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 laser turbidity probe. A suspension of Bakers’ yeast (0.5−50 gl-1) was subjected to various conditions of agitation and aeration in a stirred tank reactor and the turbidity measured using the probe. Both agitation and aeration were found to influence the turbidity. At any constant biomass concentration, the effect on the turbidity measurement of changing agitation or aeration rate independently was linear, while at any constant conditions of agitation and aeration rate, the relationship between turbidity and biomass concentration was non-linear. The results indicate that, in a bioprocess with non-particulate medium, it is possible to correct for the effects of aeration and agitation on turbidity measurement using a multivariate calibration model. A procedure for calibration and correction of measurements for the effects of agitation and aeration is presented and is verified using experimental data. This procedure may be generalised for other applications.