Abstract
Concentrations of the dissolved oxygen (DO) and nitrate nitrogen (NN) directly affect the effluent quality. Keeping those concentrations in a desired level is crucial in a wastewater treatment process. However, numerous undesirable factors as well as couplings between DO and NN challenge keeping both DO and NN in a desired level. To achieve satisfactory performance, rather than model those issues accurately, but view them to be disturbances, a disturbance rejection control (DRC) is designed. By estimating and cancelling out those disturbances in real-time, couplings can be addressed effectively, and robustness of the closed-loop system is also promoted. Numerical results based on the benchmark simulation model no. 1 (BSM1) shows that the DRC is able to reject the disturbances and meet the control requirements satisfactorily. It may be a practical and feasible wastewater treatment process control approach.