The effect of antifoam agents on mass transfer in bioreactors

The influence of antifoam agents on the liquid-phase mass transfer coefficient in stirred tank and bubble column bioreactors is studied. A physical model based on a surface-renewal concept and additional data in 40-dm³ bubble column bioreactor are presented. Comparisons between the physical model and the data indicate that the model predicts the maximum influence of antifoam agents on the liquid-phase mass transfer coefficient.List of Symbols a 1/m specific surface area - D m²/s diffusivity - D _c m bubble column diameter - d _vs m bubble diameter - g m/s² gravitational acceleration - k _L m/s liquid-phase mass transfer coefficient - k _LO m/s liquid-phase mass transfer coefficient for clean surface - N 1/s impeller speed - Sc Schmidt number (v/D) - U _sg m/s superficial gas velocity Greek Letters W/kg energy dissipation rate per unit mass - _g gas hold-up - Pa s viscosity - v m²/s kinematic viscosity - kg/m³ density - N/m surface tension