Estimation of CO2 stripping/CO2 microalgae consumption ratios in a bubble column photobioreactor using the analysis of the pH profiles. Application to Nannochloropsis oculata microalgae culture

Nannochloropsis oculata was grown in an outdoor bubble column photobioreactor. To obtain information about the behaviour of microalgae/photobioreactor system related to the CO2 net balance, an analysis of the pH profiles during microalgae growth was carried out. The use of the carbonate equilibrium chemistry and the overall CO2 volumetric mass transfer in the photobioreactor has permitted to obtain information of the CO2 losses/CO2 microalgae consumption ratios. The simplicity of the technique used (a pH probe) could extend the use of this methodology for the correct selection of the photobioreactor/microalgae parameters with the aim to maximize the [CO2 uptaken/(CO2 uptaken + CO2 stripped)] ratios.