WO2004045742A1

WO2004045742A1 - Water filter and a method of water purification, backwashing and rinsing

Info

Publication number: WO2004045742A1
Application number: PCT/SG2003/000272
Authority: WO
Inventors: Chee Woh Chaw; Ah Chong Chaw; Chee Kien Chaw; Yoke Ling Chaw; Yoke Peng Chaw
Original assignee: C.A.C. Engineering Construction Sdn Bhd
Priority date: 2002-11-19
Filing date: 2003-11-19
Publication date: 2004-06-03
Also published as: AU2003276817A1; CN1826161A

Abstract

The present invention discloses a water filter, used in the purification of mains water supply which comprises a vertically placed filter vessel (4) with a filter media (13), a system of valves (A to G), an inlet (61), an outlet (31), a backwashing port (51) and an effluent outlet (121). A fenestrated sheet (11) is disposed at the common adjoining end between a bottom compartment and the filter vessel (4); and the filter media (13) is placed inside the filter vessel (4) above the fenestrated sheet (11), leaving the top portion of the filter vessel (4) unfilled. The bottom compartment is provided with a base opening (8) which leads to a bottom sedimentation chamber (9) or alternatively is elongated and functions as a sedimentation chamber (9) on its own right. The system of valves (A to G) is selectively manipulated to invoke a water purification operation, or a backwashing operation, or a rinse operation, or a bypass operation. During water purification operation mode, mains water moves upwardly in an anti-gravity direction through the filter vessel (4), where the filtered water can be inspected visually through two transparent viewing ports (2) installed opposite each other towards the top portion of the filter vessel (4). A backwash operation mode is performed in the reverse direction, through a backwash pipe (5) embedded within the distance of the filter media (13), substantially at the middle of the filter media (13). The backwash pipe (5) allows the removal of coarse contaminants using mains water whereas finer contaminants are removed by the filtered water at the top of the filter vessel (4). A rinse operation mode is also taught.

Description

WATER FILTER AND A METHOD OF WATER PURIFICATION, BACKWASHING AND RINSING

TECHNICAL FIELD

The present invention relates generally to water filters used in the purification of mains water supply. The invention relates particularly to an improved design of water filters, and a method of water purification, backwashing and rinsing.

BACKGROUND OF THE INVENTION

Rapid sand filter, in which water passes through a bed of sand under gravity or pressure, is commonly used for the treatment of urban supplies. When the sand filter becomes clogged, it is cleaned by backwashing, often assisted by mains water. Clogging can be reduced by using two or more layers of filter media, such as anthracite and sand, so that the water first passes through coarse material which retains larger solids. On backwashing, the lighter filter media, with larger pore sizes, stays on top.

Up-flow filters enable small particles to pass through the lower, larger-sized grains of media and to be retained on the higher, smaller grains of the media. The stratification of the media is preserved during backwashing.

I

As seen in Figures la- lb and lc, a prior art water filter system comprises a multi-port valve with a first inlet from the mains, a second inlet and an outlet, and a cylindrical vessel containing a filter media. Mains water supply enters the first inlet disposed at the upper part of a closed vertically placed filter vessel and flows through a filter media downwardly by gravity. The filter media includes various compositions of activated carbon, anthracite, fine sand and manganese gree sand singly o in combination. Filtered water accumulates at the bottom of the filter vessel and is appropriately channeled via a channel through the outlet to the consumers. The cliannel takes the form of a central tubing which is connected to a pumping means. Over time, the filter media becomes dirty with contaminants from the mains water. Rejuvenation of the filter media is performed with a backwash procedure whereby the mains water, through the second inlet, is used to flush the fitter media in the opposite direction. The water purification and backwashing operations are facilitated by a system of valves. A backwash operation and a fast rinse operation are allowed.

One of the problems with the prior art design of water filters is that the contaminants will remain substantially towards the top portion of the filter media. Gravity will eventually cause the contaminants to settle down and permeate towards the bottom portion of the filter media. This will make the backwash operation difficult and inefficient. Furthermore, mains water (with contaminants) is used to cleanse the system. Further contaminants still remain in the filter media even at the end of the backwash operation.

During the backwash operation, both the filter media and the contaminants will be agitated by the reverse flow of water. Light material of the filter media, such as activated carbon, eventually exits the vessel together with the effluent, resulting in a less efficient water filter during subsequent usage.

Another disadvantage is the enclosed nature of the filter vessel The consumer is not able to visually inspect the clarity of the filtered water, unless the water is collected in a separate transparent container. This leaves the consumer with the chore of having to flush the system on a very regular basis as suggested by the manufacturer without direct reference to the quality of the mains water supply. The quality of mains water supply often varies from time to time, and from place to place.

OBJECT OF THE INVENTION It is a primary object of the present invention to overcome the stated drawbacks of the prior art water filters, so as to improve the efficiency of water filters.

It is another object of the invention to facilitate maintenance of water filters.

Other objects, features and advantages of the present invention will become apparent ftora the detailed description which follows, or may be learned by practice of the invention. SUMMARY OF THE J- ^ENTI N

According to the present invention, the bottom end of a vertically placed cylindrical filter vessel is integrally fitted with a funnel its narrow apex end pointing downwards. The common adjoining end between the funnel and the filter vessel is a fenestrated sheet. A filter media is placed inside the filter vessel above the fenestrated sheet. The top portion of the filter vessel is not filled. The apex end with an apex opening leads to a bottom sedimentation chamber which supports the funnel and the filter vessel An effluent outlet is provided at the bottom sedimentation chamber. An inlet is provided at the side of the funnel, allowing water to flow upward against gravity. An outlet is provided near the top of the filter vessel A cruciate-shaped backwash pipe, with multiple openings on its underside, is embedded within the substance of the filter media, substantially at the middle of the filter media. The backwash pipe is connected to an external system of valves through a backwash port. Two transparent viewing ports are provided opposite each other towards the top portion of the filter vessel A system of valves creates fluid communication with the inlet, the outlet, the backwash port and the effluent port.

A method of water purification, backwashing and rinsing is also taught by the present invention. The method teaches various steps, including the step of providing valve G on an effluent pipe connected to the bottom sedimentation chamber; the step of providing valve A on an inlet pipe connected to the side of the funnel; the step of providing valve B on the external portion of a backwash pipe connected to the side of the filter vessel; the step of providing valve E on an outlet pipe connected to the top portion of the filter vessel; the step of providing a connecting pipe to link the inlet pipe, the backwash pipe, and the outlet pipe; the step of providing valve C on the portion of the connecting pipe between the backwash pipe and the outlet pipe; the step of connecting the bottom end of the connecting pipe to the mains water supply; the step of connecting the top end of the connecting pipe to a distribution pipe to consumers and to a rinsing pipe; the step of providing valve F on the distribution pipe; and the step of providing valve D on the rinsing pipe, whereby a water purification operation mode, or a backwashing operation mode, or a rinse operation mode is invoked by selectively manipulating the valves, BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the present invention serves to explain the principles of the inventioa It is to be understood that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention. Reference will be made to the accompanying drawings, in which:

Figure 1 a illustrates a prior art water filter during water purification operation mode.

Figure lb illustrates the prior art water filter shown in Figure la during backwash operation mode.

Figure lc illustrates the prior art water filter shown in Figure la during quick rinse operation mode. ,

Figure 2 illustrates one embodiment of the present invention with its system of valves.

Figure 3 illustrates the underside view of a cruciate-shaped backwash pipe as shown in Figu e 2.

DETAILED DESCRIPTION In detail now and referring to Figure 2, the bottom end of a vertically placed cylindrical filter vessel (4) is integrally fitted with a funnel (7), its narrow apex end pointing downwards. The common adjoining end between the funnel (7) and the filter vessel (4) is a fenestrated sheet (U). A filter media (13) is placed inside the filter vessel (4) above the fenestrated sheet. The top portion of the filter vessel (4) is not filled. The apex end with an apex opening (8) leads to a bottom sedimentation chamber (9) which supports the funnel (7) and the filter vessel (4). The funnel arid the sedimentation chamber are significant in the invention, because contaminants are allowed to settle down. An effluent outlet (121) is provided at the bottom sedimentation chamber (9).

It is important to note that the funnel may be substituted by a bottom compartment with a base opening. The fenestrated sheet (1 1) divides the filter vessel (4) into an upper portion and a bottom compartment. The bottom compartment is provided with a base opening (8) which leads to a bottom sedimentation chamber (9) or alternatively is elongated and f nctions as a sedimentation chamber on its own right. The filter media (13) is placed inside the upper portion above the fenestrated sheet (11), leaving a top portion of the filter vessel (4) unfilled

An inlet (61) is provided at the side of the funnel (7), allowing water to flow upward against gravity. An outlet (31) is provided near the top of the filter vessel (4). A cruciate- shaped backwash pipe (5), with multiple openings on its underside, is embedded within the substance of the filter media (13), substantially at the middle of the filter media (13). The backwash pipe (5) is connected to an external system of valves through a backwash port (51). Two transparent viewing ports (2) are provided opposite each other towards the top portion of the filter vessel (4). The turbidity of filtered water inside the filter vessel (4) can be quickly ascertained.

A system of valves creates fluid communication with the inlet (61), the outlet (31), the backwash port (51) and the effluent outlet (121). Valve G is disposed on an effluent pipe (12) connected to the effluent outlet (121). Valve A is disposed on an inlet pipe (6) connected to the inlet (61). Valve B is disposed on the external portion of the backwash pipe (5). Valve E is disposed on an outlet pipe (3) connected to the outlet (31). A connecting pipe (10) connects the inlet pipe (6), the backwash pipe (5), and the outlet pipe (3), Valve C is disposed on the portion of the connecting pipe (10) between the backwash pipe (5) and the outlet pipe (3). The bottom end of the connecting pipe (10) is connected to the mains water supply (15). The top end of the connecting pipe (10) is connected to a distribution pipe (16) to consumers and a rinsing pipe (1 ). Valve F is disposed on the distribution pipe (1 ). Valve D is disposed on the rinsing pipe (17).

During water purification operation mode, the mains water supply (15) enters the funnel (7) through valve A and the inlet pipe (6). Water moves upwardly through the fenestrated sheet (1 1), made of a solid material, such as stainless steel, and then through the filter media (13). The filtered water is then channeled through the outlet pipe (3), and valve E, and then through the distribution pipe (16) and valve F to be supplied to a consumer. At the top of the filtered water level in the filter vessel (4) is a column of compressed air that resides underneath a top service port (1).

As the water moves upwardly in an anti-gravity direction, most contaminants will be trapped at the lower portion of the filter media (13). When the water movement is slow, such as durbg periods of low water usage at night, sedimentation will occur, whereby the heavier contaminants will settle to the bottom of the funnel (7), through the apex opening (8) into the sedimentation chamber (9). Water movement in the sedimentation chamber (9) is very minimal, even during periods of high water flow in the funnel (7). Hence, the contaminants will generally remain in the sedimentation chamber (9), until it is discharged through the effluent pipe (12) during backwashing.

To clean the filter media (13), a backwashing operation is performed. First, all the valves (A, C to G) are closed except for valve B, which allows the water pressure within the filter vessel (4) to build up. Valve G is then opened and closed repeatedly, resulting in a rapid agitation or fluctuation of the hydrostatic pressure inside the filter vessel (4). This leads to the successive expansion and contraction of the volume of compressed air in the top service port (1) as predicted by the Boyle's Law, In the filter media (13) below the level of the backwash pipe (5), water movement will be jerky. There will be net movement of water in the direction of the gravity. This will dislodge the contaminants at the lower portion of the filter media (13) into the funnel (7) and the sedimentation chamber (9), before being discharged through the effluent pipe (12).

As to the filter media (13) above the level of the backwash pipe (5), water movement during the above operation will be jerky but there will not be much overall water flow. This action will dislodge the finer contaminants from the filter media (1 ) in a way like the manual scrubbing of dirty laundry. When the discharge from the effluent pipe (12) is visually clear, valve B is closed while valves G, E and D are opened. The effect of gravity will cause the previously filtered clean water in the upper portion of the filter vessel (4) to flow through the filter media (13) and expel the remaining contaminants through the effluent pipe (12). This is aided by the equalization of pressure within the filter vessel (4) with that of the surrounding atmosphere, as ambient air enters the filter vessel (4) via valves D and E, Once the flow of effluent has stopped, all valves are closed except valves A, E and F, in order to resume the purification of the mains water. There is little or no need to rinse the system, since clean filtered water will reach the consumer.

Due to variations in the quality of mains water supply at different geographical locations and at different time (e.g. more turbid water after resumption of water supply following water works), the load of contaminants in the mains water differs, hence the frequency of backwashing also differs. With the two viewing ports (2) installed in alignment, the consumer is able to visually check the clarity and turbidity of the filtered water to determine the need for backwashing. This avoids unnecessary backwashing and hence reduces maintenance and water wastage.

The system of valves also allows a rinse operation. In rinse operation mode, valves A, D and E are opened and valves B, C, F and G are closed. Mains water moves upwardly through the filter vessel (4) and exit through the outlet pipe (3) to the rinsing pipe (17).

I Furthermore, the system of valves allows a bypass operation. Valves C and F are opened while all other valves are closed. Mains water moves upwardly through the connecting pipe without passing through the vessel

As required in all water filters, the filter media (13) has to be replaced after a certain lifespan. This can be accomplished easily in the present invention by the provision of a top service port (1) and a side service port (14). The top service port (I) with cover is disposed at the top end of the filter vessel (4). The side service port (14) with cover is provided at the side of the filter vessel (4) slightly above the fenestrated sheet (1 ), The two service ports (1, 14) allow the filter media (13) to be discharged, if need arises.

While only one embodiment of the present invention has been described and illustrated, it is to be understood that many changes, modifications and variations could be made to water filter and the method of water purification, backwashing and rinsing, without departing from the scope of the invention.

Claims

CLAIM

1 - An upfiow water fitter comprising: a) a vessel containing a filter bed; b) an inlet for contaminated liquid; c) an outlet for filtrate; d) at least another inlet located within or above the filter bed for introducing washing liquid to wash the bed; e) drainage means for effluent from washing the filter bed; f) valves disposed at the inlet, the outlet, the inlet(s) for introducing washing liquid and the drainage mean's.

wherein the liquid flows upward against gravity during filtration, the cleaning fluid flows generally downward within the bed during washing and the selection of filtering and washing mode can be effected by manipulating the said valves.

2. An upfiow water filter according to claim 1 wherein the interior of the vessel is divided into two compartments by a fenestrated plate which supports the filter bed in a manner only to allow the passage of fluid within the vessel.

3. An upfiow water filter according to claim 2 wherein the Inlet opens to the bottom compartment, so as to allow sedimentation.

4. An upfiow water filter according to claim 2 or 3 wherein the bottom compartment is made up of a frusto-conical funnel that is attached and opens to a cylinder.

5. An upfiow water filter according to any of the preceding claims wherein the filter bed is arranged in a manner such that an air space is created above the filter bed and the outlet during the operation of the filter.

6. An upfiow water filter according to any of the preceding claims wherein the inlet for introducing washing liquid consists of at least a pipe with multiple openings in its wall.

7. An upfiow water filter according to any of the preceding claims wherein there is an additional bypass pipe connected to the inlet and the outlet of the filter.

8. A filter cartridge comprising: a) a close vessel; b) a filter bed contained within the vessel; c) a perforated plate, which is attached to the interior of the enclosed vessel, to support the filter bed; d) a compartment (within the vessel) beneath the perforated plate to allow sedimentation; e) an air space above the filter bed; f) at least an inlet for contaminated liquid at the sedimentation chamber; g) at least an outlet for filtrate located above the fitter bed; h) at least an outlet for effluent during washing near or at the bottom of the sedimentation chamber; i) and at least an inlet for cleaning flufd, which is located within or above the filter bed. wherein the various inlets and outlets are to be connected to pipes with valves.

9. A method of washing the filter bed as claimed in claim 1 comprises: a) stopping any flow in the inlet and the outlet; b) allowing cleaning fluid to flow continuously into the filter, c) turning on and stopping the flow repeatedly in the drainage means to agitate the cleaning fluid in the filter bed while draining only part of the cleaning fluid; d) stopping any flow of cleaning fluid, opening up the Inlet to allow entry of air and turning on the flow in the drainage means to drain remaining liquid in the filter when effluent in the drainage means turns clear.