VALBJØRN, Anders (Mosevang 14, Nordborg, DK-6430, DK)
LAURSEN, Michael (Mommarkvej 249, Sydals, DK-6470, DK)
CLAUSEN, Peter, J. M. (Solsikkevej 3, Havnbjerg, Nordborg, DK-6430, DK)
VALBJØRN, Anders (Mosevang 14, Nordborg, DK-6430, DK)
LAURSEN, Michael (Mommarkvej 249, Sydals, DK-6470, DK)
CLAIMS
1. A water supply system (1) comprising a forward conduit (2) for supplying contaminated water from a supply structure (3) to a consumer structure (4), a consumer structure (4) comprising a purification structure (5) for separating the contaminated water into purified water and brine, at least one water outlet for delivering purified water to a consumer, and a rearward conduit (6) for removing the brine from the consumer structure (4).
2. A system according to claim 1 , wherein the consumer structure (4) further comprises a number of water outlets for delivering the contaminated water to a consumer.
3. A system according to claims 1 or 2, wherein the consumer structure (4) further comprises a number of brine outlets for delivering the brine to a consumer.
4. A system according to any of claims 1-3, wherein the consumer structure (4) further comprises a mixing outlet for delivering a mixture of at least two of the purified water, contaminated water, and brine to the consumer.
5. A system according to claim 4, wherein the mixing outlet provides for a variable mixture proportion.
6. A system according to any of the preceding claims, wherein the contaminated water is anti-bacterially treated prior to the delivery to the consumer.
7. A system according to any of the preceding claims, wherein the contaminated water is pre-filtered prior to being delivered to the consumer.
8. A system according to any of the preceding claims, wherein a chemical composition is added to the contaminated water prior to the delivery to the consumer.
9. A system according to claim 6, wherein the chemical composition is removed from the brine after being returning from the consumer to the supply structure.
10. A system according to any of the preceding claims, comprising a local storage tank arranged at the consumer structure for storage of the purified water.
11. A system according to claim 10, comprising a level meter for determining a content of the local storage tank.
12. A system according to any of the preceding claims, further comprising a water conduit (7) for pumping purified water from the consumer structure to a central storage tank (8).
13. A system according to claims 11-12, comprising a pumping structure controlled by the level meter for pumping purified water from the consumer structure to the central storage tank based on the content of the local storage tank.
14. A system according to any of claims 12-13, wherein the central storage tank (8) is located in a level above the purification structure (5).
15. A system according to any of the preceding claims, further comprising a power source (9) adapted to drive at least one of the purification structure and the pumping structure based on a renewable energy source with a variable energy supply.
16. A system according to any of the preceding claims, wherein the rearward conduit (6) returns the brine to the supply structure.
17. A system according to claim 16, wherein the forward conduit (2) and the rearward conduit (6) are formed in a single pipe.
18. A system according to any of the preceding claims, wherein the purification structure (5) comprises a reverse osmosis system.
19. A system according to any of the preceding claims, wherein the contaminated water is pumped in the forward conduit (2) at a variable pressure.
20. A system according to any of claims 1-18, wherein the contaminated water is pumped in the forward conduit (2) at a fixed pressure.
21. A method of supplying water to a community wherein contaminated water is supplied from a supply structure to a consumer structure, the water is purified at the consumer structure by separating the contaminated water into purified water and brine, and the brine is removed from the consumer structure.
22. A method according to claim 21 , wherein the removed brine is returned to the supply structure.
23. A method of utilizing excess renewable energy wherein the renewable energy is utilized for separating purified water and brine from contaminated water, and the purified water is stored in a storage tank. |
A WATER DISTRIBUTION SYSTEM
INTRODUCTION
The present invention relates to a water supply system for distributing water between a supply and a consumer.
BACKGROUND OF THE INVENTION
Shortage of natural freshwater increasingly urges communities around the world to narrowly regulate water distribution and consumption, and in some areas, lack of freshwater of a satisfactory quality necessitates chemical or mechanical purification of water or even desalination of saltwater. This causes increasing water costs and dependence on a constant energy supply for the often very energy consuming purification and desalination processes. In some geographical locations, distribution of natural freshwater is completely prohibited, and the potentials of such locations are obviously limited.
On ships and in certain geographical locations, purification or desalination by use of reverse osmosis (RO) is a common solution. In this process, the contaminated water is pressurized and permeated through a membrane which retains salt and other unwanted contents. US 6,056,878 describes a method for treating water, and US 2004/0049230 describes a biological membrane to be used in a water purification process.
In household and industry, a quantity of the distributed water is consumed for vital purposes, e.g. for cooking and sanitation etc. Often, the quality of the water for such purposes is governed by national or regional\ instructions. Typically, a larger quantity of the distributed water is
consumed for non-vital purposes, e.g. for cooling down industrial processes, for laundry and cleaning purposes, or in general for purposes wherein the quality of the water is less important or even unimportant.
DESCRIPTION OF THE INVENTION
It is an object of one embodiment of the invention to provide better access to purified water of an acceptable quality for vital purposes, to reduce energy consumption, and to make better use of water with different qualities for different purposes. According to a first aspect, the invention provides a water supply system comprising a forward conduit for supplying contaminated water from a supply structure to a consumer structure, a consumer structure comprising a purification structure for separating the contaminated water into purified water and brine, at least one water outlet for delivering purified water to a consumer, and a rearward conduit for removing the brine from the consumer site, e.g. for returning the brine to the supply structure where the brine could be regenerated, discharged, or used for purposes where the quality of the water is less important.
In the following description, purified water denotes water with a lower content of contaminants than the water which is supplied to the consumer, and brine denotes water with a higher content of contaminants than the water which is supplied via the forward conduit. In other words, what is denoted purified water does not necessarily have to be clean water but water which is less contaminated than the supplied water, and the wording contaminated water, purified water, and brine simply denotes three different quality grades of water. Contaminants denote anything which could be contained in the water, e.g. regular salt. In one example, the water which is supplied is regular saltwater, e.g. seawater. The purification structure could be of any kind known in the art, e.g. an RO system where contaminated water, e.g. saltwater is filtered under a large pressure
through a membrane to provide freshwater and brine. The water desalination system could e.g. use carbon nanotube membranes, or the purification could be in a system of the kind which is described in US 6,056,878.
Since the consumer receives contaminated water and the conversion of the contaminated water into purified water occurs at the consumers site, the consumer may judge based on individual needs and preferences when to use purified water, contaminated water, or brine, or even to mix contaminated water and purified water to obtain water with a quality which is sufficiently high for a specific purpose. It is a further advantage that the purification may occur immediately before consumption without intermediate storage, transportation in long pipe lines, possible additional contamination and exposure to light or high temperatures etc.
The consumer structure may further comprise a number of water outlets for delivering contaminated water to a consumer and/or a number of brine outlets for delivering the brine to a consumer. In that way, the consumer may select between up to three different fixed grades of water qualities e.g. having different salt contents based on the specific purpose. The system may further comprise a mixing outlet for delivering a mixture of at least two of the purified water, contaminated water, and brine to the consumer to provide even better options for adapting the quality of the water to a specific purpose and thus for reducing the costs of the water consumption to a minimum.
The supply structure may comprise pre-filtering facilities for filtering out larger particles prior forwarding of the contaminated water to the consumer. Depending upon the quality of the contaminated water, it may further be necessary to anti-bacterially treat the water prior to the consumption. Since such processes can be potentially environmentally
hazardous, or they may require expensive equipment or special education, it may be an advantage to perform such anti-bacterial treatment prior to the forwarding of the contaminated water to the consumer. Accordingly, the supply structure may comprise facilities for such water treatment. If a chemical composition is added to the contaminated water prior to the forwarding to the consumer structure, the chemical composition may be returned to the supply structure with the brine. The supply structure may thus comprise facilities for removing the chemical composition from the brine, e.g. for reusing the composition in the contaminated water which is to be forwarded to the consumer structure.
The system may further comprise a local storage tank arranged at the consumer structure for storage of the purified water. The storage tank may comprise a level meter for determining a content of the local storage tank, and based on the content of the local storage tank, purified water may be conducted in a purified water conduit from the consumer structure to a central storage tank, e.g. a tank which is shared amongst a number of consumers. Accordingly, the system may comprise a pumping structure controlled by the level meter for pumping purified water from the consumer structure to the central storage tank based on the content of the local storage tank. Advantageously, the central storage tank is located above the consumer structure so that subsequent consumption of the purified water may occur with no further forced pumping.
Since the process of separating contaminated water into purified water and brine requires a large amount of energy, it may be an advantage to provide a power source which is based on a renewable energy source, e.g. a wind turbine etc. Such power sources typically have a variable energy supply. A wind mill, as an example, generates power in response to the wind speed, solar cells in response to solar intensity etc. Accordingly, the local and/or the central storage tank could serve as an
energy reservoir which receives purified water when sufficient renewable energy is available and which delivers purified water when the power source is incapable of producing sufficient energy for the separation process. In fact, in combination with the water supply system according to the invention, it may serve as a flexible buffer for consuming an excessive energy production during periods with excessive renewable energy and for storage of the "energy" in the form of purified water.
To facilitate efficient installation of the system in a community, the forward conduit and the rearward conduit could be formed in a single pipe.
In a second aspect, the invention provides a method of supplying water to a community wherein contaminated water is supplied from a supply structure to a consumer structure, the water is purified at the consumer structure by separating the contaminated water into purified water and brine, and the brine is removed from the consumer structure and e.g. returned to the supply structure.
In a third aspect, the invention provides a method of utilizing excess renewable energy wherein the renewable energy is utilized for separating purified water and brine from contaminated water, and the purified water is stored in a storage tank.
DETAILED DESCRIPTION OF THE INVENTION
In the following, a preferred embodiment of the invention will be described in further details with reference to the drawing in which:
Fig. 1 illustrates a water supply system 1 comprising a forward conduit 2 for supplying contaminated water from a supply structure 3 to a plurality of consumer structures, in this case residential properties or houses 4. Each
house comprises a purification structure 5 for separating the contaminated water into purified water and brine. The purification structure is shown in further details in Fig. 2, and described in further details e.g. in US 7,081 ,205. The system further comprises rearward conduits 6 for returning the brine from the consumer structure 4 to the supply structure 3. When one of the purification structures produces more purified water than what is consumed in the house, the excess amount is stored in a local tank and/or conducted via the reservoir conduit 7 to a central storage tank 8. Two of the purification structures are powered by wind turbines 9.
The contaminated water is collected from a contaminated water well 10 and the brine is discharged, e.g. directly into the ocean at a distance from the well in order not to cause increasing salt content in the contaminated water. The pressure in the forward conduit 2 is 2-6 bar, and the pressure is preferably maintained constant. For this purpose the feeding pump 11 is controlled by a frequency converter 12 which receives a pressure signal from the pressure sensor 13. The contaminated water is pre-filtered in a filter 14 which prevents solid particles to settle in the forward conduit 2. The flow is measured by a flow meter 15, and the contaminated water is treated by UV radiation in the device 16 and chemical compositions known per se e.g. for anti bacterial treatment are added in the device 17
Fig. 2 shows a diagrammatic view of a portion of a purification structure comprising an RO chamber 18, a pump 19 and a pressure recovery unit 20. The RO chamber 18 receives contaminated water via the forward conduits 21. The pump 19 pressurizes the contaminated water which is received at a pressure in the range of 2-6 bar to around 70 bar pressure. Due to the high pressure, a portion of the contaminated water permeates through the RO membrane 22 and leaves the RO chamber as purified water at the outlet 23 while another portion leaves the RO chamber as brine at the outlet 24. The brine typically has a pressure in the range of 68-
69 bar. The brine enters the pressure recovery unit 20 and the relatively large pressure of the brine is utilized for pressurizing a smaller portion of contaminated water, via the conduits 25, 26. The brine is returned to the supply structure via the outlet 27. If the brine must be transported back to the water supply structure, or if the brine is used for purposes requiring a certain pressure, e.g. for cleaning or cooling purposes, the pressure recovery unit 20 may advantageously be adjusted to step down the pressure from the approximately 68-69 bar to the pressure which is desired, e.g. a pressure in the range of 2-5 bar.
In order to make better usage of the purification structures in the individual consumer structures, each purification structure may be adapted to provide a measure for its present load, e.g. how many litters of water which is purified per time measure, e.g. in percentage of a maximum possible purification rate for the structure in question. These measures could be transmitted to a central control unit, e.g. located at the supply structure, and the supply structure may thus request an increased production rate if purified water is requested elsewhere, or the supply structure may request a decreased production rate, e.g. if contaminated water is requested elsewhere - e.g. for important purposes such as fire fighting etc.
A central unit may further control the step down pressure transformation which takes place at each purification structure, e.g. in pressure recovery units. As an example, the central unit may request an increased pressure in the rearward conduit 6 in case brine is requested elsewhere, e.g. for fire fighting purposes.
To ensure a constant availability of water, the consumer structures may contain a reservoir for the contaminated water. Such a reservoir may in addition form part of a fire-fighting system and may comprise a large tank
which is located on the roof of the property to which the consumer structure belongs. Alternatively, the reservoir could comprise a swimming pool etc. To reduce the consumption of contaminated water which is received from the supply structure, the reservoir may further receive rainwater etc.