Feedback regulation of an industrial aerobic wastewater plant

The main task of this work is related with the design of a class of SISO robust control law for the regulation of substrate concentration measured as chemical demand of oxygen (CDO) of an industrial activated sludge wastewater plant. The control design is related with an uncertainty estimator (reduced order observer)-based active control. Departing from the dynamic error between the desired and the current substrate concentration trajectories a control law is designed and the plant is regulated to the corresponding set point of the COD concentration. To be realizable the controller needs model information related with the kinetic term of COD (substrate) consumption which is provided with a reduced order observer, this coupled structure (observer-based controller) is robust against model uncertainties. The performance of the proposed control law is illustrated with numerical simulations employing a mathematical model of an industrial activated sludge wastewater plant tuned with industrial data.