Title of Invention	A CARTRIDGE FOR FILTRATION OF WATER
Abstract	The present invention relates to a filter cartridge for filtration of water and to a cost-effective filter cartridge for gravity filtration of water substantially free of particulate contaminants including microorganisms like cysts while consistenly providing for relatively high flow rates of output water. It is an object of the present invention to provide a cost-effective filter cartridge, which ensures desired particulate removal including microorganisms like cysts while giving the desired high flow rate more consistently over a larger volume of inlet water, as compared to the prior art cartridges. Accordingly, the present invention provides a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means wherein said filter cartridge comprises a collection chamber positioned below the carbon block in the receptacle for holding the water that exits the carbon blocks, said collection chamber comprising a dome shaped holder plate provided with at least one water discharge port said plate positioned in close proximity to the carbon block, and an outlet nozzle for water having an inlet and outlet end, said inlet end positioned in close proximity to the under side of said plate such that all the water passing through the carbon block collects in the space between the top of the plate and the carbon block before exiting through the discharge port to fill the collection chamber and exit through the nozzle.

Title of Invention

A CARTRIDGE FOR FILTRATION OF WATER

Abstract

The present invention relates to a filter cartridge for filtration of water and to a cost-effective filter cartridge for gravity filtration of water substantially free of particulate contaminants including microorganisms like cysts while consistenly providing for relatively high flow rates of output water. It is an object of the present invention to provide a cost-effective filter cartridge, which ensures desired particulate removal including microorganisms like cysts while giving the desired high flow rate more consistently over a larger volume of inlet water, as compared to the prior art cartridges. Accordingly, the present invention provides a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means wherein said filter cartridge comprises a collection chamber positioned below the carbon block in the receptacle for holding the water that exits the carbon blocks, said collection chamber comprising a dome shaped holder plate provided with at least one water discharge port said plate positioned in close proximity to the carbon block, and an outlet nozzle for water having an inlet and outlet end, said inlet end positioned in close proximity to the under side of said plate such that all the water passing through the carbon block collects in the space between the top of the plate and the carbon block before exiting through the discharge port to fill the collection chamber and exit through the nozzle.

Full Text	COMPLETE AFTER PROVISIONAL LEFT ON 7 NOV 2006 C2140 FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENT RULES, 2003 COMPLETE SPECIFICATION (See Section 10 and Rule 13) A CARTRIDGE FOR FILTRATION OF WATER HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India The following specification particularly describes the nature of the invention and the manner in which it is to be performed. FIELD OF INVENTION The present invention relates to a filter cartridge for filtration of water, more particularly to a cost-effective filter cartridge for gravity filtration of water, substantially free of particulate contaminants including microorganisms like cysts while consistently providing for relatively high flow rate of output water. The invention has been developed primarily for use in water purification and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. BACKGROUND AND PRIOR ART Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field. Common contaminants present in water include particulate matter, chemicals and microorganisms. In the case of potable water, it is desirable to remove these harmful contaminants to maintain good health. Various methods are known for purification of water and based on which many devices and apparatus are designed and are also commercially available. These 2 methods and devices are varied in accordance with the type of impurities present in water. Particulate contaminants, which are generally larger than 3 microns are filtered using a cloth filter or a depth filter e.g. a bed of activated carbon or clay which is present in free granular form or which has been moulded into a block by using a binder. Carbon and clay are highly porous materials, which also facilitates the removal of soluble impurities e.g. dissolved organic compounds by adsorption apart from compounds that lend an offensive odour and taste such as pesticide and pesticide residues. Water available in many remote areas and the areas having scarcity of water is generally highly contaminated with soil which and often contains traces of oxides and hydroxides of Iron and Aluminium. It is commonly observed that filter cartridges having carbon blocks get choked after having been used for some time, especially in gravity water filters. Upon choking, the filters provide very low flow rates of water, which is undesirable to the user. Upon such choking, the consumer often tries to rejuvenate the cartridge by agitating in water or backflushing. The presently available filter cartridges are relatively difficult to rejuvenate so as to provide the original flow rate and filtration efficacy. Thus the consumer is required to replace the filter cartridge with a new filter cartridge which turns out to be a costly affair. The present inventors in the copending application 801/MUM/2005 (or its equivalent EP 05077094.0) have sought to solve this problem by providing a filter cartridge which provides 3 consistently high flow rates of water of desired quality, while providing for ease of cleaning and replacement of the carbon blocks, while ensuring that the overall cost of the cartridge is relatively minimized. The co-pending application provides for a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle having an orifice for outlet of water wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means such that all inlet water passes through said carbon block before exiting said filter cartridge. While the invention of the co-pending application provides for a cost-effective filter cartridge for filtration of water while giving high flow rates and good filtration efficacy, it was observed that the flow rate of output water was not as consistent as desired. This problem was observed to be more acute when the filter was kept idle for some period of time. The present inventors have developed a novel solution to the problem, which ensures that the filter cartridge is modified to provide for consistent and relatively high flow rates. OBJECTS OF THE INVENTION It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. 4 Another object of the present invention to provide for a cost-effective filter cartridge which ensures the removal of particulate matter including microorganisms, like cysts, while providing for relatively high flow rate of water over a larger volume of inlet water, as compared to the prior art cartridges. SUMMARY OF THE INVENTION According to the present invention there is provided a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means wherein said filter cartridge comprises a collection chamber positioned below the carbon block in the receptacle for holding the water that exits the carbon block, said collection chamber comprising: (a) a dome shaped holder plate provided with at least one water discharge port, said plate positioned in close proximity to the carbon block, (b) an outlet nozzle for water having an inlet and outlet end, said inlet end positioned in close proximity to the under side of said plate such that all the water passing through the carbon block collects in the space between the top of the plate and the carbon block before exiting through the discharge port to fill the collection chamber and exit through the nozzle. Preferably, the carbon block is a carbon disc. 5 DETAILED DESCRIPTION OF THE INVENTION The present inventors observed that especially when the carbon block of the copending application 801/MUM/2005 was idle for periods of time, the out put flow rate of the water exiting the filter cartridge was inconsistent. Without wishing to be bound by theory, the inconsistent flow rate is attributed to the problem of 'air-lock'. Air-lock is a severe problem which is observed in many low-pressure (including gravity fed) filtration apparatus, especially in those devices that operate in the down flow mode. When such filters are kept idle for periods of time, air enters into the cavities of the water flow path. Subsequently when the filter cartridge is used again to filter water, the air being lighter than water gets trapped in the form of bubbles in the cavities of the filter especially close to the underside of the filtration media, (the carbon block, in the present invention) and causes a back pressure and consequent loss of filtration surface area, both of which contribute to the reduction in the flow rate of water. The present inventors have developed a filtration cartridge which is believed to substantially minimize this problem thereby leading to consistently high filtration rates. It is believed that the constructional features provided for in this invention viz. the dome shaped holder plate (HP) positioned close to the carbon block, the water discharge port (DP) on said plate, and the outlet nozzle (ON) for water having an inlet end positioned in close proximity to the under side of said plate, all work effectively in tandem to ensure that the filter cartridge of the invention provides the 6 desired high flow rates, consistently over time. Further, it is believed that when air is entrapped downstream of the carbon block, the constructional features of the invention ensures effective coalescence of the bubbles into a single air bubble which is directed towards a small volume, close to the inlet end of the outlet nozzle. Additionally the filtered water first collects on said plate, free of dispersed air bubbles and the pressure exerted by the collected water ensures that the single air bubble is first pushed out through the exit nozzle, thereby ridding the filter cartridge of the "air-lock" problem, thus providing an elegent and effective solution to this problem. A highly preferred carbon block of the invention is a carbon disc. The disc may have a circular, oval, square or polygonal cross-section, preferably a circular cross-section. When a carbon disk is used, it is preferred that the dimensions are such that the ratio of the longest dimension to the thickness is in the range of 2:1 to 20:1, more preferably 3:1 to 15:1. The collection chamber in the receptacle of the filter cartridge comprises a dome shaped holder plate which is in close proximity to the underside of the carbon block. The holder plate preferably has corrugations with troughs and peaks. The troughs form grooves on the upper side of the holder plate. The grooves are preferably spirally oriented. The holder plate has at least one water discharge port, preferably 2 and more preferably 4 or more. The collection chamber also comprises an outlet nozzle for water, which has an inlet end and an out let end. 7 The inlet end of the outlet nozzle is in close proximity to the underside of the holder plate, preferably positioned approximately equidistant from the periphery of the dome shaped holder plate. The fastening means may be a closure which may be snap fit on to the receptacle, or a clamp which holds the carbon block on to the receptacle. The gasket means may be a gasket, an O-ring or any other means which serves the purpose of a gasket, which provides leak tightness to water when a fastening means is used to fasten two articles together. It is preferred that the fastening means is a screw-threaded closure, which comprises an orifice for inlet of water and it is screwable on to the receptacle housing the carbon block. The receptacle is provided with corresponding screw threads for urging the carbon block against the gasket means provided in the base of the receptacle thereby attaching the carbon block in the filter cartridge. The closure may be provided on its bottom surface with downwardly projecting members which are urged against the top surface of the carbon block, as the closure is screwed on to the receptacle thereby urging the bottom surface of the carbon block against the gasket means placed in the base of the receptacle thereby ensuring the necessary leak tightness. When the carbon block is desired to be detached from the filter cartridge, the closure is unscrewed from the receptacle thereby releasing the carbon block. One or more orifices are provided on the closure for inlet of water on to the carbon block. It is preferred that the 8 orifice comprises at least 30% of the surface area of the top surface of the closure. The invention is especially suitable and configured to be capable of filtering water which is contaminated with particulate contaminants, including dust and microorganisms e.g. protozoan cyst like Cryptosporidium and Giardia. The invention is capable of 99% removal (two log removal) preferably 99.9% removal (three log removal) of cyst. Log removal is defined as the log10 of the number of input particles minus the log™ of the number of output particles. The carbon blocks are made from activated carbon, more preferably powder activated carbon. It is desirable to include a replaceable sediment filter that externally envelops the carbon block such that water passes through the sediment filter before passing through the carbon block. The sediment filter preferably corresponds to the shape of the carbon block. The sediment filter may be washable or replaceable and is preferably a woven or non-woven fabric, more preferably a non-woven fabric having micropores. This sediment filter ensures filtration of particles generally above 3 microns. The sediment filter can be washed and rinsed under flowing tap water with mild scrubbing. The receptacle and the fastening means are preferably made of polymeric materials. Preferred polymeric materials include polypropylene, polyethylene, acrylonitrile butadiene styrene, or styrene acrylonitrile. The gasket means is 9 preferably made from natural or synthetic rubber, synthetic elastomers, teflon, nitrile rubber or silicone. The term carbon block is used to denote a block prepared using activated carbon particles bound together using polymeric binder under the action of heat and pressure. The term polymeric binder preferably has Melt Flow Rate (MFR) less than 5 g/ 10 minutes, preferably less than 2 g/ 10 minutes, more preferably less then 1 g/10 minutes. The melt-flow rate (MFR) is measured using ASTM D 1238 (ISO 1133) test. Bulk density of the binder used as per the invention is preferably less than or equal to 0.6 g/cm3, more preferably less than or equal to 0.5 g/cm3, and further more preferably less than or equal to 0.25 g/cm3. The carbon block preferably comprises powder activated carbon (PAC) having a particle such that not more than 5% medium passes through a sieve of 200 mesh and not more than 5% is retained on a sieve of 12 mesh. The PAC is preferably obtained from bituminous coal, coconut shell, wood, or petroleum tar. The surface area of the PAC is preferably selected such that it exceeds 500 m2/g, more preferably exceeds 1000 m2/g. It is preferred that the PAC has a size uniformity co-efficient of less than 2, or more preferably less than 1.5, a carbon tetrachloride number exceeding 50%, more preferably exceeding 60%. The PAC preferably has an Iodine number greater than 800, more preferably greater than 1000. 10 The proportion of the binder material to the PAC particles by weight is chosen such that it is preferably in the range of 1:1 to 1:10, more preferably in the range of 1:2 to 1:6. By way of the above filter cartridge of the invention it is possible to attain average flow rate of water, from a starting height of 200 mm down to 50 mm under gravity, of 600-50 ml/min., preferably 200-50 ml/min., without compromising on the requirements of removal of particulate including microorganisms, and chemical contaminants. According to another aspect of the present invention there is provided a method of obtaining filtered water at flow rates in the range of 50 to 600 ml/minute comprising the steps of (i) filtering water through a filter cartridge of the invention; and (ii) replacing the carbon block in the filter cartridge whenever the flow rate of water is below desired value with a block which provides the desired flow rate. The present invention facilitates easy removal of the carbon block from the cartridge to rejuvenate it, after which the carbon block is easily re-attachable in the cartridge. 11 The details of the invention, its objects and advantages are explained hereunder in greater detail in relation to the following non-limiting exemplary embodiments of the invention: BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, Fig. 1 is a schematic of a filter cartridge of the invention with a carbon disc filter assembled in a receptacle comprising a dome shaped holder plate and an outlet nozzle. Fig. 2 is a schematic of the detailed construction of a typical dome shaped holder plate with corrugations. DETAILED DESCRITION OF THE DRAWINGS Referring to Fig.1, the filter cartridge comprises a carbon disk (CB) seated on a gasket (G) provided in the base of a receptacle (R) which has a collection chamber (CC) provided with a dome shaped holder plate (HP) and an outlet nozzle (ON) for outlet of water. The outlet nozzle has an inlet end (IE) and an outlet end (OE). The dome shaped holder plate is positioned close to the underside of the carbon block. The dome shaped holder plate has two discharge ports (DP) at or close to the peripheral ends of the plate. The inlet end (IE) of the 12 outlet nozzle is positioned close to the underside of the dome shaped holder plate, preferably equidistant from the peripheral ends. The receptacle has a closure (CL) which has an orifice on the top surface (not shown) for inlet of water. The closure has screw threads (ST1) with which it is screwed on to the receptacle provided with corresponding screw threads (ST2). Downwardly projecting members (M) are provided on the closure for urging the carbon disk against the gasket as the closure is screwed on to the receptacle. The gasket ensures leak-proof outlet such that all the water fed to the filter cartridge passes though the carbon block before exiting it. Referring to Figure 2, the dome shaped holder plate has corrugation (C) on the upper side forming grooves (GR). When in use, the water enters the closure (CL) through the orifice provided thereon (not shown) and flows through the carbon disk (CB) enabling filtration and firsts collects in the space between the carbon disk and the dome shaped holder and exits into the bottom part (B) of the collection chamber through the discharge ports (DP). The water collects and fills the collection chamber. When the water is filled to the height of the inlet end (IE) of the outlet nozzle (ON), the water enters the outlet nozzle through the inlet end (IE), flows in the downward directions and exits the filter cartridge through the outlet end (OE) of the outlet nozzle. 13 It will be appreciated that the invention as embodied, provides for a filter cartridge which ensures desired particulate removal while giving the high desired flow rate of water very consistently over larger volumes of water while providing a higher efficiency in terms of the amount of water filtered for a given amount of carbon. Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. 14 We Claim: 1. A cartridge for filtration of water, said cartridge comprising: (i) a carbon block seated in a receptacle, said carbon block being detachably attachable to said receptacle by a fastening means and a gasket means; and (ii) a collection chamber positioned below said carbon block in said receptacle for holding the water that exits said carbon block, said collection chamber comprising: a dome shaped holder plate provided with at least one water discharge port, said plate positioned in close proximity to said carbon block and an outlet nozzle for water, said outlet nozzle having an inlet end and an outlet end, said inlet end positioned in close proximity to the under side of said plate, such that all the water passing through said carbon block collects in the space between the top of the plate and said carbon block before exiting through said discharge port to fill said collection chamber and exit through said outlet nozzle. 2. A filter cartridge as claimed in claim 1 wherein said carbon block is a carbon disk. 15 3. A filter cartridge as claimed in claim 1 or claim 2 wherein said plate is provided on the upper side with corrugations such that water collected in the grooves of said corrugations leads to said water discharge port. 4. A filter cartridge as claimed in claim 3 wherein said grooves are spirally oriented. 5. A filter cartridge as claimed in any one of the preceding claims wherein inlet end of said nozzle is equidistant from the periphery of the holder plate. 6. A filter cartridge as claimed in any one of the preceding claims wherein said fastening means is a screw threaded closure which comprises an orifice for inlet of water and is screwable on to said receptacle provided with corresponding screw threads for urging said carbon block against said gasket provided in the base of said receptacle. 7. A filter cartridge as claimed in any one of the preceding claims wherein said receptacle and said fastening means are made of materials selected from polymers which includes polypropylene, polyethylene, acrylonitrile butadiene styrene and styrene acrylonitrile. A filter cartridge as claimed in any one of the preceding claims wherein said gasket means is made of natural or synthetic rubber, synthetic elastomers, teflon, nitrile rubber or silicone. A filter cartridge substantially as herein described with reference to the accompanying examples and figures. A method of obtaining filtered water at flow rates in the range of 50 to 600 ml/minute comprising the steps of: (i) filtering water through a filter cartridge as claimed in any one of the preceding claims; and (ii) replacing the carbon block in the filter cartridge whenever the flow rate of water is below desired value with a block which provides the desired flow rate. Dated this 7th day of November 2006 17 ABSTRACT A CARTRIDGE FOR FILTRATION OF WATER The present invention relates to a filter cartridge for filtration of water and to a cost-effective filter cartridge for gravity filtration of water substantially free of particulate contaminants including microorganisms like cysts while consistently providing for relatively high flow rates of output water. It is an object of the present invention to provide a cost-effective filter cartridge, which ensures desired particulate removal including microorganisms like cysts while giving the desired high flow rate more consistently over a larger volume of inlet water, as compared to the prior art cartridges. Accordingly, the present invention provides a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means wherein said filter cartridge comprises a collection chamber positioned below the carbon block in the receptacle for holding the water that exits the carbon block, said collection chamber comprising a dome shaped holder plate provided with at least one water discharge port said plate positioned in close proximity to the carbon block, and an outlet nozzle for water having an inlet and outlet end, said inlet; end positioned in close proximity to the under side of said plate such that all the water passing through the carbon block collects in the space between the top of the plate and the carbon block before exiting through the discharge port to fill the collection chamber and exit through the nozzle.

Full Text

COMPLETE AFTER PROVISIONAL
LEFT ON 7 NOV 2006
C2140
FORM-2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
A CARTRIDGE FOR FILTRATION OF WATER
HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India
The following specification particularly describes the nature of the invention and
the manner in which it is to be performed.

FIELD OF INVENTION
The present invention relates to a filter cartridge for filtration of water, more particularly to a cost-effective filter cartridge for gravity filtration of water, substantially free of particulate contaminants including microorganisms like cysts while consistently providing for relatively high flow rate of output water.
The invention has been developed primarily for use in water purification and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.
BACKGROUND AND PRIOR ART
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.
Common contaminants present in water include particulate matter, chemicals and microorganisms. In the case of potable water, it is desirable to remove these harmful contaminants to maintain good health.
Various methods are known for purification of water and based on which many devices and apparatus are designed and are also commercially available. These
2

methods and devices are varied in accordance with the type of impurities present in water.
Particulate contaminants, which are generally larger than 3 microns are filtered using a cloth filter or a depth filter e.g. a bed of activated carbon or clay which is present in free granular form or which has been moulded into a block by using a binder. Carbon and clay are highly porous materials, which also facilitates the removal of soluble impurities e.g. dissolved organic compounds by adsorption apart from compounds that lend an offensive odour and taste such as pesticide and pesticide residues. Water available in many remote areas and the areas having scarcity of water is generally highly contaminated with soil which and often contains traces of oxides and hydroxides of Iron and Aluminium.
It is commonly observed that filter cartridges having carbon blocks get choked after having been used for some time, especially in gravity water filters. Upon choking, the filters provide very low flow rates of water, which is undesirable to the user. Upon such choking, the consumer often tries to rejuvenate the cartridge by agitating in water or backflushing. The presently available filter cartridges are relatively difficult to rejuvenate so as to provide the original flow rate and filtration efficacy. Thus the consumer is required to replace the filter cartridge with a new filter cartridge which turns out to be a costly affair. The present inventors in the copending application 801/MUM/2005 (or its equivalent EP 05077094.0) have sought to solve this problem by providing a filter cartridge which provides
3

consistently high flow rates of water of desired quality, while providing for ease of cleaning and replacement of the carbon blocks, while ensuring that the overall cost of the cartridge is relatively minimized.
The co-pending application provides for a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle having an orifice for outlet of water wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means such that all inlet water passes through said carbon block before exiting said filter cartridge.
While the invention of the co-pending application provides for a cost-effective filter cartridge for filtration of water while giving high flow rates and good filtration efficacy, it was observed that the flow rate of output water was not as consistent as desired. This problem was observed to be more acute when the filter was kept idle for some period of time. The present inventors have developed a novel solution to the problem, which ensures that the filter cartridge is modified to provide for consistent and relatively high flow rates.
OBJECTS OF THE INVENTION
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
4

Another object of the present invention to provide for a cost-effective filter cartridge which ensures the removal of particulate matter including microorganisms, like cysts, while providing for relatively high flow rate of water over a larger volume of inlet water, as compared to the prior art cartridges.
SUMMARY OF THE INVENTION
According to the present invention there is provided a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means wherein said filter cartridge comprises a collection chamber positioned below the carbon block in the receptacle for holding the water that exits the carbon block, said collection chamber comprising:
(a) a dome shaped holder plate provided with at least one water discharge port, said plate positioned in close proximity to the carbon block,
(b) an outlet nozzle for water having an inlet and outlet end, said inlet end positioned in close proximity to the under side of said plate
such that all the water passing through the carbon block collects in the space between the top of the plate and the carbon block before exiting through the discharge port to fill the collection chamber and exit through the nozzle.
Preferably, the carbon block is a carbon disc.
5

DETAILED DESCRIPTION OF THE INVENTION
The present inventors observed that especially when the carbon block of the copending application 801/MUM/2005 was idle for periods of time, the out put flow rate of the water exiting the filter cartridge was inconsistent. Without wishing to be bound by theory, the inconsistent flow rate is attributed to the problem of 'air-lock'. Air-lock is a severe problem which is observed in many low-pressure (including gravity fed) filtration apparatus, especially in those devices that operate in the down flow mode. When such filters are kept idle for periods of time, air enters into the cavities of the water flow path. Subsequently when the filter cartridge is used again to filter water, the air being lighter than water gets trapped in the form of bubbles in the cavities of the filter especially close to the underside of the filtration media, (the carbon block, in the present invention) and causes a back pressure and consequent loss of filtration surface area, both of which contribute to the reduction in the flow rate of water. The present inventors have developed a filtration cartridge which is believed to substantially minimize this problem thereby leading to consistently high filtration rates.
It is believed that the constructional features provided for in this invention viz. the dome shaped holder plate (HP) positioned close to the carbon block, the water discharge port (DP) on said plate, and the outlet nozzle (ON) for water having an inlet end positioned in close proximity to the under side of said plate, all work effectively in tandem to ensure that the filter cartridge of the invention provides the
6

desired high flow rates, consistently over time. Further, it is believed that when air is entrapped downstream of the carbon block, the constructional features of the invention ensures effective coalescence of the bubbles into a single air bubble which is directed towards a small volume, close to the inlet end of the outlet nozzle. Additionally the filtered water first collects on said plate, free of dispersed air bubbles and the pressure exerted by the collected water ensures that the single air bubble is first pushed out through the exit nozzle, thereby ridding the filter cartridge of the "air-lock" problem, thus providing an elegent and effective solution to this problem.
A highly preferred carbon block of the invention is a carbon disc. The disc may have a circular, oval, square or polygonal cross-section, preferably a circular cross-section. When a carbon disk is used, it is preferred that the dimensions are such that the ratio of the longest dimension to the thickness is in the range of 2:1 to 20:1, more preferably 3:1 to 15:1.
The collection chamber in the receptacle of the filter cartridge comprises a dome shaped holder plate which is in close proximity to the underside of the carbon block. The holder plate preferably has corrugations with troughs and peaks. The troughs form grooves on the upper side of the holder plate. The grooves are preferably spirally oriented. The holder plate has at least one water discharge port, preferably 2 and more preferably 4 or more. The collection chamber also comprises an outlet nozzle for water, which has an inlet end and an out let end.
7

The inlet end of the outlet nozzle is in close proximity to the underside of the holder plate, preferably positioned approximately equidistant from the periphery of the dome shaped holder plate.
The fastening means may be a closure which may be snap fit on to the receptacle, or a clamp which holds the carbon block on to the receptacle. The gasket means may be a gasket, an O-ring or any other means which serves the purpose of a gasket, which provides leak tightness to water when a fastening means is used to fasten two articles together.
It is preferred that the fastening means is a screw-threaded closure, which comprises an orifice for inlet of water and it is screwable on to the receptacle housing the carbon block. The receptacle is provided with corresponding screw threads for urging the carbon block against the gasket means provided in the base of the receptacle thereby attaching the carbon block in the filter cartridge. The closure may be provided on its bottom surface with downwardly projecting members which are urged against the top surface of the carbon block, as the closure is screwed on to the receptacle thereby urging the bottom surface of the carbon block against the gasket means placed in the base of the receptacle thereby ensuring the necessary leak tightness. When the carbon block is desired to be detached from the filter cartridge, the closure is unscrewed from the receptacle thereby releasing the carbon block. One or more orifices are provided on the closure for inlet of water on to the carbon block. It is preferred that the
8

orifice comprises at least 30% of the surface area of the top surface of the closure.
The invention is especially suitable and configured to be capable of filtering water which is contaminated with particulate contaminants, including dust and microorganisms e.g. protozoan cyst like Cryptosporidium and Giardia. The invention is capable of 99% removal (two log removal) preferably 99.9% removal (three log removal) of cyst. Log removal is defined as the log10 of the number of input particles minus the log™ of the number of output particles. The carbon blocks are made from activated carbon, more preferably powder activated carbon.
It is desirable to include a replaceable sediment filter that externally envelops the carbon block such that water passes through the sediment filter before passing through the carbon block. The sediment filter preferably corresponds to the shape of the carbon block. The sediment filter may be washable or replaceable and is preferably a woven or non-woven fabric, more preferably a non-woven fabric having micropores. This sediment filter ensures filtration of particles generally above 3 microns. The sediment filter can be washed and rinsed under flowing tap water with mild scrubbing.
The receptacle and the fastening means are preferably made of polymeric materials. Preferred polymeric materials include polypropylene, polyethylene, acrylonitrile butadiene styrene, or styrene acrylonitrile. The gasket means is
9

preferably made from natural or synthetic rubber, synthetic elastomers, teflon, nitrile rubber or silicone.
The term carbon block is used to denote a block prepared using activated carbon particles bound together using polymeric binder under the action of heat and pressure. The term polymeric binder preferably has Melt Flow Rate (MFR) less than 5 g/ 10 minutes, preferably less than 2 g/ 10 minutes, more preferably less then 1 g/10 minutes. The melt-flow rate (MFR) is measured using ASTM D 1238 (ISO 1133) test. Bulk density of the binder used as per the invention is preferably less than or equal to 0.6 g/cm3, more preferably less than or equal to 0.5 g/cm3, and further more preferably less than or equal to 0.25 g/cm3.
The carbon block preferably comprises powder activated carbon (PAC) having a particle such that not more than 5% medium passes through a sieve of 200 mesh and not more than 5% is retained on a sieve of 12 mesh. The PAC is preferably obtained from bituminous coal, coconut shell, wood, or petroleum tar. The surface area of the PAC is preferably selected such that it exceeds 500 m2/g, more preferably exceeds 1000 m2/g.
It is preferred that the PAC has a size uniformity co-efficient of less than 2, or more preferably less than 1.5, a carbon tetrachloride number exceeding 50%, more preferably exceeding 60%. The PAC preferably has an Iodine number greater than 800, more preferably greater than 1000.
10

The proportion of the binder material to the PAC particles by weight is chosen such that it is preferably in the range of 1:1 to 1:10, more preferably in the range of 1:2 to 1:6.
By way of the above filter cartridge of the invention it is possible to attain average flow rate of water, from a starting height of 200 mm down to 50 mm under gravity, of 600-50 ml/min., preferably 200-50 ml/min., without compromising on the requirements of removal of particulate including microorganisms, and chemical contaminants.
According to another aspect of the present invention there is provided a method of obtaining filtered water at flow rates in the range of 50 to 600 ml/minute comprising the steps of
(i) filtering water through a filter cartridge of the invention; and
(ii) replacing the carbon block in the filter cartridge whenever the flow rate of water is below desired value with a block which provides the desired flow rate.
The present invention facilitates easy removal of the carbon block from the cartridge to rejuvenate it, after which the carbon block is easily re-attachable in the cartridge.
11
The details of the invention, its objects and advantages are explained hereunder in greater detail in relation to the following non-limiting exemplary embodiments of the invention:
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings,
Fig. 1 is a schematic of a filter cartridge of the invention with a carbon disc filter assembled in a receptacle comprising a dome shaped holder plate and an outlet nozzle.
Fig. 2 is a schematic of the detailed construction of a typical dome shaped holder plate with corrugations.
DETAILED DESCRITION OF THE DRAWINGS
Referring to Fig.1, the filter cartridge comprises a carbon disk (CB) seated on a gasket (G) provided in the base of a receptacle (R) which has a collection chamber (CC) provided with a dome shaped holder plate (HP) and an outlet nozzle (ON) for outlet of water. The outlet nozzle has an inlet end (IE) and an outlet end (OE). The dome shaped holder plate is positioned close to the underside of the carbon block. The dome shaped holder plate has two discharge ports (DP) at or close to the peripheral ends of the plate. The inlet end (IE) of the
12

outlet nozzle is positioned close to the underside of the dome shaped holder plate, preferably equidistant from the peripheral ends. The receptacle has a closure (CL) which has an orifice on the top surface (not shown) for inlet of water. The closure has screw threads (ST1) with which it is screwed on to the receptacle provided with corresponding screw threads (ST2). Downwardly projecting members (M) are provided on the closure for urging the carbon disk against the gasket as the closure is screwed on to the receptacle. The gasket ensures leak-proof outlet such that all the water fed to the filter cartridge passes though the carbon block before exiting it.
Referring to Figure 2, the dome shaped holder plate has corrugation (C) on the upper side forming grooves (GR).
When in use, the water enters the closure (CL) through the orifice provided thereon (not shown) and flows through the carbon disk (CB) enabling filtration and firsts collects in the space between the carbon disk and the dome shaped holder and exits into the bottom part (B) of the collection chamber through the discharge ports (DP). The water collects and fills the collection chamber. When the water is filled to the height of the inlet end (IE) of the outlet nozzle (ON), the water enters the outlet nozzle through the inlet end (IE), flows in the downward directions and exits the filter cartridge through the outlet end (OE) of the outlet nozzle.
13

It will be appreciated that the invention as embodied, provides for a filter cartridge which ensures desired particulate removal while giving the high desired flow rate of water very consistently over larger volumes of water while providing a higher efficiency in terms of the amount of water filtered for a given amount of carbon.
Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.
14

We Claim:
1. A cartridge for filtration of water, said cartridge comprising:
(i) a carbon block seated in a receptacle, said carbon block being detachably attachable to said receptacle by a fastening means and a gasket means; and
(ii) a collection chamber positioned below said carbon block in said receptacle for holding the water that exits said carbon block, said collection chamber comprising:
a dome shaped holder plate provided with at least one water discharge port, said plate positioned in close proximity to said carbon block and an outlet nozzle for water, said outlet nozzle having an inlet end and an outlet end, said inlet end positioned in close proximity to the under side of said plate, such that all the water passing through said carbon block collects in the space between the top of the plate and said carbon block before exiting through said discharge port to fill said collection chamber and exit through said outlet nozzle.
2. A filter cartridge as claimed in claim 1 wherein said carbon block is a carbon disk.
15

3. A filter cartridge as claimed in claim 1 or claim 2 wherein said plate is provided on the upper side with corrugations such that water collected in the grooves of said corrugations leads to said water discharge port.
4. A filter cartridge as claimed in claim 3 wherein said grooves are spirally oriented.
5. A filter cartridge as claimed in any one of the preceding claims wherein inlet end of said nozzle is equidistant from the periphery of the holder plate.
6. A filter cartridge as claimed in any one of the preceding claims wherein said fastening means is a screw threaded closure which comprises an orifice for inlet of water and is screwable on to said receptacle provided with corresponding screw threads for urging said carbon block against said gasket provided in the base of said receptacle.
7. A filter cartridge as claimed in any one of the preceding claims wherein
said receptacle and said fastening means are made of materials
selected from polymers which includes polypropylene, polyethylene,
acrylonitrile butadiene styrene and styrene acrylonitrile.

A filter cartridge as claimed in any one of the preceding claims wherein said gasket means is made of natural or synthetic rubber, synthetic elastomers, teflon, nitrile rubber or silicone.
A filter cartridge substantially as herein described with reference to the accompanying examples and figures.
A method of obtaining filtered water at flow rates in the range of 50 to
600 ml/minute comprising the steps of:
(i) filtering water through a filter cartridge as claimed in any one of
the preceding claims; and
(ii) replacing the carbon block in the filter cartridge whenever the flow
rate of water is below desired value with a block which provides
the desired flow rate.
Dated this 7th day of November 2006

17

ABSTRACT A CARTRIDGE FOR FILTRATION OF WATER
The present invention relates to a filter cartridge for filtration of water and to a cost-effective filter cartridge for gravity filtration of water substantially free of particulate contaminants including microorganisms like cysts while consistently providing for relatively high flow rates of output water. It is an object of the present invention to provide a cost-effective filter cartridge, which ensures desired particulate removal including microorganisms like cysts while giving the desired high flow rate more consistently over a larger volume of inlet water, as compared to the prior art cartridges. Accordingly, the present invention provides a filter cartridge for filtration of water comprising a carbon block that is seated in a receptacle wherein said carbon block is detachably attachable in said receptacle using a fastening means and a gasket means wherein said filter cartridge comprises a collection chamber positioned below the carbon block in the receptacle for holding the water that exits the carbon block, said collection chamber comprising a dome shaped holder plate provided with at least one water discharge port said plate positioned in close proximity to the carbon block, and an outlet nozzle for water having an inlet and outlet end, said inlet; end positioned in close proximity to the under side of said plate such that all the water passing through the carbon block collects in the space between the top of the plate and the carbon block before exiting through the discharge port to fill the collection chamber and exit through the nozzle.

A CARTRIDGE FOR FILTRATION OF WATER

Documents:

Inventors:

PCT Conventions: