Surface-to-volume ratio influence on the growth of Scenedesmus obliquus in a thin-layer cascade system

Microalgae biomass is a source of a wide range of high commercial value compounds such as proteins, carotenoids, lipids and polysaccharides that have potential applications in several biotechnological processes. This study evaluated the influence of two different illuminated surface-to-volume-ratios (S/V) on the growth in cultivation of Scenedesmus obliquus in a thin-layer cascade system (TLC). Two S/V ratios (80 m−1 and 60 m−1) were used, corresponding to water columns of 0.5 cm and 1.0 cm, respectively. The cultures were compared in terms of the maximum biomass attained, volumetric and area productivities, photosynthetic efficiency, and CO2 fixation into biomass. The maximum biomass achieved was 20.14 g L−1 in SV80 cultures while the SV60 treatments attained 14.60 g L−1, with a maximum volumetric productivity of 2.42 and 1.85 g L−1 day−1, respectively. The culture with lower S/V was more efficient in relation to CO2 fixation, reaching 62% of the total carbon offered in comparison to the higher S/V (54%). Concerning the incident energy in the daylight period, both treatments presented similar photosynthetic efficiency values.