MIMO quantitative robust control of a wastewater treatment plant for biological removal of nitrogen and phosphorus

This paper applies a recent full-matrix multi-input-multi-output QFT controller design methodology to simultaneously regulate nitrogen and phosphorus concentrations in the effluent of a wastewater treatment plant (WWTP) according to environmental standard policies. The robust controller is based on two terms: a non-diagonal pre-compensator for decoupling and a diagonal controller for robust performance and stability. Simulation results show the benefits of the control strategy for WWTP-type complex processes with large channel-interaction and uncertainty.