JPH0810793A - Nitrification and denitrification equipment - Google Patents

Abstract

PURPOSE:To efficiently execute nitrification and denitrification treatments by respectively forming denitrification vessels which are partitioned to two vessels, upper and lower, by partition walls and have raw water inflow ports in the lower story and nitrification vessels which have outflow water paths for treated water in the upper story and circulate liquids in order of the outflow water paths, pipings and the inflow water paths between the nitrification vessels and the denitrification vessels. CONSTITUTION:The nitrification and denitrification equipments 14 of a biological reaction plate 10 adjacently provided with an aeration tank 12 and plural sets of the nitrification and denitrification equipment 14 are composed by segmenting the main bodies to the nitrification vessels 28 and the denitrification vessels 20 by the partition walls 26. The outflow water paths 38 disposed in the nitrification vessels 28 and the inside of the denitrification vessels 20 are communicated by communicating pipes 52. The inside of the denitrification vessels 20 and the inflow water paths 54 disposed in the nitrification vessels 28 are communicated by communicating pipes 55. The liquid is circulated between both vessels 28 and 20 by the air lift effect from air diffusers 3 of the nitrification vessels 28. As a result, the air 66 from the air diffusers 33 or the liquid of the nitrification vessels 28 having the high concn. of dissolved oxygen are prevented from short passing into the denitrification vessels 20, by which the increase of dissolved oxygen in the denitrification vessels 20 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological treatment apparatus for wastewater, and more particularly to a nitrification / denitrification apparatus that includes a nitrification tank and a denitrification tank and circulates a part of the nitrification solution into the denitrification tank.

[0002]

2. Description of the Related Art In this type of nitrification / denitrification apparatus, raw water flowing into the nitrification tank through the denitrification tank is nitrified in the nitrification tank in an aerobic state, and a part of the nitrification liquid is transferred to the denitrification tank. It is circulated and denitrified in an anaerobic state. Nitrogen gas generated by this denitrification process is released from the liquid surface of the denitrification tank to the outside air, whereby ammonia nitrogen in the wastewater is removed. In the case of the conventional nitrification / denitrification apparatus, a fixed amount of nitrification solution nitrified in the nitrification tank was circulated to the denitrification tank by a circulation pump. However, the circulation system using this pump requires pump power, and there is a drawback in that the power cost of the apparatus increases significantly when the circulation ratio from the nitrification tank to the denitrification tank increases.

For this reason, a nitrification / denitrification system of the type in which the nitrification liquid is circulated through the denitrification tank without the need for a circulation pump has been adopted. In this nitrification / denitrification apparatus, a partition wall is provided to partition the substantially central portion of the rectangular parallelepiped apparatus main body in the longitudinal direction (the direction in which the nitrification tank and the denitrification tank are arranged), and one of them serves as a denitrification tank and the other serves as a nitrification tank. Then, the nitrification liquid in the nitrification tank is communicated with the nitrification tank and the denitrification tank arranged in the longitudinal direction by an air lift function by an air diffuser or a dedicated air diffuser for making the inside of the nitrification tank aerobic. The nitrification liquid is circulated from the nitrification tank to the denitrification tank by overflowing the circulation channel.

However, in the case of the circulation type nitrification / denitrification apparatus utilizing the air lift action, although there is a merit of energy saving as compared with the circulation type using a pump,
Since the longitudinal direction of the denitrification device is as long as about 100 meters, there is a drawback that the circulating water channel becomes extremely long. Also,
There is a drawback in that it becomes difficult to control the circulation amount of digestive juice due to the long circulation channel. Also, like this,
In the case of a horizontal nitrification / denitrification device in which the nitrification tank and the denitrification tank are arranged on the same plane, there is a drawback that a large space (site area) is required to install the nitrification / denitrification apparatus.

From such a background, as a nitrification / denitrification apparatus utilizing the air lift action and requiring no large space, a vertical type nitrification / denitrification apparatus in which the apparatus main body is divided into upper and lower two tanks by a partition wall is proposed. Proposed. As this type of nitrification / denitrification device, there is a wastewater biological treatment device which has been filed by the applicant of the present application and is disclosed in JP-A-60-193593. In this biological treatment apparatus, the main body of the apparatus is partitioned by a partition wall into two upper and lower tanks (a nitrification tank on the upper floor and a denitrification tank on the lower floor), and the upper and lower two tanks communicate with each other at the opening of the partition wall. Then, the air is lifted by air from an air diffuser provided at the bottom of the nitrification tank to circulate the nitrification tank and the denitrification tank through the opening. Further, as a similar nitrification / denitrification device, there is a waste water denitrification tank disclosed in Japanese Utility Model Publication No. 58-33840. This device
The apparatus main body is divided into two upper and lower tanks (nitrification tank on the upper floor and denitrification tank on the lower floor) by partition walls, and the two tanks are connected by a communication channel (corresponding to the opening) formed in the partition walls, and the partition walls The air is connected to the air lift section vertically arranged in the denitrification tank through the opening, and air is diffused in the air lift section. Then, the liquid in the upper and lower two tanks is circulated through the communication flow path and the air lift portion by the air lift action diffused in the air lift portion.

[0006]

However, JP-A-60-193593 and JP-B-58-33840 are used.
The conventional vertical nitrification / denitrification apparatus disclosed in Japanese Patent Publication has the following drawbacks. The liquid in the nitrification tank that requires aerobic condition and the liquid in the denitrification tank that requires anaerobic condition are in direct communication with each other through the open part (or communication passage) of the partition wall (or partition wall). . Therefore, riding on the flow from the nitrification tank to the denitrification tank generated in the open part, the air from the air diffuser or the liquid of the nitrification tank in the state of high dissolved oxygen easily mixes into the denitrification tank, The dissolved oxygen in the liquid becomes high. As a result, the inside of the denitrification tank cannot maintain a good anaerobic condition, which has a drawback that the denitrification reaction is hindered.

Further, since the nitrification tank is located on the upper floor of the denitrification tank, digestive gases such as methane gas and nitrogen gas generated by the denitrification reaction in the denitrification tank reach the outside air after passing through the nitrification tank. Therefore, compared with the horizontal nitrification / denitrification apparatus described above, it has a drawback that it is less likely to be released to the atmosphere, and has a drawback that it adversely affects the nitrification reaction because it passes through the nitrification tank.

Further, in order to circulate the liquid in the nitrification tank to the denitrification tank, a swirl flow must be generated between the nitrification tank and the denitrification tank, and the entire surface of the nitrification tank is diffused. I can't. As a result, in the nitrification tank, an area with a sufficient amount of air diffused and an area with insufficient air diffusion are likely to occur, and there is a drawback that the digestion reaction in the nitrification tank becomes uneven. As described above, the conventional horizontal nitrification / denitrification device has drawbacks in that it has a large installation space, a long circulating water channel, and difficulty in controlling the circulation amount. It is difficult to form good aerobic conditions in the nitrification tank and good anaerobic conditions in the denitrification tank, so that nitrification and denitrification treatment cannot be performed efficiently, and digestive gas generated in the denitrification tank is not easily released to the outside air. There is a drawback that. Therefore, none of the nitrification / denitrification equipment was satisfactory.

The present invention has been made in view of the above circumstances, and eliminates the drawbacks of the conventional nitrification / denitrification apparatus, and
An object of the present invention is to provide a nitrification / denitrification device that can efficiently perform denitrification processing, can easily control the circulation amount, and can save energy and make the device compact.

[0010]

In order to achieve the above-mentioned object, the present invention forms a denitrification tank having a raw water inlet on the lower floor by dividing the tank into upper and lower two tanks by a partition wall, and discharging treated water. An apparatus main body having a nitrification tank having a water channel formed on the upper floor, a large number of carriers added in the nitrification tank and carrying nitrifying bacteria, and one opening communicating with the outflow water channel, and in the denitrification tank A first communication pipe having the other opening formed therein,
A second communication pipe having one opening formed in the denitrification tank, the other opening being in communication with an inflow water channel provided in the nitrification tank or in the vicinity of the nitrification tank and communicating with the nitrification tank; An air diffuser provided at the bottom of the nitrification tank for diffusing air into the nitrification tank, and between the nitrification tank and the denitrification tank, the outflow water channel, the first pipe, and the second Plumbing,
It is characterized in that the liquid is circulated in the normal path of the inflow water channel.

[0011]

[Function] The nitrification / denitrification apparatus of the present invention has a denitrification tank on the lower floor,
The nitrification tank was installed on the upper floor, and the upper and lower two tank structures that can reduce the site area were constructed, and the drawbacks of the conventional upper and lower two tank structures were solved by the following structures. That is, according to the nitrification / denitrification apparatus of the present invention, the apparatus main body is completely partitioned by the partition wall into the nitrification tank and the denitrification tank, while the outflow channel of the treated water and the inside of the denitrification tank provided in the nitrification tank are The second communication pipe communicates with the inside of the denitrification tank and an inflow water channel provided in the nitrification tank or in the vicinity of the nitrification tank and communicating with the nitrification tank. Then, between the nitrification tank and the denitrification tank, an outflow water channel, a first pipe,
The liquid was circulated through the second pipe and the inflow water channel. That is, unlike the conventional vertical nitrification / denitrification apparatus, the nitrification tank and the denitrification tank do not directly communicate with each other due to the opening formed in the partition wall. As a result, the air from the air diffuser installed in the nitrification tank or the liquid in the nitrification tank in a state of high dissolved oxygen does not mix into the denitrification tank, preventing the dissolved oxygen in the liquid in the denitrification tank from increasing. it can. Furthermore, while the liquid in the nitrification tank flows through the first communication pipe and descends into the denitrification tank, air bubbles in the liquid rise and escape, so that the anaerobic state of the denitrification tank can be better maintained. Therefore, since the anaerobic state in the denitrification tank is maintained well, the denitrification reaction can be efficiently performed. Also,
By providing a defoaming device for eliminating bubbles of the liquid flowing into the outflow water channel near the outflow water channel, the anaerobic state of the denitrification tank can be further maintained.

Further, since the circulation of the liquid between the nitrification tank and the denitrification tank is configured as described above, the nitrification tank and the denitrification tank are separated from each other as in the case of forming an open portion in the conventional partition wall for circulation. There is no need to generate swirling flow between them. Thereby, the entire surface of the nitrification tank can be diffused. Therefore, the aeration in the nitrification tank is not biased, and the inside of the nitrification tank is maintained in a favorable aerobic state, so that the nitrification reaction can be efficiently performed. In addition, since many carriers carrying nitrifying bacteria are added to the nitrification tank, the nitrification reaction is promoted.

Further, since the air lift effect by the air from the air diffuser is used as the power for circulating the liquid,
It saves energy because it does not need to use pump power. At this time, circulation can be performed more smoothly by providing an air diffuser for generating an air lift action in the second communication pipe or a pump for generating an upward flow in the second communication pipe.
Further, since the control means for controlling the circulation amount of the liquid circulating in the inflow water channel is provided, the circulation amount of the liquid can be easily controlled according to the conditions such as the property of the raw water and the water temperature.

Further, the denitrification tank is provided with a stirrer, and a duct is provided through which an opening formed in the partition wall above the stirrer passes through the nitrification tank and communicates with the outside air. As a result, digestive gases such as methane gas and nitrogen gas generated in the denitrification tank can be released to the atmosphere without passing through the nitrification tank, so that the nitrification reaction in the denitrification tank is not hindered,
The duct can be used as a carry-out path for repairing the stirring device. In addition, the surface of the partition wall on the denitrification tank side,
When the slope having the opening of the duct as the apex is formed, the digestive gas is likely to collect at the inlet of the duct, so that it can be released to the atmosphere more quickly.

[0015]

The preferred embodiments of the nitrification / denitrification apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing the internal structure of a bioreactor for biologically removing phosphorus and nitrogen simultaneously by combining an anaerobic tank and the nitrification / denitrification apparatus of the present invention. 2 is a plan view of the nitrification / denitrification apparatus of the present invention seen from the upper side (nitrification tank side), FIG. 3 is a vertical sectional view taken along line AA of FIG. 2, and FIG. 4 is BB of FIG.
It is sectional drawing along the line.

As shown in FIG. 1, the bioreactor 10 comprises:
Anaerobic tank 12 and a plurality of nitrification / denitrification devices 14, 1 of the present invention
And 4 are provided adjacent to each other. Then, the raw water 16 that has flowed into the anaerobic tank 12 is distributed and supplied to the denitrification tank 20 to be described later of each nitrification / denitrification device 14 through a plurality of raw water pipes 18, 18. In addition, the anaerobic tank 12 has a large underwater agitator 2
2 is provided and an absolute anaerobic state is formed with neither molecular oxygen nor bound oxygen. Further, the raw water inflow amount flowing into the anaerobic tank is adjusted by the raw water flow rate adjusting device 17, and the raw water supply amount supplied from the anaerobic tank 12 to each nitrification / denitrification device 14 is adjusted by the supply flow rate adjusting device 24. It

Next, the nitrification / denitrification apparatus 14 of the present invention will be described. As shown in FIG. 1, the rectangular parallelepiped nitrification / denitrification apparatus main body 14 is partitioned by a partition wall 26 into upper and lower two tanks, and The denitrification tank 20 is formed on the floor, and the nitrification tank 28 is formed on the upper floor. In addition, activated sludge is added to the denitrification tank 20 and the nitrification tank 28, and nitrifying bacteria are immobilized in the nitrification tank 28 separately from the activated sludge, for example, a large number of carriers 3 are entrapped and immobilized.
0 is added. Further, an underwater stirrer 32 is provided at the bottom of the denitrification tank 20, and by slowly stirring the liquid in the denitrification tank 24 with this underwater stirrer 32, the air in the raw water is deaerated to form an anaerobic state.

On the other hand, a large number of air outlets 34, 34 ... Of an air diffuser 33 for ejecting air are formed on the entire bottom surface in the nitrification tank 28. The air diffuser 33 is connected to a compressor (not shown) via a high pressure air pipe (not shown). As a result, air is diffused over the entire surface of the liquid in the nitrification tank 28 from the air outlet 34, an aerobic state is formed in the nitrification tank 28 to nitrify the ammonia nitrogen in the raw water 16, and the entire surface is diffused. By the air lift action of air by
The water level in the nitrification tank 28 becomes high.

Further, as shown in FIGS. 1 to 4, the nitrification tank 2
An outflow water channel 38 through which the treated water 36 flows out of the apparatus is provided along one longitudinal side wall surface of the device 8. A side surface of the outflow water channel 38 on the side of the nitrification tank 28 is formed with a separation screen 40 for separating the carrier 30, and a carrier outflow prevention plate 42 is arranged at an upper end of the separation screen 40. Further, the separation screen 40 is inclinedly provided on the bottom side of the nitrification tank 28, and in the nitrification tank 28 below the separation screen 40, a cleaning air nozzle 44 of the separation screen 40 (see FIGS. 3 and 4). ) Is provided. Thereby, air bubbles from the cleaning air nozzle 44 and the carrier 30
Prevents the separation screen 40 from being clogged by the collision of the separation screen 40 with the surface of the separation screen 40. Further, outside the nitrification tank 28 above the separation screen 40, a defoaming device 46 that sprays water on the liquid surface near the separation screen 40 is provided.
Accordingly, the nitrification tank 28 is blown out from the air diffuser 33.
Since the bubbles that tend to collect on the liquid surface of the separator, especially near the separation screen 40 are extinguished, the carriers are prevented from accumulating in the vicinity of the separation screen 40, and the bubbles are prevented from flowing through the separation screen 40 into the outflow water channel 38. Can be prevented.

In addition, an outflow trough 48 is provided in the outflow water channel 38 along the outflow water channel 38 and is connected to a precipitation device (not shown). 1 and 2) are formed.
Further, a plurality of first communication pipes 52, 52 are arranged in the longitudinal direction so as to penetrate the partition wall 26, one end of which is communicated with the bottom of the outflow water channel 38, and the other end of which is inside the denitrification tank 20. Opened at the bottom. On the other hand, along the other side wall surface in the longitudinal direction of the nitrification tank 28, the inflow channel 5 into which the liquid from the denitrification tank 20 flows.
4 are provided. A plurality of second communication pipes 55 penetrate the partition wall 26 and are arranged in the vertical direction, and one end of the second communication pipe 55 communicates with the bottom of the inflow water channel 54, and the other end of the second communication pipe 55 with an upper part of the denitrification tank 20. It is opened (see FIG. 3). In addition, the pipe 5 from a predetermined position of the inflow water channel 54 to the vicinity of the bottom of the nitrification tank 28
6 is extended, and the tip of the extended pipe 56 is formed sideways or upward so that air from the air diffuser 33 does not enter. As a result, the main body of the device is the partition wall 2
6 is completely partitioned into the nitrification tank 28 and the denitrification tank 20, while the outflow water channel 38, the first communication pipe 52, the second communication pipe 5
5, the inflow water passage 54 and the pipe 56 form a circulation passage for circulating the liquid between the nitrification tank 28 and the denitrification tank 20. In addition, a circulation amount control gate 57 is provided in the inflow water passage 54, whereby the circulation flow rate flowing through the circulation passage can be adjusted according to conditions such as the properties of the raw water and the water temperature. Further, above the liquid surface of the inflow water passage 54, a defoaming device 59 that sprays water on the liquid surface of the inflow water passage 54 is provided (see FIG. 3).

As shown in FIGS. 1, 2 and 4, an opening 58 (see FIG. 4) is formed in the partition wall 26 at a position above the submersible stirrer 32, and the nitrification tank 28 is opened from this opening 58.
A duct 60 is provided that communicates with the atmosphere through the inside. The side surface of the denitrification tank 20 of the partition wall 26 is formed to be inclined in a mountain shape with the opening 58 of the duct 60 as the apex. Also,
Submersible pump 6 for collecting scum near the liquid surface of duct 60
2 is provided, and the submersible pump 62 is a scum pipe 6
4 (see FIG. 4) is connected to a scum treatment facility (not shown). As a result, the scum that is entrained by the raw water 16 and floats on the liquid surface of the denitrification tank 20 is collected.

Next, the operation of the nitrification / denitrification apparatus 14 of the present invention constructed as described above will be described. As shown in FIG. 3, air 66 is supplied from the air diffuser 33 provided in the nitrification tank.
Is diffused over the entire surface of the nitrification tank 28 to make the inside of the nitrification tank 28 aerobic, and the water level in the nitrification tank 28 is higher than that of the anaerobic tank 12, the outflow water channel 38 and the inflow water channel 54 due to the air lift action by the air diffusion. Is kept high (h in the figure). As a result, the liquid in the nitrification tank 28 passes through the separation screen 40 and flows into the outflow water channel 38. Then, the liquid overflows from the overflow port 50 to the outflow trough 48 and is discharged to the outside of the nitrification / denitrification device 14, and a part of the liquid flows downward in the first communication pipe 52 into the denitrification tank 20. Then, the liquid in the denitrification tank 20 flows into the inflow water channel 54 as an upward flow through the second communication pipe 55. Then, the liquid flowing into the inflow water channel 54 flows out to the bottom of the nitrification tank 28 through the pipe 56 as shown in FIG. As a result, a circulating flow is generated between the nitrification tank 28 and the denitrification tank 20. In the generation of this circulation flow, an air diffuser (not shown) for generating an air lift action in the second communication pipe 55 or a pump (not shown) for generating an upward flow in the second communication pipe 55 is used. If provided, circulation can be performed more smoothly. In addition, the inflow channel 5 is used to control the circulation amount.
Since it can be controlled by the circulation amount control gate 57 provided in 4, the optimum circulation amount can be controlled according to the characteristics of the raw water, the water temperature, the difference in the raw water load between day and night, and the like.

Thus, the nitrification / denitrification apparatus 14 of the present invention
According to the above, the main body of the apparatus 14 completely partitions the nitrification tank 28 and the denitrification tank 20 by the partition wall 26, while the outflow channel 38 of the treated water 36 provided in the nitrification tank 28 and the denitrification tank 20 are connected to each other by the first communication. While communicating with the pipe 52, the inflow water channel 54 provided in the denitrification tank 20 and the nitrification tank 28 are communicated with each other by the second communication pipe 55, and further communicated with the nitrification tank 28 by the pipe 56. The nitrification tank 28 and the denitrification tank 20 using the air lift function
The liquid was circulated between and. As a result, the air 66 from the air diffuser 33 or the liquid of the nitrification tank in a state where the dissolved oxygen is high does not mix into the denitrification tank 20.
It is possible to prevent the dissolved oxygen of the liquid in 0 from increasing. Also,
The liquid in the nitrification tank 28 flows in the first communication pipe 52 and the denitrification tank 2
While falling to 0, the bubbles in the liquid rise and escape,
The anaerobic state of the denitrification tank 20 can be better maintained. Furthermore, a defoaming device 46 is provided above the separation screen 40 to defoam bubbles that easily accumulate near the separation screen 40.
Bubbles were prevented from flowing into the outflow channel 38 through the separating screen 40. Therefore, the anaerobic state in the denitrification tank 20 is more favorably maintained, and the denitrification reaction can be efficiently performed.

Further, since the nitrification / denitrification apparatus 14 of the present invention has an upper and lower two-vessel structure, a plurality of nitrification / denitrification apparatuses 1
The length of the liquid circulation path between the nitrification tank 28 and the denitrification tank 20 does not change even if the apparatus main body of the nitrification / denitrification apparatus 14 or the bioreactor 10 becomes long by connecting 4, 14 ... .
This makes it easy to control the circulation flow rate even if the entire apparatus 10 becomes long. Further, since the upper and lower two-tank structure is used, the ratio of the liquid surface of the denitrification tank 20 in contact with the atmosphere can be made extremely small. The anaerobic degree of the denitrification tank 20 can be increased as compared with the denitrification device.

Further, since the liquid circulation between the nitrification tank 28 and the denitrification tank 20 is configured as described above, the entire surface of the nitrification tank 28 can be diffused. As a result, the nitrification tank 28
Since the inside of the nitrification tank 28 is sufficiently aerated and the inside of the nitrification tank 28 is maintained in a favorable aerobic state, the nitrification reaction can be efficiently performed. Incidentally, in the case of a conventional vertical type nitrification / denitrification device having an upper and lower two tank structure, since an opening is formed in the partition wall 26 to circulate it, a swirling flow is generated between the nitrification tank 28 and the denitrification tank 20. Therefore, it is not possible to diffuse the entire surface of the nitrification tank 28, and there are disadvantages that an area where the air is sufficiently supplied and an area where the air is difficult to supply are easily formed in the nitrification tank 28.

Further, the denitrification reaction in the denitrification tank 20 generates a digestive gas such as methane gas or nitrogen gas, and this digestive gas needs to be discharged to the outside of the apparatus 14. However, in the case of the conventional vertical nitrification / denitrification apparatus described above, digestive gas reaches the atmosphere after passing through the inside of the nitrification tank 28, and thus has the drawback that it is difficult to be released into the atmosphere, and the inside of the nitrification tank 28 By passing through, the nitrification reaction is adversely affected. Therefore,
In the nitrification / denitrification apparatus 14 of the present invention, an opening 58 is formed in the partition wall 26 above the submersible stirrer 32, and a duct 60 is provided from this opening 58 to the atmosphere through the nitrification tank 28. Further, the surface of the partition wall 26 facing the denitrification tank 20 is formed to be inclined in a mountain shape with the opening 58 of the duct 60 as the apex. As a result, digestive gases such as methane gas and nitrogen gas in the denitrification tank 20 can be released to the atmosphere without passing through the nitrification tank 28, so that the nitrification reaction in the nitrification tank 28 is not hindered and the duct 60 serves as an underwater stirrer. It can be used as a carry-out path for repairing 32. Also, the partition wall 2
The inclination of 6 facilitates the digestion gas to collect at the inlet 58 of the duct 60, so that the digestion gas can be released to the atmosphere more quickly.

According to the nitrification / denitrification apparatus 14 of the present invention, the nitrification tank 28 and the denitrification tank 20 are arranged on the same plane, which is a drawback of the conventional horizontal nitrification / denitrification apparatus. It is possible to solve the difficulty of controlling the water channel and circulation amount. In addition, a favorable aerobic condition for the nitrification tank and a good anaerobic condition for the denitrification tank were formed, which was a drawback of the conventional vertical nitrification / denitrification equipment with the nitrification tank on the upper floor and the denitrification tank on the lower floor. It is possible to solve the problem that digestive gas that is difficult to make is difficult to be released to the atmosphere. As a result, it is possible to provide a nitrification / denitrification apparatus which can form a favorable nitrification / denitrification treatment state, can easily control the circulation amount, and can save energy and make the apparatus compact.

In the present embodiment, the circulation utilizing the air lift effect by the air from the air diffuser as the power source for circulating the liquid between the nitrification tank and the denitrification tank has been described, but the present invention is not limited to this. Alternatively, a water level difference may be previously formed between the nitrification tank, the outflow part, and the inflow part, and this water level difference may be used, or pump power may be used.

[0029]

As described above, according to the nitrification / denitrification apparatus of the present invention, the following effects can be obtained. It does not require a large installation space unlike conventional horizontal nitrification / denitrification equipment. As a result, the device can be made compact.

Unlike the conventional horizontal nitrification / denitrification apparatus, it is not necessary to lengthen the circulation path between the nitrification tank and the denitrification tank even if the apparatus main body becomes long. This makes it easier to control the circulation amount. Unlike conventional vertical nitrification / denitrification equipment, the air from the air diffuser and the liquid in the nitrification tank with high dissolved oxygen will not enter the denitrification tank. As a result, a good anaerobic state can be formed in the denitrification tank. Further, since it is not necessary to generate a swirling flow for circulation between the nitrification tank and the denitrification tank, the entire surface can be diffused into the nitrification tank. Thereby, a favorable aerobic condition can be formed in the nitrification tank. Furthermore, many carriers carrying nitrifying bacteria were added to the nitrification tank. Therefore, the nitrification / denitrification treatment can be efficiently performed.

Like a conventional vertical nitrification / denitrification device,
Digestion gas generated in the denitrification tank is not released to the outside air through the nitrification tank. That is, a duct connecting the denitrification tank and the outside air was provided so that the digested gas generated in the denitrification tank was released to the outside air without passing through the nitrification tank. As a result, the digestive gas is easily released, and since it does not pass through the nitrification tank, it does not adversely affect the nitrification reaction.

The liquid was circulated between the nitrification tank and the denitrification tank by utilizing the air lift action from the air diffuser. Thereby, energy saving can be achieved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the internal structure of a biological reaction apparatus for biologically simultaneously removing phosphorus components and nitrogen components by combining an anaerobic tank and the nitrification / denitrification apparatus of the present invention.

FIG. 2 is a plan view of the nitrification / denitrification apparatus of the present invention viewed from the upper side (nitrification tank side).

3 is a longitudinal sectional view taken along the line AA of FIG.

4 is a vertical cross-sectional view taken along the line BB of FIG.

[Explanation of symbols]

 10 ... Biological reaction device 14 ... Nitrification / denitrification device 16 ... Raw water 18 ... Raw water pipe 20 ... Denitrification tank 26 ... Partition wall 28 ... Nitrification tank 30 ... Carrier 22, 32 ... Submersible agitator 33 ... Diffuser 34 ... Diffuser Outlet 36 ... Treated water 38 ... Outflow water channel 40 ... Separation screen 48 ... Outflow trough 50 ... Overflow port 52 ... First communication pipe 54 ... Inflow water passage 55 ... Second communication pipe 56 ... Piping 58 ... Duct opening 60 ... Duct 66 ... Air

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C02F 3/30 ZAB A (72) Inventor Masayuki Kojima 1-1-1 Uchikanda, Chiyoda-ku, Tokyo No. 14 Hijiri Plant Construction Co., Ltd. (72) Inventor Hitoshi Kawajiri 1-1-14 Kanda, Uchida, Chiyoda-ku, Tokyo Tokyo Plant Construction Co., Ltd. (72) Inventor Teruaki Kitazawa Within Chiyoda-ku, Tokyo 1-14 Kanda 1-Nitta Plant Construction Co., Ltd.

Claims (8)

[Claims] 1. An apparatus main body having a denitrification tank having a raw water inlet port formed on a lower floor and a nitrification tank having a treated water outflow passage formed on an upper floor, which is divided into upper and lower tanks by a partition wall. A large number of carriers that are added to the nitrification tank and carry nitrifying bacteria, and a first communication pipe in which one opening is connected to the outflow water channel and the other opening is formed in the denitrification tank, A second communication pipe having one opening formed in the denitrification tank and having the other opening communicated with an inflow water channel which is provided in the nitrification tank or close to the nitrification tank and communicates with the nitrification tank. An air diffuser provided at the bottom of the tank for diffusing air into the nitrification tank, and between the nitrification tank and the denitrification tank, the outflow water channel, the first pipe, and the second pipe. Nitrification / denitrification equipment characterized by circulating a liquid through the piping and the inflow channel . 2. The nitrification / denitrification apparatus according to claim 1, wherein a liquid is circulated between the nitrification tank and the denitrification tank by an air lift action of the air diffuser. 3. The nitrification / denitrification apparatus according to claim 1, wherein an air diffusing pipe for generating an air lift action is provided in the second communicating pipe. 4. The nitrification / denitrification apparatus according to claim 1, further comprising a pump for generating an upward flow in the second communicating pipe. 5. The nitrification / denitrification apparatus according to claim 1, wherein the inflow water channel is provided with control means for controlling the circulation amount of the liquid circulating in the forward path. 6. The denitrification tank is provided with a stirrer, and a duct is provided through an opening formed at a position above the stirrer of the partition wall to pass through the nitrification tank to the outside air. The nitrification / denitrification apparatus according to claim 1. 7. The nitrification / denitrification apparatus according to claim 1, wherein a side surface of the partition wall of the denitrification tank is inclined with the opening of the duct as an apex. 8. The nitrification / denitrification apparatus according to claim 1, further comprising a defoaming device provided near the outflow channel for eliminating bubbles of the liquid flowing into the outflow channel.