THE EFFECTS OF AERATION AND AGITATION ON THE MEASUREMENT OF YEAST BIOMASS USING A LASER TURBIDITY PROBE

The paper reports the measurement of biomass concentration using a las er turbidity probe. A suspension of Bakers' yeast (0.5 - 50 gl(-1)) wa s subjected to various conditions of agitation and aeration in a stirr ed tank reactor and the turbidity measured using the probe. Both agita tion and aeration were found to influence the turbidity. At any consta nt biomass concentration, the effect on the turbidity measurement of c hanging agitation or aeration rate independently was linear, while at any constant conditions of agitation and aeration rate, the relationsh ip between turbidity and biomass concentration was non-linear. The res ults indicate that, in a bioprocess with non-particurate medium, it is possible to correct for the effects of aeration and agitation on turb idity measurement using a multivariate calibration model. A procedure for calibration and correction of measurements for the effects of agit ation and aeration is presented and is verified using experimental dat a. This procedure may be generalised for other applications.