Stirred-Tank Photobioreactors

Stirred-tank photobioreactors are the conventional reactor setup in which agitation is provided mechanically with the help of impellers or baffles by providing illumination exter­nally. CO2-enriched air is bubbled at the bottom to provide a carbon source for algae growth (Petkov, 2000; Demessie and Bekele, 2003). Protoceratium reticulatum growth studied in 2 L and 15 L stirred photobioreactors equipped with internal spin filters showed average biomass cell productivity 3.7 times higher than that of the static cultures (Camacho et al., 2011). Low surface-area-to-volume ratio, which in turn decreases light-harvesting efficiency, is the inher­ent disadvantage of this system. Low surface-area-to-volume ratio and high shear stress imposed due to mechanical agitation limits this reactor’s use in CO2 sequestration (Demessie and Bekele, 2003).