JP3058579B2 - Method for producing filter media for anaerobic treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used in an anaerobic treatment section of a sewage purifying apparatus, and a method for producing a filter material for anaerobic treatment excellent in solid substance trapping property and workability. br />.

[0002]

2. Description of the Related Art Purification treatment of sewage by so-called anaerobic microorganisms has been widely used in various purification apparatuses.

FIG. 17 shows an example of a sewage treatment apparatus using anaerobic microorganisms, and is a schematic sectional view of a so-called anaerobic filter bed contact aeration type combined treatment / purification tank. That is, the inlet 20
22 (human waste and household wastewater) flowing into the first anaerobic filter tank 21a through the convection pipe 23 and into the second anaerobic filter tank 21b, and firstly into the both anaerobic filter tanks 21a and 21b. Undergoes anaerobic treatment by anaerobic microorganisms. The sewage subjected to anaerobic treatment in the anaerobic filter tank 21 continues to be connected to the communication hole 2.
After passing through 4 and entering the contact aeration tank 25, which is purified by aeration treatment, it is discharged from the discharge port 28 to the outside through the precipitation tank 26 and the disinfection tank 27.

[0004] In the anaerobic filter bed tank 21,
In order to capture the solid matter in the sewage 22, prevent the inflow of the solid matter into the contact aeration tank 25, and promote the growth of anaerobic microorganisms to enhance the anaerobic treatment capacity, the anaerobic of an appropriate shape and size is used. The processing filter medium 29 is filled.

[0005] By the way, this anaerobic treatment filter medium 29 includes:
There is an indispensable requirement that contradictory performances such as excellent solids trapping property and difficulty of clogging must be satisfied at the same time, and various anaerobic treatments currently used for Each filter medium has its advantages and disadvantages.

For example, a conventionally used anaerobic treatment filter medium of this type is a thin corrugated sheet (having a specific surface area of about 80 mm and a height of about 60 mm) made of polyvinyl chloride or the like. 55 m ² / m ³ ), a net-like thick corrugated plate (specific surface area of about 45 mm) formed by bending a net-like thick plate having a thickness of about 60 mm made of polypropylene or the like into a waveform having a pitch of 100 to 300 mm and a height of 150 to 350 mm.
m ² / m ³ ) and polyethylene etc., outer diameter 60m
There are, for example, those molded into a cage-like cylindrical body having a length of 80 mm and a specific surface area of 40 m ² / m ³ .

[0007] However, in the above-mentioned filter medium for anaerobic treatment of a thin corrugated sheet, a net-like thick corrugated sheet, or a cage-like cylinder, the sludge holding capacity, the sludge trapping property, the dispersibility of the sludge, the degassing property, and the consolidation property in the filter bed. Each has its own advantages and disadvantages, and as a result, the treatment in the anaerobic filter tank becomes insufficient, and the BOD value in the sewage flowing into the contact aeration tank from the anaerobic filter tank cannot be reduced sufficiently. And that the tank volume of the entire purification device cannot be reduced. These anaerobic filter media are
Usually, they are cut to an appropriate outer diameter according to the capacity of an anaerobic filter bed tank to which these are applied, and there is a problem that the secondary processing is troublesome. Furthermore, these anaerobic treatment filter media have to be filled in an anaerobic treatment section of a sewage treatment apparatus in an aligned state, and there is a drawback that the filling is troublesome.

[0008]

The object of the present invention is to solve the above-mentioned problems in the conventional filter medium for anaerobic treatment, that is, the filter medium for anaerobic treatment has a relatively low sludge holding ability and sludge trapping property, and thus sufficient anaerobic treatment is not possible. It is difficult to solve the problem that it is difficult to reduce the size of the treatment device significantly and it takes time to perform secondary processing and filling of the anaerobic treatment filter medium, and the sludge trapping property and the sludge holding capacity are high, In addition, a method for producing anaerobic filter media that can perform anaerobic treatment of sewage without clogging and the like, can easily perform degassing and cleaning, and can be manufactured relatively easily and has excellent workability. To provide.

[0009]

[0010]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
In the method for producing a filter medium for anaerobic treatment of the present invention, a filament made of a thermoplastic resin that is heated and melted downward from a plurality of nozzle holes is spun, and the tip of the filament is placed near the water surface in a cooling water tank. A plurality of filaments that are received by a roughly spherical retainer with a shrinkable and diametrically adjustable chasen structure that rotates vertically at a position, and that the distal end of the filament is deformed into a curl shape on the retainer and curled. The bodies are sequentially wound in a spherical shape around the outer periphery of the holding body while being brought into contact and fusion with each other, and then the spinning of the filaments from the nozzle holes is stopped. For a certain period of time, and finally, a substantially hollow spherical body completely cooled and hardened is extracted from the holder.

[0011]

[Function] A molten thermoplastic resin thread spun from a plurality of nozzle holes is a substantially spherical holder of a shrinkable and expandable chasen structure which is vertically rotated near the water surface in a cooling water tank. It is received and cooled rapidly by touching the cooling water. Due to the rapid cooling, a solidifying force acts to deform the lower end of the filament into a so-called curl shape. In addition, the plurality of filaments that have been deformed into a curl form contact with each other, and enter into the cooling water in a state where they are mutually contacted and fused by the rotation of the holder, and the contact portions are hardened by being hardened. Is fixed. Then, the plurality of filaments are continuously supplied to the holder, and the curl-like filaments are wound around the outer periphery of the holder in a substantially spherical shape. When the curled filament is wound around the entire periphery of the holding body, the spinning of the filament from the nozzle hole is stopped, and the holding body holds the curled filament in the cooling water for a certain period of time. Dipped. Thereby, the filament is completely cooled and hardened, and a substantially hollow spherical body is formed. That is, a substantially hollow spherical filter medium is formed. Thereafter, the spherical body is extracted from the holding body to obtain a substantially hollow spherical filter medium for anaerobic treatment.

The anaerobic filter medium is filled into the space of the anaerobic treatment section of the sewage treatment apparatus to form a so-called anaerobic filter bed. Thus, while the sewage flowing into the anaerobic treatment section passes through the filter bed made of the anaerobic treatment filter medium, solid matter contained therein is captured by the filter medium, and so-called filtration processing is performed. In addition, the solid matter containing the sludge is captured and held by the filter medium for anaerobic treatment, whereby the anaerobic microorganisms in the sludge sufficiently propagate and the anaerobic microorganisms promote the decomposition treatment of the sewage.

The filter medium for anaerobic treatment collects a large number of filaments made of synthetic resin curled in a curl shape and fixes them together to form a substantially hollow body having a reticulated spherical wall of a predetermined thickness. Because of the spherical shape, the trapping rate of sludge can be greatly improved without clogging of the filter medium, and the processing capacity in the anaerobic treatment section is greatly improved. In addition, since the anaerobic treatment filter medium is formed in a substantially spherical shape, only the anaerobic treatment section of the sewage treatment apparatus is charged,
The anaerobic treatment part is naturally and orderly filled. As a result, the filter bed for anaerobic treatment can be formed easily and quickly, and the workability is extremely excellent. Further, the filter medium for anaerobic treatment does not need to be subjected to secondary processing or the like after the formation of the filter medium, and can be manufactured relatively easily.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIGS. 1 to 3 show a filter medium A for anaerobic treatment according to the present invention. The filter medium A for anaerobic treatment has a net-like spherical wall made of a thread-like material of a thermoplastic resin such as polypropylene or polyethylene by a method described later. And has an outer diameter D of about 1
50 mm, and the thickness t of the reticulated spherical wall is selected to be about 25 mm. The thermoplastic resin thread forming the net-like spherical wall has an outer diameter selected to be about 0.5 to 3.0 mmφ, and has a large number of curls having a diameter of about 10 to 40 mm. They are fixed to each other.

The external dimensions of the filter medium A are determined mainly from the capacity of the anaerobic filter tank to which the filter medium A is applied, the properties of sewage, anaerobic treatment performance (sludge trapping property, sludge retention rate, etc.), the method of manufacturing the filter medium A, and the like. Things. For example, if the outer diameter D of the filter medium A is 60 mm or less and 400 mm or more, it becomes difficult to manufacture the filter medium A. From this point, the outer diameter D is limited to about 60 to 400 mm. Further, the thickness t of the spherical wall of the filter medium A is determined mainly from the viewpoint of clogging and sludge trapping property, and when the outer diameter D of the filter medium A is 100 mm, the thickness of the spherical wall is 10 mm.
It has been confirmed by actual machine tests that when the outer diameter D is about 200 mm and the outer diameter D is about 200 mm, the thickness of the spherical wall is about 20 mm to about 30 mm.

FIGS. 4 to 7 show an example of a filter material producing apparatus used for producing the filter medium A for anaerobic treatment according to the present invention, wherein 1 is a synthetic resin supply apparatus, 2 is a nozzle, 3 is a cutter mechanism, 4 is a cooling water tank, 5 is a rotating disk, 6 is a disk drive mechanism, 7 is a holder, 8 is a holder drive mechanism, 9 is a pressing mechanism, 10 is a withdrawal mechanism, 11 is a chute, and P is thermoplastic. resin, P ₁ is the filament, W is the cooling water, WL is cooled water.

The synthetic resin supply device 1 uses a conventionally known screw type extrusion molding machine, and is a granular thermoplastic resin material (thermoplastic synthetic resin material such as polypropylene or polyethylene) charged into the hopper 1a. Is passed through the extruder 1b by rotation of a screw (not shown), and is melted into a fluid state by heating from a heater (not shown), and the melted thermoplastic resin P is kneaded to an appropriate viscosity by the screw. The pressure is fed into the nozzle 2.

As shown in FIGS. 4 and 5, the nozzle 2 is provided at the tip of the extruder 1b, and is disposed symmetrically at a position above the cooling water surface WL in the cooling water tank 4.
The nozzle holes 2a of the nozzles 2 are arranged in series at intervals of 5 mm to 10 mm and in a range of 100 mm to 150 mm, and the diameter of the nozzle holes 2a is about 0.1 mm.
5 mm to 2.5 mm is selected. In addition, nozzle hole 2
The distance from a to the cooling water surface WL is approximately 400 mm to 60 mm.
0 mm is selected.

The cutter mechanism 3, as shown in FIG.
Hydraulic cylinder arranged in a horizontal position in the vicinity of the nozzle 2
3a and attached to the tip of the rod of the hydraulic cylinder 3a
The filament P spun from the nozzle hole 2a₁Disconnect
From the nozzle hole 2a.
₁Is spun for a certain period of time and expands and contracts to form a filament P ₁
Is to cut off.

The rotating disk 5 has a central portion attached to a rotating shaft 12 rotatably supported between side walls 4a of the cooling water tank 4, and rotates vertically in the cooling water tank 4 as the rotating shaft 12 rotates. It is supposed to. Note that the amount of the cooling water W stored in the cooling water tank 4 is selected so that the cooling water level WL comes to the center of the rotating disk 5.

The disk drive mechanism 6 drives the rotary shaft 12 to rotate the rotary disk 5 vertically in the direction of arrow a in FIG. 4, and includes a motor 6a and a transmission mechanism 6b (for example, a gear type transmission mechanism). ) Etc. The drive mechanism 6 for the disk is drive-controlled so that the rotary disk 5 rotates intermittently by 90 ° at regular intervals.

The holders 7 are arranged on the outer peripheral edges of both sides of the rotating disk 5 so as to be vertically rotatable at 90 ° intervals, and are configured in a chasen structure which can be reduced and expanded in diameter. That is, each holder 7
As shown in FIGS. 4 to 6, a plurality of (about 8 to 12) elastically deformable disks 7b are rotatably mounted on the outer peripheral edge of the rotating disk 5 via a support shaft 7a. Is formed by arranging a curved steel wire 7c in an annular shape,
The distal end of each steel wire 7c is rotated by a pressing mechanism 9 to be described later.
By pressing a certain distance to the side, the diameter gradually increases and is deformed into a substantially spherical shape. When the pressed state is released, the drum is restored to a substantially drum shape.
The position at which the holder 7 is attached to the rotating disk 5 is such that when the rotating disk 5 that is rotating intermittently stops, the center of the holder 7 comes to the position of the cooling water surface WL and the holder 7 Some of the steel wires 7c (the steel wires 7c located in the vicinity of the cooling water surface WL) are set to be directly below the nozzle 2.

As shown in FIG. 6, the driving mechanism 8 for the holder is
A driven gear 8a fitted to a support shaft 7a of each holding body 7, a drive shaft 8b rotatably supported between the side walls 4a of the cooling water tank 4 near the cooling water surface WL, and a drive shaft 8b fitted to the drive shaft 8b. The driving gear 8c is configured to be freely meshable with the driven gear 8a, a motor 8d for driving the driving shaft 8b to rotate, and the like. Driven gear 8a and drive gear 8
and c. Therefore, the cooling water level W
The holder 7 having reached the position near L is vertically rotated by the holder driving mechanism 8 in the direction of arrow B in FIG.

The pressing mechanism 9 is, as shown in FIGS.
The hydraulic cylinder 9a is disposed in a horizontal position on the side wall 4a of the cooling water tank 4 and faces the holder 7 near the cooling water surface WL. The hydraulic cylinder 9a is attached to a rod of the hydraulic cylinder 9a. Disc-shaped pressing body 9 that can freely contact line 7c
When the fluid pressure cylinder 9a extends, the pressing body 9b abuts on the steel wire 7c to bend the steel wire 7c into a substantially spherical shape, and when the fluid pressure cylinder 9a is shortened, the pressing body 9b The steel wire 7c is separated from the steel wire 7c.

As shown in FIG. 5, the extracting mechanism 10 includes a first hydraulic cylinder 10a, which is symmetrically disposed at a position above the cooling water tank 4 and is swingable vertically. A second hydraulic cylinder 10b for vertically swinging the hydraulic cylinder 10a, a bifurcated extraction body 10c attached to the rod of the first hydraulic cylinder 10a, and capable of being loosely fitted to the holder 7 at the uppermost position, etc. And a spherical body (filter medium A) wound around the outer periphery of the holder 7
It is extracted from. Also, the first hydraulic cylinder 10
a is a standby position (solid line position in FIG. 5) in a posture inclined upward by the second fluid pressure cylinder 10b, and an actuated position in a horizontal posture, which is lowered from the standby position to face the holding member 7 at the uppermost position. (The position indicated by the broken line in FIG. 5). Further, when the first hydraulic cylinder 10a is extended to the operating position in the extended state, the extracted body 10c is loosely fitted to the base end side of the steel wire 7c of the holder 7 at the uppermost position. The filter medium A is selected so that the filter medium A can be removed from the steel wire 7c of the body 7.

Next, the case where the filter medium A for anaerobic treatment is manufactured by using the filter medium manufacturing apparatus will be described. The granular thermoplastic resin material (a thermoplastic synthetic resin material such as polypropylene or polyethylene) charged into the hopper 1a of the synthetic resin supply device 1 is melted into a fluid state by heating from a heater (not shown), and is screwed. And the mixture is kneaded to an appropriate viscosity and fed into the nozzle 2.

[0027] Thermoplastic resin P pumping molten state into the nozzle 2 is spun from the nozzle holes 2a, it becomes the filament P ₁ descends into the cooling water tank 4 (see FIGS. 4 and 5).
The holding member 7 located near the cooling water surface WL is deformed into a substantially spherical shape by the pressing mechanism 9 before the thread P ₁ descends, and the holding member driving mechanism 8 rotates the holding member 7 in a certain direction in the direction of arrow B. It is rotated at a speed (the speed at which the holder 7 makes one rotation in about 20 to 30 seconds) (see FIGS. 8 to 11).

The plurality of filaments P ₁ spun from each nozzle hole 2 a are received by the steel wire 7 c of the spherical holder 7 rotating vertically near the cooling water surface WL and come into contact with the cooling water W. It is rapidly cooled. The lower end of the filament P ₁ solidifying force acts rapidly cooled is gradually deformed into a so-called curled. Further, the plurality of curled bodies formed on the holding member 7 are contact-fused with each other, and enter the cooling water W in a state where they are contact-fused with each other by the rotation of the holding member 7, and the contact portion is hardened. By doing so, they are firmly fixed to each other (see FIGS. 12 and 13). The filament P ₁
The diameter of the curl can be changed by adjusting the viscosity of the synthetic resin material, the diameter of the nozzle 2, and the like.
φ has been selected.

Then, the plurality of filaments P ₁ are continuously supplied to the holder 7, and the curl-like filaments P ₁ are continuously wound around the outer periphery of the steel wire 7 c of the holder 7. (See FIGS. 12 and 13).

The curled filament P is applied to the entire outer periphery of the holder 7.
₁ is wound, the cutter mechanism 3 is operated, and the filament P is spun from the nozzle hole 2a by the cutter 3b.
₁ is cut supply of the filamentous body P ₁ is made to stop (see Figure 14). Also, the fluid pressure cylinder 9a of the pressing mechanism 9
And the pressed state of the holding member 7 is released, and the rotating disk 5 is turned 90 ° in the direction of arrow a by the disk driving mechanism 6.
Then, the curled filament P ₁ wound around the holder 7 is immersed in the cooling water W for a certain time. Thus, filaments P ₁ is completely cooled and hardened, substantially hollow spheres (filter material A) is formed.

When the rotating disk 5 is rotated by 90 ° and the holder 7 positioned at the uppermost position is lowered to a position near the cooling water surface WL, the holder 7 is rotated by the holder driving mechanism 8. At the same time, the holding mechanism 7 is deformed into a substantially spherical shape by operating the pressing mechanism 9 (see FIGS. 8 to 11).

[0032] Further, when the holding member 7 is deformed approximately spherical, continue with filament P ₁ is spun from the nozzle holes 2a, the distal end is received by the holder 7 of the spherical holder in the same manner as described above 7 the outer peripheral filament P ₁ curled can go wound in substantially hollow spheres (filter material a) is formed.

[0033] In this way, the filament P ₁ of each holding member 7 successively comes to the lower position curled nozzle 2 is gradually being wound around a and hollow spherical shape.

When the substantially hollow spherical body (filter medium A) wound around the holding member 7 comes to the uppermost position due to the intermittent rotation of the rotating disk 5, the extracting mechanism 10 is operated to release the holding member 7 from the holding member 7. Remove the filter medium A. That is, the first hydraulic cylinder 10a in the standby position extends and descends from the standby position to the operating position, and the extracted body 10c is connected to the steel wire 7c of the holding body 7.
(See FIG. 15). Thereafter, the first fluid pressure cylinder 10a is shortened, and the spherical body (filter medium A) is extracted from the holder 7 by the extraction body 10c. The extracted filter medium A falls on a chute 11 arranged above the cooling water surface WL, and is moved by the chute 11 into the cooling water tank 4.
It is taken out (see FIG. 16).

In this way, a substantially hollow spherical anaerobic filter medium A is continuously formed.

The filter medium A for anaerobic treatment produced as described above is filled in the space between the filter medium receiver and the filter medium retainer, which is horizontally disposed at a fixed interval inside the anaerobic treatment section,
A so-called anaerobic filter bed is formed.

The sewage that has flowed into the anaerobic treatment section passes through a filter bed made of the anaerobic treatment filter medium A, and solids contained therein are captured by the filter medium A, so-called filtration is performed. . Further, the solid matter containing the sludge is captured and held by the filter medium A for anaerobic treatment, whereby the anaerobic microorganisms in the sludge sufficiently propagate and the decomposition treatment of the sewage by the anaerobic microorganisms is enhanced.

The simulated sludge simulates the trapping property of the anaerobic treatment filter medium A and the trapping property of the conventional anaerobic treatment filter medium (a thin-plate filter medium, a net-like thick corrugated sheet filter medium, and a basket-like cylindrical filter medium). , It was found that the filter medium A had a significantly improved sludge trapping rate as compared with the conventional filter medium.

That is, an anaerobic filter bed of 1 mx 1 mx 0.5 m (height) is formed inside an anaerobic filter tank having a capacity of about 1.3 m ³ , and SS is introduced from the inlet into the anaerobic filter tank. Concentration 32
00 ppm artificial wastewater was continuously supplied at a flow rate of 20 l / min, and the SS concentration in the effluent discharged from the discharge port was continuously measured, and the average value was calculated. In this test, it is a matter of course that the total surface area of the filter media of each anaerobic filter bed is set to almost the same value. As a result, in the filter medium A , the SS concentration in the effluent was 480 p.
pm, and about 85% of SS (suspended matter) was captured. On the other hand, in the case of a thin-plate type filter medium,
The concentration is 3200 ppm, the SS concentration in the effluent is 1300 ppm for the net-like thick corrugated filter medium, and the SS concentration in the effluent is 2000 ppm for the basket-like cylindrical filter medium, and the trapping rate is 0% and about 60%, respectively. It was about 38%.

[0040]

As described above, the filter medium for anaerobic treatment of the present invention
The manufacturing method is made of thermoplastic resin heated and melted from multiple nozzle holes.
The resin is spun out and the filaments are placed near the water surface in the cooling water tank.
With a spherical holder that is vertically rotating
Stop and deform into a curl shape, and deform into a curl shape
The outside of the holding body is brought into contact with the
Circular filaments are sequentially wound around the circumference, and then
Approximately in the middle of cooling and hardening by stopping the spinning of the filament from the chisel hole
Empty spheres are removed from the holder. That
As a result, it is easy to manufacture a filter medium with the desired outer diameter.
It is not necessary to perform secondary processing after forming the filter media.
No. Further, the filter for anaerobic treatment obtained by the production method of the present invention.
The material is made of a number of curled synthetic resin threads.
By assembling the bodies and sticking them together,
A substantially hollow sphere with a reticulated sphere wall of predetermined thickness
You. As a result, compared to the conventional filter media for anaerobic treatment,
Greatly improves the sludge trapping rate without clogging
And the processing capacity in the anaerobic treatment section is large.
Improve in width. Furthermore, the filter medium for anaerobic treatment is almost spherical.
Into the anaerobic treatment section of the sewage treatment equipment
Simply fills the anaerobic treatment section naturally
become. As a result, the filter for anaerobic treatment can be formed easily and quickly.
And workability is extremely excellent.

[Brief description of the drawings]

FIG. 1 is a front view of a filter medium for anaerobic treatment according to an embodiment of the present invention.

FIG. 2 is a plan view of a filter medium for anaerobic treatment.

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a schematic front view in which a part of a filter medium manufacturing apparatus used for manufacturing a filter medium for anaerobic treatment is broken.

FIG. 5 is a sectional view taken along line CC of FIG. 4;

FIG. 6 is a sectional view taken along line DD of FIG. 4;

FIG. 7 is a cross-sectional view of the nozzle.

FIG. 8 is a partial front view showing a state in which a holder near a cooling water surface is vertically rotated by a holder driving mechanism.

FIG. 9 is a plan view of FIG. 8;

FIG. 10 is a partial front view showing a state where a holding body near a cooling water surface is deformed into a spherical shape by a pressing mechanism.

FIG. 11 is a plan view of FIG. 10;

FIG. 12 is a partial front view showing a state in which a thread made of a synthetic resin is wound around a holder near a cooling water surface.

FIG. 13 is a side view of FIG.

FIG. 14 is a partial front view showing a state in which a thread made of synthetic resin is wound around the entire outer periphery of the holder near the cooling water surface.

FIG. 15 is a partial side view showing a state where a filter medium is extracted from a holder at an uppermost position by an extraction mechanism.

FIG. 16 is a partial side view showing a state where a filter medium has been extracted from the holder at the uppermost position.

FIG. 17 is a schematic cross-sectional view showing one example of a merged treatment septic tank utilizing a filter medium for anaerobic treatment.

[Explanation of symbols]

A is a filter medium, P is a thermoplastic resin material, P ₁ is a filament, W is cooling water, WL is a cooling water surface, 2 is a nozzle hole, 4 is a cooling water tank,
7 is a holder.

Claims (1)

(57) [Claims] 1. A plurality of nozzle holes (2a) heating and melting downwardly from thermoplastic resin (P) made of the filament (P ₁₎
And a substantially spherical holder (7) of a shrinkable and expandable chasen structure in which the tip of the filament (P ₁ ) is vertically rotated near the water surface (WL) in the cooling water tank (4). in receiving, together with transform a curled tip portion of the thread-like member (P ₁₎ on the holder (7), while contact fusing a plurality of filaments which deform the curled a (P ₁₎ to each other The filament (P ₁ ) is sequentially wound around the outer periphery of the holder (7) in a spherical shape, and then, the spinning of the filament (P ₁ ) from the nozzle hole (2a) is stopped, and the curled filament (P ₁ ) is wound on the holder (7) ) Is immersed in cooling water (W) for a certain period of time while holding the hollow material, and finally a substantially hollow spherical body completely cooled and hardened is extracted from the holding body (7). Production method.