GB2255772A

GB2255772A - Oil decontamination method and structure

Info

Publication number: GB2255772A
Application number: GB9110646A
Authority: GB
Inventors: John Christopher Butcher
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-05-15
Filing date: 1991-05-15
Publication date: 1992-11-18
Also published as: GB9110646D0

Abstract

A method of removing oil from oil-contaminated areas of water and adjacent coasts comprises contacting the oil with a buoyant structure comprising wool so that the oil is absorbed by the wool.

Description

OIL DECONTAMINATION METHOD AND STRUCTURE This invention relates to an oil decontamination method and structure, and in particular to a method of removing oil from oil-contaminated areas of water and adjacent coasts, and also a structure suitable for use in the method.

As is well known, oil spillages in rivers, lakes and at sea can cause very serious damage to natural life over an extensive area and can also have a serious effect on local industries such as fishing and tourism.

When spillages occur the methods used to contain and clear up the oil are often implemented too slowly. There is a need for a decontamination method which is simple to use, can be brought quickly into effect, involves low cost and causes no damage to the environment.

According to the present invention there is provided a method of removing oil from oilcontaminated areas of water and adjacent coasts which method comprises contacting oil with a buoyant structure comprising wool so that the oil is absorbed by the wool.

The present invention also provides a buoyant structure suitable for use in the above method of decontamination which comprises an elongate sheet of buoyant material having wool secured to it at intervals along its length and width.

In the method of the present invention the wool which is used as the absorbent for the oil can be either untreated wool, i.e. wool which still contains natural lanolin, or scoured wool. Untreated wool is preferred, which is carded and semi-spun. All types of wool are very absorbent to all kinds of oil and when placed in contact with oil in water absorbs the oil very quickly and effectively. Thus the use of wool potentially enables a very large area of contaminated water to be decontaminated in a relatively short period of time.

It is also a feature of the present invention that both the oil removed from the contaminated area and also the buoyant structure comprising the wool can be treated, as explained hereafter, so that both the structure and the oil are reusable.

A preferred type of buoyant structure is one comprising a buoyant polymeric material, for example foam plastic, in the form of elongate sheeting or mats having wool, preferably bunches of carded or semi-spun wool, secured to it at intervals along its length and width. The foamed plastic material is preferably of the close cell variety so that its buoyancy is retained in water. The types of inexpensive expanded plastics materials which are often used in packaging, for example closed cell polyethylene, are particularly suitable as the buoyant material of the elongate sheet.Such plastics materials can be readily made with relatively large lengths and widths, and the flexible and elastic materials particularly preferred both enable the "mats" of the invention to counteract wave action when in use and also enable the mats to be rolled up and stored to a relatively low volume and when released from storage their elasticity causes them to take up their natural shape again, thus assisting the deploying process.

As described above, the mats can of course be connected together and manoeuvred in the nature of booms to contain and absorb the oil contamination.

Due to the fact that the oil may be squeezed mechanically from the wool the recovery of the bouyant mats and treatment for re-use, and also the recovery of the oil, can be effected on board suitable vessels. The type of equipment required is already available in whaling factory ships which following their redundancy could be put to good use as oil spillage emergency vessels enabling their hydraulic press rollers to be used to extract both water and oil. The minor residue of oil remaining after pressing can be removed by steam or chemical washing and then the mats dried for re-use.

The securing of the wool to the buoyant plastic material may be by narrow band strapping stitched together or by the use of a chemical bonding agent.

The first method is preferred as it provides greater tensile strength and enables a greater area of wool to be exposed to absorb oil. As mentioned previously, the dimensions of the mats are not critical. Thus large volume mats, for example in excess of 600 square metres can be employed, in which case they can be recovered from the sea by vessels provided with winches such as the aforementioned whaling factory ships. Smaller volume mats could also be retrieved by means of cranes or winches.

The method of deployment of the buoyant structures of the invention and also their size will depend to some extent on the nature of the oil spillage.

For coastal and estuary contamination where the method would be land-based, and having regard to the difficulties which might occur due to difficult terrain, typically lightweight mats in lengths of, for example, 50 to 75 metres by 2 metres wide rolls might be released from the shore or dropped from a cliff onto the area to be decontaminated. At sea larger rolls might simply be dropped astern of a vessel or over its side, probably being released upwind of the oil slick so as to roll over and cover the spillage area. It is also envisaged that the method could be operated from the air i.e. by drop deployment by means, for example, of large transport aircraft such as the Hercules, which could deliver quickly and efficiently large rolls of the buoyant structure of the invention of the double-sided type over oil contaminated areas by means of their large rear hatchways.It is also envisaged that helicopters might be used to cover smaller spillages.

For spillages in rivers the smaller types of rolls which could for example be handled by just two men might be dropped upstream of the spillage, from barges or low bridges, and anchored to prevent entanglement.

The release and deployment mechanism of the buoyant structures of the invention may for example be simply by means of an encircling restraint around a roll, e.g. strong cordage, with a simple release mechanism like the rip-cord used on a parachute. For larger rolls an inflatable chamber along the length of the mat could be provided which could be inflated by high pressure gas when the mat was to be deployed from a roll.

In the embodiment of the invention involving mats having wool secured to one side of them it is of course important that the mats are deployed face down. Thus when the mats are dropped onto the contaminated area of water either they should be already facing downwards or should embody means to enable them to be self-righting. Such means can for example comprise suitably positioned buoyancy tanks.

Alternatively of course mats may be employed, as mentioned above, which have wool secured on both sides.

In the accompanying drawings: Figure 1 is a schematic end view of an example of a buoyant structure in accord with the invention.

Figure 2 is side view of a part of the structure shown in Figure 1.

Figure 3 is a schematic end view of another embodiment of a buoyant structure in accord with the invention.

Figure 4 is a side view of a part of the structure shown in Figure 3.

In the embodiment shown schematically in Figures 1 and 2 a buoyant mat 1 has secured to one side of it by binding or strapping a continuous or discontinuous layer of untreated natural wool. The embodiment shown in Figures 3 and 4 has a continuous or discontinuous layer of natural wool 2 secured to both sides of the buoyant mat.

Claims

CLAIMS:

1. A method of removing oil from oilcontaminated areas of water and adjacent coasts which method comprises contacting the oil with a buoyant structure comprising wool so that the oil is absorbed by the wool.

2. A method as claimed in claim 1 wherein the buoyant structure comprises an elongate planar sheet of buoyant material having wool secured to it at intervals along its length and width.

3. A method as claimed in claim 2 wherein wool is secured on both sides of the elongate planer sheet of buoyant material.

4. A method as claimed in any one of the preceding claims wherein the oil is subsequently removed from the buoyant structure and the buoyant structure is brought to a re-usable condition.

5. A method as claimed in any one of the preceding claims wherein the buoyant material is a foamed plastics material.

6. A method as claimed in claim 5 wherein the buoyant material is closed cell polyethylene.

7. A method as claimed in any one of the preceding claims wherein a plurality of said buoyant structures are linked together.

8. A method as claimed in any one of the preceding claims wherein the buoyant structure is stored prior to use in the form of a roll and is deployed at the oil contaminated area by unrolling the roll.

9. A method as claimed in claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

10. A buoyant structure suitable for use in the method claimed in claim 1 which comprises an elongate sheet of buoyant material having wool secured to it at intervals along its length and width.

11. A buoyant structure as claimed in claim 10 wherein wool is secured on both sides of the elongate sheet.

12. A buoyant structure as claimed in claim 10 or claim 11 in the form of a roll.

13. A buoyant structure as claimed in claim 10 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. A vessel when equipped with a buoyant structure as claimed in any one of claims 10 to 13 and with means for recovering oil from the buoyant structure so as to render the oil and structure ready for re-use.