Deoxygenation rate, reaeration and potential for self-purification of small tropical urban stream

Joao Paulo Cunha de Menezes, Ricardo Parreira Bittencourt, Matheus De Sá Farias, Italoema Pinheiro Bello, Luiz Fernando Coutinho de Oliveira, Ronaldo Fia

Abstract


The mathematical models used to simulate the water quality and the processes of self-purification of water bodies are important tools to support management of water resources. The objective of this study was to evaluate the impact of organic pollution on water quality and the assimilative capacity of organic matter in the stream called Ribeirão Vermelho, in Lavras city, MG. For this purpose, it was determined and tested the deoxygenation rate (K1) and reaeration (K2), in three parts the Ribeirão Vermelho stream and in two different periods (summer and winter). The largest K1 and K2 values were obtained during the winter period, when the lower flows and the simulation of self-purification process was performed using the Streeter-Phelps model. The simulation of DO profile presented in summer and BOD acceptable calibration, in order to optimize the weightings, showed the prevalence of carbonaceous deoxygenation due to nitrification and demonstrated the importance of natural reaeration the depuration process. Different behavior was observed during the winter, in which the high primary productivity values stood in reaeration process stream. Just biochemical oxygen demand did not respect the limits recommended by the Resolution of the Ministry of the Environment 357/2005, having stayed at the entire length of the river and in both periods, out of regulation. Thus, it is concluded that the Ribeirão Vermelho unable autodepurar along its length, and the quality of its waters influenced by effluent discharges which intensifies the river degradation process.

Keywords


effluent release, Streeter Phelps models, water quality.



Revista Ambiente & Água. ISSN:1980-993X DOI:10.4136/1980-993X


Editoração:Apoio:Filiada à ABEC:
IPABHi CAPES CNPq ABEC