U.S. patent application number 11/045555 was filed with the patent office on 2006-08-03 for reticulated liquid treatment devices with electric power source.
Invention is credited to Primo L. Acernese, Thomas Lotts, James JR. Novak, William J. Parkinson.
Application Number | 20060171841 11/045555 |
Document ID | / |
Family ID | 36756758 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060171841 |
Kind Code |
A1 |
Acernese; Primo L. ; et
al. |
August 3, 2006 |
Reticulated liquid treatment devices with electric power source
Abstract
The present invention relates to devices for treating liquids,
and methods for treating liquids, particularly by using such
devices. Reticulated electrode structures with a high proportion of
surface area to volume are formed with at least two metals, and are
coupled in arrays to an electrical driving signal such as an
alternating and/or direct current voltage source, for ion exchange
with a liquid to be treated, to produce, e.g., potable water.
Inventors: |
Acernese; Primo L.;
(Allentown, PA) ; Novak; James JR.; (Emmaus,
PA) ; Lotts; Thomas; (Austin, TX) ; Parkinson;
William J.; (Bethlehem, PA) |
Correspondence
Address: |
DUANE MORRIS, LLP;IP DEPARTMENT
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103-4196
US
|
Family ID: |
36756758 |
Appl. No.: |
11/045555 |
Filed: |
January 28, 2005 |
Current U.S.
Class: |
420/477 ;
420/587 |
Current CPC
Class: |
C02F 1/441 20130101;
C02F 1/46109 20130101; C22C 18/02 20130101; C22C 9/04 20130101;
C22C 30/02 20130101; C02F 2001/46157 20130101; C02F 1/4604
20130101; C22C 30/06 20130101; C02F 1/4606 20130101 |
Class at
Publication: |
420/477 ;
420/587 |
International
Class: |
C22C 9/04 20060101
C22C009/04; C22C 30/02 20060101 C22C030/02 |
Claims
1. A device for treating liquids, comprising at least two metals,
said metals having reticulated structures, wherein said reticulated
structures are coupled to an electrical driving signal for ion
exchange, electron transfer or electro-catalysis with the liquid to
be treated.
2. The device as recited in claim 1, wherein the metals are in the
form of an alloy.
3. The device as recited in claim 1, wherein the electrical driving
signal is an alternating current or a direct current voltage
source.
4. The device of claim 1, further comprising a substrate having
said reticulated structure, wherein said metals are disposed upon
said substrate.
5. The device of claim 4 wherein said substrate comprises a
non-metallic material.
6. The device of claim 5 wherein said substrate comprises a
material selected from the group consisting of ceramics, polymers,
and composite materials.
7. The device of claim 4, wherein said substrate comprises a
metal.
8. The device of claim 1 wherein at least two of said metals are
selected from the group consisting of copper, gold, platinum,
magnesium, aluminum, activated alumina, zinc, tin, titanium and
palladium.
9. The device of claim 1 wherein said metals comprise copper, zinc
and silver.
10. The device of claim 9, comprising at least about 20 weight
percent zinc.
11. The device of claim 9, comprising up to about 45 weight percent
zinc.
12. The device of claim 9, comprising at least about 35 weight
percent copper.
13. The device of claim 9, comprising up to about 60 weight percent
copper.
14. The device of claim 9 comprising from about 40 weight percent
to about 60 weight percent copper, from about 25 weight percent to
about 45 weight percent zinc, and from about 0.5 weight percent to
about 25 weight percent silver.
15. The device of claim 1, comprising at least about 0.5 weight
percent silver.
16. The device of claim 1, comprising at least about 8 weight
percent silver.
17. The device of claim 1, comprising up to about 30 weight percent
silver.
18. The device of claim 1, wherein said reticulated structure
comprises a porosity of at least about 90 percent.
19. The device of claim 1, wherein said reticulated structure
comprises a porosity of at least about 95 percent.
20. The device of claim 1, wherein said reticulated structure
comprises pores having diameters of at least about 5 microns.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to devices for treating
liquids, and methods for treating liquids, particularly by using
such devices. Reticulated electrode structures with a high
proportion of surface area to volume are formed with at least two
metals, and are coupled in arrays to an electrical driving signal
such as an alternating current or direct current voltage source,
for e.g., ion exchange, electron transfer, galvanic absorption,
etc. with a liquid to be treated, to produce, e.g., potable
water.
BACKGROUND OF THE INVENTION
[0002] Water is of course needed for any number of uses, such as
general household, industrial, military and medical applications.
The water may be obtained from a source in which the water is aptly
purified prior to use. It may also be advisable to purify used or
"gray" water before discharging it into the environment.
Purification may include removing from the water (or reducing the
proportionate content thereof) undesired biological and/or chemical
entities, or neutralizing or counteracting the activity or
detrimental effects of such materials. Any number of materials may
be involved, such as microorganisms, including bacteria,
protozoans, or viruses; algae; noxious chemicals; radioactive
material; or heavy metals.
[0003] Typical methods of purification may include chemical
treatment, such as treatment with oxidizing agents (e.g, chlorine)
or other reagents intended to precipitate or neutralize harmful
components; application of electromagnetic energy (e.g.,
ultraviolet light) as a biocidal step; sedimentation of solids that
are entrained or precipitated; filtration through particle and/or
reverse osmosis filter media; application to surface active agents
or passage over surface absorption elements of activated carbon or
the like; or ion exchange.
[0004] A common chemical treatment includes combining water with
one or more compounds containing chlorine. Chlorine is useful in
controlling bacteria and is often used in the form of hypochlorous
acid or calcium hypochlorite. However, chlorine (Cl.sub.2) can
damage purification elements such as reverse osmosis filters, and
discharge of chlorinated water raises environmental concerns. Other
chemical compounds that have been used for treatment of water,
particularly for removal of organic compounds, include potassium
permanganate and sodium hydroxide.
[0005] Reverse osmosis generally uses a filtration membrane, which
allows a liquid such as water to pass through while partially or
completely retaining species such as salts. Flow across the
membrane is driven by a chemical potential gradient; generally,
osmosis relies on a gradient from high concentration to low
concentration. In reverse osmosis, a "reverse" gradient can be
formed, e.g., by the application of an external driving force such
as pressure or mechanical means. Membranes used in osmosis can have
a chemical charge, imparted by the presence of functional groups
such as carboxylic or sulfonic groups on the membrane. Charged
membranes that can allow relatively high liquid flux and can remove
compounds such as organic materials and color agents are used in
modern filtration techniques, such as nanofiltration.
[0006] Precipitants and coagulants are also known for use in water
treatment and purification, and can be used in combination with
other agents. An exemplary water purification composition is
disclosed in U.S. Pat. No. 5,681,475, hereby incorporated by
reference. This patent discloses a composition provided in
unit-dosage form, including a disinfectant-sanitizer; a coagulant
precipitant; a dispersion-buffer agent; a primary colloidal
flocculant; a secondary colloidal flocculant; an agglomeration
matrix and pre-filter; and a bulk ion exchange absorbent.
[0007] It may be desirable or necessary to remove heavy metals from
a water supply. Metals in water supplies or wastewater may include,
for example, copper, chromium, zinc, cadmium, mercury, lead and
nickel. Metals and other similar contaminants may be removable by
chemical precipitation as carbonates, hydroxides or sulfides, or by
activated carbon, reverse osmosis, ion exchange and other known
techniques.
[0008] On the other hand, certain metal ions are known to be active
as algaecides, bactericides, etc., and some metals may be useful as
reagents that bind with chlorine or other halogen water treatment
agents. Metal particulate or metal powder elements are used for
water treatment, and may be placed serially in a water flow so as
to interact with a flow of water. Typical metals used in
particulate form for water purification include zinc and copper,
which are useful for treating water containing chlorine and
bacteria, respectively. U.S. Pat. No. 5,314,623, incorporated
herein by reference, discloses a method for treating fluids that
utilizes a bed of metal particles such as aluminum, steel, zinc,
tin, copper, and mixtures and alloys thereof. The preferred metals
are zinc and copper, which can be combined in the form of an alloy
such as brass, to which the water is exposed.
[0009] A need remains for improvements and new effective treatment
methods and devices for water and other liquids. A particular
benefit could be obtained by improving methods and devices that can
effectively remove bacteria and/or heavy metals. The present
invention is directed toward these and other important ends.
SUMMARY OF THE INVENTION
[0010] One aspect of the invention is a device for treating liquids
which includes a reticulated element or structure formed from at
least two metals, one of which metals preferably is silver. The
metals are preferably in the form of an alloy, and although
integral are caused by reticulation to have a porous or foamed
shape characterized by a high proportion of surface area to volume.
The device has two or more electrically isolated portions that are
held at a potential difference by an electric power supply.
Isolation can be provided, for example, by interspersing a
non-conducting material between the reticulated structures to which
electrical power is applied. The power supply is preferably a
moderate direct current voltage source, but it is also possible to
employ time varying signals or polarity reversal, etc., such as
alternating current.
[0011] In embodiments, the reticulated structures or elements are
disc-shaped. The disc-shaped reticulated structures can be stacked
and carried in a housing that defines a flow path for water over
the elements. For example, a number of reticulated metal discs can
be stacked in series in the housing, with the water flowing through
the reticulated bodies of the discs. In certain embodiments, two or
more of the reticulated structures are in direct contact with one
another, whereby they are electrically connected. In other
embodiments, two or more of the reticulated structures are spaced
apart from each other or stacked on an "interleaved" insulator,
such that they do not come into direct contact with one another and
can be coupled respectively to the anode and cathode leads of the
power supply. Alternatively, one or more elements can be held at a
given potential or driven at a predetermined time varying voltage
relative to another reference, such as a metallic portion of the
housing to which the water is exposed.
[0012] Another aspect of the invention is a method for reducing the
apparent hardness of a liquid. The method includes treating the
liquid by contacting the liquid with a device comprising two or
more reticulated structures coupled to anode and cathode leads of
an electrical power supply. The reticulated structures may be
spaced apart from each other or stacked on an interleaved
insulator, such that they do not come into direct contact with one
another. In other embodiments, a plurality of reticulated
structures having the same charge, i.e. anode or cathode, are
stacked in contact with one another, and are separated by an
insulating material from one or more reticulated structures having
the opposite charge.
[0013] In embodiments, one or more discs made of a non-metallic
material may be included. Such non-metallic discs may be located so
that a first non-metallic disc contacts a reticulated disc coupled
to the anode and a second non-metallic disc contacts a reticulated
disc coupled to the cathode. One or more additional reticulated
discs may be disposed between the first and the second non-metallic
discs.
[0014] These and other aspects of the present invention will be
apparent to one skilled in the art in view of the following
disclosure and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1(a) shows a device for treating liquid, which includes
reticulated discs and a pair of electrodes;
[0016] FIG. 1(b) shows a device for treating liquid, which includes
reticulated discs in direct contact and a pair of electrodes;
[0017] FIG. 2(a) shows a device for treating liquid, which includes
a plurality of reticulated discs having a positive charge and a
single reticulated disc having a negative charge, wherein the
positively charged discs and the negatively charged disc are
isolated from one another by a non-conducting disc of insulating
material;
[0018] FIG. 2(b) shows a device for treating liquid, which includes
a plurality of reticulated discs having a negative charge and a
single reticulated disc having a positive charge, wherein the
negatively charged discs and the positively charged disc are
isolated from one another by a non-conducting disc of insulating
material; and
[0019] FIG. 3 shows a device for treating liquid, which includes a
single reticulated disc having a positive charge, a single
reticulated disc having a negative charge, and two non-conducting
discs made of a plastic or ceramic material.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The methods and devices disclosed herein utilize the
application of electric power and ion release/deposition elements
in the treatment of liquids such as water, and in particular relate
to coupling a direct or alternating current to respective
reticulated metal elements placed in contact with a flow of
water.
[0021] The term "treatment," as used herein to refer to the use of
the devices and methods of the present invention, means contacting
a liquid with a device as described, in order to reduce, remove,
inactivate, neutralize, kill, react, modify, adjust or otherwise
affect chemical and/or biological entities in the liquid. This may
be accomplished with a raw liquid or a liquid that has been
subjected to additives or previous treatment steps, or a liquid
that is yet to be subjected to further additives or steps.
Generally, the idea is to ameliorate undesirable agents in the
liquid, and treatment can therefore include purification. However,
it is to be understood that treatment in accordance with this
disclosure is not limited to purification or total or partial
removal of one or more chemical and/or biological entities, and
that other results are within the scope of the invention.
[0022] Liquid treatment devices that utilize reticulated metal
structures are described in U.S. Pat. Nos. 6,395,168, 5,972,216 and
5,788,858. The disclosures of these documents are hereby
incorporated by reference. The metals used in the devices and
methods disclosed in the '168 patent can include silver and at
least two other metals. In some embodiments, a metal oxide can be
used in place of one of the three or more metals.
[0023] In accordance with the present invention, it has been found
that driving two or more reticulated elements as electrodes (or a
single element versus a casing or other reference) with an electric
driving current, can enhance the performance of the reticulated
elements in connection with treatment of a liquid. The driving
signal can be a direct or alternating current potential difference.
Current between the driven elements (or the element and the opposed
electrode in the circuit) is generally characterized by the release
(dissolution) or deposition (plating) of metal ions and other
elements and compositions, from or onto the surfaces of the
reticulated metal structures to which the liquid is exposed in the
treatment, which can enhance the performance of the reticulated
metal structures.
[0024] The devices of the present invention include one or more
reticulated structures made of at least two metals. One of the
metals can be silver. Silver is desirable in the devices of the
present invention because of its known bactericidal properties.
Other metals are also suitable, including copper, zinc, tin,
nickel, aluminum, magnesium, vanadium, cobalt, molybdenum,
titanium, gold, manganese, platinum, palladium, tungsten, rhenium,
and tantalum. The particular composition chosen can be due in part
to the physical and chemical properties of the liquid to be
treated, the amount of driving voltage to be applied, and other
factors consistent with this disclosure.
[0025] Using the example of a DC driving voltage, a conventional DC
power supply comprising a transformer, rectifier and optional
parallel capacitor can develop a direct current voltage or
potential difference from the domestic mains. The voltage can be
coupled to two of the reticulated elements, or between one such
element and a casing or other conductive surface that the liquid
contacts. The connections can be made in the usual ways that power
connections are made, such as by soldering conductors to the
element(s) and/or casing or providing an appropriate contact that
is resiliently biased against the element or casing. In a DC
example, two conductors couple the power supply to electrodes
(reticulated elements or other conductors that contact the liquid
and are not in direct conductive contact), functioning as an anode
and a cathode. Two exemplary configurations are shown in FIGS. 1
and 2.
[0026] In embodiments, the applied voltage is about 12-24 volts or
less, more preferably about 9 volts or less, with about 7 volts or
less particularly preferred. In addition, the applied voltage is
preferably at least about 3 volts.
[0027] The electrode leads may be made of conventional conductive
materials such as stainless steel, copper or aluminum, or may
comprise a composite material. By coupling to the power supply at
least one reticulated element and at least one other conductor in
contact with the liquid, the respective electrodes (10 in figures)
are made more disposed to release ions (11 in figures) into the
liquid or to accept the deposition of ions, by electrophoresis
effects. The potential difference tends to generate a current in
the form of ions physically moving between the liquid and one of
the anode and the cathode due to electromagnetic forces.
[0028] The conductors may be coupled to the elements by soldering
or by fasteners (e.g., screws) or simply by contact from resilient
pressure. However, the ion exchange activity is such that soldering
is preferred. An electrode that releases ions can erode and shrink
relative to a simple pressure contact. Also, compounds that are
deposited can accumulate and interfere with good conductive
connection.
[0029] FIG. 1(a) shows one exemplary embodiment of the devices of
the invention. Two or more reticulated disc-shaped structures 12
(also referred to herein as "discs") are placed inside a
cylindrical housing 13. In the embodiment shown, four discs are
used; however, the number of discs is not critical and can be
selected, in part, based on the properties of the liquid to be
treated. In the embodiment shown in FIG. 1(a), the discs 12 are not
in direct contact with one another but are spaced apart from one
another. Spacing is optional, and the size of space between discs
may be from about 10 mm to about 3 inches, although a separation
about equal to several (2, 3, or 4, preferably 2) disc thicknesses
may advantageously be used. If the discs are not spaced apart, a
nonconductive panel 16 such as a polymer screen or sieve element
may be placed between the discs to prevent shorting of the power
supply.
[0030] The discs, whether contacting one another or spaced apart,
can conveniently be provided in a cartridge as exemplified in the
figures by a cylindrical housing 13 into which the discs fit.
Generally, the cylindrical housing 13 containing the discs 12 is
perforated or slotted, so that the liquid being treated can enter
the housing and contact the discs. The housing containing the discs
can be packaged (in tube 14) and transported to its point of use.
Although the embodiments shown in the figures depict the discs
stacked vertically atop one another, any configuration may be used;
for example, the discs may be oriented alongside one another,
whereby a central axis through the discs would be substantially
horizontal. Thus, the orientation in space of the devices of the
present invention is generally not critical, although for certain
applications a configuration in which, e.g., a liquid to be treated
flows upward, may be desirable.
[0031] FIG. 1(b) shows an embodiment wherein a number of stacked
discs 15 are in direct conductive contact. The discs are coupled to
the same potential because they are in conductive contact with one
another, and at least one of the discs, and optionally several or
all of the discs, are soldered or otherwise connected to a lead
from the power supply (not shown).
[0032] FIG. 2(a) shows an embodiment wherein most of the discs 20
are positively charged. Such a configuration may be useful for
removing negatively charged contaminants from a fluid.
[0033] FIG. 2(b) shows an embodiment wherein most of the discs 21
are negatively charged. Such a configuration may be useful for
removing positively charged contaminants from a fluid.
[0034] An alternate exemplary embodiment is shown in FIG. 3. In the
embodiment shown in FIG. 3, two of the discs (30a and 30b of discs
30) are made of a plastic, i.e. Lexan.TM. polycarbonate, from
General Electric. Other plastic or ceramic materials can be used,
provided they are electrically insulating. Exemplary suitable
plastic materials for use in the insulating discs include
polycarbonate, polyethylene, polypropylene, and
polytetrafluoroethylene. In the embodiment shown, one of the
plastic discs 30a contacts a negatively-charged reticulated disc
30c, and the second plastic disc 30b contacts a positively charged
reticulated disc 30d. One or more additional discs, such as
reticulated discs, can be disposed between the two plastic discs,
and those reticulated discs will be "unelectrified", i.e. not
coupled to an electrical voltage.
[0035] The methods and devices disclosed herein preferably utilize
reticulated metal structures. A "reticulated" structure, as used
herein, is meant to denote a structure resembling a network of
fibers or a mesh-like or sponge-foam like configuration of the
metal, in an integral or solid body that defines numerous through
passages. Reticulated structures made of brass are described in
U.S. Pat. No. 5,788,858. Reticulated structures are desirable for a
variety of reasons, including the durability and ease of handling
integral discs as opposed to particulates, the inherent electrical
connection of all parts of the integral body, the favorable ratio
of surface area-to-volume, porosity and/or permeability leading to
minimal flow resistance.
[0036] Reticulated structures for use according to the present
invention preferably have porosities of at least about 85 percent,
more preferably at least about 90 percent, even more preferably at
least about 95 percent, with a porosity of at least about 97
percent particularly preferred. "Porosity" refers to void volume,
i.e., empty volume, within the outer outline of the structure. Pore
sizes are preferably at least about 1 micron in diameter, more
preferably at least about 2 microns, still more preferably at least
about 3 microns, even more preferably at least about 4 microns, and
still even more preferably at least about 5 microns. Also
preferably, the pore diameters are about 500 microns or less, more
preferably about 450 microns or less, still more preferably about
400 microns or less, even more preferably about 350 microns or
less, and still even more preferably about 300 microns or less. The
term "diameter" as used herein is not intended to imply that pores
are necessarily spherical or cylindrical, but rather "diameter" is
used to conveniently refer to the dimension in a single pore,
measured laterally relative to a longitudinal flow direction.
Reticulated structures having pores of highly irregular shapes are
within the scope of the present invention, and are preferred
because the irregularity further contributes to a high
proportionate surface area for exposure to the liquid being
treated.
[0037] A reticulated structure can be formed from metal particles
bound together, such as the foam-like structures shown in U.S. Pat.
No. 5,599,456, which is also incorporated herein by reference.
Other methods for forming a reticulated structure include melting
followed by melt extraction. In an exemplary technique, a molten
alloy of three of more metals is extracted, cooled, and solidified
into fibers. The fibers preferably have a structure similar to that
of a ribbon or tape. The fibers preferably have thicknesses of at
least about 15 microns, more preferably at least about 20 microns,
still more preferably at least about 25 microns, and even more
preferably at least about 30 microns. Also preferably, the fibers
are about 3000 microns thick or less, more preferably about 2000
microns thick or less, still more preferably about 1500 microns
thick or less, and even more preferably about 1000 microns thick or
less. The thicknesses recited herein refer to the thickest part of
a fiber. While flat, ribbon-like fibers are preferred, fibers
having other structures, including cylindrical or highly irregular
shapes, are within the scope of the present invention. The fibers
preferably are at least about 0.5 millimeters long, more preferably
at least about 1 millimeter long, still more preferably at least
about 1.5 millimeters long, and even more preferably at least about
2 millimeters long. Also preferably, the fibers are up to about 100
millimeters, more preferably up to about 75 millimeters, and still
more preferably up to about 50 millimeters long. Alternatively,
metal substrates can be formed by vacuum compression of metal
particles.
[0038] In preferred embodiments, the reticulated structures are
formed from laminates of the metals. Laminates can be formed by
depositing three or more metals onto a substrate having the
above-described reticulated structure. Metals can be deposited onto
a substrate, for example, by electrodeposition, chemical vapor
deposition, physical vapor deposition (sputtering), high energy ion
bombardment, plasma implant processes, dip coating, and
metallurgical processes known to those skilled in the art.
[0039] The substrate can be made of any material to which the
desired metals for a device can be adhered. If the substrate is to
be removed to leave flow passages, non-metal substrates should be
used of a material that can be "burned off", i.e., decomposed, upon
heating to a temperature that is below the melting point of the
metal or metals, preferably at temperatures used in forming a
laminate on the substrate. Alternatively, it is possible to apply
metal to the surfaces of a substrate that is preformed and intended
as a permanent support. Exemplary materials suitable as substrates
for forming the laminates include polymeric materials such as
plastics, wood, carbon, and composite materials, which are subject
to heat decomposition. Exemplary composite materials include
ceramics and cermets and can comprise one or more compounds such as
silica, alumina, and titania. Exemplary plastic and polymeric
materials include polyethylene, polypropylene, polystyrene,
polycarbonate, polyurethane, copolymers of acrylic and non-acrylic
polymers, and blends thereof. Any plastic, polymeric or composite
material that can provide a suitable reticulated structure having
desired properties of porosity, rigidity and pore size is useful.
Plastic and polymeric materials can contain additives and
processing aids known to those skilled in the art. Plastic and
polymeric materials may contain additives that enhance their
physical properties and/or facilitate deposition of a metallic
coating thereon.
[0040] Following deposition of the metals, if deposition has been
accomplished by a method that does not utilize sufficient heat to
decompose the substrate, the metals and substrate are heated to a
temperature and for a time sufficient to at least partially
decompose the substrate, preferably to substantially vaporize the
substrate, including any additives and processing aids contained in
the substrate. The required temperature and time depend upon the
composition of the substrate, and can be determined by one skilled
in the art. As an example, for a polyethylene substrate, a
temperature of about 1,000 to 2,000 degrees F. is generally
adequate.
[0041] In some embodiments, the substrate can be metal and can be
in forms such as, for example, meshes or wires. Metal substrates
will generally not be decomposed, but will remain an integral part
of the reticulated structure. Particles of individual metals and/or
metal alloys can be deposited onto a metal form of, e.g., copper.
Following deposition of the metal or alloy onto the metal
substrate, the coated substrate can be annealed, and, if desired,
can be further treated. Further treatments can include, for
example, high energy ion bombardment, chemical vapor deposition or
physical vapor deposition.
[0042] The devices and methods of the present invention can be used
to treat any liquid, preferably an aqueous liquid, especially
water. Preferably, for treatment using the devices and methods of
the present invention, a liquid has an ionic impurity concentration
of less than about 2000 mg/L, more preferably less than about 1500
mg/L. If necessary, prior to treatment using the devices and
methods of the present invention, the ionic impurity concentration
of a liquid can be reduced using conventional methods known to
those skilled in the art.
[0043] The devices and methods of the present invention can reduce
the apparent hardness of a liquid, particularly that of water. By
"apparent hardness" it is meant coagulation or deposition of ions,
which can lead to scale formation. When the apparent hardness of a
liquid is reduced, although the concentration of ions in the liquid
remains the same, deposition and scale formation is reduced. Thus,
the liquid may have a concentration of ionic material that would
cause it to be termed "hard", but has a reduced apparent
hardness.
[0044] The devices and methods of the present invention can be used
in combination with other purification techniques, such as reverse
osmosis. Preferably, a liquid purified by a device of the present
invention is subjected to further purification, such as reverse
osmosis, after having been contacted with the device. The use of
the devices of the present invention to treat a liquid prior to
subjecting the liquid to reverse osmosis reduces biological
contamination of membranes used in subsequent filtration or reverse
osmosis. The metal reticulated structure of the device of the
invention also reduces or removes chlorine present in
chlorine-treated or contaminated water, reducing damage to
membranes used in filtration or reverse osmosis. In addition to or
in place of subsequent treatment, a liquid can be treated using one
or more conventional treatment methods prior to subjecting the
liquid to treatment using the devices and methods of the present
invention. For some applications, the devices disclosed herein may
be used in combination with modular and mobile water purification
plants such as the reverse osmosis water purification unit
(acronym: "ROWPU") that is employed for delivery of potable water
or to treat gray water before discharge into the environment.
[0045] While the present invention has been described with respect
to particular embodiments thereof, it is apparent that numerous
other forms and modifications of the invention will be obvious to
those skilled in the art. The appended claims and this invention
generally should be construed to cover all such obvious forms and
modifications, which are within the true spirit and scope of the
present invention.
* * * * *