Influence of light stratification on the growth of Scenedesmus quadricauda

Abstract

Light availability and light stratification within any photobioreactor and their impact on the growth of microalgaeare important issues in the analysis, modeling and design of a photobioreactor. In this work, the microalgaScenedesmus quadricauda was grown in a laboratory scale photobioreactor irradiated with different arrangementsof white LEDs giving rise to different degrees of light stratification within the culture medium. To ensure that theobserved effects were solely caused by the inhomogeneity of the radiation field properties, the different arrangementsof LEDs were required that they emit the same total number of photons per unit time and per unitvolume of culture. Assessment of light availability in the culture medium was made using the volumetric averagerate of photon absorption and the distribution function of volumetric photons absorption rates. The resultsobtained highlight the importance of systematically quantifying the degree of stratification of light in the culturemedium for the purpose of optimization and scaling up of photobioreactors.