A study of the model of the multiobjective fuzzy process control on citric acid fermentation

In order to obtain the highest concentration of citric acid in the fermentation, a model of the multiobjective fuzzy process control is put forward. Also a series of rules determining the values of the control variables in this model, based on the records of citric acid fermentation, mathematical models from biotechnology scientists and experience of the engineers of the fermentation control, is set up and refined stepwise. To examine this model and these rules, experiments were conducted on a 1.5 m³ fermenter. The results show that the citric acid concentration reaches 10.39% with the initial glucose concentration 11.30%, in comparison with the citric acid concentration 11.4% with the initial glucose concentration 14.2% in normal control on a 100 m³ fermenter. The fermentation time is shortened from 70 hours (normal control) to 63 hours. The residual glucose concentration hits the lowest level 1.36%