Continuous cell suspension processing using magnetically stabilized fluidized beds.

The behavior of a cell suspension in a continuous magnetically stabilized fluidized bed (MSFB) was investigated both experimentally and theoretically. The low, constant pressure drop and fluidity of the solids phase in the MSFB allowed a continuous countercurrent separator to be constructed. The magnetic field eliminated all motion of the solids phase (nickel spheres) and produced a device similar to a packed-bed depth filter. Yeast cells were used as the suspended solids and the performance of the MSFB filter was assessed as a function of the bed height, solids velocity, cell concentration, and liquid composition. Removal rates could be adjusted by controlling the cell/support interaction and were found to be as high as 99%. A mathematical model was used to aid in understanding this filtration and was found to agree qualitatively with all experimental observations. Comparison of the model with the data suggests that both cell/cell binding and cell shadowing are occurring.