Integrated supervisory and override control strategies for effective biological phosphorus removal and reduced operational costs in wastewater treatment processes

A novel control strategy is developed for a municipal wastewater treatment plant (WWTP) consisting of anaerobic-anoxic-aerobic reactors. The idea is to generate more organic matter with a reduction of nitrate concentration in the anoxic section so that more biological phosphorus (P) removal happens. For this, the Supervisory and Override Control Approach (SOPCA) is designed based on the benchmark simulation model (BSM1-P) and is evaluated by considering dynamic influent. In the supervisory layer, proportional integral (PI) and fuzzy controllers are designed. Additionally, dissolved oxygen (So) control loops in the aerobic reactors are designed. PI controller is designed for control of nitrate levels in the anoxic reactors and is integrated with override control and supervisory layer. It is found that the novel SOPCA approach gave better nutrient removal with slightly higher operating costs when So control is not put in place. With three So control loops in place, the WWTP showed better effluent quality and lower cost. Here, the improved removal efficiency of 28.5% and 20.5% are obtained when Fuzzy and PI control schemes respectively are used in the supervisory layer. Therefore, the application of SOPCA is recommended for a better P removal rate. [Display omitted] •A novel integrated control framework is developed to enhance biological phosphorus removal.•Seven reactor system (anaerobic-anoxic-aerobic) is used to represent the treatment process.•In the supervisory layer, PI and fuzzy controllers are designed.•Nitrate controller in the anoxic reactors is integrated with override and supervisory layer.•The proposed control approaches gave better nutrient removal and lower operational cost.