JPH0747387A - Anaerobic device for water treatment and method therefor - Google Patents

Abstract

PURPOSE:To surely execute compaction in an anaerobic reaction vessel, to prevent the carry over from the anaerobic reaction vessel and to accurately execute a water treatment. CONSTITUTION:This device is provided with the anaerobic reaction vessel 2 purifying a waste water by the anaerobic microorganisms sticking on the surface of a carrier and a surplus sludge concentrating vessel 17 in which the surplus microorganisms in the anaerobic reaction vessel 2 is discharged together with the carrier and concentrated. The carrier in a carrier tank 13 is introduced into the anaerobic reaction vessel 2 by an introducing means 14 to increase the apparent specific gravity of the sludge. In this way, the carry-over is prevented surely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anaerobic water treatment device for purifying organic wastewater such as industrial wastewater by the action of anaerobic microorganisms and a water treatment method thereof.

[0002]

2. Description of the Related Art An anaerobic water treatment method using methane-fermenting bacteria, which are anaerobic microorganisms, produces less excess sludge than a activated sludge method that uses aerobic bacteria, and aeration There are advantages such as not requiring the power of, and being able to recover energy because methane gas is generated. However, on the other hand, there is a drawback that the decomposition rate of organic substances is slow and the processing time becomes long.

In order to improve such problems, an anaerobic water treatment device has been developed in which the concentration of methane-fermenting bacteria is increased and the treatment time is shortened. As such an anaerobic water treatment device, a fluidized bed type water treatment device in which methane-fermenting bacteria are adhered and immobilized on the surface of a carrier, or a biological bed type (UAS) in which methane-fermenting bacteria are self-granulated (granulated) is used.
B type) water treatment devices, which are put into practical use mainly for highly concentrated wastewater such as industrial wastewater.

FIG. 3 is a block diagram of a conventional biological bed type (UASB type) anaerobic water treatment apparatus. In FIG. 3, wastewater is introduced from the lower part of the anaerobic reaction tank (anaerobic reactor) 2 from the raw water pipe 25 by the raw water pump 1. The inside of the anaerobic reactor 2 is divided into a lower reaction section 3 and an upper clarification section 5, and in the reaction section 3, granules 4 which are methane-fermenting bacterial granules are flowing. While the wastewater flows upward in the reaction section 3, organic matter in the wastewater comes into contact with methane-fermenting bacteria and is decomposed, and a fermentation gas containing methane gas and carbon dioxide gas as main components is produced.

After that, the fermentation gas rises in the reaction section 3 and the clarification section 5 formed above the reaction section 3, and the anaerobic reactor 2
Is temporarily stored in the gas holder 7 via the fermentation gas pipeline 6 from above. Next, the fermentation gas in the gas holder 7 is effectively used as fuel for a gas boiler or the like. On the other hand, the treated water purified in the anaerobic reactor 2 is the anaerobic reactor 2
Overflows from the upper part of the system and is drawn out of the system through the treated water pipe line 10.

[0006] During such treatment, the methane-fermenting bacteria assimilate organic matter in the wastewater and grow. Therefore, the excess sludge in the anaerobic reactor 2 is extracted from the extraction line 16 and flows into the excess sludge thickening tank 17. Next, the excess sludge is gravity-concentrated in the excess sludge thickening tank 17, and is withdrawn from the excess sludge thickening tank 17 via the concentrated sludge pulling-out conduit 18 at the lower part, and the excess sludge is then subjected to a treatment such as a dehydration treatment.

An overflow pipe line is provided above the excess sludge thickening tank 17, and the desorbed liquid in the excess sludge thickening tank 17 overflowing from the overflow pipe 19 is temporarily stored in a desorbed liquid tank 20. Since the desorbed liquid in the desorbed liquid tank 20 cannot be discharged into the river due to its water quality, it is returned to the anaerobic reactor 2 by the desorbed liquid pump 21. If a post-treatment device is installed, the desorbed liquid in the desorption liquid tank 20 may be transferred to the post-treatment device.

[0008]

In the biological bed type (UASB type) water treatment apparatus as described above, floating methane-fermenting bacteria (seed sludge) are charged into the anaerobic reactor 2 at the time of start-up, and the granules are granulated. Start forming. At that time, sludge having poor sedimentation property carries over from the anaerobic reactor 22 and flows out of the system. The sludge having a good sedimentation property is accumulated and consolidated in the lower part of the anaerobic reactor 2, and is gradually granulated by being subjected to a gentle rolling action by the fermentation gas generated. At this time, it is important to promote active growth of methane-fermenting bacteria, and for granulation, 0.6 kg-COD / kg-VSS /
More than a day load is required.

By the way, there is a drawback that the above-mentioned granulation requires a long period of half a year to one year. In addition, the mechanism of granulation is not fully understood, and depending on the characteristics of wastewater and the conditions of granulation, granulation of seed sludge may not occur.

In order to improve such a state, there is a method in which a fine carrier is charged into the anaerobic reaction tank 2 at the initial stage of granulation, but when the sludge is granulated, the operation is continued. However, the amount of sludge in the anaerobic reaction tank 2 increases, and it becomes necessary to extract excess sludge. In this case, since the carrier is contained in the sludge, the ratio of the carrier amount in the sludge in the anaerobic reaction tank 2 is reduced, the apparent specific gravity of the sludge is reduced, and carryover easily occurs.

The present invention has been made in consideration of the above points, and an anaerobic water treatment apparatus and its water treatment capable of maintaining a constant amount of carrier in sludge for stable operation for a long time. The purpose is to provide a method.

[0012]

The invention according to claim 1 is
An anaerobic reaction tank that purifies wastewater by anaerobic microorganisms attached to the surface of the carrier, and an excess sludge concentrating tank that is connected to this anaerobic reaction tank and the excess microorganisms in the anaerobic reaction tank are extracted together with the carrier and concentrated. An anaerobic water treatment apparatus comprising: a carrier tank containing a carrier; and a charging means for intermittently charging the carrier in the carrier tank into the anaerobic reaction tank.

According to the second aspect of the present invention, a step of purifying waste water by microorganisms adhering to the surface of the carrier in the anaerobic reaction tank, and a surplus sludge concentrating tank by extracting the surplus microorganisms in the anaerobic reaction tank together with the carrier. The method for treating anaerobic water, comprising: a step of concentrating the carrier in a carrier tank; and a step of charging the carrier stored in the carrier tank into the anaerobic reaction tank with a charging time of 60 minutes or less. Is.

[0014]

According to the invention as set forth in claim 1, the wastewater flowing into the anaerobic reaction tank is purified by the anaerobic microorganisms adhering to the surface of the carrier, and the surplus microorganisms in the anaerobic reaction tank are extracted together with the carrier to generate an excess. It is concentrated in the sludge thickening tank. During this period, the carrier stored in the carrier tank is intermittently charged into the anaerobic reaction tank by the charging means, and the apparent specific gravity of sludge in the anaerobic reaction tank is increased.

According to the second aspect of the present invention, the carrier stored in the carrier tank is charged into the anaerobic reaction tank by a charging means in a charging time of 10 to 60 minutes, whereby the granules in the anaerobic reaction tank are granulated. The destruction of the cable is prevented.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of the present invention.

In FIG. 1, the anaerobic water treatment device is drawn into an anaerobic reactor 2 and an anaerobic reactor 2, which are separated into a lower reaction section 3 for purifying wastewater by anaerobic microorganisms and an upper clarification section 5. It is provided with a surplus sludge tank 17 which is connected via a pipe 16 and in which the excess microorganisms in the anaerobic reactor 2 are extracted together with the carrier and concentrated.

The anaerobic reactor 2 has a raw water pump 1
Therefore, the wastewater is allowed to flow in through the raw water pipe 25, and the carrier stored in the carrier tank 13 is allowed to flow into the anaerobic reactor 2 by the carrier pump 14 through the carrier feeding pipe line 15. Has become.

Further, the anaerobic reactor 2 has an overflow pipe 8
The treated water tank 9 is connected via the so that the treated water in the anaerobic reactor 2 flows into the treated water tank 9. Further, the treated water in the treated water tank 9 is then treated with the treated water pipeline 10.
Is released to the outside of the system via. A part of the treated water in the treated water tank 9 is returned to the anaerobic reactor 2 by the circulation pump 12 via the circulation pipe line 11.

Next, the operation of this embodiment having such a configuration will be described.

In FIG. 1, the wastewater flows from the raw water pipe 25 into the lower part of the reaction tank (anaerobic reactor) 2 by the raw water pump 1, and flows into the upper part of the anaerobic reactor 2 in an upward flow.
During this time, the anaerobic microorganisms attached to the surface of the carrier (granules 4 made of methane-fermenting bacteria are flowing in the reaction part 3 in the anaerobic reactor 2, and the organic substances in the wastewater are decomposed by the granules 4. Wastewater is purified.

The purified wastewater becomes treated water from the clarification section 5 in the upper part of the anaerobic reactor 2 and flows into the treated water tank 9 through the overflow pipe line 8. The treated water that overflows from the treated water tank 9 is taken out of the system through the treated water pipeline 10 and discharged to a river or sewage, or transferred to a post-treatment process. A part of the treated water in the treated water tank 9 is returned by the circulation pump 12 to the lower portion of the reactor 2 via the circulation water passage 11.

On the other hand, the fermentation gas produced by the decomposition of the organic substances in the anaerobic reactor 2 is once stored in the gas holder 7 via the fermentation gas pipe 6, and is effectively used as a fuel for a gas boiler or the like.

The anaerobic microorganisms of the granule 4 decompose the organic matter in the wastewater to produce a fermentation gas, and at the same time, assimilate the organic matter and proliferate. The anaerobic microorganisms thus proliferated are withdrawn from the anaerobic reactor 2 as excess sludge from the withdrawal pipeline 16 to the excess sludge concentration tank 17. In this case, since the carrier is contained in the excess sludge, the ratio of the carrier amount in the sludge (aggregate of granules 4) in the anaerobic reactor 2 decreases, and the apparent specific gravity of the sludge decreases.

When the apparent specific gravity of the sludge is reduced in this way, the carrier stored by being mixed with water in the carrier tank 13 is introduced into the anaerobic reactor 2 by the carrier pump 14 via the carrier introducing pipe 15. It is put in in a short time.

In this case, the reason why the charging is carried out in a short time is because the granules 4 formed in the anaerobic reactor 2 are not destroyed by the charging for a long time.
It is preferably 0 minutes or less, for example, 10 to 60 minutes.

According to this embodiment, the carrier charged in the anaerobic reactor 2 adheres to the granules 4 floating in the reaction section 3 in the reactor 2 to increase the apparent specific gravity of sludge, so that the reaction The sludge can be consolidated in the section 3 as in the start-up, and the carryover of the sludge from the anaerobic reactor 2 can be prevented.

Next, an experimental example of the present invention will be described.

Using the anaerobic water treatment system shown in FIG.
A wastewater treatment experiment was conducted. The wastewater used here is food industry wastewater, and the composition of the wastewater is shown in Table 1.

[0030]

[Table 1] The anaerobic reactor 2 used in the experiment is made of transparent vinyl chloride having a reaction part volume of 10 L, and silica sand having a diameter of 150 μm or less (specific gravity 2.6) is used as a carrier in the anaerobic reactor 2 with a reaction part volume of 6 L. It was thrown in so that it might become%. The seed sludge to be attached to the carrier was digested sludge from an urban sewage treatment plant, and was prepared so that the reaction part sludge concentration was 5000 mg-VSS / L. Further, the rising speed in the reactor 2 was adjusted to be 1.2 m / H.

The reason why silica sand having a specific gravity of 2.6 and having a particle size of 150 μm or less is used as the carrier is as follows.
That is, when the diameter is 150 μm or more, the amount of anaerobic microorganisms attached to the surface of silica sand decreases. It has been confirmed that sludge overflows from the reactor 2 when the specific gravity is small (for example, when the specific gravity is 1.1 or less). Therefore, the shape of silica sand as a carrier is set as described above.

Next, the results of this experiment are shown in FIG. Figure 2
It is a figure which shows SS density | concentration of the treated water of a stable operation period. As shown in FIG. 2, S of the treated water due to the growth of anaerobic microorganisms
The S concentration increases. In this case, the treated water SS is 200
By adding the carrier for 10 minutes when the amount reached ˜500 mg / L, the treated water SS decreased to the same level as the initial stage of the experiment. From this result, it was found that the addition of the carrier prevents the SS concentration of the treated water from decreasing, that is, the carryover of microorganisms.

[0033]

As described above, according to the present invention as set forth in claim 1, the carrier is intermittently charged into the anaerobic reaction tank by the charging means so that the apparent specific gravity in the anaerobic reaction tank is increased. By increasing the number, the sludge can be surely consolidated. Therefore, carryover of sludge from the anaerobic reaction tank can be reliably prevented.

According to the second aspect of the present invention, the carrier is charged into the anaerobic reaction tank by the charging means in a charging time of 60 minutes or less to prevent the granules in the anaerobic reaction tank from being damaged. You can Therefore, water treatment can be performed accurately.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing an anaerobic water treatment device according to the present invention.

FIG. 2 is a diagram showing the results of an experimental example of the present invention.

FIG. 3 is a schematic system diagram showing a conventional anaerobic water treatment device.

[Explanation of symbols]

 2 Anaerobic reactor 4 Granule 13 Carrier tank 14 Carrier pump 17 Excess sludge thickener

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mamoru Mamoru 1 TOSHIBA-CHO, Fuchu-shi, Tokyo Inside the Toshiba Fuchu factory

Claims (2)

[Claims] 1. An anaerobic reaction tank for purifying wastewater by anaerobic microorganisms attached to the surface of a carrier, and an anaerobic reaction tank connected to the anaerobic reaction tank, and excess microorganisms in the anaerobic reaction tank are extracted together with the carrier and concentrated. An anaerobic water treatment characterized by comprising: an excess sludge thickening tank, a carrier tank containing the carrier, and a charging means for intermittently charging the carrier in the carrier tank into the anaerobic reaction tank. apparatus. 2. A step of purifying wastewater by microorganisms adhering to the surface of a carrier in an anaerobic reaction tank; a step of extracting surplus microorganisms in the anaerobic reaction tank together with the carrier and concentrating them in a surplus sludge concentrating tank. An anaerobic water treatment method comprising: a step of charging the carrier stored in the carrier tank into the anaerobic reaction tank by a charging means at a charging time of 60 minutes or less.