JPH09276892A - Method for anaerobic biological treatment of organic waste water and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an anaerobic biological treatment apparatus capable of holding highly conc. anaerobic sludge without scaling up the apparatus and capable of continuing stable treatment while enhancing the maintenance properties of the apparatus. SOLUTION: An anaerobic tank 1 is packed with anaerobic sludge to which a magnetic powder is added and raw water is introduced into the anaerobic tank from a raw water inflow pipe 4 by an inflow pump 3 to treat a suspended component by anaerobic sludge. Anaerobic sludge and treated water after treatment are separated by the magnetic separator 20 arranged in the tank and treated water is taken out of the tank.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and apparatus for treating anaerobic organisms of organic wastewater.

[0002]

2. Description of the Related Art Conventionally, many methods have been devised in anaerobic biological treatment methods in which sludge is kept at a high concentration in a reaction tank to prevent outflow of methanogenic bacteria and to carry out high load operation. Examples of the method include an anaerobic sludge bed method, an anaerobic fluidized bed method, and an anaerobic fixed bed method.

As shown in FIG. 6, the anaerobic fluidized bed method is a method in which a carrier is added to an anaerobic biological treatment tank 1 and a high concentration of anaerobic sludge 2 is held around the carrier, and high load operation is possible. Is. The smaller the carrier, the larger the specific surface area of the carrier, and the greater the sludge concentration that can be retained. The raw water is introduced from the lower part of the anaerobic tank by the inflow pump 3 from the raw water inflow pipe 4 through the raw water supply nozzle 5 in an upward flow. The raw water and circulating water that have flowed in rise while the anaerobic sludge containing the carrier in the tank is being developed in the tank, while the anaerobic sludge treats the pollutant components. The anaerobic sludge reaching the upper part of the tank is solid-liquid separated in the solid-liquid separation space 15, and a part of the treated water is circulated by the inflow pump 3 and circulated from the lower part of the reaction tank into the reaction tank.

On the other hand, as shown in FIG. 7, a magnetic powder is added to and retained in the activated sludge, and the activated sludge containing the magnetic powder is introduced into the magnetic separation tank 13 provided at the outlet side of the activated sludge tank 16 by magnetism. A method has been proposed in which solid-liquid separation is forcibly performed and the separated activated sludge is returned to the activated sludge tank 16 (JP-A-7-80491).

[0005]

However, the anaerobic fluidized bed method has a problem in the solid-liquid separation step of the first anaerobic sludge and the treated water. That is, a large space for solid-liquid separation is required on the space for developing the carrier, and the size of the apparatus becomes large.

The reason is that in the conventional anaerobic fluidized bed method,
This is because solid-liquid separation of anaerobic sludge and treated water is performed by the difference in specific gravity. When the treatment device is in a steady operation, anaerobic sludge adheres to the carrier, contains gas generated by the treatment reaction inside the sludge, and the apparent specific gravity changes. as a result,
Separation of anaerobic sludge and treated water becomes difficult gradually, and the distance from entering the solid-liquid separation space to solid-liquid separation gradually increases. Therefore, when designing the apparatus, a solid-liquid separation space with a margin should be set.

Secondly, there is a problem that the maintenance frequency of the pump for circulating the circulating water in the tank is high. The reason is the first
The reason is that the solid-liquid separation is performed by the difference in specific gravity. That is, the anaerobic sludge having a smaller apparent specific gravity is finally not subjected to solid-liquid separation and flows into the circulation path together with the treated water, and the carrier in the anaerobic sludge damages the inflow pump.

Therefore, the solid-liquid separation space can be made smaller by applying the solid-liquid separation method by magnetic separation disclosed in Japanese Patent Laid-Open No. 7-80491. However, the second problem is not solved. The reason is that the anaerobic sludge-containing water containing magnetic powder to the magnetic separation tank must be sent by water and the separated sludge that has been magnetically separated must be returned to the anaerobic tank by a pump.

The third problem is that the anaerobic treatment is not stable. The reason is that the anaerobic tank and the magnetic separation tank are required, which complicates the tank structure,
This is because the airtightness required for anaerobic treatment cannot be maintained well, and the influence of oxygen in the air is exerted.

An object of the present invention is to provide a method and apparatus for treating anaerobic organisms, which can retain a high concentration of anaerobic sludge without requiring a large-sized apparatus and can continue stable treatment while improving maintainability of the apparatus. Is to provide.

[0011]

In order to solve the above problems, the present invention provides a method for treating anaerobic organisms of organic wastewater, comprising:
A step of adding magnetic powder to the anaerobic sludge and holding it, a step of treating the water to be treated with the anaerobic sludge inside the anaerobic tank, and a step of magnetically separating the anaerobic sludge and the treated water by a magnetic separation device provided inside the anaerobic tank. And a step of returning the magnetically separated anaerobic sludge to the anaerobic tank.

In the present invention, the anaerobic sludge and the magnetic powder are integrated and the anaerobic sludge itself has magnetism in the step of adding the magnetic powder to the anaerobic sludge and retaining it. here,
As the material of the magnetic powder, sand iron, ferrite, magnetite and the like can be used, but magnetite / ferrite is preferable in consideration of dissolution in water. If the particle size of the magnetic powder is too large, the spread of the anaerobic sludge becomes worse. Therefore, a minute one having a size of 10 μm or less is used. The amount of magnetic powder added to sludge depends on the sludge concentration, but is added at a concentration of 50% to 150% of the sludge concentration.

In the step of magnetically separating the anaerobic sludge and the treated water by the magnetic separation device provided inside the anaerobic tank, the anaerobic sludge that has become magnetic in the previous step is forcibly separated from the treated water by the magnetic force. To be separated. As a method of supplying magnetic force used in the magnetic separation device, there is a method of using an electromagnet with an exciting coil or a permanent magnet. Since the magnetic separation device can efficiently separate the anaerobic sludge and the treated water in a limited space, the device can be downsized.

In the step of returning the magnetically separated anaerobic sludge to the anaerobic tank, the anaerobic sludge scraped by the scraper is returned to a portion in the anaerobic tank that is not affected by the magnetic force, so that the anaerobic sludge hardly flows into the treated water. . Therefore, the anaerobic sludge concentration in the anaerobic tank can be kept high.

Through the above steps, the concentration of anaerobic sludge in the anaerobic tank is always kept high, and since the tank structure does not become complicated, airtightness is maintained and stable treatment can be obtained.

Further, according to the present invention, an anaerobic biological treatment tank filled with anaerobic sludge to which magnetic powder is added, a mechanism for introducing water to be treated into the treatment tank, and the treated water is discharged from the treatment tank. An anaerobic biological treatment apparatus for organic wastewater is obtained which has a mechanism for controlling the effluent and a magnetic separation apparatus which is disposed in the treatment tank and separates anaerobic sludge and treated water.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a first embodiment of a method and apparatus for treating anaerobic organisms of organic wastewater according to the present invention. FIG. 2 is a partial schematic view of a part of the magnetic separation device 20 of FIG. 1 as seen from above. Reference numeral 1 is an anaerobic biological treatment tank. First, anaerobic sludge and, for example, powder of ferrite of magnetic material are put therein to form an anaerobic sludge 2 containing magnetic powder. Raw water (water to be treated) and circulating water are introduced from the lower part of the anaerobic tank by an inflow pump 3 in an upward flow from a raw water inflow pipe 4 through a raw water supply nozzle 5. The raw water and the circulating water that have flowed in rise while the anaerobic sludge containing the magnetic substance in the tank is being developed in the tank, while the anaerobic sludge treats the pollutant components. The anaerobic sludge reaching the upper part of the tank is introduced into the magnetic separation device 20. The magnetic separation device 20 in FIG. 1 separates anaerobic sludge and treated water by a magnet 7 embedded in a rotating body 6. A plurality of rotating bodies 6 are mounted in parallel on a rotating shaft 8 and rotated by a motor 9. The anaerobic sludge close to the rotating body 6 is attracted by the magnetic force of the magnet 7 and adheres to the rotating body 6. In this way, solid-liquid separation of anaerobic sludge and treated water is performed. The magnetically separated anaerobic sludge is scraped from the magnet by the scraper 10 and returned to the treatment tank.

The treated water that has been solid-liquid separated is discharged from the treated water outlet 11 to the outside of the system. A part of the treated water is introduced into the inflow pump 3 through the circulating water pipe 12 and circulates in the treating tank again.

FIG. 3 is a schematic diagram of a second embodiment of the method and apparatus for anaerobic treatment of organic wastewater according to the present invention. FIG. 4 is a partial schematic view of the magnetic separation device portion of FIG. 3 seen from above. 1 is an anaerobic biological treatment tank,
The inside is filled with anaerobic sludge 2 containing a magnetic material. The raw water and the circulating water are introduced from the lower part of the anaerobic tank by the inflow pump 3 from the raw water inflow pipe 4 through the raw water supply nozzle 5 in an upward flow. The raw water and the circulating water that have flowed in rise while the anaerobic sludge containing the magnetic substance in the tank is being developed in the tank, while the anaerobic sludge treats the pollutant components.
The anaerobic sludge reaching the upper part of the tank is introduced into the magnetic separation layer 13. The magnetic separation device in FIG. 4 separates the anaerobic sludge and the treated water by the magnet 7 attached to the magnetic separation layer 13 installed so as to sandwich the rotating body 6. A scraper 10 is attached to the rotating body 6, and the magnetic sludge adhering to the inner surface of the magnetic separation layer is scraped off by the rotation of the rotating body and returned to the tank. A plurality of rotating bodies are mounted in parallel on the rotating shaft 8 and rotated by a motor 9. The treated water that has been solid-liquid separated is discharged from the treated water outlet 11 to the outside of the system. A part of the treated water is introduced into the inflow pump 3 through the circulating water pipe 12 and circulates in the treating tank again.

FIG. 5 is a schematic diagram of a third embodiment of the method and apparatus for treating anaerobic organisms of organic wastewater according to the present invention. An anaerobic biological treatment tank 1 is filled with an anaerobic sludge 2 containing a magnetic material inside. The raw water and the circulating water are introduced from the lower part of the anaerobic tank by the inflow pump 3 from the raw water inflow pipe 4 through the raw water supply nozzle 5 in an upward flow. The inflowing raw water and circulating water cause the anaerobic sludge containing the magnetic substance in the tank to develop in the tank. The magnetic separation device in FIG. 5 is a device which is located on the side of the tank and which separates the anaerobic sludge from the treated water by passing the treated water through the discharge pipe 14 in which the magnet 7 is embedded. The solid-liquid separated anaerobic sludge is
It accumulates on the inner surface of the exhaust pipe 14, and magnetic separation becomes impossible after a certain period of time. Before this happens, the piston-shaped scraper 10 is inserted into the discharge pipe and the anaerobic sludge accumulated on the inner surface is pushed back into the tank. At least two magnetic separators are installed in the reaction tank, and they operate alternately at regular intervals. The treated water does not pass through the discharge pipe into which the scraper is fed, but during that time, the treated water is discharged from another discharge pipe that does not scrape sludge.

The treated water which has been solid-liquid separated is discharged from the treated water outlet 11 to the outside of the system. A part of the treated water is introduced into the inflow pump 3 through the circulating water pipe 12 and circulates in the treating tank again.

In the state where the treatment is continuously carried out in the steps of the embodiment as described above, the anaerobic sludge containing the magnetic powder is magnetically separated by the magnetic force of the magnet and returns to the tank. Therefore, the anaerobic sludge in the tank can be maintained at a high concentration and can be operated under a high load. In addition, S in treated water
S (suspended solid) is kept low. As an example, Table 1 shows data when a processing test is performed in the device according to the first embodiment.

[0023]

[Table 1]

[0024]

According to the present invention, the following effects can be exhibited. The first effect is that the anaerobic sludge in the anaerobic biological treatment tank can be maintained at a high concentration and can be operated under a high load. The reason is that the anaerobic sludge containing the magnetic powder is forcibly solid-liquid separated by magnetic force and the separated anaerobic sludge is returned to the treatment tank, so that the anaerobic sludge in the anaerobic tank is always maintained.

The second effect is that the device can be miniaturized. The reason is that solid-liquid separation is performed by the magnetic separation device, so that the separation is reliable, and there is no need to allow a space as in the case of gravity separation.

The third effect is that the maintenance frequency of the pump for circulating the circulating water can be reduced. The reason is that solid-liquid separation is reliably performed by magnetic separation, so that anaerobic sludge containing the carrier does not flow out into the treated water, and the carrier does not flow into the circulation system path, thus damaging the inflow pump. This is because there is no

[Brief description of drawings]

FIG. 1 is a schematic view showing a first embodiment of a method and an apparatus for treating anaerobic organisms of organic wastewater according to the present invention.

FIG. 2 is a partial schematic view of the magnetic separation device portion of FIG. 1 seen from above.

FIG. 3 is a schematic diagram showing a second embodiment of a method and apparatus for treating organic wastewater with a magnetic organism according to the present invention.

FIG. 4 is a partial schematic view of the magnetic separation device portion of FIG. 3 as seen from above.

FIG. 5 is a schematic view showing an example of a method and an apparatus for treating anaerobic organisms of organic wastewater according to the present invention.

FIG. 6 is a schematic diagram showing an example of a conventional method and apparatus for treating anaerobic organisms from organic waste water.

FIG. 7 is a schematic configuration diagram showing an example of a conventional method for treating organic wastewater with aerobic organisms.

[Explanation of symbols]

 1 Anaerobic biological treatment tank 2 Anaerobic sludge 3 Inflow pump 4 Raw water inflow pipe 5 Raw water supply nozzle 6 Rotor 7 Magnet 8 Rotating shaft 9 Motor 10 Scraper 11 Treated water outlet 12 Circulating water pipe 13 Magnetic separation tank 14 Discharge pipe 15 Solid Liquid separation space 16 Activated sludge tank

Claims (2)

[Claims] 1. A step of adding magnetic powder to anaerobic sludge and holding it, a step of treating water to be treated with the anaerobic sludge inside the anaerobic tank, and a step of separating the anaerobic sludge and the treated water by a magnetic separation device provided inside the anaerobic tank. An anaerobic biological treatment method for organic wastewater, comprising a step of magnetically separating and a step of returning the magnetically separated anaerobic sludge to an anaerobic tank. 2. An anaerobic biological treatment tank filled with anaerobic sludge to which magnetic powder is added, a mechanism for introducing water to be treated into the treatment tank, a mechanism for discharging treated water from the treatment tank, and the treatment. An anaerobic biological treatment device for organic wastewater, which is provided in a tank and has a magnetic separation device for separating anaerobic sludge and treated water.