JP6519874B2 - Water treatment system - Google Patents

Description

The present invention relates to a water treatment system that processes the organic wastewater such as night soil.

When treating organic wastewater such as human waste, it has become mainstream to use membrane separation such as MF (microfiltration) and UF (ultrafiltration) for separation of solid and liquid.
As a membrane separation device, using a plurality of membrane modules provided with a cylindrical casing and a plurality of tubular filtration membranes (hollow fiber membranes) accommodated in the casing, the raw water is circulated inside the tubular filtration membrane There is known an apparatus of a filtration type while (see, for example, Patent Document 1). The permeated water that has permeated through the tubular filtration membrane is sucked by a suction pump and stored, for example, in a storage tank and used appropriately.

JP, 2013-052338, A

By the way, in the conventional membrane separation apparatus, the arrangement method of the tubular filtration membranes accommodated in the casings of a plurality of membrane modules is a parallel system. That is, the water to be treated is introduced into the plurality of tubular filtration membranes through the header of the casing.
In the case of such a form, since the quantity of the to-be-processed water which circulates increases, there existed a problem that driving power became large. In addition, when the water to be treated is not supplied uniformly to each tubular filtration membrane, the membrane surface flow rate becomes uneven, and there is a problem that sludge accumulates or stagnates on the tubular filtration membrane. There is a problem that (1) a tubular filtration membrane which is not effectively used is generated due to the deposition or stagnation of sludge, (2) a decrease in FLUX (efflux), (3) a blockage of the tubular filtration membrane or the like occurs.

The invention, together with reduced operating power of the water treatment system, and to provide or sludge deposited on the tubular filtration membranes, the water treatment system that can be suppressed or to stagnate.

According to a first aspect of the present invention, a water treatment system comprises a biological treatment water tank for treating an organic substance contained in water to be treated, and a raw water tank containing the water to be treated discharged from the biological treatment water tank. A cylindrical casing, and a plurality of tubular filtration membranes having a single-layered structure in which a hydrophilic monomer is copolymerized in a single main component, extending in the extending direction of the casing inside the casing; Provided at one end of the extending direction of the casing, at a first partition having a plurality of through holes to which one end of the plurality of tubular filtration membranes is connected, and at the other end of the extending direction of the casing; A second partition wall having a plurality of through holes to which the other ends of the tubular filtration membranes are connected, one ends of the tubular filtration membranes, and the other ends of the tubular filtration membranes are connected in series by the plurality of tubular filtration membranes. Membrane connection to connect as connected A membrane separation device including: a membrane module including: a pair of membrane connection plates; and separating the water to be treated supplied from the raw water tank into a permeate water and a concentrated water; And a return line to be returned to the treatment water tank, wherein the concentrated water is not returned to the raw water tank at all .

  According to such a configuration, the flow rate of the water to be treated flowing through the tubular filtration membranes can be reduced as compared with a method in which a plurality of tubular filtration membranes are connected in parallel. As a result, the operating power for circulating the water to be treated can be reduced. In addition, since the film surface flow rate becomes uniform, it is possible to suppress the deposition or stagnation of sludge on the tubular filtration membrane.

  According to such a configuration, the assembly process of the membrane module can be simplified. In addition, since the number of parts is reduced, disassembly and cleaning can be facilitated.

  In the water treatment system, the membrane separation apparatus may include a plurality of the membrane modules connected in series.

  According to such a configuration, one pipe is connected to the membrane separation device, and the flow rate of the treated water circulating in the water treatment system can be reduced. As a result, the operating power for circulating the water to be treated can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, compared with the system which connects a several tubular filtration membrane in parallel, the flow volume of the to-be-processed water which flows through a tubular filtration membrane can be decreased. As a result, the operating power for circulating the water to be treated can be reduced. In addition, since the film surface flow rate becomes uniform, it is possible to suppress the deposition or stagnation of sludge on the tubular filtration membrane.

It is a schematic block diagram of the water treatment system of a first embodiment of the present invention. It is a schematic sectional drawing of the membrane module of 1st embodiment of this invention. It is a schematic block diagram of the water treatment system of a second embodiment of the present invention. It is a disassembled perspective view of the 1st partition of the membrane module of a third embodiment of the present invention, and a membrane connection board. It is a schematic sectional drawing of the 1st partition of the film | membrane module of 3rd embodiment of this invention, and a film | membrane connection board.

First Embodiment
Hereinafter, a water treatment system 10 having a membrane module 1 according to a first embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the water treatment system 10 according to the present embodiment includes a biological treatment water tank 11 for treating organic matter contained in water to be treated W1 (human waste, organic wastewater including septic tank sludge), and a biological treatment water tank 11. The raw water tank 12 in which the water to be treated W2 to be discharged is stored, and the membrane separation device 13 for separating the water to be treated W3 (raw water) supplied from the raw water tank 12 into the permeate water PW and the concentrated water W4 ing.

  The biological treatment tank 11 is, for example, a device that decomposes and removes BOD, nitrogen compounds, and the like in the liquid by the action of nitrifying bacteria and denitrifying bacteria. Water to be treated W1 is supplied to the biological treatment tank 11 via the first pipe 15. The biological treatment tank 11 and the raw tank 12 are connected by a second pipe 16.

The membrane separation apparatus 13 includes a plurality of membrane modules 1. The plurality of membrane modules 1 are arranged in parallel. The plurality of membrane modules 1 are vertically disposed in the casing of the membrane separation apparatus 13. That is, the axis A of the cylindrical casing 2 (see FIG. 2) of the membrane module 1 extends in the vertical direction.
As shown in FIG. 2, the membrane module 1 has a casing 2 and a plurality of tubular filtration membranes 3 disposed inside the casing 2. The membrane separation device 13 is a device for taking out the permeated water PW from the water to be treated W3 using a method of circulating the water to be treated W3 while circulating it inside the tubular filtration membrane 3.

The raw water tank 12 and the membrane separation device 13 are connected via a raw water supply pipe 17. The raw water supply pipe 17 is provided with a circulation pump 21. The water to be treated W3 discharged from the raw water tank 12 is supplied to the membrane separation device 13 while being pressurized by the circulation pump 21.
The permeate water PW separated from the membrane separation device 13 is introduced into the permeate water pipe 18. The permeated water pipe 18 is connected to the storage tank 20. That is, the permeated water discharge port 9 (see FIG. 2) of the membrane module 1 is connected to the permeated water pipe 18. A suction pump 22 is provided in the permeated water pipe 18.

The concentrated water W4 separated from the permeated water PW and discharged from the membrane separation device 13 is returned to the biological treatment water tank 11 through the return pipe 19 (return line) except the excess sludge. That is, the concentrated water outlet 8 (see FIG. 2) of the membrane module 1 is connected to the return pipe 19.
Therefore, the concentrated water W4 is not returned to the raw water tank 12. The treated water W 2 discharged from the biological treatment water tank 11 returns to the biological treatment water tank 11 via the raw water tank 12 and the membrane separation device 13. That is, the water to be treated W circulates in the piping of the water treatment system 10.

  As mentioned above, a plurality of membrane modules 1 are arranged in parallel. Specifically, the raw water supply pipe 17, the permeated water pipe 18, and the return pipe 19 are connected to the respective membrane modules 1.

As shown in FIG. 2, the membrane module 1 includes a cylindrical casing 2 and a plurality of tubular filtration membranes 3.
The casing 2 includes a cylindrical casing main body 4, a first side wall 5 closing the lower end of the casing main body 4, a second side wall 6 closing the upper end of the casing main body 4, and a process formed on the casing main body 4 A water inlet 7, a concentrated water outlet 8 formed in the casing main body 4, and a permeated water outlet 9 formed in the casing main body 4 are provided.

The membrane module 1 includes a first partition wall 30 and a second partition wall 31 that divide the inside of the casing 2 into three spaces. A plurality of insertion holes 32 are formed in the first partition wall 30 and the second partition wall 31. The insertion hole 32 is a through hole penetrating in the thickness direction of the first partition wall 30 and the second partition wall 31. The inner diameter of the insertion hole 32 is slightly larger than the outer diameter of the tubular filtration membrane 3.
The first partition wall 30 is provided at one end of the extending direction of the casing 2, and one end of the plurality of tubular filtration membranes 3 is connected to the plurality of through holes 32. The second partition wall 31 is provided at the other end of the casing 2 in the extending direction, and the other ends of the plurality of tubular filtration membranes 3 are connected to the plurality of through holes 32.

The first partition wall 30 is a member having a plate shape, and is fixed to the lower side in the extension direction of the casing 2 (the side of the first side wall 5). A space surrounded by the casing body 4, the first partition wall 30, and the first side wall 5 is a lower header space S1.
The second partition wall 31 is a member having a plate shape, and is fixed to the upper side in the extension direction of the casing 2 (the side of the second side wall 6). A space surrounded by the casing main body 4, the second partition wall 31 and the second side wall 6 is an upper header space S2.
A space surrounded by the casing main body 4, the first partition wall 30 and the second partition wall 31 is a permeated water space S3. The permeated water PW taken out of the plurality of tubular filtration membranes 3 is discharged into the permeated water space S 3 and then introduced into the permeated water pipe 18 through the permeated water outlet 9.

The treated water inlet 7 is an opening for communicating the outside of the casing 2 with the lower header space S1. The water inlet 7 is formed in the casing body 4. The water inlet 7 is provided between the first partition wall 30 and the first side wall 5 in the direction of the axis A of the casing 2.
The concentrated water discharge port 8 is an opening for communicating the outside of the casing 2 with the upper header space S2. The concentrated water discharge port 8 is formed in the casing main body 4. The concentrated water discharge port 8 is provided between the second partition wall 31 and the second side wall 6 in the direction of the axis A of the casing 2.
The permeated water discharge port 9 is an opening for communicating the outside of the casing 2 with the permeated water space S3. The permeated water outlet 9 is formed in the casing main body 4. The permeated water discharge port 9 is provided between the first partition wall 30 and the second partition wall 31 in the direction of the axis A of the casing 2.

One end of each tubular filtration membrane 3 is inserted into the insertion hole 32 of the first partition wall 30 and then fixed to the inner circumferential surface of the insertion hole 32. A seal material (not shown) seals between the inner peripheral surface of the insertion hole 32 and the outer peripheral surface of the tubular filtration membrane 3. The sealing material is preferably a material such as an epoxy resin or a urethane resin, which has viscosity in the initial stage and is cured with time.
The other end of each tubular filtration membrane 3 is fixed to the insertion hole 32 of the second partition 31 in the same manner as one end of the tubular filtration membrane 3.

The plurality of tubular filtration membranes 3 of the present embodiment are connected in series. Specifically, in the membrane module 1 of the present embodiment, one end of the tubular filtration membrane 3 and the other end of the tubular filtration membrane 3 are connected so that the plurality of tubular filtration membranes 3 are connected in series. There is.
The ends of the tubular filtration membrane 3 are connected by a U-shaped membrane connection pipe 34. The U-shaped membrane connection pipe 34 is, for example, a cylindrical connection member which is formed of engineering plastic such as POM and is curved. The film connection pipe 34 may be formed of a metal having excellent corrosion resistance such as SUS304. The end of the membrane connection pipe 34 is connected to the insertion hole 32 of the partition wall 30, 31. The end of the membrane connection tube 34 may be connected directly to the tubular filtration membrane 3.

The tubular filtration membrane 3 has a cylindrical shape and is formed of a polymer filtration membrane of a single layer structure in which a hydrophilic monomer is copolymerized in a single main constituent material.
That is, in the tubular filtration membrane 3, the main material is formed of one kind of material. That the main material is formed of one type of material means that one type of resin occupies 50% by mass or more in the material (for example, resin) forming the tubular filtration membrane 3.
Further, the fact that the main material is formed of one type of material means that the properties of the one type of material dominate the properties of the constituent material. Specifically, it means a material in which one kind of resin has 50% by mass to 99% by mass.

  Main materials constituting the tubular filtration membrane 3 include vinyl chloride resin, polysulfone (PS), polyvinylidene fluoride (PVDF), polyolefin such as polyethylene (PE), polyacrylonitrile (PAN), polyether Polymeric materials such as sulfone type, polyvinyl alcohol (PVA) type, polyimide (PI) type and the like can be used.

  Especially as a main material which comprises the tubular filtration membrane 3, vinyl chloride-type resin is preferable. As a vinyl chloride resin, a vinyl chloride homopolymer (vinyl chloride homopolymer), a copolymer of a monomer having an unsaturated bond copolymerizable with a vinyl chloride monomer and a vinyl chloride monomer, and a vinyl chloride monomer as a polymer Examples thereof include graft copolymers obtained by graft copolymerization, and (co) polymers comprising those vinyl chloride monomer units chlorinated.

As a hydrophilic monomer, for example,
(1) Cationic group-containing vinyl monomers such as amino group, ammonium group, pyridyl group, imino group, betaine structure and / or salts thereof,
(2) hydrophilic nonionic group-containing vinyl monomers such as hydroxyl group, amide group, ester structure, ether structure, etc.
(3) An anionic group-containing vinyl monomer such as a carboxyl group, a sulfonic acid group or a phosphoric acid group and / or a salt thereof
(4) Other monomers may, for example, be mentioned.
The tube diameter of the tubular filtration membrane can be appropriately selected depending on the properties of the water to be treated W, for example, when the crude fiber amount α in the water to be treated W3 is 200 mg / liter or less, the inner diameter of the tubular filtration membrane 3 is 5 mm Hereinafter, when the coarse fiber amount α is more than 200 mg / liter and less than 500 mg / liter, the inner diameter of the tubular filtration membrane 3 is 5 mm-10 mm, and when the coarse fiber amount α is 500 mg / liter or more, the inner diameter of the tubular filtration membrane 3 Can be 10 mm or more. By selecting the pipe diameter, it is possible to suppress the blockage of the tubular filtration membrane 3 due to the coarse fiber content.

Next, the operation of the water treatment system 10 of the present embodiment will be described.
First, the water to be treated W1 is treated in the biological treatment water tank 11. Specifically, the organic substance contained in the water to be treated W1 is decomposed by the microorganism.
Next, the water to be treated W 2 discharged from the biological treatment tank 11 is stored in the raw water tank 12. When the water to be treated W3 discharged from the raw water tank 12 is supplied to the membrane separation device 13 via the circulation pump 21, it is fed into the tubular filtration membrane 3 of the membrane module 1. On the other hand, the permeated water space S3 in the casing 2 of the membrane module 1 becomes negative pressure by the operation of the suction pump 22. The suction pump 22 sucks in a direction substantially orthogonal to the flow of the water to be treated W3 flowing through the tubular filtration membrane 3 through the permeated water outlet 9. The permeated water PW permeated from the tubular filtration membrane 3 is stored in the storage tank 20 via the permeated water outlet 9 and the permeated water pipe 18.

Here, the flow of the water to be treated W3 in the membrane module 1 will be described with reference to FIG.
By connecting the plurality of tubular filtration membranes 3 in series, the water to be treated W3 flowing into the lower header space S1 is introduced into the first tubular filtration membrane 3a. Next, the water to be treated W3 is introduced into the second tubular filtration membrane 3b via the membrane connection pipe 34a. Thereafter, the water to be treated W3 is introduced into the fifth tubular filtration membrane 3e via the third tubular filtration membrane 3c and the fourth tubular filtration membrane 3d. The treated water W3 is discharged from the concentrated water outlet 8 after flowing into the upper header space S2 from the fifth tubular filtration membrane 3e.
That is, by arranging the arrangement of the tubular filtration membranes 3 in series, the same amount of water W3 to be treated always passes through the inside of all the tubular filtration membranes 3.
Alternatively, the first tubular filtration membrane 3 a may be directly connected to the treated water inlet 7 and the fifth tubular filtration membrane 3 e via the connecting member 39 and the connecting member 40. In this case, the upper header space S2 may not be provided, and the configuration of the casing can be changed, such as eliminating the second side wall 6.

  The whole amount of the concentrated water W4 discharged from the membrane separation device 13 is returned to the biological treatment water tank 11 via the return pipe 19, and the treatment is performed again.

According to the said embodiment, compared with the system which connects the several tubular filtration membranes 3 in parallel, the flow volume of the to-be-processed water W which flows through the membrane module 1 can be decreased. As a result, the operating power for circulating the water to be treated W can be reduced.
Moreover, when not decreasing the flow volume of the to-be-processed water W, a film surface flow velocity can be improved. Thereby, it can suppress that sludge accumulates on the membrane surface of the tubular filtration membrane 3.

  Moreover, since the film surface flow rate becomes uniform, it is possible to suppress the deposition or stagnation of the sludge on the tubular filtration membrane 3. Thereby, all the tubular filtration membranes 3 can be used effectively. In addition, it is possible to suppress the decrease in FLUX (the amount of outflow). Furthermore, the tubular filtration membrane 3 can be prevented from being blocked.

  Further, by forming the tubular filtration membrane 3 with a material having hydrophilicity, the membrane surface flow rate of the water to be treated W3 can be lowered. The film surface flow rate can be, for example, 0.15 m / s-0.30 m / s.

  When the tubular filtration membrane 3 is hydrophobic, it is necessary to increase the membrane surface flow rate (for example, 2.5 m / s). Therefore, the circulation flow rate is increased, and the concentrated water W4 discharged from the membrane separation device 13 needs to be returned to the raw water tank 12 and the biological treatment water tank 11. In order to return to the raw water tank 12 and the biological treatment water tank 11, a distribution tank for distributing the concentrated water W4 to the raw water tank 12 and the biological treatment water tank 11 and a piping for returning the concentrated water W4 to the raw water tank 12 are required. .

In the water treatment system 10 of the present embodiment, the membrane surface flow rate can be reduced, and therefore the circulation flow rate of the water to be treated W can be reduced. Thus, the power of the circulation pump 21 can be reduced. Further, a distribution tank for distributing the water to be treated W4 to the raw water tank 12 and the biological treatment water tank 11, and a return pump for returning the water to be treated W4 from the raw water tank 12 to the biological treatment water tank 11 become unnecessary.
In addition, by reducing the flow rate, the diameter of the pipe can be reduced. In addition, since the flow rate is reduced, it is possible to reduce the number of devices such as flow meters.

Second Embodiment
Hereinafter, water treatment system 10B of a second embodiment of the present invention is explained based on a drawing. In the present embodiment, differences from the first embodiment described above will be mainly described, and the description of the same parts will be omitted.
As shown in FIG. 3, in the water treatment system 10B of the present embodiment, a plurality of membrane modules 1 are connected in series with each other. For example, when the membrane separation apparatus 13 includes three membrane modules 1, the water to be treated W3 discharged from the raw water tank 12 is introduced only into the first membrane module 1a and discharged from the first membrane module 1a. Water to be treated is introduced only to the second membrane module 1b. The water to be treated discharged from the second membrane module 1 b is introduced only to the third membrane module 1 c, and the concentrated water W 4 discharged from the third membrane module 1 c is introduced to the return pipe 19.

  According to the said embodiment, the raw water supply piping 17 and the return piping 19 which are connected to the membrane separation apparatus 13 each become one place, and it can reduce the flow volume of the to-be-processed water W which circulates the water treatment system 10B. As a result, the operating power for circulating the water to be treated W can be reduced.

Third Embodiment
Hereinafter, a membrane module of a third embodiment of the present invention will be described based on the drawings. In the present embodiment, differences from the first embodiment described above will be mainly described, and the description of the same parts will be omitted.
As shown in FIGS. 4 and 5, the membrane module 1C of this embodiment is a pair of membrane connection plates 36 (FIGS. 4 and 5) as an alternative to the membrane connection pipe 34 (see FIG. 2) of the first embodiment. Shows one of the pair of membrane connection plates 36). The membrane connection plate 36 has a plate shape, and is attached in close contact with the surface of the first partition 30 opposite to the surface facing the second partition 31.
Although the film connection plate 36 is also attached to the surface of the second partition wall 31 opposite to the surface facing the first partition wall 30, the description will be omitted because it has the same structure.

The film connection plate 36 is connected to the first partition 30 so that the main surface is in close contact with the surface of the first partition 30 opposite to the surface facing the second partition 31. The surface of the film connection plate 36 in close contact with the first partition wall 30 is called a close contact surface 36 a. A plurality of film connection grooves 37 are formed in the adhesion surface 36 a of the film connection plate 36. Further, the membrane connection plate 36 is formed with a treated water insertion hole 38 which penetrates the contact surface 36 a and the opposite surface.
The film connection groove 37 is a bottomed groove formed in the close contact surface 36 a of the film connection plate 36. The membrane connection groove 37 has the same function as the membrane connection tube 34 of the first embodiment. That is, the water to be treated W flowing through one tubular filtration membrane 3 flows to the other tubular filtration membrane 3 via the membrane connection groove 37. The to-be-processed water penetration hole 38 is a hole which makes the tubular filtration membrane 3 and header space connect.

  According to the said embodiment, compared with the film | membrane module 1 of 1st embodiment using several film connection pipe | tube 34, the assembly process of a film | membrane module can be simplified. In addition, since the number of parts is reduced, disassembly and cleaning can be facilitated.

Although the embodiments of the present invention have been described in detail, various modifications can be made without departing from the technical concept of the present invention.
For example, although five tubular filtration membranes 3 are shown in FIG. 2 etc. regarding the number of tubular filtration membranes 3, the number of tubular filtration membranes 3 is not limited to this.

  Also, the membrane module 1 may be placed horizontally. That is, the membrane module 1 may be arranged such that the axis A of the membrane module 1 extends in the horizontal direction. By disposing the membrane module 1 horizontally, replacement of the membrane module 1 can be facilitated even in the case where a plurality of membrane modules 1 are disposed.

Reference Signs List 1 membrane module 2 casing 3 tubular filtration membrane 4 casing main body 5 first side wall 6 second side wall 7 treated water inlet 8 concentrated water outlet 9 permeated water outlet 10 water treatment system 11 biological treatment tank 12 primary water tank 13 membrane separation Device 15 First piping 16 Second piping 17 Raw water supply piping 18 Permeated water piping 19 Return piping (return line)
Reference Signs List 20 storage tank 21 circulation pump 22 suction pump 30 first partition 31 second partition 32 insertion hole (through hole)
34 Membrane connection pipe (connection member)
36 Membrane connection plate (connection member)
36a adhesive surface 37 membrane connection groove 38 untreated water passage hole A axis PW PW permeated water S1 lower header space S2 upper header space S3 permeated water space W1 to W3 treated water W4 concentrated water

Claims (2)

A biological treatment water tank for treating organic matter contained in the water to be treated;
A raw water tank containing the treated water discharged from the biological treatment water tank;
A cylindrical casing, and a plurality of tubular filtration membranes having a single-layered structure in which a hydrophilic monomer is copolymerized in a single main component, extending in the extending direction of the casing inside the casing;
A first partition provided at one end in the extending direction of the casing and having a plurality of through holes to which one end of the plurality of tubular filtration membranes is connected;
A second partition wall having a plurality of through holes provided at the other end of the casing in the extending direction and to which the other ends of the plurality of tubular filtration membranes are connected;
And a pair of membrane connection plates provided with membrane connection grooves for connecting the ends of the tubular filtration membranes and the other ends of the tubular filtration membranes such that the plurality of tubular filtration membranes are connected in series. A membrane separation device for separating the water to be treated supplied from the raw water tank into permeate water and concentrated water;
A return line for returning the concentrated water to the biological treatment tank, wherein the raw water tank does not return the concentrated water at all . The water treatment system according to claim 1 , wherein the membrane separation device comprises a plurality of the membrane modules connected in series with each other.

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