U.S. patent application number 09/877187 was filed with the patent office on 2001-11-01 for water treatment composition.
Invention is credited to Linn, Tosby L., Nier, Thomas J..
Application Number | 20010036904 09/877187 |
Document ID | / |
Family ID | 24993826 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010036904 |
Kind Code |
A1 |
Nier, Thomas J. ; et
al. |
November 1, 2001 |
Water treatment composition
Abstract
A water soluble copper salt, preferably cupric sulfate
pentahydrate, is mixed with water. A small quantity of an acidic
flocculent is added to the copper sulfate solution to acidify the
water and promote dissolving of the copper sulfate in the water. A
25-50% water solution of an acidic flocculant, with or without a
cationic polymeric flocculent aid, is prepared and pumped into a
processing vessel or tank. The acidified copper sulfate solution is
added to the tank and mixed with the acidic flocculent. The
algicide-flocculant solution is transported to a municipal water
plant and added to raw water in the clarifier to drop out
particulates in the incoming water and control algae in the
clarifier.
Inventors: |
Nier, Thomas J.; (Corpus
Christi, TX) ; Linn, Tosby L.; (Corpus Christi,
TX) |
Correspondence
Address: |
NIXON PEABODY, LLP
8180 GREENSBORO DRIVE
SUITE 800
MCLEAN
VA
22102
US
|
Family ID: |
24993826 |
Appl. No.: |
09/877187 |
Filed: |
June 11, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09877187 |
Jun 11, 2001 |
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09055205 |
Apr 6, 1998 |
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6248369 |
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09055205 |
Apr 6, 1998 |
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08744742 |
Oct 28, 1996 |
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Current U.S.
Class: |
504/151 |
Current CPC
Class: |
C02F 1/52 20130101; C02F
1/505 20130101; A01N 59/20 20130101; A01N 59/20 20130101; A01N
59/20 20130101; A01N 33/12 20130101; C02F 1/56 20130101; A01N 59/06
20130101; A01N 59/16 20130101; A01N 2300/00 20130101 |
Class at
Publication: |
504/151 |
International
Class: |
A01N 059/00 |
Claims
I claim:
1. An algicide-flocculant solution for use in treating raw water in
a municipal water plant to control algae, comprising 25-50 wt % of
an acidic flocculant; 0-10 wt % of a polymer flocculent aid; an
algicide consisting essentially of copper having a concentration of
0.025-1.25 wt % in the form of a water soluble copper salt; balance
water, so that uniform mixing of the flocculant into the raw water
simultaneously uniformly mixes the algicide of the
algicide-flocculant solution into the raw water.
2. The algicide-flocculant solution of claim 1, wherein the acidic
flocculant is selected from the group consisting of aluminum
sulfate, iron sulfate, iron chloride and mixtures thereof.
3. The algicide-flocculant solution of claim 2, wherein the acidic
flocculant is selected from the group consisting of aluminum
sulfate, iron sulfate and mixtures thereof.
4. The algicide-flocculant solution of claim 2, wherein the acidic
flocculant is 35-50 wt % of the algicide-flocculant solution.
5. The algicide-flocculant solution of claim 1, wherein the water
soluble copper salt is selected from the group consisting of copper
sulfate, copper chloride, copper nitrate, copper acetate and
mixtures thereof.
6. The algicide-flocculant solution of claim 5, wherein the water
soluble copper salt is copper sulfate.
7. The algicide-flocculant solution of claim 5, wherein the copper
concentration is 0.025-0.25 wt % of the algicide-flocculant
solution.
8. The algicide-flocculant solution of claim 1, wherein the
flocculant aid is a high molecular weight quaternary amine.
9. The algicide-flocculant solution of claim 8, wherein the
flocculant aid is diallyldimethylammonium chloride.
10. The algicide-flocculant solution of claim 9, wherein the
flocculant aid is 0-5 wt % of the algicide-flocculant solution.
11. The algicide-flocculant solution of claim 1, wherein the acidic
flocculant is 35-50 wt % of the algicide-flocculant solution.
12. The algicide-flocculant solution of claim 1, wherein the copper
concentration is 0.025-0.25 wt % of the algicide-flocculant
solution.
13. The algicide-flocculant solution of claim 1, wherein the
flocculant aid is 0-5 wt % of the algicide-flocculant solution.
14. A premixed algicide-flocculant solution for use in treating raw
water in a municipal water plant to control algae, consisting
essentially of 35-50 wt % of an acidic flocculent; 0-5 wt % of a
polymer flocculent aid; an algicide having a concentration of
0.025-0.25 wt % copper in the form of a water soluble copper salt;
balance water, so that uniform mixing of the flocculant into the
raw water simultaneously uniformly mixes the algicide of the
algicide-flocculant solution into the raw water.
15. The algicide-flocculant solution of claim 14, wherein the
acidic flocculant is selected from the group consisting of aluminum
sulfate, iron sulfate and mixtures thereof.
16. The algicide-flocculant solution of claim 15, wherein the water
soluble copper salt is selected from the group consisting of copper
sulfate, copper chloride, copper nitrate, copper acetate and
mixtures thereof.
17. The algicide-flocculant solution of claim 16, wherein the
flocculent aid is a high molecular weight quaternary amine.
18. The algicide-flocculant solution of claim 17, wherein the
flocculent aid is diallyldimethylammonium chloride.
19. The algicide-flocculant solution of claim 14, wherein the water
soluble copper salt is selected from the group consisting of copper
sulfate, copper chloride, copper nitrate, copper acetate and
mixtures thereof.
Description
[0001] This application is a continuation of application Ser. No.
09/055,205, filed Apr. 6, 1998 which is a division of application
Ser. No. 08/744,742 filed Oct. 28, 1996, now abandoned.
[0002] This invention is a process for treating raw water and
producing potable water meeting accepted purity standards.
BACKGROUND OF THE INVENTION
[0003] Fresh water from rivers or lakes is treated in a water plant
to convert the raw water into water for human consumption meeting
accepted purity standards. The processes used have been honed over
the years to produce high quality potable water from raw water at
surprisingly low costs.
[0004] The primary treatment in a water plant occurs in a clarifier
where a flocculant is added to raw water. A water plant clarifier
is a large sized, round or rectangular concrete structure. The
flocculant causes particles suspended in the water to coagulate,
subsequently growing in size and weight. The clarifier is sized to
provide sufficient residence time for the majority of the solids to
drop out of suspension. Water is then passed through sand filters,
perhaps treated with activated carbon, chlorinated and possibly
fluoridated before being delivered to water supply mains which
transport the treated water to residences, businesses and
industries.
[0005] One of the recurrent problems in water treatment plant
operations is the growth of algae in the clarifier and sand
filters. Algae come in many types including filamentous algae, such
as Cladaphora and Spirogyra, planktonic algae such as Microcystis
and Anabaena, branched algae such as Chara vulgaris and Nitellam,
swimming pool algae commonly referred to as black, brown and red
algae and algae found in ponds such as Dictyosphaerium, Spirogyra,
Oedogonium, Chlorococcum, Pithophora, Hyudrodictyon and Lyngbya. It
is not uncommon to see a municipal water plant clarifier with a
beard of algae around its peripheral walls and filamentous algae
growths several feet long.
[0006] As used herein, the term municipal water plant is intended
to mean a water plant used in treating raw water and converting it
to potable water for human consumption, regardless of whether the
entity doing so is public or private.
[0007] Algae blooms have been noted to appear literally overnight
under the right temperature and sunlight conditions and, if left
untreated, will cause taste and odor problems in the finished
waters. The problems caused by algae in municipal water plants are
handled in a variety of ways by current treatment methods. The odor
and taste problems which typically recur during periods of high
summer temperatures and long daylight hours occur from detritus
thrown off by algae in the clarifier. Not all of this detritus is
removed by sand filters. Any detritus passing through the sand
filters is converted in the final chlorination process to a family
of chloro-organic compounds which cause the objectionable smell and
taste that consumers complain about.
[0008] The standard treatment for controlling algae in municipal
water plants is to scatter crystals of cupric sulfate pentahydrate,
CuSO.sub.4.5H.sub.2O, which is also known by its common name blue
vitriol, into the clarifier. Blue vitriol is commercially available
in 50 pound bags having crystals ranging in size from fine (1/8")
to large (1"). Scattering is done with a shovel, a scoop, or by
hand. Ideally, the crystals dissolve in the water so the copper ion
is present in the water. The soluble or active copper (II) ion
kills algae because of its effect on chlorophyll which is a large
porphyrin structure occurring either as blue-green chlorophyll-a or
yellow-green chlorophyll-b. Both molecules have four centrally
placed nitrogen atoms which complex a single magnesium atom. The
magnesium removes carbon dioxide from the water and delivers it to
the algae thus allowing photosynthetic growth. The soluble copper
(II) ion replaces the magnesium by forming a stronger porphyrin
complex, which does not bond with carbon dioxide. The algae dies by
virtue of its growth mechanism being squelched by a lack of carbon
dioxide, in a process analogous to the chemical poisoning of
hemoglobin in mammals. A small part of the algicidal copper exits
the treated water stream in the clarifier sludge and not with the
finished water because it has been intimately bonded to the algae
chlorophyll. A large part of the copper sulphate is believed to
remain undissolved and drops into the clarifier sludge as copper
hydroxide coated pellets. One of the inherent advantages of copper
algicides is that algae cannot mutate or evolve to avoid its
effect. No amount of evolution can prevent copper from displacing
magnesium in the chlorophyll and no amount of evolution can cause
the copper porphyrin to absorb carbon dioxide.
[0009] Disclosures of some interest are found in U.S. Pat. Nos.
3,844,760; 4,012,221; 4,505,734 and 5,541,150.
SUMMARY OF THE INVENTION
[0010] The above description of the prior art is an idealized
situation but which has a number of practical problems and
disadvantages, some subtle and some not so subtle. A substantial
part of the blue vitriol does not dissolve because it is difficult
to dissolve in water which is not acidic. Plainly put, blue vitriol
crystals do not dissolve very well in pH 7, or more alkaline,
water. Thus, much of the copper sulfate is wasted because it ends
up in the clarifier sludge as blue vitriol pebbles with a thin
copper hydroxide coating. In addition, scattering blue vitriol
crystals in the clarifier does not produce uniform dosages of
copper sulfate in the water. Instead, very high dosages will be
found immediately down current from the crystals and little copper
sulfate will be found elsewhere.
[0011] In this invention, a water soluble copper salt is dissolved
in an aqueous solution of an acidic flocculent. It is fortuitous
that the selected flocculants are quite acidic because many water
soluble copper salts, and the preferred copper sulfate, are much
more soluble in low pH water than in neutral to high pH water. The
resultant algicide-flocculant solution is commonly delivered in a
tank truck or by a tank rail car and off loaded into storage
tanks.
[0012] The solution is then metered into the clarifier, thus
delivering a reliable, predictable quantity of flocculant and
copper algicide. This technique operates to deliver a uniform low
dose of copper algicide in a very simple, efficient and trouble
free manner because flocculent metering pumps deliver a controlled
amount of flocculent in a manner which mixes the flocculant into
the raw water in a thorough and uniform manner. It is this liquid
injection that thoroughly and uniformly mixes the algicide with the
water, as contrasted to the prior art technique scattering of blue
vitriol crystals with a shovel into the clarifier. Efficient mixing
of the copper algicide with the water provides low, uniform dosages
of copper which is very desirable because little copper is
wasted.
[0013] The copper solution provides copper (II) ions that displace
the magnesium ion in chlorophyll to kill the algae in the
clarifier. The amount of copper in the algicide-flocculant solution
is controlled; thus the amount of copper in the clarifier is also
controlled and is maintained at low levels. The copper reacts with
the magnesium in the chlorophyll molecules and, along with the dead
algae, collects in the sludge in the bottom of the clarifier.
[0014] When using this invention, no blue copper crystals will be
found in the clarifier sludge which means that more of the copper
has been put to its intended use of killing algae rather than
wasted in the clarifier sludge. In addition, the amount of soluble
copper ion passing through the clarifier into the finished water
will normally not exceed 0.1 ppm which is well below the 1.3 ppm
standard required by the Lead and Copper Rule of the Environmental
Protection Agency.
[0015] It is difficult to overstate the importance of low, uniform
dosages of copper. For the algicide to be effective, copper (II)
ions must come intimately close to the magnesium ion in the
chlorophyll complex of substantially all of the algae cells.
Although there is moderate circulation in the clarifier, it is hard
to imagine copper ions in concentrations on the order of less than
1 ppm reacting with enough magnesium atoms in chlorophyll to
control an algae bloom. However, this can be done with improved
mixing and distribution of the algicide when it is combined with
the flocculant as in this invention. Uniform dosages are the key to
effectiveness. Low dosages are the key to economy.
[0016] In the past, a water plant has typically used a conventional
flocculent, either with or without a polymeric flocculant aid. With
the onset of a substantial algae bloom, attempts would be made to
control the algae bloom using the prior art technique with less
than satisfactory results. When facing a full grown algae bloom,
the amount of copper in the algicide-flocculant solution of this
invention would be at a relatively high level which will bring the
algae bloom under control in a fairly short period. After the algae
bloom is brought under control, the amount of soluble algicide will
be reduced in subsequent batches of algicide-flocculant solutions
and ultimately reduced to a lower level that is sufficient to keep
algae growth suppressed at a very reasonable cost. A large
proportion of the algicidal copper exits the treated water stream
in the clarifier sludge and not with the finished water because it
has been intimately bonded to the algae chlorophyll.
[0017] An object of this invention is to provide an improved
technique for treating algae in a municipal water plant.
[0018] Another object of this invention is to provide an improved
technique for preparing an algicide-flocculant solution.
[0019] A more specific object of this invention is to treat raw
water with an algicide-flocculant solution which, when added to a
water plant clarifier, drops particulates out of suspension and
simultaneously controls algae in the clarifier.
[0020] These and other objects and advantages of this invention
will become more apparent as this description proceeds, reference
being made to the appended claims.
DETAILED DESCRIPTION
[0021] The copper algicide of this invention is selected from water
soluble copper salts. From a simple algicidal standpoint, almost
any water soluble copper salt is suitable. From the standpoint of
producing potable water, the choice is more limited because not all
water soluble copper salts can economically be put into drinking
water. Thus, the common choices for the water soluble copper salt
are copper sulfate, copper chloride, copper nitrate and copper
acetate. The selection will likely be based on the relative cost of
copper salts. Copper sulfate is the preferred water soluble copper
salt because it is the only one presently approved for use in
municipal water plants; it is effective as a source of copper (II)
ions; and, it is the least expensive of the possible candidates.
The preferred form of copper sulfate is blue vitriol which is
cupric sulfate pentahydrate.
[0022] The amount of blue vitriol in the algicide-flocculant
solution varies between 0.1-5% by weight. The proportion of copper
in blue vitriol is 25.45% by weight which means that the copper
concentration in the algicide-flocculant solution varies from about
0.025-1.25%. Preferably, the amount of blue vitriol in the
algicide-flocculant solution is 0.1-1% by weight meaning that the
active copper concentration in the preferred solution is
0.025-0.25% by weight. The equivalent concentration of other
soluble copper salts is found in Table I:
1 TABLE I copper salt copper salt concentration concentration
necessary necessary to produce 0.025% to produce 1.25% copper salt
active Cu (II) active Cu (II) CuSO.sub.4.5H.sub.2O 0.10% 5.0%
CuCl.sub.2.2H.sub.2O 0.067% 3.35% Cu(acetate).sub.2.H.sub.2O 0.078%
3.93% Cu(NO.sub.3).sub.2.3H.sub.2O 0.095% 4.75%
Cu(NO.sub.3).sub.2.6H.sub.2O 0.116% 5.82% CuSO.sub.4.H.sub.2O
0.070% 3.49%
[0023] Accordingly, the concentration of the copper salts vary from
about 0.05% to about 6% in order to provide the desired range of
active copper concentration.
[0024] It has been found that an active copper concentration of
0.25% in the algicide-flocculant solution is sufficient to bring
algae blooms under control. As initial batches of
algicide-flocculant solution are used in response to an algae
bloom, the algae die off substantially. Subsequent batches of
algicide-flocculant solution preferably contain reduced amounts of
active copper algicide, usually about half the initial dose. It has
been found that copper concentrations in the algicide-flocculant
solution approaching 0.025%, such as in the range of about
0.025-0.050%, are sufficient as a maintenance dose to keep algae
under control and prevent the formation of algae blooms, even under
the most trying conditions of temperature and sunlight.
[0025] Theoretically, it is possible to add copper salt crystals in
the proper proportion to an acidic flocculent solution and agitate
the solution to dissolve the copper salt. In practice, this has not
been efficient for a variety of reasons. The source of blue vitriol
is solid pebbles which require vigorous agitation to dissolve, such
as occurs with a powered impeller. With aluminum sulfate as the
flocculent, solubility is adversely affected by the common ion
effect. It is accordingly much better to dissolve the copper salt
in water and then mix the water soluble copper salt solution with
the flocculant solution. Using copper sulfate as the algicide, one
part blue vitriol is dissolved in two parts water making a nearly
saturated copper sulfate solution.
[0026] To prepare the water solution of the copper salt, a mixing
tank is partially filled with water and a suitable mixer, such as a
powered impeller, is used to agitate the water. Preferably, the
water is heated with a suitable heater, such as an electrically
powered immersion heater or preheated with a conventional water
heater. The selected copper salt is taken from commercially
available bags and the desired quantity added to the tank. Using
blue vitriol, the water solution will initially be bluish but
somewhat milky which is caused by partial formation of copper
hydroxide. Continued stirring and complete dissolving of the blue
vitriol will result in a clear blue color typical of copper sulfate
solutions.
[0027] During the mixing process, a small quantity of acidic
flocculent solution is poured into the tank to acidify the copper
salt solution to a pH of no more than 5 and preferably in the range
of 4-5. A typical flocculant solution has a pH of about 2.5, which
is about the same as lemon juice. Acidifying the solution prevents
the formation of copper hydroxide so the copper salt completely
dissolves, and remains in solution. Acidifying the solution with
the flocculant material avoids using a different acid material
which, in the treatment of water for human consumption, might
provide regulatory problems.
[0028] The flocculant of this invention is acidic and, when mixed
with the algicide, acidifies the water used to dissolve the copper
salt. Suitable flocculants are aluminum sulfate, iron sulfate, iron
chloride and mixtures thereof. Preferably, but not necessarily, the
flocculants are prepared in a nearly saturated solution. In a
typical process, aluminum oxide is reacted with sulfuric acid to
produce liquid aluminum sulfate, i.e. about 47-50% by weight
aluminum sulfate in water. Iron sulfate or iron chloride may be
prepared by commonly known procedures, as is well known in the art.
In this invention, the amount of flocculant in the
algicide-flocculant solution varies between 25-50% by weight and
preferably is 35-50% by weight.
[0029] The invention is also useable with polymer flocculant aids
of any suitable type. Polymer flocculant aids are long chain, high
molecular weight cationic materials, usually having molecular
weights in the range of 100,000-800,000. Conventional flocculants,
such as aluminum sulfate, iron sulfate, iron chloride and mixtures
thereof, produce relatively small flocs which require relatively
long residence times to settle out by gravity in the clarifier. The
polymer flocculant aids cause these small flocs to agglomerate into
larger particles that settle at faster rates, thereby allowing
shorter residence times in the clarifier. The present standard
polymer flocculant aids are high molecular weight quaternary amines
such as diallyldimethylammonium chloride which is commercially
available from CPS Chemical Company, West Memphis, Ark. In this
invention, the amount of polymer flocculant aid in the
algicide-flocculant solution varies between 0-10% by weight but
preferably is 0-5% by weight. Preferably, the polymer flocculent
aid is added to the flocculant prior to the addition of the water
soluble copper salt solution.
[0030] Potable water treatment chemicals are typically delivered by
tank truck to the water plant. In this invention, the flocculent,
with or without the cationic polymer aid, and the acidified copper
salt solution are thoroughly mixed in a processing vessel or tank
by agitation, air mixing or a recirculating pump. The complete
homogenous mixture is then loaded into the tank truck for delivery
to the water plant. In an alternate production method, the
flocculent, with or without the cationic polymer aid, is
simultaneously loaded with the acidified copper salt solution into
the tank of a tank truck. Final mixing occurs during transport,
caused by agitation o the liquid contents due to movement of the
truck.
[0031] The algicide-flocculant solution, with or without the
polymeric flocculent aid, is added to raw water in the clarifier
using conventional metering equipment to deliver sufficient
flocculent to coagulate the particulates in the raw water.
Typically, nearly saturated flocculant is added to the raw water in
the range of 20-60 ppm, an average value being about 30 ppm.
Because incoming raw water contains very little soluble copper, the
active copper concentration in the clarifier is due almost entirely
to the copper algicide combined with the flocculant. Thus, the
clarifier water has a copper concentration in the range of
0.050-0.15 ppm.
[0032] Examples of this invention are:
EXAMPLE 1
[0033] Approximately 55 gallons of tap water are added to a mix
tank. The water is then heated slightly using an electric immersion
heater. 220 pounds of commercially available blue vitriol crystals
are added to the mix tank and agitated vigorously with a powered
impeller. During the mixing process, two-three gallons of 47-50%
aluminum sulfate solution are added to the tank and mixing
continues until the blue vitriol crystals are completely dissolved,
producing a clear blue liquid. A processing vessel or tank is
filled with 4000 gallons of 47-50% aluminum sulfate solution with
no polymer flocculent aid. The copper sulfate solution is then
transferred into the processing vessel or tank containing with the
aluminum sulfate. This produces a solution of 1/2% by weight copper
sulfate, 45-47% aluminum sulfate, balance water. After delivery to
the water plant, the solution is transferred to a storage tank and
then metered into the clarifier at about 30 ppm where it mixes
substantially uniformly with the incoming raw water to flocculate
particulates in the raw water and kill algae in the clarifier. In
this example, the water plant had run 1% concentrations of copper
sulfate in the flocculant to bring an algae bloom under control and
the 1/2% solution in this batch was intended as a maintenance
dosage to prevent recurrence of the algae bloom.
EXAMPLE 2
[0034] 440 pounds of blue vitriol crystals are thoroughly dissolved
in 110 gallons of tap water acidified with aluminum sulfate. The
copper sulfate solution is added to 4000 gallons of 48-50% aluminum
sulfate to produce a 1% copper sulfate solution. The
algicide-flocculant solution is metered into the clarifier of a
water plant at a dosage of about 30 ppm.
EXAMPLE 3
[0035] 440 pounds of blue vitriol crystals are thoroughly dissolved
in 110 gallons of tap water and acidified with aluminum sulfate.
The copper sulfate solution is added to a 4000 gallon mixture of
41% liquid alum and 5% cationic polymeric flocculent aid, to
provide a 1% copper sulfate solution having 0.25% active copper.
The algicide-flocculant solution is metered into the clarifier of a
water plant at a dosage of about 25 ppm.
EXAMPLE 4
[0036] 300 pounds of cupric chloride dihydrate crystals are fully
dissolved in 110 gallons of tap water, acidified with aluminum
sulfate. This copper chloride solution is added to a 4000 gallon
mixture of 46% aluminum sulfate and 1% cationic polymeric
flocculant aid, to make a 0.68% copper chloride solution having
0.25% active copper.
EXAMPLE 5
[0037] 490 pounds of blue vitriol crystals are completely dissolved
in 110 gallons of tap water and acidified with liquid ferric
sulfate. This copper sulfate solution is added to 3700 gallons of
38-42% liquid ferric sulfate, balance water, to make a 1% copper
sulfate solution having 0.25% active copper.
EXAMPLE 6
[0038] 245 pounds of blue vitriol crystals are thoroughly dissolved
in 110 gallons of tap water and acidified with liquid ferric
sulfate. This copper sulfate solution is added to a 3700 gallon
mixture of 38% ferric sulfate and 2% cationic polymeric flocculant
aid, to produce a 0.5% copper sulfate solution having 0.125% active
copper.
EXAMPLE 7
[0039] 335 pounds of copper chloride dihydrate are fully dissolved
in 110 gallons of tap water and acidified with liquid ferric
chloride. The copper chloride solution is added to 4100 gallons of
34-37% liquid ferric chloride, to make a 0.68% copper chloride
solution having 0.25% active copper.
EXAMPLE 8
[0040] 2200 pounds of blue vitriol crystals are thoroughly
dissolved in 550 gallons of tap water, and acidified with aluminum
sulfate. The copper sulfate solution is added to a 3475 gallon
mixture of 25% liquid alum, 10% cationic polymeric flocculant aid,
balance water, to provide a 5% copper sulfate solution having 1.25%
active copper.
[0041] It is hard to exaggerate the effectiveness of the
algicide-flocculant treatment of this invention in combating algae
growth. For example, in one application in South Texas, the water
plant had battled an algae bloom using the standard scattering of
blue vitriol pellets into the clarifier for several months.
Numerous complaints of bad tasting and bad smelling water were
received. Upon using a 1% copper sulfate-aluminum sulfate solution
of this invention, the bloom was over in a few days and complaints
of bad taste and bad smell stopped.
[0042] Another, more objective, measure of the effectiveness of
this invention is found by comparing copper concentrations in
clarifier water and in tap water. In the examples in Table II, a
copper sulfate-aluminum sulfate solution has been metered into a
municipal plant clarifier in accordance with this invention.
Substantially no copper is present in the raw water so all of the
copper in the clarifier is added by this invention. No free copper
is accumulating in the clarifier sludge. In other words, the copper
consumed in the clarifier is being used for its intended purpose,
i.e. to control algae growth. Table II tabulates the results of
trace copper analyses on tap and clarifier water in several South
Texas municipal water plants.
2TABLE II Cu conc. Cu conc. Cu in in consumed % Cu clarifier tap in
consumed water, water, clarifier, in location date mg/L mg/L mg/L
clarifier plant S 10/8/96 0.035 0.011 0.024 66% plant L 10/10/96
0.045 0.035 0.010 22% plant D 10/10/96 0.026 0.018 0.008 31% plant
O 10/11/96 0.043 0.026 0.017 40%
[0043] Upon reflection, it will be appreciated that the percentage
of copper consumed in the clarifier is very high. The copper
present in the clarifier water is very dilute. For the copper ion
to replace the magnesium ion in chlorophyll, the ions must come
very close together, the exact distance being measured in
Angstroms. Even so, a significant part of the copper added to the
clarifier by the technique of this invention is effective in
combating algae.
[0044] It will also be appreciated that the reported percentage of
copper consumed in the clarifier is understated because the
measured copper concentration in the clarifier is not necessarily
the same as the copper added to the clarifier. It is highly likely
that some copper is consumed by algae in the clarifier before the
water sample is taken that produces the results in Table II. Thus,
the amount of reported copper in the clarifier is always less than
the amount of copper added to the clarifier. The result is that the
reported percentage of copper consumed in the clarifier is
conservative.
[0045] Although this invention has been disclosed and described in
its preferred forms with a certain degree of particularity, it is
understood that the present disclosure of the preferred forms is
only by way of example and that numerous changes in the proportion
of the materials and the details of mixing and use may be resorted
to without departing from the spirit and scope of the invention as
hereinafter claimed.
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