Performance evaluation of a green process for microalgal CO2 sequestration in closed photobioreactor using flue gas generated in-situ

• CO2 fixation from industrial flue gas using Chlorella sp.
• Chlorella sp. tolerates gas stream with 5% of CO2 v/v.
• Different strategies to minimize toxic effect of flue gas compounds were evaluated.
• Biofixation efficiency was improved by 54%.

In the present study, carbon-dioxide capture from in situ generated flue gas was carried out using Chlorella sp. in bubble column photobioreactors to develop a cost effective process for concomitant carbon sequestration and biomass production. Firstly, a comparative analysis of CO2 sequestration with varying concentrations of CO2 in air-CO2 and air-flue gas mixtures was performed. Chlorella sp. was found to be tolerant to 5% CO2 concentration. Subsequently, inhibitory effect of pure flue gas was minimized using various strategies like use of high initial cell density and photobioreactors in series. The final biofixation efficiency was improved by 54% using the adopted strategies. Further, sequestered microalgal biomass was analyzed for various biochemical constituents for their use in food, feed or biofuel applications.