Simulation of microalgae growth in limiting light conditions: Flow effect

Abstract

Effect of hydrodynamical conditions on a microalgae culture growth was investigated in a photobioreactor with annular light chambers, with the focus on the relation between the cell displacement and the amount of light received by microorganisms, by comparing two different flow conditions in light chambers: an axial flow generating a poor radial mixing and a 3‐D swirling motion. To determine microorganism trajectories, a Lagrangian approach was retained, allowing light received to be considered from a single microalga point of view. The light distribution was calculated using Beer–Lambert law, and a biological modeling of the culture growth was proposed, with consideration of light/dark cycle effects induced by cell displacement in the depth of the culture. Finally, batch cultures of Porphyridium purpureum were simulated for both hydrodynamical conditions in light chambers. The advantage of applying a three‐dimensional motion to generate cell renewal in front of the light source, allowing microorganisms to use light more efficiently, is clearly shown.

Cell weight kinetics simulation in chemostat and batch culture of the rhodophyte Porphyridium cruentum

“…All of these features make them easy to count. Chemostat and batch cultures of P. cruentum from the Göttingen collection (B 112.79) were performed in a 100-L artificial light photobioreactor described by Muller-Feuga et al (1998 and Pruvost et al (2002). The process allows phototrophic production of microorganisms in sufficient amounts for cell weight samples to be taken without interfering with the culturing itself.…”

Influence of limiting factors on biomass and lipid productivities of axenic Chlorella vulgaris in photobioreactor under chemostat cultivation

“…Thirdly, light was the major limiting resource in this cylindrical PBR as confirmed from stages 3-5 (Cuaresma et al, 2011;Pruvost et al, 2002;Richmond, 1996).…”

Model-supported optimization of phototrophic growth in a stirred-tank photobioreactor

“…The well-known Beer-Lambert law has been widely used to describe local irradiances inside the photobioreactors with different geometries (Csögör et al, 1999(Csögör et al, , 2001a(Csögör et al, , 2001bFleck and Posten, 2003;García Camacho et al, 1999;Li et al, 2003;Muller-Feuga et al, 2003;Rorrer and Mullikin, 1999;Pruvost et al, 2002), even when it does not fulfill some of the basic assumptions for its validity (low concentrations, small light pathways, mono-chromatic light, no light scattering, etc.). Considering photobioreactors, alternative approaches of the Beer-Lambert law incorporate light scattering effects to overcome its limitations Evers, 1991;Molina Grima et al, 1999), while some others make use of hyperbolic models to empirically describe attenuation of light in media (Acién Fernandez et al, 1997;Reynolds and Pacala, 1993;Suh and Lee, 2001;Su et al, 2003;Walter et al, 2003;Weissing and Huisman, 1994).…”

“…Biomass productivity in a photobioreactor depends not only on the nutritional and environmental factors, but also is more closely related to the light regime and fluid-dynamics to which the cells are subjected (Luo and Al-Dahhan, 2004;Merchuk and Wu, 2003;Molina Grima et al, 1999;Pruvost et al, 2002;Wu and Merchuk, 2001). As a consequence of mutual shading and absorption, light is attenuated while penetrating into dense cell cultures generating a heterogeneous radiation profile.…”