Abstract:
A compact point of use water purifier intended for both urban and rural areas of developing countries. The purifier is a spigot with an integrated UV radiation source  18  adjacent to an outlet orifice  19  to selectively on demand expose untreated water when the spigot valve  15  is activated to dispense water for consumption. The valve includes a user-activated handle  154  and is configured such that upon initial movement of the handle the ultraviolet radiation source is activated and upon continued movement of the handle the valve is opened. The water purifier is connectable to an electric power source, either 110V/220V AC or 12VDC, via a transformer unit to deliver the appropriate voltage to the spigot unit.

Description:
FIELD OF INVENTION 
     This invention relates to water purification and more particularly to an apparatus for subjecting fluids to ultraviolet (UV) light. The apparatus may be used for water sterilization and is intended for point-of-use on demand application. 
     BACKGROUND OF THE INVENTION 
     In both urban and rural areas of developing countries, the main limitation for ensuring good quality drinking water to the population is the absence of what developed countries call “tap water”. 
     Urban areas of developing countries do not have access to continuous flow of water in their potable distribution system; instead, urban households receive only a few hours of water per day, and not every day. As a result, buildings in urban areas are equipped with storage tanks that are filled whenever there is flow in the municipal water pipes. Those tanks can be roof tanks or underground cisterns. They range in volume between 200 and 1000 gallons storage capacity. Therefore, in developing countries, opening a faucet means receiving water from a tank where water has been stagnant for a few days, possibly silted and contaminated with bacterial growth. 
     Consequently, most urban households in developing countries do not drink water from their faucets, they use it solely for washing, bathing, and sometimes cooking. For drinking, urban families purchase “purified water”, typically sold in 5 gallon jugs that cost around 1 dollar. The 5 gallon jugs are heavy and cumbersome and require some kind of dispenser for serving the water. Typical dispensers are either plastic or ceramic large-mouth containers, and 5-gal jugs are flipped 180 degrees on those containers so as to rest neck-down. The dispensers are equipped with a regular plastic spigot to conveniently serve water. From a study conducted in 2009 in a medium-size city of Mexico, namely La Paz, Baja Calif. Sur, it was determined that 95% of the 150 urban families interviewed were using 5-gal purified water jugs and dispensers in their households for drinking water. In the same study, water quality tests were conducted to measure concentration of bacteria, i.e. total coliform and fecal coliform bacteria, in both unopened 5-gal jugs and household dispensers. It was found that there was zero bacterial contamination in the 5-gal jug samples. However 26% of these spigoted dispensers had total coliform bacteria and 11% had fecal coliform bacteria in their drinking water. Dispensers therefore seem to promote recontamination of the water. Sources of recontamination include typical handling and transport of jugs. Purified water jugs are oftentimes delivered at the back of pick-up trucks, by a person carrying it on his shoulder to the house and placing it onto the spigoted dispenser. Dust and fumes during transport and unwashed hands while handling 5-gal jugs are therefore likely pathways for bacteria to reach the inside of the drinking water dispensers. 
     Having examined the water situation in urban areas of developing countries, it can easily be imagined how the problem is magnified in rural areas. There are no faucets and no water distribution infrastructure in most rural communities of the developing world. Water is carried from the wells or springs to the house in buckets or other containers. In the best scenario, there might be a hose or pipe conducting water by gravity from a spring or tank to communal faucets. In a study conducted in 2005 in Baja Calif. Sur with the National Water Commission of Mexico, samples of 500 water sources in rural communities and determined that 42% of them had fecal contamination. In the same study, samples were taken from 500 household water containers and found that 54% had fecal contamination. Household containers are indeed generally more contaminated than water sources in rural communities. Providing a “safe” water source is therefore not enough since rural families have no “tap water” and will continue to store water in unsafe containers. In another study of 30 existing water filters installed by aid agencies and non-profit organizations, it was found that 36% of water filters had total coliform bacterial contamination in the stored filtered water, one of the filters actually having had a higher bacterial concentration in the filtered water compared to the source water. This can be explained by lack of maintenance and cleaning of the filter, poor hygienic conditions in the households such as dirt floors and dusty homes, handling of filters with unwashed hands, and presence of animals in the households (for example, a chicken sitting on top of a bucket water purifier). 
     From the foregoing description of the water situation in developing countries it can be concluded that safe drinking water can only be provided at the point-of-use. But that is not enough, because point-of-use water filters, if they involve storage of the filtered water, can themselves become contaminated. Safe drinking water therefore requires not merely point-of-use purification, but actually no-storage instantaneous point-of-use purification. This is the main motivation beyond the here-presented invention. 
     Prior point-of-use water purification devices for developing countries typically involve storing filtered water within the device, such as the various types of ceramic pot filters and ceramic candle filters (Potters-For-Peace, Katadyn) which are prone to recontamination of the filtered water, especially if adequate maintenance is not provided to the filter after a few months of use. The germicidal chemicals used in ceramic filters, typically iodine or silver, are lost after a year of use, but users have no way to know when replacement of the ceramic element is necessary, they therefore continue using their device for many years. This leads to the filter being a source of contamination instead of a means of sterilization, as was observed during the aforementioned water sampling campaign, where filtered water had sometimes more bacteria than the source water. 
     Boiling is another typical means of sterilizing water, but the boiled pot of water left standing in the kitchen is used by family members throughout the day, and water is retrieved from the pot by dipping cups which leads to quick recontamination of the boiled water. A simple experiment was conducted in a rural household of Mexico to measure the recontamination time for boiled water: at 10 am, a pot of water was boiled and a sample was taken to ensure it had zero bacterial contamination; samples were then taken every 30 min, and it was observed that recontamination by bacteria occurred at the fourth sample, i.e. at 11:30 am. Only one hour and 30 minutes was necessary to recontaminate boiled water left standing in a kitchen in a typical rural household scenario. 
     Chlorine or iodine drops are another means of sterilizing water in developing countries. Chemical disinfection is difficult to implement at the household level, since rural families strongly reject the taste of those disinfectants described as unhealthy to ingest. Short shelf life of those disinfectants require frequent buying which is oftentimes impossible for isolated communities, who prefer to spend the few dollars of their monthly budget on food and other items. 
     Other devices have employed ultraviolet light to sterilize water for use in developing countries, such as the UV water purification system described in U.S. Pat. No. 7,361,904 and the UV water disinfector described in U.S. Pat. No. 5,780,860. The former presents a major problem observed during monitoring of 1,500 units installed in rural Mexico between 2006 and 2008. The disinfection chamber is prone to silting since fine sediments contained in water accumulate over time and grow to a thick “mud-type” layer. Water passing in the bottom chamber is therefore not sterilized properly by UV radiation source since bacteria can easily hide in between mud particles before reaching the outlet where the user obtains water. Observation of the use of the aforementioned UV water purification system led to the conclusion that a water sterilization device intended for developing countries cannot rely on maintenance performed by a user, since many users will not clean or maintain their water sterilization device, at least not as expected by the inventor of the device. The UV water disinfector described in U.S. Pat. No. 5,780,860 is another sterilization device intended for use in developing countries at the village scale. The major issue with village-scale sterilization devices is recontamination of the water during transport and storage. Villagers will walk a certain distance to the location of the sterilization system to obtain water, or will have someone deliver sterilized water to their homes. But if sterilized water is transported or stored in unclean containers, or if water is retrieved by dipping cups where hands can come in contact with sterilized water, there is a significant risk of recontamination within a few hours of obtaining sterilized water. 
     Other devices using ultraviolet light to sterilize water have been invented for use in modern homes of developed nations. The UV water purifying devices described in U.S. Pat. Nos. 6,909,101; 5,843,309; and 4,280,912 are faucet-type UV sterilizing systems. These devices are specifically manufactured for developed country household plumbing systems and would not be easily adapted to rural households in the developing world. These devices also have elongated conduits between the UV radiation source and the water outlet which can promote growth of bacteria between each use. Droplets of water remaining in the conduit between the UV sterilizing chamber and the water orifice can promote bacterial growth which would not be sterilized by subsequent uses of the device. Other UV sterilizing devices are counter-top water purification devices such as those described in U.S. Pat. Nos. 6,451,202; 6,726,839 and 5,445,729 involving multiple steps of filtering and sterilizing with a UV radiation source prior to dispensing at a spigot. Those units are complicated and costly, typically in the hundreds of dollars, and they are therefore neither affordable nor easily serviceable by families in developing countries. The counter-top units pose the same problem as the faucet-type ultraviolet systems described above, because they also possess an elongated conduit between the UV sterilization chamber and the water outlet which creates a potential recontamination hotspot that is not easily accessible for cleaning between each use. 
     The present invention is a simple, compact, affordable, maintenance-free and recontamination-free ultraviolet purification spigot that resolves many of the challenges observed in other water purification devices intended for developing countries. By placing the UV light immediately adjacent to the outlet orifice of the water, there is no recontamination risk along conduits or in storage units and the user is able to sterilize just the amount that is needed, be it a glass of water to drink or a pot of water to bath a child. The small size of the device is an essential characteristic of this invention which will greatly enhance its distribution potential in rural areas of developing nations as hardware stores in villages or county capitals will be able to carry this device in their inventory among other similar-sized items such as bulbs, batteries, and flashlights. This will eliminate the need for humanitarian-type distribution schemes by governments, aid agencies or non-profit organizations which are generally one-time campaigns that do not establish distribution channels for long-term supply of replacement parts. As a final note, the present invention provides a great opportunity for creating a national water solidarity campaign between urban and rural areas. Such a campaign can be conceived such that, for every UV spigot sold in urban markets, one UV spigot can be subsidized for a rural family. 
     SUMMARY OF THE INVENTION 
     It is an aspect of the present invention to be able to inactivate all viruses, bacteria and parasites from untreated water in minimal exposure time to UV radiation. 
     It is another aspect of the present invention to expose the untreated water to UV radiation at the point of delivery to preclude the build-up of viral, bacterial and parasitic contamination in the dispenser and such contaminants from entering the dispensed water. 
     It is yet another aspect of the present invention that a water purifier employing a UV radiation source inside a spigot to germicidally treat water in a chamber adjacent to outlet orifice is provided and is especially suited for point of use on demand supply of purified water in urban and rural areas of developing countries. 
     It is a feature of the present invention that the UV radiation is supplied adjacent to the point of delivery of the water from the dispenser. 
     It is another feature of the present invention that the treated water is dispensed through a spigot that houses the UV radiation source. 
     It is still another feature of the present invention that a control valve selectively controls the flow of untreated water from the inlet of the spigot attached to any suitable container to the ultraviolet treatment chamber and that the control valve activates a switch that supplies electricity to the UV radiation source so that the ultraviolet bulb outputs germicidal light only when the spigot is in use and water flows around it to the outlet orifice. 
     It is a further feature of the present invention that it can be connected to either 110 VAC, 220 VAC or 12 VDC power source by means of transformer and ballast circuitry to supply the adequate starting and running voltage to the UV bulb. 
     It is yet another feature of the present invention that the UV radiation source is a filament-type ultraviolet lamp which allows the lamp to illuminate immediately when electrical contact is made. 
     It is an advantage of the present invention that the dispensed water is purified in about a second exposure time to the UV radiation source. 
     It is another advantage of the present invention that contaminants in the reservoir or water delivery device are eliminated via the UV radiation prior to exiting the spigot at the point of use. 
     It is yet another advantage of the present invention that the circuitry can be housed at a location distant from the device, optimally in a wall adapter unit at the electrical outlet. 
     It is a further advantage of the present invention that the compact filament-type ultraviolet bulb employed in this device allows for a low starting and running voltage, respectively around 14V and 10V, which is a standard safe voltage for household appliances coming in contact with water such as coffee makers and blenders. 
     It is still another advantage of the present invention that it is low-cost, maintenance-free and will only require easy replacement of the complete spigot unit every few years when the ultraviolet bulb burns out as easily noticed by user thanks to a viewing window on spigot. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects, features and advantages of the invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the following drawings wherein: 
         FIG. 1  is a general view of water purifying spigot unit; 
         FIG. 2  is a cross-sectional view of the water purifier showing from left to right threaded attachment for spigot unit to be mounted on any suitable container, valve seal and valve mechanism and UV treatment chamber adjacent to outlet orifice for dispensing water; and 
         FIG. 3  is a general view of the water purification spigot unit when connected to power supply unit. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The UV water purification spigot, indicated generally by the numeral  10 , as seen in  FIG. 1  and more specifically in  FIG. 2 ; consists of a threaded inlet conduit  11 , a valve mechanism indicated generally by the numeral  15 , a disinfection chamber  17  containing an ultraviolet bulb  18  and an orifice outlet  19  through which a user gets disinfected and germicidally treated water. 
     The threaded inlet conduit  11  is a ¾ inch outside diameter conduit designed to be attached to any suitable container (not shown), provided such container has a matching ¾ inch hole where threaded conduit  11  can be inserted and attached safely by using the two gaskets  12  and  13 . Gasket  12  is designed to be placed on the outside wall of the container while gasket  13  is placed on the inside wall of the container. Threaded nut  14  pressures gaskets  12  and  13  to ensure spigot  10  is tightly held to container while gaskets  12  and  13  provide a secure seal to avoid water leaks from container. The untreated water flows in spigot  10  through conduit  11 . 
     The flow of water is controlled by a valve mechanism indicated generally by numeral  15  comprising a conical rubber seal  151 , a tapered spring  152  to exert pressure on conical rubber seal  151 , a plunger  153  attached to a handle  154  that is activated by a user by either pushing or pulling on handle  154  to raise rubber seal  151  to let untreated water flow to entrance conduit  16 . A gap  156  between plunger  153  and rubber seal  151  allows plunger  153  to raise 2 mm vertically to release pressure on lever  26  and unactivate button of microswitch  22  to turn on ultraviolet bulb  18  before engaging seal  151  which opens the flow of water to conduit  16 . This built-in delayed valve opening mechanism ensures that lamp  18  is illuminated before water enters conduit  16  prior to reaching disinfection chamber  17 . Prior designs allowed some water to pass out through the spigot before the lamp irradiated it. Afore-mentioned design now retains the water until the lamp is illuminated and the plunger is raised to engage the seal and release the water out through the spigot orifice. 
     Handle  154  can be pushed down or can be raised all the way to sit in a vertical position where it can rest without exerting pressure on it. Slight downward push on handle  154  when resting vertical returns it promptly to its horizontal position thanks to action of spring  152 . Handle  154  is free to rotate horizontally around plunger  153  to any position within an approximate 180 degree radius limited by the wall of a container (both not shown) where spigot  10  is attached. When valve  15  is open, water flows to conduit  16  and enters disinfection chamber  17  where it is exposed to UV radiation emitted from germicidal bulb  18 . The small diameter of disinfection chamber  17  forces untreated water to flow all around ultraviolet bulb  18  and guarantees full illumination and penetration of germicidal light into the untreated water. The distance between quartz wall of ultraviolet bulb  18  and the wall of disinfection chamber  17  is 1.5 mm. Water disinfected inside chamber  17  flows out through outlet orifice  19  where a user can obtain water by placing a cup or any container under orifice  19 . Orifice  19  is a 6 mm diameter round hole. 
     A translucent cap  20  allows the user operating spigot  10  to visualize the ultraviolet light safely as ultraviolet rays are absorbed by plastic cap  20 . Translucent cap  20  is therefore a viewing window for a user to visualize disinfection of untreated water and also detect the end of life of spigot  10  when ultraviolet bulb  18  no longer illuminates. Ultraviolet bulb  18  is held in housing  21  and epoxy is poured in gap  27  between ultraviolet lamp base  181  and housing  21  to prevent water from flowing upward when it reaches the disinfection chamber  17 . Lamp base  181  has a positive and a negative pole to which electric connections are made. Electric connections run from lamp base  181  to microswitch  22  and to connector jack  23  which receives the matching connector plug  24  from the transformer ballast unit  25  at a remote location from spigot  10 , preferably at the wall plug. Microswitch  22  is a normally closed switch which is activated by lever  26 . When valve  15  is closed, plunger  153  is in its down position and pin  155  attached to plunger  153  pushes on lever  26  to maintain microswitch  22  in its activated position, which corresponds to its OPEN position. When user pushes or pulls on handle  154 , plunger  153  raises and pin  155  no longer exerts pressure on lever  26  which releases microswitch  22  to its unactivated position, corresponding to its CLOSED position, which allows current to flow to ultraviolet bulb  18 . 
     A suitable material for spigot  10  is ABS (acrylonitrile butadiene styrene) plastic or any suitable food-grade plastic approved by the Food and Drug Administration, preferably a plastic that does not contain BPA (Bisphenol A) chemicals that are currently facing possible ban in United States and Europe. Translucent cap  20  can be made of transparent or slightly colored translucent ABS provided the plastic composition contains a suitable FDA approved UV stabilizer such as TINUVIN or other adequate UV stabilizers to prevent degradation of cap  20  during usage of the spigot  10 . Use of spigot  10  is estimated to take about 15 seconds per use to fill a glass of water and to be used between 20 and 30 times a day. The type of use of the spigot  10 , i.e. for short lapses of time, but repeatedly throughout the day, will limit the degradation of plastic which usually happens during prolonged exposure to ultraviolet light. 
     Gaskets  12  and  13  are preferably made of flexible elastomer-type material of conical shape to provide maximum leak prevention. Seal  151  is a conical seal of any suitable flexible plastic material. Spring  152  is a tapered spring of 8.7 mm lower outside diameter, 12.7 mm upper diameter, 22.3 mm free length available commercially at Century Springs Corporation of Los Angeles, Calif. Plunger  153  is made preferably of a high resistance plastic such as reinforced acrylic or other strong and durable plastic to withstand the pulling and pushing action numerous times a day. 
     Microswitch  22  is a sealed pin plunger type subminiature switch rated at 125 VAC and 6 A current, or 30 VDC and 3 A, with solder terminals, available commercially from Future Electronics of Pointe-Claire, Montreal, Canada. 
     Germicidal bulb  18  is a filament-type, hot cathode, low pressure mercury vapor ultraviolet lamp that produces ultraviolet wavelengths around 254 nm that are lethal to pathogens such as bacteria, viruses and parasites that can be harmful to human health. As the UV radiation source, bulb  18  is available commercially from CNLight Co., Ltd of Fo Shan, China. Bulb  18  is rated at 3 W power with GTL2 standard base type, and is 17 mm in diameter, 52 mm in length where the quartz section of the bulb is 32 mm and the metal base of bulb is 20 mm. Ultraviolet bulb  18  requires a starting voltage of 12 to 14V and runs at a voltage of 10V and 0.3 A. 
     The transformer ballast unit  25  has two versions, a 110V/220 VAC version for use in urban areas with regular 110V AC or 220 VAC power outlet, and a 12 VDC version for use in rural areas or during disaster-relief operations where 12 VDC batteries or a 12 VDC power source are oftentimes the only power sources available. Spigot  10  has such a low power requirement that it makes it especially suitable for being powered in any remote location from a small, postcard-size, solar panel. 
     Connector jack  23  and matching connector plug  24  are 1.3 mm center pin, 3.5 mm outside diameter, 7.4 mm length DC jack and plug available commercially from Shogyo International Corp. of Syosset, N.Y. Transformer ballast unit  25  for either 110V/220 VAC or 12 VDC applications is commercially available from Advanced Power Solutions Inc. in Pleasanton, Calif. Spigot  10  including spigot body, cap, housing, handle, seals, gaskets, plunger, pin and lever is commercially available in plastic injection from High Performance Engineering in Colorado Springs, Colo. 
     In operation, a user first attaches spigot  10  to a suitable container where untreated water will be added. Containers such as buckets, 5-gal jug water dispensers, and ceramic pots are all suitable. A user then connects transformer unit  25  to an appropriate power source. The user also connects connector plug  24  to jack  23  of spigot  10 . Spigot  10  is then ready to dispense disinfected and germicidally treated water at outlet  19  whenever the user activates handle  154  to turn on ultraviolet bulb  18  and open flow valve  15 . When the user is done serving water, the user can stop the flow of water and turn off bulb  18  by simply returning handle  154  to its resting horizontal position. 
     The UV water purification spigot  10  has been tested at FDA certified laboratory CIAD (Centro de Investigación en Alimentos y Desarrollo) in Culiacan, Sinaloa, MEXICO and found to supply 2.5 liters per minute of germicidally treated water after a less-than-a-second radiation period, effectively removing 99.9% of bacteria and viruses from the untreated water. The water purifier is thus able to inactivate all viruses, bacteria and parasites from untreated water in less-than-a-second exposure time to, or illumination by, UV radiation. 
     While the invention has been described above with references to specific embodiments thereof, it is apparent that many changes, modifications and variations in the materials, arrangements of parts and steps can be made without departing from the inventive concept disclosed herein. For example, any suitable FDA approved plastic material can be used to make the injection molded parts of spigot  10  such as polyethylene, polypropylene, PET or polyester, among others. Valve  15  could be a different flow control mechanism, such as a ball valve or diaphragm valve mechanism. Microswitch  22  could also be chosen from different miniature switch mechanism, such as a reed switch or mercury switch provided they are normally closed switches. Ultraviolet bulb  18  can be any 3 W ultraviolet bulb of GTL2 or GTL3 base type, either cold cathode or hot cathode, provided the dimensions of the bulb are small enough to fit in a spigot unit designed to be comparable in size to existing plastic spigots. Threaded inlet conduit  11  can be ¾ inch or ½ inch outside diameter thread or any other thread size most commonly used in container and dispenser applications in the specific country where spigot  10  will be made available. Connector jack  23  and plug  24  can be of other common dimensions for the center pin, outside diameter and length of plug provided the size of jack  23  remains small enough to be conveniently incorporated in spigot  10 . Cap  20  could be of a pigmented translucent color such as translucent dark blue color to retain the ability of the user to view ultraviolet light safely, while dampening the intensity of light slightly. Outlet orifice  19  could be of any suitable shape for dispensing water, such as a rectangular or square slot provided it allows a user to conveniently obtain water in a common-size glass, cup, jar or any other water holding receptacles. 
     Accordingly, the spirit and broad scope of the appended claims are intended to embrace all such changes, modifications and variations that may occur to one of skill in the art upon a reading of the disclosure. All patent applications, patents and other publications cited herein are incorporated by reference in their entirety.