Desempenho de modelos de otimização na determinação de eficiências mínimas para remoção de DBO e compostos nitrogenados

Abstract

The selection of sanitary effluent treatment efficiencies, when analyzed within the watershed, is a complex process, since it must perform the joint analysis of multiple releases, which have different flow rates and quality characteristics in watercourses with different assimilation capacities. With the objective of establishing subsidies for the determination of minimum sewage treatment efficiencies within a watershed, using a combination of water quality model and optimization technique, this research sought to establish and apply optimization models that would allow the determination of minimum efficiencies for the removal of organic matter and nitrogen compounds. The minimization of the sum of efficiencies, the compliance with the environmental quality standards established for the watercourses and measures of equity between releases were aspects incorporated by the optimization models developed. The proposed models were applied to the Pardo River basin, a tributary of the Itapemirim River, which is the most important watercourse in the southern region of the state of Espírito Santo. The results indicated that the optimization models that employed objective function equity measures produced similar results and invariably suggested greater treatment effort than that indicated by a model whose objective function exclusively sought to minimize treatment efficiencies. The evaluation of Lorenz Curves and the appropriate values for the Gini Coefficient led to the conclusion that the models that incorporated equity measures in the objective function presented satisfactory performance regarding the distribution of the treatment effort within the watershed.