Integrated design of wastewater treatment processes using model predictive control

In this work the Integrated Design of the activated sludge process in a wastewater treatment plant has been performed, including a linear multivariable predictive controller with constraints. In the Integrated Design procedure, the process parameters are obtained simultaneously with the parameters of the control system by solving a multiobjective constrained non-linear optimization problem, taking into account investment and operating costs. Performance indexes for optimal automatic MPC tuning are the ISE norm, the H_∞ norm of the closed loop disturbances transfer function, and the ∞ norm of the error signal. The mathematical optimization for tuning all parameters is tackled in two iterative steps. First a sequential quadratic programming (SQP) method is used to obtain plant parameters, and secondly, a special type of random search method is used to tune the controller parameters.