Jet loop photobioreactor for enhanced $CO_2$ mass transfer in microalgal culture

Abstract

Continued attentions on fossil fuel depletion and environmental pollution have prompted the development of renewable energy in recent years. Among carbon neutral energy sources, microalgae has been a promising feedstock for renewable energy source. In this study, a jet loop photobioreactor (JLPBR) was developed for enhanced $CO_2$ mass transfer and cultivation of Chlorella sp. ABC-001 comparing to conventional types of photobioreactor. It is confirmed that mass transfer rate and microalgal lipid concentration in the JLPBR was about three times higher that of controls. Furthermore, the effect of hole size and number of the perforated cylinder in the JLPBR was investigated. Mass transfer rate increased when total hole area of the perforated cylinder decreased. Incidentally, jet velocity at each hole increased as total hole area of perforated cylinder decreased. That’s why a linear relationship between mass transfer coefficients and jet velocity was shown. The highest performance of microalgal growth was shown in the JLPBR with 0.5 mm/20 holes. Furthermore, lipid content in cells increased when mass transfer rate increased. This is because hydrodynamic shear forces might increase with mass transfer rate, which caused to form reactive oxygen species inducing lipid accumulation. Therefore, it is expected to be successfully applied to cultivation of Chlorella sp. ABC-001 showing high biomass and lipid production.