Numerical and experimental study on the performance of flat-plate photobioreactors with different inner structures for microalgae cultivation

Abstract

Three types of 15-L flat-plate photobioreactors (PBRs), namely, bubble reactor, split flat-plate airlift reactor, and central flat-plate airlift reactor, were investigated for their performance based on numerical and experimental methods. The computational fluid dynamics (CFD) method was used to calculate mixing and light regime characteristics parameters of PBRs. The performance of flat-plate PBRs was preliminarily evaluated according to the light–dark cycle of algal cells and fluid mixing along the light attenuation direction. The analysis showed that the optimal PBR was the split airlift type, whereas the bubble PBR was the poorest. The photoautotrophic cultivation of Chlorella pyrenoidosa was conducted to confirm the actual performance of PBRs. The result of microalgae culture experiment showed the biomass productivity in split airlift reactor was 0.018 g L−1 h−1 which was 50 and 12.5 % higher than those in bubble and central airlift PBRs, respectively. The maximum biomass concentration and specific growth rate of algal cell in split flat-plate airlift reactor were greatest, and those in bubble reactor were lowest. Therefore, the experiment results are completely consistent with those obtained through the computational approach, suggesting the numerical model combining fluid hydrodynamics with irradiation transfer as well as statistical treatment developed in this study can be applied to optimize and evaluate the performance of PBRs efficiently.