Dissolved oxygen control in fermentation

Levente Bodizs, Bala Srinivasan, Dominique Bonvin

Overview

Industrial filamentous fungal fermentations are typically operated in fed-batch mode. Oxygen control represents an important operational challenge due to the varying biomass concentration. In this study, oxygen control is implemented by manipulating the substrate feed rate, i.e. the rate of oxygen consumption. It turns out that the setpoint for dissolved oxygen represents a trade-off since a low dissolved oxygen value favors productivity but can also induce oxygen limitation. This project addresses the regulation of dissolved oxygen using a cascade control scheme that incorporates auxiliary measurements to improve the control performance. The computation of an appropriate setpoint profile for dissolved oxygen is solved via process optimization. For that purpose, an existing morphologically structured model is extended to include the effects of both low levels of oxygen on growth and  medium rheological properties on oxygen transfer. Experimental results obtained at the industrial pilot-scale level confirm the efficiency of the proposed control strategy but also illustrate the shortcomings of the process model at hand for optimizing the dissolved oxygen setpoints.

Keywords : Bioprocesses; Filamentous fungal fermentation; Rheological properties; Oxygen control; Dissolved oxygen setpoint; Cascade control;

 

Related publications

Journal Articles

2007

L. Bodizs; M. Titica; N. Faria; B. Srinivasan; D. Dochain et al. : Oxygen Control for an Industrial Pilot-Scale Fed-Batch Filamentous Fungal Fermentation; Journal of Process Control. 2007.

Conference Papers

2005

L. Bodizs; N. Faria; M. Titica; B. Srinivasan; H. Jorgensen et al. : Industrial experience with oxygen control of fed-batch filamentous fungal fermentation. 2005. 16th IFAC World Congress, Prague, July 4-8, 2005.