GB2299081A - Waste treatment apparatus - Google Patents

Abstract

A waste treatment apparatus comprises a collapsible container (10) having a plurality of interconnecting panels (24, 26, 28, 30) at least some of which are perforated to permit the passage of air, the panels being adapted to be assembled to form a housing (12) for receiving soil to be treated through which air and water may pass, wherein a suitable environment for aerobic bioremediation of solid and for liquid waste is provided. The housing (12) is adapted to be disassembled and collapsed to form a flatpack arrangement to facilitate transportation. A perforated base may be provided. The perforated base is preferably a non-biodegradable permeable material, (e.g. a) flexible plastic with a high internal surface area. The apparatus is used to convert environmentally unsound and/or waste products, into products which are not deleterious to the environment and which may have useful properties. An example is the conversion of harmful hydrocarbons in a contaminated soil, into carbon dioxide and water.

Description

WASTE TREATMENT APPARATUS The present invention relates to a waste treatment apparatus and to methods for the treatment of solid and liquid wastes. The apparatus is particularly but not exclusively useful in the treatment of contaminated soil and ground water, by a process known as "bioremediation.

That is, decontamination of soil and water by natural processes.

In the past, bioremediation was carried out by socalled "landfarming" techniques. Contaminated soil and sludges are mixed with nutrients and tilled into uncontaminated soil. However, there are a number of drawbacks to this process: large areas of land are required, making it uneconomical for farmers; native microbiological flora work most efficiently at decontaminating the soil and sludge at temperatures of around 250C making this type of process unsuitable in many areas of the world during winter months. It is undesirably slow, due to the cold ambient temperature.

In order to overcome this temperature problem, bioremediation has been carried out in "windrows" where contaminated soil is mixed with nutrients and formed into long heaps or piles which heat up due to microbial activity and maintain warmth due to the insulation of the biomass in the piles. However, aerobic conditions are necessary in order to permit certain microbes to break down the contaminants and a variety of techniques have been employed to maintain sufficient oxygen levels within the windrows. These techniques include forcing air through the windrows and turning the windrows periodically using composting machinery. Unfortunately, while this is efficient, it has the disadvantage of being costly and labour intensive.

Another disadvantage of using windrows is that water and contaminants tend to drain to the base of the windrows, resulting in saturated and anaerobic zones in the base of the windrow. Furthermore, the windrows are generally open to the environment, which is undesirable as children or vandals have easy access to contact and disturb the contaminated soil mixture. Tarpaulins may be used to cover the windrows, to prevent access to or spillage of the soil and also prevent volatilisation of hydrocarbons. However the tarpaulins need to be anchored in some manner, to the ground. Moreover, windrow treatment in confined situations such as petrol station sites may be unfeasible due to the lack of space and the insecure nature of the windrow.

Containerised bioremediation systems have been developed, to overcome or alleviate some of the above problems. Such systems generally use metal waste disposal containers. However, due to the solid nature of the walls of these containers, complicated and expensive drainage and aeration systems are required for efficient bioremediation. In general, conventional metal skips are specially adapted for the purpose of bioremediation and are then transported to the site where treatment is required. Transportation costs of these skips are considerable and because of the limited capacity of such skips, multiple skips are required for large volumes of soil, making them relatively ineffective for treating large volumes of soil as well as being expensive.

It is an object of the present invention to obviate and/or mitigate at least one of the above disadvantages by providing an easily transportable waste treatment apparatus suitable for the bioremediation of solid and liquid waste.

It is a further object to provide an easily transportable waste treatment apparatus formed from a kit of parts, the waste treatment apparatus being transported in a 'flat pack' arrangement and assembled on-site.

It is a further object to provide a liquid treatment method which involves recirculating liquid through the waste treatment apparatus until the liquid is sufficiently decontaminated.

It is yet further object to provide a method for decontaminating solid and/or liquid waste contaminated by polyaromatic hydrocarbons such as polychlorinated biphenyls (PCBs).

This is achieved by providing a waste treatment apparatus comprising a collapsible container through which air and water may pass, wherein a suitable environment for aerobic bioremediation of solid and for liquid waste is provided.

The apparatus is used to treat for example, environmentally unsound and/or waste products, into products which are not deleterious to the environment and which may have useful properties. An example is the conversion of harmful hydrocarbons in a contaminated soil, into carbon dioxide and water. This renders the soil suitable for re-use.

The present invention provides a waste treatment apparatus for treating contaminated soil and/or liquid waste comprising a collapsible container having a plurality of interconnecting panels at least some of which are perforated to permit the passage of air, the panels being adapted to be assembled to form a housing for receiving soil to be treated and being adapted to be disassembled and collapsed to form a flatpack arrangement to facilitate transportation.

Preferably the apparatus further includes a perforated base for supporting the soil above ground level for allowing air to circulate underneath the container and to allow adequate drainage therefrom.

Preferably the perforated base is a nonbiodegradable textile or other permeable material which is frequently plastic with a high internal surface area.

For example, this may be a material similar to a plastic pan scourer. Alternatively, it may be a fibrous mat.

The perforated base material may be rigid or flexible as required and, if flexible, can be rolled up.

Alternatively, if rigid, may be in the form of panel sections which may be interlocked with similar base sections. The perforated base, whether flexible or rigid, may be configured to engage or interlock with the side panels or can simply act as a base supporting layer.

The base may be composed of several sections or parts which can be rolled out similar to launch strips or interconnected like plastic tiles with suitable adjacent key ways.

The perforated base may be a separate panel adapted to be spaced above ground level for supporting the soil and allowing air to circulate underneath the container and to allow adequate drainage therefrom. The panel may be interlocked with the side panels and may also be rigid or flexible.

Conveniently also a flexible base can be used as an intermediate layer in a soil treatment pile for facilitating air flow and drainage throughout the pile.

This would be a convenient additional use of a perforated permeable base material such as that of a plastic pan scourer-type material. The flexible fibrous plastic material could, in addition to being used as a base or intermediate layer, also be used to wrap the soil pile and facilitate drainage and aeration. The perforated or permeable non-biodegradable material could also be used as flexible side panels in a structure similar to that shown in Fig. 9 of the drawings.

Preferably the apparatus further comprises a walled tray upon which the assembled container is positioned.

In some instances the degree of aeration required internally in the container can be more than that required in the peripheral regions thereof. In such instances, the apparatus further includes at least one perforated aeration tube, which is capable of providing additional aeration internally to the container. The interconnecting panels can be adapted such that the aeration tube or tubes pass through apertures in the panels. For instance, apertures in opposed wall panels can be aligned so that a tube can extend completely through the container. The perforated panels and the aeration tube or tubes can also serve to help maintain the interior of soil in the container at a suitable temperature by venting excess heat generated outside the container, or by drawing in cooler air from outside the container by convection.Operating temperatures of between 150C-350C are preferred, but particularly in the range of 200C-300C.

An assembled container may be any suitable size and shape e.g. drum shaped, box shaped and the like.

Containers with a volume of 5m3-25m3 are preferred, and containers with a volume of 10m3-20m3 most preferred. The container may be positioned adjacent to at least one further container, either horizontally or vertically, thereby allowing many such containers to be positioned in a small area. Preferably the container is of a cubic or cuboid shape.

The panels of the container are connectable elements and may be made of metal, a strong rigid plastic material, such as high density polyethylene, or a strong flexible plastic material. In a preferred embodiment, the panels are rigid open mesh panels. Typically, the mesh size of the panels is selected so as to facilitate lightness and ease of transport, whilst at the same time, minimising the passage of soil thorough the panels.

Consequently, the mesh size may be selected depending on the particular properties of the contaminated soil being treated. For example, a larger mesh size may be utilised for treating a heavy clay, whereas a finer particulate soil may require a smaller mesh size. The container is transported in a disassembled form to minimise storage area and the panels are of such a size that they are readily handled by one or two operators and rapidly assembled on site with appropriate locking means to form a container for receiving waste to be treated.

The panels of the container can be interconnected by any suitable locking means known in the art. For example a plurality of elongate members may be used to support and/or interconnect the panels, one elongate member may contact two panels and be bolted or fixed thereto.

Alternatively the panels may have apertures, through which a locking-bolt or locking-strap may be fitted. The wall panels may each be separate and may require connecting to one another. Alternatively, the wall panels may be hinged together in some manner.

The means for spacing the base panel of the container above the ground may be any suitable means.

Typically this may be blocks, upon which the container rests. Alternatively the wall panels can be of such a length that the base panel can be clipped part way up the wall panels and still therefore be spaced above the ground level. Spacing the base panel of the container above the ground level is essential, as it allows air to circulate underneath the container and to pass into the container through the perforations in the base panel. It also ensures that liquid which may pass through the container does not become trapped, but penetrates thorough the base panel and onto the ground or the tray if present. If the tray is used, liquid passing through the container may be collected by the tray. The liquid can then be subjected to further treatment, either by passing back through the container or by passing through a separate trickling filter.

Thus in a further aspect of the present invention provides a method of treating liquid contaminated with organic contaminants comprising the steps of: a) disposing a volume of porous material mixed with microorganisms in a first location, said microorganisms capable of metabolising said organic contaminant, b) draining said liquid through said porous material, so that said microorganism metabolise said organic contaminant, and c) collecting treated liquid in a second location and analysing the liquid to determine if said liquid has reached a predetermined level of decontamination.

If said liquid has not reached the predetermined level of purity then preferably steps b) and c) are repeated until said liquid reaches the predetermined level.

Contaminated liquid suitable for treating includes ground water associated with contaminated soil and also pond, lake, and river water which may be contaminated and spent sheep dip.

Suitable porous material can include soil, contaminated or otherwise and also sand which may or may not be seeded with bacteria adapted to treat the liquid waste. Also, wood chips, sawdust seeded with fungal stains capable of degrading recalcitrant organics which cannot be broken down by the soil's indigenous, microbiota.

Analysing of the drained liquid may be carried out manually, on-site, or samples taken away for analysing in a laboratory. Alternatively an automated system may be provided. Such a system would analyse the liquid waste and recirculate the liquid waste back through the apparatus until the liquid reaches the required level of decontamination. In this manner a closed-loop system may be formed.

The required level of purity for any given contaminant is usually determined by regulatory authorities and is normally represented in parts per million (ppm). For example in the U.K., ICRCL guidelines from the Government are used as a guide.

Spacing the base panel of the container above the ground also provides a space under the container into which further suitable waste treatment devices, may be placed. Suitable devices include; compost for providing heat to the container and porous supports containing fixated bacteria, for purifying contaminated liquid.

Alternatively solid waste material not suitable for placing in the container (e.g. large rocks) may be placed in the gap between the tray and the base panel of the container and be washed by water passing through the container.

Solid waste suitable for treating in the apparatus of the present invention, includes soil contaminated by hydrocarbons (for example oils, polyaromatic hydrocarbons and the like). Other soiled waste particularly sewage, sludge and food waste may also be treated.

It is known that certain white rot fungi such as Phanaerocytae Chrvsosorium can produce enzymes capable of breaking down contaminants such as polyaromatic hydrocarbons. However, the organism requires nitrogen for growth, but only secretes the desired enzyme when in a nitrogen deficient environment. Thus, it is impractical to mix contaminated soil with compost or other organic material, to heat up the soil and stimulate microbial activity in order to improve contaminant breakdown, because the normally high nitrogen content of compost prevents the fungus releasing the desired enzyme.

Thus in a further aspect, the present invention provides an aerobic apparatus comprising a soil compartment and separate compost compartment, arranged to prevent or minimise mixing of the soil and compost; and heat transfer means coupled between the soil and compost compartment for transferring heat from the compost to the soil.

Preferably the soil compartment is located above the compost compartment and the heat transfer means extend substantially vertically.

Alternatively the soil compartment is adjacent the compost compartment and the heat transfer means extend transversely. Conveniently the heat transfer means are pipes.

There is also provided a method of treating soil contaminated with polyaromatic hydrocarbons, said method comprising the steps of: a) disposing a volume of nitrogen deficient contaminated soil mixed with microorganisms, to be treated in a first location, said microorganisms being enzymically active in the absence of nitrogen at a predetermined temperature or range of temperatures.

b) disposing a volume of compost for generating heat, in a second location, substantially separate from said soil mixture, and c) conveying said generated heat through said soil so as to raise the temperature of said soil to a level sufficient to activate said microorganisms to release a sufficient quantity of an enzyme into said contaminated soil mixture to breakdown said contaminants.

Preferably the method comprises disposing the contaminated soil mix above the compost and transferring heat vertically in a plurality of parallel heat paths.

This and other aspects of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partial cut away isometric-type view of an assembled container of a preferred embodiment of the present invention; Figure 2 is a view similar to Figure 1 of part of a kit of parts for a container of the present invention; Figures 3-7 are diagrammatic side elevations of container apparatus according to various embodiments of the present invention; Figure 8 shows a diagrammatic view in perspective of apparatus according to a further embodiment of the present invention;; Figures 9a and 9b show diagrammatic side and isometric elevations respectively of an apparatus according to a yet further embodiment of the present invention, and Figures 10a, 10b and lOc depict further embodiments of apparatus according to the present invention.

Reference is first made to Figure 1 of the drawings which illustrates an apparatus 10 comprising a collapsible container 12 positioned above a walled waste collecting tray 14 by supporting blocks 16. The container 12 is filled with hydrocarbon contaminated soil 18, through which aeration tubes 20, 22 have been positioned.

The container 12 is formed from four interconnecting wire mesh wall panels 24, 26, 28, 30 and one wire mesh base panel 32. There are two equal sized side panels 24, 28 and two equal sized end panels 26, 30. The wall panels 24, 26, 28, 30 and the base panel 32 are connected and fixed together by locking pins (not shown) to form the container 12 as shown in Figure 1. The wire mesh wall panels 24, 26, 28, 30 are plastic coated to minimise corrosion and have a mesh size or spacing of 5 cm. The base panel 32 has a smaller mesh size (2 cm) so that contaminated soil does not fall through the mesh openings.

Opposing apertures 34, have been formed in walls 24, 28. The apertures 34, are sized and shaped to fit the aeration tubes 20. The tubes are fitted through the apertures 34 of wall 24 and passed through the inside of the container 12 and out through the apertures 34 of wall 28. In this manner the tubes 20 extend between and beyond the walls 24, 28. Opposing apertures 36 have been formed in walls 26, 30. The apertures 36 are sized and shaped to receive aeration tube 22. The tube 22 is fitted in the same manner as tube 20, but extending through walls 26, 30. Air from outside the container 12 passes into and along the aeration tubes 20, 22. The air then passes into the inside of the container 12 by way of a plurality of slot perforations 38.

For ease of transportation, the collapsible container 12 is transported disassembled or in a collapsed state. That is, components such as the wall panels 24, 26, 28, 30 and the base panel 32 are not connected together, enabling them to be stacked flat, upon one another. The container 12 is then assembled on site.

Figure 2 shows in some of the components required to assemble the container 12. One of the two end panels 30 is shown, together with one of the two side panels 28.

The base panel 32 is shown also. Adjacent panels such as 28, 30 are connected together by two plug locking members 33 and locking pins 35. The plug locking members fit into holes 37 formed in the panels and are secured by locking pins 39. The locking pins are shaped so as to connect two panels together (for instance side panel 28 and end panel 30), or three panels together (for instance side panel 28, end panel 30 and base member 32). In order to assemble the container 12 shown in Figure 1, a kit of parts containing; two end panels 26, 30, two side panels 24, 28, one base member 32, eight plug locking members and twenty locking pins 35, is required.

Container size is dependent on the space available on a particular site and upon an amount of contaminated waste to be treated. The container shown in Figure 1 has measurements of 2x2x4 metres, enabling upto 16m3 of solid waste to be treated, however smaller or larger containers may be constructed.

Once on site the container 12 is assembled and the apparatus constructed. The waste collecting tray 14 is placed on the ground and the assembled container 12 placed upon the supporting blocks 16, within the confines of the tray 14.

The assembled container is filled with soil 18 contaminated with hydrocarbons. The soil 18 has been previously mixed with a composting material (e.g. spent mushroom compost or horse manure) which adds structure for aeration and supplies nutrients. This forms what is termed as a "bio-pile". Heat is quickly generated as the easily available carbon in the compost is utilised by both the compost microorganisms and the soil microorganisms. The heat generated increases microbial activity, quickly creating a vast population of microorganisms. The temperature of a bio-pile (soil and compost) may be checked periodically to ensure that the bio-pile is within the most preferred temperature range (200C-300C). It is important that the temperature is not too low (e.g. 150C), as the treatment process would proceed to slowly. It is also important that the temperature is not too high, (e.g. 550C) since this can kill off the microorganisms in the bio-pile.

The bio-pile temperature is controllable by the number of aeration tubes passing through the soil.

Addition of extra aeration tubes will vent some of the heat produced from the container and removal of aeration tubes, will increase the temperature of the bio-pile.

Once the readily available carbon in the compost has been utilised, the increased population of microorganisms in the bio-pile then turn to utilising the carbon in the hydrocarbon contaminant, transforming the hydrocarbon contaminant into water and carbon dioxide.

Contaminated water present in the soil drains through the bio-pile and through the perforated base panel 32 of the container 12, onto the tray 14. This water is collected and treated further elsewhere, or preferably recirculated to the top of the bio-pile and allowed to drain into the biopile, using a perforated tube or perforated plastic sheeting. The microorganisms present within the bio-pile act upon the contaminated water to decontaminate it. In this manner a closed loop system is formed, continually recirculating the contaminated water through the bio-pile, until it reaches a suitable level of decontamination.

The entire process for treating contaminated soil and ground water takes a period of weeks, for example, some two to three weeks or more or less, depending on the environmental conditions of the bio-pile (e.g. aeration, numbers of bacteria and temperature etc).

If the apparatus is to be used for treating only contaminated water then the apparatus is used as a trickling filter device. The container is filled with a material (e.g. sand) seeded with microorganisms capable of utilising the contaminant, to form the bio-pile.

Contaminated water is drained/trickled through the material, as described above, and collected by the tray 14 underneath the container 12. The water is analysed to check for contaminants and recirculated though the biopile, if necessary.

Figures 3-7 show various embodiments of the apparatus and methods of the present invention. Figures 3-7 show an apparatus 40 comprising a container 42 filled with contaminated soil 44 raised upon supporting blocks 46 and positioned within the confines of a tray 48. An air space 50 is formed underneath the container 42 and this air space 50 is utilised in a number of ways.

Figure 3 displays drainage guttering 52 which is used to collect water draining from the soil 44. Figure 4 shows additional stacked base units 53 which are packed with bacteria fixed on a mineral support. Partially treated water draining from the container 42 permeates into and drains slowly through the base units 53 wherein the bacteria act upon the water to further decontaminate it. A similar process is shown in Figure 5. Here, contaminated rocks 54 which have been separated from the contaminated soil 44 are piled with the air space 50 and upon a base unit 53. Water draining from the soil 44 acts to wash the rocks 54 and remove any contaminants attached thereon. The water drains through the base unit 46 and is collected by the tray 48. The water is then analysed as before and recirculated through the bio-pile if not sufficiently decontaminated.Figure 6 shows a trickling sand filter 56 positioned within the air space 50. This trickling sand filter 56 is seeded with bacteria adapted to decontaminate the draining liquid.

A particularly preferred embodiment of the present invention is for the treatment of soil contaminated with certain organic compounds such as polyaromatic hydrocarbons (e.g. PCB). Figure 7 shows a structure for achieving this. Compost 58 is separated from the contaminated soil 44 by placing in the air space 50 beneath the container 42. A plurality of pipes 60 extend from the soil to the top of the compost 58. The pipes 60 prevent exchange of soil 44 and compost 58 but allow passage of air.

The microbial activity of the compost 58 generates heat which is channelled through the heating pipes 60 into the soil 44 which is seeded with white rot fungus (e.g. P. chrysosporium). The activity of the white rot fungus increases, but due to the fungus being in a nitrogen deficient environment, and at an appropriate temperature, enzyme is released from the white rot fungus, which in turn facilitates the breakdown of the polyaromatic hydrocarbons within the soil.

Figure 8 shows an embodiment for decontaminating soil contaminated with recalcitrant organic compounds, using two containers. The first container 62 provides a trickling san filter 63 which is seeded with a microbe known to de-contaminate the recalcitrant organic compounds. The second container 64 is filled with soil 44 contaminated by the recalcitrant organic compound.

Liquid drains from the soil and is collected by guttering 66. The liquid is then transferred by a pump 68 to the top of the first apparatus 62 and allowed to drain therethrough. The liquid is again collected by guttering 70 and allowed to wash through the second container 64.

This forms a loop system whereby the water washes the soil 44, removing some of the organic compounds. The organic compound contaminated liquid is in turn decontaminated by the trickling sand filter 63 and returned to wash the soil 44. The circulating loop process proceeds until the soil 44 has been decontaminated.

Figures 9a and 9b show a container 12 comprising flexible perforated sheeting panels 72 and non-perforated panels 73 rather than rigid panels. The flexible sheeting 72, 73 is fixed and secured to upright supports 74 which form the cuboid frame of the container 12. This embodiment provides an extremely versatile container assembly, as the flexible sheeting is particularly easy to transport and can be cut to size on site. A combination of perforated and non-perforated panels can be used to provide a container adapted to accommodate a variety of soil mixtures and weather conditions. For example, non-perforated panels could be located transverse to a prevailing wind to minimise soil loss and soil drying.

Reference is now made to Figures 10a, of the drawings which depict an alternative use of the perforated panels in a windrow base. In this case a conventional windrow 80 is disposed on top of a perforated base 82 made from perforated top and side panels 84, 86 to facilitate windrow aeration and drainage. It will be understood that the side panels need not be perforated but in such a case the top panel is perforated and extends outside the boundary of the windrow to form a perforated margin 88 which facilitates soil aeration. As shown in Figure 10a the base 90 can be formed of a raft of perforated drainage pipe 92 held in a perforated frame 94.

It will be clear to those of skill in the art that the above described embodiments are merely exemplary of the present invention and that various modifications and improvements may be made thereto without departing from the scope of the invention. These may include covering the container to prevent the escape of volatile hydrocarbons from the waste, or providing forced aeration and/or heating to the container. A suction system may be provided for stripping volatile contaminants from the waste.

A further modification to improve aeration is to 'seed' the soil or soil/compost mixture with many small containers which have perforations to define structures which have a volume of "air sacs", which can be used to aerate the soil/compost mixture. The perforations are small enough to minimise soil/compost ingress. The air sacs are distributed throughout the soil/compost mixture to supply air to the microorganisms. The air sacs can be provided by any suitable means, such as a honeycomb or open-cell structure but a particularly convenient way is to use plastic golf balls which are corrosion resistant and which are of the right dimensions. The golf balls can be added to the compost at the time it is mixed with the soil and once the soil has been decontaminated the mixture can be passed through a screen to remove the golf balls for reuse.It will also be understood that the perforated base can be any suitable non-biodegradable textile or other permeable material with a high internal surface area. As disclosed above, this permeable material may be a fibrous plastic such as a plastic pan scourer-type of material and it may also be a fibrous mat. As also mentioned above, it could be rigid or flexible and, if flexible, it could be easily rolled up for storage and, if rigid, may consist of a plurality of small interlocking units which can be interlocked together to form a rigid type of base structure to support the interconnecting side panels. The main thing about the base structure is that it can be of any suitable material as long as it allows aeration of the soil treatment pile and adequate draining from the sole treatment pile.Thus, the base material in some embodiments has been formed from a trickling filter, rocks, perforated pipes and the like.

It can be seen from the foregoing description that the present invention provides a number of advantages over the prior art. The invention provides a collapsible container which may be easily transported from site to site without requiring specialised lorries for transportation. The invention provides an aerobic environment where bioremediation is carried out which does not become saturated with water and which can easily be maintained at an optimum temperature.

A further advantage is that the units or containers can be readily assembled on site and can be stacked or extended readily to accommodate soil from a variety of site sizes. The fact that the units are collapsible means that they can be assembled in confined spaces and no specialist transport or structures are required to locate them in difficult sites. The fact that different mesh sizes can be used, means that the containers can be selected to be used with soils of different properties and a common basic structure can be used with a number of varieties of base to provide particular treatment for different soil contaminant situations. The fact that meshes are used, means that the structure can incorporate a bio-pile for treating contaminated water in addition to soil and in an automated system recirculation of the contaminated water or fluid can be used to provide a "green light" to an operator to determine as soon as the contaminated soil in the container is decontaminated. A further advantage of the arrangement is that it can be readily assembled by unskilled labour and without specialist equipment.

Claims (29)

1. A waste treatment apparatus for treating contaminated soil and/or liquid waste comprising a collapsible container having a plurality of interconnecting panels at least some of which are perforated to permit the passage of air, the panels being adapted to be assembled to form a housing for receiving soil to be treated and being adapted to be disassembled and collapsed to form a flatpack arrangement to facilitate transportation.

2. A waste treatment apparatus as claimed in claim 1 including a perforated base for supporting the soil above ground level for allowing air to circulate underneath the container and to allow adequate drainage therefrom.

3. A waste treatment apparatus as claimed in claim 2 wherein the perforated base is a non-biodegradable permeable or other permeable material with a high internal surface area.

4. A waste treatment apparatus as claimed in claim 2 or claim 3 wherein the perforated base is flexible.

5. A waste treatment apparatus as claimed in any one of claims 2 to 4 wherein the perforated base is rigid.

6. A waste treatment apparatus as claimed in claim 5 wherein the perforated base is a rigid panel adapted to be coupled to the interconnecting panels.

7. A waste treatment apparatus as claimed in any one of claims 2 to 4 wherein the perforated base is a textiletype material which is flexible and which can be rolled out to form a flat support surface in use and which can be rolled up when not in use to facilitate storage.

8. A waste treatment apparatus as claimed in any one of claims 2 to 7 wherein the flexible perforated base can also be used as an intermediate layer in the soil treatment pile to facilitate soil aeration and draining throughout the treatment pile.

9. A waste treatment apparatus as claimed in claim 2 or claim 3 wherein the perforated base consists of a plurality of interconnecting elements adapted to be coupled together to form a base structure for supporting the contaminated soil pile.

10. A waste treatment apparatus as claimed in claim 1 or claim 2 including a walled tray upon which the assembled container is positioned.

11. A waste treatment apparatus as claimed in any preceding claim wherein said apparatus further includes at least one perforated aeration tube, for providing additional aeration internally to the container.

12. Apparatus as claimed in any preceding claim wherein the interconnecting panels have at least one aperture for receiving said aeration tube for insertion into container.

13. A waste treatment apparatus as claimed in claim 12 wherein apertures are disposed in opposed wall panels for alignment for receiving an aeration tube such that the tube extends completely through the container.

14. A waste treatment apparatus as claimed in any preceding claim wherein said interconnecting panels are rigid, open mesh panels, said panels having a mesh size selected to facilitate lightness and ease of transport whilst minimising the passage of soil through the panels.

15. A waste treatment apparatus as claimed in any preceding claim wherein said panels are interconnected by locking means in the form of a plurality of elongate members, each elongate member being adapted to be secured to two panels.

16. A waste treatment apparatus as claimed in any one of claims 1 to 14 wherein said interconnecting panels have apertures for receiving a locking bolt or locking strap by which the panels may be coupled to each other.

17. A waste treatment apparatus as claimed in any one of claims 1 to 14 wherein the interconnecting wall panels are hinged together whereby the panels can be folded to a relatively flat position for transport and pivoted to a spaced position to form a container volume.

18. Apparatus as claimed in any one of claims 2 to 17 wherein the means for spacing the base panel of the container above ground is provided by a plurality of block members upon which said container rests.

19. A waste treatment apparatus as claimed in any one of claims 2 to 17 wherein said means for spacing the base panel for container above the ground is provided by making the wall panels of such a length that the base panel is clipped partly up the wall panels and therefore is spaced above the ground level.

20. A method of treating liquid contaminated with organic contaminants comprising the steps of: a) disposing a volume of porous material mixed with microorganisms in a first location, said microorganisms capable of metabolising said organic contaminant, b) draining said liquid through said porous material, so that said microorganism metabolise said organic contaminant, and c) collecting treated liquid in a second location and analysing the liquid to determine if said liquid has reached a predetermined level of decontamination.

21. A method as claimed in claim 20 wherein if said liquid has not reached the predetermined level of purity then preferably steps b) and c) are repeated until said liquid reaches the predetermined level.

22. A method as claimed in claim 20 or claim 21 wherein the treated liquid is analysed and, once analysed, is circulated back through the apparatus until the liquid reaches a required level of decontamination.

23. A method as claimed in any one of claims 20 to 22 wherein further waste treatment devices are placed in the space beneath the container, said devices including compost for providing heat to the container and porous supports container fixated bacteria for purifying contaminated liquid.

24. A method as claimed in any one of claims 20 to 22 wherein solid waste material not suitable for placing in the container is placed in the gap between the tray and base panel of the container for washing by water passing through the container.

25. An aerobic apparatus comprising a soil compartment and separate compost compartment, arranged to prevent or minimise mixing of the soil and compost; and heat transfer means coupled between the soil and compost compartment for transferring heat from the compost to the soil.

26. An apparatus as claimed in claim 25 wherein the soil compartment is located above the compost compartment and the heat transfer means extend substantially vertically.

27. Apparatus as claimed in claim 25 or claim 26 wherein the soil compartment is adjacent the compost compartment and the heat transfer means extend transversely.

28. A method of treating soil contaminated with polyaromatic hydrocarbons, said method comprising the steps of: a) disposing a volume of nitrogen deficient contaminated soil mixed with microorganisms, to be treated in a first location, said microorganisms being enzymically active in the absence of nitrogen at a predetermined temperature or range of temperatures.

b) disposing a volume of compost for generating heat, in a second location, substantially separate from said soil mixture, and c) conveying said generated heat through said soil so as to raise the temperature of said soil to a level sufficient to activate said microorganisms to release a sufficient quantity of an enzyme into said contaminated soil mixture to breakdown said contaminants.

29. A method as claimed in claim 28 further comprising the step of disposing the contaminated soil mix above the compost and transferring heat vertically in a plurality of parallel heat paths.