Multivariable advanced nonlinear controller for bioethanol production in a non-isothermal fermentation bioreactor

Area of Science:

• Biochemical Engineering
• Process Control Systems

Background:

• Fermentation bioreactor control is complex due to nonlinear kinetics and limited online measurements for critical variables.
• Existing control strategies often struggle with dynamic set-point changes and external disturbances.

Purpose of the Study:

• To develop and evaluate a multi-input, multi-output advanced nonlinear control structure for continuous, non-isothermal bioreactors.
• To integrate a novel estimator for online biomass concentration measurement.
• To enhance bioreactor operational flexibility and performance.

Main Methods:

• Implemented feedback linearization control for bioreactor feed to regulate glucose concentration.
• Applied backstepping control for cooling jacket feed to manage reactor temperature.
• Incorporated a novel estimator for real-time biomass concentration estimation.

Main Results:

• The control structure successfully established dynamic and fixed set points for glucose and temperature.
• The system demonstrated robustness against disturbances in bioreactor feed temperature and glucose concentration.
• The novel biomass estimator provided accurate online state variable estimates.

Conclusions:

• Feedback linearization and backstepping control are effective for designing controllers for biological systems with nonlinear dynamics.
• The developed control structure enhances bioreactor operational flexibility and performance potential.
• This approach addresses challenges in controlling complex biological processes with unmeasurable variables.