Control of Dissolved Oxygen in Stirred Bioreactors

Abstract This report discusses control of dissolved oxygen in a biore actor where the oxygen supply is manipulated using the stirrer speed. In batch and fedbatch cultivations the operating conditions change signifi cantly which may cause tuning problems. Analysis using a linearized pro cess model shows that the process dynamics is mainly affected by changes in the volumetric oxygen transfer coefficient KLa. To account for the pro cess variations, a control strategy based on PID control and gain schedul ing from the stirrer speed is suggested. This approach is straightforward to implement in an industrial control system. Experimental results from a laboratory reactor are presented