JP2003024989A - Denitrification apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a denitrification apparatus capable of keeping a good operation state even if continuously operated. SOLUTION: In the denitrification apparatus using denitrifying bacteria, a carrier 4 for holding denitrifying bacteria is included and an air bubble removing means 10 for removing air bubbles generated accompanying the advance of denitrification reaction is provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a denitrification apparatus for denitrifying nitrate nitrogen in a liquid to be treated by using denitrifying bacteria.

[0002]

2. Description of the Related Art Conventionally, there has been known a wastewater treatment in which, for example, ammonia is nitrified by nitrifying bacteria, and nitric acid produced is further denitrified by denitrifying bacteria. Such wastewater treatment is carried out by a biological treatment apparatus such as a nitrification and denitrification treatment facility such as a nitrification tank and a denitrification tank. Here, the denitrification tank is a denitrification device for denitrifying the nitrate nitrogen in the liquid to be treated (water to be treated) using denitrifying bacteria. As such a denitrification tank, a type is known in which denitrification bacteria are maintained in a carrier to carry out a denitrification reaction. However, in such a type of denitrification tank, the outlet nitrogen concentration in the liquid to be treated varies with the treatment time, and sometimes the preferable outlet nitrogen concentration cannot be maintained.

[0003]

That is, the present invention is
The present invention has been made in response to the above-mentioned request, and an object thereof is to provide a denitrification device capable of maintaining a good operating state even when continuously operated.

[0004]

As described above, the inventors of the present invention continued to search for the reason why the outlet nitrogen concentration fluctuated and the cause thereof. As a result, it was thought that the major cause of this was the nitrogen bubbles generated as the denitrification proceeded. It is presumed that such bubbles hinder the contact between the liquid to be treated and the denitrifying bacteria, and inhibit the denitrification reaction. The bubbles grow into large bubbles when observed by a surveillance camera, and once they are discharged, the outlet nitrogen concentration once decreases.
The outlet nitrogen concentration fluctuated periodically along with this.

In other words, in order to achieve the above object, the present invention provides a denitrifying apparatus using denitrifying bacteria, which includes a carrier for holding the denitrifying bacteria, and bubbles generated as the denitrifying reaction progresses. It is characterized in that a bubble removing means for removing the is provided. In a preferred embodiment, the air bubble removing means may be an air cleaning device for air cleaning the carrier. Further, it may be an ultrasonic wave generator that applies ultrasonic waves to the denitrification device.

Further, in the present invention, it is preferable that the pressure detecting means is installed, the fluid resistance state of the carrier is monitored, and the air bubble removing means is operated. It is also possible to install a nitrate nitrogen detecting means and monitor the nitrate nitrogen concentration to operate the bubble removing means. Furthermore, it is also preferable to take measures to increase the flow rate of the liquid to be treated flowing through the carrier so that air bubbles do not accumulate.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the denitrification apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the entire denitrification tank which is a denitrification device according to the present invention in one form. The denitrification tank 1 is provided with a cathode 2 and an anode 3, and is filled with a carrier 4 having good conductivity to carry denitrifying bacteria. The denitrifying bacteria include those known as this type of denitrifying bacteria, such as activated sludge derived from sewage treatment plants. Denitrification tank 1
Functions as a nitrate nitrogen treatment tank. Further, the denitrification tank 1 is divided by a diaphragm 5 into a cathode chamber 6 and an anode chamber 7.

The carrier 4 is for supporting the denitrifying bacteria as described above, and is made of a conductive material such as activated carbon or carbon used for the anode of a dry battery. Under the condition that conductivity is not required, as a carrier, sand, anthracite, ceramic (porcelain, porcelain, glass fiber, etc.), plastic (polyethylene, polypropylene,
A carrier such as beads composed of a material such as nylon or cellulose can be used.

The diaphragm 5 is for preventing a short circuit between the anode 2 and the cathode 3. In this embodiment, the material is, for example, a non-woven fabric. The cathode 2 is
It is preferable that the anode 3 is made of carbon and the anode 3 is made of a material such as carbon, Pt, palladium, or gold. In the present embodiment, the liquid to be treated containing nitrate ions to be treated is passed through the cathode chamber 6 as indicated by arrow A.
Note that FIG. 1 does not show other facilities in which the liquid to be treated (culture liquid) circulates. However, when operating the denitrification tank 1, other necessary equipment apparent to those skilled in the art is used.

The denitrification tank 1 is treated by intermittently passing the liquid to be treated so as to have an anaerobic atmosphere and is treated by a combination of a biological treatment method and an electrochemical method. That is, the denitrification reaction of nitrate nitrogen is performed while charging between the cathode 2 and the anode 3 to generate electrolytic hydrogen from the electrode and take it into the denitrifying bacterium, or while directly donating electrons from the electrode to the denitrifying bacterium. Let it be done. The denitrification reaction is performed at the cathode 2.

Here, in this embodiment, the blower 10 is provided. The blower 10 is a characteristic part of this embodiment. The blower 10 is time-controlled by a timer 11. In the denitrification tank 1, nitrogen is produced as a product in association with the denitrification reaction of nitrate nitrogen, and bubbles thereof are produced in the carrier 4. It is presumed that these bubbles hinder the contact between the denitrifying bacteria and the liquid to be treated, and hinder the treatment of nitrate nitrogen. In the present embodiment, the timer 11 controls the time interval as appropriate so that the blower 1
0 is operated at a time interval, and air is sent to the denitrification tank 1 from a blowout port 12 provided below the carrier 4. As a result, the inside of the denitrification tank 1 is forcibly washed with air (air washing) to remove air bubbles. The time interval is determined by keeping both the outlet nitrogen concentration at a good level and preventing denitrifying bacteria from separating from the carrier.

FIG. 2 shows another embodiment of the denitrification tank according to the present invention. In this embodiment, a pressure gauge 21 is provided as a pressure detecting means, and the pressure detected by this pressure gauge 21 is monitored. The pressure to be detected is upstream of the carrier 4. When the bubbles are accumulated in the carrier 4, the resistance is increased in terms of fluid and the pressure is increased. This increased pressure information is sent to the controller 22. The pressure at which the blower 23 works is set in the controller 22 in advance. When the pressure becomes equal to or higher than this set pressure, the blower 23 works to send the air into the denitrification tank 1 through the outlet 24 provided below the carrier 4. by this,
The carrier 4 is washed with air. In this embodiment, by performing the air washing while monitoring the pressure, it becomes unnecessary to perform the air washing unnecessarily. This can prevent denitrifying bacteria from peeling off.

FIG. 3 shows still another embodiment of the denitrification tank according to the present invention. In this embodiment, a nitrate nitrogen sensor 31 is provided as a nitrate nitrogen detecting means, and the concentration of nitrate nitrogen detected by the nitrate nitrogen sensor 31 is monitored. The concentration to be detected is downstream of the carrier 4. When bubbles are accumulated in the carrier 4, the concentration of nitrate nitrogen increases. This increased density information is sent to the controller 32. The concentration at which the blower 33 works is set in the controller 32 in advance. When the concentration becomes equal to or higher than the set concentration, the blower 33 works and sends air into the denitrification tank 1 through the blowout port 34 provided below the carrier 4. In this way, the carrier 4 is washed with air. In this embodiment, by performing the air washing while monitoring the concentration of nitrate nitrogen, it becomes unnecessary to perform the air washing unnecessarily. This can prevent denitrifying bacteria from peeling off.

FIG. 4 shows still another embodiment of the denitrification tank according to the present invention. In this embodiment, the space between the cathode 2 and the anode 3 is narrowed and the width of the cathode chamber 6 is narrowed. Further, the diaphragm 5 is made of a material that is cheap as air, for example, a plastic net. This prevents bubbles from accumulating.

Further, in the present invention, it is also included as an embodiment that the bubbles are not retained by increasing the flow velocity of the liquid to be treated. Normal flow velocity is 0.1 to 1 m
/ Hour, but 5 to 50 times that speed. 5
m / hour or around that is preferable.

Further, the present invention also includes, as its embodiment, an ultrasonic wave generator for applying ultrasonic waves to the denitrification tank as means for removing bubbles. Such an ultrasonic generator is also provided with a timer, a pressure detecting means, or a detecting means for nitrate nitrogen in the same manner as the above-mentioned air washing with a blower so as not to work excessively and to avoid denitrifying bacteria from peeling. You can

[0018]

As is apparent from the above, according to the present invention, there is provided a denitrification device capable of maintaining a good operating condition even when continuously operated.

[Brief description of drawings]

FIG. 1 is a conceptual cross-sectional view illustrating an embodiment of a denitrification tank according to the present invention.

FIG. 2 is a conceptual cross-sectional view illustrating another embodiment of the denitrification tank according to the present invention.

FIG. 3 is a conceptual cross-sectional view illustrating still another embodiment of the denitrification tank according to the present invention.

FIG. 4 is a conceptual cross-sectional view explaining still another embodiment of the denitrification tank according to the present invention.

[Explanation of symbols]

1 denitrification tank 2 cathode 3 anode 4 carriers 5 diaphragm 6 Cathode chamber 7 Anode chamber 10, 23, 33 blowers 11 timer 21 pressure gauge 22, 32 controller 31 Nitrate nitrogen sensor

Claims (6)

[Claims] 1. A denitrification apparatus using denitrifying bacteria, comprising a carrier for holding the denitrifying bacteria, and provided with a bubble removing means for removing bubbles generated along with the progress of the denitrifying reaction. Denitrification device. 2. The denitrification device according to claim 1, wherein the bubble removing means is an air cleaning device for cleaning the carrier with air. 3. The denitrification device according to claim 1, wherein the bubble removing means is an ultrasonic wave generation device for applying ultrasonic waves to the denitrification device. 4. The denitrification device according to claim 1, wherein a pressure detecting means is installed, and a fluid resistance state of the carrier is monitored to operate the bubble removing means. 5. The denitrification device according to claim 1, wherein a nitrate nitrogen detecting means is installed, and the concentration of nitrate nitrogen is monitored to operate the bubble removing means. 6. A denitrification apparatus using a denitrifying bacterium, comprising a carrier for holding the denitrifying bacterium, and providing a means for accelerating the flow rate of a liquid to be treated flowing through the carrier. .