Description
This paper describes the optimization af an activated sludge system wich comprises an aeration tank and a secondary settler. This system is by far the most widely used biological process in wastewater treatment plants. The optimization process is represented as a smooth nonlinear problem with highly nonlinear equality constraints, some linear equality constraints, one inequality constraint and simple bounds, in which the objective is to minimize the total cost associated with the installation and operation of the biological process. We use the software LOQO to solve the problem. Several computational results show that the quality of the effluent, especially in terms of carbonaceous matter, influences directly the cost and the main contribution to the total cost is the air flow, due to the acquirement of the electromechanical equipment and spent energy.
; Fernandes, Edite Manuela da G. P. 
