A bench-scale rotating bioreactor with improved oxygen transfer and cell growth

•A scaled-up bioreactor with spiroid showed improvement in oxygen transfer.•The operating time of the bioreactor was reduced by 33% in batch using a spiroid.•E. coli experiments confirmed the enhanced oxygen transfer using a spiroid. A prototype novel multiphase rotating bioreactor with an internal spiroid was shown to enhance oxygen delivery. This bioreactor was scaled up from 1.11 × 10-4 m3 to 9.86 × 10-4 m3 to enable the evaluation of its potential for scaled cell production. The internal spiroid occupying the inside wall of the bioreactor was shown to increase the liquid–gas interface during rotation of the horizontal cylinder, leading to better oxygen transfer performance and decreasing oxygen saturation time by almost half. Oxygen measurements were conducted at different operating conditions and the corresponding volumetric mass transfer coefficients (kLa) were obtained by a mathematical model to compare the oxygen transfer performance in the bioreactor with and without the spiroid. The results showed that kLa was increased by about 20% when employing the spiroid. E. coli cells were cultivated to demonstrate enhanced biomass production. The results showed an increase of 11% in cells and a 33% reduction in operating time in batch mode by using the bioreactor with the spiroid. Moreover, this novel bioreactor is also capable of growing and harvesting cells continuously.