Combined $\mathcal{L}_2$ -Stable Feedback and Feedforward Aeration Control in a Wastewater Treatment Plant.

A nitrifying activated sludge process with ammonium feedback and inflow feedforward control is studied. The feedback and feedforward measurements are subject to time delay and the control loop includes a saturation. A Hammerstein-based model is therefore identified, including process delays and the nonlinearity. A Monod-type nonlinearity is used, as motivated by the oxygen injection efficiency red...