Fuzzy control of dissolved oxygen concentration in a bioreactor for wastewater applications

A fuzzy controller for the dissolved oxygen (DO) concentration of a wastewater bioreactor is presented. The controller is developed and tested based on simulations using first order plus dead time models obtained from experiments with an actual wastewater bioreactor. The controller uses feedback of the error in DO concentration and rate of change of the DO concentration and manipulates the valve position of the flow control valves supplying air to the bioreactor cells. The proposed controller has been tested for robustness across several process models including models incorporating proposed worst-case conditions. The performance of the controller is compared to traditional PID control and it shows several enhancements.