Enhancing CO₂ utilization by a physical absorption-based technique in microalgae culture

Carbon dioxide supplementation is significant for cell growth in autotrophic cultures of microalgae. However, the CO₂ utilization efficiency is quite low in most processes. Aimed at this problem, six kinds of physical absorption enhancers were investigated to enhance the biological carbon sequestration of microalgae. By the addition of a small amount of CO₂ absorption enhancer, the total inorganic carbon concentration of the medium was significantly increased. In addition, the biomass productivity of Scenedesmus dimorphus was maximally increased by 63% by the addition of propylene carbonate in flask cultures. In cultures using an air-lift photobioreactor equipped with a pH-feedback control system to supply CO₂, the CO₂ consumption was maximally reduced by 71% with added polyethylene glycol dimethyl ether. This study indicates that the incorporation of physical absorption enhancers could be a promising approach to overcome the problems of low CO₂ utilization efficiency and high carbon source cost in algal biomass production.