Simple Control Systems for Set-point Control of Dissolved Oxygen Concentration in Batch Fermentation Processes

Abstract

Dissolved oxygen concentration (DOC) is one of the most important technological parameters of fermentation processes influencing the physiological state of microorganisms’ cultures, production of desired products and reproducibility of desired processes. However, automatic set-point control of DOC in batch and fed-batch fermentation processes is not a trivial control task, as the resulting dynamic parameters (gain coefficient, time constant and time delay) of the control channel “agitation speed – DOC” vary over a wide range, and the ordinary PI or PID controllers with fixed tuning parameters are insufficient for accurate control of DOC during the entire control course. In this text, two control approaches have been proposed for coping with the problems of nonlinear and non-stationary dynamics of the DOC control process.