Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR STERILISATION AND CLEANING OF WATER SUPPLY
SYSTEMS. IN PARTICULAR IN SWIMMING AND BATHING POOL UNITS
AND DEVICE FOR CARRYING OUT THE SAME
The invention relates to a method for
sterilization and cleaning of water supply systems,
especially in swimming and bathing pool units, and to a
device for carrying out the same.
The treatment of water, especially in swimming
pools, already needs to meet stringent requirements
with respect to treatment and disinfection. Hygiene is
of very crucial importance in swimming and bathing pool
water. This also relates, for example, to biogenic
deposits (biofilms) in the filter bed - which
inevitably occur in water supply systems - and
contamination of the water supply system (pipes) and
the filters with a wide variety of germs, such as
pathogens, sporogens, microorganisms etc., so that
effective cleaning and disinfection which can be
performed in a technically straightforward way -
further to the mandatory disinfection of the water,
i.e. swimming and bathing pool water - has to be
carried out at regular time intervals.
It is therefore necessary to ensure a
consistently high water quality, with the need to
provide a sufficient germicidal capacity for
disinfection or killing germs and microorganisms, on
the one hand, but at the same time the bather should in
no way be harmed by chemical or microbiological levels
in the bathing water.
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Improper water treatment and disinfection may
lead to significant risks of infection and therefore
health risks for the bathers, for example due to
pathogenic germs, sporogens or viruses etc.
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Studies have shown that about 80 to 90% of the
various filter materials, especially in the lower
region, carry high levels of germs - including human
pathogens such as Pseudomonas aeruginosa or Legionella
pneumophilia. Besides the filter material, this also
affects the filter chamber walls, the filter nozzles
and the entire pipeline of the water supply system of a
swimming and bathing pool unit.
Known methods of water treatment and
disinfection have the disadvantage that apart from the
customary disinfection of the bathing water, the water
supply systems are only cleaned and disinfected
insufficiently. This is true even when large amounts of
chlorine are used. The disadvantages of this are
readily apparent, so that increasing contamination by
water constituents, and therefore biogenetic deposits
(biofilms) in the water supply system, cannot be
avoided even with high concentrations.
It has recently become known in the technical
world that the biofilms create their own living space
for microorganisms, which is supplied correspondingly
well with water, substrates and nutrition. A variety of
microorganisms, such as bacteria, protozoa or viruses,
live in this "self-contained living space". The
microorganisms not only have nutrition in this living
community, but also protection for further
proliferation. The biofilms includes corresponding
channels for feeding the microorganisms (inhabitants).
The danger with this is that the bacteria
themselves can actively separate and therefore enter
the water in an aggregate form. These aggregates are
relatively insensitive to levels of disinfectant such
as those prescribed for swimming and bathing pool
water.
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Disinfectant-free regions are then particularly
dangerous, as occur in swimming pool units - when using
absorptive materials that contain carbon - in the lower
region of the filter material and the filter chamber
and the filter line. Undesirable growth of biofilms
therefore occurs relatively rapidly.
Not least the pipe materials, which are
predominantly made of plastic, play a significant part
in this.
The older these biofilms are, the more
difficult they are to break down. The levels of
chlorine customarily used in swimming pools, for
example, do not remove existing biofilms. The breakdown
of biofilms by means of suitable methods will become
even more important in the future because of the
recently identified risks to human health.
According to one example from the prior art,
DE-32 29 219 describes the use of a surface-active
substance as a backwash medium for backwashable filter
beds containing particles, for water treatment in
swimming pool, drinking and waste water treatment
units. The cleaning effect of this method, however, is
only moderate against solid deposits. In particular,
only a minor effect is achieved against contamination
of the filter by microorganisms. The surface-active
substance furthermore needs to be used in high
concentrations, which leads to high costs and high
levels in the waste water.
It is therefore an object of the present
invention to provide a method which does not have the
disadvantages explained above. In particular, besides a
high cleaning and sterilizing effect - to tackle the
problem of biofilms - the method according to the
invention should also facilitate effective
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decontamination of the entire water supply system or
the entire water supply area, for example a swimming or
bathing unit, and in particular dispose of
microorganisms, pathogenic germs, sporogens, viruses,
fungi and all types of contamination. The method should
also be cost-effective, that is to say permit
economically viable operation, and lead to only minor
levels in the waste water.
According to the invention, this object is
achieved by a method for sterilization and cleaning of
water supply systems and areas, with the following
steps:
(1) setting up a closed circuit between two
points of the water supply system, or the water supply
area,
(2) adding a predetermined amount of a
disinfecting agent in the form of an aqueous rinsing
solution containing chlorine oxide, halogen and/or
peroxide, for sterilization and cleaning,
(3) sterilizing and cleaning the pipes, filters
and filter materials contained in the system, including
filter carbon with or without adsorptive properties,
while periodically circulating the rinsing solution in
the closed circuit at defined time intervals,
(4) discharging and disposing of the aqueous
rinsing solution, and
(5) re-establishing the original water circuit.
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According to another aspect of the invention, the object is achieved by a
method of disinfecting and purifying a water-conveying system and surface
having
an original water circuit, wherein disinfection and purification are effected
by adding
a set quantity of a disinfectant in the form of an aqueous rinsing solution
containing
at least one of a chlorine oxide or halogen and a peroxide, characterised by
the
following steps:
(1) constructing a closed circuit in the original water circuit between a
first
and a second point of the water-conveying system or the water-conveying
surface,
wherein components of the system for disinfection and purification are
disposed in
a mechanical fluid communication between the first and the second point and
comprise at least pipes, filters and filter materials, including filtering
charcoal with or
without adsorptive properties,
(2) adding into the closed circuit, the aqueous rinsing solution for
disinfecting
and purifying,
(3) disinfecting and purifying the components by periodically circulating the
aqueous rinsing solution in the closed circuit at defined intervals,
(4) discharging the aqueous rinsing solution from the closed circuit and
dumping the solution, and
(5) re-establishing the original water circuit.
The method is preferably used for sterilizing
and cleaning a swimming or bathing pool unit.
According to a first variant of the method
according to the invention, therefore, a closed circuit
is first set up in step (1) between the outlet of the
overflow water tank and the inlet immediately before
the clean water enters the swimming or bathing pool.
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This may be done by the person skilled in the art using
known means according to the swimming or bathing bath
unit involved, and will depend on the structural
situation in question. This is followed in step (2) by
the addition of a predetermined amount of a
disinfecting agent selected from an aqueous rinsing
solution containing chlorine oxide, halogen and/or
peroxide, for sterilization and cleaning. The amount of
rinsing solution and its composition may be modified
according to requirements, and should be determined
appropriately with reference to the water supply system
in question, its size, capacity, degree of
contamination and the time available for the cleaning.
Step (3) involves the sterilization and
cleaning of the pipes, filters and filter materials
contained in the system, including filter carbon with
or without adsorptive properties, with periodic
circulation of the rinsing solution in the closed
circuit at defined time intervals. In other words, the
rinsing solution does not need to be circulated
continuously, and prolonged working times in which it
is not circulated may also be included.
It has proved expedient for the rinsing
solution to be circulated from a few minutes to a
several hours, for example about 3 to 10 minutes, or
about 3 to 12 h, preferably about 4 to 8 h, and in
particular about 4 to 6 h, in which case the
circulation may be interrupted one or more times. The
circulation is therefore initiated from so-called
resting phases, in which the rinsing solution is left
to stand for a particular working time. The circulation
is preferably carried out in a privileged direction, or
it may be carried out alternately in one of the two
directions.
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After the sterilization and cleaning, the
aqueous rinsing solution is discharged and disposed of
in step (4) of the first variant of the method
according to the invention. The rinsing solution may be
used repeatedly after testing for the presence of
unconsumed active agent (quantitative test).
Lastly, the original water circuit of the
swimming or bathing unit is restored in step (5) by
simply dismantling or removing the extra lines, devices
or systems installed temporarily, so that normal
operation can be resumed.
It is recommendable to repeat this first
variant of the method with steps (1) to (5), that is to
say carry it out at regular time intervals, in order to
maintain an appropriate cleaning and sterilization
effect, i.e. to avoid undesired contamination for a
prolonged period of time.
In another preferred embodiment, the water
supply system is a hot tub, in particular a hot
whirlpool or a whirl tub. The method, however, may also
be used to good effect for a drinking water supply
system in a household installation, in particular in a
shower system. For use in a shower system, it is
particularly preferable to set up a closed circuit in
step (1) between the hot water boiler and the shower
head. Good results are also achieved when the method is
applied to a process water treatment system in the
industrial sector.
Another particularly preferred variant of the
method according to the invention, provides a method
for sterilization and cleaning of water supply systems
and areas, especially in treatment units, pipe systems
and swimming and bathing pool units, with the following
steps:
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(a) isolating a defined section inside the
water supply system,
(b) introducing a highly concentrated rinsing
solution, containing at least one disinfectant agent,
(c) flushing the defined section with the
rinsing agent, optionally with circulation,
(d) collecting the rinsing solution,
(e) checking for the presence of the active
agent and/or the concentration of the active agent
and/or the sterilizing and cleaning effect,
(f) optionally repeating steps (c) to (e),
(g) discharging and disposing of the aqueous
rinsing solution, and
(h) re-establishing the original water circuit
of the swimming and bathing pool unit.
According to another aspect of the invention, there is provided a method of
disinfecting and purifying a water-conveying system and surface, said water-
conveying system and surface having an original water circuit and being at
least
one of a processing installation, a pipe system and a swimming- and bathing-
pool
establishment, wherein disinfection and purification are effected by adding a
concentrated aqueous rinsing solution containing at least one disinfectant,
characterised by the following steps:
(a) dividing off a defined portion of the original water circuit between a
first
and a second point in the water-conveying system, wherein components of the
system for disinfection and purification are disposed between the first and
the
second point in a mechanical fluid communication, said components comprising
at
least pipes, filters, and filter materials,
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(b) introducing the concentrated aqueous rinsing solution into the defined
portion,
(c) thoroughly rinsing the defined portion with the concentrated aqueous
rinsing solution, optionally with circulation,
(d) removing a sample of the concentrated aqueous rinsing solution from the
defined portion,
(e) checking in the sample, at least one of: a presence of the disinfectant, a
concentration of the disinfectant, a disinfecting effect and a purifying
effect,
(f) optionally repeating steps (c) to (e),
(g) discharging the concentrated aqueous rinsing solution from the defined
portion and dumping the concentrated aqueous rinsing solution, and
(h) re-establishing the original water circuit.
According to the second variant according to
the invention, a defined section in the water supply
system is first isolated in step (a), that is to say a
particular region is selected and two delimitations are
provided. According to step (b), a highly concentrated
rinsing solution containing at least one disinfectant
agent is then introduced in this defined region.
The defined section is then flushed with the
rinsing solution (step (c)). The expression "flushing"
is intended to be understood in the broad sense in the
present invention. According to one option, this may be
done by introducing a gas and moving the rinsing
solution through the defined section by using pressure.
Compressed air is preferably used. According to another
embodiment, the pipe inner walls, filters and filter
materials may also be sprayed with the rinsing
solution. Optionally, the rinsing solution may also be
circulated as described above.
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After collection of the rinsing solution in
step (d), a check is carried out as to whether any
disinfectant agent is still present. The disinfecting
effect may be inferred from the amount of active agent
consumed (also referred to as depletion). Complete
disinfection is obtained when no more disinfectant is
consumed. Another more accurate check may be carried
out by determining the concentration of the active
agent before and after the disinfecting rinse, and
subsequently comparing the two concentration values. An
appropriate method for checking the disinfecting effect
may be selected according to requirements.
According to the invention, the sterilization
and cleaning effect is preferably checked by using the
known Bart a test (biological activity reaction test),
although this may also be done by using other known
tests relating to adsorption activity or other
biological studies, depending on the filter materials
involved. Such checking methods, quick tests and the
like are known to the person skilled in the art, so
they do not need to be explained in detail.
Steps (c) to (e) for sterilizing and cleaning
the water supply system may be repeated according to
requirements.
According to the invention, the aforementioned
first and second variants of the method may also be
coupled so that sections of a process path which are
particularly difficult to clean may additionally be
subjected to separate cleaning and disinfection. In
order to clean and disinfect process paths in which the
central treatment stage - the filtration - is carried
out with filter materials that have adsorptive
properties (for example granular activated carbon or
particular types of lignite), for example, it is
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advantageous to initially treat these filter materials
separately by first of all introducing the requisite
amount of rinsing solution, which is needed in order to
clean (chemically and microbiologically) carbon-type
materials with adsorptive properties and allow it to
act (first variant of the method of the invention).
The overall cleaning process may then be
carried out by circulation of the rinsing solution
either in only a part of a given process path
(repetition of the first variant of the invention), or
the entire process path may undergo the cleaning and
disinfection (second variant of the method of the
invention).
For example, it is possible for a granular
activated carbon filter contaminated to an undesirably
high degree, which is for example connected downstream
of a sand filter, to be specially treated periodically
with this cleaning system. Very specific sections of
pipeline, for example the filtrate line and the clean
water line, may thus be deliberately cleaned and
disinfected in a process path circuit by the method
according to the invention.
According to particularly preferred embodiment
of the invention, an aqueous solution containing
chlorine oxide is used as the aqueous rinsing solution.
Among the oxides of chlorine, chlorine dioxide has been
found to be particularly preferred both for reasons of
efficacy and availability. Since chlorine dioxide is a
chemically unstable substance which is difficult to
handle, it is advantageous for a large part of the
chlorine dioxide in the solution not to be present in a
free form, but to be chemically bound in the form of a
chemical species from which chlorine dioxide is
constantly reformed. One such substance is the
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tetrachloride decaoxide complex dianion [C14010]2-. This
complex dianion, which is documented under the ELINCS
number 420-970-2, reacts in aqueous solution according
to the following two reactions:
(1) [C14010)2_ -. 4C102 + 02 + 2e- (continuous
phase)
(2) [C1401o]2- + 2e- 502 + 4Cl- (balanced overall
equation)
The tetrachloride decaoxide complex dianion is
thus in an equilibrium with the chlorine oxide, so that
the solution of the dianion always contains a certain
amount of chlorine dioxide which is obtained as an
intermediate product from breakdown of the complex, and
which is replenished as it is consumed. The TCDO
complex therefore constitutes a biocatalytically
activatable oxygen carrier, which differs in terms of
its oxidation properties qualitatively from
hypochlorite, chlorate and hydrogen peroxide and
quantitatively from chlorite. Merely oxygen and
chloride are formed as the final reaction products,
which do not lead to any waste water problems.
A preferred embodiment of the invention
therefore uses an aqueous solution of the tetrachloride
decaoxide complex dianion [C14010]2-, which has outside
excellent properties owing to the biocatalytically
selective action mechanism. This aqueous solution
containing tetrachloride decaoxide complex dianions is
preferably obtained by mixing an aqueous solution of pH
< 3 containing sulfate ions with a peroxo compound,
which is stable in it, and subsequently adding the
alkaline aqueous solution of a chlorite to this
solution. The aqueous solution containing sulfate ions
is preferably mixed with the peroxo compound, which is
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stable in it, in such an amount as to provide a peroxo
compound concentration of from about 0.001 to 0.01
molar in the solution. According to the invention, it
is also possible for the aqueous solution containing
sulfate ions to be mixed with the peroxo compound,
which is stable in it, and for the alkaline aqueous
solution of a chlorite to be subsequently added to this
solution in such an amount as to obtain a pH of more
than 7.0, in particular between 7.5 and 8Ø
It has been found particularly advantageous for
an inorganic peroxo compound in the form of hydrogen
peroxide, persulfate, percarbonate, perborate or a
peroxide of an alkali or alkaline earth metal, to be
used as the peroxo compound. An alkali metal chlorite and/or
an alkaline earth chlorite is preferably used as the
chlorite. Particularly advantageous results are obtained when
the aqueous solution containing sulphate ions has a pH S 1.
When the aqueous starting solutions which are
used have only a minor carbonate hardness, or can be
prepared with demineralized water, it is recommendable
to operate in an inert gas atmosphere since the
formation of explosive air/chlorine dioxide mixtures
can occur in the absence of a protective gas layer
between the slightly gas-evolving chlorine dioxide and
air. With an air to chlorine dioxide component ratio of
about 10:1, air/chlorine dioxide mixtures are
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susceptible to explosive breakdown of the chlorine
dioxide into chlorine and oxygen. In the case of the
aqueous starting solutions of medium or high carbonate
hardness (carbonate hardness > about 7 degrees or >
about 1.3 mmol/1), the use of an inert gas is generally
unnecessary since a kind of a protective gas layer of
carbon dioxide is formed. Mineralized water is
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therefore preferably used to prepare the aqueous
solution containing sulfate ions, which is to be used
in order to form the solution containing tetrachloride
decaoxide complex dianions.
The solution containing tetrachloride decaoxide
complex dianions preferably contains a water-soluble
phosphate, since the amount of peroxo compounds can be
reduced when the final solution includes a small amount
of a water-soluble phosphate, for example sodium
metapolyphosphate.
The concentration with which the aqueous
rinsing solution is used depends on various factors,
for example the degree of contamination and/or biogenic
deposits or bacterial contamination of the water supply
system. The aqueous rinsing solution containing
chlorine oxide, halogen and/or containing peroxide in
the method according to the invention is therefore
preferably used in a concentration which corresponds to
and an initial chlorite concentration of at least about
0.1 mol/1, preferably at least about 0.15 mol/l. This
has led to particularly good results according to the
invention.
Other aqueous rinsing solutions containing
chlorine oxide, halogen and/or containing peroxide
besides the aforementioned inventive variants of the
aqueous solution of the tetrachloride decaoxide complex
dianion [C14O10] 2- may of course be used, although these
are less preferred.
The method is preferably configured in such a
way that continuous dosing of the disinfectant is
provided. Such a dosing technique may, for example, be
provided using feed water of a unit for providing
washing and shower water, or alternatively in the
bypass of a feed water line of swimming bath units or
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in feed lines of water for industrial purposes. It is
particularly preferable to configure a unit so that
both continuous rinsing with the disinfectant and
continuous dosing of the disinfectant are possible.
Fig. 1 shows an arrangement for a shower unit, with
which it is both possible to introduce the necessary
amounts of disinfectant for periodic rinses of water
supply systems, but also continuous dosing of
disinfectants can be carried out.
For the case of periodic rinsing, the shut off
taps (3) and (20) are closed. The draining cock (7) is
opened and the same amount of water is taken from the
system as will subsequently be refilled with a
disinfectant solution-working solution. The shut off
taps (6) and (17) need to be opened before draining and
filling with the disinfectant solution. The circulation
pump (16) is subsequently turned on and the required
amount of disinfectant is simultaneously dosed (the
rinsing is carried out according to a stop-and-go
method, the delivery flow device being changed at
specific intervals). The entire system is drained after
the rinsing process. The system is subsequently filled
again with drinking water, circulated again and
drained. This insures that any remaining disinfectant
solution and residues of biogenic deposits and
contamination are rinsed from the system. The line is
then filled again with drinking water and can return to
operation.
If continuous dosing of the disinfectant is
intended to be carried out, the two shut off taps (6)
and (20) are closed. The shut off taps (1), (3), (8),
(14) and (17) are opened. The required amount of
disinfectant solution is dosed as a function of the
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water consumption, using the two dosing pumps and
contact water meters.
Although this description refers to a shower
unit as an example, other applications of the method
for sterilizing and cleaner water supply systems and
quantitatively proportional dosing of disinfectant are
possible.
The invention also relates to a device for
sterilization and cleaning of water supply systems and
areas, comprising:
(1) a closed circuit between two points of the
water supply system, or the water supply area,
containing a predetermined amount of at least one
disinfecting agent in the form of an aqueous rinsing
solution containing chlorine oxide, halogen and/or
peroxide, for sterilization and cleaning,
(2) a pump for circulation of the rinsing
solution in the closed line system while sterilizing
and cleaning the pipes and filters contained in the
system,
(3) an outlet for the aqueous rinsing solution,
and
(4) means for re-establishing the original
water circuit.
In the preferred embodiment, the water supply
system is a swimming or bathing pool unit. In this
case, the sterilization and cleaning of the swimming
and bathing pool system is carried out by a device
comprising:
(1) a closed circuit between the outlet of the
overflow water tank and the inlet immediately before
the clean water enters the swimming or bathing pool,
containing a predetermined amount of at least one
disinfecting agent in the form of an aqueous rinsing
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solution containing chlorine oxide, halogen and/or
peroxide, for sterilization and cleaning,
(2) a pump for circulation of the rinsing
solution in the closed line system while sterilizing
and cleaning the pipes and filters contained in the
system,
(3) an outlet for the aqueous rinsing solution,
and
(4) means for re-establishing the original
water circuit.
According to another aspect of the present invention, there is provided a
device for disinfecting and purifying a water-conveying system and surface,
the
water-conveying system and surface having an original water circuit and
comprising
at least one of a pipe and a filter and wherein the device comprises
introducing
means for introducing a set amount of at least one disinfectant, the device
being
characterised it that it comprises:
(1) means for producing a closed circuit in the original water circuit between
a first and a second point on the water-conveying system or the water-
conveying
10 surface, wherein the components of the system for disinfection and
purification are
disposed between the first and the second point in a mechanical fluid
communication and comprise at least said at least one pipe and filter,
(2) the introducing means, wherein said introducing means are provided for
introducing the set quantity of the at least one disinfectant into the closed
circuit
and wherein the disinfectant is a at least one of chlorine oxide- or halogen-
and a
peroxide-containing aqueous rinsing solution used for disinfecting and
purifying,
(3) at least one pump for circulating the aqueous rinsing solution in the
closed circuit for disinfecting and purifying the components,
(4) at least one outlet for out flowing the aqueous rinsing solution from the
closed circuit, and
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(5) means for re-establishing the original water circuit.
According to yet another aspect, there is provided a device for disinfecting
and purifying a water-conveying system and surface, said water-conveying
system
and surface having an original water circuit and being at least one of a
processing
installation, a pipe system and a swimming- and bathing-pool establishment,
said
device comprising introducing means for introducing a concentrated aqueous
rinsing solution containing at least one disinfectant and means for checking
at least
one of a presence of the disinfectant, a concentration of the disinfectant and
a
disinfecting and purifying effect, and being characterised in that it
comprises:
(a) means for dividing off a defined portion in the original water circuit
between a first and a second point in the water-conveying system, wherein
components of the system for disinfection and purification are disposed
between
the first and the second point in a mechanical fluid communication, said
components comprising at least pipes, filters and filter materials,
(b) the introducing means, wherein said introducing means are for
introducing the concentrated aqueous rinsing solution into the defined
portion,
(c) means for rinsing the defined portion with the concentrated aqueous
rinsing solution in order to disinfect and purify said components,
(d) means for withdrawing a sample of the concentrated aqueous rinsing
solution from the defined portion,
(e) means for discharging the concentrated aqueous rinsing solution from the
defined portion, and
(f) means for re-establishing the original water circuit.
The device according to the invention thus
comprises a closed circuit between the outlet of the
overflow water tank and the inlet immediately before
the clean water enters the swimming or bathing pool,
and contains a predetermined amount of at least one
disinfecting agent in the form of an aqueous rinsing
solution containing chlorine oxide, halogen and/or
peroxide, for sterilization and cleaning. This is
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preferably the aforementioned tetrachloride decaoxide
complex dianion in aqueous solution.
At least one pump is furthermore provided for
circulation of the rinsing solution in the closed
circuit while sterilizing and cleaning the pipes and
filters present in the system, which pump operates in
the so-called "stop and go" mode, that is to say
circulation is carried out for a defined time interval
as required, in which case the circulation may also
take place alternately in one direction and then the
other, and is subsequently turned off so that the
rinsing solution remains in the water supply system and
can act, before resuming the circulation of the rinsing
solution.
According to a preferred refinement according
to the invention, the device for sterilization and
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cleaning of water supply systems and areas, especially
in treatment units, pipe systems as well as swimming
and bathing pool units, may comprise:
(a) means for isolating a defined section
inside the water supply system,
(b) means for introducing a highly concentrated
rinsing solution, containing at least one disinfectant
agent,
(c) means for flushing the defined section with
the rinsing agent, optionally with circulation,
(d) a device for collecting the rinsing
solution,
(e) means for checking for the presence of the
active agent and/or the concentration of the active
agent and/or the sterilizing and cleaning effect,
(f) means for discharging the aqueous rinsing
solution, and
(g) means for re-establishing the original
water circuit of the swimming and bathing pool water
unit.
This allows optimum control and supervision of
the cleaning and sterilization effect, on the water
supply system, as already explained in detail with
reference to the respective variant of the method of
the invention.
The method and the device of the invention are
suitable for sterilizing and cleaning various types of
water supply systems in bathing units, especially in
swimming and bathing pool circuits, there being in
principle no restrictions with respect to the type,
size and design of the water supply system. The two
variants of the method, or devices of the invention may
also be combined, so that even problematic regions of
the process path can be sterilized and cleaned.
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Overall, it can be said that the invention
provides for sterilization and cleaning of swimming
pool units which leads to much better results compared
with the prior art. For instance, the cleaning effect
with respect to biogenic deposits (biofilms) is
significantly improved. The very crucial advantages
with respect to the effect against contamination by
germs, microorganisms, sporogens, viruses and fungi are
thus particularly pronounced. The cleaning methods
described in the prior art only achieve a weak effect
in this case. Surprisingly, it has been found that the
method according to the invention not only leads to
substantial disinfection with respect to occurrence of
microorganisms or the buildup of biofilms structures,
but a strong preventive effect is also be achieved.
This is possibly attributable to the fact that killing
all the germs and simultaneously eliminating virtually
all the contamination which could lead to growth of the
microorganisms, for example by acting as a nutrition
source, prevents proliferation of microorganisms even
for a prolonged time after the treatment. Use of the
method according to the invention therefore can and
should be regarded and carried out as a preventive
method for active and preventive health protection.
The aforementioned embodiments according to the
invention therefore make it possible to select
expediently particular sections of a process path and
adapt the cleaning and disinfection method to them.
This entails less consumption of water, especially when
the pipe cross sections are relatively large. The
required amount of rinsing solution can be reduced
drastically, while the same high cleaning and
sterilizing effect is still achieved. Another advantage
of the described variants of the method of the
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invention makes it possible to check the cleaning
effect after each run, so that expedient control can be
achieved and another run can be carried out only if
required. This ensures that the concentration of the
rinsing solution, the duration of the cleaning process
and the amount of water used can be matched optimally
to one another. Regions that are particularly difficult
to clean can furthermore be addressed, and particular
sections of pipeline in a process path, for example the
filtrate line and the clean water line, can be
expediently cleaned and disinfected. Owing to the much
lower amount of water, costs for the rinsing solution
can therefore be saved according to the invention, but
without the occurrence of significant levels in the
waste water.
An embodiment of the device according to the
invention will be presented with reference to appended
Figure 2. It schematically represents the following:
- overflow water tank (10),
- access to the feed water pipeline (20a),
- sampling line and sampling cock (25a) for feed water
before the first treatment stage of flocculation (Fl.),
- filter (30) with
- adsorption stage (30a)
- barrier layer (30b) and
- protective layers (30c),
- sampling line and sampling cock (25b) in the filtrate
before the disinfection (chlorination),
- heat exchanger (40),
- device for the basic and operational chlorination
(50),
- sampling line and sampling cock (25c) in the clean
water after the disinfection (chlorination) immediately
before entering the pool,
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- access to the clean water pipeline (20b) and
- swimming pool (60).
The filter (30) has the strongest degree of
contamination in the lower region, i.e. in the
protective layers (30c), which then continues to the
device for the basic and operational chlorination (50)
and may extend in an attenuated form as far as the
swimming pool (60). Nevertheless, strong to medium
contamination also occurs in the upper region of the
filter, the adsorption stage (30a) and on the tank
edges of the overflow water tank (10).
In order to sterilize and clean these
particularly strongly contaminated regions of the
process path in the water supply system of the swimming
pool unit, therefore, a closed line system (not shown)
is formed between the outlet of the overflow water
tank, i.e. the access (20a), and the inlet immediately
before the clean water enters the swimming or bathing
pool, the access (20b). A predetermined amount of an
aqueous rinsing solution containing chlorine oxide,
halogen and/or peroxide, preferably the TCDO complex,
is added to this system for sterilization and cleaning
and is circulated at defined time intervals by using a
pump (not shown). The sampling cocks should be slightly
open during the circulation of the rinsing solution, so
as likewise to permit cleaning and disinfection by the
rinsing solution of the pipes and tubes which lie
between the pipelines (lines for feed water, filtrate
and clean water) and the sampling cocks.
This is important because, as is known, the
water in these pipelines and tubes is predominantly in
a stagnation phase over time and during operation of
the circulation unit (filtration process). This
repeatedly leads to enhanced microbiological
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contamination of the pipes and tubes of the sampling
cocks and possible misinterpretation in the
microbiological testing.
After cleaning and sterilization has been
carried out, the aqueous rinsing solution is discharged
and the original water circuit of the bathing unit as
shown in Figure 1 is restored.
The invention will be explained below with
reference to examples:
Example 1:
- Preparation of a solution containing tetrachloride
decaoxide complex dianions -
0.5 g of a 30 wt.% strength hydrogen peroxide
solution is added to 1 1 of water containing sulfate
(carbonate hardness: 18 degrees or 3.2 mmol/1) with a
pH of O.S. 0.9 1 of a commercially available sodium
chlorite solution (about 300 g of sodium chlorite/l)
are added to this solution while stirring thoroughly.
The solution then passes through a brown color change,
which becomes a light lime-green color when the pH of 7
is exceeded after the stabilization reaction has taken
place. A pH of about 7.5 is thereby set up in the
solution.
Example 2:
- Sterilization and cleaning of the water supply system
of a swimming bath with the first method according to
the invention, or device variant -
In the present case, a bathing water treatment
unit of a swimming pool and a recreational pool in a
public baths are sterilized and cleaned. The flow rate
is 150 m3 per hour with a pool water volume of about
470 m3. The bathing unit is used by 350 persons/day on
average. The user frequency varies between about 250
and 1000 persons/day during the times when it is open.
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The method according to the invention was
carried out as follows:
A closed circuit was first set up between the
outlet of the overflow water tank and the inlet to the
swimming pool. This is done by providing extra inputs
and outputs and particular points on the feed water
pipeline and clean water pipeline of the swimming water
treatment unit.
The filter is then rinsed according to the
rinsing data required for the unit. After rinsing, the
circulation unit is returned to normal operation. After
circulation of the swimming and bathing pool water for
about 10 minutes, the unit is turned off and a check is
made that no water has been lost from the process path.
Just the amount of water which will be made up
again by introducing the disinfection solution is then
removed from the process path to be cleaned. An aqueous
rinsing solution for sterilization and cleaning in the
form of a tetrachloride decaoxide complex dianion
solution is then added in a concentration which
corresponds to an initial chlorite concentration of
about 0.1 to 0.2 mol/l.
The disinfection solution is introduced by
dosing by means of dosing pumps during the circulation
in the parts of the process path of the bathing pool
water treatment unit to be cleaned.
The rinsing solution was circulated by means of
a special frequency-controlled circulation pump with
the so-called "stop-and-go" method for defined
intervals, each of about 1 to 3 hours, and the pump was
turned off for about 20 to 40 min. in order to provide
a specific action time of the rinsing solution.
In the so-called "resting phases", it is
advantageous for there to be a rinsing air fan in order
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to "blow" rinsing air into the filter for 2 to 5 min.
and achieve additional loosening of the filter
material, which promotes the oxidative cleaning process
by the TCDO solution in the filter material.
After having used the rinsing solution for
about 3 hours, a check should be carried out using a
TCDO reagent as to whether and active agent from the
TCDO solution being used is still present in the
rinsing solution. This is intended to ensure that
sufficient efficacy of the disinfection solution is
provided throughout the cleaning process.
The aqueous rinsing solution is then discharged
and disposed of. This is only done in the pipelines.
The residual rinsing solution in the filter is
extracted by rinsing the filter via the rinsing water
line.
The original water circuit of the swimming and
bathing pool water treatment system is then restored.
The filter should then be rinsed again after an
operating time of 24 to 36 hours.
The amount of rinsing solution was 120 1 of
working solution (active agent: TCDO anion) which was
introduced into a total of 9 m3 water and used as the
rinsing solution.
Example 3:
- Sterilization and cleaning of the water
supply system with a variant of the method according to
the invention -
The procedure in Example 2 was carried out, but
the rinsing solution was circulated for defined time
intervals, each of about 1 to 3 hours, and the pump was
turned off for about 30 to 60 min. in order to provide
a specific action time of the rinsing solution.
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The sterilizing and cleaning effect of the
rinsing solution was found by the disinfectant test
according to DIN EN 1276/August 1997 (Chemical
Disinfectants and Antiseptics) and studies and tests -
by laboratory techniques and on the industrial scale -
for the chemical cleaning and disinfection of
microbiologically contaminated granular activated
carbons from various public swimming pool units with
the tetrachloride decaoxide dianion (TCDO complex).
For practical use, qualitative detection of the
TCDO anion in the rinsing solution can be and is
carried out using the HydroQuant TCDO reagent. The HydroQuant TCDO
reagent essentially consists of an aqueous solution of iron(III) chloride with
the
empirical formula FeCl3, constitutes an easy-to-handle
chemical test agent and makes it possible to detect the
TCDO anion in the form of a color change (coloration
from bright yellow to brown). If the TCDO anion is
still present in the rinsing solution, then a brown
coloration is found which occurs irrespective of the pH
of the solution in a broad pH interval of from pH 3 to
pH 11. The brown coloration also occurs irrespective of
the freely active chlorine content. Even freely active
chlorine concentrations of up to 100 mg/1 have no
effect on the measurability of the TCDO anion in the
rinsing solution. The sterilizing and cleaning effect
of the rinsing solution was accordingly found from the
consumption of the TCDO complex.
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Example 4:
- Sterilization and cleaning of the water
supply system with another variant of the method
according to the invention -
A closed circuit was set up as in Example 2,
but with accurately defined delimitations, by means of
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which a very specific section of the process path is to
be sterilized and cleaned.
A tetrachloride decaoxide complex dianion
solution in a concentration which corresponds to an
initial chlorite concentration of about 1.5 mol/l was
then added as a highly concentrated aqueous rinsing
solution for sterilization and cleaning. The amount of
rinsing solution was from 1/100 to'1/20 of the pipe
volume. The rinsing solution was delivered through the
isolated section by compressed air.
The sterilizing and cleaning effect was
determined as described above in Example 3.
c
