CFD simulation of algae production in airlift photobioreactor

The energy crisis has become a major problem in this energy-driven world, so there is a need to explore new ways to meet the energy demands. Production of biodiesel from algae is one such method. Algae production using present technologies is quite challenging. Because algae are known to grow in wastewater, a possible solution is to integrate algal production with treatment of nutrient-rich wastewater and utilization of CO2 from power plant flue gas. The present study focuses on simulation of algae production by photosynthesis in an airlift photobioreactor (PBR) in a batch process. The simulation studies are carried out using computational fluid dynamics (CFD) software, considering mass transfer of CO2 from gas phase to liquid phase and O2 from liquid phase to gas phase. The effect of geometry of PBR on hydrodynamic properties such as gas holdup and liquid circulation velocities are investigated. The results of the work are compared with past studies which did not consider the actual photosynthesis reaction. The results show (1) that algae production is not uniform throughout the PBR and (2) higher gas holdup due to the presence of algae produced in photosynthesis reaction. © 2017 American Society of Civil Engineers.