Estimation of carbon dioxide sequestration potential of microalgae grown in a batch photobioreactor

•High algal growth rate observed with continuous flow of 10% CO2 enriched air.•Moles of CO2 sequestered was determined by mass balance and graphical integration.•Both strains exhibited maximum carbon sequestration at gas flow rate of 40 ml/min.•Good correlation observed between moles of CO2 sequestered and algal growth rate.•Chlorella pyrenoidosa sequestered CO2 more effectively than Scenedesmus abundans.

The carbon dioxide (CO2) sequestration potential of two microalgae, Chlorella pyrenoidosa and Scenedesmus abundans was evaluated in a tubular batch photobioreactor with provision for continuous flow of 10% CO2 enriched air through the headspace. CO2 sequestration and biomass growth was affected by gas flow rate over the range 20–60 ml/min and 40 ml/min was found to maximize algal growth and CO2 sequestration. Moles of CO2 sequestered over 20 h at a gas flow rate of 40 ml/min was estimated using a novel rapid screening approach as 0.096 and 0.036, respectively, for C. pyrenoidosa and S. abundans. At this gas flow rate the maximum growth rate was 4.9 mg L−1 h−1 and 2.5 mg L−1 h−1 for C. pyrenoidosa and S. abundans, respectively. The CO2 sequestration and growth rate were comparable at height/diameter ratio of 8 and 16.