Evaluación hidráulica y propuesta de rediseño de las unidades de mezcla rápida y floculación de la planta de tratamiento de agua potable (PTAP) de Nero

Abstract

The purpose of the present work was the evaluation and redesign of the hydraulic component of the rapid mixing and flocculation units in the Nero PTAP. These units were evaluated based on the geometry and the most influential hydraulic factors such as retention time and velocity gradient. It was determined that the rapid mixing unit works adequately for flows of up to 70 l/s. However, for higher flows the hydraulic jump drowns due to the higher downstream water level, which reduces the mixing energy. This causes insufficient velocity gradients for the type of mixing implemented. In the case of the flocculation unit, it was determined that the unit has an acceptable hydraulic behavior in terms of retention times and flow. However, the velocity gradients are considerable higher than those considered for the design (50% and 33% higher in the chamber 1 and 2 respectively). This negatively affects the performance of this unit. Based on the results, it was proposed to improve the performance of the rapid mixing unit, by modifying the surface water levels and the transition between the rapid mixing unit and the flocculation unit in order to guarantee the effectiveness of the hydraulic jump. In the flocculation unit, it was proposed to reduce the velocity gradients, by reconfiguring the panels to have velocity gradient in the order of 60 and 27 s-1 which are closer to the design values, especially in chamber 2. This improves the behavior of the flocculation unit for an analyzed flow of 85 l/s.