Design and characterization of a scalable airlift flat panel photobioreactor for microalgae cultivation

Abstract

A novel flat panel photobioreactor prototype with bulk liquid flow driven by an external airlift was designed, modeled, and experimentally characterized for the purpose of developing scalable industrial photobioreactors. Baffles were built inside the flat panel part of the reactor, directing the liquid bulk flow in a serpentine way, and the external airlift drove the liquid flow and facilitated gas mass transfer. The gas holdup, liquid flow velocity, and oxygen mass transfer of this prototype were experimentally determined and mathematically modeled, and the performance of the reactor was tested by cultivating two species of microalgae, Scenedesmus obliquus and Chlorella sorokiniana. The model-predicted trends correlated well with experimental data, indicating that the reactor might be scaled up using these models. A high cell concentration of C. sorokiniana was achieved under controlled indoor cultivation conditions although serious biofouling occurred in the case of S. obliquus cultivation. The results favor the possibility of scaling up the reactor to industrial scales, based on the models employed, and the potential advantages and disadvantages of the reactor are discussed regarding this industry-oriented photobioreactor configuration in comparison with current industrial photobioreactors.