Air treatment process using a compound of interest and implementation installation

Abstract

The invention relates to a method and installation for air treatment. It comprises the following steps: a) supplying air polluted by a chemical compound; b) injecting said polluted air and a first aqueous solution in a countercurrent flow; c) recovering air stripped of at least a portion of said chemical compound; d) injecting said air stripped of a portion of said chemical compound and a second aqueous solution in a countercurrent flow; e) exhausting purified air on one side and recovering said second aqueous solution and said other portion of said chemical compound on the other; and in step b), said first aqueous solution comprises said second aqueous solution and said other portion of said chemical compound, while in step c), recovering a third concentrated aqueous solution of said at least a portion and said other portion of said chemical compound. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: Method for treating air charged with a compound of interest and implementation installation

[0001] The present invention relates to a method for treating air charged with a compound of interest and to an installation enabling the implementation of said method.

[0002] Controlling the quality of air released in different industries is now a major issue for the preservation of the environment.

[0003] Therefore, it is necessary to identify the chemical compounds contained in the air released in each industrial process and to be able to trap them if they are likely to have an impact on the environment.

[0004] A large number of industries are therefore concerned. This is the case, for example, of poultry farmers who release air laden with ammonia or of oil refineries responsible for sulfur oxide emissions.

[0005] The retention of these chemical compounds related to pollutants results in additional costs for existing facilities. Moreover, when they have been captured before being released into the atmosphere, the chemical compounds must be stored and possibly recycled or inert.

[0006] Ammonia, for example, is a chemical compound with the formula NH3, and is gaseous under normal temperature and pressure conditions. It is dangerous at high concentrations and is itself a source of other pollutants.

[0007] With regard to sulfur oxides, the most stable are sulfur dioxide SO2 and sulfur trioxide SO3. These molecular chemical compounds are also atmospheric pollutants involved in particular in the phenomenon of acid rain.

[0008] Furthermore, it is known to use scrubber towers to treat polluted air. Polluted air and a reactive liquid are circulated counter-currently inside these towers. The objective is to release pollutant-free air into the atmosphere.

[0009] However, the implementation of these washing towers contributes to increasing the overall cost of polluting industrial processes.

[0010] Also, a problem which arises and which the present invention aims to solve is to provide a method to reduce the operating costs of these industrial processes, and also, an installation to implement this method.

[0011] In order to solve this problem, and according to a first objective, a method for treating air charged with a compound of interest is proposed, which method comprises the following steps:

[0012] - a) air is supplied polluted by a given chemical compound;

[0013] - b) said polluted air and a first aqueous solution are injected counter-currently of a solute suitable for causing the solubilization of at least a part of said given chemical compound in said first aqueous solution;

[0014] - c) air is recovered from said at least a part of said compound given chemical;

[0015] - d) said air removed from said a part of said compound is injected counter-currently given chemical compound and a second aqueous solution of said solute so as to cause the solubilization of the other part of said given chemical compound in said second aqueous solution;

[0016] - e) purified air removed from said other part of said compound is evacuated on one side given chemical compound, and on the other side we recover said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution;

[0017] and in step b), said first aqueous solution injected against said polluted air comprises said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution, while in step c), a third concentrated aqueous solution of said at least one part of said given chemical compound and of said other part of said given chemical compound is further recovered.

[0018] Thus, a feature of the invention lies, on the one hand, in the successive implementation of two exchange processes between the polluted air to be treated and two aqueous solutions of a solute capable of trapping the pollutant, and on the other hand, in the recovery of the second aqueous solution from the second exchange process to carry out the first exchange process. In this way, during the first exchange process, the given chemical compound is extracted from the polluted air by means of an aqueous solution already charged with this chemical compound thanks to the solute. Consequently, the resulting aqueous solution is further enriched with said chemical compound. Therefore, a highly concentrated aqueous solution of the given chemical compound is obtained, which can then be advantageously used and implemented in various industries, as will be explained below.Consequently, the given chemical compound, which is initially an undesirable, diffuse, and non-concentrated pollutant, becomes economically valuable after treatment. This also reduces the cost of implementing the treatment process.

[0019] The treatment process according to the invention has the double advantage of allowing, on the one hand, the release into the atmosphere of air free of pollutants, and on the other hand, of giving an economic value to the pollutants.

[0020] According to a particularly advantageous embodiment of the invention, in step d), said second aqueous solution of said solute comprises, said second aqueous solution and the other portion of the given chemical compound solubilized in the second aqueous solution, recovered in step e). In other words, a portion of the second aqueous solution and the other portion of the given chemical compound recovered in step e) are reinjected counter-currently through the air from which a portion of the given chemical compound has been removed. In this way, the remaining portion of the compound of interest in the polluted air is captured, and the aqueous solution of the given chemical compound of interest is further enriched.

[0021] Furthermore, preferably in step d), an original aqueous solution of said solute alone is co-injected with said second aqueous solution and said other portion of said given chemical compound solubilized in said second aqueous solution, recovered in step e). In this way, the aqueous solution of said solute is enriched in the second exchange process, to promote the solubilization of the compound of interest. The purification of the polluted air is then completed with an aqueous solution containing only the solute.

[0022] Furthermore, according to a particularly advantageous embodiment of the invention, at least a portion of said third concentrated aqueous solution of said at least a portion of said given chemical compound and of said other portion of said given chemical compound is transformed into a solid phase. Thus, the third aqueous solution is supersaturated with the given chemical compound and tends to partially transform to form crystals. Consequently, the chemical compound is obtained in solid form. It is then inherently more concentrated and more easily transported. And it is even more readily usable in various industries, as will be explained below.

[0023] According to a first particularly advantageous embodiment of the invention, in step a) said chemical compound given is ammonia of formula NH3. Its molecule includes the nitrogen atom N which can be of great interest in industry, and in the form of fertilizers, in particular for the fertilization of crops.

[0024] According to the invention, and in accordance with the first embodiment, in step b) said solute is advantageously a strong acid. In this way, ammonia in gaseous form in air reacts naturally with the strong acid in aqueous solution.

[0025] According to a first embodiment, in step b) said solute is sulfuric acid of formula H2SO4. In other words, ammonia in gaseous form in air is suitable for being solubilized in an aqueous solution of sulfuric acid to form ammonium sulfate of chemical formula (NH4)2SO4.

[0026] Thus, thanks to the process according to the invention, a third aqueous solution highly concentrated in ammonium sulfate is obtained, at least a portion of which can crystallize. In this way, the ammonium sulfate in solid form can be directly used to fertilize crops and supply nitrogen to plants. It will be noted that the only The third aqueous solution can also be spread on soils in its liquid form to fertilize them.

[0027] According to a second embodiment, in step b) the solute is orthophosphoric acid with the formula H3PO4. Consequently, ammonia in gaseous form in the air is able to be solubilized in an aqueous solution of orthophosphoric acid to form ammonium phosphate with the chemical formula (NH4)3PO4. Here too, thanks to the process according to the invention, a third highly concentrated aqueous solution of ammonium phosphate is obtained, and a portion of it is obtained in crystalline form. It is then in a form that makes it easier to fertilize crops. Indeed, phosphorus is also an essential mineral element for plant growth and development.

[0028] According to a third embodiment, in step b) the solute is nitric acid with the formula HNO3. In this way, ammonia in gaseous form in the air can be dissolved in an aqueous solution of nitric acid to form ammonium nitrate with the chemical formula NH4NO3. By means of the process according to the invention, a highly concentrated aqueous solution of ammonium nitrate is then obtained, and a portion can be obtained in solid form. Ammonium nitrate is widely used as a chemical mineral fertilizer. It can also be used in other industries, for example, in the manufacture of explosive devices.

[0029] According to a second, particularly advantageous embodiment of the invention, in step a) said chemical compound is a sulfur oxide. The given chemical compound is, for example, sulfur dioxide SO2, or sulfur trioxide SO3.

[0030] According to the invention, and in accordance with the second embodiment, in step b) said solute is advantageously a strong base. In this way, sulfur oxide in gaseous form in air reacts naturally with a strong base in an aqueous solution.

[0031] According to one embodiment, in step b) said solute is potassium hydroxide KOH. In other words, sulfur oxide in gaseous form in air is suitable for being solubilized in an aqueous solution of potassium hydroxide to form potassium sulfate of chemical formula K2SO4.

[0032] Thus, thanks to the process according to the invention, a third aqueous solution highly concentrated in potassium sulfate is obtained, at least a portion of which can crystallize. In this way, the potassium sulfate in solid form can be directly used to fertilize crops and provide potassium and sulfur to plants. It will be noted that the only third aqueous solution can also be spread on the soil in its liquid form in order to enrich it.

[0033] According to a second object, an air treatment system charged with a compound of interest is proposed in accordance with the invention. This treatment system enables the implementation of the process described above. It comprises:

[0034] - a first scrubbing tower for injecting, in a counter-current flow, air polluted by a given chemical compound and a first aqueous solution of a solute suitable to cause the solubilization of at least a part of said given chemical compound in said first aqueous solution, said first washing tower comprising a first upper outlet to recover air removed from said at least a part of said given chemical compound;

[0035] - a second washing tower connected to said first washing tower by said first upper outlet to inject counter-currently into said second washing tower said air removed from said a part of said given chemical compound and a second aqueous solution of said solute so as to cause the solubilization of the other part of said given chemical compound in said second aqueous solution, said second washing tower comprising a second upper outlet to evacuate on one side purified air removed from said other part of said given chemical compound, and a second lower outlet to recover on the other side said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution;

[0036] and in that said second lower outlet is connected to said first scrubbing tower so that said first aqueous solution injected counter-currently to said polluted air comprises said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution, while said first scrubbing tower comprises a first lower outlet for further recovering a third concentrated aqueous solution of said at least a part of said given chemical compound and of said other part of said given chemical compound.

[0037] Thus, by implementing two washing towers in series connected to each other, the process of treating air charged with a compound of interest is implemented in order to obtain an aqueous solution very rich in the given chemical compound of interest.

[0038] Furthermore, according to the invention, the installation includes a receptacle connected to said first lower outlet for transforming into solid phase at least a part of said third concentrated aqueous solution of said at least a part of said given chemical compound and of said other part of said given chemical compound.

[0039] As will be explained in more detail in the detailed description that follows, the receptacle can take the form of a crystallizing dish allowing the crystallization of the given chemical compound to occur.

[0040] Other features and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:

[0041] [Fig-1] is a schematic view of an air handling installation conforming to the invention operating according to a first embodiment; and,

[0042] [Fig.2] is a schematic view of an air handling installation conforming to the invention operating according to a second embodiment variant.

[0043] The installation according to the invention, which will be described in detail below in two embodiments, employs scrubbing towers. A scrubbing tower is a device for treating gases in general. A gas is circulated counter-currently through a liquid reagent dispersed in fine droplets. The finer the droplets, the greater the surface area of ​​exchange with the gas. This is the desired effect, enabling the transfer of one or more chemical compounds contained within the gas into the liquid reagent with greater efficiency.

[0044] Thus, according to a first embodiment as illustrated in [Fig. 1], a first washing tower 10 and a second washing tower 12 are provided, connected in series as will be explained below. The first washing tower 10 has a first lower end 14 and, opposite it, a first upper end 16, while the second washing tower 12 has a second lower end 18 opposite a second upper end 20.

[0045] Also, the first washing tower 10 has a first first inlet 22 of polluted air, while the second washing tower 12 has a first second inlet 24 of polluted air.

[0046] According to the first embodiment presented here, the polluted air is charged with ammonia (NH3). In this case, the average flow rate of the polluted air at the first inlet 22 is adjusted to obtain an upward velocity of the polluted air inside the tower of between 0.5 and 1.5 m / s. For example, it is 1.2 m / s. As for the ammonia concentration, it is, for example, 50 ppm, or 50 parts per million. It can be lower, but also much higher.

[0047] Furthermore, the first washing tower 10 has a second first inlet 26 of a first aqueous solution of a solute, here sulfuric acid H2SO4. The characteristics of this first aqueous solution of strong acid will be specified in more detail below.

[0048] This second first inlet 26 is connected to a first plurality of spray booms not shown, distributed on different floors inside the first tower Washing point 10. In this way, the first aqueous solution is sprayed as fine droplets from the first upper end 16 to the first lower end 14, while the polluted air laden with ammonia is injected counter-currently from the first lower end 14 to the first upper end 16. This causes the trapping and solubilization of at least some of the ammonia in the first aqueous solution. It should be noted that the portion of ammonia solubilized during this first exchange is substantial. For example, it corresponds to more than three-quarters of the ammonia contained in the polluted air injected at the first inlet 22.

[0049] Ammonia then reacts in water with sulfuric acid to form ammonium sulfate with the chemical formula (NH4)2SO4. As a result, the first aqueous solution is then concentrated in ammonia in the form of ammonium sulfate and it flows towards the first lower end 14 as will be explained below.

[0050] Conversely, in the first upper end 16, the first washing tower 10 includes a first upper outlet 28 allowing the recovery of polluted air freed from at least part of its ammonia.

[0051] This first first outlet 28 is directly connected to the first second inlet 24 of polluted air from the second washing tower 12.

[0052] In addition, the second washing tower 12 has a second inlet 30 of a second aqueous solution of sulfuric acid H2SO4. The characteristics of this second aqueous acidic solution will be specified below.

[0053] The second inlet 30, like the first scrubber tower 10, is connected to a second plurality of spray booms (not shown), arranged in tiers inside the second scrubber tower 12. In this way, the second aqueous solution is sprayed as fine droplets from the second upper end 20 to the second lower end 18, while polluted air, laden with at least some of the additional ammonia remaining after passing through the first scrubber tower 10, is injected counter-currently from the second lower end 18 to the second upper end 20. This causes the additional ammonia to dissolve in the second aqueous solution. It will be observed that almost all of the additional ammonia is dissolved during this second exchange.

[0054] As mentioned above with regard to the first washing tower 10, ammonia reacts in water with sulfuric acid to form ammonium sulfate with the chemical formula (NH4)2SO4.

[0055] The second aqueous solution is also enriched with ammonia in the form of ammonium sulfate and is conveyed to the second lower end 18.

[0056] Conversely, the polluted air after this double exchange with an acidic aqueous solution leads to purified air which then escapes from the second upper end 20 through a first second outlet 32. This air, free of the chemical compound ammonia NH3, can then be released into the atmosphere without danger.

[0057] It will be noted that traces of ammonia may nevertheless remain in this released air. But this is harmless to the environment.

[0058] Conversely, and according to a preferred embodiment, an original aqueous solution of sulfuric acid alone is injected at the second upper end 20 of the second tower 12, through a third inlet 34. This aqueous solution of sulfuric acid has, for example, a concentration of one mole per liter. In certain circumstances, the concentration may be higher.

[0059] Advantageously, the original aqueous solution is co-injected with the second aqueous sulfuric acid solution through the second plurality of spray ramps.

[0060] The second aqueous solution enriched in ammonium sulfate of chemical formula (NH4)2SO4 is thus recovered by gravity in the second lower end 18 of the second washing tower 12.

[0061] The second lower end 18 of the second washing tower 12 has a second outlet 36 connected to the second inlet 30 and a third outlet 38 connected to the second first inlet 26 of the first washing tower 10. In other words, a first fraction of this second acidic aqueous solution containing ammonium sulfate is reinjected into said second washing tower 12 through the second inlet 30, so as to complete the purification of the polluted air, while a second fraction of this second acidic aqueous solution is injected into the first washing tower 10 through the second first inlet 26 in order to remove a substantial part of the ammonia contained in the polluted air and injected through the first inlet 22 of the first washing tower 10.

[0062] In other words, according to an upstream-downstream flow, the polluted air tends to become depleted of ammonia as it escapes from the installation. And according to a reverse downstream-upstream flow, the sulfuric acid solution tends to become enriched in ammonium sulfate (NH4)2SO4. Thus, a third aqueous solution supersaturated with ammonium sulfate is found in the first lower end 14 of the first scrubber tower 10.

[0063] The first lower end 14 of the first washing tower 10 has a second first outlet 40 allowing the third supersaturated aqueous solution to be conveyed into a receptacle 42, in order to be transformed into a solid phase at least a portion of the ammonium sulfate (NH4)2SO4 from the third supersaturated aqueous solution.

[0064] The receptacle 42, for example a crystallizer, has a receptacle outlet 44 connected to the first upper end 16 of the first washing tower 10 by a third first inlet 46. This third first inlet 46 is connected to the first plurality of ramps like the second first inlet 26. It thus allows the liquid part of the third supersaturated aqueous solution to be recycled and further enriched in ammonium sulfate.

[0065] In this way, the ammonium sulfate is recovered in solid form in the receptacle 42 so that it can be conditioned and used as fertilizer for example.

[0066] It will be noted that this third aqueous solution supersaturated with ammonium sulfate can also be conditioned and used in liquid form as a fertilizer.

[0067] The installation described above is intended to operate in a continuous mode where the inputs consist of air charged with ammonia and the original sulfuric acid solution, while the outputs consist of ammonium sulfate in solid and / or liquid form, and purified air.

[0068] The object of the invention relates not only to the installation, but also to the process which it enables to be implemented.

[0069] According to a second embodiment as illustrated in [Fig. 2], a first washing tower 10' and a second washing tower 12' are provided, connected in series as will be explained below. The first washing tower 10' has a first lower end 14' and, opposite it, a first upper end 16', while the second washing tower 12' has a second lower end 18' opposite a second upper end 20'.

[0070] Also, the first washing tower 10 has a first inlet 22' of polluted air, while the second washing tower 12 has a first inlet 24' of polluted air.

[0071] According to the second embodiment presented here, the polluted air is charged with sulfur dioxide (SO2). In this case, the average flow rate of the polluted air at the first inlet 22' is adjusted to obtain an upward velocity of the polluted air inside the tower of 0.8 m / s. The ammonia concentration is approximately 100 ppm.

[0072] In addition, the first washing tower 10' has a second first inlet 26' of a first aqueous solution of a solute, here potassium hydroxide KOH.

[0073] The characteristics of this first strong base aqueous solution will be specified in more detail below.

[0074] This second first inlet 26' is connected to a first plurality of spray booms (not shown), arranged in tiers inside the first scrubber tower 10'. In this way, the first aqueous solution is sprayed as fine droplets from the first upper end 16' to the first lower end 14', while polluted air laden with sulfur dioxide is injected counter-currently from the first lower end 14' to the first upper end 16'. This causes at least a portion of the sulfur dioxide to dissolve in the first aqueous solution. It will be noted that the portion of sulfur dioxide dissolved during this first exchange is substantial. For example, it corresponds to more than three-quarters of the sulfur dioxide contained in the polluted air injected at the first inlet 22'.

[0075] Sulfur dioxide then reacts with the potassium hydroxide solution to form potassium sulfate with the chemical formula K2SO4.

[0076] Consequently, the first aqueous solution is then concentrated in sulfur dioxide in the form of potassium sulfate and is conveyed to the first lower end 14' as will be explained below.

[0077] Conversely, in the first upper end 16', the first washing tower 10' includes a first upper outlet 28' allowing the recovery of polluted air freed from at least part of its sulfur dioxide.

[0078] This first first outlet 28' is directly connected to the first second inlet 24' of polluted air of the second washing tower 12'.

[0079] In addition, the second washing tower 12' has a second inlet 30' of a second aqueous solution 10' of potassium hydroxide KOH. The characteristics of this second strong base aqueous solution will be specified below.

[0080] The second inlet 30', like the first scrubber tower 10', is connected to a second plurality of spray booms (not shown), arranged in tiers within the second scrubber tower 12'. In this way, the second aqueous solution is sprayed as fine droplets from the second upper end 20' to the second lower end 18', while the polluted air, laden with at least some of the additional sulfur dioxide remaining after passing through the first scrubber tower 10', is injected counter-currently from the second lower end 18' to the second upper end 20'. This process causes the remaining additional sulfur dioxide to dissolve in the second aqueous solution. It will be observed that almost all of the additional sulfur dioxide is dissolved during this second exchange.

[0081] As mentioned above, with regard to the first scrubbing tower 10', sulfur dioxide reacts in water with potassium hydroxide to form potassium sulfate of chemical formula K2SO4.

[0082] The second aqueous solution is enriched in sulfur dioxide in the form of potassium sulfate also and it flows towards the second lower end 18'.

[0083] Conversely, the polluted air, after this double exchange with a basic aqueous solution, leads to purified air which then escapes from the second upper end 20' through a first second outlet 32'. This air, free of sulfur dioxide SO2, can then be released into the atmosphere without danger.

[0084] It will be noted that traces of sulfur dioxide may nevertheless remain in this released air. But this is harmless to the environment.

[0085] Conversely, and according to a preferred embodiment, an original aqueous solution of potassium hydroxide alone is injected at the second upper end 20' of the second tower 12', through a third inlet 34'. This aqueous solution of potassium hydroxide has, for example, a concentration of two moles per liter. In certain circumstances, the concentration may be higher.

[0086] Advantageously, the original aqueous solution is co-injected with the second aqueous potassium hydroxide solution through the second plurality of spray ramps.

[0087] The second aqueous solution enriched in potassium sulfate of chemical formula K2SO4 is thus recovered by gravity in the second lower end 18' of the second washing tower 12'.

[0088] The second lower end 18' of the second scrubbing tower 12' has a second outlet 36' connected to the second inlet 30' and a third outlet 38' connected to the second inlet 26' of the first scrubbing tower 10'. In other words, a first fraction of this second basic aqueous solution containing potassium sulfate is reinjected into said second scrubbing tower 12' through the second inlet 30', so as to complete the purification of the polluted air, while a second fraction of this second basic aqueous solution is injected into the first scrubbing tower 10' through the second inlet 26' in order to remove a substantial part of the sulfur dioxide contained in the polluted air and injected through the first inlet 22' of the first scrubbing tower 10'.

[0089] Thus, according to an upstream-downstream flow, the polluted air tends to become depleted in sulfur dioxide before escaping from the installation. And according to a reverse downstream-upstream flow, the The potassium hydroxide solution tends to become enriched in potassium sulfate K2SO4. And thus, in the first lower end 14' of the first washing tower 10', we find a third aqueous solution supersaturated in potassium sulfate.

[0090] The first lower end 14' of the first washing tower 10' has a second first outlet 40' allowing the third supersaturated aqueous solution to be conveyed into a receptacle 42', in order to transform into solid phase at least part of the potassium sulfate K2SO4 of the third supersaturated aqueous solution.

[0091] The receptacle 42', for example a crystallizer, has a receptacle outlet 44' connected to the first upper end 16' of the first washing tower 10' at a third first inlet 46'. This third first inlet 46' is connected to the first plurality of ramps like the second first inlet 26'. It thus allows the liquid portion of the third supersaturated aqueous solution to be recycled and further enriched with potassium sulfate K2SO4.

[0092] In this way, potassium sulfate is recovered in solid form in the receptacle 42' so that it can be conditioned and used as fertilizer, for example.

[0093] It will be noted that this third aqueous solution supersaturated with potassium sulfate can also be conditioned and used in liquid form as a fertilizer.

[0094] The installation described above is intended to operate in a continuous mode where the inputs consist of air charged with sulfur dioxide and the original potassium hydroxide solution, while the outputs consist of potassium sulfate in solid and / or liquid form and purified air.

[0095] The object of the invention relates not only to the installation, but also to the process which it enables to be implemented.

Claims

Demands

1. A method for treating air containing a compound of interest, characterized in that it comprises the following steps: - a) air polluted by a given chemical compound is supplied; - b) said polluted air and a first aqueous solution of a solute suitable for causing the solubilization of at least a part of said given chemical compound in said first aqueous solution are injected in a countercurrent manner; - c) air removed from said at least a part of said given chemical compound is recovered; - d) said air removed from said a part of said given chemical compound and a second aqueous solution of said solute are injected in a countercurrent manner so as to cause the solubilization of the other part of said given chemical compound in said second aqueous solution;- e) purified air, removed from said other part of said given chemical compound, is discharged on one side, and said second aqueous solution and said other part of said given chemical compound, solubilized in said second aqueous solution, are recovered on the other side; and in that, in step b), said first aqueous solution injected counter-currently with said polluted air comprises said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution, while in step c), a third concentrated aqueous solution of said at least one part of said given chemical compound and of said other part of said given chemical compound is further recovered.

2. Processing method according to claim 1, characterized in that in step d) said second aqueous solution of said solute comprises, said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution, recovered in step e).

3. Processing method according to claim 1 or 2, characterized in that in step d), an original aqueous solution of said single solute is co-injected with said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution, recovered in step e).

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13. Processing method according to any one of claims 1 to 3, characterized in that at least a part of said third concentrated aqueous solution of said at least a part of said given chemical compound and of said other part of said given chemical compound are transformed into a solid phase. Processing method according to any one of claims 1 to 4, characterized in that at step a) said given chemical compound is ammonia of formula NH3. A treatment process according to any one of claims 1 to 5, characterized in that in step b) said solute is a strong acid. Processing method according to any one of claims 1 to 6, characterized in that in step b) said solute is sulfuric acid of formula H2SO4. Processing method according to any one of claims 1 to 5, characterized in that in step b) said solute is orthophosphoric acid of formula H3PO4. Processing method according to any one of claims 1 to 5, characterized in that in step b) said solute is nitric acid of formula HNO3. Processing method according to any one of claims 1 to 4, characterized in that at step a) said given chemical compound is a sulfur oxide. Processing method according to claim 10, characterized in that at step b) said solute is a strong base. A treatment process according to claim 11, characterized in that in step b) said solute is potassium hydroxide (KOH). An air treatment installation charged with a compound of interest, characterized in that it comprises: - a first scrubbing tower for injecting counter-currently air polluted by a given chemical compound and a first aqueous solution of a solute suitable to cause the solubilization of at least a part of said given chemical compound in said first aqueous solution, said first scrubbing tower comprising a first upper outlet for recovering air removed from said at least a part of said given chemical compound; - a second washing tower connected to the first washing tower by the first upper outlet for counter-current injection

14. in said second washing tower said air removes from said a part of said given chemical compound and a second aqueous solution of said solute so as to cause the solubilization of the other part of said given chemical compound in said second aqueous solution, said second washing tower comprising a second upper outlet to evacuate on one side purified air removed from said other part of said given chemical compound, and a second lower outlet to recover on the other side said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution;and in that said second lower outlet is connected to said first scrubber so that said first aqueous solution injected counter-currently to said polluted air comprises said second aqueous solution and said other part of said given chemical compound solubilized in said second aqueous solution, while said first scrubber comprises a first lower outlet to further recover a third concentrated aqueous solution of said at least a part of said given chemical compound and said other part of said given chemical compound. Processing installation according to claim 13, characterized in that it comprises a receptacle connected to said first lower outlet for transforming into solid phase at least a part of said third concentrated aqueous solution of said at least a part of said given chemical compound and of said other part of said given chemical compound.

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