Control applications in fermentation processes.

Publisher Summary The potential use of programmed and cascade control systems in fermentations has not been fully realized. Heretofore, applications of control in fermentations have measured a single variable or a function thereof and then changed this variable by some means to obtain a correction. In more sophisticated control systems, such as are coming into use in various chemical process industries, many variables are measured simultaneously, and, by means of a computer, optimum adjustments of all controlled variables can be made. Accurate control of a fermentation process also opens another wide area that has received scant attention. Obviously, in a true continuous fermentation, all variables should remain constant with time and be adjusted to some optimum value. Technique involving a statistical optimization procedure has already been developed and applied to fermentation problems. These methods, using the Box-Wilson techniques, can be applied to a large number of variables, utilizing the method of “steepest accent.” A technique has been developed for the programmed variation of dissolved oxygen level in fermentation, and a number of experiments utilizing this method have been performed. As more information is gained it might be possible to raise yields even further by simultaneous variation of, for instance, temperature, sugar concentration, pH, and dissolved oxygen content.