TW202034764A - Aquatic creature cultivation device, purification device, purification method, and molded article - Google Patents

Abstract

The present invention addresses the problem of providing a method for efficiently removing ammonia generated in a device for cultivating aquatic creatures. An aquatic creature cultivation device for cultivating aquatic creatures, the aquatic creature cultivation device comprising a cultivation tank for cultivating the aquatic creatures, and a purification tank for purifying water used in cultivating the aquatic creatures, wherein: the purification tank comprises a molded article having a communicating hole, e.g., a solid mesh-form molded article in which wires comprising a thermoplastic resin are curved and intertwined and in which the wires are fused together at contact parts where the wires are in contact with each other; and the molded article includes a structural unit derived from dicarboxylic acid at a prescribed proportion or greater, and may, for example, be biodegradable.

Description

Aquatic organism breeding device, purification device, purification method and formed body

The invention relates to an aquatic organism cultivation device used for the cultivation of aquatic organisms. In addition, it relates to a purification device and purification method for purifying water used in the cultivation of aquatic organisms, and further relates to a molded body such as a three-dimensional mesh-shaped molded body that can be applied to these devices or methods.

When cultivating fish, etc., in order to prevent the nitrogen component generated from the excrement of the cultivated fish, the remaining bait, etc., from becoming ammonia and causing damage to the cultivated fish, etc., it is necessary to obtain fresh water from the river, etc. , Replace the water in the aquaculture tank etc. in a short time. However, in order to replace the water, a prerequisite is to use a large amount of water. For example, it is difficult to replace a large amount of water when aquaculture is conducted in an inland portion where there is no ocean or river nearby. In addition, the replacement of water means that a large amount of drainage is generated, and in terms of eutrophication of rivers and other aspects, it is not good that all the nitrogen generated in aquaculture flows into the river or the ocean as drainage. In addition, from the viewpoint of environmental protection in recent years, the standards for drainage have become stricter.

To solve this problem, a two-stage reaction using microorganisms is being used to remove ammonia generated from fish and the like from the drainage. That is, a method of using the reaction of converting ammonia into nitric acid and the reaction of decomposing nitric acid into nitrogen. If it is decomposed into nitrogen, it can be discharged into the air without burdening the environment. This reaction using organisms, particularly the reaction of reducing nitric acid to nitrogen (N ₂ ) in the latter stage, is performed using denitrifying bacteria which are facultative anaerobic bacteria.

In the reaction using microorganisms, in the first-stage reaction of converting ammonia to nitric acid, bacteria that naturally live on calcium-based substrates such as shells that are discarded are often used. On the other hand, in the denitrification reaction that converts nitric acid to nitrogen in the second stage, denitrification bacteria that use a polymer such as cellulose as a base material and live there are often used.

The principle of using cellulose as a substrate in the second stage of the reaction has been explained as: "Biodegradable polymers such as natural polymers or biodegradable synthetic resins become substrates for the growth and proliferation of subordinate (organic) vegetative bacteria. Or a hydrogen donor, in the presence of nitrite and nitrate, which are nitrogen oxides, that oxygen in nitrogen oxides is used for respiration and nitrogen oxides are reduced and removed in the presence of very little dissolved oxygen in water. Denitrification bacteria, which are facultative anaerobic microorganisms, implant in groups on biodegradable polymers” (refer to Patent Document 1). In addition, as a substrate that can be used in denitrification reactions other than cellulose, a technique exemplifying a biodegradable resin is disclosed (see Patent Document 2 and Patent Document 3). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 10-85782 [Patent Document 2] Japanese Patent Laid-Open No. 2014-24000 [Patent Document 3] Japanese Patent Laid-Open No. 2010-88307

[The problem to be solved by the invention] In Patent Document 2 and Patent Document 3, a biodegradable resin is used as a substrate for carrying denitrification bacteria, but it has not been studied in an apparatus for cultivating aquatic organisms. It is preferable to use a substrate for carrying denitrification bacteria. What shape is formed. The invention provides a method for efficiently removing the generated ammonia in a device for cultivating aquatic organisms.

[Means to solve the problem] In order to solve the above-mentioned problems, the inventors of the present invention conducted studies and found that by using a molded body having a continuous hole and containing a specific thermoplastic resin, or a three-dimensional mesh-shaped molded body containing wires and having the wires welded to each other The integral structure of the molded body can solve the above-mentioned problems, and the present invention has been completed. The present invention includes the following contents.

(1) An aquatic organism breeding device, including: a breeding tank for breeding aquatic organisms; and a purification tank to purify water used in the breeding of aquatic organisms, wherein, The Johkasou includes a molded body containing a thermoplastic resin and having communicating holes, The molded body contains 50% by mass or more of structural units derived from dicarboxylic acid in all thermoplastic resins constituting the molded body. (2) The aquatic organism cultivation device according to (1), wherein the molded body is a molded body in which the wires are adhered to each other at the contact portion where the wires are in contact with each other. (3) An aquatic organism culturing device for cultivating aquatic organisms, the aquatic organism cultivating device comprising: a breeding tank, cultivating aquatic organisms; and a purification tank, purifying water used in the cultivation of aquatic organisms, wherein, The purification tank includes a three-dimensional mesh-shaped molded body in which a wire material containing a thermoplastic resin is bent and wound, and the wires are welded to each other at a contact portion where the wires contact each other, and the three-dimensional mesh is formed The wire of the shaped molded body contains a biodegradable resin. (4) The aquatic organism cultivation device according to (3), wherein the biodegradable resin is a biodegradable resin containing structural units derived from dicarboxylic acid. (5) The aquatic organism culture device according to any one of (1) to (4), wherein the filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% by volume or more and 30% by volume or less . (6) A purification device for purifying water used in the cultivation of aquatic organisms, the purification device comprising: Oxidize the part to turn ammonia into nitric acid; and denitrify the part to denitrify nitric acid, and The denitrification member is a denitrification bacteria carrier in which denitrification bacteria are supported on a molded body containing a thermoplastic resin and having communicating holes, and the molded body contains 50% by mass or more of the derived material in all the thermoplastic resins constituting the molded body. The structural unit of dicarboxylic acid. (7) The purification device according to (6), wherein the molded body is a molded body in which the wires are adhered to each other at the contact portion where the wires are in contact with each other at the contact portion where the wires are included. (8) A purification device that purifies water used in the cultivation of aquatic organisms, the purification device comprising: Oxidize the part to turn ammonia into nitric acid; and denitrify the part to denitrify nitric acid, and The denitrification member is a denitrification bacteria carrier in which denitrification bacteria are carried on a three-dimensional mesh-shaped molded body. In the three-dimensional mesh-shaped molded body, a wire material containing a thermoplastic resin is bent and wound, and the wires are in contact with each other In the contact portion, the wires are welded to each other, and the wires contain a biodegradable resin. (9) The purification device according to (8), wherein the biodegradable resin is a biodegradable resin containing a structural unit derived from a dicarboxylic acid. (10) The purification device according to any one of (6) to (9), wherein the filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% by volume or more and 30% by volume or less. (11) A purification method for purifying water used in the cultivation of aquatic organisms, the purification method comprising: The step of oxidizing ammonia contained in water to nitric acid, and then reducing the nitric acid to nitrogen by denitrification, The denitrification of the nitric acid is carried out by denitrifying bacteria, which are carried on a molded body containing a thermoplastic resin and having communicating holes, and the molded body contains 50 masses of all thermoplastic resins constituting the molded body. % Or more of structural units derived from dicarboxylic acids. (12) The purification method according to (11), wherein the molded body is a molded body in which the wires are bonded to each other at the contact portion where the wires are in contact with each other. (13) A purification method for purifying water used in the cultivation of aquatic organisms, the purification method comprising: The step of oxidizing ammonia contained in water to nitric acid, and then reducing the nitric acid to nitrogen by denitrification, The denitrification of the nitric acid is carried out by denitrifying bacteria carried on a three-dimensional mesh-shaped molded body in which a wire material containing a thermoplastic resin is bent and wound, and the wires are in contact with each other In the contact portion, the wires are welded to each other, and the wires contain a biodegradable resin. (14) The purification method according to (13), wherein the biodegradable resin is a biodegradable resin containing a structural unit derived from a dicarboxylic acid. (15) The purification method according to any one of (11) to (14), wherein the filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% by volume or more and 30% by volume or less. (16) A molded body containing a thermoplastic resin and having communicating holes, and the molded body contains 50% by mass or more of structural units derived from dicarboxylic acid in all thermoplastic resins constituting the molded body. (17) The molded body according to (16), wherein the molded body is a molded body in which the wires are adhered to each other at a contact portion where the wires are in contact with each other at a contact portion where the wires are included. (18) A molded body which is a three-dimensional mesh-shaped molded body in which a wire material containing a thermoplastic resin is bent and wound, and the wires are welded to each other at a contact portion where the wire materials are in contact with each other, and The wire contains a biodegradable resin. (19) The molded body according to (18), wherein the biodegradable resin is a biodegradable resin containing a structural unit derived from a dicarboxylic acid. (20) The molded body according to any one of (16) to (19), wherein the filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% by volume or more and 30% by volume or less.

Hereinafter, the present invention will be described in detail, but the description of the constituent elements described below is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these contents, and various modifications can be made within the scope of the gist. To implement.

An embodiment of the present invention is an aquatic organism cultivation device for cultivating aquatic organisms, including: a cultivation tank for cultivating aquatic organisms, and a purification tank for purifying water used in the cultivation of aquatic organisms. Furthermore, the sanitation tank includes a three-dimensional mesh-shaped molded body in which a wire material containing a thermoplastic resin is bent and wound, and the wires are welded to each other at a contact portion where the wires are in contact with each other to form the three-dimensional mesh The wire of the shaped molded body contains a biodegradable resin. In addition, in another embodiment of the present invention, the Johkasou includes a molded body containing a thermoplastic resin and having communicating holes, and the molded body contains 50% by mass or more of the two-derived resin in the entire thermoplastic resin constituting the molded body. The structural unit of carboxylic acid. The specific configuration example of the aquatic organism cultivation apparatus is shown in FIG.

FIG. 1 is a schematic diagram showing the structure of an aquatic organism cultivation device 10. The aquatic organism breeding device 10 includes: a breeding tank 11, a pump 12, and a purification tank 13. The purification tank 13 includes a shell 14 as an oxidizing member that oxidizes ammonia contained in water to nitric acid, and a three-dimensional mesh-shaped molded body 15 containing a biodegradable resin that reduces nitric acid to nitrogen by denitrification.

The breeding tank 11 is a tank for breeding aquatic organisms. The size and shape of the breeding tank 11 can be appropriately set according to the type and number of aquatic organisms to be cultivated. As long as it can breed aquatic organisms, it does not need to be a water tank. The aquatic organisms to be cultivated may be organisms that live in water, and typically include freshwater fish such as salmon, trout, ayu, and char, and crustaceans such as crabs and shrimps, but are not limited to these. Typically, fresh water or sea water is used in aquaculture. In the case of using seawater, the salt concentration is not limited.

The oxygen concentration (DO) in the water of the rearing tank 11 is 5 mg/L or more, preferably 6 mg/L or more, more preferably 7 mg/L or more, further preferably 8 mg/L or more, particularly preferably 9 mg /L or more, preferably 10 mg/L or more. If the oxygen concentration (DO) in the water is higher than the lower limit, it becomes an environment suitable for the habitat of aquatic organisms. The concentration of ammonia nitrogen in the water of the rearing tank 11 is 10 mg/L or less, more preferably 8 mg/L or less, still more preferably 6 mg/L or less, particularly preferably 4 mg/L or less. If the ammonia nitrogen concentration is higher than the upper limit, it will have a fatal impact on aquatic organisms. If the ammonia nitrogen concentration is below the upper limit, it becomes an environment suitable for aquatic organisms to inhabit.

The pump 12 is a member that transfers the water in the breeding tank 11 to the purification tank 13. If the water in the breeding tank 11 can be transferred to the purification tank 13, the transfer member is not limited to a pump, and other transfer members may be used instead. The transfer speed of the water transferred by the pump 12 is not particularly limited, but it is difficult to supply oxygen to the bacteria by reducing the transfer speed, so it is preferable to have a certain transfer speed. Once a day can be the degree of water circulation of the rearing tank 11, or the degree of circulating the water of the rearing tank 11 more than twice a day, such as once in 12 hours, once in 10 hours, once in 6 hours, once in 4 hours, and once in 2 hours , 1 hour, 30 minutes, 10 minutes.

The purification tank 13 includes a shell 14 as an oxidizing member that oxidizes ammonia contained in water to nitric acid, and a three-dimensional mesh-shaped molded body 15 of PBSA resin that reduces nitric acid to nitrogen by denitrification. The shell 14 is a base material used to grow bacteria that convert ammonia in the water transferred from the breeding tank 11 into nitric acid. As the bacteria for converting ammonia into nitric acid, known bacteria having this function can be suitably used. Furthermore, the shell 14 is an oxidizing member that oxidizes ammonia contained in water to nitric acid, and as long as it has the same oxidizing function, it can be replaced with another substance. For example, various oxidants can also be added. As a substrate supporting bacteria for converting ammonia into nitric acid, a calcium-based substrate and other substrates containing alkaline earth metals can be used. More specifically, in terms of effective utilization of waste, shells, Coral sand, sea urchin shell, etc. As an oxidizing component that oxidizes ammonia to nitric acid, in addition to shells, pellet type, ring type, sponge type, fiber type, molding type, and mesh type using polyethylene, polypropylene, etc. as the base material can be used. Microbial carrier or nitrification carrier carrier. A so-called immobilized carrier in which microorganisms are pre-encapsulated in a carrier containing polyethylene glycol can also be used. It can be a so-called fluidized bed in which shells or carriers flow in the purification tank, or a so-called fixed bed in which shells or carriers are fixed.

The shells 14 can be directly arranged in the purification tank 13, or arranged after coarse grinding, or arranged after fine grinding. Furthermore, when ammonia is converted into nitric acid, the pH of the water in the purification tank 13 is lowered by the nitric acid. As a substrate used to grow bacteria that convert ammonia into nitric acid, by using a substrate containing alkaline earth metals, pH can be adjusted to promote the growth of nitrifying bacteria.

The three-dimensional mesh-shaped molded body 15 is an example of a molded body having a communication hole, and the communication hole refers to a space in which a fluid can flow in the molded body. Examples of the molded body having communicating holes include a mesh-shaped molded body in which a linear resin is bent and wound, a molded body in which particles are welded to form a space, and a molded body made by weaving a linear resin. Body, molded body using nonwoven fabric, molded body formed by foaming resin, etc. In the communicating hole, it is used to grow nitric acid into nitrogen bacteria. The three-dimensional mesh-shaped molded body 15 which is an example of a molded body having continuous holes is a substrate used to grow bacteria that reduces nitric acid to nitrogen by denitrification, and may include a biodegradable resin. As the bacteria for turning nitric acid into nitrogen, known bacteria having this function can be suitably used. As biodegradable resins, generally known are polylactic acid (PLA) series, polybutylene succinate (PBS) series, polycaprolactone (PCL) series, polyhydroxybutyrate Poly hydroxybutyrate (PHB) resin. In this embodiment, as the biodegradable resin, it is preferable to use a synthetic biodegradable resin containing a structural unit derived from a dicarboxylic acid. The synthetic biodegradable resin may contain structural units derived from diols.

As the kind of biodegradable resin, polyester is preferred. As the type of dicarboxylic acid, succinic acid, adipic acid, oxalic acid, malonic acid, glutaric acid, suberic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, Phthalic acid, etc. Preferably, it is a biodegradable resin containing two or more structural units derived from dicarboxylic acid. Compared with the case of using a biodegradable resin containing a structural unit derived from a dicarboxylic acid, the denitrification rate is faster, and there is a tendency to show high denitrification performance. Among these, it is preferable to contain a structural unit derived from succinic acid, that is, it is preferable to be a PBS-based biodegradable resin having a succinate unit as a main repeating unit. Specific examples of the PBS-based biodegradable resin include polybutylene succinate, poly(butylene succinate/adipate) (PBSA), poly(butylene succinate/adipate), and Diacid/butylene carbonate) and the like are preferred examples. In particular, in terms of high biodegradability, and in terms of slowly supplying the carbon source required for denitrification, poly(butylene succinate/adipate) (PBSA ). Furthermore, PBSA is more easily degraded than other biodegradable resins such as PLA-based resins, so it is better as a substrate or hydrogen donor for the growth and proliferation of denitrifying bacteria.

In the environment in which the aquatic organism cultivation device 10 works, the concentration of nitric acid in the water is low compared with general wastewater treatment, so the organic matter required for denitrification is small, and the elution of excess organic matter will cause a decrease in dissolved oxygen, etc. . Therefore, in the three-dimensional mesh-shaped molded body 15, the proportion of the structural unit derived from the dicarboxylic acid in the total thermoplastic resin constituting the molded body is preferably 50% by mass or more, more preferably 70% by mass or more, and further Preferably it is 80 mass% or more, particularly preferably 90 mass% or more, most preferably 95 mass% or more. In addition, since the structural unit derived from the dicarboxylic acid in the three-dimensional mesh-shaped molded body 15 accounts for a high proportion of all the thermoplastic resins constituting the molded body, the elution of excess organic matter can be suppressed, thereby preventing excessive reduction. Therefore, it can suppress the production of hydrogen sulfide, which may adversely affect the cultivation of aquatic organisms, so it is preferable. In addition, by suppressing the elution of excessive organic matter, the reduction of dissolved oxygen concentration in the fish tank and the proliferation of bacteria can be prevented. Furthermore, the structural units derived from dicarboxylic acid in all the thermoplastic resins constituting the molded body can be measured by a Fourier transform-nuclear magnetic resonance (FT-NMR) device.

The biodegradable resin contained in the three-dimensional mesh-shaped molded body 15 may be mixed with other resins such as polylactic acid, PHB, PHV, and PCL. By mixing a biodegradable resin containing a structural unit derived from a dicarboxylic acid with these resins having different biodegradability, the period during which the three-dimensional mesh-shaped molded body 15 is used as a carbon source can be adjusted. The three-dimensional mesh-shaped molded body 15 may contain components other than resins, such as calcium carbonate and calcium stearate. If these components are 40% by mass or less with respect to the synthetic biodegradable resin, the fine powders due to these components fall off from the molded body, thereby increasing the surface area of the polymer, and denitrification can be efficiently performed.

The three-dimensional mesh-shaped molded body 15 is a three-dimensional mesh-shaped molded body in which a wire rod containing a thermoplastic resin is bent and wound, and the wires are welded to each other at a contact portion where the wire rods contact each other. The method for producing the three-dimensional mesh-shaped molded body used in the present embodiment is not particularly limited, and it may be molded by injection molding or extrusion molding. For example, the following methods can be cited. That is, when molten PBSA or other biodegradable resin (thermoplastic resin) is extruded from the die of an extrusion molding machine in the form of a plurality of wires, bending force acts on the extruded wire to bend into a ring shape. In addition, a plurality of wire rods bent into a loop are entangled with each other and the parts where the wires contact each other are thermally bonded. Therefore, by sandwiching them between a roller and forming a certain thickness while passing through a water tank to cool and solidify, A three-dimensional mesh-shaped molded body in which wires are randomly wound can be obtained three-dimensionally.

In the three-dimensional mesh-shaped molded body 15 in which the wires are welded at the contact portion, even when the biodegradable resin is decomposed, the presence of multiple welded portions in the molded body can suppress the generation of resin chips due to the decomposition of the resin . If the resin is decomposed and resin fragments are generated, there is a risk of aquatic organisms eating the resin fragments by mistake in the aquatic organism cultivation device, but the three-dimensional mesh-shaped molded body of this embodiment can suppress such a risk of ingestion.

The shape of the three-dimensional mesh-shaped molded body 15 is not particularly limited, and may be spherical, cylindrical, plate-shaped (cushion shape), cylindrical, prismatic, or other cylindrical shapes, and may be indefinite. . Furthermore, from the viewpoint of filling efficiency, a shape having a hollow portion like a cylindrical structure is not good.

The thickness of the wire can be adjusted according to the diameter of the hole in the die of the extrusion molding machine through which the molten biodegradable resin is passed. In addition, it can be set according to the number of wires extruded from the die of the extrusion molding machine, or The thickness of the sandwiched roller is set to adjust the filling rate of the three-dimensional mesh-shaped molded body 15. The thickness of the wire rod can be appropriately set according to the filling rate of the desired three-dimensional mesh-shaped molded body, and for example, the diameter can be 0.5 mm or more, 1 mm or more, and 10 mm or less, or 5 mm or less.

In the present embodiment, the filling rate (vol%) of the three-dimensional mesh-shaped molded body 15 represented by its actual volume relative to its apparent volume×100 is usually 7.5% or more, preferably 8% or more, and more preferably 9% or more, more preferably 10% or more, particularly preferably 12.5% or more. In addition, the upper limit is usually 30% or less, preferably 27.5% or less, more preferably 25% or less, and still more preferably 22.5% or less. Alternatively, it can also be expressed by the void ratio (%) obtained by subtracting the filling ratio (%) from 100%. In the case of the porosity, it is usually 92.5% or less, preferably 92% or less, more preferably 91% or less, still more preferably 90% or less, particularly preferably 87.5% or less. In addition, the lower limit is usually 70% or more, preferably 72.5% or more, more preferably 75% or more, and still more preferably 77.5% or more. If the filling rate is equal to or higher than the lower limit, when filling the device with the amount of resin required for denitrification, the filling volume does not increase. As a result, the cost can be reduced by miniaturizing the device. In addition, the volume of the processed resin does not increase, so the operability for replacement and addition is good. If the filling rate exceeds the upper limit value, the water flow resistance becomes high, and there is a possibility of forming a so-called "water channel" that only passes through a part of the flow path. By setting the filling rate below the upper limit, "water channels" can be prevented. In addition, by setting the filling rate to the upper limit or less, clogging caused by hypertrophy of the biofilm can be prevented. The apparent volume is to cut the molded body into a shape whose volume can be obtained, and the volume is regarded as the apparent volume. The actual volume occupied by the resin in the apparent volume is regarded as the actual volume.

In this embodiment, the three-dimensional mesh-shaped molded body 15 is a substrate for growth of bacteria that is used in an aquatic organism cultivation device to reduce nitric acid to nitrogen by denitrification. Therefore, compared with the case of general drainage, the risk of the gap of the molded body being blocked by the solid content is low. Therefore, compared with the case of using a three-dimensional mesh-shaped molded body in general drainage treatment, in the case of using a three-dimensional mesh-shaped molded body in this embodiment, the filling rate can be improved.

Generally speaking, in the Johkasou 11 of the aquatic organism cultivation device 10, unlike the wastewater treatment, it is often required to save space. In the case where the three-dimensional mesh-shaped molded body 15 is in the shape of a plate (mat shape), by layering in the thickness direction, a multilayer three-dimensional mesh-shaped molded body can be made, even if there is insufficient space in the longitudinal direction It can also provide sufficient denitrification capacity.

The amount of the three-dimensional mesh-shaped molded body 15 arranged in the Johkasou 13 varies not only according to the amount of water in the aquatic organism cultivation device 10, but also according to the type, number, growth stage, etc. of the fish being raised, but only according to The amount of water in the aquatic organism cultivation device 10, the concentration of nitrogen accumulated in the water, and the nitrogen removal ability of the three-dimensional mesh-shaped molded body may be appropriately set. As the denitrification reaction progresses, the three-dimensional mesh-shaped molded body 15 is consumed and the weight gradually decreases. The denitrification performance can be maintained by supplementing the reduction when the mass is approximately half. In addition, in the case where the denitrification ability is insufficient even though the quality is not reduced, the denitrification performance can be maintained by adding appropriately.

In the Johkasou 13, the shell 14 as an oxidizing member and the three-dimensional mesh-shaped molded body 15 as a denitrification member may be arranged in the same purification tank 13 as shown in FIG. 1, or may be arranged in different tanks. When arranging the shell 14 and the three-dimensional mesh-shaped molded body 15 as an oxidation member in the same purification tank 13, you may isolate|separate by a fiber separator, filter paper, etc..

Above, the aquatic organism cultivation device 10 in which the shell 14 as an oxidizing member and the three-dimensional mesh-shaped molded body 15 as a denitrification member are arranged in one flow path has been described, but these grooves may also be arranged in independent flow paths. . That is, like the aquatic organism cultivation device 20 shown in FIG. 2, a flow path for nitrification by the shell 24 and a flow path for denitrification by the three-dimensional mesh-shaped molded body 25 may be provided.

FIG. 2 is a schematic diagram showing the structure of the aquatic organism cultivation device 20. The aquatic organism cultivation device 20 includes: a breeding tank 21, a pump 22, and a purification tank 23. The purification tank 23 includes a shell 24 as an oxidizing member that oxidizes ammonia contained in water to nitric acid, and a three-dimensional mesh-shaped molded body 25 of PBSA resin that reduces nitric acid to nitrogen by denitrification. In the aquatic organism cultivation device 20, the shell 24 and the three-dimensional mesh-shaped molded body 25 are arranged in different Johkasou 23. In the case of such a form, you may have a mechanism which can carry out the exchange of water in each tank.

In this embodiment, in order to suppress the generation of hydrogen sulfide, it is preferable to periodically expose the three-dimensional mesh-shaped molded body to the atmosphere to prevent an excessive reduction state. The method for regularly exposing the three-dimensional mesh-shaped molded body to the atmosphere is not particularly limited, and examples thereof include a sprinkling method, a siphon method, and a periodic pumping method. An example of using the siphon method is shown in FIG. 3.

FIG. 3 is a schematic diagram showing the structure of the aquatic organism cultivation device 30. The aquatic organism breeding device 30 includes: a breeding tank 31, a pump 32, and a purification tank 33. The purification tank 33 includes a shell 34 as an oxidizing member that oxidizes ammonia contained in water to nitric acid, and a three-dimensional mesh-shaped molded body 35 of PBSA resin that reduces nitric acid to nitrogen by denitrification. In the aquatic organism cultivation device 30, the shell 34 as an oxidizing member is arranged above and the three-dimensional mesh-shaped molded body 35 is arranged below, but the order may be reversed or may be arranged adjacently.

In FIG. 3, the siphon 36 is a transfer member that can transfer water from the purification tank 33 to the breeding tank 31, and is a mechanism that exposes the three-dimensional mesh-shaped molded body 35 to the atmosphere. The siphon 36 makes the water level of the purification tank 33 higher than the uppermost part of the siphon 36, thereby transferring the water in the purification tank 33 to the breeding tank 31, exposing the three-dimensional mesh-shaped molded body 35 to the atmosphere. By exposing the three-dimensional mesh-shaped molded body 35 to the atmosphere, there is a tendency for the denitrification rate to be fast and to exhibit high denitrification performance.

As a member for transferring water from the purification tank 33 to the breeding tank 31, in addition to using a siphon, a pump may be used to transfer water from the purification tank 33 to the breeding tank 31. In addition, the rearing water may be pumped out (bump-up) from the rearing tank 31, and supplied from the upper part of the purification tank 33 by showering, thereby transferring the water. The three-dimensional mesh-shaped molded body 35 may be brought into contact with the atmosphere by supplying air or oxygen to the water in the purification tank 33.

The aquatic organism cultivation device 10, the aquatic organism cultivation device 20, the aquatic organism cultivation device 30, etc. may also be equipped with other foam separation devices, but they are not necessary in this embodiment. By having a foam separation device, chemical oxygen demand (COD) can be reduced, but in this embodiment, even if a foam separation device is not provided, COD can be reduced. [Example]

Hereinafter, the present invention will be explained in more detail with examples, but the scope of the present invention is of course not limited to the aspects shown in the following examples.

<Example 1> First, a three-dimensional mesh-shaped molded body was prepared. A schematic diagram of the prepared three-dimensional mesh-shaped molded body is shown in FIG. 4. The three-dimensional mesh-shaped molded body is processed into a width of 50 cm × a depth of 50 cm × a thickness of 1.8 cm using PBSA (manufactured by Mitsubishi Chemical, with a structural unit derived from dicarboxylic acid of 50% by mass or more) using an extruder. At this time, the diameter of the wire rod was 1.1 mm, the weight of the three-dimensional mesh-shaped molded body was 0.7 kg, and the specific gravity of PBSA was 1.24 g/cm ³ . The surface area per unit apparent volume (50 cm (width) × 50 cm (depth) × 1.8 cm (thickness)) of the formed body is 0.45 m ² /L, the surface area per unit weight is 2.9 m ² /kg, and the clearance ratio is 87.5% (filling rate 12.5%). In addition, the gap ratio represents the ratio of the void volume to the apparent volume, and the filling ratio represents the ratio of the actual volume to the apparent volume.

Next, the experimental device schematically shown in FIG. 5 was prepared. The experimental device 50 shown in FIG. 5 has a structure in which a water tank 51 filled with simulated drainage and a pipe string 53 are connected by a pipe pump 52. A resin column 53 with an inner diameter of 20 mm was filled with 17.2 g of a three-dimensional mesh-shaped molded body 55 made of PBSA. The total surface area of the molded body at this time was 0.05 m ² .

A tube pump 52 is used to pass simulated drainage from the bottom of the tube string 53 at a flow rate of 6.5 mL/min, so that the overflow water from the upper part of the tube string 53 is returned to the water tank 51. The composition of the simulated drainage is shown in Table 1. In addition, the temperature of the simulated drainage was set to room temperature (23°C).

[Table 1] Table 1 Composition of simulated drainage Compound name Compound concentration Element concentration K ₂ HPO ₄ 30 mg/L 5.3 mgP/L MgSO ₄ ·7H ₂ O 90 mg/L 8.8 mgMg/L Trace elements 0.3 mL/L Nitrate NaNO ₃ Na 600 mg/L 98.8 mgN/L *Trace elements (g/L): EDTA·2Na: 57.1, ZnSO ₄ ·7H ₂ O: 3.9, CaCl ₂ ·2H ₂ O: 7.0, MnCl ₂ ·4H ₂ O: 5.1, FeSO ₄ ·7H ₂ O: 5.0 , (NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O: 1.1, CuSO ₄ ·5H ₂ O: 1.6, CoCl ₂ ·6H ₂ O: 1.6

For domestication, after 15 days of water supply, samples were taken from the container to simulate drainage for water quality analysis. Regarding water quality, the total organic carbon (TOC), total nitrogen (TN) and dissolved oxygen concentration (DO) are measured. Furthermore, since the simulated wastewater contains only nitrate nitrogen as a nitrogen source, the total nitrogen concentration can be regarded as the nitrate nitrogen concentration. The result of water quality measurement is that as TOC increases, dissolved oxygen and TN decrease. This means that the microorganisms attached to the PBSA molded body decompose PBSA into monomers/oligomers, and the TOC rises and the dissolved oxygen is consumed by the TOC. While the dissolved oxygen is reduced, the nitrate nitrogen in the simulated drainage is reduced to nitrogen by the denitrifying bacteria attached to the PBSA molded body, so TN is reduced.

Based on the TN reduction rate (denitrification rate) and the amount of PBSA molded body used for the test, the denitrification rate per unit mass is calculated and it is 4.80 gN/kg/day. In addition, the denitrification rate per unit surface area was 1.65 gN/m ² /day. In addition, during the test, the PBSA molded body was colored light yellow, and PBSA decomposing bacteria and denitrifying bacteria were attached. Although slight detachment of these bacteria was also seen, it did not cause the clogging of the PBSA molded body. The measurement results are shown in FIG. 6.

<Comparative Example 1> Except that PBSA resin pellets having no communicating holes were used instead of the three-dimensional mesh-shaped molded body, a test under the same conditions as in Example 1 was performed. A resin column with an inner diameter of 20 mm was filled with 20 g of PBSA pellets. At this time, the total surface area of the particles is 0.05 m ² . The shape of PBSA resin particles is a thin elliptical disk with a long diameter of 5 mm, a short diameter of 3 mm, and a thickness of 1.2 mm. The surface area per unit apparent volume of the resin particles is 2.1 m ² /L, and the surface area per unit weight is 2.7 m ² / kg, the clearance rate is 34% (filling rate 66%).

The same test as in Example 1 was performed, and as a result, it was also confirmed that as TOC increased, DO and TN decreased. Based on the TN reduction rate (denitrification rate) and the amount of PBSA particles used in the test, the denitrification rate per unit mass is calculated, which is 1.55 gN/kg/day. In addition, the denitrification rate per unit surface area is 0.59 gN/m ² /day. In addition, it was also confirmed that the microorganisms attached to the PBSA particles were enlarged and blocked a part of the gaps between the particles.

Table 2 shows the results of Examples and Comparative Examples. Compared with pellets, the denitrification rate per unit mass and the denitrification rate per unit surface area of the mesh-shaped formed body are both higher values. It is generally believed that in the method of processing by attaching microorganisms to the surface of the carrier to form a so-called biofilm as in this method, the surface area of the biofilm is proportional to the processing capacity. Therefore, it is considered that if the raw materials and drainage conditions are the same, the denitrification rate per unit surface area will be the same value. In the Examples and Comparative Examples this time, the denitrification rate per unit surface area is the same in the case of the mesh-shaped formed body. Is a high value. It is considered that one of the reasons for this is that the enlarged microbes in the particles block part of the interstitial space of the particles, and the entire surface of the particles is not effectively used.

[Table 2] Table 2 shape Fill rate (%) Denitrification rate per unit mass gN/kg/day Denitrification rate per unit surface area gN/m ² /day Example 1 Mesh shaped body 12.5 4.80 1.65 Comparative example 1 Particles 66 1.55 0.59

Furthermore, the present invention will be described in detail with reference to specific embodiments, but it is obvious to those having ordinary knowledge in the technical field that various changes can be implemented without departing from the spirit and scope of the present invention. change.

10, 20, 30: Aquatic organism breeding device 11, 21, 31: Feeding trough 12, 22, 32, 52: pump 13, 23, 33: Johkasou 14, 24, 34: Shell 15, 25, 35: three-dimensional mesh shaped body 50: Experimental device 51: sink 52: Tube pump 53: pipe string 55: PBSA resin three-dimensional mesh shaped body

Fig. 1 is a schematic diagram showing one form of an aquatic organism cultivation device. Fig. 2 is a schematic diagram showing another form of the aquatic organism cultivation device. Fig. 3 is a schematic diagram showing another form of the aquatic organism cultivation device. 4 is a schematic diagram of a three-dimensional mesh-shaped molded body used in Example 1. FIG. FIG. 5 is a schematic diagram of the experimental device used in Example 1. FIG. 6 is a graph showing the results of water quality measurement in Example 1. FIG.

10: Aquatic organism breeding device

11: Feeding trough

12: Pump

13: Johkasou

14: Shell

15: Three-dimensional mesh shaped body

Claims (20)

An aquatic organism breeding device, comprising: a breeding tank for breeding aquatic organisms; and a purification tank for purifying water used in the breeding of aquatic organisms, wherein, The Johkasou includes a molded body containing a thermoplastic resin and having communicating holes, The molded body contains 50% by mass or more of structural units derived from dicarboxylic acid in all thermoplastic resins constituting the molded body. The aquatic organism cultivation device according to claim 1, wherein the molded body is a molded body in which the wires are adhered to each other at a contact portion where the wires are in contact with each other. An aquatic organism breeding device, which is used for breeding aquatic organisms. The aquatic organism breeding device includes: a breeding tank for breeding aquatic organisms; and a purification tank for purifying water used in the breeding of aquatic organisms, wherein, The purification tank includes a three-dimensional mesh-shaped molded body in which a wire material containing a thermoplastic resin is bent and wound, and the wire materials are welded to each other at a contact portion where the wire materials are in contact with each other to form the The wire of the three-dimensional mesh-shaped molded body contains a biodegradable resin. The aquatic organism cultivation device according to claim 3, wherein the biodegradable resin is a biodegradable resin containing a structural unit derived from a dicarboxylic acid. The aquatic organism culture device according to any one of claim 1 to claim 4, wherein the filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% or more and 30% or less. A purification device for purifying water used in the cultivation of aquatic organisms, the purification device comprising: Oxidize the part to turn ammonia into nitric acid; and denitrify the part to denitrify nitric acid, and The denitrification member is a denitrification bacteria carrier in which denitrification bacteria are carried on a molded body containing a thermoplastic resin and having communicating holes, and the molded body contains 50% by mass or more of all thermoplastic resins constituting the molded body Structural units derived from dicarboxylic acids. The purification device according to claim 6, wherein the molded body is a molded body in which the wires are adhered to each other at a contact portion where the wires are in contact with each other. A purification device for purifying water used in the cultivation of aquatic organisms, the purification device comprising: Oxidize the part to turn ammonia into nitric acid; and denitrify the part to denitrify nitric acid, and The denitrification member is a denitrification bacteria carrier in which denitrification bacteria are carried on a three-dimensional mesh-shaped molded body. In the three-dimensional mesh-shaped molded body, a wire material containing a thermoplastic resin is bent and wound, and the wires are in contact with each other The wires are welded to each other, and the wires contain biodegradable resin. The purification device according to claim 8, wherein the biodegradable resin is a biodegradable resin containing a structural unit derived from a dicarboxylic acid. The purification device according to any one of claims 6 to 9, wherein the filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% by volume or more and 30% by volume or less. A purification method for purifying water used in the cultivation of aquatic organisms, the purification method comprising: The step of oxidizing ammonia contained in water to nitric acid, and then reducing the nitric acid to nitrogen by denitrification, The denitrification of the nitric acid is carried out by a denitrifying bacteria carried on a molded body containing a thermoplastic resin and having communicating holes, and the molded body contains all the thermoplastic resins constituting the molded body 50% by mass or more of structural units derived from dicarboxylic acid. The purification method according to claim 11, wherein the molded body is a molded body in which the wires are adhered to each other at a contact portion where the wires are in contact with each other. A purification method for purifying water used in the cultivation of aquatic organisms, the purification method comprising: The step of oxidizing ammonia contained in water to nitric acid, and then reducing the nitric acid to nitrogen by denitrification, The denitrification of the nitric acid is carried out by denitrifying bacteria carried on a three-dimensional mesh-shaped molded body in which a wire material containing a thermoplastic resin is bent and wound, and the wires are in contact with each other The wires are welded to each other, and the wires contain biodegradable resin. The purification method according to claim 13, wherein the biodegradable resin is a biodegradable resin containing a structural unit derived from a dicarboxylic acid. The purification method according to any one of claims 11 to 14, wherein the filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% by volume or more and 30% by volume or less. A molded body containing a thermoplastic resin and having continuous holes, and the molded body contains 50% by mass or more of structural units derived from dicarboxylic acid in all thermoplastic resins constituting the molded body. The molded body according to claim 16, wherein the molded body is a molded body in which the wires are bonded to each other at a contact portion where the wires are in contact with each other. A molded body is a three-dimensional mesh-shaped molded body in which a wire material containing a thermoplastic resin is bent and wound, and the wires are welded to each other at a contact portion where the wire materials contact each other, and the The wire contains a biodegradable resin. The molded body according to claim 18, wherein the biodegradable resin is a biodegradable resin containing a structural unit derived from a dicarboxylic acid. The molded body according to any one of claims 16 to 19, wherein a filling rate of the molded body or the three-dimensional mesh-shaped molded body is 7.5% by volume or more and 30% by volume or less.

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