Enhancing the Performance of a Simulated WWTP: Comparative Analysis of Control Strategies for the BSM2 Model

This study aimed to improve the performance of a wastewater treatment plant (WWTP) simulated with Benchmark Model No. 2 (BSM2). To achieve this objective, three control strategies were implemented and tested. The first control strategy aimed to maintain the concentration of nitrate and nitrite nitrogen (S NO ) by controlling the external carbon flowrate (strategy A 1 ), and the second control strategy aimed to maintain the ammonia and ammonium nitrogen (S NH ) at a desired level with the use of a cascade controller (strategy A 2 ). The third strategy was applied to control the total suspended solids (TSS) (strategy A 3 ). Combinations of these strategies were considered (B 1 , B 2 , and B 3 strategies), as well as the use of all three together (strategy C 1 ). The control strategies presented in this paper were compared to the default control strategy of BSM2 to validate and identify the one that provided the best performance. The results revealed that the B 1 strategy was the most environmentally friendly, while C 1 obtained the highest overall performance. Several Monte Carlo simulations were performed for the validated control strategies, to identify the optimal setpoint values. For the C 1 strategy, a second method of optimization regarding polynomial interpolation was considered. The applied optimization methods provided the optimal reference values for the PI (proportional integral) controllers.