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

We report experimental data of mass transfer of oxygen into yeast resu spension in a pulsed baffled bioreactor. The bioreactor consists of a 5O-mm-diameter column with the presence of a series of either wall (or ifice) or central (disc) baffles or a mixture of both where fluid osci llation can also be superimposed during the experiments. Air bubbles a re sparged into the bottom of the pulsed baffled bioreactor, and the k inetics of liquid oxygen concentration in the yeast solution is follow ed using a dissolved oxygen probe with a fast response time of 3 s tog ether with the dynamic gassing-out technique. Among the three differen t 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 observe d 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 1 1% increase in the k(L)a is reported. (C) 1995 John Wiley & Sons, Inc.