Oxygen transport and consumption by suspended cells in microgravity: A multiphase analysis

A rotating bioreactor for the cell/tissue culture should be operated to obtain sufficient nutrient transfer and avoid damage to the culture materials. Thus, the objective of the present study is to determine the appropriate suspension conditionsfor thebead/celldistribution andevaluateoxygen transport in the rotating wall vessel (RWV) bioreactor. A numerical analysis of the RWV bioreactor is conducted by incorporating the Eulerian-Eulerian multiphase and oxygen transport equations. The bead size and rotating speed are the control variables in the calculations. The present results show that the rotating speed for appropriate suspensions needs to be increased as the size of the bead/cell increases: 10 rpm for 200 mm; 12 rpm for 300 mm; 14 rpm for 400 mm; 18 rpm for 600 mm. As the rotating speed and the bead size increase from 10 rpm/200 mm to 18 rpm/600 mm, the mean oxygen concentration in the 80% midzone of the vessel is increased by � 85% after 1-h rotation due to the highconvectiveflowfor18rpm/600 mmcaseascomparedto 10 rpm/200 mm case. The present results may serve as criteria to set the operating parameters for a RWV bio- reactor, such as the size of beads and the rotating speed, according to the growth of cell aggregates. In addition, it might provide a design parameter for an advanced suspen- sion bioreactor for 3-D engineered cell and tissue cultures. Biotechnol. Bioeng. 2008;99: 99-107. 2007 Wiley Periodicals, Inc.