Algorithmic Synthesis and Integrated Design for Activated Sludge Processes Using Genetic Algorithms Silvana Revollar a , Rosalba Lamanna a , Pastora Vega b a Universidad Simón Bolívar. Dpto. de Procesos y Sistemas. Caracas 1081A, Venezuela b Departamento de Informática y Automática. Universidad de Salamanca. Spain. Abstract This work presents an approach for the Synthesis and Integrated Design of an activated sludge process. The mathematical formulation translates a superstructure that contains all the design alternatives into a mixed-integer dynamical optimization problem with non-linear constraints. A real-coded genetic algorithm is proposed for the solution of such complex problem as an alternative to classical optimisation techniques. Thus, the process synthesis considering open-loop-dynamical-performance indexes and also the closed loop integrated design for the plant are carried out. The results are encouraging for future application of these techniques to solve process synthesis problems Keywords: Process synthesis, Integrated design, genetic algorithms, controllability 1. Introduction The process design aims to select the economically optimal plant configuration, together with its dimensions and stationary working point. For chemical process design, several authors (Luyben, 1993; Luyben and Floudas, 1994) have suggested the integration of controllability issues at the early stage of process design in order to improve the dynamical behaviour of the resulting plants. Based on this idea, the integrated design is addressed to the systematic study of the influence of the process design and controllability of the system, even before the process flowsheet is defined. This methodology has been actually applied for chemical processes by Luyben and Floudas (1994) and Kookos and Perkins (2001). This paper deals with the Integrated Synthesis and Design of an activated sludge process. We present the process synthesis following an optimization procedure where the constraints are posed to consider the dynamical performance of the process and the minimization of the investment and operation costs. Thus, the structure of the process is achieved, along with the set of the process variables that guarantees an acceptable dynamical behaviour for the plant. The activated sludge process synthesis has been previously performed by Gutierrez and Vega (2002a) who used Generalised Benders Decomposition Algorithm to solve the optimisation problem. The closed loop design of an alternative plant structure was also European Symposium on Computer Arded Process Engineering – 15 L. Puigjaner and A. Espuña (Editors) © 2005 Elsevier Science B.V. All rights reserved. European Symposium on Computer Aided Process Engineering – 15 L. Puigjaner and A. Espuña (Editors) © 2005 Elsevier Science B.V. All rights reserved.