JP2004188413A - Wastewater denitrification method, denitrification device, and stirring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decompose and reduce nitrogen compounds such as nitrate nitrogen compounds and nitrite nitrogen compounds contained in waste water by effectively utilizing the biodegradation action of denitrifying bacteria while keeping the inside of a treatment tank anaerobic. A denitrification method, a denitrification device, and a stirring device.
SOLUTION: The wastewater denitrification method of the present invention is a method for denitrification of wastewater 1 in which nitrogen compounds contained in wastewater 1 are denitrified by anaerobic denitrifying bacteria, and the wastewater containing nitrogen compounds is denitrified. 1 is introduced into the treatment tank 2, and the carrier 11 holding the anaerobic bacteria is dispersed in the treatment tank 2, and disposed in the upper layer, and the wastewater 1 is discharged horizontally and obliquely downward by rotating. Impeller 3 that forms a flowing stream, guide vanes 4 that are disposed at the bottom and guides drainage 1 that has descended mainly outward from the center upward, and a baffle plate 6 that is disposed above the impeller 3 The nitrogen compound is denitrified by an anaerobic bacterium in the carrier 11 which is uniformly dispersed and fluidized while maintaining anaerobic while preventing air from entering the water surface.
[Selection diagram] Fig. 1

Description

  The present invention decomposes and reduces nitrogen compounds such as nitrate nitrogen compounds and nitrite nitrogen compounds contained in wastewater by effectively utilizing the biodegradation action of denitrifying bacteria while keeping the inside of the treatment tank anaerobic. The present invention relates to a method for denitrifying wastewater, a denitrification device, and a stirring device.

In general, the denitrification treatment is to remove organic nitrogen and inorganic nitrogen in wastewater, and decomposes these nitrogen components into nitrogen gas and emits them into the atmosphere.
For example, biological treatment of reducing nitrate ions or nitrite ions to nitrogen gas using a denitrifying bacterium is an effective method, and the denitrification reaction is, for example, the following when methanol is used as a hydrogen donor. It is represented by an equation.
^{_{6NO 3 - + 5CH 3 OH →}} 3N 2 + 5CO 2 + 7H 2 O + 6OH -
^{_{6NO 2 - + CH 3 OH →}} 3N 2 + CO 2 + 5H 2 O + 6OH -
In this method, wastewater is maintained under anaerobic conditions with low dissolved oxygen (DO), and nitrate or nitrite respiration of denitrifying bacteria is used to remove nitrogen in nitrate nitrogen compounds or nitrite nitrogen compounds. It reduces to gas.

An apparatus for performing such a denitrification treatment agitates wastewater stored for the purpose of promoting the culture of denitrifying bacteria and promoting the mass transfer of metabolites. As the stirring means, various methods have been proposed, for example, a rotating cylinder is provided in a processing tank, and a centrifugal force generated in the cylinder causes an upward flow to circulate in the cylinder and is provided in the processing tank. A proposal has been made in which an axial impeller is rotatably arranged inside a cylindrical body, and the axial impeller causes an upward flow in the cylindrical body.
However, in this type of apparatus, the carrier having a large buoyancy had to be drawn into the waste water by the surrounding circulation flow and circulated, and the rotational speed of the cylinder had to be increased. In addition, the power for driving the cylinder has to be increased.

Further, in order to solve these drawbacks, there has been proposed a device in which a centrifugal force generating section is provided at a lower end of a cylindrical body rotating in a processing tank to generate a downward flow in the cylindrical body. In this method, the carrier and the waste water are sucked in by the centrifugal force generated by the rotation of the cylinder, discharged from the lower end of the cylinder, and circulated.
However, in this type of apparatus, the amount of suction is adjusted by the rotation speed of the cylinder in order to circulate the carrier having a large buoyancy with the discharge force utilizing the centrifugal force of the rotating cylinder and the suction force associated with it. Was. Therefore, the formed downward flow is weak, and it is difficult to adjust the flow rate. Further, the adjustment range of the downward flow is narrow, and the adjustment is not easy. Furthermore, the mechanism and structure for installing and rotating the cylinder in the processing tank are complicated, and it has been extremely difficult to manufacture a biochemical reactor. Further, slurry or the like easily accumulates in a bearing portion that supports the tube from below, which has caused wear and failure of the bearing.

In addition, by providing a baffle plate fixed to the bottom of the tank and a stirring blade that discharges drainage in the horizontal direction, a flow state where the shearing force of the drainage is small is obtained, and the drainage is performed without crushing the carrier that is weak in shearing force. An apparatus for performing a denitrification treatment in the inside has also been proposed (Patent Document 1, etc.).
However, in the device of Patent Document 1, the amount of dissolved oxygen (DO) increases due to the entrainment of air, and the number of aerobic bacteria increases. Therefore, the amount of a hydrogen donor such as methanol used for maintaining anaerobic increases. There was a problem of doing it. Also, when aerobic bacteria increase, anaerobic bacteria regenerate inside and aerobic bacteria cover the outside in carriers with continuous microcavities such as urethane carriers, so wastewater and anaerobic bacteria However, there has been a problem that the denitrification treatment cannot be performed because of the inability to make contact.

Furthermore, in an apparatus mode in which a stirring blade is provided at the bottom of the tank and a fixed blade is provided at the upper layer, a perforated plate made of a punching metal or the like is fixed (stretched) to the inner wall of the reaction tank (processing tank) without gaps to partition the reaction tank. Thus, an apparatus has been proposed in which a carrier supporting anaerobic microorganisms is prevented from floating on a perforated plate (Patent Document 2). Paragraph Nos. [0005] and [0006] of Patent Document 2 clearly state that the perforated plate functions to prevent the carrier from floating on the water surface and coming into contact with air. It is to be noted that this apparatus is provided with a blind plate having a diameter equal to or smaller than that of the fixed wing, and it is specified that the blind plate functions to prevent the entrainment of air due to the rotational flow of the water to be treated. ing. It is also specified that when the rotation speed of the stirring blade is relatively low, the entrainment of air due to the rotation flow of the water to be treated is unlikely to occur, so that the structure may be simplified by eliminating the blind plate.
However, the apparatus of Patent Document 2 having the above configuration has many problems as described below.
(1) As an essential configuration, a perforated plate (such as a punched metal plate) is fixed to the inner wall of the processing tank, so that it is extremely difficult to assemble the apparatus and manufacture it.
(2) Even if the apparatus can be manufactured, maintenance is extremely difficult because the perforated plate interferes with maintenance work from above.
(3) Further, the holes of the perforated plate need to be smaller than the diameter of the carrier in order to prevent the floating of the carrier from passing through.In other words, the carrier used is larger than the hole of the perforated plate. It was necessary to select a large one and use it.
(4) Also, since the presence of this perforated plate makes it difficult to introduce drainage from above, a drainage inlet must be provided at the bottom of the tank, and this also makes it difficult to manufacture the apparatus.
(5) In addition, the carrier may be clogged by holes in the perforated plate, and when gas is generated in the treatment tank, the gas cannot be easily released from the water surface, resulting in bumping. In some cases, this phenomenon occurred.
(6) Further, in the embodiment in which the blind plate is provided, the structure becomes more complicated, and the manufacture and maintenance of the device are more difficult. Furthermore, since this blind plate has the same or smaller diameter as the fixed wing, even if it is possible to prevent the entrainment of air from near the center of the water surface, the water to be treated that rises near the inner wall in the tank is fixed to the fixed wing. Could not be led to.
JP-A-2002-143889 JP-A-2000-254682

  Therefore, the present invention does not cause the above-described problems, and effectively utilizes the biodegradation action of denitrifying bacteria while keeping the inside of the treatment tank anaerobic. An object of the present invention is to provide a method for denitrifying wastewater, a denitrification device, and a stirring device that decompose and reduce nitrogen compounds such as nitrogen compounds.

  The present invention has been proposed in view of the above, and is a method for denitrifying wastewater in which a nitrogen compound contained in the wastewater is denitrified by anaerobic denitrifying bacteria as described in claim 1, Is introduced into the treatment tank, and the carrier holding the anaerobic bacteria is dispersed in the treatment tank, and the wastewater is horizontally and diagonally lowered by rotating the stirring blades arranged in the upper layer. The drainage that has descended mainly from the outside is guided upward (up) from the center by the guide vanes disposed at the bottom, and the water surface is formed by the baffle plate disposed above the stirring vanes. A method for denitrifying wastewater, comprising denitrifying nitrogen compounds with an anaerobic bacterium in a carrier that has been uniformly dispersed and fluidized while maintaining anaerobic while preventing air from entering from the wastewater. 1 denitrification method)

  Further, the present invention provides a method for denitrifying wastewater in which nitrogen compounds contained in wastewater are denitrified by anaerobic denitrifying bacteria as described in claim 2, wherein the wastewater containing nitrogen compounds is treated. Introduced into the tank, and in the treatment tank, the carrier holding the anaerobic bacteria is dispersed, and by rotating the stirring blades arranged at the bottom, a flow is formed that discharges drainage horizontally and diagonally upward. The drainage, which has risen mainly on the outside, is guided downward from the center (down) by the guide vanes disposed in the upper layer portion, and is disposed above the guide vanes, and has a larger diameter than the guide vanes and a treatment tank. The baffle plate arranged so that a gap is formed between the inner wall of the carrier and the carrier prevents air from coming into contact with the carrier. Denitrification of wastewater characterized by denitrification of compounds Method (hereinafter, referred to as a second denitrification process) but also suggest.

  In addition, the present invention also proposes a denitrification device for performing the first denitrification method as described in claim 3 (hereinafter, referred to as a first denitrification device), which contains a nitrogen compound. A treatment tank that stores the wastewater, a stirring blade that is disposed in the upper layer of the treatment tank and forms a flow that discharges the wastewater horizontally and obliquely downward by rotating, and is disposed at the bottom of the treatment tank; A guide blade that raises the drainage that has descended mainly from the outside from the center, a baffle plate that is disposed above the stirring blade and that prevents air from entering the water surface, and is dispersed in the drainage and contained in the drainage And a carrier holding an anaerobic bacterium for denitrification of the nitrogen compound.

  Further, the present invention also proposes a denitrification device for performing the second denitrification method as described in claim 4 (hereinafter, referred to as a second denitrification device), which contains a nitrogen compound. A treatment tank that stores the wastewater, a stirring blade that is disposed at the bottom of the treatment tank and forms a flow that discharges the wastewater horizontally and obliquely upward by rotation, and is disposed in an upper layer of the treatment tank; A guide wing for lowering drainage, which has risen mainly from the outside, from the center, and disposed above the guide wing so as to have a larger diameter than the guide wing and to form a gap between the inner wall of the processing tank and the guide wing. And a carrier holding anaerobic bacteria dispersed in the wastewater and denitrifying nitrogen compounds contained in the wastewater.

Further, as described in claim 5, a lead-out mechanism is provided outside the upper layer portion in the treatment tank, a filtration part is formed so as to face the water surface, the carrier is filtered, and the treated water is continuously led out by the lead-out mechanism. You may.
Even if the drawing-out mechanism is extended to the outside upper part of the treatment tank as described in claim 6, a filtration part is formed so as to face the water surface, the carrier is filtered and the treated water is continuously drawn out by the drawing-out mechanism. good.
As described in claim 7, in the first denitrification apparatus, a partition plate whose lower end reaches near the bottom surface is provided outside the treatment tank, and the outside of the partition plate is used as a lead-out mechanism. It may be derived continuously.
As set forth in claim 8, in the first denitrification apparatus, an elimination tool may be provided on the baffle plate for gently rotating to remove the carrier reaching the baffle plate to the outside.
Further, in the second denitrification apparatus, a hole may be formed substantially at the center of the baffle plate to wind the carrier reaching the baffle plate.

  The present invention also proposes a stirrer as described in claim 10, wherein a stirrer and a stirrer are disposed at the bottom of the stirrer and rotate to drain the water horizontally and diagonally upward. A stirrer that forms a flow to be discharged; a guide blade that is disposed in the upper layer of the processing tank and that mainly lowers drainage that has risen outward from the center; and a guide blade that is disposed above the guide blade and has a diameter larger than the guide blade. And a baffle plate disposed so as to form a gap between the inner wall of the processing tank and the second denitrification method and the second denitrification apparatus. can do.

In the denitrification method according to the first aspect of the present invention and the denitrification apparatus according to the third aspect, a stirring blade is provided in an upper layer portion and a guide blade is provided in a bottom portion. A circulating flow of wastewater descends spirally in the vicinity of the inner wall) and rises in the center, and the carrier can be uniformly dispersed and fluidized. Nitrogen compounds can be removed by anaerobic bacteria in the carrier while maintaining anaerobic properties. It can be denitrified.
The baffle plate reduces contact between the carrier and air (air entrapment from the water surface) and prevents an increase in dissolved oxygen (DO). The amount of hydrogen donor used can be greatly reduced. In addition, since the baffle plate is disposed so that a gap is formed between the baffle plate and the inner wall of the processing tank, assembly and manufacture are easy, and maintenance work is also easy. Moreover, when gas is generated in the processing tank, the gas can be guided to the water surface from the gap and escaped.

In the denitrification method according to the second aspect of the present invention and the denitrification apparatus according to the fourth aspect, since the stirring blade is provided at the bottom and the guide blade is provided at the upper layer, the outer portion (= In the vicinity of the inner wall of the treatment tank), a circulating flow of wastewater that rises spirally and descends in the center is formed, and the carrier can be uniformly dispersed and fluidized. The compound can be denitrified. This basic structure is almost the same as that of Patent Document 2 described above, but since the perforated plate is not provided as described above, the problems (1) to (5) described above do not occur, and the following effects are obtained. .
(1 ') Manufacturing such as assembly of the device is extremely easy.
(2 ') Maintenance work from above is easy.
(3 ′) The carrier used is not limited with respect to particle size and diameter.
(4 ′) Since the drainage can be introduced from above by inserting a drainage introduction pipe into the gap between the baffle plate and the inner wall, the device can be easily manufactured.
(5 ′) When gas is generated in the treatment tank, the gas can escape upward from the gap and easily escape from the water surface.
Further, since the baffle plate is disposed so as to be larger in diameter than the guide blade and to form a gap between the baffle plate and the inner wall of the processing tank, the above-mentioned problem (6) does not occur. The effect can be achieved.
(6 ′) Since the baffle plate has a larger diameter than the guide vanes, the drainage rising near the inner wall in the processing tank can be guided to the guide vanes.

Further, by providing the denitrification device according to the fifth to seventh aspects of the present invention with the deriving mechanism and the filtering part, the treated water can be continuously discharged while being filtered with a simple structure. As described above, by adopting a structure that does not use a perforated plate as in the above-described conventional apparatus, a derivation mechanism having a simple structure is provided so that treated water can be continuously extracted, and maintenance work can be easily performed. Can be.
Further, in the denitrification apparatus according to claim 8 of the present invention, the carrier that has reached the baffle plate can be removed to the outside by the removal tool, and the carrier can be used efficiently.
Similarly, in the denitrification apparatus according to the ninth aspect of the present invention, the carrier that has reached the baffle plate can be rolled down from the hole and used for the reaction, and the carrier can be used efficiently.

  Furthermore, in the stirring device according to claim 10 of the present invention, since the stirring blade is provided at the bottom portion and the guide blade is provided at the upper layer portion, even if the guide mechanism is provided at the upper layer portion, it is possible to prevent a shortcut of the introduced liquid to be treated. , Can be used as a stirring device.

  In the first denitrification method and the first denitrification apparatus, it is desirable to treat the carrier that has reached the baffle plate while removing the carrier to the outside with a removal tool, and to continuously discharge the treated water while filtering, In the second denitrification method and the second denitrification apparatus, it is preferable that the support reaching the baffle plate is rolled downward from the hole and subjected to the reaction, and the treated water is continuously drawn out while being filtered.

  Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment. 1 to 6 show an example (A1...) Of a first denitrification apparatus for performing the first denitrification method, and FIGS. 7 to 10 show a second denitrification method for performing the second denitrification method. 2 is an example (B1...) Of the denitrification apparatus of FIG.

The denitrification apparatus A1 shown in FIG. 1 includes a treatment tank 2 for storing a wastewater 1 containing a nitrogen compound, and is disposed in an upper layer of the treatment tank 2, and rotates the wastewater 1 horizontally and diagonally downward. A stirring vane 3 for forming a flow to be discharged, a guide vane 4 disposed at the bottom of the treatment tank 2 for raising the drainage 1 that has descended mainly from the outside from the center, and disposed above the stirring vane 3; A baffle plate 6 for preventing air from entering from the water surface, and a carrier 11 dispersed in the wastewater 1 and holding anaerobic bacteria for denitrifying nitrogen compounds contained in the wastewater 1 are provided. 1 has the configuration of a denitrification apparatus.
The lower end of the rotating shaft 21 vertically disposed in the processing tank 2 is a short one located in the upper layer of the processing tank 2, and the stirring blade 3 is formed radially at the lower end of the rotating shaft 21. Thus, a flow of rotating the drive motor 22 to discharge the wastewater 1 horizontally and obliquely downward in the treatment tank 2 can be formed.
In addition, a guide vane 4 disposed at the bottom opposite to the agitating vane 3 disposed at the upper part of the processing tank 2 guides the drainage 1 that has descended in a spiral shape mainly from the outside upward from the center. Can be raised (raised).
Further, a baffle plate 6 is provided above the stirring blade 3, so that contact between the carrier 11 and air (entrance of air from the water surface) can be suppressed. The baffle plate 6 has a diameter larger than that of the stirring blade 3 and is disposed such that a gap 5 is formed between the baffle plate 6 and the inner wall of the processing tank 2. The baffle plate 6 may be formed integrally on the upper surface of the stirring blade 3 as shown in the drawing, and may be rotated integrally with the stirring blade 3 or may be arranged so as to face above the stirring blade 3. Is also good.
In addition, a lead-out mechanism C1 is provided outside the upper layer portion in the treatment tank 2, a partition wall 81 is provided so as to partially include the water surface, and a filtering unit is provided on a part of the partition wall 81 so as to face the water surface. 82 is formed, and the treated water can be continuously discharged to the externally provided discharge path 83. Since the outflow of the carrier 11 is prevented by the filtration unit 82, only the treated water is led out (indicated by a white arrow in the drawing).
Although the introduction of the wastewater 1 is indicated by a hatched arrow in the drawing, an introduction pipe (shown by a dotted line in the figure) is inserted into the treatment tank 2 as shown in FIG. It is desirable to introduce the drainage 1 in a state where the inlet 10 is immersed. Further, when the carriers 11 are accumulated in the filtration unit 82, the blockage of the filtration unit 82 may be eliminated by discharging the treated water from the outside.

Each configuration is not particularly limited as long as it has the above-described operation, and may be designed in any manner. For example, the carrier 11 is preferably a porous (foamed) cellulose, polyester, polypropylene, polyurethane or the like having a diameter of several mm or more, but is a fine particle having a carrier diameter of several mm or less such as activated carbon, alumina, silica, or glass. Those having a relatively large specific gravity can also be used. In addition, a mesh material or the like having openings smaller than at least the carrier 11 can be used as the filtering unit 82.
Further, the stirring blade 3 may be any one that forms a flow of discharging the drainage 1 horizontally and obliquely downward by rotating as described above, and the guide blade 4 mainly descends outside as described above. Any shape may be used as long as the drain water 1 is raised from the center, and the shape thereof is not particularly limited.

  The denitrification apparatus A1, which is the first denitrification apparatus of the present invention having such a configuration, has a circulating flow of the wastewater 1 which descends spirally outside the processing tank 2 (near the inner wall) and rises in the center. Is formed, the carrier 11 can be uniformly dispersed and fluidized, and a nitrogen compound is denitrified by an anaerobic bacterium in the carrier 11 while maintaining anaerobic as in an example of a denitrification method described later. Can be. In particular, since the contact between the carrier 11 and the air is suppressed by the baffle plate 6 and the increase of dissolved oxygen (DO) is prevented, the use of a hydrogen donor such as methanol or acetic acid is compared with the case where the baffle plate 6 is not provided. The amount can be greatly reduced.

The denitrification apparatus A2 shown in FIG. 2 is an example in which an eliminator 7 composed of four plates is provided on the upper surface of the baffle plate 6, and the eliminator 7 rotates slowly (in the direction of the arrow in the figure). Thus, the carrier 11 that has reached the baffle plate 6 can be removed to the outside. Otherwise, the embodiment is the same as the embodiment of FIG. 1, and the same reference numerals are given to the drawings and the description is omitted.
The removal tool 7 is not limited to the illustrated shape, and may have any shape as long as it can remove the carrier 11 that has reached the baffle plate 6 by rotating.
In this embodiment, even if the carrier 11 may reach the upper surface of the baffle plate 6 by the above-described exclusion tool 7, the carrier 11 does not stay in substantially the center of the baffle plate 6 and is quickly removed to the outside. The carrier 11 can be efficiently used because it can be guided to the lower part of the treatment tank 2 for the reaction.

In the denitrification apparatus A3 shown in FIG. 3, the lead-out mechanism C2 is provided with a substantially flat plate-like partition plate 84 whose lower end reaches the vicinity of the bottom surface outside the treatment tank 2, and the outside of the partition plate 84 is a lead-out portion 85. Except for this point, the embodiment is the same as the embodiment of FIG. 1 or FIG. 2, and the same reference numerals are given to the drawings, and the description is omitted.
Also in the processing tank 2 here, as in the embodiment of FIG. 1 or FIG. 2, the flow of the wastewater 1 near the bottom surface in the processing tank 2 moves toward the center and rises from the center. For this reason, since the flow is formed inward in the gap between the lower end and the bottom surface of the partition plate 84, the carrier 11 does not flow to the outside of the lower end of the partition plate 84 (outflow portion 85), and the carrier 11 is externally attached. The treated water can be continuously led out to the lead-out path 86.

The denitrification apparatus A4 shown in FIG. 4 inscribes a cylindrical body 87 having a lower end of a cylinder having a smaller diameter than the treatment tank 2 and a slope surface expanding outwardly. This is the same as the embodiment shown in FIG. 1 or FIG. 2 except that a lead-out mechanism C3 (lead-out path 89) is formed by cutting out the part and forming a filtering part 88. .
The denitrification apparatus A5 shown in FIG. 5 is the same as that of the embodiment shown in FIG. 4 except that a lead-out mechanism C4 (lead-out path 92) is provided as a filtration unit 91 in which the cylinder and the slope surface are all formed of a mesh material or the like. Since this embodiment is the same as the embodiment of FIG. 4, the same reference numerals are given to the drawings and the description is omitted.
In these examples, the derivation of the treated water is basically exactly the same as that in the embodiment of FIG. 1 or FIG. 2, but since the installation of the cylindrical body 87 and the filtration unit 91 which are inner cylindrical is easy, There are great advantages in device design and fabrication. Furthermore, there is an advantage that the effective volume in the processing tank 2 is not reduced as compared with the embodiment in which the partition wall 81 and the partition plate 84 are installed in the processing tank 2.

The denitrification apparatus A6 shown in FIG. 6 is configured such that a part of the processing tank 2 is cut off to form a filtering unit 93, and a deriving mechanism C5 (deriving path 94) externally attached to the upper outside of the processing tank 2 is extended. Since this embodiment is the same as the embodiment shown in FIG. 1 or FIG. 2, the same reference numerals are given to the drawings and the description is omitted.
In this example, the derivation of the treated water is basically the same as that of the embodiment shown in FIG. 1 or FIG. 2, but there is a great advantage in the design and production of the apparatus. Furthermore, there is an advantage that the effective volume in the processing tank 2 is not reduced as compared with the embodiment in which the partition wall 81 and the partition plate 84 are installed in the processing tank 2.

The denitrification apparatus B1 shown in FIG. 7 has a treatment tank 2 for storing wastewater 1 containing a nitrogen compound, and is disposed at the bottom of the treatment tank 2 and discharges the wastewater 1 horizontally and obliquely upward by rotating. A stirring blade 3 for forming a flowing stream; a guide blade 4 disposed in an upper layer of the processing tank 2 for lowering the drainage 1 rising mainly from the outside from the center; and a guide blade 4 disposed above the guide blade 4. A baffle plate 6 which is larger in diameter than the guide vanes 4 and is disposed so as to form a gap 5 between the inner wall of the treatment tank 2 and a nitrogen compound dispersed in the waste water 1 and contained in the waste water 1 And a carrier 11 holding anaerobic bacteria to be nitrified.
In this apparatus, the positional relationship between the agitating blades 3 and the guide blades 4 disposed in opposition to each other is reversed, and the lower end of the rotating shaft 21 vertically disposed in the processing tank 2 is connected to the processing tank 2. It is a long one located at the bottom, and the stirring blade 3 is formed radially at the lower end thereof, and can be rotated by the drive motor 22 to form a flow for discharging the wastewater 1 horizontally and obliquely upward.
In addition, a guide vane 4 disposed in an upper layer portion in opposition to a stirring vane 3 disposed at the bottom of the processing tank 2 guides the drainage 1 which has risen mainly in a spiral shape from the outside downward from the center. (Down).
Further, the baffle plate 6 is fixed to the upper surface of the guide vane 4, and the contact between the carrier 11 and air (entrance of air) can be suppressed. The baffle plate 6 has a larger diameter than the guide vanes 4 and is disposed so as to form a gap 5 with the inner wall of the processing tank 2. Specifically, a baffle plate 6 having a diameter of 95% or less of the inner diameter of the processing tank 2 and larger than the diameter of the guide blade 4 is used. If the diameter of the baffle plate 6 is larger than 95% of the inner diameter of the treatment tank 2, a sufficient gap 5 cannot be secured, and it becomes difficult to introduce the drainage 1 from the water surface. When the diameter of the baffle plate 6 is equal to or smaller than the diameter of the guide vanes 4, the flow of the drainage 1 rising near the inner wall in the treatment tank 2 rises to the water surface, and the carrier 11 comes into contact with air. And air entrapment is likely to occur. In the second denitrification apparatus, the size of the baffle plate 6 is important because the rising flow of the wastewater 1 is near the inner wall in the treatment tank 2, but in the first denitrification apparatus, The size of the baffle plate 6 is not important because the rising flow of the drainage 1 was at the center. The baffle plate 6 may be formed integrally with the upper surface of the guide vane 4 as shown in the figure, or may be arranged so as to face above the guide vane 4.
In addition, about the structure which leads out the drainage 1, the derivation | leading-out mechanism C1 exactly the same as the Example of said FIG. 1 is provided.

The denitrification apparatus B1, which is the second denitrification apparatus of the present invention having such a configuration, has a circulating flow of the wastewater 1 which rises spirally outside the processing tank 2 (near the inner wall) and descends in the center. The carrier 11 can be uniformly dispersed and fluidized, and the nitrogen compound can be denitrified by anaerobic bacteria in the carrier 11 while maintaining anaerobic as in the example of the denitrification method described later. it can. In particular, since the entrapment of air is reduced by the baffle plate 6 and an increase in dissolved oxygen (DO) is prevented, the amount of use of a hydrogen donor such as methanol is significantly reduced as compared with the case where the baffle plate 6 is not provided. Can be.
Further, since a perforated plate is not used as in the above-mentioned Patent Document 2, manufacturing such as assembly of the apparatus is extremely easy, and maintenance work from above is easy. Further, the carrier 11 to be used is not basically limited in terms of particle size and diameter, and the introduction pipe of the drainage 1 (shown by a dotted line in the figure) is inserted from above into the gap 5 between the baffle plate 6 and the inner wall of the processing tank 2. ) Can be inserted, and the drainage 1 can be introduced by immersing the inlet 10, so that the device can be easily manufactured.
Further, when gas is generated in the processing tank 2, the gas can escape upward from the gap 5 and easily escape from the water surface.
Further, since the baffle plate 6 has a larger diameter than the guide vanes 4, it is possible to prevent the flow of the drainage 1 rising near the inner wall in the treatment tank 2 from rising to the water surface and guide the flow to the guide vanes 4. it can.

  In addition, since the hole 61 is formed substantially at the center of the baffle plate 6 in the illustrated embodiment, the carrier 11 reaching the baffle plate 6 moves downward from the hole 61 as indicated by a dotted arrow in the drawing. And is taken up by the guide vanes 4 into a circulating flow descending at the center. Therefore, even if the carrier 11 reaches the baffle plate 6, it can be quickly returned to the circulation flow, and the carrier 11 can be used efficiently. In the second denitrification apparatus, the above-described effect is achieved by the holes 61. However, in the first denitrification apparatus, the flow of the rising wastewater 1 is at the center, so that such holes 61 Is an aspect that cannot be adopted because the carrier 11 floats on the baffle plate 6 as well as not having the above-described effect.

The denitrification apparatus B2 shown in FIG. 8 is inscribed in a cylindrical body 87 having a lower end of a cylinder smaller in diameter than the treatment tank 2 and a slope surface extending outwardly extending around the lower end. 7 is the same as that of the embodiment of FIG. 7 except that the drawing-out mechanism C3 (the drawing-out passage 89) is formed by cutting out the part and forming the filtering part 88. That is, in this example, the derived structure (C3) of the embodiment of FIG. 4 is applied to the embodiment of FIG.
The denitrification apparatus B3 shown in FIG. 9 is the same as that of the embodiment shown in FIG. 8 except that a lead-out mechanism C4 (lead-out path 92) is provided as a filtration unit 91 in which the cylinder and the slope surface are all formed of a mesh material or the like. Since this embodiment is the same as the embodiment of FIG. 7, the same reference numerals are given to the drawings, and the description is omitted. That is, in this example, the deriving mechanism C4 of the embodiment of FIG. 5 is applied to the embodiment of FIG.
In these examples, the derivation of the treated water is basically exactly the same as that in the embodiment of FIG. 7 described above. However, since the installation of the inner cylindrical body 87 and the filtration unit 91 is easy, the apparatus design, There are great advantages in terms of fabrication. Furthermore, there is an advantage that the effective volume in the processing tank 2 is not reduced as compared with the embodiment in which the partition wall 81 and the partition plate 84 are installed in the processing tank 2.

The denitrification apparatus B4 shown in FIG. 10 is configured such that a part of the processing tank 2 is cut out to form a filtration unit 93, and a deriving mechanism C5 (deriving path 94) externally attached to the upper outside of the processing tank 2 is extended. Since this embodiment is the same as the embodiment of FIG. 7, the same reference numerals are given to the drawings and the description is omitted. In this example, the derivation structure of the embodiment of FIG. 6 is applied to the embodiment of FIG.
In this example, the derivation of the treated water is basically the same as that of the embodiment shown in FIG. 7, but there is a great advantage in the design and production of the apparatus. Furthermore, there is an advantage that the effective volume in the processing tank 2 is not reduced as compared with the embodiment in which the partition wall 81 and the partition plate 84 are installed in the processing tank 2.

  Note that, as described above, FIGS. 7 to 10 show examples of the denitrification apparatus for performing the second denitrification method, but these may be used as a stirrer used for other purposes. For example, in these apparatuses, since a flow to be discharged to the outside is formed at the bottom of the processing tank 2, the deriving mechanism C2 in FIG. 3 cannot be employed, but the deriving mechanism C2 in FIGS. When the mechanisms C1 and C3 to C5 are provided in the upper layer, it is desirable in that a shortcut of the drainage 1 (the liquid to be introduced) can be prevented.

[Example]
Hereinafter, an embodiment of the denitrification method using the denitrification apparatus A1 of FIG. 1 will be described.

(Denitrification treatment conditions)
Raw water continuous treatment Carrier used: Tbm Aquacell 5mm □ (manufactured by Taiho Kogyo)
Raw nitrate _{concentration; (NO 3 -N) mg /} L
Methanol addition amount; Nitrogen concentration (N) x 2.5 times Treatment tank capacity: 50 L
Wastewater temperature; 28-40 ° C
pH; 7.5 (automatic control)
pH control chemicals; 45% sulfuric acid oxidation-reduction potential (ORP); -1 to -160 mV
Nitrogen load units; kg-N / m ³ · day

〔Processing result〕
Three levels of nitrogen load were selected, and one week after curing, denitrification treatment was performed under the above treatment conditions. The results are shown in Tables 1 to 3.

As is clear from Tables 1 to 3, it was confirmed that in the present invention, an effective denitrification treatment can be performed under any nitrogen load conditions and under any nitrate concentration of the raw water.
Further, as described above, methanol was added in a nitrogen concentration (N) × 2.5 times, and dissolved oxygen (DO) in the treated water was maintained at 0.1 ppm. It gradually decreased and eventually increased 1.9 times.

  As a comparison, when the denitrification treatment was performed in the same manner except that the baffle plate 6 was not provided in the denitrification apparatus A1 of FIG. 1, the dissolved oxygen (DO) in the treatment liquid was 0.5 ppm And sufficient denitrification treatment was not performed. Therefore, when the amount of methanol added is increased to about three times the nitrogen concentration (N), that is, about 1.2 times the amount added in the present invention, the dissolved oxygen (DO) in the treated water can be maintained at the same level, and Nitriding treatment could be performed similarly. However, it was confirmed that when the treatment was continued, the added amount gradually increased.

  Using the respective denitrification apparatuses A2 to A6 and B1 to B4 shown in FIGS. 2 to 10 and performing the same treatment under the above denitrification treatment conditions, completely the same results were obtained.

  Although the embodiments and examples of the present invention have been described above, the present invention is not limited to these, and can be implemented in any manner as long as the configuration described in the claims is not changed.

  Denitrification of wastewater to decompose and reduce nitrogen compounds such as nitrate nitrogen compounds and nitrite nitrogen compounds contained in wastewater by effectively utilizing the biodegradation action of denitrifying bacteria while keeping the inside of the treatment tank anaerobic Used for

1A is a top view and FIG. 1B is a longitudinal sectional view showing a first embodiment of a first denitrification apparatus according to the present invention. FIG. 3A is a top view and FIG. 3B is a vertical sectional view showing a second embodiment of the first denitrification apparatus according to the present invention. It is (a) top view which shows 3rd Example of the 1st denitrification apparatus concerning this invention, (b) It is a longitudinal cross-sectional view. It is (a) top view which shows 4th Example of the 1st denitrification apparatus which concerns on this invention, (b) It is a longitudinal cross-sectional view. It is the (a) top view and the (b) longitudinal section showing the 5th example of the 1st denitrification device concerning the present invention. It is (a) a top view and (b) a longitudinal section showing a sixth embodiment of the first denitrification apparatus according to the present invention. 1A is a top view and FIG. 1B is a longitudinal sectional view showing a first embodiment of a second denitrification apparatus according to the present invention. It is (a) top view and (b) longitudinal sectional view which show 2nd Example of the 2nd denitrification apparatus which concerns on this invention. It is the (a) top view and the (b) longitudinal section showing the 3rd example of the 2nd denitrification device concerning the present invention. It is (a) top view and (b) longitudinal section which show 4th Example of the 2nd denitrification apparatus which concerns on this invention.

Explanation of reference numerals

A1 to A6 First denitrification apparatus B1 to B4 Second denitrification apparatus 1 Drainage 10 Inlet 11 Carrier 2 Processing tank 21 Rotary shaft 22 Drive motor 3 Stirrer blade 4 Guide blade 5 Gap 6 Baffle plate 61 Holes C1 to C5 Derivation mechanism 7 Elimination tool 81 Partition walls 82, 88, 91, 93 Filtration parts 83, 85, 86, 89, 92, 94 Derivation parts 84 Partition plates 87 Cylindrical body

Claims (10)

  A denitrification method for wastewater in which nitrogen compounds contained in wastewater are denitrified by anaerobic denitrifying bacteria, wherein wastewater containing nitrogen compounds is introduced into a treatment tank, and anaerobic bacteria are introduced into the treatment tank. By dispersing the carrier holding the above, a flow for discharging the drainage horizontally and obliquely downward is formed by rotating the stirring blades arranged in the upper part, and the outer side is mainly formed by the guide vanes arranged in the bottom part. The descending drainage is guided upward from the center, and air is prevented from being mixed in from the water surface by a baffle plate disposed above the stirring blade, and uniformly dispersed while maintaining anaerobic. A method for denitrifying wastewater, comprising denitrifying nitrogen compounds with anaerobic bacteria.   A denitrification method for wastewater in which nitrogen compounds contained in wastewater are denitrified by anaerobic denitrifying bacteria, wherein wastewater containing nitrogen compounds is introduced into a treatment tank, and anaerobic bacteria are introduced into the treatment tank. By dispersing the carrier holding the above, a flow for discharging the drainage horizontally and obliquely upward is formed by rotating the stirring blade disposed at the bottom, and the outer side is mainly formed by the guide blade disposed at the upper layer. A baffle plate that guides the ascending drainage downward from the center, is disposed above the guide vanes, has a larger diameter than the guide vanes, and is disposed such that a gap is formed between the guide vanes and the inner wall of the processing tank. A method for denitrifying wastewater, comprising: denitrifying nitrogen compounds with an anaerobic bacterium in a carrier uniformly dispersed and fluidized while maintaining anaerobic while suppressing contact between the carrier and air.   A treatment tank that stores wastewater containing nitrogen compounds, a stirring blade that is disposed in an upper layer of the treatment tank and forms a flow that discharges the wastewater horizontally and obliquely downward by rotating, and a bottom part of the treatment tank A guide blade that guides the drainage that has descended outward from the center upward, a baffle plate that is disposed above the stirring blade and that prevents air from being mixed from the water surface, A carrier holding anaerobic bacteria dispersed therein for denitrifying nitrogen compounds contained in the wastewater.   A treatment tank for storing wastewater containing nitrogen compounds, a stirring blade disposed at the bottom of the treatment tank and forming a flow of discharging the wastewater horizontally and obliquely upward by rotation, and an upper layer of the treatment tank And a guide wing that guides the drainage that has risen outward from the center downward, and a clearance between the guide wing, which is larger than the guide wing, and the inner wall of the treatment tank. A baffle plate arranged so as to be formed, and a carrier that is dispersed in the wastewater and holds an anaerobic bacterium that denitrifies nitrogen compounds contained in the wastewater. Wastewater denitrification equipment.   The denitrification device for wastewater according to claim 3 or 4, wherein a discharge mechanism is provided outside the upper layer portion in the treatment tank, and a filtration unit is formed so as to face the water surface.   The drainage denitrification device according to claim 3 or 4, wherein a lead-out mechanism is provided at an outer upper portion of the treatment tank, and a filtration unit is formed so as to face the water surface.   The denitrification apparatus for drainage according to claim 3, wherein a partition plate whose lower end reaches the vicinity of the bottom surface is provided outside the processing tank, and the outside of the partition plate is a lead-out mechanism.   The wastewater denitrification apparatus according to any one of claims 3, 5 to 7, further comprising an eliminator on the baffle plate for gently rotating the carrier that has reached the baffle plate to the outside.   The drainage denitrification device according to any one of claims 4 to 6, wherein a hole is formed substantially at the center of the baffle plate for winding the carrier reaching the baffle plate.   A stirring tank, a stirring blade disposed at the bottom of the stirring tank, which forms a flow for discharging drainage horizontally and diagonally upward by rotating, and a stirring blade disposed at an upper layer of the processing tank and mainly rising outside. A guide wing for guiding the discharged wastewater from the center downward, and a baffle disposed above the guide wing and having a diameter larger than the guide wing and arranged so as to form a gap between the inner wall of the processing tank. A stirrer, comprising: a plate;

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