WO2012145787A1

WO2012145787A1 - Apparatus and method for reducing fouling and scaling in a fluid treatment system

Info

Publication number: WO2012145787A1
Application number: PCT/AU2012/000423
Authority: WO
Inventors: Frank Palmer
Original assignee: Aviva Pure Holdings Pty Ltd
Priority date: 2011-04-21
Filing date: 2012-04-23
Publication date: 2012-11-01

Abstract

The present invention discloses a system for reducing fouling or scaling of a filter medium in a fluid filtration system (10). A fluid source supplies a feedfluid (12) having contaminants suspended therein. A filter unit (14) receives the feedfluid (12) and has a filter medium for separating the contaminants from the feedfluid (12) to produce a fluid (18) substantially free from said contaminants. The fluid (18) is then collected in a collection reservoir (19). A generator device (30) is provided in fluid communication with the feedfluid (12) and wastefluid (20) and is configured such that the flow of the wastefluid (20) or feedfluid (12) merethrough generates a pressure fluctuation within the feedfluid (12) and wastefluid (20).

Description

APPARATUS AND METHOD FOR REDUCING FOULING AND SCALING IN A FLUID TREATMENT SYSTEM

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Australian Provisional Patent Application No. 2011901509 filed on 21 April 2011, the contents of which are incorporated herein by reference,

FIELD OF INVENTION

This invention relates to a method and apparatus for reducing the likelihood of fouling or scaling of membranes or filters in a filtration system, and in particular, to a method and apparatus for reducing the occurrence and likelihood of membrane or filter fouling or scaling in a fluid treatment system.

BACKGROUND OF THE INVENTION

Filtration systems are used in a variety of chemical, biochemical and environmental engineering situations to separate solutes, particles and or fluids present within a sourceftuid. Filtration systems may take a variety of forms and may employ a cross- flow filtration method or a dead-end filtration method. A cross-flow filtration system generally comprises a system whereby a feed fluid from a fluid source flows tangentially across a surface of a filter membrane at a positive pressure relative to the permeate side of the membrane, such that a purified liquid separated from contaminates passes through the membrane at the permeate side. In a dead-ended filtration system, feed fluid from a fluid source may be directed to pass directly through a filter membrane or porous material, such that as the fluid passes through the filter medium it is separated from any contaminates contained therein.

One such application of a cross-flow filtration system is in a reverse osmosis (RO) membrane desalination or filtration application, where a feed source of water, such as seawater or low salinity brackish water, is processed to provide a source of pure water or water substantially free of contaminants. Such water treatment systems provide an important role in delivering a pure source of water in environments where a fresh water source is limited or unavailable, such that the purified water can be used for drinking and domestic applications,

RO membrane filtration and desalination systems are an energy intensive technology for producing fresh or purified water from industrial wastewater, seawater or low salinity brackish water, and the like. To increase the efficiency of the process it is possible to heat-up and pressurise the feed-water source. However, it has been found that any gains in efficiency that may be achieved through suc a practice can be lost due to an increase in membrane fouling and scaling that occurs with an increase in temperature and pressure of the feedwater.

Membrane and filter fouling and scaling typically occurs where particles or solutes present in the feed-water are deposited onto the membrane of filter surface or in pores provided in the membrane or filter surface, This acts to degrade and/or significantly reduce the porous nature of the membrane or filter and thus its ability to function properly. In desalination and filtration applications feedwater may be sourced from an aquifer which may be contaminated with a variety of solutes, celluloids and suspended compounds which may contribute to fouling of the membrane or filter. Other sources of membrane or filter fouling may be from calcium, magnesium, iron, silica, clay, organic matter and other elements and compounds which may deposit on the surface of the membrane or filter medium.

Membrane and filter fouling and scaling are significant problems that have been hurdles to the widespread adoption of RO membrane desalination and filtration systems. Fouled and/or scaled membranes and filters lead to increases in energy requirements of such systems due to the reduced flow of water and the higher pressures needed to produce the same volume of permeate or filtrate (fresh) water.

A variety of methods have been proposed to minimise fouling and scaling of membranes and filters, such as through selecting an appropriate membrane for a specific operation, and through cross-flow filtration techniques and running backflushing cycles. Further, it has been found that the addition of very low levels of chlorine directly to the feedwater stream can be effective in minimising biological fouling.

In any event, as membrane and filter fouling and and scaling is a common problem with water treatment systems, an essential requirement in maintaining the optimum performance of such systems is to provide regular maintenance of the plants and membranes and filters, This is typically through chemical cleaning and/or replacement of the membranes or filters and servicing of water treatment plants when less than optimal performance of the plant is detected. Current chemical cleaning processes to remove membrane fouling and scaling are expensive in terms of system downtime as well as the use of toxic and expensive chemicals and antiscalants and, when required, replacement membranes and filter media.

Thus, there is a need to provide a water treatment system that reduces the likelihood of membrane and filter fouling and scaling from occurring in the first instance, so as to reduce the likelihood of a plant from running below optimum performance and reducing the need for expensive cleaning treatments and servicing of the plan

The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the above prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.

STATEMENT OF INVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

According to a first aspect, there is provided a system for reducing fouling or scaling of a filter medium in a fluid filtration system comprising:

a fluid source for supplying a feedfluid having contaminants suspended therein;

a filter unit having a filter medium for separating said contaminants from the feedfluid to produce a fluid substantially free from said contaminants; and a generator device in fluid communication with said feedfluid and configured such that the flow of said feedfluid therethrough generates a pressure fluctuation within the feedfluid.

In one embodiment, the generator device generates an oscillating pressure fluctuation within the feedfluid so as to prevent or substantially minimise contaminants separated from said feed fluid from collecting on a surface of the filter medium. The generator device may located either upstream or downstream of the filter unit.

The generator device may receive the feedfluid and generate the pressure fluctuation therein by controlling the flow of feedfluid therethrough. The generator device may be configured to both permit and restrict the flow of feedfluid therethrough in a changing manner, thereby generating an oscillating pressure fluctuation within the feedfluid.

The generator device may comprise a rotor member mounted within a body having at least one egress means for permitting the flow of feedfluid therefrom. The rotor member may be configured to be driven by the feedfluid as the feedfluid passes therethrough. The rotor member may comprise a plurality of blades configured to open and close the at least one egress means as the rotor member rotates within the body, thereby generating the oscillating pressure fluctuation within the feedfluid.

In another embodiment, at least one pump is provided in fluid communication with the fluid source to supply the feedfluid to the filter unit under pressure.

The filter medium may be a porous membrane having a plurality of pores formed therein for separating contaminates from the feedfluid.

The filter unit may comprise an outlet for permitting the egress of feedfluid therefrom. The generator device may be in fluid communication with the outlet so as to receive the feedfluid as it exits the filter unit.

According to another aspect of the present invention, there is provided a generator device for generating an oscillating pressure fluctuation within a feedfluid of a fluid filtration system, comprising:

a body having at least one inlet for receiving the feedfluid and at least one outlet for releasing the feedfluid therefrom; and

a fluid control device mounted within the body and configured to control the flow of feedfluid from the at least one inlet to the at least one outlet;

wherein the fluid control device is provided within the path flow of the feedfluid so as to be driven by the feedfluid passing through the body and the oscillating pressure fluctuation within the feedfluid is generated by the fluid control device functioning to open and close the at least one outlet.

In one embodiment, the feedfluid is provided to the body under pressure from a filter unit of the fluid filtration system.

In another embodiment, the feedfluid is provided to the body under pressure from a fluid source.

The fluid control device may be rotatably movable within the body under action of the received feedfluid. The fluid control device may be configured to open and close the at least one outlet as it rotates within the body, thereby generating said oscillating pressure fluctuation within the feedfluid. The fluid control device may comprise a rotor having one or more blades extending therefrom that control access of the feedfluid to the at least one outlet as the blades rotate within the body,

According to another aspect of the present invention, there is provided a method of reducing fouling of a filter medium in a fluid filtration system comprising;

supplying feedfluid from a fluid source, said feedfluid having contaminants contained therein;

separating a permeate from the feedfluid through drawing said permeate through the filter medium in fluid communication with the feedfluid, the permeate being a constituent of the feedfluid substantially free of said contaminants;

collecting said permeate; and

generating an oscillating pressure fluctuation within said feedfluid such that said oscillating pressure fluctuation passes along said filter medium to substantially prevent or minimise separated contaminants from collecting on a surface of the filter medium.

In one embodiment, the step of generating an oscillating pressure fluctuation within the feedfluid comprises passing the feedfluid through a generator device such that the energy associated with said feedfluid generates said oscillating pressure fluctuation,

Accordingly, to yet another aspect of the invention there is provided a system for reducing fouling or scaling of a filter or membrane in a fluid filtration system comprising:

a pipe for receiving feedfluid from a source, said feedfluid having contaminants suspended or dissolved therein;

a porous membrane or filter medium in fluid communication with the feedfluid for permitting the flow of a permeate or fluid therethrough, the permeate or fluid being constituent of the feedfluid substantially free of contaminants; and

a generator in fluid communication with the feedfluid and operable to generate a vibration energy within said feedfluid flowing through said pipe to reduce, minimise or prevent the contaminants present in the feedfluid collecting on a surface of the porous membrane or filter medium and fouling said porous membrane. In one embodiment, the generator is operable by a computer controller to control a duration and/or intensity of the vibration energy within said feedfluid. The generator may be mountable to said pipe to impart vibration energy to the feedfluid ⁱ as the feedfluid passes through said pipe!

In any of the above aspects of the invention, the feedfluid may be supplied from a source including rainwater, industrial waste, sewage, wastewater, seawater or an aquifer. The permeate obtained from the feedfluid may be water.

In yet another aspect, the invention provides a method of reducing fouling of a membrane in a fluid filtration system comprising:

supplying feedfluid from a source, said feedfluid having contaminants suspended or dissolved therein;

generating an ultrasonic vibration wilhin said feedfluid; and

separating a permeate or filtrate from the feedfluid through drawing said permeate through a porous membrane or filter medium in fluid communication with the feedfluid, the permeate or filtrate being a constituent of the feedfluid substantially free of said contaminants.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Figure 1 is a simplified view of a conventional cross-flow fluid filtration system employing the present invention according to first embodiment;

Figure 2 is a top sectional view of an embodiment of a generator device in accordance with the present invention;

Figure 3 is a simplified view of the generator device of Figure 2 in use with a fluid filtration system;

Figure 4 is a simplified view of a generator device according to another embodiment of the present invention in use with a fluid filtration system;

Figure 5 is an exploded view of the generator device of Figure 4;

Figure 6 is simplified representation of a convention fluid filtration system; and Figure 7 is a simplified representation of a fluid filtration system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

The present invention will be described below in relation to its application in for use with a reverse osmosis (RO) filtration system. However, it will be appreciated that the present invention has application across a variety of different types of filtration systems, such as micro-filtration (MF) systems, ultra-filtration (UF) systems, and nano- filtration ( F) systems, as well as in cross-flow or dead end applications.

Referring to Figure 1, a conventional cross-flow filtration system 10 is depicted m simplified form. The system 10 represents a system that may be used in a conventional reverse osmosis membrane filtration, MF, UF or NF desalination system,

The system 10 generally receives feedwater 12 from a feedwater source, such as seawater or an aquifer or any other relevant fluid source, by way of an inlet pipe 11 where it is pumped by pump Pi at a predetermined pressure, into the filtration unit 14. The predetermined pressure at which the feedwater is supplied by the pump PI may vary depending upon the feedwater properties, with a pressure of around 6000 kPa being typical for a seawater desalination application. The feedwater 12 has particulate or dissolved matter 13 contained therein, which may be in the form of suspended particulate matter, dissolved matter, microorganisms and the like, depending upon the source of the feedwater being processed.

The filtration unit 14 may take a variety of forms, but generally comprises a main body 15 which houses one or more filter mediums 16 therein. In a preferred form the filter medium 16 may be a porous membrane, and for simplicity, a porous membrane will be referred to in the preferred embodiments discussed below. Generally, the term "membrane" may be considered to refer to any material having openings or pores satisfactory for use in separating particulate or dissolved matter from a fluid. However, it will be appreciated that the filter medium may include conventional polymer membranes as well as woven, non-woven materials and other plastic films suitable for such a purpose. The pressurised feedwater 12 typically enters the main body 15 of the filtration unit 14 and passes across the membrane 16 in a tangential direction, as is shown in Figure 6. The membrane 16 comprises pores 17 formed therein that permits fluid flow therethrough. Due to the positive pressure of the introduced feedwater 12 in relation to the other side of the membrane 16, fluid is caused to pass through the membrane 16 with all particulate or dissolved matter 13 having a size greater than the size of the pores 17 remaining on the feed side of the membrane or filter media 16 and all else passing through the membrane as permeate 19. By controlling the size of the pores 17 to capture the particulate and dissolved matter 13 present in the feedwater 12, substantially pure water 18 is typically collected as it passes through the membrane or filter 16 and stored in collection reservoir 19.

Due to the cross-flow nature of the filtration system 10, wastewater 20 exits the filtration unit 14 for recirculation back into the filtration unit 14 by way of return pipe 21, An additional pump P2 may be employed to assist in pressurising the wastewater 20 as shown. In the embodiment of the system 10 shown in Figure 1, the wastewater 20 is continually circulated with the feedwater 12 until processed into pure, or substantially pure, water collected in reservoir 19. Whilst not shown, it will be appreciated that an amount of wastewater 20 will be continually removed from the system and sent to a waste collection means.

As is shown in Figure 6, particulate and/or dissolved matter 13 present in the feedwater 12 (and recirculated wastewater 20) may crystallise or otherwise deposit on the surface of the membrane 16 or in the pores 17 of the membrane 16. The particulate or dissolved matter 13 may include a variety of contaminants, such as solutes, colloids and suspended compounds and often includes calcium, magnesium, iron, silica, clay, organic matter and other elements and compounds. The type and extent of particulate matter 13 present in the feedwater 12 may depend upon the source of the feedwater 12.

Once the particulate or dissolved matter 13 becomes deposited on the membrane or filter, fouling or scaling can occur by the particulate or dissolved matter blocking the pores 17 preventing, or significantly restricting, the flow of fluid through the membrane or filter 16. Such fouling or scaling reduces the efficiency of the system 10 leading to increases in energy requirements of the system due to the reduced flow of water and the need for higher pressures to produce the same volume of pure water. Typically, when fouling or scaling occurs, as represented in Fig. 6, there is a need to implement one of a variety of different regeneration techniques, to return the system to an efficient operation state. Such regeneration techniques may include removing and cleaning the membrane 16, o replace the membrane 16, implementing backwashing cycles to flush out the pores 17, or employ a chemical cleaning process. Typicall regeneration techniques are employed to treat fouling and scaling as an accepted part of the process, rather than prevent fouling or scaling from occurring in the first instance, and most regenerative techniques require system shut down which can expose maintenance staff to contaminants and which reduces tihe efficiency of the system.

The system of the present invention addresses this problem by employing a system that prevents fouling or scaling of the filter medium or membrane 16 and removes the foulants or sealants from the surface of the filter medium as the feedwater passes through the filtration unit 14.

This is achieved by providing a generator 30 located in the return pipe 21 that receives the wastewater 20 flowing from the filtration unit 14, as shown in Figure 1. As the wastewater 20 exits the filtration unit 14 under pressure, there is significant energy present therein. The generator 30 utilises this otherwise wasted energy to convert the energy into vibration energy present within the wastewater which can pass through the wastewater and back into the filtration unit 14. In essence, the generator 30 is a device that is positioned in fluid communication with the fluid passing through the filtration unit and which creates an oscillating pressure fluctuation in the fluid and across the membrane or filter 16 surface so as to minimise or substantially prevent the contaminants present in the feedfluid from collecting on the surface of the membrane,

Referring to Figure 7, the generator 30 can be configured to produce subsonic, sonic or ultrasonic oscillating pressure waves in the feedwater 12. This creates oscillating pressure fluctuating waves 24 within the feedwater 12 as the feedwater flows within the pipe 11. Such fluctuating wave energy 24 may act to tear the liquid apart b inducing cavitation and other effects within the flow of feedwater 12 (and recycled wastewater 20) as it passes through the filtration unit 14.

Due to the cavitation and other effects experienced within the feedwater 12 (and recycled wastewater 20) created by the generator 30, the surface laminar layer of feedwater passing over the surface of the membrane 16 is disturbed or retained in constant motion, thus exhibiting turbulent flow and preventing or substantially reducing the occurrence of fouling or scaling of the membrane 16.

The generator 30 acts to apply the vibration waves to the feedwater 12 (and circulating wastewater 20) in situ such that fouling, rusting, scaling, concretions or any other accretions are reduced during use of the system. The presence of such vibration energy within the feedwater 12 (and wastewater 20) is able to release foulants, scale and particulate material from the surface of the membrane 16 and the pores 17 to be removed with the exiting wastewater 20.

One embodiment of a generator 30 suitable for use with the present invention is shown in Figures 2 and 3.

As is shown in Figure 3, the generator 30 is directly connected to the return pipe 21 so as to receive the wastewater 20 exiting from the filter unit 1 . The wastewater 20 is received at pressure which provides energy to power the generator 30 as the pressurised wastewater 20 passes therethrough, As the wastewater exits the generator 30 it is collected and returned back into the return pipe 21 for delivery back into the filter unit 14. As mentioned previously, a pump member P2 may be provided with the return pipe to provide pressure to the wastewater as required. The generator 30 thus generates a wave shaped energy 40 created by oscillating pressure fluctuation within the wastewater 20 which is able to flow back along the return pipe 21 so as to travel through the fluid present within the filter unit 14.

Referring to Figure 2, the manner in which one embodiment of a generator 30 can be constructed is shown. The generator 30 comprises a body 32 which is mounted to the return pipe 21 such that the wastewater 20 is delivered centrally into the body 32. In the embodiment as shown in Figure 2, the body 32 is substantially cylindrical; however, it will be appreciated that the body 32 may take a variety of forms. A pair of egress pipes 33 are provided on opposing sides of the body to provide an egress path for the wastewater 20 to exit the body 32 of the generator 30,

Mounted within an internal space 35 of the body 32 is a turbine or rotor 36. The turbine or rotor 3 has a plurality of blades 34 which are configured such that the ends of the blades 34 extend for a distance along the internal surface of the body 32. Each of the blades 34 extend through the internal space 35 of the body 32 to define a plurality of internal compartments within the space 35. As the turbine is mounted centrally within the space 35, wastewater 20 entering the body 32 under pressure contacts a vane 24a provided on each of the blades 24 to cause the turbine 36 to rotate. As the turbine 36 rotates, the blades act to open and close the egress pipes 33 such that the wastewater 20 exits the body 32 at staggered intervals, thus generating the vibration wave energy 40 within the wastewater 20. Due to the nature of the turbine 36 and the number and arrangement of the blades 34, the wave energy generated within the wastewater 20 typically resembles a square wave.

An alternative arrangement of a generator 50 for use with the present invention is shown in Figures 4 and 5. Referring firstly to Figure 4, the generator 50 is mounted in the return pipe 21 so as to receive the wastewater 20 as it exits from the filtration unit 14 under pressure. However, it will be appreciated that the generator 50 may also be mounted in the feedpipe 11 where it is driven by the feedwater under pump PI.

The generator 50 comprises a rotating cylinder member 52 received within a static cylinder member 56. The rotating cylinder member 52 receives the wastewater 20 directly from the return pipe 21 such that the wastewater flows into the rotating cylinder member 52 which is free to rotate about its central axis. The rotating cylinder member 52 has a plurality of vanes 53 formed along an internal surface thereof, which cause the rotating cylinder member 52 to rotate as the wastewater 20 flows therein, The distal end of the rotating cylinder member 52 is provided with an egress means, such as a plurality of slots 54 which provide a path for wastewater 20 to flow from the rotating cylinder member 52.

The rotating cylinder member 52 is free to rotate within the static cylinder member 56. In this regard, the static cylinder member 56 snugly receives the rotating cylinder member 52 therein through an open end thereof. The opposing end of the static cylinder member 56 has a closed end. A plurality of slots 57 are formed adjacent the closed end and are spaced apart so as to substantially align with the slots 54 formed in the rotating cylinder member as me rotating cylinder member 52 rotates under action of the wastewater. When the slots 57 align with the slots 54 of the rotating cylinder member 52, wastewater is free to flow from the rotating cylinder member 52 and through the static cylinder member 56 where it is collected for delivery back into the filtration unit 14 by way of the return pipe 21. Conversely, when the slots 54 of the rotating cylinder member 52 do not align with the slots 57 of the static cylinder member 56, no wastewater flows from the rotating cylinder member 52. In this instance there is a sudden build up of pressure in the wastewater 20. Thus, the generator 50 functions to generate an oscillating pressure fluctuation within the fluid. This may be in the form of a wave of energy that travels through the wastewater 20, thus acting to increase turbulent flow of the wastewater in the filtration unit 14 to reduce the likelihood of particulate matter or dissolved matter crystallising or otherwise collecting on the surface of the membrane.

It will be appreciated that the generator of the present invention may be locally or remotely controlled by a computer controller or logic controller operating under system software. In such an arrangement an amplifier may be employed to control the amplification and intensity of the energy delivered by the generator, as well as the duration and regularity of such energy. It will be appreciated that the method and system of the present invention is directed at utilising the waste energy of existing treatment systems to prevent or reduce the fouling of components and pipes within the systems whilst maintaining high flux and low membrane pressures thus resulting in less power consumption to produce a given volume of treated water. Such a system and method will significantly reduce energy requirements and operating costs and reduce the costs associated with conventional membrane and filter cleaning treatments, particularly those employing costly cleaning and antiscalant chemicals.

It will be appreciated that by reducing the occurrence of membrane or filter fouling in the first instance, any chemical cleaning that may be required during the life of a treatment system, will be safer for operators, quicker and less expensive and less labour intensive. Further, the present invention will significantly prolong the life of membranes and filters and reduce replacement costs whilst increasing efficiencies of the water treatment plants, The system of the present invention may be readily fitted to existing systems without significant cost or redesign.

Throughout the specification and claims the word "comprise" and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word "comprise" and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

Orientational terms used in the specification and claims such as vertical, horizontal, top, bottom, upper and lower are to be interpreted as relational and are based on the prernise that the component, item, article, apparatus, device or instrument will usually be considered in a particular orientation, typically with the generator uppermost.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the invention.

Claims

The claims defining the invention are as follows:

1. A system for reducing fouling or scaling of a filter medium in a fluid filtration system comprising:

a fluid source for supplying a feedfluid having contaminants suspended therein;

2. A system according to claim 1, wherein the generator device generates an oscillating pressure fluctuation within the feedfluid so as to prevent or substantially minimise contaminants separated from said feed fluid from collecting on a surface of the filter medium.

3. A system according to claim 1, wherein the generator device is located either upstream or downstream of the filter unit

4. A system according to claim 3, wherein the generator device receives the feedfluid and generates the pressure fluctuation therein by controlling the flow of feedfluid therethrough.

5. A system according to claim 4, herein the generator device is configured to both permit and restrict the flow of feedfluid therethrough in a changing manner, thereby generating an oscillating pressure fluctuation within the feedfluid.

5. A system according to claim 5, wherein the generator device comprises a rotor member mounted within a body having at least one egress means for permitting the flow of feedfluid therefrom, the rotor member being configured to be driven by the feedfluid as the feedfluid passes therethrough.

6, A system according to claim 5, wherein the rotor member comprises plurality of blades configured to open and close the at least one egress means as the rotor member rotates within the body, thereby generating the oscillating pressure fluctuation within the feedfluid,

7. A system according to claim 1, wherein at least one pump is provided in fluid communication with the fluid source to supply the feedfluid to the filter unit under ressure.

8. A system according to claim 1, wherein the filter medium is a porous 5 membrane having a plurality of pores formed therein for separating contaminatea from the feedfluid.

9. A system according to claim 1, wherein the filter unit comprises an outlet for permitting the egress of feedfluid therefrom.

10. A system according to claim 9, wherein the generator device is in fluid io communication with the outlet so as to receive the feedfluid as it exits the filter unit.

11. A generator device for generating an oscillating pressure fluctuation within a feedfluid of a fluid filtration system, comprising:

a body having at least one inlet for receiving the feedfluid and at least one 1$ outlet for releasing the feedfluid therefrom; and

a fluid control device mounted within the body and configured to control the flow of feedfluid from the at least one inlet to the at least one outlet; wherein the fluid control device is provided within the path flow of the feedfluid so as to be driven by the feedfluid passing through the body and the 20 oscillating pressure fluctuation within the feedfluid is generated by the fluid control device functioning to open and close the at least one outlet.

12. A generator device according to claim 11, wherein the feedfluid is provided to the body under pressure from a filter unit of the fluid filtration system.

13. A generator device according to claim 11, wherein the feedfluid to provided 25 to the body under pressure from a fluid source.

14. A generator device according to claim 11, wherein the fluid control device is rotatably movable within the body under action of the received feedfluid.

1 . A generator device according to claim 14, wherein the fluid control device is configured to open and close the at least one outlet as it rotates within the w body, thereby generating said oscillating pressure fluctuation within the feedfluid.

16. A generator device according to claim 15, wherein the fluid control device comprises a rotor having one or more blades extending therefrom that control access of the feedfluid to the at least one outlet as the blades rotate within the body.

s

17. A method of method of reducing fouling or scaling of a filter medium in a fluid filtration system comprising:

separating a permeate from the feedfluid through drawing said permeateo through the filter medium in fluid communication with the feedfluid, the permeate being a constituent of the feedfluid substantially free of said contaminants;

collecting said permeate; and

18. A method according to claim 17, wherein the step of generating an oscillating pressure fluctuation within the feedfluid comprises passing the feedfluid0 through a generator device such that the energy associated with said feedfluid generates said oscillating pressure fluctuation.