Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates generally to the disinfecting of
drinking water by use of apparatus making use of silver ion as a disinfecting
agent.
It has been known that silver ion has a disinfecting effect upon ; -~
organisms commonly found in drinking water. However, simple apparatus and
methods making use of silver ion a~d applicable to drinking water dispensers
have not been generally available. This is attributed to inability of prior
apparatus and methods to maintain an effective silver ion concentration over
extended periods of time, cost of the apparatus or devices required, the
nature of the apparatus and devices which have required changes in convention-
al dispensers, and inability to control the ion concentration between desired ~ :~
levels. Among the apparatus and devices employed for making use of silver
ion for water disinfection, reference can be made to filters having porous ~ -
filter mediums ~e.g.J ceramic or carbon) containing metallic silver, electro-
lytic cells for generating and introducing silver ion into water flowing
through the cell, and silver-plated or silver-containing coatings on bodies
in contact with the water. Such apparatus and devices have not provided
simple means applicable to conventional water dispensers capable of develop-
ing and maintaining a silver ion concentration to an effective level for
disinfection.
In general it is an object of the present invention to provide a ;
water dispensing apparatus having means capable of disinfecting and main-
taining drinking water in a sae condition. ;` ~ :
Another object is to provide a dispensing apparatus having a water ~ :
disinfecting capsule in the form of a ceramic body which contains dispersed
metallic silver and which is incorporated in the apparatus in such a manner ~ ,
that it is immersed in the water whereby silver ion is released in a con-
trolled manner ~o provide a level of silver ion concentration effective to
disinfect and to maintain the water disinfected. '
In general the invention consists of water dispensing apparatus ~-
comprising a container for storing water and a vessel below the container
having an upper open end adapted to communicate with the lower open end of
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the container. Means ~e.g.~ a faucet) is provided for dispensing water from
the vessel. There is an upwardly open basket generally surroundlng and
extending below the lower open end of the container which has openings for
flow of water from the interior of the same into the vessel. A ceramic body is
disposed within the lower portion of the basket below the lower open end of
the container, and this body is immersed in the water within the vessel.
The body is formed of porous ceramic material having a metallic silver
dispersed within the same and adapted to absorb water through its exterior
surfaces and retain absorbed water in static condition within the body, the
basket and the ceramic body being so disposed as to cause water to flow from
the container downwardly tcward and in contact with surfaces of the body and
through the openings in the basket when water is dispensed from the vessell.
Preferably the ceramic body is provided with ribs on its lower side which -support the body in spaced relationship with adjacent surface of the basket.
Also the body preferably has a hole extending through its central portion. ~; ,
Additional advantages and features will appear from the following
description in which the preferred embodiments have been set forth in detail
in conjunction with the accompanying drawings.
In the drawings:
Figure 1 is a side elevational unit of a conventional olla dis-
penser with a capsule made according to the present invention installed
therein;
Figure 2 is an enlarged detail in section illustrating a suitable
positioning of the capsule within the olla dispenser;
Figure 3 is a side elevational view illustrating a suitable form
for the capsule; `~
Figure ~ is a plan view of the capsule shown in Figure 3;
Figure 5 is a diagram illustrating steps in a method for manufacture
of the capsule.
The drinking water dispenser illustrated in Figure 1 consists of
a container 10 which may be enclosed within a housing or shell 11 and may be
made of suitable material, such as glass~ plastic, stainless steel or
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ceramic. Its lower portion is in communication with the dispensing
faucet 12. It has a relatively wide opening 13 in its upper end. A contain-
er 14, which generally is in the form o~ a bottle made of glass or suitable
plastic, is inverted and supported upon the upper end of the container 10, - ~ ;
with its neck 15 extending through the opening 13. A
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basket 16 also is disposed within the opening 13, and is
provided with a skirt or flange 17 which is interposed
between the lower end of the bottle 14 and the upper end
of the container 10. ~he bas]cet is generally annular in
horizontal section and is provided with openings 18 through
which water may pass from the interior of the basket into
the container 10.
Supported within the basket and disposed beneath -
the lower o~en end of the hottle neck 15, there is a capsule
19 as shown in Figur s 3 and 4. The capsule consists or a ;~
body 21 of porous ceramic material, made by a method as ~,
presently explained. The porosity of the body is such that A~
when it is immersed in water, a substantial amount of water ,
is absorbed within the pores of the body by capillarity. ;~
The functioning of the capsula is not critical with respect
to its form or configuration. As illustrated the body is
annular as viewed in plan. Its upper side is concave, and
its lower side convex. Stated another way, it is in tha
form of a shallow cup, with the vertical thickness of the
body increasing from the perimeter toward its central ~ortion.
The sides and lower surfaces of the body are shown provided
with integral ribs 22. The purpose of theqe ribs is to
provide a support upon the underlying surface of the basket
16, whereby spaces are provided between the body of the cap-
sule and the adjacent surfaces of the basket to permit thefree access of water. ~he central portion of the body is
shown provided with a duct or vent 23 which serves to prevent
an~ entrapment of air immediately above or below the body.
A desLrable method for manuacturing the capsule
is outlined in Figure 5. The principal ingredient is a
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relatively pure form o~ kaolin or clay. As indicated in
step 26, a sufficient amount of water and silver compound
is mixed with the kaolin to ~orm a mixture of proper
moldable characteristics. To facilitate the smoothness ~,
and moldability of the mix, a small amount of clay is added
of a type which swells when ~etted, such as bentonite. In
the mixing operation the silver solution is uniformly ,~,
distributed throughout the mass. The mix is then introduced
into suitable molds in step ~7, such as molds capable of
producing the configuration shown in Figures 3 and 4. The
dimensions of the mold cavity are such as to produce the
desired dimensions after shrin~age during subsequent treat- '
ment. The molded forms are then subjected to drying 28 to
reduce the moisture content and to provide forms having
sufficient strength for subse~uent firing. In general, it
is satisfactory to reduce the moisture content to less than
1~ in step 28. ~he dried forms are th~n fired in a suitable
furnace as indicated in step 29, Wit}l the temperatures and
times being controlled to prevent glazing. By way o
example, the total firing time may be of the order of 12 `~`
hours, including initial heating from arnbient temperatura
up to a firing temperature of 1900F., holding this ' ' ,
temperature for about 2 hours, and then permitting the '~
capsule to cool to at or near arnbient temperature for an ''
additional 12 hours. In addition to providing a capsule of '~,'sufficient structural strength for use in the manner ' ,previously described, firing to such temperatures causes
reduction of the silver compound to form metallic silver, ,'` ;
with the metallic silver bei~g relatively uniformly dispersed ~ '
in the porous ceramic body. ' ~ ,
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~1hile adding the si.lver solution in step 26 is .. .
preferred it is possible to immerse the dried capsule in
the silver 301ution after drying in step 28 to eEfect
absorption into the interior of the body. In this event .
further drying is required before firing.
With respect to the composition of the kaolin
or clay employed, the mix may contain 90~i of a relatively ,~
pure ~orm of kaolin, and 10% of bentonite clay. A typical
analysis oL such a mix is as follows: ~
~ ~ 3 37.3~ :
SiO~ 46.9
2 3 0 7 '~`
CaO 0.06 ;
':'
0~2
KO~l ~ Na20 0 4
TiO2 1.4
so3 0.1 .
P205 0,06 ~-
Ignition loss 12.87
The kaolin used in preparing the above mix by
itself analyzes as follows:
Al23 39,21%
Si2 ~.95~ .
~e23 0.49~
CaO 0.06% .
MgO 0.04~i -
I~OI~ ~ Na20 0.13
TiO2 1.51~
S03 0.01~ .
25 0~07% .
: .
Ignition loss 13.57%
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With respect to the silver compound employed, it
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is desirahle to employ a compound which has good solubility
in water, such as silver nitrate, silver acetate, silver
chlorate, silver lactate, or silver picrate. ~ikewise, all -
of these compounds or salt~ are reduced at a temperature
of the order of 1900F. to provide elemental or metallic
silver. Other silv2r salts are likewise reduced at a
temperature of the order of 1900F., but have relatively
low solubility compared to the salts previously mentioned. ~;
In this connection reference can be made to such compounds
or salts as silver bromate, carbonate, chromate, citrate,
iodate, nitrite, oxide, perchlorate, permanganate, phosphate, ~:
selenate and sulfate. In the event such silver compounds
are used they mav be introduced into -the mix in finely
powdered form, or as a slurry.
A convenient size for a cap~ule having a
con~iguration like Figures 3 and 4 i5 one having a volume ;
of 3.66 cubic inches (60 ml) with a weight of 3.46 ounces '"~
~8 grams). When constructed in the manner described with
reference to Figure 5, the capsule will absorb about 24
grams of water. Good results are secured when such a
body contains about 2.0 grams of metallic silver, which
is the amount of metallic silv~r provide.d by 3.15 grams o `~`
silver nitrate added to the mix. The effectiveness of the
capsule does not appear to be highly critical with respect ~
to the amount of metallic silver in a capsule of given ~ ~`
weight. Good results are obtained when the capsule contains ~!,'.
an amount of metallic silver ranging from 1.5 to 3 grams
of dispersed silver for a capsule weighing about 100 grams.
The amount of metallic silver can be increased in
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proportion to an increase in the weight of the capsule.
When a capsule constructed as described above is
.
introduced into a dispensing unit of the type shown in '~
Figure l, with the capsule being positioned in the basket
16 and below the open end of the bottle neck 15, it
immediately ahsorbs a substantial quantity of water because
of its porosity. The absorbed water being in intimate
contact with the metallic silver dispersed in the capsule ~
causes the release of silver ion into the absorbed water, ~ -
and silver ion from the absorbed water is thereby dispersed
into the surrounding water. Within a relatively short ;~
period of time, the ion thereby released finds its way into
the body of water within the bottle 14 and the container 10,
with initial creation and subsequent maintenance of a silver ~,
lS ion concentration within the entire body of water which is
capable of inhibi~iny the growth of bacteria and other
microorganisms. In general, the silver ion concentration
within the main bocly of water is maintained with a range
of about 10 to 30 parts per billion (ppb), which is
effective to control growth of any organisms present in a
good quality drinking water, and to ma.intain such water
safe in a dispensing unit.
While a capsule made as described ahove serves to
maintain an effective level of silver ion in various types
of water, it is considered to be particularly effective and ;;
desirable when used in connection with drinking water having
not more than 150 ppm of dissolved 501icls. It has been
observed that when the amount of dissolved solids in the
water increases beyond 150 ppm, the effectiveness of the ;
capsule in disinfecting the water appears to be impaired. '
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The capsule described above has a relatively
long useful life. For the periods in which the capsule
has been used under test conditions, no impairment in
activity has been noted. Judged by such experimental use,
it is considered that the useful life of a capsule is well
over one year. ~ `
~ t is advisable to periodically clean a capsule
to remove any surface deposits. Any such deposits can be
readily removed without impairing the effectiveness of the
ca~sule slmply by washing off the surface with the aid of
a brush. `
An example of the invention is as follows: -
Example
The kaolin used was ona sold under the trade
lS name of Kaolex. 10~ of bentonite was added to the kaolin. ,~
The resulting dry mix analyzed as specified above by way
of example. An 8.5% silver nitrate solution was added to
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the mix to form a mass of moldable consistency. The mold
was constructed to orm a capsule shaped as in Figures 3 '~
and 4. After molding, the molded body while within the
mold was dried in a hot air oven over a period of 24 hours
to eliminate substantially all of the moisture. The green
clay body was then placed in a kiln and fired to a tempera-
ture of about 1900F. ~he total ~iring cycle was 12 hours,
including an initial period for heating from ambient to
1900F" holding at that temperature for 2 hours, and then
cooliny ~or an additional 12 hours. The body of the capsule
measured 2-3/4 inches maximum diameter and l inch in height,
with ribs 1/4 inch wide and projecting l/8 inch from the
body. The body at its perimeter (upper edge) was about
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1/16 inch thick, and 9/16 inch thick at its central portion.
The volume of the capsule was 60 ml (3.66 cu. inches) and
the weight was 93 grams. When immersed in water, the water
a~sorption was 24 ml. The amount of metallic silver was
2.0 grams, resulting ~rom the reduction of 3.15 grams
silver nitrate.
Tests were made to détermine the effectiveness
of the capsule in inhibiting bacterial growth. Fifty
drinking water dispensers of varying types (12 of the
hot/cold water type, 4 of the type provided with electrical
coolers, and 9 of the simple olla type~ were each equipped
with a capsule made as described above. At regular
intervals (once each 7 days) over a total test period
of 45 days, samples were taken from the reservoir and
faucet of each dispenser and were read at 24 hours and
5-7 days of incubation. It was found that the control
of bacteria ranged from 96.1 to 9S.7%, compared to bacteria
present in the same types of dispensers operating without
the capsule. The same test was carried out ~ith a capsule
of aqual size and weight but containing 1 gram of silver.
This gave. bacteria control over a range of 92.7 to 96.3~.
The water used in both of the above tests was
good quality drinkiny water having ~ess than lS0 ppm
dis301ved solids in the form of mineral salts.
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