U.S. patent application number 13/570787 was filed with the patent office on 2012-11-29 for chitosan-coated fibers to satisfy nsf50 test standard for spas and pools.
This patent application is currently assigned to FREUDENBERG FILTRATION TECHNOLOGIES, L.P.. Invention is credited to Kartik POTUKUCHI.
Application Number | 20120298595 13/570787 |
Document ID | / |
Family ID | 42980214 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120298595 |
Kind Code |
A1 |
POTUKUCHI; Kartik |
November 29, 2012 |
CHITOSAN-COATED FIBERS TO SATISFY NSF50 TEST STANDARD FOR SPAS AND
POOLS
Abstract
A fibrous filter media is provided for meeting NSF 50
requirements for water turbidity in pools, hot tubs and spas which
includes a sheet of nonwoven fibers coated with chitosan, wherein
the sheet may be pleated or present in a stacked layer
configuration.
Inventors: |
POTUKUCHI; Kartik;
(Hopkinsville, KY) |
Assignee: |
FREUDENBERG FILTRATION
TECHNOLOGIES, L.P.
Hopkinsville
KY
|
Family ID: |
42980214 |
Appl. No.: |
13/570787 |
Filed: |
August 9, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12427239 |
Apr 21, 2009 |
|
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13570787 |
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Current U.S.
Class: |
210/767 |
Current CPC
Class: |
C02F 1/001 20130101;
B29K 2005/00 20130101; C02F 1/5263 20130101; B01D 2239/0233
20130101; B01D 2239/0464 20130101; C02F 2103/42 20130101; B01D
39/163 20130101 |
Class at
Publication: |
210/767 |
International
Class: |
E04H 4/16 20060101
E04H004/16 |
Claims
1. A method of treating pool and spa water, comprising: providing a
quantity of water to be filtered; providing a filter including
filter media; circulating said quantity of water through said
filter media, wherein said filter media comprises nonwoven fibers
and chitosan, wherein the chitosan has been deposited on said
nonwoven fibers at a level of 0.5% to 8.0% by weight and wherein
said filter indicates a turbidity remaining value (TR) of less than
0.3 after a fifth turnover of water volume wherein the testing
conditions comprise: (1) water temperature 24+/-6.degree. C.; (2)
turbidity before addition of silica (TB1)<2 nephelometric
turbidity units; (3) turbidity after adding silica (TB2)=45+/-10
nephelometric turbidity units; (4) flow rate is 0.16 liters per
minute; (5) water volume is 1.6 liters; (6) turnover time is 10
minutes; (7) turbidity after one turnover of said water volume is
TB3; wherein TR=(TB3-TB1)/(TB2-TB1).
2. The method of claim 14 wherein said filter media comprises a
pleated sheet.
3. The method of claim 14 wherein said filter media comprises a
sheet stacked in layers.
4. The method of claim 14 wherein said chitosan level is in the
range of about 2.0% to 4.0% by weight.
5. The method of claim 14 wherein said fibers comprise bicomponent
polyester fibers in a sheath-core configuration.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 12/427,239 filed Apr. 21, 2009, the teachings
of which are incorporated herein by reference.
FIELD
[0002] The present disclosure is related to the filtration and
treatment of water in pools and spas, and more particularly, to the
use of chitosan-coated fibers as a media which may satisfy the
NSF50 test standard for turbidity reduction.
BACKGROUND
[0003] Swimming pools, spas, whirlpools and hot tubs may be enjoyed
and used to improve one's health as well as relieve physical and
psychological stresses. Swimming pools, spas, whirlpools and hot
tubs require that the water be filtered in order to assure that the
water is kept clean in terms of water quality. The control of dirt,
debris, hair, oils, and microorganisms from the water may be
critical towards ensuring the health and safety of the individuals
using such. This may be particularly true with indoor swimming
pools which may generally be heated and used year round. Sweat,
hair and other foreign matter originating from the human body may
be sources of bacterial growth that may contaminate the water and
deteriorate its quality.
[0004] To eliminate contaminants, the water has traditionally been
treated by continuous passage through relatively fine filters
containing sand or diatomaceous earth, following passage through a
relatively coarse filter for the removal of materials such as
particulates, dirt, debris, insects, hair, etc. The water may then
be returned to the pool or tub. Generally, a chemical product such
as chlorine, chlorine dioxide, bromine, iodine, ozone or the like,
may be added to the water as it is being circulated in order to
provide a safe environment for use.
[0005] Sand and diatomaceous earth have typically been the
filtration media of choice, but are not the only filtration media
currently available. Substitutes for sand and/or diatomaceous earth
include ceramic filters and activated carbon. For example, porous
ceramic filters have a three-dimensional network of extremely fine
filtering spaces that can trap organic matter, such as oils.
However, these ceramic filters can become easily clogged with the
build-up of oils, dirt and biofilm formed by microorganisms
associated with the typical pool environment. Most pool filter
systems require occasional backwashing to rejuvenate the filter
media. Many different types and styles of diatomaceous earth
filters are available. Some are designed to be pressure backwashed
Oils (body oils, tanning oils, etc.) typically float on the surface
of the water. In pool and spa situations with high concentrations
of oils, significant quantities of oil may simply flow through the
filter and return to the vessel. The oils that are trapped by
diatomaceous earth tend to bond the filter cake to the grids and
eventually may impregnate the grid material itself. The end result
may be large volumes of water needed to backwash the diatomaceous
earth from the grids, fouled grids and an increasing buildup of
diatomaceous earth at the bottom of the filter. Oils that are not
removed may result in scum lines in the pool/spa and reduced water
clarity.
[0006] Alternatively, the filter often used for the filtration of
pool or spa water may be a filtration cartridge mounted in
combination with the water delivery system. The coarsely filtered
water may be filtered through a system comprising a basket or
filter cartridge containing a filter bag or a filter element.
Filter elements may generally be made of a pleated fabric arranged
radially around a central cylinder. The base of the cartridge may
be in communication with a suction system in order to filter the
water that enters from the outside of the cartridge and passes
through its walls. Although the fabric filter may remove
contaminants, it may become soiled relatively quickly from the
build up of oils, microorganisms and biofilm, and it may be quite
difficult to clean due to its construction. Cleaning of the filter
may not easily lend itself to decontamination and removal of
microorganisms.
[0007] NSF International has been recognized as a leader in public
health safety for pools and such. For the last 40 years, NSF has
been helping people Swim Safer.TM. by meeting the needs of public
health inspectors, product manufacturers, aquatic facility
managers, facility users, and homeowners through a vast array of
testing and certification services.
[0008] At the core of NSF's service offerings to this industry is
the NSF Pool and Spa Equipment Program. This program encompasses
voluntary standards, such as NSF/ANSI Standard 50, plus various
standards criteria from ASTM, ASME, and others.
[0009] Of all the relevant pool and spa industry standards and
criteria, NSF/ANSI Standard 50 is special due to the manner in
which it was created and its continued evolution. The registered
NSF Certification Mark on a pool, spa, or hot tub system component
confirms that NSF has assessed--and certified--its conformity with
the relevant section of NSF/ANSI Standard 50 and/or other product
standards.
[0010] NSF/ANSI Standard 50 --Equipment For Swimming Pools, Spas,
Hot Tubs and Other Recreational Water Facilities works to enable a
comprehensive product evaluation for health effects safety,
performance validation, and safety for factors such as burst,
sustained pressure, cyclic pressure, head loss, turbidity
reduction, filtration efficacy, disinfection efficacy, durability
or life testing, chemical resistance, corrosion resistance, and
electrical safety.
[0011] NSF Standard 50 applies to diatomite and other pre-coat
media filters, sand filters, cartridge filters, recessed automatic
surface skimmers, centrifugal pumps, drains, flexible pool and spa
hose, adjustable output rate chemical feeding equipment, multiport
valves, flow-through chemical feeding equipment, and process
equipment, including: in-line and brine type electrolytic
chlorinators; copper/silver and copper ion generators; UV systems;
and ozone generators. The components and materials are intended to
be used specifically for swimming pool, spa, or hot tub water
circulation and treatment in both public and residential
applications.
[0012] Section 5.4, Cartridge-type and High-permeability-type
Filters, references Section B.4, Filter Media Cleanability Test,
which specifies the method to determine head loss through the
filter after cleaning. It should not exceed 150% of the initial
head loss and not exceed the design head loss. Section B.5,
Turbidity Reduction Test, specifies the method to determine
turbidity reduction. The turbidity remaining ratio (TR) shall be
.ltoreq.0.3 or a 70% or greater reduction in turbidity after 5
passes of testing.
[0013] Accordingly, there is a need for fibrous filters that are
relatively inexpensive and wherein the fibers are coated with a
material that satisfies the requirements of NSF 50.
SUMMARY
[0014] In a first aspect, the present disclosure is directed at a
nonwoven filter media comprising a sheet of nonwoven fibers and
chitosan, wherein the chitosan has been deposited on said nonwoven
fibers at a level of 0.5% to 8.0% by weight wherein the filter
indicates a turbidity remaining value (TR) of less than 0.3 after a
fifth turnover of water volume when testing in accordance with NSF
50, Annex B.5.
[0015] In a second aspect, the present disclosure is directed at a
method of producing a nonwoven filter comprising providing a sheet
of nonwoven fibers, providing a solution of chitosan in water, and
dispersing the solution onto the sheet. This may be followed by
drying the sheet to evaporate said water and forming the sheet into
a filter media. The chitosan may be present on said fibers at a
level of 0.5% to 8.0% by weight wherein the filter indicates a
turbidity remaining value (TR) of less than 0.3 after a fifth
turnover of water volume when testing in accordance with NSF 50,
Annex B.5.
[0016] In a third aspect, the present disclosure is directed at a
method of treating pool and spa water, comprising providing a
quantity of water to be filtered and providing a filter including
filter media. This may then be followed by circulating the quantity
of water through said filter media, wherein the filter media
comprises nonwoven fibers and chitosan. The chitosan may be
deposited on the nonwoven fibers at a level of 0.5% to 8.0% by
weight and wherein the filter indicates a turbidity remaining value
(TR) of less than 0.3 after a fifth turnover of water volume when
testing in accordance with NSF 50, Annex B.5.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above-mentioned and other features and advantages of
this disclosure, and the manner of attaining them, will become more
apparent and the disclosure will be better understood by reference
to the following description of embodiments taken in conjunction
with the accompanying drawings, wherein:
[0018] FIG. 1 is a prospective view of a filter element according
to the present disclosure;
[0019] FIG. 2 is a graph indicating the Turbidity Remaining Ratio
for treated and untreated fibrous filters after a number of
successive tests according to NSF 50 Section B.5.
DETAILED DESCRIPTION
[0020] Chitosan is a linear polysaccharide composed of randomly
distributed .beta.-(1-4)-linked D-glucosamine (decetylated unit)
and N-acetyl-D-glucosamine (acetylated unit). It is a natural
occurring substance (produced by the deacetylation of chitin, the
structural element in the exoskeleton of crustaceans such as crabs
and shrimp). Chitosan may be biodegradable and may have
anti-microbial and anti-fungal properties.
[0021] Chitosan has been shown to improve flocculation and to cause
fine sediment particles to bind together. Chitosan may also remove
phosphorus, heavy minerals, and oils from water.
[0022] The present disclosure is directed at the use of chitosan to
assist a nonwoven substrate to augment fluid filtration as applied
to the pool and spa filtration market, and in particular, to
replace the need to pre-load with a filter aid such as diatomaceous
earth. This may be achieved without sacrificing the ability to
achieve NSF 50 test standards.
[0023] FIG. 1 is perspective view of a filter cartridge 10 having a
pleated fabric media 20 made of non-woven fibers which have been
coated with a solution containing chitosan, resulting in the
deposition of about 2.0 to 4.0% by weight of chitosan to the
fibrous media. Giving considerations to filtration requirements and
production efficiency, the deposition of chitosan may therefore now
be conveniently applied in the range of 0.5%-8.0% by weight for a
given fibrous media, including all values therein, in 0.1%
increments.
[0024] The fibers may be in the form of a nonwoven or carded
nonwoven and may further comprise a web of spunbonded polyester
bi-component core-sheath fibers. The sheath portion of the fiber
may be bonded to one or more adjacent fibers, forming an
interconnected array of fibers. The sheath material connects the
fibers together, such that the nonwoven filter media may be porous.
This bonding may generally be accomplished by melting the sheath
material about the core fiber. At points of contact, the melted
sheath material solidifies upon cooling, thereby forming an
interconnected porous filter media. The fibers may have a denier in
the range of about 2-6, preferably about 4.
[0025] The nonwoven fabric may be stacked in layers or pleated to
form the filter media.
[0026] It is contemplated that the nonwoven fabric may be formed
from meltblown fibers as well as spun bonded. As used herein, the
term "nonwoven fabric" is used to mean a sheet that has a structure
of individual fibers or filaments which are interlaid, but not in
an identifiable repeating manner.
[0027] As used herein, the term "spunbonded" is understood to mean
the process of producing a web or sheet of small diameter fibers
and/or filaments which are formed by extruding a molten
thermoplastic material as filaments from a plurality of fine,
usually circular, capillaries in a spinneret with the diameter of
the extruded filaments then being rapidly reduced, for example, by
fluid-drawing or other well known spunbonding mechanisms.
[0028] As used herein, the term "meltblown" is understood to mean
the process of producing fibers formed by extruding a molten
thermoplastic material through a plurality of fine, usually
circular, die capillaries as molten threads or filaments into a
high-velocity gas (e.g. air) stream which attenuates the filaments
of molten thermoplastic material to reduce their diameters, which
may be to microfiber diameter. Thereafter, the meltblown fibers are
carried by the high-velocity gas stream and are deposited on a
collecting surface to form a web of randomly dispersed meltblown
fibers.
[0029] While the description above regarding FIG. 1 mentions
sheath-core bicomponent fibers, it is contemplated that other
configurations of bicomponent fibers may be used, including but mot
limited to, side-by-side, segmented pie structure and
islands-in-the-sea (matrix/fibril).
[0030] As used herein, the term "bicomponent fibers" is understood
to mean fibers produced by extruding two polymers having different
melting points from the same spinneret with both polymers contained
within the same filament.
[0031] While the description above mentions polyester fibers being
used, it is further contemplated that other materials may be used
to form the bicomponent fibers, such as polyamide, polyolefin,
polycarbonate, polystyrene, thermoplastic elastomer, fluoropolymer,
vinyl polymer and combinations thereof.
[0032] The basis weight of the nonwoven fabric may generally range
from about 70 to about 200 g/m.sup.2, preferably from about 100 to
about 150 g/m.sup.2, and most preferably about 135 g/m.sup.2. The
nonwoven fabric may generally have a thickness range from about 0.4
to about 1.0 millimeters, preferably about 0.5 millimeters.
[0033] To coat the fibers with chitosan, as alluded to above, a
solution of about 2.0% to 4.0% chitosan in water was prepared, the
nonwoven fabric was run under a roll submerged in the solution to
wet the it and then run through two rubber rolls to squeeze the
excess solution out to achieve a level of about 2.0 to 4% by weight
of chitosan on the fabric. After drying to remove the water, the
fabric was formed into a single layer filter element about 3 inches
in diameter and about 0.5 mm in thickness. The effective filter
area was about 38.6 cm.sup.2.
[0034] The filter element was inserted into a filter cartridge
which was part of a recirculating system designed for testing
turbidity according to NSF 50. The parameters of the test regimen
were as follows: [0035] Specified Water temperature,
24.+-.6.degree. C. [0036] Specified Turbidity prior to adding
silica, (TB1), .ltoreq.2 NTU* [0037] Specified Turbidity after
adding silica, (TB2), 45.+-.10 NTU* [0038] *NTU is a measure of
turbidity in Nephelometric Turbidity Units [0039] Actual Flow rate,
0.16 liters per minute [0040] Actual Water volume, 1.6 liters
[0041] Actual Water temperature, 20.degree. C. [0042] Turn-over
time, 10 minutes [0043] Testing material, Sil-Co-Sil.RTM. 106
[0044] Turbidimeter, HACH2100N
[0045] The filter element having chitosan-treated fibers, 135CNG,
was tested and the results compared to a filter element having the
same nonwoven construction but not treated with the chitosan
solution, 135NG. The results of the turbidity test for each filter
element, 135CNG and 135NG, are listed below in Table 1.
TABLE-US-00001 TABLE 1 135CNG 135NG (with chitosan) (without
chitosan) TB1 = 0.2 NTU TB1 = 1.03 NTU TB2 46.7 TB2 45.7 Turnover**
TB3 15.5 1 TB3 32.3 9.36 2 26.0 8.19 3 22.4 5.82 4 20.3 4.14 5 17.6
**Turnover is the number of times that the water volume is passed
through the filter.
[0046] To calculate the Turbidity Remaining (TR),
TR=(TB3-TB1)/(TB2-TB1)
wherein TR which must be less than 0.3, after the fifth turnover of
the water volume.
[0047] Table 2 identifies the TR values for the individual
turnovers for each filter element.
TABLE-US-00002 TABLE 2 135CNG (with chitosan) 135NG (without
chitosan) TR TR Turnover 0.329 1 0.700 0.197 2 0.559 0.172 3 0.478
0.121 4 0.431 0.085 5 0.371
[0048] As can be seen from Table 2, the filter element containing
chitosan (135CNG) met the required level of Turbidity Remaining
(TR.ltoreq.0.3) after the second through fifth turnover, while the
untreated filter element (135NG) was unable to meet the requirement
after any of the turnovers. FIG. 2 shows these results in graphical
form.
[0049] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *