JPH0459040B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to an anaerobic wastewater treatment device, and more specifically to an anaerobic treatment device for wastewater containing solid organic matter.

<<Prior Art>> As is well known, methods for treating organic wastewater include an aerobic treatment method typified by an activated sludge method and an anaerobic treatment method typified by a methane fermentation method.

Anaerobic treatment method is different from aerobic treatment method.
It has features such as low power consumption, the ability to convert organic matter into methane gas, the ability to reduce and stabilize sludge, and the ability to quickly kill pathogenic microorganisms and parasite eggs. With the progress of basic research on organic wastewater treatment, these features are being utilized to treat a wide range of organic wastewater.

This type of anaerobic treatment method has traditionally been
The anaerobic activated sludge method, anaerobic bed method, anaerobic fluidized bed method, and anaerobic sludge bed method are known.

However, such conventional anaerobic treatment methods are particularly difficult for organic wastewater that contains about 1 to 10% solid organic matter, such as wastewater from food factories, starch factories, and kitchens. In both cases, there were problems explained below.

<<Problems to be solved by the invention>> In other words, when attempting to treat wastewater containing solid organic matter using the methods of and, it takes 15 days to process, ie, digest, the solid organic matter.
Since it takes ~30 days, a huge amount of equipment is required to treat the entire wastewater.

In addition, if you try to treat it using the method described above, solid organic matter will adhere to the surface or gaps of the flooring material.
It blocks the floor, making it impossible to process.

Furthermore, if you try to treat the solid organic matter using the method described above, anaerobic bacteria will adhere to the surface of the solid organic matter and this will flow out of the treatment tank, making treatment impossible in the same manner as above. There's a problem.

This kind of problem can be solved by removing solid organic matter from wastewater, but this solution requires a separation device to be installed upstream of the anaerobic treatment device, which increases the size of the treatment equipment. Therefore, the structure becomes complicated.

This invention was made in view of these conventional problems, and its purpose is to develop a compact system that can decompose wastewater containing solid organic matter anaerobically without having to separate and remove it in advance. An object of the present invention is to provide an anaerobic wastewater treatment device.

<<Means for Solving the Problems>> In order to achieve the above object, the present invention provides an anaerobic treatment device for wastewater containing solid organic matter.
A first anaerobic treatment tank of a downward flow type, which is provided with an anaerobic bed in which the treated raw water containing the solid organic matter is supplied from above and is capable of settling the solid organic matter, and a lower part of the first anaerobic treatment tank is connected to the first anaerobic treatment tank. an upflow type second anaerobic treatment tank communicating through a passage and having an anaerobic bed to which the primary treated water treated in the first anaerobic treatment tank is supplied from below, and the first anaerobic treatment tank. A sludge tank was formed directly below the anaerobic bed and below the communication path to treat the settled solid organic matter anaerobically in a restrained state.

<<Operation>> According to the anaerobic wastewater treatment apparatus having the above configuration, the anaerobic bed of the downward flow type first anaerobic treatment tank to which treated raw water containing solid organic matter is supplied is capable of sedimentation of solid organic matter. This prevents it from becoming clogged with organic matter.

In addition, solid organic matter is separated from the treated raw water or primary treated water by settling in the downward flow type first anaerobic treatment tank, and only the solid organic matter is then anaerobically treated in a confined state in the sludge tank. Therefore, the sludge tank is much smaller than when the entire treated raw water is treated anaerobically, and the entire treatment equipment does not become large.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of an anaerobic wastewater treatment apparatus according to the present invention.

The treatment device shown in the figure is for anaerobically treating raw water A containing about 1 to 10% of solid organic matter, and has vertically long first and second anaerobic treatment tanks 10 and 1.
It is roughly composed of 2.

A supply port 14 for the treated raw water A is provided in the upper part of the first anaerobic treatment tank 10, and the treated raw water A supplied through the supply port 14 at an intermediate position inside the tank 10 is supplied vertically from above to below. An anaerobic bed 16 is installed that flows downward, forming a downward flow type anaerobic treatment tank.

The anaerobic floor 16 is made of materials such as non-woven synthetic fibers, needle-punched chemical fibers, fibrous activated carbon, plate-shaped glass wool, rock wool, and foamed fireclay that are processed into a flat or honeycomb shape. A space of several tens of millimeters is provided between each material so that the solid organic matter contained in the treated raw water A can settle.

Anaerobic bacteria are attached to the surface of this anaerobic bed 16, and while the treated raw water A flows down this, water-soluble organic matter in the raw water A is anaerobically decomposed by the anaerobic bacteria. .

The downward flow type first anaerobic treatment tank 10 and second anaerobic treatment tank 12 are communicated with each other via a communication passage 18 below the anaerobic bed 16, and the raw water A treated in the anaerobic bed 16 is Primary treated water B is supplied to the second anaerobic treatment tank 12 from below.

Inside the second anaerobic treatment tank 12, there is an anaerobic bed 20 in which the primary treated water B rises vertically from below to above.
is installed at an intermediate position, and an outlet 22 for the treated water C is provided above it.
It constitutes an upward flow type anaerobic treatment tank.

Examples of materials for the anaerobic bed 20 include:
Natural or artificial materials such as sand, firestone, pumice, activated carbon, foamed fireclay, foamed ceramics, and synthetic resins are used in regular or irregular shapes, and are made into a predetermined length using an upflow method. The second anaerobic treatment tank 12 is filled.

In this anaerobic bed 20, water-soluble organic substances that could not be decomposed in the anaerobic bed 16 are anaerobically decomposed by anaerobic bacteria attached to the bed 20, and
2 to the outside as treated water C.

Further, in this embodiment, the circulation passage 26 in which the circulation pump 24 is installed is branched from the outlet 22, and one end of the circulation passage 26 is connected to the second anaerobic treatment tank 1.
It is connected to the bottom of 2.

In this circulation passage 26, the overflow water (treated water C) of the second anaerobic treatment tank 12 is returned to the lower part of the treatment tank 12 again, and is again subjected to anaerobic treatment in the anaerobic bed 20.

Note that the amount returned through the circulation passage 26 is desirably about 2 to 3 times the treated water.

On the other hand, a sludge tank 28 located below the communication path 18 is provided directly below the anaerobic bed 16 of the first downward flow type anaerobic treatment tank 10 .

This sludge tank 28 separates solid organic matter in the treated raw water A by sedimentation, and performs anaerobic treatment on it in a restrained or semi-restricted state.

As a means for restraining solid organic matter, in this embodiment, a rotating shaft 30 is provided that vertically passes through the first downward flow type anaerobic treatment tank 10, and a plurality of stirring blades 32 are fixed to this rotating shaft 30. , rotating shaft 30
The drive motor 34 connected to the upper end is driven at 5 to 50 rpm.
This is done by driving at a relatively low speed.

When the stirring blade 32 is driven to rotate at a low speed in this way, the anaerobic bacteria in the sludge tank 28 come into contact with the solid organic matter while flowing and can decompose it anaerobically. Therefore, the floating state is maintained, and floating and flowing down from the communication path 18 to the second anaerobic treatment tank 12 is prevented.

In the sludge tank 28, when solid organic matter is generally subjected to anaerobic treatment in a restrained state for about 20 days, the solid organic matter is completely anaerobically decomposed and becomes methane and carbon dioxide gas. Depending on the state of the bacterial group, it is possible that organic matter may be hydrolyzed and solubilized.

Therefore, in this embodiment, a branch passage 36 is provided in the circulation passage 26, and this branch passage 36 is connected to the lower part of the sludge tank 28, so that a part of the treated water C is transferred to the sludge tank 28.
We are planning to introduce it in 8th.

With this configuration, the treated water C introduced from the branch passage 36 washes out the solubilized organic matter by an upward flow, and is passed through the communication passage 18 to the second anaerobic treatment tank 1.
2 and undergoes anaerobic treatment in the anaerobic bed 20.

When treating solid organic matter in the sludge tank 28, it is desirable to control the hydrogen ion concentration to a value suitable for anaerobic decomposition, and for this purpose, an alkaline solution or the like may be added.

The pH adjustment range is preferably 7 to 7.5 when performing complete anaerobic decomposition, and 5 to 6 when performing up to solubilization of organic matter.

In this case, when solubilizing organic matter in the sludge tank 28, the pH of the second anaerobic treatment tank 12 is
The value is adjusted to about 7 to 7.5 via the circulation passage 26.

The stirring blade 32a fixed to the uppermost stage of the rotating shaft 30 is located above the anaerobic bed 16 to destroy and settle scum generated on the surface of the supplied treated raw water A, and to remove the scum from the raw water A. It has the function of promoting early sedimentation of solid organic matter contained in

Further, at the lower end of the second anaerobic treatment tank 12, there is a return passage 40 equipped with a return pump 38 for appropriately returning the primary treated water B to the supply side of the raw water A, and a sludge tank 28.
A drawing passage 44 equipped with a pump 42 for drawing excess sludge is provided at the lower end of each of the pipes.

Furthermore, the first and second anaerobic treatment tanks 10,
A recovery passage 46 for digestive gas is provided at the upper end of the pipe 12 .

Now, in the wastewater treatment apparatus configured as above, the treated raw water A containing solid organic matter is separated from the solids in the anaerobic bed 16, the communication passage 18,
It flows down in order of anaerobic bed 20, and each bed 1
By performing the anaerobic treatment in steps 6 and 20, water-soluble organic matter is decomposed and removed and is discharged as treated water C.

In this case, the anaerobic bed 16 of the first downward flow type anaerobic treatment tank 10 to which the treated raw water A containing solid organic matter is supplied is capable of settling solid organic matter, so that it is prevented from being clogged with organic matter. Ru.

In addition, the solid organic matter is separated from the treated raw water A or the primary treated water B by settling in the downward flow type first anaerobic treatment tank 10, and only the solid organic matter is then suspended in the sludge tank 28. Since anaerobic treatment is performed in this state, the sludge tank 28 becomes considerably smaller than when the entire treated raw water A is treated anaerobically, and the entire treatment apparatus does not become large.

<<Effects of the Invention>> As explained above in the embodiments, the anaerobic wastewater treatment apparatus according to the present invention treats the entire wastewater anaerobically without removing solid organic matter from the wastewater in advance. In addition to being decomposable, solid organic matter usually requires a long decomposition time, but the device of the present invention separates this by sedimentation and decomposes only the solid organic matter in a sludge tank, not the entire wastewater, so that it can be decomposed easily. Even if the residence time is increased, the sludge tank can be kept small, and since water-soluble organic matter is treated in an anaerobic bed, the entire device can be made compact.

[Brief explanation of the drawing]

FIG. 1 is an overall explanatory diagram showing an example of an anaerobic wastewater treatment apparatus according to the present invention. 10... Downward flow type first anaerobic treatment tank, 12...
Upflow type second anaerobic treatment tank, 16...anaerobic bed,
18... Communication path, 20... Anaerobic bed, 28... Sludge tank, A... Treated raw water, B... Primary treated water, C...
...treated water.

Claims (1)

[Claims] 1. In an anaerobic treatment device for wastewater containing solid organic matter, the raw water to be treated containing solid organic matter is supplied from above, and the first anaerobic downstream flow type is equipped with an anaerobic bed capable of settling the solid organic matter. A processing tank;
A second anaerobic treatment of an upward flow type having an anaerobic bed that communicates with the lower part of the first anaerobic treatment tank via a communication path and to which the primary treated water treated in the first anaerobic treatment tank is supplied from below. tank, and a sludge tank that is formed directly below the anaerobic bed of the first anaerobic treatment tank and below the communication path, and performs anaerobic treatment of the settled solid organic matter in a restrained state. Anaerobic wastewater treatment equipment.