AN EXPERT SYSTEM APPLIED TO THE CONTROL OF AN INDUSTRIAL-SCALE BIOREACTOR

Control of a fed-batch industrial-scale fermenter requires a large amo unt of ''finger-tip feeling'' on the part of operators, despite reason ably sophisticated instrumentation. The reason for this is that there are no applicable deterministic models giving aid to the control syste m in deciding the best operation strategies. This is a typical case of a heuristic experimental process, treating inexact knowledge that is excluded from deterministic and statistic modelling a priori. Essentia l parts of this problem can be solved by means of an expert system she ll, capable of dealing with uncertain information, using the linguisti c shell application. Knowledge was extracted from process records on f ermentation batches producing baker's yeast on an industrial scale. A strategy for heuristically optimized yield and growth rate can be pred icted using knowledge gained in previous runs and stored in the knowle dge base of the expert system. The expert system, once built up, can a lso be used for experimental simulation of the effects of fundamental decision parameters: temperature, production rate, ethanol concentrati on and specific growth rate. The use of expert system consultations ca n be generally recommended as an efficient aid in fermentation control .