DEVICE FOR THE ENVIRONMENTAL RECLAMATION OF CONTAMINATED SOILS

Abstract

A device is described for the environmental reclamation of contaminated soils through the technology known as landfarming. According to the invention, such device provides one or more tubs (1) of a rigid material, (for example a metal material or a plastic material) each equipped with a sensing probe (3) of soil moisture to be inserted thereinto for reclamation, a watering unit (5), connected to said probe (3), and a collection point (4) of soil sample to allow analysis thereof. Preferably, the tub (1) has a bottom plane (2) tilted of 0.01% to 5%.

Claims

1) Stationary device for environmental reclamation of contaminated soils, through the technology known as landfarming, characterised in that it provides one or more tubs (1) containing the soil to be reclaimed and into which said soil to be reclaimed is introduced, taking it from its natural seat, and laid flat and levelled, in a similar way to how it is found in its natural location, said tubs being of a rigid material, to be placed resting on the ground or partially buried in it, and equipped with a sensing probe (3) of soil moisture to be inserted thereinto for reclamation, a watering unit (5), connected to said probe (3) and a collection point (4) of soil samples to allow analysis thereof.

2) Device according to claim 1, characterised in that the soil to be reclaimed is introduced into the tub(s) (1) making a layer of thickness between 10 and 50 cm.

3) Device according to claim 1, characterised in that said tub (1) is made of a metal material, such as cast iron, iron, steel, aluminium, lead or alloys of the same.

4) Device according to claim 1, characterised in that said tub (1) is made of a plastic material which is resistant under the treatment conditions, such as polyethylene, polypropylene, polystyrene, polycarbonate, Kevlar, polyethylene terephthalate, polyurethane, polyamide.

5) Device according to claim 1, characterised in that the tub (1) has a tilted bottom plane (2).

6) Device according to claim 5, characterised in that the slope of the bottom plane (2) ranges from 0.01% to 5%, preferably ranging from 0.8% to 2% and preferably being around 1%.

7) Device according to claim 1, characterised in that said sensing probe (3) also monitors also one or more of the following parameters: temperature, pressure, concentration of microorganisms, concentration of oxygen, concentration of carbon dioxide.

8) Device according to claim 1, characterised in that said watering unit (5) includes a tank (6), a pipeline (7) and a nozzle system (8).

9) Device according to claim 8, characterised in that said nozzles (8) consist of pipes (9) with openings (10) along their length.

10) Device according to claim 1, characterised in that it is a pilot plant.

11) System for environmental reclamation of contaminated soils, including one or more devices according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further features and advantages of the invention will anyway be better apparent from the following detailed description of a preferred embodiment, given purely by way of non-limiting example and illustrated in the attached drawings, wherein:

[0019] FIG. 1 is a schematic, perspective view of a device according to a preferred embodiment of the present invention;

[0020] FIG. 2 shows a system which employs devices according to the present invention, based on the embodiment of FIG. 1;

[0021] FIG. 3 shows an operating diagram of the system according to FIG. 2; and

[0022] FIG. 4 is a detail of FIG. 3.

DETAILED DESCRIPTION

[0023] According to the present invention, the device includes a tub 1 to be laid on a land, placing it above the ground or partially in-ground. The tub 1 is made of rigid material and can preferably be made of a metal material, such as cast iron, iron, steel, aluminium, lead or their alloys, or in a plastic material which is resistant under the treatment conditions, such as polyethylene, polypropylene, polystyrene, polycarbonate, Kevlar, polyethylene terephthalate, polyurethane, polyamide, and others. It can also be made of wood or a stone material as long as the chemical conditions allow it. It is preferred that the tub 1 in made of AISI 316L steel, given its high resistance to corrosion. Preferably, the tub 1 is in the shape of a parallelepiped which allows to place it without causing any space issues.

[0024] The tub 1 preferably has a tilted bottom plane 2 for a better irrigation of the soil contained therein. Preferably, the slope of the bottom plane 2 ranges between 0.01% and 5%, preferably ranging from 0.8% to 2% and preferably being around 1%. This range of slope of the soil is to reproduce the slope of the land normally undergoing reclamation, in order to work under similar conditions to the natural ones; in this way, the device according to the present invention could be used for a study of reclamation directly in the land, profiling the reclamation rate depending on soil depths. A tub 1 suitable for use in a pilot plant is, for example, 10 cm×30 cm×20 cm in size.

[0025] A sensing probe 3 is further placed inside the tub 1. The sensing probe 3 generally and mainly detects the moisture of the soil under reclamation, but sensing probes can be provided that also monitor one or more of the following parameters: temperature, pressure, concentration of microorganisms, concentration of oxygen, concentration of carbon dioxide, so as to better monitor the remediation progress and to quickly and reliably identify the possible causes of a slowing down in the remediation process going on in tub 1, and to be able of acting to remove them. The sensing probe 3 can be of any known type. For example, it can be the EE210 sensing probe, marketed by EE Elektronik of En-gerwitzdorf, Austria.

[0026] Externally to the bottom part of the tub 1 a collection point 4 is provided, which can be of any known type, for example a pipe with an opening/closing valve or a tap.

[0027] Finally, a watering unit 5 is associated to the tub 1, preferably including a tank 6, a pipeline 7 and a nozzle system 8. The nozzles 8 can preferably consist of pipes 9 with openings 10 along their length. This particular embodiment ensures an even irrigation within the entire tub 1.

[0028] The sensing probe 3 and the watering unit 5 are logically connected by a processing unit 11, for example a PLC.

[0029] The device according to the present invention can function as a single tub 1, as shown in FIG. 1, or as a system of multiple tubs, as shown in FIGS. 2 and 3 (where three tubs are illustrated). Therefore, the invention also relates to a system for environmental reclamation of contaminated soils including one or more of the devices described so far.

[0030] At the start of the process, the soil to be remediated is introduced into the tub(s) 1, making a relatively thin layer (for example, with a thickness ranging between 10 to 50 cm), so as to keep high the mass transfer with the environment, especially of oxygen. The soil is laid flat and levelled, like in the place from which it is taken. The sensing probe 3 is then inserted into the soil and the sludge to be added are inoculated to improve the efficiency of the reclamation process. Thereby, the reclamation process starts, and bacteria begin their work of pollutant degradation in a per se known manner.

[0031] As already mentioned, the sensing probe 3 can detect several parameters; in particular, the sensing probe 3 detects the soil moisture and preferably continuously transmits the relative value to the processing unit 11. As soon as the moisture value drops below a certain threshold, the signal sent to the processing unit 11 causes the watering units 5 to be sent a start signal.

[0032] It should be noted that, in case of a system like the one shown in FIGS. 2 and 3, each sensing probe 3 and each watering unit 5 can also work independently from those of the other tubs, in contrast to what is illustrated in FIG. 2.

[0033] Upon starting the watering unit 5, water is drawn from the relative tank 6 and sent through the pipeline 7 to the nozzles 8, from which it comes out and wets the soil laid on the bottom plane 2 of the relative tub 1, irrigating it. This irrigation raises the moisture value of the soil, so that the optimal living conditions for the bacteria active in the reclamation are maintained, in order to keep the speed of the reclamation process high. The sensing probe 3 continues to sense the moisture and to transmit its value to the processing unit 11. When the moisture value exceeds a certain threshold value—normally higher than that previously mentioned—the processing unit 11 transmits a new signal to the watering unit 5, causing it to stop watering the soil through the nozzles 8.

[0034] The reclamation process proceeds and the watering unit 5 will be started again at the moment of a new downward crossing of the threshold value, and it will be stopped at the next upward crossing of the other threshold value.

[0035] In addition to water, the watering unit 5 can preferably deliver to the soil inside the tubs 1 also the nutrients possibly needed for carrying out the reclamation: this addition plays also a role in the creation of an ideal environment to promote and facilitate bacteria proliferation.

[0036] Bacteria degrade the pollutants in the soil, gradually decontaminating it. Any checks on the progress of the reclamation process can be carried out by collecting soil samples from the collection point 4. The collection point can be a pipe with a suitable valve, a septum, a door, a tap or other. Collecting samples through collection point 4 is much easier than in normal landfarming tubs and, owed to its position with respect to the soil to be remediated, the characteristics of the collected sample are those of the soil bulk and not the usually anomalous ones of the surface layer, so that a much more representative sample of the actual situation can be obtained.

[0037] As the analysis show that the remediation has successfully completed, sensing probes 3 and watering units 5 are stopped and the remediated soil is recovered to be put back to its original seat. As already mentioned in the introduction of the present disclosure, the device according to the present invention can be used directly on the site from where the sewage sludge to be used as inoculum is taken, so that there is not the always difficult and expensive handling of said sludge—which is in all respects, especially legal, waste—outside the site, and the bacterial loads are exploited to the maximum. Another advantage is that it is possible to take the soil from the surroundings, without need of digging landfarming tubs, thus considerably limiting the consumption of soil, a very sensitive problem nowadays.

[0038] The device according to the present invention is particularly useful in the case of landfarming pilot plants, since it allows to operate in situ, with no major transport of material from one site to another one, and it allows to readily monitor the various steps of reclamation, so as to enable the optimisation of its parameters, in order to improve the future operation performances. Therefore, the invention also provides a device which is a pilot plant. In this case, it will be possible to operate under conditions which are close to reality, i.e., using microcosms. If a system like that illustrated in FIGS. 2 and 3 is used for the pilot tests, each tub 1 can be managed under different conditions, so as to identify the optimal ones. The device according to the present invention can be likened in many respects to production plants of agricultural composting amendments, since the sludge after reclamation has precisely the function of agricultural amendments, notoriously having fertilising properties.

[0039] However, it is understood that the invention should not be considered as limited to the particular arrangement illustrated above, which is only an exemplary embodiment thereof, but that several variants are possible, all within the reach of a person skilled in the art, without thereby departing from the scope of the invention itself, as defined by the following claims. In particular, the device according to the present invention could be configured to be remote controlled.

REFERENCE LISTING

[0040] 1 Tub [0041] 2 Bottom plane (of 1) [0042] 3 Sensing probe [0043] 4 Collection point [0044] 5 Watering unit [0045] 6 Tank (of 5) [0046] 7 Pipeline (of 5) [0047] 8 Nozzles (of 9) [0048] 9 Pipes (of 5) [0049] 10 Openings (of 9) [0050] 11 Processing unit