Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using disinfecting or sterilizing substance
Reexamination Certificate
2001-03-13
2003-10-07
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using disinfecting or sterilizing substance
C210S757000, C210S758000, C210S763000, C210S764000, C424S489000, C424S635000
Reexamination Certificate
active
06630106
ABSTRACT:
BACKGROUND
1. Field of the Invention
This invention relates to compositions and methods for controlling the growth of microorganisms and other contaminants in water processing systems, including, but not limited to, ice makers, water coolers, refrigerators, water filtration devices, cooling towers and water reservoirs. The compositions and methods of the present invention reduce the presence and/or inhibit the growth of microorganisms, such as fungi, algae, spores, molds, mildews, protozoa, bacteria and other contaminants of water processing systems. The composition contains a solid metal oxide which is at least partially immersed in a reservoir of the water recirculation system.
2. Description of the Related Art
Equipment used to process and store water often supports heavy growth of microbiological contaminants, such as bacteria, fungi, algae, spores, molds, mildews, and an assortment of other microorganisms. The presence of such contaminants in significant quantities is undesirable and creates unhealthy conditions in equipment used to process water for everyday use or consumption by humans, raising potential health code violations. Moreover, in equipment for processing non-potable water, such as cooling towers and water chillers used in cooling systems, overgrowth of contaminants can lead to fouling of process equipment, causing decreased efficiency and corrosion.
The site and identity of the contaminating growth may depend upon the particular chemistry of the water in the system, as well as upon the contents of the air near the water processing system. For instance, ice makers and water coolers located in bakeries, delis and other establishments having bread-making and other baking operations often suffer from heavy microbial growth covering up to 80% of the surface area of the equipment possibly due to the high quantities of airborne yeast in these environments which can get transported into the water processing system. It has also been noted that ice makers and water coolers located near copy machines tend to suffer from increased microbial growth. This is believed to be related to the presence of volatile organic substances used in the copying process and which are carried through the air to the water systems and provide nutrients the microbes.
Although attempts have been made to deal with the problem of overgrowth of such contaminants in water processing and holding systems, no successful remedy has been discovered. A traditional treatment for water contamination involves sterilizing the water with chemicals before it enters the processing equipment. This method has proven unsuccessful, because the contaminants generally grow on the surfaces of the equipment itself; thus, the sterilized water becomes contaminated again when it enters the process equipment. Cleaning the water prior to putting it into a contaminated system thus does not, significantly reduce the contamination of the water output. Additionally, the sterilized water does little to reduce the microbial build up already present in the system since the level of any antimicrobials in the water is generally not sufficient to reduce or destroy an established microbe infection in the equipment. The equipment can be disinfected prior to addition of the treated water; however, the cleaning process generally requires shutting down the system for long periods of time during the cleaning. Also, many contaminants are airborne and, as such, may enter the equipment after the pre-treated water has been added, and after cleaning has occurred.
Other prior art treatments include the use of chlorine as a disinfectant. Chlorination disinfects the water and equipment, but it also causes the equipment to corrode. In ice makers, the chlorine in the water becomes incorporated into the ice, giving an unpleasant taste and odor to the ice. Attempts have also been made, primarily in Japan, to decontaminate the water with magnesium pellets and ammonia. Although this method cleanses the water of contaminants, use of these chemicals in drinking water in the United States is not yet authorized by the EPA.
Ultra violet lamps have also been placed in or near the reservoirs of water systems to generate ozone, which poisons the microorganisms. However, this method also has not proven capable of efficiently reducing the growth of contaminants for a sustained period of, time. Additionally, this technique does not appear to work well at low temperatures, which makes it an impractical solution to microbial overgrowth in water coolers, refrigerators, ice makers, chillers, and other water processing equipment affected by this problem. Finally, this technique requires the consumption of additional electrical power.
A common problem with all of the above techniques is that while they achieve partial reduction of some microorganisms, they do not have a wide effectiveness; i.e. they typically cannot both reduce bacterial contamination and also control the growth of spores, fungus and algae for more than a short period of time.
Another prior art technique involves impregnating plastic with biocides and using the treated plastic to form the reservoir and/or other parts of water processing equipment that suffer from microbial growth. This method has proven relatively ineffective at reducing microbial growth to a sufficiently low level of detection. Making the impregnated plastic also involves increased costs associated with customized production of the parts for each different system or application. This method presents an additional problem in that the parts are not easy to obtain or replace. As with all of the above-described prior art disinfecting techniques, this method is only mildly successful in reducing the growth of microorganisms. Over a period of time, new growth of microorganisms will become sufficiently well established that the colonies of organisms will become visible to casual inspection of the surface of the equipment.
Thus, what is needed in the art are methods and compositions for quickly and effectively reducing or eliminating the growth of various microorganisms in water processing equipment and holding tanks and maintaining the reduced-microbial environment for sustained periods of time. Preferably, the method should also be convenient and cost-effective.
SUMMARY OF THE INVENTION
The invention relates to methods and compositions for reducing the growth of microorganisms and other contaminants of water processing and holding systems. As used herein the term “microorganisms” refers to any microscopic organism, including but not limited to algae, fungi, bacteria, protozoa, mold, mildew, and spores.
In its broad aspects, the invention relates to placing an antimicrobial material in any area of water processing, cooling or holding equipment where there is water movement or water storage. More particularly, the antimicrobial material is placed in a water reservoir or holding or overflow tank of such equipment. Placing the antimicrobial material in the water reservoir, where it is at least partially immersed in the water, destroys contaminating microorganisms in the water and on the surfaces of the equipment in contact with the water. Water-borne or air-borne microorganisms that subsequently contact the antimicrobial material are also killed. When placed in water processing equipment, such as an ice maker, water filtration device, or water recirculation apparatus, placing the antimicrobial material in the water reservoir reduces the presence of the contaminants in the entire system.
The invention provides methods and compositions for significantly reducing the growth of undesirable contaminants in water processing and holding equipment. The invention further provides methods and compositions which work quickly and require little expense or maintenance.
In a particular embodiment, the antimicrobial material of the invention comprises a powdered or fumed metal oxide. The metal oxide can be formed into a shaped solid, or into granules, pellets, extrudates, or other solid forms. The metal oxide may include, but is not limited to, oxides of tit
Conley Sean E.
Gray Bruce D.
Kilpatrick Stockson LLP
Prutt John S.
Selecto, Inc.
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