U.S. patent application number 13/955699 was filed with the patent office on 2014-06-19 for localized disinfection system for large water bodies.
This patent application is currently assigned to Crystal Lagoons (CURACAO) B.V.. The applicant listed for this patent is Crystal Lagoons (CURACAO) B.V.. Invention is credited to Fernando Benjamin FISCHMANN.
Application Number | 20140166588 13/955699 |
Document ID | / |
Family ID | 47552994 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140166588 |
Kind Code |
A1 |
FISCHMANN; Fernando
Benjamin |
June 19, 2014 |
LOCALIZED DISINFECTION SYSTEM FOR LARGE WATER BODIES
Abstract
The present disclosure relates to a method for controlling the
microbiological properties of a portion of water within a large
body of water by treating such zone with chemical agents, according
to the temperature of the water, its salinity, its dilution power
and the diffusion of chemicals within the large water body.
Inventors: |
FISCHMANN; Fernando Benjamin;
(Vitacura, CL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Crystal Lagoons (CURACAO) B.V. |
Curacao |
|
NL |
|
|
Assignee: |
Crystal Lagoons (CURACAO)
B.V.
Curacao
NL
|
Family ID: |
47552994 |
Appl. No.: |
13/955699 |
Filed: |
July 31, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/EP2012/076170 |
Dec 19, 2012 |
|
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13955699 |
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Current U.S.
Class: |
210/742 |
Current CPC
Class: |
C02F 1/76 20130101; C02F
2103/007 20130101; C02F 1/50 20130101; C02F 2209/05 20130101; C02F
2209/02 20130101; C02F 1/78 20130101; C02F 2103/42 20130101; C02F
2209/005 20130101; C02F 1/008 20130101; C02F 1/766 20130101; C02F
2303/04 20130101; C02F 1/72 20130101; C02F 2209/04 20130101 |
Class at
Publication: |
210/742 |
International
Class: |
C02F 1/72 20060101
C02F001/72; C02F 1/76 20060101 C02F001/76; C02F 1/78 20060101
C02F001/78 |
Claims
1. A method for controlling microbiological properties of a portion
of water within a water body, comprising: a. identifying a portion
of water intended for recreational purposes within the water body,
the portion of water comprising one or more zones wherein: at least
one zone is designated a sanitary compliance zone, at least one
zone is designated a delimiting zone, and one zone is designated a
most unfavorable zone, the most unfavorable zone corresponding to
the zone that exhibits the lowest ORP value within the identified
portion of water; b. maintaining at least a minimum ORP level in
the portion of water for at least a minimum period of time, wherein
the minimum ORP level and the minimum period of time cannot be
lower than the values calculated by: i. determining salinity of the
water at the most unfavorable zone; and ii. determining the minimum
ORP value based on the salinity of the water where: for salinities
in the water between 0% and up to 1.5% the minimum ORP level is 550
mV; for salinities in the water higher than 1.5%, and up to 2.5%,
the minimum ORP level is calculated by the following equation:
[Minimum ORP,mV]=625-50*[Salinity of the Water,%(Weight
Percent)];and for salinities in the water higher than 2.5%, the
minimum ORP level is 500 mV; iii. determining the temperature of
the water in the most unfavorable zone; and iv. determining the
minimum period of time based on the water temperature, wherein: for
water temperatures from 5.degree. C. to 35.degree. C., the minimum
period of time is calculated by the following equation: [Minimum
period of time,min]=80-2*[Temperature of the water,.degree. C.];and
for water temperatures between 35.degree. C. and up to 45.degree.
C., the minimum period of time is calculated by the following
equation: [Minimum period of time,min]=5*[Temperature of the
water,.degree. C.]-165; c. dispensing an effective amount of
chemical agent into the identified portion of water in order to
maintain at least the minimum ORP level during at least the minimum
period of time at the most unfavorable zone, and d. repeating step
c as needed to prevent the ORP in the most unfavorable zone from
decreasing by more than 20% of the minimum ORP value.
2. The method of claim 1, further comprising repeating step b.
3. The method of claim 1, wherein the water body is a natural body
of water.
4. The method of claim 1, wherein the water body is selected from
the group consisting of a lake, sea, estuary, dam, lagoon, spa,
pool, pond and reservoir.
5. The method of claim 1, wherein the water is fresh water.
6. The method of claim 1, wherein the portion of water intended for
recreational purposes is defined by the delimiting zone.
7. The method of claim 1, wherein the portion of water intended for
recreational purposes is located on an edge of the water body.
8. The method of claim 1, wherein the portion of water intended for
recreational purposes is located on the interior of the water
body.
9. The method of claim 1, wherein the most unfavorable zone
presents the lowest ORP value within the portion of water intended
for recreational purposes after dispensing chemical agent into the
water.
10. The method of claim 1, wherein if the water body has a surface
area smaller than 5 hectares, the most unfavorable zone is the
central zone of the water body.
11. The method of claim 1, wherein the chemical agent is selected
from the group consisting of ozone; chlorine and chlorine
compounds; biguanide products; halogen-based compounds; bromine
based compounds, and mixtures thereof.
12. The method of claim 1, wherein the chemical agent is dispensed
by manual application or using a dispenser selected from the group
consisting of an injector, diffusor, sprinkler, weight dispenser,
piping, and combinations thereof.
13. The method of claim 1, wherein the ORP, the salinity, and the
temperature of the water are determined by empirical methods.
14. The method of claim 1, further comprising supplying water from
a different portion within the water body into the portion of water
intended for recreational purposes in order to provide a dilution
effect.
15. The method of claim 1, further comprising supplying water from
a different portion within the water body into the portion of water
intended for recreational purposes in order to provide a dilution
effect of bather's load of contaminants.
16. The method of claim 1, wherein the minimum ORP level is
maintained permanently in the sanitary compliance zone.
17. The method of claim 1, further comprising applying the method
to the portion of water when bathers are present in the
sanitary-compliant zone.
18. The method of claim 1, wherein the water body is an artificial
body of water.
19. The method of claim 1, wherein the water is brackish water,
salty water, or sea water.
Description
FIELD OF THE INVENTION
[0001] The present disclosure relates to a method for controlling
the microbiological properties of a portion of water within large
water bodies, by focusing on treating such portion of water, where
said portion of the large water body complies with specific
microbiological sanitary conditions. The present disclosure allows
people to use large water bodies for recreational purposes in a
safe manner, avoiding the treatment of the total water body. The
method also comprises dispensing chemicals governed by a parameter
determination method based on the ORP, the temperature, the
salinity, and optionally the diffusion of chemicals, and the
dilution power of the water as well. This results in using in
orders of magnitude less chemicals to treat water and low energy
consumption. Thus, the present disclosure can allow people to use
certain zones within large artificial or natural water bodies, such
as large lakes, lagoons, reservoirs, dams, spas, ponds, or the sea;
for recreational purposes in a safe manner, overcoming the
limitation or impossibility of treating the whole water body.
BACKGROUND
[0002] Several studies throughout the world show that the water
quality found in several large water bodies, such as lakes,
reservoirs, dams, and the sea, have bacteriological and physical
characteristics that do not comply with safety standards and or
water quality required for recreational purposes. Therefore, the
use of such large water bodies for recreational purposes can pose
health threats to the people, and adversely effect the surrounding
communities and geographies.
[0003] Water pollution can relate to the change in the chemical,
physical and biological characteristics of a water body due to
human activity. As the world's population has grown exponentially
over the years, it demands more living and recreational space,
therefore using natural or artificial water bodies for different
purposes. The increasing population is occupying the periphery of
large cities, increasing land demand and related utilities.
Furthermore, the number of industries has multiplied, which has
caused several environmental consequences that also affect the
quality of such large water bodies.
[0004] One contributor to poor water quality is water pollution.
Water can be contaminated by sewage disposal, industrial
contamination, overdevelopment on the edge of water bodies, runoff
from agriculture and urbanization, air pollution, etc. Also, higher
temperatures can adversely affect the microbiological and physical
properties of water and allow for a rapid proliferation of
microorganisms that may negatively affect the human health. These
examples can cause the water quality to drop below the standards
required for recreational water.
[0005] The effects of water pollution include the impact over the
health of living organisms within the water bodies, and eventually
the health of humans that can use such water for direct or indirect
purposes.
[0006] Also, the amount of nutrients entering large water bodies
has intensified greatly over the years, mainly due to increased
urbanization and agriculture, leading to an increased
microbiological growth or eutrophication of the water body. Under
eutrophic conditions, the amount of nutrients causes the metabolic
rate of aquatic plants to increase, thus increasing the biochemical
oxygen demand and reducing the water's dissolved oxygen levels.
Moreover, the temperature also affects the water's dissolved oxygen
level, as warm water has a reduced capability of holding dissolved
oxygen. Therefore, combining both oxygen reduction effects, such as
larger amount of nutrients and higher temperatures, results in a
weakening of the organisms as they become more susceptible to
diseases, parasites, and other pollutants. All of such problems
produce a negative influence on the water quality, causing the
proliferation of algae and other microorganisms, which later die
and create an unsafe recreational environment for the people. Also,
global warming will tend to increase this kind of problem
throughout the world.
[0007] Many studies and analysis have been performed on large water
bodies used for recreational purposes. Large water bodies are used
for a wide variety of recreational purposes that include bathing,
waterskiing, windsurfing, boating, and many other activities.
However, several water bodies used for such recreational purposes
do not comply with specific microbiological sanitary conditions
applied to the water body. For example, an EPA study was performed
on more than 1,000 lakes across the U.S. to analyze the potential
risks of using such lakes for direct-contact recreational purposes,
and it was found that more than 30% of all the lakes potentially
have wide ranging impacts on human health, and over 41% of lakes
pose a high or moderate exposure potential to algal toxins. Also,
it has been found that microbial counts and toxin concentrations
are greater in near shore residuals than in open water areas.
[0008] Many countries throughout the world have regulations for
using bodies of water for direct contact recreational purposes,
such as bathing, in safe and hygienic conditions, and there are
generally two types of regulations regarding recreational use of
such water bodies. The first type of regulation is directed to
swimming pools, and essentially requires maintaining a high
permanent chlorine buffer in order to maintain low microorganisms
levels and also to avoid the contamination of the water when new
bathers enter the swimming pool. The chlorine buffer neutralizes
contaminants and kills microorganisms brought to the swimming pool
water by bathers, amongst many other pollutants, thus maintaining a
high water quality suitable for recreational purposes. The second
type of regulation applies to natural or artificial large water
bodies, such as lakes, the sea, lagoons, reservoirs, or dams, among
other large water bodies, and it is referred to as the criteria for
bathing with full body contact for recreational waters. This
regulation is based on the diluting power of water. When the water
has acceptable microorganisms' levels, and new bathers enter into a
body of water, the contaminants are diluted in such way that the
contaminants do not attain a concentration in the body of water
that causes significant effects. Therefore, in large water bodies,
a disinfectant buffer is not needed due to the high diluting power
of the large water volume, and because of its natural capacity to
maintain sanitary conditions.
[0009] Direct-contact recreational water regulations, like the one
applied to lakes, the sea, lagoons or dams; require the water
quality to comply with several standards that allow the safe use of
such bodies. In order to evaluate the suitability of the large
water bodies for direct-contact recreational purposes, the most
important standards are the microbiological parameters of the
water. For example, the EPA (Environmental Protection Agency)
criteria for bathing with full body contact in recreational waters
points out that as for freshwater, E. Coli must not exceed 126 CFU
per 100 ml of water, and that Enterococci must not exceed 33 CFU
per 100 ml of water. For seawater, the EPA rules that the
Enterococci must not exceed 35 CFU per 100 ml of water. As another
example, in Chile, the Norm NCh1333 for direct-contact recreational
waters states that the water must not contain over 1000 CFU of
fecal coliforms per 100 ml of water (including E. Coli, among
others). Therefore, strict norms apply when such large water bodies
are used for direct-contact recreational purposes.
[0010] It is therefore a significant challenge to obtain such
required specific microbiological conditions in large water bodies
which are currently unsuitable for recreational purposes, as the
application of large quantities of chemical agents and
disinfectants throughout the complete large water body to comply
with specific microbiological sanitary conditions is unfeasible
technically, economically and environmentally. Thus, the treatment
of the complete water body to comply with specific microbiological
sanitary conditions applied to the water body is impossible most of
the times.
[0011] Also, although some water bodies can comply with
microbiological regulations for direct contact recreational waters,
or more stringent regulations applied to the water body, there are
pathogenic organisms such as protozoa, and specifically amoebas,
among others, that can be present in such water bodies especially
in low salinity waters or high temperature waters. Therefore, there
are no guarantees that maintaining bacteriological regulations for
direct contact recreational waters, can allow safe bathing
conditions permanently.
[0012] Currently, water treatment technologies applied to swimming
pools require the addition of chemical agents to maintain a
permanent chlorine buffer of at least 1.5 ppm or to maintain a
permanent ORP of at least 750 mV. Currently, there are no known
practical methods to treat large water bodies contaminated by
microorganisms, such as lakes, the sea, lagoons, reservoirs, or
dams because current methods are technically, economically, and
environmentally unviable for large water bodies. The ORP has
increasingly become a primary approach to standardizing water
disinfection parameters. The metabolism of microorganisms and
consequently their ability to survive and propagate are influenced
by the ORP (Oxidation Reduction Potential) of the medium in which
they live. From a bacteriological point of view, an oxidizing
compound removes and accepts the electrons from the cell membrane
(reduction-oxidation reaction), causing the cell to become unstable
and leading to a rapid death.
[0013] The Oxidation Reduction Potential (ORP), i.e., the tendency
of a chemical compound to acquire electrons from another species,
may be controlled by the addition of different disinfectants that
allow treating the water and the killing of dangerous
microorganisms that can create an unsafe environment for
recreational purposes. Also, the temperature of the water carries
an important role on its bacteriological characteristics and
microorganism proliferation, where microorganism proliferation
tends to increase at higher temperatures. Furthermore, the salinity
of the water also carries an important role on its bacteriological
properties, as some microorganisms require specific salinity levels
in order to be able to proliferate, and do not withstand mediums
with different salinities. For example, some pathogenic protozoa
only grow in water with salinities lower than 2% in weight,
therefore for higher salinities such microorganisms will not grow
nor proliferate.
[0014] Swimming pool water treatment technologies require the
addition of large quantities of chemical agents, in order to
maintain suitable disinfection parameters. For large water bodies,
the application of current swimming pool disinfecting technologies
is unviable technically and economically, because of the large
amount of chemicals that would be needed, and that would cause
important environmental damage.
[0015] Currently, there are no known practical methods to disinfect
large water bodies, and treating such large water bodies, such as
lakes, the sea, lagoons, reservoirs, or dams. If traditional
disinfection technologies are utilized, a proper treatment and
disinfection would be technically, economically, and
environmentally unviable. Therefore, it is desired to provide a
method for treating large water bodies, and preferably defined
portions thereof in order to provide a zone that complies with
specific microbiological sanitary conditions, and using them for
recreational purposes in a safe way.
[0016] Therefore, there is an unresolved problem regarding
recreational uses on natural or artificial large water bodies such
as lakes, lagoons, the sea, or dams, with poor water quality. The
microbiological characteristics of such large water bodies must
comply with direct-contact water regulations or more stringent
regulations that apply to the particular water body, in order to
allow the safe practice of recreational purposes within the water
bodies, and also to avoid any health threats to the community or
nearby terrains, which currently does not occur in many of the
large water bodies throughout the world.
STATE OF THE ART
[0017] U.S. Pat. No. 6,231,268 discloses a method and apparatus for
treatment of large water bodies by directed circulation, where the
device and method from U.S. Pat. No. 6,231,268 is directed to
maintain water circulation within large water bodies to avoid lack
of oxygen, stagnant areas, freezing, and other non-uniform
conditions. U.S. Pat. No. 6,231,268 does not mention nor disclose a
method for treating a portion of water within a large water body in
order to comply with specific micro-bacteriological sanitary
conditions, but only discloses a method for maintaining circulation
within the large water body. The method from U.S. Pat. No.
6,231,268 does not apply chemicals through diffusor means in order
to create a sanitary-compliant zone, but maintains a circulation
within the water body, which would disperse the chemicals
throughout the water body, not allowing the creation of a
sanitary-compliant zone.
[0018] U.S. Pat. No. 6,317,901 discloses a fresh or saltwater pool,
where the pool is created over a natural or artificial water body
that allows using the water from such body to avoid the
contamination due to soil or other sediments contained in the large
water body by means of physical barriers that allow the passing
through of water and not contaminants, which requires the
installation of physical containing means within the large water
body.
[0019] Patent CN 102092824 discloses a water circulation system for
ponds, lakes, municipal tanks, and other water bodies, where the
water circulation system allows creating a flow from the bottom
water to the surface water, avoiding the eutrophication of the
water body. Patent CN102092824 does not mention nor disclose a
method for controlling the microbiological properties of a portion
of water within the large water bodies, in order to create
sanitary-compliant zones that allow recreational purposes.
SUMMARY
[0020] Surprisingly, the present disclosure controls the
microbiological properties in large water bodies by treating a
portion of the large water body, where the portion of the large
water body complies with specific microbiological sanitary
conditions without having to treat the whole water body, providing
thus a sanitary-compliant zone, which is located in order to cover
the area being used for recreational purposes, allowing the water
quality to comply with specific microbiological sanitary
conditions.
[0021] The method allows treating a small part of the total water
volume. Therefore, the method requires only a small amount of
chemicals as well as low consumption of energy due to the use of
dispenser means that allow creating safe sanitary-compliant zones
without needing to treat the entire water body. Thus, the present
disclosure can allow people to use certain zones within large water
bodies for recreational purposes in a safe manner, overcoming the
limitation or impossibility of treating the whole water body, but
only treating the zone that will be used for such purposes, and
also allows using countless lakes, seashores, lagoons, and many
water bodies that are unusable today due to safety or sanitary
problems, generating unprecedented recreational and touristic
opportunities that can change the lifestyle of people around the
world.
[0022] The method can be performed on natural or artificial large
water bodies, such as lakes, the sea, estuaries, reservoirs, dams,
and lagoons. Also, the water contained in such large water bodies
can be fresh water, brackish water, salty water, or sea water.
[0023] Accordingly, in some embodiments, the present disclosure
relates to a method for controlling the microbiological properties
of water by identifying a portion of the water. The method further
includes maintaining at least a minimum ORP in the water for at
least a minimum period of time depending on the salinity and the
temperature of the water, and dispensing chemical agents in order
to maintain at least the minimum ORP at least during the minimum
period of time. The dispensation of chemical agents may preferably
be performed through dispenser means that allow creating safe
sanitary-compliant zones. The dispensation of chemical agents may
additionally be based on the diffusion of chemicals in the water
and the dilution power in the water.
[0024] In one embodiment, the method of the present disclosure
includes: [0025] a. identifying a portion of water intended for
recreational purposes within the large water body and defining
dispenser means; [0026] b. maintaining at least a minimum ORP level
in such portion of water for at least a minimum period of time,
wherein the minimum ORP level and the minimum period of time cannot
be lower than the values calculated by: [0027] i. determining the
most unfavorable zone within the portion of water; [0028] ii.
determining the salinity of the water at the most unfavorable zone;
[0029] iii. determining the minimum ORP value based on the salinity
of the water where: [0030] for salinities in the water between 0%
and up to 1.5% the minimum ORP level is 550 mV; [0031] for
salinities in the water higher than 1.5%, and up to 2.5%, the
minimum ORP level is calculated by the following equation:
[0031] [Minimum ORP,mV]=625-50*[Salinity of the Water,%(Weight
Percent)];and [0032] for salinities in the water higher than 2.5%,
the minimum ORP level is 500 mV; and [0033] iv. determining the
temperature of the water in the most unfavorable zone; and [0034]
v. determining the minimum period of time based on the water
temperature, where: [0035] for water temperatures from 5.degree. C.
to 35.degree. C., the minimum period of time is calculated by the
following equation:
[0035] [Minimum period of time,min]=80-2*[Temperature of the
water,.degree. C.];and [0036] for water temperatures between
35.degree. C. and up to 45.degree. C., the minimum period of time
is calculated by the following equation:
[0036] [Minimum period of time,min]=5*[Temperature of the
water,.degree. C.]-165; [0037] c. dispensing an effective amount of
chemical agent in order to maintain at least the minimum ORP level
during at least the minimum period of time at the most unfavorable
zone, and [0038] d. Repeating step c in order to avoid the ORP in
the most unfavorable zone to decrease by more than 20% of the
minimum ORP value.
BRIEF DESCRIPTION OF THE FIGURES
[0039] The accompanying drawings, which are incorporated herein and
constitute a part of this disclosure, illustrate various
embodiments of the present invention. In the drawings:
[0040] FIG. 1 shows a top view of a small section of the large
water body (2), and the sanitary-compliant zone (1).
[0041] FIG. 2 shows a top view of an even smaller section of the
large water body, and in particular, the sanitary compliant zone
(1), the dispenser means (3) and the delimiting zone (4).
[0042] FIG. 3 shows a chart representing the variation of the
minimum ORP value of the water according to the water's salinity,
as a result from an embodiment of the method of the present
invention.
[0043] FIG. 4 shows a chart representing the variation of the
minimum period of time that the minimum ORP value is maintained
according to the water's temperature, as a result from an
embodiment of the method of the present invention.
[0044] In accordance with common practice, the various described
features are not drawn to scale but are drawn to emphasize specific
features. Reference characters denote like features throughout the
Figures.
DETAILED DESCRIPTION
[0045] The following detailed description refers to the
accompanying drawings. While some embodiments may be described,
modifications, adaptions, and other implementations are possible.
For example, substitutions, additions, or modifications may be made
to the elements illustrated in the drawings, and the methods
described herein may be modified by substituting, reordering, or
adding steps to the disclosed methods. Accordingly, the following
detailed description does not limit the scope of the disclosure.
While systems and methods are described in terms of "comprising"
various apparatus or steps, the systems and methods can also
"consist essentially of" or "consist of" the various apparatus or
steps, unless stated otherwise.
DEFINITIONS
[0046] In the light of the present disclosure, the following terms
or phrases should be understood with the meanings described
below:
[0047] As used herein, the general types of water and their
respective Total Dissolved Solids (TDS) concentration (in mg/L)
are: Fresh, with TDS.ltoreq.1,500; Brackish, with
1,500<TDS.ltoreq.10,000; Salty, with
10,000<TDS.ltoreq.30,000; and Seawater, with TDS>30,000. The
TDS can be measured for example using a conductivity meter or by
applying gravimetric methods evaporating the solvent and weighing
the mass of residues left.
[0048] As used herein, "sanitary-compliant zone" refers to the
portion of water, within the large water body, which is established
for recreational purposes, and required to comply with specific
microbiological sanitary conditions, when used for recreational
purposes or when it is needed. It must be noted that the
sanitary-compliant zone may not be permanently the same physical
zone, but it may change according to the requirements of the people
for recreational purposes.
[0049] As used herein, "specific microbiological sanitary
conditions" refers to the microbiological properties/conditions
that need to be achieved within the sanitary-compliant zone in
order to allow recreational purposes. Such conditions can be
determined by specific local, state, federal regulations for
reducing certain specific organisms, or different predetermined
specific conditions.
[0050] As used herein, "minimum ORP level" refers to the minimum
ORP that can be allowed in the most unfavorable zone, in order to
properly control microbiological properties in such zone.
[0051] As used herein, "minimum period of time" refers to the
minimum amount of time that the minimum ORP level of the water at
the most unfavorable zone must be maintained, in order to allow the
required sanitary conditions.
[0052] As used herein, the "delimiting zone" corresponds to a
virtual zone that delimits the sanitary-compliant zone, and does
not require a physical barrier.
[0053] As used herein, the "most unfavorable zone" corresponds to
the zone that shows the lowest ORP values within the identified
portion of water, especially after applying a determined amount of
chemical agents. The most unfavorable zone is often, but not
necessarily always, found on the delimiting zone of the identified
portion of water and the farthest from the chemical dispenser.
[0054] As used herein, the "dispenser means" refer to any means for
applying one or more chemical agents to the water, and may be
selected from the group consisting of an injector, diffusor,
sprinkler, weight dispenser, piping, manual application, and
combinations thereof; pipes; valves; and connecting elements that
allow the proper application of chemicals into the established
portion of water to be treated.
[0055] As used herein, the "chemical agents" that are applied to
the water body refer to any chemical agent that allows achieving
the desired ORP level in the water. The "effective amount of
chemical agents" corresponds to the minimum amount of chemicals
that can be applied to the water in order to maintain at least the
minimum ORP level during at least the minimum period of time at the
most unfavorable zone.
Methods of the Present Disclosure
[0056] The present disclosure allows controlling the
microbiological properties in large water bodies by treating a
portion of the large water body, so that said portion of the large
water body complies with specific microbiological sanitary
conditions when required, thus overcoming the limitation or
impossibility of treating the whole water body. Sanitary-compliant
zones are created, which are strategically located in order to
widely cover the area being used for recreational purposes.
[0057] The disclosed method requires a smaller amount of chemicals
and reduced energy consumption because it does not require treating
the complete water body with this specific method (the water body
may be subject to other treatments different to the disclosed
method). Thus, the present disclosure allows people to use certain
zones within large water bodies for recreational purposes in a safe
manner, and overcomes the economic, technical and environmental
limitation or impossibility of treating the whole water body, and
also allows using countless lakes, seashores, lagoons, and many
water bodies that are unusable today due to safety or sanitary
problems, generating unprecedented recreational and touristic
opportunities that can change the lifestyle of people around the
world.
[0058] The disclosed methods can be performed on natural or
artificial large water bodies, such as lakes, the sea, estuaries,
reservoirs, dams, and lagoons. The disclosed methods can be used
with different water types including fresh, brackish, salty, and
sea water. In one embodiment, the method for controlling the
microbiological properties of a portion of water within large water
bodies includes: [0059] a. identifying a portion of water intended
for recreational purposes within the large water body and defining
dispenser means; [0060] b. maintaining at least a minimum ORP level
in such portion of water for at least a minimum period of time,
wherein the minimum ORP level and the minimum period of time cannot
be lower than the values calculated by: [0061] i. determining the
most unfavorable zone within the portion of water; [0062] ii.
determining the salinity of the water at the most unfavorable zone;
[0063] iii. determining the minimum ORP value based on the salinity
of the water where: [0064] for salinities in the water between 0%
and up to 1.5% the minimum ORP level is 550 mV; [0065] for
salinities in the water higher than 1.5%, and up to 2.5%, the
minimum ORP level is calculated by the following equation:
[0065] [Minimum ORP,mV]=625-50*[Salinity of the Water,%(Weight
Percent)];and [0066] for salinities in the water higher than 2.5%,
the minimum ORP level is 500 mV; and [0067] iv. determining the
temperature of the water in the most unfavorable zone; and [0068]
v. determining the minimum period of time based on the water
temperature, where [0069] for water temperatures from 5.degree. C.
to 35.degree. C., the minimum period of time is calculated by the
following equation:
[0069] [Minimum period of time,min]=80-2*[Temperature of the
water,.degree. C.];and [0070] for water temperatures between
35.degree. C. and up to 45.degree. C., the minimum period of time
is calculated by the following equation:
[0070] [Minimum period of time,min]=5*[Temperature of the
water,.degree. C.]-165; [0071] c. dispensing an effective amount of
chemical agent in order to maintain at least the minimum ORP level
during at least the minimum period of time at the most unfavorable
zone, and [0072] d. Repeating step c in order to avoid the ORP in
the most unfavorable zone to decrease by more than 20% of the
minimum ORP value.
[0073] The location of the most unfavorable zone, the water
salinity and temperature of the water may vary independently from
each other as a result of external conditions. Thus, the method of
the disclosure may optionally comprise a further step e., where
steps b., c. and d. are carried out once again or repeatedly.
[0074] To determine the zone that must comply with specific
microbiological sanitary conditions applied to the water body, a
strategic analysis could be done in order to provide an accessible
zone that can allow safe recreational purposes.
[0075] The dispensation of the chemical agent, preferably through
dispenser means, is controlled by a parameter determination method
that combines the effects of the ORP of the water, its salinity and
its temperature. Optionally, the diffusion of chemicals, and the
dilution power of the water may be further considered in the
parameter determination method. Due to the combined effect of the
disinfection properties of the water (ORP), the resistance of
certain microorganisms depending on the salinity of the water, the
temperature, and optionally the dilution power of the water, the
present disclosure allows to use much less chemical agents than
required by swimming pools in order to comply with specific
microbiological sanitary conditions applied to the water body,
which was a result of extensive research. In the state of the art,
there are currently two ways for maintaining a water quality
compliant with specific microbiological sanitary conditions applied
to the water body, which relate to the addition of large quantities
of disinfection agents, or instead relying on the dilution power of
the water. The present disclosure combines both effects in order to
make the most of their synergies and thus provide an effective and
sustainable method for zones that comply with specific
microbiological sanitary conditions.
Identifying the Portion of Water to be Treated
[0076] The location of the portion of water to be treated, which
after the process of the invention will be designated as the
sanitary-compliant zone, can be determined by strategically
identifying the portion of the water most likely to be used for
recreational purposes. This location can be determined by examining
where users are likely to enter the water, the depth of the water,
the purpose of the water (e.g., bathing, swimming, skiing, boating,
fishing, etc.), the temperature of the water, and the like. For
example, if a body of water is located next to a hotel, the
sanitary-complaint zone will likely be the portion of the water
next to the hotel where users are most likely to enter the water.
This is shown in FIGS. 1 and 2, which show the sanitary-compliant
zone 1 located on an edge of the large water body 2. In other
cases, the sanitary-complaint zone can be in the center of a body
of water and surrounded by the large water body. In some cases, the
sanitary-compliant zone may correspond to a recreational area that
is visually roped off or otherwise physically separated from the
rest of the water (e.g., fenced off, partitioned off with a
wall).
[0077] Referencing FIGS. 1 and 2, the zone 1 complies with
predetermined sanitary conditions. As discussed, the sanitary
conditions may be determined by local, state, or federal
regulations or different predetermined specific conditions.
Exemplary regulations for recreational water state that E. Coli
must not exceed 126 CFU per 100 ml of water, and that Enterococci
must not exceed 33 CFU per 100 ml of water. For seawater, the EPA
regulations state that Enterococci must not exceed 35 CFU per 100
ml of water. In Chile, the Norm NCh1333 for direct-contact
recreational waters state that the water must not contain over 1000
CFU of fecal coliforms per 100 ml of water (including E. Coli,
among others). Alternatively, the sanitary conditions or microbial
properties may be determined by referencing the concentration of
certain microorganisms. In any case, the sanitary-compliant zone 1
meets the sanitary conditions, while the rest of the water volume 2
may not comply with specific sanitary conditions applied to the
sanitary-compliant zone.
[0078] Additionally, the sanitary-complaint zone may include one or
more dispensers 3 for dispensing chemical agents where the rest of
the water body 2 may not include the dispensers 3.
[0079] The sanitary-compliant zone is virtually bounded by the
delimiting zone 4. The delimiting zone 4 is a virtual barrier that
may comprise but does not require a physical barrier.
[0080] The present disclosure does not require circulating water
throughout the various zones--sanitary-compliant zone, delimiting
zone, and most unfavorable zone. In fact, in some embodiments, the
water is specifically not circulated. For the large water bodies
described herein, it may be economically, technically and
environmentally unviable to circulate the water within the large
water body. The present disclosure treats the water in the
identified portion of water with chemical agents to allow such zone
to comply with specific microbiological sanitary conditions for
such area. While dispersion of the chemical agents from the
sanitary-compliant zone to other zones may naturally occur within
the water body, it is not required by the present disclosure.
Therefore, in some embodiments, maintaining water circulation
throughout the complete water body would be counterproductive with
the disclosed methods.
[0081] After the portion within the large water body to be used for
recreational purposes has been identified or established, the
dispenser means, which are controlled by a parameter determination
method based on the ORP of the water, its salinity, its
temperature, and optionally the diffusion of chemicals as well as
the dilution power of the water, may be defined.
[0082] The dispenser means 3 may be selected from one or more than
one diffusors, injectors, sprinklers, dispensers by weight, piping,
manual application, or combinations thereof. The dispenser means
are adapted to discharge an effective amount of chemicals into the
water body; and also may comprise the required equipment to allow
its proper operation, such as pipes, valves, and connecting
elements.
[0083] In order to create the zones that comply with specific
microbiological sanitary conditions applied to the water body,
chemical concentrations must be applied according to a parameter
determination method based on the ORP, the salinity, the
temperature, and optionally the diffusion of chemicals and the
dilution power of the water as well. The chemicals may preferably
be applied by dispenser means 3 that are defined in order to cover
the water volume used for recreational purposes.
[0084] It must be noted that the present disclosure does not
require a physical barrier in order to contain the portion of water
to be treated, but instead chemical concentrations are applied to
the portion of water in order to comply with specific
microbiological sanitary conditions applied to such area the water
body.
[0085] The dispenser means are controlled by a parameter
determination method based on the ORP of the water, its salinity,
its temperature, as well as optionally the diffusion of chemicals
and the dilution power of the water. The dispenser means applies
chemicals into the water in order to allow proper diffusion
conditions within the water body and comply with specific
microbiological sanitary conditions applied to the water body. The
dispenser means may be strategically configured, and positioned
relative to and/or with the portion of water intended for
recreational purposes in order to provide the required chemical
concentrations at the sanitary-compliant zone.
Number and Location of Dispensers
[0086] In one embodiment, the dispensers are located or used in
order to cover the water volume in the sanitary-compliant zone. The
number and location of the dispensers for dispensing the chemical
agents may be determined by the specific conditions of each portion
of water that will be treated. The total amount of dispensers can
be calculated according to the chemical flow that is to be applied
to the water body, and such chemical flow may be divided into a
series of dispensers in order to allow its homogeneous application
throughout the portion of water to be treated.
[0087] For example, for treating the same portion of the water
body, there is an effective amount of chemicals to be added. The
effective amount may preferably be added through several small-flow
dispensers, or just a few large-flow dispensers, depending on
several variables such as for example wind, water currents, and
many other variables that may influence the homogeneity of the
chemical application within the water body.
[0088] The dispensers can generally be located on the perimeter of
the portion of water that will be treated, in order to fully cover
such portion, but they can also have other configurations regarding
the specific requirements of the portion of water in order to
maintain the homogeneity of the chemical application and allow the
chemical diffusion throughout the portion of water.
Types of Dispensers
[0089] The types of dispensers that can be used in the disclosed
method can be variable according to the requirements for chemical
application, and may comprise diluters, injectors, dispensers by
weight, manual application, manifolds, piping, sprinklers, nozzles,
or combinations thereof. The dispensers used in the disclaimed
method are preferably nozzles, and more preferably injectors.
Discharging an Effective Amount of Chemical Agents
[0090] Chemical agents are used to create the sanitary-compliant
zone by reducing the number of microorganisms in the
sanitary-compliant zone to below a predetermined amount. The
concentration of the chemical agents in the sanitary-compliant zone
can be controlled by the amount of chemical agent dispensed from a
single dispenser as well as the total number of dispensers. For
example, it may be desirable to dispense less chemical agent from a
single dispenser, but to increase the number of dispensers in the
sanitary-compliant zone. An example of the use of multiple
dispensers is shown in FIG. 2 where a plurality of dispensers 3 are
located around the periphery of the sanitary-compliant zone. The
number and location of the dispensers for dispensing the chemical
agents are determined in order to cover the water volume in the
sanitary-compliant zone, in one embodiment.
[0091] The dispenser 3 may be a diffusor, injector, sprinkler,
dispenser by weight, piping, manual application, or combinations
thereof. The dispenser discharges an effective amount chemical
agent into the water body. The dispenser also includes any required
equipment to allow the dispenser to operate, such as pipes, valves,
and connecting elements.
[0092] Exemplary chemical agents include antimicrobial agents such
as ozone, chlorine, and chlorine compounds, biguanide products,
halogen-based compounds, bromine-based compounds, and combinations
thereof.
[0093] The total amount of chemicals added to achieve a certain ORP
level in the water depends on several variables, such as for
example the pH, meteorological conditions, rain, levels of use,
organic load, salinity, temperature, alkalinity, disinfectant
concentration, and/or concentration of metals and contaminants,
among many other factors. The ORP is a measure of the tendency for
oxidizing or reducing certain species found within the water body,
and therefore does not represent the amount of chemical agents
contained in the water. ORP measurements present the advantage of
measuring not only the concentration of the sanitizer, but also its
activity in the water and its effectiveness on killing germs and
bacteria.
[0094] There are no known equations that can relate the temperature
of the water, its salinity, and the dilution power for maintaining
a minimum ORP in a certain portion of the water for a minimum
period of time according to the diffusion of chemicals in the
water, due to the complexity of the variables and its mutual
influences, and therefore extensive research was performed. An
intricate model must be built in order to estimate the amounts of
chemicals to be applied in the water body. Since the portion of
water is contained within a large water body, when the chemicals
are applied, they will diffuse throughout the portion of water
creating a chemical gradient that will be higher near the
dispensers and lower near the most unfavorable zone.
[0095] It must be noted that when the application of chemicals
begins, at first there will be no significant change in the ORP of
the water since the chemicals will be oxidizing several other
compounds in the water. However, at some point the application will
allow generating a residual concentration of chemicals that will
help raise the ORP up to the desired levels and thus provide the
desired disinfection capacity. Therefore, it must be noted that the
chemical consumption is divided into two groups: [0096] The amount
of chemicals applied that help oxidizing diverse compounds that do
not affect ORP significantly. Such chemical consumption must be
determined on-site, as it completely depends on the water quality
of the raw water. Also, such concentration could be determined by
an intricate model based on the water quality physicochemical
parameters. [0097] The amount of chemicals applied that generate a
residual concentration in the water and thus increase the ORP in
the water. Such chemical concentration can be estimated on site or
according to diverse methods depending on water quality and
physicochemical conditions or parameters.
[0098] Notwithstanding the foregoing and without limiting the
invention, the oxidant application ranges for different oxidants
vary according to the properties of the water. Usually utilized
ranges of some oxidizing agents are the following:
TABLE-US-00001 Oxidant Range of Application (Residual
Concentration) Chlorine 0.01-5 ppm Sodium Hipochlorite 0.01-2 ppm
Bromines 0.01-2.3 ppm Ozone 0.01-0.75 ppm
[0099] The applicant will provide some embodiments to estimate the
amount of residual chemicals in the water: [0100] a. One could
estimate the minimum amount of oxidants that must be applied in the
water in order to obtain a certain ORP in the entire portion of
water to be treated, assuming the portion of water behaves as a
closed body. For example, the minimum amount of chemicals could be
estimated in order to achieve a certain ORP in the total volume of
the portion of water. For example, if the portion of water has a
volume of 1,000 m.sup.3, and the portion of water is considered a
closed water body, it can be estimated that for achieving an ORP of
550 mV in the water, a residual concentration of 0.07 ppm of sodium
hypochlorite must be maintained. In order to obtain the residual
concentration of 0.07 ppm, a first dosage of 1.2 ppm of sodium
hypochlorite was added in order to meet the chlorine demand of the
water and did not generate any residual concentration. Afterwards,
a dose of 0.07 ppm was added to obtain the required residual
concentration and obtain the desired ORP level of 550 mV.
Therefore, the amount of sodium hypochlorite added to the water can
be calculated according to its concentration in the water body as
follows: [0101] First dose:
[0101] 1.2 ppm = 1.2 ppm sodium hypochlorite liter of water .times.
1 , 000 m 3 .times. 1 , 000 liters 1 m 3 ##EQU00001## Total Sodium
Hypochlorite = 1 , 200 kg ##EQU00001.2## [0102] Residual
concentration:
[0102] 0.07 ppm = 0.07 ppm sodium hypochlorite liter of water
.times. 1 , 000 m 3 .times. 1 , 000 liters 1 m 3 ##EQU00002## Total
Sodium Hypochlorite = 70 kg ##EQU00002.2## [0103] Therefore, a
total amount of 1270 kg of sodium hypochlorite should be added to
obtain a homogeneous residual concentration of sodium hypochlorite
in the water of 0.07 ppm, and thus obtain an ORP of 550 mV in such
zone. Since in reality the portion of water is found within a large
water body, the concentration will not be homogeneous, and then the
previously calculated dose can be considered as a minimum for
obtaining such ORP due to the diffusion of chemicals produced by
currents. [0104] b. One could also use the free chlorine method,
which allows calculating the ORP of the water based on the pH and
the free chlorine concentration in the water. When the pH is
maintained at a constant value, there is a linear relationship
between ORP and free chlorine. Thus the amount of chemicals
required to achieve a certain amount of free chlorine can be
calculated subject to the ORP level as follows:
TABLE-US-00002 [0104] ORP pH Residual Chlorine Concentration 600 mV
7.0 0.06 ppm 8.0 0.20 ppm 9.0 1.60 ppm 700 mV 7.0 0.30 ppm 8.0 1.00
ppm 9.0 2.70 ppm
[0105] c. Addition of chemicals with periodic monitoring in order
to stop the addition when a certain ORP is reached is a further
option. This method is a trial and error method, which allows
adding chemicals by periodically monitoring the ORP, and when the
desired ORP is reached, the chemical addition must be stopped.
[0106] d. Another method used for determining the amount of
chemicals consists of taking a small water sample and perform a
small-scale test to determine the amount of chemicals that must be
applied to achieve a certain ORP level. This method is commonly
used and allows estimating the amount of chemicals, although it
does not consider diffusion or other variables. Therefore, the
results from this method are to be considered as a minimum amount
of chemicals required.
[0107] In some embodiments, it is desirable to apply additional
chemical agents before the ORP level in the most unfavorable zone
decreases by about 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 50%, 75%, or
100%.
[0108] In certain embodiments of the invention, where there is an
intensive use of the sanitary-compliant zone due to large amounts
of people, or if there are many currents that affect the
disinfection characteristics of the sanitary-compliant zone, or due
to safety or other reasons, the ORP may be maintained permanently
within the sanitary compliant zone for certain periods of time.
[0109] Also, in certain embodiments of the invention, the water
treatment is only utilized when bathers are present in the
sanitary-compliant zone, and therefore the treatment may not
operate all day nor permanently. For example, the water treatment
may operate only during the day, and it can be stopped during the
night, when there are no bathers in the sanitary-compliant zone.
Therefore, the water treatment method is applied when the
sanitary-compliant is effectively used for recreational
purposes.
[0110] In some embodiments, it may be desirable to improve the
water quality in the sanitary-compliant zone by supplying fresh
water or water from different portion within the large water body.
This may be beneficial, for example, to dilute the effect of
contaminants from users but may produce an unwanted diffusion
effect on the chemicals.
[0111] The minimum effective amount of disinfectant composition may
be calculated by the following equations: (Boyce & Hamblin,
1975) (Boyce & Hamblin, 1975)
C .infin. ( x , y ) = Q i C i 2 .pi. Z D exp ( U X 2 D ) K 0 ( a r
) ##EQU00003## a = [ .gamma. D + ( U 2 D ) 2 ] 1 / 2 ##EQU00003.2##
r = ( x 2 + y 2 ) 1 2 ##EQU00003.3##
[0112] Where the above equation is the solution for a point source
discharging continuously at a constant volumetric rate
Q i [ m 3 s ] ##EQU00004##
and at a concentration C.sub.i[.mu.M] at the source in a fluid of
depth Z [m], with x [m] and y [m] being the horizontal and vertical
distances respectively.
D [ cm 2 s ] ##EQU00005##
is the diffusion coefficient of the specific chemical in the water,
and K.sub.0 is the modified Bessel function of the second kind. U
[cm/s] is the uniform current of the water body through the x axis,
and .gamma.[-] is the decay process of the chemical in a time
scale.
Most Unfavorable Zone
[0113] In order to comply with specific microbiological sanitary
conditions applied to the water body, the most unfavorable zone of
the established portion of water is to be determined. The most
unfavorable zone corresponds to the one having the lowest ORP
values, especially after applying a predetermined amount of
chemicals through dispenser means in the established portion of
water, and it may be found on the delimiting zone or the furthest
from the dispenser means. The predetermined amount of chemicals can
be determined on-site and its only purpose is to determine the zone
with lowest ORP values within the portion of water to be
treated.
[0114] If the water body has a surface area smaller than 5
hectares, the most unfavorable zone is usually the central zone of
the water body.
[0115] A parameter determination method is defined to take in
account the different operation conditions of the system. It should
be noted that it is unviable to perform constant measures on the
water body, thus the present disclosure allows providing a water
quality that complies with specific microbiological sanitary
conditions without requiring constant measures.
[0116] The parameter determination method is based on the water's
ORP, its salinity, its temperature, and optionally the diffusion of
chemicals and its dilution power within the identified portion of
water. The ORP, salinity, and temperature of the water can be
determined by empirical methods, such as visual inspection, methods
based on experience, and analytical methods. The present disclosure
has related these variables and has solved a very complex
interaction regarding water quality, after very extensive
research.
[0117] The salinity can be determined by empirical or analytical
methods such as visual tests; salinometers that are based on the
conductivity of electricity in the water; hydrometers that are
based on the specific gravity of the water; or refractometers that
are based on the index of refraction of the water; or may be
publically known or can be information from other sources, among
others.
[0118] The temperature of the water can be determined by empirical
or analytical methods such as visual tests; thermometers;
thermocouples; resistance temperature detectors; pyrometers; or
infrared devices; or may be publically known or can be information
from other sources, among others.
[0119] The ORP of the water can be determined by empirical or
analytical methods, such as using ORP meters that have electrodes
in order to measure the voltage across a circuit within the
water.
[0120] It must be noted that the ORP of the water, its temperature,
its salinity, and the dilution power may be previously known or
empirically determined, therefore the method from the present
disclosure can be applied into the predefined portion of water in
knowledge of these variables.
[0121] The parameter determination method comprises maintaining at
least a minimum ORP level in the most unfavorable zone for at least
a minimum period of time in order to ensure the required sanitary
conditions throughout the entire established portion of water
within the large water body.
[0122] The minimum ORP level may depend on the salinity of the
water, as certain types of microorganisms, such as some pathogenic
protozoa, can only grow and live inside water bodies with maximum
salinities of 2% in weight. Therefore, the minimum ORP level may
depend on the salinity properties of the water, as for certain
salinity concentrations the water will not serve as a media for
some microorganisms to grow and thus pose health threats and
un-hygienic conditions.
[0123] On the other hand, the minimum period of time may also
depend on the temperature of the water. The water's temperature is
a very important factor for the proliferation of several
microorganisms. For low water temperatures, the microorganisms will
not proliferate as rapidly as for higher water temperatures,
therefore this effect is considered in the present parameter
determination method. Until now, there were no known equations that
can relate the temperature of the water, its salinity, and the
dilution power for maintaining at least a minimum ORP in a certain
portion of the water for at least a minimum period of time
according to the diffusion of chemicals in the water, due to the
complexity of the variables and its mutual influences. Such
relations are product of an extensive research, and the minimum ORP
level and the minimum period of time that are used for the method
of the present invention, in a preferred embodiment, cannot be
lower than the values defined as follows:
Minimum ORP Level:
[0124] Once the salinity is known from the most unfavorable zone,
the minimum ORP level may be calculated by the following equations:
[0125] i. for salinities between 0% and up to 1.5% the minimum ORP
of the water is at least 550 mV; [0126] ii. for salinities higher
than 1.5%, and up to 2.5%, the minimum ORP of the water is
calculated by the following equation:
[0126] [Minimum ORP,mV]=625-50*[Salinity of the Water,%(Weight
Percent)];and [0127] iii. for salinities higher than 2.5%, the
minimum ORP of the water is at least 500 mV.
[0128] The aforementioned parameter determination method is
represented in a graph as shown in FIG. 3.
[0129] For example, if the water has a salinity of 1% in weight (or
10,000 ppm) the minimum ORP of the water that has to be maintained,
according to this embodiment, will be 550 mV.
[0130] On the other hand, if the water has a salinity of, for
example, 2% in weight (or 20,000 ppm) the minimum ORP of the water
that has to be maintained is 525 mV, according to this embodiment,
is calculated using the following equation:
[Minimum ORP,mV]=625-50*[2]=525 mV
[0131] Finally, if the water's salinity is higher than 2.5%, for
example 3% in weight, the minimum ORP that has to be maintained is
500 mV.
Minimum Period of Time:
[0132] The minimum period of time is determined by the temperature
of the water, and it can be calculated by the following equations:
[0133] i. for water temperatures between 5.degree. C. and up to
35.degree. C., the minimum period of time is calculated by the
following equation:
[0133] [Minimum period of time,min]=80-2*[Temperature of the
water,.degree. C.];and [0134] ii. for water temperatures higher
than 35.degree. C. and up to 45.degree. C., the minimum period of
time is calculated by the following equation:
[0134] [Minimum period of time,min]=5*[Temperature of the
water,.degree. C.]-165.
[0135] The curve showing how the minimum period of time behaves is
shown of FIG. 4.
[0136] For example, if the water's temperature is 20.degree. C.,
the minimum period of time is 40 minutes according to the following
equation:
[Minimum period of time,min]=80-2*[20]=40 minutes
[0137] On another hand, if the water's temperature is between
35.degree. C. and 45.degree. C., for example 40.degree. C., the
minimum period of time is 35 minutes according to the following
equation:
[Minimum period of time,min]=5*[40]-165=35 minutes
[0138] The parameter determination method of the above embodiment
is described only in use for water temperatures between 5.degree.
C. and 45.degree. C., since any other temperature may not be
suitable for recreational purposes.
[0139] The parameter determination method may also comprise
applying chemicals agents through the dispenser means to avoid the
ORP of the most unfavorable zone to be less than the minimum ORP
level.
[0140] When there are bathers in the sanitary-compliant zone, the
ORP of the water will decrease more rapidly than when there are no
bathers in the water. Thus, the present parameter determination
method allows including the effect of the amount of bathers in the
sanitary-compliant zone, which in turn is controlled by the
dilution power of the water. The time taken to reach the minimum
ORP level will depend on the use of the sanitary-compliant zone and
the dilution encountered by the bathers. Therefore, the ORP
decreasing rate will depend on the amount of bathers in the water,
and thus, on the dilution power of the water.
[0141] The variables of water salinity and temperature, ORP, and
chemical concentration can vary and be affected by external
factors. The disclosed methods allow for some variation in these
factors such that constant monitoring of the water salinity, water
temperature and recalculation of the minimum ORP and chemical
concentration may not be required. Nevertheless, in some
embodiments, the water salinity and water temperature can be
constantly monitored on either a delay or in real time, and provide
feedback to a controller that automatically recalculates the
minimum ORP, minimum period of time, and concentration of chemical
agent accordingly. In some embodiments, the dispensers may be part
of an automatic feedback loop where the dispensers automatically
dispense additional chemical agents in response to a decrease in
the minimum ORP. In some embodiments, it may be desirable to
periodically measure the water salinity and temperature and
recalculate the minimum ORP, minimum period of time, and chemical
concentration. Such periodic measurements and calculations could
take place every 15 minutes, every 30 minutes, every hour, every
two hours, six times a day, four times a day, twice a day, once a
day, once a week, or as needed.
[0142] It must be noted that the present disclosure does not
require a physical barrier in order to contain the portion of water
to be treated. Rather, chemical concentrations are applied to the
portion of water in order to comply with specific microbiological
sanitary conditions applied to the water body.
[0143] The application of chemicals in order to maintain at least a
minimum ORP level during at least the minimum period of time may be
repeated before the ORP level decreases by more than 20% of the
minimum ORP value in the most unfavorable zone. In an alternative
embodiment, the location of the most unfavorable zone, the water
salinity and temperature of the water may vary independently from
each other as a result of external conditions. Thus, the method of
the invention optionally may comprise a further step e., where
steps b., c. and d. are carried out once again or repeatedly.
[0144] Chemical agents can be added to the established portion of
water within the large water body through dispenser means, where
the dispenser means is driven by a parameter determination method
that combines the effects of ORP of the water, its salinity, its
temperature, the diffusion of chemicals, and its dilution
power.
[0145] The chemical agents are selected from ozone; chlorine and
chlorine compounds; biguanide products; halogen-based compounds;
bromine based compounds, or a combination thereof.
[0146] It is also possible to improve the sanitary-compliant zone's
water quality by supplying fresh water or water from different
portion within the large water body into such portion in order to
allow a dilution effect of bather's load of contaminants.
[0147] The following example is not intended to limit the scope of
the claims of the invention but is rather intended to be exemplary
of certain embodiment. Any variations in the exemplified method
which raise to the skilled in the art are intended to fall within
the scope of the present invention.
Example
[0148] The disclosed method was applied in Lake Rapel located in
Navidad, Chile. The lake has over 8,000 hectares of surface, and
more than 695 million cubic meters of fresh water. The lake is
normally used for recreational purposes.
[0149] A portion of water within the large water body was
established according to the lake's normal recreational use, which
covered approximately 650 m.sup.2 (corresponding to about 0.0008%
of the total lake area). The portion was located on the edge of the
lake. The specific microbiological conditions required for this
specific experiment corresponded to the microbiological regulations
for direct contact recreational waters as determined by the
EPA.
[0150] Approximately 20 injectors were installed on the north
perimeter of the lake. Each injector had a maximum flow of 1.8
liters per hour. The chemical agent used was sodium hypochlorite,
which was diluted proportional to the injector flow. A solution of
chlorine in water was prepared in a plastic bin with a capacity of
1 m.sup.3. The pumping of the sodium hypochlorite solution was
performed by an IWAKI magnetic pump with a capacity of 18 liters
per minute.
[0151] During the experiment, the established portion of water had
an average of 60 bathers on an hourly basis.
[0152] The determination of the most unfavorable zone was performed
by measuring the ORP in several places within the established
portion of water using a HANNA ORP HI 98201 ORP test equipment
after discharging a predetermined amount of approximately 1.5
liters of a 10% solution of sodium hypochlorite into the
established portion of water. The most unfavorable zone was located
on the center of the delimiting zone of the established portion of
water. The water's salinity was measured with a HANNA HI 931100N
conductivity test. The salinity of the water was found to be 0.07%
in weight, and the average water temperature 21.degree. C. as
measured by a thermometer.
[0153] The minimum ORP level was determined where for salinities
between 0% and up to 1.5% the minimum ORP level of the water is at
least 550 mV. Therefore, the minimum ORP level of the water with a
salinity of 0.07% should be 550 mV.
[0154] The minimum period of time was determined, where for water
temperatures between 5.degree. C. and up to 35.degree. C., the
minimum period of time is calculated by the following equation:
[Minimum period of time,min]=80-2*[Temperature of the
water,.degree. C.]
Minimum period of time in minutes=80-2*[21]
Minimum period of time=38 min
[0155] Sodium hypochlorite was added through the injectors to
maintain a ORP level of at least 550 mV in the most unfavorable
zone for a minimum period of 38 minutes. At first, 1 ppm of sodium
hypochlorite was added to treat the water. Afterwards, sodium
hypochlorite was added in order to maintain a 0.10 ppm residual
concentration, which allowed maintaining at least a 550 mV ORP
level in the most unfavorable zone.
[0156] Once the total amount of sodium hypochlorite was discharged,
the ORP of the most unfavorable zone was measured and determined to
be 555 mV. Subsequent measures were carried out every 60 minutes.
The ORP decreased to 490 mV (by about 11% from the determined
minimum ORP) after about 30 minutes, at which point new sodium
hypochlorite was dispensed.
[0157] The dilution power of the water is reflected in the average
amount of bathers per hour in the sanitary-compliant zone: for
lower bather's densities, the water's ORP will decrease slower than
for higher bather's densities. Also, the decrease in ORP is
affected by the sun and other variables.
[0158] This example confirmed that the sanitary-compliant zone
complied with EPA's specific microbiological regulations for direct
contact recreational waters and even more stringent sanitary
regulations, and allowed applying a small amount of chemicals by
avoiding the treatment of the complete large water body, by
treating the identified portion of water in order to create a
sanitary-compliant zone.
[0159] The chemicals applied in the present example were at least
100 orders of magnitude lower compared to the amount of chemicals
required to treat the complete water body. In order to treat the
complete water body of Lake Rapel, which holds over 695 million
cubic meters of fresh water, and allow its use for recreational
purposes, a certain amount of chemicals must be added that can
ensure the safety of bathers. In order to maintain the same ORP
level as for the example (a concentration of 0.10 ppm of sodium
hypochlorite with the additional 1 ppm added beforehand to treat
the water), the total amount of sodium hypochlorite that must be
applied is approximately 764.5 tons, which is more than 100,000
times the amount of sodium hypochlorite that is required for
treating the portion of water from the aforementioned example,
which is economically and environmentally unviable.
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