Reduction of carbon loss from the effluent is one of the most important aspects of photobioreactors design. In this study, a novel gas sparger of bubble tank was adopted in a photobioreactor to enhance carbon dioxide (CO2) mass transfer rate as well as alleviate dissolved oxygen (DO) accumulation. The results showed that low DO level in the culture can be obtained due to the turbulent hydrodynamic condition provided by the bubble tank. The effects of CO2 concentration, flow rate of influent, and light intensity on CO2 removal efficiency were investigated. The maximum CO2 removal efficiency was 94% at flow rate of 30 mL min(-1), light intensity of 179 mu mol m(-2) s(-1) and CO2 concentration of 10%, implying that the novel gas sparger is a promising alternative for CO2 removal from CO2-enriched air by cultivating microalgae in the photobioreactor. (C) 2012 Elsevier Ltd. All rights reserved.