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| United States Patent |
5,478,482 |
| Jones , et al. |
December 26, 1995 |
Method and compositions for treating recirculating water systems
Abstract
A novel method and compositions are disclosed for the treatment of water in
recirculating water systems. The method includes providing a boron level of at
least 20 ppm in the water, continually eroding into the water a compressed
sanitizer/algicide component including a halogen source material, a boron source
material, and glycoluril, and periodically adding to the water an oxidizing
clarifier comprising a chlorine source material, a non-halogen, chlorine source
material, and a boron source material. The invention also provides novel water
treatment chemicals including the compressed sanitizer/algicide component and
the clarifier useful in the foregoing system. The system and compositions are
safe and reliable, control algal and fungal growth and generally provide
improved water quality for recirculating water systems.
| Inventors: |
Jones; Ronald L. (Suwanee, GA);
Carlyle; Stephen L. (Stone Mountain, GA); Shelor; Susan M.
(Alpharetta, GA); Mitchell; Presley K. (Marietta, GA); Lines,
Jr.; Ellwood L. (Atlanta, GA) |
| Assignee: |
Bio-Lab, Inc. (Decatur, GA) |
| Appl. No.: |
243236 |
| Filed: |
May 16, 1994 |
| Current U.S. Class: |
210/753; 210/754; 210/755;
210/756; 210/764; 422/37; 424/657; 424/659; 424/660; 424/661 |
| Intern'l Class: |
C02F 001/50; C02F 001/76 |
| Field of Search: |
210/753,754,755,756,764 422/28,37
424/657,659,660,661,665 |
References Cited [Referenced
By]
U.S. Patent Documents
| 3702298 |
Nov., 1972 |
Zsoldos et al. |
210/62. |
| 3793216 |
Feb., 1974 |
Dychdala et al. |
252/187. |
| 3877890 |
Apr., 1975 |
Maisey et al. |
424/185. |
| 4296103 |
Oct., 1981 |
Laso |
424/130. |
| 4594091 |
Jun., 1986 |
Girvan |
71/67. |
| 4780216 |
Oct., 1988 |
Wojtowicz |
210/756. |
| 4880638 |
Nov., 1989 |
Gordon |
424/662. |
| 5221758 |
Jun., 1993 |
Maynard |
548/110. |
| 5356624 |
Oct., 1994 |
Croan et al. |
424/657. |
Other References
Marshall, M. S. and Hrenoff, A. K., "Bacteriostasis";
Journal of Infectious Diseases, vol. 61, p. 42, published 1937.
Kirk-Othmer, "Peroxides and Peroxy Compounds, Inorganic to Piping
Systems"; Encyclopedia of Chemical Technology, 3rd. ed., vol. 17, p. 1,
published by John Wiley & Sons, New York (1978).
|
Primary Examiner: McCarthy; Neil
Attorney, Agent or Firm: Woodard, Emhardt, Naughton Moriarty &
McNett
Claims
What is claimed is:
1. A method for controlling microbial growth
in water in recirculating water systems, which comprises the steps of:
a. providing a level of boron in the water of at least about 20 ppm;
b. eroding into the water a tablet component comprising a combination of
a halogen source material and a boron source material to add to the water the
halogen source material and the boron source material; and
c. adding
periodically to the water a clarifier composition which comprises a combination
of a chlorine source material, a non-halogen oxygen donor material, and a boron
source material.
2. The method of claim 1 in which step a. comprises
adding to the water an amount of a boron source material sufficient to provide a
level of boron in the water of from about 20 to about 50 ppm.
3. The
method of claim 2 in which the boron source material is selected from the group
consisting of boric acid, boric oxide, and compounds having the formula M.sub.n
B.sub.x O.sub.y.ZH.sub.2 O, in which M=sodium, potassium, calcium, magnesium or
ammonium, n=1 to 3, x=any whole number from 2 to 10, y=3x/2+1, and z=0 to 14.
4. The method of claim 3 in which the boron source material is a pH
neutral material.
5. The method of claim 4 in which the boron source
material comprises a combination of boric acid and a second, boron source
material selected from the group consisting of compounds having the formula
M.sub.n B.sub.x O.sub.y.ZH.sub.2 O, in which M=sodium, potassium, calcium,
magnesium or ammonium, n=1 to 3, x=any whole number from 2 to 10, y=3x/2+1, and
z=0 to 14.
6. The method of claim 1 in which the tablet component
comprises a halogen source material selected from the group consisting of
calcium hypochlorite, lithium hypochlorite, sodium dichloro-s-triazinetrione,
potassium dischloro-s-triazinetrione, trichloro-s-triazinetrione, brominated
hydantoins and brominated glycoluril, and a boron source material selected from
the group consisting of boric acid, boric oxide, and compounds having the
formula M.sub.n B.sub.x O.sub.y.ZH.sub.2 O, in which M=sodium, potassium,
calcium, magnesium or ammonium, n=1 to 3, x=any whole number from 2 to 10,
y=3x/2+1, and z=0 to 14.
7. The method of claim 6 in which the tablet
component comprises 50.0 to 99.9 parts halogen source material and 0.1 to 50.0
parts boron source material.
8. The method of claim 7 in which the
tablet component comprises 80.0 to 95.0 parts halogen source material and 5.0 to
20.0 parts boron source material.
9. The method of claim 6 in which the
tablet component further comprises glycoluril.
10. The method of claim 9
in which the glycoluril is selected from the group consisting of unsubstituted
glycoluril, alkyl-substituted glycoluril, phenyl-substituted glycoluril,
chloro-substituted glycoluril and bromo-substituted glycoluril.
11. The
method of claim 10 in which the tablet component comprises 0.1 to 5.0 parts
glycoluril.
12. The method of claim 11 in which the tablet component
comprises 50.0 to 99.9 parts halogen source material and 0.1 to 50.0 parts boron
source material.
13. The method of claim 11 in which the tablet
component comprises 1.0 to 3.0 parts glycoluril.
14. The method of claim
13 in which the tablet component comprises 80.0 to 95.0 parts halogen source
material and 5.0 to 20.0 parts boron source material.
15. The method of
claim 1 in which the clarifier composition comprises chlorine source material
selected from the group consisting of lithium hypochlorite, and sodium or
potassium dichloro-s-triazinetrione, non-halogen oxygen donor material selected
from the group consisting of peroxydisulfates and persulfuric acid salts, and
boron source material selected from the group consisting of boric acid, boric
oxide, and compounds having the formula M.sub.n B.sub.x O.sub.y.ZH.sub.2 O, in
which M=sodium, potassium, calcium, magnesium or ammonium, n=1 to 3, x=any whole
number from 2 to 10, y=3x/2+1, and z=0 to 14.
16. The method of claim 15
in which the clarifier composition of step c. comprises 1 to 99 parts chlorine
source material, 1 to 99 parts non-halogen oxygen donor material, and 1 to 75
parts boron source material.
17. The method of claim 16 in which the
clarifier composition comprises 30 to 60 parts chlorine source material, 5 to 50
parts non-halogen oxygen donor material, and 5 to 50 parts boron source
material.
18. The method of claim 17 in which the clarifier composition
consists essentially of chlorine source material, non-halogen oxygen donor
material, and boron source material.
Description
FIELD OF THE INVENTION
This invention relates to methods and
compositions for the treatment of recirculating water systems such as cooling
towers, evaporative condensers, air washers, swimming pools, hot tubs and spas.
The invention particularly relates to controlling microbial growth, particularly
algae and fungi growth.
BACKGROUND OF THE INVENTION
Swimming
pools, hot tubs and spas, as well as other water systems, are subject to
contamination from microbes, e.g., algae and fungus, causing unwanted
discoloration and turbidity in the water system. Typical organisms that will
grow in the water in such systems include Chlorococcum, Chlorella, Cledaphora,
Microcystis, Oscilratoris, Spirosyra, Olaothrisx, Vanetteria, and Aspergilles
flavus. The prevention or inhibition of growth of these microorganisms in water
systems has been a problem.
It is customary to treat water systems with
one or more sanitizers and/or sanitizer/oxidizer combinations to control the
growth of microorganisms. The sanitizers most commonly used to control the
growth of microorganisms are chemicals that generate hypochlorite or hypobromite
species when dissolved in water. There are many hypochlorite generating
chemicals, with the more common ones being chlorine gas, alkali metal
hypochlorites such as sodium hypochlorite, alkaline earth metal hypochlorites
such as calcium hypochlorite and lithium hypochlorite, halogenated hydantoins
and chlorinated isocyanuric acid derivatives such as sodium or potassium
dichloro-s-triazinetrione.
Although the foregoing halogen species are
excellent water treatment agents, it can be difficult to maintain an efficient
level of the halogens to control the growth of the microorganisms. This is
especially true for bromine systems and unstabilized chlorine systems. Thus, it
is necessary with these systems to continuously replace the lost halogens. With
this type of treatment program, there frequently are periods of unnecessarily
high halogen levels which are wasteful of the chemicals, and of low to no
halogen levels which invite the growth of microorganisms.
Hydrogen
peroxide and other inorganic peroxygen compounds, in particular persulfates and
persulfuric acids and their salts, are known to be active oxygen containing
compounds which are also used for oxidation of water systems. However,
hypochlorite compounds and active oxygen compounds generally are not used
together to treat water systems. In fact, the manufacturers of both chlorine
compounds and peroxygen compounds, as well as other literature sources, have
recommended against the blending of these compounds due to their chemical
incompatibilities which may lead to explosions or fire.
Also, the
Encyclopedia of Chemical Technology (Kirk-Othmer), volume 17, page 1, reports
that hydrolysis to H.sub.2 O.sub.2 followed by the disproportionation of H.sub.2
O.sub.2 is the main path for decomposition of inorganic peroxide, e.g.,
K.sub.2 S.sub.2 O.sub.8 +2 H.sub.2 O.fwdarw.2 KHSO.sub.4 +H.sub.2
O.sub.2
Inorganic peroxides neutralize chlorine in water by acting as
dechlorinating agents:
HOCl+H.sub.2 O.sub.2 .fwdarw.O.sub.2 (Ag)+H.sup.+
+Cl.sup.- +H.sub.2 O
Based on the preceding information, it would appear
that a combination of these types of compounds would be impractical.
The
separate addition of chlorine compounds and a peroxy compound as oxidizing
agents is taught in U.S. Pat. No. 3,702,298 issued November 1972 to F. J.
Zsoldos et al. This patent teaches the addition of peroxy compounds to swimming
pool water containing multivalent metals such as Ag and Cu to raise the valence
of the metals to a level at which the metals provide an oxidizing action.
Chlorine may also be present as disinfectant in the water system. However, it
has not been suggested that chlorine source materials be physically combined
with the peroxy compounds in the same dry composition.
In U.S. Pat. No.
4,780,216, issued Oct. 25, 1988 to John A. Wojtowicz, there are disclosed
calcium hypochlorite sanitizing compositions consisting essentially of a mixture
of calcium hypochlorite and a peroxydisulfate comound. The compositions are
indicated to be useful in sanitizing water while helping to minimize the
increase in the pH of the water.
In U.S. Pat. No. 4,594,091, issued Jun.
10, 1986 to John W. Girvan, a method of controlling algal and fungal growth
using sodium tetraborate or potassium tetraborate in water systems is disclosed.
The Girvan patent teaches a method of adding from 10 to 500 ppm boron to water
systems. Girvan teaches the separate addition of the boron material,
particularly sodium tetraborate, to a water system, which may also include a
sanitizer. The results achieved with this approach vary greatly from one
swimming pool to the next.
The use of calcium hypochlorite mixed with
water-soluble, hydrated inorganic salts to provide a composition which is
resistant to exothermic, self-propagating decomposition is disclosed in U.S.
Pat. No. 3,793,216, issued to Dychdala et al. on Feb. 19, 1974. The inorganic
salts are selected from various hydrated alkali metal and alkaline earth metal
phosphates, silicates, borates, carbonates and sulfates.
It has also
been known in the prior art to combine boric acid and
trichloro-s-triazinetrione. This combination has been described by industry
practice for the purpose of increasing solubility and reducing overall raw
material costs.
The present invention is surprising in its divergence
from teachings of the prior art. For example, the prior art has included
indications that boron materials would not be efficacious at the levels utilized
herein. See, e.g., Marshall and Hrenoff, Journal of Infectious Diseases, vol.
61, p. 42 (1937).
The prior art systems for the treatment of water for
controlling growth of antimicrobials have generally had difficulties with
providing consistently dependable results. Theoretical approaches have had
shortcomings in practice because of the need for careful attention to water
chemistries. The best of systems are inadequate if they are too difficult to be
used in practice. The present system and compositions address this problem by
providing a simple, reliable and consistent system for the treatment of water
systems.
SUMMARY OF THE INVENTION
Briefly describing one aspect
of the present invention, there is provided a system for the treatment of water
systems to control microbial growth. The system includes the addition of boron
to the level of at least about 20 ppm in the water, use of a solid form
component to continually add both halogen and boron to the water to help
maintain the desired levels of both of these components in the water, and the
periodic addition of a clarification treatment which combines a chlorine
compound, a non-halogen, oxidizing compound and a boron source material. The
system provides an effective, reliable approach to the treatment of water. In
addition, the present invention includes an erodible, boron-containing,
compressed sanitizer/algicide component and an oxidizing clarifier.
It
is an object of the present invention to provide a method and compositions for
treating water in recirculating water systems to achieve improved water quality
more consistently.
A further object of the present invention is to
provide for the treatment of water in swimming pools, hot tubs and spas which
allows for quicker swimmer reentry in accordance with current regulatory
guidelines.
It is another object of the present invention to provide
chemicals useful for water treatment which are safer to transport and use, and
which have reduced decomposition and packaging deterioration.
Further
objects and advantages of the present invention will be apparent from the
following descriptions and examples.
DESCRIPTION OF THE PREFERRED
EMBODIMENT
The present invention provides a comprehensive system for the
treatment of recirculating water systems utilizing specific compositions which
provide improved efficacy and reliability for the control of algae and other
microorganisms. The compositions include (1) an initial boron contributor, (2) a
solid-form, compressed halogen/boron sanitizer/algicide product, and (3) an
oxidizing clarifier comprising a chlorine compound, a non-halogen oxidizer, and
a boron source. This system has been shown to consistently provide significantly
improved results over prior approaches. These results have been achieved despite
teachings in the prior art which have suggested away from the present invention.
The present invention provides a system and compositions for the
treatment of a variety of recirculating water systems. For example, the
invention is useful for the treatment of cooling towers, evaporative condensers,
air washers, swimming pools, hot tubs and spas. The system and compositions are
readily adapted for use in these and other environments.
No particular
mechanisms of action for the compositions and methods of the present invention
are claimed. However, it has been observed that the present invention provides
enhanced water quality on a more consistent basis. One explanation for this is a
synergistic effect of the boron materials in the water in combination with, for
example, adjunct clarifying materials. A second explanation is the operation of
the oxidizing clarifier to remove organic impurities, thereby enabling improved
control of microorganisms by the primary, halogen-containing compressed
sanitizer/algicide component.
The present system includes the use of a
boron source material for establishing initial boron levels in the treated
water. This is complemented by the subsequent, sustained addition of a
combination of halogen-source material and boron-source material. Finally, a
third composition, added periodically during the period of treatment, enhances
the operation of the overall system.
The novel method utilizes a boron
source composition comprising a source of solubilized boron for the water. At
the pH of the water systems, e.g., neutral pH in the range 6-8, the boron will
be present in the water primarily in the form of triborate [B303(OH)4]-1 and
tetraborate [B405(OH)4]-2 polyions. The boron source composition is added
initially to the water system, for example at the beginning of a pool season, to
bring the boron level to at least 20 ppm (by weight). The term boron level, as
used herein, refers to measurement in terms of elemental boron. The preferred
boron level in the treated water ranges from about 20 to about 50 ppm, although
higher ranges will work. The most preferred range is 20-26 ppm.
The
boron source material may be any suitable compound or mixture. For example, this
material may be selected from the group consisting of boric acid, boric oxide
(anhydrous boric acid), and compounds having the formula MnBxOy.ZH2O, in which
M=any alkali earth or metal/non-metallic cation including but not limited to
sodium, potassium, calcium, magnesium and ammonium, n=1 to 3, x=any whole number
from 2 to 10, y=3x/2+1, and z=0 to 14. The boron compounds include, for example,
disodium tetraborate decahydrate, disodium tetraborate pentahydrate, disodium
tetraborate tetrahydrate, disodium octaborate tetrahydrate, sodium pentaborate
pentahydrate, sodium metaborate tetrahydrate, sodium metaborate bihydrate,
dipotassium tetraborate tetrahydrate, potassium pentaborate tetrahydrate,
diammonium tetraborate tetrahydrate, and ammonium pentaborate tetrahydrate.
It is generally desirable to maintain a neutral pH in the water systems
treated by the present invention. For example, swimming pools are preferably
maintained in the range of pH 7-8. At this pH, the boron will appear as
polyborate and tetraborate polyions. The addition of certain species of boron,
such as tetraborate, will raise the pH of a neutral pH system. For example, the
addition of sodium tetraborate sufficient to add 20 ppm of boron to the water,
about 1 pound per 1000 gal water, will typically raise a neutral pH to about
9.0-9.5. If a pH-raising boron source material is used, it is then required to
add a compatible acid, for example sodium bisulfate or muriatic acid, to adjust
the pH back to the desired range.
In the alternative, a pH neutral
composition including the boron source material may be used. In particular,
boric acid may be used in combination with another boron source, such as the
pH-raising borates previously described. A preferred composition is a
combination of boric acid and a tetraborate, particularly sodium tetraborate. In
this embodiment, the composition preferably comprises 50-100 parts boric acid
and 0-50 parts tetraborate, most preferably 90 parts boric acid and 10 parts
tetraborate, parts being by weight. Sodium tetraborate (5 mol) is the preferred
compound in this regard.
The second component is a solid form material,
hereafter referred to as the "compressed sanitizer/algicide component", which
includes both a halogen-source composition and a boron-source composition. These
materials are blended and formed into a tablet, puck, stick or other solid form
that is conveniently eroded into the system water in conventional fashion, such
as by use in a skimmer basket or floater. This compressed sanitizer/algicide
component continually adds both halogen and boron into the water, which assists
in keeping the level of both components at the desired ranges.
The
halogen-source component may be selected from any compatible halogen material
useful in solid form. The halogen is selected from either chlorine or bromine,
and may comprise any solid-form material which provides the halogen in the form
of hypohalite ions, i.e. hypochlorite or hypobromite ions, or as hypohalous
acid. For example, the halogen-source component may include various chlorine
compounds including calcium hypochlorite, lithium hypochlorite, sodium
dichloro-s-triazinetrione, potassium dischloro-s-triazinetrione and
trichloro-s-triazinetrione. Suitable bromine compounds include brominated
hydantoins and brominated glycoluril.
The boron-source composition is
included to provide improved characteristics for the tablet and to assist in
maintaining the boron level in the water at a desired level. The boron material
has been found to enhance the tablet component in several respects. The tablets
formulated with the boron source material have reduced off-gassing of chlorine
gas. Consequently, the product has less packaging deterioration and reduced
levels of noxious chlorine odor. Also, the boron material is preferably present
in an amount to provide a significant supplement to the boron in the water.
The boron material may be selected from any of the boron source
compositions previously identified. That is, the boron source material is
selected from the group consisting of boric acid, boric oxide, and compounds
having the formula M.sub.n B.sub.x O.sub.y.ZH.sub.2 O, in which M, n, x, y and Z
are as previously defined.
The respective ranges of the halogen and
boron source materials in this second component may therefore vary considerably.
The suitable ranges can be readily determined by those in the art based on the
water system to be treated, desired erosion rate and/or other physical
characteristics of the solid-form component, and other parameters. In one
respect, the halogen is preferably present in an amount sufficient to maintain
the desired active halogen level in the water, for example 0.5 to 3.0 ppm
hypohalite ion in swimming pool water. Also, it has been determined that at
least certain boron materials will adversely affect the ability to compound the
overall composition into a solid form having desirable erosion characteristics.
Therefore, there may be a practical limitation on the amount of boron material
which is compounded into the compressed sanitizer/algicide component. In view of
these considerations, the compressed sanitizer/algicide component preferably
comprises 50.0 to 99.9 parts, more preferably 80.0 to 95.0 parts, of the halogen
source material, and 0.1 to 50.0 parts, more preferably 5.0 to 20.0 parts, of
the boron source material. As used herein, "parts" refers to parts by weight.
It has also been discovered that the addition of glycoluril will provide
advantages both in the compounding of the halogen and boron materials into solid
form having a controlled, consistent erosion rate, and in enhancing the release
and availability of halogen in the water. This is particularly advantageous
since the presence of a boron source material in the tablet will otherwises
result in a substantially increased erosion rate. Combination of the boron and
halogen source materials otherwise provides a solid material which erodes too
quickly for use in conventional systems.
The term glycoluril, unless
indicated otherwise, is used to generally to refer to compounds including
unsubstituted glycoluril, alkyl-substituted glycoluril, phenyl-substituted
glycoluril, chloro-substituted glycoluril and bromo-substituted glycoluril. The
compressed sanitizer/algicide component obtains the desired erosion
characteristics with a surprisingly low amount of glycoluril. The tablet
component may be suitably formulated with not more than 5.0 parts glycoluril.
More preferably, the tablet component includes 1 to 3 parts glycoluril. For
example, a particularly preferred composition of the tablet component consists
of 92.5 parts TCCA, 5 parts sodium tetraborate, and 2.5 parts glycoluril.
The present invention also contemplates the use of an oxidizing
clarifier which provides greatly enhanced removal of organic impurities. The
clarifier component comprises a unique composition including a chlorine source
material, a non-halogen, oxygen donor and a boron source compound. This
combination is useful in itself as a clarifier, aside from the system of the
present invention. In addition, when used in the overall system described
herein, the clarifier provides a supplement for the halogen and boron levels
already in the water. When used in the overall system, the oxidation and
clarification properties by the clarifier component enhance the control of
microorganisms by the compressed santizer/algicide component. This third
composition also constitutes a surprisingly safe combination of these materials
for use.
For the clarifier component, the chlorine source material is a
hypochlorite donor selected from lithium hypochlorite, sodium or potassium
dichloro-s-triazinetrione, and trichloro-s-triazinetrione. When used in the
foregoing overall system, however, the clarifier component would not include the
trichloro-s-triazinetrione.
The non-halogen, oxygen donor is selected
from peroxydisulfates and persulfuric acid salts. The peroxydisulfates may
include those having the formula: N.sub.w S.sub.2 O.sub.8 where N is an alkali
metal or alkaline earth metal or ammonium, and w is 1 or 2. The alkali metal may
include sodium, potassium or lithium. The alkaline earth metal may include
calcium or magnesium. The persulfuric acid salts include such compounds as
KHSO.sub.4, K.sub.2 SO.sub.4 and 2KHSO.sub.5. An example of a commercial product
of persulfuric acid salts is sold by DuPont under the name OXONE.TM., which
consists essentially of a combination of the compounds KHSO.sub.4, K.sub.2
SO.sub.4 and 2KHSO.sub.5.
The boron source compound is selected from the
group previously defined. Particularly preferred compounds are sodium
tetraborate and its derivatives.
For the clarifier component, the
constituent materials may be present over a broad range. Selection of
appropriate ranges can be accomplished by those in the art based on the
teachings herein and consideration of general principles known for the treatment
of water. The hypochlorite donor component preferably is present in an amount
from 1 to 99 parts, most preferably from 30 to 60 parts, by weight. The
non-halogen, oxygen donor component of the composition preferably is present in
an amount from 1 to 99 parts, more preferably from 5 to 50 parts, by weight. The
boron containing component preferably is present in an amount from 1 to 75
parts, more preferably from 5 to 50 parts, by weight. In a preferred embodiment,
the clarifier consists essentially of the three components, in which case the
foregoing amounts constitute weight percentages in the overall composition.
The clarifier component may additionally include additives comprising
algicides, clarifying agents such as aluminum sulfate, dispersants, flocculants
and other chemicals typically used for the treatment of water systems. By way of
example, a preferred composition of the clarifier includes 60% sodium
dichloro-s-triazinetrione, 20% sodium persulfate, 10% sodium tetraborate, and
10% aluminum sulfate (an additional clarifying agent).
The clarifier
component of the present invention may be produced in any suitable dry form. For
example, the clarifier could be in the form of granules, pellets, sticks or
tablets. The product is preferably compounded in a form to provide relatively
rapid dispersion, for example within a few hours. This product is added on a
periodic basis, for example weekly, to provide the desired additions of the
substituent materials, i.e., hypochlorite, oxidant and boron. For example, for
application to swimming pool water the material is typically added at the rate
of about 1#/10,000 gallons of pool water. This clarifier product is designed to
oxidize organic and inorganic contaminants and to replace boron that is lost
through loss of pool water.
In addition to enhancing the removal of
microorganisms by the compressed santizer/algicide component, the novel
compositions of the present invention are safer to transport and use. That is,
the combination of three components yields a safer composition than for certain
of the individual components, such as the chlorine source material. For example,
sodium dichloro-s-triazinetrione is classified as an oxidizer per DOT
regulations. This classification indicates certain levels of safety risks and
transportation constraints. By contrast, clarifier products formulated based on
this disclosed invention have been found to be non-oxidizers by DOT test, which
carry fewer safety risks and transportation limitations.
The following
examples are presented to illustrate more fully the present invention:
EXAMPLE 1
The boron level in treated water is raised with
various boron containing compounds. Addition of each of the following compounds
in appropriate amounts provides a boron level in excess of 20 ppm in the water:
boric acid, boric oxide, disodium tetraborate decahydrate, disodium tetraborate
pentahydrate, disodium tetraborate tetrahydrate, disodium octaborate
tetrahydrate, sodium pentaborate pentahydrate, sodium metaborate tetrahydrate,
sodium metaborate bihydrate, dipotassium tetraborate tetrahydrate, potassium
pentaborate tetrahydrate, diammonium tetraborate tetrahydrate, and ammonium
pentaborate tetrahydrate. Similarly, addition of appropriate amounts of the
foregoing compounds provides typically desirable amounts of boron levels in the
water, for example, 20, 26, 30 and 50 ppm. As previously indicated, a preferred
composition is a combination of boric acid and a pH-raising boron compound, such
as a tetraborate. Combination of these two components in amounts of 50, 90 and
100 parts boric acid, and 50, 10 and 0 parts sodium tetraborate, respectively,
provide compositions which suitably add boron to the water and permit control of
the water pH.
EXAMPLE 2
The compressed sanitizer/algicide is
prepared from various combinations of halogen and boron source compounds. The
halogen compounds include calcium hypochlorite, lithium hypochlorite, sodium
dichloro-s-triazinetrione, potassium dichloro-s-triazinetrione and
trichloro-s-triazinetrione, brominated hydantoins and brominated glycoluril. The
boron source compounds include those identified in Example 2. The foregoing
compounds are formulated into compressed tablets and the like in conventional
fashion. The tablets are prepared with various amounts of the components, for
example 50 and 99.9 parts halogen compound and 0.1 and 50 parts boron
composition, respectively, and upon erosion of the tablets, etc. into water
provide increased levels of halogen and boron in the water. In addition, tablets
are compounded with up to about 5 parts glycoluril of the various types
previously indicated, and including at levels of 2 and 3 parts glycoluril. Such
solid-forms of the sanitizer/algicide compositions are readily compounded, erode
at suitable rates, and provide desirable amounts of halogen and boron to the
water.
EXAMPLE 3
The clarifier compositions are formulated by
conventional compounding techniques from the components previously identified.
Included are hypochlorite donors selected from lithium hypochlorite, sodium and
potassium dichloro-s-triazinetrione, and trichloro-s-triazinetrione. Also
provided are the non-halogen oxidizers including peroxydisulfates and
persulfuric acid salts previously identified. Finally, the boron compounds are
included from the previous list. Mixing of these components in amounts of 1, 30,
60 and 99 parts hypochlorite donor, 1, 5, 50 and 99 parts non-halogen oxidizer,
and 1, 5, 50 and 75 parts boron containing compound provides an oxidizer
composition which provides improved clarity to the treated water.
EXAMPLE 4
The Department of Transportation (DOT) manages and
regulates transportation of hazardous materials. The DOT oversees the
classification, description, marking, labeling, packaging, and condition of
hazardous materials transported in the United States. The DOT regulations for
the transportation of hazardous materials are currently set forth in 49 C.F.R.
parts 171-180. Guidelines for the classification, packing group assignment and
test methods for oxidizers (Division 5.1 materials) are set forth in Appendix F
to Part 173, and provide a test method to measure the potential for a solid
substance to increase the burning rate or burning intensity of a combustible
substance when the two are thoroughly mixed.
In practice, two tests are
run in triplicate for each substance to be evaluated, one at a 1 to 1 ratio, by
mass, of the sample to sawdust, and one at a 4 to 1 ratio. For materials
classified in Division 5.1, the burning characteristics of each mixture are
compared with a standard having a 1 to 1 ratio, by mass, of potassium
perchlorate and potassium bromate, as appropriate, to sawdust. For materials
classified in Division 4.1, the packing group is determined using the same
method; with ammonium persulfate substituted for the potassium compound.
Potassium perchlorate, potassium bromate and ammonium persulfate
therefore are reference substances. For use in testing, these substances should
pass through a sieve mesh size smaller than 0.3 mm and should not be ground. The
reference substances are dried at 65 degrees C. for 12 hours and kept in a
desiccator until required. The combustible material for this test is softwood
sawdust. It should pass through a sieve mesh sampler smaller than 1.6 mm and
should contain less than 5% of water by weight.
A 30.0.+-.0.1 g mixture
of the reference substance and sawdust in a 1 to 1 ratio, by mass, is prepared.
For comparison, two 30.0.+-.0.1 g mixtures of the material to be tested, in the
particle size in which the material is to be transported, and the sawdust, are
prepared in ratios of 1 to 1 by mass, and 4 to 1 by mass. Each mixture is mixed
mechanically as thoroughly as possible without excessive stress. The test is
conducted in a ventilated area under the following ambient conditions:
temperature--20 degrees C..+-.5 degrees C.; humidity--50 percent .+-.10 percent.
Each of the mixtures is formed into a conical pile with dimensions of
approximately 70 mm base diameter and 60 mm height on a cool, impervious,
low-heat conducting surface. The pile is ignited by means of a wire of inert
metal in the form of a circular loop 40 mm in diameter positioned inside the
pile 1 mm above the test surface. The wire is heated electrically to 1000
degrees C. until the first sign of combustion is observed, or until it is clear
that the pile cannot be ignited. The electrical power used to heat the wire is
turned off as soon as there is combustion. The time is recorded from the first
observable sign of combustion to the end of all reaction: smoke, flame,
incandescence. The test is repeated three times for each of the two mixing
ratios.
A substance is classified in Division 5.1 if, in either
concentration tested, the mean burning time of the sawdust, established from
three tests, is equal to or less than that of the average of the three tests
with the ammonium persulfate mixture. Packing Group I is assigned to any
substance which, in either mixture ratio tested, exhibits a burning time less
than potassium bromate. Packing Group II is assigned to any substance which, in
either mixture ratio tested, exhibits a burning time equal to or less than that
of potassium perchlorate and the criteria for Packing Group I are not met.
Packing Group III is assigned to any substance which, in either mixture ratio
tested, exhibits a burn time equal to or less than that of ammonium persulfate
and the criteria for Packing Groups I and II are not met.
Samples
identified in Table 1 were subjected to oxidizer testing in accordance with the
preceding test procedures. When the samples were subjected to the oxidizer
testing, it was anticipated that the compositions would at least remain in the
Division 5.1 oxidizer category, since that is the classification for sodium
dichloro-s-triazinetrione. However, surprisingly, the tests indicated that all
three samples were classified as non-oxidizers per DOT standards. These results
are contrary to what would be expected, particularly in view of the fact that
manufacturers of chlorine oxidizers and oxygen based oxidizers strongly
recommend that these materials not be blended together due to incompatibilities.
TABLE 1
______________________________________
SAMPLE #
150A 147A 150B
______________________________________
Sodium dichloro-s-triazinetrione
60% 60% 60%
Sodium persulfate 20% 30% --
Sodium tetraborate 5 mol
10% 10% 10%
Aluminum sulfate 10% -- 10%
Oxone -- -- 20%
______________________________________
EXAMPLE 5
The three compositions from Example 1 were
subjected to additional hazard testing to determine any incompatibilities. The
tests performed were DTA, Dust Explosion severity, impact sensitivity and self
heating test. The test results are summarized hereafter, in which DPS refers to
sodium persulfate; "dichlor" refers to sodium dichloro-s-triazinetrione, ACL-60
refers to sodium dichloro-s-diazinetrione, borate refers to sodium tetraborate,
alum refers to aluminum sulfate, glycoluril refers to unsubstituted glycoluril,
and all percentages are by weight.
JANAF THERMAL STABILITY
100%
sodium dichloro--slight exotherm at 140 degrees C.; sharp, powerful exotherm at
147 degrees C.; (rupture disc) catastrophic decomposition, too quick to
determine temp/press; would be classified as flammable for transportation.
IMPACT SENSITIVITY
49.5% sodium dichlor, 49.5% sodium
monopersulfate and 1% glycoluril--50% probability of initiation at 18.5 inches.
41% sodium dichlor--50% probability of initiation at 18.5 inches.
DUST EXPLOSION SEVERITY
60% ACL-60, 20% OXONE, 10% borate and
10% alum--no trial produced a positive result.
60% ACL-60, 30% DPS and
10% borate--no trial produced a positive result.
60% ACL-60, 20% DPS,
10% borate and 10% alum--no trial produced a positive result.
IMPACT
SENSITIVITY
60% ACL-60, 30% DPS, and 10% borate--each material was
subjected to the maximum drop height of 36" with the 2 kgm weight for men trials
per material, using a fresh sample each time. No positive result was obtained in
any trial.
60% ACL-60, 20% DPS, and 10% borate--each material was
subjected to the maximum drop height of 36" with the 2 kgm weight for ten trials
per material, using a fresh sample each time. No positive result was obtained in
any trial.
60% ACL-60, 20% OXONE, 10% borate and 10% alum--each material
was subjected to the maximum drop height of 36" with the 2 kgm weight for ten
trials per material, using a fresh sample each time. No positive result was
obtained in any trial.
JANAF THERMAL STABILITY (DTA)
60% ACL-60,
20% DPS, 10% borate and 10% alum--in the initial trial with this material,
exothermic behavior was observed at about 111 degrees C. Sample temperature rose
over about 90 seconds to about 130 degrees C., held about 30 seconds, then rose
to about 140 degrees C. over about 30 seconds, where a sharp, catastrophic
reaction caused rupture to the 3000 psig disc. A replicate trial produced
essentially identical results.
60% ACL-60, 20% OXONE, 10% borate and 10%
alum--in the initial trial with this material, exothermic behavior was observed
at about 111 degrees C. Sample temperature rose over about 60 seconds to about
124 degrees C., paused about 60 seconds, then rose to about 140 degrees C. over
about 30 seconds, where a sharp, catastrophic reaction caused identical results,
except that the transition points were less sharply defined.
JANAF
THERMAL STABILITY
60% ACE-60, 30% DPS and 10% borate--in the initial
trial with this material, exothermic behavior was observed at about 137 degrees
C. About 60 seconds later, at about 152 degrees C., a sharp, catastrophic
reaction caused rupture of the 3000 psig disc. A replicate trial produced
identical results.
OXIDIZER TESTING
60% ACL-60, 30% DPS and 10%
borate--based on the test results, it is recommended that the material
represented by this sample does not need to be classified as an oxidizer, as
defined by CFR 49, section 173, Appendix F. Note that while the average burn
time of the 4 to 1 ratio was shorter than the reference, the material was not
completely consumed.
60% ACL-60, 20% DPS, 10% borate and 10% alum--based
on the test results, it is recommended that the material represented by this
sample does not need to be classified as an oxidizer, as defined by CFR 49,
section 173, Appendix F. Note that the average burn time of the 1 to 1 ratio
mixture burned considerably longer than the reference. Also, while the average
burn time of the 4 to 1 ratio mixture was shorter than the reference, the
material was not completely consumed.
60% ACL-60, 20% OXONE, 10% borate
and 10% alum--based on the test results, it is recommended that the material
represented by this sample does not need to be classified as an oxidizer, as
defined by CFR 49, section 173, Appendix F. Note that the average burn time of
the 1 to 1 ratio mixture burned considerably longer than the reference. Also,
while the average burn time of the 4 to 1 ratio mixture was shorter than the
reference, the material was not completely consumed.
UN CLASS 4.1
PRELIMINARY SCREEN TEST
60% ACL-60, 20% OXONE, 10% borate and 10%
alum--the sample was formed into an unbroken strip about 250 mm long by 20 mm
wide by 10 mm high on a cool, impervious (steel) base plate. Ignition of the
sample was attempted at one end by a gas burner. The sample would not sustain
ignition after two minutes exposure to the flame. Based on this result, the UN
4.1 Burn Rate Test is not required.
UN CLASS 4.2 PRELIMINARY SCREEN TEST
60% ACL-60, 20% OXONE, 10% borate, and 10% alum--1155.4 grams of the
sample were placed into a 10 cc wire mesh basket and covered with a larger wire
mesh basket. The sample was maintained at 140 degrees C. for 24 hours. Starting
at ambient temperature, the sample temperature slowly climbed and matched the
oven temperature about nine hours after the start. The temperature continued to
rise, reaching a maximum temperature of 149 degrees C. about 12 hours after
start. The temperature then began to fall, dropping to 146 degrees C., where it
remained for the rest of the 24 hour test period. After the test, the sample was
allowed to cool, then reweighed and examined. The sample experienced an 89.6
gram weight loss and did not exhibit visible change.
Results/Discussion:
The impact sensitivity testing for all three compositions was negative, which
indicates that the composition will not explode on impact. The key indicator for
compatibility is the results of the DTA testing. The compositions that contained
no alum exhibited exotherms at 137 degrees C., which is approximately the same
for 100% ACL-60 (140 degrees C.). The composition which contained alum exhibited
exotherms around 111 degrees C. Although these exotherms for the alum containing
compositions occurred at a lower temperature, these compositions are still
considered as safe as calcium hypochlorite which exotherms at 111 degrees C. The
overall results of the combined hazard testing indicate that these blends will
be stable and safe to transport, store and use.
EXAMPLE 6
Several compositions were tested for storage stability at elevated
temperatures. Two-hundred gram samples of the composition were prepared and
sealed in one quart pastic bottles. The bottles were fitted with two stopcocks
which allow the removal of collected gases. The bottles were then placed into an
oven at 50 degrees C. for 72 hours. At the end of 72 hours, the bottles were
removed from the oven and collected gas was removed from the head space by
blowing dry air into the bottle which forced the collected gas into a gas
collecting cylinder which contained a solution of potassium
iodide/water/ethanol. The KI solution was titrated with sodium thiosulfate and
the mg of chlorine gas was calculated. The results are summarized in Table 2.
TABLE 2
______________________________________
TEST SUBSTANCE/RESULTS
SODIUM
DICHLORO-
BOTTLE S-TRIAZINE-
# TRIONE OXONE BORAX Mg.Cl.sub.2
______________________________________
A 60% 30% 10% 0.71
B 60% 40% -- 1.20
C 100% -- -- 1.10
______________________________________
The test results indicate that the compositions are stable and do
not produce excessive chlorine gas during storage at elevated temperatures.
EXAMPLE 7
In this example the oxidation performance of several
oxidizer compounds were evaluated. The oxidation performance was determined by
measuring the destruction of crystal violet dye. The following protocol was
followed:
This protocol is designed to evaluate several oxidizer
compounds and combinations of oxidizer compound as potential shock products to
be used in pools and spas.
REAGENTS: Crystal Violet Dye Solution
APPARATUS: pH Meter: (equipped with platinum electrode) HACH 3000,
Spectrophotometer
PROCEDURE:
1) Prepare the following test
solutions:
______________________________________
COLUMN A ppm ACTIVE
DILUTION AT USE
TEST CMPD. gm/L AMOUNT DILUTIONS
______________________________________
Lithium hypochlorite
2.86 8 ml/l 8 ppm Cl.sub.2
Oxone 1.00 11 ml/l 0.5 ppm O.sub.2
DPS 1.00 11 ml/l 0.5 ppm O.sub.2
H.sub.2 O.sub.2
3.70 30 ml/l 30 ppm
______________________________________
2) Into 1500 ml beakers add 1000 mls of distilled water, 1.64 gm
of phosphate buffer (pH 7.2-7.6) and 15 drops of crystal violet dye solution.
Mix until uniform.
3) Measure initial color number on the HACH 3000
spectrophotometer. Follow HACH method #16. Use distilled water as a blank.
4) Add dilution amount of oxidizer from Column A to the 1 500 ml beaker.
Allow to mix 5 mins.
5) Allow beakers to stir for 2 hours. Monitor color
number. Calculate percent color reduction.
The results are summarized in
Table 3.
TABLE 3
______________________________________
TEST Cl.sub.2 /O.sub.2 Ratio
Initial 2 Hour % Color
COMPOUND (ppm) Color # Color #
Reduction
______________________________________
LiOCl/Oxone
8.0/0.5 244 37 85%
LiOCl/DPS 8.0/0.5 292 26 91%
LiOCl/H.sub.2 O.sub.2
8.0/30.0 296 268 9.5%
LiOCl 8.0/O 288 120 58%
DPS 0/0.5 252 252 0
Oxone 0/0.5 257 162 37%
______________________________________
DPS = Sodium Persulfate
LiOCl = Lithium Hypochlorite
Oxone .TM. = Potassium Monopersulfate
The results of this experiment indicate that the oxidation
performance is greatly enhanced when the chlorine oxidizer and the oxygen
oxidizer are combined. In fact, the DPS used alone showed no color reduction but
in combination with the chlorine achieved a color reduction of 85%. OXONE alone
reduced the color only 37%. Chlorine alone showed a color reduction of 58%.
H.sub.2 O.sub.2 another popular oxidizer actually was antagonistic with
chlorine. This experiment points out that the DPS or Oxone in the combination
with chlorine is not antagonistic, but in fact it appears to enhance the
oxidation activity.
EXAMPLE 8
During the summer of 1993, a
consumer field test was conducted involving 48 swimming pools. As a control
group, 27 pools were operated by the consumer only on a traditional chlorine
type program utilizing only a sanitizer tablet in a chlorinator or floater for
18 weeks. The sanitizer tablets contained 92.5% trichloro-s-triazinetrione, 5%
sodium tetraborate (5 mol) and 2.5% unsubstituted glycoluril which added a very
low level of boron, typically less than 0.1 ppm boron for each pound of tablets
added to 10,000 gallons of pool water. The consumers provided their own shock
treatment and shocked the water at their discretion. The pools were monitored
for algae growth during the test period. During the 18 weeks, 81.5% of the pools
experienced algae growth. The results are summarized in Table 4.
TABLE 4
__________________________________________________________________________
WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK
No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
__________________________________________________________________________
1 XX XX XX XX
2
3
4 XX XX XX
5 XX
6 XX XX XX XX XX XX
7 XX XX XX
8 XX XX XX
9 XX XX XX
10 XX XX XX XX XX XX XX XX
11 XX XX XX XX XX XX
12
13 XX XX XX XX XX
14
15 XX
16 XX
17 XX
18 XX XX XX
19 XX XX XX
20 XX XX XX XX
21 XX XX XX XX XX XX XX XX XX
22
23 XX
24 XX XX XX XX XX XX XX XX XX XX
25 XX XX XX XX
26 XX XX XX XX XX XX XX XX
27 XX XX XX XX XX XX XX XX XX XX XX XX XX
__________________________________________________________________________
The XX denotes algae growth.
At the beginning of week 19, pool numbers 1-13 were given a
lithium hypochlorite treatment on a weekly basis at the rate of 1 pound for up
to 30,000 gallons of swimming pool water. Also at the beginning of week 19,
pools 14-27 were given the clarifier product that contained 60% sodium
dichloro-s-triazinetrione, 20% potassium monopersulfate, 10% sodium tetraborate
(5 mol) and 10% aluminum sulfate on a weekly basis at the rate of 1# for up to
30,000 gallons of swimming pool water. The testing was continued until week
number 36. The number of reported algae incidences were reduced, but still
constituted 52% of the pools dences to 52% of the pools. The results are
summarized in Table 5.
TABLE 5
__________________________________________________________________________
WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK
No.
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
__________________________________________________________________________
1
2
3
4 XX XX
5
6
7 XX
8 XX
9
10 XX
11 XX XX
12
13
14
15
16 XX
17
18 XX
19 XX XX
20 XX XX
21
22 XX
23 XX
24 XX XX XX XX
25
26 XX XX
27 XX
__________________________________________________________________________
The XX denotes algae growth.
By comparison, 16 pools were initially operated on a commercially
available boron system with boron levels maintained at less than 20 ppm. The
same chlorine sanitizer tablet used in the previous pools was also used to treat
these pools. The chlorine tablets were added to the pool through a chlorinator
or a floater. The consumers added their own shock treatment at their discretion.
During the 18 week test period, 62% of these pools experienced algae growth. The
test results are summarized in Table 6.
TABLE 6
__________________________________________________________________________
WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK
No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
__________________________________________________________________________
TM 79 81 81 82 84 85 86 86 87 86 87 87 87 87 87 86 86 85
25 XX
26 XX XX XX XX XX XX
27
28 XX
29 XX XX XX XX XX XX XX XX XX XX XX
30 XX XX XX
31
32
33
34 XX
35
36 XX
37 XX
38 XX XX XX XX XX XX
39
40 XX XX XX XX
__________________________________________________________________________
The XX denotes algae growth.
At the beginning of weeks 17-19, these 16 pools were converted to
the method of the present invention. The boron levels were increased to 26-30
ppm. Sanitizer tablets containing 92.5% trichloro-s-triazinetrione, 5% sodium
tetraborate 5 mol and 2.5% unsubstituted glycoluril were used to provide both
chlorine and boron on a continuous basis. The pools were treated with blended
clarifier component on a weekly basis at the rate of 1 pound for up to 30,000
gallons of pool water. During the 19 weeks, only three pools (19.0%) reported
algae growth. One pool reported algae growth during week #23 due to mechanical
problems resulting in an interruption of the chlorine feed system and subsequent
chlorine readings of 0 ppm. The test results are summarized in Table 7.
TABLE 7
__________________________________________________________________________
WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK WK
No.
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
__________________________________________________________________________
TM 79 81 81 82 84 85 86 86 87 86 87 87 87 87 87 86 86 85
25
26
27
28
29
30
31 XX
32 XX
33
34
35
36
37
38
39
40 XX
__________________________________________________________________________
The XX denotes algae growth.
The results of the 36 week field test clearly indicate that the
method of the present invention reduces the growth of algae.
EXAMPLE 9
The treatment of various recirculating systems is repeated in accordance
with the present invention and the process of Example 8 using the various
products referenced in Examples 1-3 and suitable results along the lines of
Example 8 are achieved.
EXAMPLE 10
The loss of the boron
component in a water system was demonstrated in a 22,000 gallon swimming pool
located in North Atlanta, Georgia. Sodium tetraborate was added to the pool to
achieve a concentration of 26 ppm of boron in the pool. The pool continued to
operate on a chlorine sanitizer with weekly shock treatments. Seven months
later, the pool water was rechecked. The boron level had dropped to 20 ppm,
pointing out that the boron is depleted with time and must be continually
replenished.
* * * * *
