WO2002022243A2

WO2002022243A2 - Membrane filter used in water treatment

Info

Publication number: WO2002022243A2
Application number: PCT/EP2001/009789
Authority: WO
Inventors: Klaus Vossenkaul; Stefan Schäfer
Original assignee: Klaus Vossenkaul; Schaefer Stefan
Priority date: 2000-09-13
Filing date: 2001-08-24
Publication date: 2002-03-21
Also published as: AU2002210460A1; DE10045226B4; WO2002022243A3; DE10045226A1

Abstract

The invention relates to a membrane filter used in the treatment of water, comprising a head piece (1) consisting of a permeate collecting chamber (2) with a permeate outlet (3), and at least one bundle of fibres (4) made from capillary membranes (5) which are sealed on one end and are poured onto the head piece on the other side with an open end in relation to said permeate collecting chamber. The capillary membranes (5) are surrounded by untreated water for processing. Clarified liquid flows in the capillary membranes (5) to the permeate collecting chamber. The capillary membranes (5) in the bundle of fibres (4) are secured in a tightly packed manner to a connecting area of the head piece (1) whereby said area is not interspersed with flow channels for the untreated water. A fumigation device (8) through which air exits is arranged inside the bundle of fibres (4).

Description

Process for the production of fabric-reinforced capillary membranes, especially for ultrafiltration

The invention relates to a membrane filter for water treatment

a head piece, which has a per eat collecting space with a permeate outlet, and

at least one fiber bundle made of capillary membranes, which are closed at one end and cast on the other side with an open end to the permeate collection space in the head piece,

wherein the capillary membranes are surrounded by the raw water to be treated and clarified liquid flows out in the capillary membranes to the permeate collection space. The capillary membranes have a diameter of less than 5 mm and preferably have a permeability of microfiltration membranes or ultrafiltration membranes. However, the use of capillary membranes for reverse osmosis or nanofiltration should not be excluded. Capillary membranes in a diameter range between 0.5 and 3 mm are preferred. The driving force for membrane filtration is a pressure difference that can be realized on the raw water side by an overpressure and / or by a pressure reduction on the eat side. A pressure reduction on the permeate side is particularly useful if the membrane filter is to be used in immersion operation and is suspended in a basin containing the raw water, for example the aeration basin of a sewage treatment plant. A membrane filter with the features described above is known from DE-A 198 11 945. The bundle of capillary membranes, also referred to below as the fiber bundle, is inserted into a pressure-resistant jacket tube which is flowed through in the longitudinal direction of the capillary membranes clamped only at one end. The head piece, into which the capillary membranes are cast, is designed as an inflow base and has a large number of holes, which are evenly distributed over the cross section, for the flow of the raw water. In order to prevent cover layers from forming on the outside of the capillary membranes and the micropores of the capillary membranes from becoming clogged, a uniform flow through the membrane filter space at a defined flow rate is required. To improve the exchange of materials, the raw water can be gassed with air before entering the membrane filter room. For diving operations without inflow to the membranes, this is

Membrane filter unsuitable. Another disadvantage is the high energy input, which is associated with the uniform flow through the filter space required for the operation of the membrane filter.

The invention has for its object to provide a membrane filter for water treatment, in which a good mass transfer is guaranteed on the surface of the capillary membranes regardless of the flow to the membranes. The membrane filter should also be suitable for diving operations.

Starting from a membrane filter of the construction described in the introduction, the object is resolves that the capillary membranes of the fiber bundle are attached in a tight packing to a connection surface of the head piece, which is not penetrated by flow channels for the raw water, and that a gassing device is arranged within the fiber bundle, from which air emerges. The emerging air flows through the fiber bundle from the inside to the outside and partly flows out in the longitudinal direction of the capillary membranes. The air supply is preferably carried out intermittently with the aim of cleaning cover layers which have formed on the membrane surface during membrane filtration. The inventive air introduction into the fiber bundle enables a surprisingly effective cleaning regardless of the flow rate of the raw water. In this respect, the membrane filter according to the invention can also be used in immersion operation.

Various options are available for the further configuration of the membrane filter according to the invention. According to a preferred embodiment, the gassing device has a mouthpiece provided with at least one air outlet opening, which extends within the fiber bundle essentially parallel to the capillary membranes and is connected to an air duct arranged in the headpiece. The mouthpiece has, for example, a tubular section with circumferential bores or is designed as an annular gap nozzle from which the air exits radially or at least with a radial movement component. By dimensioning the length of the mouthpiece and by arranging the outlet bores or outlet nozzles, the air can be introduced specifically into the fiber bundle. It also proves advantageous if the mouthpiece is on Check valve that closes when the pressure of the air supply drops.

Another embodiment, which also falls under the teaching according to the invention, provides that the gassing device has an air lance which is centered on the end side of the head piece and has air outlet openings arranged on the circumference inside the fiber bundle. The air lance expediently extends parallel to the capillary membranes within the fiber bundle and dips into the fiber bundle at the freely movable end of the fiber bundle.

The capillary membranes closed at their free end move in the raw water to be filtered because they are clamped at only one end. A basket can be placed on the head piece to limit the lateral movements of the fiber bundle. The basket can be made of rods or, for example, also consist of a tube provided with openings with circumferential soaping. The head piece can also have connection devices for attachment to a frame which can be lowered into a basin containing the raw water. It is within the scope of the invention to form the head piece in a cuboid shape, with the per-flow taking place on a narrow side surface or on the floor. Several of these units can be arranged next to one another in the manner of a filter package, the per drain being expediently connected by a collecting line.

If the membrane filter is used in immersion operation, there are no facilities for inflow of capillary membranes with raw water required. It is also within the scope of the invention to design the membrane filter with a filter space through which liquid flows. The flow through the filter chamber is expediently in the longitudinal direction

I _ j of the capillary membranes, the raw water entering the filter space through bores in the head piece, which according to the invention are arranged concentrically around the gassing device. The capillary membranes are cast into the head piece at an annular connection surface between the gassing device and the liquid-carrying bores. According to a further, particularly advantageous embodiment, the connection surface of the head piece, in which the capillary membranes forming the fiber bundle are cast at the end, is star-shaped, the connection surface filling the annular surface between the gassing device and the concentrically arranged bores and extending into the areas extends between the liquid channels. According to the invention, a fiber bundle is provided which contains the capillary membranes in a very dense packing, the raw water being guided past the fiber bundle on the outside and air being introduced inside the fiber bundle. In all versions, the fiber bundle is preferably arranged vertically in the raw water, the capillary membranes being fixed to the head piece at their lower end and their upper end being able to move in the liquid flow. The air bubbles rise essentially in the interior of the fiber bundle and are not or only slightly entrained by the liquid flowing past the fiber bundle on the outside. In an embodiment of the membrane filter according to the invention with a flow through the filter space, the head piece is expediently detachably connected to a tubular jacket which forms the filter space. In a further embodiment, it is provided according to the invention that the head piece can be connected to the tubular jacket of another identically designed membrane filter on the end face facing away from the fiber bundle, and that the permeate outlet is arranged on the circumference of the head piece. In the embodiment described, several membrane filters can be connected in series as modular units. As a result, the filter area can be variably adapted to the application. The permeate drains on the circumference of the head pieces can be connected to each other by a manifold.

According to a further embodiment according to the invention, a plurality of fiber bundles are connected to the head piece, with each fiber bundle being assigned a gassing device and bores through which liquid flows concentrically surrounding the gassing device. The head piece has separate distribution chambers for water and air, into which holes for water or air ducts open. Chambers are detachably connected to the head piece, each of which contains a fiber bundle made of capillary membranes and through which the raw water flows in the longitudinal direction of the capillary membranes. The design enables a parallel connection of fiber bundles in a very compact arrangement. In the following, the invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. They show a schematic representation

1 to 3 membrane filters according to the invention for water treatment, which can be used in diving operation, each in a longitudinal section,

4 to 6 a membrane filter according to the invention with a filter chamber through which liquid flows,

7 and 8 further configurations of the membrane filter according to the invention.

The basic structure of the membrane filter according to the invention shown in the figures includes a head piece 1, which has a permeate collecting space 2 with a permeate outlet 3, and at least one fiber bundle 4 made of capillary membranes 5, which are closed at one end and with an open end on their other side Permeate collecting space 2 are poured into the head piece 1. The capillary membranes 5 are preferably ultrafiltration membranes or microfiltration membranes, the diameter of which is less than 5 mm. The capillary membranes preferably have a diameter between 0.5 and 3 mm. The capillary membranes 5 are surrounded by the raw water 6 to be treated. The filtration takes place on the basis of a transmembrane pressure difference, which can be generated by an overpressure on the raw water side and / or a negative pressure on the permeate side. The clarified liquid flows out in the capillary membranes 5 to the permeate collecting space 2. The capillary membranes 5 of the fiber bundle 4 are fastened in a tight packing to a connection surface 7 of the head piece, which is not penetrated by flow channels for the raw water. A gassing device 8 is arranged within the fiber bundle 4, from which air emerges. The air supply is preferably carried out intermittently with the aim of cleaning cover layers which have formed on the membrane surface during membrane filtration. In the embodiment shown in FIG. 1, the gassing device 8 has a protruding mouthpiece 10 provided with at least one air outlet opening, which extends within the fiber bundle 4 essentially parallel to the capillary membranes 5 and is connected to an air duct 16 arranged in the headpiece 1 is. The mouthpiece 10 has a tubular section with circumferential bores 11, but can also be designed, for example, as an annular gap nozzle from which the air emerges with a radial orientation. The capillary membranes 5 cast at one end in the head piece 1 are freely movable at their other closed end and perform more or less pronounced lateral movements under the effect of the turbulence prevailing in the raw water and / or the currents occurring in the raw water. To limit the lateral movements, a basket 12 is placed on the head piece 1, which in the exemplary embodiment is formed from rods and rings. A tube can also be used as basket 12, which can be provided with openings.

In the exemplary embodiment in FIG. 2, it is indicated that the head piece 1 is designed as a cuboid element can. A plurality of gassing devices 8 are arranged in the longitudinal direction of the head piece 1 in order to introduce air into the fiber bundle 4. The fiber bundle 4 consists of a dense packing of capillary membranes 5. The head piece 1 is suitable for diving operation and can have connection devices (not shown) for fastening to a frame, which can be lowered into a basin with raw water. The permeate outlet 3 is provided on the narrow end face. In this respect, it is clear that a plurality of the head pieces 1 can be arranged in parallel next to one another.

In the embodiment shown in FIG. 3, the gassing device 8 has an air lance 13 which is centered at the end on the head piece 1 and has air outlet openings 11 arranged on the circumference inside the fiber bundle 4.

In the embodiments shown in FIGS. 4 to 8, the membrane filter has a filter space 14 through which the raw water to be treated flows. The flow into the filter chamber 14 takes place through bores 15 in the head piece 1, which are arranged concentrically around the gassing device 8. FIG. 4 shows a top view of a head piece 1 which has a centrally arranged channel 16 for the supply of air and bores 15 concentrically surrounding the air channel 16 for the raw water. The connecting surface 7 of the head piece 1, into which the capillary membranes 5 forming the fiber bundle 4 are cast at the end, is star-shaped, with an annular surface between the air duct 16 and the liquid-carrying Renden bores 15 is filled and the connection surface extends into the areas between the liquid channels 15. 4 also shows that the capillary membranes 5 are arranged in a very dense packing. The raw water is essentially led past the outside of the fiber bundle and flows out in the longitudinal direction of the capillary membranes 5. Furthermore, the fiber bundle 4 is gassed with air from the inside.

Fig. 5 shows a longitudinal section through the membrane filter in the section plane A-A; 6 shows the longitudinal section in the sectional plane B-B of FIG. 4. It can be seen from the illustrations that the head piece 1 is detachably connected to a tubular jacket which forms the filter space. The connection between the head piece 1 and the connection of the jacket 17 can be established by means of conventional quick-action fasteners, not shown.

By suitable design of the head piece 1, a plurality of membrane filters can be arranged in series one behind the other, as is shown schematically in FIG. 7. The head piece 1 can be connected to the tubular jacket 17 of a further identical membrane filter on the end face facing away from the fiber bundle 4. The permeate drain 3 is arranged on the circumference of the head piece 1. It goes without saying that the permeate outlets of the membrane filter can be connected to a common collecting line.

In the embodiment shown in FIG. 8, a plurality of fiber bundles 4 are connected to the head piece 1, each fiber bundle 4 having a gassing device 8 and the Gassing device are assigned concentrically surrounding bores 15 through which liquid flows. The head piece 1 has separate distribution chambers 18, 19 for water and air, into which the holes 15 for the raw water or air channels 16 open. Chambers are detachably connected to the head piece 1, each of which forms a filter space 14 and contains a fiber bundle 4 made of capillary membranes 5 and the raw water flows through in the longitudinal direction of the capillary membranes 5.

Claims

Claims:

1. Membrane filter for water treatment with

a head piece which has a permeate collection space with a permeate outlet, and

the capillary membranes being surrounded by the raw water to be treated and clarified liquid flowing out in the capillary membranes to the permeate collecting space, characterized in that the capillary membranes (5) of the fiber bundle (4) are packed tightly on a connection surface (7) of the head piece (1) are attached, which is not penetrated by flow channels for the raw water, and that a gassing device (8) is arranged within the fiber bundle (4), from which air emerges.

2. Membrane filter according to claim 1, characterized in that the gassing device (8) has a mouthpiece (10) which is provided with at least one air outlet opening (11) and extends within the fiber bundle (4) essentially parallel to the capillary membranes (5) and is connected to an air duct (16) arranged in the head piece (1).

3. Membrane filter according to claim 2, characterized in that the mouthpiece (10) has a tubular section with circumferential bores (11).

4. Membrane filter according to claim 2, characterized in that the mouthpiece (10) is designed as an annular gap nozzle from which the air exits radially.

5. Membrane filter according to one of claims 2 to 4, characterized in that the mouthpiece (10) has a check valve which closes when the pressure in the air supply drops.

6. Membrane filter according to claim 1, characterized in that the gassing device (8) has an air lance (13) which is centered at the end on the head piece (1) and has circumferentially arranged air outlet openings (11).

7. Membrane filter according to one of claims 1 to 6, characterized in that a basket is placed on the head piece (1), which limits lateral movements of the fiber bundle (14).

8. Membrane filter according to one of claims 1 to 7, characterized in that the head piece (1) has connection devices for attachment to a frame which can be lowered into a basin containing the raw water.

9. Membrane filter according to one of claims 1 to 8, characterized in that the head piece (1) bores (15) for has a flow of the raw water, which is arranged concentrically around the gassing device (8), and that the capillary membranes (5) are connected to the head piece (5) at an annular connection surface (7) between the gassing device (8) and the liquid-carrying bores (15). 1) are cast in.

10. Membrane filter according to claim 9, characterized in that the connection surface (7) of the head piece (1), in which ι_ I the capillary membranes (5) forming the fiber bundle (4) are cast in at the end, is star-shaped, the connection surface (7 ) fills the annular surface between the gassing device (8) and the concentrically arranged bores (15) and extends into the areas between the liquid channels.

11. Membrane filter according to one of claims 9 or 10, characterized in that the head piece (1) is detachably connected to a tubular jacket (17) which forms a filter space (14) through which the capillary membranes (5) can flow in the longitudinal direction.

12. Membrane filter according to claim 11, characterized in that the head piece (1) on the end face facing away from the fiber bundle (4) can be connected to the tubular jacket (17) of a further, identical membrane filter and that the permeate outlet (3) on The circumference of the head piece (1) is arranged.

13. Membrane filter according to one of claims 9 to 10, characterized in that on the head piece (1) several Fiber bundles (4) are connected, with each fiber bundle (4) being associated with a gassing device (8) and bores (15) concentrically surrounding liquid-flowing bores (8), and with the head piece (1) separate distribution chambers (18 , 19) for water and air, into which the bores (15) or air channels (16) open, and that chambers are detachably connected to the head piece (1), each containing a fiber bundle (4) made of capillary membranes and the raw water flows through in the longitudinal direction of the capillary membranes (5).