Dissolved oxygen control strategy comparison for an activated sludge process

There are increasingly important financial incentives and environmental considerations for improving the treatment of wastewater from domestic and industrial users before being released into the environment. Insufficient levels of dissolved oxygen prevent the successful degradation of organic matter present, whereas too high a level causes settling problems, in addition to the waste of energy and hence cost efficiency. Therefore, the need for controlling dissolved oxygen is of great importance. The paper presents simulation results providing comparison of controller performances for three control methods (PID, fuzzy logic and self-tuning control) for a wastewater process with typical influent flow pattern. The set-point to the sludge flow control system is optimised using an objective function including released water quality and financial running cost