RU2094103C1 - Method of restoring performance characteristics of tubular ultrafilters - Google Patents

Abstract

FIELD: filtration technics. SUBSTANCE: method of restoring performance characteristics of ultrafilters for separation, concentration, and purification of waste waters and process liquid mixtures via ultrafiltration procedure includes rinsing with water, washing with detergent water solution, and wiping before and after washing. The latter procedure is performed with the aid of rotating and reciprocating motions of wiping device made in the form, for example, of rigid frame one of the ends of which bears one or several fastened spongy elastic balls, whereas, as detergent, a mixture is used composed of polyoxyethylene ether of isooctylphenol, citric, acetic, formic, hydrochloric or nitric acid or N-methylpyrrolidone, dimethylacetamide or dimethylformamide. EFFECT: intensified and facilitated procedure. 2 dwg , 1 tbl

Description

 The invention relates to membrane technology and can be used in the processes of separation, concentration and purification of wastewater components and technological liquid mixtures, in particular containing metallic soaps, by the method of ultra- and microfiltration using tubular filter elements.

 During long-term operation of tubular ultrafilters, the surface of their membranes becomes contaminated, as a result of which their filtrate productivity sharply decreases. In order to clean the membrane surface and restore filtrate performance, the ultrafilters are washed with an aqueous solution of a strong oxidizing agent (chlorine, chlorite or sodium hypochlorite, hydrogen peroxide, ozone or sodium persulfate) or a reducing agent (hydroiodic acid, hydrogen sulfide, aluminum hydride, formaldehyde or acetaldehyde).

 The specified method is associated with the use of highly aggressive, harmful, unstable substances, is not effective when deposition on the ultrafilter membrane of greasy sticky sediments from difficultly oxidized or difficult to recover substances.

 There is also a known method and device for performing mechanical removal of sediment from the surface of a tubular membrane using elastic balls, the size of which slightly exceeds the inner diameter of the membrane. The balls are made of a softer than the membrane material of natural or synthetic rubber. With a fluid flow, the ball is pushed inside the tube, during its movement it rubs against the surface of the membrane and removes the precipitate of impurities detained by the membrane. Wash water with balls is discharged from the ultrafilter into the tank, where the balls are separated from the wash liquid, washed from contaminants and can again be fed to wipe the membrane surface.

 However, in the known method, so that the balls are freely pushed by the liquid flow, their diameter should be small, 5-15% larger than the diameter of the tubular membrane. The movement of the ball is carried out only in the direction of flow, to ensure the effect requires multiple transmission of the balls.

 A known method of restoring the operational properties of tubular ultrafilters after long-term operation by removing the old membrane and applying a new membrane to the regenerated open-porous ultrafilter tube.

 The known method is time-consuming and expensive, it takes to disassemble the ultrafilter, remove the used membrane from the open-porous tube, apply a new membrane to the regenerated open-porous tube, assemble the ultrafilter, preserve the membrane in the ultrafilter.

 Closest to the claimed technical solution is a method of restoring the operational properties of tubular reverse osmosis membrane filter elements, including washing, mechanical cleaning of the membrane with sponge pieces and additional washing of the membrane with an aqueous solution of citric acid at pH 4. Soft deposits from colloidal particles are removed with sponge pieces. Hard deposits on the membrane, formed from sparingly soluble calcium salts, dissolve under the influence of citric acid.

 The known device for wiping in the form of an elastic element is pushed through the tube of the membrane filter element by hydraulic transport unidirectionally in accordance with the direction of the liquid flow of purified water. However, the elastic element may deform and clog the ultrafilter tube at the points of narrowing of the pressure channel of the ultrafilter (at the ends of the tube where the sealing gum and spacer rings are attached for them to further secure the ends of the tubular membrane). Reducing the size of the elastic element improves its throughput in the tube, but reduces the effectiveness of wiping. The unidirectional movement of the elastic element by hydraulic transport determines the contact of the same place of the elastic element with the surface of the contaminated membrane. This section of the elastic wiping element is quickly contaminated and with further movement along the tube inefficiently cleans the membrane surface along the entire length of the tube.

 Combined cleaning according to the known method is effective in the restoration of reverse osmosis tubular filter elements used for the treatment of fresh, hard, but sufficiently clean water. However, this method of restoring the operational properties of the tubular membrane was ineffective in treating wastewater containing metallic soaps (salts of higher fatty acids and alkaline-earth or heavy metals). After several months of operation, tubular ultrafilters for the treatment of wastewater containing metal soaps greatly reduced filtrate performance. The specified method of restoring the operational properties of the tubular membrane does not give the necessary effect, therefore, it was necessary to replace expensive ultrafilters.

 The aim of the invention is to develop a method for restoring the operational properties of tubular ultrafilters for the separation, concentration and purification of wastewater components and technological liquid mixtures, including those containing metal soaps without replacing the membrane.

 This goal is achieved by the fact that in the known method of restoring the operational properties of tubular ultrafilters, including rinsing with water, rubbing with a sponge elastic material the inner surface of the tubes of ultrafilters after applying them to concentrate and treat wastewater or liquid process media, including those containing metal soaps, and washing ultrafilters using aqueous solutions of detergents, according to the invention, wiping is carried out by performing a combination of a rotator and reciprocating movements moistened with a detergent solution of a hard-wiping device before and after washing, and washing is carried out using the same washing solution containing 0.1-0.2 wt. isooctylphenol polyoxyethylene ether, 0.2-0.4 wt. citric, acetic, formic, hydrochloric or nitric acids, the rest is water or 5-10 wt. N-methyl-pyrrolidone, dimethylacetamide or dimethylformamide, the rest is water.

 Another difference is that the surface of the membranes is wiped using a device made in the form of a rigid mandrel, on one end of which 1-3 spongy elastic balls are fixed, located in the center at a distance from each other of 0.5-0.7 of the diameter of the ball or soft elastic ruff with a diameter equal to 1.5-2.0 diameters of the tubular membrane.

 Wiping the surface of the membrane with a wiping device (a spongy elastic ball or a soft elastic ruff fixed on a rigid mandrel) while rubbing against the surface of the membrane provides effective removal of impurities held by the membrane, and subsequent washing with detergents allows you to dissolve or emulsify the residue in the pores of the membrane, and the final wipe allows you to fix the result.

 The fundamental difference between the proposed wiping operation and the currently used one, carried out by repeatedly unidirectionally pushing the sponge elastic ball by hydrotransport, is that using a device made in the form of a rigid mandrel, 1-3 spongy elastic balls are fixed at one end of it in the center at a distance from each other of 0.5-0.7 diameter of the ball, or a soft elastic ruff with a diameter equal to 1.5-2.0 of the diameter of the tubular membrane, it is possible to provide a combination of different directional movements of the elastic element, as a result of which the efficiency of cleaning the surface of the membrane, fixed on the inner surface of the ultrafilter tube, of greasy deposits, including from metal soaps retained by the membrane, is significantly increased. The rigid traction, to which the elastic elements for wiping are attached, in addition to the possibility of providing multidirectional movements of the elastic element, allows the elastic element of a larger diameter (5-30%) to be pushed through the tube, which also helps to clean the surface of the membrane from greasy deposits of metal soaps. The execution of the elastic element of the wiping device in the form of an assembly of 2-3 balls located at a distance of 0.5-0.7 diameters, or a ruff with a diameter equal to 1.5-2.0 diameters of the tubular membrane, helps to ensure a combination of multidirectional movements elastic element wiping device. In addition, each subsequent from the end of the mandrel, the elastic ball or each section of the elastic ruff makes its additional contribution to the cleaning of the previously cleaned membrane surface with the previous ball or the ruff section, which also improves the cleaning of the membrane surface. Impregnation of the elastic element of the wiping device with a detergent solution reduces the friction of the elastic element on the membrane, contributes to the decomposition, dissolution or dispersion of contaminants on the membrane.

 The fundamental difference between the washing operation in the proposed method of restoring the operational properties of tubular ultrafilters after treatment of wastewater and technological liquid media, including those containing metal soaps, from the known one using citric acid, is that the composition of the washing solution for washing the membrane from sediment, including metal soaps and compounds of alkaline earth and heavy metals, in addition to citric acid, includes a surfactant, namely polyoxyethyl isooctylphenol ylene ether in a concentration of 0.1-0.2 wt. Instead of citric acid, acetic, formic, hydrochloric or nitric acid with a concentration of 0.2-0.4 wt. 5-10 wt% aqueous solutions of N-methyl-pyrrolidone, dimethylacetamide or dimethylformamide can also be used as a washing solution. The proposed compositions of the washing solutions due to chemical and physico-chemical transformations decompose, loosen and translate into a soluble or finely dispersed state the remains of contaminants on the membranes, as a result of which the operational properties of tubular ultrafilters are restored.

 Figure 1 shows a variant of the General view of the device with sponge elastic balls for wiping the membrane in a tubular ultrafilter according to the proposed method, General view; figure 2 is the same, in working condition.

 The wiping device contains sponge elastic balls 1, the diameter of which is 5-30% larger than the diameter of the tubular membrane in the membrane filter element. The number of balls is 1-3 pieces. The balls 1 in the center are firmly fixed to a rigid mandrel 2, the length of which is greater than the length of the membrane tubular filter element. The distance between the balls is equal to 0.5-0.7 diameter of the balls.

 Wiping device operates as follows. Elastic sponge balls 1 are dipped into the washing solution and inserted into the pressure channel of the ultrafilter from one end of the tube 3 (figure 2). The mandrel is simultaneously imparted with reciprocal rotational and reciprocating movements, moving it to the other end of the tube 3. Balls 1, whose diameter is 5-30% larger than the diameter of the tubular membrane, are slightly deformed and wipe the surface of the membrane located on the inner surface of the tube, cleaning the membranes from pollution 4.

 The first ball removes most of the sediment from the membrane, and each subsequent one contributes to additional cleaning, coming into contact with the already partially partially cleaned surface of the membrane. The intervals between the balls form cavities 5, which provide easy advancement of the mandrel inside the ultrafilter and greater freedom for multidirectional movements of the elastic element of the wiping device during manipulation of the frame.

 In a similar way, another version of the wiping device works, where instead of balls at the end of the mandrel, a soft elastic ruff is fixed, the diameter of which is 1.5-2.0 diameters of the tubular membrane.

 As sponge elastic material for balls, open-porous elastic materials based on synthetic and natural polymers (polyurethanes, natural or synthetic rubber) can be used.

 Ruff can be made of soft bristles, soft elastic synthetic fibers or open-porous poroplasty.

 The mandrel may be a rod or tube made of metal, plastic or fiberglass with a diameter less than the diameter of the tubular membrane in the ultrafilter.

 For the preparation of washing solutions, polyoxyethylene ethers of isooctylphenol OP-5, OP-7 or OP-10 (GOST 8433-81), citric, acetic, formic, hydrochloric or nitric acid, N-methyl-pyrrolidone, dimethylacetamide or industrial dimethylformamide are used release.

 Comparative analysis shows that the proposed method for restoring the operational properties of tubular ultrafilters and a device for its implementation are distinguished by the novelty of the technical solution.

 Despite the popularity of wiping the surface of the membranes in a tubular ultrafilter, in order to prevent the formation and removal of sediments of impurities retained by the membrane and washing the membrane to remove substances that clog its pores, the wiping operation is performed due to a complex of multidirectional movements of the elastic element of the wiping unit moistened with a washing solution in the form of a rigid mandrel, at one end of which 1-3 spongy elastic balls are fixed, located in the center at a distance from each other 0.5-0.7 ball diameter, or soft elastic ruff with a diameter of 1.5-2.0 diameter of the tubular membrane, and performing a washing operation using a detergent solution containing 0.1-0.2 wt. isooctylphenol polyoxyethylene ether, 0.2-0.4 wt. citric, acetic, formic, hydrochloric or nitric acid, the rest is softened water or 5-10 wt. N-methyl-pyrrolidone, dimethylacetamide or dimethylformamide, the rest softened water, is a new and not simple use of a known technique. Experimentally found new sets of techniques and properties of the process are decisive factors for targeted measures to ensure the restoration of the operational properties of tubular ultrafilters after wastewater containing metal soaps. The mismatch of technical properties from the point of view of the positive effect of the claimed and known objects indicates that as a result there is a new set of features of the solution, leading to the emergence of a new phenomenon (property) that ensures the achievement of a positive effect, which allows us to recognize the proposed method meets the criterion of "significant differences" .

 The claimed technical solution is illustrated by the following examples.

 Example 1 (prototype).

Tubular ultrafilters with a polyvinylidene fluoride-based membrane with a diameter of 254 mm, a length of 3 m at a pressure of 0.2 MPa and a temperature of 25 ^o C have an initial specific permeability for softened water of 300-600 l / m ² • h. When cleaning (regenerating) the spent washing solution containing caustic soda, sulfonated castor oil and paint, the initial specific productivity of these ultrafilters according to the filtrate for the same parameters is 50-90 l / m ² • h, the selectivity for paint is 100%. ultrafilters gradually decreased, selectivity remained the same. Periodic washing of ultrafilters with an aqueous solution of citric acid at pH 4 and wiping with elastic sponge balls introduced into the channel of the ultrafilter tube and pushed by the liquid flow circulating in the channel gave some effect at first, but after 7 months of operation of ultrafilters in the ultrafiltration unit, their specific filtrate performance decreased up to 15-20 l / m ² • h and did not recover after the above method of wiping and washing. After rinsing with softened water, such ultrafilters have a soft water permeability of 10-100 l / m ² • h. Studies of used ultrafilters have shown that the main reason for their failure is a precipitate consisting of metal soaps and other compounds of alkaline earth metals and heavy metals. This precipitate is deposited on the surface of the membrane and clogs its pores. As a result of the high hydraulic resistance of the sediment, the performance of ultrafilters sharply decreases. The precipitate is smeared, sticky, and difficult to remove from the surface of the ultrafilter membrane.

 Example 2

A tubular ultrafilter was used after 7 months of operation, as in example 1, having a specific filtrate throughput of 20 l / m ² • h when processing the spent washing solution and a specific permeability to softened water after rinsing of 100 l / m ² • h.

 A wiping device consisting of a mandrel (a rod with a diameter of 12 mm) and a spongy elastic ball, whose diameter is 294 mm, is dipped into the washing solution containing 0.2 wt. isooctylphenol polyoxyethylene ether (OP-7), 0.4 wt. citric acid and 99.4 wt. softened water.

 After that, the end of the mandrel with the ball is placed in the tube of the ultrafilter and push the ball to the other end of the ultrafilter, making the mandrel at the same time rotational and reciprocating movements. Then the mandrel is removed from the ultrafilter tube, the ball is washed with the same detergent solution from contamination. The ultrafilter tube is poured with a washing solution of the above composition and left for 5 hours at room temperature. Then, the washing solution is drained from the ultrafilter tube, and it is again wiped with a washed wiping device as described above.

The performed operations ensure restoration of the membrane permeability of the tubular ultrafilters (initial specific water permeability in softened water is 380 l / m ² • h, the initial specific productivity in the filtrate when cleaning the spent washing solution was 80 l / m ² • h at 100% paint retention selectivity).

 Example 3

After a tubular ultrafilter after 7 months of operation, as in example 1, which has a specific filtrate capacity in the treatment of spent washing solution of 20 l / m ² • h and a specific permeability of softened water of 100 l / m ² • h, the operational properties were restored, as in Example 2, with the only difference being that 3 balls are fixed at the end of the mandrel at a distance from each other equal to 0.7 of the diameter of the ball. The recovered ultrafilter had a specific permeability for softened water of 500 l / m ² • h, a specific filtrate capacity for processing spent washing solution of 90 l / m ² • h, and a separation selectivity of 100% for paint
The same results were obtained when fixing the balls on the mandrel at a distance from each other equal to 0.5 of the diameter of the ball.

 Example 4

The restoration of the operational properties of the tubular ultrafilter is carried out, as in example 3, at a distance between the balls attached to the end of the mandrel, equal to 0.3 of their diameter. The specific productivity of the recovered ultrafilter for softened water is 260 l / m ² • h according to the filtrate. When processing the spent washing solution 55 l / m ² • h. 100% paint separation selectivity
Simulation of the operation of the wiping device in a glass tube shows that when the distances between the balls are less than 0.5 of their diameter, when the balls are deformed during wiping, a single wiping element of three balls is formed without intermediate cavities between the balls, which are created when the balls are arranged from each other at distances greater than 0.5 of their diameter.

 Example 5

A method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 0.30 wt. OP-7. The recovered ultrafilter has a soft water permeability of 350 l / m ² • h, before recovery it had 90 l / m ² • h.

 Example 6

A method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 0.05 wt. OP-7. The recovered ultrafilter has a soft water permeability of 200 l / m ² • h, before recovery it had 90 l / m ² • h.

 Example 7

The method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 0.1 wt. citric acid. The recovered ultrafilter has a soft water permeability of 180 l / m ² • h, before recovery it had 100 l / m ² • h.

 Example 8

A method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 0.5 wt. citric acid, 0.1 wt. OP-7; 99.4 wt. softened water. The recovered ultrafilter has a soft water permeability of 390 l / m ² • h, before recovery it had 100 l / m ² • h.

 Example 9

The method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 15 wt. OP-7; 0.4 wt. acetic acid and 99.45 wt. softened water. The recovered ultrafilter has a specific permeability of softened water of 360 l / m ² • h, before recovery it had 100 l / m ² • h, the filtrate performance during processing of the spent washing solution 85 l / m ² • h, the selectivity of paint retention is 100%
Example 10

A method of restoring the operational properties of tubular ultrafilters, as in example 9, but the concentration of acetic acid in the washing solution is 0.5 wt. OP-7 0.2 wt. softened water 99.3 wt. The recovered ultrafilter has a specific permeability of softened water of 360 l / m ² • h, before recovery it had 90 l / m ² • h.

 Example 11

A method of restoring the operational properties of tubular ultrafilters, as in example 9, but the concentration of acetic acid in the washing solution is 0.1 wt. OP-7 0.2% wt., Softened water 99.7 wt. The recovered ultrafilter has a specific permeability for softened water of 250 l / m ² • h, before recovery it had 100 l / m ² • h.

 Example 12

A method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 0.2 wt. OP-7, formic acid 0.4 wt. softened water 99.4 wt. The recovered ultrafilter has a specific permeability to softened water of 370 l / m ² • h, before recovery it had 90 l / m ² • h.

 Example 13

A method of restoring the operational properties of tubular ultrafilters, as in example 12, but the washing solution contains OP-7 0.2 wt. formic acid 0.5 wt. softened water 99.3 wt. The recovered ultrafilter has a specific permeability for softened water of 380 l / m ² • h, before recovery it had 100 l / m ² • h.

 Example 14

A method of restoring the operational properties of tubular ultrafilters, as in example 12, but the washing solution contains OP-7 0.2 wt. formic acid 0.05 wt. softened water 99.75 wt. The recovered ultrafilter has a specific permeability for softened water of 70 l / m ² • h, before recovery it had 30 l / m ² • h.

 Example 15.

A method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 10 wt. N-methyl pyrpolylidone and 90 wt. softened water. Rinse for 5 hours at room temperature under static conditions. The recovered ultrafilter has a specific productivity in softened water of 350 l / m ² • h, before recovery it had 100 l / m ² • h. The specific productivity of the recovered ultrafilter by filtrate during processing of the selected washing solution is 50 l / m ² • h, the separation selectivity for paint is 100%
Example 16

A method of restoring the operational properties of tubular ultrafilters, as in example 15, but the washing solution contains 5 wt. N-methyl pyrpolylidone and 95 wt. softened water. The recovered ultrafilter has a specific productivity in softened water of 240 l / m ² • h, before recovery it had 90 l / m ² • h.

 Example 17

The method of restoring the operational properties of tubular ultrafilters, as in example 15, but the washing solution contains 2 wt. N-methyl pyrpolylidone and 98 wt. softened water. The recovered ultrafilter has a specific permeability to softened water of 60 l / m ² • h, before recovery it had 20 l / m ² • h.

 Example 18

A method of restoring the operational properties of tubular ultrafilters, as in example 15, but the concentration of N-methylpyrphenolone 12 wt. the rest is water. The recovered ultrafilter has a specific permeability for softened water of 340 l / m ² • h, before recovery it had 100 l / m ² • h.

 Example 19

The method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 10 wt. dimethylacetamide and 90 wt. softened water. Rinse for 5 hours at room temperature under static conditions. The recovered ultrafilter has a specific permeability for softened water of 250 l / m ² • h, before recovery it had 40 l / m ² • h.

 Example 20

A method of restoring the operational properties of tubular ultrafilters, as in example 19, but the washing solution contains 2 wt. dimethylacetamide and 98 wt. softened water. The recovered ultrafilter has a specific permeability to softened water of 50 l / m ² • h, before recovery it had 30 l / m ² • h.

 Example 21

A method of restoring the operational properties of tubular ultrafilters, as in example 19, but the washing solution contains 5 wt. dimethylacetamide and 95 wt. softened water. The recovered ultrafilter has a specific permeability for softened water of 180 l / m ² • h, before recovery it had 40 l / m ² • h.

 Example 22

The method of restoring the operational properties of tubular ultrafilters, as in example 19, but the concentration of dimethylacetamide 12 wt. the rest is water. The recovered ultrafilter has a specific permeability of softened water of 250 l / m ² • h, before recovery it had 60 l / m ² • h. The specific productivity of the filtrate in the treatment of spent washing solution 55 l / m ² • h.

 Example 23

The method of restoring the operational properties of tubular ultrafilters, as in example 2, but the washing solution contains 10 wt. dimethylformamide and 90 wt. softened water. The recovered ultrafilter has a specific permeability for softened water of 220 l / m ² • h, before recovery it had 30 l / m ² • h.

 Example 24

A method of restoring the operational properties of tubular ultrafilters, as in example 23, but the washing solution contains 5 wt. dimethylformamide and 95 wt. softened water. The recovered ultrafilter had a specific permeability for softened water of 170 l / m ² • h, before recovery it had 40 l / m ² • h.

 Example 25

The method of restoring the operational properties of tubular ultrafilters, as in example 23, but the washing solution contains 2 wt. dimethylformamide and 98 wt. softened water. The recovered ultrafilter has a specific permeability to softened water of 60 l / m ² • h, before recovery it had 20 l / m ² • h.

 Example 26

The method of restoring the operational properties of tubular ultrafilters, as in example 23, but the concentration of dimethylformamide is 12 wt. the rest is water. The recovered ultrafilter has a specific permeability for softened water of 220 l / m ² • h, before recovery it had 40 l / m ² • h.

 Example 27

A method of restoring the operational properties of tubular ultrafilters, as in example 2, but instead of a ball at the end of the mandrel, a soft elastic ruff with a diameter equal to 1.5-2.0 diameters of the tubular membrane is fixed. The recovered ultrafilter has a softened water permeability of 400 l / m ² • h, before recovery it had 70 l / m ² • h and the specific filtrate throughput for processing the spent wash-off solution was 85 l / m ² • h at 100% paint selectivity.

 Example 28

The method of restoring the operational properties of tubular ultrafilters, as in example 2, but used to treat raw glycerin neutralized with lime milk, and the wiping device consisted of 2 tubular elastic balls fixed in the center at one end of the mandrel and 0.6 distance from each other diameter of balls. The recovered ultrafilter had a specific permeability for softened water of 450 l / m ² • h, before recovery it had 40 l / m ² • h and a specific filtrate performance when processing raw glycerin neutralized with lime milk 60 l / m ² • h at 98% selectivity fatty acids.

 Example 29

A method of restoring the operational properties of tubular ultrafilters, as in example 3, but the washing solution contains 0.2 wt. OP-7 and 0.4 wt. of hydrochloric acid. The recovered ultrafilter has a specific permeability for softened water of 500 l / m ² • h, before recovery it had 10 l / m ² • h and a specific filtrate capacity for processing waste detergent solution of 85 l / m ² • h at 100% paint selectivity.

 Example 30

The method of restoring the operational properties of tubular ultrafilters, as in example 29, but the washing solution contains 0.1 wt. OP-7 and 0.2 wt. of hydrochloric acid. The recovered ultrafilter has a specific permeability to softened water of 590 l / m ² • h, before recovery it had 50 l / m ² • h.

 Example 31

The method of restoring the operational properties of tubular ultrafilters, as in example 29, but the washing solution contains 0.2 wt. OP-7 and 0.05 wt. of hydrochloric acid. The recovered ultrafilter has a specific permeability for softened water of 150 l / m ² • h, before recovery it had 70 l / m ² • h.

 Example 32

A method of restoring the operational properties of tubular ultrafilters, as in example 3, but the washing solution contains 0.1 wt. OP-7 and 0.4 wt. nitric acid. The recovered ultrafilter has a specific permeability for softened water of 150.0 l / m ² • h, before recovery it had 40 l / m ² • h.

 Example 33

A method of restoring the operational properties of tubular ultrafilters, as in example 32, but the washing solution contains 0.2 wt. OP-7 and 0.2 wt. nitric acid. The recovered ultrafilter has a specific permeability for softened water of 190 l / m ² • h, before recovery it had 20 l / m ² • h.

 Example 34

A method of restoring the operational properties of tubular ultrafilters, as in example 32, but the washing solution contains 0.25 wt. OP-7 and 0.05 wt. nitric acid. The recovered ultrafilter has a specific permeability for softened water of 120 l / m ² • h, before recovery it had 80 l / m ² • h.

 The data are tabulated.

 As can be seen from the table, the proposed method of restoring the operational properties of tubular ultrafilters after applying them for concentration and wastewater treatment (spent flushing solution, examples 2-27, 29-34) or liquid technological mixtures (crude glycerin after treatment with milk of lime, example 28) containing metal soap, carried out by performing a combination of rotational and reciprocating movements of a wiping device moistened with a washing solution with a rigid draft before and after washing and washing with zovaniem the same detergent solution containing 0.1-0.2 wt. polyoxyethylene ether isooctylphenol and 0.2-0.4 wt. citric acid, the rest is water (examples 2-5, 8, 27, 28) or 0.1-0.2 wt. polyoxyethylene ether isooctylphenol and 0.2-0.4 wt. acetic acid, the rest is water (examples 9, 10), or 0.1-0.2 wt. polyoxyethylene ether isooctylphenol and 0.2-0.4 wt. formic acid, the rest is water (examples 12, 13), or 5-10 wt. N-methyl-pyrrolidone, the rest is water (examples 15,16,18), or 5-10 wt. dimethylacetamide, the rest is water (examples 19,21,22), or 5-10 wt. dimethylformamide, the rest is water (examples 23,24,26), or 0.1-0.2 wt. polioethyl ether of isooctylphenol and 0.2-0.4 wt. hydrochloric acid, the rest is water (examples 29.30), or 0.2-0.4 wt. nitric acid, the rest of the water (examples 32,33) provides restoration of the permeability of used ultrafilters almost to their original values while maintaining the selectivity of the membrane. Wiping the surface of the membrane can be carried out using a device made in the form of a rigid mandrel, at one end of which are fixed 1-3 spongy elastic balls (examples 2-26,28-34) located in the center at a distance from each other of 0.5-0 , 7 diameters of a ball (examples 2,3,5-23,25) or a soft elastic ruff (example 27 with a diameter equal to 1,5-2,0 diameters of a tubular membrane. Performing the wiping operation before and after washing the ultrafilters with providing multidirectional movements when pushing a soft elastic ball or ruff, heated at the end of a rigid mandrel allows effective mechanical cleaning of the surface of the tubular membrane in the ultrafilter from deposits of metal soaps and other compounds of alkaline earth and heavy metals, while the proposed cleaning solutions decompose, loosen, and translate into soluble or chemical transformations finely dispersed state remains of contaminants on the membranes, which, ultimately, as a result of a combination of effective mechanical stresses, chemical and physico-chemical transformations leads to the reduction of permeability of tubular ultrafilters to initial values without deteriorating the selectivity of the membrane.

Using the proposed method for restoring the operational characteristics of tubular ultrafilters and a device for its implementation provides, in comparison with known methods and devices, the following advantages:
a) the possibility of restoring the water permeability of used ultrafilters to their original values without replacing the membrane and reducing its separation selectivity, which is especially important since the service life of expensive tubular ultrafilters increases;
b) a structurally simple instrumentation of the process requires a small amount of raw materials produced on an industrial scale;
c) for the implementation of the process practically no additional capital costs are required.

Claims (4)

 1. A method of restoring the operational properties of tubular ultrafilters, including rinsing with water, rubbing with a sponge elastic material the inner surface of the tubes of ultrafilters and washing them with an aqueous solution of detergents, characterized in that the wiping is carried out before and after washing by performing a combination of rotational and reciprocating movements of the wetted detergent means wiping device having a rigid traction, and as a detergent use an aqueous solution containing 0.1 to 0.2 wt. isooctylphenol polyoxyethylene ether, 0.2 0.4 wt. citric, or acetic, or formic, or hydrochloric, or nitric acid, or 5 to 10 wt. an aqueous solution of N-methyl-pyrrolidone, or dimethylacetamide, or dimethylformamide.  2. The method according to claim 1, characterized in that the wiping is carried out using a device made in the form of a rigid mandrel, on one end of which a spongy elastic ball is fixed.  3. The method according to claim 2, characterized in that the wiping is carried out using a device made in the form of a rigid mandrel, on which several spongy elastic balls are fixed, located along the axis of the mandrel at a distance from one another, equal to 0.5 0.7 diameter ball.  4. The method according to claim 1, characterized in that the wiping is carried out using a device made in the form of a soft elastic ruff with a diameter equal to 1.5 2 of the diameter of the tubular ultrafilter.

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