NZ539535A - Filter apparatus with woollen fibre in screen for catch pit to filter all water entering siphon invert - Google Patents

Abstract

A filter with a woollen fibre in a screen is adapted to be locatable in a catch pit so as to prevent water passing through a siphon invert before passing through the filter.

Description

539535 Our Ref: FIL006 Patents Form No. 5 No. 539535 Dated 19 April 2005 PATENTS ACT 1953 COMPLETE SPECIFICATION SEPARATION APPARATUS We, Gary CHRISTOPHER of 58 Roberta Avenue, Glendowie, Auckland 1005, New Zealand, Kathleen Gail CHRISTOPHER of 58 Roberta Avenue, Glendowie, Auckland 1005, New Zealand, and David Malcolm Vince GIBBS of 76D Avimore Drive, Highland Park, Auckland 1705, New Zealand all New Zealand citizens as Trustees of the CHRISTOPHER FAMILY TRUST do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: FIELD OF THE INVENTION This invention relates to separation of contaminants from a liquid, and in particular to apparatus for this purpose.

BACKGROUND Separation of materials from liquids is a relatively well explored and developed technical field in which improvements are continually being made. However, treatment systems are a constant ongoing subject of research and development in order attempt to refine the processes used 10 to treat such liquids, with particular focus being on simplifying and reducing the associated costs.

Treatment of liquids such as storm water run-off from road networks, airport runways, or industrial manufacturing operations, which may contain 15 hydrocarbons (in particular petroleum hydrocarbons used within the transport industries), insoluble solids and litter, and/or heavy metals, is often required in order to meet environmental discharge operating conditions and/or to alleviate the loading on municipal treatment works and/or to minimise environmental impact.

Catch pits, which are generally the first stage in any storm water management system, have traditionally been designed as little more than a lined pit in the ground into which storm water is feed. Because the primary function of a catch pit has been to act as a feeder into the storm 25 water management system little effort to remove contaminants, other than bulk solids.

In order to remove the bulk insoluble materials, such as litter, grit, gravel and other rocks, and related particulates, a gravity-type separation 30 technique is utilised. This is based on the principle of movement of particles relative to the fluid, where the force exerted on the particles which induces movement is gravity and where the particles are heavier 2 than the suspending liquid. This is essentially a settling operation. The catch pit outlet, or siphon invert, is located in the upper half to one third of the wall so that the insoluble materials have an opportunity to settle out. Periodically such catch pits then need maintenance involving removing the settled material from the floor of the catch pit, typically by vacuum cleaning operations.

Problems with current catch pit designs include that they do not provide for the removal of finer particles, nor do they allow for hydrocarbon removal.

Further, many such catch pits have the siphon invert located relatively low in the pit. With such catch pits there is limited allowance for build up of settled material, meaning that unless cleaned out regularly the efficiency of the particulate catch drops off rapidly as the high of settled solids 15 approaches the siphon invert; as the level of settled material increases as water enters the catch pit from the top it stirs up the settled material which is then carried into the siphon and on into the storm water pipe system proper, potentially settling out in the pipes and gradually contributing to a deterioration of the system as a whole, or otherwise passing on through 20 the system into the dissipation and/or discharge areas where environmental damage can result. This can present as a particular problem in flash flood and other high rainfall circumstances. Indeed the problem identified remains an issue even for those catch pits which have a correctly located siphon invert in high flow situations.

It is an object of the present invention to overcome at some of the above identified problems, or to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION In its broadest aspect the invention provides a filter apparatus for use in a catch pit or similar waste water collection sump having a siphon invert, the apparatus comprising a filter means, said filter means including a filter intellectual property office of n.2. 31 AUG 2006 n f* ib# mmmm m frame and a filter screen, wherein said filter screen includes woollen fibre wherein the filter means is adapted to be locatable in the catch pit or sump pit such as to prevent water that may enter the catch pit or sump pit from egressing via the siphon invert without first passing through the filter 5 screen.

It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 10 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components which it directly references, but also to other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

Preferably the filter screen includes a composite fibre filter for the adsorption of petroleum hydro carbons, and the absorption of heavy metals and some other suspended particulate material. More preferably the filter screen comprises a composite of woollen fibre and one or more 20 of the following components: (i) polypropylene fibre (ii) polyester fibre (iii) other synthetic fibre Advantageously the filter screen comprises a composite of woollen fibre and two other components in a ratio of approximately 80:10:10 respectively on a dry weight basis.

Desirably the fibres of the filter screen are carded and/or twisted and/or 30 warped and/or knitted and/or felted. 4 3 AUG 2006 I ^qeiveqi Optionally the filter means can further include a high flow by pass such that in high flow situations excess water can bypass the filter screen.

Preferably the filter means further includes a protective shroud so as to provide the filter screen with a degree of protection from the direct impact of solid materials and water falling onto the filter screen.

Desirably the filter means further includes an outlet connection which, in use, is connectable to the siphon invert of a catch pit.

Advantageously the filter means is configured and arranged such that in use solid material separated out from water that has passed through the filter screen can build up in the catch pit beyond the level of the siphon invert.

Preferably the filter frame is formed from a mesh material and is shaped as a tube, optionally but not essentially as a round tube.

Desirably the filter apparatus further includes a liner bag for use to line a 20 catch pit or similar waste water collection sump to facilitate the process of settled waste removal during cleaning, said filter means residing within the filter bag and in use filtering waste water as it leaves the liner bag.

Preferably the liner bag is formed from monofilament fibre.

Advantageously the filter apparatus further includes a bag mouth opening means to, in use, hold the mouth of the liner bag open and fully occupying the opening of the catch pit or collection sump.

In a further aspect, the invention may broadly be said to comprise a sump or catch pit incorporating a filter means as described above in the first broad aspect of the invention.

' INT£lle^^wperty of n.z. 0fficei 3 7 AUG 2006 &eqejved BRIEF DESCRIPTION OF THE DRAWINGS Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1 illustrates a sectional side elevation of an apparatus in accordance with a first embodiment of the present invention located in a catch pit; Figure 2 illustrates a sectional side elevation of an apparatus in accordance with a second embodiment of the present invention located in a catch pit; Figure 3 illustrates a sectional side elevation of an apparatus in 15 accordance with a third embodiment of the present invention located in a catch pit; Figure 4 illustrates a perspective view of catch pit liner bag in accordance with an embodiment of the present invention; Figure 5 illustrates a perspective view of a catch pit liner bag in accordance with an alternative embodiment of the present invention; Figure 6 illustrates a perspective view of sump pit liner bag in accordance with an embodiment of the present invention; Figure 7 illustrates a sectional side elevation of an apparatus in accordance with a second embodiment of the present invention located in a sump pit; and Figure 8 illustrates a plan view of the apparatus of figure 7. 6 DESCRIPTION OF THE PREFERRED EMBODIMENTS A filter apparatus as generally indicated at 1 in accordance with the present invention can take various configurations. Three different preferred embodiments specifically directed to catch pits are shown in 5 Figures 1 to 3. Other configurations taking the features of the present invention are also contemplated. Figures 7 and 8 illustrate an alternative configuration more particularly suited to sump pits. Figures 4 and 5 illustrate a monofilament bag liner for use in conjunction with the embodiments of figures 1 to 3. Figure 6 illustrates a monofilament bag 10 liner for use in conjunction with the embodiments of figures 7 and 8. In the drawings like components have been like numbered.

Each of the figures 1 to 3 illustrate a preferred embodiment of the invention in situ in a catch pit 100. The catch pit 100 comprises a 15 sump 101 having side walls 102 and an open top 103. Part of the open top 103 is covered with a grate 104. In use storm water and any detritus and/or hydrocarbon residue entrained with the storm water enters the catch pit 100 either through the grate 104 or, in higher flow circumstances, via the opening 105 adjacent the grate 104. A siphon invert 106 is 20 provided in the side wall 102, preferably at least one third the way up the wall 102, and no more than three quarters of the way up the wall 102.

The apparatus 1 includes a filter 2 configured and arranged to, in use in a catch pit 100, filter storm water as it passes from the sump 101 out 25 through the siphon invert 106. A monofilament bag 50 is also included to line the catch pit 100. The general features of the design of the bag 50 are illustrated in more detail in figures 4 and 5. Depending on the design, the bag 50 can either extend up the walls 102 of the catch pit 100 to the height of the invert 106 or, with an appropriate aperture in the wall of the 30 bag 50, up and around the invert 106 to the top of the walls 102. 7 The filter 2 comprises a filter frame 3 and a filter screen or element 4. The filter screen 4 may include woollen fibre which has been treated (for example, a woollen fleece is scoured, and the natural greases are removed leaving a fibre capable of absorption of not only greases and oils, 5 but small molecular solids) to be carded and/or twisted and/or knitted and/or slumped and/or knapped or woven to help enhance the potential liquid to fibre surface contact. The fibres are a scaly material, such that each strand of fibre may be coated with hooks or scales or similar particle grabbing means to help contain contaminants within the filter fibres. A 10 desirable operation of the fibres may be that in particular hydro carbons (especially petroleum hydrocarbons) are contained within the filter fibre.

The filter screen 4 may also include polypropylene and/or polyester micro-fibre or other scaly material or woolly type fibre materials. Polypropylene 15 fibres have some ability to absorb materials, whilst the polyester is mainly provided as a deflection agent to reflect and bounce materials towards woollen fibres for absorption.

The density of the filter screen 4 may be varied depending upon the flow 20 requirements and liquid conditions, or necessary material containment by the filters from the liquid being treated. Additionally, the fibre blends and ratios of each fibre component may be adjusted from application to application as required, and may be determined by the specific contaminants being targeted for removal from the liquid. For example, a 25 typical urban road run off fibre blend may be woollen fibre 80%, polypropylene micro fibre 10% (on a dry weight basis).

The density of the filter screen 4 should not be such as to generate significant hydraulic back pressure across the filter screen 4, and should 30 be regarded as providing an initial filtering treatment stage to remove bulk solids and contain materials such as hydro carbonaceous matter. 8 Referring specifically to figure 1, the apparatus 1 essentially comprises a filter frame 3 in the form of a sheet of mesh, desirably galvanised steel mesh, onto one side of which is overlaid a filter element 4. The mesh sheet is bent into a U shape, as viewed from above. Equally, however, 5 the mesh sheet filter frame 3 could simply be curved or formed into a V shape as viewed as a horizontal cross section. The key requirement is that once in position in a catch pit 100 there be a space maintained between the filter element 4 and the wall 102 of the catch pit 100 so as to allow storm water than has passed through the filter element 4 to freely 10 migrate towards and flow into the siphon invert 106.

Preferably the mesh frame 3 should, once in position in a catch pit 100, extend from the base 107 of the sump 101 upwards and beyond the height of the siphon invert 106 to a point adjacent but slightly below the catch pit 15 open top 103.

As noted, the filter screen 4 is overlaid onto the outside of the mesh frame 3. In use storm water and any separated materials press against the filter screen 4 which is turn is supported by the frame 3. The filter 20 screen 4 can be clipped, stitched, stapled or otherwise releasably attached to the frame 3 in such a manner as to retain the filter screen 4 in position and minimise slumping, but at the same time facilitate easy replacement once the filter screen 4 has reached the end of its useful life.

Optionally the filter screen 4 could be sandwiched between the mesh frame 3 and a second mesh layer (not shown) formed from a finer mesh material, thereby providing a greater degree of protection and also support against slumping, said second layer of mesh being clipped or otherwise attached to the frame 3 via, for example, cable ties or the like.

The top 5 of the frame 3 needs to be closed off in some way so that, in use, storm water is prevented from by passing the filter screen 4. 9 Optionally that can be undertaken by extending the mesh of the frame 3 in that way, and then the filter screen 3 extended to cover that portion also. Alternatively, and as shown in the figure, a sloping shroud 6 can be fitted. The shroud 6, being formed from a resilient material such as rubber or the 5 like, in addition to diverting the contaminant laden storm water down into the sump 101, protects the filter screen 4 from damage by the impact of larger debris, and from high water flow falling onto it.

Turning now specifically to the embodiment of the invention shown in 10 figure 2, the apparatus 1 comprises a vertically extending tubular filter frame 3 formed from galvanised steel mesh or alternatively a plastics mesh material. The lower end 10 of the tubular frame is closed, also with mesh material. The tube desirably being between 150mm and 400mm in diameter, depending on the dimensions of the catch pit 100 it is intended 15 for use in.

The top 11 of the tubular frame 3 is attached to an opening in an edge of, and depend downwardly from, a horizontally extending feed pipe 12. The pipe 12 having a first end 13 adapted to, in use, engage with the siphon 20 invert 106 to form a storm water flow path out of the catch pit 100. The opposite end 14 of the pipe 12 incorporates a storm water excess flow entry point 15, so that in circumstances of very high storm water flow the filter screen 4 can be bypassed in the interests of avoiding flooding of the area surrounding the catch pit 100. In the drawing the end 14 of the 25 pipe 12 is shown as having a weir 16 partially closing the end 14. The open portion presenting as the high flow bypass point 15.

Numerous other forms of a high flow level bypasses are within the contemplation of the invention. For example, uni-directional valves or 30 vanes could be used, as well as overflow pipe extensions and the like.

The filter screen 4 is formed as a replaceable filter sock 17 which is fitted over the outside of the frame 3 and is pulled up and around the joint between the pipe 12 and the frame 3 so as to prevent storm water by passing the filter screen 4. The sock 17 can be attached to the frame 3 by 5 various means such as a releasable or replaceable clamp, such as a long cable tie or the like.

Figure 3 illustrates a further alternative embodiment of the invention. As shown, the apparatus 1 comprises a vertically extending tubular filter 10 frame 3 formed from galvanised steel mesh or alternatively a plastics mesh material. The lower end 20 of the tubular frame is closed, also with mesh material. As with the embodiment of figure 2, in this embodiment also the tube desirably between 150mm and 400mm in diameter, depending on the dimensions of the catch pit 100 it is intended for use in.

The tubular frame 3 is formed in two parts, a lower part 21 of the general configuration of the frame 3 of figure 2, and an upper part 22 of similar construction and diameter, but shorter. The two parts 21, 22 being spaced apart by a connecting housing 23 from which the lower part 21 depends, 20 and the upper part 22 extends, both vertically. Extending horizontally out of the connecting housing 23 is a feed pipe 24. The pipe 24 having a free end 25 adapted to, in use, engage with the siphon invert 106 to form a storm water flow path out of the catch pit 100.

The filter screen 4 is formed in two parts, a first, lower part 26 as a replaceable filter sock 27 which is fitted over the outside of the frame 3 and is pulled up and around the lower part 21 of the frame 3, and a second, upper, sleeve 28 which fits over and around the upper part 22 of the frame 3 to a point adjacent to but short of the full height of the upper 30 part 22 of the frame 3. The uncovered portion of the upper part 22 of the frame 3 acts as a storm water excess flow entry point 29, so that in circumstances of very high storm water flow the filter screen 4 can be 11 bypassed in the interests of avoiding flooding of the area surrounding the catch pit 100.

The sock 27 and sleeve 28 can be attached to the frame 3 by various 5 means such as a releasable or replaceable clamp, such as a long cable tie or the like.

Finally, a cover 30 can be fitted to the open end of the upper part 22 of the frame 3 so as to prevent debris from entering or otherwise bypassing the 10 filter screen 4.

Various means of holding the bag 50 in place against the walls 102 of the catch pit 100 are possible.

As shown in figure 4, a spring steel frame 51 can be used to keep the mouth 52 of the bag 50 open and to capture it firmly against the walls 102. To prevent it from slipping down the bag mouth 52 can be rolled several times over the frame 51 before it is set in place.

Figure 5 shows an alternative mechanism for maintaining the bag 50 in position. In that regard, a rubber support 53 can be bonded to the bag mouth 52. The support 53 being generally shaped to the size and configuration of the catch pit 100. A steel stiffener 54 can be pivotally connected to each corner 55 of the support 53, and also pivotally connected to a handle 56. When the bag 50 is in the desired position in the catch pit 100 the handle 56 is pushed downwardly, forcing the steel stiffeners 54 into the corners 55 of the support 53, thereby locking the support 53, and thus the bag 50, against the walls 102 of the catch pit 100. To remove the bag 50 the handle 56 is pulled upwardly, thereby removing 30 the restraining pressure on the corners 55 of the support 53, and allowing the bag 50 to be withdrawn from the catch pit 100 using the handle 56 to do so. 12 Turning now to figures 7 and 8, the drawings illustrate a preferred embodiment of the invention in situ in an inline sump 200, such as, for example, may be used to collect waste water from multiple sources. The sump 200 comprises a pit 201 having side walls 202 and a top 203 which 5 can be closed by an inspection hatch 204. It also includes an inlet 205 and an outlet 206.

In use storm water and any detritus and/or hydrocarbon residue entrained with the storm water is collected and piped into the sump 200 through the 10 inlet 205. It then passes through the filter apparatus 300, and out the outlet 206. In extreme flow situations, to prevent damage to the pipe network, and the apparatus 300 in particular, at least some of the water can flow directly across the top of the apparatus 300 and out the outlet 206.

The apparatus 300 comprises a flow directing plate 301 which is disposed vertically across a sector 302 of the pit 201 directly perpendicularly to the direction of flow from the inlet 205, and depends from a support plate 303 which covers to pit 301 save for the sector 302 partitioned off by the 20 plate 301.

The plate 301 is configured and arranged to, at all but extreme water flow levels, cause any water flowing from the inlet 205 to drop down through the aperture 304 in the sector 302 into the pit 201.

As shown in the drawing, the plate 303 includes three separate box filter frames 305 formed of mesh. Three separate frames 305 are shown because of the size of the filter elements that allows and the convenience of replacing these, but it will be appreciated that a greater number of 30 smaller frames can be used, or equally a smaller number of larger frames. 13 Each frame 305 is overlaid with a filter element 4. In use storm water and any separated materials press against the element 4 which is turn is supported by the frame 305. The filter element 4 can be clipped, stitched, 5 stapled or otherwise releasably attached to the frame 305 in such a manner as to retain the filter element 4 in position and minimise slumping, but at the same time facilitate easy replacement once the filter element 4 has reached the end of its useful life.

Optionally the filter element 4 could be sandwiched between the mesh frame 305 and a second mesh layer (not shown) formed from a finer mesh material, thereby providing a greater degree of protection and also support against slumping, said second layer of mesh being clipped or otherwise attached to the frame 305 via, for example, cable ties or the like.

Water passing into the pit 201 fills the pit 201 and then is forced up and through the filter elements 4 before passing out the outlet 206.

Turning now also to figure 8, the pit 201 is lined with a monofilament bag 50 held in place by a retainer 306. The retainer 306 is essentially a partial ring of steel having its ends joined by a turn buckle 307. The turn buckle 308 can be used to spread the ring 306 thereby expanding it in size and so forcing it, and thus the mouth 52 of the bag 50 which it holds up, against the walls of the pit 201.

While the waste water remains in the pit 201 any debris and heavy waste entrained in it is able to settle into the bag 50. As the water passes up and out through the filter elements 4 any heavy metals and hydrocarbons are scrubbed from the water. 14 A particular advantage of the present invention is the substantially biodegradable aspect of the filter fibre. This may be particularly advantageous once the used fibre filter(s) have been removed from the 5 system, and require disposal (for example in a landfill).

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the invention as 10 claimed.

Claims (5)

CLAIMS:

1. A filter apparatus for use in a catch pit or similar waste water collection sump having a siphon invert, the apparatus comprising a filter means, said filter means including a filter frame and a filter screen, wherein said filter screen includes woollen fibre wherein the filter means is adapted to be locatable in the catch pit or sump pit such as to prevent water that may enter the catch pit or sump pit from egressing via the siphon invert without first passing through the filter screen.

2. An apparatus according to claim 1 wherein the filter screen includes a composite fibre filter for the adsorption of petroleum hydro carbons, and the absorption of heavy metals and some other suspended particulate material. More preferably the filter screen comprises a composite of woollen fibre and one or more of the following components: (i) polypropylene fibre (ii) polyester fibre (iii) other synthetic fibre

3. An apparatus according to claim 2 wherein the filter screen comprises a composite of woollen fibre and two other components in a ratio of approximately 80:10:10 respectively on a dry weight basis.

4. An apparatus according to claim 2 or 3 wherein the fibres of the filter screen are carded and/or twisted and/or warped and/or knitted and/or felted. office] mtellectual property of n.z. 3 1 aug 2006 5mcejved 16

5. An apparatus according to any one of the preceding claims wherein the filter means further includes a high flow by pass such that in high flow situations excess water can bypass the filter screen. 5 6. 10 15 8. 20 9. 25 10. 30 11. An apparatus according to any one of the preceding claims for use in a catch pit, the filter means further includes a protective shroud so as to provide the filter screen with a degree of protection from the direct impact of solid materials and water falling onto the filter screen. An apparatus according to any one of claims 1 to 6 wherein the filter means further includes an outlet connection which, in use, is connectable to the siphon invert of a catch pit or sump pit. An apparatus according to any one of the preceding claims wherein the filter means is configured and arranged such that in use solid material separated out from water that has passed through the filter screen can build up in the catch pit or sump pit beyond the level of the siphon invert. An apparatus according to claim 8 wherein the filter frame is formed from a mesh material and is shaped as a tube, optionally but not essentially as a round tube. An apparatus according to any one of the preceding claims further including a liner bag for use to line a catch pit or similar waste water collection sump to facilitate the process of settled waste removal during cleaning, said filter means residing within the filter bag and in use filtering waste water as it leaves the liner bag. An apparatus according to claim 10 wherein the liner bag is formed from monofilament fibre. 17 12. An apparatus according to claim 10 further including a bag mouth opening means to, in use, hold the mouth of the liner bag open and fully occupying the opening of the catch pit or collection sump. 5 13. 14. 10 A sump incorporating a filter means as claimed in any one of the preceding claims. A catch pit incorporating a filter means as claimed in any one of claims 1 to 12. An apparatus as described or exemplified in any one or more of the accompanying drawings.