Method and equipment for bioremediation of polluted soil in the form of a mound

Abstract

The invention relates to a method for the bioremediation of polluted soil (2) in the form of a mound, characterized in that the method comprises a step of injecting a shear-thinning aqueous fluid into the soil.

Description

TITLE OF THE INVENTION: METHOD AND INSTALLATION FOR THE BIOLOGICAL DEPOLLUTION OF A POLLUTED SOIL PUT INTO THE FORM OF A MOUND TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to the decontamination of soils.

[0002] It concerns more particularly a process of biological decontamination of polluted soil in the form of a mound.

[0003] It also relates to an installation enabling such a process to be implemented.

[0004] The invention finds a particularly advantageous application in the creation of bio-tertres. STATE OF THE ART

[0005] Many naturally occurring soil bacteria are capable of degrading pollutants such as hydrocarbons, provided that these pollutants are bioaccessible and biodegradable. For example, Mycobacterium bacteria are effective at degrading pyrene present in soils.

[0006] Biodegradation, or biological degradation, of polluted soils relies primarily on creating conditions that promote the development of these bacteria, which, by proliferating, degrade the pollutants (which constitute their food source). To develop, bacteria need, in particular, sufficient humidity and preferably nutrients (carbon, nitrogen, phosphorus, potassium) and oxygen for aerobic biodegradation.

[0007] Traditionally, soil treatment using a bio-pile involves excavating the polluted soil and building a mound, sometimes more commonly called a pile. Conventional decontamination facilities then include: a hydraulic circuit for dispersing water, typically via nozzles, at the top of the mound to ensure sufficient humidity; a gas pumping system to provide oxygen; and a water and, if necessary, gas treatment system.

[0008] However, soil is an anisotropic porous medium. In other words, soil exhibits contrasts in permeability. Some areas of the soil are less permeable. are difficult to access to provide water, and therefore potentially nutrients contained in the water, or even oxygen.

[0009] In addition, water seeping into the mound by gravity tends to follow preferential paths, like canals, to flow. Areas distant from these preferential paths are then poorly humidified.

[0010] Thus, the water supply is not uniform in the soil. As a result, bacteria develop less efficiently in certain areas of the soil, which limits pollution control yields. PRESENTATION OF THE INVENTION

[0011] In this context, the present invention proposes a method for the biological decontamination of polluted soil in the form of a mound, characterized in that the method comprises a step of injecting a rheofluidifying aqueous fluid into the soil.

[0012] Thus, thanks to the invention, the non-Newtonian fluid (for example a foam, composed of water, surfactants and air) is better suited to reach areas of low permeability in the soil than a Newtonian liquid.

[0013] Indeed, since the fluid is shear-thinning, injecting the liquid into low-permeability areas increases the pressure and therefore decreases its viscosity. As a result, the fluid spreads through the soil, forming a flat front. In other words, the fluid spreads more evenly despite differences in soil permeability.

[0014] Since the fluid is aqueous, the water is thus delivered with greater homogeneity to the entire soil. The fluid, aqueous and shear-thinning, makes it possible in particular to bring water to areas that would not be reached by gravitational infiltration of water.

[0015] In addition, the fluid propagates in a substantially flat front in the ground, it generates few or no preferential paths.

[0016] As a result, since humidity is controlled more evenly in the soil, bacteria develop there more evenly, which increases pollution control yields.

[0017] Finally, the liquid according to the invention makes it possible to save water, in particular by avoiding or reducing its flow through preferential paths.

[0018] According to an optional and advantageous characteristic of the invention, the rheofluidifying aqueous fluid comprises oxygen.

[0019] Indeed, since most soil decontaminating bacteria are aerobic, it is necessary to bring oxygen into the soil. Thus, as with water, the non-Newtonian fluid allows oxygen to be brought into the soil in the form of air in a homogeneous manner, even though the latter is an anisotropic porous medium.

[0020] According to an optional and advantageous characteristic of the invention, the oxygen is injected into the soil solely by means of the rheofluidifying aqueous fluid.

[0021] In addition, the fluid reduces the use of, or even eliminates, the costly ventilation systems used in conventional decontamination facilities. These ventilation systems create a vacuum at the mound, which is then covered with a plastic sheet. The fluid therefore saves energy and materials.

[0022] According to an optional and advantageous characteristic of the invention, the rheofluidifying aqueous fluid comprises a surfactant.

[0023] Thanks to the surfactant, for example contained in a foam, the fluid facilitates the passage of pollutants from a solid phase, on which they are adsorbed in the soil particles, to a liquid phase. In other words, the surfactant allows desorption and solubilization of pollutants in the fluid or in a liquid naturally present in the soil (for example water). Thus, the surfactant improves the availability, and more specifically the bioavailability, of pollutants since bacteria decompose pollutants more efficiently in the liquid phase than in the solid phase. In addition, thanks to the shear-thinning fluid, the surfactant is delivered homogeneously to the soil.

[0024] According to an optional and advantageous characteristic of the invention, the rheofluidifying aqueous fluid is a foam comprising air bubbles and an aqueous solution which comprises a surfactant, the air bubbles being dispersed in the aqueous solution.

[0025] The fluid is thus made shear-thinning thanks to compounds that are themselves useful for decontamination. The foam provides water and oxygen (and potentially nutrients) for the proliferation of bacteria as well as the surfactant for increasing the bioavailability of pollutants. In addition, the viscosity of the fluid is easily adaptable by adjusting the size of the bubbles. Advantageously, the air used to generate the foam is also used to bring oxygen into the soil.

[0026] According to an optional and advantageous characteristic of the invention, the rheofluidifying aqueous fluid comprises nutrients adapted to the proliferation of bacteria present in the soil.

[0027] Indeed, the amount of nutrients needed for bacterial proliferation may be naturally insufficient in the soil. In this case, it is then preferable to provide additional nutrients to the soil. Thus, as with water or oxygen, the fluid allows nutrients to be brought into the soil evenly, even though the latter is an anisotropic porous medium.

[0028] Remarkably, the fluid alone provides all the resources that bacteria need, whether water, oxygen or nutrients.

[0029] Other advantageous and non-limiting characteristics of the method according to the invention, taken individually or in all technically possible combinations, are the following: - air bubbles have a diameter between 1 pm and 5 mm; - air bubbles have a diameter smaller than an average pore size of the soil; - the foam comprises between 70% and 95% air by volume; - an injection rate of the aqueous rheofluidifying fluid into the soil and an injection pressure of the aqueous rheofluidifying fluid into the soil are determined on the basis of the granulometry of the soil; - the injection pressure of the fluid into the soil is less than 10 bar / m; - the method further comprises a step of forming the rheo-thinning aqueous fluid, the rheo-thinning aqueous fluid being injected immediately after its formation; - the soil is polluted by refined petroleum hydrocarbons.

[0030] The invention also relates to an installation for biological decontamination of polluted soil in the form of a mound, the installation comprising: - a generator suitable for producing a rheofluidifying aqueous fluid; - a circuit in fluid communication with the generator and adapted to inject the rheofluidifying aqueous fluid into the soil.

[0031] Other advantageous and non-limiting characteristics of the installation according to the invention, taken individually or in all technically possible combinations, are the following: - the rheofluidifying aqueous fluid is a foam and the generator comprises a compressor, a pump and a porous medium, the compressor being adapted to inject pressurized air into the porous medium and the pump being adapted to inject an aqueous solution comprising a surfactant, and preferably nutrients, into the porous medium so as to produce the foam; - the porous medium comprises an inlet for receiving the air and the solution and an outlet for expelling the foam, the generator comprising two pressure sensors adapted to determine a pressure difference between the outlet and the inlet of the porous medium. DETAILED DESCRIPTION OF THE INVENTION

[0032] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0033] On the attached drawings:

[0034] Figure 1 is a schematic side view of a biological decontamination installation for polluted soil formed into a mound according to the invention.

[0035] Figure 2 is a block diagram of a sequence of steps for the biological decontamination of polluted soil in the form of a mound.

[0036] An installation 1 for biological decontamination of a soil 2 according to the invention is shown in Figure 1. The biological decontamination of the soil 2 here means the decontamination, or remediation, of the soil 2. The soil 2, which is intended to be treated by the installation 1, is polluted, in other words contaminated, for example by refined petroleum hydrocarbons such as diesel, fuel oil, kerosene. The soil 2 can also be polluted by volatile or semi-volatile organic compounds, pesticides or oils. The soil 2 has, for example, a pollutant concentration of less than 30,000 mg / kg.

[0037] Soil 2 here comprises mineral matter and organic matter. Soil 2 is, for example, composed of earth. Soil 2 notably comprises bacteria capable of degrading the aforementioned pollutants. The decontamination is thus described as biological because it is carried out by the bacteria themselves. Installation 1 makes it possible to treat soil 2 in such a way as to promote this biological decontamination, that is to say to increase the activity of the bacteria. This makes it possible, for example, to increase or accelerate the decontamination efficiency.

[0038] As shown in Figure 1, the soil 2 is formed into a mound 20. Here, in the context of biological decontamination, the soil 2 therefore forms a biomound. For this, the soil 2 is previously excavated, that is to say extracted, for example by digging, then piled up so as to form the mound 20. The mound 20 has a generally pyramidal shape, rising from a base 21 towards a summit 22 which is narrower than the base 21. The mound 20 has, for example, a trapezoidal shape as shown in Figure 1.

[0039] The installation 1 here comprises a support 3 on which the soil 2 is placed, more particularly the base 21 of the mound 20. The support 3 is for example a waterproof tarpaulin. In the example illustrated in figure 1, the installation 1 also comprises a geomembrane 4, i.e. a waterproof cover, which protects in particular the soil 2 from bad weather. The geomembrane 4 is here connected to the support 3, for example by means of a berm 5, so as to control the exchange of fluids, in particular water and air, between the mound 20 and the outside.

[0040] Installation 1 thus makes it possible to treat soil 2 ex situ, i.e. outside its natural location, as opposed to in situ treatment where the soil would be left in place.

[0041] As shown in Figure 1, the installation 1 comprises a generator 6 adapted to produce a fluid, which is both aqueous and shear-thinning, and a circuit 7 in fluid communication with the generator 6. The circuit 7 is arranged to inject the fluid produced by the generator 6 into the ground 2, i.e. into the mound 20. Thus, by “injecting” the liquid into the ground, we mean bringing it directly into the ground 2, i.e. inside the mound 20, by means of a device which penetrates into the ground 2, here the circuit 7, one end of which is therefore located in the ground 2. This is in particular opposed to sprinkling or spreading the liquid on the ground 2, typically at the top of the mound.

[0042] The fluid is aqueous in the sense that it is water-based. The fluid is shear-thinning in the sense that its fluidity increases as its flow rate increases. In other words, the dynamic viscosity of the fluid decreases as the shear rate applied to it increases. The fluid is therefore more liquid as its flow rate increases, particularly under the effect of a force (this is also referred to as shear thinning or shear thinning). The fluid, being non-Newtonian, is thus particularly suitable for reaching areas of low soil permeability 2 since its viscosity decreases in these areas.

[0043] The fluid here is more specifically a foam. The foam comprises a gas dispersed in an aqueous solution comprising water and a surfactant. The gas notably comprises oxygen, for example in the form of dioxygen. The gas here is air. The foam thus comprises air bubbles suspended in the solution of water and surfactant.

[0044] Surfactant is a surfactant that lowers the surface tension of water. Examples of surfactants include: sodium dodecyl sulfate (SDS), sodium dodecyl benzenesulfonate, and rhamnolipid. Surfactants advantageously help form foam by maintaining bubbles and increase the bioavailability of pollutants by facilitating their passage into the liquid phase.

[0045] As shown in Figure 1, to produce the foam, the generator 6 comprises a first tank 61, a compressor 62, a pump 63 and a porous medium 64.

[0046] The first reservoir 61 contains the water and surfactant solution. The water and surfactant are therefore premixed here. The first reservoir 61 is fluidically connected to the porous medium 64 via the pump 63 which makes it possible to inject the water and surfactant solution into the porous medium 64.

[0047] The compressor 62 is also connected to the porous medium 64 and allows pressurized air to be injected into it. The air injected is ambient air. Alternatively, the generator does not include a compressor but a bottle containing air already under pressure. The generator can then include a pressure reducer adapted to control the pressure of the air injected into the porous medium.

[0048] The porous medium 64 has open pores that communicate with each other. The porous medium 64 comprises, for example, a sintered material. The porous medium 64 is, for example, confined in a sealed enclosure delimiting an inlet of the porous medium 64, to which the compressor 62 and the pump 63 are connected, and an outlet of the porous medium 64, through which the foam is expelled. The porous medium 64 is essentially made up of materials with interstice porosity such as silts, clays, sands or even gravels.

[0049] In the porous medium 64, the pressurized air mixes with the water and surfactant solution to produce the foam. The pore size of the porous medium 64 makes it possible to control the size of the air bubbles suspended in the foam. The air bubbles have, for example, a diameter of between 1 μm and 5 mm. The size of the air bubbles here depends on the pore size of the porous medium 64.

[0050] In the example illustrated in Figure 1, the generator 6 also comprises a second reservoir 65 containing nutrients. The nutrients are here dissolved in an aqueous solution, for example at a concentration of between 100 mg / L and 1000 mg / L. The nutrients are for example selected from the group comprising: carbon, nitrogen, phosphorus, potassium. These nutrients promote the development of bacteria responsible for the biodegradation of the soil 2. In order to include them in the foam, the second reservoir 65 is also connected to the pump 63, as shown in Figure 1. Alternatively, the second reservoir can be connected to an independent pump connected to the inlet of the porous medium.

[0051] The pump 63 thus brings to the inlet of the porous medium 64 a mixing solution comprising water, the surfactant and the nutrients.

[0052] The generator 6 comprises two pressure sensors adapted to measure a pressure difference between the outlet and the inlet of the porous medium 64. As shown in FIG. 1, the two pressure sensors thus form a differential pressure sensor 66. The pressure is thus controlled at the inlet and outlet of the porous medium 64. The generator 6 also comprises valves, in particular a first valve 67 at the inlet and a second valve 68 at the outlet of the porous medium 64.

[0053] The first valve 67 at the inlet of the porous medium 64 here makes it possible to control the flow of air, and the pressure of the air, which is injected into the porous medium 64. The flow of the mixing solution is regulated by the pump 63. The first valve 67 is thus adapted to control the air pressure. The air pressure at the inlet of the porous medium 64 is for example between 1 bar and 20 bars. Generally speaking, the lower the liquid / gas ratios, the stronger the foam is said to be and the smaller the size of the bubbles.

[0054] The injection pressures and flow rates in the porous medium 64 are, for example, controlled so that the foam comprises a gaseous fraction accounting for 70% to 95% of the total volume of the foam. In other words, the foam comprises, by volume, between 70% and 95% air. In addition, the foam comprises a liquid fraction accounting for 5% to 30% of the total volume of the foam. In other words, the foam comprises, by volume, between 5% and 30% of the mixing solution.

[0055] The amount of surfactant in the liquid fraction of the foam is, for example, between 0.5 mg / L and 200 mg / L.

[0056] The amount of nutrients in the liquid fraction of the foam is, for example, between 0.1 g / L and 250 g / L. The ratio between the amounts of carbon, nitrogen, phosphorus and potassium (C / N / P / K) is, for example, 100 / 10 / 1 / 1.

[0057] The second valve 68 at the outlet of the porous medium 64 makes it possible to control the pressure of the foam at the outlet of the generator 6. As shown in FIG. 1, the generator 6 is connected to the circuit 7 downstream, i.e. at the outlet, of the porous medium 64. The second valve 68 at the outlet of the porous medium 64 thus makes it possible to control the pressure and the flow rate of the foam in the circuit 7.

[0058] The circuit 7 here comprises a plurality of pipes or conduits making it possible to convey the foam produced by the generator 6 into the ground 2.

[0059] In the example illustrated in Figure 1, the circuit 7 comprises in particular a main pipe 71 fluidly connected to the generator 6 and a plurality of injection pipes 72 each connected to the main pipe 71. The main pipe 71 is for example horizontal. The main pipe 71 comprises an inlet, connected to the generator 6 to receive the foam, and a plurality of outlets, an injection pipe 72 being connected to each outlet.

[0060] As shown in Figure 1, the injection pipes 72 extend for example in the vertical direction D1 and penetrate into the mound 20 through its top 22. The injection pipes 72 are preferably distributed homogeneously in the mound 20. The injection pipes 72 extend for example over 30% to 70% of the height of the mound 20, the height of the mound 20 being defined here as the distance between the base 21 and the top 22 of the mound 20 in the vertical direction D1. The mound 20 preferably has a height of less than 3 m. Each injection pipe 72 therefore has an end, here a lower end, located in the mound 20, when the installation 1 is in use.

[0061] The injection pipes 72 are for example tubes having on their cylindrical wall small orifices, for example smaller than a radius of the tube. The orifices (located in the mound during the injection of the fluid) allow the foam to penetrate into the soil 2 from inside the injection pipes 72. The lower end 73, opposite the main pipe 71, of each injection pipe 72 is here open. Alternatively, the lower end could be closed to increase the pressure at the orifices. Once injected into the mound 20, the foam is initially distributed laterally in the soil 2 (mostly horizontally) and concentrically from each injection line 72 due to a pressure gradient and capillary forces. Secondly, after the foam has collapsed, the water, surfactants and nutrients flow vertically by gravity.

[0062] Of course, various shapes of the circuit for conveying the foam into the mound are possible. For example, the circuit may include a single injection pipe that extends in different directions into the mound. The injection pipe(s) may be curved or have angles. The injection pipe(s) may have a variable number of orifices of varying size and shape. The installation can also be used to decontaminate several mounds simultaneously. Several main pipes can then be connected to the generator outlet, for example, one main pipe per mound.

[0063] The installation 1 also includes a drain 8 at the base 22 of the mound 20. The drain 8 is arranged to recover residues in liquid form resulting from the flow of the foam in the mound 20 (after the foam has collapsed) and bring them into a tank 9 for further treatment. These residues may in particular contain pollutants in liquid phase, desorbed from the soil 2 by the action of the surfactant.

[0064] Figure 2 illustrates a process for biological soil decontamination 2. The process is implemented here using installation 1.

[0065] The decontamination process includes a main step of injecting foam, i.e. a rheofluidifying aqueous fluid, into the soil 2.

[0066] As shown in Figure 1, the process begins more specifically with a first step E1 of forming a mound of soil 2. The first step E1 may, for example, comprise an excavation of soil 2 and the supply of soil 2 to the decontamination site where installation 1 is located.

[0067] Before forming a mound, soil 2 can be mixed with a structuring agent such as wood chips.

[0068] The formation of the mound 20 from the soil 2 is here carried out by stacking the soil 2 on the support 3. Preferably, the drain 8 is prepositioned on the support 3 when the soil 2 is formed into a mound.

[0069] The method continues with a second step E2 of installing the circuit 7 and in particular installing the injection pipes 72 in the mound 20. Once the injection pipes 72 are in place, the mound 20 is covered by the geomembrane 4.

[0070] The process then comprises a third step E3 of foam formation. The foam is here formed by the generator 6.

[0071] During the third step E3, the conditions for manufacturing the foam, in particular the pressure for injecting air into the porous medium 64, are controlled so that the air bubbles have a diameter smaller than an average pore size of the sol 2. The average pore size of the sol 2 depends on the granulometry of the sol 2.

[0072] In the third step E3, the surfactant and / or nutrients to be incorporated into the foam can also be selected based on at least one of the following parameters: average pore size of soil 2, nature of soil 2 (e.g. organic matter content, permeability, soil surface), safety with respect to bacteria present in soil 2, type of pollution (e.g. concentrations and type of pollutants, bioavailability and biodegradability).

[0073] Generally speaking, the size of the foam bubbles, the proportions of air, water and surfactant in the foam, the flow rates and injection pressures of the air and the mixing solution into the porous medium 64, are adapted as a function of at least one of the following parameters: a viscosity to be achieved, a radius of action of the injection pipes 72 (corresponding to a volume of soil 2 located around an injection pipe 72 and which the latter is intended to treat), the average pore size of the soil 2.

[0074] Once the foam has formed, it is injected into soil 2 during a fourth step E4 of the process. The foam is therefore injected when soil 2 is in the form of a mound.

[0075] The foam advantageously makes it possible to supply the soil 2, via a single fluid, with water, nutrients and oxygen useful for the proliferation of bacteria (and therefore for their decontamination work) as well as the surfactant making the pollutants more bioavailable. In addition, since the foam is rheofluidifying, these contributions useful for the proliferation of bacteria are made homogeneously in the mound 20, despite potential differences in permeability of the soil 2.

[0076] In the process, oxygen is thus injected into the soil 2 solely by means of the foam, i.e. the rheofluidifying aqueous fluid. Indeed, by collapsing in the mound 20 after injection, the bubbles release the air, and therefore oxygen, directly into the soil 2. This makes it possible to simplify the installation 1, for example by dispensing with mound ventilation ducts.

[0077] Remarkably, the foam is injected directly after its formation by the generator s. In other words, the foam is produced and injected continuously. Thus, the pressure used to generate the foam in the porous medium 64 also allows the injection of the foam into the soil 2. This makes it possible, for example, to do without a specific pump.

[0078] The injection flow rate and the injection pressure of the foam into the soil 2 are determined on the basis of the nature of the soil, and in particular its granulometry. The injection flow rate and the injection pressure are here defined, that is to say measurable, as the flow rate and the pressure of the foam at the outlet of the generator 6. In other words, the injection flow rate and the injection pressure are here defined at the inlet of the main pipe 71, and therefore at the valves 67, 68 and more particularly at the second valve 68.

[0079] The injection flow rate is for example between 0.2 and 25 m 3 / h. The injection rate is determined here according to the size of the mound 20 and the permeability of the soil 2.

[0080] The injection pressure of the fluid into the soil 2 is preferably less than 10 bar / m. This reduces the risk of the soil 2 lifting from the support 3.

[0081] The foam may be injected continuously for a predetermined period or periodically, for example at regular time intervals. The foam is, for example, injected in successive periods of a few tens of minutes of injection interspersed with a few tens of minutes of rest.

[0082] The quantity of foam injected depends in particular on the volume of the soil 2.

[0083] The process then includes a fifth step E5 of remediation of the soil 2 comprising a wait allowing the action of degradation of the pollutants by the bacteria. This fifth step E5 of remediation lasts for example several days. The fifth step E5 also includes the recovery by the drain 8 of the liquid residues which are then treated.

[0084] The present invention is in no way limited to the embodiment described and shown, but those skilled in the art will be able to make any variation in accordance with the invention. For example, the method can be implemented by any suitable system. The foam could be prefabricated and contained under pressure in a tank. The shear-thinning aqueous fluid could also be a non-oxygenated gel. Such a gel finds a particular application for anaerobic biodegradation, i.e. that is, when soil bacteria do not need oxygen.

Claims

CLAIMS

1. Method for biological decontamination of polluted soil (2) in the form of a mound, characterized in that the method comprises a step of injecting a rheofluidifying aqueous fluid into the soil (2).

2. The method of claim 1, wherein the aqueous shear-thinning fluid comprises oxygen.

3. A method according to claim 2, wherein oxygen is injected into the soil (2) solely by means of the shear-thinning aqueous fluid.

4. Method according to one of claims 1 to 3, in which the rheofluidifying aqueous fluid comprises a surfactant.

5. A method according to one of claims 1 to 4, wherein the rheofluidifying aqueous fluid is a foam comprising air bubbles and an aqueous solution which comprises a surfactant, the air bubbles being dispersed in the aqueous solution.

6. The method of claim 5, wherein the air bubbles have a diameter of between 1 pm and 5 mm.

7. A method according to claim 5 or 6, wherein the air bubbles have a diameter smaller than an average pore size of the sol (2).

8. Method according to one of claims 5 to 7, in which the foam comprises by volume between 70% and 95% air.

9. Method according to one of claims 1 to 8, in which the rheofluidifying aqueous fluid comprises nutrients suitable for the proliferation of bacteria present in the soil (2).

10. Method according to one of claims 1 to 9, in which an injection rate of the aqueous rheofluidifying fluid into the soil (2) and an injection pressure of the aqueous rheofluidifying fluid into the soil (2) are determined on the basis of the granulometry of the soil (2), the injection pressure of the fluid into the soil (2) preferably being less than 10 bar / m.

11. Method according to one of claims 1 to 10, comprising in in addition to a step of forming the rheofluidifying aqueous fluid, the rheofluidifying aqueous fluid being injected immediately after its formation.

12. Method according to one of claims 1 to 11, in which the soil (2) is polluted by refined petroleum hydrocarbons.

13. Installation (1) for biological decontamination of polluted soil (2) in the form of a mound, the installation comprising: - a generator (6) adapted to produce a rheofluidifying aqueous fluid; - a circuit (7) in fluid communication with the generator (6) and adapted to inject the rheofluidifying aqueous fluid into the soil (2).

14. Installation (1) according to claim 13, in which the rheofluidifying aqueous fluid is a foam and in which the generator (6) comprises a compressor (62), a pump (63) and a porous medium (64), the compressor (62) being adapted to inject pressurized air into the porous medium (64) and the pump (63) being adapted to inject an aqueous solution comprising a surfactant, and preferably nutrients, into the porous medium (64) so ​​as to produce the foam.

15. Installation (1) according to claim 14, in which the porous medium (64) comprises an inlet for receiving the air and the solution and an outlet for expelling the foam, the generator (6) comprising two pressure sensors adapted to determine a pressure difference between the outlet and the inlet of the porous medium (64).

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