A new hybrid photobioreactor design for microalgae culture

Abstract

The objective of this study was to develop a new design of photobioreactor for microalgae culture. Hydrodynamic characterization, growth kinetics, removal of carbon dioxide and oxygen release rates, carbon and energy balances, and requirements of the surface area were determined. The results showed that the hybrid photobioreactor presented high hydrodynamic performance (mixing time of 98s, circulation time of 39s, Reynolds number of 2500 and empty bed residence time of 60s). The carbon dioxide bioconversion kinetics for Scenedesmus obliquus CPCC05 showed maximum specific growth rates of 0.96 d−1, and a maximum cell biomass of 2.8 kg/m³. In parallel, an average carbon dioxide conversion and oxygen release rates of 45.32 kgCO2/m³/d and 33.98 kgO2/m³/d were obtained, respectively. The carbon balance indicated that a small fraction (1.28%) of the carbon dioxide is fixed into a biomass form. Volatile organic compounds (82.75%) were the main products formed in the photobioreactor. The energy balance provided a net energy ratio of 2.49. Finally, this photobioreactor configuration requires a volumetric surface area in order to 0.22 m²/m³.