Department of Ocean & Resources Engineering Seminar IMPROVING MASS TRANSFER IN A TUBULAR PHOTOBIOREACTOR

A modified tubular photobioreactor was constructed at the J.J. Look Laboratory. The design of this reactor was based on the Tredici-design near-horizontal tubular photobioreactors already present at this facility, but incorporated several features designed to improve mass transfer of carbon dioxide into the liquid phase, facilitate the stripping of photosynthetically produced oxygen, and improve the effectiveness of the cooling system. Hydrodynamics and mass transfer of carbon dioxide and oxygen were characterized and compared with those in an unmodified Tredici-design reactor. The modified design had decreased mixing and circulation times, as well as higher mass transfer coefficients for carbon dioxide and oxygen, than did the original design. In addition, lower operating temperatures were achievable with the modified cooling system. Results suggest that the modified reactor will be more efficient in its use of carbon dioxide (the carbon source for algal growth), that growth inhibition by oxygen will be less likely, and that it will be possible to grow microalgae with lower temperature optima than in the original reactors.