JPH105778A - Nitrogen removing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly distribute a microorganism immobilizing carrier in a tank. SOLUTION: The microorganism immobilizing carrier 11 is held in fluid state at an inside of an aerobic tank 3, and a carrier separating screen 12 forming a separated water passage 13 between a wall surface of the tank is provided at an upstream side position of a flow out end part tank wall being the flow out end of the aerobic tank 3. Then a parting wall 14 in the tank forming an upward passage 16 communicated with a basin in the tank at a bottom end opening of a bottom part side of the tank between a screen surface is provided at the upstream side position of the carrier separating screen 12, and an air diffusing device 17 is provided at a bottom part of the upward passage 16, and a carrier circulation flow passage 18 is provided by communicating a tank upper part side of the upward passage 16 and a flow in end side of the aerobic tank 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrogen removing apparatus used for treating sewage and industrial wastewater.

[0002]

2. Description of the Related Art Conventionally, in a circulating nitrification denitrification method, wastewater first flows into an anoxic tank for denitrification, then to an aerobic tank for nitrification, and treated water flowing out of the aerobic tank is converted to nitrification. Except for a part that is circulated and returned to the anoxic tank as circulating liquid, it flows out to the final sedimentation basin. In an anoxic tank, BOD components and nitrogen are removed by a denitrification reaction, and in an aerobic tank, Kjeldahl nitrogen including ammonia nitrogen is nitrified to nitric acid or nitrous acid.
In this process, it is common to perform nitrification and denitrification with suspended activated sludge to remove nitrogen.

[0003] Also, as a method of removing nitrogen by using a similar principle, although the structure is different from the circulating nitrification denitrification method,
There are anaerobic / anoxic / aerobic method, nitrification-endogenous denitrification method, and step-flow type multi-stage nitrification denitrification method.

[0004]

As described above, the circulation type nitrification and denitrification method, the anaerobic / anoxic / aerobic method, the nitrification-endogenous denitrification method, and the anoxic tank and the aerobic tank are provided in a plurality of stages. In a biological treatment system constituted by any of the multistage circulation methods, the hydraulic residence time of the entire biological reaction tank is reduced by 1 based on the amount of inflowing wastewater.
It takes 2 to 16 hours. For this reason, it is generally difficult to secure new land at existing sewage treatment plants in large and medium urban areas where the residence time of the entire biological reaction tank is designed and operated with a standard activated sludge method with a residence time of 6 to 8 hours. However, it is difficult to operate the above configuration. In order to solve these problems, the purpose of immobilization technology is to immobilize nitrifying bacteria whose nitrification activity decreases at low water temperature at a high concentration on an immobilization carrier with the aim of greatly increasing the nitrification rate even at low water temperature. Application is being considered.

[0005] However, in the above-mentioned method, since the carrier on which the microorganisms are immobilized is generally used in a fluid state, it is necessary to hold the carrier so as not to flow out of the system from the aerobic tank.
In addition, the nitrifying bacteria-immobilized carrier in the aerobic tank flows along the flow of the mixed solution accompanying the aeration in the aerobic tank, while the inflow sewage flows from the inflow end to the outflow end in the aerobic tank. In order to flow toward the aerobic tank, it exists at a high concentration at the outflow end rather than the inflow end, but in order to obtain high nitrification reaction efficiency, the nitrifying bacteria-immobilized carrier is placed in the aerobic tank. Must be uniform.

Further, there is a technique for immobilizing a denitrifying bacterium as a means for increasing the denitrification rate. However, it is more preferable to immobilize the denitrifying bacterium and the nitrifying bacterium on the same carrier than on each other. It is easy to determine and maintain the carrier specifications, and in the circulating nitrification denitrification method, the anaerobic anoxic aerobic aerobic method, and the step-flow type multi-stage nitrification denitrification method, the carrier separation screen is used for the anoxic tank and aerobic tank. There is no need to install them on both sides, and it is only necessary to install them in the aerobic tank at the later stage. This reduces costs and facilitates maintenance and management. Was.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, a nitrogen removing apparatus of the present invention comprises a biological treatment system having an aerobic tank, in which a microorganism-immobilized carrier is flown inside the aerobic tank. A carrier separation screen that forms a separation water flow path with the tank wall is provided at the upstream position of the outflow end tank wall that forms the outflow end of the aerobic tank, and is provided at the upstream position of the carrier separation screen. A partition wall in the tank that forms an upward flow path communicating with the flow area in the tank at the lower end opening on the bottom side of the tank between the screen surface, and an air diffusion device provided in a lower part of the upward flow path, A carrier circulation flow path is provided by connecting the tank upper side of the passage with the inflow end side of the aerobic tank.

[0008] With this configuration, the microorganism-immobilized carrier in the aerobic tank flows along the flow of the mixed liquid accompanying the aeration in the aerobic tank, and also flows from the inflow end to the outflow end. At the outflow end of the aerobic tank, the mixed solution in the aerobic tank and the microorganism-immobilized carrier flow into the upward flow channel from the lower end opening of the partition wall in the aerobic tank, and diffused gas diffused from the diffuser. Flows along the upward flow of the gas-liquid mixed phase generated by the air lift action of the gas. At this time, the carrier separation screen prevents the microorganism-immobilized carrier from flowing out of the tank. The mixed liquid in the tank and the microorganism-immobilized carrier reaching the upper part of the upward flow path circulate through the carrier circulation flow path to the inflow end side of the aerobic tank and flow again in the aerobic tank. As a result, the microorganism-immobilized carrier is uniformly present in the aerobic tank, and high nitrification reaction efficiency can be obtained.

Further, the nitrogen removing apparatus of the present invention is provided with an oxygen-free tank connected to an inflow end of an aerobic tank, and a biological treatment system in which a mixture of anoxic tank flows from the oxygen-free tank to the aerobic tank. At
The microorganism-immobilized carrier is kept in a fluid state inside the anoxic tank and the aerobic tank, and nitrifying bacteria and denitrifying bacteria are immobilized on the microorganism-immobilized carrier, and the outflow end tank wall forming the outflow end of the aerobic tank is formed. At the upstream position, a carrier separation screen that forms a separated water flow path between the tank wall surface is provided, and at the upstream position of the carrier separation screen, an upward flow path that communicates with the inside of the tank at the lower end opening on the tank bottom side. A partition wall in the tank formed between the upper surface and the screen is provided, and an air diffuser is provided at a lower portion of the upward flow path. The upper side of the upward flow path communicates with the inflow end side of the oxygen-free tank to support the carrier. A circulation channel is provided.

With this configuration, the microorganism-immobilized carrier in the anoxic tank flows from the inflow end to the outflow end in the tank,
From the outflow end, it flows into the inflow end side of the aerobic tank together with the mixed liquid in the tank, flows along the flow of the mixed liquid accompanying aeration in the aerobic tank, and flows from the inflow end to the outflow end. At the outflow end of the aerobic tank, the mixture in the tank of the aerobic tank and the microorganism-immobilized carrier flow into the upward flow path, and the mixture in the tank and the microorganism-immobilized carrier reaching the upper part of the upward flow path are It circulates through the carrier circulation channel to the inflow end side of the anoxic tank, and flows again in the anoxic tank and the aerobic tank. As a result, the microorganism-immobilized carrier on which the denitrifying bacteria and the nitrifying bacteria are simultaneously fixed is uniformly present in the anoxic tank and the aerobic tank, and high nitrification and denitrification reaction efficiency can be obtained. In addition, by simultaneously immobilizing denitrifying bacteria and nitrifying bacteria on the same microorganism-immobilized carrier, the carrier separation screen can be provided only in the latter aerobic tank, and it is not necessary to provide it in the former anoxic tank. The cost can be reduced and the maintenance can be facilitated.

Here, it is a more preferable configuration that the carrier circulation channel also serves as the nitrification liquid circulation channel. Here, it is more preferable to integrally configure the main air diffuser arranged in the aerobic tank and the air diffuser arranged in the upward flow path.

Further, the lower end edge of the partition wall in the tank is inclined toward the flow area in the tank, and the upward flow path is formed so that the cross section of the flow path becomes wider toward the lower end side. Gas can be efficiently collected, and the circulation efficiency of the mixed solution in the tank and the microorganism-immobilized carrier can be increased.

Further, a pump may be provided at the entrance of the carrier circulation channel or in the middle thereof instead of the air diffuser provided below the upward channel.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, a biological treatment system 1 for biologically treating sewage has an anoxic tank 2 in a front stage, an aerobic tank 3 in a rear stage, and sewage inflow passage F ₁ is opening.

The anaerobic tank 2 and the aerobic tank 3 are continuous via an inter-tank connecting part 4, and the inter-tank connecting part 4 serves as an outflow end of the anoxic tank 2 and an inflow end of the aerobic tank 3. ing. Here, the inter-tank connecting portion 4 is constituted by an inter-tank partition wall 5 forming an overflow weir. As shown in FIG. 3, a guide wall 6 for preventing a short circuit of flowing water is provided upstream of the inter-tank partition wall 5. A communication channel 7 is formed between the tank partition wall 5 and the guide wall 6, and after the mixture in the tank of the oxygen-free tank 2 flows into the communication channel 7 from the lower end opening 8 of the guide wall 6, You may comprise so that it may flow over the weir top of the partition wall 5 between tanks, and may flow into the aerobic tank 3. FIG.

A mechanical stirrer 9 is installed at the bottom of the anoxic tank 2, and a main diffuser 10 is installed at the bottom of the aerobic tank 3. The microorganism-immobilized carrier 1 is provided inside the aerobic tank 3.
1 is kept in a fluid state, and in this embodiment,
Although only the nitrifying bacteria are fixed on the microorganism-immobilized carrier 11,
As will be described later, denitrifying bacteria can also be fixed at the same time. A carrier separation screen 12 is provided upstream of the outflow end tank wall 3a forming the outflow end of the aerobic tank 3, and is separated between the carrier separation screen 12 and the tank wall surface of the outflow end tank wall 3a. A water channel 13 is formed. In the present embodiment, the carrier separation screen 12 is disposed from the water surface to the tank bottom so as to face the entire surface of the tank wall,
The setting mode of the carrier separation screen 12 is not limited to the present embodiment, and may be, for example, a configuration in which the carrier separation screen 12 is partially installed to an appropriate depth below the water surface. In the upstream position of the carrier separation screen 12, a partition wall 1 in the tank is provided in order to divert the flow of the flowing water to an upward flow along the screen surface of the carrier separation screen 12.
4, an upward flow path 16 communicating between the carrier separation screen 12 and the partition wall 14 in the tank at the lower end opening 15 on the tank bottom side is formed. Here, as shown in FIG. 4, the in-tank partition wall 14 is provided with the lower end edge 14 a of the in-tank partition wall 14 inclined toward the in-tank flow area side, and
Can be formed such that the cross section of the flow path becomes wider toward the lower end side. In this case, the diffused gas in the upward flow path 16 can be efficiently collected, and the circulation efficiency of the mixed solution in the tank and the microorganism-immobilized carrier 11 can be increased.

An air diffuser 17 serving as a driving source as an air pump is provided below the upward flow path 16, and is provided in the upward flow path 16 by an air lift action of the diffused gas ejected from the diffuser 17. An upward flow of a gas-liquid mixed phase occurs. here,
In the present embodiment, the main diffuser 10 and the diffuser 16 are used.
Is provided separately, but as will be described later, the main diffuser 1
0 and the air diffuser 17 can be provided integrally. As shown in FIGS. 5 and 6, instead of the air diffuser 17 serving as a driving source as an air pump, the carrier circulation flow path 1 is used.
A pump 10 for forming a driving source for carrier circulation and generating an upward flow in the upward flow path 16 at the entrance or midway of the pump 8
It is also possible to set 0. As the pump 100, a screw pump or the like is desirable in order to suppress the wear of the microorganism-immobilized carrier 11.

The upward flow path 16 communicates with the inflow end side of the aerobic tank 3 through a carrier circulation flow path 18 arranged on the both sides of the tank at the upper part of the tank. It communicates with the inflow end side of the anoxic tank 2 through a nitrification liquid circulation flow path 19 arranged in the section. Here, in the present embodiment, the carrier circulation flow path 18 and the nitrification liquid circulation flow path 19 communicate with the oxygen-free tank 2 and the aerobic tank 3 near the water surface, respectively. It is also possible to configure. In addition, the carrier circulation flow path 18 and the nitrification liquid circulation flow path 19 are formed by troughs of an open channel, but may be formed by a conduit of a closed channel. In this case, a gas-liquid separator is provided in the middle of the carrier circulation flow path 18 in order to remove gas diffused in the upward flow path 16.
An outflow channel F ₂ for guiding the treated water to a final sedimentation basin or the like is connected to the separated water channel 13.

Further, as another form of the above-mentioned system, a pump or the like may be additionally provided as a driving device for promoting circulation of the carrier. In this case, as the pump, a screw pump or the like is desirable in order to suppress the wear of the microorganism-immobilized carrier. Also, the pump suction side may be a closed channel, and the pump discharge side may be an open channel. In the case where an anoxic tank is placed after the aerobic tank as in the nitrification-endogenous denitrification method,
In the configuration shown in FIG. 1, the oxygen-free tank is arranged as such and the nitrification liquid circulation flow path is eliminated.
The operation of the above configuration will be described. Sewage inflow channel F
_The sewage flowing from ₁ into the anoxic tank 2 is stirred by the mechanical stirrer 9 and circulates in the internal basin of the anoxic tank 2,
It moves from the inflow end to the outflow end, during which the BOD component and nitrogen in the wastewater are removed by a denitrification reaction of anaerobic bacteria. The mixed liquid in the tank of the oxygen-free tank 2 flows from the outflow end to the junction 4
And flows into the aerobic tank 3.

In the aerobic tank 3, the air or the oxygen-containing gas to be aerated is received from the main diffuser 10, and the nitrifying reaction of nitrifying bacteria nitrifies the Kjeldahl nitrogen containing ammonia nitrogen to nitric acid or nitrous acid. . During this time, aerobic tank 3
The microorganism-immobilized carrier 11 remaining in the internal flow area flows along the flow of the mixed liquid in the tank accompanying the aeration in the aerobic tank 3, and also flows from the inflow end to the outflow end.

At the outflow end of the aerobic tank 3, the mixed solution in the aerobic tank 3 and the microorganism-immobilized carrier 11 are transferred to the partition wall 1 in the aerobic tank 3.
4 flows into the upward flow path 16 from the lower end opening 15 and flows along the upward flow of the gas-liquid mixed phase generated by the air-lift action of the diffused gas diffused from the diffuser 17. At this time, the carrier separation screen 12 prevents the microorganism-immobilized carrier 11 from flowing out of the tank.
2, which flows along the screen surface and prevents the microorganism-immobilized carrier 11 and the like from adhering to the screen surface. The mixed liquid in the tank and the microorganism-immobilized carrier 11 reaching the upper part of the upward flow path 16 circulate to the inflow end side of the aerobic tank 3 via the carrier circulation flow path 18, and again circulate the internal flow area of the aerobic tank 3. Flow. As a result, the microorganism-immobilized carrier 11 is uniformly present inside the aerobic tank 3, and high nitrification reaction efficiency can be obtained.

As shown in FIGS. 7 and 8, a multistage treatment may be performed by providing a subsequent anoxic tank 21 in communication with the outflow end of the aerobic tank 3. In this case, the outflow end tank wall 3a
The lower end opening 22 is provided at the bottom, and the carrier separation screen 12 is stopped at an appropriate depth to prevent short-circuit flow of upward flow, and secure the circulation amount of the mixed solution in the tank and the microorganism-immobilized carrier 11. I do.

As shown in FIG. 9 and FIG.
A carrier circulation channel 31 is provided so as to communicate the tank upper side with the inflow end side of the oxygen-free tank 2. In the present embodiment, the carrier circulation channel 31 also serves as a channel for nitrifying solution circulation. However, a channel for nitrifying solution circulation may be provided separately from the carrier circulation channel 31. In addition, the carrier circulation channel 3
Although 1 is open near the water surface of the oxygen-free tank 2, it can be connected to the tank bottom. Nitrifying bacteria and denitrifying bacteria are immobilized on the microorganism-immobilized carrier 11 at the same time.

With this configuration, the microorganism-immobilized carrier 11 residing in the anoxic tank 2 flows from the inflow end to the outflow end in the tank, and flows together with the mixed solution in the tank at the inter-tank connection section 4. It flows into the inflow end side of the aerobic tank 3 through the passage 7. In the aerobic tank 3, the microorganism-immobilized carrier 11 flows along the flow of the mixed liquid accompanying aeration, and also flows from the inflow end to the outflow end. At the outflow end of the aerobic tank 3, the mixed liquid in the tank and the microorganism-immobilized carrier 11 flow into the upward channel 16, circulate through the carrier circulation channel 31 to the inflow end side of the anoxic tank 2, and It flows inside the tank 2 and the aerobic tank 3.

As a result, the microorganism-immobilized carrier 11 on which the denitrifying bacteria and the nitrifying bacteria are simultaneously fixed is uniformly present in the anoxic tank 2 and the aerobic tank 3, and high nitrification and denitrification reaction efficiency can be obtained. it can. Further, since the denitrifying bacteria and the nitrifying bacteria are simultaneously immobilized on the same microorganism-immobilized carrier 11, there is no need to fix the microorganism-immobilized carrier 11 in the oxygen-free tank 2. Therefore, a carrier separation screen or the like is provided in the oxygen-free tank 2. There is no need to provide it, and construction costs can be reduced and maintenance can be facilitated.

As shown in FIGS. 11 to 12, the partition wall 41 in the tank and the carrier separation screen 42 are provided not on the end of the aerobic tank 3 but on the side thereof, that is, provided in parallel with the flow in the tank basin. The carrier circulation channel 43 is disposed on both the inflow end side and the opposite side along the direction crossing the flow in the aerobic tank 3. Although a diffuser 45 is provided integrally with the main diffuser 10 below the upward flow path 44, the diffuser 45 may be provided separately from the main diffuser 10.

As shown in FIG. 13, the carrier circulation channel 43 can be arranged only on the inflow end side of the aerobic tank 3.
As shown in FIG. 14, the anoxic tank 2
And the aerobic tank 3, and the anoxic tank 2 and the aerobic tank 3 can be communicated by a narrow communication passage 51, and the communication passage 51 can be communicated near the center of the aerobic tank 3. .

As shown in FIG. 15, both carrier circulation passages 43 can be opened with their outlets facing each other, and together with the communication passage 51, are opened near the center of the tank.

As shown in FIG. 16, the carrier circulation channel 43 may be provided with only one. FIG.
As shown in (2), the carrier circulation channel 71 can be provided so as to cross the center of the tank.

[0030]

As described above, according to the present invention, the microorganism-immobilized carrier in the aerobic tank flows in the aerobic tank from the inflow end to the outflow end, and flows upward from the outflow end. By circulating to the inflow end side of the aerobic tank through the carrier circulation flow path and flowing again in the aerobic tank, the microorganism-immobilized carrier is uniformly present in the aerobic tank, and high nitrification reaction efficiency is improved. Obtainable. In addition, a microorganism-immobilized carrier in which denitrifying bacteria and nitrifying bacteria are simultaneously fixed flows in an anoxic tank and an aerobic tank,
By circulating through the upward flow path and the carrier circulation flow path to the inflow end of the anoxic tank and flowing again through the internal flow area of the anoxic tank and the aerobic tank, high nitrification / denitrification reaction efficiency can be obtained. Thus, there is no need to provide a carrier separation screen for retaining the microorganism-immobilized carrier in the oxygen-free tank, so that construction costs can be reduced and maintenance can be facilitated.

[Brief description of the drawings]

FIG. 1 is an overall plan view of a nitrogen removing apparatus according to an embodiment of the present invention.

FIG. 2 is an overall cross-sectional view of the nitrogen removing device in the embodiment.

FIG. 3 is a cross-sectional view of an inter-tank connecting portion showing another embodiment of the present invention.

FIG. 4 is a sectional view of an in-tank partition wall showing another embodiment of the present invention.

FIG. 5 is an overall plan view of a nitrogen removing apparatus according to another embodiment of the present invention.

FIG. 6 is an overall cross-sectional view of the nitrogen removing device in the same embodiment.

FIG. 7 is an overall plan view of a nitrogen removing apparatus showing another embodiment of the present invention.

FIG. 8 is an overall cross-sectional view of the nitrogen removing device in the same embodiment.

FIG. 9 is an overall plan view of a nitrogen removing apparatus according to another embodiment of the present invention.

FIG. 10 is an overall cross-sectional view of the nitrogen removing device in the embodiment.

FIG. 11 is an overall plan view of a nitrogen removing apparatus showing another embodiment of the present invention.

FIG. 12 is a view taken in the direction of arrows AA in FIG. 11;

FIG. 13 is an overall plan view of a nitrogen removing apparatus showing another embodiment of the present invention.

FIG. 14 is an overall plan view of a nitrogen removing apparatus showing another embodiment of the present invention.

FIG. 15 is an overall plan view of a nitrogen removing apparatus showing another embodiment of the present invention.

FIG. 16 is an overall plan view of a nitrogen removing apparatus according to another embodiment of the present invention.

FIG. 17 is an overall plan view of a nitrogen removing apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Biological treatment system 2 Oxygen-free tank 3 Aerobic tank 4 Inter-tank connection section 5 Inter-tank partition wall 10 Main air diffuser 11 Microorganism immobilization carrier 12 Carrier separation screen 13 Separated water flow path 14 In-tank partition wall 16 Upflow Path 17 Air diffuser 18 Carrier circulation path 19 Nitrification liquid circulation path

Continued on the front page (72) Inventor Masahiro Kinoshita 2-47, Shikitsu Higashi 1-chome, Naniwa-ku, Osaka-shi, Osaka (72) Inventor Hiroshi Kishino 1-chome 2, Shikitsu-higashi, Naniwa-ku, Osaka, Osaka No. 47 Inside Kubota Corporation

Claims (5)

[Claims] In a biological treatment system having an aerobic tank, a microorganism-immobilized carrier is kept in a fluid state inside the aerobic tank, and an upstream side of an outflow end tank wall forming an outflow end of the aerobic tank. In the position, a carrier separation screen that forms a separation water flow path between the tank wall surface is provided, and at an upstream position of the carrier separation screen, an upward flow path that communicates with the inside of the tank at the lower end opening on the tank bottom side is provided on the screen surface. A partition wall in the tank formed between the upper flow path and an air diffuser at the lower part of the upward flow path. The upper part of the upward flow path communicates with the inflow end side of the aerobic tank to circulate the carrier circulation flow. A nitrogen removing device comprising a passage. 2. A biological treatment system in which an anoxic tank is connected to an inflow end of an aerobic tank and a mixed solution of the anoxic tank flows from the anoxic tank to the aerobic tank. While holding the microorganism-immobilized carrier in a fluidized state inside the tank, the nitrifying bacteria and the denitrifying bacteria are immobilized on the microorganism-immobilized carrier, and the tank is located upstream of the outflow end tank wall forming the outflow end of the aerobic tank. A carrier separation screen that forms a separation water flow path between the wall surface is provided, and an upstream flow path communicating with the in-tank flow area at the lower end opening on the tank bottom side is provided at an upstream position of the carrier separation screen between the screen surface. A partition wall in the tank to be formed was provided, an air diffuser was provided at the lower part of the upward flow path, and a carrier circulation flow path was provided by communicating the tank upper side of the upward flow path with the inflow end side of the oxygen-free tank. A nitrogen removing device characterized by the above-mentioned. 3. The nitrogen removing device according to claim 1, wherein a main diffuser disposed in the aerobic tank and a diffuser disposed in the upward flow path are integrally formed. 4. The tank according to claim 1, wherein a lower end edge of the partition wall in the tank is provided to be inclined toward a flow area in the tank, and an upward flow path is formed so that a flow path cross section increases toward a lower end side. The nitrogen removing device according to any one of the above. 5. The pump according to claim 1, wherein a pump is provided at an inlet of or in the middle of the carrier circulation channel, instead of the air diffuser provided below the upward channel. Nitrogen removal equipment.