Sustainable Energy via Biodiesel Production from Autotrophic and Mixotrophic Growth of the Microalga Phaeodactylum tricornutum in Compact Photobioreactors

The conditions for cultivation of microalgae Phaeodactylum tricornutum were studied with the objective of increasing algae lipid content for the production of biodiesel aiming at renewable energy generation. The variables investigated in the experiments were: salinity, carbon source (glycerol and glucose) and photoperiod. From the growth kinetics, and the analysis of biomass and lipid production, it was possible to determine the productivity of the studied microalgae species. The lipids production increased due to the addition of a carbon source to the culture medium. Furthermore, the carbon source addition in the beginning of the cultivation provided the best result. Among the tested salinity values in the experiments, the one that resulted in the highest microalgae growth was 15 %. The best assimilated carbon source by the microalgae was glycerol at a concentration of 0.1 M, providing cultures with up to 1.3 g/L of biomass. Mixotrophic cultivation with a photoperiod of 24 h of light in the presence of glycerol resulted in 338.97 mg/L of lipids, which was similar to 80% higher than the autotrophic one.