GB2413774A

GB2413774A - A water filter system

Info

Publication number: GB2413774A
Application number: GB0507973A
Authority: GB
Inventors: Eric Alan Fewster; Adriaan Mol
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-04-20
Filing date: 2005-04-20
Publication date: 2005-11-09
Also published as: GB0408732D0; GB0507973D0; GB2413292A

Abstract

The invention relates to a water filter system 100 for providing potable water. The system 100 comprises a container 10, the container 10 having an upper portion and a lower portion, the upper portion having a water inlet 1 and a water outlet 2, the lower portion having a filter material therein, and an integral channel 3, 7, the channel 3, 7 providing a flow path between a lower region of the lower portion of the container 10 and the water outlet 2, wherein a portion of the container 10 has a tapered circumference, said portion being disposed between a bottom of the container 10 and a top of the container 10, such that the container 10 is stackable. The system is easier to transport, less complex to install, and less vulnerable to damage.

Description

24 1 3774

WATER FILTER SYSTEM

This invention relates to water filters, and in particular to intermittently operated sand filters used for improving the quality of raw water.

A wide variety of systems for purifying water are known, from industrialscale water treatment plants to table top jug filters. However, large scale facilities are prohibitively expensive to many people living in remote and underdeveloped areas. It is therefore desirable to provide a system suitable for 'household' or 'point-of-use' water treatment, whereby relatively small amounts of water are purified on an intermittent basis to suit the immediate needs of a user or group of users, rather than for larger communities.

US 5,225,078 discloses a pour-though pitcher filter assembly including a compact filter element having a thin annular disk of moulded activated carbon and a peripheral annular seal element. Water to be purified is poured into a plastic reservoir supported in an upper portion of the pitcher. The water is fed under gravity through the filter element in a lower region of the plastic reservoir, and filtered water then drains into the lower portion of the pitcher. Filtered water may be dispensed by pouring water from the lower region through a spout by a tipping action. Filters of this type are limited, however, in the types and amounts of contaminant that they can remove from the water. .

. One solution to the problem is a slow sand filter, for use with an intermittently flowing ë water supply. In slow sand filter systems, water is percolated through a column of sand.

. In the top layers of the sand, a beneficial aerobic biological layer is allowed to form. The layer is formed by numerous organisms including algae, plankton, diatoms, protozoa and bacteria. While inert particles in the raw water are removed mechanically by the sand, a..

; organic matter is entrapped, broken down and digested by the biological layer. Systems .. of this type are able to remove bacteria, parasites, Giardia cysts, Cryptosporidium oocysts and viruses. Slow sand filters also greatly reduce turbidity as well as pathogenic contamination. A properly functioning slow sand filter can produce water of excellent quality, often well within the quality standards set for human consumption.

The biological layer needs nutrients and oxygen for survival. Whilst the nutrients are typically available in the water itself, the supply of oxygen is more problematic. In ordinary slow sand filters, oxygen is supplied by the regular flow of (oxygenated) water through the filter. However, if the filter is used intermittently, whereby there are periods when water is present in the filter but not flowing through the filter, oxygen levels become depleted and the biological layer begins to die. Thus, in an intermittent slow sand filter, the biological layer can only survive for a prolonged period in the absence of flowing water if the system maintains a level of no more than approximately 8 cm of standing water above the top of the sand. Oxygen can permeate through this shallow water level and still reach the biological layer, maintaining it in a living condition.

Traditional slow sand filters usually maintain depths of water greater than 50 cm above the sand. In the absence of a significant flow, the water turns rapidly stagnant and the biological layer starts to die.

Since no permanent flow is required by an intermittent slow sand filter, these filters can be used where water is scarce, difficult to obtain or only needed in small quantities.

Consequently they are being used increasingly to provide water for drinking or other purposes to people relying on contaminated water sources, especially in developing countries. Intermittent slow sand filters are particularly well suited for household or point-of-use water treatment.

CA 2,105,650 discloses an intermittently operating slow sand filter which uses the damming of water in a raised pipe to provide a constant level of water in a slow sand filter container. The container includes a water inlet, and a water outlet protruding from the container. The container is partially filled with sand and other material. The ë container has the disadvantage that it is of a substantial size, non-portable, and the .e protruding pipes are vulnerable to damage. e.

Commercially available plastic filter receptacles are built up from several components that are joined together. Once assembled, such filters are not stackable due to the ë absence of a suitable taper, and the presence of protruding pipes, channels and other .. components which increase the overall volume of the system substantially. The outlet of these filters is also typically an external pipe protruding from the main filter compartment, which is vulnerable to damage during transport and use.

The filters may be provided to the end user in the form of a 'kit' or 'set' whereby the final unit is assembled from several components on-site. The presence of a large number of small parts complicates a wide distribution of filter kits, for instance during emergencies, whilst the final assembly procedure is often a major obstacle for the intended users. The problem of assembly is especially evident in underdeveloped areas where the majority of a population are uneducated and have little or no exposure to technology. The majority of users may lack the basic technical insight, literacy or otherwise to assemble the kits.

Consequently the number of filters successfully assembled to date is low.

Alarmingly, it is also possible for a filter to be assembled incorrectly, such that raw water is delivered directly to the outlet rather than passing through the filter material.

In a first aspect of the present invention there is provided a water filter system suitable for use in providing potable water, the system comprising: a container, the container having: an upper portion and a lower portion, the upper portion having a water inlet and a water outlet, the lower portion having a filter material therein, and an integral channel, the channel providing a flow path between a lower region of the lower portion of the container and the water outlet, wherein a portion of the container has a tapered circumference, said portion being disposed between a base of the container and a top of the container, such that the container is stackable.

The invention has the advantage that the water filter system may be transported in a pre-assembled form. There is a lower risk of damage to the system since no external pipes or fittings are required. Furthermore, because the system is stackable, transportation costs are also reduced. By stackable is meant that two or more a. containers can be stacked or nested together. ..-

The channel may be defined by a portion of the outer wall of the container and a ' channel-defining wall depending from or otherwise attached to said outer wall. Typically the channel-defining wall may be a single wall of curved shape in cross-section, or a plurality of conjoined wall-portions. The outer wall and channel-defining wall are normally connected along at least two edges of the channel-defining wall.

.....

Alternatively, the container may have an inner lining, the channel being defined by a gap between a portion of a wall of the container and a portion of a wall of the inner lining.

Preferably, at least a portion of an inner surface of a wall of the container is roughened.

Where an inner lining is used to define the channel, preferably at least a portion of an inner surface of a wall of the inner lining is roughened. This helps to prevent raw water from 'short-circuiting' to the bottom of the filter material via the walls of the container, rather than passing through the filter material.

Preferably, a diffuser plate is provided in an upper portion of the container. The diffuser plate diffuses the flow of water into the system such that the flow is distributed over a larger area of the filter material. This helps to prevent disturbance of the biological layer.

Preferably the diffuser plate is formed integrally with the system, thereby reducing the assembly time and cost of the system.

Preferably the water outlet comprises a spout. The spout may be adapted to reduce unsteady flow from the spout. Furthermore, the spout may be formed such that the spout is flush with a wall of the container.

Preferably the filter material comprises a layer of sand.

Advantageously, the filter material further comprises a layer of coarse elements disposed below the layer of sand. The layer of coarse elements may comprise stones, gravel, crushed brick, or any other suitable coarse element.

Preferably, at least a portion of the filter material comprises a bactericidal or bacteriostatic material. The bactericidal or bacteriostatic material may be colloidal silver . or any other suitable bactericidal or bacteriostatic material. The bactericidal or .

bacteriostatic material may be coated on the filter material. Alternatively it may be . impregnated into the filter material. Impregnation has the advantage of prolonging the : .. . life of the filter material. ..

Id. 25 Either or both of the coarse elements and the sand layer may be coated or impregnated with colloidal silver. . 0 e

The system may be collapsible from an expanded use configuration to a compact configuration, so as for example to reduce the volume of the system for transportation.

Alternatively or in addition, the system may comprise at least one inflatable portion. This provides for the possibility of reducing the weight and / or volume of the filter so as to relieve the burden of transporting the system.

The system may be made from plastic, resin or a similar strong and lightweight material, thus reducing the weight per unit, as well as risk of breakage, when compared with concrete or ceramic. Preferably, the filter is mass-producible, resistant to ultraviolet light and has a structural integrity that is maintained within ambient temperatures of O 50 C.

A variety of fabrication processes may be used to make the system, including blow moulding of a plastics material.

In plan view, the receptacle can be of any shape, including round, oval, square or triangular.

In a second aspect of the invention there is provided a water filter system suitable for use in providing potable water, the system comprising: a container, the container having: an upper portion and a lower portion, the upper portion having a water inlet and a water outlet, the lower portion having a filter material therein; and a channel, the channel providing a flow path between a lower region of the lower portion of the container and the water outlet, wherein the filter material comprises a bactericidal or bacteriostatic material.

For a better understanding of the present invention, and to show how it may be carried into effect, reference will now be made by way of example to the accompanying a drawings, in which: FIGURE 1 is a front elevation of a complete filter system according to a first embodiment : . .. of the invention; . 25 FIGURE 2A is a cross section along line A-A of Figure 1; ram FIGURE 2B shows the portion indicated by 'B' in Figure 2A on an enlarged scale; - FIGURES 3A, 3B show respective perspective and cross-section views of a filter system according to a second embodiment of the invention, and FIGURE 3C shows a portion of the system of Figure 3B on an enlarged scale; FIGURE 4 shows a diffuser plate for use with a filter system according to the first embodiment of the invention; FIGURE 5 is an exploded view of a filter system according to the first embodiment of the invention; FIGURE 6 is an enlarged view of a portion of a rim of the main compartment and a rim of the inner lining of the first embodiment of the invention prior to installation of the inner lining; FIGURE 7 is an enlarged view of a portion of a rim of the main compartment and a rim of the inner lining of the first embodiment of the invention following installation of the inner lining; FIGURE 8 is a front elevation of a pair of filter systems according to the first embodiment of the invention in a stacked configuration; FIGURE 9 is a side elevation of a pair of filter systems according to the first embodiment of the invention in a stacked configuration; FIGURE 10 is a perspective view of a pair of filter systems according to the first embodiment of the invention in a stacked configuration; . FIGURE 11 is a plan view of a filter system according to the first embodiment of the -.

invention; . FIGURE 12 is a perspective view of the water outlet and a spout section of a filter *. 25 system according to the first embodiment of the invention. . -

In a first embodiment of the invention, a filter system 100 comprises (Figure 1, Figure 2A *. and Figure 2B), a main compartment 10 having an outer wall 4, an inner compartment 20, a water inlet 1 and a water outlet 2, and a channel 3 running between the water outlet 2 and a lower portion of the main compartment 10.

Figure 2A shows a cross-sectional view of the filter system 100 along the line A-A of Figure 1. Figure 2B shows an enlarged view of the portion 'B' of Figure 2A, where the channel 3 is located. The channel 3 is defined by an outer wall 4 of the main compartment 10 and a recessed portion 5B of a wall 5 of an inner compartment 20. The inner compartment 20 is in the form of an insert that slots into the main compartment 10, forming a close fit to the main compartment 10 with the exception of the portion of the wall 5B of the inner compartment 20 defining the channel 3. The inner compartment 20 is partially filled with sand or other suitable filter material, to a level 11 that provides a height difference of substantially 8 cm between the top of the filter material 11 and the level 14 of the water outlet 2. In alternate embodiments, a height difference from substantially 1cm to substantially 8cm is employed. This ensures that the water level above the filter medium will be maintained in the range from substantially 1cm to substantially 8cm.

The bottom 20A (Figure 2A) of the inner compartment 20 is spaced apart from the bottom 10A of the main compartment 10. The bottom 20A is provided with a plurality of holes 6 thereby providing a fluid flow path from the inner compartment 20 to the portion of the main compartment 10 below the inner compartment 20. The channel 3 completes the flow path to the water outlet 2. The inside surface 5A of the wall 5 of the inner compartment 20 is roughened to avoid water short-circuiting the filter material by running along the inside surface 5A.

Figure 5 illustrates how the channel 3 is formed when the main compartment 10 and inner compartment 20 are assembled together. The inner compartment 20 is held in place within the main compartment 10 using suitable cooperating engagement formations such as a pair of latches 15 (Figures 5 - 7) disposed on opposite edges of a rim 110 of the main compartment 10 that interlock with a pair of slots 150 disposed on opposite edges of a rim 22 of the inner compartment 20. The rim 22 of the inner : .. . compartment 20 has a radial flange 22A having a depending skirt 22B such that the rim - . . 25 22 can hook over the rim 110 of the outer compartment 10. This assists in preventing contamination of filtered water with raw water. .. ...

: As shown in Figures 5 and 12, the outlet is protected from contamination by a cover 12 - moulded into the inner compartment 20 above the recessed portion 5B of the wall 5.

The water outlet 2 can be enhanced by means of a specially formed spout 13 (Figure 12) to reduce uncontrolled dribbling of water from the opening, facilitating easier collection in a bucket, for example.

As shown in Figures 4 and 5, a diffuser plate 30 is installed in an upper portion of the inner compartment 20 to diffuse the flow of raw water poured into the filter system. In a variation of this embodiment the diffuser plate 30 is formed integrally with the inner compartment 20. That is, the inner compartment 20 and the diffuser plate 30 form a single component, e.g. a single moulded component.

Filter material is placed within the inner compartment 20 such that a height difference between the top of the filter material 11 and the top 14 of the channel 3 (Figure 5) is sufficient to ensure both an adequate depth of filter material within the inner compartment 20 for proper filtration, and a level of water above the top of the filter material that is within the appropriate range when a flow of water into the filter via the inlet 1 ceases and the water level in the inner compartment 20 equilibrates with that in the channel 3. The water level should usually be maintained in the range of substantially 1cm to substantially 8 cm above the filter material, although the most appropriate range in a given installation may vary subject to a variety of factors including variations in the local environmental conditions.

With a water level maintained in this range, the biological layer, which forms at the top of the filter material, remains submerged to such a depth that it does not dry out. Sufficient oxygen continues to permeate into the water to prevent the layer from dying, yet the layer is deep enough so that it is not significantly disturbed by the pouring of water into the filter.

When the filter is in operation, water, having passed through the filter material, passes ..

* through the holes 6 in the bottom 20A of the inner compartment 20 and is forced up through the channel 3 before emerging from the outlet 2. When the flow of water into the inlet 1 ceases, equalization of water levels in the inner compartment 20 and the channel - . 25 3 occurs as water emerges from the outlet 2. This results in water remaining in the inner compartment 20 to a level substantially equal to that of the top 14 of the channel 3.

- ..

Typically the filter material may comprise a layer of crushed bricks, with a layer of sand above the layer of crushed bricks. In this embodiment, the sand and bricks are impregnated with colloidal silver to provide antibacterial properties, which has a beneficial effect on the quality of the filtered water. In a variation of the first embodiment of the invention the sand and bricks are coated with colloidal silver. In further variations of the embodiment gravel or stones are used instead of crushed bricks.

The main compartment 10 and the inner compartment 20 are tapered toward the bottom 1 OA of the main compartment 10 to ensure that one filter system 100 can be stacked on top of another filter system 100. Filter systems according to the first embodiment are shown in a stacked configuration in Figures 8, 9, 10 and 11. It can be seen that each filter fits into the next up to the level of the outlet 2.

A second embodiment of the invention is shown in Figure 3. Features of this embodiment in common with the first embodiment will be described using corresponding reference numerals.

In this embodiment, a channel 7 is provided between the water outlet 2 and the bottom 10A of the main compartment 10 by a channel-defining wall 9 connected along two edges 9A, 9B to the outer wall 4 of the main compartment 10. The channel-defining wall is shaped to meet the main compartment 10 at the bottom 10A of the container 10. An aperture 40 in the outer wall 4 of the main compartment 10 at a lower region of the outer wall 4 provides a flow path between the water inlet 1 and the water outlet 2. There is therefore no requirement to insert an inner compartment 20 into the main compartment in order to form the channel.

The filter device according to the second embodiment is also tapered, towards the bottom 1 OA of the main compartment 10 to facilitate stackability.

There may be circumstances in which the integral channel and the ability to stack the -.

water filter systems are not strictly necessary, although preferred. Thus, in alternate embodiments of the invention, the channel is not formed integrally with the system. In further alternate embodiments, the channel is formed integrally with the system, but the .- A. 25 system is not tapered, and therefore the system is not stackable. However, in each of these embodiments, the presence of the bactericidal or bacteriostatic material still provides the advantage of an enhanced quality of the filtered water. e.. .

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises, means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

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. - . .. : - . .. .-.

Claims

CLAIMS: 1. A water filter system suitable for use in providing potable

water, the system comprising: a container, the container having: an upper portion and a lower portion, the upper portion having a water inlet and a water outlet, the lower portion having a filter material therein, and an integral channel, the channel providing a flow path between a lower region of the lower portion of the container and the water outlet, wherein a portion of the container has a tapered circumference, said portion being disposed between a base of the container and a top of the container, such that the container is stackable.
2. The system of claim 1 wherein the channel is defined by a wall of the container and a channel-defining wall connected along at least two edges of the channel-defining wall to the wall of the container.
3. The system of claim 1 wherein the system includes an inner lining.
4. The system of claim 3 wherein the channel is defined by a wall of the container and a wall of the inner lining. ...

.. .
5. The system of any one of claims 1 to 4 wherein at least a portion of an inner surface . e of a wall of the container is roughened. :.
6. The system of claim 3 or claim 4 wherein at least a portion of an inner surface of a ...

wall of the inner lining is roughened. -
7. The system of any one of claims 1 to 6 wherein a diffuser plate is provided in an upper portion of the container.
8. The system of claim 7 wherein the diffuser plate is formed integrally with the system.
9. The system of any one of claims 1 to 8 wherein the water outlet comprises a spout.
10. The system of claim 9 wherein a shape of the spout has a shape adapted to reduce unsteady flow from the spout.
11. The system of claim 9 or claim 10 wherein the spout is so shaped that the spout is flush with a wall of the container.
12. The system of any one of claims 1 to 11 wherein the filter material comprises a layer of sand.
13. The system of claim 12 wherein the filter material further comprises a layer of coarse elements disposed below the layer of sand.
14. The system of any one of claims 1 to 13 wherein at least a portion of the filter material comprises a bactericidal or bacteriostatic material.
15. The system of claim 14 wherein the filter material is coated with the bactericidal or bacteriostatic material.
16. The system of claim 15 wherein the filter material is impregnated with the bactericidal or bacteriostatic material. .e

.' '
17. The water filter of any one of claims 14 to 16 wherein the bacteriostatic or ..* bactericidal material is colloidal silver. .
18. The system of any one of claims 1 to 17 wherein the system is collapsible from an expanded use configuration to a compact configuration. .-

. . . a
19. The system of any one of claims 1 to 17 wherein the system comprises at least one -

inflatable portion.
20. A water filter system suitable for use in providing potable water, the system comprising: a container, the container having: an upper portion and a lower portion, the upper portion having a water inlet and a water outlet, the lower portion having a filter material therein, and a channel, the channel providing a flow path between a lower region of the lower portion of the container and the water outlet, wherein the filter material comprises a bactericidal or bacteriostatic material.
21. The system of claim 20 wherein the filter material further comprises a layer of sand.
22. The system of claim 21 wherein the sand is coated with the bactericidal or bacteriostatic material.
23. The system of claim 21 wherein the sand is impregnated with the bactericidal or bacteriostatic material.
24. The system of any one of claims 21 to 23 wherein the filter material further comprises a layer of coarse elements disposed below the layer of sand.
25. The system of claim 24 wherein the coarse elements are impregnated with the bactericidal or bacteriostatic material.
26. The system of claim 24 wherein the coarse elements are coated with the bactericidal or bacteriostatic material. ..
27. The system of any one of claims 24 to 26 wherein the coarse elements comprise at ..

least one material selected from amongst gravel, stones and crushed bricks.

25
28. The system of any one of claims 20 to 27 wherein the channel is formed integrally ë with the system. .- .
29. The system of claim 28 wherein the channel is defined by a wall of the container

I

and a channel-defining wall connected along at least two edges of the channel-defining wall to the wall of the container.
30. The system of claim 28 wherein the system includes an inner lining.
31. The system of claim 30 wherein the channel is defined by a wail of the container and a wall of the inner lining.
32. The system of any one of claims 20 to 31 wherein a portion of the container has a tapered circumference, said portion being disposed between a base of the container and a top of the container, such that the container is stackable.
33. A system substantially as hereinbefore described with reference to any of the accompanying drawings. ë ... ... c.. . ë e.