U.S. patent application number 11/439167 was filed with the patent office on 2007-11-29 for total solution for water treatments.
This patent application is currently assigned to Advanced Desalination Inc.. Invention is credited to Min-Chu Chen, Mu-Fa Chen, Lih-Ren Shiue.
Application Number | 20070272550 11/439167 |
Document ID | / |
Family ID | 38748520 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070272550 |
Kind Code |
A1 |
Shiue; Lih-Ren ; et
al. |
November 29, 2007 |
Total solution for water treatments
Abstract
All pollutants dissolved or existed in water can be grossly
classified as ionized and neutral species. The former includes
inorganic and organic ions, while the latter contains inorganic
molecules, organic molecules and organisms. Using flow through
capacitor for performing capacitive deionization (CDI), the ionic
contaminants can be effectively and economically removed from
water. Whereas the neutral contaminants are not retained in the
static electric field of CDI, they can be decomposed upon flowing
through an electrolytic ozonator. Either gaseous or ionic products
will be generated at the ozone treatment, and the ionic byproducts
can be subsequently removed by CDI. By integrating the electrolytic
ozone reactor with flow through capacitor, the O.sub.3/CDI hybrid
technique becomes a total solution for eliminating hazardous
materials in water. Both the reactor of in-situ ozone and the
flow-through capacitor (FTC) of CDI are operated in energy
conservative and pollution free conditions, so the detoxification
of water is highly cost effective.
Inventors: |
Shiue; Lih-Ren; (Hsinchu,
TW) ; Chen; Min-Chu; (Sugar Land, TX) ; Chen;
Mu-Fa; (Tulsa, OK) |
Correspondence
Address: |
BRUCE H. TROXELL;SUITE 1404
5205 LEESBURG PIKE
FALLS CHURCH
VA
22041
US
|
Assignee: |
Advanced Desalination Inc.
|
Family ID: |
38748520 |
Appl. No.: |
11/439167 |
Filed: |
May 24, 2006 |
Current U.S.
Class: |
204/267 |
Current CPC
Class: |
C02F 2201/782 20130101;
Y02W 10/37 20150501; C02F 1/463 20130101; C02F 9/00 20130101; C02F
2201/4613 20130101; C02F 1/4691 20130101; C02F 1/78 20130101 |
Class at
Publication: |
204/267 |
International
Class: |
C25C 7/00 20060101
C25C007/00 |
Claims
1. A water treatment system for removing contaminant in subject
water comprising: an inlet for receiving the subject water; at
least one ozone reactor for receiving the subject water from the
inlet and providing ozone by electrolyzing the subject water, the
ozone reactor including: a first electrode set for being submerged
in the subject water wherein the first electrode set comprises a
first electrode and a second electrode; and a first power supply
for applying a direct current voltage below 24V to the first
electrode set, wherein the first power supply is capable of
changing the polarities of the first and second electrodes at a
predetermined interval of time; at least one flow through capacitor
for performing capacitive deionization on the subject water from
the ozone reactors and removing ionic contaminant from the subject
water, the flow through capacitor including: a second electrode set
for being submerged in the subject water wherein the second
electrode set comprises a third electrode and a fourth electrode;
and a second power supply for applying a direct current voltage
about 1.about.9V to the second electrode set; and an outlet for
draining the subject water from the flow through capacitors.
2. The water treatment system as claimed in claim 1, wherein the
first electrode set comprise a plurality of identical first metal
sheets longitudinal parallel to each other; a plurality of
identical second metal sheets longitudinal parallel to the first
metal sheets, wherein the first metal sheets and second metal
sheets are arranged alternately; a first electrical rod penetrating
the first and second metal sheets and electrically connecting the
first metal sheets to the first power supply, wherein the first
electrical rod and the first metal sheets form the first electrode;
a second electrical rod penetrating the first and second metal
sheets and electrically connecting the second metal sheets to the
first power supply, wherein the second electrical rod and the
second metal sheets form the second electrode; a plurality of first
insulators disposed on the first electrical rod for providing
electrical insulations between the second metal sheets and the
first electrical rod and disposed on the second electrical rod for
providing electrical insulations between the first metal sheets and
the second electrical rod.
3. The water treatment system as claimed in claim 2, wherein the
first and second metal sheets are in the form of plate or mesh.
4. The water treatment system as claimed in claim 2, wherein the
first and second metal sheets are made of titanium and coated with
platinum, iridium oxide, or synthetic diamond.
5. The water treatment system as claimed in claim 2, wherein the
first insulator is a plastic screen or a plastic ring.
6. The water treatment system as claimed in claim 2, wherein the
firth and second electrical rods are made of titanium.
7. The water treatment system as claimed in claim 1, wherein the
first power supply including at least one supercapacitor.
8. The water treatment system as claimed in claim 7, wherein the
supercapacitor can amplify an input power by 10 times or more.
9. The water treatment system as claimed in claim 7, wherein the
supercapacitor includes a plurality of units that are divided into
two identical modules each has the same operational voltage and
capacitance to be switched reciprocally between charging and
discharging for providing consistent peak power to the first
electrode set.
10. The water treatment system as claimed in claim 1, the ozone
reactor further comprising a housing for allowing subject water
flowing through the housing.
11. The water treatment system as claimed in claim 1, wherein the
ozone reactor is submerged without a housing in an open body of
water.
12. The water treatment system as claimed in claim 1, wherein the
second electrode set comprise a plurality of identical third metal
sheets longitudinal parallel to each other; a plurality of
identical fourth metal sheets longitudinal parallel to the third
metal sheets, wherein the third metal sheets and fourth metal
sheets are arranged alternately; a third electrical rod penetrating
the third and fourth metal sheets and electrically connecting the
third metal sheets to the second power supply, wherein the third
electrical rod and the third metal sheets form the third electrode;
a fourth electrical rod penetrating the third and fourth metal
sheets and electrically connecting the fourth metal sheets to the
second power supply, wherein the fourth electrical rod and the
fourth metal sheets form the fourth electrode; a plurality of
second insulators disposed on the third electrical rod for
providing electrical insulations between the fourth metal sheets
and the third electrical rod and disposed on the fourth electrical
rod for providing electrical insulations between the third metal
sheets and the forth electrical rod.
13. The water treatment system as claimed in claim 12, wherein the
third and fourth metal sheets are in the form of perforated
plate.
14. The water treatment system as claimed in claim 12, wherein the
third and fourth metal sheets are made of titanium or stainless
steel and coated with activated carbon, carbon nanotube, or
fullerene (C60).
15. The water treatment system as claimed in claim 14, wherein the
carbon nanotube or fullerene (C60) is directly grown on the metal
sheet.
16. The water treatment system as claimed in claim 12, wherein the
second insulator is a plastic screen or a plastic ring.
17. The water treatment system as claimed in claim 12, wherein the
third and fourth electrical rods are made of titanium.
18. The water treatment system as claimed in claim 1, wherein the
second power supply charging and discharging the second electrode
set reciprocally.
19. The water treatment system as claimed in claim 1, wherein the
second power supply including at least one supercapacitor.
20. The water treatment system as claimed in claim 19, wherein the
supercapacitor can amplify an input power by 10 times or more.
21. The water treatment system as claimed in claim 19, wherein the
supercapacitor includes a plurality of units that are divided into
two identical modules each has the same operational voltage and
capacitance to be switched reciprocally between charging and
discharging for providing consistent peak power to the second
electrode set.
22. The water treatment system as claimed in claim 1, the flow
through capacitor further comprising a housing for allowing subject
water flowing through the housing.
23. The water treatment system as claimed in claim 1, wherein the
flow through capacitor is submerged without a housing in an open
body of water.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to the elimination of ionic and
neutral contaminants from water by using low power consumption
without secondary pollution. More specifically, the invention
relates to an integration of two techniques, low voltage ozone
(O.sub.3) reactor and capacitive deionization (CDI) reactor, into a
continuous flow-through system for reducing the conductivity and
toxicity of various water.
[0003] 2. Background of the Related Art
[0004] Water bound contaminants may stay as a free form, an
emulsified form, dissolved but not dissociated, or dissolved and
dissociated species in water. Charge is the main property to
differentiate ionic pollutants from neutral ones. The objectives of
all water treatments are the reduction of total dissolved solid
(TDS), chemical oxygen demand (COD) and biological oxygen demand
(BOD), as well as colony forming unit (CFU) of bacteria and
viruses. TDS is a measure of ionic species, whereas the other
indexes are important for indicating the pollution degree of water
by neutral contaminants. In the removal of COD and BOD, N- and
P-containing nutrients and organic substances are the subjects to
be eliminated from domestic, industrial, agricultural and animal
wastewater. Among the foregoing contaminants, ammonia (NH.sub.3) is
the commonest compound produced from manufacturing processes or
biological activities. Ammonia dissolves easily in water as
unionized form (NH.sub.3) and ionized form (NH.sub.4.sup.+). The
unionized form is toxic to fish and other aquatic life, while the
ionized form is not. However, both forms of ammonia will cause
eutrophication to rivers, lakes and dams jeopardizing water sources
for human use. Currently, ammonia is widely removed from water by
using biological treatment as seen in U.S. Pat. Nos. 6,572,773;
6,929,942; 6,936,456; 6,936,708; 6,984,317; 6,984,323; 6,991,931;
7,001,516 and 7,001,519. Through adsorption or precipitation,
ammonia is removed chemically as described in U.S. Pat. Nos.
5,294,348; 6,838,069; 6,994,793 and 7,005,072. The chemical
treatment requires the use of expensive chemicals, and the
chemicals in turn become a source of pollution. Not only a carbon
source, a chemical, is needed for the growth of microbes, also the
biological treatment is a slow process conducted in a prescribed
conditions of pH, temperature, oxygen content and ammonia level.
Besides, the microbes can only take care ammonia at a concentration
of 700 mg/liter or lower.
[0005] In order to expedite the treatment speed of ammonia, as well
as to lower the cost of treatment, electrolytical techniques are
developed in U.S. Pat. Nos. 6,348,143; 6,712,947 and 6,984,326. As
a matter of fact, the electrolytical treatment utilizes the
reaction between halide ions and ozone to form hypohalite ions as
the reagent to oxidize ammonia. In terms of oxidizing power, ozone
is more potent than the hypohalite ions. It would be more effective
and convenient to use ozone directly for the decomposition of
ammonia, organic substances and pathogens. Ozone is used to control
the growth of red tide organisms on the surface of seawater in U.S.
Pat. No 6,984,330, and the gas is applied on mails and shipping
parcels for reducing the biological load including anthrax in U.S.
Pat. No. 6,984,361. All of the foregoing patents of ozone
applications rely on corona discharge for the generation of ozone.
In addition to high operating voltage (>2000 Volts), the silent
discharge requires an oxygen supply system, an ozone delivery
system and a protective shield against gas leak. As ozone does not
dissolve easily in water, the gas can only be dispersed water into
fine bubbles for effective oxidation. The high cost and the low
ozone solubility limit the corona-discharge ozone for broad
utilization in water treatments. To solve the foregoing problems,
ozone is directly generated in water by using a low voltage in
conjunction with a high current to electrolyze water as elaborated
in U.S. Pat. Nos. 6,984,295 and 6,984,304. But there are rooms for
improving the overall efficiency of ozone generation and
decontamination in the electrolytic ozone. For example, an
ion-exchange membrane is used in '304 to separate hydrogen from
ozone. The membrane is expensive and vulnerable to fouling. On the
other hand, patent '295 needs multiple electrodes and a design for
wastewater to flow through the reactor, so that ammonia and other
neutral contaminants can be decomposed concurrently with the
formation of ozone bubbles.
[0006] Two steps of reaction, that is, nitrification and
denitrification, are involved in the biological removal of ammonia.
Firstly, two bacteria species (Nitrosomonas and Nitrobacter
bacteria) are used to exothermically oxidize ammonia to nitrite
(NO.sub.2.sup.-) and nitrate (NO.sub.3.sup.-) under aerobic
conditions. Next, the anions are reduced by denitrifying bacteria
(facultative anaerobes) to nitrogen under anaerobic conditions. As
ammonia is completely ionized, the byproducts can be quickly
removed by a technique other than biological or chemical
treatments. In lieu of the complexity of wastewater, reverse
osmosis (RO) and ion exchange are not appropriate for the removal
of ionic contaminants from the water. The foregoing two methods are
particularly forbidden, if the ionic species are treated following
the ozone oxidation in a continuous sequence without using
chemicals and extravagant pretreatments. Both the membranes of RO
and the resins of ion exchange are easily fouled and impaired by
scaling, organic fouling, particulate fouling, and biofouling.
Virtually all wastewater can guarantee the occurrence of one or all
types of fouling. Capacitive deionization (CDI) is more
fouling-resistant than RO and ion exchange, and CDI is very
effective on removing the ionic species from water. CDI utilizes a
flow through capacitor (FTC) and a static electric field to purify
water containing ionized substances. As the wastewater pass through
the charged electrodes of FTC, the ions will be adsorbed on the
surface of electrodes. The power consumption of CDI treatment is
very minimal at ion removal, and the residual electricity can be
directly recovered at the regeneration of FTC electrodes as
revealed in U.S. Pat. Nos. 6,580,598 and 6,661,643. It is the
capacity of FTC that mainly determines the capability of CDI. In
U.S. Pat. No. 7,000,409, a commercial FTC is used to remove
NO.sub.3.sup.- and SO.sub.4.sup.2- for converting condensed water
of engine exhaust into potable water as a water source at arid
areas, such as, desert. Only a small range of TDS is reduced in
'409 indicating that the FTC employed is not suitable for
large-scale treatment of wastewater. A FTC of high throughput is
needed for integrating with the flow-through ozone reactor into a
continuous treatment system for on-line mass purification of
miscellaneous water containing both ionic and neutral
pollutants.
SUMMARY OF THE INVENTION
[0007] The present invention offers a continuous water-treatment
system consisting of flow-through ozone reactor, parallel-packed
flow-through-capacitor (FTC) for performing CDI, and supercapacitor
for the power management of both ozone reactor and FTC. The ozone
reactor and FTC each has a novel electrode set having the same
configuration and construction. However, different active materials
are used for the electrodes of ozone reactor and FTC.
[0008] The novel electrode set includes a plurality of identical
first metal sheets longitudinal parallel to each other; a plurality
of identical second metal sheets longitudinal parallel to the first
metal sheets, wherein the first metal sheets and second metal
sheets are arranged alternately; a first electrical rod penetrating
the first and second metal sheets and electrically connecting the
first metal sheets to a power supply, wherein the first electrical
rod and the first metal sheets form a first electrode; a second
electrical rod penetrating the first and second metal sheets and
electrically connecting the second metal sheets to the power
supply, wherein the second electrical rod and the second metal
sheets form a second electrode; a plurality of first insulators
disposed on the first electrical rod for providing electrical
insulations between the second metal sheets and the first
electrical rod and disposed on the second electrical rod for
providing electrical insulations between the first metal sheets and
the second electrical rod.
[0009] The metal sheet used in the ozone reactor is in the form of
mesh, screen, or porous plate. The holes on the electrodes allow
water to flow through in a closed housing. Or, the ozone reactor
without a housing can be submerged in an open water body to perform
in-situ detoxification. Each of the first and second electrodes of
the ozone reactor is attached to a separate electrical rod. Though
a plurality of metal sheets are disposed in a stack configuration,
the metal sheets of the same polarity are connected in parallel on
one electrical rod. The polarities of the electrical rods are
switched at a selected time interval, therefore, each metal sheet
can become anode to generate ozone. Not only the throughput of
ozone can be increased, but also the lifetime of electrodes can be
prolonged, and the electrodes can be protected from fouling.
Platinum metal, iridium oxide or synthetic diamond can be selected
as the active material deposited in thin film on the metal sheets
for generating ozone. The high current required for the generation
of ozone is delivered by supercapacitors via PWM (pulse width
modulation). During operation, the ozone reactor can work
continuously without the need of regeneration. The operational
voltage, ranging from 24 V to 3 V DC, of the ozone reactor depends
on the conductivity of water, while the operational current is
adjusted at a balance between the ozone production and electrode
life. High current is beneficial to the ozone throughput, but it is
detrimental to the adherence of the deposited or plated film of
active material.
[0010] FTC is the heart of CDI treatment with respect to both
performance and cost of the technique. The present invention
provides a stack configuration electrode set similar to that of the
ozone reactor for FTC. Therefore, the FTC can be operated in a
closed system, or it can be submerged in an open water body to
adsorb ions continuously as long as a DC current is supplied to the
electrodes of FTC. There are two distinctions between FTC and the
ozone reactor. One is the active material and the other is the
regeneration of electrodes. In FTC, an active material with large
surface areas, such as, activated carbon, carbon nanotube or
fullerene (C.sub.60), is employed for adsorbing ions. Because of
quick saturation of the electrodes by the adsorbed ions, FTC
requires constant regeneration. Otherwise, the saturated FTC
electrodes have no room for ion removal. The CDI treatment
comprises a series of charging and discharging swings of FTC.
Electricity can be directly recovered in the regeneration of FTC
with automatic de-sorption of ions that require a rinsing water to
exit the FTC. Obviously, incomplete flush of ions will jeopardize
the water quality of CDI treatment. Elimination of cross
contamination of CDI treatment is one objective of the present
invention. Similar to the ozone reactor, supercapacitor is also
employed in the power management system of CDI. The capacitor
performs a dual function of energy storage and energy delivery in
the reduction of TDS.
[0011] As described above, supercapacitor is a key component in
making CDI energy effective, as well as allowing ozone formation on
a small potential source. With quick charging and discharging
property, supercapacitor can serve as a power amplifier and power
buffer to deliver power needed at ozone oxidation and ion removal,
as well as to store energy at FTC available for recuperation. An
appropriate utilization of the effective energy of supercapacitor
will further improve the efficiency of power consumption in ozone
oxidation and CDI treatment.
[0012] A further aspect of the present invention is to integrate
the flow-through ozone with CDI into O.sub.3/CDI hybrid treatment
system for purifying water in a continuous operation. After a
simple filtration, all neutral contaminants existing in the intake
water will be first oxidized by the on-line O.sub.3 reactor into
gaseous and ionic products. The ion-loaded stream is then directed
into the FTC units for ion removal to become potable, reusable, or
dischargeable water. In the operation of O.sub.3/CDI hybrid water
treatment system, O.sub.3 will provide an oxidation equivalent to
incineration to neutral substances and microorganisms, while CDI
will adsorb all charged species with high recovery rate of water
and lower power consumption. The O.sub.3/CDI hybrid water treatment
can singly remove both ionic and neutral species, the most abundant
pollutants in water. No chemical is required for either O.sub.3 or
CDI treatment, thus, no secondary pollution will incur.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention is best understood by reference to the
embodiments described in the subsequent section accompanied with
the following drawings.
[0014] FIG. 1 is a schematic diagram of a cylindrical FTC for CDI
treatment taken from U.S. Pat. No. 6,462,935.
[0015] FIG. 2A shows a metal sheet with thickness t and through
holes of three different sizes, wherein the largest hole A is for
placing the plate on one electrical rod with electrical insulation,
B for electrical conduction between the plate and other electrical
rod, and C for water to flow through.
[0016] FIG. 2B is a diagram of insulator in form of insertion ring
IR for securing an electrode plate on one electrical rod.
[0017] FIG. 2C is a schematic diagram showing the connection of a
metal sheet with two electrical rods. The metal sheet has
electrical connection to one rod and electrical insulation with the
other.
[0018] FIG. 2D is a schematic diagram of electrode set of ozone
reactor or FTC.
[0019] FIG. 3 is a block diagram of O.sub.3/CDI hybrid water
treatment system for continuous water treatments.
[0020] FIG. 4 shows the TDS (total dissolved solid) reduction
curves of 10 inorganic salts by a tandem of five FTC (flow through
capacitor) modules.
[0021] FIG. 5A shows the decomposition of 1% ammonia water as
reflected by the increase of solution conductivity by a submerged
ozone reactor.
[0022] FIG. 5B shows the reduction of the conductivity of ozone
treated ammonia water by a single FTC.
DETAILED DESCRIPTION OF THE INVENTION AND BEST MODES
[0023] The preferred embodiments of each component of the
O.sub.3/CDI hybrid water treatment system of the present invention
are presented in the subsequent sections.
FTC (Flow Through Capacitor)
[0024] FTC is the heart of CDI where ions are removed so that the
TDS of water can be reduced to the desired levels. FIG. 1 shows a
prior FTC roll disclosed in U.S. Pat. No. 6,462,935, which is
currently owned by the assignee of the present invention. As shown
in FIG. 1, the FTC is constructed by winding two electrodes, 201
and 202 with two separators 203 concentrically around a central
water inlet 102 into a cylindrical roll. Before winding, each
electrode sheet is attached an electrical lead (not shown in FIG.
1) for connecting to an outside potential source. After winding,
both ends of the FTC roll are sealed hermetically. Water enters the
FTC roll from the holes provided on the tube 102, and exits the FTC
from the sidewall of the FTC roll. The thickness of the separator
203 defines the electrode gap that greatly affects the strength of
static electric field created by a potential applied across the two
electrodes. The smaller the gap the stronger the field will be, and
the more ions will be adsorbed and removed from water.
Nevertheless, a narrow electrode gap will restrict the water flow
in the FTC resulting in cross contamination to the FTC at
regeneration. When the treated water contains low ionic species,
for example, tap water, the cylindrical FTC as depicted in FIG. 1
can quickly remove ions and convert the hard water into soft water.
Even the raw tap water can be used to rinse the electrodes at
regeneration without degrading the capacity of FTC. On the other
hand, when the intake is seawater, the winding and long path of the
wound FTC shows the following difficulties: [0025] 1. Water
distribution at the holes of the central water inlet is non-uniform
resulting in a low efficiency of electrode utilization. In other
words, not every area of the electrode surface provided has been
utilized for ion adsorption leading to ion removal and TDS
reduction. [0026] 2. At the regeneration of FTC, the desorbed ions
are difficult to flush out, and some of them are trapped inside the
FTC, which significantly contaminate the water quality at the next
run of ion removal.
[0027] In order to solve the cross contamination and to improve the
electrode utilization rate, the present invention offers an
innovative design for the configuration of FTC. FIG. 2A shows the
building block of the new FTC design. A metal sheet of titanium or
stainless steel with thickness t is used as the substrate for
coating an active material to form an ion-adsorbing electrode. The
active material can be activated carbon, carbon nanotube (CNT) or
fullerene (C.sub.60). Alternatively, a carbon cloth can replace
both of the substrates and the active materials thereon as the
ion-adsorbing electrode by itself. If activated carbon is chosen as
the active material, it can be secured on the metal substrate via a
binder using roller or spin coating. However, the binder has an
adverse effect due to binder masking of the effective surface that
activated carbon can impart to the electrodes of FTC. Often, there
is as high as high as 60% of the carbon surface blocked by the
binder. Such disadvantage of binder can be eliminated by a direct
growth of CNT or C.sub.60 as the adsorbing material on the
substrate plates. An in-house study of fabricating binder-free
electrodes for the new FTC is in progress. There are three types of
perforated holes in different diameters on the electrode plate as
shown in FIG. 2A. Holes A and B are designed to secure the
electrode plate on two electrical rods, wherein A is for creating
an electrical insulation between the metal sheet and the rod, and B
is for making an electrical conduction between the metal sheet and
the rod. For the electrical insulation purpose, an insulator such
as a non-conductive plastic insertion ring is inserted at hole A.
On the other hand, hole B is made in the same dimension as the
electrical rod so that the metal sheet can be inserted snuggly on
the supporting rod forming a good contact and a low electrical
resistance. The third type of hole, C, is in a plural number and in
a diameter of 2 mm or less to allow water to flow through freely in
cascade from one metal sheet to subsequent metal sheets vertically
or horizontally. Other patterns of holes C on the metal sheet are
feasible if water retention time and water flow rate can be
optimally adjusted. If a carbon cloth is used as the electrodes of
FTC, holes C may not be needed as water may trickle through the
electrodes. Trickling is commonly seen in medium filters or
ion-exchange beds used in water treatments. The key of treatment is
dependent upon a high surface area to volume ratio.
[0028] FIG. 2B shows a preferred embodiment of a securing device
for attaching an electrode plate on two electrical rods. The device
is an insertion ring, IR, made of an insulating material, such as
plastic including polyethylene, polypropylene, Teflon, or Bakelite.
The outside diameter (OD) of the insertion ring IR is same as the
diameter of hole A on the electrode plate as shown in FIG. 2A,
while the inside diameter (ID) of IR is sufficient to hold a metal
ring with the same diameter as the electrical rod (the metal ring
is not shown in FIG. 2B for clearance). Therefore, the metal ring
can fit snuggly on both of the insertion ring IR and the electrical
rod. The thickness h of IR defines the electrode gap for the FTC of
the present invention. Other means capable of preventing electrical
short, and other ways capable of forming good electrical
connection, for the electrode plates and the electrode rods can be
used as well to construct the innovative FTC.
[0029] FIG. 2C shows the connection of a metal sheet with two
electrical rods R1 and R2 via the insertion ring IR. As mentioned
above, a metal ring at the middle of IR is not shown in FIG. 2C for
clearance. Every electrode plate of FIG. 2C attached to R1 through
hole B, as well as to R2 via hole A, will be sandwiched by two
insertion rings IR sitting on holes A of two electrode plates
hanged on the same electrical rod R1. The same configuration is
applied to every metal sheet that is attached to the electrical rod
R2 though hole B. The new FTC of the present invention is thereby
constructed by alternating the insertion of holes A and B of the
metal sheets on the electrical rods R1 and R2. In other words,
every two adjacent metal sheets are disposed on the electrical rods
with the hole A facing the hole B. The hole B of every metal sheet
is sandwiched by two holes A of two adjacent metal sheets, and vice
versa. A complete electrode set of the innovative FTC is shown in
FIG. 2D. Each electrical rod of R1 and R2 holds the same number of
metal sheets connected to their electrical rod in parallel,
respectively. When the whole stack of electrodes of the FTC of FIG.
2D are squeezed, each metal sheet will be in close contact with the
two metal rings in the two insertion rings IR sitting above and
below the hole B of that sheet. Since all metal sheets have the
same composition, they can serve as either positive or negative
electrode. The polarity of metal sheets is determined by the charge
applied to the electrical rod. Then, the rod and all of its
intimately connected plates via holes B will carry the same
polarity. In order to provide a good electrical contact for the
metal sheets and their supporting rod, two insulating plates F1 and
F2 are squeezed from both ends of the stack of metal sheets and
insertion rings using the four nuts N1 to N4. As the metal sheets
and the insertion rings are pressed against one another, the metal
rings in the middle of insertion rings will touch the metal sheets
tightly via holes B. Therefore, the metal sheets and their
supporting rod are connected electrically through the metal rings.
All nuts, metal rings, and electrical rods of the innovative FTC of
the present invention are made of a corrosion resistant metal, such
as, titanium. If copper or stainless steel is used for the
foregoing components, the metal should have a good protection
against corrosion. A FTC as depicted in FIG. 2D can be used to
conduct CDI treatments in a closed mode or an open mode. In the
closed mode, the FTC is enclosed in a housing, and water are
deionized upon flowing through the charged FTC. Alternatively, the
FTC of FIG. 2D can be placed in an open water body at any depth to
remove ions from the water using electricity from batteries or
renewable energies. No power station is needed for the open mode
FTC to operate at remote areas. The in-house studies have
discovered that the new FTC of FIG. 2D has a high efficiency of
electrode utilization, and the FTC is virtually free of cross
contamination.
[0030] Both types of FTC as depicted in FIG. 1 and FIG. 2D are
operated using the same protocol. When a plural number of FTC units
of FIG. 1 or FIG. 2D are employed for CDI treatment, they are
charged in parallel to remove ions from water, therefore, only one
voltage is required to charge every FTC unit in the pack in
operation. Depending on the conductivity of water to be treated,
the operational voltage can be set from 1V to 9V DC. The higher the
conductivity, the lower the voltage will be. When the FTC units
become saturated as indicated by the decrease of charging current,
and the FTCs require regeneration. During regeneration, at least
30% of the electricity input for ion removal can be directly
recovered and stored for latter use. The energy recovery is
accomplished simply by connecting the saturated FTCs to a load, for
example, supercapacitor. At the discharge of FTCs, the adsorbed
ions will automatically leave the electrodes and become collectable
for reuse or easy disposal. As FTCs are discharged, they are
electrically connected in series to expedite the recovery of
electricity accompanied with complete de-sorption of the adsorbed
ions.
Flow Through Ozone Reactor
[0031] The present invention also applies the electrode set of
stacking configuration as FIG. 2D for the construction of an
innovative ozone reactor that can generate ozone directly in water.
Furthermore, all components and fabricating processes for the ozone
reactor are similar to those for the innovative FTC as described
above. Nevertheless, there are some distinctive differences between
the FTC as depicted in FIG. 2D and the new ozone reactor. The
differences are summarized as follows: [0032] 1. Titanium metal is
the substrate for the ozone reactor, whereas the FTC can use a
cheaper substrate, such as, stainless steel. The environments in
the ozone reactor is extremely harsh, thus, titanium is required to
resist the oxidative corrosion. [0033] 2. Platinum, iridium oxide,
or synthetic diamond film is the active material for the ozone
reactor, whereas carbonaceous material serves as the ion-adsorbing
medium for the FTC. Ozone is generated on the aforementioned
precious material when the material is charged as anode. [0034] 3.
The electrodes of the ozone reactor can be in the form of mesh,
screen or plate, whereas the electrodes of FTC has smaller openings
relatively. [0035] 4. The ozone reactor can remove numerous neutral
contaminants resulting in the reduction of BOD and COD through
complete oxidation, whereas the FTC removes ionic species resulting
in the reduction of TDS via surface adsorption. [0036] 5. The ozone
reactor can continuously remove BOD and COD without the need of
regeneration, whereas the FTC requires frequent cleaning. [0037] 6.
The ozone reactor provides a non-selective and destructive
treatment, whereas the FTC offers a non-destructive treatment, and
different ions may be adsorbed and released at different stages of
CDI operation. [0038] 7. Power is consumed at the ozone reactor,
whereas residual power can be directly, without energy conversion,
recovered from the FTC during regeneration. [0039] 8. The electrode
polarities of the ozone reactor are switched at a preset time
interval, whereas the FTC is switched between charging (to adsorb
ions) and discharging (to regenerate the electrodes) at a longer
time interval.
[0040] In addition to the same configuration of electrode assembly,
the ozone reactor and the FTC of the present invention also share
the use of supercapacitor as a key component for power management.
For saving energy, both of the ozone reactor and the FTC are
operated using PWM (pulse width modulation) instead of continuous
power provision. Not only the water treatments are more energy
effective on using PWM, a balance state that may exist in ozone
formation and ion adsorption can be disrupted via the intermittent
power supply. As a result, water treatments for reducing TDS, COD
and BOD of water using CDI and flow-through ozone may be
facilitated by applying the PWM technique. Similar to the FTC of
FIG. 2D, the ozone reactor can be operated in either closed or open
mode. The constant polarity switching of the new ozone reactor is
designed to provide the following benefits to the ozone treatment:
[0041] 1) Every electrode disposed in the reactor can serve as the
anode to generate ozone in water. [0042] 2) Since the electrodes
work only "half" of the operation time as anode, their service life
can be prolonged. [0043] 3) Fouling of electrodes is inhibited due
to every electrode will become the anode thereon deposits will be
destroyed by ozone.
[0044] The innovative ozone reactor of the present invention does
not use any ion exchange membrane. Although the membrane can
separate ozone from hydrogen resulting in a higher oxidant
concentration, but the membrane is expensive and vulnerable to
scaling and particulate fouling. If a membrane is employed in the
new ozone reactor of the present invention, neither the closed mode
ozonation, wherein water flows through the reactor sitting in a
housing, nor the open mode ozonation, wherein the reactor is
submerged in an open body of water at any depth, is allowed due to
the blockage of water flow by the membrane or quick fouling of
membrane, respectively. During either mode of ozonation, the ozone
reactor is surrounded by contaminants, and the latter will react
with ozone as soon as the micro bubbles of the oxidative gas are
formed. Because of the close proximity, the reaction between
contaminants ozone will be faster than that between ozone and
hydrogen. In other words, there is a plentiful amount of ozone in
water for the in-situ destruction of contaminants. The in-house
studies have found the distinctive odor of ozone in the water
stream after it passed the ozone reactor. On the other hand, the
presence of hydrogen may be beneficial to the removal of any
reducible pollutants in the water to be treated. Ozone can provide
a complete oxidation with destructive effect equivalent to
incineration, therefore, all neutral contaminants will be converted
to gaseous, ionic, or a mixed products in a less toxicity than the
original pollutants. Once the pollutants become ionic species, the
FTC will quickly remove the ionic byproducts from water. Similar to
the CDI treatments, the operational voltage of the ozone reactor
depends on the conductivity of water to be treated. Generally, the
voltage is less than 24V DC. If the treated water is extremely
conductive, for example, seawater, it is preferred set the voltage
no more than 5V DC to avoid an excess current applied to the ozone
reactor. When the current density is above 1 A/cm.sup.2, the ozone
forming materials, such as, platinum and iridium oxide, may peel
off the titanium substrate. Ozone concentration in water is
sensitive to water temperature, and low water temperature can
stabilize the presence of ozone in water. Thus, water circulation
due to the flow-through operation will keep the water temperature
of the ozone reactor low and constant, and the water movement will
promote the oxidation of pollutants as well. Under the condition of
high halide ion concentrations, for example, 50 ppm or above, the
flow-through ozonation of the present invention will generate
hypohalite ions in addition to ozone. Nevertheless, the hypohalite
ions are also potent oxidants for the removal of BOD and COD. The
hypohalite ions can stay in water at a much longer time than ozone,
and water containing the disinfecting anions is good for storage
and transportation as a bactericide. More importantly, the
hypohalite ions of the present invention are produced on-line and
the residual ions after the disinfection can be removed by CDI.
Supercapacitors
[0045] As described in the foregoing sections, supercapacitor is a
key component for managing the power utilization in the operations
of the new FTC and the new ozone reactor of the present invention.
Supercapacitor receives its name of "super" from its capability of
storing hundreds to thousands times energy of the conventional
capacitors. Like the latter, supercapacitor is a passive
energy-storage device with fast charging and discharging rates.
However, due to the large capacitances in a small volume,
supercapacitors have the following unique properties as added
values. [0046] 1. Within the rated working voltages, the capacitors
can be charged with any magnitude of currents. Henceforth, the
residual current of saturated FTC units, large or small
electricity, can be quickly and completely transferred to
supercapacitors for storage for latter use. By discharging the
saturated FTC units in series, the transfer of the residual energy
of FTC to supercapacitors can be expedited. Desorption of the
adsorbed ions from the electrodes of FTC is promoted as well.
[0047] 2. When the FTC units and the ozone reactors of the present
invention demand large currents for operation, supercapacitors can
fulfill the needs in a real-time response. This will save the cost
of water treatments for a power supply with large current output,
for example, 50 A or above, is very expensive. By the provision of
low currents from an economical potential source, supercapacitors
can deliver tens times of current for large-scale water treatments.
Because the load for the potential source is low, fire hazard is
thus prevented. [0048] 3. Supercapacitors can deliver a power at
many folds of an input power without energy conversion and
electrical components, such as, transformer and converter. On the
other hand, supercapacitors can serve as energy buffer for storing
the energy recovered from the regeneration of FTC. The energy
storage of supercapacitors is conversion free as well. Energy is
directly deposited and withdrawn at a very minimal loss. Using
supercapacitors for the power management of water treatments, the
energy consumption of the treatments will be highly cost effective.
[0049] 4. Supercapacitors have a long lifetime without maintenance.
The capacitors also have good temperature characteristics and
outdoor suitability. Supercapacitors are known to assist the
ignition of engines at frigid temperatures. [0050] 5. The working
voltage of supercapacitors is low, which is consistent with the low
operational voltages of the FTC and the ozone reactor of the
present invention. Low operational voltage allows the water
treatments to be driven by batteries, fuel cells, and renewable
energies (e.g., solar cells and wind turbines). The latter
potential sources are generally low in power output that can be
easily compensated by the use of supercapacitors.
[0051] As a matter of fact, the FTC as depicted in FIG. 1 has the
same configuration of supercapacitor. Both capacitive devices
require an electrolyte to perform. The electrolyte provides ions
for adsorption and desorption at charging and discharging of the
capacitors, respectively. The major difference between the FTC and
supercapacitor is that the electrolyte for FTC is the running water
to be treated, whereas the electrolyte is sealed permanently in the
housing of supercapacitor. As large electrode areas of FTC, which
is attained by using plural FTC units, are required for desalting
industrial wastewater, supercapacitors must be connected in series
to cope with the high voltage created in the discharging of FTC
units in series. Charging of serially connected supercapacitors at
the regeneration of FTC may create an imbalance distribution of
voltage among the capacitors. The capacitor with the highest
voltage will fail first dragging the whole pack down with it. An
assembly method of connecting the supercapacitor elements within a
single housing can solve the problem of voltage imbalance. The
foregoing in-cell series assembly provides a uniform temperature
and vapor pressure environments for all supercapacitors in the
housing. Therefore, the whole pack of capacitors is charged as one
unit resulting in equal share of the total voltage. The automatic
even distribution of voltage prevents the use of protection
circuits for each supercapacitor of the serially connected pack.
Like other energy-storage devices, not every bit of energy stored
in supercapacitors is potent to work. During the discharge of a
supercapcitor, if the voltage of supercapacitor has decayed to
under the working threshold, the rest of energy in the capacitor
will be ineffective. By cycling two identical groups of
supercapacitor between charging and discharging, or charging and
discharging swing (CD swing), only the effective energy of the
supercapacitors will be utilized and replenished leading to energy
conservation. In the operation of CD swing, at all times, there
will be one group of supercapacitors undergoing discharge in
synchronization with the other group at recharging. As the
discharging group has consumed its effective energy, it will
undergo recharging (to refill the used portion) and the other group
(after the replenishment of energy) will immediately take the
discharging position, and vice versa. Due to the continuous
discharge of capacitors, the power supply using the CD swing can
consistently deliver peak powers to water treatments under the PWM
and other controls as proposed by the present invention. The CD
swing is designed to improve the energy efficiency of the
supercapacitor for power applications, which in turn will reduce
the energy cost of water treatments on incorporating the capacitors
in the power supply system. Incidentally, the CDI operation is also
a CD swing, that is, plural FTC units are periodically and
reciprocally switched between charging and discharging. While
desalted water is produced at the charging of FTC units (in
parallel), FTC units are regenerated in conjunction with the
recovery of electricity and ions at the discharging of FTC units
(in series).
O.sub.3/CDI Hybrid Water Treatment System
[0052] The flow through ozone reactor, the FTC, and DC power
supplies using the supercapacitors operated via CD swing are
integrated to form a preferred embodiment of compact and
self-sustained water treatment system as shown in FIG. 3. As seen
in the drawing, the intake water will be pumped at an inlet 1 into
the O.sub.3/CDI hybrid water treatment system. After simple
filtration at the filter 2, which can consist of sand, charcoal,
activated carbon, or other inexpensive filtering media, the water
will be treated at the flow through ozone reactor 3. All the
neutral contaminants in the water will be oxidized in a circulation
between reactor 3 and a storage tank 4 until all neutral pollutants
are decomposed completely into gaseous and ionic products. The
ozonated water is then degassed and filtered at filter 5 for
further treatment by a FTC unit 6. During the ozonation, some
original ion, for example, Fe.sup.2+, will be oxidized to form a
fine precipitate, for example, Fe.sub.2O.sub.3. Therefore,
filtering the precipitate becomes necessary before the CDI
treatment. Other original non-oxidizable ions plus the ozonation
ions can be removed and collected at FTC 6. The CDI treatment via
FTC 6 can be operated till the desired TDS is reached, then, the
treated water is discharged at an outlet 7. From inlet 1 to outlet
7, the intake water is treated continuously by on line ozonation
and deionization without the addition of any chemical. As described
in the section of flow-through ozone reactor, the reactor is
capable of cleaning itself for continuous operation. On the
contrary, the FTC unit though requires frequent regeneration and
rinsing, the process is completed through discharging to the
supercapacitor without using any chemical. Therefore, the
O.sub.3/CDI hybrid water treatment system offers chemical free and
pollution free water treatments. Moreover, there is no limitation
on the concentration of neutral species, such as, ammonia, nor on
the ion contents of water that can be treated by the O.sub.3/CDI
hybrid water treatment system of the present invention. Without
dilution, water as concentrate as seawater can be directly
desalinated to potable water by the system of the present causing
no damage to the ozone reactor or the FTC unit.
[0053] FIG. 3 is used to elucidate the O.sub.3/CDI hybrid water
treatment system rather than restricting the scope of application
of the present invention. For treating industrial wastewater of
10,000 m.sup.3 or more per day, both ozone reactor and FTC unit can
be scaled up by increasing the dimensions of both types of
electrodes, the number of metal sheet pairs as depicted in FIG. 2D,
as well as by using plural ozone reactors and FTC units. Since the
ozone throughput and ion adsorption rate are proportional to the
total available electrode areas, the scale up of the O.sub.3/CDI
hybrid water treatment system is straightforward for any scale of
water treatments. A microprocessor controller, not shown in FIG. 3,
is used for controlling the ozonation, deionization, interface
between the two treatments, and power management. With the use of
controller, a turn-key system of O.sub.3/CDI hybrid water treatment
techniques is erected and the system can be operated automatically
with very minimal human attention. Due to the chemical free
operation, as well as the concise sizes of ozone reactor and FTC
unit, the O.sub.3/CDI hybrid water treatment system will occupy a
much smaller space area than the current water treatment techniques
on the market, for example, ozonation by corona discharge,
desalting by RO or ion exchange. Small space area means low cost
for the water treatments. Also, the O.sub.3/CDI hybrid water
treatment system can be easily retrofitted with an existing water
treatment system. Using the system of the present invention as a
non-chemical pretreatment for an existing water treatment facility,
the expenditure for the expensive RO membranes and ion exchange
resins will be greatly reduced. Supercapacitors are not shown in
FIG. 3, but they are included in the DC power supplies of the
drawing. According to individual power management, specific
switching power supply (SPS) for any scale of water treatments can
be built using the supercapacitor as the power electronics. After
the power need for a water treatment is determined, the capacity of
power provision of supercapacitors and the potential source to
charge the capacitors can be design accordingly. The foregoing
custom made SPS can offer the power needs for water treatments with
the highest energy efficiency and the lowest cost.
[0054] The ozone reactor and FTC of the present invention utilize
the same configuration of electrode stack as shown in FIG. 2D,
which allows water treatments to be conducted in a closed mode or
an open mode. FIG. 3 represents a closed mode operation wherein
both ozone reactor and FTC electrodes are enclosed in a housing.
Water flow though the closed system to receive ozonation and
deionization in sequence without exposing to air. Such closed
system can be set at a designated station, or it can be installed
on a truck, pick-up or trailer to become a mobile system for
driving to wherever a treatment is demanded, for example, business
promotion or emergency rescue. The potential source for operating
the ozonation and deionization may come from batteries, renewable
energies or generators. As the rinsing water for regenerating the
FTC units, it can come from a small portion of the purified
effluent of the O.sub.3/CDI hybrid water treatment system. The
rinsing water may be used repeatedly until it causes significant
cross contamination. Even at the end of service, the rinsing water
may join other wastewater for purification by the O.sub.3/CDI
hybrid water treatment system. Henceforth, the water treatment
system of the present invention has a water recover rate higher
than 90%. When both ozone reactor and FTC unit use the
configuration of FIG. 2D without housings, they will become an open
mode ozonation and deionization. The open ozone reactor and FTC
unit can be submerged in water at any depth to purify water
surrounding the hybrid water treatment system, or water flowing
through the hybrid system. Although water may not be treated in the
sequence of deionization after ozonation, the pollutants in water
will be oxidized or adsorbed. The open mode water treatment
requires no pump, conduits and storage tanks. By installing the
open ozone reactors and FTC units at the bow and stem, as well as
by the starboard and port of a boat, a mobile water-treatment
system on watercraft is formed. To prevent solids entrapped between
electrodes, a mesh screen is provided for each ozone reactor and
FTC unit. Since only low levels of ozone, for example, 10 ppb to 10
ppm, are required for the destruction of neutral pollutants and
algal species in the water body of a river, and the ozone level can
be controlled by the power supplied to the reactors, release of
excess ozone into the atmosphere is minimal. Thus, adverse effects
of ozone on human, marine life and the environments are greatly
reduced. Similar situation is applied to the FTC unit of the
present invention for a low power, for example, 3V.times.2 A or 6
W, is needed to remove ionic contaminants that are diluted by the
river water. The low power application significantly reduces the
hazard of electrical shock to human and marine life. When the FTC
units become saturated, the saturated units can be pulled to the
deck for regeneration, at the same time, regenerated units can be
submerged into water for ion adsorption.
[0055] The practice of the present invention can be better
understood by reference to the following examples, which are
provided to illustrate the performance of ozone reactor and FTC
unit individually and collectively.
EXAMPLE 1
[0056] 10 different reagent grade salts: CuSO.sub.4, FeSO.sub.4,
Ca(NO.sub.3).sub.2. Fe(NO.sub.3).sub.2, Al(NO.sub.3).sub.3,
NaNO.sub.3, Zn(NO.sub.3).sub.2, K.sub.3PO.sub.4, Na.sub.3PO.sub.4
and NaCl, are individually dissolved in 1 liter deionized water to
form 10 pure solutions with TDS ranging from 700 to 1000 ppm. Each
solution is deionized on 5 serially connected units of cylindrical
FTC, as shown in FIG. 1, individually sealed in a plastic housing
with a capacity of 600 ml. During test, each solution flows through
the FTC pack continuously at 1 l/min. Each FTC has a geometric area
of 1400 cm.sup.2 for each electrode to form the FTC roll, and 3V DC
is applied across the two electrodes of FTC for ion removal. Since
the 5 units of FTC are charged in parallel, every FTC will receive
3V of charging voltage. The total charging current is about 6A.
FIG. 4 shows the reduction of TDS for each salt after 3 cycles
wherein every cycle contains 3 minutes of charging for deionization
and 2 minutes of discharging and rinsing for regeneration. Except
the salts containing SO.sub.4.sup.2-, the TDS of other solutions is
reduced to below 200 ppm showing that many cations and anions are
easily removed by CDI. The removal of SO.sub.4.sup.2- and the
overall desalting rate of the solutions may be improved by using a
higher voltage for deionization.
EXAMPLE 2
[0057] 1.5 liters of 1% ammonia (NH.sub.3) water is prepared for
ozonation using an ozone reactor as revealed in U.S. Pat. No.
6,984,295, which is currently owned by the assignee of the present
invention. A pair of platinum coated titanium meshes, each is 10 cm
wide by 10 cm long with opening of 3.5 mm.times.6.5 mm, is used to
form the ozone reactor. The ozone reactor is placed in the
container of 1.5 liters ammonia water under the application of 8.5V
average voltage and 1.75 A average current and PWM control. Only
the TDS of the ammonia water during ozonation is measured, and the
hourly variation of TDS is shown in FIG. 5A. About 6 hours since
the ozonation is began, the TDS of solution levels off indicating
that the decomposition of ammonia by ozone has been completed. Most
ammonia may be decomposed by ozone according to the following
equation:
##STR00001##
[0058] Next, the ozonated water is deionized using a single FTC
unit as example 1, as well as 3V DC for deionization. TDS of the
water is reduced smoothly from 600 to 150 ppm as shown in FIG. 5B.
Since TDS of the solution is reduced steadily indicating that no
free ammonia molecule is available, otherwise, ammonia will be
electrolyzed resulting in the increase of TDS. There are four
segments of TDS reduction in FIG. 5B. At segments A and C, FTC was
rinsed with tap water, but at segment B, FTC was rinsed with
deionized water. About 500 ml of tap water or deionized water was
used for rinsing. At segment D, a new FTC was used and it was
rinsed with tap water afterwards. When a new FTC is employed, a
sudden drop of TDS is observed. Thus, cross contamination is a
nuisance to the deionization capability of FTC made by winding as
FIG. 1. Using a clean water, such as, deionized water, for rinsing
the FTC will minimize the cross contamination. This is reflected by
a faster reduction of TDS at segment B. Other means including more
clean water for rinsing, or plural FTC units for treatment, can
also ease the contamination. Nevertheless, EXAMPLE 2 demonstrates
that the O.sub.3/CDI hybrid technique can quickly treat high
ammonia concentration water to potable level at low energy
consumption and without the use of any chemical or any bacteria.
During treatment, the neutral ammonia molecules should be oxidized
before being deionized, so that the molecules would not be
electrolyzed at CDI operation to impair the current efficiency.
EXAMPLE 3
[0059] 6 g of ammonia is dissolved in 2 liters tap water, which is
mixed with 1 liter of filtered seawater (TDS=35,000 ppm). The
salted ammonia water as prepared is first oxidized using an ozone
reactor with electrode configuration of FIG. 2D concealed in a
plastic housing as EXAMPLE 1. Iridium oxide (IrO.sub.2) is used as
the ozone-forming material coated on titanium mesh, which has an
opening of 1.5 mm.times.3.0 mm. A total of 32 pieces IrO.sub.2/Ti
disk electrodes of 5.3 cm diameter are disposed in the housing. The
power for ozonation is set at 12V.times.10 A with the electrode
polarities switched once every minute. The ammonia brine is
circulated between the ozone reactor and a reservoir Table 1 lists
the hourly variation of TDS, pH, voltage and current of
ozonation
TABLE-US-00001 TABLE 1 Ozonation of ammonia brine using an iridium
oxide ozone reactor Time (hr) TDS (ppm) pH Voltage (V) Current (A)
0 11,030 10.4 3.8 10 1 12,300 9.90 3.9 10 2 12,300 9.70 3.9 10 3
12,300 9.20 3.9 10 4 12,500 7.90 4.0 10 5 12,400 8.17 4.0 10 6
12,400 8.18 4.0 10
[0060] If 2 liters tap water is mixed with 1 liter seawater, the
mixture has alkalinity of pH 7.6. As soon as ammonia is added to
the foregoing mixture, pH of the mixture jumps to 10.4. With the
progress of ozonation, pH of the ammonia brine is decreasing. Thus,
a complete oxidation of ammonia should be reached between the
3.sup.rd and 4.sup.th hour ozonation according to Table 1. If the
weight ratio between ammonia and ozone is 1:1, the ozone reactor of
the present reactor should generate more than 1.5 g of ozone per
hour. A neutral pH levels, all neutral ammonia molecules in water
will turn ammonium (NH.sub.4.sup.+). The pH of water should be at
least 10.5 for ammonia to be stripped as vapor. The applied current
for ozonation is fixed at 10 A, whereas the operational voltage is
automatically determined by the conductivity of water. Due to
constant circulation, the water temperature varies between
23.degree. C. and 25.degree. C., which is very close to the ambient
temperature. After ozonation, the oxidized water is subjected to
deionization using stack configuration as FIG. 2D for the FTC as
well. The foregoing FTC contains 80 pieces of titanium disk plates
(0.5 mm thickness and 5.3 cm diameter with a pattern of perforated
holes as depicted in FIG. 2A) coated with activated carbon as the
ion-adsorbing material. The disk electrodes are divided in two
groups, and each group is electrically connected to an electrical
post. A potential of 3V DC is applied across the two posts for
desalting the oxidized water of Table 1. In 30 cycles of CDI
operation, TDS of the water is reduced from 12,400 to 400 ppm.
Treatment of 3 liter wastewater containing 2000 ppm ammonia and at
least 10,000 ppm salt, which is beyond the capability of the
biological method and RO without chemicals, is successfully
accomplished in a no pollution fashion by the O.sub.3/CDI hybrid
technique of the present invention.
EXAMPLE 4
[0061] 20 liters of wastewater of a steel plant is treated to
reduce its COD from 314 ppm to below 100 ppm. The water was first
oxidized then desalted on a O.sub.3/CDI hybrid unit as shown in
FIG. 3. Table 2 shows the results at each stage of treatment:
TABLE-US-00002 TABLE 2 Reduction of the COD of a wastewater,
original COD = 314 ppm, by O.sub.3/CDI Total Electrode Power
Treatment COD Treatments Area (cm.sup.2) (V .times. A) Time (ppm)
Ozonation 100 5 .times. 20 1 hour circulation 235 CDI 30,000 6.5
.times. 14 One pass 90
Table 2 indicates that the total electrode area for the ozone
reactors is much smaller than that for CDI, and it is reflected by
the degree of COD reduction. Since the water contains NH.sub.3,
which is oxidized to NO.sub.2.sup.- or NO.sub.3.sup.- during
ozonation, CDI will have a faster removal rate for the ions than
the oxidation of ions by O.sub.3. The flow of water was 1.5 l/min
for both treatments, and it took about 13 minutes for the treated
water to pass through the FTC modules. Had the water allowed to
pass the FTC units one more time, the COD would be reduced further.
No chemical or bacteria is used, therefore, the treatments by
O.sub.3/CD are clean, economical and fast.
Conclusion
[0062] From the above examples and other in-house tests, the
present invention clearly provides a solution of chemical free, low
energy consumption and low space area for various water treatments.
Removal of TDS, COD and BOD can be completed in one line or in open
water body. Expansion of the O.sub.3/CDI hybrid system for any
scale of water treatment is straightforward and easy. Both of the
ozone reactor and FTC unit are modular, they can be added with the
increasing amount of water for treatment. All materials used for
constructing the ozone reactor and FTC unit are environmental
friendly, and the metal components are recyclable. Electricity is
used to generate ozone, as well as to control the adsorption and
desorption of ionic contaminants in a clean, fast and high
efficiency state. Supercapacitor is used in the custom design of
the power needs of the O.sub.3/CDI hybrid water treatment system
leading to energy conservation and high dependability. As no
chemical or bacteria is used, ions remain in the original states
and become recyclable at the FTC unit of CDI treatment. Even the
common salt of seawater is a precious resource to human life and
animal life, as well as to many industrial productions. The
application of the O.sub.3/CDI hybrid system of the present
invention is almost endless. Most importantly, the system offers a
natural and economical solution for water treatments.
* * * * *