Mitigation of carbon dioxide by oleaginous microalgae for lipids and pigments production: Effect of light illumination and carbon dioxide feeding strategies

Oleaginous microalgae Nannochloropsis sp. was selected as potential strain for CO2 mitigation into lipids and pigments. The synergistic effects of light intensity and photoperiod were evaluated to provide the adequate light energy for this strain. The saturation light intensity was 60 μmol·photon·m−2 s−1. With full illumination, the biomass obtained was 0.850 ± 0.16 g·L−1 with a lipid content of 44.7 ± 1.2%. The pigments content increased with increasing light energy supply. Three main operating factors including initial cell concentration, CO2 content and gas flow rate were optimized through Response Surface Methodology. The feedings with low CO2 content at high gas flow rate gave the maximum biomass but with low lipid content. After optimization, the biomass and lipid production were increased up to 1.30 ± 0.103 g·L−1 and 0.515 ± 0.010 g·L−1, respectively. The CO2 fixation rate was as high as 0.729 ± 0.04 g·L−1 d−1. The fatty acids of Nannochloropsis sp. lipids were mainly C16-C18 indicating its potential use as biodiesel feedstocks.