AU2004100721A4 - A Portable or Transportable Water Treatment System - Google Patents

Description

A PORTABLE OR TRANSPORTABLE WATER TREATMENT SYSTEM Field of the Invention.

The present invention relates to a portable or transportable water treatment system and in particular to a system for worksite dewatering allowing treated water to be discharged directly into regulated stormwater collection facilities.

Background Art.

Portable or transportable water treatment systems are available in the marketplace. Various units are available which treat water by passing the water through a multistage process including one or more of the process steps of coagulation, flocculation, settling and filtration.

One such unit is disclosed in U.S. 5520803. This document teaches a process for on-site recycling of wastewater with minimal odour wherein the solid wastes generated by the water treatment process are dewatering on-site by solar energy to water content levels below those required for disposal. All operations, including solar dewatering, are accomplished in a compact unit which may be mobile. The solar dewatering unit includes a drying pan over which a solar collector window arrangement is disposed. In the process, wastewater, a water purifying composition and an oxidizing agent are additively mixed together in a first reactor settling tank and the resulting composition is neutralized to a pH of between 7.5-9.4. The added water purifying composition is then allowed to precipitate wherein it binds to and precipitates heavy metals as well as other impurities. The precipitated purifying composition forms a non-hazardous sludge at the bottom of the tank. The resulting supernatant is pumped through a filter to yield recycled wastewater suitable for disposal or reuse. The remaining sludge is pumped to a third tank where it is accumulated and thickened. Once a sufficient amount of sludge is accumulated, the sludge is pumped to a solar dewatering unit where the sludge is dried to a water content level below 50% water which is suitable for landfill disposal.

Another unit is disclosed in U.S. 5611921 which discloses a process of dewatering primary-treated sewage which includes mixing the sewage with a coagulant or flocculant aid, usually activated polymer. The sewage is then mixed and flocculated at conditions which involve extensive mixing turbulence of the sewage and whereby part of the sewage is recycled so as to be again subjected to such mixing and flocculating. Flocks form the solid particles in the sewage. The pH of the sewage is chemically adjusted into the basic pH range or to a higher basic pH. The sewage is applied to a sand bed whereby the flocculated solids in the sewage are separated from the liquid in the sewage by collecting on the top of the sand bed. The flocculated solids located on the top of the sand bed are air dried. The dried flocculated solids are removed from the top of the sand bed.

With the prior art methods and processes, whilst flocculation and filtering processes are used, it is less common to use pH adjustment to enhance the flocculation effect. Where pH adjustment of the influent in the flocculation tank or reactor is used, the pH is adjusted with respect to the effluent leaving the flocculation vessel. Adjusting the pH at this stage and then subjecting the effluent to further process steps does not take into account any changes in the pH which may occur after the flocculation vessel.

When the treated water must comply with strict requirements on the characteristics of the treated water prior to release or reuse of the treated water, issues such as the turbidity and the pH of the water exiting the unit as opposed to that exiting the flocculation vessel become vitally important.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Summary of the Invention.

The present invention is directed to a portable or transportable water treatment system which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

In one form, the invention resides in a portable or transportable filtration unit specifically for worksite dewatering allowing treated water to be discharged directly into regulated stormwater collection facilities, the system including: a) a tank divided into at least a first flocculation and settling portion and a second filtration portion by a separation baffle member; b) an inlet and a sludge outlet located in the flocculation and settling portion; c) a treated fluid outlet located in the filtration portion; the unit also having a recirculating pH monitoring and adjustment system which removes a portion of fluid from the treated fluid outlet, monitors the pH of the fluid and adjusts pH of the fluid via the addition of appropriate chemical to the first portion of the tank to maintain a target pH of fluid exiting the tank.

The unit of the present invention is particularly well adapted to the treatment of groundwater, a particularly difficult form of which is known as acid sulfate groundwater, and the unit of the present invention is well suited to the treatment of this type.

The tank of the present invention is generally rectangular although the shape of the tank is not to be considered essential to the working of the invention. In keeping with the preferably rectangular shape of the tank, the tank may have a pair of longitudinal side walls, a pair of transverse end walls oriented substantially perpendicular to the side walls, a base from which the side walls and the end walls extend upwardly substantially perpendicularly, and a top opposed to the base.

The tank is separated into the first and second portions by a baffle. The separating baffle preferably extends upwardly from the base of the tank. The baffle extends only partially towards the top of the tank and is suitably high enough to form weir over which the water which has been partially treated in the first portion must flow in order to reach the second portion.

The separating baffle suitably separates the tank into an approximately volume first portion and an approximately 60% volume second portion. The portions need not be separated in this ratio but the ratio may be adjusted depending on the characteristics of the water to be treated in the tank. The separating baffle may therefore be moveable in order to achieve the adjustable nature of the respective volumes of the treatment portions.

There is suitably an additional baffle located in the first portion of the tank. The additional baffle preferably extends downwardly from the top of the tank.

The additional baffle suitably extends only partially towards the base of the tank. The additional baffle may be located approximately halfway between the end wall of the first portion and the separating baffle. The location and positioning of the additional baffle may create an "under and over" flow path for water through the first portion of the tank. The water may flow into the tank at an upper portion of the first portion, downwards and forward under the additional baffle before flowing upwards and forwards to flow over the separating baffle into the second portion.

As suggested above, the inlet is suitably in an upper portion of the first portion and preferably in an upper portion of the end wall in the first portion. The sludge outlet is preferably positioned in a lower portion of the first portion and suitably in a lower portion of the end wall in the first portion.

The second portion is a filtration portion and suitable filtration means is located in the second portion. Preferably, the filtration means is a filter member oriented inclined to the base and top of the tank. The filtration member may suitably slope downwards from top to base in the direction of flow through the tank. The filtration member may typically be removable. This may make cleaning or replacement of the filtration member more simple. Most preferably, the filtration member may be or include a geofilter cloth. A particularly preferred embodiment of geofilter cloth may be known as geotube filter cloth and an example of this type of cloth is available from CRS Industrial Water Systems Pty Ltd.

The treated water outlet from the tank may suitably be located in an upper portion of the second portion of the tank and suitably approximately midway up the end wall in the second portion.

A flocculation or coagulation aid may be used in the first portion of the tank to increase the effectiveness of the activity in the first portion. Suitably, the flocculation aid may be provided as a flocculation chemical. Such chemicals are available in a variety of forms such as a liquid or more preferably, a flocculation block. Such a block may be provided adjacent the water inlet in the first portion.

Suitably the block may be provided in a mesh cage or similar to prevent unintended break-up of the block. Blocks such as these are typically dissolved by the action of the water as it flows over the block. The rate of dissolution of the block may depend upon the water flow rate and/or the turbidity of the water. The flocculation aid is typically an anionic flocculation or coagulant aid, generally a chemical. One particularly preferred form of flocculation block is known in the industry by its tradename, MagnasolTM.

The pH monitoring and adjustment system is a recirculating system.

The system may be dependant upon the exit fluid flow rate. Suitably, the system samples the pH of the water exiting the tank and adjusts the pH in the unit by the addition of an appropriate substance to the inlet end, and most preferably to the water entering the system at the inlet.

As the unit is generally treating acid sulphate groundwater, the pH monitoring and adjustment system generally adds a caustic substance. In order to make the solution more easily available to the water to be treated, the caustic substance may be added as a solution, typically liquid.

The pH monitoring and adjustment system is suitably flow dependant and operation of the system may be suspended when there is no exit flow from the unit. The system or parts thereof may be the subject of automated control. The system may be associated with a datalogging system to enhance the reporting of the characteristic of the treated water exiting the unit, for example for verification of compliance with regulations.

The pH monitoring and adjustment system may include at least one recirculation pump, an on-line pH controller, and one or more flow switches. The system suitably operates by drawing water from the outlet, ascertaining the pH of the water at that point, and metering solution from a store of solution into the inlet of the tank.

The target pH for the pH monitoring and adjustment system to maintain in the exiting water or the unit may suitably be in the range of 6.0 to 9.0. The caustic solution is suitably provided in bulk in amounts up to 1125 kg to retain the portability of the unit and the attendant caustic store. The caustic solution store or supply tank may suitably be remote from the unit and is suitably linked to the unit using a supply line.

The unit may preferably monitor and adjust the turbidity of the water exiting the tank. The unit may have an associated on-line turbidity monitoring and adjusting system. Alternatively, turbidity may be monitored using one or more handheld devices.

The unit according to the invention may suitably be approximately to 6 meters in length, approximately 2 meters wide and approximately 2 meters tall. The unit may be fully portable and may be associated with a means to transport the unit such as a truck or trailer. The unit will generally be associated with a pump and water supply system to supply water to be treated to the tank and to move the water through the tank. There may be associated systems to deal with sludge removal and treated water storage or drainage.

Brief Description of the Drawings.

Various embodiments of the invention will be described with reference to the following drawings, in which: Figure 1 is a schematic side elevation view of a portable water treatment system according to a preferred embodiment of the invention.

Figure 2 is a schematic side elevation view of a portable water treatment system according to a preferred embodiment of the invention with a flocculant block.

Detailed Description of the Invention.

According to a preferred embodiment of the invention, a portable water treatment system is provided.

The two primary functions that are addressed by the system of the invention are: a) Reduction in turbidity/colour of water; and b) Control of pH within target range of 6.0 to As illustrated in Figure 1, the portable of transportable filtration unit includes: a) a tank 11 divided into a first flocculation and settling portion 12 and a second filtration portion 13 by a separation baffle member 14; b) an inlet 15 and a sludge outlet 16 located in the flocculation and settling portion 12; c) a treated fluid outlet 17 located in the filtration portion 13.

The unit 10 also has a recirculating pH monitoring and adjustment system which removes a portion of fluid from the treated fluid outlet 17, monitors the pH of the fluid and adjusts pH of the fluid via the addition of appropriate chemical to the flocculation portion 12 of the tank 11 to maintain a target pH of fluid exiting the tank 11.

The tank 11 of the preferred embodiment is generally rectangular. The tank has a pair of longitudinal side walls (shown in the plane of the page), a pair of transverse end walls 18 oriented substantially perpendicularly to the side walls, a base 19 from which the side walls and the end walls 18 extend upwardly substantially perpendicularly and a top 20 opposed to the base 19.

The tank 11 is separated into the first 12 and second 13 portions by a baffle 14. The separating baffle 14 extends upwardly from the base 19 of the tank 11.

The baffle 14 extends only partially towards the top 20 of the tank 11 and is high enough to form a weir over which the water which has been partially treated in the first portion 12 must flow in order to reach the second portion 13.

The separating baffle 14 separates the tank into an approximately volume first portion 12 and an approximately 60% volume second portion 13. There is an additional baffle 21 located in the first portion 12 of the tank 11. The additional baffle 21 extends downwardly from the top 20 of the tank 11. The additional baffle 21 extends only partially towards the base 19 of the tank. The additional baffle 21 is located approximately halfway between the end wall 18 of the first portion 12 and the separating baffle 14.

The location and positioning of the additional baffle 21 creates an "under and over" flow path for water through the first portion 12 of the tank 11. The water flows into the tank 11 at an upper portion of the first portion 12, downwards and forward under the additional baffle 21 before flowing upwards and forwards to flow over the separating baffle 14 into the second portion 13.

As suggested above, the inlet 15 is in an upper portion of the end wall 18 in the first portion 12. The sludge outlet 16 is positioned in a lower portion of the end wall 18 in the first portion 12.

The second portion 13 is a filtration portion and a filter member 22, oriented inclined to the base 19 and top 20 of the tank 11, is located in the second portion 13. The filtration member 22 slopes downwards from top 20 to base 19 in the direction of flow through the tank 11. The filtration member 22 is a geofilter cloth.

The treated water outlet 17 from the tank 11 is located approximately midway up the end wall 18 in the second portion 13.

To facilitate the control of pH, a small recirculation system which continuously pumps a stream of water from the outlet 17 of the tank 11 and returns it to the inlet 15 is used. This will continuously monitor the pH, and feed caustic solution to maintain the target pH. The system operates whenever water is flowing through the unit 10 and a flow switch 23 is provided to ensure that the recirculation system does not operate if there is no flow through the outlet of the unit.

There are two preferred option for system configuration as follows: Option 1 facilitates automatic control and display of current pH, but without datalogging.

Application Model Selected Number Recirculation Pump 24 25mm inlet/outlet 1 On-line pH controller 25 Controller with PID output 1 Flow through manifold 1 /hr pump 1 pH electrode for above 1 controller Flow Switch 23 Paddle flow switch 1 Option 2 facilitates automatic control and display of current pH, with datalogging.

Application Model Selected Number Recirculation Pump 24 25mm inlet/outlet 1 On-line pH controller 25 Controller with PID output 1 Flow through manifold 1 thr pump 1 Datalogging system with 5 1 variables logged pH electrode for above 1 controller Flow Switch 23 Paddle flow switch 1 The caustic is supplied in 1000L IBC containers 26. The container 26 should be placed in a bund area which should be 110% of the capacity of the tank 11, and the angle of the top edge of the container 26 to the top of the bund should be at least 250. A tube 28 or similar links the pH control unit to the caustic container 26 and the pump 24 to the inlet 15 and fluid outlet 17.

The flocculant used in the system is an anionic flocculant block 27.

The block 27 is placed in a mesh cage in the water flow as it enters the first portion.

The block 27 is such that it dissolves as the water pours over it. When the water flow ceases, the block 27 stops dissolving. The dissolution rate also increases when amount of suspended solids (turbidity) increases.

In the present specification and claims, the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims (4)

1. A portable of transportable filtration unit specifically for worksite dewatering allowing treated water to be discharged directly into regulated stormwater collection facilities, the unit including: a) a tank divided into at least a first flocculation and settling portion and a second filtration portion by a separation baffle member; b) an inlet and a sludge outlet located in the flocculation and settling portion; c) a treated fluid outlet located in the filtration portion; the unit also having a recirculating pH monitoring and adjustment system which removes a portion of fluid from the treated fluid outlet, monitors the pH of the fluid and adjusts pH of the fluid via the addition of appropriate chemical to the first portion of the tank to maintain a target pH of fluid exiting the tank.

2. A portable or transportable filtration unit as claimed in claim 1 further including an additional baffle located in the first portion of the tank, the additional baffle located approximately halfway between an end wall of the first portion and the baffle, the location and positioning of the additional baffle creating an "under and over" flow path for water through the first portion of the tank

3. A portable or transportable filtration unit as claimed in either claim 1 or 2 further including an anionic flocculation or coagulation aid in the first portion of the tank to increase the effectiveness of activity in the first portion.

4. A portable or transportable filtration unit as claimed in any one of the preceding claims wherein the unit is used to treat acid sulphate groundwater, the pH monitoring and adjustment system adding a caustic substance. A portable or transportable filtration unit substantially as described herein with reference to the accompanying drawings. Dated this 31st day of August 2004 Bucam Pty Ltd By its patent attorneys CULLEN CO