Desenvolvimento de software para análise de autodepuração em rios

Abstract

Sewage releases are some of the main pollutant loads in rivers, which spoils water for human consumption as well as destabilize and harm the water body ecosystem. In this context, self-depuration is important in the study of sewage discharges into rivers, as well as in the proper efficiency designing of sewage treatment stations and posterior effluent discharges into rivers. However, the study of self-purification includes several water quality parameters as well as many physical, chemical and biological river data, which make the solution extensive and difficult to solve by hand. Therefore, the use of computational tools becomes essential for efficient and accurate analysis of selfdepuration. In order to facilitate the academic study of self-purification as well as to make the calculation routine faster, a free computerized system in Visual Basic, named QAR-UTFPR, based on the Streeter & Phelps model was developed. The software calculates the biochemical oxygen demand (BOD), dissolved oxygen (DO) and coliforms through the input data of the river, effluent, treatment efficiency, temperature, and kinetic coefficients established by the model (decomposition reaeration, among others). The software is valid only for river stretches where there is only one continuous sewage load point, with or without previous treatment. The parameters are calculated point by point with a step distance defined by the user. Thus, through these points, the software generates the river profile graphics for each of the parameters. For DOB and DO, the software also plots the profile graphics with the treatment efficiency defined by the user. In addition, the user can define the minimum acceptable level of DO to be plotted on the graphic. Since it is a free software with academic purposes, the goal was to establish a clear and intuitive interface, moreover there is extra information for beginners about the input data. The software was tested by an example in the literature and the results were basically the same. Thus, it is concluded that the developed software can serve as an important tool for studies about river self-depuration.