WO2006024093A1

WO2006024093A1 - Apparatus for the treatment of water

Info

Publication number: WO2006024093A1
Application number: PCT/AU2005/001319
Authority: WO
Inventors: Vince Camilleri; Patrick Buckley
Original assignee: Bucam Pty Ltd
Priority date: 2004-08-31
Filing date: 2005-08-31
Publication date: 2006-03-09
Also published as: AU2004100721A4; AU2004100721B4

Abstract

An apparatus (1) for treating water and in particular acid sulphate ground water is disclosed. The apparatus (1) comprises a tank (10) comprising a particle settling unit 2 and also a filtration unit 3. The units 2 and 3 are separated by a separator plate (20) that extends up from the bottom (15) of the tank to a point spaced below the top (14) of the tank. The particle settling unit 3 has a directing plate (30) that together with the separator (20) causes a sharp change in the momentum of the water passing through the unit 2. This encourages particles within the water particularly large particles to be knocked out of suspension and to collect at the bottom (15) of the tank (10) from where they can be removed. The filtration unit 3 has a filter cloth (45) extending across the flow path for removing further particles from the water. The apparatus also has a means for adjusting the pH of water passing through the apparatus so that the pH of water issuing from the apparatus has a pH of 6.0 to 9.0. The pH adjustment means comprises a sensor sensing the pH of the water in the outlet and a recirculation conduit (50) recirculating some water from the outlet (40) back into the inlet (25). The pH adjustment means also includes a controller (56) for responding to this sensed pH by topping up the water in the recirculation conduit (50) with caustic. This water with caustic is then returned to the front end of the process.

Description

APPARATUS FOR THE TREATMENT OF WATER

FIELD OF THE INVENTION

This invention relates to apparatus for the treatment of water. This invention also extends to a method for the treatment of water.

This invention relates particularly but not exclusively to an apparatus for the treatment of water that is exposed by excavating building sites, such that this water can be discharged directly into a storm water drain and returned to natural waterways such as rivers and creeks. It will therefore be convenient to hereinafter describe the invention with reference to this example application. However at the same time it is to be clearly understood that the invention has a number of other applications and it is not to be limited to this application. For example it could be applied to the treatment of grey water to enable the recycling of water in a domestic environment. It could also be used for the treatment of water in an industrial environment.

In the specification the term "comprising" shall be understood to have a broad meaning similar to the term "including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising" such as "comprise" and "comprises".

BACKGROUND TO THE INVENTION

At a building site it is often necessary to excavate earth to build a foundation for the building or structure. Sometimes water pools in the hole formed by the excavation and this ground water needs to be removed for the structure to be built. The ground water is often not in a condition for it to be pumped into a stormwater reticulation system and returned to the ground water. For example the ground water may be acidic and have a pH lower than seven. It may also have an excessive number of particles suspended therein making it cloudy and opaque, a condition known as high turbidity. A particularly problematic form of ground water that is encountered when excavating sites is acid sulphate ground water. This water is highly acidic having a pH of less than 5 and also having a high level of turbidity.

Currently it is a common practice to pump the water into the stormwater reticulation system even though it is not clean and does not meet the standards required for this to be done legally. However it is highly undesirable for acidic water and water that has a very high level of turbidity to be passed into the storm water system. Water authorities are beginning to take a stricter line in relation to these practices and it is unlikely that they will allow untreated acidic water with high turbidity to be pumped into the storm water system in future.

An alternative to treating the water at the site would be to pump the water into road tankers and transport it away from the site. However this option is very expensive and would not be attractive to builders and engineers for this reason.

Clearly therefore it would be advantageous if a method and apparatus could be devised for treating the water on site to improve its quality to a point where it meets the standards required for it to be lawfully pumped into a storm water drain.

It would also be particularly advantageous if such an apparatus was transportable such that it could be shipped to one site where it was used and then when that job was complete it could be shipped to another site. By the term transportable is meant that the apparatus be transportable by road, eg on a truck much like a shipping container. SUMMARY OF THE INVENTION

According to one aspect of this invention there is provided an apparatus for treating water, comprising: a particle settling means for receiving water to be treated having means for encouraging at least some particles within the water, e.g. the larger particles, to drop out of suspension to enable these particles to be removed from the liquid; a filtration means in line with the particle settling means downstream of the particle settling means having a filter element through which the water to be treated is passed for removing further particles within the water from the water; and a pH adjustment means for adding an appropriate level of acid or alkali to the water being treated so that water issuing from the filtration unit has a pH within acceptable limits.

Thus incoming water first undergoes a particle settling step that encourages particles to settle or be knocked out of solution. Thereafter the water is filtered to remove further particles. In addition the pH of the water is sensed and in response there to an appropriate amount of acid or alkali is added to the water passing through the apparatus to reduce its acidity or alkalinity as the case may be before it issues from the apparatus.

The particle settling means may be a unit having an inlet, and an outlet, and a flow path extending from the inlet to the outlet. The particle settling unit may include means for sharply changing the momentum of the water as it passes along the flow path from the inlet to the outlet. The means for sharply changing the momentum of water may comprise a sharp change in the direction of the flow path. The change in the direction may be greater than 90 degrees, eg about 180 degrees.

The particle settling unit may further include means for adding a flocculating agent or agglomerating agent to the water passing there through. This may be in the form of a flocculation holder that holds a said flocculating agent. The flocculation holder may be open to permit water to pass there through and come into contact with the flocculating agent.

Further the means for adding a flocculating agent may also include a flocculating agent within the holder, eg in use. The flocculation agent may be in the form of a solid block, eg a block of MAGNASOL.

The holder may be located inside the particle settling unit, proximate to the inlet of the settling unit. For example the holder may be positioned in proximity to the inlet such that water entering through the inlet is passed over the holder.

The settling unit may further include a solids outlet for removing settled particles from the settling unit and a removable closure mounted over the settling unit. The solids outlet may be located in a lower region of the settling unit.

Thus from time to time the closure can be removed and solids can be physically removed from the particle settling unit through the solids outlet. The flow of water through the unit may be interrupted during the removal of the solids.

The filtration means may be a filtration unit having an inlet and an outlet and a flow path extending from the inlet to the outlet and a filter element extending across the flow path such that water passing from the inlet to the outlet has to pass through the filter element. The filter element may comprise a flexible filter element that extends across the flow path.

The filter element may be a filter cloth, eg a geofilter cloth or a geotube filter cloth. The warp and weft strands of the cloth may be arranged and spaced such that most of the particles in the water, including particles greater than 1 mm and more preferably particles greater than 0.5 mm, are retained on the cloth while the water passes there through. The filter cloth may extend across the flow path transverse to the direction of the flow path. Further the cloth may be angled relative to a line orthogonal into the direction of the flow path, eg such that it extends diagonally from one side of the flow path to the other. The cloth may be angled such that a lower edge the cloth is more downstream than an upper edge of the cloth.

The apparatus may include an outlet conduit extending from the outlet of the filtration unit.

The pH adjustment means may include means for sensing the pH of water passing through the apparatus. The sensing means may sense the pH of water in the particle settling unit or the filtration unit or in the outlet of the filtration unit. Preferably the sensing means senses the pH of water that issues from the outlet of the filtration unit. The sensing means may measure the pH in the outlet conduit downstream of the outlet of the filtration unit.

The pH adjustment means may include a pH adjustment unit including a recirculation conduit having an inlet drawing water from the filtration unit, or downstream of the filtration unit, and having an outlet returning the water to the settling unit, or upstream of the settling unit.

Preferably the inlet of the recirculation conduit is in fluid communication with the outlet conduit and draws water from the outlet conduit. Preferably the outlet of the recirculation conduit directs water back into the settling unit. The pH adjustment unit may further include a liquid displacement means for displacing water around the recirculation conduit.

The pH adjustment means may further include an acid or alkali supply. The supply may comprise an acid or alkali supply tank and a supply conduit operatively coupling the tank to the recirculation conduit.

The pH adjustment means may further include a control means in the form of a controller responsive to the pH sensed by the sensing means to draw an amount of acid or alkali from the supply tank into the recirculation conduit from where it is pumped through the remainder of the recirculation conduit and through the outlet of the recirculation conduit into the settling unit.

The acid or alkali may be drawn into the recirculation conduit by vacuum, by gravity feed or by pumping action, including pumping with a positive displacement pump.

The controller may be an online pH controller, eg a PID controller that controls the amount of acid or alkali drawn from the supply tank so as to achieve a pH of 6.0 - 9.0 in the water issuing from the apparatus.

The pH adjustment means may include means for visually indicating the pH of water passing out through the outlet to a user or operator.

The visual indicating means may include a visual display.

The pH adjustment means may further include means for recording the pH of water passing through the outlet for the full duration of operation of the apparatus. The recording means may log the pH of water passing out of the outlet of the filtration unit over the full duration of operation of the apparatus. The recording means may log the pH on paper or it may log the pH on an electronic storage device.

This way a record of pH of water issuing from the apparatus over the course of its operation can be produced. This can be used by a user to verify the quality of water that they discharge into a storm water drainage system complies with the regulations.

The apparatus may further include means for measuring the turbidity of the water. The turbidity measuring means may be an online turbidity measuring system that continuously measures the turbidity of the water while the apparatus is operating. Alternatively the turbidity measuring means may be a gauge separate from the rest of the apparatus that is used to sample the water.

The apparatus may further include a turbidity control means for controlling the settling and filtration steps based on the turbidity measured by the turbidity measuring means.

Conveniently the particle settling unit and the filtration unit may be formed by a tank or container having a partition dividing it up into a settling portion towards one end thereof and a filtration portion towards the other end thereof.

The tank may be a rectangular tank having two sides, a top and a bottom and inlet and outlet ends.

The partition may extend up from the bottom of the tank towards the top and terminate short of the top so as to define a gap between the terminal end of the partition and the top thereby forming said outlet of the settling unit and said inlet of the filtration unit.

The partition dividing the tank up into the settling and filtration units may comprise a substantially planar partition plate that extends up from the bottom of the tank towards the top and terminates short of the top of the container.

The tank may be sized such that it has a length not exceeding 6m, a width not exceeding 2m, and a height not exceeding 2m, such that it can be lifted by a crane and that it can be loaded onto a truck. This way the tank can be moved from one side to another by a truck travelling on the road as the need arises.

The means for changing the momentum of the water in the particle settling unit may include a directing plate extending down from the top of the tank towards the bottom and terminating short of the bottom of the tank. The inlet may be located on the inlet end of the tank towards the top thereof. The solids outlet may be located on the same inlet end of the tank as the inlet but towards the bottom of the tank.

Thus water flowing through the settling unit flows in through the inlet and is directed down towards the bottom of the tank. It then passes around the end of the directing plate and back up between the partition plate and the directing plate towards the outlet. The sharp change in direction that occurs encourages particles to settle out on the bottom of the tank proximate to the outlet. From time to time these particles can then be removed through the solids outlet.

The means for adding a flocculating agent may comprise an open container that is received within the tank and is mounted on the tank proximate to the inlet. The open container may comprise a basket or the like that can carry a solid bar or the like of flocculating agent and water can enter into and pass through the basket.

The level of water in the particle settling unit may be the same as or higher than the height of the outlet of the particle settling unit. Thus water flows over the partition which acts as a weir retaining a certain level of water in the settling unit. The basket may be located at about the same height as the level of water in the tank.

An upper edge of the filter cloth may be attached to the top of the tank and a lower edge may be attached to the bottom of the tank. The lower edge may be positioned nearer the outlet than the upper edge which is nearer the inlet so that the filter cloth is inclined downwardly and forwardly, i.e. in the direction of flow.

Thus in a cross-sectional side view it extends diagonally from top to bottom. In the filtration unit the water flows from the inlet to the outlet and in doing this it crosses the filter cloth. This filters out solid particles that are larger than the openings in the filter cloth. The inclination or diagonal orientation of the filter cloth encourages solids to drop off the cloth onto the bottom of the tank from they can be removed, e.g. manually. Thus they do not tend to build up on the surface of the cloth.

The acid or alkali supply tank may be located in close proximity to the primary tank, eg on top of the tank. The supply conduit and the recirculation conduit may be flexible.

The supply tank may be of a squat configuration to ease its transport on a truck. For example it may have a volume of .5m³ - 1.5 m³, preferably 0.8m³ - 1.2m³. Thus the supply tank like the primary tank can also be easily transported on a truck. The pH adjusting unit can be detached from the tank for transport and then assembled on site.

The apparatus may further include a water feed pump for pumping water to be treated in through the inlet to the settling unit and also a feed conduit for directing water to the inlet.

According to another aspect of this invention there is provided an apparatus for treating water, comprising: a particle settling means for receiving water to be treated having means for encouraging at least some particles within the water to drop out of suspension to enable these particles to be removed from the water; and a pH adjustment means for adding acid or alkali to the water to be treated, the pH adjustment means comprising a recirculating conduit drawing water from downstream of the settling unit and returning it to the apparatus upstream of the settling unit, and a controller for sensing the pH of the water exiting the apparatus and in response thereto adding acid or alkali to the water in the recirculating conduit so that water issuing from the apparatus has a pH within the range of 6.0 to 9.0.

The pH adjustment means may include a water displacement means for pumping water around the recirculation conduit. The pH adjustment means may also include an acid or alkali supply tank which is coupled to the controller for supplying acid or alkali into the recirculation conduit.

The settling unit may include any one or more of the features of the settling unit described above according to the first aspect of the invention.

According to yet another aspect of this invention there is provided an apparatus for treating water, comprising: a filtration means having a filter element through which the water to be treated is passed for removing further particles within the water from the water; and a pH adjustment means for adding acid or alkali to the water to be treated, the pH adjustment means comprising a recirculating conduit drawing water from downstream of the filtration unit and returning it to the apparatus upstream of the filtration unit, and a controller for sensing the pH of the water exiting the apparatus and in response thereto adding acid or alkali to the water in the recirculating conduit so that water issuing from the apparatus has a pH within the range of 6.0 to 9.0.

The pH adjustment means may include a water displacement means for pumping water around the recirculation conduit.

The pH adjustment means may also include an acid or alkali supply tank which is coupled to the controller for supplying acid or alkali into the recirculation conduit.

The filtration unit may include any one or more of the features of the filtration unit described above according to the first aspect of the invention.

According to another aspect of this invention there is provided a method of treating water to improve its quality, the method comprising the steps of: passing the water through a settling step to cause at least some of the particles within the water to settle out; and passing the water through a filtration step to filter out further particles; and controlling the pH of water issuing from the filtration step by sensing the pH of water being treated and in response there to adding an amount of acid or alkali as the case may be to the water to maintain the pH of the water within a desired range.

Preferably the settling step is carried out before the filtration step.

The settling step may include passing the water around a sharp bend so that it undergoes a rapid change in momentum thereby encouraging the particles to settle out of the water.

The method may further include adding a flocculating agent to the water being subjected to the settling step. More specifically the flocculating agent may be added to water being introduced to the settling step.

The flocculating agent may be a solid that is exposed to water entering the settling step.

The filtration step may include passing the water to be treated through a filtration cloth, such as a geotextile.

The controlling step may include sensing the pH of water issuing from the filtration step.

The controlling step may further include adding acid or alkali as the case may be to water entering the settling step or the water undergoing the settling step. Thus acid or alkali is added towards the front end of the process. The controlling step may comprise drawing a recycle stream off the water issuing from the filtration step, sensing the pH of this water, and in response to this sensed pH adding a suitable amount of acid or alkali and returning the recycle stream to the settling step. The controlling step may include pumping the water in the recycle stream into the settling step or the water being fed to the settling step.

The water may be acidic, eg acid sulphate water, and alkali, e.g. caustic, may be added to the recirculation stream to assist in neutralizing water that is treated in the apparatus.

The method may further include pumping raw water to be treated from a site, eg an excavation site, into the settling unit.

The method may further include pumping water issuing from the filtration step into a storm water drainage system.

DETAILED DESCRIPTION OF THE INVENTION

An apparatus for treating water in accordance with this invention may manifest itself in a variety of forms. It will be convenient to hereinafter provide a detailed description of more than one embodiment of the invention with reference to the accompanying drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to put the invention into practice. It is to be clearly understood however that the specific nature of this detailed description does not supersede the generality of the preceding statements. In the drawings:

Fig 1 is a schematic diagram of an apparatus in accordance with one embodiment of the invention;

Fig 2 is an upper three dimensional view of the apparatus of Fig 1 ; and Fig 3 is a schematic flow sheet of an apparatus in accordance with a second embodiment of the invention.

In Figs 1 and 2 reference numeral 1 refers to an apparatus for treating water in accordance with one example embodiment of the invention.

The apparatus 1 comprises broadly a settling unit 2 and a filtration unit 3 coupled in line with and downstream of the settling unit 2. The apparatus also includes a pH adjustment means 5 for sensing the pH of water issuing from the filtration unit 3 and in response thereto adding acid/alkali as the case may be to water entering the apparatus.

In the illustrated embodiment the settling unit 2 and filtration unit 3 are formed by a rectangular tank or vessel or container 10. The tank 10 has an inlet end 11 and an outlet end 12, two opposed sides 13 extending parallel to the surface of the paper on which the drawings are drawn, and a top 14 and a bottom 15. The settling unit 2 is contained within a settling portion in the left half of the tank 10 and the filtration unit 3 is contained with a filtration portion on the right half of the tank 10. The two portions are divided by a separator 20 in the form of a plate. The separator plate 20 extends up from the bottom 15 of the tank 10 to a terminal end spaced below the top14 of the tank 10.

The separator 20 divides the tank 10 into the settling portion which occupies about 40% of the volume of the tank 10 and the filtration portion that occupies the remaining 60% of the volume of the tank 10. This ratio of volume of settling portion to filtration portion is not fixed to this ratio. The ratio can be adjusted depending on the properties of the water to be treated in any one site. To enable the ratio to be adjusted the separator may be capable of movement towards and away from an end 11 or 12 of the tank 10.

The settling unit 2 in turn comprises an inlet 25 on the inlet end 11 of the tank 10 and an outlet effectively formed by the space between the upper end of the separator plate 20 and the top 14 of the tank 10. The inlet 25 is suitably positioned in an upper portion or reach of the inlet end 11 of the tank 10. That is it is positioned towards the top 14 of the tank 10 on the inlet end 11.

A directing plate 30 extends down from the top 14 of the tank 10 to a point spaced above the bottom 15 of the tank 10 and a flow path shown generally by directional arrow 35 extends from the inlet 25 to the outlet around the end of the directing plate 30. Thus the flow path 35 flows vertically down and then turns sharply through 180 degrees and then up to the outlet. This change in direction causes a sharp change in momentum of the water flowing through it and encourages particles in the water, particularly large particles to settle out. These particles will collect on the bottom 15 of the tank 10 in the settling portion. The settling unit 2 also includes a solids outlet with a removable closure 38 that permits access to the settled solids that have settled on the bottom of the tank 10 to remove them from the tank 10 from time to time. The solids outlet and associated closure 38 may be located in a lower portion or reach of the inlet end 11 towards the bottom 15 of the tank 10.

The separator 20 has an upper edge which forms a weir over which water passes to exit the settling unit 2 and enter the filtration unit 3. Thus the weir effectively determines the level of water in the settling unit. Any water above the level of the weir flows out of the settling unit 2 and into the filtration unit 3. The separator 20 extends up about ²k to ³A of the height of the tank 10.

The filtration unit 3 comprises an inlet again formed by the space between the separator plate 20 and the top 14 of the tank 10 and an outlet 40 defined in the outlet end 12 of the tank 10 positioned on the outlet end 12. The outlet 40 may suitably be located about halfway up the height of the outlet wall.

The filtration unit 3 defines a flow path shown generally by 42 and extends from the inlet across to the outlet 40.

The unit 3 includes a filter element that is a filtration cloth or filter cloth 45 extending across the flow path 42 from the top 14 to the bottom 15 of the tank 10. In the illustrated embodiment the cloth is a geotube filter cloth available from CSR Industrial Water Systems Pty Ltd and the cloth has a height or length of about 1600mm and a width of about 1160 mm. As shown in the drawings the cloth 45 extends diagonally across the flow path 42 from top 14 to bottom 15 with the bottom being further away from the inlet. In other words the filter cloth is not square or perpendicular to the top and bottom of the tank. This ...

The filter cloth is removable to enable it to be cleaned

The pH adjustment means 5 comprises a recirculation conduit 50 with an inlet 52 adjacent to the outlet 40 of the filtration unit 3 and an outlet 54 feeding into the settling unit 2, proximate to the inlet 25. The pH adjustment means 5 also includes a sensor for sensing the pH of water passing out of the filtration unit 3 and a control means in the form of a controller 56. The controller 56 responds to the pH of the water issuing from the filtration unit 3 sensed by the sensor and in response there to adds acid or alkali as required to bring the pH back to a range of 6. O to 9.0.

The pH adjustment means further includes a supply tank 55 containing acid or alkali as required by the water being treated which is drawn by the controller 56 into the recirculation conduit as required to bring the pH of the water into the desired range. The supply tank 55 has a supply conduit 58 that is coupled to the controller 56. The pH adjustment unit 5 also includes a water displacement means in the form of a pump 59 for pumping water around the recirculating conduit 50. In the illustrated embodiment the pump 59 is positioned upstream of the controller 56.

The supply tank 55 may contain acid and/or alkali in liquid form in an amount of 1125kg. This makes the tank 55 eminently portable which is desirable as it has to be transported onto site and moved around. Thus several such supply tanks 55 each having a weight of 1125kg of acid/alkali may be provided on the site. The tanks may be stored in a bund area on site and coupled up to the recirculation conduit 50 as and when required. The angle from the top edge of the tank 55 to the top of the bund should be at least 25 degrees.

The controller 56 is coupled in line with the recirculation conduit 50. The supply conduit 58 is coupled to the controller 56 and this enables the controller 56 to draw acid or alkali from the supply tank 55 into the recirculation conduit 50. The controller 56 responds to the sensed pH by drawing an amount of acid or alkali from the supply tank 55 and introducing it into the recycle conduit 50 where it mixes with the water passing through the recirculation conduit 50. It then gets pumped through the remainder of the recycle conduit 50 and back into the settling unit 2.

Thus the recycle conduit 50 draws a stream of water off the main stream of treated water issuing from the outlet 40 into the recirculation conduit 50. This water is then pumped around the conduit 50 and back into the inlet 25 and acid or alkali is added to the water in this recycle conduit 50. This is advantageous because the pH of the water issuing from the outlet 40 is sensed and the pH of the water entering the apparatus 1 is adjusted. This acid/alkali is thus well and truly mixed in with the rest of the water when it issues from the apparatus.

The pH adjustment unit 5 may operate automatically when there is water flowing through the tank 10 and shut off automatically when water flow through the tank 10 is interrupted. A valve 60 is provided to shut off flow through the recirculation conduit 50 when the water flow through the tank is interrupted.

The apparatus includes means for recording or logging the pH of water issuing from the outlet of the filtration unit (not shown). This recording means may log the pH measurements so that they can they later be provided as proof or verification that the water was of the required quality.

The apparatus also includes means for measuring the turbidity of the water continuously or on line. Again this has not been illustrated in the drawings. The apparatus may further include manual meters for measuring the turbidity of the water.

In use the apparatus 1 is transported to a site, eg a building excavation site, where water has pooled and needs to be treated and removed. The apparatus

1 is transported by road to the site where it is to be used. The tank 10 has the same approximate size as a shipping container and is thus sized to be capable of being transported on a truck much like a shipping container. It can be lifted onto and off the truck by means of a crane and may in fact have lifting lugs 61 provided for this very purpose.

The acid/alkali supply tanks 55 which are smaller than the main tank 10 are also suitable for being transported by truck. The recirculation conduit 50 and supply conduit 58 and other components are transported to the site also by road in a condition in which they are detached and separate from the tank 10. Once the apparatus 1 is on site the apparatus 1 is assembled. The recirculation conduit 50 is coupled to the filtration unit outlet 40 and the controller 56 and the recirculating pump 58. The supply conduit 58 is coupled to respectively the alkali supply tank 55 and the controller 56. The assembly of the various components is simple comprising the coupling of pipes and components to each other and their positioning relative to each other and it does not take long.

A water supply conduit 62 has an inlet that is placed in a pool of water to be treated and an outlet feeding into the inlet 25 to the settling unit 2. A water supply pump (not shown) is coupled in line with the conduit 62 to pump water from the pool into the settling unit 2. An outlet conduit 65 is coupled to the outlet 40. The conduit 65 might be directed into a storm water drain.

When the water supply pump is switched on water is pumped into the settling unit 2 up to the level of the outlet with the separator 20 acting as a weir. It passes from the inlet 25 down and around the directing plate 30, and then back up to the outlet. Particles, eg large particles, drop out and settle on the bottom 15 of the tank 10 in the settling unit 2. Water passes out through the outlet by overflowing the separator 20 and entering the filtration unit 3. From there it passes through the filter cloth 45 and out through the outlet 40. Particles that are above the size of the openings in the filter cloth 45 are trapped by the filter cloth 45 and accumulate on the upstream side of the filter cloth 45.

Thus particles are removed in both the settling and filtration steps and the turbidity of the water is lowered by these processes. After passing through the filtration unit 3 the water passes out through the outlet 40 thereof and into the outlet conduit 65. Some of the water passing through the conduit 65 forms the treated water product and issues from the outlet end of conduit 65. The remainder of the water enters the recirculation conduit 50. The controller 56 senses the pH of the water and based on this introduces an appropriate amount of acid or alkali, typically alkali in the form of caustic, from the supply tank 55 into the conduit 50. This maintains the pH of water passing through the outlet 40 within an acceptable range of say pH 6.0 - 9.0.

Water in the recirculation conduit 50 is pumped around the recirculating conduit 50 by the recirculation pump 59. Thus alkali that enters the water via the controller 56 is mixed in with the water in the recirculation conduit 50 and then enters the settling unit 2 with this water when it is returned to the settling unit 2. This alkali will then be intimately mixed with the water being treated before it passes out of the outlet 40 of the filtration unit 3.

From time to time it will be necessary to remove accumulated solids from the bottom of the settling unit 2 and clean the filter cloth 45. To do this the flow of water into the apparatus is stopped and the pump 59 is switched off. The closure 38 is then removed to open the solids outlet and provide access to the accumulated solids. These solids can be dried to a water content level below 50% water which is then suitable for landfill disposal.

A common application of the apparatus is in use to treat acid sulphate ground waters. Such water will be strongly acidic and thus with this treatment the supply tank 55 will contain caustic and caustic will be added to the recirculation stream 50 to help bring the pH of the water back to a range of 6-9.

Fig 3 illustrates an apparatus in accordance with the second embodiment of the invention. As this apparatus is structurally and functionally very similar to the apparatus in the first embodiments the same reference numerals will be used to refer to the same components unless other indicated.

The following description will focus on the differences between this embodiment and the first embodiment.

This embodiment includes a holder 80 in the form of an open basket or container that is positioned proximate to the inlet 25 to the settling unit 2. In use a flocculating agent 82 that is a block of agglomerating material is placed in this holder 80 and the water that enters the settling unit 2 is passed over it. In a preferred form the flocculating agent is an anionic flocculant in the form of a block sold in Australia under the trade name MAGNASOL. The flocculating agent may also be a liquid but a solid is preferred.

The block of flocculant 82 is progressively dissolved over time by the action of water passing over it. The rate of dissolution may depend on the flow rate of the water and the general condition of the water including its turbidity or hardness. The agglomerating agent 82 assists in causing the particles to agglomerate or combine together to form larger particles which are more susceptible to dropping out of the stream of water particularly when it undergoes the sharp change in momentum around the directing plate 30.

An advantage of the apparatus described above with reference to the drawings is that it is able to be transported to a site, eg a construction site, where it can be used to clean water to a quality where the water can meet the requirements for it to be pumped into a storm water drainage system. Specifically it can be used to dewater a worksite allowing the treated water to be discharged directly into a stormwater reticulation network. A further advantage is that it is capable of taking water of very poor quality and reducing the turbidity and acidity thereof to acceptable levels. In particular it is capable of treating acid sulphate waters which are highly acidic to a quality level where it is acceptable to pour the water down a storm water drain. The apparatus described above has been able to produce water with a pH in the range of 6.0 to 9.0 and a sufficiently low level of turbidity to meet the quality standards required of water management authorities for passing the water into the storm water system.

A further advantage of the apparatus described above is that it is relatively compact. The settling unit and the filtration unit can easily be constructed in a tank having a size corresponding to that of a shipping container. This enables it to be transported from one site to another site on the road by truck transport. Further the apparatus is easy to assemble on site. The various components can rapidly and easily be coupled together to form the assembled apparatus.

A further advantage is that components used in respectively the settling and filtration unit are readily available and can be purchased off the shelf. This simplifies the manufacture of the apparatus. It also enhances the reliability of the apparatus. Essentially the only moving part is a centrifugal pump which is a well known and well practised piece of engineering equipment and as such is reliable in operation

Further the apparatus can be operated largely automatically and does not require experienced operators to run it. However from time to time accumulated solids need to be removed from the settling unit through the outlet and workers are required to do this. Further the filter cloth needs to be cleaned periodically and workers are also needed to do this.

One particular advantage that the apparatus has over other apparatuses is that the pH of water exiting the apparatus is measured, i.e. after the water has been treated. It is important to measure the water exiting the apparatus because this is the water sent to storm water drainage. Further the acid or alkali that is added to neutralise the water is added to a water stream that is passed into the front end of the process. That is it is passed into the settling unit

It will of course be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

Claims

CLAIMS:

1. An apparatus for treating water, comprising: a particle settling means for receiving water to be treated having means for encouraging at least some particles within the water to drop out of suspension to enable these particles to be removed from the liquid; a filtration means in line with the particle settling unit downstream of the particle settling means having a filter element through which the water to be treated is passed for removing further particles within the water from the water; and a pH adjustment means for adding an amount of acid or alkali to the water to be treated so that water issuing from the filtration unit has a pH within acceptable limits.

2. An apparatus according to claim 1 , wherein the particle settling means is a unit that has an inlet, an outlet and a flow path extending from the inlet to the outlet, and the particle settling unit includes means for sharply changing the momentum of the water as it passes through the particle settling unit.

3. An apparatus according to claim 2, wherein the means for sharply changing the momentum of water comprises a change in direction of the flow path of greater than 90 degrees.

4. An apparatus according to claim 1 , wherein the particle settling unit further includes means for adding a flocculating agent or agglomerating agent to the water passing there through.

5. An apparatus according to claim 4, wherein the means for adding a flocculating agent or agglomerating agent is in the form of a flocculation unit that is a holder for holding a flocculating agent, the holder being open to permit water to pass there through whereby to enable the flocculating agent to come into contact with the flocculating agent.

6. An apparatus according to claim 5, wherein the means for adding a flocculating agent further includes a flocculating agent in the form of a solid block of MAGNASOL contained within the holder.

7. An apparatus according to claim 5, wherein the holder is located inside the particle settling unit in proximity to the inlet such that water entering through the inlet is passed over the holder.

8. An apparatus according to claim 2, wherein the settling unit further includes a solids outlet positioned in a lower region of the unit and a removable closure removably mounted over the solids outlet, the closure being removed to permit access to the settling unit to remove accumulated solids from the settling unit.

9. An apparatus according to claim 2, wherein the filtration means is a unit having an inlet and an outlet and a flow path extending from the inlet to the outlet and a filter element extending across the flow path between the inlet and the outlet.

10. An apparatus according to claim 9, wherein the filter element comprises a flexible filter cloth that is a geo filter cloth.

11. An apparatus according to claim 10, wherein the filter cloth is angled relative to a line orthogonal to the direction of the flow path and a relatively lower edge of the filter cloth is more downstream than a relatively upper edge of the filter cloth.

12. An apparatus according to claim 9, wherein the pH adjustment means includes a means for sensing the pH of water that issues from the outlet of the filtration unit.

13. An apparatus according to claim 12, wherein the pH adjustment means is a unit that includes a recirculation conduit having an inlet which draws water from a point downstream of the filter element and an outlet which discharges water into the settling unit, and a liquid displacement means for displacing water around the recirculation conduit.

14. An apparatus according to claim 13, wherein the pH adjustment unit further includes an acid or alkali supply tank containing alkali or acid and a supply conduit operatively coupling the tank to the recirculation conduit.

15. An apparatus according to claim 13, wherein the pH adjustment unit further includes a control means for sensing the pH of the water issuing from the outlet of the filtration unit and in response there to drawing a metered amount of acid or alkali as the case may be from the supply tank into the recirculation conduit from where it is pumped together with the rest of the water in the recirculation conduit back into the settling unit through the inlet.

16. An apparatus according to claim 2, wherein the particle settling unit and the filtration unit are formed by a tank or container having two sides, a top and a bottom and inlet and outlet ends, the tank having a partition dividing it up into a settling portion forming the settling unit and a filtration portion forming the filtration unit.

17. An apparatus according to claim 16, wherein the partition extends up from the bottom of the tank towards the top but terminating short of the top with the gap between the terminal end of the partition and the top defining said outlet of said settling unit and said inlet of the filtration unit.

18. An apparatus according to claim 16, wherein the means for changing the momentum of the water in the particle settling unit may include a directing plate extending down from the top of the tank towards the bottom and terminating short of the bottom of the tank.

19. An apparatus according to claim 2, further including a pump for pumping water to be treated in through the inlet to the settling unit and also a supply conduit for directing water to the inlet.

20. An apparatus for treating water, comprising: a particle settling unit for receiving water to be treated having means for encouraging at least some particles within the water to drop out of suspension to enable these particles to be removed from the liquid, the particle settling unit having an inlet, an outlet and a flow path extending from the inlet to the outlet and also means for sharply changing the momentum of the water as it passes through the particle settling unit; a filtration unit in line with the particle settling unit downstream of the particle settling unit having a filter element through which the water to be treated is passed for removing further particles within the water from the water; and a pH adjustment means for adding an appropriate level of acid or alkali to the water to be treated so that water issuing from the filtration unit has a pH within the range of 6.0-9.0, the pH adjustment means including a recirculation conduit having an inlet which draws water from a point downstream of the filter element and an outlet which discharges water into the settling unit, the pH adjustment means includes a means for sensing the pH of water that issues from the outlet of the filtration unit and the pH adjustment means further includes a controller for sensing the pH of the water issuing from the outlet of the filtration unit and in response there to draws a metered amount of acid or alkali as the case may into the recirculation conduit from where it is pumped together with the rest of the water in the recirculation conduit back into the settling unit through the inlet.

21. An apparatus according to claim 20, further including a tank having a settling portion occupying one portion of the tank and a filtration portion occupying the reminder of the tank, and wherein the settling unit is contained within the settling portion and the filtration unit is contained within the filtration portion.

22. An apparatus according to claim 21 , further including a tank for the acid or alkali which is operatively coupled to the recirculation conduit.

23. An apparatus for treating water, comprising: a particle settling means for receiving water to be treated having means for encouraging at least large particles within the water to drop out of suspension to enable these particles to be removed from the water; and a pH adjustment means for adding of acid or alkali to the water to be treated, the pH adjustment means comprising a recirculating conduit drawing water from downstream of the settling means and returning it to the apparatus upstream of the settling means, and a controller for sensing the pH of the water exiting the apparatus and in response thereto adding acid or alkali to the water in the recirculating conduit so that water issuing from the apparatus has a pH within the range of 6.0 to 9.0.

24. An apparatus for treating water, comprising: a filtration means having a filter element through which the water to be treated is passed for removing further particles within the water from the water; and a pH adjustment means for adding of acid or alkali to the water to be treated, the pH adjustment means comprising a recirculating conduit drawing water from downstream of the filtration means and returning it to the apparatus upstream of the filtration means, and a controller for sensing the pH of the water exiting the apparatus and in response thereto adding acid or alkali to the water in the recirculating conduit so that water issuing from the apparatus has a pH within the range of 6.0 to 9.0.

25. A method of treating water to improve its quality, the method comprising the steps of: passing the water through a settling step to cause at least some of the particles within the water to settle out; and passing the water through a filtration step to filter out further particles; and controlling the pH of water issuing from the filtration step by sensing the pH of water being treated and in response there to adding acid or alkali as the case may be.

26. A method according to claim 25, wherein the method further includes adding a flocculating agent to the water being subjected to the settling step and the flocculating agent is a sold block that is held in an open holder and that is exposed to water entering the settling step.

27. A method according to claim 25, wherein the settling step includes passing the water around a sharp bend so that it undergoes a rapid change in momentum thereby encouraging the particles to settle out of the water.

28. A method according to claim 25, wherein the filtration step includes passing the water to be treated through a flexible filter element that is a geo- textile cloth.

29. A method according to claim 25, wherein the controlling step includes adding acid or alkali as the case may be to the water undergoing the settling step or the water upstream of the settling step.

30. A method according to claim 25, wherein the controlling step comprises sensing the pH of water issuing from the filtration step and drawing a recycle stream off the water issuing from the filtration step, and in response to the sensed pH adding a suitable amount of acid or alkali to the recycle stream and returning the recycle stream to the settling step either directly or indirectly via water being fed to the settling step.

DATED this 31^st day of August 2005 Bucam Pty Ltd By PIZZEYS PATENT AND TRADE MARK ATTORNEYS