JPH11207342A - Treatment of underground water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform a membrane separation treatment of underground water with a spiral type membrane module. SOLUTION: This treatment method refers to a method for treating underground water with the spiral type membrane module. The spiral type membrane module consists of a wound body formed by winding a bag shaped separation membrane around a shaft 20, and feeds the raw water from one end face of the wound body and takes out transmitted water and concentrated water from the other end face of the wound body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for treating groundwater with a spiral membrane module.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 7-39872 describes that after groundwater is subjected to metal ion precipitation treatment by oxidation, treatment is performed by a membrane module. According to the same publication, after a chlorine-based oxidizing agent is introduced into manganese ion-containing groundwater, it is brought into contact with manganese sand (or manganese dioxide slurry) to oxidize and precipitate manganese, and then this liquid is filtered through a permeable membrane to remove manganese ( And a method for treating groundwater to remove turbidity and bacteria). In the same publication, a hollow fiber type microfiltration membrane is shown as a permeable membrane.

[0003] Japanese Patent Application Laid-Open No. 9-1155 discloses that groundwater is prepared by adding air or an oxidizing agent to groundwater and then permeating the groundwater through a permeable membrane having a metal oxide supported on a membrane surface to remove metal ions. A processing method is described. In the publication,
Examples of the filtration membrane include a tubular membrane, a hollow fiber membrane, a multi-lumen membrane, and a flat membrane made of synthetic fiber, glass, resin, ceramics and the like.

Since the present invention uses an improved spiral membrane module as a spiral membrane module for treating groundwater, the structure of a conventional spiral membrane module before the improvement will be described with reference to the drawings. explain.

FIG. 5 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 a water collecting pipe 1 via a mesh spacer 3.

The water collecting pipe 1 is provided with a slit-like opening communicating between the inside and the 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.

A top ring 6 and an end ring 7 are provided at both ends of the wound body 5 of the bag-like 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 as it is in the longitudinal direction of the wound body 5, 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.

[0009]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 7-398 is disclosed.
Hollow fiber membranes, tubular membranes and flat membranes used in the treatment of groundwater in JP-A-72 and JP-A-9-1155 have higher filtration resistance and smaller permeated water volume than spiral membranes.

The conventional spiral type membrane module shown in FIG. 5 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 also 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.

The present invention solves the above-mentioned conventional problems, and provides a groundwater treatment method capable of efficiently treating groundwater by a spiral membrane module which does not require a water collecting pipe and has low permeated water flow resistance. The purpose is to:

[0013]

The method for treating groundwater according to the present invention is a method for treating groundwater with a spiral membrane module, wherein the spiral membrane module winds the membrane around a shaft to form a wound body. Raw water is supplied from one end face of the wound body, and permeated water is taken out from the other end face of the wound body. The membrane may be any of an ultrafiltration membrane, a microfiltration membrane, and a reverse osmosis membrane, but is preferably an ultrafiltration membrane or a microfiltration membrane.

The spiral membrane module employed in the present invention is a spiral membrane module in which a permeated water channel material is disposed inside a bag-shaped membrane, and a raw water channel material is disposed between the bag-shaped membranes. The bag-like membrane is substantially rectangular with first, second, third and fourth sides, and the first, second and third sides are sealed and the fourth A part of the side part is an open part and the remaining part is a closed part, and a first side part orthogonal to the fourth side part is applied to a shaft to wind a bag-like membrane to form a wound body, The fourth side faces the rear end face of the wound body, the second side facing the fourth side faces the front end face of the wound body, between the bag-shaped films. The raw water flow path of the third
The entire side of the bag-shaped membrane is sealed, and in the fourth side, a portion overlapping with the open portion of the bag-shaped film is a closed portion, and a portion overlapping with the closed portion of the bag-shaped film is open. It is preferably a part.

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.

Further, 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 raw water (concentrated water) downstream of the raw water flow path can be increased as compared with the conventional case. In addition, the adhesion of dirt in the downstream area of the raw water flow path can be prevented.

In the present invention, a fluororesin such as polytetrafluoroethylene (PTFE) is preferable as a material of the membrane. This fluororesin film has high chemical resistance, and can be treated for a long time even if ozone or chlorine is contained in water.

In the method of the present invention, it is preferable to subject the groundwater to metal ion precipitation treatment such as the addition of an oxidizing agent in advance, and then pass the water through the membrane module.

In the present invention, groundwater may be pumped from the ground or may be discharged from the ground.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A spiral type membrane module used in an embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view of a bag-like membrane of the spiral membrane module and a shaft around which the bag-like membrane is wound. FIGS. 1B and 1C are cross-sectional views taken along lines BB and CC of FIG. 1A, respectively. FIG. 2 is a sectional view showing a method of winding a bag-like membrane around a shaft, and FIG.
Is a perspective view showing an engagement relationship between the wound body and the socket, and FIG. 4 is a side view of the spiral membrane module.

As shown in FIG. 1, the bag-like film 10 has a square or rectangular shape, and has a first side portion 11 and a second side portion.
, A third side 13, and a fourth side 14. In the first side 11, the second side 12, and the third side 13, the separation membrane films 40 are bonded to each other with an adhesive or the like, and only a part of the fourth side 14 is bonded. . In addition, as the bag-like film 10, one long film is folded in two at the second side 12, and one of the first side 11, the third side 13, and the fourth side 14 is formed. The parts 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 channel material (for example, a mesh spacer) 15 is inserted and arranged in 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 winding a plurality of bag-shaped membranes 10 around the shaft 20, the overlapping bag-shaped membranes 10 are joined to each other at the portions of the adhesives 17 and 18 in a water-tight 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 fin 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 on 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.

The groundwater treatment method of the present invention treats groundwater with the spiral membrane module configured as described above. As shown in FIG. 4, the groundwater flows from the front end face of the wound body 24 into the raw water flow path between the bag-shaped membranes 10 as raw water. 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 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.

It is to be noted that the water collecting pipe is omitted, and the length of the bag-like membrane 10 in the winding direction can be increased accordingly.
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 (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 FIGS. 1 to 4, the permeated water outflow portion is arranged on the outer peripheral side of the socket 25, and the concentrated water outflow portion is arranged inside the socket 25. The outer peripheral side of the socket 25 may be configured as a concentrated water outflow portion.

In the method for treating groundwater of the present invention, when the membrane is a microfiltration membrane or an ultrafiltration membrane, an oxidizing agent such as ozone, chlorine gas, air or potassium permanganate is added to the groundwater to remove manganese. After oxidizing and precipitating metal ions such as iron, it is preferable to pass water through the membrane module to remove metal components. When chlorine is added, it is preferable that manganese is oxidized and precipitated by passing it through a filter bed of manganese sand or a floating layer of a slurry containing manganese dioxide after the addition of chlorine, as in JP-A-7-39872.

Also, in the treatment method of the present invention, an oxide such as iron or manganese to be removed is supported on the film surface and air or an oxidizing agent is added thereto, as disclosed in JP-A-9-1155. The permeated treatment of the groundwater may be performed by the membrane.

In the method of the present invention, when the membrane is a reverse osmosis membrane, the groundwater is directly introduced into the membrane module and subjected to permeation treatment without performing such preliminary metal oxidation treatment. Ions can be removed.

Incidentally, along with the removal of such metal components,
It is clear that suspended matter and bacteria are also removed by membrane filtration.

When performing the back washing of the spiral type membrane module, gas pressure is applied to the permeated water flow path in the bag type membrane 10 of the spiral type membrane module to remove the residual permeated water and further gas in the bag type membrane module 10. It is preferable to backwash by flowing into a water flow path.

[0044]

EXAMPLES Examples and comparative examples will be described below.

Example 1 Groundwater having a water quality shown in Table 1 below was treated using a spiral-type membrane module having a structure shown in FIGS. 1 to 4 using a PTFE microfiltration membrane as the membrane.

The membrane area of this membrane module is 0.87 m ²
And the diameter is 10 cm and the length is 40 cm.

After 15 ppm of ozone was added to the raw water, water was passed through the membrane module at 22 m ³ / m ² / day, and the permeate flux was 20 m ³ / m ² / day. The quality of the permeated water was as shown in Table 1.

Comparative Example 1 A spiral type membrane module having the structure shown in FIG. 5 (the membrane area is the same as that of Example 1; diameter 10c)
m, length 100 cm), except that the same groundwater was treated in the same manner as in Example 1;
m ³ / m ² / day, which was considerably lower than that of Example 1. The quality of the permeated water was as shown in Table 1.

[0049]

[Table 1]

[0050]

As described above, the method for treating groundwater according to the present invention enables the groundwater to be subjected to membrane separation with high efficiency, and uses a heat-resistant membrane such as a fluororesin membrane. Thus, it is also possible to add ozone, chlorine and the like to raw water and perform membrane permeation treatment.

[Brief description of the drawings]

FIG. 1A is a perspective view of a bag-shaped membrane of a spiral membrane module used in a method of treating groundwater according to an embodiment, and FIG. 1B is a cross-sectional view taken along line BB of FIG. Figure,
FIG. 3C is a cross-sectional view taken along 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. 5 is a partially exploded perspective view showing the structure of a conventional spiral 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 flow path 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

Claims (4)

[Claims] 1. A method of treating groundwater with a spiral membrane module, wherein the spiral membrane module winds a membrane around a shaft to form a roll, and raw water is supplied from one end surface of the roll. And
A method for treating groundwater, wherein permeated water is taken out from the other end surface of the wound body. 2. The bag according to claim 1, wherein the membrane is a bag-like membrane in which a permeated water channel material is disposed, and the bag-like membrane is a first membrane.
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 The spiral-type membrane module is a closed part, and the first side part orthogonal to the fourth side part is applied to a shaft to wind a bag-like membrane into a roll, and the fourth side is formed. Part facing the rear end face of the wound body, a second side part facing the fourth side part facing the front end face of the wound body, and a raw water flow path between the bag-shaped membranes. The third side portion is entirely sealed, and in the fourth side portion, a portion overlapping with the open portion of the bag-shaped film is a closed portion, and the closed portion of the bag-shaped film is closed. A ground-water treatment method, characterized in that it is a spiral-wound membrane module having an open part overlapping with the above. 3. The method according to claim 1, wherein the membrane is a fluororesin membrane. 4. The method for treating groundwater according to claim 1, wherein the treatment liquid is passed through the membrane module after performing a treatment for precipitating metal ions.