Optimization Techniques for Secondary Wastewater Treatment System

Abstract

Optimization approaches are shown to be effective in solving a comprehensive model of an activated sludge wastewater treatment system. A new decomposition approach tailored to take advantage of the special structure of the treatment system is presented. A liquid subsystem and a sludge subsystem are specified, and a series of subproblems is solved. Coordination of the solutions is then required. A widely used nonlinear programming algorithm (GRG2) and a geometric programming algorithm (IGGP) designed to handle equality constraints are also demonstrated. Each of the approaches is shown to produce efficient solutions for a test problem; computational requirements are similar. The first approach most clearly illustrates cost‐effective trends and alternative solutions, while the third is most straightforward. The availability of the different approaches is important because one may be more suitable than the others for a particular application—especially if the model has been modified or extended.