(68a) Enhanced Oxygen Transfer and Cell Growth in a Scaled-up Multiphase Continuous Bioreactor with Internal Spiroid

A novel continuous bioreactor with internal spiroid has been designed to increase cell growth rate and overall productivity by improving oxygen delivery. The operation of this bioreactor is similar to a roller bottle, but it can be operated either in batch or continuous mode, with inlet flows available to provide medium and oxygen to the bioreactor. A spiroid embedded in the inside wall of the bioreactor was shown to increase the liquid-gas interface, leading to better oxygen transfer. This bioreactor was scaled up from 1.109 x 10^-4 m³ to 0.944 x 10^-3 m³ to enable evaluation of its potential for cell production. The scaling rules for this unique design were characterized in modeling and experimental studies. Oxygen measurements were conducted to determine oxygen transfer in the bioreactor with and without the spiroid at different operating conditions. In addition, mathematical models were established to simulate the oxygen transfer in the system and to calculate the volumetric mass transfer coefficients (k_La) in both chambers and the spiroid tube at different operating conditions. The new design (spiroid) improved oxygen transfer in the bioreactor by two to four fold. Growth curves for yeasts and mammalian cells in this continuous bioreactor with and without the spiroid were measured at different operating conditions to confirm improvement in oxygen transfer.

Key words: continuous bioreactor, oxygen transfer, cell cultivation, spiroid