U.S. patent application number 14/635694 was filed with the patent office on 2016-01-28 for water purification and enhancement systems.
This patent application is currently assigned to The Water Initiative, LLC. The applicant listed for this patent is THE WATER INITIATIVE, LLC. Invention is credited to Eugene A. FITZGERALD, Thomas LANGDO, Richard RENJILIAN, Carl V. THOMPSON, III, Ya-Hong XIE.
Application Number | 20160023144 14/635694 |
Document ID | / |
Family ID | 47747187 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160023144 |
Kind Code |
A1 |
FITZGERALD; Eugene A. ; et
al. |
January 28, 2016 |
WATER PURIFICATION AND ENHANCEMENT SYSTEMS
Abstract
Water purification system comprising filtration media sized with
respect to each other to allow a first contaminant in the water to
saturate the first medium with a delay prior to saturation of the
second medium with a second contaminant.
Inventors: |
FITZGERALD; Eugene A.;
(Windham, NH) ; XIE; Ya-Hong; (Dana Point, CA)
; LANGDO; Thomas; (Cambridge, MA) ; RENJILIAN;
Richard; (Gurnee, IL) ; THOMPSON, III; Carl V.;
(Acton, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE WATER INITIATIVE, LLC |
Boca Raton |
FL |
US |
|
|
Assignee: |
The Water Initiative, LLC,
Boca Raton
FL
|
Family ID: |
47747187 |
Appl. No.: |
14/635694 |
Filed: |
March 2, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14335478 |
Jul 18, 2014 |
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14635694 |
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13137507 |
Aug 22, 2011 |
9206058 |
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14335478 |
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PCT/US2010/024531 |
Feb 18, 2010 |
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13137507 |
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61154070 |
Feb 20, 2009 |
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Current U.S.
Class: |
422/261 ;
210/201; 210/335; 210/764; 210/806; 210/85; 99/290 |
Current CPC
Class: |
C02F 1/004 20130101;
C02F 1/68 20130101; B01D 63/00 20130101; C02F 1/688 20130101; C02F
2303/185 20130101; C02F 1/008 20130101; C02F 2101/103 20130101;
B01D 27/146 20130101; C02F 1/44 20130101; C02F 1/283 20130101; C02F
2101/12 20130101; C02F 2307/10 20130101; C02F 2305/14 20130101;
C02F 9/00 20130101; C02F 1/281 20130101; B01D 29/56 20130101; C02F
1/001 20130101; C02F 1/76 20130101; C02F 1/50 20130101; B01D 35/143
20130101; C02F 1/003 20130101; C02F 2303/04 20130101; C02F 9/005
20130101; C02F 1/444 20130101 |
International
Class: |
B01D 35/143 20060101
B01D035/143; C02F 1/00 20060101 C02F001/00; C02F 1/68 20060101
C02F001/68; C02F 1/76 20060101 C02F001/76; C02F 1/44 20060101
C02F001/44; B01D 63/00 20060101 B01D063/00; B01D 29/56 20060101
B01D029/56; C02F 1/28 20060101 C02F001/28; C02F 1/50 20060101
C02F001/50 |
Claims
1. A water purification system comprising at least two filtration
media sized with respect to each other to allow a first contaminant
in the water to saturate the first medium with a delay prior to
saturation of the second medium with a second contaminant.
2. A water purification system according to claim 1, which is a
point of use system.
3. A water purification system according to claim 1, wherein said
at least two filtration media are located upstream of a water
reservoir.
4. A water purification system according to claim 1, wherein a
prefilter is provided immediately upstream of said at least two
filtration media for removal of large particles and sediment from
the water.
5. A water purification system according to claim 1, wherein
chlorine and arsenic are contaminates.
6. A water purification system according to claim 1, wherein a
first filtration media is activated carbon when the first
contaminant is chlorine and a second filtration media is activated
alumina, granulated ferric oxide and/or granulated ferric hydroxide
when the second contaminant is arsenic.
7. A water purification system comprising: at least two filtration
media sized with respect to each other to allow a first contaminant
in the water to saturate the first medium with a delay prior to
saturation of the second medium with a second contaminant; and time
release capsules to impart flavor to indicate end-point-detection
of the filtration media.
8. A water purification system according to claim 7, wherein the
time-release capsules are continuous.
9. A water purification system according to claim 7, wherein the
time release capsules are abrupt.
10. A water purification system according to claim 9, wherein the
abrupt capsules are positioned as a last stage of the system.
11. A water purification system according to claim 8, wherein the
continuous capsules are positioned upstream of another media that
will saturate at some point, and allow entry of taste into the
water.
12. A water purification system comprising: at least two filtration
media sized with respect to each other to allow a first contaminate
in the water to be saturated first with a delay before a second
contaminate is saturated; color time release capsules to impart
color to indicate end-point-detection of the filtration media.
13. A water purification system according to claim 12, wherein the
color time-release capsules are continuous.
14. A water purification system according to claim 12, wherein the
time release capsules are abrupt.
15. A water purification system according to claim 14, wherein the
abrupt capsules are positioned as a last stage of the system.
16. A water purification system according to claim 13, where the
continuous capsules are positioned upstream of another media that
will saturate at some point, and allow entry of color into the
water.
17. A water purification system comprising: at least two filtration
media sized with respect to each other to allow a first contaminate
in the water to be saturated first with a delay before a second
contaminate is saturated; and time release capsules for
continuously introducing flavor or a therapeutic substance into the
water.
18. A water purification system according to claim 17, wherein the
time release capsules are positioned such that the flavor is
introduced into the water in a last stage of the system.
19. A method of purifying water comprising passing water through a
system comprising at least two filtration media sized with respect
to each other to allow a first contaminate in the water to be
saturated first with a delay before a second contaminate is
saturated.
20. A method according to claim 19, wherein the water is measured
to determine a level of taste imparting compounds and the level of
arsenic in the water; the filtration media is tested to determine
how long it will take a volume of media to be saturated with taste
imparting compounds and with arsenic; and the volumes of the media
in the system are chosen to allow the taste imparting compounds in
the water to be saturated first with a delay before the arsenic is
saturated.
21. A water purification system according to claim 1, further
comprising a membrane for filtering out pathogens present in the
water, said membrane having pore sizes comparable with or smaller
than the pathogen.
22. A water purification system according to claim 1, further
comprising time release capsules for time releasing disinfection
compounds to disinfect the water.
23. A water purification system according to claim 21, wherein the
disinfection compounds are selected from the group consisting of
chlorine, bromine, iodine and combinations thereof.
24. A water purification system according to claim 21 wherein
sources of disinfection compounds are selected from the group
consisting of sodium hypochlorite, calcium hypochlorite,
bromochloro-5,5-dimethylhydantoin, trichloroisocyanuric acid,
sodium dichloroisocyanurate dihydrate,
1,3-dibromo-5,5-dimethylhydantoin, and
1,3-dichloro-5,5-dimethylhydantoin.
25. A water purification system according to claim 1 further
comprising a membrane for filtering out pathogens present in the
water and comprising time release capsules for time releasing
disinfection compounds to disinfect the water.
26. A water purification system according to claim 22 wherein the
disinfection time release capsule is a disinfection compound
embedded in a polymer matrix.
27. A water purification system according to claim 22 wherein the
disinfection compound is a halogen disinfection compound which is
encapsulated by a polymer coating and released by diffusion through
the bulk of the coating.
28. A water purification system according to claim 22 wherein the
disinfection compound in a slow dissolving non-polymer matrix which
permits consistent release over time due to fixed solubility of the
host material.
29. A water purification system according to claim 1 having a
system for arsenic removal with a hydraulic loading rate of below
2.5 GPM/ft2 to extend the media bed lifetime.
30. A water purification system according to claim 1, comprising a
small pore membrane filter having a surface area greater than that
of a flat sheet through pleating or bundling of fibers.
31. Method according to claim 19 further comprising addition of
disinfection compounds at a first higher level to achieve
disinfection, and then removal to a second lower level prior to
ingestion by the user.
32. Method according to claim 19, wherein addition of disinfection
compounds is effected via a polymer matrix where the polymer matrix
is ethylene vinyl acetate.
33. Method according to claim 19 further comprising addition of
beneficial compounds in a time release form such that they are not
removed by the filter by proper selection of media.
34. Method according to claim 19 wherein beneficial compounds are
introduced in the last stage of the filtration system.
35. A point of use water purification system comprising: at least
one filtration media to remove a contaminant or improve water
quality; and time release capsules for continuously introducing
flavor or a therapeutic substance into the water.
36. A point of use water purification system comprising at least
one filtration media to remove a contaminant or improve water
quality comprising time release capsules for time releasing
disinfection compounds to disinfect the water.
37. A water purification system according to claim 37, wherein the
disinfection compounds are selected from the group consisting of
chlorine, bromine, iodine and combinations thereof.
38. A water purification system according to claim 38, wherein
sources of disinfection compounds are selected from the group
consisting of sodium hypochlorite, calcium hypochlorite,
bromochloro-5,5-dimethylhydantoin, trichloroisocyanuric acid,
sodium dichloroisocyanurate dihydrate,
1,3-dibromo-5,5-dimethylhydantoin, and
1,3-dichloro-5,5-dimethylhydantoin.
39. A point of use water purification system comprising at least
one filtration media to remove a contaminant or improve water
quality comprising a membrane for filtering out pathogens present
in the water and comprising time release capsules for time
releasing disinfection compounds to disinfect the water.
40. A water purification system according to claim 37 wherein the
disinfection time release capsule is a disinfection compound
embedded in a polymer matrix.
41. A water purification system according to claim 37 wherein the
halogen disinfection compound is encapsulated by a polymer coating
and released by diffusion through the bulk of the coating.
42. A water purification system according to claim 37 wherein the
disinfection compound is in a slow dissolving non-polymer matrix
which permits consistent release over time due to fixed solubility
of the host material.
43. A point of use water purification system with at least one
adsorption filtration media to remove arsenic with a hydraulic
loading rate of below 2.5 GPM/ft2 to extend the media bed
lifetime.
44. A point of use water purification system with at least one
adsorption filtration media to remove arsenic, comprising a small
pore membrane filter having a surface area greater than that of a
flat sheet through pleating or bundling of fibers.
45. Method according to claim 37 further comprising addition of
disinfection compounds at a first higher level to achieve
disinfection, and then removal to a second lower level prior to
ingestion by the user.
46. A point of use water purification system with at least one
filtration media to remove a contaminant or improve water quality,
wherein addition of disinfection compounds is effected via a
polymer matrix where the polymer matrix is ethylene vinyl
acetate.
47. A point of use water purification system with at least one
filtration media to remove a contaminant or improve water quality
further comprising addition of beneficial compounds in a time
release form such that they are not removed by the filter by proper
selection of media.
48. A point of use water purification system with at least one
filtration media to remove a contaminant or improve water quality
wherein beneficial compounds are introduced in the last stage of
the filtration system.
Description
[0001] The present invention relates to a low-cost potable water
purification system and a sensor to alert the user when the water
is no longer safe to drink. This low-cost water purification system
incorporates additional functionality that enables beneficial
impurities and molecules to be added to the water.
BACKGROUND OF THE INVENTION
[0002] Water purification systems can be comprised of many
different components using various mechanisms for removing
impurities from water. One class of prior water purification
systems is commonly referred to as `point-of-use` (POU) water
purification systems. Such POU systems are composed of components
that remove water impurities on a relatively small scale, e.g. a
table-top or dwelling-oriented system as opposed to a large central
facility, like a municipal water treatment facility.
[0003] POU systems in general have been constructed for high-end
marketplaces, i.e., markets where higher costs in POU systems can
be tolerated. POU systems have not effectively penetrated large but
lower-end marketplaces due to the lack of inventive design in
low-cost environments.
[0004] A typical POU system may have a pre-filter to remove
sediment, followed by mechanisms that ensure pathogen and sometimes
inorganic material removal. One of the most important aspects of a
POU system which contains consumables, such as filters, is an
`end-point` detection system that warns user or service personnel
that the time to change the filter has arrived. Most POU systems
use a time-based system where, after a certain amount of time has
passed, a light turns on (or some other indicator) which signals
that it is time to change the filter. This relatively low cost
sensor is not adequate. If the water purification system is
deployed in different environments, the required length of time
between filter changes to avoid contamination can vary greatly,
thus possibly exposing individuals to contaminated water.
[0005] The main method of determining water composition (and
safety) is to periodically take samples of the water and ship these
samples to a laboratory where relatively complex equipment is used
to analyze the water composition. This information supplies
feedback to the user or service personnel of what is in the water.
In addition, there are field-kits which can test for particular
contaminates, e.g. chlorine. Generally, neither of these
standardized test methods is either universal enough or compatible
with a POU water system. Likewise, neither of these test methods is
consumer friendly.
[0006] Current POU water purification systems do not add beneficial
ingredients to the water. Typical systems that impart molecules or
compounds into water are found in the confectionary or restaurant
businesses. A soda fountain, for example, adds molecules and
compounds that add flavor to carbonated water by simply mixing
streams of liquids, but not ingredients beneficial to the consumers
health.
[0007] A need exists for an improved system for purifying water
and/or adding beneficial ingredients to the water. The present
invention seeks to satisfy this need.
SUMMARY OF THE INVENTION
[0008] In one aspect, there is provided a water purification system
comprising at least two filtration media sized with respect to each
other to allow a first contaminant in the water to saturate the
first medium with a delay prior to saturation of the second medium
with a second contaminant. In another aspect, there is provided a
method of purifying water comprising passing water through a system
comprising at least two filtration media sized with respect to each
other to allow a first contaminant in the water to saturate the
first medium with a delay prior to saturation of the second medium
with a second contaminant.
[0009] An important aspect of the present system is to employ the
user of the system as the end-point detector prior to being exposed
to pathogens or other dangerous elements. This aspect of the system
allows for the ultimate in low-cost water purification and water
safety. The present inventive system employs the user as a detector
through the user's sight or taste. A mechanism in the water
purification system releases a color element when the water filter
has reached or is beginning to reach the end of its life.
Additionally the system also has the ability to release a different
taste in the water which also can alert the user that the filter
has reached its end of life. In addition, since these detection
mechanisms are introduced in a low-cost manner, the same mechanisms
can be utilized to impart desired molecules or compounds into
purified water, thus creating healthy beverages and/or therapeutic
drinks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic of a first embodiment of the present
invention showing a low-cost arsenic purification system;
[0011] FIG. 2 illustrates how taste removal media breaks through
first and the water will possess an undesirable musty or earthy
taste for some time period of delay before the water begins to be
contaminated with arsenic;
[0012] FIG. 3 illustrates how time release capsules can release
taste substances at a constant rate which is absorbed by a
downstream media and saturates the media at the right time;
[0013] FIG. 4 illustrates how time release capsules are engineered
into abrupt-release form which are located in this case at the end
of the purification system;
[0014] FIG. 5 illustrates time-release capsules designed to inject
an even dose of flavor over time;
[0015] FIG. 6 illustrates a time-release capsule designed so that
the outer shell dissolves at a rate such that the flavor is
released as abruptly as possible when the arsenic media is about to
expire;
[0016] FIGS. 7 and 8 show arsenic removal results of the
combination AC/GFO filter on Chapala water over the lifetime of the
filter;
[0017] FIG. 9 is a second embodiment where the timed release media
is situated before the filter media;
[0018] FIG. 10 is a third embodiment where the timed release media
is situated after the filter media; and
[0019] FIG. 11 is a fourth embodiment where the timed release media
are situated before and after the filter media.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Referring to the drawings, FIG. 1 is a schematic of a first
embodiment of the present invention of a low-cost arsenic
purification system. The system 2 comprises a reservoir 4 for
containing water to be purified connected via a valve 8 to a filter
region 10 having a series of remediation medias 12,14,16. Water
passing through the filter region 10 exits through nozzle 18 via
valve 20 into receiving vessel 22.
[0021] The prefilter 12 is designed to eliminate large particles
and sediment from the water. The pre-filter 12 is followed by a
series filter medias which are designed to remove targeted atoms,
molecules, or compounds from the water and/or may be employed to
impart either a color or taste change to the water when the media
are saturated with contaminates and the media is no longer
purifying the water (i.e., the invention indicates that the water
will soon be unsafe). In the particular embodiment illustrated in
FIG. 1, the prefilter media 12 is followed by a taste removal media
14, and an arsenic removal media 16.
[0022] Similar mechanisms can be employed to inject other
beneficial compounds into the water. Beneficial compounds can be,
for example, vitamins, amino acids, minerals, and/or herbal
extracts. Some examples include vitamin A, vitamin C, vitamin D,
and vitamin E, vitamin K, vitamin B.sub.6, vitamin B.sub.12,
thiamin, riboflavin, niacin, folic acid, biotin, pantothenic acid,
calcium, iron, phosphorus, iodine, magnesium, zinc, selenium,
copper, manganese, chromium, molybdenum, potassium, boron, nickel,
silicon, tin, vanadium, lutein, and lycopene.
[0023] The system of the invention is primarily designed for
treatment of water which has been disinfected with chlorine. As
noted above, one of the remediation medias 14 may be designed to
remove undesirable tastes, and the other 16 may be chosen to remove
arsenic.
[0024] Different geographical areas may have different water
problems and, hence, may require adjustment of the media types,
number of medias, or media ratios to properly remove contaminants.
The filter system is designed with an appropriate empty bed contact
time (EBCT) for each of the medias to allow sufficient removal of
the target contaminants. Typical EBCTs are on the order of 1 to 10
minutes, and these guidelines determine water flow rates through
the media filter volume.
[0025] The purification system may include additional filter stages
after the remediation medias described above (not shown). For
example, a filter to remove media fines (such as a fiber wound
filter) and/or a filter to remove microbial contaminants may be
implemented after the remediation media stages. Common causes of
water taste problems are algal metabolites such as geosmin, or 2
methylisoborneol (MIB) which impart musty or earthy tastes to the
water. (See for example, chapter 26 in Adsorption by Carbon, edited
by Bottani and Tascon). Although the order of the media in the
present system is not critical, in the embodiment illustrated in
FIG. 1, the taste removal filter media 14 is positioned immediately
following the prefilter media 12, followed by the arsenic removal
media 16.
[0026] In other embodiments, the medias may be intermixed,
alternating, or stacked. Additionally, although there are other
potential media that can perform both tasks described above,
activated carbon (also referred to as activated charcoal) is
typically selected as the taste removal filter media 14, and one or
more of granular ferric hydroxide, activated alumina, granular
ferric oxide, titanium oxide, zirconium oxide, or another metal
oxide or mixture of metal oxides may be selected as the arsenic
removal media 16.
[0027] The design of the system of the invention is very low cost
for two principal reasons. First, the system is targeted at the two
primary problems arising with the water, namely the toxic arsenic
concentration and the undesirable taste. Secondly, the method of
end-point-detection is either time, or more importantly, taste. The
system is able to employ user taste as an end-point detection
mechanism by sizing the taste-removal media and the arsenic-removal
media such that the taste-removal media is saturated before the
arsenic-removal media is saturated. When these media volumes are
sized as described, the taste removal media breaks through first,
and the water will possess an undesirable musty or earthy taste for
some time period of delay before the water begins to be
contaminated with arsenic.
[0028] This effect is represented schematically in the graph shown
in FIG. 2. The sizing of the volume media to arrive at this
functional effect, in which the user is the sensor since the user
is signaled to replace the media when an earthy or musty taste is
sensed in the water, is accomplished in a series of steps as
described below.
[0029] First, the local water is measured to determine the level of
taste imparting compounds such as geosmin or MIB and the level of
arsenic in the water. Secondly, the taste and arsenic removal media
is tested to determine how long it will take a volume of media to
be saturated with geosmin and/or MIB or arsenic. Once this second
step is complete, volumes of the media in the system can be chosen
to achieve the effect shown in FIG. 2.
[0030] For example, a two component POU filter can be constructed
with activated carbon for taste improvement and granular ferric
oxide (GFO) for arsenic removal. By appropriately sizing the
medias, the taste improvement serves the function of an early
warning system for the user that it is time to replace the filter.
The relevant parameters are the media adsorption capacities for
target contaminants, typically listed in mg contaminant adsorbed
per gram of media. The adsorption capacity of MIB on activated
carbon is in the range of 1 to 3 mg/g, depending on activated
carbon structure (carbon containing source material, pore size
distribution, and surface area), and water chemistry. (See for
example, Chapter 26 in Adsorption by Carbon, edited by Bottani and
Tascon, p. 683, (2008)). Similarly, the adsorption capacity of
arsenic (V) on GFO is in the range of 0.5 to 1 mg/g depending on
water chemistry. (Reference, Adsorption Treatment Technologies for
Arsenic Removal, AWWA publishing, Chapter 6, (2005)).
[0031] A suitable activated carbon can be obtained from Calgon
Carbon Corporation
(http://www.calgoncarbon.com/solutions/?view=ChallengeProducts&Industry=1-
0&Application=7&Challenge=7). Similarly GFO can be obtained
from Severnt Trent
Corporation.(http://severntrentservices.com/Water_Wastewater_Treatm-
ent/Arsenic_Removal_prod.sub.--52.aspx).
[0032] For example, it is assumed that, in the input water, MIB and
arsenic (V) concentrations are both 0.05 mg/L, and further it is
assumed that the adsorption capacity of both contaminants on their
respective removal medias is 1 mg/g. Neither GFO nor AC has
appreciable adsorption capacity for the other contaminant. Thus, to
design a filter where MIB breaks through the activated carbon prior
to arsenic break through in the GFO requires a GFO to carbon ratio
greater than 1. Suitable ratios could be 2:1=mass GFO:mass
activated carbon. Such a ratio would result in an undesirable taste
notification to the user that it is time to replace the filter
prior to the user being exposed to elevated levels of arsenic. Of
course, the overall media masses (and hence filter volume) must be
chosen appropriately for the intended water flowrate and filter
lifetime. If the concentration of geosmin or MIB is not large
enough, the saturation is not abrupt enough, or another suitable
taste imparting compound is not present in the water, the method
described above cannot be used as an end-point-detection
sensor.
[0033] If a constant rate of a taste compound is added outside the
POU system, the invention has a similar design as shown in FIG. 1
since the geosmin or MIB taste removal media is replaced with a
media that removes the intentionally introduced taste compound.
Alternatively, the taste substance or compound may be added within
the POU system by employing time-release capsules.
[0034] FIG. 3 shows a system similar to that shown in FIG. 1 except
that a region 24 is provided downstream of the taste removal media
14 containing capsules adding constant rate release of taste
substances. These time release capsules can either release taste
substances at a constant rate which is absorbed by a downstream
media and saturates the media at the right time (as seen in FIG.
3), or the capsules may be engineered into abrupt-release form 26
which are located in this case at the end of the purification
system as the last stage (see FIG. 4). In the first case
(continuous), the time-release capsules (see FIG. 5) are designed
to inject an even dose of flavor over time. In the capsule shown in
FIG. 6, this is designed so that the outer shell dissolves at a
rate such that the flavor is released as abruptly as possible when
the arsenic media is about to expire.
[0035] The inventive time-release capsules used in the water
purification system of the invention can also be used to release
color either in addition to or instead of taste. For example, both
methods described above for flavor release can be used for color
release. In the first case, the constant-rate-release time capsule
can be used to release a color that is absorbed by one of the media
in a filter system, and the saturation is planned such that the
color compound achieves saturation in the media just before a
purification media becomes saturated with an undesirable atom,
molecule, or compound(s) which is being removed. Thus, the water
will change color when it is time to replace the purification
media. A time delay is designed into this system as well, so that
even though the water changes color, the water is still safe for
some delay time. The delay is designed by understanding the
saturation rate of the color compound concentration released by the
time-release capsule as well as the saturation of the undesirable
atom, molecule, or compound that is being removed.
[0036] An abrupt-time-release time capsule can be used as well to
impart color in the water to indicate that it is time to replace
the purification media. In this embodiment, the outer shell of the
time release capsule dissolves at a rate such that color is
released abruptly just before the purification media is saturated
with the atom, molecule, or compound that it is removing from the
water.
[0037] The time-release capsules described herein are also useful
in adding desirable atoms, molecules, or compounds to the water.
The constant-rate time capsules described previously are desirable
for this beneficial release. The capsules are loaded into a media,
or separately, located at the last stage of the water purification
system (so that other media do not remove the desired beneficial
atoms, molecules, or compounds). Flavors can be released by these
capsules, as well as therapeutic substances such as vitamins.
[0038] A key aspect of the invention is the recognition that local
water conditions must be carefully assessed in order to choose the
most appropriate, lowest cost media for optimum arsenic POU removal
with sufficient longevity to produce potable water in amounts
suitable for a household. For example, in one particular location,
testing determined that the chlorine content, arsenic valence, and
pH would need to be primarily considered when choosing the most
appropriate arsenic removal media. Likewise, the ratios of the
media in the filtration system would have to be adjusted based on
the water characteristics and desired longevity and quality of the
water post-filtration. Chlorine neutralization requires activated
carbon (AC), while arsenic removal requires a metal oxide media
such as GFO. In the example above, GFO media was chosen because it
exhibits superior As(V) removal at the elevated pHs present in the
local water supply compared to other metal oxide medias such as
activated alumina. (Reference, Adsorption Treatment Technologies
for Arsenic Removal,AWWA publishing, Chapter 6, (2005)).
[0039] To minimize plumbing connections and reduce unit assembly
cost, the medias were combined in a single standard filter housing.
It was estimated that 550 g of GFO (1.1 dry liters) would give
sufficient arsenic removal capacity under local water conditions to
achieve the designed filter lifetime of 7,000 liters. The overall
filter volume was fixed to that of a standard 130 cc filter element
in the POU device. It was determined that the element containing
1.1 L of GFO and 1.1 L of AC, in a 1:1 media ratio by volume worked
best for the conditions present in the example.
[0040] Following the above described process, the media ratios can
be adjusted without undue experimentation once the local water
characteristics have been assessed. The medias formed two distinct
layers, and water flowed through the AC prior to the GFO. FIGS. 7
and 8 show arsenic removal results of the combination AC/GFO filter
on Chapala water over the lifetime of the filter. Arsenic is
maintained below the 0.01 mg/L limit during the test. In addition,
chlorine was not detected in the treated water, resulting in
pleasing taste to local residents. Depending on the local water
quality factors, POU filter size, and designed operational lifetime
the ratios of GFO to AC may be adjusted as required. For small
filter sizes present in POU devices, it is expected that proper
ratios of GFO arsenic removal media to activated carbon would be
approximately 1:1=volume of GFO:volume AC or larger such as 2:1.
These volumes should be adjusted for the arsenic removal capacities
and densities of different medias appropriate for the local water
conditions. Additional medias may be added to the filter elements
to remove other water contaminants as required resulting in
elements with 3, 4, or more media components. The individual medias
may be separated (i.e., layered) as in the above example, or they
may be intermixed.
[0041] FIGS. 9-11 illustrate further embodiments where the timed
release media is situated before, after or before and after the
filter media. In FIG. 9, the timed release media is situated
upstream of the filter media and may consist of, for example,
beads, capsules or films 30, such as disinfection capsules,
pellets, beads, and /or films. Water 32 enters at the top 34 and
exits at the bottom 36. The filter may operate under gravity fed
conditions or may function under water pressure. Medias 1 and 2 are
shown for illustrative purposes but are not limited to two medias,
and may range from 1 to N medias, where N is, for example, 1-10.
The medias may target, for example, taste improvement, removal of
disinfection parent compound, neutralization of disinfection agent
after a suitable contact time as required for disinfection, and
arsenic removal.
[0042] The embodiment of FIG. 10 is similar to that illustrated in
FIG. 9, except that the timed release media is situated after the
filter media. In this embodiment, the timed release capsules 38 may
contain beneficial nutrients such as vitamins, herbal extracts,
fruit and/or vegetable extracts and/or tastes, pharmaceuticals
and/or neutraceuticals.
[0043] The embodiment shown in FIG. 11 is similar to those
discussed above with respect to FIGS. 9 and 10 except that the
timed release media are situated before and after the filter media.
In the embodiment of FIG. 11, the upstream capsules may consist of
timed release media, for example beads, capsules and/or films 30,
such as disinfection capsules, pellets, beads, and/or films, and
the downstream timed release capsules 38 may contain beneficial
nutrients such as vitamins, herbal extracts, fruit and/or vegetable
extracts and/or tastes, pharmaceuticals and/or neutraceuticals.
[0044] In addition to the users' sense of taste and sight, the
sense of smell may be used to alert the user to a change in filter
performance. For example, in one approach, the user could assess
filter performance by detection of chlorine by smell or taste.
Activated carbon media could be employed to remove the chlorine
which is present in the incoming water after addition in a central
treatment plant, or by chlorine addition by the POU device through
a time release mechanism. The activated carbon bed would be
properly sized such that it saturates prior to saturation of the
contaminant bed which is removing arsenic. Once the activated
carbon was saturated, the chlorine concentration would increase in
the filtered water. This increase in chlorine concentration could
be detected by the user through smell or taste. Similarly, this
activated carbon bed could be replaced with an activated carbon
impregnated membrane, or a copper-zinc (brass) alloy media such as
KDF, produced by KDF Fluid Treatment.
[0045] The POU system of the invention may be employed in a variety
of locations and water conditions. Some water conditions may have
inadequate or nonexistent disinfection capabilities such as by
chlorine disinfection. This may occur due to inadequate
chlorination infrastructure, or because of a disruption of the
central treatment disinfection process after a natural disaster or
supply pipe rupture. The POU system of the present invention
possesses disinfection capability which may be implemented several
ways.
[0046] In one way, a membrane is provided which mechanically
filters out pathogens. This requires use of a membrane with pore
sizes comparable and preferentially smaller than the pathogen. In
addition, a very tortuous path can be implemented in a filter to
trap pathogens when the pore size is larger than the pathogen.
Further trapping improvements can occur by the embedding of
materials such as activated alumina in the membrane which exhibit
surface charges when in water. These surface charges can
electrostatically bind viruses and bacteria, resulting in increased
capture than would be expected based solely on mechanical pore size
measurements.
[0047] In another approach disinfection compounds which are
beneficial to the user can be added through controlled, time
release methods to actively disinfect the water, performing a
benefit to the user. The POU filter system of the invention has
either or a combination of both approaches.
[0048] For the membrane pathogen approach, the system integrates
small pore size filters with large surface areas to overcome the
limitation of reasonable flows at low water pressures such as
gravity fed applications. To mechanically remove protozoan cysts
requires membranes with pore sizes on the order of 1 micron, while
bacteria require pore sizes on the order of 0.1 micron. The flow of
water through a membrane with 0.1 micron pore size is very slow,
typically on the order of 1 milli liter per min per cm2 of membrane
area. This is too slow to filter a reasonable amount of water under
gravity. This area limitation is overcome by the present invention
utilizing two different approaches.
[0049] In the first approach, the common circular geometries are
replaced by the use a rectangular or square filter shape to allow
pleating and thus increase the filter area and flow. Using
pleating, it is possible to increase filter area by a factor of 10
if 1 inch deep pleats and 5 pleats per inch are used. This larger
increase in area allows the practical introduction of small pore
size filters such as 0.1 micron filters in a gravity fed POU
application. Circular geometries are not easily amenable to
pleating, hence the need for a square or rectangular geometry.
Thus, in one embodiment, the POU system of the invention combines
time release of a halogen disinfectant with a small pore membrane
filter which has a surface area greater than that of a flat sheet
through pleating or bundling of fibers. In another embodiment, the
POU system of the invention combines a small pore membrane filter
which is has a surface area greater than that of a flat sheet
through pleating or bundling of fibers along with arsenic removal
media and has a resulting flow greater than 100 mL/min under
gravity fed conditions.
[0050] In a second approach, hollow fiber filters are used which
are combined strands of filter fibers, greatly increasing the
surface area for water transport. Using hydrophilic materials such
as PES allows wetting of the hollow fiber filters and operation
under gravity fed conditions at 0.1 micron pore sizes. The above
approach does not kill pathogens, but establishes a mechanical
barrier through membrane pores to eliminate them.
[0051] The inventive time-release capsules used in the water
purification system of the invention can also be used to release
beneficial disinfection compounds in addition to vitamins, herbal
extracts, etc. The present invention describes time release methods
to actively disinfect the water and kill all types of pathogens
from viruses to bacteria to cysts which have advantages over
membrane only approaches. This approach may be combined with the
membrane approach above, and would be preferred to offer a
multi-faceted defense for microorganisms and to eliminate cysts
which are resistant to chlorination.
[0052] The beneficial disinfection compounds are typically
halogen-containing compounds, comprising chlorine, bromine, and/or
iodine groups. Disinfection efficacy is predicted by CT products,
where C is the concentration of free halogen (such as free chlorine
in mg/L) and T is the contact time in min. The EPA publishes
guidelines for pathogen disinfection for different CT products and
pathogens as can be found in the following reference (US EPA,
Guidance manual for compliance with the filtration and disinfection
requirements for public water systems using surface water systems,
1989). Some potential disinfection compounds which could be
released to create free halogen compounds are sodium hypochlorite,
calcium hypochlorite, bromochloro-5,5-dimethylhydantoin,
trichloroisocyanuric acid, sodium dichloroisocyanurate dihydrate,
1,3-dibromo-5,5-dimethylhydantoin, and/or
1,3-dichloro-5,5-dimethylhydantoin among others. The requirement is
that the sources be liquid or solid, with solid being
preferred.
[0053] The issue is a controlled release of these potentially
dangerous chemicals in a prescribed dosage range over the lifetime
of the filter. Too low a concentration results in incomplete
disinfection, while too much results in offensive tastes and odors
and potential end user harm. Typically, for free chlorine, levels
are desired in the range of about 0.2 mg/L to 10 mg/L, with 0.5
mg/L to 5 mg/L being preferred. With those levels of free chlorine
a majority of viruses and bacteria are inactivated (99.99%) in
approximately 10 minutes according to the EPA reference above.
[0054] In industrial settings such as centralized water treatment
facilities, this controlled release is achieved through close
monitoring and testing of mechanical dosage pumps and the resulting
chlorine levels. This level of automation and oversight is not
practical in a home POU device. Instead, the invention employs a
matrix or coating to hold the disinfection compound and time
release it controllably over time into the POU reservoir without
user intervention. This controlled release system achieves the
required disinfection chemical concentration without input or
monitoring by the user safely and controllably. These time release
disinfection materials would exhibit sanitizing or biocidal
properties to kill pathogens.
[0055] Release mechanisms may be grouped into reservoir-type
systems with a delivery device where an inert membrane shell
surrounds an active agent which upon activation diffuses through
the membrane at a finite controllable rate, and matrix systems
which have microparticles prepared by extrusion or molding of
polymers or fat-congealed capsules where the actives are dispersed
in the encapsulating medium (carbohydrate, fat, etc.) A combination
release mechanism which is a combination of the reservoir-type and
matrix systems is also possible.
[0056] In a preferred embodiment, the disinfection time release
capsule may be formed by embedding the disinfection compound in a
polymer matrix, preferably such that the disinfection compound is
homogeneously distributed throughout the matrix. The polymer matrix
may be in the form of a sheet, tablet, or hemisphere.
[0057] This matrix approach is also suitable to other beneficial
compounds such as vitamins, minerals, and herbal extracts. The
polymer may be chosen from ethylene vinyl acetate, low or high
density polyethylene, polypropylene, polystyrene, or silicone among
others. These polymers should all be food contact grade. The
fabrication parameters of these polymers such as molding
temperature should be chosen such that they do not result in a
major degradation of the beneficial compound.
[0058] In a preferred embodiment, the polymer is ethylene vinyl
acetate and the chlorine source is calcium hypochlorite. The
controlled release of the halogen compound is tailored through
choice of the chlorine source, the polymer, the chlorine source to
polymer ratio, the size of the chlorine source particles, and the
method of manufacture which would control the homogeneity of the
resulting matrix. The polymer matrix should be more than 10%
chlorine source by weight, but less than 90% chlorine source by
weight. The result could be a tablet, capsule, hemisphere or sheet
which releases the disinfection compound controllably into the
filter system to disinfect the water over time. The use of the
matrix geometry and any barrier coating is important to control the
release rate.
[0059] In another embodiment, the halogen disinfection compound is
encapsulated by a polymer coating and released by diffusion through
the bulk of the coating or shell. Alternatively, the disinfection
compound may be embedded in a slow dissolving non-polymer matrix to
allow consistent release over time due to the fixed solubility of
the host material. This slow release matrix or coating may be a
wax, carbohydrate, cellulose, or hydrogel.
[0060] The water may be chlorinated to a higher level to kill the
pathogens and then the chlorine level can be reduced to a level
which is not objectionable to user taste or smell through use of a
second media bed such as activated carbon. This controlled release
of disinfection compound can serve to protect the user from
pathogens as well as alert the user that the arsenic or other media
is reaching its useful life and needs to be replaced.
[0061] In this scheme, the controlled release of the disinfection
compound would need to function longer than the lifetime of the
removal media. In addition, it may be required to remove the parent
chlorine compound in addition to the free chlorine by proper choice
of media.
[0062] In addition the above, beneficial compounds introduced may
interfere with and be removed by the filtration media. In the above
chlorination example, this is desirable. However, in the case of
some beneficial compounds such as vitamins, it would be
advantageous to allow the beneficial compounds to be released into
the water without uptake by the filter. This can be achieved by
properly choosing the media order and introduction point for the
beneficial compounds.
[0063] According to a further embodiment, the invention provides a
water purification system as described above which has a membrane
for filtering out pathogens present in the water. To this end, the
membrane has pore sizes comparable with or smaller than the
pathogen. Alternatively, the system of the invention contains time
release capsules for time releasing disinfection compounds to
disinfect the water. The disinfection compounds are typically
selected from chlorine, bromine, iodine and combinations thereof.
Sources of disinfection compounds may be chosen sodium
hypochlorite, calcium hypochlorite,
bromochloro-5,5-dimethylhydantoin, trichloroisocyanuric acid,
sodium dichloroisocyanurate dihydrate,
1,3-dibromo-5,5-dimethylhydantoin, and
1,3-dichloro-5,5-dimethylhydantoin. The system of the invention may
further include a membrane for filtering out pathogens present in
the water and comprising time release capsules for time releasing
disinfection compounds to disinfect the water. In one embodiment,
the disinfection time release capsule may consist of a disinfection
compound embedded in a polymer matrix, for example a halogen
disinfection compound encapsulated by a polymer coating and
released by diffusion through the bulk of the coating. The
disinfection compound may for example be contained within a slow
dissolving non-polymer matrix which permits consistent release over
time due to fixed solubility of the host material.
[0064] In another embodiment, there is provided a system for
removing arsenic with a hydraulic loading rate of below 2.5 GPM/ft2
to extend the media bed lifetime.
[0065] In another embodiment, the water purification system of the
invention has a small pore membrane filter with a surface area
greater than that of a flat sheet through pleating or bundling of
fibers.
[0066] The method of the invention may be carried out by addition
of disinfection compounds at a first higher level to achieve
disinfection, and then removal to a second lower level prior to
ingestion by the user. In this regard, the addition of disinfection
compounds may be effected via a polymer matrix where the polymer
matrix is ethylene vinyl acetate, and the beneficial compounds may
be added in a time release form such that they are not removed by
the filter by proper selection of media. In a preferred embodiment,
the beneficial compounds are introduced in the last stage of the
filtration system.
[0067] According to another embodiment, there is provided a point
of use water purification system comprising at least one filtration
media to remove a contaminant or improve water quality and time
release capsules for continuously introducing flavor or a
therapeutic substance into the water.
[0068] In another embodiment, there is provided a point of use
water purification system comprising at least one filtration media
to remove a contaminant or improve water quality comprising time
release capsules for time releasing disinfection compounds to
disinfect the water. The disinfection compounds are typically
selected from chlorine, bromine, iodine and combinations thereof.
Sources of disinfection compounds may be sodium hypochlorite,
calcium hypochlorite, bromochloro-5,5-dimethylhydantoin,
trichloroisocyanuric acid, sodium dichloroisocyanurate dihydrate,
1,3-dibromo-5,5-dimethylhydantoin, and/or
1,3-dichloro-5,5-dimethylhydantoin.
[0069] The point of use water purification system may comprise at
least one filtration media to remove a contaminant or improve water
quality comprising a membrane for filtering out pathogens present
in the water and comprising time release capsules for time
releasing disinfection compounds to disinfect the water. The
disinfection time release capsule is typically a disinfection
compound embedded in a polymer matrix. The halogen disinfection
compound is usually encapsulated by a polymer coating and released
by diffusion through the bulk of the coating. Alternatively, the
disinfection compound is present in a slow dissolving non-polymer
matrix which permits consistent release over time due to fixed
solubility of the host material.
[0070] In another embodiment, the point of use water purification
system is provided with at least one adsorption filtration media to
remove arsenic with a hydraulic loading rate of below 2.5 GPM/ft2
to extend the media bed lifetime.
[0071] A further embodiment provides a point of use water
purification system with at least one adsorption filtration media
to remove arsenic, comprising a small pore membrane filter having a
surface area greater than that of a flat sheet through pleating or
bundling of fibers.
[0072] The method is typically carried out by adding disinfection
compounds at a first higher level to achieve disinfection, and then
removal to a second lower level prior to ingestion by the user.
[0073] The invention also provides a point of use water
purification system with at least one filtration media to remove a
contaminant or improve water quality, in which addition of
disinfection compounds is effected via a polymer matrix where the
polymer matrix is ethylene vinyl acetate.
[0074] The invention further provides a point of use water
purification system with at least one filtration media to remove a
contaminant or improve water quality further comprising addition of
beneficial compounds in a time release form such that they are not
removed by the filter by proper selection of media. The point of
use water purification system preferably has at least one
filtration media to remove a contaminant or improve water quality
wherein beneficial compounds are introduced in the last stage of
the filtration system.
[0075] For example, many organic compounds are removed by activated
carbon. If beneficial compounds are to be introduced, it would be
advantageous to introduce them after the activated carbon stage in
the filter, preferably at the last stage so that there is no
interference or uptake by the filter.
[0076] To maximize arsenic media life requires proper choice of
media and flow conditions. It has been discovered that the
hydraulic loading rate has a large effect on media bed lifetime,
with lower hydraulic loading rates being advantageous. The present
invention provides in one embodiment larger diameter vessels to
offset the lower hydraulic loading rates to achieve reasonable
flows. Typical media parameters for hydraulic loading from vendors
are 8 gpm/ft2.
[0077] Based on testing, it has been discovered that lifetime may
be dramatically extended by operating filters at much lower
hydraulic loadings below 4 gpm/ft2, preferably below 2.5 gpm/ft2.
To achieve reasonable flow rates, custom filters were designed that
have diameters 5 inches and larger. This approach works with all
metal oxide and hydroxide medias including rare earth materials,
such as granular ferric hydroxide, activated alumina, granular
ferric oxide, titanium oxide, zirconium oxide, cerium oxide,
hafnium oxide, lanthanum oxide or another metal oxide or
mixtures.
[0078] In another embodiment, the beneficial disinfection compounds
are added at a first higher level to achieve disinfection, and then
removed to a second lower level prior to ingestion by the user.
[0079] In a further embodiment, beneficial compounds such as
flavors, vitamins, nutrients, etc., are added in a time release
form so that they are not removed by the filter by proper selection
of media. In a first alternative, the beneficial compounds are
introduced in the last stage of the filtration system. In a second
alternative, the beneficial compounds (flavors, vitamins,
nutrients, etc.) are introduced in a time-release form after the
water passes through the filter system, in a reservoir or
equivalent.
[0080] A yet further embodiment comprises determination by the user
of filtration saturation through the use of taste, smell, or
appearance and proper sizing of at least 2 medias, one of which
removes a harmful contaminant.
[0081] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *
References