Improved efficiency pollution control process

Abstract

The invention relates to a process for decontaminating a liquid material to be treated, including a step of circulating a stream (FLX) of said material through at least two treatment media (TDM1, TMD2), each containing a decontamination means. The process according to the invention is characterized in that it includes an oxygenation step (OXY1, OXY2) of said liquid material to be treated before and after its passage through each of the treatment media (TDM1, TMD2). By subjecting the biomass involved in the decontamination process to successive exposures to an oxygenated medium, obtained through the multiple oxygenation steps included in the process according to the invention, it is possible to considerably increase the yield of the chemical reactions that enable the decontamination of the liquid material to be treated. Reference: Figure 4

Description

Title of the invention: Decontamination method with improved efficiency

[0001] The invention relates to a method for decontaminating a liquid material to be treated, including a step of circulating a flow of said material through at least two treatment media each containing a decontamination means. Technical field

[0002] The present invention falls particularly, but not exclusively, within the general field of the decontamination of wastewater loaded with toxic materials such as heavy metals and / or hydrocarbons.

[0003] Such wastewater may, for example, result from washing operations of light or heavy motor vehicles, but may also come from washing operations of tools and machines used in the construction field, where the almost omnipresence of cement and concrete generates another, more specific type of pollution. Prior art

[0004] In the current state of the art, certain decontamination processes provide for the circulation by piston effect of a flow of liquid material to be treated through a pit filled with a sandy medium in which phytoremediation plants have previously been placed, the liquid material collected at the outlet then being considerably purified because the roots of the phytoremediation plants naturally capture the heavy metals and hydrocarbons present in the flow of material to be treated which passes through them, the hydrocarbons then being converted into nutrients, while the heavy metals remain stored there.

[0005] While these known processes allow a certain form of decontamination to be achieved, their effectiveness in terms of sanitation remains improvable, even though their implementation requires large areas of land, which can prove prohibitive, particularly in situations in which the waste water results from washing vehicles in stations set up for this purpose at the roadside, where the availability of free areas is low, and consequently the price of land is very high. Principle of the invention

[0006] After identifying these problems, the inventors designed solutions to resolve them, and in particular developed a method and a system allowing increased pollution control efficiency, while requiring a smaller footprint for its implementation. Summary of the invention

[0007] The present invention thus proposes a method in accordance with the introductory paragraph, characterized in that it includes a step of oxygenation of said liquid material to be treated before and after its passage through each of the treatment media.

[0008] The inventors have in fact observed that by subjecting the biomasses involved in the decontamination process to successive exposures to an oxygenated medium, obtained thanks to the multiplicity of oxygenation stages included in the process according to the invention, it was possible to considerably increase the yield of the chemical reactions which allow the decontamination of the liquid material to be treated.

[0009] In particular, the inventors have observed that a treatment carried out through a box containing a treatment medium having a given length will be less effective than a treatment carried out through a succession of boxes whose cumulative lengths would be equal to said given length, when said boxes are separated by oxygenated spaces.

[0010] According to an advantageous embodiment of the method described above, the treatment media are isolated in removable modular boxes.

[0011] Such an implementation mode makes possible, in addition to the advantages of the invention described above, a variable geometry configuration of the system implemented to carry out the decontamination of the flow of liquid material to be treated, which makes it possible to modulate the nature of the treatment by mixing or not different types of treatment media and by adjusting the number thereof according to the space available to carry out this treatment, and according to the desired decontamination efficiency.

[0012] According to a variant of the method described above, at least one oxygenation step is carried out by exposing the flow of liquid material to be treated to the open air.

[0013] Such a variant allows the beneficial effects of oxygenation to be obtained naturally, for example by causing the liquid material flow to be treated to flow by gravity from a first box to a second box located below the first.

[0014] According to a particular embodiment of the invention, at least one of the treatment media consists of a sandy medium in which phytoremediation plants have been placed.

[0015] As explained above, this method of implementation makes it possible to considerably purify the liquid material collected at the outlet of the box because the roots of the phytoremediation plants naturally capture the heavy metals and hydrocarbons present in the flow of material to be treated which passes through them, the hydrocarbons then being converted into nutrients, while the heavy metals remain fixed there.

[0016] According to another particular embodiment of the invention, which can be implemented alternatively or cumulatively with the previous one, at least one of the treatment media consists of a hydroponic system on the surface of which float rafts carrying phytoremediant aquatic plants.

[0017] This method of implementation makes it possible to purify the liquid material collected at the outlet of the box because the roots of the phytoremediation aquatic plants naturally capture the heavy metals and hydrocarbons present in the flow of material to be treated which is discharged into the settling water, the hydrocarbons then being converted into nutrients, while the heavy metals remain fixed there.

[0018] According to yet another particular implementation variant of the invention, which can be implemented alternatively or cumulatively with the previous ones, at least one of the treatment media consists of a pile of maritime pine bark.

[0019] Such a variant of the invention is particularly suitable for carrying out decontamination operations in the field of construction. The inventors have in fact observed that the rinsing water from tools used in construction, in particular for making concrete, has an extremely alkaline pH, and that exposing this rinsing water to maritime pine bark makes it possible to lower the pH so that the resulting liquid flow can then be treated by the means described above, which are impossible to implement in alkaline environments where the pH is often higher than 12.

[0020] According to a material aspect, the invention also relates to a decontamination system intended for implementing a method as described above, characterized in that it includes a plurality of removable modular boxes each including a treatment medium containing a decontamination means, and intended to be successively crossed by a flow of liquid material to be treated.

[0021] According to a particularly advantageous variant of this material aspect, at least two modular boxes are superimposed therein at least partially with respect to each other so that one of these boxes, called the lower box, can receive by gravity a flow of liquid material to be treated coming from the other box which is immediately above it. Brief description of the drawings

[0022] Other characteristics and advantages of the invention will appear more clearly on reading the following description of a particular embodiment, given by way of illustrative and non-limiting example, and with regard to the appended figures: Fig.l

[0023] [Fig.l] is a perspective view illustrating a pollution control system in accordance with a first embodiment of the invention; Fig.2

[0024] [Fig.2] is a perspective view illustrating a removable box included in such a system ; Fig.3

[0025] [Fig.3] is a sectional view of such a removable box; Fig.4

[0026] [Fig.4] is a schematic view illustrating in more detail the operation of the system conforming to this first mode of implementation of the invention; Fig.5

[0027] [Fig.5] is a perspective view illustrating a pollution control system in accordance with a second mode of implementation of the invention; Fig.6

[0028] [Fig.6] is a schematic view illustrating in more detail the operation of the system conforming to this first mode of implementation of the invention; and Fig.7

[0029] [Fig.7] is a perspective view illustrating a pollution control system in accordance with a particular variant of implementation of the invention. Description of the embodiments

[0030] [Fig.l] represents a decontamination system SYST1 in accordance with a first embodiment of the invention, which includes a plurality of removable modular boxes, each of which is embedded in a metal structure STR, which itself rests on a frame BAT.

[0031] In this first embodiment of the invention, the removable modular boxes are arranged in stages, each box of a given stage, for example the box MCI, being arranged so as to cover a box of the stage immediately below above which it is arranged, in this example the box MC2, which is itself arranged so as to cover a box of the stage immediately below above which it is arranged, in this example the box MC3, which gives great compactness to the SYST1 system.

[0032] These boxes (for example boxes MCI, MC2, MC3) each include a treatment medium containing a decontamination means, and are intended to be successively crossed by a flow of liquid material to be treated. This flow is conveyed by pumping through an inlet pipe IT to the boxes MCI located in the upper position, and flows naturally by gravity to the boxes MC2 and MC3 before being collected in a hydroponic system HPS on the surface of which float rafts carrying phytoremediant aquatic plants PAP. Such rafts are described in patent FR3100686 held by the applicant.This method of implementation makes it possible to purify the liquid material collected at the outlet of the HPS hydroponic system because the roots of the PAP phytoremediant aquatic plants naturally capture the heavy metals and hydrocarbons present in the flow which is discharged into the settling water of the HPS hydroponic system, the hydrocarbons then being converted there. in nutrients for PAP phytoremediation aquatic plants, while heavy metals remain fixed in their roots.

[0033] An outlet pipe OT makes it possible to evacuate the decontaminated liquid after the flow has passed through the treatment media described above.

[0034] In the embodiment shown here, the boxes (MCI, MC2, MC3) each contain a treatment medium consisting of a sandy medium in which PHP phytoremediation plants have been placed.

[0035] As explained above, this method of implementation makes it possible to considerably purify the liquid material collected at the outlet of each box (MCI, MC2, MC3) because the roots of the PHP phytoremediation plants naturally capture the heavy metals and hydrocarbons present in the flow of material to be treated which passes through them, the hydrocarbons then being converted into nutrients, while the heavy metals remain fixed there.

[0036] Figures 2 and 3, to be considered together, represent a particular embodiment of a removable modular box intended to include a treatment medium containing a decontamination means, and to be crossed by a flow of liquid material to be treated.

[0037] In this particular embodiment, the MC box is provided with two shoulders (EPI, EP2) intended to come to bear on the edges of a frame forming part of a support structure, such as for example the metal structure STR previously described.

[0038] This MC box further includes an exhaust pipe OE, intended to collect the flow of liquid material to be treated after it has traveled through the box in a longitudinal direction LGD, driven by a force produced by a piston effect.

[0039] [Fig.4] illustrates in more detail the operation of the way in which two boxes MCI and MC2 interact in this first embodiment of the invention.

[0040] These boxes (MCI, MC2) each contain a treatment medium (TMD1, TMD2) consisting of a sandy SMD medium in which PHP phytoremediation plants have been placed.

[0041] In this first embodiment of the invention, the two modular boxes (MCI, MC2) are superimposed on one another so that the lower box MC2 can receive by gravity a flow FLX of liquid material to be treated from the box MCI which is above it, this flow FLX thus being the subject of an initial oxygenation OXY0 before its passage into the treatment medium TDM1.

[0042] The flow FLX passes through the upper box MCI in its longitudinal direction, driven by a force produced by the piston effect, and is collected through an exhaust pipe OE1 before flowing by gravity towards the lower box MC2, and is then exposed to the open air, which therefore causes an oxygenation step OXY1 of the flow FLX. after its passage through the TDM1 treatment medium and before its entry into the TDM2 treatment medium included in the lower MC2 chamber.

[0043] Similarly, the flow FLX received by gravity effect by the lower box MC2 from the upper box MCI travels through said lower box MC2 in its longitudinal direction, driven by a force produced by piston effect, and is collected through an exhaust pipe OE2 before flowing by gravity towards one or more lower boxes, and is then exposed to the open air, which therefore causes an oxygenation step 0XY2 of the flow FLX after its passage through the treatment medium TDM2, which will further increase the efficiency of the method and of the decontamination system according to the invention.

[0044] It should be noted here that, each box (MCI, MC2) having in its longitudinal dimension a length noted L, the inventors were able to observe that a treatment carried out through a box containing a treatment medium similar to the treatment media (TMD1, TMD2) and having in one piece a length equal to 2xL proves to be less effective than a treatment carried out through the two boxes (MCI, MC2), when said boxes (MCI, MC2) are separated by oxygenated spaces in accordance with the invention.

[0045] [Fig. 5] represents a decontamination system SYST2 in accordance with a second embodiment of the invention, which includes a plurality of removable modular boxes (AC11, AC12, AC13, AC21, AC22, AC33), each of which is embedded in a metal structure STI, which itself rests on a CNT container which serves as a reservoir for an HPS hydroponic system on the surface of which float rafts carrying phytoremediant aquatic plants not shown in the present figure.

[0046] Other metal structures ST2 and ST3 similarly accommodating other removable modular boxes extend overhanging the CNT container in the longitudinal direction LGD, and benefit in a shared manner from the HPS hydroponic system housed in said CNT container.

[0047] In this second embodiment of the invention, the removable modular boxes are arranged in stages, each box of a given stage, for example the box AC11, being arranged so as to only partially cover a box of the stage immediately below which it is arranged, in this example the box AC12, which is itself arranged so as to cover a box of the stage immediately below which it is arranged, in this example the box AC13. Such an arrangement by partial covering allows the plants to develop without being hindered in their growth by the box immediately above.

[0048] PASS gateways allow operators to intervene on each structure (STI, ST2, ST3), and in particular at the level of the boxes to adjust or even re renew the content, for example by replacing phytoremediant plants or sandy media that may be saturated with polluting substances.

[0049] [Fig. 6] represents the operation of a part of the SYST2 decontamination system, in which the removable modular boxes (AC21, AC2) are each provided with a substantially vertical central wall (VW21, VW22) extending in the longitudinal direction while leaving free a circulation space between the lower edge of said wall (VW21, VW22) and the bottom of the removable box (AC21, AC2) to which it is integral.

[0050] Thus, in this example, an upper box AC21 receives a flow FLX of liquid material to be treated from a pumping system not shown in the present figure and is thus subject to an initial oxygenation OXY0. By gravity effect, this flow crosses the sandy media contained in the box AC21 towards the bottom of said box AC21, and goes around the vertical wall VW21 which is installed there before rising towards the surface opposite the inlet zone of said flow under the effect of capillarity and communicating vessels.

[0051] The FLX flow then leaves the upper box AC21 by overflow and falls, in the open air, into a lower box AC22 partially covered by the upper box AC21. On this occasion, the FLX flow is subject to a new oxygenation 0XY1.

[0052] By gravity, this flow crosses the sandy media contained in the lower box AC22 towards the bottom of said box AC22, and goes around the vertical wall VW22 which is installed there before rising towards the surface opposite the inlet zone of said flow under the effect of capillarity and communicating vessels.

[0053] The FLX flow then leaves the lower box AC22 by overflow and falls, in the open air, towards a lower box AC23 not shown in the present figure. On this occasion, the FLX flow is subject to a new oxygenation 0XY2, which further increases the efficiency of the process and of the decontamination system according to the invention.

[0054] [Fig.7] represents a SYST3 pollution control system conforming to a variant by particular implementation of the invention, which is particularly suitable for carrying out decontamination operations in the construction field.

[0055] In this variant of the invention, the decontamination system SYST3 includes a first plurality of superimposed boxes (MC11, MC21 MC31) each containing an EPM treatment medium consisting of a mass of maritime pine bark.

[0056] These superimposed boxes (MCI 1, MC21 MC31) are intended to receive through an inlet pipe IT a flow of liquid material to be treated LMT initially contained in a tank RSV and driven by pumping means not shown in this figure. This liquid material to be treated LMT is here constituted by rinsing water from tools used in construction, in particular for making concrete, and having an extremely alkaline pH (often greater than 12), so that it is not possible to directly apply the phytoremediation steps previously described to it. The inventors have however observed that the exposure of these rinsing waters to maritime pine bark makes it possible to lower the pH so that the resulting liquid flow can then be directed by pumping towards a second plurality of superimposed boxes (MC21, MC22, MC23) similar to that described with reference to figures 1, 2 and 3, in order to continue the decontamination of the liquid material to be treated LMT by phytoremediation.

[0057] Boxes CS1, CS2 containing hydroponic systems HPS1 and HPS2 on the surface of which float rafts carrying phytoremediant aquatic plants not shown in this figure are intended to collect by gravity the flows of liquid material to be treated LMT in order to complete their decontamination.

[0058] It should be emphasized here that the various pollution control systems described above all have a high degree of compactness with regard to their effectiveness. They are also easily integrated into standard-sized containers and therefore easily transportable, for example by road, to their place of use, where they will only require a small installation area.

Claims

Claims

1. Method for decontaminating a liquid material to be treated, including a step of circulating a flow (FLX) of said material through at least two treatment media (TDM1, TMD2) each containing a decontamination means, method characterized in that it includes a step of oxygenation (0XY1, 0XY2) of said liquid material to be treated before and after its passage through each of the treatment media (TDM1, TMD2).

2. Method according to claim 1, characterized in that the treatment media (TDM1, TMD2) are isolated in removable modular boxes (MC).

3. Method according to claim 2, characterized in that at least one oxygenation step (0XY1, 0XY2) is carried out by exposing the flow (FLX) of liquid material to be treated to the open air.

4. Method according to one of claims 1 to 3, characterized in that at least one of the treatment media (TDM1, TMD2) consists of a sandy medium (SMD) in which phytoremediant plants (PHP) have been placed.

5. Method according to one of claims 1 to 3, characterized in that at least one of the treatment media (TDM1, TMD2) consists of a hydroponic system (HPS) on the surface of which float rafts carrying phytoremediant aquatic plants (PAP).

6. Method according to one of claims 1 to 3, characterized in that at least one of the treatment media (TDM1, TMD2) consists of a mass of maritime pine bark (EPM).

7. Decontamination system intended for implementing a method according to one of claims 1 to 6, characterized in that it includes a plurality of removable modular boxes (MCI, MC2) each including a treatment medium (TDM1, TMD2) containing a decontamination means, and intended to be successively crossed by a flow (FLX) of liquid material to be treated.

8. Pollution control system according to claim 7, characterized in that at least two modular boxes (MCI, MC2) are superimposed thereon at least partially with respect to each other so that one of these boxes (MC2), called the lower box, can receive by gravity a flow (FLX) of liquid material to be treated from the other box (MCI) which is immediately above it.

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