On Introducing a Dummy State Variable in Modelling Biochemical Reaction Processes

Abstract

In this paper, it will be shown that the introduction of a dummy state variable which cannot be directly measured can extremely imporve the conventional model. A dummy state variable is introduces based on the concepts of two different kinds of “activity” of mocroorganisms. One of them means a saturation ability of microorganism for the substrate, and the other means the adaptability of microorganism for the changes of environmental conditions. These two characteristics of activity may be essentially held in all biochemical reaction processes, but the activity of saturation is emphasized in a activated sludge process and the adaptability is emphasized in a fermentation process. The value of activity cannot be directly measured such as concentration of chemical species. However, it should be emphasized that the model structure introducing a dummy state variable of activity can give reasonable results for design and coutrol of biochemical processes.