Multifunctional fluorocarbon photobioreactor system: a novel integrated device for CO₂ segregation, O₂ collection, and enhancement of microalgae growth and bioproductions

An enhanced greenhouse effect due to high CO₂ emissions has become one of the most concerning issues worldwide. Although plant/algae-mediated approaches have been extensively used for CO₂ segregation in the last decades, these methods are generally aimed at environment protection. In contrast, less attention has been given to CO₂ manipulation that has regrettably caused a decrease in the commercial availability of the associated technologies. To generate a system for practical use, a synthetic fluorocarbon photobioreactor system (FCPBRS) consisting of a CO₂ isolation unit, a gas modulation unit, an O₂ collection unit, and a microalgal culture chamber was developed in this study. After injecting a 60%-N₂/40%-CO₂ gas mixture into the CO₂ isolation unit for 10 days, the results showed that the FCPBRS enabled a > 93% CO₂ separation efficiency using a fluorocarbon liquid FC-40 as the CO₂ adsorbent. In addition, the growth rate of Nannochloropsis oculata was significantly enhanced when cultured with 20 mL min⁻¹ of the FC-40 flow containing 2% CO₂ throughout the time course, resulting in 4.7-, 4.6-, and 4.5-fold (P < 0.05 for each) increases in biomass, total lipid, and eicosapentaenoic acid yields, respectively, compared to the aerated group without FC-40. Moreover, approximately 1600 mL of photosynthetic O₂ with a ~ 80% collection efficiency was obtained in the O₂ collection unit within 10 days of FCPBRS operation. These outcomes indicate that the FCPBRS may provide a feasible means to simultaneously achieve CO₂ isolation, O₂ collection, and enhanced microalgae bioproductions.