ON THE MASS-CULTURE OF MICROALGAE - AREAL DENSITY AS AN IMPORTANT FACTOR FOR ACHIEVING MAXIMAL PRODUCTIVITY

Scenedesmus obliquus was grown in a bioreactor under constant light and at a temperature of 24 degree C. From measurements of biomass production, it was possible to determine the influence of areal density on productivity in open as well as closed cultures. Maximal productivity occurred at an areal density of 40 to 45 g(dw) m** minus **2, which was in good agreement with predicted values from a model. The optimal areal density for maximal productivity was influenced by factors such as culture depth, algal species, turbulence, available light, etc. , and hence the establishment and maintenance of an optimal areal density are seen as some of the most important operational procedures for the mass culture of algae. Supersaturated concentrations of oxygen resulted in lower productivities due to photorespiration and/or oxidation.