Modeling, simulation, and optimization of the centrifugal separation of a microalgae-culture medium mixture

Abstract

The present paper aimed to develop a simple transient mathematical model to analyze the centrifugal separation of microalgae particles dispersed in a culture medium, considering a two-phase mixture: a dispersed (microalgae) and a continuous (culture medium) phase. Mass balances were written for the dispersed phase in the suspension zone for the interface between suspension and sediment, and the mixture, resulting in an EDO system. The mathematical model was adjusted according to experimental data and, thus, it was possible to predict the volume fraction profiles of microalgae in the suspension, the fraction of residual particles in the clarified, and the sediment thickness. It can be predicted that the capture efficiency was 97.5%. The optimization showed that rotation should be higher, while the mass flow rate should be lower than those originally used in the centrifuge operation, resulting in capture efficiencies of 98.5% and 97.7%, respectively. Geometry optimization revealed that the centrifuge basket must be higher and have a diameter smaller than that of the original geometry, whose capture efficiency was 97.8%. Finally, for all optimized cases, the values of the energy efficiency indicator were lower than the value for the original case, reaching a reduction of up to 21.9% of the energy required in the process for each dollar of profit.