SORBENT BOOM

Abstract

A panel-shaped sorbent boom for the removal of oil and other chemicals from water.

Description

BACKGROUND

When oil or similar hydrophobic chemicals are spilled into waterways, they typically float, forming a layer or “slick” on the surface. The removal of this slick is essential to prevent the fouling of beaches, riverbanks, and other areas that the oil might come into contact with, and also to permit the entry of oxygen and sunlight essential to the aquatic ecosystem. It has been well known in the art to use sorbent booms for this purpose. Such booms are long sock-like tubes filled with a material which absorbs oil and similar hydrophobic liquids, but does not absorb water. These tubes are often linked end-to-end to create a chain of booms intended to surround a spill (or in the case of a spill in a river or stream, span the flow). However, although this design has been in use for many years, it has not proven satisfactory in practice. Such booms typically permit substantial quantities of oil to pass underneath them rather than being absorbed. Their round shape limits the surface area which can be exposed to oil, and prevents them from being weighted to float at an appropriate depth. Attempts to mitigate this problem have typically involved the placement of a hard barrier boom behind the sorbent boom so that the oil is trapped in close proximity to the sorbent and therefore more likely to be absorbed. This solution is expensive, because two booms are employed, requiring two deployment and recovery efforts using redundant equipment. Hard booms are also very heavy, and therefore difficult to transport and deploy, as well subject to damage by wind or current. In addition, a hard boom may not be practical for use in rapidly flowing water such as small streams.

Another approach to dealing with spills in flowing water has been the use of “filter fences.” These are literally fences, consisting of posts and water-permeable netting or fabric, which are built across streams. By themselves they do little to stop oil, so oil-absorbing particulate material is placed on the upstream side to absorb oil as the water passes through. Although more effective than sock booms, this method is labor intensive. Fences must be built by hand and the oil absorbent must be placed and removed by hand. The absorbant material near the top is largely wasted, because it floats above the oil and is therefore unable to absorb it. It is difficult to place fenceposts in hard-bottomed streams or concrete-filled drainage ditches, and difficult to affix fenceposts with the necessary permanence in areas with fast flowing water or soft silt bottoms. In the event of a loss of fence integrity or unexpected water volume overtopping the fence, contaminated oil-absorbing particulate can be scattered downstream, creating a secondary environmental hazard to complement the oil spill.

Mechanical skimmers of the type used to remove oils from industrial wastewater have also been employed, but they suffer from even more severe deficiencies in real-world conditions than the above approaches. They do not handle waves or tides well, require a power supply to function, and have no barrier qualities at all, meaning they must be combined with hard booms or some other means of concentrating oil to allow it to be removed.

SUMMARY

The problems of the prior art are solved by a sorbent boom having multiple compartments of similar size in a single panel, permitting it to absorb oil more effectively than sock booms without halting the flow of water through the boom as hard booms do.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of the panel sorbent boom having 3 compartments.

FIG. 2 is a perspective view of the boom of FIG. 1 cut along line 2-2, showing the compartments in which fill material is placed.

FIG. 3 is a perspective view of a chain of booms weighted and floating upright in a body of water.

FIG. 4 is an overhead view of one possible open-water application in which a chain of weighted booms is towed behind boats to gather up spilled oil, and a skimmer vessel follows the boom at its apex to pump oil directly out of the water.

FIG. 5 is a perspective view of an alternative embodiment of the panel sorbent boom having two compartments.

FIG. 6 is a perspective view of the boom of FIG. 5 cut along line 6-6, showing the compartments in which fill material is placed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, the panel-type oil boom 10 is preferably composed of cover 12, which has front 12a and back 12b. The cover 12 may be formed by one or more elongate tubes of material which permit both water and oil to pass through easily. It may be formed of multiple separate sheets of material as well. The material may be mesh or fabric, but is preferably non-biodegradable. Preferably, the boom 10 is about three inches thick, about ten inches wide, and about six to ten feet long. The front 12a and back 12b are joined to divide the cover 12 into more than one, preferably two or three, compartments 18a, 18b, and 18c that run longitudinally. This may be accomplished by attaching dividers 16 to the inner wall 14 of the cover 12 by attaching separate tubes of material to one another, or simply by attaching the front 12a to the back 12b along an elongate seam. The dividers 16 may be the same material making up the cover, or may be different. The attachment of dividers 16 or of the front 12a to the back 12b may be accomplished by any means having suitable strength, such as sewing, gluing, or the application of heat to fuse the parts together. The dividers 16 and cover 12 combine to form a rectangular panel-like boom with a much greater surface area relative to its volume than conventional sock booms.

Compartments 18a, 18b, and 18c are filled with an oil absorbing fill material. Preferably, this fill material absorbs oil but not water, so that water may flow easily through the boom as a whole, but oil is trapped. The fill material should be lighter than water so that the boom 10 can float while absorbing oil rather than sinking. Meltblown polypropylene is preferred, and virgin rather than reclaimed polypropylene is especially preferred. Other oil absorbing fill materials are also available and well known in the art. Each compartment is closed in whatever manner will retain the fill material.

The boom 10 will preferably have some means of attaching it to other booms, to fixed structures, to boats, or to winches, reels, and other means of deployment. These attachment means 20 may be any well-known device, such as grommets, fabric or wire loops, or clips. These attachment means 20 are already in use on conventional sock booms. For illustrative purposes only, fabric loops are shown. Preferably, some of these attachment means 20 are located at or near the corners of the boom 10. This permits the booms 10 to be joined in such a fashion as to keep them substantially parallel with each other and prevent twisting. Additional attachment means 20 may be along the edges of the boom 10 to permit the booms 10 to overlap each other to maximize oil absorption. In addition, weights 22 may be attached to the attachment means 20 along one edge so as to hold it upright in the water.

The booms 10 of the invention may be deployed in a number of ways. For spills of limited scope in enclosed and relatively static bodies of water, they may simply be placed upon the water's surface and permitted to absorb any oil they encounter. This is an inexpensive means of cleaning the water. Somewhat greater efficiency can be achieved by connecting a plurality of booms 10 together and permitting the booms to float horizontally in an extended string. This method is simple and quick to set up and gives superior absorption compared to sock booms because the flat design puts more oil-absorbing material near the surface of the water, where it is needed. A flat-floating panel boom 10 or string of panel booms 10 also deals with wave action better than sock booms because waves that push the leading edge up tend to drive the trailing edge downward, into the oil requiring absorption.

A preferred method for deploying booms 10, as shown in FIG. 3, is to link them together into a chain and then apply weights 22 to the attachment means 20 all along one edge of the chain. By choosing the weights 22 appropriately, the chain may be caused to float vertically a predetermined distance out of the water. This distance may be adjusted to account for conditions, such as wave action, which may call for a greater distance to prevent overtopping, and depth of the oil slick, with deeper slicks requiring a lower floating boom 10 to prevent oil from slipping underneath. It is possible to manufacture booms 10 with weights 22 pre-attached to simplify deployment. This arrangement both exposes a much greater surface area than sock booms, to maximize absorption, and also ensures that oil will not simply slip underneath.

The weighted chain of oil booms 10 may be positioned in any way which maximizes the chance of encountering oil. For instance, a set of booms 10 may be deployed across a harbor mouth so that tidal action will cause bilge oils to be collected before they escape the harbor. The chain may be positioned to surround or “blockade” an environmentally sensitive section of shoreline so that oil spills from the open sea will not affect that area. It may be strung across a river or stream to capture oil from upstream and prevent it from doing further damage, and in this application it is much more efficient than filter fences because all of the sorbent material is located near the surface of the water, where the oil is. A chain of booms 10 may be deployed in a circle around the source of an oil spill or leak to contain it. It may be towed behind two or more towing boats 24 in a “purse seine” action to surround and mitigate an otherwise uncontrolled spill, as depicted in FIG. 4. The boats then steer to gather oil in a manner reminiscent of a purse seine gathering fish. A skimmer boat 26, which is well known in the art, may be employed to pull oil 28 out of the water before it encounters the chain of booms 10. In this way more oil may be removed before the booms 10 become saturated. These various applications may range from chains of hundreds of booms 10 to surround leaking tanker ships to the placement of a single boom 10 across a drainage ditch at the site of an automobile accident.

Because the booms 10 are not made of biodegradable materials, they may be left in place indefinitely until saturated with oil. They may then be removed and optionally replaced with fresh booms 10. This permits cleanup to occur naturally over an extended period of time with minimal human intervention. For instance, a tanker truck carrying some quantity of oil may crash on the roadways, leaking oil into drainage ditches or storm drains which lead to local streams. While the bulk of the oil may be cleaned up fairly promptly, some may cling to rocks or the roadway and leach into the water only gradually. Booms 10 may be placed in the stream and left in place for extended periods of time to catch this residue until it has been reduced to an acceptably low level by the natural water flow.

The terms and expressions that have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims that follow.

Claims

1. An oil absorbing boom, comprising:

a cover having a front and a back;

a plurality of compartments formed within the cover by connecting said front and said back; and

an oil absorbing fill material within said compartments.

2. The boom of claim 1 wherein said oil absorbing fill material is polypropylene.

3. The boom of claim 2 where said polypropylene is virgin material.

4. The boom of claim 1 wherein said compartments are elongate and arranged substantially parallel to each other.

5. The boom of claim 1 further comprising weights attached to the boom.

6. The boom of claim 5 wherein said weights are so selected that when placed in water, the boom floats at a predetermined depth.

7. The boom of claim 6 wherein said weights are so arranged that when placed in water, the boom floats with said front and said back substantially perpendicular to the surface of the water.

8. An oil absorbing boom, comprising:

A plurality of elongate compartments, each having an length, formed of a flexible material, said compartments arranged substantially parallel to each other and joined along their lengths; and

an oil absorbing fill material within said compartments.

9. The boom of claim 8 wherein said oil absorbing fill material is polypropylene.

10. The boom of claim 9 where said polypropylene is virgin material.

11. The boom of claim 8 wherein said compartments all have a height and a width, wherein said compartments further have substantially the same width, and are so arranged that the boom has a width equal to the width of each compartment and an height equal to the sum of the compartments' respective heights.

12. The boom of claim 11 further comprising weights attached to one of the compartments.

13. The boom of claim 12 wherein said weights are so selected that when placed in water, the boom floats at a predetermined depth.

14. The boom of claim 13 wherein said weights are so arranged that when placed in water, the boom floats with the compartments arranged substantially vertically relative to one another.

15. A method of removing a contaminant from water, comprising the steps of:

providing a sorbent boom comprising a cover having a front and a back, a plurality of compartments formed within the cover by connecting said front and said back, and a contaminant-absorbing fill material within said compartments;

attaching weight said boom; and

placing said boom in water containing a contaminant.

16. The method of claim 15 wherein the boom is so weighted that when placed in water, the boom floats with said compartments arranged substantially parallel to the surface of the water and substantially vertically relative to one another.

17. The method of claim 15 further comprising the step of joining a plurality of booms together to form a chain.

18. The method of claim 15 wherein said water is in motion, and said boom is placed in said water and affixed to an immobile object such that the water tends to flow between said front and said back.

19. The method of claim 15 further comprising the step of attaching said boom to an object that moves through said water in such a fashion that the water tends to flow between said front and said back.