Large-Scale Cultivation of Spirulina for Biological CO₂ Mitigation in Open Raceway Ponds Using Purified CO₂ From a...

In order to select excellent strains with high CO₂ fixation capability on a large scale, nine Spirulina species were cultivated in columnar photobioreactors with the addition of 10% CO₂. The two species selected (208 and 220) were optimized for pH value, total dissolved inorganic carbon (DIC), and phosphorus content with intermittent CO₂ addition in 4 m² indoor raceway ponds. On the basis of biomass accumulation and CO₂ fixation rate in the present study, the optimum pH, DIC, and phosphate concentration were 9.5, 0.1 mol L^-1, and 200 mg L^-1 for both strains, respectively. Lastly, the two strains selected were semi-continuously cultivated successfully for CO₂ mitigation in 605 m² raceway ponds aerated with food-grade CO₂ purified from a coal chemical flue gas on a large scale. The daily average biomass dry weight of the two stains reached up to 18.7 and 13.2 g m^-2 d^-1, respectively, suggesting the two Spirulina strains can be utilized for mass production.