JP7501904B2 - Microorganism-retaining carrier, method for producing the microorganism-retaining carrier, wastewater treatment method, and wastewater treatment device - Google Patents

Description

The present invention relates to a microorganism-retaining carrier, a method for manufacturing a microorganism-retaining carrier, a wastewater treatment method, and a wastewater treatment device.

Wastewater treatment is an essential technology for livestock farmers to treat wastewater from livestock barns. Currently, wastewater treatment methods that use microorganisms, such as the activated sludge method, are widely used.

A known wastewater treatment method using microorganisms is a sewage treatment method using a microorganism-holding carrier containing carbon fiber. In this sewage treatment method, a large amount of microorganisms can be attached to the carbon fiber, and by carrying out an aeration process or the like, the microorganisms attached to the carbon fiber decompose organic matter in the wastewater. There are various types of microorganism-holding carriers used in wastewater treatment, depending on the purpose, such as sewage treatment performance and durability.

For example, Patent Document 1 discloses a method for treating wastewater, which includes a step of subjecting wastewater to an aeration treatment in the presence of fixed-bed carbon fiber. According to Patent Document 1, the wastewater treatment method described above is capable of treating the wastewater while suppressing the release of nitrous oxide from the wastewater.

Patent Document 2 discloses a microorganism carrier having protrusions on a material that can be positively charged in water. The protrusions are used to attach microorganisms, and are fixed to the axis of the microorganism carrier by clamping or gluing. Carbon fiber is given as an example of the material of the protrusions. According to Patent Document 2, the microorganism-holding carrier makes it easier to capture microorganisms on the protrusions, and has the effect of maintaining an optimal environment for the growth of microorganisms.

Patent Document 3 discloses a water treatment member having a rod-shaped support, a fiber member made of carbon fiber, and a string-shaped or band-shaped flexible member, all arranged parallel to the direction of flow of the treated water. The fiber member (fibrous carrier) of the water treatment member is used to attach microorganisms, and is fixed to a flexible member (backbone material) that serves as an axis by bonding or welding, or the fiber member and the flexible member are integrally formed. According to Patent Document 3, the water treatment member can efficiently repair sludge, is less likely to clog the filter bed, and can withstand the load when the water in the tank is discharged.

JP 2014-205136 A Japanese Patent Application Laid-Open No. 9-252770 JP 2011-147886 A

In wastewater treatment, when aeration is performed on wastewater in a wastewater treatment tank, especially when air comes into direct contact with the microorganism-retaining carrier, the flow of wastewater in the wastewater treatment tank is very fast, placing a strain on the microorganism-retaining carrier. For this reason, when the microorganism-retaining carriers described in Patent Documents 2 and 3, in which the carrier portion to which the microorganisms adhere is fixed by adhesive or the like, are used under aeration treatment, there is a risk that the carrier portion that retains the microorganisms will fall off or be damaged.

In addition, if the water treatment component described in Patent Document 3 is formed integrally with the fibrous carrier and the base material, it will be time-consuming and the manufacturing costs will be high.

The present invention has been made in consideration of the above circumstances, and aims to provide a microorganism-retaining carrier in which the carrier portion that retains the microorganisms is less likely to fall off and which can be manufactured at low cost, and a method for manufacturing the same. Another aim of the present invention is to provide a wastewater treatment method and a wastewater treatment device that use the above-mentioned microorganism-retaining carrier.

A microorganism-holding carrier according to one embodiment of the present invention for solving the above problems includes a string, a number of threads including carbon fiber, each of which has a portion wound around the string, and a cover sheet that covers the string and the portions of the number of threads that are wound around the string.

A method for manufacturing a microorganism-retaining carrier according to one embodiment of the present invention for solving the above problems includes the steps of winding a portion of each of a plurality of threads containing carbon fiber around a string, covering the string and the portions of the plurality of threads that are wound around the string with a covering sheet, and fixing the covering sheet and the portions of the plurality of threads that are covered with the covering sheet.

In addition, a wastewater treatment method according to one embodiment of the present invention for solving the above problem includes a step of supplying oxygen to wastewater in a wastewater treatment tank in which the microorganism-holding carrier is arranged so as to come into contact with the wastewater.

In addition, a wastewater treatment device according to one embodiment of the present invention for solving the above problem includes a wastewater treatment tank that contains wastewater, an oxygen supply device that supplies oxygen to the wastewater in the wastewater treatment tank, and the microorganism-holding carrier that is arranged to contact the wastewater in the wastewater treatment tank.

The present invention provides a microorganism-retaining carrier in which the carrier portion that retains the microorganisms is less likely to fall off and which can be manufactured at low cost, a method for manufacturing the carrier, and a wastewater treatment method and wastewater treatment device that use the microorganism-retaining carrier.

FIG. 1 is a schematic diagram showing the configuration of a microorganism-holding carrier according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of a microorganism-holding carrier according to one embodiment of the present invention. FIG. 3 is a flow chart of a method for producing a microorganism-retaining carrier according to one embodiment of the present invention. FIG. 4 is a schematic diagram showing a method for producing a microorganism-holding carrier according to one embodiment of the present invention. FIG. 5 is a schematic diagram showing the configuration of a wastewater treatment device according to one embodiment of the present invention. FIG. 6 is a schematic diagram showing the configuration of a microorganism-holding carrier according to a modified example of the present invention.

The following describes in detail the embodiments of the present invention. Note that the present invention is not limited to the following embodiments.

1. Microorganism-retaining carrier and its manufacturing method (Structure of the microorganism-retaining carrier)
1 and 2 are schematic diagrams showing the configuration of a microorganism retention carrier 100 according to one embodiment of the present invention. In Fig. 2, the configuration of the invisible parts of the microorganism retention carrier 100 is shown by dashed lines. As shown in Fig. 1 and Fig. 2, the microorganism retention carrier 100 has a plurality of threads 110, a string 120, and a cover sheet 130.

Each of the multiple threads 110 contains carbon fiber and functions as a carrier for attaching microorganisms. A portion of each of the multiple threads 110 is wound around the string 120 at a different position.

The type of the multiple threads 110 is not particularly limited as long as each thread contains carbon fiber and can adhere microorganisms. Each of the multiple threads 110 may contain fibers other than carbon fiber, or may contain only carbon fiber. The number of carbon fibers (filaments) contained in one thread 110 is also not particularly limited. In addition, each of the multiple threads 110 may be surface-treated.

The shape of the cross section perpendicular to the extension direction of the multiple threads 110 is not particularly limited, and is, for example, approximately circular or approximately rectangular. The thickness of the multiple threads 110 is not particularly limited, but is preferably 3 mm or more and 7 mm or less. Here, the "thickness of the thread 110" refers to the maximum outer diameter of the thread 110 when the cross section of the thread 110 is, for example, approximately circular, and refers to the width (length of the long side) in the direction perpendicular to the extension direction of the thread 110 when the cross section of the thread 110 is, for example, approximately rectangular. If the thickness of the thread 110 is 3 mm or more, it is easy to ensure the strength of the thread 110 that can withstand the flow of sewage. If the thickness of the thread 110 is 7 mm or less, the specific surface area of the thread is large, making it easy to sufficiently attach microorganisms. In addition, when sewage treatment is performed using multiple microorganism-holding carriers 100, it is easy to leave a gap between adjacent microorganism-holding carriers 100. For example, T700SC-24000 (manufactured by Toray Industries, Inc.) is an example of a commercially available product of the thread 110.

The length of the multiple threads 110 is not particularly limited, but it is preferable that each be 30 cm or more and 50 cm or less. If it is 30 cm or more, it is easy to sufficiently attach microorganisms to the multiple threads 110. If it is 50 cm or less, it is difficult for adjacent microorganism retention carriers 100 to become entangled when multiple microorganism retention carriers 100 are used to treat wastewater. The lengths of the multiple threads 110 may be the same or different.

In the portion covered by the covering sheet 130, the spacing between adjacent threads 110 is not particularly limited, but is preferably 1 cm or more and 2 cm or less. If it is 1 cm or more, the multiple threads 110 are less likely to become entangled with each other in the sewage treatment tank. If it is 2 cm or less, the density of the multiple threads 110 to which microorganisms are attached increases, making it easier to improve the efficiency of sewage treatment. Note that the spacing between adjacent threads 110 may be equal or different.

It is preferable that the multiple threads 110 wound around the string 120 each extend in approximately the same direction to prevent them from becoming tangled.

In this embodiment, each of the multiple threads 110 may be partially wrapped around the string 120, or may be further knotted and/or bonded with an adhesive or the like.

The string 120 is a part of the microorganism retention carrier 100 for winding a portion of each of the multiple threads 110 containing carbon fiber, and functions as an axis for each of the multiple threads 110. By using a relatively soft string 120, rather than a hard rod, as the axis for each of the multiple threads 110, even if the microorganism retention carrier 100 hits the pipes in the sewage treatment tank due to the flow of sewage during sewage treatment, the pipes are less likely to be damaged.

The thickness of the string 120 is not particularly limited as long as it can be wrapped around multiple threads 110, but from the viewpoint of improving durability, it is preferable that the string 120 be thicker than the threads 110, and more preferably be at least three times the thickness of the threads 110.

The length of the string 120 is not particularly limited, and is adjusted appropriately according to the number of threads 110 wound around the string 120. The material of the string 120 is not particularly limited. Examples of materials for the string 120 include resin, silk, leather, etc. The shape of the cross section perpendicular to the extension direction of the string 120 is not particularly limited, and is, for example, approximately circular or approximately rectangular.

The covering sheet 130 is a sheet that covers the string 120 and the portions of the multiple threads 110 that are wrapped around the string 120. The type of covering sheet 130 is not particularly limited as long as it can perform the above-mentioned functions and can fix the multiple threads 110. Examples of covering sheets 130 include cloth, resin sheets, leather, etc. From the standpoint of durability and cost reduction, it is preferable that the covering sheet 130 is a resin cloth. Examples of resin cloth include polyester cloth such as Hurricane (registered trademark) by Teijin Frontier Co., Ltd.

In this embodiment, at least a portion of each of the multiple threads 110 is exposed to the outside without being covered by the covering sheet 130, and functions as a carrier for microorganisms to adhere to. This allows the portions of the multiple threads 110 wound around the string 120 to be covered with the covering sheet 130, while efficiently decomposing organic matter in the wastewater. The smaller the proportion of the portions of the multiple threads 110 that are covered by the covering sheet 130 relative to the total length of the threads 110, the more preferable it is, for example, 50% or less, 25% or less, or 10% or less.

The covering sheet 130 may cover only a portion of the string 120, including the portion around which the multiple threads 110 are wound, or may cover the entire string 120. When multiple microorganism retention carriers 100 are used in a linked manner, it is preferable to cover only a portion of the string 120, including the portion around which the multiple threads 110 are wound. In this way, the portion of the string 120 that is not covered by the covering sheet 130 can be tied to the string 120 of another microorganism retention carrier 100.

The shape and size of the covering sheet 130 are not particularly limited as long as it can cover the string 120 and the portions of the multiple threads 110 that are wound around the string 120. The shape of the covering sheet 130 is, for example, approximately rectangular or approximately circular. In this embodiment, the shape of the covering sheet 130 is rectangular. In addition, the thickness of the covering sheet 130 is not particularly limited, and may be set appropriately depending on the type of covering sheet 130, the required strength, etc.

As shown in FIG. 2, in this embodiment, the portion of the multiple threads 110 wound around the string 120 is covered with two covering sheets 130, but it may be covered with a single covering sheet 130. It may also be covered with three or more covering sheets 130 of different sizes.

The covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 are fixed to each other. Here, "fixing" does not only mean that the multiple threads 110 are fixed to the covering sheet 130 so that they cannot move at all, but also includes that the multiple threads 110 can move to a certain extent relative to the covering sheet 130, but are fixed so that the multiple threads 110 do not fall out of the covering sheet 130. The method of fixing the covering sheet 130 and the multiple threads 110 is not particularly limited. For example, the covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 may be fixed by sewing them together, the covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 may be fixed by staples, the covering sheet 130 and the multiple threads 110 may be fixed by adhesive or the like, or a combination of these may be used. As shown in Figures 1 and 2, in this embodiment, the covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 are sewn together in a straight line at two points with sewing thread 140 and fixed. This makes it difficult for the multiple threads 110 wound around the string 120 to shift significantly due to the flow of the wastewater during wastewater treatment. In addition, even under conditions where the wastewater flows quickly, the multiple threads 110 are unlikely to fall off the string 120. The type of sewing thread 140 is not particularly limited and may be appropriately selected from known threads.

The method for manufacturing the microorganism-retaining carrier 100 according to this embodiment is not particularly limited. For example, the microorganism-retaining carrier 100 can be manufactured by the method described below.

(Method for producing a microorganism-retaining carrier)
Fig. 3 is a flow chart of a method for producing a microorganism-retaining carrier according to this embodiment. Figs. 4A to 4C are schematic diagrams showing a method for producing a microorganism-retaining carrier 100.

As shown in Figures 3 and 4A-C, the method for manufacturing the microorganism retention carrier 100 according to this embodiment includes: (1) a step of winding a portion of each of the multiple threads 110 containing carbon fiber around the string 120 (step S10, Figure 4A); (2) a step of covering the string 120 and the portions of the multiple threads 110 wound around the string 120 with a covering sheet 130 (step S20, Figure 4B); and (3) a step of fixing the covering sheet 130 and the threads 110 covered with the covering sheet 130 (step S30, Figure 4C). Each step will be described below.

(1) A step of winding a plurality of threads around a string (step S10)
First, as shown in FIG. 4A, a portion of each of the multiple threads 110 is wound around a string 120.

The method of winding the thread 110 around the string 120 is not particularly limited. As described above, the thread 110 may not only be wound around the string 120, but may also be tied to the string 120. Also, the portion of the thread 110 that is wound around the string 120 may be glued with adhesive.

(2) Covering with a covering sheet (step S20)
Next, as shown in FIG. 4B, the string 120 and the portions of the plurality of threads 110 wound around the string 120 are covered with a covering sheet 130.

The method of covering the string 120 and the portion of the thread 110 wrapped around the string 120 with the covering sheet 130 is not particularly limited. In this embodiment, two covering sheets 130 are used to sandwich the string 120 and the portion of the thread 110 wrapped around the string 120, thereby covering the string 120 and the portion of the thread 110 wrapped around the string 120. Note that in this embodiment, the string 120 and the portion of the thread 110 wrapped around the string 120 may be covered by sandwiching them using only one covering sheet 130, or three or more covering sheets 130 of different sizes may be used to cover the string 120 and the portion of the thread 110 wrapped around the string 120.

(3) Step of fixing the covering sheet and the yarn (step S30)
Finally, as shown in FIG. 4C, the covering sheet 130 and the multiple threads 110 covered with the covering sheet 130 are fixed together.

As described above, the method of fixing the covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 is not particularly limited. In this embodiment, the covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 are fixed by sewing them together with sewing thread 140. In addition, the location where the covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 are sewn together is not particularly limited, but it is preferable that the location is near the edge of the covering sheet 130 corresponding to the boundary between the part of the multiple threads 110 covered by the covering sheet 130 and the part not covered by the covering sheet 130. This makes it difficult for the multiple threads 110 to fall off the string 120. In this embodiment, in FIG. 4C, the vicinity of the right edge and the vicinity of the left edge of the covering sheet 130 are sewn together along the extension direction of the string 120.

2. Wastewater Treatment Method Next, a wastewater treatment method using the microorganism-holding carrier 100 according to the present embodiment will be described. Note that the present invention is not limited to the following embodiment.

A wastewater treatment method according to one embodiment of the present invention includes a step of supplying oxygen to wastewater in a wastewater treatment tank in which a microorganism-holding carrier 100 is arranged so as to contact the wastewater.

The microorganism-retaining carrier 100 may be arranged so as to be in contact with the wastewater in the wastewater treatment tank, for example, suspended from above the wastewater treatment tank. From the viewpoint of improving the efficiency of wastewater treatment, it is preferable that the microorganism-retaining carrier 100 is arranged so as to be immersed in the wastewater. By arranging the microorganism-retaining carrier 100 so as to be in contact with the wastewater, the microorganisms in the wastewater can be attached to the multiple threads 110.

The microorganism-retaining carrier 100 may be used alone, or multiple microorganism-retaining carriers 100 may be connected together, for example by tying them together. When the volume of wastewater in the wastewater treatment tank is large, it is preferable to use multiple microorganism-retaining carriers 100 in order to improve the efficiency of wastewater treatment.

The method of supplying oxygen to the wastewater is not particularly limited, and includes, for example, aeration using an aeration device, supplying oxygen from an oxygen cylinder, and the like. When oxygen is supplied to the wastewater, the microorganism-holding carrier 100 may be in direct contact with the supplied oxygen. By supplying oxygen to the wastewater, the microorganisms attached to the multiple threads 110 can decompose organic matter in the wastewater.

3. Wastewater Treatment Apparatus Finally, a wastewater treatment apparatus that can be used in carrying out the above-mentioned wastewater treatment method will be described. Note that the present invention is not limited to the following embodiments.

Figure 5 is a schematic diagram showing the configuration of a wastewater treatment device 200 according to this embodiment. As shown in Figure 5, the wastewater treatment device 200 has a wastewater treatment tank 210, an oxygen supply device 220, and a microorganism retention carrier 100.

The sewage treatment tank 210 contains sewage. There are no particular limitations on the shape or size of the sewage treatment tank 210. The shape of the sewage treatment tank is, for example, approximately rectangular or cylindrical.

The oxygen supplying device 220 supplies oxygen to the wastewater 240 in the wastewater treatment tank 210. The configuration of the oxygen supplying device 220 is not particularly limited as long as it can supply oxygen to the wastewater 240 in the wastewater treatment tank. Examples of the oxygen supplying device 220 include, for example, an aeration device and an oxygen cylinder. In this embodiment, the oxygen supplying device 220 is an aeration device.

The microorganism-retaining carriers 100 are arranged so as to be in contact with the wastewater 240 in the wastewater treatment tank 210. In this embodiment, multiple microorganism-retaining carriers 100 are suspended from brackets 230 and immersed in the wastewater 240.

As shown in FIG. 4, the wastewater treatment device 200 may further include a wastewater supply device 250 that supplies wastewater, and a drain pipe 260 that drains the wastewater 240 after the wastewater treatment.

(effect)
The microorganism-retaining carrier 100 according to the present embodiment is easy to manufacture at low cost because the carrier portion that retains the microorganisms is unlikely to fall off. Therefore, by using the microorganism-retaining carrier 100 according to the present embodiment, wastewater treatment can be performed stably at low cost.

(Modification)
As shown in Fig. 6, the microorganism retention carrier 100 may have one end of each of the multiple threads 110 wound around the string 120. In this case, the multiple threads 110 are arranged in the same direction relative to the string 120 in a direction perpendicular to the extension direction of the string 120. Also, the multiple threads 110 wound around the string 120 can be folded and covered with only one covering sheet. This makes it difficult for the multiple threads 110 of the adjacent microorganism retention carriers 100 to become entangled when wastewater treatment is performed using multiple microorganism retention carriers 100. Also, the covering sheet 130 and the multiple threads 110 covered by the covering sheet 130 can be fixed by sewing them together in a straight line at only one place.

The microorganism-holding carrier, wastewater treatment method, and wastewater treatment device of the present invention are useful for treating wastewater such as livestock wastewater and sewage.

Reference Signs List 100 Microorganism retention carrier 110 Thread 120 String 130 Covering sheet 140 Sewing thread 200 Sewage treatment device 210 Sewage treatment tank 220 Oxygen supply device 230 Bracket 240 Sewage 250 Sewage supply device 260 Drain pipe

Claims (8)

With string,
a plurality of yarns each including carbon fiber, a portion of each yarn being wound around the string;
a covering sheet for covering the string and the portions of the plurality of threads wound around the string;
A microorganism-holding carrier comprising: The covering sheet and the plurality of threads are sewn together.
The microorganism-holding carrier according to claim 1 . The microorganism-holding carrier according to claim 1 or 2, wherein the covering sheet is a resin cloth. A step of winding a portion of each of a plurality of yarns including carbon fibers onto a string;
covering the string and portions of the plurality of threads wound around the string with a covering sheet;
fixing the covering sheet to the portions of the yarns covered by the covering sheet;
The method for producing a microorganism-holding carrier comprising the steps of: In the fixing step, the covering sheet and the plurality of threads are sewn together to be fixed.
A method for producing the microorganism-holding carrier according to claim 4. The method for producing a microorganism-retaining carrier according to claim 4 or 5, wherein the covering sheet is a resin cloth. The method includes a step of supplying oxygen to wastewater in a wastewater treatment tank in which the microorganism-holding carrier according to any one of claims 1 to 3 is arranged so as to contact the wastewater.
Wastewater treatment methods. a sewage treatment tank for storing sewage;
an oxygen supplying device that supplies oxygen to the wastewater in the wastewater treatment tank;
The microorganism retention carrier according to any one of claims 1 to 3, which is arranged so as to contact the wastewater in the wastewater treatment tank;
A sewage treatment device comprising:

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