GB2337690A

GB2337690A - Absorbing pollutants from surfaces

Info

Publication number: GB2337690A
Application number: GB9912140A
Authority: GB
Inventors: John Denby Downing
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-05-30
Filing date: 1999-05-26
Publication date: 1999-12-01
Also published as: GB9912140D0; GB9811601D0

Abstract

A method of separation from non-pollutants of a fluid pollutant in a container or on an area of land or water involves the taking up the pollutant by particulate material (11) contained in permeable enclosed body (12). For oil spills, the particulate material (11) may be carbon black containing rubber. The enclosed body (12) is preferably strands (13) of a synthetic polymer material formed into a matrix (13) by a textile process such as stitch bonding, adhesive or thermo bonding, and the whole constructed as a mat, but for certain applications a perforated and rigid container or flexible bag may be used. The enclosed body (12) is deployed in a polluted area such as the sea and may be recovered from its operational location, and treated by a mangle (43) and/or scourer (44) to remove taken-up pollutant and to restore absorbency to the enclosed body (12) for re-use. Solid surfaces such as floors, roadways, tanks, and ships bilges may also be treated in this way. [Figs 2, 4 not shown].

Description

POLLUTANT SEPARATION 1 2337690 This invention relates to the separation

from non-pollutants of a fluid pollutant in a container or on an area of land or water. Such separation is desirable in cases where container is, for example, a tank or a ship's bilge, or where the area of land or water is a landfill site, a factory or garage floor, a roadway, a lake, a dock or harbour, a lake or river or the sea. In many such cases the pollutant concemed is oil, but in some cases other pollutants may be involved.

WO 92114002 proposes the use of particulate rubber to absorb oil pollution from polluted water, the rubber particles being discharged into the polluted water and contained within a cage-like construction of floats and depending netting from which the particles may, after taking up typically three times their weight of oil, be harvested by suction for reprocessing to remove the pollutant. The proposal has merit insofar as a) the particulate rubber is readily available and is a waste product of various processes for which there are few recycling or utilisation routes, and b) it is particularly effective at absorbing oil but not water. The use of loose rubber particles may also be useful in the case of a small oil spills on the ground, for example from leaking machinery or motor vehicles, instead of using sand or sawdust. However the method of WO 92114002 of deployment and harvesting the rubber particulates is cumbersome and correspondingly expensive, and not generally suitable for all pollution situations such as unnavigable waterways, tidal areas, heavy weather and most larger land based situations.

It is an object of the present invention to provide a method of separation of a fluid pollutant from the non-pollutants that is not so cumbersome and expensive and which can extend to areas and situations where the above described proposal would experience difficulties.

The invention provides a method of separation from non-pollutants of a fluid pollutant in a container or on an area of land or water, comprising taking up the pollutant by particulate material comprised in permeable enclosed body form.

The particulate material may be rubber. Used as free particles as taught in WO 92114002, the rubber can take up some three times its own weight of oil pollutant. Surprisingly, rubber particles can be restrained in a permeable enclosed body without adversely affecting their ability to take up oil preferentially to water for high efficiency pollution control. The rubber particles may contain carbon black, a formulation as prescribed in WO 92114002 is suitable.

2 The enclosed body may comprise a perforated sheet or a matrix of strand material confining the particulate material. The enclosed body may comprise metal, natural fibres or a synthetic polymer material such as, for example polyester, polypropylene or polyamide. The enclosed body may be of a hydrophobic material. The enclosed body may be constructed by a textile fabrication technique such as woven mesh or by a non-wovens technique, for example, stitchbonding or an adhesive or thermo-bonding technique, any of which can produce a structure into which the particulate material is integrated within the structure yet accessible to the pollutant.

The enclosed body may be in the form of a mat of elongate shape having a width substantially greater than its thickness and substantially less than its length, and may be deployable from a rolled or folded stowed configuration into an operational configuration for the pollutant take-up period and recoverable into the stowed configuration. Alternatively the enclosed body may be in the form of a cuboid or spheroid body, which may have a closable opening for filling with and removal of the particulate material.

The enclosed body, when recovered from its operational location, may be treated to remove taken-up pollutant and to restore absorbency to the enclosed body for re-use. The pollutant may be removed by mangling, by heat treatment or by a washing treatment using a detergent- The enclosed body may have a density lower than water, and bodies for use in salt water may have a density greater than those for use in fresh water. The density of the body may be controlled or compensated for by added flotation.

A plurality of bodies of mat formation may be disposed adjacent each other to form successive filters. Successive mats may have differing thicknesses andlor densifies. The mats may be housed in a container, which may have an inlet for polluted fluid and an outlet for fluid from which pollutant has been removed.

Methods according to the invention of separation from non-pollutants of a fluid pollutant in a container or on an area of land or water will now be described with reference to the accompanying drawings, in which:

Fig. 1. is a diagrammatic cross-section of one construction of mat, Fig. 2 is a diagrammatic illustration of the structure of another construction of mat, Fig. 3 is a diagrammatic view of a mat construction for use in the method of the invention, 3 Fig. 4 is a diagrammatic illustration of a method of deployment/recovery of a mat secbon according to the invention, Fig. 5 is a diagrammatic illustration of an alternative method to that of Fig. 4, Fig. 6 is a diagrammatic illustration of a method of using mats as a filter, Fig. 7 is a diagrammatic illustration of an alternative filtraton method, and Fig. 8 is a diagrammatic illustration of another alternative filtration method.

The drawings illustrate methods of the separation from non-pollutants of a fluid pollutant in a container or on an area of land or water, such as the separation of oil from water, by particulate rubber 11 comprised in a permeable enclosed body 12. In Figs. 1 to 6, the enclosed body 12 is in the form of a mat, which may have a density lower than that of water in which it is intended to be used so that it will float. It is advantageous if the buoyancy is nearly neutral so that in use most of the mat 12 is submerged. Clearly a mat 12 for use in sea water can be more dense than one for use in fresh water.

The mats 12 comprise a matrix of strand material 13 confining the particulate rubber 11. The strand material 13 imparts coherence, stability strength and shape for purposes of handling and processing the mat 12. The strand material 13 may be of synthetic polymer such as continuous filament polyester, polypropylene or polyamide, although natural fibre strands or metal wires may be used instead. The strands 13 may be of hydrophobic material which may pass pollutant differentially through to the contained particles to accelerate take-up.

The fabrication technique used in the mat 12 of Fig. 1 is a stitch bonding technique in which the longitudinal threads 14 are sewn in chain sfitch formaflon along parallel lines with laid-in transverse threads 15.

Fig. 2 illustrates in cross-section an adhesive or thermo- bonded fabric 13 in which the rubber pardcles 11 are contained in a matrix of warp threads 14 and weft threads 15, the components 11, 14 and 15 of the mat 12 being connected to each other by adhesive bonds 16 which may have been produced by, for example, a spray-on adhesive or by melting adhesive particles or low melting point fibres using hot air or rollers. These techniques are used conventionally to make textile fabrics of various weights. A mat 12 of strand material 13 of the weight required for cleaning up oil slicks will be usually of much heavier gauge than conventional textile fabrics and may need to be made on specially constructed machinery to such gauge in a single layer, or as shown in Fig. 3, laminated from multiple layers L of thinner fabric. Since fabrication and particularly lamination should not form any barrier to penetration by oil, in pollution problems 4 often 'heavy' oil with high viscosity especially at sea temperatures, the structure of the fabric 13 should be as open as possible consistent with retention of the particles 11 Usually with textile material fabrication processes, fabric 13 can be made on a substantially continuous basis to a predetermined width dictated by the size of the available machinery. Hence the mat 12 is preferably made in strip form, say 1 metre wide, a few centimetres thick and tens, if not a hundred or more, metres long. Such a mat 12 can, as seen in Fig. 4 be wound on a reel 41 and deployed therefrom into the water 40 where it may be left for a time sufficient to take up a much pollutant as possible, and then be recovered to be wound on the same reel 41 after passing through a treatment station 42 comprising a mangle 43 to squeeze out a major proportion of the taken-up pollutant followed by a washing plant 44 for a detergent-based scouring- The rewound mat 12 is then ready for deployment in the same or some other polluted area. Altematively, one or more mats 12 may be anchored in moving water 50 or towed as shown in Fig. 5 to remove pollutant from a river, lake or sea 50. In this case the mats 12 depend from a support 51 into the water 50 as it flows past them in the direction shown by arrow F due to the relative motion of the water 50 and the support 51. In this case the mats 12 comprise a metal or plastic cloth mesh 13 enclosing the particulate material 11.

In Fig. 6, several mats 12 are disposed one above another in a container 61 to provide a filter arrangement for polluted liquid 62. In this case the polluted liquid 62 is fed by gravity or is pumped from its location, for example the interior of a sea- or road-going tanker 63, to an inlet 64, in this case the open top, of the container 61. An outlet 65 for liquid 66 from which pollutant has been removed is located at the bottom of the container 61. At suitable intervals the filter mats 12 may be removed from the container 61 and their pollutant absorbing capacity restored by mangling and or scouring as described above.

Whilst the permeable mat 12 format is practical and capable of rapid deployment and recovering in marine conditions, it is just an example of a number of ways in which particulate material can be deployed to control pollution. For example, such mats 12 may be used in a factory or garage environment for 'mopping-up' after a spillage of oil or other pollutant from a machine or storage container. Other novel and inventive arrangements include the use of perforated spherical or other shape rigid plastic containers of any convenient size depending on where they are to be used which can hold the particulate material loosely packed so that it is accessible to the pollutant but cannot escape through the perforations. Alternatively the containers may be perforated ncn-hgid bags to contain the particles 11, and to extend the bags to prevent the particles clogging together, rigid hoops or the like may be deployed inside the bags. Such containers can be deployed and harvested much in the manner of the loosely scattered particles of WO 92114002 but much more easily and efficiently, and they are more easily processed to retrieve the picked up contaminant. However such a container 12 may be deployed as shown in Fig. 7 in a grid 71 at the side of a road 72 to counteract the effect of an oil tanker spillage on the road 72.

In Fig. 8 there is illustrated a landfill site 80 which has been lined with a conventional lining of clay 81 or other suitable lining material and then with a second lining formed of mats 12 of one of the types of mat described above. A centrally disposed pipe 82 is used to pump polluted water from the site to a filter container of the type described in connection with Fig. 6 (item 6 1)- A further filter container 83 containing particles 11 is provided around the base of the pipe 82 to absorb pollutant as the polluted liquid is sucked into the pipe 82. The mats 12 absorb pollutant which would otherwise leach into the ground 84. The thickness of the mats 12 and capacity of the container 83 are chosen so that substantially all of the pollutant being deposited in the landfill site 80 is absorbed by the particles 11 in the mats 12 and container 83.

For pollutants other than oil, particles 11 of a material other than rubber may be used, and in such cases materials other than those referred to above may be used for the enclosed body 12.

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Claims

WHAT WE CLAIM IS

1. A method of separation from non-pollutants of a fluid pollutant in a container or on an area of land or water, comprising taking up the pollutant by particulate material comprised in permeable enclosed body form-

2. A method according to claim 1, wherein the particulate material is rubber.

3. A method according to claim 2, wherein the rubber particles contain carbon black.

4. A method according to any one of claims 1 to 3, wherein the enclosed body comprises a perforated sheet.

5. A method according to any one of claims 1 to 3, wherein the enclosed body comprises a matrix of strand material confining the particulate material.

6. A method according to claim 4 or claim 5, wherein the enclosed body comprises metal.

7. A method according to cJaim 5, wherein the strand material comprises natural fibres.

8. A method according to claim 4 or claim 5, wherein the enclosed body comprises a synthetic polymer material.

9, A method according to claim 4 or claim 5, wherein the enclosed body is of a hydrophobic material

10. A method according to claim 5, wherein the enclosed body is constructed by a textile fabrication technique.

A method according to claim 10, wherein the enclosed body comprises a woven mesh.

12. A method according to claim 11, wherein the enclosed body is constructed by a nonwovens technique.

13. A method according to claim 12, wherein the enclosed body is constructed by stitchbonding.

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14. A method according to claim 12, wherein the enclosed body is constructed by an adhesive technique.

15. A method according to claim 12, wherein the enclosed body is constructed by a thermo-bonding technique.

16. A method according to any one of claims 6 to 15, wherein the enclosed body is in the form of a mat of elongate shape having a width substanfially greater than its thickness and substantially less than its length.

17. A method according to claim 16, wherein the mat is deployable from a rolled or folded stowed configuration into an operational configuraflon for the pollutant take-up period and recoverable into the stowed configuration.

18 A method according to any one of claims 6 to 15, wherein the enclosed body is in the form of a cuboid or spheroid body.

19. A method according to claim 18, wherein the body has a closable opening for filling with and removal of the particulate material.

20. A method according to claim 1, wherein the enclosed body is recovered from its operaflonal location, and is treated to remove taken-up pollutant and to restore absorbency to the enclosed body for re-use.

21. A method according to claim 20, wherein the pollutant is removed by mangling.

22. A method according to claim 20, wherein the pollutant is removed by heat treatment.

23. A method according to claim 20 or claim 22, wherein the pollutant is removed by a washing treatment using a detergent.

24. A method according to any one of claims 1 to 23, wherein the enclosed body has a density lower than water.

25. A method according to claim 24, wherein bodies for use in salt water have a density greater than those for use in fresh water.

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26. A method according to claim 24 or claim 25, wherein the density of the body is controlled or compensated for by added flotation-

27. A method according to claim 16 or any claim dependent thereon, wherein a plurality of bodies of mat formation are disposed adjacent each other to form successive filters-

28. A method according to claim 27, wherein successive mats have differing thicknesses.

29. A method according to claim 27 or claim 28, wherein successive mats have differing densities.

30. A method according to any one of claims 27 to 29, wherein the mats are housed in a container.

31. A method according to claim 30, wherein the container has an inlet for polluted fluid and an outlet for fluid from which pollutant has been removed.

32. A method of separation from non-pollutants of a fluid pollutant in a container or on an area of land or water substantially as hereinbefore described with reference to any one of figures in the accompanying drawings.