No abstract

Este artículo contiene el análisis comparativo realizado entre dos plantas de tratamiento de agua potable (PTAP), una que abastece de agua a una parte de Bogotá, Colombia y otra en Boston, Estado Unidos de América (EE. UU.). El análisis se enfoca en tres aspectos: el tratamiento implementado en el agua que ingresa a las PTAP, el desinfectante utilizado en las plantas y el modelo administrativo utilizado en cada país. De acuerdo con estudios desarrollados en la Carroll Water Treatment Plant  CWTP), al implementar el sistema de desinfección por ozonización se obtienen cambios notables y considerables en las características del agua, su sabor y color, un aumento en la inactivación de patógenos, así como una dramática reducción en los subproductos de la desinfección. Por otra parte, contar con varias entidades que intervengan en la administración financiera del recurso hídrico proporciona un mejor control y vigilancia de este, como en EE. UU. Asimismo, la prevención de la contaminación del agua parece una directiva de manejo más sabia y prudente que la limpieza de nuestras fuentes de agua en el futuro.

Computational fluid dynamics is a tool that allows to simulate and observe the behavior of any fluid, based on a physical, hydraulic, and hydrodynamic analysis. This research analyses the behavior of the flow in a sand trap, which is a structure used to remove sand particles with a minimum size of 0.10 mm, prior to treatment in a drinking-water plant. The objective of this study is to determine the highest efficiency between two sand traps, one with a double smooth screen and the other with a double perforated screen (with diffusers), based on the simulation and analysis behavior of the flow inside each sand trap. The methodology used includes the traditional design of each unit based on Hazen’s model and Stokes viscosity law, to later carry out the numerical model simulation from Ansys Fluent (pre-processing, processing, and post-processing). The result shows that perforated double screen sand trap generates a removal efficiency of 78%, while the smooth double screen 28%. In addition, other four units of interleaved screens are proposed, in these cases efficiencies of up to 50% are observed and it is shown that it is necessary to implement at least two perforated screens (with diffusers) to guarantee an efficiency greater than 70%. Hydraulic simulation has a broad impact on infrastructure works and consulting.

This study proposes a methodology for the calibration of combined sewer overflow (CSO), incorporating the results of the three-dimensional ANSYS CFX model in the SWMM one-dimensional model. The procedure consists of constructing calibration curves in ANSYS CFX that relate the input flow to the CSO with the overflow, to then incorporate them into the SWMM model. The results obtained show that the behavior of the flow over the crest of the overflow weir varies in space and time. Therefore, the flow of entry to the CSO and the flow of excesses maintain a non-linear relationship, contrary to the results obtained in the one-dimensional model. However, the uncertainty associated with the idealization of flow methodologies in one dimension is reduced under the SWMM model with kinematic wave conditions and simulating CSO from curves obtained in ANSYS CFX. The result obtained facilitates the calibration of combined sewer networks for permanent or non-permanent flow conditions, by means of the construction of curves in a three-dimensional model, especially when the information collected in situ is limited.

In this study, the degree of goodness of fit presented by the San model is determined to calculate the percentage of removal of flocculent particles, when the initial turbidity in the problem water is low. For this, the frequency analysis of the historical turbidity data that enters four drinking water treatment plants located in the department of Cundinamarca (Colombia) is made, which show values that range between 0.60 and 15.08 NTU (Nephelometric Turbidity Units). The water coagulation was done using type A aluminum sulfate and the sedimentation test was carried out in a sedimentation tower in order to determine the remaining turbidity in the water, which allows calculating the percentage of removal for different sedimentation times and at different depths. The values of the constants of the San model were determined through a multiple linear regression and the goodness of fit test was performed by calculating the coefficient of determination R2 for the different initial turbidity values in the test water.