Effect of superficial gas velocity on CO2 capture from air by Chlorella vulgaris microalgae in an Airlift photobioreactor with external sparger

The world is becoming warmer due to the increase of greenhouses gas release, particularly CO2. The bio-fixation process in the bioreactor is one of the environment-friendly methods for CO2 capture and prevention of CO2 entry to the atmosphere. In the present study, the hydrodynamic comparison of internal and external spargers in an airlift bioreactor with air-water system and CO2 bio-fixation study is conducted under different gas velocities at the temperature of 25 +/- 2 degrees C. The present study aims to investigate input gas velocity effect on fixation of CO2 by Chlorella vulgaris microalgae in an airlift reactor with an external sparger. The study shows that the hydrodynamic result of internal and external spargers strongly depends on the riser and downcomer crosssectional area. Additionally, the results indicate that Chlorella vulgaris can growth to 26.95 x 10(6) cell/mL and remove the CO2 by 94% efficiency in the lowest superficial gas velocity of 1.88 x 10(-3) m/s.