Choice of control variable for optimization of fed-batch fermentation

Abstract The optimization problem for fed-batch fermentation is formulated in a framework which allows comparison of optimal operating policies with four different control variables. These variables include the original control variable, namely the substrate feed rate, and three transformed control variables, i.e. the substrate concentration in the fermenter, the substrate concentration in the feed and the mass flow rate of substrate. The optimality conditions for the three transformed control variables are identical but are generally different from the optimality condition for the original control variable. The optimality condition for the transformed control variables does not take into account (i) the dependence of the specific rates on the concentrations of cell mass and product and (ii) the substrate consumption dynamics. The control variable transformation leads to suboptimal operating policies for fed-batch fermentation as compared with the operating policies resulting from the original control variable. Examples are provided to demonstrate the effect of the choice of the control variable on the optimization of fed-batch fermentation.

[1]  H C Lim,et al.  Feedback optimization of fed‐batch fermentation , 1987, Biotechnology and bioengineering.

[2]  Anil Menawat,et al.  Singular optimal control strategy for a fed‐batch bioreactor: Numerical approach , 1987 .

[3]  J Hong,et al.  Optimal substrate feeding policy for a fed batch fermentation with substrate and product inhibition kinetics , 1986, Biotechnology and bioengineering.

[4]  J. E. Cuthrell,et al.  Simultaneous optimization and solution methods for batch reactor control profiles , 1989 .

[5]  Tsuneo Yamane,et al.  A Simple Optimization Technique for Fed-batch Culture : Kinetic Studies on Fed-batch Cultures (VI) , 1977 .

[6]  Tsuneo Yamane,et al.  Fed-batch techniques in microbial processes , 1984 .

[7]  W. Ramirez,et al.  Optimal production of secreted protein in fed‐batch reactors , 1988 .

[8]  T. Takamatsu,et al.  Optimal control of a semibatch fermentation , 1976, Biotechnology and bioengineering.

[9]  G Stephanopoulos,et al.  Optimization of fed‐batch penicillin fermentation: A case of singular optimal control with state constraints , 1989, Biotechnology and bioengineering.

[10]  Satish J. Parulekar,et al.  Modeling, optimization and control of semi-batch bioreactors , 1985 .

[11]  H. Lim,et al.  Computational algorithms for optimal feed rates for a class of fed‐batch fermentation: Numerical results for penicillin and cell mass production , 1986, Biotechnology and bioengineering.

[12]  W. A. Knorre,et al.  Optimal substrate profile for antibiotic fermentations , 1981 .

[13]  David DiBiasio,et al.  An experimental investigation of stability and multiplicity of steady states in a biological reactor , 1981 .

[14]  J Stanissis,et al.  An adaptive control algorithm for fed‐batch culture , 1984, Biotechnology and bioengineering.

[15]  H C Lim,et al.  Simple nonsingular control approach to fed‐batch fermentation optimization , 1989, Biotechnology and bioengineering.

[16]  H C Lim,et al.  General characteristics of optimal feed rate profiles for various fed‐batch fermentation processes , 1986, Biotechnology and bioengineering.