Carbon Dioxide Sequestration by Spirulina Platensis in Photo-Bioreactors

Spirulina platensis was cultivated at small scale in photobioreactors for CO₂ sequestration experiments carried out at different CO₂ concentrations within the range 0.5 to 10%, temperatures 10 to 40°C and light intensities 60 to 200 mol s⁻¹ m⁻². CO₂ sequestration efficiency of achieved 99.9%, specific growth rate, doubling time, rate of CO₂ sequestered into the algal cells and small changes of pH found for each batch experiment. Spirulina Platensis adapted to a novel nutrient solution was cultivated to explore its capacity to sequester CO₂. The impacts CO₂ concentration, light intensity and temperature, on specific growth rate of Spirulina platensis and the adapted algae strain were described using empirical microbial growth kinetic models, Monod, Andrews and Mayo. The first two models described properly the effects of CO₂ concentration and light intensity whereas the third the impact of temperature. Kinetic parameters from each model estimated optimum growth conditions of Spirulina platensis (2.5% CO₂, 25°C, 60 to 100 mol s⁻¹ m⁻²) and Spirulina platensis adapted (2.5% CO₂, 25°C, 100 mol s⁻¹ m⁻²) photoinhibition pedicted for extreme growth conditions (10% CO₂, 40°C, 200 mol s⁻¹ m⁻²) with both algal culture. Given comparable productivity between Spirulina Platensis and its adopted it would be worthwhile to select the algae strain adopted to specie to be used for CO₂ sequestration using photobioreactors at commercial scale and the production of value-added products.