U.S. patent application number 10/712621 was filed with the patent office on 2005-05-19 for water treatment system and method.
This patent application is currently assigned to United States Filter Corporation. Invention is credited to Freydina, Evgeniya, Jha, Anil D., Madhusudan, Reshma, Reardon, Michael, Sezgi, Aytac, Wilkins, Frederick.
Application Number | 20050103717 10/712621 |
Document ID | / |
Family ID | 34573582 |
Filed Date | 2005-05-19 |
United States Patent
Application |
20050103717 |
Kind Code |
A1 |
Jha, Anil D. ; et
al. |
May 19, 2005 |
Water treatment system and method
Abstract
A water treatment system provides treated water to a point of
use by removing at least a portion of any hardness-causing species
contained in water from a water source, such as municipal water,
well water, brackish water and water containing foulants. The water
treatment system typically receives water from the water source or
a point of entry and purifies the water containing at least some
undesirable species before delivering the treated water to a point
of use. The water treatment system has a pressurized reservoir
system in line with an electrochemical device such as an
electrodeionization device. The water treatment system can have a
controller for adjusting or regulating at least one operating
parameter of the treatment system or a component of the water
treatment system.
Inventors: |
Jha, Anil D.; (Lincoln,
MA) ; Wilkins, Frederick; (Pepperell, MA) ;
Freydina, Evgeniya; (Acton, MA) ; Sezgi, Aytac;
(Bedford, NH) ; Madhusudan, Reshma; (Arlington
Heights, IL) ; Reardon, Michael; (Barrington,
IL) |
Correspondence
Address: |
LOWRIE, LANDO & ANASTASI
RIVERFRONT OFFICE
ONE MAIN STREET, ELEVENTH FLOOR
CAMBRIDGE
MA
02142
US
|
Assignee: |
United States Filter
Corporation
40-004 Cook Street
Palm Desert
CA
92211
|
Family ID: |
34573582 |
Appl. No.: |
10/712621 |
Filed: |
November 13, 2003 |
Current U.S.
Class: |
210/652 ;
210/243; 210/257.2; 210/85; 210/96.2 |
Current CPC
Class: |
C02F 2209/40 20130101;
C02F 1/46 20130101; C02F 5/00 20130101; C02F 2209/00 20130101; C02F
2209/05 20130101; C02F 2209/006 20130101; C02F 2301/066 20130101;
C02F 2209/02 20130101; B01D 61/48 20130101; C02F 2209/03 20130101;
C02F 2209/11 20130101; C02F 2209/06 20130101; C02F 1/441 20130101;
C02F 1/283 20130101 |
Class at
Publication: |
210/652 ;
210/085; 210/096.2; 210/257.2; 210/243 |
International
Class: |
B01D 061/02 |
Claims
What is claimed is:
1. A water treatment system comprising: a pressurized reservoir
system fluidly connected to a point of entry; a water treatment
device fluidly connected to the pressurized reservoir system; a
water distribution system fluidly connected to the pressurized
reservoir system; and at least one point of use fluidly connected
to the water distribution system.
2. The water treatment system of claim 1 further comprising a
pretreatment system fluidly connected upstream of the water
treatment device.
3. The water treatment system of claim 2 wherein the pretreatment
system comprises a reverse osmosis device.
4. The water treatment system of claim 3 wherein the pretreatment
system further comprises a carbon filter.
5. The water treatment system of claim 4 further comprising at
least one water property sensor.
6. The water treatment system of claim 5 wherein the water property
sensor comprises any of a conductivity sensor, a flow rate sensor,
a temperature sensor, pressure sensor, a pH sensor, a turbidity
sensor, a composition analyzer and combinations thereof.
7. The water treatment system of claim 6 further comprising a
controller for regulating an operating condition of the water
treatment system based on a measurement of the water property
sensor.
8. The water treatment system of claim 7 wherein the controller
regulates at least one of an applied current and an applied voltage
to the water treatment device.
9. The water treatment system of claim 8 further comprising a
remote communication device in communication with the
controller.
10. The water treatment system of claim 9 wherein the point of use
comprises an appliance.
11. The water treatment system of claim 7 further comprising an
algorithm in the controller capable of calculating an LSI based on
the measurement of the water property sensor.
12. The water treatment system of claim 1 wherein water in the
water storage vessel comprises chlorine.
13. The water treatment system of claim 1 further comprising a heat
exchanger thermally connected to the pressurized reservoir
system.
14. The water treatment system of claim 1 further comprising at
least one water property sensor.
15. The water treatment system of claim 1 further comprising a
controller for regulating an operating condition of the water
treatment system based on a measurement of a water property
sensor.
16. The water treatment system of claim 1 further comprising an
auxiliary use fluidly connected downstream of the water treatment
device.
17. The water treatment system of claim 1 further comprising an
irrigation system fluidly connected downstream of the water
treatment device.
18. The water treatment system of claim 1 wherein the water
distribution system is a household water distribution system.
19. The water treatment system of claim 1 wherein the treated water
has a conductivity of less than about 220 .mu.S/cm.
20. The water treatment systems of claim 1 wherein the water
treatment device comprises an electrodeionization device.
21. A treatment system comprising: a reservoir system fluidly
connected to a point of entry; an electrochemical device fluidly
connected to the reservoir system; a point of use fluidly connected
to the reservoir system; and an auxiliary use fluidly connected
downstream of the electrochemical device.
22. The treatment system of claim 21 wherein the reservoir system
is pressurized.
23. The treatment system of claim 21 further comprising a
pretreatment system fluidly connected upstream of the
electrochemical device.
24. The treatment system of claim 21 wherein the pretreatment
system comprises a reverse osmosis device.
25. The treatment system of claim 23 wherein the pretreatment
system comprises a carbon filter.
26. The treatment system of claim 21 further comprising a
controller for regulating at least one operating parameter of the
treatment system.
27. The treatment system of claim 21 wherein the point of use
comprises an appliance.
28. The treatment system of claim 21 further comprising a heat
exchanger thermally connected to the reservoir system.
29. The treatment system of claim 21 wherein the auxiliary use
comprises an irrigation system.
30. A method for treating water comprising: introducing water to a
pressurized reservoir system; transferring a portion of the water
from the pressurized reservoir system to a water treatment device;
removing at least a portion of any undesirable species from the
water from the pressurized reservoir system in the water treatment
device to produce treated water; transferring the treated water
from the water treatment device to the pressurized reservoir
system; and distributing a portion of the treated water from the
pressurized reservoir system to a point of use.
31. The method of claim 30 wherein the undesirable species is a
hardness ion species.
32. The method of claim 30 further comprising pretreating the water
before transferring the water to the water treatment device.
33. The method of claim 30 further comprising measuring any of a
water turbidity, alkalinity, composition, conductivity, pH,
pressure and temperature.
34. The method of claim 30 further comprising adjusting at least
one of an applied current and an applied voltage on the water
treatment device.
35. The method of claim 30 further comprising heating the water in
the pressurized reservoir system.
36. The method of claim 30 further comprising adjusting an
operating cycle of the water treatment device.
37. The method of claim 30 wherein the water treatment device
comprises an electrodeionization device.
38. The method of claim 30 further comprising cleaning the water
treatment device to remove or inactivate at least a portion of any
contaminant organisms.
39. The method of claim 38 wherein cleaning the water treatment
device comprises exposing at least a portion of a wetted surface of
the water treatment device to a cleaning agent.
40. A method for treating water comprising: introducing water from
a point of use to a reservoir system; removing at least a portion
of any undesirable species from the water in the reservoir system
in an electrochemical device to produce treated water and discharge
water; transferring at least a portion of the treated water from
the electrochemical device to the reservoir system; transferring a
portion of the discharge water to an auxiliary use; and
distributing a portion of the treated water from the reservoir
system to a point of use.
41. The method of claim 40 wherein the reservoir system is
pressurized.
42. The method of claim 40 wherein distributing a portion of the
treated water comprises distributing water to a household.
43. The method of claim 40 wherein transferring the discharge water
to the auxiliary use comprises transferring at least a portion of
the discharge water to an irrigation system.
44. The method of claim 40 further comprising pretreating the water
before removing the at least a portion of the any undesirable
species from the water.
45. The method of claim 40 further comprising adjusting an
operating parameter of the electrochemical device.
46. A water distribution system comprising: a first pretreatment
system fluidly connected to a point of entry; a pressurized
reservoir system fluidly connected downstream of the first
pretreatment system; a second pretreatment system fluidly connected
to the pressurized reservoir system; and an electrochemical device
fluidly connected downstream of the second pretreatment system and
to the pressurized reservoir system.
47. The distribution system of claim 46 further comprising a
controller for regulating at least one of an applied current and an
applied voltage on the electrochemical device.
48. The distribution system of claim 46 further comprising a heat
exchanger in thermal communication with the pressurized reservoir
system.
49. The distribution system of claim 46 further comprising a fluid
transfer system fluidly connected to the pressurized reservoir
system and a point of use.
50. The distribution system of claim 49 further comprising a post
treatment system fluidly connected downstream of the
electrochemical device and upstream of a point of use.
51. A water treatment system comprising: means for accumulating
water from a water source at a pressure above atmospheric pressure;
and an electrochemical device fluidly connected to the means for
accumulating water.
52. The system of claim 51 further comprising means for fluidly
delivering a portion of the water to a point of use.
53. The system of claim 51 further comprising a pretreatment system
fluidly connected upstream of the means for accumulating water.
54. The system of claim 51 further comprising a means for adjusting
an operating parameter of at least one of the electrochemical
device, the means for accumulating water and the means for fluidly
delivering a portion of the water.
55. The system of claim 51 further comprising means for heating the
water.
56. A method for treating water comprising: mixing water from a
point of entry with a treated water to produce a mixed water;
removing a portion of any undesirable species from a portion of the
mixed water in an electrochemical device to produce the treated
water; and distributing a portion of the mixed water to a point of
use.
57. The method of claim 56 further comprising pre-treating at least
a portion of the mixed water.
58. The method of claim 56 further comprising adjusting at least
one of a voltage and current applied on the electrochemical
device.
59. The method of claim 56 further comprising heating at least a
portion of the mixed water.
60. A method for treating water comprising: accumulating water from
a point of use; removing at least a portion of any undesirable
species from the water in an electrochemical device to produce
treated water; and supplying at least a portion of the treated
water to a household.
61. The method of claim 60 wherein the water from the point of use
is accumulated under a pressure that is above atmospheric
pressure.
62. A method for treating water comprising: accumulating water from
a point of use at a pressure that is above atmospheric pressure;
providing an electrochemical device; transferring at least a
portion of the accumulated water to the electrochemical device;
removing at least a portion of any undesirable species from the
water in the electrochemical device to produce a treated water; and
adjusting at least one operating parameter of the electrochemical
device.
63. The method of claim 62 further comprising supplying at least a
portion of the treated water to a household appliance.
64. The method of claim 63 further comprising heating at least a
portion of the treated water prior to supplying the water to a
household appliance.
65. The method of claim 62 further comprising calculating a desired
property of the treated water.
66. The method of claim 62 further comprising reversing a polarity
of an electric field applied across the electrochemical device.
67. The method of claim 62 further comprising adjusting a time
delay between reversing cycles.
68. A system comprising: a fluid reservoir in thermal communication
with a heat exchanger; and a fluid treatment device fluidly
connected to the fluid reservoir.
69. The system of claim 71 wherein the fluid treatment device
comprises at least one of an electrochemical device, a reverse
osmosis device, an ion-exchange device, an electrodialysis device
and a capacitive deionization device.
70. A method for facilitating water treatment comprising: providing
a system comprising a pressurizable reservoir system that is
fluidly connectable to a point of entry and an electrochemical
device fluidly connected to the pressurizable reservoir system and
fluidly connectable to a water distribution system.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to a system and
method of treating or purifying a fluid and, more particularly, to
a water treatment system incorporating an electrochemical device
with a reservoir system for delivering treated water to a point of
use.
[0003] 2. Description of Related Art
[0004] Water that contains hardness species such as calcium and
magnesium may be undesirable for some uses in industrial,
commercial and household applications. The typical guidelines for a
classification of water hardness are: zero to 60 milligrams per
liter (mg/l) as calcium carbonate is classified as soft; 61 to 120
mg/l as moderately hard; 121 to 180 mg/l as hard; and more than 180
mg/l as very hard.
[0005] Hard water can be treated by removing the hardness ion
species. Examples of systems that remove such species include those
that use ion exchange beds. In such systems, the hardness ions
become ionically bound to oppositely charged ionic species that are
mixed on the surface of the ion exchange resin. The ion exchange
resin eventually becomes saturated with ionically bound hardness
ion species and must be regenerated. Regeneration typically
involves replacing the bound hardness species with more soluble
ionic species, such as sodium chloride. The hardness species bound
on the ion exchange resin are replaced by the sodium ions and the
ion exchange resins are ready again for a subsequent water
softening step.
[0006] Other systems have been disclosed. For example, Dosch, in
U.S. Pat. No. 3,148,687 teaches a washing machine including a water
softening arrangement using ion exchange resins. Similarly, Gadini
et al., in International Application Publication No. WO00/64325,
disclose a household appliance using water with an improved device
for reducing the water hardness. Gadini et al. teach of a household
appliance having a control system, a water supply system from an
external source and a softening system with an electrochemical
cell. McMahon, in U.S. Pat. No. 5,166,220, teaches of a
regeneration of ion exchange resin with a brine solution in a water
softening process.
[0007] Systems and techniques that utilize electrodeionization
(EDI) can be used to demineralize, purify or treat water. EDI is a
process that removes ionizable species from liquids using
electrically active media and an electrical potential to influence
ion transport. The electrically active media may function to
collect and discharge ionizable species, or to facilitate the
transport of ions by ionic or electronic substitution mechanisms.
EDI devices can include media having permanent or temporary charge
and can be operated to cause electrochemical reactions designed to
achieve or enhance performance. These devices may also include
electrically active membranes such as semi-permeable ion exchange
or bipolar membranes.
[0008] Continuous electrodeionization (CEDI) is a process that
relies on ion transport through electrically active media or
electroactive media. A typical CEDI device includes alternating
electroactive semi-permeable anion and cation selective membranes.
The spaces between the membranes are configured to create liquid
flow compartments with inlets and outlets. A transverse DC
electrical field is imposed by an external power source through
electrodes at the bounds of the compartments. In some
configurations, electrode compartments are provided so that
reaction product from the electrodes can be separated from the
other flow compartments. Upon imposition of the electric field,
ions in the liquid to be treated in one compartment, the
ion-depleting compartment, are attracted to their respective
attracting electrodes. The ions migrate through the selectively
permeable membranes into the adjoining compartments so that the
liquid in the adjoining ion-concentrating compartments become
ionically concentrated. The volume within the depleting
compartments and, in some embodiments, within the concentrating
compartments, includes electrically active media. In CEDI devices,
the electroactive media may include intimately mixed anion and
cation exchange resin beads. Such electroactive media typically
enhances the transport of ions within the compartments and may
participate as a substrate for controlled electrochemical
reactions. Electrodeionization devices have been described by, for
example, Giuffrida et al. in U.S. Pat. Nos. 4,632,745, 4,925,541,
and 5,211,823, by Ganzi in U.S. Pat. Nos. 5,259,936 and 5,316,637,
by Oren et al. in U.S. Pat. No. 5,154,809 and by Kedem in U.S. Pat.
No. 5,240,579.
[0009] Other systems that can be used to demineralize water have
been described. For example, Gaysowski, in U.S. Pat. No. 3,407,864,
teaches of an apparatus that involves both ion exchange and
electrodialysis. Johnson, in U.S. Pat. No. 3,755,135, teaches of a
demineralizing apparatus using a DC potential.
SUMMARY OF THE INVENTION
[0010] The present invention is directed to a water purification or
treatment system comprising a pressurized reservoir system fluidly
connected to a point of entry, a water treatment device fluidly
connected to the pressurized reservoir system, a water distribution
system fluidly connected to the pressurized reservoir system and at
least one point of use fluidly connected to the water distribution
system.
[0011] In another aspect of the present invention, a treatment
system is provided comprising a reservoir system fluidly connected
to a point of entry, an electrochemical device fluidly connected to
the reservoir system, a point of use fluidly connected to the
reservoir system, and an auxiliary use fluidly connected downstream
of the electrochemical device.
[0012] In another aspect of the present invention, a method is
provided for treating water comprising introducing water to a
pressurized reservoir system, transferring a portion of the water
from the pressurized reservoir system to a water treatment device,
removing at least a portion of any undesirable species from the
water from the pressurized reservoir system in the water treatment
device to produce a treated water, transferring the treated water
from the water treatment device to the pressurized reservoir system
and distributing a portion of the treated water from the
pressurized reservoir system to a point of use.
[0013] In another aspect of the present invention, a method is
provided for treating water comprising introducing water from a
point of use to a reservoir system, removing at least a portion of
any undesirable species from the water in the reservoir system in
an electrochemical device to produce treated water and discharge
water, transferring at least a portion of the treated water from
the electrochemical device to the reservoir system, transferring a
portion of the discharge water to an auxiliary use, and
distributing a portion of the treated water from the reservoir
system to a point of use.
[0014] In another aspect of the present invention, a water
distribution system is provided comprising a first pretreatment
system fluidly connected to a point of entry, a pressurized
reservoir system fluidly connected downstream of the first
pretreatment system, a second pretreatment system fluidly connected
to the pressurized reservoir system and an electrochemical device
fluidly connected downstream of the second pretreatment system and
to the pressurized reservoir system.
[0015] In another aspect of the present invention, a water
treatment system is provided comprising means for accumulating
water from a water source at a pressure above atmospheric pressure
and an electrochemical device fluidly connected to the means for
accumulating water.
[0016] In another aspect of the present invention, a method is
provided for treating water comprising mixing water from a point of
entry with a treated water to produce a mixed water, removing a
portion of any undesirable species from a portion of the mixed
water in an electrochemical device to produce the treated water and
distributing a portion of the mixed water to a point of use.
[0017] In another aspect of the present invention, a method is
provided for treating water comprising accumulating water from a
point of use, removing at least a portion of any undesirable
species from the water in an electrochemical device to produce
treated water, and supplying at least a portion of the treated
water to a household.
[0018] In another aspect of the present invention, a method is
provided for treating water comprising accumulating water from a
point of use at a pressure that is above atmospheric pressure,
providing an electrochemical device electrochemical device,
transferring at least a portion of the accumulated water to the
electrochemical device, removing at least a portion of any
undesirable species from the water in the electrochemical device to
produce a treated water, and adjusting at least one operating
parameter of the electrochemical device.
[0019] In another embodiment, the present invention provides a
system comprising a fluid reservoir in thermal communication with a
heat exchanger and a fluid treatment device fluidly connected to
the fluid reservoir.
[0020] In another embodiment, the present invention provides a
method for facilitating water treatment. The method can comprises
providing a system comprising a pressurizable reservoir system that
is fluidly connectable to a point of entry and an electrochemical
device fluidly connected to the pressurizable reservoir system and
fluidly connectable to a water distribution system.
[0021] Other advantages, novel features and objects of the
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings, which are schematic and are not intended
to be drawn to scale. In the figures, each identical or
substantially similar component that is illustrated in various
figures is represented by a single numeral or notation. For
purposes of clarity, not every component is labeled in every
figure, nor is every component of each embodiment of the invention
shown where illustration is not necessary to allow those of
ordinary skill in the art to understand the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Preferred, non-limiting embodiments of the present invention
will be described by way of example and with reference to the
accompanying drawings, in which:
[0023] FIG. 1 is a process flow diagram of a water treatment system
showing an in-line system with a pressurized reservoir system and a
treatment device in accordance with one or more embodiments of the
invention;
[0024] FIG. 2 is a schematic, sectional view through a typical
electrochemical device in accordance with one or more embodiments
of the present invention, illustrating the fluid and ion flow
directions through depleting and concentrating compartments;
[0025] FIG. 3 is a schematic flow diagram of a water treatment
system in accordance with one or more embodiments of the invention
as discussed in Example 1;
[0026] FIG. 4 is a graph showing conductivity of water treated in
the water treatment system exemplarily illustrated in FIG. 3 and
discussed in Example 1;
[0027] FIG. 5 is a schematic flow diagram of a water treatment
system in accordance with one or more embodiments of the invention
as discussed in Example 2; and
[0028] FIG. 6 is a graph showing conductivity of water treated in
the water treatment system exemplarily illustrated in FIG. 5 and
discussed in Example 2.
DETAILED DESCRIPTION OF THE INVENTION
[0029] United States patent applications titled WATER TREATMENT
SYSTEM AND METHOD by Wilkins et al. and filed on even date
herewith; WATER TREATMENT SYSTEM AND METHOD by Ganzi et al. and
filed on even date herewith; WATER TREATMENT SYSTEM AND METHOD by
Freydina et al. and filed on even date herewith; WATER TREATMENT
SYSTEM AND METHOD by Wilkins et al. and filed on even date
herewith; WATER TREATMENT SYSTEM AND METHOD by Freydina et al. and
filed on even date herewith; WATER TREATMENT SYSTEM AND METHOD by
Wilkins et al. and filed on even date herewith; and WATER TREATMENT
SYSTEM AND METHOD by Jha et al. and filed on even date herewith are
hereby incorporated by reference herein.
[0030] The present invention is directed to a water treatment or
purification system and method of providing treated water in
industrial, commercial and residential settings. The treatment
system can provide treated water to a point of use by removing at
least a portion of any hardness-causing species contained in water
from a water source, such as municipal water, well water, brackish
water and water containing foulants. Other applications of the
system would be in the treatment and processing of foods and
beverages, sugars, various industries, such as the chemical,
pharmaceutical, food and beverage, wastewater treatments and
power-generating industries. The present invention will be
described using water as the fluid but should not be limited as
such. For example, where reference is made to treated water, it is
believed that other fluids can be treated according to the present
invention. Moreover, where reference is made to a component of the
system or to the method of the present invention that adjusts,
modifies, measures or operates on water or water property, the
present invention is believed to be applicable as well. Thus, the
fluid to be treated may be a fluid that is a mixture comprising
water. Accordingly, the fluid can be a liquid that can comprise
water.
[0031] The water purification or treatment system in accordance
with one or more embodiments of the present invention typically
receives water from the water source or a point of entry and
purifies the water containing at least some undesirable species
before delivering the treated water to a point of use. The
treatment system typically has a reservoir system in line with a
water purification or treatment apparatus such as, but not limited
to, an electrodeionization device, a reverse osmosis device, an
electrodialysis device, a capacitive deionization device, a
microfiltration device, and/or an ultrafiltration device. The
treatment system, in some embodiments of the present invention,
further comprises a sensor for measuring at least one property of
the water or an operating condition of the treatment system. In
other embodiments, the treatment system also includes a controller
for adjusting or regulating at least one operating parameter of the
treatment system or a component of the treatment system.
[0032] FIG. 1 shows a schematic flow diagram of a treatment system
according to one embodiment of the present invention. Treatment
system 10 includes a reservoir system 12 fluidly connected,
typically, to a liquid source or a point of entry 14 and to a
purification or treatment device 16, typically downstream of the
point of entry. Treatment system 10 typically includes a point of
use 18, which is typically fluidly connected downstream of
reservoir system 12. In certain embodiments, treatment system 10
also has a sensor 20 and a controller 22 for controlling or
regulating power source 24 which provides power to treatment device
16. Treatment device 16 typically removes at least a portion of any
undesirable species from the liquid to be treated, flowing from
point of entry 14, to produce treated liquid, such was treated
water, for storage in reservoir system 12 and ultimate delivery to
point of use 18. Undesirable species removed by treatment device 16
can be transferred to an auxiliary use or a drain 26.
[0033] In certain embodiments of the present invention, treatment
system 10, as, for example, a water treatment system, further
includes pretreatment system 28, which is typically fluidly
connected upstream of reservoir system 12 or treatment device 16.
Moreover, treatment system 10 typically also includes one or more
fluid control components, such as pump 30 and valve 32.
[0034] The present invention will be further understood in light of
the following definitions. As used herein, "pressurized" refers to
a system or component that has a pressure, internal or applied,
that is above atmospheric pressure. For example, pressurized
reservoir system 12 has an internal pressure that is greater than
atmospheric pressure. Pressure in the pressurized reservoir system
can be created by various methods and techniques, for example, by
pressurizing the water with a water pump or by elevating the water
source, thus creating head pressure. Furthermore, where reference
is made to "treated" water or fluid, the treated water can be
softened water, low Langelier Saturation Index (LSI) water or low
conductivity water. As used herein, low LSI water has a LSI of less
than about 2, preferably, less than about 1, and more preferably,
less than about zero. As used herein, the phrase "treatment device"
or "purification device" or apparatus pertains to any apparatus
that can be used to remove or reduce the concentration any
undesirable species from a fluid to be treated. Such treatment
apparatus include, but are not limited to, those that rely on
techniques such as ion-exchange resin reverse osmosis,
electrodeionization, electrodialysis, ultrafiltration,
microfiltration, capacitive deionization. Further, where reference
is made to an electrochemical device, such as "electrodeionization
device 16," such reference is meant to be exemplary and other
electrochemical devices such as, but not limited to,
electrodeionization devices, electrodialysis devices, and, in some
cases, capacitive deionization devices, may be used in accordance
with the principles of the present invention as long as such use is
not inconsistent or contrary to operation of such devices and/or
the techniques of the present invention. Although a number of
apparatus may be used as a treatment device, the applicability of
such apparatus is not intended to imply that each or all of the
apparatus utilize the same principles but that such apparatus may
be used, alone or in combination, as a treatment device in
accordance with one or more systems and techniques of the present
invention.
[0035] FIG. 2 schematically shows a cross-sectional view of fluid
and ion flow paths through one embodiment of an electrodeionization
device of the present invention. The electrodeionization module or
device 16 includes ion-depleting (depleting) compartments 34 and
ion-concentrating (concentrating) compartments 36, positioned
between depleting compartments 34. Depleting compartments 34 are
typically bordered by an anolyte compartment 38 and a catholyte
compartment 40. Typically, end blocks (not shown) are positioned
adjacent to end plates (not shown) to house an anode 42 and a
cathode 44 in the respective compartments. In certain embodiments,
the compartments include cation-selective membranes 46 and
anion-selective membranes 48. The cation-selective membranes and
anion-selective membranes typically comprise ion exchange powder, a
polyethylene powder binder and a glycerin lubricant.
[0036] In accordance with one or more embodiments of the present
invention, the cation- and anion-selective membranes are typically
heterogeneous polyolefin-based membranes, which are typically
extruded by a thermoplastic process using heat and pressure to
create a composite sheet. However, the present invention
contemplates the use of the other types of membranes including
homogeneous membranes. Representative suitable ion-selective
membranes include, for example, web supported using styrene-divinyl
benzene with sulphonic acid or quaternary ammonium functional
groups, web supported using styrene-divinyl benzene in a
polyvinylidene fluoride binder, and unsupported-sulfonated styrene
and quarternized vinyl benzyl amine grafts on polyethylene
sheet.
[0037] Concentrating compartments 36 are typically filled with
electroactive media such as cation exchange resin beads 50 and
depleting compartments 34 are typically filled with a mixture of
cation exchange resin beads 50 and anion exchange resin beads 52.
In some embodiments, the cation exchange and anion exchange resin
beads can be arranged in layers within any of the depleting,
concentrating and electrode compartments so that a number of layers
in a variety of arrangements can be assembled. Other configurations
and/or arrangements are believed to be within the scope of the
invention including, for example, the use of mixed bed ion exchange
resin beads in any of the depleting, concentrating and electrode
compartments, the use of inert resin between layer beds of anionic
and cationic exchange resin beads, the use of various types and
arrangements of anionic and cationic resin beads including, but not
limited to, those described by DiMascio et al., in U.S. Pat. No.
5,858,191, which is incorporated herein by reference in its
entirety.
[0038] In operation, a liquid to be treated 54, typically from an
upstream water source entering the treatment system at point of
entry 14, having dissolved cationic and anionic components,
including hardness ion species, can be introduced into depleting
compartments 34 through manifold 60, wherein the cationic
components are typically attracted to the cation exchange resin
beads 50 and the anionic components are attracted to the anion
exchange resin beads 52. An electric field applied across
electrodeionization device 16, through anode 42 and cathode 44,
which are typically positioned on opposite ends of
electrodeionization device 16, typically passes perpendicularly
relative to the fluid flow direction. Under the influence of the
electric field, cationic and anionic components in the liquid tend
to migrate in a direction corresponding to their attracting
electrodes. Cationic components can migrate through
cation-selective membrane 46 into adjacent concentrating
compartment 36.
[0039] Anion-selective membrane 48, positioned on the opposite side
of concentrating compartment 36, prevents migration into adjacent
compartments, thereby trapping the cationic components in the
concentrating compartment. Similarly, anionic components migrate
through the ion-selective membranes, but in a direction that is
opposite relative to the migration direction of the cationic
components. Anionic components migrate through anion-selective
membrane 48, from depleting compartment 34, into adjacent
concentrating compartment 36. Cation-selective membrane 46,
positioned on the other side of concentrating compartment 36,
prevents further migration, thus trapping anionic components in the
concentrating compartment. In net effect, ionic components are
removed or depleted from the liquid 54 flowing in depleting
compartments 34 and collected in concentrating compartments 36
resulting in a treated water product stream 56 and a concentrate or
waste stream 58.
[0040] In accordance with some embodiments of the present
invention, the applied electric field on electrodeionization device
16 creates a polarization phenomenon, which typically leads to the
dissociation of water into hydrogen and hydroxyl ions. The hydrogen
and hydroxyl ions regenerate the ion exchange resin beads 50 and 52
in depleting compartments 34 and in some embodiments, concentrating
compartments 36, so that removal of dissolved ionic components can
occur continuously and without a separate step for regenerating
exhausted electroactive media.
[0041] The applied electric field on electrodeionization device 16
is typically a direct current. However, any applied electric
current that creates a bias or a potential difference between one
electrode and another can be used to promote migration of ionic
species by, for example, ionic attraction. Therefore, an
alternating current may be used, provided that there is a potential
difference between electrodes that is sufficient to attract
cationic and anionic species to the respective attracting
electrodes. In yet another embodiment, an alternating current may
be rectified, for example, by using a diode or a bridge rectifier,
to convert an alternating current to a pulsating current with
sufficient potential to attract the charged species.
[0042] The electroactive media, ion exchange resin beads 50 and 52,
typically utilized in ion-depleting compartments 34, can have a
variety of functional groups on their surface regions including,
but not limited to, tertiary, alkyl amino groups and dimethyl
ethanolamine. These materials can also be used in combination with
materials having various functional groups on their surface
regions, such as quaternary ammonium groups. Other modifications
and equivalents of the electrodeionization device, as part of the
water treatment system disclosed, will occur to persons skilled in
the art using no more than routine experimentation. For example,
various other types of electroactive media may be used such as
heterogeneous and homogeneous types. Similarly, other variations in
arrangements of depleting and concentrating compartments are
believed to be within the scope and spirit of the invention.
[0043] Reservoir system 12 serves to store or accumulate water from
point of entry 14 or a water source and can also serve to store
treated water from product stream 56 from electrodeionization
device 16 and can also provide water, typically treated water, or
treated water mixed with water from point of entry 14, to point of
use 18 through a distribution system.
[0044] In accordance with some embodiments of the present
invention, reservoir system 12 comprises a pressurized vessel or a
vessel that has inlets and outlets for fluid flow such as an inlet
62 and an outlet 64. Inlet 62 is typically fluidly connected to
point of entry 14 and outlet 64 is typically fluidly connected to a
water distribution system or a point of use 18. Reservoir system 12
can have several vessels, each vessel, in turn, can have several
inlets positioned at various locations. Similarly, outlet 64 can be
positioned on each vessel at various locations depending on, among
other things, demand or flow rate to point of use 18, capacity or
efficiency of electrodeionization device 16 and capacity or hold-up
of reservoir system 12. Reservoir system 12 can further comprise
various components or elements that perform desirable functions or
avoid undesirable consequences. For example, reservoir system 12
can have vessels having internal components, such as baffles that
are positioned to disrupt any internal flow currents within the
vessels of reservoir system 12. In some embodiments, reservoir
system 12 has a heat exchanger for heating or cooling the fluid.
For example, reservoir system 12 can comprise a vessel with a
heating coil, which can have a heating fluid at an elevated
temperature relative to the temperature of the fluid in the vessel.
The heating fluid can be hot water in closed-loop flow with a
furnace or other heating generating unit operation so that the
heating fluid temperature is raised in the furnace. The heating
fluid, in turn, raises the vessel fluid temperature by heat
transfer. Other examples of auxiliary or additional components
include, but are not limited to, pressure relief valves designed to
relieve internal pressure of any vessels and avoid or at least
reduce the likelihood of vessel rupture and thermal expansion tanks
that are suitable for maintaining a desired operating pressure. The
size and capacity of the thermal expansion tank will depend on
factors including, but not limited to, the total volume of water,
the operating temperature and pressure of the reservoir system.
[0045] In accordance with one or more embodiments of the present
invention, the reservoir system is connected in or in thermal
communication with the heat exchanger and, optionally, to a fluid
treatment device. The fluid treatment device can be an
electrodeionization device, a reverse osmosis device, an
ion-exchange resin bed, an electrodialysis device, a capacitive
deionization device, or combinations thereof.
[0046] In operation, reservoir system 12 is typically connected
downstream of point of entry 14 and fluidly connected in-line, such
as in a circulation loop, with electrodeionization device 16. For
example, water from point of entry 14 can flow into inlet 62 and
can mix with the bulk water contained within reservoir system 12.
Bulk water can exit reservoir system 12 through outlet 64 and can
be directed to point of use 18 or through pump 30 into
electrodeionization device 16 for treatment or removal of any
undesirable species. Treated water leaving electrodeionization
device 16 can mix with water from point of entry 14 and enter
reservoir system 12 through inlet 62. In this way, a loop can be
formed between reservoir system 12 and electrodeionization device
16 and feedwater from point of entry 14 can replenish water demand
created by and flowing to point of use 18.
[0047] Point of entry 14 provides or connects water from a water
source to the water treatment system. The water source can be a
potable water source, such as municipal water source or well water
or it can be a non-potable water source, such as a brackish or
salt-water source. In some instances, an intermediate treatment or
treatment system typically purifies the water for human consumption
before it reaches point of entry 14. The water typically contains
dissolved salts or ionic or ionizable species including sodium,
chloride, chlorine, calcium ions, magnesium ions, carbonates,
sulfates or other insoluble or semi-soluble species or dissolved
gases, such as silica and carbon dioxide. Moreover, the water can
contain additives, such as fluoride, chlorate and bromate.
[0048] In accordance with another embodiment of the present
invention, treatment system 10 includes a fluid distribution system
(not shown), which in turn connects to a point of use. The
distribution system can comprise components that are fluidly
connected to provide, for example, water, typically treated water,
from reservoir system 12 to point of use 18. The distribution
system can comprise any arrangement of pipes, valves, tees, pumps
and manifolds to provide water from reservoir system 12 to one or
several points of use 18 or to any component of treatment system
10. In one embodiment, the distribution system comprises a
household or residential water distribution system including, but
not limited to, connections to one or more points of use such, but
not limited to, a sink faucet, a shower head, a washing machine and
a dishwasher. For example, system 10 may be connected to the cold
or hot, or both, water distribution system of a household.
[0049] Point of use 18 is typically any device or appliance that
requires or demands water. For example, point of use 18 can be an
appliance, such as a washing machine or a dishwasher, or can be a
faucet serving to provide water to a kitchen sink or a showerhead.
In another embodiment, point of use 18 comprises a system for
providing water suitable for household or residential use.
[0050] In accordance with another embodiment of the present
invention, water treatment system 10 also comprises a sensor, such
as a water property sensor, which measures at least one physical
property in treatment system 10. For example, sensor 20 can be a
device that can measure water conductivity, pH, temperature,
pressure, composition or flow rate. Sensor 20 can be installed or
positioned within treatment system 10 to measure a particularly
preferred water property. For example, sensor 20 can be a water
conductivity sensor installed in reservoir system 12 so that sensor
20 measures the conductivity of the water, which can provide an
indication of the quality of the water available for service in
point of use 18. In another embodiment, sensor 20 can comprise a
series or a set of sensors in any various configurations or
arrangements in treatment system 10. The set of sensors can be
constructed, arranged or connected to controller 22 so that
controller 22 can monitor, intermittently or continuously, the
quality of water in, for example, reservoir system 12. In such an
arrangement, the performance of treatment system 10 can be
optimized as described below. Other embodiments may comprise a
combination of sets of sensors in various locations throughout
treatment system 10. For example, sensor 20 can be a flow sensor
measuring a flow rate to a point of use 18 and further include any
of a pH meter, nephelometer, composition analyzer, temperature and
pressure sensor monitoring the operating condition of treatment
system 10.
[0051] In accordance with another embodiment of the present
invention, water treatment system 10 can further comprise a
pretreatment system 28 designed to remove a portion of any
undesirable species from the water before the water is introduced
to, for example, reservoir system 12 or the electrodeionization
device 16. Examples of pretreatment systems include, but are not
limited to, reverse osmosis devices, which are typically used to
desalinate brackish or salt water. A carbon or charcoal filter may
be used to remove at least a portion of any chlorine, including
active chlorine, or any species that may foul or interfere with the
operation of electrodeionization device 16. Pretreatment system 28
can be positioned anywhere within water treatment system 10. For
example, pretreatment system 28 can be positioned upstream of
reservoir system 12 or downstream of system 12 but upstream of
electrodeionization device 16 so that at least some chlorine
species are retained in reservoir system 12 but are removed before
water enters electrodeionization device 16. In accordance with
further embodiments of the present invention, disinfecting and/or
cleaning apparatus or systems may be utilized with the treatment
system. Such disinfecting or cleaning system can comprise any
apparatus that destroys or renders inactive, at least partially,
any microorganisms, such as bacteria, that can accumulate in any
component of the treatment system. Examples of such cleaning or
disinfecting systems include those that can introduce a
disinfectant or disinfecting chemical compounds, such as halogens,
halogen-donors, acids or bases, as well as systems that expose
wetted components of the treatment system to hot water at a
temperature capable of sanitization. In accordance with still
further embodiments, of the present invention, the treatment system
can include final stage or post treatment systems or subsystems
that provide final purification of the fluid prior to delivery at a
point of use. Examples of such post treatment systems include, but
are not limited to those that expose the fluid to actinic radiation
or ultraviolet radiation, and/or ozone or remove undesirable
compounds by micro filtration or ultrafiltration. Thus, in
accordance with one or more embodiments of the present invention,
the treatment system may be utilized for household service and
installed, for example, under a sink and provide treated water,
which is treated by exposure to ultraviolet radiation, before being
delivered to a point of use, such as a faucet.
[0052] In accordance with other embodiments of the present
invention, treatment system 10 can further comprise a controller 22
that is capable of monitoring and regulating the operating
conditions of treatment system 10 and its components. Controller 22
typically comprises a microprocessor-based device, such as a
programmable logic controller (PLC) or a distributed control system
that receives or sends input and output signals to components of
treatment system 10. In one embodiment, controller 22 can comprise
a PLC that sends a signal to power source 24, which supplies power
to electrodeionization device 16 or can provide a signal to a motor
control center that provides power to pumps 30. In certain
embodiments, controller 22 regulates the operating conditions of
water treatment system 10 in open-loop or closed-loop control
scheme. For example, controller 22, in open-loop control, can
provide signals to the water treatment system such that water is
treated without measuring any operating condition. Controller 22
can control the operating conditions in closed-loop control so that
operating parameters can be adjusted depending on an operating
condition measured by, for example, sensor 20. In yet another
embodiment, controller 22 can further comprise a communication
system such as a remote communication device for transmitting or
sending the measured operating condition or operating parameter to
a remote station.
[0053] In accordance with another embodiment of the present
invention, controller 22 can provide a signal that actuates a valve
32 in treatment system 10 so that fluid flow in treatment system 10
is adjusted based on a variety of parameters including, but not
limited to, the quality of water from point of entry 14, the
quality of water to point of use 18, the demand or quantity of
water to point of use 18, the operating efficiency or capacity of
electrodeionization device 16, or any of a variety of operating
conditions, such as the water conductivity, pH, turbidity,
composition, temperature, pressure and flow rate. In one
embodiment, controller 22 receives signals from sensor 20 so that
controller 22 is capable of monitoring the operating parameters of
treatment system 10. For example, sensor 20 can be a water
conductivity sensor positioned within reservoir system 12 so that
the water conductivity in reservoir system 12 is monitored by
controller 22. Controller 22 can, based on, for example, the water
quality measured by sensor 20, control power source 24, which
provides an electric field to electrodeionization device 16. So, in
operation, controller 22 can increase or decrease or otherwise
adjust the voltage and current or both supplied from power source
24 to electrodeionization device 16. Controller 22 typically
includes algorithms that can change an operating parameter of
treatment system 10 based on one or more measured properties of the
liquid flowing in the system. Thus, in some embodiments of the
present invention, controller 22 can increase or decrease or
otherwise adjust the period between operating cycles of
electrodeionization device 16, such as, but not limited to, cycles
of reversing applied electric field and the associated fluid
flow.
[0054] In accordance with another embodiment of the invention,
controller 22 can reverse the direction of the applied current from
power source 24 to electrodeionization device 16 according to a
predetermined schedule or according to an operating condition, such
as the water quality or any other operating parameter. Polarity
reversal has been described by, for example, Giuffrida et al., in
U.S. Pat. No. 4,956,071, which is incorporated herein by reference
in its entirety.
[0055] Controller 22 can be configured or configurable by
programming or can be self-adjusting such that it is capable of
maximizing, for example, any of the service life and the efficiency
of or reducing the operating cost of treatment system 10. For
example, controller 22 can comprise a microprocessor having
user-selectable set points or self-adjusting set points that
adjusts the applied voltage and current to electrodeionization
device 16, the flow rate through the concentrating and depleting
compartments of the electrodeionization device or the discharge
flow rate to drain 26 from the electrodeionization device or the
pretreatment system or both. Other modifications and equivalents of
the controller, as part of the water treatment system disclosed,
will occur to persons skilled in the art using no more than routine
experimentation. For example, the use of adaptive, self-adjusting,
or self-diagnosing controllers capable of changing the operating
parameters based on a variety of input parameters such as rate of
water use or time of water use, are believed to be within the scope
and spirit of the invention.
[0056] In accordance with another embodiment of the present
invention, controller 22 can calculate a control parameter that can
be used to adjust or vary a control signal to a component of the
water treatment system. For example, controller 22 can calculate a
LSI based on the measured operating conditions of the streams of
the water treatment system. LSI can then be used in another or the
same control loop, in the same or another controller, as an input
variable that can be compared to a set-point and generate an output
signal that actuates, adjusts or otherwise regulates a component of
the water treatment system. LSI can be calculated according to, for
example, ASTM D 3739.
[0057] Controller 22 can incorporate dead band control to reduce
the likelihood of unstable on/off control or chattering. Dead band
refers to the range of signal outputs that a sensor provides
without necessarily triggering a responsive control signal. The
dead band may reside, in some cases, intrinsically in the sensor or
may be programmed as part of the control system, or both. Dead band
control can avoid unnecessary intermittent operation by smoothing
out measurement excursions. Such control techniques can prolong the
operating life or mean time before failure of the components of
treatment system 10. Other techniques that can be used include the
use of voting, time-smoothing or time-averaging measurements or
combinations thereof.
[0058] In accordance with another embodiment of the present
invention, discharge water, typical from waste stream 58, to
auxiliary use can serve or provide additional or secondary
benefits. For example, waste stream 58, rather than going to drain
26, may be used to provide, for example, irrigating water to any
residential, commercial or industrial use, such as for irrigating,
for recycling or for recovery of collected or concentrated salts.
In yet another embodiment, the treatment system includes a mixing
system that is fluidly connected to at least one of the
distribution system and the reservoir system. The mixing or
blending system can include a fluid connection in the distribution
system as well as a fluid connection to the point of entry. The
mixing system can provide fluid mixing of, for example, untreated
water with treated water to produce service water that can be used
at the point of use. The mixing system can include at least one a
tee and a mixing tank, or both, that fluidly connects an outlet of
the reservoir system and the point of entry. The mixing system, in
some cases, can include a valve that regulates the flow of any of
the untreated water stream and the treated water stream flowing to
the point of use. In another embodiment, the valve can be a
proportional valve that mixes the treated water with untreated
water according to a predetermined ratio. In another embodiment,
the valve can be actuated by the controller depending on any of the
flow rate, the water property and the particular service associated
with the point of use. For example, if a low hardness water is
required by the point of use, then the controller can regulate the
amount of untreated water, if any, that can be mixed with treated
water by actuating a valve, which regulates the flow rate of the
untreated water, in closed-loop control with a sensor measuring the
conductivity of the mixed water stream. In another embodiment, the
valve can regulate the flow rate of the treated water that would be
mixed with the untreated water according to the requirements of the
point of use. In another embodiment, the treatment device can be
operated to reach a set-point that is lower than any required by
various points of use so that any mixing of treated water with
untreated water can produce service water that satisfies the
particular requirements of each point of use. Those of ordinary
skill should recognize that the present the treatment system can be
adjustable to accommodate fluctuations in demand as well as
variations in water quality requirements. For example, the present
invention can provide a water treatment system that can produce low
LSI water, which would be available to the system as a whole,
during extended idle periods. The low LSI water, in some
embodiments, can be used to flush the wetted components of the
treatment system, which can reduce the likelihood of scaling and
should increase the service life of the components, individually,
as well as the treatment system as a whole. In accordance with some
embodiments, the present invention provides a system for producing
treated liquids, such as water, having a low conductivity. As used
herein, a low conductivity liquid has a conductivity of less than
about 300 .mu.S/cm, preferably less than about 220 .mu.S/cm and
more preferably, less than about 200 .mu.S/cm.
[0059] The treatment system can comprise a fluid circuit that can
provide treated or, in some cases, softened water or, in other
cases, low conductivity water or low LSI water, to an electrode
compartment of the treatment device such as an electrodeionization
device. The fluid circuit can comprise fluid connections from a
treated water source to the electrode compartments of the
electrodeionization device. The fluid circuit can also comprise a
pretreatment unit, such as a carbon filter that can remove any
species, such as chlorine, which can interfere with the operation
of the electrodeionization device. The fluid circuit can also
include fluid connections to at least one of the depleting and the
concentrating compartments of the electrodeionization device, for
example, downstream of the pretreatment unit. The fluid circuit
connections, in accordance with one or more embodiments of the
present invention provides connections so that fluid exiting the
electrode compartments can be, for example, mixed together or mixed
with fluid to be treated in the depleting compartment. The fluid
circuit can also comprise pumps and valves that can direct fluid
flow to and from the electrodeionization device as well as to and
from the reservoir system. In some cases, the fluid circuit is
arranged to provide fluid connections that creates parallel flow
paths through the electrode compartments of the electrodeionization
device. Other arrangements and configurations are considered to be
within the scope of the present invention including, for example,
serial flow paths from one electrode compartment to the other, the
use of single, multiple or dedicated pretreatment units as well as
multiple or staged treatment units including, but not limited to,
reverse osmosis, ion exchange and electrodeionization devices, or
combinations thereof, in the fluid circuit.
[0060] The treatment system can comprise a fluid circuit that
provides fluid connections from a depleting compartment to at least
one electrode compartment of the electrodeionization device. Such
an arrangement can provide treated water, preferably water having
low LSI or low conductivity, or both, to the electrode compartment.
The fluid circuit can be arranged so that the fluid flow paths can
be in series or in parallel through the electrode compartments. The
fluid circuit can also comprise fluid connections to allow the
fluid that would exit the electrode compartment to be delivered to
a point of use via, for example, a water distribution system or to
a reservoir system, or to both. In some arrangements, the fluid
circuit can comprise fluid connections so that untreated fluid can
be mixed with fluid that would exit any of electrode compartments;
the mixture can be delivered to the point of use. In another
embodiment, the fluid circuit can further comprise fluid
connections to and from a reservoir system so that, for example,
treated fluid that would exit the depleting compartment can be
transferred to the reservoir system and mixed with untreated fluid
from the point of entry and the mixture can be delivered to the
point of use and, optionally, to the electrode compartments of the
electrodeionization device in parallel or series flow paths. Other
arrangements and combinations including, for example, the mixing of
treated and untreated water to produce a mixed electrode
compartment flushing fluid is considered to be within the scope of
the present invention.
[0061] The present invention will be further illustrated through
the following examples, which are illustrative in nature and are
not intended to limit the scope of the invention.
EXAMPLE 1
[0062] An in-line pressurized water treatment system in accordance
with one or more embodiments of the systems and techniques of the
present invention, schematically shown in FIG. 3, was evaluated for
performance. The water treatment system 10 had an
electrodeionization module 16 with a pretreatment system (not
shown) and a pressurized storage vessel 12. Water, from point of
entry 14, was introduced into pressurized vessel 12 and was
circulated through electrodeionization module 16. The water
treatment system was controlled by a programmable controller (not
shown) based on a measured water conductivity, as measured by
sensors 20b and 20c, upstream of an inlet 62 and downstream of an
outlet 64 of pressurized vessel 12.
[0063] Electrodeionization device 16 comprised of a 10-cell pair
stack with 13-inch flowpaths. Each cell was filled with about 40%
AMBERLITE.RTM. SF 120 resin and about 60% AMBERLITE.RTM. IRA 458
resin, both available from Rohm & Haas Company, Philadelphia,
Pa. The electrodeionization device had an expanded titanium
electrode, which was coated with ruthenium oxide. The pretreatment
system comprised of an aeration type iron-filter with a 25-micron
rating, a 20 inch.times.4 inch sediment filter and a 20
inch.times.4 inch carbon block filter. Pressurized vessel 12 was
about a 10 inch diameter fiberglass vessel with about a 17-gallon
capacity. The pressurized vessel was fitted with a valve head and a
center manifold pipe.
[0064] The concentrate stream leaving the electrodeionization
device was partially circulated and partially rejected to a drain
26 by regulating valves 32b, 32c, 32e, 32f, 32g, 32h, 32j and 32l.
Make-up water, from point of entry 14, was fed into the circulating
stream to compensate for any water that was rejected to drain 26 by
actuating valves 32b, 32c and 32d, in proper sequence. Treated
water exited electrodeionization device 16 and was returned to
vessel 12 through a return fluid circuit having a liquid conduit
and valves 32i and 32k.
[0065] The flow rate of treated water to a point of use 18 from
outlet 64 of pressurized vessel 12 was regulated by adjusting valve
32a. Several sensors measuring operating conditions and water
properties were installed throughout water treatment system 10
including pressure indicators 20d, 20f, 20g, 20h and 20i, flow rate
indicators 20a, 20e, 20j and 20k and conductivity sensors 20b, 20c
and 201.
[0066] The controller was a MICROLOGIX.TM. 1000 programmable
controller available from Allen-Bradley Company, Inc., Milwaukee,
Wis., which was used to control the valve sequencing as well as to
monitor and record the operating conditions of the system. The
controller fluidly isolated the electrodeionization device when a
set-point was reached. The controller started the
electrodeionization device depending on whether a flow switch
signal triggered operation or when the water conductivity of the
outlet stream leaving the pressurized vessel was higher than the
set point. The feed from the electrodeionization device was
circulated from the pressurized vessel via a second feed pump. The
polarity of the electric field applied to the electrodeionization
device was reversed by the controller every 15 minutes.
[0067] The water treatment system was operated until a set point
was reached. The applied voltage to the electrodeionization device
was about 50 volts. The flow rate through the electrodeionization
device was maintained at about 2000 ml/min. Tables 1 and 2
summarize the measured properties of the various streams of the
water treatment system at the start and end of the test,
respectively. Notably, the data presented in Table 1 showed that
the initial feed stream into electrodeionization device 16, with a
conductivity of about 462 .mu.S/cm, was treated to produce an
initial dilute stream having a conductivity of about 374 .mu.S/cm
without a substantial pH change. At the end of the run, feed water
was treated from a conductivity of about 255 .mu.S/cm to produce a
dilute stream with a conductivity of about 158 .mu.S/cm. Notably,
the lower conductivity of the feed stream at the end of the test
run reflected the effect of circulation, which effectively removed
undesirable species over several passes.
1TABLE 1 Stream properties at the start of the test run. Feed
Stream Reject Stream Dilute Stream pH 7.23 7.51 7.41 Conductivity
462 1394 374 (.mu.S/cm)
[0068]
2TABLE 2 Stream properties at the end of the test run. Feed Stream
Reject Stream Dilute Stream pH 6.79 7.77 6.62 Conductivity 255 1024
158 (.mu.S/cm)
[0069] FIG. 4 shows the conductivity of the water along with the
applied current through the electrodeionization device during the
test run. The conductivity of the treated water from the
electrodeionization device, labeled as dilute, was reduced to less
than about 175 .mu.S/cm in less than about 45 minutes. FIG. 4 also
shows that the conductivity of the product stream, to service such
as a point of use and labeled as tank outlet and dilute feed, was
reduced to less than about 300 .mu.S/cm. Furthermore, FIG. 4 shows
that the applied current was reduced, as expected, with decreasing
concentration of hardness species. Thus, the water treatment system
of the present invention reduced the hardness, as measured by
conductivity, by about 70% while delivering about 80 gallons per
day.
EXAMPLE 2
[0070] An in-line pressurized water treatment system in accordance
with one or more embodiments of the present invention,
schematically shown in FIG. 5, was evaluated for performance. The
water treatment system 10 had an electrodeionization module 16 and
a pressurized storage vessel 12. Water, from point of entry 14, was
introduced into pressurized storage vessel 12 through inlet 62 and
was circulated using pumps 30a and 30b and treated through
pretreatment units 28a and 28b and electrodeionization module 16.
The water treatment system was controlled by a programmable
controller (not shown) based on the measured water conductivity, as
measured by sensors any of 20a, 20b, and 20c.
[0071] Electrodeionization device 16 comprised of a 10-cell pair
stack with flowpaths that were about 7.5 inches long and about 2.5
inches wide. Each cell was filled with about 40% AMBERLITE.RTM. SF
120 resin and about 60% AMBERLITE.RTM. IRA 458 resin, both
available from Rohm & Haas Company, Philadelphia, Pa. The
electrodeionization device had an expanded titanium electrode
coated with ruthenium oxide.
[0072] The controller was a MICROLOGIX.TM. 1000 programmable
controller available from Allen-Bradley Company, Inc., Milwaukee,
Wis. The electrodeionization device was set to start up either by a
flow switch signal or when the water conductivity of the outlet
stream leaving the pressurized vessel was higher than a set point.
The electrodeionization device operated until the conductivity
reached the set point. The feed from the electrodeionization device
was circulated from the pressurized vessel via a second feed pump.
The polarity of the electric field applied to the
electrodeionization device was reversed about every 15 minutes. In
addition to controlling the components of electrodeionization
device 16, the PLC collected, stored and transmitted measured data
from sensors 20a, 20b, 20c and 20d.
[0073] Pressurized vessel 12 was a 10-inch diameter fiberglass
vessel with a 30-gallon capacity. Pressurized vessel 12 was fitted
with a valve head and a center manifold pipe. The concentrate
stream leaving the electrodeionization device was partially
circulated and partially rejected to a drain 26 by regulating
valves 32c, 32d, 32e, 32f and 32g. Make-up water, from point of
entry 14, was fed into the circulating stream to compensate for any
water that was rejected to drain 26. The pretreatment system
comprised of an aeration iron-filter with a 25-micron rating, a 20
inch.times.4 inch sediment filter and a 20 inch.times.4 inch carbon
block filter.
[0074] In the one flow direction, water from pressure vessel 12 was
pumped by pump 30a, from pressure vessel 12 through valve 32c, to
pretreatment unit 28a before being introduced to the depleting
compartments (not shown) of electrodeionization device 16. Treated
water from electrodeionization device 16 was directed by valve 32f
to storage in pressure vessel 12. Fluid collecting removed ionic
species was circulated by pump 30b through pretreatment unit 28b,
the concentrating and electrode compartments (not shown) of
electrodeionization device 16 and valve 32e. When the direction of
the applied electric field was reversed, the flow directions were
correspondingly adjusted so that pump 30a, pretreatment unit 28a,
and valves 32c and 32f circulated the concentrate stream, which was
accumulating ionic species, while flowing through the concentrating
and electrode compartments of electrodeionization device 16.
Similarly, water to be treated was pumped from pressure vessel 12
using pump 30b through valve 32d to pretreatment unit 28b before
being introduced and treated in the depleting compartments of
electrodeionization device 16. From electrodeionization device 16,
treated water was directed by valve 32e to flow into pressure
vessel 12.
[0075] The flow rate of treated water, as measured by flow
indicator 20d, to a point of use 18 from outlet 64 of pressurized
vessel 12 was regulated by adjusting valves 32a and 32b. To
discharge the concentrate stream, valve 32g was operated as
necessary. Water from point of entry 14 was used to replace fluid
that was discharged to drain 26. The water treatment system was
operated until a target set point of about 220 .mu.S/cm was reached
and stable for about one minute. The applied voltage to the
electrodeionization device was about 46 volts. The flow rates into
the depleting and concentrating compartments were maintained at
about 4.4 liters per minute. The reject flow rate was controlled to
discharge about 270 ml of the concentrate stream about every 30
seconds. The pressure in the vessel was about 15 psig to about 20
psig.
[0076] FIG. 6 shows the measured conductivity of the various
streams in the water treatment system, against run time. Tables 3
and 4 summarize the measured properties of the various streams of
the water treatment system at the start and end of the test,
respectively. The data presented in Table 3 showed that the initial
feed stream, labeled as tankout conductivity in FIG. 6, into
electrodeionization device 16 with a conductivity of about 412
.mu.S/cm was treated to produce an initial dilute stream, labeled
as stackout conductivity in FIG. 6, having a conductivity of about
312 .mu.S/cm, without a substantial pH change. Similarly, at the
end of the test run, water having a conductivity of about 221
.mu.S/cm was treated to produce lower conductivity water of about
164 .mu.S/cm without a substantial pH change.
[0077] As similarly noted in Example 1, the lower conductivity of
the feed stream at the end of the test run reflected the effect of
circulation, which effectively removed undesirable species over
several passes. Thus, this example shows that the treatment system
of the present invention, schematically illustrated in FIG. 5, can
treat water that is suitable for household or residential use.
3TABLE 3 Stream properties at the start of the test run. Feed
Stream Reject Stream Product Stream pH 8.19 8.3 8.02 Conductivity
412 944.9 312.0 (.mu.S/cm)
[0078]
4TABLE 4 Stream properties at the end of the test run. Feed Stream
Reject Stream Product Stream pH 8.37 8.33 7.75 Conductivity 221
833.8 164 (.mu.S/cm)
[0079] Those skilled in the art would readily appreciate that all
parameters and configurations described herein are meant to be
exemplary and that actual parameters and configurations will depend
upon the specific application for which the systems and methods of
the present invention are used. Those skilled in the art will
recognize, or be able to ascertain using no more than routine
experimentation, many equivalents to the specific embodiments of
the invention described herein. For example, those skilled in the
art may recognize that the present invention may further comprise a
network of systems or be a component of a system such as a
household or residential management system. It is, therefore, to be
understood that the foregoing embodiments are presented by way of
example only and that, within the scope of the appended claims and
equivalents thereto, the invention may be practiced otherwise than
as specifically described. The present invention is directed to
each individual feature, system, or method described herein. In
addition, any combination of two or more such features, systems or
methods, if such features, systems or methods are not mutually
inconsistent, is included within the scope of the present
invention.
* * * * *