Aplicação combinada de método de otimização e modelo de qualidade de água na determinação de eficiências de sistemas de tratamento de efluentes domésticos: uma abordagem para gerenciamento de bacias hidrográficas

Abstract

The disposal of raw sewages into water bodies courses a major environmental problem. Design building and operation of wastewater treatment plants have been the most usual control effort for this problem. The selection of wastewater treatment plants become more complex when analyzed from view of watershed multiple discharges of different loads into water bodies with different self-purification capabilities. In this context, new tools and methodologies have been developed to provide adequate support to the decision-making process for selecting wastewater treatment plants systems. This work aims to combine water quality model and optimization technique -Genetics Algorithms - as an alternative methodology for the selection wastewater treatment systems. Three different optimization models were combined in order to minimize the sum of efficiencies of treatment within a watershed, maintain equity between different discharges and comply with environmental constraints. The mathematical water quality model and the Genetic Algorithm were combined in the MATLAB software computational environment. An exhaustive search algorithm was implemented to evaluate the efficiencies estimated using the Genetic Algorithm. The results indicate that the lowest sum of efficiencies was obtained from the optimization model that considerate rivers’ self-purification. The use of genetic algorithm made possible to estimate organic matter removal efficiencies very close to those estimated by the Exhaustive Search algorithm in a computer processing time substantially smaller.