Optimal Control Strategies for Wastewater Stabilization Ponds

Abstract

In this work, we address the control problem of wastewater stabilization ponds by formulating an optimal control problem considering electrical motor power for mixers and nutrient addition rate as control variables (degrees of freedom of the problem). Nitrogen and phosphorus are the added nutrients. Constraints are embedded in the DAE model and boundaries on the control variables. As the specification on biochemical oxygen demand (BOD) in the outlet stream is far from the target one, the objective is to minimize the offset between the desired value and the current one, along a time horizon of a year. As a result of the dynamic optimization problem the optimal time profiles of motor power and nutrient addition rates (phosphorus and nitrogen) are obtained for the time horizon of a year, while the BOD is kept below the required level. © 2014 Elsevier B.V.