Double Closed Loop Robust Optimal Control for Wastewater Treatment Process

Optimal control is commonly utilized in the wastewater treatment process (WWTP). In WWTP the effluent quality and operational cost should be optimized by solving the optimal set points of dissolved oxygen and nitrate nitrogen. However, due to the unknown disturbances of WWTP, the optimal operation objectives have strong uncertainties. Therefore, it is crucial to solve the optimization problem of the operation process, which has become the major obstacle to the optimal control of WWTP. For overcoming this obstacle, a double closed-loop robust optimal control (DCL-ROC) method is designed in this paper. First, a double-closed-loop scheme, contains a close optimization loop and a close control loop, is formulated to realize the optimal control of WWTP. Second, a closed-loop robust optimization (CL-RO) algorithm is designed to solve the optimal set points with enhanced robustness. Third, an adaptive controller based a fuzzy neural network is proposed to control the process variables with superior accuracy and robustness. The experimental results by using benchmark simulation model No.1 (BSM1) demonstrate the effectiveness of DCL-ROC.