JP5492621B2 - Nitrification tank, wastewater treatment system - Google Patents

Description

  The present invention relates to a nitrification tank and a wastewater treatment system.

  For example, ammonia is generated in the aquarium where fish and shellfish are bred due to food, waste, etc. left over by seafood. This ammonia is harmful to fish and shellfish, and if it accumulates in the aquarium, it may hinder the growth of fish and shellfish. Therefore, there is known a nitrification tank in which ammonia contained in water in the water tank is nitrified by nitrifying bacteria to make nitric acid relatively harmless to fish and shellfish (see, for example, Patent Document 1). This nitrification tank is provided with a filter medium such as oyster shell or plastic with nitrifying bacteria attached to its surface, for example. Then, the water supplied from the water tank passes through the nitrification tank while contacting the surface of the filter medium, so that ammonia in the water is nitrified.

JP-A-5-76257

  However, in the nitrification tank described above, there is a possibility that the filter medium moves due to the flow of water supplied from the water tank, and the density of the filter medium in the nitrification tank is biased. If the density of the filter medium in the nitrification tank is biased, for example, the flow of water will stagnate in places where the density is high, and water will pass through the nitrification tank without efficiently contacting the surface of the filter medium in places where the density is low. There is a fear. For this reason, there is a possibility that ammonia cannot be efficiently nitrified.

  This invention is made | formed in view of this subject, The place made into the objective is to provide the nitrification tank and waste water treatment system which can nitrify ammonia efficiently.

The invention for solving the above problems includes a supply port to which water from a water tank in which seafood is bred is supplied, a first perforated pipe for discharging the water supplied to the supply port, and the water nitrifying bacteria you nitrification of ammonia contained has a plurality of hollow filter medium inner surface the deposited tubular hollow, outer surfaces on each of said plurality of hollow filter medium are arranged adjacently without any people gaps husband a first filter which is fixedly arranged nitrification tank, a pre Ki硝 bacterium adheres, the water discharged from said first perforated tube from the upper side to the lower side of each of the plurality of hollow filter medium A second filter that proliferates the nitrifying bacteria attached to the inner surfaces of the plurality of hollow filter media by supplying substantially evenly and moving the nitrifying bacteria onto the inner surfaces of the plurality of hollow filter media ; , suspended contained in the water discharged from said first perforated tube It exhibits a sheet form having a mesh size to remove the object, and a third filter that supplies the water to remove the suspension in the second filter, to the upper from the lower side of the plurality of hollow filter medium It is a nitrification tank provided with the 2nd perforated pipe which supplies oxygen, and the discharge port which discharges the water obtained from the lower side of the 1st filter.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  ADVANTAGE OF THE INVENTION According to this invention, the nitrification tank and waste water treatment system which can nitrify ammonia efficiently can be provided.

It is a mimetic diagram showing composition of an aquaculture system provided with a wastewater treatment system concerning this embodiment. It is a top view of the nitrification tank concerning this embodiment. It is a schematic diagram of a mesh-like filter medium. It is a perspective view of a honeycomb filter medium. It is a figure which shows the relationship between the feed amount at the time of cultivating a trough puffer in the aquaculture system shown in FIG. 1, and the ammonia nitrogen concentration in a water tank.

  At least the following matters will become apparent from the description of the present specification and the accompanying drawings.

<<< About aquaculture system >>>
The wastewater treatment system according to the present embodiment is provided in an aquaculture system for culturing fish and shellfish such as trough puffers. First, the aquaculture system 1 including the wastewater treatment system 10 according to the present embodiment will be described with reference to FIG.

  The aquaculture system 1 includes a water tank 2, a wastewater treatment system 10, a pump 7, and a chiller / heater 8. In the aquarium 2, for example, trough puffer is reared. Along with this, the water in the aquarium 2 contains solid matter such as food left over by the troughfish (residual food) and discharged matter, and ammonia (ammonia nitrogen) resulting from this remaining food and discharged material. Is contained.

  The waste water treatment system 10 is supplied with water from the water tank 2 and removes solids and ammonia contained in the water. The details of the wastewater treatment system 10 will be described later.

  The pump 7 circulates water between the water tank 2 and the waste water treatment system 10. That is, water containing solids and ammonia is supplied from the water tank 2 to the wastewater treatment system 10, and the water from which the solids and ammonia have been removed by the wastewater treatment system 10 is returned to the water tank 2.

  The chiller / heater 8 includes a heat pump or the like, and adjusts the water temperature in the aquarium 2 so as to be a temperature suitable for trough breeding.

<<< About wastewater treatment system >>>
Hereinafter, the waste water treatment system 10 will be specifically described. The waste water treatment system 10 includes a sedimentation tank 3, a drum filter 4 (filter device), an aeration tank 5, and a nitrification tank 6.

  The settling tank 3 is supplied with water from the water tank 2, and removes precipitates made up of residual food, feces aggregates, and the like from the solid content contained in the water. For example, the sedimentation tank 3 has a treated water tank (not shown) having a hollow cylindrical shape having a bottom surface and an upper surface. A through hole penetrating between the inner peripheral surface and the outer peripheral surface is provided on the bottom surface side of the treated water tank, and water is supplied from the through hole so as to rotate along the inner peripheral surface. As a result, a swirl flow is generated inside the treated water tank, and a precipitate having a specific gravity larger than that of water is efficiently settled. The settled sediment is collected on the bottom side of the treated water tank. Moreover, the water separated from the precipitate is discharged from a through-hole penetrating between the inner peripheral surface and the outer peripheral surface provided on the upper surface side of the treated water tank.

  The drum filter 4 is supplied with water from which the sediment has been removed by passing through the sedimentation tank 3, and removes, for example, solids smaller than the precipitate and larger than about 90 μm from the solid content contained in the water. . For example, the drum filter 4 includes a filter made of metal or the like and having a hollow cylindrical shape. A mesh having a size of about 90 μm is formed on the peripheral surface of the filter. The filter is supported in the casing so that the axis passing through the center of the hollow circle faces the horizontal direction and is rotatable about the axis. And by supplying the water from the sedimentation tank 3 to the inside of the filter rotating by the driving force of the motor or the like, the solid matter remains inside the filter, and the water from which the solid matter is removed outside the filter. Discharged.

  In addition, the drum filter 4 temporarily stops the supply of water from the settling tank 3 when the mesh is blocked by the solid matter remaining in the filter and the water level in the filter becomes a certain level or more, for example, Wash water is jetted from the outside to the inside of the filter. That is, it has a so-called backwash function. As a result, clogging of the filter is automatically eliminated, and solids in the water can be efficiently removed.

  The aeration tank 5 supplies air to the water after passing through the drum filter 4. For example, the aeration tank 5 stores water from the drum filter 4 and sends air to the water by a blower (not shown). Thereby, the amount of dissolved oxygen in the water can be increased.

  The nitrification tank 6 nitrifies ammonia contained in the water supplied with air in the aeration tank 5 by nitrifying bacteria.

<<< About nitrification tank >>>
Hereinafter, the nitrification tank 6 will be specifically described with reference to FIGS. 1 and 4. The nitrification tank 6 includes a supply port 60, a first porous tube 61, a sheet-like filter 62 (third filter), a plastic filter medium 63 (second filter), and a honeycomb filter medium 64 (first filter). A second perforated pipe 65, a discharge port 66, a nitrification tank body 67, a block 68, and a grating 69.

  As shown in FIGS. 1 and 2, the nitrification tank body 67 is made of, for example, fiber reinforced plastic (FRP) and has a box shape with an open top. Of the pair of side walls forming the width direction of the nitrification tank body 67, the supply port 60 is provided above one side wall, and the discharge port 66 is provided below the other side wall. In addition, a first porous tube 61, a sheet filter 62, a plastic filter material 63, a honeycomb filter material 64, a grating 69, a second porous tube 65, and a block 68 are accommodated in the inside of the nitrification tank body 67 in order from the upper side. Yes. A management space 67 a is formed between these components housed inside the nitrification tank body 67 and the side wall provided with the discharge port 66 of the nitrification tank body 67. The aeration tank 5 is adjacent to the side wall of the nitrification tank body 67 where the supply port 60 is provided.

  The supply port 60 is, for example, a through-hole that communicates the aeration tank 5 and the nitrification tank body 67 in order to supply water from the aeration tank 5 to the first porous tube 61, and one end side of the first porous tube 61 is inserted therethrough. Has been. For example, as shown in FIG. 2, three supply ports 60 are provided at substantially equal intervals in the width direction of the nitrification tank body 67.

  The first porous tube 61 is made of, for example, metal or resin, and has a tubular shape in which a plurality of rows of perforations 61a are provided along the longitudinal direction on the peripheral surface. For example, as shown in FIG. 2, the first porous tube 61 includes three pipes extending from the supply port 60 in the length direction of the nitrification tank body 67, and water from the aeration tank 5 passes through the supply port 60. Distributed through. The first porous tube 61 supplies water to the entire nitrification tank body 67 by discharging the water supplied from the supply port 60 while dispersing the water through the plurality of perforations 61a.

  The sheet-like filter 62 removes a suspension, for example, smaller than about 90 μm and larger than about 10 μm contained in the water discharged from the first porous tube 61. For example, the sheet-like filter 62 is made of a fibrous resin or the like and has a sheet shape having a mesh size of about 10 μm. The entire upper side of the plastic filter medium 63 is covered below the first porous tube 61 so as to spread in the horizontal direction of the nitrification tank body 67.

  The plastic filter medium 63 has a rectangular parallelepiped shape in which, for example, a plurality of approximately 6 cm square mesh filter media 63a (see FIG. 3) made of resin are stacked and integrated. Further, nitrifying bacteria that nitrify ammonia are attached to the surface of the plastic filter medium 63. Since nitrifying bacteria have the property of adhering to a solid carrier, for example, immersing the plastic filter medium 63 in a water tank in which nitrifying bacteria are present allows the nitrifying bacteria to adhere to the surface of the plastic filter medium 63.

  A plurality of plastic filter media 63 are arranged below the sheet filter 62 and over the entire upper side of the honeycomb filter media 64. For this reason, the water that has passed through the sheet filter 62 flows toward the honeycomb filter medium 64 while being transmitted to the adjacent plastic filter medium 63 in contact with the surface of the plastic filter medium 63. That is, the water that has passed through the plastic filter medium 63 is dispersed and discharged in the horizontal direction of the nitrification tank body 67. For this reason, the plastic filter medium 63 nitrifies the water from the sheet filter 62 and supplies it to the honeycomb filter medium 64 so as to be substantially uniform.

  In the top view of the nitrification tank 6 shown in FIG. 2, the sheet-like filter 62 and the plastic filter medium 63 are omitted for convenience of explanation.

  As shown in FIG. 4, the honeycomb filter medium 64 includes a plurality of hollow filter media 64 a made of, for example, a resin and having a hollow hexagonal column shape. Each of the plurality of hollow filter media 64a is fixedly arranged in the nitrification tank main body 67 in such a state that the openings at both ends face the upper side and the lower side and the outer surfaces are adjacent to each other without a gap.

  For example, the distance (the length indicated by the arrow A in FIG. 2, the cell size) between the apexes facing each other across the hollow of the hexagonal opening of each hollow filter medium 64a is about 13 mm. Further, the honeycomb filter medium 64 has a shape in which a plurality of hollow filter media 64a are integrally formed so as to share the outer surface. The honeycomb filter medium 64 has elasticity against forces applied from both ends in the width direction and has a specific gravity greater than that of water. For this reason, for example, first, the honeycomb filter medium 64 in a contracted state by applying a force against the elastic force is installed in the nitrification tank body 67 without a gap. Then, by releasing the force that resists the elastic force, the outer surface of the honeycomb filter medium 64 comes into contact with the inner wall of the nitrification tank body 67 so as to be pressed. Thereby, the honeycomb filter medium 64 is fixedly arranged so as not to move by a water flow or the like with respect to the nitrification tank body 67.

  However, the present invention is not limited to this, and the plurality of hollow filter media 64a may be fixedly arranged in the nitrification tank main body 67 with an adhesive or the like, for example.

  Further, nitrifying bacteria are attached to the inner surface of each of the plurality of hollow filter media 64a. For example, when water is supplied from the plastic filter medium 63 to which the nitrifying bacteria are attached to the hollow filter medium 64a, the nitrifying bacteria move from the plastic filter medium 63 onto the inner surface of the hollow filter medium 64a and proliferate. Thereby, nitrifying bacteria adhere to the inner surface of each of the plurality of hollow filter media 64a.

  Since water is supplied to the honeycomb filter medium 64 substantially uniformly from the plastic filter medium 63, the water flows from the upper side to the lower side while contacting the inner surfaces of the plurality of hollow filter media 64a. Thereby, ammonia in water is efficiently nitrified. That is, since the water from the plastic filter medium 63 passes through the honeycomb filter medium 64 and ammonia is oxidized to nitric acid (nitrate nitrogen), the water from which ammonia harmful to the trough is removed from below the honeycomb filter medium 64. can get.

  In the present embodiment, the diameter of the honeycomb filter medium 64 is described as being, for example, 13 mm. However, for convenience of explanation, FIG.

  The second porous tube 65 is made of, for example, metal, resin, or the like, and has a tube shape in which a plurality of perforations 65a are provided on the peripheral surface along the longitudinal direction. For example, the second porous pipe 65 is composed of three pipes extending in the length direction of the nitrification tank main body 67 below the honeycomb filter medium 64 in the nitrification tank main body 67, and mutually in the width direction of the nitrification tank main body 67. It arrange | positions so that it may become substantially equal intervals. The second porous tube 65 discharges air from the perforations 65a by supplying air from one end side by a blower (not shown) or the like, and supplies oxygen from the lower side to the upper side of the hollow filter medium 64a.

  Thereby, it is possible to suppress the flow of water from the upper side to the lower side of the hollow filter medium 64a and to generate the flow of water from the lower side to the upper side. For this reason, ammonia can be efficiently nitrified by increasing the contact time and the contact opportunity between the inner surface of the hollow filter medium 64a and water. Further, the amount of dissolved oxygen in the water in the nitrification tank body 67 can be increased, and the nitrifying bacteria can be kept aerobically, so that ammonia can be efficiently nitrified.

  The supply of air from the second porous tube 65 may be performed continuously or intermittently. Further, the second porous tube 65 may supply air only to the specific hollow filter medium 64a.

  The block 68 has a rectangular parallelepiped shape made of a material having a specific gravity greater than that of water such as resin or concrete, and is disposed on the bottom surface in the nitrification tank body 67. The grating 69 has a lattice shape made of a material having a specific gravity greater than that of water, such as resin, and is disposed on the block 68. A honeycomb filter medium 64 is disposed on the grating 69. That is, the honeycomb filter medium 64 is fixedly disposed on the second porous tube 65 by the block 68 and the grating 69, and the air discharged from the second porous tube 65 passes between the lattices of the grating 69 and the honeycomb filter medium. 64.

  The discharge port 66 is a through-hole penetrating between the inner side surface and the outer side surface of the nitrification tank main body 67, and water obtained from the lower side of the honeycomb filter medium 64 is discharged from the nitrification tank main body 67 through the discharge port 66. To do. The water discharged from the discharge port 66 is supplied to the pump 7.

  The management space 67 a is provided to manage the discharge port 66 that is the suction port of the pump 7. For example, when the discharge port 66 is clogged with foreign matter, the discharge port 66 can be cleaned through the management space 67a with a cleaning tool (not shown).

<<< About aquaculture test result in aquaculture system >>>
In the aquaculture system 1 including the wastewater treatment system 10 according to the present embodiment, a trough puffer aquaculture test was conducted for about one year and three months from the fry stage to the adult stage, and the amount of trough puffer fed and ammonia nitrogen in the tank 2 The relationship with concentration was examined. The results of this aquaculture test will be described with reference to FIG.

Incidentally, the amount of water is stored in each component of the aquaculture system 1, water tub 2, 26.8M ^3, aeration tank 5 and nitrification tank 6 in 7.5 m ^3, the settling tank 3 at 0.3 m ^3, connecting each configuration The total amount of water including the pipe portion was 35 m ³ . In the aquaculture system 1, water having a flow rate of 243 l / min was circulated by the pump 7, and the number of trough puffers bred in the water tank 2 was 1029.

  As a result, as shown in FIG. 5, in the aquaculture system 1, the amount of waste and the like increases because the amount of feeding increases each time a trough grows, but the increase in ammonia nitrogen concentration accompanying this increase in the amount of feeding is Not always below 1 mg / L. Therefore, it was found that ammonia was efficiently nitrified by the wastewater treatment system 10, and the water in the water tank 2 was maintained at an ammonia nitrogen concentration suitable for the growth of trough fish.

  As described above, in the nitrification tank 6 according to the present embodiment, the water containing ammonia from the water tank 2 is supplied to the first porous tube 61 through the supply port 60. Then, water discharged from the perforations 61 a of the first porous tube 61 is supplied to the plastic filter medium 63 through the sheet filter 62, and water that has passed through the plastic filter medium 63 is supplied to the honeycomb filter medium 64.

  In the first porous tube 61, water can be dispersed by the perforations 61 a and supplied to the sheet filter 62. For this reason, the suspension in water can be efficiently captured using the mesh of the entire sheet-like filter 62. Then, the water from which the suspended matter is removed by the sheet filter 62 can be supplied to the entirety of the plurality of plastic filter media 63. Thus, the mesh of the plastic filter medium 63 can be prevented from being blocked by the suspension, and the water can be efficiently contacted with the surface of the plastic filter medium 63, so that ammonia can be efficiently nitrified.

  Further, the water dispersed by passing through the plastic filter medium 63 is supplied to the honeycomb filter medium 64, so that the water is supplied approximately evenly to each of the plurality of hollow filter media 64a. Furthermore, since the hollow filter medium 64a is fixedly arranged in the nitrification tank main body 67, it is possible to prevent the density from being biased in the nitrification tank main body 67 due to a water flow or the like. Therefore, since water contacts the inner surface of each of the plurality of hollow filter media 64a efficiently, ammonia can be efficiently nitrified.

  Moreover, in the waste water treatment system 10 concerning this embodiment, it decided to purify the water from the water tank 2 which breeds a trough puffer. Since the trough feces are smaller than other fish and shellfish, the feces suspended in water can be efficiently removed by setting the mesh size of the sheet filter 62 to about 10 μm. Accordingly, clogging of the plastic filter medium 63 can be prevented, and ammonia in water can be efficiently nitrified. Further, the water after the solid matter of about 90 μm or more formed by collecting trough poops and the like is removed by the drum filter 4 is supplied to the sheet filter 62. As a result, clogging of the sheet-like filter 62 and the like can be effectively prevented, and the solid content in the water can be efficiently removed. Further, the backwash function of the drum filter 4 works effectively by setting the mesh size of the filter of the drum filter 4 to about 90 μm according to the size of the solid matter according to the size of the trough puffer droppings. Thus, the solid content in the water can be efficiently removed.

  Moreover, in the aquaculture system 1 provided with the wastewater treatment system 10 according to the present embodiment, water is circulated between the water tank 2 and the wastewater treatment system 10. In other words, a so-called circulation filtration method is employed in which water for rearing trough puffer in the water tank 2 is repeatedly used while being purified by the wastewater treatment system 10. Accordingly, the water temperature in the water tank 2 can be easily adjusted by the water cooler / heater 8 or the like, and the water mixed with pathogenic bacteria can be prevented from being supplied from the outside, so that the trough can be efficiently grown. . Moreover, the waste water generated by the farming of trough puffer can be reduced, and the environmental load can be reduced.

<<< About other embodiments >>>
The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention is changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  The honeycomb filter medium 64 of the nitrification tank 6 according to the present embodiment is formed such that a plurality of hollow filter media 64a having a hollow hexagonal column shape are formed adjacent to each other without a gap, but the present invention is not particularly limited thereto. For example, the honeycomb filter medium 64 may be formed by adjoining a plurality of hollow filter media having a cylindrical shape such as a hollow quadrangular prism shape or a triangular prism shape without a gap.

  Further, in the nitrification tank 6 according to the present embodiment, the plastic filter medium 63 is formed by stacking a plurality of about 6 cm square mesh filter media 63a. However, the present invention is not particularly limited to this. Oyster shells with nitrifying bacteria attached to them may be used.

  In the nitrification tank 6 according to the present embodiment, the sheet-like filter 62 is provided, but the invention is not particularly limited thereto. For example, the nitrification tank 6 may not include the sheet filter 62, and water discharged from the perforations 61 a of the first porous tube 61 may be directly supplied to the plastic filter medium 63. In this case, since the water from which the suspended solids are removed is preferably supplied to the nitrification tank 6, a sheet-like filter 62 is provided at a position after the microfilter 4 and before the nitrification tank 6. It is preferred that

  In the nitrification tank 6 according to the present embodiment, the hollow filter medium 64a is fixedly disposed on the nitrification tank main body 67, but is not particularly limited thereto. For example, a plurality of hollow filter media 64a not fixed in the nitrification tank main body 67 may be filled to such an extent that the density of the hollow filter medium 64a is suppressed from being biased in the nitrification tank main body 67 by a water flow or the like.

  Moreover, although the waste water treatment system 10 concerning this embodiment was provided in the culture system 1 of what is called a circulation filtration system, it is not specifically limited to this. The wastewater treatment system 10 may be a nitrification method for ammonia contained in the wastewater in a so-called pouring culture system in which the water used in the aquarium 2 is drained into the sea to cultivate seafood. Moreover, you may be equipped with the aquaculture system which cultures seafood other than a trough puffer. Moreover, the waste water treatment system 10 is not limited to an aquaculture system for culturing seafood, but can be applied to a system that needs to nitrify ammonia in water.

DESCRIPTION OF SYMBOLS 1 ... Aquaculture system, 2 ... Water tank, 3 ... Sedimentation tank, 4 ... Drum filter, 5 ... Aeration tank, 6 ... Nitrification tank, 7 ... Pump, 8 ... Cooling water heater, 10 ... Waste water treatment system, 60 ... Supply port, 61 ... first porous tube, 61a, 65a ... perforated, 62 ... sheet filter, 63 ... plastic filter medium, 63a ... mesh filter medium, 64 ... honeycomb filter medium, 64a ... hollow filter medium, 65 ... second porous tube, 66 ... Discharge port, 67 ... Nitrification tank body, 67a ... Management space, 68 ... Block, 69 ... Grating

Claims (3)

A supply port to which water from a tank where seafood is raised is supplied;
A first porous tube for discharging the water supplied to the supply port;
A plurality of hollow filter medium of the deposited tubular ammonia nitrifying bacteria you nitrified has a hollow inner surfaces contained in the water, the outer surfaces on each of said plurality of hollow filter media adjacent without people gaps respectively A first filter arranged and fixedly disposed in the nitrification tank;
Is adhered prior Ki硝 bacterium, wherein the plurality of the upper respective hollow filter medium substantially uniformly supplying the water discharged from said first perforated tube into the lower, hollow the nitrifying bacteria of the plurality A second filter for propagating the nitrifying bacteria attached to the inner surfaces of the plurality of hollow filter media by moving on the inner surface of the filter media ;
Presenting a sheet shape having a mesh size that removes the suspension contained in the water discharged from the first porous tube, and supplying the water from which the suspension has been removed to the second filter A third filter to
A second porous tube for supplying oxygen from the lower side to the upper side of the plurality of hollow filter media;
An outlet for discharging the water obtained from the lower side of the first filter;
A nitrification tank characterized by comprising: The nitrification tank according to claim 1, wherein the seafood is a pufferfish. A nitrification tank according to claim 1;
A settling tank that is supplied with water from the water tank and removes precipitates contained in the water,
A filter device for removing solids smaller than the precipitate contained in the water after passing through the settling tank;
An aeration tank for supplying air to the water after passing through the filter device,
In the nitrification tank, the water is supplied from the aeration tank to the supply port.

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