RU2336120C1 - Method of production of filtering material for water purification from iron-containing admixtures and method of water purification using filtering material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: as initial raw material for filtering material production preliminary accumulated and dehydrated sediment from water purification, which mainly contains contaminant colloid particles, having chemical affinity with iron, is used. Sediment is pressed in briquettes with density 2.6 g/cm³ and fired by thermal sintering into conglomerate at temperature 1200-1400°C. Water purification is carried out on produced filtering material.

EFFECT: cheap and available raw material for production of filtering material and increase of its absorptive ability.

3 cl, 1 ex, 1 tbl

Description

The invention relates to the field of water purification of household and technical purposes from iron-containing impurities and the production of filter materials for these purposes. The invention can be used in water treatment of mineralized sources at borehole and river intakes.

The urgency of the problem of treating household and technical waters from iron-containing impurities is associated with significant water mineralization that occurs when minerals and rocks interact with groundwater, mainly in places where mineral deposits are concentrated. Impurities enter water bodies in most cases as a result of erosion of surrounding rocks and soil erosion.

At the underground water intake facilities, the environmental problem is most acute, associated with the collection and disposal of sludge formed as a result of water treatment of household and technical waters. The basis of the water treatment sludge at deferrization stations, for example, the Tomsk underground water deposit, is iron oxohydroxide (hydroxide). The problem is compounded by the fact that sediment, the amount of which remains very high, is often discharged into rivers or other bodies of water.

To separate the sediment from water, there is a water reuse system designed to flush fast filters with a large number of suspended particles. At deferrization stations, filters are used that are layer by layer loaded by screening of crushed rocks. One of the necessary technological operations of preparing the filter for operation is the activation of the filter material to form iron-containing centers on it, having an affinity for colloidal particles of the pollutant in the water to be purified and contributing to their deposition on the filter material in the form of a precipitate. The material is activated by prolonged transmission of untreated water through it without output to the consumer.

During the normal operation of the filter after its activation, these germinal centers purify water, trapping and agglomerating pollutants. After the filter is saturated with a colloidal precipitate, its throughput and filtering ability drops, and the filter must be washed with countercurrent washing water. The time between two washes (filter cycle) for typical filters used in underground water intakes is 24-36 hours. The estimated rate of water filtration through the filter charge is 8-10 m / h. Sludge for water treatment is fed to silt fields for drying and subsequent disposal.

Known methods of iron removal and filtering devices used for these purposes. Sorption water purification is carried out by filtering it using chemical reagents or chemical industry waste as filter material (ed. Certificate No. 1699525 “Method for producing filter material for water purification from iron compounds”, MKI B01D 39/00, C02F 1/28, publ. 12/13/1991, Bull. No. 47).

A known method of purification of running water containing metals, including the deposition of metal using drainage, grinding and dispersion of drainage elements, the deposition of metals (lead, zinc, copper, manganese, iron and metal compounds) and the removal of metals and their compounds from solutions to obtain pure water . The concentration of metals is less than 1.0 mg / L. The flow rate is about 10 gal / min. (Method for removing metals from a solution. US Pat. US 5536416, July 16, 1996).

Known methods for the removal of metals, including heavy metals, from running water, based on water purification and including stages such as separation, flotation, etc. Additional purification is carried out by activation with the addition of agents: limestone, ash, magnesium dioxide, metal salts (e.g. iron salts). (Methods for removing heavy metals from water using chemical precipitation and field separation methods. US Pat. No. 6896815, May 24, 2005).

A known method of treating water contaminated with metals and organic impurities by filtering using powdered iron and sand, serving as agents for the activation of aqueous solutions (Iron powder and sand filtration process for treatment of water contaminated with heavy metals and organic compounds. US Pat. No. 6,942,807, September 13, 2005).

A known device and method of filtering to remove contaminants from water using iron oxide and iron oxyhydroxide. The claimed method is not economically viable, because Fine filter iron or purified iron oxyhydroxide is used to load the filter. At the same time, the adsorption process includes, as an obligatory stage of the technology, the stage of mixing aluminum oxide, magnesium and titanium oxide or their hydroxide or the stage of dehydration of the product in a suspension of iron oxide and oxyhydroxide, which complicates the preparatory stage of the filter (German application No. DE 10129307 “Filtration unit for removing pollutants from fluids, especially water, comprising agglomerates of finely divided iron oxide and oxyhydroxide ", MKI C01G 49/02; C01G 49/06, publ. 2002.12.19).

A known method of water purification for domestic drinking water supply, based on obtaining filter material for water purification from iron and manganese (RF patent No. 2077380 "Method for producing granular filter material", MKI B02J 20/02, 20/04, publ. 04/20/1997 Bull. No. 11).

Known methods of water purification are associated with the need for preliminary activation of the filter and complete periodic replacement of the filter material in case of loss of filtering properties. The filtering materials shown in the analogues have sufficient absorption capacity, but they require significant investment in production. In addition, the task of disposing of the precipitate formed during filtration is practically not posed and solved.

A known method of obtaining filter material for purification of natural water of drinking water from iron compounds in the form of crushed dolomite, which after grinding is subjected to annealing, cooling and drying at a temperature of 100-200 ° C (RF patent No. 2162737 "Method for producing granular filter material" , MKI B02J 20/02, 20/06, B01D 39/02, publ. 02/10/2001, Bull. No. 4).

This method is accepted by us for the first prototype.

As the disadvantages of the method, it should be noted that dolomite is used as a filter material, the production of which is difficult due to the high strength of the material, because significant costs are required when grinding it. Dolomite is mined in the Leningrad region and its delivery, for example to areas of Western or Eastern Siberia, requires very high transport costs. In addition, this durable, frost-resistant material with all the properties of natural stone can find a more economically viable application, and therefore its use as a filter material cannot be considered justified. Moreover, the claimed purification method requires an additional step — activation using divalent manganese.

A known method of purification of household water and technical water for values from iron-containing impurities, based on the use of filter material from the screening of crushed rocks - albitofir, granodiorite, burned rocks (3.V.N. Lisetskiy, V.N. .Andreichenko. “Capture and disposal of water treatment sludge at Tomsk water intakes.” - Tomsk: Publishing House of Scientific and Technical Literature, 2003).

This publication presents a method of water purification at deferrization stations using filters layer-by-layer loaded with source material - screening crushed rocks with a total loading layer height of 1.8-2.1 m. One of the necessary technological operations for preparing the filter for work is the activation of the filter material consisting in the long passage of untreated water through it without its removal to the consumer for the formation of germinal iron-containing sedimentation centers on the fragments of the filter material from purified water having chemical affinity for the colloidal particles of the pollutant in the purified water in order to increase the absorption capacity of the filter material. Sludge from treatment is fed to silt fields for drying and subsequent disposal.

This technical solution was made by us for the second prototype.

The disadvantages of the technical solution for the second prototype:

1. Filters based on screening of crushed rocks have a limited service life (until the material is completely replaced) - not more than 1 year.

2. A mandatory technological operation is the activation of filtering material, which takes time from several days to several weeks.

3. Insufficient absorption capacity of the filter material

4. Requires material costs for the acquisition of screenings of crushed rocks used for the manufacture of the filter

5. Sludge from water treatment is not reused.

The first technical task is to obtain cheap and affordable raw materials for filtering material with increased absorption capacity, suitable for purification of natural water from drinking water from iron compounds and having a chemical affinity for iron.

The second task according to the invention is to reduce and reduce the cost of the technological cycle of water purification of borehole and river water intakes from iron-containing impurities.

The first task - obtaining a cheap and affordable feedstock for filters, expanding the range of filter materials, is solved as follows. After washing quick filters with a large amount of suspended particles, settling the wash water for the time required for the suspended particles to sediment and then re-purifying the water on quick filters, the sediment for water treatment from sedimentation tanks should be fed to silt fields for drying and subsequent disposal. The technology we developed for the production of filtering material allows us to use this accumulated and dehydrated sludge for water treatment. The advantage of this technology is that the accumulated and dehydrated sludge from water purification is predominantly colloidal particles of a pollutant having a chemical affinity for iron, which makes it possible for the filter material to adsorb iron-containing impurities optimally on itself.

To obtain filter material, the accumulated and dehydrated precipitate in the form of a powder mass, which is mainly iron hydroxide FeOOH (goethite) with the inclusion of a mixture of Fe (OH) ₃ and Fe ₂ O ₃ , was pressed into briquettes to a density of 2.6 g / cm ³ , then thermally sintered into the conglomerate at a temperature of 1200-1400 ° C, without bringing the temperature to the melting point (about 1600 ° C). The resulting conglomerate was crushed and sieved into size fractions according to the filter components.

Since the selected sintering temperature of the powdered mass is lower than the melting temperature, after sintering the product after crushing the conglomerate and sieving into fractions, it acquires a specific surface that is 5-7 times higher than the specific surface of the filter material from screenings of crushed rocks - albitofir, granodiorite, and burnt rocks. This allows you to create a filter from a material having a chemical affinity for the pollutant contained in the water to be purified and deposited on the filter. The filter material has a high absorption capacity for the pollutant. Moreover, almost the entire surface of the filter material is the nuclei for the deposition of colloidal particles of the pollutant and the filter capacity as a whole is greater than that of the prototype method, which allows to increase the filtering cycle of water treatment. In addition, the filter material does not require irreversible replacement: after repeated processing and sieving it is again ready for use, and excess material, which is small solid particles of various sizes, can be used for other purposes, for example, in the production of building materials, paints, etc. P.

The second task - reducing and cheapening the technology of water purification from iron-containing impurities is achieved by replacing the purification cycle using filter material from the screening of crushed rocks or other filter material by cleaning using filter material with increased absorption capacity obtained from accumulated and dehydrated sludge. Thus, in accordance with the claimed method, the deposition and agglomeration of pollutants is carried out without prior activation of the filter material - it is not necessary, because sediment as a filtering material already initially has a chemical affinity for colloidal particles of a pollutant in filtered water. Thanks to this technical solution, the technology of water purification from iron-containing impurities is simplified and cheapened, and the filter cycle is increased due to the possibility of a longer use of the filter (increased time between washes) - at least 48 hours.

The analysis of the prior art, including a search by patent and scientific and technical sources of information, made it possible to establish that a technical solution characterized by features identical to the essential features in the claimed technical solutions was not found, which allows us to conclude that the proposed solution meets the criterion of "novelty."

Distinctive features allow us to solve the tasks and make a conclusion on the conformity of the claimed technical solutions with the criteria of "inventive step" and "industrial applicability".

An example implementation of the method.

The sediment of water treatment of artesian water of the Tomsk field in the form of a powder mass, representing iron hydroxide FeOOH (goethite) and including a mixture of products Fe (OH) ₃ and Fe ₂ O ₃ , was pressed into briquettes with sizes of 40 × 50 mm with a density of up to 2, 6 g / cm ³ , then thermally sintered in the conglomerate at a temperature of 1200-1400 ° C, without bringing the sintering temperature to the melting temperature. After cooling, the resulting material was crushed and scattered into size fractions in layers, the main filtering mass being 5–2 mm, and the supporting layers respectively: extremely large fraction 40–30 mm, coarse 20–10 mm and transition to the main filtering layer 10 ÷ 5 mm. The resulting filter material was loaded layer-by-layer into a filter column with a total height of up to 1.9 m. The height of the main filter layer with a thickness of 5 ÷ 2 mm is 1.5 m, the height of the support layers is 0.2 and 0.1 m, respectively, and the height of the transition layer is 0.1 m. water through a filter column (water supply to the column from the bottom up), water treatment results were obtained for the main components of pollution (iron, manganese). The results are tabulated.

Cleaning method The main elements of contamination, mg / l (average) Estimated rate of water filtration through the filter load, m / h Filter cycle time, h Iron before cleaning after cleaning Manganese before cleaning after cleaning Prototype method 2.64 0.15 0.18 0,071 8-10 24 The inventive method 2.64 0.12 0.18 0,069 8-10 48

Claims (3)

1. The method of obtaining filter material for water purification from borehole and river water intakes from iron-containing impurities by calcining and grinding the source material and dispersing the crushed particles into fractions, characterized in that the collected and dehydrated sludge from water treatment, which contains mainly colloidal particle contaminants having affinity for iron as goethite FeOOH-, Fe (OH) ₃ and Fe ₂ O ₃ and the precipitate was pressed into briquettes to a density of 2.6 g / cm ^3, calcined by thermal pecans into conglomerates at 1200-1400 ° C. 2. Filtering material for purifying water from borehole and river intakes from iron-containing impurities, characterized in that it is obtained by the method described in paragraph 1. 3. The method of purification of water from borehole and river intakes from iron-containing impurities, characterized in that the water is passed through a filter material described in paragraph 2.