Optimized Control Structure for a Wastewater Treatment Benchmark

In this paper, we define and implement the design of an optimized control structure for the activated sludge process given as COST/IWA benchmark simulation model No.1. Emphasis is given to the identification of controlled variables that contribute to minimize economic costs while the effluent requirements are met. This is achieved considering the selfoptimizing procedure as reference method for the controlled variables selection. The proposed optimal control strategy consists of multivariable PID loops which manipulate the airflow rate in the aerobic basins, the nitrate and sludge recirculation flows and the waste sludge flow proportionally to the influent flow such that the overall cost function is minimized. Dynamic simulations validate the resulting optimized controller structure, showing that minimal costs can be achieved.