A photobioreactor with pH control: demonstration by growth of the marine diatom Skeletonema costatum

A photobioreactor with pH control for cultivation of algae is described. The magnetically stirred culture flask is connected to separate reservoirs for medium and for acid and base (diluted HCl and NaOH, respectively). A pH electrode is inserted into the culture flask and coupled to a pH controller, which activates acid and base titration at set points of pH 8.1 and 7.8, respectively. Illumination is provided by light tubes with a diel light : dark cycle. The use of the photobioreactor in batch mode is illustrated by showing pH curves in different growth phases of the marine diatom Skeletonema costatum. The photobioreactor can also be run as a semicontinuous or continuous reactor with slight modifications.