WO2009087670A2

WO2009087670A2 - Gravity operating ceramic water filter

Info

Publication number: WO2009087670A2
Application number: PCT/IN2008/000840
Authority: WO
Inventors: Van Der Ven Klaas; Ries Korse
Original assignee: Basic Water Needs B.V.
Priority date: 2008-01-04
Filing date: 2008-12-16
Publication date: 2009-07-16
Also published as: WO2009087670A3; WO2009087670A4

Abstract

The present invention relates to a gravity operating ceramic filter incorporating a ceramic filter element for filtering particulate matter from the liquids especially from the water and it includes a self-contained back wash flow arrangement. The invention uses a rubber bulb, different combinations of the non-return valve, tap and automatic shut off mechanism, for starting the siphoning action, for starting the back wash action and for starting to stop the flow of the filtered water when the required amount of water collected in the receptacle.

Description

Gravity Operating Ceramic Water Filter

FIELD OF THE INVENTION

The present invention relates to a gravity operating ceramic water filter incorporating a ceramic filter element for filtering particulate matter from the liquids especially from the water and includes a self contained back wash flow arrangement.

BACK GROUND OF THE INVENTION For more than 40 years traditional two containers based gravity fed ceramic water filters are used in many of the countries. But these systems have some drawbacks. All systems have a limited output per hour. A one filter element ceramic water filter usually delivers about 0.5 liters per hour. When the filter becomes dirty the flow rate often is reduced to about 0.2 liters per hour. In practice such a system is not enough for delivering drinking water for a family. This is the reason that many filter systems are sold incorporating 2 or 3 ceramic filter elements for a higher output per hour. Another problem in the existing systems is frequent clogging of the ceramic filter element. When the water to be purified contains clay particles or other small particles, the filter becomes clogged and has to be cleaned by removing a small layer from the ceramic element using a knife or hard brush. Existing systems requires a way of cleaning of the filter element, which is not at all user friendly. The filter has to be dismantled first. The wing nut and washer have to be removed. The ceramic filter element has to be taken in the hand to be cleaned and after cleaning the element has to be put back in the original position, applying the washer and tighten the wing nut. In case people do not remove the ceramic filter element before cleaning, the filter often breaks because of the weak bond between the plastic or metal end cap and the ceramic filter element. The traditional filter occupies lot of space in retail outlets and is costly, mainly due to the costs of the two containers (made from rust free steel or plastic) and the cost of the attached tap. Hence there is a system required to overcome the drawbacks of the existing system.

It is the objective of the invention to provide a gravity operating ceramic filter water filter incorporating a self contained back wash arrangement. STATEMENT OF INVENTION

A water purification system operating on a siphoning action comprising a ceramic filter mounted in a filter housing; said filter and housing is placed in a container filled with contaminated water, said ceramic filter is covered by a removable and washable pre- filter to prevent premature clogging of the ceramic filter; said housing having a water inlet opening above the bottom of the filter housing, said filter housing having a lid with an outlet opening for air release and an opening for mounting the ceramic filter with a wing nut. A rubber bulb is connected on one side to the outlet opening of the filter by a flexible hose and on the other side to a non return valve with an attached tap, wherein said bulb in combination with the non return valve tap is used to start the siphoning filtration process and for cleaning the ceramic filter by backwash action.

BRIEF DESCRIPTION OF THE DRAWINGS Fig E shows the water purification system comprises of ceramic filter element in accordance with the invention.

Fig F shows the combination of the rubber bulb with a non return valve with the connected tap.

Fig A1 , A2, Shows the position of the valve in open/closed position.

Fig BI ₁ B2, B3, shows the working of an improved valve comprises of polyurethane foam.

Fig C1 , C2, C3, Shows the working of the non-return valve comprises of an insert in the foam of a small diameter rod shaped element.

Fig D shows the view of pre-filter consisting of two layers of filtration material.

Fig G shows the view of pre-filter placed in a closed jar. DETAILED DESCRIPTION

As can be seen in the Fig E the ceramic filter element (2) with a small diameter hose (3) is placed in an open container (9) that can be a plastic bucket, etc. The container is provided with one or more openings (10) which are positioned a few cm. above the bottom of the jar in order to prevent the settling mud particles to enter into the container (9). The container is provided with a screw cap (11) with a small hole for air release (12) and a larger hole to mount the ceramic filter with a wing nut (13). Referring Fig F along with the Fig E it can be seen that in order to over come the problem of the limited flow rate, the output opening (1) of the ceramic filter element (2) is connected with a small diameter hose (3) of sufficient length to provide the needed under-pressure to create a siphoning effect with sufficient flow.

Again referring to the Fig F, as an example the end of the hose is placed one meter (4) below the water level in the container(5) filled with contaminated water, applying a high porosity ceramic filter element between 4 and 8 liters per hour can be delivered, depending upon the type of the ceramic filter element used. The small diameter hose (3) is filled with water, thus creating an under-pressure (suction force) of 1 meter water column and it can be seen that the same effect could be realized when the ceramic filter would be placed 1 meter below the water level.

Some siphoning ceramic filters are on the market. Using these systems, the user has to suck at the hose in order to start the siphoning action. This is not user's friendly in usage. As shown in the Fig F this invention uses a rubber bulb (6) in combination with a non-return valve (7) with connected tap (8) to start the siphoning action which is much more user's friendly.

One of the objectives of the invention is to solve the problem of frequent clogging of the filter surface caused by silt and other small particles in the water to be filtered. It has been investigated that the rubber bulb, filled with clean filtered water, could be used for cleaning the ceramic filter by back washing action. When closing the tap and pressing the bulb by hand, enough water pressure is created to back wash the ceramic filter. In this way many fine particles that have been trapped in the pores of the filter surface will be removed using this back wash pressure, thus restoring the flow of filtered water. In case the water flow would not be sufficient after back washing, the above procedure can be repeated one or two times.

Using turbid water it has been investigated that, compared to traditional gravity fed ceramic filter, the frequency of the need to clean the ceramic filter surface by removing a small layer of ceramic material, will decrease significant using this back wash action. At each cleaning cycle of the surface of a ceramic candle a thin top layer of ceramic material has to be removed, slightly reducing the wall thickness of the ceramic material. By reducing the needed frequency of cleaning the surface, the effective lifetime of the ceramic filter element will be increased thus reducing the yearly costs for replacement filters.

In order to start the siphoning system, the tap has to be in the open position. By pressing the bulb (6), air from the bulb will be released to the outside atmosphere.

As shown in figures A1 , A2, A3, a standard non return valve (14), with one valve saddle (15) without spring, prevents outside air from coming back into the rubber bulb after pressing the bulb. The bulb is flat now, wants to expand and thus creates an under pressure that sucks water trough the ceramic filter into the hose in order to start the siphoning action.

Backwash action takes place by closing the tap, and pressing the bulb filled with filtered water. By this pressure the filtered water is forced to enter the hollow interior of the ceramic candle and will pass the wall of the ceramic candle from inward to outwards, thus cleaning the pores on the exterior of the candle. In this way the user has to close the tap for backwashing action and to open the tap to start siphoning action.

The other function of the tap is to stop the water flow when the receptacle has been filled with filtered water. Figure A1 and A2 show the position of the valve in open/closed position. As shown in figures B1 , B2, B3, an improved valve (16) has been developed. The improved valve has been designed in such a way that it is not needed to close the tap for backwashing, resulting in a more users' friendly way of operation. The tap can always stay in the open position, both for backwashing and for starting siphoning action. The only remaining function of the tap is to close the water flow.

This improvement is based on the fact that the (released) air has a low viscosity while water has a relative high viscosity.

The improved valve consists of two identical valve saddles (17 and 18) and one round rubber valve disk (19).

Inside the inlet/outlet opening of the lower valve saddle a weak spring is mounted elevated a few mm. above the level of the lower saddle valve. The weak spring can be porous polyurethane foam, a plastic flexible piece or a metal spring. A preferred solution is to use a piece of open cell polyurethane foam (20) functioning as a weak spring. Foam needs just a little bit of force to be compressed a few mm. acting as a weak spring like action.

In the normal position as can be seen in figure B1 , the rubber valve disk rests on top of the foam spring. When the rubber bulb is filled with air, pressing the bulb for air release does not result to the closure of the valve in the lower position, due to the small force from the released air acting on top of the rubber valve disk resting on the foam spring because air has a low viscosity. The force to the surface of the lifted rubber valve disk is not enough to overcome the spring tension, preventing the closure of the rubber valve at the lower valve saddle position.

After pressing the rubber bulb (air has released now) the rubber valve goes into the upper position and closes the upper saddle valve as can be seen in figure B3. The suction force of the bulb will now start the siphoning effect.

In case water from the filter slowly passes the improved valve at a rate by gravity, as for example 6 liters per hour, the force to the surface of the lifted rubber valve disk is not enough to overcome the foam spring tension. The valve stays open too (figure B1). When the water flow will be reduced by the clogging of the ceramic filter surface, back washing action should take place. By pressing the bulb filled with filtered water, this pressured water delivers enough pressure to the surface of the rubber valve disk to compress the weak foam spring effect and will result in the closure of the valve (see figure B2). In practice the valve closes immediately, directing the pressured water towards the ceramic filter for back washing

As shown in figures C1 , C2, C3, an insert (21) in the form of a small diameter rod shaped element to be mounted into the outlet opening of a non return valve with two identical valve saddles (17 and 18), will be combined with an adjustable foam made floating element (22) mounted around the hose that can be pushed upwards or downwards into any desired position.

The insert element cannot leave the valve by mounting a small knob functioning as a stopper (23). At the end of the insert element another small knob will be mounted as a stopper (24) in such a way that when the needle shaped insert element is pressed inwards when the valve touches the bottom (25) of the receptacle for storage of filtered water, because of this the rubber valve disk will be lifted a few mm. The rubber valve disk that has been lifted now will be positioned halfway between the two valve saddles and the valve is in an open position, see figure C1. Pressing the rubber bulb for starting siphoning action will enable air to leave the valve and to start siphoning action. Starting the siphoning action, the valve is in position as seen in figure C2.

To start the back washing action, the hose with connected valve has to be lifted a little bit. By gravity, the insert will fall down a few mm. and the valve will close the lower valve saddle to enable backwashing as seen in figure C3.

When the receptacle will become filled with purified water, the adjustable floating element (22) slowly will be covered by water and the hose with connected valve will start to float. The insert element slowly will move to the lowest position, resulting into the move of the rubber valve disk towards the lower valve saddle and closure of the valve (figure C3).

By hand the floating element can be positioned to the level where the receptacle will be full. This automatic shut off solution can be used when for example large 2 liter PET bottles will be used for collecting and storing purified water.

The adjustable floating device mounted around the flexible hose can be pushed in such a position that it will result to the floating of the hose with connected valve when the level of filtered water reaches the position of the floating element, said combination results in three functions without the need of an opening and closing valve, said functions are the starting the siphoning action, starting the backwash action and starting to stop the flow of filtered water when the receptacle has been filled till the level of the floating element.

It is important to find solutions to enable people only to filter the required amount of water. This will prevent waste of filtered water that will flow over the edge of the receptacle used for filtered water, in case the volume of the receptacle is smaller than the volume of the container filled with contaminated water. The special valve as described under C) can be used for this purpose.

When the filter housing partially hangs in the water of the upper container, the water flow stops when the water level has reached the bottom of the filter housing. It has been identified that the siphoning action will start again by itself without pressing the bulb when the housing with the wet pre-filter around the ceramic candle will be placed in position a little bit lower and will again partially covered with water. The fleece pre-filter filter that is still wet causes this. The fleece filter above the water level will suck water from the lower part that is covered by water caused by the hygroscopic effect, resulting that the siphoning action starts again without any usage of the rubber bulb.

This effect can be used to design a marking system that will roughly deliver the required amount of filtered water and will stop after that amount has been delivered.

A type of clamp will be used to secure the hose in a desired position to the edge of the container filled with contaminated water. When the hose is secured in a certain position, the hose connected filter housing will be placed in a certain position too. Using visual or other markings on the exterior of the filter housing users can lower the container in the water till the visual marking they choose and only the required amount of water will be filtered.

The hose can be pulled and fixed into any desired position

As the innovative water filter often will be used at the countryside, many times water to be purified is quite turbid.

In order to prevent frequent backwashing, ways have been sought to apply a pre-filter that will remove a substantial part of colloidal clay particles and other small particles present in the water resulting in a lower clogging frequency of the ceramic candle.

Many materials have been investigated and at the moment it seems that a tightly woven fleece fabric gives the best performance regarding filtration effect and costs effectiveness. Using a fleece filter tightly placed around inlet holes made in the plastic jar. A preferred solution turned out to use a fleece filter (26) covering the complete surface of the ceramic filter.

The fleece filter substantially prevents premature clogging of the ceramic filter. Backwashing the ceramic filter even partially removes collected dirt in the fleece filter, using the same back washing force from the rubber bulb filled with filtered water. Tightly securing the fleece filter to the plastic cap of the ceramic filter is important for this. From time to time the fleece filter has to be removed to be cleaned, by rinsing the filter by hand in clear water. After cleaning the fleece material, the pre-filter has to be put back in position.

In case very turbid water with lots of clay particles will be used, even this pre-filter will let pass too much clay particles, resulting in very fast clogging of the ceramic filter. Frequent back washing will help a bit, but altogether the surface of the ceramic filter has to be cleaned often by removing a small layer of the ceramic surface. In this situation, using the filter is not user's friendly and requires frequent changing of a replacement filter resulting in higher costs for the consumer.

To solve this problem a small amount of coagulation material first has to be added to the muddy water. After stirring by hand during a few minutes, the clay particles start to stick together and will form larger seized flocks. After a waiting time of at least a few minutes most clay particles have stuck together into flocks. The size of the flocks is such, that contrary to clay particles, most flocks cannot pass the pores of the fleece pre-filter. In this way clogging of the ceramic filter surface will be prevented and the innovative water filter, in combination with a coagulant/flocculent, can be used to purify muddy water having a very high turbidity.

In this situation a preferred position is to have the filter floating in the water, by adding a floating body to the plastic jar. After about 10 minutes, most flocks are in the lower position of the bucket, while the top layer of the water is relatively clear. The combination of fleece pre-filter and ceramic filter now will filter relative clear water having a limited amount of flocks. During the filtration process the floating filter slowly goes down, when the water in the container filled with contaminated water slowly will be emptied by the filtration process.

Fig G shows, another option is to mount the ceramic filter inside a closed jar (27) outside the container filled with contaminated water. A special designed pre-filter (28) can be placed inside the container, connected to the closed jar with a flexible hose. The ceramic filter, mounted inside the closed plastic jar with a watertight screw lid, is mounted to the screw lid with a rubber washer and wing nut.

The outlet opening of the ceramic filter is connected with the attached rubber bulb and one of the valve/tap options as described above.

A special pre-filter has been designed that is flexible and flat, see figure D. This pre-filter consists of two layers of filtration material (29). Inside the top layer of the filtration material, using a special connector (30), a flexible hose is mounted. Between the two layers of filtration material a permeable flexible separation layer (31) is mounted to enable the filtered water to flow between the two filtration layers into the direction of the hose outlet connection.

The form of the pre filter can be such that it will fit into the opening of a jerry can. In state of the fleece pre-filter, different layers of filtration material, a fine foam of sponge material can be used that can be cleaned by washing the material by squeezing it in clear water.

ADVANTAGES OF THE INVENTION Compared to existing traditional two container ceramic filters, this innovative water filter:

1. Has a smaller volume (about 1.5 liters, versus about 20 liters) and lower weight (about 300 grams, versus 3 kilo or more).

2. Delivers about 5 liters of water per hour, compared to 0.5 liters per hour for a traditional system having one ceramic candle filter.

3. Substantially reduces the amount of times that because of fouling the surface of the ceramic candle has to be cleaned. This is realized by using a combination of an innovative back wash system and a removable and washable pre-filter covering the surface of the ceramic filter. 4. Is cheaper than traditional two container systems due to the fact that the users already have containers at home for storage of contaminated water and to collect purified water (buckets or pots). Purchasing of special containers is not needed.

Claims

We claim

1. A water purification system operating on a siphoning action comprising a ceramic filter (2) mounted in a filter housing; said filter and housing is placed in a container filled with contaminated water, said ceramic filter is covered by a removable and washable pre-filter (26) to prevent premature clogging of the ceramic filter; said housing having a water inlet opening (10) above the bottom of the filter housing, said filter housing having a lid (11) with an outlet opening (12) for air release and an opening for mounting the ceramic filter with a wing nut (13); a rubber bulb (6) is connected on one side to the outlet opening of the filter by a flexible hose and on the other side to a non return valve with an attached tap (8), wherein said bulb in combination with the non return valve tap is used to start the siphoning filtration process and for cleaning the ceramic filter by backwash action.

2. The water purification system as claimed in claim 1, wherein the said nonreturn valve (14) is provided with a valve saddle (15) and rubber valve disk for preventing outside air from coming back in to the rubber bulb after pressing the bulb.

3. The water purification system as claimed in claim 1 and 2, wherein the said non return valve (16) comprises of two identical valve saddles (17, 18) and a rubber valve disk (19); said non return valve is having a spring (20) which is mounted above the said lower saddle valve, whereby the said non return valve allows the said tap to stay in open position, both for back wash action and for starting the siphoning action.

4. The water purification system as claimed in claim 3, wherein the said spring can be porous polyurethane foam, a flexible plastic piece or a metal spring.

5. The water purification system as claimed in claim 1 , wherein the said non return valve comprises of an insert (21) which is mounted in to the outlet opening of the said non return valve with two identical valve saddles (17,18) and a floating element (22) mounted around the said hose can be pushed upwards or down wards in to the desired position; said insert (21) is provided with two stoppers (23, 24) on either side for securing inside the outlet opening of said valve and for lifting the rubber valve disk, wherein the said valve in combination with the insert, valve saddles, floating element .rubber disk are used for starting the siphoning action, starting the back wash action and starting to stop the flow of filtered water when the receptacle has been filled till the level of the floating element, without opening and closing the said valve.

6. The water purification system as claimed in claim 1, wherein the said fleece filter (26) can suck water with the hygroscopic effect when it is partially covered by water and can able to start siphoning action without using rubber bulb thereby the hose connected with the filter housing can be secured in to any desired position in order to filter only an amount of water required by the user.

7. The water purification system as claimed in the preceding claims wherein the said removable and washable pre-filter can be made from two or more layers of filtration material preferably fleece fabric or fine foam or sponge, having a flexible porous separation material between those layers.

8. The water purification system as claimed in the preceding claims, wherein the combination of the ceramic candle pre-filter with the coagulant/flocculent agent can be used to purify the contaminated water having high turbidity.

9. A water purification system, wherein the ceramic filter mounted inside a closed filter housing located outside the container filled with contaminated water, said inlet of the filter housing is connected by a flexible hose to a flexible double layer prefilter (29) which is positioned in to the container filled with contaminated water, said double layer prefilter (29) comprises of plurality of layers of filtration material having permeable separation layer (31) to allow easy passage of filtered water to the outlet hose, said outlet hose is connected to the connecter (30) mounted in one layer of the filter, said filter housing has an outlet connected to a rubber bulb and non return valve combination as claimed in the preceding claims.

10. A water purification system substantially as herein described and illustrated in the figures of accompanying drawings.