Sewage estimation and self depuration modeling of domestic effluents released in the Rio Doce in the municipality of Baixo Guandu, ES

Abstract

The urbanization and industrialization expansion, Industrial Revolution consequences, have gradually increased pressures on water resources. The domestic sewage of Baixo Guandu municipality is thrown directly into the river without any previous treatment. This work aims to estimate the amount of sewage released in the river and to evaluate the autodepuration process after the effluent is released. In order to carry out this work, a data survey was performed in the Autonomous Water and Sewage Service (SAAE) of the municipality’s water consumption between 2010 and 2015 and mathematical models cited in the literature. Researchers Streeter and Phelps, in 1925, established the mathematical bases of the oxygen curve dissolved in a watercourse. The structure of the model proposed by them is classic within Environmental Engineering, serving as support for all the other more sophisticated models that have succeeded. It was noted that the OD concentration depletion and the BOD increase after the domestic effluent discharge is not so significant, because the river has sufficient flow to dilute the sewage in it. Despite the intense discharge of effluents released “in natura” in the Rio Doce, it still presents a good quality in its waters based on OD and BOD values. Through the model of Streeter and Phelps, it was verified that there is not a significant environmental impact in the Doce River caused by the release of organic matter coming from Baixo Guandu domestic effluents in relation to the dissolved oxygen.