Mobile soil treatment unit

Abstract

A modular soil treatment system and apparatus for treating soils contaminated by petroleum hydrocarbons such as gasoline, diesel and heating oil, chlorinated hydrocarbons and volatile organic compounds is disclosed which can be transported to any site and reused.

Claims

1. A modular soil treatment apparatus comprising: a steel container having a floor and sides adapted to hold a quantity of contaminated soil; at least one air circulating section positioned on the floor of the steel container and extending the length of the steel container, the at least one air circulating section including an air extraction pipe positioned underneath a protective perforated steel plate; a steel beam positioned adjacent each side of the protective perforated steel plate wherein the steel beams are positioned at a higher elevation than the protective perforated steel plate relative to the floor of the steel container; an air-water separator positioned outside the steel container and connected to the air extraction pipe; a vacuum blower connected to the air-water separator; and an air filter connected to the vacuum blower.

2. A modular soil treatment apparatus as defined in claim 1, wherein the floor of the steel container slopes towards an outlet for draining liquids seeping from the contaminated soil into a sealed basin connected to the outlet.

3. A modular soil treatment apparatus as defined in claim 1, wherein the steel container is open at the top and is covered with a covering tarp preventing precipitation water from entering into the container.

4. A modular soil treatment apparatus as defined in claim 1, wherein the steel container includes a set of steel wheels and is adapted to be loaded and unloaded from a truck.

5. A modular soil treatment apparatus as defined in claim 1, wherein the steel container includes a door to give access to the inside of the container.

6. A modular soil treatment apparatus as defined in claim 1, further comprising a solar power unit connected to the modular soil treatment apparatus.

7. A modular soil treatment apparatus as defined in claim 6, wherein the solar power unit includes folding solar panels.

8. A modular soil treatment apparatus as defined in claim 7, wherein the solar power unit includes a frame on which the folding solar panels are mounted.

9. A modular soil treatment apparatus as defined in claim 8, wherein the solar power unit is mounted onto a platform adapted for transportation.

10. A modular soil treatment apparatus as defined in claim 7, wherein the solar power unit includes a locking mechanism to adjust the inclination of the solar panels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a better understanding of the present invention, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:

(2) FIG. 1 is a right perspective view of a modular soil treatment apparatus in accordance with one embodiment of the invention;

(3) FIG. 2 is a schematic side elevational view of the modular soil treatment apparatus of FIG. 1;

(4) FIG. 3 is a schematic plan view of the interior of the modular soil treatment apparatus of FIG. 1;

(5) FIG. 3A is cross sectional view of an air circulating section taken at lines 3A-3A of FIG. 3;

(6) FIG. 4 is a side elevation view of the modular soil treatment apparatus of FIG. 1 connected to a solar power unit;

(7) FIG. 5a is a side elevation view of the solar power unit shown in FIG. 4 in a folded position.

(8) FIG. 5b is a front elevation view of the solar power unit shown in FIG. 4 in a folded position.

(9) FIG. 6 is a front elevational view of the solar power unit with a first solar panel opened;

(10) FIG. 7 is a front elevational view of the solar power unit with a second solar panel opened;

(11) FIG. 8a is a side elevational view of the solar power unit in an inclined position; and

(12) FIG. 8b is a front elevational view of the solar power unit of FIG. 8a in an inclined position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) With reference to FIG. 1, there is shown a mobile soil treatment apparatus 10 consisting of a 30 m.sup.3 steel container 12 opened at the top and covered with a tarp 14 secured to the metal container 12 with a series of straps 16. The metal container 12 includes a set of steel wheels 18 and is adapted to be loaded and unloaded from a truck (not shown). On the front of the metal container 12 is mounted a vacuum blower 20 connected via a tube 22 to an integrated air-water separator 24 which is connected via a second tube 26 to an outlet 28 located near the bottom of the metal container 12 in fluid communication with the inside of the metal container 12. The vacuum blower 20 is also connected via a third tube 30 to an air filter (biofilter or carbon filter) 32 in the form of a drum. The air filter 32 includes a venting tube 34 extending upwardly and having a T-shaped exit 36 to prevent precipitations from seeping into the air filter 32.

(14) With reference to FIG. 2, in operation, the container 12 is filled with soil contaminated with petroleum hydrocarbons to which has been previously added the required amendments and fertilizer (e.g., manure, compost, sewage sludge, wood chips, peat moss, nitrogen, phosphorus, potassium). When the vacuum blower 20 is activated, air circulates through the contaminated soil from top to bottom as indicated by the arrows a, exits through the outlet 28, passes through the air-water separator 24 and is redirected to the air filter 32 which absorbs the lighter and more volatile petroleum constituents' carried by the circulating air and the treated air is released into the atmosphere through the venting tube 34. The covering tarp 14 prevents precipitation water from entering into the container 12 but does not seal the top of the container 12 such that air may enter inside the container 12 and circulate.

(15) Biodegradation of the mid-range hydrocarbon products (e.g., diesel fuel, kerosene) and the heavier (non-volatile) petroleum products (e.g., heating oil, lubricating oils) is accomplished by initially introducing minerals, nutrients, and moisture into the contaminated soil inside the container 12, and periodically mixing the soil, to stimulate aerobic microbial activity within the contaminated soil in combination with the aeration process of the circulating air within the container 12 thereby enhancing microbial activity resulting in the degradation of adsorbed petroleum-product constituents through microbial respiration similar to the standard biopile process.

(16) With reference to FIG. 3 illustrating the floor 38 or bottom portion of the container 12, the floor 38 is designed to slope towards the outlet 40 as indicated by arrows b in order to drain liquids seeping from the bottom of the contaminated soil which is accumulated in a sealed basin 42. The floor 38 includes a slotted air extraction pipe 45 (one shown) positioned inside each of the two air circulating sections 44 extending the length of the container 12. The air circulating sections 44 are each covered with a perforated steel plate 47 (one shown) to allow air to pass while supporting the contaminated soil and protecting the extraction pipes 45 during soil mixing operations. The circulating sections 44 are connected to outlets 28 connected to the vacuum blower 20.

(17) With reference to FIG. 3A, which is a cross sectional view of the air circulating sections 44, the slotted air extraction pipe 45 is positioned underneath the perforated steel plate 47 which is supported by a pair of legs 51 resting on the floor 38 of the container 12 such that the perforated steel plate 47 is solidly anchored to the floor 38 and provides the required protection for the slotted air extraction pipe 45. The perforated steel plate 47 is overlain by a layer of geotextile 52 which protects the holes of the perforated steel plate 47 from clogging by soil particles. The perforated steel plate 47 is flanked on both sides with steel beams 49 also resting on the floor 38. As illustrated, the steel beams 49 are higher than the perforated steel plate 47 relative to the floor 38 thereby protecting the perforated steel plate 47 from excavator bucket impacts during soil mixing operations as well as when treated soils are removed from the container 12. The air circulating sections 44 which is defined by the inside portion of the perforated steel plate 47 and a portion of the floor 38 of the container 12 as well as the slotted air extraction pipe 45 are therefore protected from impact from the top by the perforated steel plate 47 and from the sides by the steel beams 49.

(18) Referring back to FIG. 2, apertures 46 are positioned at the bottom of the container 12 to allow a fork lift or wheel-loader to lift, move and position the modular soil treatment apparatus 10. The container 12 is also provided with a door 48 to give access to the inside of the container 12 for soil mixing, for emptying the container 12 by tilting the container 12 and discharging the decontaminated soil and for cleaning the container 12 once the decontamination is completed.

(19) The modular soil treatment apparatus 10 can easily be transported and delivered in any location where decontamination of soil is needed via trucks, trains or ships and can be removed from the location when the decontamination is completed. The same modular soil treatment apparatus 10 may be transported into a new location and reused.

(20) The modular soil treatment apparatus 10 is fully functional as a single unit and is simple to operate such that only a short training program is required by a person to operate and monitor the modular soil treatment apparatus 10.

(21) The modular soil treatment apparatus 10 may be filled with contaminated soil in one location and then transported filled with the contaminated soil to another location where the air filter 32 is connected and the decontamination treatment can take place.

(22) The modular soil treatment apparatus 10 could also be used for treating soils contaminated by chlorinated hydrocarbons and volatile organic compounds.

(23) For soils contaminated by chlorinated hydrocarbons, the modular soil treatment apparatus 10 requires no modification but the treatment process does. The treatment process consists in adding to the contaminated soils 1) nitrogen gas to create an anaerobic environment and 2) a reducing agent. No air circulation is carried out during the treatment process. Following a pre-determined treatment period, the vacuum blower 20 is activated to remove the treatment by-products from the soils by filtration through the air filter 32. The treated soils may present a low pH and therefore may require neutralisation by the addition of an alkaline solution.

(24) For soils contaminated by volatile organic compounds (VOCs), the modular soil treatment apparatus 10 is modified by increasing the size and/or number of air filter(s) 32 or by simply changing the air filtering media, inside the air filter 32, more frequently. In this case, the bioventing treatment process combines biodegradation and the physical removal of the VOCs by air circulation or venting. The extracted VOCs are then removed from the air by filtration through the air filter 32. The bioventing treatment process also requires the addition of amendments and fertilizer to the contaminated soils.

(25) The modular soil treatment apparatus 10 and more specifically, the vacuum blower 20 of the modular soil treatment apparatus 10 may be powered by a standard electrical connection to the local electrical power grid if available. However, in remote locations where electrical power grid is not available, the modular soil treatment apparatus 10 may be powered by a gasoline electric generator which must be maintained and refueled periodically.

(26) As illustrated in FIG. 4, the modular soil treatment apparatus 10 is provided with a standard electrical connection 60. However, to make the modular soil treatment apparatus 10 fully autonomous, a solar power unit 62 is provided. The solar power unit 62 comprises three solar panels 64a, 64b and 64c mounted on to a frame 66 and connected to a power converter 68, itself connected to a battery pack 70 and to the vacuum blower 20 of the modular soil treatment apparatus 10. The power converter 68 manages the electrical current produced by the solar panels 64 to charge the battery pack 70 and manages the delivery of electrical current from the battery pack 70 to the vacuum blower 20 of the modular soil treatment apparatus 10. The entire solar power unit 62 including the solar panels 64, the frame 66 and the battery pack 70 are mounted onto a single platform 72 adapted for easy lifting and manipulation by a standard fork lift.

(27) With reference to FIGS. 5a and 5b, the solar panels 64b and 64c are mounted onto each side of the central solar panel 64a via hinges 74 and 75 such that they can be folded over the central solar panel 64a and the solar power unit 62 with its solar panels 64b and 64c in their folded position may be transported efficiently. In operation, the solar power unit 62 may be loaded inside the steel container 12 of the modular soil treatment apparatus 10 and the entire system brought to location together or it may be transported to the location separately.

(28) With reference to FIGS. 6 and 7, on location, the solar power unit 62 is positioned near the modular soil treatment apparatus 10 and is oriented for maximum exposure to the sun. The solar panels 64b and 64c are deployed by manually opening the solar panel 64b first and then opening the solar panel 64c thereby exposing the central solar panel 64a. As illustrated, solar panels 64b and 64c are hinged onto each side of the central solar panel 64a whereas central solar panel 64a is mounted onto the frame 66 via hinges 76.

(29) With reference to FIGS. 8a and 8b, with the solar panels 64b and 64c fully deployed, the central solar panel 64a is then manually raised by pivoting the central solar panel 64a on its hinges 76 in order to position all solar panels 64a, 64b and 64c in an optimal inclination for maximum exposure to the sun. Once the optimal inclination is established, the central solar panel 64a is locked in the optimal inclined position via locking mechanism 78.

(30) The solar power unit 62 is then connected to the modular soil treatment apparatus 10 when the latter is filled with contaminated soil and ready to begin its operation.

(31) The solar power unit 62 provides an economical, environmentally friendly and autonomous power source for the modular soil treatment apparatus 10 such that the modular soil treatment apparatus 10 can be operated in any location where there is no electrical power grid. Obviously, the solar power unit 62 can be used with the modular soil treatment apparatus 10 even in locations where electrical power is available from a power grid.

(32) Modifications and improvements to the above-described embodiments of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.