Growth of Chlorella vulgaris Under Atmospheric CO2 in Lab-Scale Photobioreactors: Effects of Aeration Rate and Growth Model Comparison

This study presents the results of an experimental investigation on the growth of the microalga <i>Chlorella vulgaris</i> in laboratory-scale photobioreactors under different aeration intensities: 0.25-3.25 vvm (vessel volumes per minute). The experiments were conducted at room temperature (24.5-28.5 °C) under constant illumination and atmospheric CO₂ concentration (~0.04%). It was found that increasing the aeration intensity up to ~1.3 vvm was accompanied by an almost linear increase in biomass productivity (from 0.33 to 5 g/L) until reaching a plateau, beyond which further increase in aeration rate did not result in statistically significant differences. This behavior indicates the existence of an optimal aeration range for the studied system. To describe the growth kinetics, a comparative analysis of several mathematical models was performed, including the Logistic model, the modified Logistic model with lag phase, Gompertz model, and Baranyi-Roberts model. In addition, two new models were proposed-the Monod × Gauss model and a hybrid two-phase model. Both demonstrated high fitting accuracy for our experimental conditions and may be applied in photobioreactor design and aeration regime optimization under atmospheric CO₂ conditions in lab-scale photobioreactors.