U.S. patent application number 13/784618 was filed with the patent office on 2013-09-26 for waste to product on site generator.
The applicant listed for this patent is MIOX Corporation. Invention is credited to Craig Andrew Beckman, Thomas Edward Muilenberg, Justin Sanchez.
Application Number | 20130248375 13/784618 |
Document ID | / |
Family ID | 49083383 |
Filed Date | 2013-09-26 |
United States Patent
Application |
20130248375 |
Kind Code |
A1 |
Sanchez; Justin ; et
al. |
September 26, 2013 |
Waste to Product On Site Generator
Abstract
Method and apparatus for adjusting the salinity and/or hardness
of a process waste stream so that the stream may be electrolyzed to
form an oxidant or disinfectant. Also an electrolytic cell having
certain features such as widely spaced electrodes, flushing
capabilities, and insulating dividers that can accommodate waste
streams that have varying salinity, hardness, and dissolved solids
content.
Inventors: |
Sanchez; Justin;
(Albuquerque, NM) ; Beckman; Craig Andrew;
(Albuquerque, NM) ; Muilenberg; Thomas Edward;
(Ames, IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MIOX Corporation |
Albuquerque |
NM |
US |
|
|
Family ID: |
49083383 |
Appl. No.: |
13/784618 |
Filed: |
March 4, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61605929 |
Mar 2, 2012 |
|
|
|
Current U.S.
Class: |
205/335 ;
204/275.1; 205/334; 205/350; 205/351 |
Current CPC
Class: |
C02F 2303/14 20130101;
C02F 2209/05 20130101; C02F 2201/4612 20130101; C02F 2209/40
20130101; C02F 2209/055 20130101; C02F 1/4674 20130101; C25B 9/00
20130101; C02F 2201/46145 20130101; C02F 1/006 20130101; C25B 15/08
20130101 |
Class at
Publication: |
205/335 ;
205/334; 205/351; 204/275.1; 205/350 |
International
Class: |
C25B 15/08 20060101
C25B015/08 |
Claims
1. A method for producing an oxidant, the method comprising:
adjusting the salinity and/or hardness of a waste stream thereby
forming a brine solution; and electrolyzing the brine solution to
produce at least one oxidant.
2. The method of claim 1 wherein the adjusting step comprises
measuring the salinity and/or hardness of the waste stream.
3. The method of claim 1 wherein the adjusting step comprises
adding water or processed water to the waste stream to reduce the
salinity of the waste stream.
4. The method of claim 1 further comprising varying the relative
flow rates of the waste stream and the water or processed water
being input into an electrolytic cell.
5. The method of claim 1 wherein the adjusting step comprises
adding a saturated or near saturated salt solution to the waste
stream to increase the salinity of the waste stream.
6. The method of claim 1 further comprising varying the relative
flow rates of the waste stream and the saturated or near saturated
salt solution being input into an electrolytic cell.
7. The method of claim 1 wherein the adjusting step comprises
treating the waste stream by a method selected from the group
consisting of softening, ion exchange, filtering, and reverse
osmosis.
8. The method of claim 1 wherein the brine solution has a salinity
between approximately 10 g/L and 40 g/L.
9. The method of claim 1 wherein the adjusting step reduces a
cleaning frequency of the electrolytic cell.
10. A method for cleaning an electrolytic cell, the method
comprising: measuring a salinity and hardness of a waste stream to
be electrolyzed; calculating a frequency for cleaning the
electrolytic cell based on the measured salinity and hardness of
the waste stream and a spacing between electrodes of the
electrolytic cell; and cleaning the electrolytic cell in accordance
with the calculated frequency.
11. The method of claim 10 wherein the cleaning step comprises
reversing a polarity of the electrolytic cell.
12. The method of claim 10 wherein the cleaning step comprises
flushing solid contaminants from the electrolytic cell.
13. The method of claim 12 wherein the solid contaminants are
flushed from the electrolytic cell once or twice a day or after the
electrolytic cell was cleaned by reversing the polarity of the
electrolytic cell.
14. The method of claim 10 further comprising adjusting the
salinity and/or hardness of the waste stream, thereby reducing the
cleaning frequency.
15. An electrolytic cell for electrolyzing a waste stream, the
electrolytic cell comprising: one or more devices for adjusting a
flow rate of the waste stream entering an electrolytic cell; one or
more dispersion tubes for transporting the waste stream into said
electrolytic cell; a plurality of holes in said dispersion tubes,
said holes angled to direct a flow of the waste stream toward
bottom edges of said electrolytic cell; and one or more insulators
substantially parallel to electrodes in said electrolytic cell and
extending from a bottom of said electrolytic cell to at least a
level of bottoms of said electrodes.
16. The electrolytic cell of claim 15 wherein the additive stream
comprises water, processed water, a saturated salt solution, or a
near saturated salt solution.
17. The electrolytic cell of claim 15 wherein at least one of the
devices can flush the cell with the waste stream or water at a
flushing flow velocity higher than an operational flow velocity of
the waste stream.
18. The electrolytic cell of claim 17 wherein the flushing flow
velocity is at least twice the operational flow velocity.
19. The electrolytic cell of claim 15 wherein spacing between
adjacent holes is between approximately 0.5'' and approximately
2''.
20. The electrolytic cell of claim 15 comprising electrodes which
are spaced more widely than electrodes in an electrolytic cell
designed to produce a similar quantity and strength of oxidants
from a controlled brine stream.
21. The electrolytic cell of claim 20 comprising intermediate
electrodes, wherein spacing between adjacent intermediate
electrodes of between approximately 0.15'' and approximately
0.5''.
22. The electrolytic cell of claim 21 wherein said spacing is
0.25''+/-0.1''.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of
filing of U.S. Provisional Patent Application Ser. No. 61/605,929,
entitled "Waste to Product On Site Generator," filed on Mar. 2,
2012, the specification and claims of which are incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention (Technical Field)
[0003] The present invention relates to methods and apparatuses for
electrolytic processing of waste brine solutions produced by water
purification or other industrial processes, thereby producing one
or more oxidants and/or disinfectants.
[0004] 2. Background Art
[0005] Note that the following discussion refers to a number of
publications and references. Discussion of such publications herein
is given for more complete background of the scientific principles
and is not to be construed as an admission that such publications
are prior art for patentability determination purposes.
[0006] Electrolytic technologies utilizing dimensionally stable
anodes have been developed to produce oxidant solutions from brine
solutions, and these technologies have grown in market presence and
interest across a variety of applications. Dimensionally stable
anodes are described in U.S. Pat. No. 3,234,110 to Beer, entitled
"Electrode and Method of Making Same," wherein a noble metal
coating is applied over a titanium substrate. Electrolytic cells
have had wide use for the production of chlorine and mixed oxidants
for the disinfection of water. Some of the simplest undivided
electrolytic cells are described in U.S. Pat. No. 4,761,208,
entitled "Electrolytic Method and Cell for Sterilizing Water", and
U.S. Pat. No. 5,316,740, entitled "Electrolytic Cell for Generating
Sterilizing Solutions Having Increased Ozone Content." One
limitation of these technologies is the operating cost associated
with the feedstock of this process, consisting of sodium chloride
and other dissolved salts which are converted into solutions
comprising at least one oxidant. It is well accepted that one of
the major failure mechanisms of undivided electrolytic cells is the
buildup of unwanted films on the surfaces of the electrodes. The
source of these contaminants can be either from the feed water to
the on-site generation process, or contaminants in the salt that is
used to produce the brine solution feeding the system. Typically
these unwanted films consist of manganese, calcium carbonate,
silica, or other unwanted substances. If buildup of these films is
not controlled or they are not removed on a fairly regular basis,
the electrolytic cells will lose operating efficiency and will
eventually catastrophically fail (due to localized high current
density, electrical arcing or some other event). Typically,
manufacturers protect against this type of buildup by incorporating
a water softener on the feed water to the system to prevent these
contaminants from ever entering the electrolytic cell. However,
these contaminants will enter the process over time from
contaminants in the salt used to make the brine. High quality salt
is typically specified to minimize the incidence of cell cleaning
operations. U.S. Pat. No. 7,922,890 describes methods and
apparatuses of creating low maintenance, highly reliable
electrolytic cells for creating oxidants. However, this type of
approach typically only works for lower hardness waters (<20
grains/gallon for example) and higher quality salts (>99.5%
dry).
[0007] Many water purification processes produce a brine solution
containing enough dissolved salts to be suitable for processing
into a disinfectant/oxidant. Specifically, reverse osmosis,
evaporation, distillation, chemical softening, and ion exchange
technologies have waste streams with high concentrations of salts.
Typically, however, these waste streams also have high
concentrations of contaminants (typically measured as hardness)
that would foul most electrolytic cells quickly, resulting in
premature electrolytic cell failure.
[0008] More recently, though, solutions providers such as GE or
Veolia Water have developed offerings such as the HERO or OPUS.RTM.
technologies, where waste water is pretreated to reduce the
hardness prior to exposing them to the RO membranes. This makes
this waste stream from the RO membranes much more desirable as a
possible feedstock for electrolytic generation of an oxidant from
that waste stream, as most of the undesirable contaminants for
electrolysis are removed via the pretreatment process.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
[0009] An embodiment of the present invention is a method for
producing an oxidant, the method comprising adjusting the salinity
and/or hardness of a waste stream thereby forming a brine solution;
and electrolyzing the brine solution to produce at least one
oxidant. The adjusting step preferably comprises measuring the
salinity and/or hardness of the waste stream. The adjusting step
optionally comprises adding water or processed water to the waste
stream to reduce the salinity of the waste stream and preferably
further comprises varying the relative flow rates of the waste
stream and the water or processed water being input into an
electrolytic cell. The adjusting step optionally comprises adding a
saturated or near saturated salt solution to the waste stream to
increase the salinity of the waste stream and preferably further
comprises varying the relative flow rates of the waste stream and
the saturated or near saturated salt solution being input into an
electrolytic cell. The adjusting step preferably comprises treating
the waste stream by a method selected from the group consisting of
softening, ion exchange, filtering, and reverse osmosis. The brine
solution preferably has a salinity between approximately 10 g/L and
40 g/L. The adjusting step preferably reduces a cleaning frequency
of the electrolytic cell.
[0010] Another embodiment of the present invention is a method for
cleaning an electrolytic cell, the method comprising measuring a
salinity and hardness of a waste stream to be electrolyzed,
calculating a frequency for cleaning the electrolytic cell based on
the measured salinity and hardness of the waste stream and a
spacing between electrodes of the electrolytic cell, and cleaning
the electrolytic cell in accordance with the calculated frequency.
The cleaning step preferably comprises reversing a polarity of the
electrolytic cell and/or flushing solid contaminants from the
electrolytic cell. The flushing is preferably performed once or
twice a day or after the electrolytic cell was cleaned by reversing
the polarity of the electrolytic cell. The method preferably
further comprises adjusting the salinity and/or hardness of the
waste stream, thereby reducing the cleaning frequency.
[0011] Another embodiment of the present invention is an
electrolytic cell for electrolyzing a waste stream, the
electrolytic cell comprising one or more devices for adjusting a
flow rate of the waste stream entering an electrolytic cell; one or
more dispersion tubes for transporting the waste stream into the
electrolytic cell; a plurality of holes in the dispersion tubes,
the holes angled to direct a flow of the waste stream toward bottom
edges of the electrolytic cell; and one or more insulators
substantially parallel to electrodes in the electrolytic cell and
extending from a bottom of the electrolytic cell to at least a
level of bottoms of the electrodes. The additive stream may
comprise water, processed water, a saturated salt solution, or a
near saturated salt solution. At least one of the devices can
preferably flush the cell with the waste stream or water at a
flushing flow velocity higher than (preferably at least twice) the
operational flow velocity of the waste stream. Spacing between
adjacent holes is preferably between approximately 0.5'' and
approximately 2''. The electrolytic cell preferably comprises
electrodes which are spaced more widely than electrodes in an
electrolytic cell designed to produce a similar quantity and
strength of oxidants from a controlled brine stream. The
electrolytic cell preferably comprises intermediate electrodes,
wherein spacing between adjacent intermediate electrodes is
preferably between approximately 0.15'' and approximately 0.5'',
and more preferably 0.25''+/-0.1''.
[0012] Objects, advantages, novel features, and further scope of
applicability of the present invention will be set forth in part in
the detailed description to follow, taken in conjunction with the
accompanying drawings, and in part will become apparent to those
skilled in the art upon examination of the following, or may be
learned by practice of the invention. The objects and advantages of
the invention may be realized and attained by means of the
instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are incorporated into and
form a part of the specification, illustrate an embodiment of the
present invention and, together with the description, serve to
explain the principles of the invention. The drawings are only for
the purpose of illustrating various embodiments of the invention
and are not to be construed as limiting the invention. In the
drawings:
[0014] FIG. 1 is a schematic showing brine waste at a high salinity
being converted electrochemically into usable oxidant.
[0015] FIG. 2 is a schematic showing brine waste at a low salinity
being converted electrochemically into usable oxidant.
[0016] FIG. 3 is a schematic showing brine waste with a very high
hardness to salinity ratio, where divalent cations are removed
prior to electrolysis making the brine waste appropriate for
electrolysis.
[0017] FIG. 4 is a high level schematic of an on-site electrolytic
generator for converting brine waste to oxidant.
[0018] FIG. 5 is a cross section of an electrolytic cell for
converting brine waste to oxidant.
[0019] FIG. 6 is a 3D representation of an electrolytic cell for
converting brine waste to oxidant.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Embodiments of the present invention electrolize the waste
stream from an industrial process, such as reverse osmosis, ion
exchange softening, chemical softening, evaporation, distillation,
produced or flowback water from oil and gas wells, to produce an
oxidant and/or disinfectant. This waste stream may be highly
variable in salt content, presenting a unique challenge for
consistent oxidant production. For example, a water source with low
dissolved salt may be injected into the electrolyte for a high
salinity waste stream at a rate determined by the operating current
of the electrolytic cell. When the operating current is high, more
water with low dissolved salt is preferably injected to reach the
target operating current of the cell. Conversely, when the
operating current is low, the water with low dissolved salts may be
replaced with a concentrated brine solution injection to raise the
current to the desired operating condition.
[0021] As used throughout the specification and claims, the term
"waste stream" means an aqueous byproduct of an industrial process
or application, including but not limited to frac water, produced
water from oil and gas operations, cooling towers, desalination, or
evaporation, the byproduct having a sodium chloride content of
greater than approximately 1 g/L.
[0022] Embodiments of the present invention utilize an
electrochemical process to convert a waste brine stream into a
usable oxidant; one such process is shown in FIG. 1. In FIG. 1, raw
water 1 is first treated via softening process equipment 2 to
remove divalent cations (typically those acknowledged as hardness)
and other contaminants. Softened waste water 3 is then put through
purification processing equipment 4, such as reverse osmosis or
other membrane processing equipment, to remove monovalent cations
(i.e. salts) to create processed water 5 and brine waste 6.
Processed water 5 can often be used for industrial processes, is
appropriate for discharge, and/or can even potentially be used as
potable water. Brine waste 6 is then processed and electrolyzed in
on-site electrolytic generator 7 into oxidant 8. Oxidant 8 can
either be stored in a tank or directly used for a variety of
applications (not shown). To produce a desired concentration of
oxidant 8 (for example 100 to 1000's mg/L) and/or provide
electrolyte with the proper salinity for electrolysis, dilution
water 9 may optionally be used to dilute brine waste 6 in the
on-site electrolytic generator if brine waste 6 is too salty.
[0023] Raw water 1 can be from virtually any source. However,
certain sources have, or certain industrial processes produce a
waste stream that has, a somewhat higher incidence of dissolved
salts in the raw water, such as seawater, produced and/or flowback
water from oil and gas operations, ground water, surface water,
waste from industrial processes, waste water from municipalities,
potable water, etc.
[0024] Brine waste 6 is often at a fairly high salinity, often
greater than approximately 40 g/L but less than that for saturated
brine (317 g/L). In the event that the salinity is greater than
approximately 40 g/L, dilution water 9 may be used to dilute the
brine waste to a lower level that is more appropriate for
electrolysis, typically between approximately 10 g/L and 40 g/L. A
small percentage of processed water 5 may optionally be used as the
dilution water 9.
[0025] Depending on the nature of the raw water 1 and the
purification processing equipment 4, if not required softening
process equipment 2 may not be included in order to reduce cost and
complexity of the system.
[0026] Some industrial processes produce a brine waste that does
not require complicated purification processing equipment 4 because
the brine waste has the appropriate hardness to salinity ratio in
the brine solution that it can be electrolyzed. Examples of this
are waste water remediation and/or flowback or produced waters from
oil and gas operations. Thus, in one embodiment of the invention,
there is no processed water 5, and the purification processing
equipment comprises or consists essentially of a simple filter to
remove large particles (typically >20 microns, but preferably
>100 microns) from brine waste 6.
[0027] FIG. 2 shows another embodiment of the invention. In the
event that the salinity of the waste brine 6 is low, less than
approximately 10 g/L for example, solid brine storage tank 11 may
be utilized. In the solid brine storage tank, solid salt is
saturated in water, creating a brine solution 10 at or near
saturation (approximately 317 g/L). In this event, a small amount
of saturated brine solution 10 is combined with the brine waste 6
for electrolysis by on-site electrolytic generator 7.
[0028] Another embodiment of the invention is shown in FIG. 3. In
this embodiment, divalent cations are removed from brine waste 6
using selective ion exchange process equipment 12, leaving a brine
solution suitable for electrolytic generation of oxidant in on-site
electrolytic generator 7.
[0029] Compared to existing commercially available on-site
electrolytic generators, embodiments of that required to convert
waste to oxidant in accordance with the present invention are
substantially different. FIG. 4 shows a high level schematic of an
embodiment of on-site electrolytic generator 7. The electrolytic
generator takes brine waste 6 and either dilution water 9 or
saturated brine solution 10 and generates oxidant 8 by
electrolyzing it in electrolytic cell 14. Depending on the salt
concentration of brine waste 6. the relative flow rates of brine
waste 6 and/or dilution water 9 or saturated brine solution 10 are
preferably controlled by integrated controls 15, preferably via
devices 13 such as pressure mechanisms, pumps, or valves. These
input rates and the current and/or voltage applied to the
electrolytic cell are preferably varied to maintain a controlled
oxidant concentration.
[0030] During operation, devices 13 can be controlled to
intermittently flush the electrolytic cell with very high flow
rates (preferably greater than approximately two times the
operational flow rate) of water or waste stream 6. If the latter is
used, flushing can occur during the electrolysis process. This
flushing prevents or reduces deposits from accumulating at the
bottom of the electrolytic cell. Integrated controls 15 also
preferably control reversing the polarity of the cell, which
removes deposits from the electrode surfaces. This process is more
fully described in U.S. Patent Application Publication No.
20090229992.
[0031] Despite being exposed to high levels of hardness, suspended
solids, dissolved solids, and contaminants such as silica,
electrolytic cell 14 is preferably designed such that it is robust
and has an adequate lifetime. FIG. 5 shows a cross section of an
embodiment of a bipolar electrolytic cell useful for the current
invention. Primary electrodes 15 and intermediate electrodes 16 are
preferably coated with Dimensionally Stable Anode (DSA) material,
such as ruthenium, iridium, palladium, or other materials known in
the art. Both the primary anode and preferably cathode are coated
with DSA so that the polarity of the cell can be intermittently
reversed to remove any deposits on the electrodes. A series of
intermediate electrodes 16 are disposed between primary electrodes
15. The spacing from one electrode to the next is wider than on
most typical electrolytic cells, preferably greater than 0.15'' but
less than approximately 0.5'', preferably 0.25''+/-0.1''. In
general, the wider the spacing the more inefficient the cell is,
but wider spacing is useful with the present invention to prevent
elevated contaminants from the incoming brine waste 6 from
depositing on intermediate electrodes 16 and creating an electrical
short circuit and arcing and/or premature cell failure. Brine waste
6 is introduced to the electrolytic cell via dispersion tube 18,
which comprises holes which direct the brine waste towards the
bottom of electrolytic cell 14, and more preferably, to the bottom
corners of the electrolytic cell 14. The size, angles, and spacing
of these holes down the length of the dispersion tube are
preferably chosen to increase the velocity of the fluid, such that
particles are less likely to settle into the bottom of the cell. By
accelerating the brine waste 14 and angling it down and
substantially towards the corners of the bottom of the electrolytic
cell, any contaminants and/or particles that have begun to settle
into the bottom of the cell can be accelerated and re-suspended up
and between electrodes 16 and out of the electrolytic cell 14. This
design makes it particularly easy to flush larger particles and/or
contaminants out of the bottom of the cell by performing
intermittent flushing, preferably 1-2 times a day, preferably at
high flow rates either while the cell is energized or not. During
operation, brine waste 6 stream through dispersion tubes 18 and out
of the holes, where its flow is directed to agitate any particles
that may have settled. The brine waste stream then travels up
between the electrodes, and, when power is applied to primary
electrodes 15, it is electrolyzed to form oxidant 8 which leaves
the electrolytic cell.
[0032] Electrolytic cell preferably comprises one or more
electrical isolator blocks 17, which preferably extend from the
bottom of the cell at least up to the bottom of the electrodes. One
isolator block is preferably present every few intermediate
electrodes 16, which prevents loss of electrical efficiency and
also protects the electrodes from being exposed to voltages beyond
their breakdown voltages, for example due to high salinity of the
brine waste. Thus the use of these blocks enables particles to
build up in the cell without arcing between electrodes taking
place. Typically electrical isolator blocks 17 are spaced every
5-10 electrodes, but depending on the chemistry desired in the
oxidant and the salinity of brine waste 6, one electrical isolator
block 17 could be present every 3 electrodes or even up to every 40
electrodes. As shown in the perspective view of electrolytic cell
14 shown in FIG. 6, dispersion tubes 18 preferably distribute the
brine waste 6 into the cell through an array of holes as described
above. The holes are preferably spaced apart between approximately
0.5'' and approximately 2'', preferably 1''+/-0.25''.
[0033] The characteristics of the brine waste vary considerably
with different waste applications, which has implications on the
frequency with which the electrolytic cell is cleaned.
Specifically, the ratio of divalent cations to monovalent cations
is particularly important. For a given ratio, the growth rate of
contaminants on the electrodes is calculated, and for a given
electrode spacing, the required cleaning frequency of the cell to
prevent arcing between electrodes can be determined, after applying
a given safety factor. From this cleaning frequency the expected
life of an electrolytic cell can then be predicted given a certain
number of cycles to failure. Thus, treating the waste stream so
that the salinity and/or hardness are in optimal ranges can greatly
increase the lifetime of the cell by reducing required cleaning
frequency. By controlling these parameters, as well as flow rate,
voltage, and current in the electrolysis cell, the system can be
optimized for energy conversion efficiency as salt is a waste
product for various industrial processes and is therefore is
extremely inexpensive.
Example 1
[0034] A waste brine stream was created by a system very similar to
the system shown in FIG. 1, in which the softening water processing
equipment was an ion exchange resin softener, and the purification
process equipment was a membrane based reverse osmosis filter. The
salinity of the waste brine stream was measured at 40 g/L, and had
100 grains/gallon hardness. Electrolyzing this waste brine stream
was completed yielding an oxidant with 3400 mg/L FAC, with a
required cell cleaning frequency of about 7 days corresponding to
an expected cell life well over 10 years.
Example 2
[0035] A waste brine stream consisting of produced water from an
oil and gas operation was created by a system similar to the one
shown in FIG. 1, with the exception that the softening water
processing equipment was not present and the process equipment was
a simple filter to remove particles >80 microns. The salinity of
the waste brine stream was 17 g/L, and the hardness was 24 grains,
and electrolyzing it yielded an oxidant with 2200 mg/L FAC, with a
cell cleaning frequency of 12 days and an expected cell life well
over 10 years.
Example 3
[0036] A waste brine stream from a desalination plant was created
with a system similar to the one depicted in FIG. 1, with no
softening processing equipment. The desalination plant relied on
reverse osmosis to process the water. The waste brine stream had a
salinity of 210 g/L (typically too salty for effective
electrolysis) and a hardness of 2800 grains/gallon. The waste brine
stream was recombined with a side stream of RO permeate as
described herein to deliver a salinity of approximately 15 g/L to
the electrolytic cell. Electrolysis of this stream yielded an
oxidant with 4200 mg/L FAC, with a cell cleaning frequency of 1.3
days and an expected cell life of 3.9 years.
Example 4
[0037] Waste blowdown from a cooling tower had approximately 4 g/L
salt and a hardness of 180 grains/gallon. This waste blowdown was
directly electrolyzied, yielding an oxidant with 650 mg/L FAC with
a cleaning frequency of 0.4 days and an expected cell life of 1.2
years. When combined with a solid brine source as shown in FIG. 2,
the salinity was increased to 15 g/L, lengthening the cleaning
frequency to 1.5 days and increasing expected cell life to over 5
years. In both instances, the oxidant produced was used to
disinfect the cooling tower.
[0038] Although the invention has been described in detail with
particular reference to the disclosed embodiments, other
embodiments can achieve the same results. Variations and
modifications of the present invention will be obvious to those
skilled in the art and it is intended to cover all such
modifications and equivalents. The entire disclosures of all
patents and publications cited above are hereby incorporated by
reference.
* * * * *