The pH control is essential for many fields of chemical and biotechnology. Examples include fermentation processes that require controlled pH to a specific extent under optimum conditions, water absorption, coagulation of metals, and algal growth in biomass production. The main problems of pH control are three major: process nonlinearity, high sensitivity near the equilibrium point, and time-varying behavior of input concentration changes with changing process behavior.
Since the pH control plant is a nonlinear control plant in nature, modeling becomes important. In this regard, many studies have discussed the general nature of pH and what factors are non-linearities, and the problems of pH control, mathematical modeling of pH control plant, and various control design approaches for pH control have been discussed. It is clear that all pH control systems have difficulties, and it is important to make the operation of simple linear controllers well-suited.
In our research group, we have performed simulations on the analytical model of the proposed pH control plant based on process parameters, verified the validity of the model, proposed a nonlinear controller design by means of input-output linearization approach, and verified the effectiveness of the designed controller through numerical simulation and experiments.
The results of this study were published in "Theoretical Foundations of Chemical Engineering" (2023) under the title of "pH Control of Yeast Fed-Batch Fermentation Process by Improved Input-Output Linearization Method"(https://doi.org/10.1134/S0040579523060088).
