JPH11197467A - Membrane separator having spiral membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane separator using a spiral membrane module capable of efficiently subjecting raw water to multistage treatment. SOLUTION: Raw water is supplied to the spiral membrane module 41 of a first stage from a raw water pump 40 and the conc. water thereof is supplied to the spiral membrane module 42 of a second stage as it is. In each of the membrane modules 41 and 42, a bag-shaped membrane is wound around a shaft and raw water is supplied from one end surface of the wound member and conc. water and permeated water are separately allowed to flow out from the other end surface thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a membrane separation device such as a microfiltration device, an ultrafiltration device, and a reverse osmosis membrane separation device, and more particularly to a membrane separation device having spiral-type membrane modules installed in multiple stages.

[0002]

2. Description of the Related Art There is known a membrane separation apparatus in which membrane modules are installed in multiple stages, and concentrated water from a front-stage membrane module is introduced into a rear-stage membrane module for treatment. As a membrane module used in such a multi-stage membrane separation device, there is a spiral membrane module in which a separation membrane is wound around the outer periphery of a water collecting pipe.

FIG. 6 is a partially exploded perspective view showing the structure of a conventional spiral type membrane module.

A plurality of bag-shaped separation membranes 2 are wound around the outer periphery of a water collecting pipe 1 via a mesh spacer 3.

[0005] The water collecting pipe 1 is provided with a slit-shaped opening communicating with the inside and outside of the pipe. The separation membrane 2 has a bag shape,
The central part surrounds the water collection pipe 1. A channel material 4 made of a mesh spacer or the like is inserted inside the bag-shaped separation membrane 2, and the inside of the bag-shaped separation membrane (bag-shaped membrane) 2 is a permeated water channel.

[0006] A top ring 6 and an end ring 7 are provided at both ends of a wound body 5 of the bag-shaped membrane 2, and a brine seal 8 is provided around the outer periphery thereof.

The raw water flows into the raw water flow path between the bag-like membranes 2 from the front end face of the wound body 5, flows in the longitudinal direction of the wound body 5 as it is, and concentrates from the rear end face of the wound body 5. Leaked as. While flowing through the raw water flow path, water permeates the bag-like membrane 2 and enters the inside thereof, flows into the water collecting pipe 1, and is taken out of the module from the rear end side of the water collecting pipe 1.

[0008]

The above-mentioned conventional spiral type membrane module has the following problems to be solved.

In order to increase the flow rate of the permeated water in the water collecting pipe 1, it is necessary to increase the diameter of the water collecting pipe 1, but in such a case, the diameter of the spiral membrane module becomes large. The permeated water that has permeated into the bag-shaped membrane 2 flows to the water collecting pipe 1 while spirally flowing through the bag-shaped membrane 2.
The flow resistance in the bag-like membrane 2 is large. Moreover, the flow resistance near the slit portion of the water collecting pipe flowing into the water collecting pipe 1 from the inside of the bag-shaped membrane 2 is large. The flow rate of the raw water flowing through the raw water flow path decreases toward the downstream side. (The flow rate of raw water decreases as much as the raw water is concentrated.)
For this reason, the raw water flow velocity is low in the downstream of the raw water flow path,
Dirt easily adheres.

[0010] An object of the present invention is to provide a membrane separation apparatus for treating raw water in multiple stages by using a spiral membrane module which solves the above-mentioned conventional problems.

Another object of the present invention is to provide a membrane separation apparatus which does not require a pump for pressurizing the concentrated water of the first-stage membrane module and passing the concentrated water to the second-stage membrane module.

[0012]

The membrane separation device of the present invention comprises:
Membrane modules are installed in multiple stages, raw water is passed through the previous membrane module to separate the membrane into permeated water and concentrated water, and this concentrated water is passed through the subsequent membrane module as raw water and concentrated with permeated water. In a membrane separation device that separates a membrane into water, the membrane module is formed by winding a bag-like membrane around a shaft to form a roll, and raw water is supplied from one end surface of the roll, and concentrated water and permeated water are rolled. It is a spiral type membrane module taken out from the other end face of the rotator.

In the membrane separation apparatus of the present invention, only a pump for supplying the membrane module at the most upstream stage is installed as a pump, and the concentrated water of each membrane module is passed as it is to the lower stage membrane module as raw water without passing through the pump. Preferably, it is watered.

The spiral membrane module employed in the membrane separation apparatus of the present invention is a spiral membrane module in which a permeated water flow path material is disposed inside a bag-shaped membrane, and a raw water flow path material is disposed between the bag-shaped membranes. In the type membrane module, the bag-shaped membrane is first,
It is a substantially rectangular shape having second, third and fourth sides, the first, second and third sides are sealed, the fourth side is partially open, and the remainder is It is a closed part, and the fourth
A first side perpendicular to the side of the roll is applied to the shaft to wind the bag-like membrane to form a roll, and the fourth side faces the rear end face of the roll, and the fourth With the second side facing the side facing the front end face of the wound body, the raw water flow path between the bag-like membranes is entirely sealed with the third side, and the fourth side is closed. It is preferable that, in the side portion, a portion overlapping the open portion of the bag-like film is a closed portion, and a portion overlapping the closed portion of the bag-like film is an open portion.

In such a spiral type membrane module, raw water flows into the raw water flow path from the front end face of the wound body. The raw water flows through the raw water flow path in a direction substantially parallel to the axis of the wound body, and then flows out as concentrated water from the raw water flow path opening at the rear end face of the wound body.

The water that has passed through the bag-like membrane flows in the bag-like membrane in a direction substantially parallel to the axis of the wound body, and flows out of the bag-shaped membrane opening at the rear end face of the wound body.

As described above, since the permeated water flows in the bag-shaped membrane in a direction parallel to the axis of the wound body, the water collecting pipe used in the conventional spiral membrane module becomes unnecessary. Then, there is no flow resistance when flowing into the water collecting pipe from inside the bag-shaped membrane, and the flow resistance of permeated water is reduced.

Since the water collecting pipe is eliminated, the length of the bag-like membrane in the winding direction can be increased accordingly.
The membrane area can be expanded. And even if the length in the winding direction of the bag-like membrane is increased, the flow resistance of the permeated water does not increase,
The amount of permeated water can be increased.

In this spiral type membrane module, since the raw water flow path is opened only at a part of the rear end face of the wound body, the flow rate of the raw water (concentrated water) downstream of the raw water flow path. Can be increased as compared with the conventional case, and the adhesion of dirt to the membrane surface in the downstream area of the raw water flow path can be prevented. Since there is little adhesion of dirt to the membrane surface, the pressure loss of the raw water flow is low, and the differential pressure between the inlet and the outlet of the raw water flow path is small. For this reason, since the pressure of the concentrated water flowing out of the upstream-side membrane module is sufficiently high, the water can be directly passed to the downstream-side membrane module without being pressurized by the pump. It is also possible to lower the pressure of the raw water supplied to the first stage, so that the load on each membrane module is reduced,
The film life is also extended. In addition, power costs are reduced,
Film clogging is reduced and backwash frequency is reduced.

The apparatus of the present invention can be used for water such as industrial water,
It is suitable for treating wastewater such as sewage and industrial wastewater.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view of a bag-shaped membrane of a spiral type membrane module used in a membrane separation device according to an embodiment of the present invention and a shaft around which the bag-shaped membrane is wound. 1 (b) and 1 (c) respectively show FIG.
It is sectional drawing which follows the BB line and CC line of (a). FIG.
Is a sectional view showing a method of winding a bag-like membrane around a shaft, FIG. 3 is a perspective view showing an engagement relationship between a wound body and a socket, and FIG. 4 is a side view of a spiral type membrane module.
FIG. 5 is a system diagram of a membrane separation device provided with this spiral type membrane module.

In the membrane separation apparatus of the present invention, a spiral type membrane module described below is installed in multiple stages, and the concentrated water of the first stage membrane module is passed through the second stage module.

This spiral type membrane module is formed by winding a plurality of bag-like membranes 10 around a shaft. As shown in FIG. 1, the bag-like film 10 has a square or rectangular shape, and includes a first side portion 11, a second side portion 12, a third side portion 13, and a fourth side portion 14. have. First side 1
In the first, second and third sides 12 and 13, the separation membrane films are adhered to each other by an adhesive or the like, and only a part of the fourth side 14 is adhered. In addition, as the bag-like film 10, one long film is folded back at the second side 12, and the first side 11 and the third side 13 are folded.
Alternatively, a part of the fourth side part 14 may be bonded.

From the middle of the fourth side portion 14 to the third side portion 13
The separation membrane films of the bag-like membrane 10 are not adhered to each other, and the opening portion 30 for permeated water outflow is formed. Further, from the middle of the fourth side portion 14 to the first side portion 11, the separation membrane films of the bag-like membrane 10 are adhered to each other, forming a closing portion 31 for preventing outflow of permeated water. I have.

A permeated water flow path material (for example, a mesh spacer) 15 is inserted into the bag-like membrane 10.

On one surface of the bag-like film 10, an adhesive 1
6 is adhered and adhesives 17 and 18 are adhered to the other surface, and the bag-like film 10 is wound around the shaft 20. The adhesive 16 is applied along the first side 11, and the adhesive 17 is applied along the third side 13. The adhesive 18 is applied along the opening 30 for outflow of permeated water from the intermediate portion in the longitudinal direction of the fourth side portion 14 to the third side portion 13.

By wrapping a plurality of bag-like films 10 around the shaft 20, the overlapping bag-like films 10 are joined to each other at the adhesive 17 and 18 parts in a watertight manner. Thus, a raw water flow path through which raw water (and concentrated water) flows is formed between the bag-shaped membranes 10. As the adhesive 18 cures, an open portion for flowing out the raw water (concentrated water) is formed on the rear end surface of the wound body on the inner peripheral side, and a closing portion for preventing raw water outflow is formed on the outer peripheral side. You.

Fins 19 extend from the boundary between the open portion 30 for permeate outflow and the closed portion 31 for permeate outflow prevention in the fourth side portion 14 toward the rear of the wound body. I have. The fins 19 are made of, for example, a synthetic resin film or sheet, and are preferably bonded to the bag-like film 10 by adhesion or the like.

By winding the bag-like membrane 10 around the shaft 20 via a raw water flow path material (mesh spacer) 29 as shown in FIG. 2, a wound body 24 is formed as shown in FIG. The fin 19 extends from the rear end face of the wound body 24. By providing the fins 19 at the same location on the fourth side portion 14 of each bag-like film 10, the fins 19
Are located equiradially from the axis of the winding body 24 and
The fins 19 form a ring-shaped protrusion by overlapping the 9. The rear end of the cylindrical socket 25 is inserted into the ring-shaped protrusion, and the socket 25 and the fin 19 are joined with an adhesive or the like. Note that the socket 25 may be externally fitted to the fin 19. Also, fin 1
A cutting groove may be formed on the rear end face of the wound body 24 along the line 9 by a lathe, and the end of the socket 25 may be embedded in the groove.

By joining the socket 25 and the fins 19 in this manner, a permeated water outflow area on the outer peripheral side of the rear end face of the wound body 24 and a concentrated water outflow area on the inner peripheral side of the socket 25 are defined. .

When the bag-like film 10 is wound around the shaft 20, as shown in FIG.
A raw water flow path material (mesh spacer) 29 is interposed between them. The raw water flow path is formed by interposing these mesh spacers 29.

As shown in FIG. 4, a top ring 26 and an end ring 27 are provided at the leading edge and the trailing edge of the wound body 24, respectively.
Is formed by a synthetic resin mold or the like, and the top ring 26 is formed.
A brine seal 28 is provided around the outer periphery of.

In the spiral membrane module configured as described above, as shown in FIG. 4, raw water flows into the raw water flow path between the bag-shaped membranes 10 from the front end face of the wound body 24. This raw water flows through the raw water flow path in a direction substantially parallel to the axis of the wound body 24, and is taken out from the end face inside the socket 25 at the rear end of the wound body 24. Then, while the raw water flows through the raw water flow path, the water permeates into the bag-like membrane 10, and the permeated water flows out from the outer peripheral side of the socket 25 on the rear end surface of the wound body 24.

In this spiral type membrane module, the permeated water flows in the bag-like membrane 10 in a direction parallel to the axis of the wound body 24 and is taken out from the rear end face. The used collecting pipe is unnecessary. For this reason, the flow resistance when flowing from the bag-like membrane into the water collecting pipe is eliminated, and the permeated water flow resistance is significantly reduced.

The water collecting pipe is omitted, and the length of the bag-like membrane 10 in the winding direction can be increased by that much.
It is possible to increase the film area. Even if the length of the bag-like membrane in the winding direction is increased, the permeated water flow resistance does not increase,
The amount of permeated water can be increased.

In this spiral type membrane module, the outlet portion of the raw water flow path is provided only inside the socket 25, and the outlet (the most downstream portion) of the raw water flow path is narrowed. The flow rate of the raw water (concentrated water) becomes sufficiently large also on the downstream side of the road, and the adhesion of dirt in the downstream area of the raw water flow path can be prevented. The area inside and outside the socket 25 (the length of the adhesive 18 in the side portion 14 direction) is preferably determined according to the water recovery rate of the spiral membrane module.

In this spiral type membrane module, the socket 25 is connected to the winding body 24 using the fins 19.
And the connection strength between the socket 25 and the winding body 24 is high. Then, the inflow side of the raw water and the outflow side of the concentrated water are partitioned in a watertight manner by the socket 25.

In the above embodiment, the socket 25
A permeated water outflow portion is arranged on the outer peripheral side of the socket 25, and a concentrated water outflow portion is arranged inside the socket 25. Conversely, the inside of the socket 25 is used as the permeated water outflow portion, and the outer peripheral side of the socket 25 is concentrated water outflow. It may be configured to be a part.

As shown in FIG. 5A, in the embodiment of the present invention, spiral type membrane modules 41 and 42 configured as shown in FIGS. Raw water is supplied from the raw water pump 40 to the raw water flow path of the membrane module 41, and is separated into permeated water and concentrated water. The retentate is kept intact (ie without being repressurized by the pump)
The raw water is supplied to the raw water flow path of the membrane module 42 of the stage, and the membrane is separated.

The spiral type membrane modules 41, 42
The pressure difference between the inlet and the outlet of the raw water (water to be treated) is small, and the concentrated water of the first stage membrane module 41 can be passed directly to the second stage membrane module 42 as described above. Also, the discharge pressure of the pump 40 may be low, and the cost of pump equipment and the cost of power are low. Furthermore, since the pressure applied to the membrane surfaces of the membrane modules 41 and 42 is low, the membrane life is long, the membrane is less clogged, and the backwashing frequency is less.

In the present invention, the SS (suspension material) in the raw water flowing into the first-stage membrane module 41 is supplied to the raw-water flow path material (mesh spacer) 2 of the first-stage membrane module 41.
9, the SS concentration in the concentrated water from the first-stage membrane module 41 is considerably low. For this reason, the first-stage membrane module 41 is compared with the second-stage membrane module 42.
It is preferable to increase the frequency of backwashing.

[0042]

EXAMPLE 1 As shown in FIG. 5 (a), spiral type membrane modules 41, 4
Next, the operation side of the membrane separation apparatus in which 2 is installed in two stages will be described. The used spiral type membrane modules 41 and 42
Has the configuration shown in FIGS. 1 to 4, and details thereof are as follows.

Separation membrane: polytetrafluoroethylene (P
TFE) microfiltration membrane Membrane area: 0.87 m ² Raw water flow path material: polyethylene Module length: 55 cm Module diameter: 10 cm (element nominal diameter) The conditions for water flow are as follows.

Raw water: SS 25 to 30 p with organic sludge in city water
pm Organic wastewater for water flow test added so as to obtain pm Raw water flow rate: 0.6 m ³ / Hr Average permeated water flow rate of the first stage membrane module: 0.4 m ³ / H
r Second stage membrane module average permeated water amount: 0.18 m ³ /
Hr Raw water pump discharge pressure: 0.8 to 3.5 kg / cm ² (however, when water is passed) In this case, the time-dependent change in the differential pressure between the raw water inlet and the concentrated water outlet of the first-stage spiral membrane module 41 is described. FIG. 5 (b)
Shown in

Comparative Example 1 Conventional module shown in FIG. 6 as a spiral type membrane module (module length 100 cm, diameter 10 cm)
Water was passed under the same conditions as in Example 1 except that was used. In this case, the change with time of the differential pressure between the raw water inlet and the concentrated water outlet of the first-stage spiral membrane module is shown in FIG.
(B). In Comparative Example 1, the pressure difference increased remarkably one day after the start of water passage, and water passage was impossible.

As apparent from FIG. 5 (b), the membrane separation device of the present invention requires a low differential pressure between the raw water inlet and the concentrated water outlet, and requires less backwashing.

[0047]

As described above, the spiral type membrane module used in the membrane separation device of the present invention does not require a water collecting pipe.
The flow resistance of permeated water is small, and the membrane area can be increased. The membrane separation device using this spiral type membrane module has a small hydraulic pressure product of raw water and requires a small number of raw water pumps. In addition, the load on the membrane module is small, and clogging of the membrane surface is small. Furthermore, it has excellent effects such as a long film life and a low backwash frequency.

[Brief description of the drawings]

FIG. 1A is a perspective view of a bag-shaped membrane of a spiral type membrane module of a membrane separation device according to an embodiment, FIG. 1B is a cross-sectional view taken along line BB of FIG. c) is a sectional view taken along the line CC in FIG.

FIG. 2 is a cross-sectional view showing a method of winding a bag-like membrane of the spiral membrane module of FIG.

FIG. 3 is a perspective view showing an engagement relationship between a wound body and a socket of the membrane module of FIG. 1;

FIG. 4 is a side view of the spiral membrane module of FIG. 1;

FIG. 5A is a system diagram of a membrane separation device according to an embodiment, and FIG. 5B is a graph showing the results of an example and a comparative example.

FIG. 6 is a partially exploded perspective view showing the structure of a conventional spiral type membrane module.

[Explanation of symbols]

 Reference Signs List 10 bag-like membrane 11 first side 12 second side 13 third side 14 fourth side 15 channel material 16, 17, 18 adhesive 19 fin 20 shaft 24 wound body 25 socket 29 Mesh spacer 30 Open part for permeate outflow 31 Closed part for permeate outflow prevention 40 Raw water pump 41, 42 Spiral type membrane module

Claims (3)

[Claims] 1. A membrane module is provided in a plurality of stages, raw water is passed through a preceding-stage membrane module to perform membrane separation into permeated water and concentrated water, and the concentrated water is passed through the subsequent-stage membrane module as raw water. In the membrane separation apparatus for separating the permeated water and the concentrated water into membranes, the membrane module winds the bag-shaped membrane around a shaft to form a wound body, and raw water is supplied from one end surface of the wound body. Is a spiral type membrane module taken out from the other end surface of the wound body. 2. The method according to claim 1, wherein only a pump for supplying the upstream-most membrane module is provided as a pump,
A membrane separation device having a spiral type membrane module, wherein concentrated water of each membrane module is passed as raw water to a lower membrane module without passing through a pump. 3. The bag-like film according to claim 1, wherein the bag-like film is substantially rectangular having first, second, third, and fourth sides, and the first, second, and third sides. The fourth side is partly open and the remaining part is closed. The first side perpendicular to the fourth side is applied to the shaft to apply the bag-like membrane. Wound to form a wound body, with the fourth side facing the rear end face of the wound body, and the second side facing the fourth side facing the front end face of the wound body. In the raw water flow path between the bag-shaped membranes, the entire third side is sealed, and a portion of the fourth side that overlaps the open portion of the bag-shaped membrane is a closed portion. And a portion overlapping the closed portion of the bag-shaped membrane is an open portion.