chaetoceros calcitrans (C. calcitrans), Tetraselmis chuii (T. chuii), and Euglena sanguinea (E. sanguinea). Further, these stains were mass cultivated in a 250-L bioreactor to assess their biomass production ability. At the end of the exponential phase, algal biomass was harvested for lipid extraction. The fatty acid profile and physico-chemical properties of the lipids were analyzed. It was observed that a maximum of 27.67wt% of lipid was obtained for N. salina followed by D. salina (22.58 wt%), E. sanguinea (21.88 wt%), T. chuii (20.15 wt%), and C. calcitrans (16.25 wt%). Subsequently, the extracted lipids were subjected to single-step esterification and transesterification process to produce biodiesel by using an acid catalyst. The different parameters influencing the reaction such as catalyst concentration, temperature, methanol to lipid molar ratio, and time were investigated. A maximum biodiesel yield of 97, 94, 96, 92, and 92 wt% were obtained for N. salina, D. salina, C. calcitrans, T. chuii, and E. sanguinea, respectively, at the favorable reaction conditions. The fuel properties of biodiesel were analyzed as per the standard protocol and compared with ASTM D6751 standard.