Robust PID control for a wastewater treatment based on genetic algorithm and small-gain approach

This paper presents robust PID (proportional integral derivative) controller tuning using genetic algorithm and small-gain approach for wastewater treatment. In operational terms, the main control objective is to maintain the concentration of the biomass directly proportional to the influent flow rate with the various disturbance compensation, noisy measurements and varying process model parameters. The robust PID control design is based on a simplified Activated Sludge Model No. 1 (ASM 1) with the description of the nonlinearities by bounded structured uncertainty. The genetic algorithm is used to optimize the PID parameters based on the underlying problems constrained by the small-gain theorem and H∞ specifications without resolving complex mathematical calculations. The simulation shows that the optimization result of PID parameters having the ability to overcome the systems uncertainty.