Mass Transfer in a Liter-Scale Wave Mixed Single-Use Bioreactor: Influence of Viscosity and Antifoaming Agent

Abstract

Wave mixed single-use bioreactors (also called rocking bioreactors) are a group of devices in which mixing is caused by characteristic wave-like movement of liquid inside a pillow-shaped bag mounted on a continuously oscillating platform. This study aimed to investigate the influence of liquid phase viscosity and the presence of an antifoaming agent on the mass transfer in a 2 liter single-use bag used in a ReadyToProcess WAVE 25 bioreactor system. The mass transfer rate was quantified by measuring the volumetric liquid-side mass transfer coefficient kLa using a gassing-out method. Two liquid phase mixture types were independently composed of Dulbecco’s modified Eagle medium or water and supplemented with fetal bovine serum (FBS). The viscosity of the liquid phases was modified with glycerin. The measurements were performed with and without the addition of a Pluronic F-68 antifoaming agent in a viscosity range of 0.9-4.2 mPa·s. It was shown that the viscosity of the liquid phase significantly impacts the values of the kLa coefficient, ranging from 0.8 to 3.7 h-1 at α = 7° and ω = 2 min-1. The addition of the antifoaming agent caused a decrease in the mass transfer rate. A correlation has been proposed for estimating kLa values as a function of the modified Reynolds number.