Obtaining effluent dilution flow using the QUAL-UFMG water quality model

Abstract

The supervised model of socioeconomic development, associated with accelerated population growth and the need to attend to various human activities evidenced in a complex panorama of pollution in water bodies, which directly affects the dilution capacity and self-purification of rivers. The implementation of decision support systems and water quality models is essential for efficient water management and articulation of the National Water Resources Policy instruments. Thus, the main objective of this work is to analyze the dilution capacity using the QUAL-UFMG water quality model in a case study in the Piracicaba River. For this, the model was adjusted and calibrated using hydrological and water quality data from fluviometric stations. From the results of the modeling it was possible to make a diagnosis of the basin and after the application of the model it was found that it was able to represent well the reality of the river studied. The hypothetical simulation considering the installation of domestic effluent treatment systems for some discharges directly into the Piracicaba River showed a 36.96% decrease in biochemical oxygen demand concentration. The change in the framing classes resulted in variations of up to 79.83% in the dilution flows. The framing class has a significant influence on the dilution flows, with an increase in the consonant values for level and restriction, that is, each time the permitted biochemical oxygen demand concentration in the water body decreases, the dilution flow increases. It is interesting to note that according to the calculated dilution flow conditions, the consideration of previous releases is of extreme importance for the determination of available and unavailable flows and consequent water availability.