Abstract
To improve the efficiency of removal of suspended solids at rapid filters, we designed improved structure of the device. The improvement is based on the application, simultaneously with a granular filter layer, of vertical drainage elements with porous fibrous shells. Such a solution makes it possible to shift part of the load to the shells of drainage elements, reduce colmatation and head losses in a granular filter layer, as well as to more evenly distribute contaminants along its height. This increases the duration of operation of the filter under filtering mode and brings down the cost of regeneration of a filter layer. A filtration equation was derived to describe parallel filtration of a low-concentrated suspension through a granular medium and a fibrous medium. The mathematical model also includes equations of mass transfer, mass exchange and dependences to account for the impact of colmatation and parameters of filtering media. For a granular filter layer, we considered filtering with a gradual blocking of pores; for a porous shell ‒ the formation of a sediment layer at its surface. Using a mathematical model, we conducted numerical experiments. The following significant parameters for the filter with improved design were determined: equivalent diameter of particles in a filter layer, working height of the vertical drainage element, duration of washing a porous fibrous shell. We give examples of calculations for determining the values of basic parameters at which the effectiveness of application of vertical drainage elements is maximal
Highlights
In the preparation of drinking water from surface sources, an important stage of treatment is filtering through a granular filter layer
With respect to the assumptions accepted, a mathematical model of the process of parallel filtering of a low-concentrated suspension through a granular filter layer and porous fibrous shells (PFS) vertical drainage elements (VDE) is based on the following equations and dependences
Using the mathematical model constructed, we studied the effectiveness of application of the filtering structure with VDE
Summary
In the preparation of drinking water from surface sources, an important stage of treatment is filtering through a granular filter layer. Such a technique of purification, in combination with coagulation, enables effective removal of finely dispersed suspended particles. Additional facilities and equipment are required to treat and pump the water used for the regeneration of rapid filters. Especially in Ukraine, the cost of services to provide drinking water has been continuously increasing This is due to inflation, increased prices for electricity, the need to employ expensive imported reagents, and other factors. It is an important task to explore ways to solve a given problem
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