Water treatment process

FIELD: water treatment.

SUBSTANCE: invention relates to removing and decomposing nitrate ions contained in water, for example in ground water or in surface waters. Process consists in passing aqueous solution through electrochemical cell containing at least one anode and at least one cathode and passing electric current between them. Surface(s) of cathode is(are) covered with layer consisted of metallic rhodium. Aqueous solution is preferably aqueous solution, which was used for regeneration of ion-exchange column.

EFFECT: enhanced electrochemical cell efficiency.

18 cl, 3 ex

 

The present invention relates to a method of water purification, according to which nitrate ions are removed from aqueous solutions that contain them, and to a method for removal and decomposition of nitrate ions contained in the water, such as groundwater or surface waters.

Widespread in recent times, the use of fertilizers has led to an increase in nitrates in the water. The content of nitrates in drinking water, greater than 50 parts per million (ppm), leads to health problems, such as “blue syndrome child” and possible cancer of the stomach. In addition, nitrates are often present in wastewater that can be released into the water system in a concentrated form; such emissions of nitrates is considered the main cause of algal blooms in reservoirs, and inland and coastal eutrophication - eutrophication of water bodies algae. This prevalence of nitrates in the environment has led to legislative restriction of nitrates in drinking water and industrial wastes.

Nitrates at present, as a rule, removed from solutions of either ion exchange or reverse osmosis.

When conducting ion-exchange processes nitrosoureas solutions (usually containing cations of calcium, magnesium and sodium in combination with anion - nitrate is m, sulfate, chloride and bicarbonate) is passed through a column containing anion exchange resin. When the anion exchange resin is fully loaded nitrate-ions, the resin is recovered, for example, using a solution of salt (sodium chloride). Then there is the exchange of nitrate ions on chloride-ions of the salt solution, and the resulting sodium nitrate and salt mixture is then dumped as waste.

When carrying out reverse osmosis solutions of nitrates is passed through the membrane, which holds approximately 90% of nitrate-ions (and other ions), usually 20% of the used solution. The obtained concentrated solution of detainees ions must then be disposed of as waste.

Removal of nitrate ions from the solution are also available, and other technologies, such as biological denitrification.

Problems associated with known methods for the removal of nitrates, is that as a waste are thrown away rather concentrated solutions of nitrates. In addition, in the case of ion exchange, for further use of ion exchange resins may require fresh regenerating solutions, resulting in significant production costs.

Also known destruction of nitrate ions with the use of electrolysis. For example, in application EP-A-291330 described method of treatment of groundwater containing itrate, which comprises contacting water with ion exchange resins and resin regeneration regenerating means, according to the method used regenerating means is electrolyzed. Regenerating means may contain bicarbonate, chloride or sulfate ions. The electrolysis is carried out in an electrochemical cell containing an anode and a cathode. The material of each of the electrodes is a platinized titanium, Nickel, stainless steel, copper or graphite. Released during this gaseous nitrogen can simply enter the atmosphere.

In U.S. patent US-A-3542657 described by way of conversion of nitrate of an alkali metal in the alkali metal hydroxide by passing nitrate solution through an electrolytic cell in which miss DC current between the anode and cathodes arranged in the cell, while receiving gaseous oxygen at the anode and hydroxide of alkali metal on the cathodes. The cathodes also produces nitrogen gas. Preferably use such bipolar cells in which the cathodes are copper, lead, tin, iron, silver, cadmium, platinum, cobalt, Nickel and their alloys or coated them with other metals.

The present invention is directed to the creation of yet another method of removing nitrate ions from aqueous solutions that contain them, using e is estrogenically cell.

The present invention provides a method of removing nitrate ions from aqueous solutions that contain them, by passing the solution through an electrolytic cell containing at least one anode, and at least one cathode, and passing direct current between them, according to this method, the surface (surface) of the cathode include a metal rhodium.

Unexpectedly it was found that the electrical efficiency of the electrochemical cell, in which the surface (surface) of the cathode include a metal rhodium, unexpectedly higher than the efficiency of other cells containing the cathode, the surface of which includes, for example, platinum or Nickel.

For example, it was found that in conventional bipolar cell in which the cathode and the anode is made of titanium, coated with a mixture of ruthenium dioxide and titanium dioxide, the electrical efficiency for the decomposition of nitrate ions in a solution of bicarbonate is about 40%, with one passing through the cell is restored about 12% of the nitrate ions. In the same cells with anodes and cathodes, made of Nickel, the electrical efficiency is about 35%. However, if the cell contains an anode made of titanium, coated with a mixture dioxide ruten the I and titanium dioxide, and the cathode is made of titanium, which galvanised coated with rhodium, the electrical efficiency is about 49%, with one passing through the cell is restored to about 24% of the nitrate ions. The exact values will, of course, depend on the cell size and mode of operation.

The method which is the subject of the present invention, can be used to remove, either wholly or partly, the nitrate ions from any aqueous solution that contains them. However, it is preferable that the aqueous solution consisted of an aqueous solution used for the regeneration of ion exchange columns. Ion-exchange column could be used, for example, for water purification, in particular for the purification of ground water and surface water containing nitrate ions. The nitrate ions may be present in solution, purified by ion exchange column at a concentration of, for example, equal to from 15 to 1000 parts per million (ppm), preferably from 15 to 500 parts per million. Ground water or surface water that can be purified can then be used as drinking water. The maximum allowable level of nitrate in drinking water, as a rule, is limited in accordance with international standards to 50 parts per million (in the form of nitrates).

Aqueous solution, with whom containing a series of nitrate ions cleared in the electrochemical cell may also contain additional anions, such as hydroxide ions, bicarbonate ions and chloride ions. This solution can also contain cations such as the cations of hydrogen, sodium or potassium. The electrochemical cell itself is well known and described, for example, in U.S. patent US-A-3542657. However, it is essential that the surface (surface) of the cathode include a metal rhodium.

The cathode, for example, may simply consist of metallic rhodium, although it is expensive. Thus, it is preferable to cover the base of a cathode metal rhodium, for example, electrolytic.

It is desirable that the thickness of the coating left from 0.1 to 0.75 μm, for example, from 0.5 to 0.75 microns.

The cathode substrate may, for example, include a metal, such as titanium. It may also include an intermediate covering layer under the coating of metallic rhodium, for example, in order to facilitate coating of rhodium to reduce the use of rhodium, given its high cost. Thus, for example, the substrate of the cathode may include titanium or titanium coated with titanium dioxide, ruthenium dioxide, iridium dioxide and/or gold. Commercially available is a variety of substrates cathode.

The anode can be used by any suitably the anode. Suitable anodes are known to specialists in this field of technology. The surface of the anode can be coated with metals or metal oxides, which contribute to the predominance of education chlorine compared with oxygen. Thus, for example, the anode may include such metal, such as titanium, optionally coated with metal or metal oxide. Examples of metal oxides are titanium dioxide, ruthenium dioxide, oxides of platinum and iridium and mixed oxides of these metals. Mainly, the surface of the anode does not include metallic rhodium in order to avoid unwanted reverse reactions.

In bipolar configuration of the cell, one side of the intermediate electrode functions as a cathode, while the other side functions as the anode. In this case, the cathode side cover metal rhodium.

It is desirable that all of the cathode surface in the electrochemical cell consisted of metallic rhodium. However, this is not the essential feature, and you want only some of the surfaces included metal rhodium. Preferably, at least 75% of the surface of the cathode, and preferably 100% of the surface of the cathode consisted of metallic rhodium in the composition of its surface. It is desirable that the whole surface of the cathode included use the th rhodium.

The electrochemical cell accordingly operates preferably at elevated temperature, i.e. at temperatures above room temperature (20°). For example, the cell can operate at a temperature at least equal to 60°C, preferably from 60 to 70°more preferably, at a temperature of approximately 65°C. the Authors of the present invention have discovered that the efficiency of recovery of nitrate ions to nitrogen gas increases with increasing temperature. In order to ensure heating of the aqueous solution flowing in the electrochemical cell, can be used with suitable heat exchange means, use warm water solution exiting the electrochemical cell.

The decomposition of the nitrate ions in the electrochemical cell obeys the formula described in U.S. patent US-A-3541657. Thus, the decomposition of the nitrate ions in the electrochemical cell is in equilibrium with the formation of the hydroxide ion. If the aqueous solution exiting the electrochemical cell used for any other purpose, the solution can be further processed to remove hydroxide ions, if necessary, for example, by adding acid, such as hydrochloric acid, to neutralize the hydroxide ions.

Preferably, th is would be the way to remove nitrate ions according to the present invention was used for the removal and destruction of nitrate ions, contained in the solutions obtained during the regeneration of ion exchange columns. Ion-exchange column itself could be used to remove nitrate ions from water, for example, from groundwater or from surface water.

Thus, the present invention enables to carry out the method of removal and destruction of nitrate ions contained in water, which includes:

(i) passing water through ion-exchange column (a)containing selective in relation to the nitrate anion exchange resin to exchange the nitrate ions to bicarbonate and/or chloride ions; and

(ii) the destruction of nitrate ions and regeneration of ion exchange columns (a) through:

a) removal from ion-exchange columns (a) any cations that form insoluble hydroxides or carbonates;

(b) passing an aqueous solution containing bicarbonate and/or chloride ions through the ion exchange column (a) for the exchange of nitrate ions to bicarbonate and/or chloride ions;

c) passing the solution obtained in stage b), through the electrochemical cell for the conversion of nitrate ions in hydrogen gas using the methods defined above;

d) update the solution obtained in stage (C), by adding to it the bicarbonate and/or chloride ions; and

e) return the solution obtained in stage (d)to the step (b).

Water is passed through inoome the percent column (a) for the exchange of nitrate ions to bicarbonate and/or chloride ions. Water, of course, may be subjected to pre-or post-processing, if there are other impurities, such as organic products.

When water is passed through an ion exchange column (a), nitrate ions contained in the water are replaced by bicarbonate and/or chloride ions and anion-exchange resin charged nitrate ions. Anion-exchange resin is a selective towards nitrate resin, which is used to exchange the nitrate ions to bicarbonate or chloride ions. Examples of suitable resins are the resins Purolite F 520E supplied by the company Puro-lite Internatuonal Limited and resin NR supplied by the company Rohm & Haas Limited.

In the end, the ion exchange resin becomes fully saturated nitrate ions. At this point, the nitrate ions must be removed from the anion-exchange columns (a) and destroyed, and the ion exchange resin is regenerated so that the anion-exchange column (a) could be used again in the process.

At the initial stage of any cations that form insoluble hydroxides or carbonates, must be removed from the ion exchange column (a). This is, mainly, Mg2+and CA2+. The cations can be removed by any suitable method. However, it is preferable that they were simply expelled by passing softened water through the ion exchange column (a).

An aqueous solution containing bicarbonate and/or chloride ions, and then passed through an ion exchange column (a) for the exchange of nitrate ions to bicarbonate and/or chloride ions. A suitable solution containing bicarbonate ions is a solution containing sodium bicarbonate or potassium. A suitable solution containing chloride ions is a solution containing sodium chloride or potassium hydroxide or hydrochloric acid. It is desirable that the solution contained either the chloride or the chloride and bicarbonate ions.

A solution containing bicarbonate ions, typically contains up to 1 M bicarbonate ions, preferably from 0.75 to 0.9 M bicarbonate ions. The solution containing chloride ions, typically contains up to 2 M chloride ions, preferably, from 1 to 2 M of the chloride ions. In those cases, when it is used as the chloride and bicarbonate ions, the solution typically contains up to 1 M, preferably from 0.75 to 0.9 M bicarbonate ions and up to 2 M, preferably, from 0.3 M to 2 M chloride ions.

After the aqueous solution was passed through an ion-exchange column (a), it contains nitrate ions, as well as either one of two things, or both, bicarbonate and chloride ions.

Then the solution passes through the electrochemical cell for the conversion of the nitrogen ions in the nitrogen gas in accordance with the method according to the present invented the Yu, determined above.

The solution emerging from the electrochemical cell is put back into the ion exchange column (a). However, it is necessary to replenish the solution by adding to it the bicarbonate and/or chloride ions. In order to Supplement the amount of bicarbonate ions, may be added an additional amount of sodium bicarbonate or potassium bicarbonate. However, this is not preferred, since it makes the increase in the number of hydroxide ions in the regenerant solution, which leads to an increase of the content of hydroxides such as calcium hydroxide and magnesium hydroxide which precipitates in normal water treatment. Therefore, more desirable to barbthroat through a solution of gaseous carbon dioxide to convert the hydroxide ions formed as a byproduct in the recovery of nitrate-ions, bicarbonate ions. To replenish the amount of chloride ions, as a rule, it is advisable to simply add sodium chloride or potassium or chlorostoma-burly acid.

As soon as the anion exchange resin regenerated, ion-exchange column (a) can again be used to remove nitrate ions from water containing nitrate ions. Thus, stage (i) and (ii) can be, if desired, be repeated at least once. Definitely on the right is the tick method can be implemented repeatedly again and again many times.

Water treated by ion-exchange column may contain impurities other than nitrate ions. In order to ensure that these anions will not affect adversely on the implementation of the method which is the subject of the present invention, the anion exchange resin is a selective relative to nitrate-anion ion-exchange resin, such that it preferably exchanges in water nitrate ions, in comparison with other anions, such as sulfate and phosphate.

The method according to the present invention can thus be carried out for water purification, which also contains other anions. So, for example, especially in cases when the water contains sulphate, chloride or phosphate ions, the method may further include: (i) the transmission of the stream exiting the ion exchange columns (a) through ionoobmennoi column (b)containing an ion-exchange resin to exchange any nitrate ions contained in the outgoing flow of the bicarbonate and/or chloride ions as long as the concentration of nitrate in the stream exiting the ion exchange column (a) essentially becomes equal to the concentration of nitrate in the stream, the incoming in ion-exchange column (a); (ii) the elimination of the transmission of water through the ion exchange column (a) by passing water straight through the column (b).

The concentration of nitrates mo what should be measured continuously or intermittently by any of the methods known from the prior art.

The above-described embodiment of the invention provides continuous purification of water. Thus, the removal of nitrate ions and, consequently, purification of water flow should not cease at that time, when regenerate one ion exchange column. It is desirable that the ion-exchange column (a) was recovered, and the stream exiting the ion exchange columns (b) at this time, perhaps, would pass through another ion-exchange column. It can be regenerated ion-exchange column (a).

Another possibility is to have more ion exchange columns. If the total number of columns is n, the water at some point in time, usually only goes through n-1 columns. Thus, for example, can be used 3 or 4 ion-exchange columns, but the water at some point in time will only pass through 2 or 3 columns of these columns. The remaining column will be outside the loop water purification and subjected to regeneration. Thus, if you use 3 columns, snapshot pictures you would see 2 columns, purifying water separately, in parallel, and the third column, which is on the regeneration or in reserve (i.e. one that is ready for subsequent use after using one of the other columns).

Thus, according to one of izsposobov implementation of the present invention, initially, the water passes through the ion exchange column (a) up until the nitrate content, will not increase, indicating leakage. Then to ion exchange column (a) connect the ion-exchange column (b) (or it can be connected in series in advance) and pass water through both columns, until then, until it becomes evident that the content of nitrates in the water stream leaving the column (a) essentially becomes the same as the content of nitrate ions in the flow of water to the ion exchange column (a), indicating the maximum absorption of nitrates in column (a). After that, water is passed only through the column (b), and column (a) regenerate. After ion-exchange column (a) recycled water continues to pass through the ion exchange column (b), until then, until it becomes evident that the content of nitrates in the water stream leaving the column increases, indicating leakage. Then connected in series to the ion-exchange column (b) ion exchange column (a) (or other ion-exchange column (C), if the ion-exchange column (a), for example, regenerated, and pass water through both columns, until then, until it becomes evident that the content of nitrates in the water stream emerging from the ion exchange columns (b) essentially becomes the same as the content of nitrate ions in p is the current of water, coming in ion-exchange column (b), indicating the maximum absorption of nitrates in column (b). After that, water is passed only through the ion exchange column (a) (or through ion-exchange column (C)), and ion-exchange column (b) regenerate.

Of course, this embodiment of the invention can be modified so that, if desired, water in ion exchange columns cease feeding before reached their maximum capacity. This order can be modified by a parallel connection of a larger number of columns. Typically use three or four ion exchange columns under cyclic ring system.

Further, the present invention is described by way of providing examples and comparative examples.

Examples

In all following examples elemental bipolar cell made from plastic sheet and has internal dimensions: 19.5 cm (length), 9 cm (width), 12 cm (height). The working volume, i.e. the volume of liquid is 1.5 litres.

Cell provided with an electrode at both ends and connected to the constant current source. Between the end electrodes may be additionally connected to 24 intermediate electrode size 9.1 cm (width) and 11.5 cm (height) with a small grooves with the depth of 0.2 cm on one side only by installing the connectors on boscovichian cells. The electrodes are placed in such a way that the grooves located opposite each other at the adjacent electrodes, provide the tortuosity of the flow through cell. Direct connection of electricity to the electrodes do not produce.

The cell is equipped with a cover and operates at a constant volume of liquid in the periodic release of gas generated at the electrodes through the gas valve. It is directly connected to a float switch that allows automatic control of liquid level. The liquid level is set below the top of the intermediate electrodes, so that approximately 10 cm of each of the electrodes immersed in the liquid. The liquid in the cell served by the pump through a plastic tube at one end of the cell and out through a plastic tube at the opposite end of the cell. The exiting liquid stream passes through a heat exchanger to transfer residual heat to the incoming fluid. The incoming fluid also passes through the second heat exchanger so that the temperature at the inlet of the cell could be monitored.

Example 1

The cell is equipped with 24 commercially available electrodes in the form of plates with a thickness of 1.2 mm of pure Nickel, a cathode whose surface is electrochemically coated metal rhodium plated, with a thickness of 0.5 µm. At the electrode-to the TOD similarly coated with rhodium. The incoming fluid is water containing 32 g/l NaOH, when the nitrate content in the solution is equal to 11 600 parts per million (ppm), in the form of sodium nitrate. The flow rate is 1 l/h, the internal temperature is maintained 75°C. At a constant current of 1 a (equivalent to a current density of 11 mA/cm2) nitrate is reduced to 9 500 ppm in a single pass through the cell. The electrical efficiency is about 37%, with the cost of electricity, equal to approximately 7.4 watt-hours/g restored nitrate.

Comparative example 1

The same cell is equipped with 10 electrodes in the form of titanium plates with the thickness of 1.2 mm, both surfaces of which are coated with mixed oxides of titanium and ruthenium with a thickness of 2 μm. Extreme electrodes are also a titanium plate having a coating of mixed oxides of titanium and ruthenium with a thickness of 2 μm. The incoming fluid is water containing 63 g/l sodium bicarbonate, nitrate content in the solution is equal to 8 900 parts per million, in the form of sodium nitrate. A flow rate of 1.5 l/h, the internal temperature is maintained 75°C. At a constant current of 0.8 A (equivalent to a current density of 9 mA/cm2) nitrate is reduced to 7 800 ppm in a single pass through the cell. E is tricocci efficiency is about 40%, with the cost of electricity, equal to about 9 watt-hrs/g restored nitrate.

Example 2

The same cell is equipped with 10 electrodes in the form of titanium plates with the thickness of 1.2 mm, the anode surface of which is coated with mixed oxides of titanium and ruthenium with a thickness of 2 μm, and the cathode whose surface is covered with metal rhodium plated, with a thickness of 0.5 µm. Extreme electrodes are also titanium plate anode surface which has a coating of mixed oxides of titanium and ruthenium with a thickness of 2 μm, and the cathode surface which has a coating of metallic rhodium, with a coating thickness of 0.5 μm. The incoming fluid is water containing 63 g/l sodium bicarbonate with nitrate content in the solution is equal to 8 800 parts per million, in the form of sodium nitrate. A flow rate of 1.5 l/h, the internal temperature is maintained 75°C. At a constant current of 1.3 A (equivalent to a current density of 14.5 mA/cm2) nitrate is reduced to 6 650 ppm in a single pass through the cell. The electrical efficiency is about 49%, with the cost of electricity, equal to about 8.4 watt-hrs/g restored nitrate.

Example 3

High performance rhodium-plated at the cathode compared to platinum on the freight shown by voltametric experiment.

Polypropylene cups filled with an aqueous solution containing 120 g/l NaOH, with the addition, as shown below, sodium nitrate and sodium nitrite. The cathodes consisting of a wire diameter of 1 mm, immersed to the same depth, while receiving the same surface area in each of the experiments. The anode is made of platinum. The temperature is maintained constant. The potential difference is changed from (platinum) +0.45 In (all voltages are relative to SCE) and (rhodium) from-0.2 V to -1,1 V At the scan rate 50 mV·-1.

As for platinum and rhodium cathode in the absence of nitrate regular schedule type “butterfly”associated with adsorption and desorption of hydrogen is observed at ~of-0.9 V, and the release of gaseous hydrogen begins at ~-1,1 Century Significant differences between rhodium and platinum was not.

Add 51 g/l sodium nitrate to 120 g/l of sodium hydroxide and repeat the experiments described above.

In the case of the platinum cathode maximum power of 4.5 And was observed at -0,87 In case of a negative scan potential, indicating that the adsorption of nitrate. This peak was not observed during the positive scan potential, indicating that the effect on the adsorption of nitrate by the desorption of hydrogen. In addition, the width of the peak at a current of 2 mA, with a negative scan potential is and was 0.1 Century

In the case of rhodium cathode similar peak current is observed at negative scanning capabilities and a smaller maximum (2.5 mA) is observed in the positive sweep potential. The width of the peak at a current of 2 mA was 0.2 In the case of a negative scan potential and 0.1 In the positive scan capabilities.

This shows that the adsorption of nitrate on radii unexpectedly desorption of hydrogen has little effect, and suggests that the rhodium is preferably platinum in the reduction of nitrate.

Add to 41.4 g/l of sodium nitrite to 120 g/l of sodium hydroxide and again repeat the above experiments.

In the case of the platinum cathode maximum current of 4.5 mA is observed when -0,92 a negative scan potential, indicating that the adsorption of nitrite, and there is a slightly lower maximum positive scan potential, which indicates a lack of significant effect desorption of hydrogen on the adsorption of nitrite.

In the case of rhodium cathode peak current is outside the field of measuring instruments used. The concentration of nitrite is reduced to 0.23 g/l, while the maximum current is in the field of measuring instruments used. When this concentration is observed a maximum current of 5.5 mA, the shape of the peak of the testimony of the t on the limitation of mass transfer in relation to adsorption of nitrite. This shows that rhodium is again significantly preferred platinum for recovery of nitrite.

As is known, the reduction of nitrate with the formation of gaseous nitrogen flows through the formation of nitrite. Formed intermediate product, nitrite, ammonium, which decomposes when heated. In addition, the above experiments indicate that the coefficient in the case when using rhodium cathode, unexpectedly higher than in the case of the platinum cathode. In addition, these results show that the formation of nitrite is reduced to a minimum, because nitrite is easily restored to ammonium ion. It is an advantage of the methods of water purification, in cases where there are stringent limits on the amount of nitrates.

1. Method of removing nitrate ions from aqueous solutions that contain them, including passing the solution through an electrolytic cell containing at least one anode and at least one cathode, and passing an electric current between them, in which the surface (surface) of the cathode is covered with a layer consisting of metallic rhodium.

2. The method according to claim 1, in which the cathode (the cathode) comprises a metal coated with a metal rhodium.

3. The method according to claim 2, in which the cathode (the cathode) comprises titanium or titanium coated with dioxi the Ohm titanium and/or ruthenium dioxide, coated metal rhodium.

4. The method according to any of the preceding paragraphs, in which the anode (the anode) comprises titanium coated with platinum, ruthenium or iridium, or oxides of platinum or iridium, or mixed oxides of these metals.

5. The method according to any of the preceding paragraphs, in which the electrochemical cell operates at a temperature at least equal to 60°C.

6. The method according to any of the preceding paragraphs, in which the solution is obtained by regeneration of ion exchange columns.

7. The method of removal and destruction of nitrate ions contained in water, comprising (i) passing water through ion-exchange column (a)containing selective in relation to the nitrate anion exchange resin to exchange the nitrate ions to bicarbonate and/or chloride ions, and

(ii) the destruction of nitrate ions and regeneration of ion exchange columns (a) through

a) removal from ion-exchange columns (a) any cations that form insoluble hydroxides or carbonates,

(b) passing an aqueous solution containing bicarbonate and/or chloride ions through the ion exchange column (a) for the exchange of nitrate ions to bicarbonate and/or chloride ions

c) passing the solution obtained in stage b), through the electrochemical cell for the conversion of nitrate ions to nitrogen gas using the method according to any one of claims 1 to 5,/p>

d) update the solution obtained in stage (C) by adding thereto the bicarbonate and/or chloride ions, and

e) returning the solution obtained in stage (d)to the step (b).

8. The method according to claim 7, in which the solution obtained in stage (C), update by ozonation through a solution of carbon dioxide gas to convert the hydroxide ions formed as a side product during the recovery of nitrate ions, bicarbonate ions.

9. The method according to claim 7 or 8, in which the solution obtained in stage (C), update by adding sodium chloride or potassium hydroxide or hydrochloric acid.

10. The method according to any of claims 7 to 9, in which the solution emerging from the electrochemical cell, return to the ion exchange column (a) until such time as all of the nitrate ions is not exchanged for bicarbonate and/or chloride ions.

11. The method according to any of claims 7 to 10, in which a solution containing bicarbonate ions is a solution containing sodium bicarbonate or potassium.

12. The method according to any of claims 7 to 11, in which the solution containing chloride ions is a solution of chloride of sodium or of potassium.

13. The method according to any of claims 7 to 12, in which a solution containing bicarbonate and/or chloride ions, contains up to 1 M bicarbonate ions and/or up to 2 M chloride ions.

14. The method according to item 13, in which the solution contains up to 1 M bicarbonate ions or up to 0.6 M of the chloride ions.

15. The method according to any of claims 7 to 14, in which water is passed through ion-exchange column (a)represents the ground water or surface water containing waste.

16. The method according to any of claims 7 to 15, in which water is passed through ion-exchange column (a), also contain other anions, including additional

(i) passing a stream emerging from the ion exchange columns (a)through ion-exchange column (b)containing an ion-exchange resin to exchange any nitrate ions contained in the output flow of the bicarbonate and/or chloride ions to the moment when the concentration of nitrate ions in the stream exiting the ion exchange column (a), in essence, becomes equal to the concentration of nitrate ions in the stream included in the ion exchange column (a),

(ii) eliminate the passage of water through ionoobmennoi column (a) by passing water immediately after ion-exchange column (b).

17. The method according to clause 16, which regenerate the ion exchange column (a) and the stream exiting the ion exchange columns (b), is passed through the regenerated ion-exchange column (a).

18. An electrochemical cell containing at least one anode and at least one cathode, in which the surface (surface) of the cathode is covered with a layer, which consists of a metal rhodium, for the conversion of nitrate ions contained in the water is aStore, in nitrogen gas.



 

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1 dwg

FIELD: devices for purification of household and industrial sewage.

SUBSTANCE: the invention is dealt with devices for purification of household and industrial sewage and intended for electrical and cavitational treatment of sewage containing a large quantity of organic compounds. The device for purification of sewage consists of a body made out of a dielectric material partitioned by diaphragms for two electrode chambers and one working chamber, that contains a filtering material. The electrode chambers have cavitational field sources installed and the working chamber is supplied with a the bubbler installed in it. The technical result consists in an increase of recuperation of the filtering material at the expense of application of a cavitational field to it, decrease of the microbiological semination, and an increase of cavitational effect on particles.

EFFECT: the invention ensures an increase of the filtering material recuperation, decreased microbiological semination and increased the cavitational effect on particles.

1 dwg

FIELD: devices for purification of household and industrial sewage.

SUBSTANCE: the invention is dealt with devices for purification of household and industrial sewage and intended for electrical and cavitational treatment of sewage containing a large quantity of organic compounds. The device for purification of sewage consists of a body made out of a dielectric material partitioned by diaphragms for two electrode chambers and one working chamber, that contains a filtering material. The electrode chambers have cavitational field sources installed and the working chamber is supplied with a the bubbler installed in it. The technical result consists in an increase of recuperation of the filtering material at the expense of application of a cavitational field to it, decrease of the microbiological semination, and an increase of cavitational effect on particles.

EFFECT: the invention ensures an increase of the filtering material recuperation, decreased microbiological semination and increased the cavitational effect on particles.

1 dwg

The invention relates to a structurally-modified water-soluble polymers that can be used for clarification of organic compounds obtained by polymerization in an aqueous solution of monomers

The invention relates to wastewater livestock complexes and can be used in agriculture for the preparation of liquid waste cattle-breeding complexes and farms for irrigation and fertilization of agricultural land

The invention relates to the field of power engineering and can be used in boilers and thermal power plants

The invention relates to the field of power engineering and can be used in boilers and thermal power plants

FIELD: petrochemical and food and other processing industries.

SUBSTANCE: the invention presents a device for purification of sewage and is dealt with designs of sewage treatment plants for purification and averaging of consumption and composition of sewage and may be used for preliminary purification of sewage of the enterprises of processing industries from floating and settling insoluble impurities. The device contains a cylindrical body with a cone-shaped bottomed, a mounted along the axis of the body cylindrical partition, a located above the body reactive water distributor with branch-pipes, a floating device, a rotating rocker arm with a foam pushing plates mounted with the help of a half-coupling to the reactive water distributor at a maximum level of water in the device, a collecting tank mounted with possibility of delivery in it of the circulating water, a pump, a pressure tank-saturator linked by a pressure pipeline with the reactive water distributor. Inside the body there is a ring-type chute, in which the reactive water distributor branch-pipes supplied with diffusers on their ends are placed. The technical result is an increase of efficiency of sewage purification and realization of averaging of consumption and composition of sewage and its purification simultaneously.

EFFECT: the invention ensures increased efficiency of sewage purification and simultaneous realization of averaging of sewage consumption, composition and purification.

1 dwg

FIELD: water-supply engineering.

SUBSTANCE: invention relates to methods of removing hardness salts from regenerates and can be used in water treatment processes in heat-and-power engineering, chemical, petrochemical, food, and other industries provided with ion-exchange water-desalting filters. Method is accomplished by precipitation of hardness salts involving recycle of precipitate treated by alkali solution followed by passage of supernatant through H-cationite filter. Treated precipitate accumulated in preceding settling cycles is recycled into regenerate and settling-subjected solution is passed through cationite filter to produce purified sulfuric acid further used for regeneration of H-cationite filters in water-treatment cycle. Precipitate is treated with alkaline regenerate from OH-anionite filters or with alkali solution obtained from electrolysis of regenerates with pH not below 11. Amount of regenerate introduced into accumulator-settler should be at least 20 kg/m3.

EFFECT: excluded liming procedure, preserved initial (after regeneration of filters) content of sulfate ions in sulfuric acid, reduced consumption thereof during preparation of regeneration solution, and excluded discharge of sulfate ions unto water objects.

3 cl, 2 ex

FIELD: food and pharmaceutical industries; water filtration.

SUBSTANCE: the invention presents a method of purification of liquids and is dealt with filtration, in particular with the methods of purification of liquids from impurities. It may be used in the systems of industrial and household water supply in food and pharmaceutical industries. The method of liquids purification includes a partial shutting off a trunk of the unpurified liquid, delivery of the unpurified liquid in a trunk of the unpurified liquid and to the filtration element - in a trunk of purified liquid. Before the unpurified liquid delivery into the trunks of the unpurified and purified liquids it is passing through an ejector. The technical result is an increased convenience in operation and productivity of purification due to simultaneous outflow of both purified and unpurified liquids without decrease of a flow area of the purified liquid trunk running cross-section.

EFFECT: the invention ensures an increase of convenience in operation and productivity of purification of liquids without decrease of a flow area of the purified liquid trunk running cross-section.

6 dwg

FIELD: devices for purification of household and industrial sewage.

SUBSTANCE: the invention is dealt with devices for purification of household and industrial sewage and intended for electrical and cavitational treatment of sewage containing a large quantity of organic compounds. The device for purification of sewage consists of a body made out of a dielectric material partitioned by diaphragms for two electrode chambers and one working chamber, that contains a filtering material. The electrode chambers have cavitational field sources installed and the working chamber is supplied with a the bubbler installed in it. The technical result consists in an increase of recuperation of the filtering material at the expense of application of a cavitational field to it, decrease of the microbiological semination, and an increase of cavitational effect on particles.

EFFECT: the invention ensures an increase of the filtering material recuperation, decreased microbiological semination and increased the cavitational effect on particles.

1 dwg

FIELD: devices for purification of household and industrial sewage.

SUBSTANCE: the invention is dealt with devices for purification of household and industrial sewage and intended for electrical and cavitational treatment of sewage containing a large quantity of organic compounds. The device for purification of sewage consists of a body made out of a dielectric material partitioned by diaphragms for two electrode chambers and one working chamber, that contains a filtering material. The electrode chambers have cavitational field sources installed and the working chamber is supplied with a the bubbler installed in it. The technical result consists in an increase of recuperation of the filtering material at the expense of application of a cavitational field to it, decrease of the microbiological semination, and an increase of cavitational effect on particles.

EFFECT: the invention ensures an increase of the filtering material recuperation, decreased microbiological semination and increased the cavitational effect on particles.

1 dwg

FIELD: devices for purification of household and industrial sewage.

SUBSTANCE: the invention is dealt with devices for purification of household and industrial sewage and intended for electrical and cavitational treatment of sewage containing a large quantity of organic compounds. The device for purification of sewage consists of a body made out of a dielectric material partitioned by diaphragms for two electrode chambers and one working chamber, that contains a filtering material. The electrode chambers have cavitational field sources installed and the working chamber is supplied with a the bubbler installed in it. The technical result consists in an increase of recuperation of the filtering material at the expense of application of a cavitational field to it, decrease of the microbiological semination, and an increase of cavitational effect on particles.

EFFECT: the invention ensures an increase of the filtering material recuperation, decreased microbiological semination and increased the cavitational effect on particles.

1 dwg

The invention relates to a structurally-modified water-soluble polymers that can be used for clarification of organic compounds obtained by polymerization in an aqueous solution of monomers

The invention relates to wastewater livestock complexes and can be used in agriculture for the preparation of liquid waste cattle-breeding complexes and farms for irrigation and fertilization of agricultural land

The invention relates to the field of power engineering and can be used in boilers and thermal power plants

The invention relates to the field of power engineering and can be used in boilers and thermal power plants

FIELD: petrochemical and food and other processing industries.

SUBSTANCE: the invention presents a device for purification of sewage and is dealt with designs of sewage treatment plants for purification and averaging of consumption and composition of sewage and may be used for preliminary purification of sewage of the enterprises of processing industries from floating and settling insoluble impurities. The device contains a cylindrical body with a cone-shaped bottomed, a mounted along the axis of the body cylindrical partition, a located above the body reactive water distributor with branch-pipes, a floating device, a rotating rocker arm with a foam pushing plates mounted with the help of a half-coupling to the reactive water distributor at a maximum level of water in the device, a collecting tank mounted with possibility of delivery in it of the circulating water, a pump, a pressure tank-saturator linked by a pressure pipeline with the reactive water distributor. Inside the body there is a ring-type chute, in which the reactive water distributor branch-pipes supplied with diffusers on their ends are placed. The technical result is an increase of efficiency of sewage purification and realization of averaging of consumption and composition of sewage and its purification simultaneously.

EFFECT: the invention ensures increased efficiency of sewage purification and simultaneous realization of averaging of sewage consumption, composition and purification.

1 dwg

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