Dynamic multi-objective optimization and multi-units linear active disturbance rejection control for wastewater treatment processes

Abstract

Wastewater treatment processes (WWTPs) are complex nonlinear systems with strong nonlinearity among many treatment units and disturbances including weather conditions, uncertainties, and time-varying dynamics. This paper studies the multi-objective and multi-units linear active disturbance rejection control for WWTPs to lower the overall cost index and enhance the effluent quality index simultaneously. A multi-objective optimization method using the multi-strategy mutation and the adaptive mechanism is employed to dynamically optimize set points. Then, multiple-units linear active disturbance rejection controllers are designed to achieve tracking control for dissolved oxygen concentration (including 3-5 units) and nitrate level with unmeasurable disturbances based on the optimal set points. The comparison experiments tested on the benchmark simulation model No. 1 demonstrate that the proposed method can improve the tracking performance and achieve a significant improvement in reducing the overall cost index and the effluent quality index.