Microalgae growth kinetic model based on the PSII quantum yield and its utilization in the operational curves construction

In this study, a microalgae growth kinetic model based on its PSII quantum yield was built. It was used to simulate the following operational curves: microalgae concentration - dilution rate (X-D) and volumetric cell productivity - dilution rate (Q-D) in a continuous culture. The model considers 8 parameters particular for the microalgae species and its condition and 2 operational parameters (irradiance and flat plate photo-bioreactor (FPB) light path). The model was tested in a Scenedesmus obliquus continuous culture in FPB at a constant irradiance of 300 μmol·m^-2 s^-1 and a dilution rate range of (0.16 to 2.7 d^-1), with CO₂-enriched air at 2%. The microalgae kinetic parameters were determined independently by means of simple methodologies, which were used to simulate the X-D and Q_x-D operational curves. A very good correlation with the experimental results was found (correlation coefficient of 0.993 for the X-D curve). The optimal operating point to maximize the experimentally determined cell volumetric productivity was D = 0.84 d^-1, while the model determined a value of D = 1 d^-1.