JP2003285088A - Wastewater treatment method and treatment apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus capable of performing highly efficient treatment for wastewater by sludge bacteria and capable of treating the damaged part of the treatment apparatus together with sludge even if the treatment apparatus is partially damaged by long-term use. <P>SOLUTION: The wastewater treatment apparatus is equipped with an aeration tank 6 for treating wastewater by utilizing the action of sludge bacteria, an oxygen supply means 54 for dissolving oxygen in the aeration tank 6 and a carrier put in wastewater to immobilize sludge bacteria. The carrier is constituted of a plant fiber body and/or a wood fiber body having porous interstices and sludge bacteria adhere to the porous interstices of the plant fiber body and/or the wood fiber body not only to keep the surface parts of the plant fiber body and/or the wood fiber body aerobic but also to keep the interiors of them anaerobic. For example, as the plant fiber body, there is a dry luffa and, as the wood fiber body, there is a hemp palm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method and a treatment apparatus for treating wastewater such as factory wastewater and domestic wastewater by utilizing the function of sludge bacteria.

[0002]

2. Description of the Related Art Various methods have been proposed as a method for treating wastewater, and one of them is known to utilize the action of sludge bacteria. In this wastewater treatment method, the wastewater to be treated flows into the aeration tank, oxygen (for example, air) is supplied to the aeration tank by the oxygen supply means, and the supplied oxygen (oxygen in air) enters the wastewater. Dissolved. Sludge bacteria are present in the waste water, the sludge bacteria are activated by dissolved oxygen, and the organic substances in the waste water are decomposed into carbon dioxide (CO ₂ ) and water (H ₂ O) by the action of the sludge bacteria. Treated wastewater, that is, purified water, is discharged into waterways, rivers and the like.

In such a wastewater treatment method, in order to proliferate sludge bacteria and treat the wastewater efficiently, the wastewater in the aeration tank may usually contain a carrier as a habitat for the sludge bacteria.
When the carrier is put in this way, the sludge bacteria adhere to the carrier, the sludge bacteria grow on the carrier, and the wastewater can be efficiently treated.

[0004]

However, in the conventional wastewater treatment method, the carrier is urethane foam, ceramic,
It is formed from pumice, etc., and in connection with this, there are the following problems to be solved. When, for example, urethane foam is used as a carrier, if it is put in waste water and used for a long time, it will be soaked in the waste water for a long time, and it will be easily damaged. When it breaks, it mixes with the sludge, becomes together, and is treated together with the sludge, but urethane foam (synthetic resin)
There is a problem in treating a mixture of the above as ordinary sludge, and therefore the treatment becomes complicated and the treatment cost becomes high. Further, when using, for example, ceramic or pumice stone as a carrier, if it is damaged by long-term use, it becomes sandy and precipitates on the bottom of the aeration tank, which causes a decrease in the treatment capacity of the aeration tank. Further, since the specific gravity of ceramics and pumice stone is larger than that of water, if sludge bacteria adhere, it becomes difficult to float in the wastewater, and if the floating is insufficient, the efficiency of treatment with sludge bacteria decreases.

An object of the present invention is to provide a wastewater treatment method and treatment apparatus that can treat sludge bacteria with high efficiency and that can be treated together with sludge even if a part is damaged due to long-term use. Is to provide.

[0006]

According to the present invention, waste water to be treated is introduced into an aeration tank, a carrier serving as a habitat for sludge bacteria is placed in the waste water, and the waste water is treated by utilizing the action of the sludge bacteria. In the wastewater treatment method described above, a plant fiber body and / or a wood fiber body is used as the carrier, and the sludge bacterium is attached to the porous space of the plant fiber body and / or the wood fiber body.

According to the present invention, since a plant fiber body and / or a wood fiber body is used as a carrier, it can be treated as normal sludge even if it is damaged and combined with sludge, and unlike urethane foam, etc. It is unlikely to be a pollution problem. Also,
The carrier composed of a plant fibrous body and / or a wood fibrous body has a porous space between fibers, and sludge bacteria easily enter the porous space to become a dwelling, thereby activating the sludge bacteria. In addition, it is possible to operate in a state higher than the apparent sludge concentration, the load of the aeration tank can be increased, and the amount of organic substances removed in the activated sludge treatment and its removal rate can be increased. Furthermore, the carrier composed of plant fibrous bodies and / or wood fibrous bodies has a small specific gravity, and even if sludge bacteria adhere to the carrier, they easily float in the sludge, so that sludge bacteria can spread all over the sludge in the aeration tank. The sludge treatment efficiency can also be improved. The carrier may be a plant fiber body or a wood fiber body alone, or may be a combination of both.

Further, in the present invention, the plant fiber and / or
Alternatively, the surface portion of the wood fiber body is kept aerobic and the inside thereof is kept anaerobic, and the growth of the sludge bacterium is controlled by the aerobic property of the surface portion and the anaerobic nature of the inside.

According to the present invention, since the surface portion of the plant fiber body and / or the wood fiber body becomes aerobic, the function of the sludge bacteria on this surface portion is activated, and the sludge bacteria in the aerobic portion activate the sludge. The processing is performed efficiently. On the other hand, since the inside of the plant fibrous body and / or the wood fibrous body becomes anaerobic, the function of sludge bacteria weakens and returns to the inside of the aeration tank, and the growth of sludge bacteria is controlled by the aerobic surface and anaerobic inside. Therefore, the generation of excess sludge can be reduced.

Further, in the present invention, the plant fiber body is dried loofah, and the wood fiber body is palm fiber. According to the present invention, since the plant fibrous body is dried loofah, the porous space of the dried loofah easily serves as a habitat for sludge bacteria, and its specific gravity is small, so that it can be used as a relatively inexpensive carrier. In addition, since the wood fiber body is palm fiber, a large number of spaces between palm fibers function as a porous space, and its specific gravity is small, so that it can be used as a carrier like dry loofah.

The present invention also provides an aeration tank for treating wastewater by utilizing the action of sludge bacteria, an oxygen supply means for dissolving oxygen in the aeration tank, and an aeration tank for treating the sludge bacteria in wastewater. In the wastewater treatment device including a carrier for housing, the carrier is composed of a plant fiber body and / or a wood fiber body having a porous space, and the plant fiber body and / or the wood fiber body is The sludge bacterium adheres to the porous space, the surface portion of the plant fiber body and / or the wood fiber body is kept aerobic, and the inside thereof is kept anaerobic.

According to the present invention, the carrier to be put in the aeration tank is composed of the plant fiber body and / or the wood fiber body, so that even if it is damaged and is combined with the sludge, it can be treated as normal sludge. In addition, the carrier composed of a plant fibrous body and / or a wood fibrous body has a porous space between the fibers, and the porous space serves as a residence for sludge bacteria, thereby activating the sludge bacteria and apparently It is possible to operate at a higher concentration than the sludge concentration of. Further, the carrier composed of plant fibrous bodies and / or wood fibrous bodies has a small specific gravity, and the carrier easily floats due to the oxygen supplied into the sludge from the oxygen supply means, and therefore the sludge bacterium is contained in the entire sludge in the aeration tank. And the efficiency of sludge treatment in the aeration tank can be improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a wastewater treatment method and treatment apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a system diagram schematically showing a wastewater treatment apparatus (apparatus for performing a wastewater treatment method) according to the present invention, and FIG. 2 is a perspective view showing a carrier to be put in an aeration tank.

In FIG. 1, the illustrated wastewater treatment apparatus comprises a flow rate adjusting tank 2, a pH adjusting tank 4, an aeration tank 6, a precipitation tank 8 and a treated water tank 10. The flow rate adjusting tank 2 is a tank for adjusting the amount of waste water to be treated. For example, factory waste water (eg, milk, coffee, etc.), domestic waste water, etc. are temporarily stored in the flow rate adjusting tank 2. To be pH adjustment tank 4
Is a tank for adjusting the pH of the wastewater. Flow rate adjustment tank 2
The pH adjusting tank 4 and the pH adjusting tank 4 are connected to each other via a feed passage 12, and a feed pump 14 is arranged in the feed passage 12.
The waste water in the flow rate adjusting tank 2 is fed to the pH adjusting tank 4 by a predetermined amount through the feed passage 14 by the action of the feed pump 14. In the pH adjusting tank 4, hydrochloric acid or the like is added to the waste liquid to neutralize the waste water to be treated. If there is no need to neutralize the wastewater to be treated, the pH adjusting tank 4 can be omitted.

The aeration tank 6 utilizes the function of sludge bacteria to remove organic substances contained in wastewater from carbon dioxide (CO2) and water (H2).
O) or the like, and the waste water neutralized in the pH adjusting tank 4 is fed through the feed passage 16.
The aeration tank 6 and the structure related thereto will be described later.

The settling tank 8 is for separating and separating treated water and sludge (including sludge bacteria). The wastewater treated in the aeration tank 6 is fed to the settling tank 8 through the feed passage 18, and in the settling tank 8, the wastewater from the aeration tank 6 (organic substances are decomposed) is treated water. And sludge 20 is precipitated and separated. The separated sludge 20 collects at the bottom of the settling tank 8, and the separated treated water collects at the upper part of the settling tank 8. A sludge collecting member 24 rotated by, for example, an electric motor 22 is provided at the bottom of the settling tank 8, and the sludge collecting member 24 is rotated as necessary to collect the sludge 20.

The treated water tank 10 is for sterilizing treated water. The treated water that has been precipitated in the settling tank 8 is
The water is fed to the treated water tank 10 through the feed passage 26. The treated water tank 10 is provided with a sterilizer 28,
The treated water sent to is sterilized by the sterilizer 28. For this sterilization treatment, for example, sodium hypochlorite is used. Then, after being sterilized in this way, the treated water is discharged to rivers, waterways and the like.

A return passage 30 is further provided between the aeration tank 6 and the settling tank 8, and a measuring tank 32 is provided in the return passage 30.
Is provided. The measuring tank 32 is used when returning the sludge 20 precipitated in the settling tank 8 to the aeration tank 6, measures the amount of the sludge 20 returned to the aeration tank 6, and returns the measured sludge 20. It is returned to the aeration tank 6 through the flow path 30. Since the sludge 20 is returned to the aeration tank 6 in this way, the sludge bacteria used when treating the sludge are circulated through the aeration tank 6, the feed passage 18, the settling tank 8 and the return passage 30. Become.

A waste flow path 34 is branched into the measuring tank 32,
The waste flow path 34 is connected to the sludge storage tank 36.
When the amount of the settled sludge 20 in the settling tank 8 increases, a part of the settled sludge 20 is returned to the return channel 30, the measuring tank 32, and the waste channel 3.
The sludge fungus circulated through the aeration tank 6 and the settling tank 8 is obtained by storing a part of the settled sludge 20 in the settling storage tank 36 by being sent to and stored in the sludge storage tank 36 through 4. You can control the street.

The sludge bacteria stored in the sludge storage tank 36 are fed to the dehydrator 42 through the sludge feed passage 40 by the action of the sludge feed pump 38. The dehydrator 42 dehydrates and solidifies the sent sludge, and thus the excess sludge is discarded as a fixed matter. At this time, as will be described later, since the sludge does not contain a synthetic resin or the like, the solidified product of the sludge can be disposed of as ordinary sludge, and the disposal thereof is easy and the disposal cost is also low. is there.

Next, referring to FIG. 2 together with FIG. 1, the aeration tank 6 and the structure related thereto will be described. The aeration tank 6 includes a tank main body 52 into which waste water to be treated flows, and an oxygen supply unit 54 for supplying oxygen to the waste water to dissolve the waste water is disposed at the bottom of the tank main body 52. The oxygen supply means 54 shown is an air supply source 56 such as a blower.
And a plurality of air ejection pipes 58 arranged at the bottom of the tank main body 52, and the air supply source 56 and the air ejection pipes 58 through the main feed passage 60 and the branch feed passage 62. Connected,
An on-off valve 64 is arranged in each branch feed passage 62. Therefore, when the on-off valve 64 is opened, the air from the air supply source 56 is sent to the air jet pipe 58 through the main feed passage 60 and the branch feed passage 62, and a large number of these air jet pipes 58 are supplied. It is ejected into the wastewater from an ejection hole (not shown).
In this embodiment, the air (oxygen is contained in this air) supplied from the air supply source 56 is dissolved in the waste water, but instead of the air supply source 56 of the oxygen supply means 54, for example, oxygen is used. An oxygen supply source to be supplied may be used, and oxygen supplied from the oxygen supply source may be dissolved in the waste water.

In the aeration tank 6, as described above, the function of sludge bacteria is utilized to decompose the organic substances contained in the wastewater. There are bacteria such as zooglare, protozoa such as boltesera, and sludge fungi such as filamentous fungi in the sludge for wastewater treatment.Activates the functions of these bacteria, protozoa, filamentous fungi, etc. Let it be decomposed.

In the wastewater of the aeration tank 6, a carrier 72 (see FIG. 2), which is a residence of the sludge bacteria, is placed in order to activate the function of the sludge bacteria. It is important that the carrier 72 is composed of a plant fiber body and / or a wood fiber body having a porous space, and by using such a carrier 72,
The sludge bacteria enter the porous space of the carrier 72 to form its residence.

As the plant fibrous body, for example, dried loofah (dried loofah) 74 can be conveniently used. For example, one side is approximately 2 to 6 cm in a substantially cubic shape, and each side is approximately 2 to 6 cm. Rectangular parallelepiped shape, diameter about 5-10 cm
With a thickness of about 2 to 5 cm, a suitable shape such as a substantially short cylindrical shape (the dried loofah is sliced into slices) (see FIG. 2) or a substantially short semi-cylindrical shape (the sliced slice is further halved) is used. Can be formed. Since there are many porous spaces inside the dried loofah 74, it is suitable as a house for sludge bacteria, and the dried loofah may be used as it is. Further, instead of using it as it is, as shown in FIG. 2, it may be used by being compressed by twine 76, wood fiber or the like, that is, by compressing the porous space to a small size.

Further, as the wood fiber body, for example, one obtained by bundling palm fibers into an appropriate shape can be used. Even when such a palm is used, the space between the bundled fibers functions as a porous space of the carrier 72, and like the case where the dried loofah 72 is used, it is suitable as a house for sludge bacteria.

As the carrier 72, a plant fiber body (for example, dried loofah) or a wood fiber body (for example, palm) may be used alone, but a combination of the plant fiber body and the wood fiber body may be used. Good. Carrier 72 like this
Has a low specific gravity, and even if sludge bacteria adhere to the internal porous space, they easily float in the wastewater. Also, plant fiber bodies,
Since the wood fiber body is a natural fiber material, it can be subjected to normal waste treatment together with the sludge by dehydration treatment and solidification together with the sludge.

The carrier 72 has a volume ratio of 10 with respect to the total volume of the wastewater to be treated (volume containing the wastewater and the carrier 72).
~ 30% can be added. When the filling rate of the carrier 72 is 10% or less, the number of dwellings is small and the sludge bacteria in the wastewater are small, and the wastewater cannot be decomposed efficiently, and when the filling rate exceeds 30%, the carrier 72 becomes too large, the amount of waste water in the tank body 52 decreases, and the amount of waste water decomposed decreases.

The decomposition treatment by sludge bacteria in the aeration tank 6 is performed as follows. When decomposing an organic substance by utilizing the action of sludge bacteria, the opening / closing valve 64 is held in an open state, and the air from the air supply source 56 is supplied to the main feed passage 6
It is jetted from the air jet pipe 58 through the 0 and the branch feed passage 62, and is dissolved in the waste liquid. Also, when air blows out,
The jetted air allows the carrier 72 floating in the waste liquid to circulate, and the filled carrier 72 is the tank main body 52.
Almost uniformly dispersed in the waste liquid inside. Since the carrier 72 is thus dispersed, due to the action of sludge bacteria adhering to the carrier 72,
Organic substances in the waste liquid in the tank main body 52 are decomposed into carbon dioxide and water, and the entire waste liquid in the tank main body 52 is decomposed by sludge bacteria. Thus, the decomposition processing ability can be enhanced and the processing efficiency can be improved. Can be increased.

At the time of this decomposition treatment, sludge bacteria adhere to the porous space inside the carrier 72, and the carrier 72 becomes a residence of sludge bacteria. In the carrier 72, the surface portion thereof is likely to come into contact with dissolved oxygen in the wastewater and thus exhibits aerobic property, and the sludge bacteria existing on this surface portion are activated and proliferate, and the activated sludge bacteria are contained in the waste liquid. Decomposes organic substances. On the other hand, the inside thereof is unlikely to come into contact with the dissolved oxygen in the waste liquid, and thus exhibits an anaerobic property, and the activity of the sludge bacteria existing inside this is weakened and returns to the waste liquid. Since the carrier 72 has a certain size, as described above, its surface portion is aerobic,
The inside has anaerobic property, and the activity and growth of sludge bacteria are controlled by the aerobic property of the surface and the anaerobic property of the interior, and the desired activity and growth state are maintained to stably decompose the wastewater for a long time. It can be carried out.

Example In order to confirm the effect of the present invention, the following experiment was conducted. As Example 1, the following aeration tank and precipitation tank were used, dry loofah was used as a carrier, the waste water treatment was performed under the following operating conditions, and the treatment results were examined. The treated wastewater was food material wastewater and was continuously treated for 2 months. Aeration tank and its operating conditions Aeration tank capacity 500 liters Amount of treated water 500 liters / day Treated water quality (BOD) 3000 mg / liter Load amount 1.5 kg / day Aeration tank load amount 3.0 kg / m ³ · day Air into wastewater in the feed weight 400 l / min dried gourd gourd shape substantially cubic shape loofah filling rate of 15 to 25 mm (volume ratio to the total waste water) about 20% example 1, the water quality of the waste water in the inlet of the aeration tank (BOD) is Although it was 3000 mg / liter, the water quality (BOD) of the wastewater at the outlet of the aeration tank was reduced to 100 mg / liter by the decomposition treatment under the above operating conditions, and the removal rate of the wastewater was 96.7%. It was Further, even if the decomposition treatment was continued for 2 months, the treatment capacity did not decrease, and it was confirmed that the wastewater could be sufficiently decomposed by the sludge bacteria.

Further, as Example 2, the following aeration tank and precipitation tank were used, dry loofah was used as a carrier, the waste water treatment was performed under the following operating conditions, and the treatment results were examined. The treated wastewater is soft drink water, 1
Processing was continued for a month. Aeration tank and its operating conditions Aeration tank capacity 1000 liters Amount of treated water 300 liters / day Treated water quality (BOD) 15000 mg / liter Load amount 4.5 kg / day Aeration tank load amount 4.5 kg / m ³・ day Air to waste water in the feed weight of 800 liters / min dry gourd gourd shape substantially cubic shape loofah filling rate of 15 to 25 mm (volume ratio to the total waste water) about 20% example 2, water quality of the waste water in the inlet of the aeration tank (BOD) is It was 15,000 mg / liter,
By decomposing under the above operating conditions, the quality of wastewater (BOD) at the outlet of the aeration tank is 1000 mg.
/ Liter, and the removal rate of wastewater was 93.3%. Further, even if the decomposition treatment was continued for one month, the treatment capacity did not decrease, and it was confirmed that even such wastewater can be sufficiently decomposed by sludge bacteria.

[0032]

According to the wastewater treatment method of the first aspect and the wastewater treatment apparatus of the fourth aspect of the present invention, since the plant fiber body and / or the wood fiber body is used as the carrier, it is damaged and becomes together with the sludge. However, it can be treated as normal sludge. Further, the carrier composed of a plant fiber body and / or a wood fiber body has a porous space between the fibers, and sludge bacteria easily enter the porous space to become a dwelling, thereby activating the sludge bacteria. As a result, the load on the aeration tank can be increased, and the sludge removal amount and sludge removal rate in sludge treatment can be increased. Furthermore, the carrier composed of plant fibrous bodies and / or wood fibrous bodies has a small specific gravity, and even if sludge bacteria adhere to the carrier, it easily floats in the sludge. Therefore, sludge bacteria can be spread all over the sludge in the aeration tank. Become.

Further, according to the wastewater treatment method of the second aspect of the present invention, since the surface portion of the plant fiber body and / or the wood fiber body becomes aerobic, the function of sludge bacteria on this surface portion is activated. The sludge treatment can be efficiently performed by the sludge bacteria in the aerobic part. On the other hand, since the inside of the plant fiber body and / or the wood fiber body becomes anaerobic, the function of sludge bacteria weakens and returns to the inside of the aeration tank, and the growth of sludge bacteria is controlled by the aerobic surface and the anaerobic inside. can do.

Furthermore, according to the wastewater treatment method of claim 3 and the wastewater treatment device of claim 5 of the present invention, since the plant fibrous body is dried loofah, the porous space of the dried loofah serves as a residence of sludge bacteria. It can be used as a relatively inexpensive carrier because it is easy and its specific gravity is small and it easily floats in wastewater.
Further, since the wood fiber body is palm fiber, a large number of spaces between palm fibers function as a porous space and can be used as a carrier like dry loofah.

[Brief description of drawings]

FIG. 1 is a system diagram schematically showing a wastewater treatment apparatus (apparatus for performing a wastewater treatment method) according to the present invention.

FIG. 2 is a perspective view showing a carrier placed in an aeration tank.

[Explanation of symbols]

2 Flow rate adjustment tank 6 aeration tank 8 settling tank 10 treated water tank 20 Settled sludge 30 Return flow path 32 weighing tank 52 tank body 54 Oxygen supply means 58 Air ejection pipe 72 carrier 74 dried loofah

Claims (5)

[Claims] 1. A wastewater treatment method for treating wastewater by inflowing wastewater to be treated into an aeration tank, inserting a carrier that becomes a habitat of sludge bacteria into the wastewater, and treating the wastewater by utilizing the action of the sludge bacteria. As the plant fiber body and / or wood fiber body,
A method for treating wastewater, characterized in that the sludge fungus is attached to the porous space of the plant fiber body and / or the wood fiber body. 2. The surface portion of the plant fiber body and / or the wood fiber body is kept aerobic, and the inside thereof is kept anaerobic. Due to the aerobic property of the surface portion and the anaerobic property of the inside, The method for treating wastewater according to claim 1, wherein the growth is controlled. 3. The wastewater treatment method according to claim 1, wherein the plant fiber body is dry loofah, and the wood fiber body is palm fiber. 4. An aeration tank for treating wastewater by utilizing the action of sludge bacteria, an oxygen supply means for dissolving oxygen in the aeration tank, and a wastewater to be used as a residence for the sludge bacteria. In the wastewater treatment apparatus including the carrier, the carrier is composed of a plant fibrous body and / or a wood fibrous body having a porous space, and in the porous space of the plant fibrous body and / or the wood fibrous body. The sludge bacterium adheres, and the surface portion of the plant fiber body and / or the wood fiber body is kept aerobic,
A wastewater treatment device whose inside is kept anaerobic. 5. The wastewater treatment apparatus according to claim 4, wherein the plant fiber body is dry loofah, and the wood fiber body is palm fiber.