Control of the Biodegradation of Mixed Wastes in a Continuous Bioreactor by a Type-2 Fuzzy Logic Controller

The paper describes the application of type-2 fuzzy logic control to a nonlinear system with bifurcations. A type-2 fuzzy logic controller is tested by simulation on a bioreactor with cell recycle that presents bifurcations. The process involves a pure culture of Pseudomonas putida containing phenol and glucose as carbon and energy sources and is characterized by two saddle-node bifurcations. Because of the bifurcational behaviour the system may become unstable also for further variation of process parameters. The simulation results show the validity of the proposed controller, that, compared with other controllers, has a higher performance in terms of robustness and response speed