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Optimizing Outfall System Configurations Using Decision Support and Numerical Models. Case Study of Santa Catarina Island, Brazil

Author(s): A. V. Falkenberg; R. C. Barletta; L. Franklin; P. Ribeiro; P. G. De Lara; T. Bleninger; A. B. Trevisan; V. Dos Santos

Linked Author(s): Tobias Bleninger

Keywords: Outfall system; Topsis; Hydrodynamic and water quality modeling

Abstract: This paper presents the methodology used to define the optimal design for the outfall system to be implemented in the northern part of Santa Catarina Island, south of Brazil. Among several relevant factors there were considered the current sanitation infra-structure, population growth estimation, social aspects, cost analysis and potential environmental impacts. In order to evaluate the different feasible alternatives, the TOPSIS methodology was used, which represents a multi-criteria decision making approach based on similarity to an ideal solution. There were evaluated 42 possible alternatives varying several criteria, such as geographic location, effluent discharge, treatment levels, construction and operating costs and environmental and social aspects. Subsequently, a numerical modeling phase was started implementing a 3D hydrodynamic model (Delft3D-FLOW) which was calibrated and validated for a one year period using measured oceanographic data. Afterwards, a near -field model (CORMIX) was used to evaluate the dilution performance for each location and to set up the input concentration data for the far field water quality model (Delft3D-WAQ) to analyze the dispersion of nutrients, BOD and bacteria in order to ascertain the performance of each alternative with the environmental legal requirements. The results show that even though initially there were dozens of potential alternatives, decision support methodologies and models exist to provide guidance to decision makers, as well as sanitation and environmental agencies, and stakeholders to find optimal solutions


Year: 2016

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