Carbon dioxide bio-fixation by Chlorella sp. BTA 9031 towards biomass and lipid production: Optimization using Central Composite Design approach

Depletion in the fossil fuel reserves and the unceasing rise in the greenhouse gas emissions due to excessive use of fossil fuels has become a subject of worldwide concern. Production of microalgal biomass using the carbon dioxide (CO2) laden flue gas is identified as one of the potent solutions to the trap the excessive emissions of CO2 from entering into the atmosphere along with the production of renewable and sustainable biofuel thereby, combating both energy crisis and global warming. Understanding and optimizing the parameters affecting the microalgal growth process is crucial prerequisite for effective CO2 bio-fixation using microalgae in photobioreactors (PBRs). Chlorella sp. BTA 9031 was selected as a potential strain for biomass and lipid production under varying temperatures (20-40 °C), light intensity (30-100 μmol m−2 s−1) and CO2% (4-15%). These three main operating factors were optimized through Central Composite design (CCD) approach of Response Surface Methodology (RSM). The optimal conditions for attaining both maximum biomass and total lipid content were selected to be 28.26 °C, 76.64 μmol m−2 s−1 and 4.00% CO2. Under the optimum conditions, CO2 bio-fixation rate was observed to 0.235 g L−1 d−1 of Chlorella sp. BTA 9031. Confirmatory experiments confirmed that the model predictions were in good agreement with the experimental results.