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Patent Abstract
A unitary water filter assembly and method for removing all microbiological
and multiple types of chemical contaminants from water used in an
appliance for human consumption are provided. The filter assembly
includes a first filter stage fluidly coupled to receive influent
water for filtering chemical contaminants therein. A second filter
stage is fluidly coupled to the first filter stage for filtering
microbiological organisms therein. The filter assembly allows removal
of all microorganisms such as cysts, bacteria, bacterial spores
and viruses, from the drinking water. The filter assembly may also
be configured to remove chemicals, such as chlorine, including associated
taste and odor with such chemicals, particulates, and metal contaminants
from drinking water. The filter assembly may be further configured
to remove volatile organic compounds (VOCs), and other organic and
inorganic contaminants from drinking water.
Patent Claims
What is claimed is:
1. A unitary water filter assembly comprising: a first filter stage
fluidly coupled to receive influent water for filtering chemical
contaminants therein; and a second filter stage fluidly coupled
to the first filter stage for filtering microbiological organisms
therein, wherein the microbiological organisms are selected from
the group consisting of cysts, bacteria, bacterial spores, viruses
and any combination thereof.
2. The water filter assembly of claim 1 wherein the first filter
stage comprises an adsorbent cartridge.
3. The water filter assembly of claim 2 wherein the adsorbent in
the cartridge is selected from the group consisting of activated
carbon, calcined clay, kaolinite, adsorption resins, carbonaceous
type resins, silica gels, alumina, zeolites, nanoparticles and any
combination thereof.
4. The water filter assembly of claim 1 wherein the second filter
stage comprises an ultrafiltration membrane comprising a bundle
of hollow fiber filters.
5. The water filter assembly of claim 1 wherein the second filter
stage comprises an ultrafiltration membrane comprising spiral wound
flat sheet membranes.
6. The water filter assembly of claim 1 wherein the second filter
stage is concentrically disposed relative to the first filter stage
to receive filtered water output therefrom.
7. The water filter assembly of claim 6 further comprising a wrap
of polypropylene media interposed between an adsorption cartridge
and an ultrafiltration membrane comprising a bundle of hollow fiber
filters to remove carbon particulates, wherein the adsorption cartridge
comprises the first filter stage and the ultrafiltration membrane
in the form of hollow fiber filters comprises the second filter
stage.
8. The water filter assembly of claim 1 further comprising a sleeve
of polypropylene media interposed between an outer canister and
an adsorption cartridge to remove colloidal particulate material,
wherein the adsorption cartridge comprises the first filter stage.
9. The water filter assembly of claim 1 wherein the second filter
stage is serially disposed downstream relative to the first filter
stage.
10. The water filter assembly of claim 9 further comprising a pad
of polypropylene media interposed between an adsorption cartridge
and an ultrafiltration membrane comprising a bundle of hollow fiber
filters to remove carbon particulates, wherein the adsorption cartridge
comprises the first filter stage and the ultrafiltration membrane
in the form of hollow fiber filters comprises the second filter
stage.
11. The water filter assembly of claim 9 further comprising a sleeve
of polypropylene media to remove colloidal particulate material
from the influent water prior to an adsorption cartridge, wherein
the adsorption cartridge comprises the first filter stage.
12. The water filter assembly of claim 1 further comprising a sealing
assembly configured to avoid cross-contamination between influent
and effluent water passing through the filter assembly.
13. The water filter assembly of claim 12 further comprising a
needle valve, wherein the needle valve is configured to provide
a predefined amount of flow restriction to effluent water passing
therethrough.
14. The water filter assembly of claim 13 further comprising an
affixing lid at one end of a shell containing a bundle of hollow
fiber filters, the lid configured to affix respective open ends
of the bundle of hollow fiber filters, wherein the open ends provide
passage to water that enters through the exterior of the hollow
fiber filters, travels through the hollow interior and exits free
from the microbiological organisms.
15. The water filter assembly of claim 12 wherein the seal assembly
comprises a gasket seated around the needle valve, said gasket comprising
a base for sealing passage of water between the affixing lid and
an external interface manifold.
16. The water filter assembly of claim 15 wherein the gasket further
comprises a tapered surface for sealing passage of water relative
to a passageway defined in the manifold for receiving the needle
valve.
17. A method for removing contaminants from water dispensed by
an appliance, the method comprising: fluidly coupling a first filter
stage to receive influent water for filtering chemical contaminants
therein; and fluidly coupling a second filter stage to the first
filter stage for filtering microbiological organisms therein, wherein
the microbiological organisms are selected from the group consisting
of cysts, bacteria, bacterial spores, viruses and any combination
thereof.
18. The method of claim 17 further comprising configuring the first
filter stage as a cartridge to adsorb the chemical contaminants
therein.
19. The method of claim 18 wherein adsorbent material in the cartridge
is selected from the group consisting of activated carbon, calcined
clay, kaolinite, adsorption resins, carbonaceous type resins, silica
gels, alumina, zeolites, nanoparticles and any combination thereof.
20. The method of claim 17 further comprising configuring an ultrafiltration
membrane in the form of a bundle of hollow fiber filters, the hollow
fiber filters constituting the second filter stage.
21. The method of claim 17 further comprising configuring an ultrafiltration
membrane in the form of spiral wound flat sheet membranes, the flat
sheet membranes constituting the second filter stage.
22. The method of claim 17 further comprising concentrically disposing
the second filter stage relative to the first filter stage to receive
filtered water output therefrom.
23. The method of claim 22 further comprising interposing a wrap
of polypropylene media between an adsorption cartridge and an ultrafiltration
membrane comprising a bundle of hollow fiber filters to remove carbon
particulates, wherein the adsorption cartridge comprises the first
filter stage and the ultrafiltration membrane in the form of a bundle
of hollow fiber filters comprises the second filter stage.
24. The method of claim 17 further comprising interposing a sleeve
of polypropylene media between an outer canister and an adsorption
cartridge to remove colloidal particulate material, wherein the
adsorption cartridge comprises the first filter stage.
25. The method of claim 17 further comprising serially disposing
the second filter stage downstream relative to the first filter
stage.
26. The method of claim 25 further comprising interposing a pad
of polypropylene media between an adsorption cartridge and an ultrafiltration
membrane comprising a bundle of hollow fiber filters to remove carbon
particulates, wherein the adsorption cartridge comprises the first
filter stage and the ultrafiltration membrane in the form of hollow
fiber filters comprises the second filter stage.
27. The method of claim 25 further comprising providing a sleeve
of polypropylene medium to remove colloidal particulate material
from the influent water prior to an adsorption cartridge, wherein
the adsorption cartridge comprises the first filter stage.
28. The method of claim 17 further comprising configuring a sealing
assembly to avoid cross-contamination between influent and effluent
water passing through the filter assembly.
29. The method of claim 28 further comprising providing a predefined
amount of flow restriction to effluent water passing through a needle
valve.
30. The method of claim 29 further comprising affixing respective
open ends of a bundle of hollow fiber filters to an affixing lid,
wherein the open ends provide passage to water entering through
the exterior of the hollow fiber filters, traveling through the
hollow interior and exiting free from the microbiological organisms.
31. The method of claim 30 wherein the configuring of the seal
assembly comprises seating a gasket around the needle valve and
providing a base for sealing passage of water between the affixing
lid and a corresponding section of an interface manifold.
32. The method of claim 31 further comprising tapering a surface
of the seal gasket for sealing passage of water relative to a passageway
defined in the manifold for receiving the needle valve.
Patent Description
BACKGROUND OF THE INVENTION
[0001] Water filters, such as in-line after market water filters
for refrigerators, filters pre-installed in a refrigerator unit
and under-the-counter water filters, have been able to remove many
chemical contaminants, and, may have been able to remove some relatively
large microbiological organisms, such as cysts (i.e., protozoa such
as Cryptosporidium and Giardia) from drinking water. These filters,
however, have not been able to remove from the drinking water smaller
microbiological organisms, e.g., bacteria, bacterial spores and/or
viruses.
[0002] Separate and relatively bulky and complex treatment units
specially configured (e.g., using ultraviolet radiation) for the
treatment of the relatively small microbiological forms have been
required to meet these microbiological treatment needs. Unfortunately,
the addition of such a specialized separate treatment unit to an
appliance would lead to substantial incremental costs, assuming
that the manufacturer of the appliance is even able to find the
appropriate space for installing any such separate treatment unit.
[0003] In view of the foregoing considerations, it would be desirable
to provide a microbiological water purifier filter that may be affordably
and compactly manufactured to provide a unitary filter assembly
for reliable and cost-effective removal of all forms of microbiological
organisms, including cysts, bacteria, bacterial spores and/or viruses
as well as removal of chemical contaminants, such as chlorine and
other contaminants. It would be further desirable to provide a microbiological
water purifier filter that without the use of a drain and/or electrical
power is able to remove such microbiological organisms.
BRIEF SUMMARY OF THE INVENTION
[0004] Generally, the present invention fulfills the foregoing
needs by providing in one aspect thereof, a unitary water filter
assembly including a first filter stage fluidly coupled to receive
influent water for filtering chemical contaminants therein, and
a second filter stage fluidly coupled to the first filter stage
for filtering microbiological organisms therein, such as cysts,
bacteria, bacteria spores and viruses.
[0005] In another aspect thereof, the present invention further
fulfills the foregoing needs by providing a method for removing
contaminants from water dispensed by an appliance for consumption,
e.g., human, pet consumption, etc. The method allows fluidly coupling
a first filter stage to receive influent water for filtering chemical
contaminants therein. The method further allows fluidly coupling
a second filter stage to the first filter stage for filtering microbiological
forms therein, such as cysts, bacteria, bacteria spores and viruses.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The features and advantages of the present invention will
become apparent from the following detailed description of the invention
when read with the accompanying drawings in which:
[0007] FIG. 1 is a cross-sectional view of one exemplary embodiment
of a water filter assembly, including concentrically disposed first
and second filter stages for removing chemical and microbiological
contaminants, respectively.
[0008] FIG. 2 shows exemplary water flow paths within the filter
assembly of FIG. 1.
[0009] FIG. 3 is a cross-sectional view of another exemplary embodiment
of a water filter assembly, including serially disposed first and
second filter stages for removing chemical and microbiological contaminants,
respectively.
[0010] FIG. 4 shows exemplary water flow paths within the filter
assembly of FIG. 3.
[0011] FIG. 5 is a cross-sectional view of a coupling assembly
that may be used by either of the water filter assemblies of FIGS.
1 and 3 for avoiding or reducing the possibility of cross-contamination
between influent and effluent water passing through the filter assembly.
[0012] FIG. 6 is a side view of a shell containing ultrafiltration
membranes in the form of hollow fiber filters for removal of all
forms of microbiological organisms.
[0013] FIG. 7 is an expanded view of exemplary components used
by a water filter assembly embodying aspects of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The inventors of the present invention have innovatively
recognized a relatively low-cost and compact unitary water filter
assembly for reliable removal of various microbiological organisms,
such as cysts, bacteria, bacterial spores and/or viruses as well
as removal of chemical contaminants.
[0015] In one exemplary embodiment, such as illustrated in FIG.
1, a filter assembly 10 comprises an outer canister 12 configured
to enclose a sleeve 14 made of a suitable polymer, such as polypropylene
melt blown or wound media, marketed in commerce under the trade
name/designation polyspun media. Sleeve 14 comprises a first filtering
path configured to remove particulates, e.g., colloidal particulate
material. Sleeve 14 encloses a cartridge 16 that constitutes a first
filtering stage configured to remove contaminants, such as oxidizing
chemicals, e.g., chlorine, including removal of taste and odor associated
with such oxidizing chemicals, and other chemical contaminants.
A second filter stage is concentrically disposed relative to the
first stage and, in operation, is fluidly coupled to the first stage
to receive filtered water that passes from the first stage to remove
any microbiological organisms that may be present in the filtered
water output from the first filter stage, as described in greater
detail below. Neither of the filter stages requires a drain or electrical
power for operation. In one exemplary embodiment, the unitary assembly
may be considered disposable at the end of its rated filtering capacity.
[0016] In one exemplary embodiment, cartridge 16 comprises a suitable
adsorbent, such as activated carbon, calcined clay, adsorption resins
(especially carbonaceous type, e.g., Ambersorb 563), silica gels,
alumina, kaolinite and zeolites, nanoparticles and any combination
thereof. In one exemplary embodiment, activated carbon is used because
of the high adsorption capacity and relatively low cost of activated
carbon. In one exemplary embodiment, a sufficiently large amount
of carbon could be added to enable the cartridge to remove a spectrum
of organic compounds, such as volatile organic compounds (VOCs)
and other organic compounds that might contaminate drinking water.
A suitable metal-adsorbent material, such as a metal-adsorbent resin,
can be optionally incorporated in the cartridge to remove metal
contaminants from the water, such as lead and/or mercury and other
such contaminants.
[0017] A shell 18, such as may be made of plastic, in one exemplary
embodiment comprises a mesh opening or plurality of slots, holes
or openings to permit flow of water through it. Shell 18 may be
configured to define an inner core for receiving ultrafiltration
membrane filters 20. In one exemplary embodiment, the ultrafiltration
membrane filters comprise membranes, such as hollow filter membranes
or spiral wound flat sheet membranes with pores of a size appropriate
for removing all microbiological contaminants. In one exemplary
embodiment, the pore size may be a minimum of approximately 0.025
microns (25 nanometers) in size. It will be understood that the
foregoing example is just that, an example, and should not be construed
as a limitation of the present invention. In general, an ultrafiltration
membrane functions as a molecular sieve. It separates particles
and molecules on the basis of size by passing a solution through
an infinitesimally fine filter. This ultrafilter comprises a relatively
tough, thin, selectively permeable membrane that retains most macromolecules
above a certain size, including colloids, microorganisms and pyrogens.
For readers desirous of additional background information regarding
the physical principles involved in the filtering action provided
by ultrafiltartion membranes, reference is made to the Report issued
by the United States Environmental Protection Agency, EPA 815-C-01-001
(April 2001), titled "Low-Pressure Membrane Filtration For
Pathogen Removal: Application, Implementation, And Regulatory Issues,"
which report is incorporated herein by reference.
[0018] In one exemplary embodiment, the ultrafiltration membranes
may be configured to block passage to particles and/or microbiological
organisms greater than approximately 0.025 microns (25 nanometers)
in diameter. By way of example, such microbiological organisms may,
include cysts (protozoa such as Cryptosporidium, Giardia, Toxoplasma,
etc., and parasites such as Entamoeba, etc.), bacteria, bacterial
spores and viruses. Examples of ultrafiltration membranes suitable
for purposes of the present invention include those manufactured
by and commercially available from Millipore, Pall, Zenon, Norit,
etc. It will be understood that the present invention is not limited
to ultrafiltration membranes from such suppliers, since ultrafiltration
membranes from other suppliers can be readily used for purposes
of the present invention.
[0019] As shown in FIG. 1, in this exemplary embodiment, shell
18 and hollow fiber filters 20 constitute the second filter stage
which is concentrically disposed relative to the first filter stage
(e.g., adsorbent cartridge 16) for removing any forms of microbiological
organisms, including cysts, bacteria, bacterial spores and viruses
that may be received from the water that passes through the first
filter stage.
[0020] As best shown in FIG. 6, ultrafiltration membranes in the
form of hollow fiber filters may be looped at one end of shell 18
(e.g., shell end 19) so that the respective ends of each fiber with
corresponding openings are held in place by an affixing lid 22,
e.g., adhesive, plastisal, or other sealable media disposed at the
opposite end (e.g., shell end 21) of shell 18. In one exemplary
embodiment, affixing lid 22 provides an adhesive dam or structure
for receiving a suitable adhesive, (e.g., glue) for affixing the
respective ends of the fiber filters.
[0021] A layer or wrap 24, (FIG. 1) such as made of polyspun media
or other suitable filter element, may be interposed in the annular
space defined between adsorption cartridge 16 and shell 18 to block
passage to any particulates, such as carbon particulates, that may
exit from the cartridge during initial use of the cartridge. This
layer helps to extend the life of the ultrafiltration membranes.
[0022] In operation, as shown in FIG. 2, and represented by the
various arrows indicative of exemplary water flow within filter
assembly 10, influent water may enter the filter assembly through
an inlet port 30 disposed through a sealing cap 32 of canister 12
and travel through sleeve 14 and into the first filter stage, e.g.,
adsorbent cartridge 16. As will be now appreciated by those skilled
in the art, sleeve 14 provides a pre-filtering process to remove
colloidal particulate materials that may be present in the influent
water to prolong the operational life of the adsorption cartridge.
After the filtering action provided by adsorption cartridge 16,
water would then flow through wrap 24 and into shell 18, e.g., filled
with ultrafiltration membranes in the form of hollow fiber filters,
through a plurality of openings at the base or on the sides of the
shell. Water would then pass through the bundle of hollow fiber
filters from the exterior of each hollow fiber filter to the respective
interior of the hollow fiber filter. As suggested above, the hollow
fiber filters are configured to remove all microbiological organisms,
such as cysts, bacteria, bacterial spores and viruses from the water.
In one exemplary embodiment, water would travel upwardly along the
inside of each hollow fiber filter and would exit through the openings
at the respective ends affixed to affixing lid 22.
[0023] A needle valve 40 may be provided to direct the flow of
the purified effluent water through a respective interface manifold
50. The needle valve may serve at least two purposes. One purpose
would be to provide a user-friendly and secure interface with a
passageway 52 in manifold 50 for passing effluent water. Another
purpose of the needle valve is that one may configure the needle
valve as a flow restrictor for the filter assembly. As will be appreciated
by those skilled in the art, such a flow restrictor may be used
to achieve enhanced adsorption of contaminants passing through the
adsorption cartridge since the adsorption ability of the cartridge
may be time dependent. For example, increased contact time with
the carbon may facilitate adsorption of certain contaminants that
may be present in the water. Thus, by appropriately restricting
the flow of effluent water exiting from the filter assembly, in
essence one may appropriately set the contact time for water that
passes through the adsorption cartridge. It will be appreciated
that such a flow restrictor may be directly built into the filter
assembly (e.g., the needle valve) or the flow restrictor may be
provided external to the filter assembly. For example, in a refrigerator
the restrictor could be coupled in an outlet for a water dispenser
therein. In one exemplary embodiment, it may be preferred to have
the flow restrictor integrated with the filter assembly so as to
provide a stand-alone filter. This would allow for a more universal
filter interface because one would be able to provide any appropriate
flow rate to meet any given requirements for removal of chemical
contaminants through the adsorption cartridge.
[0024] As will be appreciated by those skilled in the art, another
aspect of the present invention provides a seal assembly 100 (FIG.
5) configured to avoid cross-contamination between influent water
that may comprise microbiological organisms and the purified effluent
water. In one exemplary embodiment, a tapered gasket 102 is situated
around needle valve 40. Gasket 102 provides at least two sealing
areas: 1) For example, gasket 102 comprises a base 104 configured
to provide a sealing action between a manifold section, e.g., the
bottom section of manifold 50, and affixing lid 22 and 2) gasket
102 further comprises a tapered surface 105 to provide a sealing
action relative to the passageway 52 in manifold 50 that receives
the needle valve 40 for passing effluent water. In one exemplary
embodiment, manifold 50 includes a pair of O-rings 106 and 108 configured
to provide respective sealing actions between engaging male and
female couplers 110 and 112, respectively. In one exemplary embodiment,
O-rings 106 and 108 would prevent leakage of influent water along
a path represented by dashed line 114. It is believed that, in the
unlikely event that each of O-rings 106 and 108 were to fail to
provide their respective sealing function, gasket 102 would provide
a backup sealing action to prevent passage of influent water that
could otherwise cross-contaminate the effluent water from the filter
assembly.
[0025] In another exemplary embodiment, as illustrated in FIG.
3, a filter assembly 10' comprises a second type of filter stage
(e.g., the microbiological filter comprising ultrafiltration membranes
in the form of hollow fiber filters 20 in shell 18) that is serially
disposed (e.g., downstream) relative to the first stage (e.g., adsorbent
cartridge 16). In operation, the second filter stage is fluidly
coupled to the first stage to receive filtered water from that first
stage to remove any and all microbiological organisms that may be
present in the water output from the first filter stage. In this
case, a pad 60, such as a circular pad made of polyspun media or
other suitable filter element, may be interposed between adsorption
cartridge 16 and shell 18 to block passage to any particulates,
such as carbon particulates, that may exit from the cartridge during
initial use of the cartridge. As suggested above, sleeve 14 may
be used to remove colloidal particulate material from the influent
water prior to adsorption cartridge 14. The various arrows shown
in FIG. 4 represent exemplary water flow within filter assembly
10'.
[0026] FIG. 7 is an expanded view of exemplary components used
by a water filter assembly embodying aspects of the invention. This
view should facilitate visualizing the relative simplicity of assemblage
of some of the relatively few components of a unitary and compact
water filter assembly that advantageously provides both removal
of chemical and microbiological forms, in accordance with aspects
of the present invention. As shown in FIG. 7, outer canister 12
may be configured to receive the various components that comprise
the first and second filter stages, such as cartridge 16, ultrafiltration
membranes 20, sleeve 14, etc., as described above. FIG. 7 further
shows affixing lid 22 for affixing the ultrafiltration membranes
within the inner core of cartridge 16. Sealing cap 32 allows to
seal canister 12 and further allows interface with an adaptor plug
56 that, for example, threadingly mates with a tubing head 58 that
allows interfacing with suitable water-conducting lines or tubing
in the appliance, such as lines or tubing connected to a water dispenser
and/or an ice maker of a refrigerator appliance.
[0027] While the preferred embodiments of the present invention
have been shown and described herein, it will be obvious that such
embodiments are provided by way of example only. Numerous variations,
changes and substitutions will occur to those of skill in the art
without departing from the invention herein. Accordingly, it is
intended that the invention be limited only by the spirit and scope
of the appended claims. |