THE INFLUENCE OF PHYSICAL-PROPERTIES ON THE OPERATION OF A 3-PHASE FLUIDIZED-BED FERMENTER WITH YEAST-CELLS IMMOBILIZED IN CA-ALGINATE

A three-phase fluidized-bed bioreactor with Ca-alginate immobilized yeast cells in which an external air stream is introduced to promote and maintain fluidization was studied with respect to its characterization and air-flow optimization. The fluidization behavior is very strongly dependent on the physical properties of both liquid and solid phases (liquid viscosity, density, surface tension, and solid density). Satisfactory or unsatisfactory fluidization behavior could be determined in a graph on the basis of two parameters calculated with the values of the physical properties. A correlation on the minimum air-flow rate necessary to obtain acceptable fluidization of the immobilized yeast beads was developed using experimental data obtained in two fermentors with different L/D ratios.