Patent Application
20150053602
The present invention relates to a bulk water container for removing impurities from water to provide sterile, safe drinking water to a large community of people.
Water is heavy. Delivering it over even short distances is time consuming and expensive. It requires long logistics chains or complex and expensive pipelines to maintain supplies to remote locations. This problem is evident during military or humanitarian operations, but is also relevant to communities which live in remote locations on a permanent basis.
If members of a community choose to drink water from the surrounding environment they run the risk of becoming struck down by disease through the ingestion of bacteria or viruses living naturally in the water.
A problem with the provision of clean drinking water to remote communities is the cost and complexity of the infrastructure required to deliver clean drinking water. In many countries, Governments go to the expense of implementing a national infrastructure grid with outlet nodes located in every home. This provides drinking water, on tap, in every residence. Whilst this is a reliable means of ensuring that the population is provided with clean drinking water, the cost of installing this infrastructure is very high and can for some nations be prohibitive due to a lack of available finance. Cost is not the only concern. Complexity of maintenance can be high, since the delivery safe drinking water over long distances requires very high standard pipe-lines and a high degree of maintenance can be necessary to ensure that there is no contamination along the delivery route through the delivery network.
Existing clean water delivery networks require not only a large network of pipelines, but also a large scale set of water works, which in turn consume large amounts of energy to process and distribute the water. Energy is therefore consumed not only in processing the water into clean drinking water, but also then to distribute the water under pressure throughout the network.
The problems escalate even further in difficult terrains, such as mountainous regions, jungles and rainforests. National pipeline installation projects in the past have, in some examples, been abandoned due to causes such as landslides and earthquakes, which repeatedly damage pipelines and can make the installation of pipelines, as well as their maintenance, very difficult and nearly impossible.
These costs and difficult conditions result in higher numbers of people around the world continuing to suffer because National Governments and infrastructure providers are unable to install the distribution networks which have been used in the past to solve the problem of providing clean drinking water to remote communities.
Our published International patent application WO2008/037969 discloses a water bottle having a water filter which removes sediments and other deposits from the water and has a retention of greater than 99.9999% of bacteria, cysts, parasites and fungi, and greater than 99.99% of viruses from the water.
According to the present invention, there is provided a container for the bulk storage and distribution of water to a community as drinking water. There is also provided a replaceable filter for use with such a container.
The container of the present invention provides a self contained, potentially hand operated, water storage and nano-filtration device.
The device may hold approximately 750 litres and may be configured to hold between around 200 litres and 3000 litres. Due to features of the design of the device and the filters used therein, the container can process between one and two million litres of water over its normal expected life. This life can be extended by replacing the components such as filters and/or seals and other replaceable parts as necessary.
An example of the invention will now be described in detail with reference to the following figures in which:
The container is equipped with valve assemblies 2, which may comprise a standard tap for use with water. The tap may be made from metallic materials or from moulded plastics, or any other suitable material. The valve assembly 2 may also comprise a release mechanism 21 which may be arranged to release the valve assembly from the container for replacement or maintenance. The mechanism may comprise a screw-threaded cap. The mechanism 21 may be removable from the container by a two-stage release mechanism. This two-stage release mechanism can be arranged to operate in a first stage of release, where its normally operative seal is broken and water is allowed to be released from the container without the release mechanism and associated valve assembly being fully released from the container. This allows pressure within the container to be released gradually, without the release mechanism and any attached components being ejected at high velocity by the internal pressure of the container. In a second stage of release, the valve assembly is completely free of the container for removal once the internal pressure has dropped to a safe level, where the assembly won't be ejected at high velocity. The release mechanism 21 may be configured to release both the valve assembly and a filter arranged on the internal side of the release mechanism. This can allow both the valve assembly and the filter to be removed in one go for maintenance, cleaning, or replacement. This type of two-stage functionality can be provided by a screw thread which allows fluid to pass along the threads when it is first unscrewed by an initial amount, and which then releases the whole assembly when completely unscrewed. A bayonet-type connection can work in a similar manner. The valve assemblies may be located on one first side of the container as illustrated, but may also be located on opposite sides of the container, at opposite ends of a filter 10. This will affect the construction of the filter, as will be described later in relation to the filter itself.
Container 1 is arranged to be pressurized internally such that internal pressure within the container 1 encourages water on the inside of the container, through a filter attached to the inside of each of the valve assemblies 2, to the outside of the container for use as drinking water.
The container may comprise a plurality of valve assemblies 2, each having a separate release mechanism 21, although a plurality of valve assemblies may be arranged on any one release mechanism 21. Generally, one single filter is connected to each valve assembly 2. However, alternatively, several taps or valve assemblies 2 may be connected to and be in fluid communication with each filter. Container pressurisation means 3 are provided adjacent the valve assemblies, or taps, in the illustrated example. However, they could be located anywhere on the container as appropriate. An advantage of locating the container pressurisation means adjacent the valve assemblies 2 is that a user opening the valve assembly can operate the pressurisation means 3 at the same time to re-pressurise the container as water escapes through the valve assemblies. The container pressurisation means 3 may take the form of a hand pump, such that air pressure can be induced inside the container by manual operation of the hand pump. The hand pump may be angled at an angle of around 15 degrees to 20 degrees with respect to the plane of the bottom of the container. The bottom plane is defined as a substantially horizontal plane on which the container is configured to stand when placed upon a surface or a stand in its normal upright position for use. This removes the need for any electrical or other energy sources to pressurise the container and distribute water from the container.
The container 1 has a substantially capsular form. A capsular form is that of a capsule, which comprises a substantially cylindrical body, or straight sided body, being capped at either end with a substantially hemispherical form, as can be seen in
The container may further be provided with at least one recess 9 on its upper side, which may be configured to receive some form of structural insert, such as a base for an upper platform to be placed on the container. The recess 9 may be concave and may have flat inner sides, to correspond with a substantially rectangular structure made from wood or other structural materials, so that the platform placed on top of the container is held stably in place. The recess is “concave” when it creates a depression in the wall of the container in the direction of the interior of the container, but may still have straight sides to accommodate the supporting structure placed on top. The recess 9 may comprise a drainage gully 91 which forms a liquid release, or drainage, region, arranged to allow liquid collected in the recess to escape when the container is arranged with the recess on its top side as illustrated in
It is possible to incorporate a shroud to provide some overhead protection for the filters to encourage particulates in the water to fall around and away from the filters themselves rather than settling on top of the filters in the container. A problem which can occur when using locally collected water or rain water in the container of the present invention is that a substantial amount of sediment can accrue over time in the bottom of the container 1. Since the filters are also located towards the bottom of the container 1 in order to make best use of the water in the container 1 as it empties, there is a substantial risk of the filters getting blocked by sediment and other solids resting in the bottom of the container 1. To address this problem, solids collecting recesses 14 may be provided to help to guide sediment away from the filters and into the legs 11 of the container. These recesses 14 are located on the bottom side of the container and substantially between the filter and the legs 11 in a vertical direction.
Due to the size and nature of the container 1, it is not practical to turn the container upside down to clean out the solids and so a drainage port may be provided at a substantially low or lowest point in the container. This may, for example, be located in either or both of the solids collecting recesses 14 and/or in one or both of the legs 11 of the container. It is preferable to have the ports located in the lowest portion of the container so that solids, which will tend to collect in the lowest portion of the container, can be substantially entirely cleaned out of the container. Further, at the lowest point in the container, the water pressure due to gravity will be at its greatest, although this pressure will also be increased by any internal air pressure in the container if it is sealed.
Since the container will be sealed, and subject to internal pressure, it may be necessary to include a one way valve in water feed connection point 7, or in any pipe connected to it, so that when the container is pressurised internally, the pressure does simply not escape up any feed or hose connected to port 7.
The walls of the container may have a multilayer construction and the layers from which the walls are constructed may comprise any one, or any two or all of: a structural layer 101; an insulating layer 102; and an internal, water facing, layer 103. Structural layer 101 may be constructed from a material which is primarily selected for its structural strength and may be a protective layer made from a strong material such as metal or plastic, although plastics are preferred. This is because they tend to be more light-weight, are not subject to corrosion and can be less expensive. Layer 103 may be an inner layer, facing and contacting the water inside the container 1. This layer may be selected from materials appropriate for use with drinking water. These materials are known as potable grade materials and could be a plastic such as high density polyethylene (HDPE). This layer may also comprise a micro biological inhibitor, such as Microban™. In between layers 101 and 103 there may optionally be placed an insulating layer 102, which may be made from a foam or other thermally insulating material. This can help to protect the water inside the container from increases in temperature outside of the container. This can be particularly advantageous where daily temperatures in the environment in which the container is used rise and, if the water sealed inside the container were heated, this could induce or increase bacterial growth which could represent a health risk. This can also avoid the water in the container freezing, in cold temperatures, which is advantageous since the membranes in the filter can be damaged by freezing temperatures.
Solids collecting recess 14 can be seen, and may provide a flow-path for solids from the filter recesses 13 toward a sump area located in the leg 11. A support, or hanger, 15 may be provided below the valve assembly 2 for a user to hang a bucket or other water vessel on. Other peripheral attachments may be provided such as a shower head attached to the valve assembly 2, and a soap dish provided adjacent the valve assembly 2.
The container of the present invention is also useful for sanitation and improved cleanliness in the communities in which it is utilised. Providing clean water and soap encourages washing and improved health and hygiene among a community.
Preferred water filters for use with the present invention are suitable for ultrafiltration: that is to remove all particles of a size greater than 0.01 microns. In another preferred embodiment the filter is suitable for nanofiltration or reverse osmosis. Reverse osmosis filters are capable of removing everything (including salts and oils) apart from pure water (H2O) from a liquid. Nanofiltration removes particles of a size greater than 0.001 microns (including aqueous salts).
Water is passed through the water filter under a pressure differential. This allows the water to be passed through finer filters than would be possible if the container 1 were not pressurised.
A pore size of less than or equal to 25 nanometres is sufficient to remove most microbiological matter from the liquid, including viruses, thereby providing safe drinking water and a far more effective portable water filtration system than has previously been available. However, for additional security, preferred embodiments of the invention have a pore size of less than or equal to 20 nanometres, and more preferably have a pore size of less than or equal to 15 nanometres.
As is known in the art, the pore size of a material is in fact an average of the individual sizes of the pores (or holes) in the material, since it is inevitable that any material comprising a large number of pores will include some variation in these individual sizes. Preferred filters for use in the present invention have a tightly defined distribution of pore sizes such that the difference between the maximum pore size and the average pores size is minimized. Preferably, the standard deviation of the pore size distribution is less than 30% of the average pore size, and more preferably is less than 15% of the average pore size. In preferred embodiments of the invention, the filter has a maximum pore size of less than or equal to 30 nanometres, more preferably, less than or equal to 25 nanometres, and most preferably less than or equal to 20 nanometres. In other embodiments, the maximum pore size may be even lower in order to perform nanofiltration or reverse osmosis, for example.
Preferably, the water container of the present invention will filter water with a pressure differential of any size. For example, the operating pressure differential of a preferred embodiment is preferably greater than 10 kPa (0.1 bar), more preferably in the range of 10 kPa (0.1 bar)-500 kPa (5 bar), more preferably in the range of 50 kPa (0.5 bar)-100 kPa (1 bar). In containers of the size required for the present invention the water is encouraged through the filters by gravity when the valve is open. This gravitational pressure, or head, is more significant than in smaller-sized containers where similar filters are used and so internal pressures used need not necessarily be as high. Further, the larger surface areas used in the filters of the present invention allow for a greater flow rate for a given pressure differential across the filter or between the container-side of the filter and the ambient pressure of the surrounding environment. Thus the container of the present invention can be used at lower pressures than smaller containers while still achieving a satisfactory flow-rate through the filters. Due to these factors, a user can actuate a pump of the container of the present invention by a relatively small amount to extract water from the container. As described above, the system is sealed so as to allow a pressure differential between the inside of the container and the outside atmosphere to be created to drive water out of the valve when opened. When the valve is open, it will be apparent that internal pressure induced by actuation of the pump reduces as water leaves the container through the valve and the internal static pressure at the valve eventually reaches equilibrium with the external atmospheric pressure at the valve. Once this equilibrium is reached, water ceases to exit the container through the valve. This means that even if a valve is left open by a user, the flow of water from the container will eventually stop once the internal and external static pressures across the valve are equal. This acts to prevent unnecessary or inadvertent waste of water in the container, by providing an inherent and automatic excess-flow inhibiting arrangement.
The water filter of the present invention is preferably a membrane filter. It preferably comprises at least one hydrophilic membrane. Hydrophilic membranes are attractive to water and therefore water is passed through them in preference to other liquids and to gases. In this way, not only is the filtration offered by the preferred embodiments improved, but it is possible to use the filter even when it is not completely immersed in the liquid.
Preferably, the membranes are capillary hollow fibre membranes. These membranes act to filter the water as only particles smaller than their pore size may pass through them. The fibre membranes may incorporate carbon or other chemical elements, or reverse osmosis membranes. A combination of different types of filter membranes may be included in the filter. These may include ultrafiltration, nanofiltration and reverse-osmosis membranes.
In a preferred embodiment, the water filter comprises a filter cartridge comprising a plurality of fibre membranes. Preferably, the base incorporates a seat to receive the filter cartridge to resist lateral movement. This helps reduce the strain on the preferred fibre membranes.
Once water enters through the wall of a hollow fibre membrane under the influence of a pressure differential, it is transferred along its tube-like structure to the output. As a result, water may enter at any point along the membrane wall and reach the output while also being filtered.
The preferred fibre membranes have a retention of greater than 99.999995% of bacteria, cysts, parasites and fungi, and greater than 99.999% of viruses from the water. The fibre membranes also remove sediments and other deposits from the water.
Fibre membranes suitable for use with the present invention are available commercially, for example X-flow™ capillary membranes from Norit (www.norit.com) may be used. This hollow fibre ultra-filtration membrane 22 is effective to screen all turbidity, bacteria as well as viruses.
In the preferred commercial embodiment of the water container 1, given the relatively large capacity (typically 200 to 3000 litres), the length of the preferred fibre membranes is relatively long—typically between 50 to 200 cm, preferably 80 cm. For such lengths in the container of the present invention, the preferred filter cartridge incorporates 600 to 800, preferably 650 to 700, fibre membranes, giving an initial flow rate of between 7 to 40 litres/minute, which may be achieved at a pressure differential across the filter of 50 kPa. Each of 7 bundles of fibres in the filter cartridge may comprise 96 individual fibres. It is important to provide a reasonable flow rate to encourage users to take filtered water from the container when required, rather than transfer filtered water to a different container for storage, where it would quickly become contaminated. Advantageous flow rates may be achieved where the total surface area provide by the filter membranes is in the region of 10 m2 to 12 m2, preferably around 11m2.
The water container 10 optionally also incorporates an additional carbon filter (not shown), which sits within a void within the valve assembly 2, and through which water can pass before leaving through the tap or valve. Carbon filters are known to be effective in the removal of chemicals from water. The carbon filter used in the preferred embodiment is an active carbon filter, although other types of carbon-based filters (such as charcoal filters) may be adopted.
In
The filter membranes 611 may be bundled in further groups of 7 within each subgroup 61 as illustrated. This configuration allows some spacing to be kept between adjacent membranes, which makes efficient use of space in the filter while allowing a sufficient flow-area for water to reach the membranes and establish the required flow-rate through the filter.
A spacer 62 is provided in between sub-groups 61 of filter membranes 611. The spacer may have a central circular or hexagonal portion surrounding a central sub-group and a series of spokes protruding substantially radially from the central portion such that spacing is maintained in between adjacent sub-groups 61 of filter membranes 611. A plurality of spacers may be provided at plural axial locations along the length of filter cartridge 101 to provide support and spacing relatively evenly along the length of the filter cartridge.
Surrounding the filter membranes is an outer structural member 63 in the form of a substantially cylindrical grid-patterned or mesh-like structure, which may comprise a structure through which water can penetrate to reach the filter membranes 611, while maintaining a structural support around the filter membranes 611.
Around the structural member 63 is a primary filter here illustrated in the form of an outer filter mesh 64, which acts as a primary filter to prevent silt, dirt and sediment from contacting the filter membranes 611 inside the structural member 63. Filter mesh 64 may be made from cloth or other fibrous material or from a fine plastic mesh having an opening size of around 100microns. The outer filter mesh 64 may comprise activated carbon.
The fibre membranes 611 may be potted at an open end proximal the valve assembly 2 and sealed and capped at a distal end. A mesh wrap helps hold the fibre membranes together. In a configuration where the container has taps or valves on opposite sides, and/or taps or valves are arranged at opposite ends of a filter cartridge 101, the fibre membranes 611 may not be capped, but may be open at both ends, such that water entering the fibre membranes 611 can be delivered to either one of the taps or valves at either end of the filter cartridge 101.
| Number | Date | Country | Kind |
|---|---|---|---|
| PI2012700167 | Apr 2012 | MY | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2013/050907 | 4/9/2013 | WO | 00 |
