Characterization of flow lines generated by pressurized sand filter underdrains

Abstract

The physical particles filtration, inorganic and organic, is an important action in the irrigation water treatment, preventing emitters clogging, the main operational problem in localized irrigation. Sand filters have better particles removal than screen and discs filters. These equipments have two operation fundamental processes, filtration and backwashing. During these processes the streamlines homogeneity and profile are fundamental parameters to obtain the effectiveness and efficiency of the retention and detachment of impurities, respectively, filtration and backwashing. The purpose of this study was to identify the profile and homogeneity of distribution of fluxes lines and characterizing the trend of flow during the filtration and backwash processes, for different underdrains types (nozzle) used in pressurized sand filters. A Computational Fluid Dynamics (CFD) model was developed further to simulate and analyze the hydrodynamic of the flow in the virtual module configured with three nozzle models, one cylindrical and other conical type, commercially available, and other modified of the conical type, named as "cuca". The results have shown that the commercial models, (cylindrical and conical), provides uneven distribution flow lines and it was observed flux stagnation points, ie., there was no uniform fluid distribution in area of the actuation of the accessory, in flow directions ascending and descending. It phenomenon wasn't identified for optimized drain (cuca). The modified drain presented greater distribution homogeneity of the flow lines and, consequently, the potential to maximize the removal and detachment efficiency of inorganic and organic particles.