An improved dissolved oxygen concentration fuzzy controller in wastewater treatment

The paper focuses on developing a dissolved oxygen concentration controller based on a fuzzy model for activated sludge wastewater treatment processes. To achieve accurate aeration in the sewage treatment plant and improve its robustness, a new cascade fuzzy control system is introduced in the paper. The control system contains double fuzzy controllers which can separately be responsible for the aeration rate during the air supply and air shut-off processes. The discrete dissolved oxygen concentration model is derived and the effect of the influent load on the aeration demand is also considered in the fuzzy controllers. The method was validated on the benchmark simulation model, no 1 (BSM1) simulation platform and comparisons with some related methods are presented. The system has been put into use in some sewage plants and its steady-state control accuracy can be within 0.3 mg/L. It can maintain good dynamic response even when the influent has many changes.