JP7501903B2 - 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 wastewater treatment method that 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 suppressing the release of nitrous oxide from the wastewater and treating the wastewater.

Patent Document 2 discloses a microorganism carrier in which the material that serves as the axis has protrusions 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. Patent Document 2 claims that 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 comprises a thread including carbon fibers, the thread including a main line, a plurality of loops each continuing from the main line, and a plurality of knots each continuing from the main line and the loops and fixing the position of the loops relative to the main line, and a covering sheet that covers the main line and the plurality of knots, and at least a portion of the plurality of loops is exposed to the outside without being covered by the covering sheet.

In addition, a method for manufacturing a microorganism-retaining carrier according to one embodiment of the present invention for solving the above problem includes the steps of tying a thread containing carbon fiber to form a main line, a plurality of loops each continuing from the main line, and a plurality of knots each continuing from the main line and the loops and fixing the position of the loops relative to the main line, covering the main line and the plurality of knots with a covering sheet so that at least a portion of the plurality of loops is not covered, and fixing the covering sheet and the thread 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 above-mentioned microorganism retention 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 an embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of a microorganism-holding carrier according to an embodiment of the present invention. FIG. 3 is a flow chart of a method for producing a microorganism-holding carrier according to an embodiment of the present invention. FIG. 4 is a schematic diagram showing a method for producing a microorganism-holding carrier according to an embodiment of the present invention. FIG. 5 is a schematic diagram showing the configuration of a wastewater treatment device according to an embodiment 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 Figures 1 and 2, the microorganism-holding carrier 100 has a thread 110 containing carbon fibers and a covering sheet 120.

The thread 110 includes carbon fibers and functions as a carrier for attaching microorganisms. The thread 110 has a main line 111, multiple loops 112, and multiple knots 113. The main line 111, the loops 112, and the knots 113 are formed from the same single thread 110. That is, the multiple loops 112 are each continuous with the main line 111, and the multiple knots 113 are each continuous with the main line 111 and the multiple loops 112. For example, the main line 111, multiple loops 112, and multiple knots 113 are formed by repeatedly forming a loop 112 in a single thread 110, tying the base of the loop 112 to make a knot 113, and fixing the position of the loop 112.

The type of thread 110 is not particularly limited as long as it contains carbon fiber and can adhere microorganisms. The thread 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, the thread 110 may be surface-treated.

The shape of the cross section perpendicular to the extension direction of the thread 110 is not particularly limited, and is, for example, approximately circular or approximately rectangular. The thickness of the thread 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 performing sewage treatment 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 trunk 111 is the portion of the thread 110 other than the loops 112 and the knots 113, and functions as an axis for the loops 112 and the knots 113. The length of the trunk 111 is adjusted as appropriate depending on the size of the sewage treatment tank used for sewage treatment, the method of use, etc.

Each of the multiple loops 112 protrudes from a predetermined position of the main line 111 and is a ring-shaped portion that carries microorganisms when performing wastewater treatment. As will be described later, the base of each of the multiple loops 112 (the connection portion with the main line 111) has a knot 113. The circumferential length of the loop 112 is not particularly limited as long as it can adhere microorganisms, but is preferably 60 cm to 90 cm, and more preferably 60 cm to 70 cm. If the circumferential length of the loop 112 is 60 cm or more, it is easy to sufficiently adhere microorganisms to the loop 112. If it is 90 cm or less, it is easy to prevent entanglement with adjacent microorganism retention carriers 100 when performing wastewater treatment using multiple microorganism retention carriers 100. The circumferential lengths of the multiple loops 112 may be equal to each other or different from each other.

In the direction perpendicular to the extension direction of the trunk line 111 (the radial direction of the trunk line 111), the direction in which the multiple loops 112 are arranged relative to the trunk line 111 is not particularly limited. For example, the multiple loops 112 may be arranged in only one direction relative to the trunk line 111, or may be arranged in two directions opposite to each other. In this embodiment, the multiple loops 112 are arranged in the same direction relative to the trunk line 111. By arranging the multiple loops 112 as described above, when performing wastewater treatment using multiple microorganism retention carriers 100, they are less likely to become entangled with adjacent microorganism retention carriers 100. In addition, the multiple loops 112 and the multiple knots 113 can be easily covered with a single cover sheet 120 (described later).

The multiple knots 113 are disposed at the connection between the main line 111 and the multiple loops 112, respectively, and fix the position of each of the multiple loops 112 relative to the main line 111. There is no particular limitation on the method of forming the knots 113 (how to tie the thread 110) as long as the above-mentioned functions are achieved. There is also no particular limitation on the shape and size of the knots 113 as long as the above-mentioned functions are achieved.

The center distance between two adjacent knots 113 is not particularly limited, but is preferably 1 cm or more and 2 cm or less. If the center distance between the two knots is 1 cm or more, the multiple loops 112 are less likely to become entangled in the sewage treatment tank. If the center distance between the two knots is 2 cm or less, the density of the multiple loops 112 to which microorganisms are attached increases, making it easier to improve the efficiency of sewage treatment. Note that, among the multiple knots 113, the center distance between two adjacent knots 113 may be equal to or different from each other.

The covering sheet 120 is a sheet that covers the main line 111 and the multiple knots 113. The type of covering sheet 120 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 120 include cloth, resin film, leather, etc. From the standpoint of durability and cost reduction, it is preferable that the covering sheet 120 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 the loop 112 is exposed to the outside and not covered by the covering sheet 120, and functions as a carrier for microorganisms to adhere to. This allows the microorganisms adhering to the loop 112 to efficiently decompose organic matter in the wastewater. The smaller the proportion of the loop 112 that is covered by the covering sheet 120, the more preferable it is, for example, 50% or less, 25% or less, or 10% or less.

The covering sheet 120 may cover only a portion of the trunk line 111, including the portion where the multiple knots 113 are formed, or may cover the entire trunk line 111. When multiple microorganism retention carriers 100 are connected for use, it is preferable that the covering sheet 120 covers only a portion of the trunk line 111, including the portion where the knots 113 are formed. In this way, the portion of the trunk line 111 that is not covered by the covering sheet 120 can be connected to the trunk line 111 of another microorganism retention carrier 100.

The shape and size of the covering sheet 120 are not particularly limited as long as they can cover the main line 111 and the multiple knots 113. The shape of the covering sheet 120 is, for example, approximately rectangular or approximately circular. In this embodiment, the shape of the covering sheet 120 is rectangular. In addition, the thickness of the covering sheet 120 is not particularly limited, and may be set appropriately depending on the type of covering sheet 120, the required strength, etc.

As shown in Figures 1 and 2, in this embodiment, the thread 110 is covered with one covering sheet 120, but it may be covered with multiple covering sheets 120. For example, the thread 110 may be sandwiched between two covering sheets 120.

The covering sheet 120 and the thread 110 covered by the covering sheet 120 are fixed to each other. Here, "fixing" does not only mean that the thread 110 is fixed so that it cannot move at all relative to the covering sheet 120, but also includes that the thread 110 can move to some extent relative to the covering sheet 120 but is fixed so that the thread 110 does not fall out of the covering sheet 120. The method of fixing the covering sheet 120 and the thread 110 is not particularly limited. For example, the covering sheet 120 and the thread 110 covered by the covering sheet 120 may be fixed by sewing together, the covering sheet 120 and the thread 110 covered by the covering sheet 120 may be fixed by stapler, the covering sheet 120 and the thread 110 may be fixed by adhesive or a combination of these. As shown in Figures 1 and 2, in this embodiment, the covering sheet 120 and the thread 110 covered by the covering sheet 120 (a part of the loop 112) are fixed by sewing together with a sewing thread 130. This prevents the position of the loop 112 from being significantly displaced due to the flow of wastewater during wastewater treatment. In addition, even under conditions where the wastewater flows quickly, the loop 112 can be prevented from falling off the main line 111, so wastewater treatment can be performed stably using the microorganism retention carrier 100. The type of sewing thread 130 is not particularly limited and can 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 the microorganism-holding carrier 100. Figs. 4A to 4C are schematic diagrams showing the method for producing the microorganism-holding carrier 100.

As shown in Figures 3 and 4A-C, the manufacturing method of the microorganism retention carrier 100 according to this embodiment includes: (1) a step of tying a thread 110 containing carbon fiber to form a trunk 111, multiple loops 112, and a knot 113 (step S10, Figure 4A); (2) a step of covering the trunk 111 and multiple knots 113 with a covering sheet 120 (step S20, Figure 4B); and (3) a step of fixing the covering sheet 120 and the thread 110 covered with the covering sheet 120 (step S30, Figure 4C). Each step will be described below.

(1) Step of forming a main line, a loop, and a knot (Step S10)
First, as shown in FIG. 4A, a single thread 110 is knotted to form a main line 111, a plurality of loops 112, and a knot 113.

The method of forming the main line 111, the multiple loops 112, and the knot 113 is not particularly limited. For example, the main line 111 and the loops 112 are formed by forming a loop with the thread 110 and passing the thread 110 through the loop. Furthermore, the thread 110 passed through the loop is tightly knotted with the main line 111 to form the knot 113 at the base of the loop 112 (the connection between the main line 111 and the loop 112). By repeating this process, multiple loops 112 and knots 113 are formed. In this way, the main line 111, the loops 112, and the knots 113 can be formed using only one thread 110 and without cutting the thread 110.

(2) A step of covering the main line and the multiple knots with a covering sheet (step S20)
Next, as shown in FIG. 4B, the trunk line 111 and the multiple knots 113 are covered with a covering sheet 120.

The method of covering the main line 111 and the multiple knots 113 with the covering sheet 120 is not particularly limited. In this embodiment, the main line 111 and the multiple knots 113 are covered with one covering sheet 120 by folding the single covering sheet 120 and sandwiching the main line 111 and the multiple knots 113. In this case, the multiple loops 112 are arranged in the same direction relative to the main line 111 in a direction perpendicular to the extension direction of the main line 111. As described above, the main line 111 and the multiple knots 113 may be sandwiched between two covering sheets 120. In this case, the multiple loops 112 may be arranged in the same direction relative to the main line 111 in a direction perpendicular to the extension direction of the main line 111, or may be arranged in two directions opposite to each other.

(3) Step of fixing the covering sheet and the yarn (step S30)
Finally, as shown in FIG. 4C, the covering sheet 120 and the thread 110 covered with the covering sheet 120 are fixed together.

As described above, the method of fixing the covering sheet 120 and the thread 110 covered by the covering sheet 120 is not particularly limited. In the present embodiment, the covering sheet 120 and the thread 110 covered by the covering sheet 120 are fixed by sewing them together with sewing thread 130. The place where the covering sheet 120 and the thread 110 covered by the covering sheet 120 are sewn together is not particularly limited as long as the thread 110 does not fall off.

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 retention 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 retention carrier 100 is arranged so as to be immersed in the wastewater. By arranging the microorganism retention carrier 100 so as to be in contact with the wastewater, the microorganisms in the wastewater can be attached to the loop 112.

The microorganism-retaining carrier 100 may be used alone, or multiple microorganism-retaining carriers 100 may be connected 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 tank, and the like. By supplying oxygen to the wastewater, the microorganisms attached to the loop 112 can decompose organic matter in the wastewater. When oxygen is supplied to the wastewater, the supplied oxygen may come into direct contact with the microorganism-holding carrier 100.

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 an aeration device and an oxygen cylinder. In this embodiment, the oxygen supplying device 220 is an aeration device.

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

In this embodiment, 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, as shown in FIG. 5.

(effect)
The microorganism-retaining carrier 100 according to the present embodiment uses a single thread to form a plurality of loops 112 that serve as the carrier portion that retains the microorganisms, so that the carrier portion that retains the microorganisms is unlikely to fall off, and the carrier can be easily manufactured at low cost. Therefore, by using the microorganism-retaining carrier 100 according to the present embodiment, wastewater can be treated stably at low cost.

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-holding carrier 110 Thread containing carbon fiber 111 Main line 112 Loop 113 Knot 120 Covering sheet 130 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 (10)

A yarn including carbon fibers, the yarn including a main line, a plurality of loops each continuing to the main line, and a plurality of knots each continuing to the main line and the loops, the knots fixing the positions of the loops relative to the main line;
a covering sheet covering the trunk line and the plurality of knots;
having
At least a portion of the plurality of loops is not covered by the covering sheet and is exposed to the outside.
Microorganism retention carrier. The microorganism retention carrier according to claim 1, wherein the covering sheet and the plurality of loops are sewn together. The microorganism retention carrier according to claim 1 or 2, wherein the multiple loops are arranged in the same direction relative to the trunk line in a direction perpendicular to the extension direction of the trunk line. The microorganism-holding carrier according to claim 1 or claim 2, wherein the covering sheet is a resin cloth. a step of tying a yarn including carbon fiber to form a main line, a plurality of loops each continuing from the main line, and a plurality of knots each continuing from the main line and the loops, each fixing a position of the loop with respect to the main line;
covering the trunk line and the plurality of knots with a covering sheet such that at least a portion of the plurality of loops are not covered;
fixing the covering sheet and the yarn covered with the covering sheet;
The method for producing a microorganism-holding carrier comprising the steps of: The method for manufacturing a microorganism-retaining carrier according to claim 5, wherein the fixing step fixes the covering sheet and the plurality of loops by sewing them together. In the forming step, the plurality of loops are arranged in the same direction with respect to the trunk line in a direction perpendicular to the extension direction of the trunk line.
A method for producing a microorganism-holding carrier according to claim 5 or 6. The method for producing a microorganism-retaining carrier according to any one of claims 5 to 7, wherein the covering sheet is a resin cloth. A wastewater treatment method comprising 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 4 is arranged so as to come into contact with the wastewater. a sewage treatment tank for storing sewage;
an oxygen supplying device for supplying oxygen to the wastewater in the wastewater treatment tank;
The microorganism retention carrier according to any one of claims 1 to 4, which is arranged so as to contact the wastewater in the wastewater treatment tank;
A sewage treatment device comprising:

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