STUDY OF MASS-TRANSFER IN YEAST IN A PULSED BAFFLED BIOREACTOR

We report experimental data of mass transfer of oxygen into yeast resuspension in a pulsed baffled bioreactor. The bioreactor consists of a 5O-mm-diameter column with the presence of a series of either wall (orifice) or central (disc) baffles or a mixture of both where fluid oscillation can also be superimposed during the experiments. Air bubbles are sparged into the bottom of the pulsed baffled bioreactor, and the kinetics of liquid oxygen concentration in the yeast solution is followed using a dissolved oxygen probe with a fast response time of 3 s together with the dynamic gassing-out technique. Among the three different baffle geometries investigated, the orifice baffles gave the highest and sharpest increase in the oxygen transfer rate, and the trends in the k(L)a measurements are consistent with the fluid mechanics observed within both the systems and previous work. In addition, we have also compared the k(L)a values with those obtained in a stirred tank; an 11% increase in the k(L)a is reported. (C) 1995 John Wiley & Sons, Inc.