IBE Fernentation Control

  • R. T. J. M. van der Heijden
  • W. J. Groot
  • Ch. Hellinga
  • G. Honderd
  • K. Ch. A. M. Luyben


Immobilized Clostridia have been used for the production of a mixture of alcohols from glucose. Because the main product, butanol, causes inhibition, a pervaporation unit has been added for continuous withdrawal of butanol. For economical reasons, the glucose and the butanol concentration must be kept at given setpoints.

The dilution rate and the pervaporation temperature can be used for these control purposes. The butanol concentration is measured on-line and can therefore be used to estimate the substrate concentration. For that we used an observer.

A new method was developed to obtain suitable values for the observer parameters in order to make the estimation procedure insensitive to parameter errors in the model. For steady state operation, the resulted observer can ideally correct for many possible model errors.

Two control strategies were followed:
  1. 1)

    Two separate PI-type controllers. For substrate the dilution rate and for butanol the pervaporation temperature are used as the input signal. Attention is paid to the interaction between the two control loops.

  2. 2)

    An LQG-type controller.


The controllers are compared. As a result some criteria are indicated to make a priori choices between several control strategies. In the present case the combination of the two PI-type controllers is to be preferred because this controller does not give steady state errors and interaction between both control loops does not cause instability.


Dilution Rate Feedback Gain Steady State Error Pole Placement Linearization Point 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Society of Chemical Industry 1989

Authors and Affiliations

  • R. T. J. M. van der Heijden
    • 1
  • W. J. Groot
    • 1
  • Ch. Hellinga
    • 1
  • G. Honderd
    • 2
  • K. Ch. A. M. Luyben
    • 1
  1. 1.Department of Biochemical EngineeringDelft University of TechnologyThe Netherlands
  2. 2.The Control LaboratoryDelft University of TechnologyThe Netherlands

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