Análise de metodologias de estimativas de vazão de diluição para subsídio a processos de análise de outorgas de lançamento de efluentes

Abstract

Grants for sewage discharge is an important tool to control water pollution. However, in Brazil, there is no legal provision that define criteria to analyze this type of grant. Methods for estimating sewage dilution are proposed in the literature, and these support the grant process. The aim of this study is compare some of these proposed methods, considering different aspects of the watercourses. Simulations seven scenarios were performed, including the presence of other releases and abstractions of water, upstream and downstream the river, and change of framework classes. Furthermore, sensitivity analysis was performed, considering different conditions of flow incremental, natural concentrations of BOD of the river, values of the deoxygenation coefficients (K1) and sedimentation coefficients (K3). The applied methodologies were proposed by Cardoso da Silva & Monteiro (2004), Hora (2001), Nahon (2006), Roques (2006), Kelman (1997) and the Mass Balance Equation method, modified by MMA (2000). Results showed that depending of the different variables considered in equations and the values adopted the proposed methodologies can result in very different values. These results emphasize the great importance of the use of long-term monitoring techniques to more realistic analysis of grants.