JP3826411B2 - Nitrification denitrification equipment - Google Patents

Description

【００６２】
表１より次のことが明らかである。
【００６３】
即ち、本発明によれば、従来に比べて約２０％程度の滞留時間で窒素成分を十分に処理することが可能である。従って、装置を小型、小容量化できる。また、処理水についても、従来法では溶解性ＢＯＤの不足により硝酸性窒素が残留し、全窒素濃度が高いのに対し、本発明によれば、脱窒が円滑に進行し、十分に窒素濃度の低い高水質処理水を得ることができる。
【００６４】
【発明の効果】
以上詳述した通り、本発明の硝化脱窒装置によれば、
▲１▼ 装置の設置面積が大幅に低減される。
▲２▼ 流入溶解性ＢＯＤ濃度が低下しても、安定して脱窒を行える。
▲３▼ 硝化、脱窒性能が向上する。
▲４▼ 流量変動に対する耐性が高くなり、運転管理が容易になる。
といった効果が奏され、コンパクトで管理が容易な装置により、排水中の窒素を効率的に処理して高水質処理水を安定に得ることができる。
【図面の簡単な説明】
【図１】本発明の硝化脱窒装置の一実施例を示す系統図である。
【図２】本発明に好適な造粒槽の一例を示す一部断面斜視図である。
【図３】図２に示す造粒槽の平面図である。
【図４】従来例を示す系統図である。
【符号の説明】
１ 沈殿槽
２ 脱窒槽
３ 造粒槽
４ 硝化槽[0001]
[Industrial application fields]
The present invention relates to a nitrification denitrification apparatus for removing BOD, nitrogen, SS, and the like from wastewater containing soluble and insoluble organic matter (BOD) such as municipal sewage. Specifically, the present invention relates to a nitrification denitrification apparatus that can perform a stable and efficient denitrification process with a compact apparatus.
[0002]
[Prior art]
Conventionally, as a treatment method for removing nitrogen from sewage or the like, a so-called circulating activated sludge method using floating microorganisms is generally employed. As shown in FIG. 4, this processing method is composed of an initial settling tank 51, a denitrification tank 52, a nitrification tank 53, and a final settling tank 54. The raw water is first introduced into the settling basin 51 and separated into solid and liquid. Supernatant water is introduced into the nitrification tank 53 through the denitrification tank 52, ammonia nitrogen and organic nitrogen components are nitrified in the NO _X by the nitrifying bacteria. A part of the effluent water from the nitrification tank 53 is circulated to the denitrification tank 52, and the NO _x component is reduced to N ₂ by denitrifying bacteria in the denitrification tank 52 and released to the atmosphere. The effluent from the nitrification tank 53 with a sufficiently low nitrogen concentration is sent to the final sedimentation basin 54 and separated into treated water and sludge. A part of the sludge is returned to the denitrification tank 52.
[0003]
As is well known, the denitrification reaction in the denitrification tank 52 consumes soluble BOD as a hydrogen donor.
[0004]
[Problems to be solved by the invention]
The conventional nitrification denitrification apparatus has the following problems.
[0005]
(1) Since the installation area of the device is large, it is difficult to install it in urban areas where there is no room for installation space. A conventional processing apparatus for removing BOD is composed of a first sedimentation tank, an aeration tank, and a final sedimentation tank. Even this BOD removal apparatus requires three tanks with a large capacity, so the installation area is considerably large. However, the nitrogen removal method shown in FIG. 4 further requires a denitrification tank, and requires an installation area twice or more that of the BOD removal device.
[0006]
(2) If the organic substance source (soluble BOD component) necessary for denitrification is insufficient, nitrogen removal may be insufficient.
[0007]
To solve the problem of shortage of BOD in (2) above, an organic oxidation tank that converts the organic matter in the separated sludge of the sedimentation basin to an organic acid by anaerobic treatment is provided, and soluble BOD required for denitrification from insoluble BOD There is also a system for generating the. However, this processing method has a drawback that a relatively large installation area is required because the organic oxidation tank is a floating reaction tank.
[0008]
The present invention solves the above-mentioned conventional problems and is a compact apparatus that requires a small installation area, and even if the soluble BOD concentration of raw water is low, denitrification is performed using insoluble organic matter. It is an object of the present invention to provide a nitrification / denitrification apparatus capable of performing denitrification stably and efficiently by securing a necessary organic material source.
[0009]
[Means for Solving the Problems]
The nitrification denitrification apparatus of the present invention is separated by solid-liquid separation means for separating SS in waste water, granulation means for granulating sludge separated by the solid-liquid separation means, and solid-liquid separation means. A denitrification tank in which the separated water is introduced and the granulated product granulated by the granulation means is held, a fixed bed nitrification tank into which the outflow water of the denitrification tank is introduced, and an outflow of the nitrification tank A nitrification denitrification apparatus comprising: means for returning a part of water to a denitrification tank; and means for discharging the remainder of the effluent of the nitrification tank as treated water to the outside of the system. It has a filtration part, The liquid in this granulation means passes through this filtration part, and is discharged | emitted from this granulation means, It is characterized by the above-mentioned.
[0010]
[Action]
In the present invention, it granules obtained by granulating the separated sludge in waste water solid-liquid separation means, i.e., the granulated product not soluble soluble BOD held in denitrification used as denitrifying bacteria. By using the granulated product that is obtained by granulating and concentrating sludge in this way, it becomes possible to keep the sludge at a high concentration in the denitrification tank, and the denitrification tank is smaller than the conventional floating system. Can be achieved. Normally, in the denitrification tank according to the present invention, sludge can be maintained at a high concentration of 10,000 to 50,000 ppm.
[0011]
In addition, by granulating sludge, it is possible to prevent sludge from flowing out of the denitrification tank with simple means such as screens (perforated plates, nets, slits, etc.), and the residence time of sludge granules in the denitrification tank is reduced to HRT. It can be made longer than (hydraulic residence time). And the insoluble BOD granule is kept for a long time in the denitrification tank, solubilization of the insoluble BOD proceeds, and a BOD component necessary for denitrification is generated. For this reason, even when the soluble BOD concentration in the waste water is low, stable nitrogen removal is performed by using the BOD component generated by solubilization of the insoluble BOD in the denitrification tank. Can be done.
[0012]
In the present invention, since the use of fixed bed nitrification reactor as a nitrification tank, thereby to further miniaturization of the apparatus. That is, the fixed bed type nitrification tank does not require a sedimentation basin for separating sludge and can maintain a high sludge concentration per nitrification tank, so that the tank capacity can be reduced as compared with the floating type nitrification tank.
[0013]
In particular, when the nitrification tank is an upward flow type biological filtration tank in which a filter medium layer is formed with a floating carrier, the tank capacity is greatly reduced to 1/3 to 1/5 of the conventional nitrification tank capacity. be able to.
[0014]
In the present invention, the backwash wastewater from the nitrification tank is fed to the granulation means together with the separated sludge from the solid-liquid separation means, and the SS in the backwash wastewater is also granulated and held in the denitrification tank. good. Thus, by supplying backwash wastewater to the granulating means, the backwash wastewater can be treated together.
[0015]
【Example】
Hereinafter, embodiments of the nitrification denitrification apparatus of the present invention will be described in detail with reference to the drawings.
[0016]
FIG. 1 is a system diagram showing an embodiment of the nitrification denitrification apparatus of the present invention.
[0017]
In Figure 1, 1 is a sedimentation tank (first sedimentation basin), 2 denitrification tank, 3 granulating vessel, 4 is a nitrification tank, V _1, V ₂ is a valve.
[0018]
In this embodiment, the raw water is first introduced into the sedimentation tank 1 as solid-liquid separation means from the pipe 11, and the separated water from which coarse SS has been removed is extracted from the pipe 12 and introduced into the denitrification tank 2. The
[0019]
On the other hand, the sludge (primary sludge) separated in the sedimentation tank 1 is extracted from the pipe 17 and is added with an inorganic salt (inorganic flocculant) and a polymer flocculant (hereinafter referred to as “polymer”) from the adding means 18 and 19, respectively. .) Is added to the granulation tank 3.
[0020]
In the granulation tank 3, sludge is granulated into a granulated product (pellet) as the liquid is swirled by the rotation of the agitator 3 a having rotating blades.
[0021]
That is, the inorganic salt added to the initial sedimentation sludge is aggregated by neutralizing the negatively charged SS charge, and this aggregated floc is coarsened by the polymer while being stirred in the granulating tank 3. And it becomes densified and becomes a granulated particle excellent in separability from water.
[0022]
In addition, in granulation in this granulation tank 3, the backwash waste water of the below-mentioned nitrification tank 4 can be mixed with the initial sedimentation sludge, and the process of backwash waste water can also be performed in a system.
[0023]
The liquid in the granulation tank 3 passes through the screen (filter unit) 3b, and is returned to the precipitation tank 1 through the pipe 21. The granulated product is sent to the denitrification tank 2 through the pipe 20 together with a small amount of liquid. The supply of sludge granules to the denitrification tank 2 may be continuous or intermittent.
[0024]
In the granulation tank 3, as described above, the aggregation granulation reaction is performed while draining with the filtration unit 3 b, and thus a hard and large aggregation floc can be granulated with a small granulation tank.
[0025]
As the inorganic salt added to the sludge, sulfuric acid band, ferric chloride, aluminum chloride, polyaluminum chloride, polyiron sulfate and the like can be used.
[0026]
These inorganic salts are usually added in an amount of about 0.5 to 5% by weight based on the SS content.
[0027]
On the other hand, the polymer is preferably an amphoteric polymer having a cation constituent unit and an anion constituent unit in the molecule, and the molar ratio of the cation constituent unit to the anion constituent unit is greater than 1, particularly 2 to 5 amphoteric. Polymer flocculants are desirable.
[0028]
Examples of the amphoteric polymer flocculant include a copolymer of an anionic monomer component and a cationic monomer component, a copolymer of an anionic monomer component, a cationic monomer component, and a nonionic monomer component, Alternatively, a Mannich modified product or a Hoffmann decomposition product of a copolymer of an anionic monomer component and a nonionic monomer component can be used.
[0029]
Here, examples of the anionic monomer component include acrylic acid (AA), sodium acrylate (NaA), methacrylic acid, and sodium methacrylate. Examples of the cationic monomer component include dimethylaminoethyl acrylate (DAA), dimethylaminoethyl methacrylate (DAM), dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylamide (DAPAAm), dimethylaminopropyl methacrylate, and These quaternized compounds can be mentioned. Examples of the quaternized product include dimethylaminoethyl acrylate methyl chloride quaternized product. Further, dimethylaminopropylacrylamide carbonate and the like can also be used. Examples of the nonionic monomer component include acrylamide (AAm), methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide and the like. As a copolymer of these compounds, specifically, DAA quaternized product / AA / AAm copolymer, DAM quaternized product / AA / AAm copolymer, DAPAAm / AA / AAm copolymer, DAA quaternized product / AAA copolymer or Mannich modified product of NaA / AAm copolymer.
[0030]
The amount of these amphoteric polymer flocculants added is usually preferably in the range of 0.5 to 2.5% by weight relative to the SS content.
[0031]
In the present invention, the addition and mixing of these inorganic salts may be performed by providing a separate agglomeration tank. As shown in the figure, the polymer can be injected directly into the granulation tank 3 or added to a separately provided agglomeration tank. Further, two types of polymers may be used, and one may be added by separate injection means such that one is added in the coagulation tank or pipeline injection, and the other is directly injected into the granulation tank.
[0032]
In the denitrification tank 2, the granulated material of the first settling sludge fed from the pipe 20 is stirred by the stirrer 2 a together with the supernatant water from the precipitation tank 1 and the circulating water from the nitrification tank 4. Thereby, a denitrification reaction and the production | generation of the BOD component by solubilization of a granulated material progress.
[0033]
That is, water introduced into the nitrification tank 4 through the precipitation tank 1, the pipe 12, the denitrification tank 2 and the pipe 13 is ammonia nitrogen (which is contained in the nitrification tank 4 by nitrifying bacteria under aerobic conditions. NH ₄ —N) and the like are oxidized to nitrate nitrogen or nitrite nitrogen (NO _x —N). The effluent nitrification tank 4 is circulated to the denitrification tank 2 as circulating water from the pipe 15, these NO _x -N in denitrification within 2, anaerobic conditions are reduced to nitrogen (N ₂₎ by denitrifying bacteria Removed.
[0034]
In this denitrification tank 2, since the insoluble BOD component in the granulated product of the first settling sludge is oxidized to produce an organic acid, denitrification is performed even when the concentration of soluble BOD in the raw water is low. It is possible to secure sufficient organic substances necessary for the stable denitrification treatment.
[0035]
The treated water in the denitrification tank 2 passes through the screen 2b and is fed from the pipe 13 to the nitrification tank 4, but at this time, the sludge in the denitrification tank 2 is in the form of granulated pellets, By providing a simple filtration means comprising a screen 2b such as a perforated plate, a net, and a slit, it is possible to easily prevent sludge from flowing out together with the treated water.
[0036]
In this invention, since the granulated sludge is made to stay in the denitrification tank 2 in this way, the sludge concentration in the denitrification tank 2 can be normally maintained as high as about 10,000 to 50,000 ppm. Thereby, size reduction of a denitrification tank can be achieved.
[0037]
Excess sludge in the denitrification tank 2 is withdrawn continuously or intermittently from the pipe 22 and dehydrated by a dehydrator.
[0038]
As described above, the effluent from the denitrification tank 2 is introduced into the nitrification tank 4 via the pipe 13 and subjected to nitrification treatment. A part of the effluent from the nitrification tank 4 is circulated from the pipe 15 to the denitrification tank 2, and the remainder is It is discharged out of the system as treated water from the pipe 14.
[0039]
In the present embodiment, the nitrification tank 4 has a filter medium layer 4a in which polystyrene, polypropylene, urethane resin or the like is foamed into a spherical shape with a diameter of 3 to 10 mm or an indefinite shape, and a floatable filter medium having a very small specific gravity is used as a carrier. It is the formed upward flow type biofilm filtration tank, and nitrification is performed by aeration by the aeration tube 4b provided in the lower part of the filter medium layer 4a.
[0040]
In the present invention, the nitrification tank may be a fixed bed type, and in addition to the upward flow type biofilm filtration tank using the floatable filter medium as a carrier, sedimentary filter medium such as sand, activated carbon and synthetic resin is supported as a carrier. And it may be a downward flow type biofilm filtration tank in which the treated water flows downward.
[0041]
In the present invention, since such a fixed bed type nitrification tank is used, a sedimentation basin for separating sludge becomes unnecessary, and by maintaining a high sludge concentration in the nitrification tank, compared to a floating type, The nitrification tank can be downsized.
[0042]
The amount of circulating water circulated from the nitrification tank 4 to the denitrification tank 2 is usually about 2 to 4 in volume ratio of the circulating water amount to the raw water amount flowing into the apparatus (hereinafter referred to as “circulation ratio”). Is preferred.
[0043]
According to the nitrification denitrification apparatus of the present embodiment, treated water from which BOD and nitrogen are highly removed can be obtained by solid-liquid separation treatment in the precipitation tank 1 and nitrification denitrification treatment by the denitrification tank 2 and the nitrification tank 4.
[0044]
In addition, the granulation tank (coagulation concentration apparatus) suitable for this invention is demonstrated with reference to FIG.
[0045]
2 and 3, reference numeral 31 denotes a cylindrical tank, and the agitator 3 a is provided at the center of the cylindrical tank 31. The stirrer 3a includes a rotating shaft 32 that is rotationally driven by a motor and a transmission, and stirrer blades 33 and 34 that are provided in two upper and lower stages with respect to the rotating shaft 32 and are radially provided with a phase of 180 °. . The filtration part 3b is a cylinder having a bottomed filter cylinder 37 slightly smaller than a semicircular shape installed along an arc part of the same curvature along the inner periphery of the cylindrical tank 31, and a bottom 37 ′ of the filter cylinder 37. A plurality of arc-shaped slits 38 provided concentrically with the layer 31 are provided.
[0046]
The filter tube 37 is provided with a hook 35, and the filter tube 37 is fixed by the hook 35 engaging with the upper edge of the cylindrical tank 31.
[0047]
The upper end of the filter cylinder 37 and the upper end of the cylindrical tank 31 are at the same level. The bottom 37 ′ of the filter cylinder 37 is only about 1 to 10 mm away from the upper edge of the upper stirring blade 33 and is approaching. If necessary, a rubber plate may be attached to the upper edge of the stirring blade 33, and the bottom 37 'of the filter cylinder 37 may be stroked with this rubber plate during rotation. The width of the slit 38 is 5 mm or less, preferably about 1 to 2 mm, the distance between adjacent slits in the cylindrical direction is about 2 mm, and the distance between the inner and outer slits in the radial direction is about 5 mm.
[0048]
Note that the upper one 33 of the stirring blade is preferably a flat plate having a constant vertical width over the entire length from the base fixed to the rotating shaft 32 to the tip as shown.
[0049]
The cylindrical tank 31 is also provided with a drain pipe 21 for discharging filtered water from the filter cylinder 37 through the tank wall.
[0050]
While the first settling sludge (including inorganic salt and polymer) supplied from the pipe 17 to the center of the bottom of the tank is stagnating in the tank by the stirring action of the stirring blades 33 and 34 attached to the rotary shaft 32. Reacts evenly mixed. Water (separated liquid) injected into the filter cylinder 37 through the slit 38 at the bottom of the filter cylinder 37 is discharged from the pipe 21 to the outside of the tank. As a result, the continuously supplied sludge is sufficiently concentrated and becomes a granulated product having high strength. This granulated material is discharged from the pipe 20.
[0051]
Just below the bottom 37 ′ of the filter cylinder 37, a horizontal swirling flow a is generated by the swirling of the stirring blade 33. The slit 38 provided in the bottom 37 'of the filter cylinder has a concentric arc shape along the horizontal swirling flow a. For this reason, the aggregated floc and the fibrous substance in the liquid flow under the bottom 37 ′ in the same direction as the extending direction of the slit 38. As a result, flocs and the like are not caught by the slits 38, and the aggregated floc rolls under the bottom 37 'to become a denser and stronger granulated product.
[0052]
The lower agitating blade 34 has a wing plate shape in which the vertical width of the base 40 on the side attached to the rotary shaft 32, which is about half the total length, is narrow and the vertical width of the remaining free end 41 is wide. It is preferable to do this. In this way, the lower blade-shaped stirring blade 34 pushes water outward at the wide free end 41 under the horizontal swirling flow a generated by the upper stirring blade 33, and the flow is swirling while the inner periphery of the tank is swung. In the vicinity, it is divided into an upward flow b and a downward flow b ′, the upward flow b comes into contact with the horizontal swirling flow a by the flat plate-shaped stirring blade 33 and descends toward the center, and the downward flow b ′ is the bottom surface of the tank. Thus, the upper and lower circulation flows swirling at the center and bottom of the tank, and the sludge and the flocculant supplied to the center of the tank bottom ride on the flows b and b ′. Thus, the agglomeration flocs already produced are efficiently mixed and brought into contact with each other for good aggregation. Then, as shown in the figure, when the wide free end 41 is bent at an angle (for example, 45 °) so as to recede with respect to the swirling direction of the blade, the free end pushes water toward the inner periphery of the tank. Strengthening and stronger swirl circulation flows b and b 'are obtained, so that the mixing and contact efficiency is further improved. Furthermore, it is located at the lower end portion of the inner periphery of the cylindrical tank 31 and at the intermediate portion between the upper stirring blade 33 and the lower stirring blade 34, extends in the turning direction of the stirring blade, and gradually moves away from the inner periphery toward the tip. If the curved guide plates 42 and 43 as shown in the figure or the figure are provided, the upper circulating flow b flows along the lower side of the horizontal swirling flow a and then goes down at the center, and the lower circulating flow b ' It is possible to assist in the upward movement at the center along the tank bottom, and the mixing and contact efficiency can be improved in the same manner.
[0053]
Although the case where the filter cylinder is provided in the cylindrical tank as described above has been described, the filter cylinder may be provided outside the cylindrical tank. In that case, a filter cylinder is provided outside the upper outer periphery of the tank wall of the cylindrical tank, and a slit for filtering the liquid in the cylindrical tank into the upper part of the tank wall of the cylindrical tank surrounded by the filter cylinder Is provided horizontally, and the outer edge of the stirring blade may be brought close to the upper inner periphery of the tank wall of the cylindrical tank at an interval of 1 to 10 mm. If necessary, a rubber plate may be attached to the outer edge of the stirring blade, and during rotation, the inner periphery of the tank wall of the cylindrical tank provided with a slit may be stroked with this rubber plate. Even in the granulation tank having such a structure, the sludge supplied from the bottom of the cylindrical tank is agitated and aggregated in the tank, while the water entering the filter cylinder through the slit in the tank wall is drained outside the tank by a pump or the like. Therefore, the continuously supplied sludge is sufficiently concentrated and is discharged after growing into a floc with high strength. The floc generated in the cylindrical tank is pushed by the stirring blade that rotates horizontally close to the inner periphery of the tank wall upper part of the cylindrical tank provided with the slit, and the floc is slit along the inner periphery of the tank wall along the slit. In addition to being clogged with water, it is dense and strong by rolling along the inner periphery of the tank wall along the slit.
[0054]
In addition, as processing conditions in this granulation tank, it is preferable to employ | adopt the density | concentration in a tank 0.5-3 weight / volume% and the peripheral speed 5-20 m / min of a stirring blade.
[0055]
Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples.
[0056]
Example 1
With the nitrification / denitrification apparatus of the present invention shown in FIG.
[0057]
As the nitrification tank, an upward flow type biological filtration tank loaded with a floating synthetic filter medium was used.
[0058]
Raw water quality T-BOD (total BOD): 130 mg / l
S-BOD (soluble BOD): 80 mg / l
TN (total nitrogen): 30 mg / l
SS: 200 mg / l
Operating conditions Precipitation tank surface area load: 30 m / day
Settling tank residence time: 2.4 hr
Excess sludge extraction rate from denitrification tank: 80% of granulated sludge
Denitrification tank sludge concentration: 15000ppm
Denitrification tank residence time: 0.7 hr
Nitrification tank residence time: 0.9 hr
Circulation ratio: 3
Addition amount of inorganic salt (polyaluminum chloride): 1% by weight with respect to SS
Amphoteric polymer (trade name “Clibest P702” manufactured by Kurita Kogyo Co., Ltd.)
Addition amount: 1.5% by weight with respect to SS
Table 1 shows the quality of the treated water obtained. Table 1 also shows the total residence time of the apparatus (total residence time of the precipitation tank, denitrification tank and nitrification tank).
[0059]
Comparative Example 1
The wastewater having the same water quality as the wastewater treated in Example 1 was treated by the conventional apparatus shown in FIG. The operating conditions were as follows.
[0060]
Initial sedimentation basin surface area load factor: 30 m / day
Final sedimentation basin surface area load factor: 20 m / day
Denitrification tank residence time: 4.8 hr
Nitrification tank residence time: 2.2 hr
Circulation ratio: 3
Table 1 shows the quality of the treated water obtained. Table 1 also shows the total residence time of the apparatus (total residence time of the first sedimentation tank, denitrification tank, nitrification tank, and final sedimentation tank).
[0061]
[Table 1]

[0062]
From Table 1, the following is clear.
[0063]
That is, according to the present invention, it is possible to sufficiently treat the nitrogen component with a residence time of about 20% compared to the conventional case. Therefore, the apparatus can be reduced in size and capacity. Also, in the case of treated water, nitrate nitrogen remains due to a lack of soluble BOD in the conventional method, and the total nitrogen concentration is high. However, according to the present invention, denitrification proceeds smoothly and the nitrogen concentration is sufficiently high. Can be obtained.
[0064]
【The invention's effect】
As detailed above, according to the nitrification denitrification apparatus of the present invention,
(1) The installation area of the device is greatly reduced.
(2) Even if the inflow soluble BOD concentration decreases, denitrification can be performed stably.
(3) Nitrification and denitrification performance is improved.
(4) Resistance to flow fluctuations is increased and operation management is facilitated.
With such an effect, a compact and easy-to-manage apparatus can efficiently treat nitrogen in the wastewater and stably obtain high-quality treated water.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a nitrification denitrification apparatus of the present invention.
FIG. 2 is a partial cross-sectional perspective view showing an example of a granulation tank suitable for the present invention.
FIG. 3 is a plan view of the granulation tank shown in FIG.
FIG. 4 is a system diagram showing a conventional example.
[Explanation of symbols]
1 Precipitation tank 2 Denitrification tank 3 Granulation tank 4 Nitrification tank

Claims (3)

Solid-liquid separation means for separating SS in the waste water;
A granulating means for granulating the sludge separated by the solid-liquid separating means;
A denitrification tank in which the separated water separated by the solid-liquid separation means is introduced and the granulated product granulated by the granulation means is held;
A fixed bed nitrification tank into which the outflow water of the denitrification tank is introduced;
Means for returning a part of the effluent of the nitrification tank to the denitrification tank;
Means for discharging the remaining effluent of the nitrification tank out of the system as treated water;
A nitrification denitrification device comprising:
The nitrification denitrification apparatus, wherein the granulation means has a filtration part, and the liquid in the granulation means passes through the filtration part and is discharged from the granulation means. 2. The fixed bed type nitrification tank according to claim 1 , wherein the fixed bed type nitrification tank has back washing means, and the back washing waste water from the nitrification tank is fed to the granulation means together with the separated sludge of the solid-liquid separation means. Nitrification denitrification equipment. 3. The nitrification / denitrification apparatus according to claim 1, wherein the waste water from the granulation means that has passed through the filtration unit is returned to the solid-liquid separation means.

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