PURPOSE: Although chlorination is the traditional method of disinfecting swimming pools, hot tubs, and cooling towers to prevent outbreaks of illness due to pathogenic bacteria, viruses, and protozoa, high levels of chlorine can cause eye and skin irritation was well giving rise to a noticeable chlorine odor. The authors evaluated electrolytically generated copper: silver ions alone and in combination with low levels of free chlorine as an alternative method of reducing the bacterial population in water.
MATERIALS AND METHODS: The test medium was local well water which was subjected to chemical analysis, filtering, and pH stabilization and used at room temperature. Suspensions of the following organisms were prepared: Escherichia coli, Legionella pneumophila, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella TYPHII, Klebsiella terrigena, and Streptococcus faecalls. Approximately 1 ml of the selected bacterial suspension was added to 99 ml of test medium containing (1) copper: silver ions in a concentration of 400 ug/liter copper to 40 ug/liter silver, (2) free chlorine (0.2 mg/liter) alone, or (3) a combination of copper: silver ions and free chlorine (quantities as above). Cultures were incubated and the bacterial colonies enumerated, after which statistical analysis were performed.
RESULTS: The bacteria tested were inactivated more rapidly in a solution in which electrolytically generated copper and silver ions were added to low levels of chlorine than where either method was used separately. Some organisms were more resistant to treatment than others. In the experiments with Salmonella typehi and Klebsiella terrigena no viable cells were recovered after 30 seconds of exposure to either chlorine alone or to the combined regimen, indicating equal effectiveness when resistance to disinfection is low. On the other hand, Legionella pneumophilia titers decreased more than 5 log 10 values after 7 minutes of exposure to free chlorine (0.2 mg/liters) alone for the same length of time. Similarly, E. coli numbers were reduced by 4.2 log 10 by the combination regimen but by less than 3 log 10 after extended exposure to the copper: silver method without chlorine.
CONCLUSIONS: The use of electrolytically generated copper and silver ions in combination with low levels of free chlorine proved an effective method of killing a wide range of pathogenic bacteria under controlled test conditions. Such bacteria are of potential concern in swimming pools and cooling towers.
Inactivation of Poliovirus & Bacteriophage MS-2 by Copper/Silver and Reduced Levels of Free Chlorine
AUTHORS: Landeen LK, Yahya MT, and Gerba CP
PURPOSE OF STUDY: Viruses tend to be more resistant than bacteria to disinfection regimes. Although chlorination is widely used to control viral contamination, high levels of chlorine promote the formation of organic compounds in water that may be hazardous to human health. An alternative method, copper and silver ion treatment, is known to be effective against bacteria and algae. The authors tested electrolytically generated copper and silver ions, alone and in the presence of reduced levels of free chlorine, in treating water sample to which either bacteriophage MS-2 or poliovirus had been added to test effectiveness against viral contamination.
MATERIALS AND METHODS: Purified bacteriophage MS-2 and poliovirus type I were prepared by standard methods in pellet form. The viral pellets were placed in samples of filtered well water. The virus-containing samples were then exposed to one of the following treatment regimens: (1) no added disinfectant, i.e. untreated control; (2) low levels of free chlorine; (3) a combination of copper: silver with free chlorine; (4) copper: silver ions without chlorine; or (5) either copper or silver without chlorine. Experiments were performed in duplicate at room temperature. Linear regression analysis was performed to calculate the viral inactivation rates for each treatment regimen.
RESULTS: The bacteriophage MS-2 inactivation rate for copper alone was significantly higher when the concentration reached 400 ug/liter. The MS-2 inactivation rate for electrolytically generated copper and silver ions together was greater than for either metal alone, suggesting an additive effect. Although not significant for very low levels of chlorine, the addition of 0.3 mg/liter of free chlorine to a 400/40 ug/liter copper/silver regimen significantly enhanced MS-2 inactivation rates.
Similarly for poliovirus, the activation rates achieved with the 400/40 copper/silver regimen were significantly greater as compared with untreated controls. The number of poliovirus were reduced approximately 2.5 log 10 within 72 hours. The addition of 0.3 mg/liter of free chlorine again improved the inactivation rates achieved, although in this case the improvement did not reach statistical significance. Poliovirus showed greater resistance to inactivation by any means tested than did bacteriophage MS-2.
CONCLUSIONS: Electrolytically generated copper and silver ions demonstrate efficacy against bacteriophage MS-2; further improvement occurs with the addition of reduced levels of free chlorine. The same regimen is capable of inactivating an enteric virus such as poliovirus in the presence or absence of free chlorine. The same regimen is capable of inactivating an enteric virus such as poliovirus in the presence or absence of free chlorine. Therefore, a regimen in which copper: silver ion treatment is combined with low levels of chlorine should prove useful as a method of disinfecting water against viral contamination.
The following is a synopsis of medical, and scientific professional quotes on the effectiveness of this technology.
Routine Surveillance and Electronic Liquid Purification Systems Prevent Outbreaks “The continued control of legionella by electronic ionization is due to the penetration of the copper and silver ions into the biofilms of the water distribution system killing the organisms. – Cu/Ag ionization systems have proven to be the most effective method for control of legionella in water distribution systems.” Infection Control Today 2000
Efficacy of Copper & Silver Ions
SWIMMING POOL DISINFECTION
An Evaluation of the Efficacy of Copper:Silver Ions
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Abstract - Electrolytically generated
copper:silver ions were evaluated as
an alternative disinfectant to high
levels of chlorination in swimming
pools. Pure cultures of Escherichia coli
and Streptococcus faecalis were
individually tested by Inoculating
autoclaved well water with and without
0.20 mgILfree chlorine. Copper:silver
ions in combination with free chlorine
reduced bacterial numbers more
rapidly than chlorine or copper:silver
ions alone. Numbers of S. faecalis also
were reduced more In the combined
system than In the system containing
only free chlorine when exposed for
0.5 min. The addition of copper:silver
ions allowed concentrations of free
chlorine to be reduced to 0.20 mgll
while still being able to meet guidelines
for commercial swimming pool
disinfectants.8
,81nthe United States, 95 percent of
water disinfection is achieved using
chlorine.Chlorineroutinelyis addedto
swimming pools to achieve
concentrationsof 0.6 - 1.0 mgIL free
availablechlorine.Noticeablechlorine
odor usuallyoccurs at concentrations
greater than 0.6 mg/L. High
concentrationsalso may also cause
irritations of the eyes, mucus
membranes and skin, creating
considerable discomfort for swimmers..
8 As alternative to chlorine compounds,
electrolyticallygenerated copper and
silver ions have been introduced
recently as a relatively safe and
odorless method for water
disinfection. ·
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Both copper and silver are bactericidal
and virucidal and copper has been
shown to be algicidal and possess
fungicidal properties.
1n experiments using standard
procedures, E. call numbers were
more effectively reduced by the
combination of copper:silver ions and
free chlorine than with free chlorine
alone. In the copper:silver ions with the
free chlorine system, the numbers of
E. coli were reduced 3.5 log 10 in 0.5
minutes. The system containing free
chlorine alone inactivated E. coli
numbers 2.8 log 10 in 0.5 minutes.
The levels of copper and silver to be
used in swimming pools apparently
would not pose any health risks.
Standards for copper levels in drinking
water were established more for
aesthetics than for health concerns..
"The use of copper and silver with low
levels of chlorine as a method of
commercial swimming pool
disinfection, thus, should greatly
outweigh the negative aspects of high
level chlorination, such as eye and skin
irritation.·
"The data obtained indicate that a
system of electrolytically generated
copper:silverions with concurrentlow
level of free chlorine in water appears
to havean enhancedeffectin reducing
microbial numbers. This would allow
the level of chlorine currently
recommended for commercial
swimming pools to be reduced.
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Journal of Environmental Health Volume 51, Number 5
US SURVEY OF HOSPITALS USING COPPER-SILVER IONIZATION FOR THE CONTROL OF LEGIONELLA
September 26-29, 2000,
Janet E. Stout, Y.E. Lin, V.L. Yu
VA Medical Center, Pittsburgh, PA
and the University of Pittsburgh, Pittsburgh, PA
Despite documentation of its efficacy in numerous hospitals, the long term efficacy of copper-silver ionization for controlling Legionella pneumophila in hospital water distribution systems has not been well documented. We conducted a survey of the first 13 hospitals in the U.S. that had implemented copper-silver ionization systems on their hot water systems for Legionella control. The mean bed size was 434 (range 150-700), 61% (8/13) performed transplant operations. 100% (13/13) had diagnosed cases of nosocomial Legionnaires' disease (LD). 30% of the hospitals installed copper-silver ionization because of problems and expense associated with the prior use of hyperchlorination. 50% had previously used thermal eradication. The average number of ionization flow cells installed per hospital was 3.4 (range 1-7), and the average start-up cost was $86,432. 46% (6/13) of hospitals had >30% of distal outlets positive before using ionization, and 0% had > 30% positive after installation. For 46% (6/13) of the hospitals, distal site positivity decreased to 0% positivity. When we conducted the survey, the ionization systems had been in place from 1 to 4 years. Ionization requires regular maintenance and the pH of water should be < 8.0 for optimal performance. Ionization is a viable option for controlling Legionella in hospital water distribution systems.
5th International Conference on Legionella
September 26-29, 2000, Ulm, Germany
Janet E. Stout
Infectious Disease Section,
University Drive C
Pittsburgh PA 15240 USA
Disinfection of Bacteria In Water Systems by Using Electrolytically Generated Copper: Silver & Reduced Levels of Free Chlorine
AUTHORS: Yahya MT, Landeen LK, Mesina MC, Kutz SM, Schultze R, & Gerba CP
PUBLICATION REF: Canadian Journal of Microbiology 36: 109-116, 1990
PURPOSE:
The recommended minimum level of free chlorine for disinfection of public swimming pools is 1 mg/liter. This level is difficult to maintain due to the chlorine-demanding organic material introduced by bathers themselves as well as the environment. Eye and skin irritation may also occur at the minimum chlorine level needed for effective disinfection. Electrolytically generated copper/silver ions are also microbiocidal and are much less subject to degradation but are slower acting than chlorine. Therefore, the authors tested the hypothesis that using the two methods together would accomplish effective disinfection while reducing the level of free chlorine required.
MATERIALS AND METHODS:
Two 32-gallon plastic containers, one indoors (temperature range 22 to 25) and the second outdoors exposed to sunlight (temperature range 18 to 36) were filled with tap water. After chemical analysis and adjustment of pH and test levels of disinfectants, bath water and urine were added to stimulate typical swimming conditions. Four treatment regimens were tested: (1) No added disinfectants (2) Free chlorine alone at the generally recommended level of 1 mg/liter (3) Free chlorine at 0.3 mg/liter combined with copper and silver ions at a ration of 400 ug/liter of copper to 40 ug/liter of silver (4) Copper and silver ions alone at the same ratio as above. An isolate of Staphylococcus sp was employed for bacterial challenge testing since previous work had shown that staphylococci are more resistant to disinfection than are coli form bacteria. The experiment was continued for 12 weeks.
RESULTS:
In the test of free chlorine alone, location proved to be critical. In the outdoor setting subject to strong sunlight and high temperatures, no residual chlorine could be detected 3 to 4 hours after optimization. Indoor, where environmental factors were much less extreme, a residual level of 0.1 to 0.3 mg/liter was found after 24 hours.
Bacterial counts were kept within drinking water standards (as recommended for swimming pools) by either high levels of chlorine alone or by the combination regimen of copper and silver ions with low levels of chlorine: the difference in total bacterial numbers was not significant. Hen challenged with Staphylococcus sp isolate, the combination of copper and silver ions with low levels of chlorine achieved a 2.4 log 10 reduction in bacterial numbers within 2 minutes, while the single-agent regimes (free chlorine alone, or copper/silver alone) showed only 1.5 & 0.03 log 10 reductions respectively. Under Staphylococcus sp challenge, the combined copper/silver and free chlorine had a faster log 10 reduction of microbial numbers than did treatment with a high level of chlorine alone.
CONCLUSIONS:
The addition of electrolytically generated copper/silver ions in the radio tested (400 ug/liter copper to 40 ug/liter silver) allowed reduction in the concentration of free chlorine to one third of the level customarily recommended. The use of copper/silver may provide resisting protection in swimming pools after chlorine has been rendered ineffective due to contamination from swimmers and the natural environment.
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Excerpts from the University of
Arizona Department of
Microbiology and ImmunologyLab
Reports.
Metals for use in disinfection have
been documented for many years,
although they have only been in use
as electrolytic devices in the United
States since the early 193O's.8
8Free-chlorine concentrations can be
affected by sunlight, temperature,
organic materials and the chemical
consistency of the water. Organic
material may be introduced into
swimming pools by rain drainage, soil,
foliage and animals. Swimmers can
also contribute large amounts of
organic matter to pool water in the
form of sweat and urine. Active
. swimmers can perspire up to 1LJhand
the average swimmer can contribute
25-50 mL of urine. All of these factors
have a chlorine demand and act to
lower the levels of free chlorine in the
water. This poses one drawback to the
use of chlorine as a swimming-pool
disinfectant. Other negative aspects
Include eye and skin imtation, low
residual effect and the formation of
trihalomethane compounds which can
be absorbed through the skin or
volatilized and inhaled. For these
reasons, alternative disinfectant
systems have been investigated.
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A letter quoted from Dr. Charles
Garba University of Arizona:
During our experiments we paid
particular attention to the efficacy of
copper:silver ions against J.agiooejla
pneumopblla. Our experiments have
proven that copper:silver ions
combined with very low levels of
chlorine produces a synergistic effect
which enables the dual disinfectants to
kill ~ bacteria much more
Rapidly and is up to 1000 times more
effective than chlorine alone.8
The additional benefit of the
copper:silver system is that there is
always a disinfectant in circulation that
is unaffected by sunlight and
temperature and, in fact, the
bactericidal effect is enhanced by
sunlight and high temperatures.8
J.agiooejlapneumopblla is resilient to
high levels of chlorine and is a most
difficult bacteria to eliminate, especially
within systems that are exposed to
sunlight and temperature such as
cooling towers and hot water lines
where levels of chemical biocides are
difficult to maintain, and in most cases,
non-existent due to dissipation. This
breakthrough in water purification
means that the combination now
produces a far more effective constant
disinfectant against L.e.giQruilla
pneumopbHa and other chlorine
resistant strains of bacteria. These
systems are automatic and are easily
monitored once they are installed.
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