JPH10180289A - Anaerobic treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the anaerobic treating device capable of conducting a high-efficiency treatment by stabilizing a liq. flow in a solid-liq. separation part to enhance solid-liq. separation efficiency and to decrease the outflow of a granular sludge into the treated liq., restoring the settling property even if the granular sludge is floated up and returning the sludge to a reaction part. SOLUTION: A reaction part 11 in which a sludge blanket is provided in an anaerobic reaction tank 1, a first solid-liq. separation part 9a formed by solid-liq. separation members 8a, 8b and 8c and a gas collecting part 10 are furnished at the upper part of the reaction part 11, and a second solid-liq. separation part 9b isolated from the reaction part 11 and first solid-liq. separation part 9a is provided to constitute the anerobic treating device. The separated liq. is transferred to the second solid-liq. separation part 9b from the first solid- liq. separation part 9a, the separated sludge is returned to the reaction part 11 from the second solid-liq. separation part 9b, and the granular sludge is discharged from the floated sludge discharge part 14 of the second solid-liq. separation part 9b, crushed by a crushing pump 23 and returned to the reaction part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic wastewater
The present invention relates to an anaerobic treatment apparatus for performing anaerobic treatment by the B (upflow sludge blanket) method.

[0002]

2. Description of the Related Art As an anaerobic treatment method for organic wastewater, a sludge blanket is formed by forming granular sludge having high density and large sedimentation, and flowing upward the organic wastewater containing soluble BOD. The UASB method of performing high-load, high-speed processing by making contact in such a state is adopted. This method is a method of separating solid organic substances having a low digestion rate and separately treating them, and treating only soluble organic substances having a high digestion rate at a high load by anaerobic treatment using granule sludge having a high anaerobic microorganism density. It is said that this is a more efficient processing method than the conventional anaerobic processing.

Some UASB anaerobic treatment devices include:
In particular, in a device that performs high-load treatment with a BOD load of 10 kg / m ³ · d or more, the granular sludge floats and turns into scum, and the floating sludge flows out into the treated water, and the sludge in the anaerobic reaction tank is discharged. A phenomenon in which the retention amount decreases is seen.
If the sludge floats or flows out, the treatment becomes insufficient, and the high-load operation characteristic of the UASB method becomes difficult, and anaerobic sludge flows into the activated sludge treatment device, which is a post-treatment of the UASB method, Dramatically lower the DO of the aeration tank,
The treatment performance of the activated sludge treatment device will be reduced.

[0004] Most of the granular sludge floating in the UASB anaerobic reaction tank has the specific gravity of the sludge reduced because the gas generated by the anaerobic reaction is built in the granular sludge. There are many examples. Therefore, by crushing the granular sludge containing the gas, the gas in the contained state is released, and it is possible to form a blanket which is the original form of the granular sludge. Therefore, in the anaerobic treatment device of the UASB type, the granular sludge floating in the reaction tank is appropriately discharged to the outside of the reaction tank, and the discharged sludge is crushed using a pump, a mixer, a homogenizer, or the like capable of crushing the sludge. Attempts have been made to return it to the reactor in an exposed state.

FIG. 2 is a sectional view of a conventional UASB type anaerobic treatment apparatus disclosed in, for example, JP-A-8-103794. In the figure, reference numeral 1 denotes an anaerobic reaction tank, which is formed of a rectangular parallelepiped container, and a liquid to be treated inflow portion 2 is uniformly provided at a bottom portion, and communicates with a liquid to be treated introduction passage 3. The upper part of the anaerobic reaction tank 1 is covered with a cover 4 to form a gas chamber 5 having a closed structure, and a gas extraction path 6 communicates with the top.

A liquid chamber 7 is formed below the gas chamber 5 in the anaerobic reaction tank 1, and a solid-liquid formed of first and second partition plates inclined in opposite directions is formed above the liquid chamber 7. Gas separation member 8
a and 8b are arranged, and a solid-liquid separation part 9 is defined inside the upper part, a gas collecting part 10 is defined outside the upper part, and a reaction part 11 is defined below. The lower ends of the solid-liquid gas separating members 8a and 8b are separated to form a communication passage 12, and one lower end covers the lower side of the other lower end. 9 is prevented from entering.

An organic waste liquid is introduced into the liquid chamber 7 in the anaerobic reaction tank 1, and a sludge blanket 13 is formed in the reaction section 11. An overflow-type floating sludge take-out section 14 is provided at a liquid level near the upper portion of the communication passage 12 above the solid-liquid separation section 9 and communicates with a floating sludge take-out path 15. An overflow-type processing liquid take-out section 16 is provided above the solid-liquid separation section 9 and communicates with a processing liquid take-out path 17. Both take-out units 14 near the processing liquid take-out unit 16;
A baffle 18 is provided near the liquid surface between the 16.

A crushing device 21 has a gas chamber 5a formed in the upper part and a liquid chamber 7a formed in the lower part. The gas chamber 5a communicates with the pressure equalizing pipe 22 from the gas chamber 5 of the anaerobic reaction tank 1. 7a
Is connected to the rising sludge removal path 15. The liquid chamber 7a
Is provided with a crushing pump 23, and a sludge return path 24 communicates with the liquid chamber 7 of the anaerobic reaction tank 1.

In the above-described anaerobic treatment method using the anaerobic treatment apparatus, first, granule sludge containing anaerobic microorganisms granulated by utilizing the self-granulating properties of anaerobic microorganisms is supplied to the reaction section 11 of the anaerobic reaction tank 1. To And the liquid to be treated 3
An organic effluent is introduced into the to-be-processed liquid inflow section 2 provided at the bottom of the anaerobic reaction tank 1 from above, and the sludge blanket 13 is formed by passing the liquid in an upward flow, and is contacted under anaerobic conditions to be anaerobic. Perform a sexual reaction. Thereby, the soluble organic matter in the wastewater is decomposed into methane and carbon dioxide by the action of the anaerobic microorganism through the acid generation step and the methane generation step.

Since the granular sludge has a high density and an excellent sedimentation property, a uniform sludge blanket 13 is formed by passing the discharged liquid in an upward flow, and the sludge blanket 13 is held in the reaction section 11. The organic effluent that has passed through the sludge blanket 13 enters the solid-liquid separation section 9 through the communication path 12, where it is separated into solid and liquid. The separated liquid overflows from the processing liquid extraction section 16 and becomes a processing liquid as a processing liquid. Is taken out.
The separated sludge settles and returns from the communication passage 12 to the reaction section 11. Gas such as methane generated in the reaction section 11 rises in the reaction section 11, but is blocked by the solid-liquid gas separation members 8a and 8b and does not flow into the solid-liquid separation section 9, but is collected in the gas collection section 10. , From the gas chamber 5 to the gas extraction path 6.

When the operation is performed under a high load, or when the operation is continued for a long period of time, the apparent specific gravity of the granular sludge becomes small and floats and floats on the liquid surface of the solid-liquid separation section 9. . In this case, the floating sludge that has entered the solid-liquid separation section 9 from the communication passage 12 is separated from the floating sludge removal section 14.
Floating sludge removal path 15
From the crusher 21.

In the crushing device 21, the introduced floating sludge is crushed by the crushing pump 23 and returned to the reaction section 11 from the sludge return path 24. The floating sludge has a hollow part formed inside, so by crushing this hollow part to be exposed on the surface, it returns to the original state with a large specific gravity,
Sedimentation recovers.

However, in the conventional anaerobic treatment apparatus as described above, the liquid in the liquid chamber 7 enters the solid-liquid separation section 9 through the communication passage 12, while the sludge separated in the solid-liquid separation section 9 communicates with the sludge. Because of the sedimentation through the flow path 12, the upward flow and the downward flow collide in the communication path 12, and turbulence is likely to occur. In particular, in high-load high-speed processing, the upward flow velocity of the liquid in the reaction section is large and the amount of generated gas is large, so that the upward flow flowing into the solid-liquid separation section 9 tends to generate turbulent flow. For this reason, the water flow in the solid-liquid separation unit 9 becomes unstable, the solid-liquid separation effect is reduced, and the granular sludge having a small particle diameter or the sludge particles serving as the granule precursor easily flows out into the treatment liquid. There was a problem.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to stabilize a liquid flow in a solid-liquid separation section by cutting off the influence of a liquid flow and a generated gas in a reaction section, thereby increasing a solid-liquid separation efficiency. In addition, it is possible to reduce the outflow of the granular sludge having a small particle diameter or the sludge serving as a granule precursor to the treatment liquid, and even when the granular sludge floats, efficiently remove the sludge and recover the sedimentation property. It is an object of the present invention to provide an anaerobic treatment apparatus which can return to a reaction section and thereby maintain the sludge concentration in the tank at a high level and perform treatment with high treatment efficiency.

[0015]

SUMMARY OF THE INVENTION The present invention relates to an anaerobic reaction tank having a reaction section in which a sludge blanket made of granular sludge containing anaerobic microorganisms is formed and a bottom section having an inflow section of a liquid to be treated. A solid-liquid gas separating member that is arranged at an upper portion of the reaction section so as to be inclined so as to separate the first solid-liquid separation section and the gas collection section, and a communication section that connects the reaction section to the first solid-liquid separation section. A passage, a second solid-liquid separator isolated from the reaction section and the first solid-liquid separator, and a transfer path for transferring the separated liquid from the first solid-liquid separator to the second solid-liquid separator. A sludge return section for returning separated sludge from the sludge concentration section formed below the second solid-liquid separation section to the reaction section, and an overflow type provided via a baffle above the second solid-liquid separation section. From the processing liquid discharge section and the floating sludge discharge section, and from the floating sludge discharge section It and a crushing device for returning to the reaction portion by crushing the granular sludge anaerobic treatment apparatus according to claim.

The anaerobic treatment apparatus of the present invention is used for a high-load anaerobic treatment method by the UASB method, and is suitable for treating a solution portion obtained by solid-liquid separation of an organic effluent. The organic effluent to be treated is not limited, and includes, for example, sewage, human waste, effluent from the paper industry, effluent from the food industry, etc. Among them, those having a high solid content concentration are treated by removing the solid content. To be served.

As the anaerobic reaction tank constituting the anaerobic treatment apparatus of the present invention, an anaerobic reaction tank having a reaction part inside, which has been conventionally used for UASB treatment, can be used almost as it is. In this case, granule sludge is present in the reaction section,
A sludge blanket is formed by flowing upward from the liquid-to-be-treated introduced portion provided at the lower portion, and the tank is maintained in an anaerobic state so as to be in contact with the sludge blanket.

The operating conditions of the anaerobic reaction tank, for example, the flow rate, residence time, temperature and the like are the same as those of the conventional method, and the upward flow rate in the UASB is 0.5 to 2 m / hr, preferably 1 to 1.
5 m / hr, residence time 4-48 hours, preferably 6-48 hours
The liquid sending system is configured to be about 24 hours. The temperature is, for example, 20 to 45 ° C. for the medium temperature treatment, and 4
A heating or warming device and a temperature control device are provided so that the temperature is 5 ° C. or more.

The first solid-liquid separation section is provided above the reaction section so as to be separated from the gas collection section by a solid-liquid gas separation member, like the conventional anaerobic reaction tank, and communicates with the reaction section through a communication passage. It is configured to

The second solid-liquid separation section is provided in a state separated from the reaction section and the first solid-liquid separation section. Here, the state of being isolated from the reaction part means a structure in which the liquid flow in the reaction part and the first solid-liquid separation part and the generated gas are blocked by a partition wall or the like so as not to affect the inside of the solid-liquid separation part. And
It may be provided independently of the anaerobic reaction tank. First
The solid-liquid separation section and the second solid-liquid separation section are connected by a transfer path.

The transfer path is provided between the sludge concentration section and the processing liquid take-out section of the second solid-liquid separation section so as to transfer the separated liquid. The transfer path is divided by a baffle so as to prevent disturbance of the liquid in this section. It is preferably transferred to the inlet. In the second solid-liquid separation section, a sludge concentration section is formed at a lower portion, and an overflow type treatment liquid take-out section and a floating sludge take-out section are formed at an upper portion via a baffle.

The sludge return section is configured to extract concentrated sludge from the sludge concentration section of the second solid-liquid separation section, and forcibly return the sludge to the reaction section by a pump if necessary. At this time, it can be configured to discharge the excess sludge outside the system. The crushing device is configured to crush the granular sludge taken out from the floating sludge take-out section and return it to the reaction section.

Although the growth process of granular sludge in the UASB method is not clear, anaerobic microorganisms adhere to the surface of minute inorganic SS with a particle size of about 0.1 mm or the surface of scale components containing calcium and magnesium. Then, new anaerobic microorganisms grow and adhere in the form of annual rings with the small SS and scale as nuclei, and it takes over several months to grow into granular sludge with a particle size of 0.5 to 1 mm. I have. It is said that the grown granule sludge is crushed by a flow caused by the flow of water and gas in the reaction tank, and the crushed fine particles and fragments become nuclei, and the next granule sludge grows.

In the case where the grown granule sludge is not crushed or the crushed ratio or degree is small,
As the sludge continues to grow and the particle size becomes 1 to several mm, the anaerobic microorganisms and organic SS components inside the granular sludge self-decompose. After self-decomposition, it becomes a cavity, and the gas generated by the methane generation reaction accumulates in the cavity, and the specific gravity of the granular sludge is reduced by the contained gas, and as a result, the granular sludge is thought to rise and flow out .

When the load in the UASB method is low,
The growth of granulated sludge and the ratio of crushed grown sludge are balanced, so the existence ratio of granulated sludge that grows to a large particle size and contains gas is low, and the sludge floating and outflow phenomenon Is not noticeable. On the other hand, BO
When the treatment is performed at a high load of 10 to 15 kg / m ³ · d as the D load, the growth rate of the granular sludge becomes much higher than the crushing rate, and the floating and outflow phenomenon of the sludge increases. Therefore, when the UASB method performs a high-load operation, a floating phenomenon of granular sludge occurs unless a heavy scale component or inorganic SS is constantly supplied into the sludge.

Therefore, according to the present invention, the floating sludge is efficiently taken out and crushed appropriately, thereby reducing the average particle diameter of the floating sludge and, at the same time, exposing the internal hollow portion to the outer surface to recover the sedimentation property. , And is configured to maintain the sludge concentration in the tank high. It is preferable that the floating sludge take-out part is opened at a position lower than the treatment liquid take-out part. As the crushing device, a pump having a crushing mechanism such as a grinder pump, a mixer, a homogenizer, or the like can be used. It is preferable that the crushing device is disposed at a position lower than the floating sludge take-out section, and the floating sludge is configured to move down.

[0027]

The anaerobic treatment method using the anaerobic treatment apparatus according to the present invention comprises the steps of first reacting granulated sludge containing anaerobic microorganisms granulated by utilizing the self-granulating properties of anaerobic microorganisms in an anaerobic reaction tank. The organic wastewater is introduced from the inflow portion of the liquid to be treated provided at the bottom portion, and is passed in an upward flow to form a sludge blanket, which is contacted under anaerobic conditions. Thereby, the soluble organic matter in the wastewater is decomposed into methane and carbon dioxide by the action of the anaerobic microorganism through the acid generation step and the methane generation step.

Since the granular sludge has a high density and an excellent sedimentation property, a uniform sludge blanket is formed by passing the discharged liquid in an upward flow, and is held in the reaction section. The waste liquid that has passed through the sludge blanket enters the first solid-liquid separation section from the communication path, where it is separated into solid and liquid, and the separated liquid is transferred from the transfer path to the second solid-liquid separation section. The separated sludge settles and returns to the reaction section from the communication passage. Gas such as methane generated in the reaction section rises in the reaction section, but is blocked by the solid-liquid gas separation member and does not flow into the first solid-liquid separation section,
Removed from the gas collection section.

In a normal operation state where the load is relatively low, there is no floating of the granular sludge, and the sludge flowing into the solid-liquid separation section is settled as it is and returns to the reaction section. When the operation is continued for a long period of time, the apparent specific gravity of the granular sludge becomes small and floats, and floats on the liquid surface of the gas collecting part or the first solid-liquid separating part. In the gas collecting section, since the liquid level is disturbed by the generated gas, even if the specific gravity of the granular sludge is small, it can be easily circulated to the reaction section as it is.

In the first solid-liquid separation section, the upward flow of the reaction liquid flowing from the reaction section through the communication section and the downward flow of the sludge returning to the reaction section collide to generate turbulent flow. In high-load, high-speed processing, the amount of gas generated in the reaction section is large.
Since the turbulent flow easily occurs in the upward flow flowing into the solid-liquid separation section, the water flow in the first solid-liquid separation section becomes unstable. For this reason, the solid-liquid separation effect in the first solid-liquid separation section is low,
Granule sludge having a small particle size and sludge particles of a granule precursor easily flow out together with the separation liquid.

The separated liquid thus transferred from the first solid-liquid separation section to the second solid-liquid separation section includes large floating granulated sludge floating on the liquid surface of the first solid-liquid separation section. Besides,
Granular sludge of a small particle size and sludge particles of a granule precursor which did not settle in the first solid-liquid separation section are also included.

In the second solid-liquid separation section, the separated liquid from the first solid-liquid separation section flows into an intermediate portion between the sludge concentration section and the processing liquid take-out section. In the second solid-liquid separation section, the liquid flow is not disturbed and free sedimentation occurs. In the case of UASB, the rising flow velocity is 3 to
30 m / hr is possible. The separation liquid separated in the solid-liquid separation section is taken out as a processing liquid from the processing liquid take-out section. The separated sludge is concentrated in the sludge concentration section, and is returned from the sludge return section to the reaction section by a pump or the like.

An anaerobic reaction is performed while the floating sludge floating in the second solid-liquid separation section is taken out from the floating sludge take-out section, crushed by a crusher and returned to the reaction section. Floating sludge is blocked by the baffle and does not flow out of the processing liquid outlet. Since the floating sludge has a hollow part inside,
When the hollow portion is crushed so as to be exposed on the surface, the granular sludge returns to its original state having a large specific gravity, and the sedimentation property is restored. The degree of crushing at this time is such that most of the crushed sludge has a particle size of 0.2 to 0.7 mm, preferably 0.3 to 0.5 mm.
mm. If the particle size of the crushed sludge is less than 0.2 mm, it tends to flow out together with the treatment liquid, and if it exceeds 0.7 mm, the hollow portion is not exposed and the sedimentation property is often not recovered, which is not preferable.

When crushing with a pump having a sludge crushing mechanism, the degree of crushing is checked in advance using a special pump having a vortex type or a foreign matter crushing mechanism, and the number of revolutions suitable for an appropriate crushing situation is determined. It is preferable to operate with a constant flow rate. The appropriate crushing situation can be confirmed and adjusted by measuring the particle size of the crushed sludge. When using a mixer or a homogenizer for crushing, it is preferable to adjust the stirring intensity while checking the crushing status.

If the treatment is continued without crushing the floating sludge, the floating sludge flows out together with the treated water, and the amount of the sludge decreases, thereby reducing the treatment efficiency. By returning, the sludge concentration in the tank (the amount of sludge in the tank /
Reaction volume) is kept high. Sludge concentration in tank is 300
It can be kept at not less than 00 to 40000 mg / l.

In the present invention, in addition to the first solid-liquid separation section,
The second solid-liquid separation section is separated from the reaction section, and the sludge is circulated by the transfer path and the sludge return path. The generated gas does not affect the solid-liquid separation section, and the entering liquid does not collide with the exiting sludge. Therefore, the liquid flow in the second solid-liquid separation section is stabilized, whereby the solid-liquid separation efficiency is increased, the outflow of sludge to the treatment liquid is reduced, and the granular sludge or granule precursor having a small particle diameter is obtained. Is returned to the reaction section and grows into granule sludge having a large particle size. The granulated sludge that has floated recovers its sedimentation property by crushing, and is returned to the reaction section to maintain a high sludge concentration in the reaction section. Thereby, in the present invention, processing can be performed with high processing efficiency.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a UASB type anaerobic treatment apparatus according to an embodiment, and the same reference numerals as those in FIG. 2 indicate the same or corresponding parts. In the drawing, an anaerobic reaction tank 1 is formed of a rectangular parallelepiped container, and a liquid-to-be-treated inflow portion 2 is uniformly provided at a bottom portion, and is connected to a liquid-to-be-treated introduction path 3. Anaerobic reaction tank 1
Is covered with a cover 4 to form a gas chamber 5 having a closed structure, and a gas extraction path 6 communicates with the top.

A liquid chamber 7 is formed below the gas chamber 5 in the anaerobic reaction tank 1, and a solid-liquid made of first and second partition plates inclined in opposite directions is formed above the liquid chamber 7. Gas separation member 8
a and 8b are arranged, a first solid-liquid separation part 9a is provided inside the upper part, a gas collecting part 10 is provided outside the upper part, and a reaction part 1 is provided below.
1 is sectioned. The lower ends of the solid-liquid gas separating members 8a and 8b are separated to form a communication path 12, and the lower side thereof is covered by a cap-shaped third solid-liquid gas separating member 8c. The structure is such that it is prevented from entering the liquid separating section 9a.

An organic effluent is introduced into the liquid chamber 7 in the anaerobic reaction tank 1, and a sludge blanket 13 is formed in the reaction section 11. Above the first solid-liquid separation section 9a, an overflow type separation liquid take-out section 25 is provided, and a transfer path 26 communicates with the second solid-liquid separation section 9b.

The second solid-liquid separation section 9b is provided independently of the reaction tank 1 so as to be isolated from the reaction section 11 and the first solid-liquid separation section 9a. A part 27 is formed. A processing liquid take-out section 16 is provided in an upper peripheral portion of the second solid-liquid separation section 9b in an overflow manner, and an overflow floating sludge take-out section 14 is provided inside the baffle 18 from the processing liquid take-out section 16 through a baffle 18. Is also provided so as to open at a slightly lower position.

At the center of the upper part of the second solid-liquid separation part 9b, an introduction cylinder 28 is provided so as to open from the liquid level to an intermediate part between the sludge concentration part 27 and the processing liquid take-out part 16, and the opening thereof is provided. A diffusion member 29 is provided at the end. The transfer path 26 communicates with the introduction cylinder 28, and the processing liquid extraction path 17 communicates with the processing liquid extraction section 16. A sludge return path 32 having a pump 31 from the sludge concentration section 27 communicates with the reaction section 11, and a sludge return path 24 having a crushing pump 23 from the floating sludge take-out section 14.
Communicates with the reaction unit 11. 33 is a surplus sludge taking-out path.

In the anaerobic treatment method using the anaerobic treatment apparatus described above, first, granule sludge containing anaerobic microorganisms granulated by utilizing the self-granulating property of anaerobic microorganisms is supplied to the reaction section 11 of the anaerobic reaction tank 1. To And the liquid to be treated 3
An organic effluent is introduced into the to-be-processed liquid inflow section 2 provided at the bottom of the anaerobic reaction tank 1 from above, and the sludge blanket 13 is formed by passing the liquid in an upward flow, and is contacted under anaerobic conditions to be anaerobic. Perform a sexual reaction. Thereby, the soluble organic matter in the wastewater is decomposed into methane and carbon dioxide by the action of the anaerobic microorganism through the acid generation step and the methane generation step.

Since the granular sludge has a high density and an excellent sedimentation property, a uniform sludge blanket 13 is formed by passing the discharged liquid in an upward flow, and the sludge blanket 13 is held in the reaction section 11. The organic effluent that has passed through the sludge blanket 13 enters the first solid-liquid separation section 9a from the communication passage 12, and
Here, the liquid is primarily solid-liquid separated, and the separated liquid overflows from the separated liquid take-out section 25 and is transferred from the transfer path 26 to the second solid-liquid separating section 9b. The separated sludge settles and returns from the communication passage 12 to the reaction section 11. Gas such as methane generated in the reaction section 11 rises in the reaction section 11, but is blocked by the solid-liquid gas separation members 8 a, 8 b, 8 c, so that the first solid-liquid separation section 9
The gas does not flow into a, but is collected in the gas collecting section 10 and is taken out from the gas chamber 5 to the gas take-out passage 6.

In a normal operation state with a low load, the granular sludge does not float on the liquid surface, and the sludge flowing into the first solid-liquid separation section 9a settles as it is and returns to the reaction section 11, but the high sludge is returned to the reaction section 11. When the operation is performed with a load or when the operation is continued for a long time, the apparent specific gravity of the granular sludge becomes small and floats, and the granular sludge floats on the liquid surface of the first solid-liquid separation section 9a. In this case, the buoyant sludge that has entered the first solid-liquid separation section 9a from the communication path 12 overflows from the separation liquid take-out section 25, and is transferred from the transfer path 26 to the second solid-liquid separation section 9b.

The separated liquid transferred from the transfer path 26 enters the introduction cylinder 28 of the second solid-liquid separation section 9b, where it flows downward and is located at an intermediate position between the sludge concentration section 27 and the processing liquid removal section 16. It is transported, where it is diffused in the peripheral direction by the diffusion member 29 to perform solid-liquid separation.

In the second solid-liquid separation section 9b, separation is performed by free sedimentation so that liquid flow is not disturbed. The separated liquid separated in the solid-liquid separation section 9b is taken out of the treatment liquid take-out section 16 through the treatment liquid take-out path 17 as a treatment liquid. The separated sludge is concentrated in the sludge concentration section 27, accelerated by the pump 31 through the sludge return path 32, and returned to the reaction section 11. As a result, the granular sludge having a small particle diameter and the sludge particles of the granule precursor flowing out of the first solid-liquid separation section 9a are returned to the reaction section and grow into large-sized granule sludge. When excess sludge is generated, excess sludge removal path 3
Removed from 3.

The large-sized granulated sludge that has floated is taken out at a substantially constant flow rate from the rising sludge take-out section 14, crushed by a crushing pump 23, and passed through the sludge return path 24 to the reaction section 11.
Will be returned to Since the floating sludge has a hollow portion formed therein, the crushing of the hollow sludge so that the hollow portion is exposed on the surface returns to a state where the specific gravity is large, and the sedimentation property is restored. By performing the anaerobic reaction while crushing the floating sludge and returning it to the reaction section 11 in this manner, the sludge concentration in the tank is maintained at a high level, and the treatment efficiency is maintained at a high state.

In the above-described apparatus, a second solid-liquid separation section 9b is provided in addition to the first solid-liquid separation section 9a, and the second solid-liquid separation section 9b is isolated from the reaction section 11, In addition, since the sludge is circulated by the transfer passage 26 and the sludge return passage 32, the liquid flow and the generated gas in the reaction unit 11 do not affect the second solid-liquid separation unit 9b, and the liquid that flows in There is no collision with the sludge coming out. Therefore, the liquid flow in the second solid-liquid separation section 9b is stabilized, whereby the solid-liquid separation efficiency is increased, the outflow of sludge into the treatment liquid is reduced, and the granular sludge or granule precursor having a small particle size is reduced. The body is returned to the reaction section 11 and grows into granule sludge having a large particle diameter. The granulated sludge that has floated is crushed by the crushing pump 23 to recover the sedimentation property, and
1 to maintain the sludge concentration in the reaction section 11 high. This makes it possible to perform processing with high processing efficiency.

[0049]

As described above, according to the present invention, the reaction section of the anaerobic reaction tank and the second solid-liquid separation section separated from the first solid-liquid separation section are provided. Was transferred to the intermediate portion of the second solid-liquid separation section, and the concentrated sludge was returned to the reaction section by a pump from the sludge return path, and the floating sludge was crushed and returned to the reaction section. The liquid flow in the second solid-liquid separation section and the first solid-liquid separation section are shut off to stabilize the liquid flow in the second solid-liquid separation section, thereby increasing the solid-liquid separation efficiency, and In addition to reducing the outflow of sludge, the granule sludge of small particle size and the sludge particles of the granule precursor are returned to the reaction section to grow into large-sized granule sludge, and the floating sludge is crushed to reduce sedimentation. It recovers and the reaction zone can be maintained at a high sludge concentration.

[Brief description of the drawings]

FIG. 1 is a sectional view of an anaerobic treatment device of an embodiment.

FIG. 2 is a cross-sectional view of a conventional anaerobic treatment device.

[Explanation of symbols]

 Reference Signs List 1 anaerobic reaction tank 2 liquid to be treated 3 inlet for liquid to be treated 4 cover 5 gas chamber 6 gas outlet 7 liquid chamber 8a, 8b, 8c solid-liquid gas separating member 9a first solid-liquid separating section 9b second Solid-liquid separation unit 10 Gas collection unit 11 Reaction unit 12 Communication passage 13 Sludge blanket 14 Floating sludge extraction unit 15 Floating sludge extraction passage 16 Treatment liquid extraction unit 17 Treatment liquid extraction passage 18 Baffle 21 Crusher 22 Equalizing tube 23 Crush pump 24 , 32 Sludge return path 25 Separation removal section 26 Transfer path 27 Sludge concentration section 28 Introductory cylinder 29 Diffusion member 31 Pump 33 Excess sludge removal path

Claims (1)

[Claims] 1. An anaerobic reaction tank having a sludge blanket formed of granular sludge containing anaerobic microorganisms therein, and having an inflow part for a liquid to be treated at the bottom, and a anaerobic reaction tank at the top of the reaction part. A solid-liquid gas separating member inclined to separate the solid-liquid separating section and the gas collecting section, a communication path communicating the reaction section with the first solid-liquid separating section, A second solid-liquid separator isolated from the solid-liquid separator, a transfer path for transferring the separated liquid from the first solid-liquid separator to the second solid-liquid separator, and a second solid-liquid separator. A sludge return section for returning separated sludge from the sludge enrichment section formed at the lower portion to the reaction section; an overflow-type treatment liquid take-out section provided via a baffle above the second solid-liquid separation section; Extraction unit and crushed granular sludge taken out from the floating sludge extraction unit Anaerobic treatment apparatus characterized by comprising a crushing device for returning the 応部.