Field of the invention

The present invention relates to a device for dispensing a unit dose of disinfecting agent for use in a water purifier. The invention further relates to a water purification system comprising said device for dispensing a unit dose of disinfecting agent, which device is capable of regulated and controlled discharge of pre-determined doses of any water-soluble disinfecting material into a batch of water.

Background and Prior art

There are various systems known and in use for household disinfection of drinking water. In most of these systems, calcium hypochlorites, chloro- isocyanurates etc. in the form of pellets or tablets are used for chlorinating or treating water. These tablets or pellets generate chlorine when they come in contact with water. The chlorine kills the microorganisms present in the water, thus purifying the water and making it safe for drinking.

US 4165709 describes a tablet dispensing device for dispensing a solid form pharmaceutical preparation on a periodic regimen. The device described is a combination of a stationary support with a single tablet dispensing aperture, a rotatable tray with a plurality of openings therein for individual alignment with the aperture, and collapsible pockets each containing a tablet corresponding in orientation with the openings of the tray, the tablets maintained in position by a frangible membrane covering the openings. However, the dispenser described here is more suitable for the purpose of dispensing tablets in a time related regimen and is not suitable for use in a water purification system for releasing the tablets in a regulated, reliable, controlled and pre-determined manner.

US 4428502 discloses a tablet dispensing device which includes a tablet dispensing wheel able to receive tablets and to convey tablets to a discharge opening, the rotation of the dispensing wheel being controlled by a circular control knob interconnected with the dispensing wheel by a rotatable axle, the control knob being able to be manually controlled and which includes a locking means to prevent rotation of the control knob. However, the dispensing device disclosed herein has very complex constructive features, which render it rather expensive.

US 4235849 discloses a pellet dispensing device for dispensing chemical tablets into a well in response to water flow from the well. The dispenser device disclosed herein also suffers from complex constructional features and is not suitable for household uses.

US 6298871 describes a chemical feeder that produces a solution of a chemical treating agent like calcium hypochlorite. In such devices, the increase in the flow rate of water into the feeder meant that there is more water-to-solid calcium hypochlorite interaction, thereby producing an aqueous effluent with a nearly constant concentration. In such feeders the delivery rate of chemical material with increasing flow rate of dissolving liquid approximates a linear function. A drawback of such feeders is that the delivery rate of chemical material is too invariant with the changes in the flow of the dissolving liquid.

In the conventional candle type domestic water filters, chlorine tablets are manually added to the filtered or unfiltered water. Such manual addition is extremely disadvantageous, cumbersome and unfriendly from the user's point of view. Thus, there exists a need for a tablet-dispensing device that can store multiple units of water-disinfecting material and release one or more single units of the same into a batch of water in a water purification system when required.

Objects of the invention

It is thus an object of the present invention to provide a unit dose-dispensing device for use in a water purification system that can store multiple unit doses of water-disinfecting material and release one or more units of the same into a batch of water in the purification system when required.

Another object of the present invention is to provide a water purification system, which is portable and inexpensive and provides for fast and easy generation of disinfected water and in which disinfecting agents are not required to be manually added.

Yet another object of the present invention is to provide a device that does not need elaborate installations prior to the water treatment.

Summary of the invention

According to one aspect of the invention, there is provided a unit-dose dispensing device for dispensing a disinfectant for use in a water purifier comprising: a) a container having a base provided with a unit-dose dispensing aperture; b) a rotatable unit-dose dispensing mechanism disposed in said container, said dispensing mechanism comprising: (1) a rotatable shaft;

(2) a plate disposed below said base fixedly attached to said shaft wherein said plate has an opening whose cross-section is substantially the same as said aperture;

(3) a open-ended column for holding a stack of unit-doses of disinfecting material, said column being offset from and attached to said shaft and capable of being rotated on rotation of said shaft; such that at one position at which said column is aligned with said aperture, only one unit-dose is released from said column and held on said plate, and on

rotation of said shaft, at the dispensing position, said aperture aligns with said opening to dispense the unit-dose from said container.

According to another aspect of the invention there is provided a water purification system comprising:

(a) an upper chamber comprising an inlet means for receiving input water and a lower chamber comprising an outlet means for collecting purified water; said upper chamber in fluid communication with

(b) a filter medium for removing suspended particulates and dissolved organics; and further comprising

(c) said unit-dose dispensing device; such that when feed water is fed into the upper chamber, the water is filtered through said filter medium and fed into the lower chamber where the water is disinfected by the unit dose of disinfectant dispensed from said unit-dose dispensing device.

It is desirable that the disinfected water from the lower chamber passes through a scavenger means to remove any disinfection byproducts that may be present in the water.

Detailed Description of the invention

In the unit-dose dispensing device the unit dose may be a tablet or a capsule filled with powder or fluid suitable for disinfecting a batch of water. The unit- dose dispensing device comprises a container which has a rotatable unit-dose dispensing mechanism. The container may be of any shape but is preferably cylindrical. The base of the container has an aperture whose cross-section corresponds to the shape of the unit-dose to be dispensed. Thus, if the unit- dose has a circular cross-section, the aperture has a circular cross-sectionas well. The aperture is further configured such that the unit-dose is capable of passing through said aperture. The rotatable unit-dose dispensing mechanism has a rotatable shaft which is preferably cylindrical. The rotatable shaft is

preferably disposed in the centre of said container. The rotatable shaft is attached to a plate which is disposed below the base of the container. The rotatable shaft is also attached to a column which is offset from said shaft. The column is capable of containing a stack of the unit doses to be dispensed and is open on both ends. The upper ends facilitates addition of fresh unit-doses while the lower end enables dispensing into the water to be purified when rotated into selected positions. The rotatable shaft may optionally comprise a means for rotating said shaft, e.g. a handle. Optionally, a means to resiliently bias the position of the column from the dispensing position to the position at which column is aligned with the aperture, may be provided, e.g. a spring.

The water purification system of the invention comprising the unit-dose dispensing device has a filter medium. The filter medium is so disposed in the purification system that water fed in to the upper chamber flows through said filter medium into the lower chamber. The filter medium is preferably a granular adsorbent medium e.g. clay or granular activated carbon or combinations thereof. When activated carbon is used, it may bonded into a block or unbonded. When bonded, the preferred binding agents include polymers e.g high molecular weight poly ethylene. The filter medium facilitates removal of suspended particulates and dissolved organic compounds like pesticides and pesticide residues. When bonded into a block, the block may be used to remove particulates generally above 3 μm in size, including chlorine-resistant microorganisms like cysts. The water thus free of the dissolved and suspended impurities is collected in the lower chamber where the disinfecting agent is dispensed by the dispensing device thus killing micro-organisms like viruses and bacteria.

The unit-doses, e.g. tablets may be made from any chlorine-releasing material e.g. potassium or sodium dichloroisocyanurate, trichlorocyanuric acid, chlorinated trisodium phosphate, calcium hypochlorite, lithium hypochlorite, monochloramine, dichloramine, [(monotrichloro)-tetra(monopotassium dichloro)]

pentaisocyanurate, 1,3 dichloro-5,5-dimethylhydantoine, N.N-dichloro- p.toluene-sulfonamide, thrichloromelamine, N-chloramine, N-chlorosuccinimide, N.N'-dichloroazodicarbonamide, N-chloroacetyl-urea, N, N- dichloroazodicarbonamide, N-chloroacetyl-urea, N.N-dichlorobiurile, chlorinated dicyandiamide. The unit dose of disinfectant is preferably a material which, on the one hand is capable of being configured as a unit dose e.g. a tablet, on the other hand easily disintegrates and dissolves in water. The disinfectant also preferably is not very hygroscopic. Due to these opposing requirements, very often disinfectants e.g. sodium dichloro isocyanurate which disintegrate and dissolve easily but are hygroscopic may have to be used. In such cases, an additional dessicating material may be provided in the column wherein the unit- doses are stacked so as to maintain the purity and integrity of the unit doses.

The water may then optionally pass through a scavenger means before exiting the water purification system. The scavenger means separates the excess disinfectant and its byproducts from the water, thus making it suitable for drinking. The scavenger means is preferably bacteriostatic activated carbon.

The water may flow through the scavenger means in the downward direction or in the upward direction. Various embodiments may be envisaged for such flow arrangement, including the one described in WO04/014803. It is preferred that the volume of water collected post the scavenger means in, for example, a collection chamber is kept to a minimum. A particularly preferred embodiment of this is to have the water post the scavenger means directly connected to an outlet means, e.g. a tap so that water is in contact with the disinfecting agent for the longest time possible and is dispensed for use through the scavenger means only on opening the tap.

The invention will now be illustrated with reference to a non-limiting exemplary embodiment.

Description of the drawings

Figure 1 is a perspective view of the tablet dispensing device with container and the contents of the container shown separately. The column (1) for holding the stack of tablets (2) is attached to the shaft (3) with the plate (4) having the opening (5) with support plates (6, 6a). The column is open on both the bottom end (7) and the top end (8). An air tight closure (9) is provided on the top end of the column to keep it closed during use. The rotatable tablet dispensing mechanism (10) would be disposed in container (11) when assembled. The container has aperture (12) on the bottom plate (13). The shaft is provided with a handle (14) to enable rotation.

Figure 2 is a perspective view of the tablet dispensing device at the position with the column (1) aligned with the aperture (12). The space between the base (13) of the container and the plate (4) is so adjusted that at this position, only one tablet passes through the aperture and is held on the plate.

Figure 3 is a perspective view of the tablet dispensing device in the dispensing position i.e. the position with the aperture (13) in the base aligned with the opening (5) in the plate. When the tablet is desired to be dispensed into the water, the handle (14) is rotated, to bring the aperture (13) in line with the opening (5), such that the tablet held on the plate falls through the opening, to be dispensed into the water.

Figure 4 is an embodiment of a water purification system comprising the container (10) having the tablet dispensing device. The water purification system (15) has an upper chamber (16) and a lower chamber (17). Water is fed into the water purification system through inlet means (18). The feed water is filtered first through a sediment filter (19) which is cup shaped and made of non-woven cloth and collects in the upper chamber. The water then passes through filter medium (20) which is a block made of activated carbon, to make the water free of dissolved organics, particulate matter with a size greater than 3 microns, and biologically active organisms like cysts. The water then flows

through tube (21) and downcomer (22) into the bottom chamber. When the water flows through the downcomer, the tablet dispensing device is actuated to dispense one disinfectant tablet into the bottom chamber also through the downcomer (22). The tablet dissolves in the water in the bottom chamber, thus generating the active biocide e.g. chlorine thereby killing the microorganisms like virus and bacteria. When the water reaches a level higher than the height h, the water then flows through the scavenger means (23) e.g. a bed of bacteriostatic granular activated carbon in the downflow direction into collection chamber (24). The bed of granular carbon adsorbs the residual chlorine in the water and any by products generated as a result of the biocide dissolution in water e.g. cyanuric acid as a byproduct when sodium di chloro iso cyanurate is used as the biocide. The water is dispensed from the outlet means (25) e.g. a tap.

It is thus possible by way of the present invention to provide a simple portable and convenient tablet dispensing device that can store multiple units of disinfecting material and release one or more single units into a batch of water in a water purification system as and when required, thereby providing fast and easy purification of potable water.