Non-singular optimal control for fed-batch fermentation processes with a differential-algebraic system model

• Published in: Journal of process control 1993, Vol.3 (4), p.211-218
• Main Authors: Fu, P.-C., Barford, J.P.
• Format: Article
• Language: English
• Subjects: differential-algebraic system; ethanol formation; fed-batch fermentation
• ISSN: 0959-1524; 1873-2771
• DOI: 10.1016/0959-1524(93)80026-8

The problem of optimal control for fed-batch fermentation processes is studied with nonlinear differential-algebraic system modelling. A non-singular optimal control strategy has been developed as a result of the necessary condition analysis of non-singularity of the Hamiltonian function established for the processes. Proof of the optimality of the proposed feeding policy is given. The difficulty associated with singularity of the fed-batch operation mode can thus be avoided. The ethanol fermentation process from glucose by S. cerevisiae is taken as an example for the optimization application. It has been found that previous investigations by some authors, with different optimization methods, led to overestimation of the product formation from the process. A constraint is thus put on the specific productivity, which if unconstrained is responsible for the existing inaccurate predictions. This constraint takes into account the stoichiometry involved in the fermentation. Our simulation study has shown that a realistic result can be achieved with the proposed non-singular optimization scheme.