RU2697350C1 - Two-component filter material - Google Patents

Abstract

FIELD: filtration.

SUBSTANCE: invention relates to filtering materials and is intended for use in all industries, where water filtration processes are used: purification of drinking water, treatment of water pools and water parks, post-treatment of sewage water, water treatment in food industry and other industries where purified water is used in technological processes. Two-component filtering material contains two fine-grained materials used in the water treatment technology, having the same granulometric composition and different bulk density differing by 15–25 %.

EFFECT: technical result of this invention is to increase efficiency of water treatment measures by obtaining two successive steps of fine-grained filtration.

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Description

The invention relates to filtering materials and is intended for use in all industries where water filtering processes are used: drinking water treatment, water treatment for pools and water parks, post-treatment of sewage, water treatment in the food industry and other industries where purified water is used in technological processes.

Filtration is the process of passing clarified water through a layer of filter material. Filtering is used to clarify water, that is, to detain suspended solids in water. The filter material should be a porous medium with very small pores. In conventional filters, water is supplied from above and discharged from below through a drainage device, and the filter is flushed with a reverse water flow.

When washing the most commonly used industrial filters with coarse and fine grains of filter material, the following processes occur. Rising currents of wash water agitate the filter material, and its volume increases; this increase in volume is called the filter load extension. In the upward flow of water, small and light grains of the filter load are higher than larger and heavier ones. After stopping the washing process, the filter material settles. Moreover, larger particles settle faster, while smaller ones, on the contrary, slower. Thus, the particles of the filter load are sorted into fractions. The finest fractions accumulate in the upper part of the filter charge. And since water is fed from top to bottom for filtration, the largest particles of pollution get into the fine-grained fraction, respectively, and are retained on it. Those finely dispersed contaminants that managed to penetrate through the fine-grained upper layer no longer linger in the lower coarse-grained loading layers and pass freely through them.

After washing the filter, water, filtered from top to bottom, deposits deposits mainly in the upper most fine-grained layer of the filter charge. As a result, the dirt capacity of the rest of the filter material remains unused. Under these conditions, its upper layers are quickly contaminated, pressure losses increase rapidly, as a result of which the useful life between the filter washes is insignificant (Abramov N.N. WATER SUPPLY. Textbook for high schools. - 3rd edition, revised and enlarged - Moscow, Stroyizdat, 1982, Paragraph 101, p. 277).

Thus, in order to remove from the treated water those contaminants that passed through the filters of the first stage of filtration, in some cases it is necessary to install additional filters of the second stage, which indicates the low efficiency of such filters and significantly increases the capital cost of the water treatment system.

To partially solve this problem, filters are sometimes used loaded with filter materials of different bulk density and different grain sizes.

Bulk weight (bulk bulk density) is the mass of bulk material per unit volume along with voids. The bulk density is expressed in kilograms per cubic meter (kg / m ³ ).

For example, two-layer filter media filters are known comprising an upper layer of coarse-grained crushed anthracite and a lower layer of fine-grained silica sand. In this case, a two-layer loading is located on a layer of coarse-grained heavy gravel that acts as a support layer for the filtering load (RF patent No. 64929, published July 27, 2007, RF patent No. 75160, published July 27, 2008).

Crushed anthracite and quartz sand are materials used in water treatment technology. Anthracite is a type of coal, quartz sand is a material consisting mainly of silicon dioxide. When water is supplied from top to bottom during filtration, large particles of impurities are retained by a layer of anthracite, and smaller ones by a layer of sand. Anthracite has a lower bulk density than quartz sand, therefore, after washing the filter with a reverse current of water, sand settles faster than anthracite. As a result, the arrangement of the layers remains the same, and the filter after washing is ready for a new cleaning cycle. However, even in this two-layer filter load, we have only one layer of fine-grained quartz sand, located immediately below the layer of crushed anthracite, while the dirt capacity of the rest of the sand remains unused. Thus, the anthracite layer and the upper sand layer quickly become clogged, which leads to the need for frequent washing of the filter, interruptions in its operation, which generally reduces the effectiveness of water treatment measures.

The inconvenience when using the filtering media considered here lies in the fact that various filtering materials (crushed anthracite, silica sand) are delivered in different packaging containers and then layer by layer are loaded into the filter, observing the required layer height and other parameters. In addition, various filter media most often have to be purchased from different suppliers, which further complicates the processes.

Also known from the prior art is a two-component filter material that is taken as the closest analogue to the claimed filter material and contains a layer of glass particles and a layer of silica sand, while the glass particles have a negative charge to ensure bactericidal properties and delay contamination, and the two-layer material is located on a layer of coarse-grained heavy gravel that acts as a support layer for the filter media (China Patent No. 203954764, published November 26, 2014).

Crushed glass and sand are also materials consisting mainly of silicon dioxide, while the bulk density of the glass is less than the bulk density of sand. However, this solution does not disclose the particle size of glass particles and silica sand and other indicators of particle size distribution, which allow us to judge the effectiveness of the filtering properties of such a material. In any case, both crushed glass and quartz sand are delivered in different packaging containers and, as a rule, by different suppliers. This, as in the previous case, creates certain inconveniences both when delivering filter materials from different places, and when they are layer-by-layer loaded into the filter.

The objective of the invention is to manufacture in a production environment a two-component filter material (DFM), followed by packaging it in a single container in which it enters the final consumer for subsequent use as a filter load.

The technical result of this invention is to increase the efficiency of water purification measures by obtaining two successive stages of fine-grained filtration.

The technical result is achieved when using a two-component filtering material (DFM) for water filtration, containing two fine-grained materials used in water treatment technology, having the same particle size distribution and different bulk density, differing by 15-25%.

In this case, DFM is manufactured under production conditions by mixing two fine-grained materials (for example, silica sand and silicate glass), followed by packing the resulting two-component filter material in a common container. In this container, it remains unchanged for the final consumer, who loads it into filters for water purification by simple filling.

The granulometric composition of the filtering material implies such indicators as (SP 31.13330.2012 "Code of practice. Water supply. External networks and structures"):

- minimum and maximum grain diameter;

- coefficient of heterogeneity;

- equivalent grain diameter.

These characteristics must meet the requirements of the relevant regulatory documents (SP 31.13330.2012, DIN 12904: 2005, etc.).

The same particle size distribution means that the DFM contains two fine-grained materials having the same characteristics, that is, within the limits according to the standards, such as: minimum and maximum grain size in diameter, heterogeneity coefficient, equivalent grain diameter.

DFM can be made by mixing natural quartz sand and crushed silicate glass. The main component of these materials is silicon dioxide. Due to the lower content of silicon dioxide, the bulk density of crushed silicate glass is 15–25% less than the bulk density of quartz sand of the same particle size distribution.

The granular filter material indicators characterizing the grain size and their uniformity are determined by the results of a sieve analysis, which consists in sieving the dried sample sample on calibrated sieves with determining the mass of the granular material remaining on each sieve. Based on the data obtained, a sieve analysis graph is constructed, according to which the heterogeneity coefficient and the equivalent grain diameter are determined. Formulas for calculating particle size distribution are standard (https://studme.org/80703/geograflya/opredelenie_granulometricheskogo_sostava_dispersnyh_gr untov, viewed June 25, 2019, https://vunivere.ru/work16629, reviewed June 25, 2019 and others) .

After manufacturing, the DFM is packaged in a single container and delivered to the consumer, who simply puts it in the filter without separation into layers and purifies the water. In this case, large particles of impurities settle in the upper fine-grained part of the DFM, while smaller ones are retained by the lower fine-grained part of the DFM.

In the process of washing the filter loaded with such a DFM, the grains of heavier silica sand will be located in rising currents of water below the grains of lighter silicate glass of the same size as the sand, and at the same level with larger grains of silicate glass. After washing, the fine-grained particles of quartz sand will fall down at the speed of larger silicate glass grains. Thus, fine grains of material with a higher bulk density (silica sand) will be distributed between larger grains of material with a lower bulk density (silicate glass) and will create a second fine-grained layer located in the thickness of the filter charge below the upper fine-grained layer. As a result, in the filter load, after several washes, a second filtration stage is formed on the fine-grained layer, located below the first - upper filtration stage. Thus, the DFM forms two successive stages of fine-grained filtration in one filter.

The use of DFM will make it possible to intensify the filtration process and significantly improve the quality of the filtrate in all sectors where filtration processes are used: drinking water treatment, water treatment for pools and water parks, post-treatment of sewage, water treatment in the food industry, etc. It does not require replacement of filter equipment or an increase in the number of filters. It is enough to overload the filters and replace the old filter material with a new two-component. Thus, the solution to the problem with water quality is achieved without reconstruction of the water treatment facilities and at minimal cost. Also, the use of DFM will make it possible, if necessary, to increase the productivity of treatment facilities without significant capital costs by increasing the filtration rates.

On the basis of the DFM, a three-component filter material (TFM) is manufactured. In this case, the third component, crushed anthracite, is added to the DFM during the production process. At the same time, the characteristics of all used filter materials and the requirements for their composition must comply with current regulatory documents (SP 31.13330.2012, DIN 12904: 2005, etc.). Crushed anthracite, as the lightest material, creates an upper - coarse-grained filter layer in the filter, that is, a kind of prefilter that serves to retain the largest particles of contaminants. Thus, three successive stages of filtration are formed in the filter.

Ultimately, by combining natural and artificially made filter materials, it is possible to produce multicomponent filter materials for various purposes.

Claims (4)

1. A two-component filter material, characterized in that it contains two fine-grained materials used in water treatment technology, having the same particle size distribution and different bulk density, differing by 15-25%. 2. The two-component filter material according to claim 1, characterized in that silicate glass is used as the first filter material with a lower bulk density. 3. The two-component filter material according to claim 1, characterized in that quartz sand is used as the second filter material with a larger bulk. 4. The two-component filter material according to claim 1, characterized in that it is manufactured under production conditions by mixing quartz sand and silicate glass, followed by packing the resulting two-component filter material in a single container for transfer to the end consumer, which loads it into water filters .