NZ332958A - Filter apparatus including a housing, disc filters and conduit from filters to output - Google Patents

Abstract

A filter includes a housing 14 with apertures 12 in a side wall for effluent input from a septic tank, closely adjacent discs 16, with effluent breakdown bacteria living on the surfaces, located on the central shaft 11a and an output 13 through a wall at the upper end for treated effluent. A central shaft extends through a lid 11 to form an extendable handle 11a for ease of removing the disc cluster from the housing. Effluent entering through the input 12 is restricted to follow a path through the disc cluster into the central shaft via slits 17 to the output.

Description

No: 332958 Date: 23 November 1998 NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION IMPROVEMENTS IN FILTER APPARATUS We, GOULD GT SYSTEMS (NZ) LIMITED a New Zealand company of 14 Lyndale Place, Palmerston North, New Zealand 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 pNTRl£CfUAT?ROPERlY=OmCEl OF N.Z. 2 3 FEB [received 2 The present invention relates to improvements in filter apparatus, particularly filter apparatus for use at a primary stage of effluent treatment, such as in a septic tank.

Various effluent treatment and septic tanks are known which take the sewage output from say a domestic dwelling and treat it sometimes to an extent whereby the resultant treated water can be reused for garden use or ground irrigation.

Typically, a septic tank is a settling tank which accumulates sludge over time from the effluent which enters and exits the tank. Bacteria residing within the tank breaks down solids and partially processes the effluent to reduce Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS). Processed effluent may then be pumped or gravity fed out of the septic tank (eg. for further treatment).

It is known for septic tanks to include additional physical/biological filtering means, particularly at the output end. For example, disc filters are known which include multiple layers of finely separated discs over which effluent may pass.

SPEC 1150 23 Februaiy, 2000 3 0 ^ 4"\[ t Bacteria develops on the disc layers and additionally processes the effluent by biological means. Existing disc filters have varying effectiveness based on design constraints and are usually of a * cartridge' type which can be removable for cleaning.

The use of a filter of this type in a septic tank substantially reduces the BOD and TSS level of the output effluent. This reduces the processing load on subsequent filtering stages and thereby increases efficiency.

The object of the present invention is to provide a filter (for use in septic tanks, grease traps and the like) which provides an improvement over other available filter apparatus or at least provides the public with a useful alternative In one broad aspect of the invention there is provided a filter apparatus including a housing with effluent input means and spaced therefrom processed effluent output means and a plurality of closely adjacent surfaces over which the effluent may pass, characterised in that a conduit means is provided toward the output means and that said effluent is restricted to follow a path after entry into the housing which leads it through the closely adjacent surfaces and to said conduit means and then to the output means. intellectual property office of n.z.

SPECI 150 2 7 APR 2001 RECEIVED 26 April. 2001 4 The filter apparatus of the present invention is herein described with reference to its preferred application, ie. domestic and commercial septic tanks. However, a number of other uses may exist where the present invention is equally applicable. Such other uses are well within the scope and intention of the present invention.

The filter apparatus according to the present invention will now be described with reference to the accompanying drawings, illustrating two preferred embodiments, where:- Figure 1 is a general perspective view of a filter apparatus according to the invention, including a cutaway section, Figure 2 is a cross section view of the portion A-A shown in Figure 1, Figure 3 is a general perspective view of a second preferred embodiment, including a cut-away section, and Figure 4 is a cross-section view of the portion B-B shown in Figure 3.

SPEC 1150 23 Februaiy, 2000 Referring to the first embodiment (Figures 1 and 2), the filter apparatus 10 (hereinafter referred to as a disc filter) is principally comprised of a lid means 11, including a handle shaft 11a, input apertures 12 and output means 13 formed in the walls of a main housing 14, a stabilising rod 15 and a plurality of substantially uniform discs 16.

Preferably the shaft of handle 11a extends substantially down the centre of the entire length of main housing 14 and the discs 16 are fixed at suitable intervals on the shaft 11a. Therefore the lid 11, handle 11a and all discs 16 can be removed from the filter housing 14 as a single unit for cleaning etc.

A particular feature of this removal arrangement is the relatively long length of handle 11a. In common septic tank installations the actual tank and therefore the lid 11 and access to the filter may be well below ground level. This can make it exceptionally difficult or inconvenient to remove the discs 16 in an existing disc filter because the handle 11a is part of, or does not extend far from, the lid 11. The extended height of the shaft/handle 11a in the present invention (which in further embodiments may be telescopic, ie extendable) makes access to the disc filter more convenient for the user.

SPEC 1150 23 February, 2000 6 The gap between the man-hole on the septic tank (not illustrated) and the top of the disc filter may be one meter or more. Therefore the handle 11a of the present invention is a particular advantage to users.

Typically the cluster of discs 16 of the preferred embodiment are 1 to 1.5mm thick and spaced 1mm apart. Greater numbers of discs 16 provide greater surface area on which bacteria may cultivate. The capacity of the disc filter 10 needed may be determined by the volume of the septic tank to which it is to be applied, however, by way of example the preferred embodiment includes a disc cluster 16 approximately one meter high with discs approximately 120mm in diameter.

Installation of the housing 14 is aided by the stabilising rod 15 which can be adjusted to length and contacts or is set in to the inner wall of the septic tank. Primary stability comes from output means 13 which extends through the wall of the septic tank (not illustrated).

Figure 2 best illustrates the functional characteristics of the disc filter in action. Three different effluent 'stages' are shown by Figure 2 as effluent is processed through the filter 10.

SPEC1150 23 February, 2000 7 Firstly, effluent enters the housing 14 via input apertures 12 (which are in the form of a series of circular holes) . By example, there are two such sets of apertures 12 arranged at substantially the lower end of the filter 10. Once inside the housing 14 effluent may move freely within a first chamber C which is formed between the disc cluster 16 and the inner wall of housing 14 .

Secondly (and immediately) the effluent enters the disc cluster 16 where bacteria resides on the surfaces B of the discs 16. Here the bacteria breaks down the effluent (larger solids may not enter the bacteria chamber B by virtue of the 1mm gap between the discs).

Thirdly, effluent may flow into the exit channel X which leads toward the output means 13 located substantially at the upper end of the filter 10. Effluent passing through channel X has been through the bacterial/physical filtration of the disc cluster 16 and has substantially reduced BOD and TSS levels. The effluent level in the septic tank and filter 10 rises until it 'over flows' through output 13 and on to further processing.

The construction of housing 14 includes two full length indentations 14a in its cylindrical wall which touch the SPEC 1150 23 February, 2000 8 edge of discs 16 and form channel X. In this way the effluent must first pass through the disc cluster 16 before it can exit the filter. In the preferred embodiment illustrated channel X occupies approximately one quarter to one third of the total circumference of housing 14.

The flow of effluent through the filter is usually very slow and as such there is little pressure to * force" larger particles into the disc cluster 16 and through to channel X. Also, treated effluent cannot exit through output 13 until the effluent level outside the filter 10 has reached at least the bottom of output 13 (this gives a lengthy "residency" time within the filter). Once the effluent has reached this level there will be a constant flow of treated effluent out of output 13 (eg. for further processing).

Preferably the entire componentry of the disc filter 10 is produced from a plastics material, eg. polyethylene housing 14 and polystyrene discs 16. This will ensure long service life (no rusting etc).

Referring now to the second embodiment (Figures 3 and 4), the essential components of the filter 10 are equivalent to that described by Figures 1 and 2.

SPEC 1150 23 February, 2000 9 The principal difference in construction between Figures 1,2 and 3,4 respectively is in the arrangement of exit channel X which, in Figures 3 and 4, extends centrally through the disc cluster 16 within shaft 11a. The exit channel is best seen by Figure 4.

Shaft 11a (as illustrated by Figures 3 and 4) includes slot-like apertures 17 which receive effluent after it has passed over discs 16 (the arrangement illustrated by Figure 3 shows the majority of discs 16 removed so slots 17 are visible).

The housing 14 shown in dotted detail does not require * indentations" 14a to form the exit channel X as shown by the first embodiment. However, it does include corresponding input apertures 12 for allowing effluent to enter the filter.

Once effluent has passed over surfaces B of discs 16 it may enter hollow shaft 11a via slots 17 and exit the filter at the top end via output 13 formed through the wall of shaft 11a.

The second embodiment may be constructed with similarly sized discs 16 (ie 120mm in diameter x 1.5mm thick) however, it is preferred that the spacing be 0.1mm in order to create a finer filter than the first embodiment.

SPEC 1150 23 February, 2000 The filters of Figures 1 and 3 respectively, in use, are arranged in series in the treatment plant such that the effluent containing finer particles after processing by the Figure 1 filter is further processed by the Figure 3 filter. The filters may be situated in different tanks containing different types of bacteria.

The advantage of either filter embodiment, as previously mentioned, is that effluent must pass over the bacteria surface B before exiting the filter.

Existing disc filter arrangements simply rely on a long residency time of effluent within the filter to achieve efficient processing, however, the effluent stream is not directed such that it must all pass over the disc surfaces before it can exit the filter.

The disc filters of each embodiment according to the present invention are a simple and hence cheap-to-produce alternative to existing disc filter arrangements and may be sized to meet specific usage requirements.

SPEC 1150 23 Februaiy, 2000 11 r-> _ *V

Claims (15)

WHAT WE CLAIM IS:-

1. A filter apparatus including a housing with effluent input means and spaced therefrom processed effluent output means and a plurality of closely adjacent surfaces over which the effluent can pass, characterised in that a conduit means is provided toward the output means and that said effluent is restricted to follow a path after entry into the housing which leads it through the closely adjacent surfaces and to said conduit means and then to the output means.

2. The filter apparatus of claim 1 wherein the effluent input means is in the form of at least one aperture formed in a side wall of the housing.

3. The filter apparatus of claim 2 wherein the aperture is formed at a lower end of the side wall.

4. The filter apparatus of any one of claims 1 to 3 wherein the plurality of closely adjacent surfaces is in the form of a cluster of substantially disc shaped elements (disc cluster).

5. The filter apparatus of claim 4 wherein discs of the disc cluster are located upon a central shaft. SPEC1150 intellectual property office of n.z. 2 7 APR 2001 RECEIVED 26 April. 2001 12

6. The filter apparatus of claim 5 wherein the central shaft extends through a lid means for covering the housing.

7. The filter apparatus of claim 4 or 5 wherein the central shaft forms a handle means for removing the disc cluster from the housing.

8. The filter apparatus of any one of claims 5 to 7 wherein the shaft includes an extendable end.

9. The filter apparatus of any one of the preceding claims wherein the housing includes at least two longitudinally extending protrusions spaced apart on an internal side wall of the housing which substantially contact the plurality of closely adjacent surfaces over which effluent can pass, thereby forming the conduit means toward the output means.

10. The filter apparatus of any one of claims 1 to 3 wherein a substantially hollow shaft, including apertures between an interior and exterior of said shaft, is provided upon which the plurality of closely adjacent surfaces are mounted, said hollow shaft thereby forming the conduit means toward the output means. intellectual property office of n.z. 2 7 APR 2001 RECEIVED 26 April. 2001 13 shaft thereby forming the conduit means toward the output means.

11. The filter apparatus of claim 10 wherein the plurality of closely adjacent surfaces is in the form of a cluster of substantially disc shaped elements (disc cluster).

12. The filter apparatus of claim 10 or 11 wherein the output means is formed through a wall at an upper end of the hollow shaft.

13. The filter apparatus of claim 11 or 12 wherein the hollow shaft includes a handle means at its uppermost end for removal of the shaft and disc cluster from the housing.

14. The filter apparatus of any one of the preceding claims wherein a stabilising element extends from the housing.

15. A filter apparatus substantially as herein described with reference to the accompanying drawings. GOULD GT SYSTEMS (NZ) LIMITED By its Attorney DON HOPKINS & ASSOCIATES Per: SPECl 150 23 February, 2000