Investigation of growth limitation by CO2 mass transfer and inorganic carbon source for the microalga Chlorella vulgaris in a dedicated photobioreactor

An experiment was set up using a well-controlled photobioreactor to characterize the CO2 transfer and assimilation by photosynthetic microorganisms. This lab-scale system enabled accurate monitoring of the carbon sources in liquid and gas phases for in-depth characterization of the CO2 physical transfer and biological consumption of dissolved carbon. This paper presents a validation of the set-up by assessing the carbon mass balance in various absorption/desorption experiments. This is represented by the Carbon Recovery Percentage, which was found to be equal to 1 +/- 0.1 confirming the accuracy of the time monitoring for the various carbon fluxes. These carbon fluxes were modeled to determine on-line the gas-liquid mass transfer coefficient (k(L)a). This enabled investigation of some aspects of CO2 dissolution in water, such as the effect of the culture medium composition and its pH value. Finally, carbon assimilation and growth limitation by the carbon source were studied for the microalga Chlorella vulgaris. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study validated the accuracy of a well-controlled photobioreactor experiment setup and investigated the transfer and assimilation of CO2 in water by photosynthetic microorganisms. The gas-liquid mass transfer coefficient (k(L)a) was modeled to understand the dissolution of CO2 in water, affected by the composition of the culture medium and its pH value. Additionally, the carbon assimilation and growth limitation by the carbon source were studied for the microalga Chlorella vulgaris.