GB2386117A

GB2386117A - Fluid treatment apparatus and method of use thereof

Info

Publication number: GB2386117A
Application number: GB0205069A
Authority: GB
Inventors: Artis Rees
Original assignee: PROTECH WATER TREAT Ltd
Current assignee: PROTECH WATER TREAT Ltd
Priority date: 2002-03-05
Filing date: 2002-03-05
Publication date: 2003-09-10
Also published as: GB0205069D0

Abstract

A fluid treatment apparatus (1, Fig. 1) adapted to produce potable liquids, in particular water, comprising a multi-stage self contained system having at least one fluid treatment means, wherein the fluid treatment means includes a dosing device adapted to operate to release fluid treatment material at a rate that is controlled by the throughput of fluid through the fluid treatment apparatus. The dosing device comprises a inner tube 16 comprising a section holding material 18, and a space 24 between the material holding section and the outer body 23. Fluid enters the device by aperture 16a, reaches a screen 17 and the majority of the fluid is diverted back down the inner tube and out of apertures 16b into space 24. The fluid that passes through the screen into the material holding section is treated by the tablets and released back into the main flow by apertures 20. The material 18 may be an polymeric acrylic coagulant, and/or calcium chloride tablets. The system may comprise a tank divided into four sections. The first section (3, Fig. 1) may contain a flow regulating device, and the dosing device. The second (5, Fig. 1) may be designed to accelerate flocculation, while the third section (6, Fig. 1) contains an undrained filter bed (13, Fig. 2) and a secondary system (12, Fig. 2) to absorb soluble organics. A fourth section (7, Fig. 1) may be a storage tank. Also claimed is a method of using the multi-stage system anti-microbial materials are added to the treated fluid by passing the fluid through a dosing devices after treated fluid has been passed to the storage tank.

Description

Fluid Treatment Apparatus and a Method of use thereof Field of the Invention The invention relates to a self contained, portable apparatus for the purification of fluid. The apparatus is in particular for the treatment of water and is capable of providing potable water from a contaminated source as the water flows passively through the apparatus. A particular application of the apparatus is in the supply of water in emergency conditions but it is also suitable for domestic/community applications.

Many types of filtration systems have been used to provide potable water from contaminated sources. A number of home systems are available that utilise filtration and absorption (usually by activated charcoal), and/or ion exchange beds, all of which require either a pressurised water source or power to drive a pump to provide operating pressure. This increases cost of operation.

There is available a limited selection of devices for water purification that utilise gravity to provide operating pressure. Such devices may be easily portable, but are always small scale (providing only a few litres per hour) and require addition of oxidising compounds such as halazone to destroy any micro-organisms present. These systems have the disadvantage that care needs to be taken when adding treatment materials to ensure that they are added at safe levels.

Larger scale treatment devices have exclusively

utilised polyvalent metallic salts (such as aluminium or ferric sulphate) to effect coagulation. Such compounds require extensive control of dosage because of their potential toxic effects, and pose a risk, in isolated or emergency conditions, of over or under dosing, resulting in toxicity or lack of coagulation (and subsequent microbial contamination) respectively.

The apparatus of the present invention seeks to overcome the problems of the prior art by providing an easy to use system for producing potable fluid, at a greater rate than known systems, without the need for pumping fluid through the apparatus, so expending external power.

Summary of the Invention According to the invention there is provided a fluid treatment apparatus adapted to produce a potable liquid, the apparatus comprising a self contained system through which fluid can flow, with there being one or more fluid treatment sections for producing the potable fluid, characterised in that one or more of the fluid treatment sections includes a dosing device adapted to operate to release fluid treatment material at a rate that is controlled by the passive throughput of fluid through the fluid treatment apparatus.

Preferably, the fluid treatment apparatus includes at least one storage section, downstream of the fluid treatment sections (s) to hold the potable fluid that is produced.

It is preferred that the fluid treatment apparatus comprises a treatment section formed of individual chambers for multi-stage treatment of the fluid.

The treatment section may have a first chamber including an inlet for receiving fluid to be treated into the apparatus. It is envisaged that the first chamber may include a flow regulation device for controlling flow of fluid from the inlet. The regulation device may be a ball valve. In addition, the first chamber may include a screening element to remove larger particles from the fluid being treated. As an alternative, it is envisaged that the screening element is situated in the inlet leading into the first chamber so that large particles are substantially prevented from entering the treatment section of the fluid treatment apparatus.

It is envisaged that one or more of the dosing devices is situated in the first chamber of the fluid treatment sections. Preferably, the dosing device releases a coagulant and/or calcium into the fluid.

Preferably, the fluid treatment section includes a further chamber, downstream of the first chamber, said further chamber having fluid agitators such as turbines. The agitators are used to flocculate material in the fluid due to shear forces.

It is preferred that the fluid treatment section further comprises one or more filter devices downstream of the further chamber. It is envisaged that the filter

devices comprise filter beds adapted for the physical removal of contaminants from the fluid. Preferably, the filter beds comprise sand filters formed of grains of sand of approximately 0.3-0. 7mm in diameter. The sand filters may be followed by absorption filters, preferably of a carbon-based material such of anthracite. Preferably, the anthracite comprises grains of 0.5-0. 7 mm in diameter.

Ideally, downstream of the filter beds is one or more further dosing devices. The further dosing device (s) may contain chlorinating material, which is released as fluid flows through the further dosing device. Preferably the further dosing device is in a storage stank for the treated fluid, which is downstream of the fluid treatment section.

However, it is envisaged, that chlorination can occur prior to or as the fluid flows into the storage tank.

Preferably the apparatus is adapted to operate at a rate of 0.5 to 1m head of water and 500-1000 litres/hour flow rate.

According to a further aspect of the invention there is provided a dosing device adapted to release material or materials into a fluid passing through said device, the device comprising a body having a material holding section and a fluid restrictor adapted to limit the amount of fluid contacting the material by diverting fluid away from the material holding section, with there being one or more apertures downstream of the material holding section, which release the fluid that has come into contact with the

material into the fluid that has been diverted.

Preferably, the dosing device comprises an inner body and an outer body separated by a space into which the diverted fluid is directed.

It is envisaged that the fluid restrictor is a mesh screen.

Preferably the inner body is a tube having a lid at one end above the mesh for the insertion of material to be released. It is envisaged that the inner body includes an inlet for the dosing device, while the outer body includes the outlet for treated fluid.

Yet another aspect of the invention comprises a method of treating fluid to provide a potable liquid, the method comprising the steps of: allowing fluid to passively flow into a treatment device; treating the resultant fluid with a coagulant; agitating the coagulated fluid to flocculate contaminants; filtering the resultant fluid; passing the treated fluid to a storage device; adding antimicrobial materials into the treated fluid by passing the fluid through a dosing device regulated by the flow of fluid through said device.

As can be seen, the embodiments of the invention are adapted to increase the capability for removal (or substantial reduction to acceptable levels) of suspended and dissolved solids, metals, organic macromolecules, and

removal of protzoan parasites, bacteria and viruses in a portable system.

The utilisation of materials such as coagulants and the method of introduction of materials into the fluid reduces the risk of toxicity due to inappropriate dosing. Further, the dosing device used in the apparatus and as described allows proportional dosing of chemical additions.

Also, the invention has minimal environmental impact by using filter material that is capable of being regenerated utilising simple technology that is readily available in most domestic situations. Further the use of apparatus constructed of an ultraviolet stable, reflective plastic requiring minimal maintenance, and a source of consumable chemicals. Also, the apparatus involves a system which uses devices such as the dosing device which have inherent safety features by using a dosing system that is regulated by fluid flow through the apparatus.

Consequently, the invention has the advantage that it can be easily operated by a person having received simple instructions and so is particularly useful for emergency field work.

Description of the Figures For a better understanding of the invention, an embodiment will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 is a cut away of the apparatus showing it to comprise a tank separated into four sections, the position

of the constituent devices being indicated; Figure 2 is an end cross sectional view showing the sequence of events during operation of the unit; Figure 3 is an end cross sectional view showing the sequence of events during backwashing of the filter bed, and; Figure 4 is a vertical cross sectional view of a proportional chemical dosing device used for addition of materails such as calcium, coagulant and chlorination compound.

Detailed Description of the Invention The fluid treatment apparatus, generally indicated as 1 in Figure 1, comprises a multiple stage, closed operating system, contained in a tank divided into four sections. An inlet 2, is used to introduce fluid into a first section 3, which contains (if necessary) a flow regulation device, a particle screening device (both commercially available) and a dosing device 4 for proportionately dosing the water with calcium and coagulant. The second section 5 is designed to accelerate flocculation by application of shear forces and turbulence to the water flow and flow disturbance to enhance sedimentation. The third section 6 contains an underdrained filter bed and a secondary filtration system to absorb soluable organic molecules. The filter bed is backwashed at regular intervals to prevent clogging of the filter bed by a siphoning system utilising the stored, clean water. The fourth section 7 is a storage tank of

approximately 1 m3 volume, and contains a further dosing device for proportionately dosing a chlorinating compound into the fluid in the storage tank to maintain potability of the fluid.

The internal diameters of all pipework and fittings are calculated to provide the required flowrates without applied pressure. Ideally, all internal devices offer no more than 5% pressure reduction in the water flow.

As can be seen in Figures 2 and 3, it is envisaged that feed water enters the unit via an isolation ball valve 2, from which is passes through a drainable screening filter. As shown, there are two dosing devices 3a and 3b, which can be described as chemfeeders. However, the invention is not limited to two doing devices and one device may be used for less contaminated fluid, whilst several devices may be used for heavily contaminated liquid.

The water proceeds through the apparatus by passing through a level controlling valve such as a floating ball or ballcock valve 5a, then through an agitator such as a turbine into a flocculation chamber 5. Flocculation is accelerated by shear force as applied by the turbine, and turbulent flow caused by baffles in the chamber. The level controlling 5a valve determines the maximum level throughout the system and prevents overflow when supply exceeds demand. Passage of water through this chamber is downward, and from the bottom, enters the underdrain 14 of

the filtration chamber 6.

The water, now containing flocculated contaminants, passes upward through a filter bed of sand 13 (approx 0. 3- 0.7mm grains) where the flocculated contaminants are removed by physical filtration by and adsorption to the sand filter bed. Following passage through the sand filter, the water passes through a removable bed of anthracite coal 12 (approx 0. 5-0. 7 mm grains) where remaining metals and soluble organic macromolecules are removed by adsorption to the surface of the anthracite grains. The filtered water passes from the filtration chamber 6, through a further dosing device or chemfeeder (not shown) where it is chlorinated. The water than passes through passage 10, into the storage tank 7.

As shown in Figure 3, during backwashing of the filter bed, during cleaning of the filter material, the anthracite bed 12 is raised out of the backwash flow. The inlet isolation valve 2 is closed and the backwash drain valve 8 opened. Backwashing is effected by opening of a valve 11 in a siphoning system, which then siphons the stored water through the filter bed downwards, effecting filter backwash.

Chlorination of the water entering the storage tank is effected by utilisation of a dosing device/chemfeeder. The storage chamber is divided into two sections, treated water entering the section adjacent to the filter bed chamber and filling the chamber to a level triggering a siphon flush

which empties the water into the second chamber. This ensures that all water for consumption has had a minimum of 30 mins contact time with chlorine at 1 PPM free chlorine.

Water from the final storage chamber is discharged through a commercially available 0.2 mm filter/housing and to an isolation valve for dispensing the clean water.

The dosing device used in the apparatus of the invention is more clearly shown in Figure 4. The dosing device contains slow dissolving calcium chloride tablets 18 in a central tube 16 forming the inner body of the dosing device. There is an outer body 23 and a space 24, between the inner and outer body. Fluid passes into the dosing device by an aperture 16a in the inner body. The fluid reaches a screen 17 and the majority of the fluid flow is diverted back down the central tube 16 and out through one or more apertures 16b situated between apertures 16a and the screen 17. The 16b, situated below the mesh 17, are of a diameter such that approximately 90% of the water passes through the dosing device into the space 24 between the inner tube 16 and an outer body 23. 10% of the water passes upward through the mesh 17 and into a material holding section, through the material 18 and towards one or more apertures 20, situated downstream of the material. The apertures 20 release fluid that has passed through the material into the main flow of fluid in space 24. The fluid that has passed through the passing through the material central tube and into the main flow via one or more

variable apertures 20. The material 18 may be a polymeric acrylic coagulant such as Magnafloc TM. If required (in cases where feed water pH is low), calcium oxide, and is dosed proportionately to the flow rate to give coagulant (and calcium) concentrations of between 5 and 50 PPM. By using the dosing device, the water which will pass through the apparatus contains coagulant at a suitable concentration (this depends on the quality of the feed water). The aperture 20 in the dosing device may be adjusted to give a concentration of 1 PPM free chlorine in the effluent water. The adjustment may be by rotation of an inner tube 21 in the upper body of the dosing device in proximity to apertures 20. Rotation of the inner tube 21 allows for opening and closing of the apertures to a required size for dosing of material. There is also a cap 22, which closes off an end of the dosing device where the material 18 is held. Removal of the cap 22 allows for the introduction or replacement of material in the dosing device. Stored water in the storage tank 7, would then contain 1 PPM residual free chorine.

Although the apparatus, device and method of the invention are most suitable for the treatment of water, it is envisaged that they could be used to improve the potability of other fluids for consumption. Further by using the natural flow of liquid through the device, for example the passive flow of water from a stream, there is the avoidance of the need to use an external energy source

to force the fluid through the apparatus to purify it.

Claims

Claims 1. A fluid treatment apparatus adapted to produce a potable liquid, the apparatus comprising a self contained system through which fluid can flow, with there being one or more fluid treatment sections for producing potable fluid, characterised in that one or more of the fluid treatment sections includes a dosing device adapted to operate to release fluid treatment material at a rate that is controlled by the throughput of fluid through the fluid treatment apparatus.
2. A fluid treatment apparatus according to claim 1 including at least one storage section, downstream of the fluid treatment sections (s) to hold the potable fluid that is produced.
3. A fluid treatment apparatus according to claim 1 or claim 2 wherein the treatment section (s) are formed of individual chambers for multi stage treatment of the fluid.
4. A fluid treatment apparatus according to claim 3, wherein the treatment section comprises at least three chambers.
5. A fluid treatment apparatus according to claim 4, wherein the treatment section includes a first chamber

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having an inlet for receiving fluid to be treated into the apparatus.
6. A fluid treatment apparatus according to claim 5, wherein the first chamber includes a flow regulation device for controlling flow of fluid from the inlet.
7. A fluid treatment apparatus according to claim 5 or claim 6, wherein the first chamber includes a screening element.
8. A fluid treatment apparatus according to claim 5,6 or 7 wherein the first chamber includes one or more dosing devices for the treatment of fluid.
9. A fluid treatment apparatus according to claim 8, wherein the dosing device releases a coagulant and/or calcium into the fluid.
10. A fluid treatment apparatus according to any preceding claim wherein the fluid treatment section includes a further chamber, downstream of the first chamber, said further chamber having fluid agitators.
11. A fluid treatment apparatus according to claim 10, wherein the fluid treatment section further comprises one or more filter devices downstream of the further chamber.

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12. A fluid treatment apparatus according to claim 11, wherein the filter devices comprise sand filters.
13. A fluid apparatus according to claim 12, wherein the sand filter includes grains of sand of approximately. 0.3- 0.7mm in diameter.
14. A fluid treatment apparatus according to claim 12 or claim 13, wherein the filter device also includes an absorption filter.
15. A fluid treatment apparatus according to claim 14, wherein the absorption filter is anthracite.
16. A fluid treatment apparatus according to claim 15, wherein the anthracite comprises grains of 0.5-0. 7 mm in diameter.
17. A fluid treatment apparatus according to any preceding claim including one or more further dosing devices, downstream of the filter devices.
18. A fluid treatment device according to claim 17, wherein the further dosing device (s) contain a chlorinating material.

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19. A fluid treatment device according to claim 18, wherein the further dosing device (s) is in the storage tank downstream of the fluid treatment section.
20. A fluid treatment apparatus according to any preceding claim adapted to operate at a rate of 0.5 to 1m head of water and 500-1000 litres/hour flow rate.
21. A dosing device adapted to release material or materials into a fluid passing through said device, the device comprising a body having a material holding section and a fluid restrictor adapted to limit the amount of fluid contacting the material by diverting fluid away from the material holding section, with there being one or more apertures downstream of the material holding section, which release the fluid that has come into contact with the material into the fluid that has been diverted.
22. A dosing device according to claim 21 comprising an inner body and an outer body separated by a space into which the diverted fluid is directed.
23. A dosing device according to claim 21 or claim 22, wherein the fluid restrictor is a mesh screen.
24. A fluid dosing device according to any of claim 21 to 23 adapted to be used with fluid treatment apparatus

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according to any of claims 1 to 20.
25. A method of treating fluid to provide a potable liquid, the method comprising the steps of: allowing fluid to passively flow into a treatment device; treating the resultant fluid with a coagulant; agitating the coagulated fluid to flocculate contaminants; filtering the resultant fluid; passing the treated fluid to a storage device; adding antimicrobial materials into the treated fluid by passing the fluid through a dosing device regulated by the flow of fluid through said device.
26. A fluid treatment apparatus as substantially described herein, with reference to and as illustrated in the accompanying figures.
27. A dosing device as substantially described herein, with reference to and as illustrated in the accompanying figures.