AU724345B2 - A filter assembly - Google Patents

Description

1 "A FILTER ASSEMBLY" This invention relates to a filter assembly.

This invention has particular application to filter assemblies for stormwater drains and the like for filtering runoff water prior to discharge. However this invention is not limited to such application and may be used as an inline process filter which is particularly suitable for variable rate liquid flows. However for illustrative purposes only, the present invention will be described hereinafter in relation to its use with stormwater drains.

Stormwater drains typically discharge directly into streams and the like and carry large amounts of debris and other contaminating matter into the streams. In recent years there has been a growing awareness of the need to minimise 15 pollution resulting from groundwater runoff.

*One of the difficulties associated with groundwater runoff discharging from the outlets of stormwater drains is that the contaminants discharged therewith can range from relatively large lightweight objects such as aluminium drink 20 cans and plastic bags as well as liquid contaminants such as oils and greases improperly discharged onto the ground and .collected in the stormwater drains. In addition stormwater drains gather poisons and other chemicals which have been applied to lawns and plants as well as to buildings and machinery and particles from industrial processes as well as debris from roads and car parks.

i 2 Another difficulty associated with stormwater runoff is that the runoff may range from a trickle to a raging torrent and any apparatus placed in line in the stormwater drain must be capable of handling the full range of flows if it is to be effective.

Some local authorities have made attempts to filter stormwater runoff by placing a mesh fence across streams downstream of a stormwater discharge. These are suitable for catching relatively large articles only and require frequent clearing. In addition such filters represent a hazard in small creeks and the like as during periods of flooding they may snare persons or animals caught in the flow.

This invention aims to alleviate at least one of the S. above disadvantages and to provide apparatus for and methods S 15 of filtering variable rate liquid flows.

With the foregoing in view, this invention in one aspect resides broadly in a filter assembly including:a housing; inlet means to the housing; S: 20 primary outlet means from the housing through which liquid entering through the inlet means may be discharged; elevated flow conveying means along which the liquid entering through the inlet means may be conveyed to the outlet means; a diversion drain for diverting shallow flows through the inlet means from the elevated conveying means, and ,4 3 filter means for collecting contaminants in the diverted shallow flows.

The filter means may be of the type in which the filtered flows are accumulated in the housing for periodical discharge or emptying.

Alternatively the filter means may be associated with a secondary outlet through which filtered shallow flows may drain from or be discharged from the housing.

The diversion drain may be disposed at any desired location along the conveying means but preferably it is located adjacent the inlet and preferably the diversion drain includes blocking means for blocking passage of large objects into the diversion drain. The blocking means is suitably a grille or the S° like disposed at the entrance to the diversion drain and preferably configured S.with elongate openings extending longitudinally of the conveying means.

The conveying means may be a hollow conduit but preferably it is in the form of an open channel and suitably the conduit or channel is provided &too° :1111. with slots along its underside adjacent the inlet means which constitute the diversion drain which is blocked to passage of large objects therethrough.

In a further aspect of the invention there is a filter assembly including a housing having opposed sidewall portions; an inlet to the housing in one of said sidewall portions; a first outlet in the other of said sidewall portions; an elevated flow guide which serves to guide liquid between the inlet and the first outlet; a diversion drain in a leading end of said flow guide which diverts a shallow flow including debris carried therewith from the elevated flow guide; a filter chamber in said housing below said elevated flow guide in which said debris may collect and liquid from the shallow flow pass through a second outlet.

In another aspect this invention resides broadly in a filter assembly including: a housing; a plurality of filtering elements in the housing; S i -0 S

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*9* 9 *6S 0 *&0 4 inlet means to the housing from which liquid may pass to the filtering elements; outlet means from the housing through which filtered liquid may be discharge from the housing, and the filtering elements being arranged to filter different liquid flows through the inlet means.

The different flow paths from the inlet preferably result from different inlet flow characteristics which may be velocity, volume or viscosity dependent characteristics for example. Alternatively, the filter assembly may include active control means which are actuated to direct incoming fluid along different flow paths.

The active control means may be externally controlled by electronic control means, for example, or the active control S" 15 means may be moved by control devices from an inactive position to an active blanking position for blanking lower velocity flows from certain parts of the filter assembly when the inlet flow velocity, volume or level reaches a predetermined amount. Suitably such control devices, which utilise the flow for actuating the flow control means are biased to an inactive position to which they return when the flow volume, velocity or level reduces.

The filter assembly may be flow volume dependent and may include separate flow passages through which different flow volumes will preferentially pass. The flow passages may be separated vertically or longitudinally such that all low flow volumes will pass through the lowest or first flow passage while the maximum volume flow will pass through an elevated flow passage or a flow passage downstream from the low flow passage.

In a preferred form of the invention the inlet means is an inlet aperture formed opposite a main outlet aperture from the housing such that high velocity/volume liquid flow to the inlet means has a flow across the housing towards the main outlet for direct discharge of a substantial portion of the incoming liquid through the outlet aperture, whereas a low velocity/volume liquid flow to the inlet will pass through a respective one or ones of the filter elements adapted to filter such flows.

In one embodiment, the flow may range from shallow flow 15 such as a trickle through the inlet means, wherein the flow passes through a primary filter, a secondary filter and a tertiary filter prior to being discharged from the housing through a plurality of outlet apertures constituting the outlet means, whereas a medium flow will pass only from the inlet means along a different path through the primary and secondary filters, whereas full flow through the inlet will pass substantially unimpeded through the filter assembly.

In a preferred embodiment of the invention the primary filter is a relatively coarse filter which extends between the underside portions of the inlet and outlet such that water flowing therebetween but not passing directly through 6 the outlet aperture, that is shallow flow, can pass through the primary filter for discharge or for passage to the secondary filter. Suitably the primary filter is a bar type filter with closely spaced bars extending between the front and back walls of the housing beneath the apertures therein forming the inlet and main outlet apertures.

Part of the primary filter may be shielded to prevent passage of liquid therethrough. The shielded portion may be adjacent the inlet to prevent trickle flow falling directly from the inlet into the housing beneath the primary filter or the shielded portion may be adjacent the main outlet aperture to deflect high velocity flow through the main outlet. In a preferred form the main outlet aperture is larger than the inlet aperture.

S 15 Suitably the primary filter is a bar type filter which blocks passage of contaminants such as soft drink cans or the like therethrough and affords substantially unimpeded progress of such contaminants across the housing to the outlet while permitting smaller sized contaminants to pass S: 20 between the bars to the secondary filter. The secondary filter may also include a bar type filter for separating relatively large solids from the liquid and there may be provided a secondary outlet aperture through which those solids may be discharged from the housing. The secondary filter may also include an active or fine filter adapted for filtering further contaminants which may be included in liquid which passes through the bar type filter element of the secondary filter.

The tertiary filter is suitably disposed directly beneath the inlet and may entrap silt and the like which may act as a filter for further liquid trickling through the filter assembly. Suitably the outlet from the tertiary filter is fed to the secondary filter for discharge through the secondary outlet aperture.

In a further aspect this invention resides in a method of filtering variable rate liquid flows including providing a catchment having a common liquid flow inlet and flow dependent paths therethrough, and arranging respective filter means in the' catchment to intercept flows passing along selected ones of the flow dependent paths. Preferably the catchment means is a filter assembly as herein defined.

In a further aspect this invention resides in a method of filtering liquid flows including providing a filter assembly as claimed in any one of the preceding claims to receive flows through a common inlet; separating different flows depending on their flow characteristics; filtering different flows; and discharging liquid from the outlets.

In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a typical embodiment of the invention and wherein: FIG. 1 is a top perspective view of the filter assembly; FIG.. 2 is a side cross-sectional view of the filter assembly of Fig. 1; FIG. 3 is a transverse cross-sectional view of the filter assembly of Fig. 1; FIG. 4 is a perspective view of the lid for the filter So. e *a a 9*

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*S 8 assembly of Fig. 1 and FIG. 5 is a cutaway perspective view of another embodiment of the filter assembly; FIGS. 6 and 7 illustrate alternate discharge collectors for the filter assembly of Fig. 1; FIGS. 8a, 8b and 8c illustrate a further embodiment in plan, side and end elevations; FIG. 9 is a cutaway perspective view of the embodiment of Fig. 8; FIGS. 10a and 10b illustrate a front end and a cutaway side view of the further embodiment, and FIG. 11 is a sectional view along the line 11-11 of Fig. 8b.

o The filter assembly 10 illustrated in Fig. 1 includes a concrete housing 11 which expands downstream from an inlet wall 12 to the outlet wall 13.

o 15 The housing may be in the order of 2.4 metres long, 1.8 metres wide and between 1.2 and 1.5 metres deep. The inlet wall is provided with a circular inlet aperture 14 in the order of 450mm diameter whereas the outlet aperture is larger and is in the order of 600mm wide by 500mm deep.

A blocking filter wall 16 extends between the walls 12 and 13 beneath 20 the inlet and outlet apertures and is formed as a bar type filter with bars extending longitudinally as illustrated with relatively wide spacings therebetween, in the order of 25 mm.

Rubbish such as drink containers will be supported by the blocking filter and pass therealong through to the main outlet aperture 15 through which they will be discharged either by gravitational flow along the inclined blocking filter or with water flow during a rainy period. The end portion of the blocking filter adjacent the main outlet aperture 15 is closed to provide a deflector 18 for deflecting water flows impinging thereon through the main outlet aperture A lid 19 covers the housing and a curved ridged portion extends along the base 21 of the housing directly beneath the blocking filter wall 16 and is separated therefrom by a :.".secondary filter 22 in the form of a relatively fine wedgewire filter of the type used in the manufacture of bore S 15 screens and the like. This filter extends the full length of the housing such that water passing through the blocking filter wall 16 will then pass through the secondary filter 22 onto the bridge portion 20 where it will be separated by the curved ridge 20 and directed to a respective one of the 20 opposite sides of the housing.

Any solid matter too large to pass through the secondary -filter 22 will pass along that filter to the elongate outlets 24 which extend across the end wall 13 beneath the main outlet 15. Suitably the wedge wires are aligned parallel to the bars of the blocking filter wall 16 to facilitate passage of solid material thereacross to the outlets 24.

Further active filters which are preferably in the form of removable mat type filters 26 are supported on the outer base wall portions 25 of the housing extending along either side of the ridge portion 20 and through which the liquid can flow for final discharge through the side outlets 27. The removable filter mats may be aerated nylon or similar filter material which is removable and washable. The filter may also include an active ingredient for filtering chemicals such as activated carbon.

The secondary and blocking filters may be associated with shielding means which shields them from any flow which is sufficient to dislodge the filtered waste therefrom to the outlet. The shielding means may be provided with active externally controlled operating means or may be moved a nonshielding position to an shielding when an inlet flow characteristic reaches a predetermined level.

A tertiary filter 30 is located in the base of the housing directly beneath the inlet 14. The tertiary filter includes a front dividing wall 31 which is also formed of a e 20 wedgewire material with an spacing between wires of up to oo imm. The tertiary filter receives any trickle flow passing through the inlet 14. Such flow often contains large amounts of silt and other solids material which will be retained behind the filter wall 31. The silt retained therein will itself act as a filter for incoming flows through the inlet 14.

The main outlet aperture 15 discharges through a flexible shield filter 35 which may be in the form of hanging chains which is adapted to impede the progress of solid materials passing through the outlet 15 such that they are caused to fall downwardly into the rubbish collector which may be in the form of an open wire bin 38 as illustrated in Fig. 6 or in the form of an open tray 39 as illustrated in Fig. 7 which has a side wall 34 formed as a ramp along which a bobcat or the like vehicle may be driven to clear out the rubbish collected in the collector 39. The open wire bin may be provided with lifting hooks or the like to enable it to be emptied into the back of a truck or discharge at an appropriate location as desired.

*In use, trickle flows through the inlet 14 will pass to e 15 the tertiary filter 30 whereby silt and the like material will be retained. The liquid will pass through the wedgewire wall 31 to the filter mats 26 for further filtering before discharge through the outlets 27. If the flow through the inlet is somewhat greater, the water will bypass the tertiary 20 filter 30 and will pass through the blocking filter direct to .o 'oo the secondary filter for treatment as described above.

.For full flow conditions, such as during a storm flow or the like, the water flow through the inlet will be at such a velocity that it will carry substantially fully across the blocking filter to the main outlet aperture 15 or to the deflector 18 for deflection through the main outlet aperture whereby it will bypass the filters and be discharged directly through the outlet The flexible shield filter 35 will act to deflect some of the large solid rubbish into the rubbish collector although in such conditions much of the rubbish will be discharged directly without impedance of the flow. This will facilitate prevention of a back pressure buildup in the stormwater drains which may result in local flooding at the inlets to the stormwater drains if the stormwater can not be drained away quickly.

An alternative embodiment of the filter assembly is shown in Fig. There is a concrete housing 111 with an inlet aperture 114 in front wall 112 and an outlet aperture 115 in rear wall 113.

The outlet aperture 115 is comparatively larger than the inlet aperture 114. The filter assembly 110 also has an elevated flow guide 118 with a diversion drain 116 in the leading end of the flow guide 116 adjacent the inlet :aperture 114. The diversion drain 116 is in the form of elongate openings 15 extending longitudinally relative to the flow guide 118. Below the flow guide 118 is a secondary filter 117 which has a grille type screen 122 in the end below the diversion drain 116. The grille type screen 122 of the secondary o*oo filter has smaller openings than the diversion drain 116. Solids prevented from passing through screen 122 and medium flows of liquid are directed 20 along the secondary filter 117 and through secondary outlets 124. Solids and liquid able to pass through the opening of screen 122 fall to the chamber floor 121 where it is further filtered by tertiary filter 130. Tertiary filter 130 includes a front dividing wall 131 of wedgewire mesh and filter mats 126.

The front dividing wall 130 may retain silt and the like whereas the filter mats 12 0, 126 may retain liquid contaminants or pollutants such as oil. Liquid filtering through the tertiary filter 130 may be discharged from tertiary outlets 127.

There is a ridge portion 120 that separates the two sides of filter mats 126.

The filter assembly 110 includes a lid 119 with grate 119a. The grate 119a provides access to the inside of the assembly for maintenance and cleaning purposes as well as provide a facility for overflow.

The filter assembly 40 illustrated in Figs. 8, 9 and 10 maintains most of the features of the above described embodiment, however there are differences which are described below. For comparison similar reference numerals are used for corresponding parts.

The concrete housing 10a maintains an elevated circular inlet aperture 14a in the inlet wall 12a and an open part-circular blocking filter wall 16a extending between the inlet wall 12a and the outlet wall 13a for directing full 9S a: flows to the outlet aperture 15a. However the blocking filter wall 16a is in the o 15 form of a solid half pipe conveyor with elongate slots 16b formed therein adjacent the inlet aperture 14a and upstream the secondary filter 22a which is in the form of a mesh or bar type wall extending between the side walls Slea" 17a and from the bottom wall 21a to the underside of the blocking filter wall 16a.

20 The removable filter mats 26a are suitably formed of aerated nylon fabric material or the like and are positioned at opposite sides of the ridge portion 20a. Side outlets 27a are formed in the outlet wall 13a at opposite sides of the main outlet aperture 15a which extends to the base wall 21a.

However in this embodiment the blocking filter wall 16a terminates short of the outlet wall 13a at a position at which a further mesh type filter wall 41 extends across the housing and at which the ridge portion 20a terminates. The blocking filter wall 16a is supported by the secondary filter 22a and the filter wall 41.

A removable filter basket 46 extends to opposite sides of the blocking filter wall 16a between the filter wall 41 and the outlet wall 13a. A coarse wire basket 38a is provided downstream from the outlet 15a. A removable top ."'.panel 43 provided with a lifting lid 44 adjacent the inlet 9* 9 15 wall 12a and a lifting grate 45 adjacent the outlet wall 13a is provided to close the housing lla. The grate 45 provides flood release in case the outlet 15a is restricted or blocked as well as access to the removable basket 46.

.9I Typically normal regular shallow flows will pass through 20 the slots 16b for collection in the chamber formed behind the r secondary filter wall 22a. The filtrate therefrom will flow onto the filter mats for collection of further contaminates such as oils and greases and the like and then through the further mesh wall 41 to the outlets side outlets or main outlet.

Storm flows which may contain debris will pass directly along the blocking filter wall 16 to the -outlet 15a without 14 significantly disturbing the material filtered by the secondary and further filters from which material can be removed for safe disposal either before or after a storm flow. If desired a storage tank such as a one thousand litre tank may be provided beneath the housing 11 or lla to receive filtrates from the side outlets and resulting from shallow flows for subsequent disposal remote from the normal stormwater outlet.

Slight storm flows or the like may discharge into the basket 46 whereas strong storm flows will mostly pass directly to the coarse basket 38a which will trap large objects contained in the storm flow without blocking the outlet 15a. The basket 38a may be of any desired size for *this purpose.

S 15 It will of course be realised that the above has been

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i. given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as is da 20 defined in the appended claims.

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Claims (12)

1. A filter assembly including:- a housing having opposed sidewall portions; an inlet to the housing in one of said sidewall portions; a first outlet in the other of said sidewall portions; an elevated flow guide which serves to guide liquid between the inlet and the first outlet; a diversion drain in a leading end of said flow guide which diverts a shallow flow including debris carried therewith from the elevated flow guide; a filter chamber in said housing below said elevated flow guide in which said debris may collect and liquid from the shallow flow pass through a second outlet.

2. A filter assembly as claimed in claim 1, including blocking means for blocking passage of large objects into the diversion drain. C

3. A filter assembly as claimed in claim 1 or 2, wherein the elevated flow guide is an open channel member.

4. A filter assembly as claimed in any one of claims 1 to 3 wherein the diversion drain includes a bar type filter disposed with elongate 16 openings extending longitudinally with respect to the elevated flow guide. A filter assembly as claimed in any one of the preceding claims wherein the inlet is at an elevated position relative to the first outlet.

6. A filter assembly as claimed in any one of the preceding claims wherein the outlet has an opening which is larger than an opening of the inlet. .6

7. A filter assembly as claimed in any one of the preceding claims wherein there is a secondary filter located below the elevated flow guide. 15 8. A filter assembly as claimed in claim 7 wherein the secondary filter 6 includes a bar type filter or grille type filter in a leading end thereof and substantially below the diversion drain.

9. A filter assembly as claimed in claim 7 or 8, wherein solids or liquid prevented from passing through the secondary filter are discharged through a secondary outlet. 17 A filter assembly as claimed in any one of the preceding claims wherein a tertiary filter is located at the base of the housing and includes a front dividing wall and a filter mat.

11. A filter assembly as claimed in any one of the preceding claims wherein the housing has a top wall with one or more access openings.

12. A filter assembly as claimed in claim 11 wherein one of the access openings is covered by a grate.

13. A filter assembly as claimed in any one of the preceding claims wherein there are on or more removable filter baskets downstream of the flow guide for the collection of rubbish from said flow guide. 15 14. A filter assembly substantially as hereinbefore described with o*o° reference to the accompanying drawings.

15. A method of filtering liquid flows including C providing a filter assembly as claimed in any one of the preceding claims to receive flows through a common inlet; separating different flows depending on their flow characteristics; filtering different flows; and discharging liquid from the outlets. -,it 18

16. A method of filtering liquid flows as substantially described herein with reference to the accompanying drawings. DATED THIS SEVENTEENTH DAY OF JULY 2000. C-M CONCRETE PRODUCTS PTY LIMITED BY V 9 9 9 q a. V a a PIZZEYS PATENT TRADE MARK ATTORNEYS. S oo