WO2005081627A2 - Crossflow filtration system and method for membrane fouling prevention - Google Patents

Abstract

Methods and systems for fluid filtration via semipermeable membranes is provided with means for their fouling prevention. An improved conventional filtration system includes a pressure pump (24), a membrane module (28), an inlet port (30), a concentrate outlet (36) and a filtrate outlet (34). The membrane is cleaned by applying an additional reciprocal fluid pulse to the fluid passing through the module which is achieved via a corresponding supplementary means: pressure pumps (42, 44, 46), diaphragm cylinders (78, 80, 82), piston-type thrust cylinders, hydraulic cushions (90, 92, 94) or hydraulic cylinders (66, 68, 70). Each of them having an individual actuator (48, 50, 52) associated with a control system (54).

Description

CROSSFLOW FILTRATION SYSTEM AND METHOD FOR MEMBRANE FOULING PREVENTION

BACKGROUND OF THE INVENTION

fθtHKE} (ϊ) Field of the Invention

002} The present invention relates to filtration of fluids, in particular,

to filtration of fluids via se ipermeabϊe membranes. rø3} (2) Background of fee Invention

{0004J For purification of fluids, in particular, in water treatment, in

natural water treatment, in industrial and agricultural wastewater

treatment, there are widely used various meambranes. Fluid filtration

through a membrane is perforemed on "cross and flow" principle. That is,

the stream delivered by a pressure pump moves parallel with the

membrane. Part of this stream passes through the membrane. This is the

purufied fluid. The remaining part of this stream carrying impurities and

named concentrate further moves parallel with the membrane and leaves

its surface. There are known membranes for various purposes. In

particular;, membranes for removing suspended particles and large

colloids while macromolecules and dissolved solids pass through them -

this technology is named mϊcrofiltration (MF) and membranes for

macromolecular separation while dissolved salts and small molecules

pass through them, this technology is named ultrafiltratϊon (UF), and the

membranes themselves - respectively MF-membranes or UF-membranes

(see U.S. Pats. 6,197,203 and 5,132,015 or EP 0479492 AI). There are

further known membranes for removing from a fluid all dissolved salts

and inorganic molecules as well as organic molecules. Water molecules

pass f eely through them. This technology is called reverse osmosis (RO) and membranes - RO-membranes, (see U.S. Pats. 6,604,914; 5,132,017;

5,131,277; 5,122,265; 5,096,574; and 4,814,086).

fββθSj Fluid filtration through a membrane is not perfect, as the

membranes themselves are fouled during operation both by mechanical

impurities, and by salts by deposition of foreign matter on the membrane

surface. As a result, the membrane capacity is reduced, the pressure at the

inlet to the membrane increases and the permeate quality deteriorates.

Unless measures are taken in time to clean the membrane, it is heavily

fouled or scaled and may be damaged by fluid pressure.

fOO J Measures conventionally taken for prevention of membrane

fouling or for cleaning membranes already fouled are expensive and, as a

rule, not sufficient enough. Among these we find, for example,

preliminary water treatment (see U.S. Pat. 5,034,121), which require high

capital outlays in combination with high operating costs, that is,

corresponding plants, chemicals, reagents, etc. are needed. To prevent

membrane fouling by salts or substances forming deposits or films on the

membrane surface, special expensive chemical or biological substances

are added to a filtered fluid (see U.S. Pat. Appl. 2002/0036168 Al, U.S.

Pats. 4,921,610 and 5,403,479), which cannot fully eliminate membrane

fouling and compensate their capacity reduction. Therefore, when the membrane capacity is reduced and pressure at its inlet increases, the

membrane is washed directly on the spot of its location by chemical

solutions or blown through by gas (see U.S. Pats. 4,207,183 and

6,641,733). This process is named **CIP cleaning in place". Such methods

of membrane cleaning also cause an increase in additional costs and

creation of aggressive waterwastes. Besides, all these methods are often

not efficient enough or efficient only for a short period of time. As a

result, it is necessary to replace the used membranes by new ones,

\ W1] The main cause of foulant deposition on the membrane surface is

the inadequate turbulance of a fluid stream passing through the membrane

module due to design peculiarities of fee filtering membrane element. A

conventional diagram of a device for fluid filtration is shown in FIG. 1.

Device 1 includes a pressure pump 2, membrane module 4 wife ports : 6

- for feed entrance (F), 8 - for exit of concentrate (C) and 10 - for exit of

the permeate (P). Besides devices are known (FIG. 2) comprising a

pressure pump 2, membrane module 4 with ports: 6 -for entrance of feed

(F), 8 - for exit of concentrate (C ) and 10 - for exit of permeate (P). Part

of the concentrate stream returns to the inlet 6 of membrane module 4 to

increase the stream velocity within the membrane, which allows to slow

its fouling (see U.S. Pat. 4,961,851). There are also known devices

(FIG.3) having means for changing from time to time the direction of the feed stream passing through membrane module 4 - in this case, valve 12,

which allows to reduce the membrane fouling (U.S. Pat. 5,690,829). At

last, there are known devices for cleaning membrane modules using

methods for vibration or ultrasonic cleaning (see U.S. Pat. 5,919,376).

{0008} A disadvantage of aforesaid devices and methods is quick

membrane fouling which causes its capacity reduction, deterioration of

permeate quality and, finally, membrane failure. Besides, the return of

part of the concentrate to membrane inlet (recirculation) requires an

increase of pressure pumps capacity, causes an increased concentration of

impurities at the membrane inlet which also increases the membrane

loading. Other methods, such as vibration or based on electric effects are

complicated, expensive and of low efficiency. Besides, they require fee

use of special membranes (see U.S. Pat. Appl. 2003 0155314, U.S. Pats.

6,241,485; 5,985,160 and 4,830,642).

{0009} (3) Description of the Prior Art

pβlO] Closest to the claimed object are devices and methods disclosed

in US Pat. 6,168,714; 6,423,230; 6,322,698 and U.S. patent application

2001/0000895. OIII Rios, Luis et al. in U.S. Pat. 6,322,698 describe a vibratory

separation system having a drive mechanism for imparting a vibratory

motion to a membrane module to enhance filtration. The membrane

module comprises one or more filter elements secured to one another,

each having a permeable membrane. The vibratory motion imparted to

the membrane module generates a dynamic flow boundary layer at the

permeable membranes. This fluid shear boundary layer, in turn, generates

lift, thereby inhibiting fouling of the membranes.

{00I2J Aforesaid vibration system has some disadvantages: it is

complicated, expensive and is of low capacity. Besides, it also requires

the use of special membranes.

P013J Ilias, Shamsuddin et al. in U.S. Pats. 6,168,714; 6,423,230 and

U.S. Pat. Appl. 2001 0000895 describe a filtration system for a cross-

flow membrane filter which reduces the deleterious effects of

concentration polarization and membrane fouling, thereby increasing the

average transmembrane flux. The filtration system includes a feed supply

for providing a feed solution; a feed pump connected to the feed supply; a

cross-flow membrane filter connected downstream of the feed pump for

separating the feed into a permeate and a reteπtate, the cross-flow

membrane filter including at least two membrane ports and at least two permeable outlets; a valve manifold assembly located between fee feed

pump and fee cross-flow membrane filter; and a control system for

controlling fee valve manifold to selectively reverse fee flow of fee feed

ferough the cross-flow membrane filter. Periodic reversal of the direction

of Sow of the feed stream in the membrane module, while mamtaining

the cross-flow, keeps the system in a hydrodynamically transient state

and prevents the formation of an undesirable stable boundary layer at fee

membrane surface thereby increasing fee average transmembrane flux.

{0014} A disadvantage of aforesaid device is that fee returnn of part of

the concentrate to fee membrane inlet (recirculation) requires an increase

m capacity of pressure pumps, causes increased concentration of

impurities at the membrane inlet, which also increases membrane

loading. This may finally result in reduction of membrane capacity and its

failure.

{0015} An object of the present invention is the prolongation of

membrane life by reducing the level of their fouling salination and an

increase in membrane capacity, and increasing thereby the life of the

whole filtering equipment. {0016} Another object of the invention is a reduction of quantity of

energy and chemical substances added during the filtration process,

reduction in bacterial fouling of membranes.

{0017} Still another object of the invention is reducing the quantity of

aggressive wastes generated in fee process of filtration and enhancing the

effect of fluid demineralization.

SUMMARY OF THE INVENTION

{0018} The subject matter of the present invention is a crossflow

filtration system for prevention of foulng of the membrane surface. The

system comprises a pipe-line for feeding a fluid to be cleaned, a pressure

pump connected via a hydraulic line with fee pipe-line for feeding the

fluid to be cleaned. The system also comprises a membrane module

having an inlet connected via a pressure line wife fee pressure pump, and

two exits, the first whereof serves for removing cleaned fluid, and fee

second - for removing waste concentrate. This membrane module serves

for separating a feed stream into a fluid and concentrate containing

impurities. Besides, the system includes a pipe-line for cleaned fluid

connected with fee first exit of fee membrane module, as well as a pipe¬

line for removing waste concentrate connected with fee second exit of this membrane module. At last, the system contains means for applying

an additional reciprocal fluid pulse to the fluid passing through the

membrane module, and pipe-lines connecting said means wife this

membrane module.

{0019} Besides aforesaid devices, the suggested system for membrane

fouling prevention is provided wife a control system controlling the

operation of the pressure pump, membrane module, means for applying

an additional reciprocal fluid pulse to fee fluid passing through fee

membrane module. This control system contains at least one

microprocessor or at least one controller.

{0020} Means for applying an additional reciprocal fluid pulse to fee

fluid passing ttøougfr the membrane may contain pressure pumps. These

may be gear-type, diaphragm, lobe or piston pumps. Each of these pumps

has an individual actuator. All pump actuators are connected wife the

control system.

{0021} In another embodiment of the suggested system means for

applying an additional reciprocal fluid pulse to fee fluid passing through

the membrane module may contain diaphragm cylinders, piston type

thrust cylinders or hydraulic cushions. Each of these diaphragm cylinders, piston type thrust cylinders or hydraulic cushions has an

individual actuator. AH actuators of these diaphragm cylinders, piston

type thrust cylinders or hydraulic cushions are associated with fee

control system.

{0022} In still another embodiment of fee suggested system means for

applying an additional reciprocal fluid pulse to the fluid passing through

fee membrane module may contain hydraulic cylinders, in particular,

three hydraulic cylinders, the one whereof is connected with fee first exit

of the membrane module, fee second — with the second exit of the

membrane module, and the third - with the inlet of this membrane

module and with fee pressure line. AH these hydraulic cylinders may be

connected together to form a single unit. Each of the hydrualic cylinders

is provided with an individual actuator. AH actuators of the hydraulic

cylinders are associated with said control system.

{0023} And in the last embodiment of fee suggested system at least one

of the means for applying an additional reciprocal fluid pulse to the fluid

passing through the membrane module, is provided with an individual

actuator and a hydraulic control device, having an autonomous actuator,

is connected wife the input and one of the outputs of the membrane

module or with both outputs of this membrane module. This means actuator and an autonomous actuator of the hydraulic control device are

connected wife fee contol system.

{0024} Another subject matter of the invention is a method for membrane

fouling prevention by applying an additional reciprocal fluid pulse to fee

fluid passing through the membrane via corresponding means,

substantially pressure pumps, diaphragm cylinders, piston type thrust

cylinders, hydraulic cushions or hydraulic cylinders, each of them

provided with an individual actuator associated wife fee control system.

This method comprises fee following steps: i) applying an additional

reciprocal fluid pulse to the fluid fed into fee membrane module through

fee inlet; li) applying an additional reciprocal fluid pulse to the fluid

removed from the membrane module through fee first exit; iii) applying

an additional reciprocal fluid pulse to the fluid removed from the

membrane module through the second exit and, finally, iv) repeating

steps (I), (Li), pii) in certain succession and combination until the

oscillations of fluid stream through the membrane reach the desired level.

Thereby, feere ϊs generated in the membrane module a controlled fluid

motion in all directions which prevents membrane fouling and formation

of a boundary concentrate layer on said membrane surface. {0025} In performing fee suggested mefeod, pressure pumps, diaphragm

cylinders, piston type thrust cylinders, hydraulic cushions or hydraulic

cylinders can operate in antiphase. In this case, pressure pumps,

diaphragm cylinders, piston type thrust cylinders, hydraulic cushions or

hydraulic cylinders can generate a hydraulic wave in the fluid passing

through the membrane module.

{©026} In performing the suggested mefeod fee control system can

change the direction and velocity of streams at fee exits of pressure

pumps, diaphragm cylinders, piston type thrust cylinders, hydraulic

cushions or hydraulic cylinders. Besides, the control system can change

mutual relation of fluid streams at the exits of pressure pumps, diaphragm

cylinders, piston type thrust cylinders, hydraulic cushions or hydraulic

cylinders as to fee value, direction of these streams or their phase.

Besides, ϊt is possible to generate a mode in which only one or two

pressure pumps, diaphragm cylinders, piston type thrust cylinders,

hydraulic cushions or hydraulic cylinders can operate simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

{0027} The invention will now be described in conjunction with the

following drawings in which like reference numerals designate like

elements and wherein:

{0028} FIG. 1 - 3 show schematic diagrams of known devices for

cleaning of fluids ( Prior Art);

{0029} FIG. 4 shows a schematic diagram of fee suggested system using

pressure pumps for applying an additional fluid pulse to fee fluid;

{0030} FIG. 5 shows a schematic diagram of the suggested system using

hydraulic cylinders for applying an additional fluid pulse to the fluid;

{0031} FIG. 6 shows a schematic diagram of the suggested system using

diaphragm cylinders for applying an additional fluid pulse to the fluid;

{0032} FIG. 7 shows a schematic diagram of fee suggested system using

hydraulic cushions for applying an additional fluid pulse to the fluid. {0033} FIG, 8 shows a schematic diagram of the suggested system using

means for applying an additional reciprocal fluid pulse, which is provided

wife an individual actuator and a hydraulic control device with an

autonomous actuator

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

{0034} The preferred embodiments of the present invention are described

below. The inventors of fee present subject matter contemplate feat the

embodiments described herein are capable of use in the repair of other

vessels and in other procedures. Thus, it is intended feat the present

invention cover the modifications and variations of the invention,

provided they come within fee scope of the appended claims and their

equivalents.

{0035} The most preferred embodiment of an apparatus, according to the

present invention, are shown in drawing figures 4-8.

{0036} The suggested system 20 for preventing the fouling of a

membrane surface (FIG. 4) comprises a pipe-line 22 for feeding a fluid

to be cleaned, as well as a pressure pump 24 associated via a hydraulic

line wife pipe-line 22 for feeding a fluid to be cleaned and a membrane 26 enclosed in a body - membrane module 28. Membrane module 28

has an inlet 30 connected via a pressure hydraulic line 32 with pump 24,

as well as two exits, 34 and 36 respectively, fee first whereof, 34 serves

for removing the cleaned fluid, and fee second, 36 - for removing the

concentrate. Membrane 26 serves for the separation of feed into pure

fluid and concentrate containing impurities. Besides, system 20 includes a

pϊpe-Iine 38 for cleaned fluid connected wife the first exit 34 of

membrane module 28, as well as a pipe-line 40 for removing the

concentrate connected with the second exit 36 of membrane module 28.

{0037} At last, system 20 comprises means for applying a reciprocal

fluid pulse to the fluid passing through membrane 26 containing pressure

pumps, diaphragm cylinders, piston type thrust cylinders, hydraulic

cushions or hydraulic cylinders, as well as pipe-lines connecting said

means with membrane module 28.

{0038} In fee first embodiment of suggested system 20 means for

applying an additional reciprocal fluid pulse to the fluid passing through

membrane 26 located in membrane module 28 contain pressure pumps,

42, 44, 46 respectively (FΪG.4). There may be gear-type, diaphragm, lobe

or piston pumps. Each of these pumps is provided with an individual

actuator, 48, 50 and 52 respectively. All actuators 48, 50 and 52 of pumps 42, 44, 46 are associated with fee control system controlling fee operation

of pump 24, membrane 26 and membrane module 28, means for applying

an additional reciprocal fluid pulse to fee fluid passing through the

membrane, in this embodiment - 42, 44, 46. This control system contains

at least one microprocessor 54 (FIG, 4) or at least one controller 56 (FIG.

5).

{0039} In the second embodiment of suggested system 20 (FIG.5) means

for applying an additional reciprocal fluid pulse to the fluid passing

through membrane 26 contain hydraulic cylinders, in particular, three

hydraulic cylinders 66, 68, 70, one whereof 68 is connected with the first

exit 34 of membrane module 28, the second 70 — with the second exit 36

of membrane module 28, and fee third 66 - with inlet 30 of membrane

module 28 and with pressure line 32. AH these hydraulic cylinders 66, 68

and 70 may be connected together to form a single unit. Each of hydraulic

cylinders 66, 68 and 70 has an individual actuator, 72, 74 and 76

respectively. AH actuators 72, 74 and 76 of hydraulic cylinders 66, 68,

and 70 are associated wife said control system 54 (56).

{0040} In the third embodiment of suggested system 20 (FΪG.6) means

for applying an additional reciprocal fluid pulse to fee fluid passing

through membrane 26 contain diaphragm cylinders, in particular, three diaphragm cylinders 78, 80, 82, one whereof 80 is connected wife the

first exit 34 of membrane module 28, the second 82 - with the second

exit 36 of membrane module 28, and the third 78 - with inlet 30 of

membrane module 28 and with pressure line 32, AH these diaphragm

cylinders 78, 80 and 82 may be connected together to form a single unit.

Each of diaphragm cylinders 78, 80 and 82 is provided with an individual

actuator, 84, 86 and 88 respectively. AH actuators 84, 86 and 88 of

diaphragm cylinders 78, 80 and 82 are associated with said control

system 54 (56).

{0041} In fee fourth embodiment of suggested system 20 (FIG.7) means

for applying an additional reciprocal fluid pulse to fee fluid passing

through membrane 26 contain hydraulic cushions (or piston type thrust

cylinders), in particular, three hydraulic cushions (or piston type thrust

cylinders) 90, 92, 94, one whereof, 92 is connected with the first exit 34

of membrane module 28, the second 94 - with fee second exit 36 of

membrane module 28, and the third, 90 - with inlet 30 of membrane

module 28 and wife pressure line 32. AH these hydraulic cushions (or

piston type thrust cylinders) 90, 92 and 94 may be connected together to

form a single unit. Each of hydraulic cushions (or piston type thrust

cylinders) 90, 92 and 94 is provided wife an individual actuator, 96, 98 and 100 respectively. AH actuators 96, 98 and 100 of hydrauKc cushions

90, 92, 94 are associated wife said control system 54 (56).

{0042} And in the last embodiment of suggested system 20 (FIG. 8), the

means for applying an additional reciprocal fluid pulse to fee fluid

passing through membrane 26 located in membrane module 28 contain

pressure pumps, 102, 104, 106, 108 respectively (FIG.8). These may be

gear-type, diaphragm, lobe or piston pumps. Each of these pumps Is

provided wife an individual actuator, 110, 112, 114 and 116 respectively.

The pressure pump 108 has an individual actuator 116 and an individual

hydraulic control device 118 with an autonomous actuator 120. AH

actuators 110, 112, 114 and 116 of pumps 102, 104, 106, 108 as well as

an individual hydraulic control device 118 with its autonomous actuator

120, are associated with fee control system 54 (56) controlling the

operation of pump 24, membrane 26 and membrane module 28, means

for applying an additional reciprocal fluid pulse to fee fluid passing

through fee membrane, in this embodiment - pumps 102, 104, 106, 108.

This control system contains at least one microprocessor 54 (FIG. 8) or

at least one controller 56.

{0043} Suggested system 20 operates in accordance wife fee suggested

mefeod for membrane 26 fouling prevention. {0044} The conventional system of fluid cleaning operates in a standard

mode by delivering fluid via pressure pump 2 (FIG. 1 - 3) or 24 (FIG. 4 -

8) to membrane 4 or 26. Then the fluid feat has been cleaned is removed

through a corrresponding exit, 10 or 34 of membrane module 28, and the

fouled eca centrate - through another exit of membrane module 28, 8 or

36 respectively.

{0045} According to the suggested method, the claimed system for

membrane 26 fouling prevention (FIG. 4 - 8) acts on fee fluid to be

cleaned by applying thereto an additional reciprocal fluid pulse via

corresponding means, substantially pressure pumps 42, 44, 46, 102, 104,

106, 108 hydraulic cylinders, 66, 68, 70 respectively. The same occurs

when diaphragm cylinders 78, 80, 82, as well as hydraulic cushions 90,

92, 94 or piston type thrust cylinders are used. The method comprises the

following steps: ϊ) applying an additional reciprocal fluid pulse to the

fluid fed to membrane module 28 through inlet 30; H) applying an

additional reciprocal fluid pulse to the fluid removed from membrane

module 28 through first exit 34; Hi) applying an additional reciprocal

fluid pulse to the fluid removed from membrame module 28 through

second exit 36, and, at last, iv) repeating steps (i), (ϋ), (in) in certain

succession and predetermined combination until oscillations of fluid

stream through membrane 26 reach fee desired level and fee control system - microprocessor 54 or central controller 56 issue a corresponding

signal (FIG. 4 - 8). Thereby, in membrane module 28 there is excited a

controlled reciprocal movement of fluid through membrane 26 in aH

directions, which prevents its fouling and, in particular, prevents the

formation of a boundary concentrate layer on the surface of membrane

26.

{0046} In performing the suggested mefeod, pressure pumps 42, 44, 46 ,

hydraulic cylinders 66, 68, 70, diaphragm cylinders 78, 80, 82 or

hydraulic cushions (or piston type thrust cylinders) 90, 92, 94 can operate

in antiphase. In this case, pressure pumps 42, 44, 46, hydraulic cylinders

66, 68, 70, diaphragm cylmders 78, 80, 82 or hydraulic cushions (piston

type thrust cylinders) 90, 92, 94 may excite a hydraulic wave in the

liquid passing through membrane 26.

{0047} In performing the suggested method, the hydraulic control device

118 changes fee direction and velocity of stream, its value and pressure. In this case, the additional pressure pump 108 can create an additional

fluid stream, which changes its value and direction and is imposed on the

basic fluid stream in membrane module 28, changing its direction and

value and so applying an additional reciprocal fluid pulse to the fluid fed

to the membrane module 26. The additional pressure pump 108 with a hydraulic control device 118 Is controlled by actuators 116, 120 and

control system 54 (56) together or separate of the basic pump 24 and

other pumps 102, 104, 106 in definite consecutivϊty and in definite

predesigned pulse combination.

{0048} In performing fee suggested method, the control system -

microprocessor 54 or controller 56 can change the direction and velocity

of streams at fee outlets of pumps 42, 44, 46, 102, 104, 106, 108

hydraulic cylinders 66, 68, 70, diaphreagπi cylinders 78, 80, 82 or

hydraulic cushions (piston type thrust cylinders) 90, 92, 94. Besides, the

control system can change the mutual relation of fluid streams at the

outlets of pumps 42, 44, 46, 102, 104, 106, 108 hydraulic cylinders 66,

68, 70, diaphragm cylinders 78, 80, 82 or hydraulic cushions (piston type

thrust cylinders) 90, 92, 94 as to fee value, direction of these streams or

their phase.

{0049} Application of system 1, as well as performing, on fee basis of

this system, new and improved method of membrane 26 fouling

prevention allows to solve fee problem of increasing fee life of

membranes 26 and their capacity. Besides, it increases fee life of filtering

equipment and reduces capital outlays for this equipment.

Simultaneously, there is reduced fee quantity of aggressive wastes

generated in fluid filtration process. At last, It reduces fee consumption of

energy and chemical substances in the process of fluid filtration.

{0050} While this invention has been described in conjunction with

specific embodiment thereof, it is evident that many alternatives,

modifications and variations will be apparent to those skHIed in fee art.

Accordingly, the preferred embodiments of the invention as set forth

herein are intended to be illustrative, not limiting. Various changes may

be made without departing from fee spirit and scope of the invention as

defined in the following claims.

Claims

A cross .and flow filtø & system for membrane fouling prevention,

comprising: a) a pipe-line for feeding liquid to be cleaned; b) a pressure pump associated via a hydraulic line with the pipe-line for feeding fluid to be cleaned; c) a membrane module, including a membrane enclosed in a body associated via a pressure line with fee pump and two exits, the first whereof serves for removing cleaned fluid, and the second - for removing waste concentrate, this membrane module serves for separating the feed into pure fluid and concentrate containing impurities; d) a pipe-line for cleaned fluid associated with fee first exit of said membrane body; e) a pipe-line for removing waste concentrate connected with fee second exit of said membrane body; f) means for applying an additional reciprocal fluid pulse to the fluid passing through fee membrane module,

whereby ihere are prevented membrane fouling in said membrane module

and formation thereon a boundary concentrare layer.

2. The system of claim I, which Is additionally provided wife a control

system controlling the operation of said pump, membrane module and

means for applying an additional reciprocal fluid pulse to fee fluid

passing tϊrrough the membrane module.

3. The system of claim 2, wherein said control system contains SSL least

one microprocessor.

4. The system of claim 2, wherein said control system contains at least

one controller.

5. The system of claim 1, wherein said means for applying an additional

reciprocal fluid pulse to the fluid passing through the membrane module

may contain pressure pumps.

6. The system of claim 5, wherein said means for applying an additional

reciprocal fluid pulse to fee fluid passing through fee membrane module

contain gear-type pumps.

7. The system of claim 5, wherein said means for applying an additional

reciprocal fluid pulse to the fluid passing through fee membrane module

may contain diaphragm pumps.

8. The system of claim 5, wherein said means for applying an additional

reciprocal fluid pulse to the fluid passing through the membrane module

may contain lobe pumps.

9. The system of claim 5, wherein said means for applying an additional

reciprocal fluid pulse to fee fluid passing through fee membrane module

may contain piston pumps,

10. The system of claim 5 - 9, wherein each of said pumps has an

individual actuator.

11. The system of claim 10, wherein said pump actuators are associated

wife said control system.

12. The system of claim 1, wherein said means for applying an additional

reciprocal fluid pulse to the fluid passing through the membrane module

contain substantϊaHy diaphragm cylinders or piston type thrust cylinders.

13. The system of claim 1, wherein said means for applying an additional

reciprocal fluid pulse to fee fluid passing through fee membrane module

contain substantially hydraulic cushions.

14. The system of claim 12 or 13, wherein each of said diaphragm

cylinders, piston type thrust cylinders or hydraulic cushions has an

individual actuator.

15. The system of claim 14, wherein said actuators of diaphragm

cylinders, piston type thrust cylinders or hydraulic cushions are

associated with said control system.

16. The system of claim 1, wherein said means for applying an additional

reciprocal fluid pulse to the fluid passing through the membrane module

substantially contain hydraulic cylinders.

17. The system of claim 16, wherein said means for applying an

additional reciprocal fluid pulse to the fluid passing through fee

membrane module contain hydraulic cylinders, the one whereof is

connected with said first exit of said membrane module, the second —

with said second exit of the membrane module, and the third - with said

inlet of the membrane module and wife the pressure line.

18. The system of claim 17, wherein said hydraulic cylinders may be

connected together to form a single unit.

19. The system of claim 17, wherein each of said hydraulic cylinders has

an individual actuator.

20. The system of claim 19, wherein said actuators of fee hydraulic

cylinders are associated with said control system.

21. The system of claim 1, wherein at least one of said means for

applying an additional reciprocal fluid pulse to the fluid passing through

the membrane module, is provided wife an individual actuator and a

hydraulic control device, having an autonomous actuator, is connected

with the input and one of the outputs of the membrane module or with

both inputs of the membrane module, and this means actuator and

autonomous actuator of fee hydraulic control device are connected wife

said contol system.

22. A method for membrane fouling prevention by applying an

additional reciprocal fluid pulse to the fluid passing ferough a membrane

module via corresponding means, substantially pressure pumps,

diaphragm cylinders, piston type thrust cylinders, hydraulic cushions or

hydraulic cylinders, each whereof has an individual actuator associated

wife the control system, this mefeod comprises the following steps: i) applying an additional reciprocal fluid pulse to the fluid fed to fee membrane module through the inlet; ϊi) applying an additional reciprocal fluid pulse to the fluid removed from fee membrane module through said first exit; iii) applying an additional reciprocal fluid pulse to fee fluid removed from the membrane module through the second exit; iv) repeating steps (i), (ii), (iii) in definite succession and definite combination until the oscillations of a fluid stream through the membrane module reach a desired level,

whereby in said membrane module there is excited a controlled reciprocal

motion of fluid in all directions, which prevents membrane fouling and

the formation of a boundary concentrate layer.

23. The mefeod of claim 22, wherein said pressure pumps, diaphragm

cylinders, piston type thrust cylinders, hydraulic cushions or hydraulic

cylinders may operate in antiphase.

24. The method of claim 22, wherein said pressure pumps, diaphragm

cylinders, piston type thrust cylinders, hydraulic cushions or hydraulic

cylinders may excite a hydraulic wave in the fluid passing through the

membrane module.

25. The mefeod of claim 22, wherein said control system changes the

direction and velocity of streams at the outlets of these pressure pumps,

diaphragm cylinders, piston type thrust cylinders, hydraulic cushions or

hydraulic cylinders.

26. The method of claim 25, wherein said control system changes the

mutual relation of fluid streams at the outlets of these pressure pumps,

diaphragm cylinders, piston type thrust cylinders, hydraulic cushions or

hydraulic cylinders in fee value of these streams.

27. The method of claim 25, wherein said control system changes fee

mutual relation of fluid streams at the outlet of these pumps, diaphragm

cylinders, piston type thrust cylinders, hydraulic cushions or hydraulic

cylinders in fee direction of these streams.

28. The mefeod of claim 25, wherein said control system changes the

mutual relation of fluid streams at the outlet of these pressure pumps,

diaphragm cylinders, piston type thrust cylinders, hydraulic cushions or

hydraulic cylinders in fee phase of these streams.