JPH04310298A - Biological nitrogen removing unit - Google Patents

Abstract

PURPOSE:To facilitate anchoring and withdrawal and to simplify the attachment and detachment of necessary apparatuses by utilizing an existing activated sludge sewage treatment plant to remove not only the org. matter but also nitrogen in water to be treated. CONSTITUTION:A biological nitrogen removing unit is constituted of the cage 1 immersed in an aeration tank 9 and provided with a net 1 having a mesh size smaller than bacteria immobilizing carriers 8 under tension, the partitioning means 4 dividing the cage 1 into a denitrifying region 2 and a nitrating region 3, the submerged stirring device 5 arranged in the denitrifying region 2 of the cage 1 and stirring the water to be treated in the denitrifying region 2, the air diffuser 6 arranged in the nitrating region 3 of the cage 1 to send air into the water to be treated of the nitrating region 3, the nitrated liquid circulating apparatus 7 arranged to the cage 1 to circulate the water to be treated from the nitrating region 3 to the denitrifying region 2 and the bacteria immobilizing carriers 8 charged in the denitrifying region 2 and the nitrating region 3.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a unitized nitrogen removal device that converts various nitrogen compounds present in sewage water, etc. into inert nitrogen gas, etc. and removes them. The present invention relates to a unit for biological nitrogen removal.

0002

2. Description of the Related Art FIG. 2 is a schematic diagram showing an example of an activated sludge method, which is one of the conventional sewage water treatment methods. This activated sludge method generally consists of an initial sedimentation tank 21 that settles and separates the SS component of water to be treated such as sewage water, an aeration tank 22 that aerates the water by sending air into the water, and a final sedimentation tank that sediments and separates the sludge. It consists of a pond 23.

[0003] In this conventional activated sludge method, suspended matter that tends to settle in the water to be treated is first settled and removed in a settling tank 21, and then continuously introduced into an aeration tank 22. In the aeration tank 22, aerobic microorganisms are suspended in a fluid state and organic matter in the wastewater is oxidized and decomposed while being aerated. Next, the mixed liquid in the aeration tank 22 is continuously introduced into the settling tank 23, the activated sludge is separated by sedimentation, and the treated water is overflowed to be sterilized and then discharged. At the same time, a part of the activated sludge that has settled is returned to the aeration tank 22, and the other part is disposed of as surplus sludge after being subjected to dewatering and other treatments.

0004

[Problems to be Solved by the Invention] Recently, there has been a demand for the removal of nitrogen from the viewpoint of preventing eutrophication in wastewater treatment. Moreover, it would be preferable in terms of cost and other aspects if existing equipment for the conventional activated sludge method could be converted into equipment that can remove nitrogen.

However, the conventional activated sludge method described above was designed for the purpose of removing organic matter, and cannot be expected to remove nitrogen from the water to be treated. Moreover, in order to use an existing sewage treatment plant using the activated sludge method as a nitrogen removal facility, it is necessary to enlarge the aeration tank 22, but expanding the aeration tank 22 is difficult due to land constraints and the like.

The present invention has been made to solve the above-mentioned problems, and it is possible to remove nitrogen from the water to be treated by using the existing activated sludge method sewage treatment plant as is, and it is easy to install. The object of the present invention is to provide a biological nitrogen removal unit that is easy to remove, and the necessary equipment can be easily installed and removed.

[0007]

[Means for Solving the Problems] The present invention provides a frame that is immersed in a reaction tank to which devices of a nitrogen removal device are attached, partition means that divides the frame into a denitrification region and a nitrification region, and a denitrification region. An underwater agitation device is installed in the frame of the nitrification area to agitate the water to be treated in the denitrification area, an aeration device is installed in the frame of the nitrification area to send air into the water to be treated in the nitrification area, and and a nitrification liquid circulation device that circulates the water to be treated from the nitrification region to the denitrification region.

[0008] In the present invention, a frame immersed in a reaction tank is formed by a cage covered with a net having a mesh size smaller than that of the microorganism immobilized carrier, and the microorganism immobilized carrier is introduced into this cage.

[0009]

[Effect] While the water to be treated remains in the nitrification area, air is blown from the air diffuser to promote nitrification, and a part of the water to be treated in the nitrification area is transferred to the denitrification area by the nitrification liquid circulation device. It is circulated and denitrified in the denitrification area.

By introducing a microorganism-immobilized carrier into the nitrification region or denitrification region, the concentration of microorganisms per reaction tank increases, resulting in an increase in the nitrification rate or denitrification rate, and even in the existing aeration tank, nitrification and denitrification It is possible to carry out sufficient nitrification.

[0011] By unitizing the equipment necessary for nitrogen removal, it can be easily installed and removed from existing wastewater treatment equipment. Moreover, it is easy to install equipment,
Since it is removable, it is easy to repair and repair.

0012

[Embodiment] An embodiment of the biological nitrogen removal apparatus of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing a biological nitrogen removal unit according to an embodiment of the present invention immersed in a reaction tank of an activated sludge method. This nitrogen removal unit includes a cage 1 in which devices for nitrogen removal are attached, and a partition means 4 that divides the cage 1 into a denitrification area 2 and a nitrification area 3.
, an underwater stirring device 5 installed in the cage 1 of the denitrification area 2 to stir the water to be treated in the denitrification area 2, and an underwater stirring device 5 installed in the cage 1 of the nitrification area 3 to stir the water to be treated in the nitrification area 3. An aeration device 6 that sends air, a nitrification liquid circulation device 7 that is installed in the cage 1 and that circulates the water to be treated from the nitrification region 3 to the denitrification region 2, and microorganisms introduced into the denitrification region 2 and the nitrification region 3. It is composed of an immobilization carrier 8.

The cage 1 has microorganism immobilization carriers 8 in a frame (not shown) that has a size that can be immersed in an existing aeration tank 9 and has sufficient strength to attach an underwater stirring device 5, an aeration device 6, etc. A net 1a with a mesh size of 1/4 to 3/4 of the minimum dimension of the net 1a is attached. The cage 1 is divided into two separate regions, a denitrification region 2 and a nitrification region 3, for ease of installation and removal.

A partition means 4 for separating the denitrification region 2 and the nitrification region 3 is provided on the side of the cage 1 of the denitrification region 2 which is in contact with the nitrification region 3. This partitioning means 4 has a partition wall 4A provided at the bottom so that the water to be treated in the nitrification region 3 does not flow back into the denitrification region 2, and a partition wall 4A provided at the top to prevent the water to be treated in the denitrification region 2 from flowing back into the nitrification region 3. It consists of a screen 4B to prevent the microorganism immobilized carrier 8 from overflowing during flowing, and the screen 4B is attached to the partition wall 4A at an angle of 0 to 60 degrees.

[0015] A screen 3B is also provided at the outlet of the cage 1 on the side of the nitrification region 3 in the same manner as described above, and is configured to prevent the microorganism immobilization carrier 8 in the nitrification region 3 from overflowing from the nitrification region 3. There is. However, denitrification region 2 and nitrification region 3
The screens 4B and 3B provided in the cage 1 are not necessarily necessary when the entire cage 1 is covered with the net 1a and the net 1a at the outlet portion plays the role of the screens 4B and 3B.

An underwater stirring device 5 for stirring the water to be treated in the denitrification region 2 is provided at the bottom of the cage 1 in the denitrification region 2 . On the other hand, the cage 1 in the nitrification region 3 is provided with an air diffuser 6 for feeding air into the water to be treated. This air diffuser 6 is a separate device from the air diffuser (not shown) installed in the existing activated sludge method sewage treatment plant, and is installed in the cage 1 of the nitrification area 3 and is unitized. be.

[0017] However, although it is possible to use the existing aeration equipment as is, the existing aeration equipment often lacks the aeration capacity to achieve nitrification as in this method. In many cases, it is necessary to add a new air diffuser 6.

A nitrifying liquid circulation device 7 is installed between the outlet of the nitrification zone 3 and the inlet of the denitrification zone 2, and is configured so that the treated water that has undergone nitrification is circulated to the denitrification zone 2. ing. 7A is a nitrified liquid circulation pipe, and 7B is a nitrated liquid circulation pump that sends the nitrated liquid.

A large number of microorganism immobilization carriers 8 are placed in the cages 1 in the denitrification zone 2 and nitrification zone 3. This microorganism immobilization carrier 8 is formed of a porous single material such as polyurethane, ceramic, activated carbon, etc., and denitrifying bacteria,
On the nitrification region 3 side, there is one carrying nitrifying bacteria.

[0020]In the installation of the above configuration, the cage 1 of the denitrification area 2 of the unitized nitrogen removal unit is placed in the aeration tank 9.
The cage 1 in the nitrification area 3 is placed in the aeration tank 9.
Installed on the downstream side of the In addition, denitrification region 2 and nitrification region 3
A microorganism immobilization carrier 8 is placed in advance.

The operation of the nitrogen removal apparatus having the above structure will be explained below. First, raw water is led from the inlet of denitrification area 2,
It stays in the denitrification region 2 for a certain period of time. During the retention period, the water to be treated in the denitrification area 2 is constantly stirred by the underwater stirring device 5, and the microorganism immobilization carrier 8 and the water to be treated are uniformly mixed, thereby increasing nitrogen removal efficiency.

After the water to be treated remains in the denitrification region 2 for a certain period of time, it overflows into the nitrification region 3 from the upper part of the partition wall 4A, and remains in the nitrification region 3 for a certain period of time. While the water remains in the nitrification region 3, air is blown into the water from the aeration device 6 to promote nitrification. A part of the water to be treated in the nitrification region 3 is circulated to the denitrification region 2 by the nitrification liquid circulation device 7. While the liquid to be treated circulates between the denitrification area 2 and the nitrification area 3, in the denitrification area 2, nitrites and nitrates in the water to be treated are absorbed by the denitrifying bacteria carried on the microorganism immobilization carrier 8 and the denitrifying bacteria in the water. It is denitrified by denitrifying bacteria and converted into inert nitrogen gas, and in the nitrification tank, ammonia and other substances in the water to be treated are converted to nitrites and nitrates by nitrifying bacteria, and nitrogen compounds in the water to be treated are removed through this cycle.

Although not shown, denitrified and nitrified water to be treated is led from the nitrification region 3 to a settling tank, and the treated water is overflowed from the settling tank and discharged after sterilization, while the settled sludge is settles at the bottom of the settling basin. A part of the settled sludge is sent to the denitrification area 2 through the return sludge pipe by the sludge extraction pump.
The remaining sludge is sent back to the inlet of the sludge, and the remaining sludge passes through a surplus sludge pipe where it is dehydrated and then disposed of.

When repairing or repairing the underwater agitation device 5 or the aeration device 6, etc., the cage 1 can be easily repaired or repaired by pulling it up from the aeration tank 9, and the inside of the reaction tank can be easily repaired or repaired. There is no need to drain the water to be treated.

Although one unit has been described in the above embodiment, it goes without saying that a plurality of units may be used in an activated sludge method in which denitrification and nitrification are carried out continuously in multiple stages.

[0026]Although the biological nitrogen removal unit is constructed by dividing the cage 1 into the denitrification area 2 and the nitrification area 3, this nitrogen removal unit removes these cages 1 as one unit. The nitrification region 2 and the nitrification region 3 may be simply separated by a partitioning means 4.

Furthermore, in the above embodiment, the cage 1 is attached with a net 1a on the frame body to which the underwater stirring device 5, the aeration device 6, etc. are attached.
It consists of a frame consisting only of a frame body to which an underwater stirring device 5, an aeration device 6, etc. are attached,
The denitrification region 2 and nitrification region 3 of this frame are separated by a screen 4.
The nitrification region 3 may be partitioned by a partition means 4 having a nitrification region 3, and a screen 3B may also be provided at the outlet of the nitrification region 3.

Furthermore, in the above embodiment, the microorganism immobilization carrier 8 is placed in the denitrification zone 2 and the nitrification zone 3, but the microorganism immobilization carrier 8 does not necessarily have to be placed in both tanks 1 and 2. , or may be added to at least one of the tanks. Further, it is not necessary to introduce the microorganism immobilization carrier 8 into the denitrification region 2 and the nitrification region 3 at all.

[0029]

[Effects of the Invention] By unitizing the equipment necessary for nitrogen removal as in the above configuration, existing activated sludge method sewage treatment plants can be used as is, and installation in existing sewage and wastewater treatment equipment is possible. , easy to remove. In addition, repairs and repairs are easy because the necessary equipment can be easily attached and removed.

[0030] Furthermore, the present invention improves the denitrification rate and the nitrification rate by increasing the microorganism concentration per reaction tank by introducing a microorganism-immobilized carrier into at least one of the denitrification region and the nitrification region. It is also possible to reduce the volume of the reaction tank by increasing the height of at least one of them.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which an embodiment of the biological nitrogen removal unit of the present invention is immersed in an aeration tank.

FIG. 2 is a configuration diagram showing an example of a conventional activated sludge method.

[Explanation of symbols]

1 Cage 2　　　Denitrification area 3 Nitrification area 4 Partition means 5. Underwater stirring device 6. Air diffuser 7 Nitrification liquid circulation device 8 Microorganism immobilization carrier 9 Aeration tank

Claims (2)

[Claims] 1. A frame immersed in a reaction tank and removable from the reaction tank, a partition means for dividing the frame into a denitrification area and a nitrification area, and a partition means installed in the frame of the denitrification area for denitrification. An underwater stirring device that stirs the water to be treated in the area, a diffuser installed in the frame of the nitrification area to send air into the water to be treated in the nitrification area, and a diffuser installed in the frame to move air from the nitrification area to the denitrification area. A biological nitrogen removal unit consisting of a nitrification liquid circulation device that circulates the water to be treated. 2. The method according to claim 1, wherein the frame immersed in the reaction tank is formed by a cage covered with a net having a mesh size smaller than that of the microorganism-immobilized carrier, and the microorganism-immobilized carrier is introduced into the cage. Unit for biological nitrogen removal.