(218c) Spiroid Design Optimization in a Rotating Continuous Bioreactor for Enhanced Oxygen Mass Transfer

Research on continuous bioreactors requires new methods to improve mixing and mass transfer to increase cell production. The high shear stress from mechanical impellers typically results in greater cell death, especially for mammalian cells. An internal spiroid in a rotating continuous bioreactor provides an alternative for enhanced oxygen transfer and mixing to produce more viable cells. The tubular spiroid collects liquid and gas from the partially-filled rotating bioreactor near the reactor exit and delivers the gas and liquid to the reactor entrance. Computational fluid dynamic simulations were utilized in determining the optimum dimensions of an internal spiroid. The mass transfer coefficients were estimated for the reactor with and without the spiroid using theoretical models to determine the projected increase in oxygen transfer. These values were compared to published experimental values at various rotational rates. Calculated volumetric mass transfer coefficients provided a basis for optimizing the design of the spiroid. This study also determined the dependency of oxygen transfer rate and mixing on the diameter, length and other significant factors of the spiroid at several bioreactor rotational rates. The design of the spiroid included the changing fluid properties due to cell growth.