JPH10165980A - Anaerobic treatment equipment for organic wastewater - Google Patents

Abstract

(57) [Summary] (Modifications) [Problem] Treatment that does not mix with sludge regardless of the amount of CODcr load of organic wastewater (raw water) to be treated and the amount of generated anaerobic gas are large. In addition to being able to collect water, the sludge that has been subjected to sedimentation treatment is forcibly returned to the reaction section, and the organic matter in the raw water is completely biologically treated. SOLUTION: A reaction section 21 having an anaerobic sludge layer 22 at the bottom and a water supply pipe 23 for supplying organic wastewater in an upward flow in the sludge layer is provided. A cylindrical settling section 24 is arranged, and a partition wall 28 is provided around the settling section.
And the above-mentioned space between the sedimentation section and the partition wall is provided as a rising water passage 29, and a communication means 30 for communicating the rising water passage with the inside of the sedimentation section is provided. A baffle plate 34 is provided below the lower end of the rising water passage. Is provided, and a return pipe 33 for returning sludge settled at the bottom of the settling section to the reaction section is provided between the bottom of the settling section and the reaction section, and treated water is taken out of the tank from the upper portion in the settling section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for converting organic matter in organic wastewater into granules composed of anaerobic microorganisms constituting sedimentation and self-granulated sludge (a granule having a small particle size) as a precursor thereof. Finally, it is decomposed into anaerobic gas mainly composed of methane and carbon dioxide to remove organic matter, and the treated water after the decomposition of organic matter is separated from the generated anaerobic gas and sludge. The present invention relates to a UASB type (upflow sludge blanket type) anaerobic treatment apparatus which is separated and taken out.

[0002]

2. Description of the Related Art As shown in FIG.
1, an inclined separating plate 12 whose upper end protrudes above the water surface in the tank, is inclined below the water surface, and whose lower end is located at the middle of the height of the tank. Sludge sedimentation chamber 13 and reaction chamber 14 provided separately in the tank by
And an anaerobic sludge layer 15 formed on the bottom of the tank in the reaction chamber.
And a water supply pipe 1 for supplying organic wastewater into the anaerobic sludge layer.
6, an overflow trough 17 for treated water provided in contact with an inclined separation plate in the upper part of the sludge settling chamber, and a gas separation inclined in the lower part of the sludge settling chamber inside the reaction chamber. An anaerobic treatment device for organic wastewater comprising a plate 18 is conventionally known. The planar shape of the treatment tank 10 may be a cylindrical shape or a rectangular tube shape. In the case of the cylindrical shape, the inclined separating plate 12 is a conical tube having a diameter decreasing downward, and the gas separating plate 18 is a jinkasa shape. In addition, the conical plate of the inclined separation plate has an upper half 12a.
And the upper part is composed of a lower half part 12b whose diameter is slightly larger than the lower part of the upper half part. The lower part of the upper half and the upper part of the lower half are fitted concentrically inside and outside, and a gas-like gas between them A conical passage 12 'is formed toward the peripheral surface of the separator. With such a configuration, the lower opening of the sludge settling chamber 13 is covered with the gas separation plate 18 from below, leaving the flow path.

[0003] Raw water (organic wastewater) supplied into the treatment tank from the water supply pipe 16 decomposes organic substances contained therein by anaerobic microorganisms of the sludge constituting the sludge layer when rising in the anaerobic sludge layer. The treated water flows upward in the reaction chamber 14 with some sludge accompanying the rise of the anaerobic gas generated by the decomposition. Then, a part of the treated water enters the sludge settling chamber 13 from the periphery of the gas separation plate 18 through an inlet at the lower end, and becomes an upward flow A rising in the chamber. The inlet at the lower end of the sludge sedimentation chamber is blocked by the gas separation plate 18, and the treated water with the sludge does not directly flow upward into the sludge separation chamber, so that the gas is separated and the treated water flowing into the sludge sedimentation chamber rises. The sludge contained in the stream A is separated inside the room, and the sludge falls on the gas separation plate from the inlet at the lower end of the sedimentation room against the treated water flowing into the sludge sedimentation room from below, and from around the gas separation plate. It sinks on the anaerobic sludge layer 15. Therefore, the treated water from which the sludge has been separated flows into the overflow trough 17 and is taken out from the discharge pipe 19.
In addition, a part of the generated anaerobic gas collects under the gas separation plate 18, and from around the gas separation plate or from both ends of the gas separation plate having a chevron-shaped cross section when the processing tank has a rectangular tube shape, outside the sedimentation chamber. It floats on the liquid surface and is discharged from the gas vent tube 11.

[0004] The remaining treated water containing the sludge that has not flowed into the sludge sedimentation chamber rises to the upper part of the reaction chamber around the inclined separation plate 12 accompanying the anaerobic gas, and the anaerobic gas is removed from the liquid in the reaction chamber. It floats on the surface and is discharged from the degassing pipe 11. The rising speed of the treated water that rises to the upper part of the reaction chamber accompanying the anaerobic gas is determined by the CODcr load in the raw water, that is, the amount of the generated anaerobic gas. As the CODcr load increases, the anaerobic gas increases. The production rate of the treated water is increased because the amount of the produced water is large. In this way, the treated water that has released the anaerobic gas in the reaction chamber forms a conical passage 12 below the inclined separation plate 12 along the outside of the inclined separation plate 12 along the outside of the inclined separation plate 12 in the reaction chamber as a reverse flow C of the upward flow B caused by the anaerobic gas. ′, The sludge contained in the treated water sinks onto the anaerobic sludge layer 15.

[0005]

SUMMARY OF THE INVENTION The above-mentioned conventional apparatus is a COD.
If the organic wastewater has a cr load of up to about 15 kg / COD / m ³ / day, it can be sufficiently treated.
In the case of an organic wastewater having an OD load of 20 kg / COD / m ³ / day or higher, the amount of generated anaerobic gas is large, so that the ascending flow B in the reaction chamber and the subsequent outside of the inclined separation plate The reverse flow C descending along the passage 12 ′ along the path becomes high speed, violently impinges on the gas separating plate 18, and partly becomes a reflective upward impinging flow D and enters the inside of the sedimentation chamber 13, The sludge to be settled in the sedimentation chamber may be prevented, or the sludge to be settled may flow into the overflow trough 17, and the sludge may be mixed with the treated water taken out from the discharge pipe 19. That is, since the reverse flow C descending along the inclined separation plate 12 in the reaction chamber utilizes the reverse flow of the upward flow B rising in the reaction chamber due to the anaerobic gas, the reverse flow C rises with an increase in the CODcr load. An increase in the flow velocity of the flow B leads to an increase in the flow velocity of the reverse flow C,
As a result, the vertically upward impinging flow D which rises reflexively into the sedimentation chamber 13 and agitates the inside of the chamber has a considerable effect, and as described above, prevents sludge sedimentation in the sedimentation chamber,
The sludge flows out to the discharge pipe 19. In addition, the sludge separated in the sludge sedimentation chamber must flow into the chamber and fall on the gas separation plate against the flow of the treated water that becomes the upflow A, so that the sludge stays in the sludge sedimentation chamber and becomes anaerobic. The amount of the sludge in the activated sludge layer 15 may be insufficient.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for reliably treating sludge contained in treated water without being affected by the upward flow of treated water due to anaerobic gas even when the CODcr load of raw water is high. The above-mentioned problems of the conventional apparatus are completely solved by forcibly returning the separated sludge to the anaerobic sludge layer by sedimentation and separation. As an anaerobic treatment apparatus for organic wastewater, anaerobic sludge is provided at the bottom. The inside of a treatment tank having a reaction section having a bed and a water supply pipe for supplying organic wastewater in an upward flow into the sludge layer, above the reaction section, and the upper end is above the water surface in the tank. A protruding bottomed cylindrical sedimentation section is arranged, and an overflow device for taking out treated water out of the treatment tank is provided in the upper part of the sedimentation section, and a space is maintained around the sedimentation section along the sedimentation section. And place the above-mentioned space between the sedimentation section and the partition wall above the reaction section. A rising water channel into which a part of the treated water flows, and a communication means for communicating the rising water channel with the inside of the sedimentation section. The communication means has a tangential direction in which the treated water is tangentially supplied to the inside of the sedimentation section. While forming the supply port,
A baffle plate is provided below the lower end of the rising channel to prevent anaerobic gas from entering the rising channel, and sludge settled at the bottom of the settling portion is provided between the bottom of the settling portion and the reaction portion. A return pipe for returning to the reaction section is provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In each of the embodiments shown in FIGS. 1 and 2, reference numeral 20 denotes a covered processing tank having a degassing pipe 20 'at the top, reference numeral 22 denotes an anaerobic sludge layer formed of sludge formed inside the processing tank, and reference numeral 23 denotes a processing tank. This is a water supply pipe that supplies raw water (organic wastewater) into the anaerobic sludge layer and flows it upward. The sludge that constitutes the anaerobic sludge layer reaches the middle of the height of the treatment tank due to the raw water flowing upward. Evolve into a flowing state. A reaction section 21 is formed in the lower half of the treatment tank by the water supply pipe 23 of raw water and the anaerobic sludge layer 22 that develops in a fluidized state.

[0008] Above the reaction section 21 inside the processing tank,
A bottomed cylindrical precipitation part 24 whose upper end protrudes above the water surface W in the tank is arranged. The bottom 24 ′ of the sedimentation section 24 is closed in the illustrated embodiment in the form of a cone having a V-shaped cross section, and the reaction section 2 is closed.
Located away on one. An overflow device 25 into which the treated water in the settling section overflows is provided at an upper portion in the settling section, and the treated water overflowing the overflow device is taken out of the tank by a drain pipe 26. The overflow device 25 is, in the embodiment of FIG.
2 is a trough provided along the upper inner periphery, and in the embodiment of FIG.

Around the sedimentation section 24, a partition wall 28 is arranged at intervals along the sedimentation section, and treated water rising from the reaction section 21 flows at the above-mentioned interval between the sedimentation section and the partition wall. The rising water channel 29 is formed. And the communication means 30 which supplies the treated water of this rising water channel 29 to the inside of the sedimentation section is provided,
The communication means is provided with a tangential supply port 31 for supplying treated water tangentially into the water in the settling section. The communication means 30 of the embodiment of FIG. 1 is provided in the rising water channel 29 and is connected to a water pipe 32 for lowering the treated water overflowing from the water surface of the water channel, to the lower end of the water pipe, and connects the wall of the sedimentation section. The supply port 31 penetrates in the tangential direction. The communication means 30 in the embodiment of FIG. 2 is the supply port 31 which is attached to a hole formed in the wall of the sedimentation portion and projects tangentially into the water of the sedimentation portion.

A return pipe 3 for returning sludge settled at the bottom of the settling section to the reaction section is provided between the bottom of the settling section 24 and the reaction section 21.
3 is provided. A pump P is connected to the return pipe 33, and the pump is operated continuously or intermittently to supply sludge from the bottom of the settling section to the reaction section.

The anaerobic gas floating from the reaction section 21 flows into the rising water channel below the lower end of the rising water channel 29 formed at the interval between the outer surface of the settling portion and the inner surface of the partition wall surrounding the settling portion. A baffle plate 34 is disposed to prevent the occurrence of the baffle. In the embodiment of FIG. 1 where the bottom 24 ′ of the sediment closes conically as shown and the lower end of the partition 28 ends shortly from above in a cone of the lower half of the sediment, in the embodiment of FIG. A little downward from the lower end of the bottom, a baffle plate having a C-shaped cross section substantially perpendicular to the conical lower half of the sedimentation section is fixed to the lower half of the sedimentation section. Also, in the case of the embodiment of FIG. 2 where the lower end of the partition wall 28 extends long near the conically closed bottom of the sedimentation section, the partition wall 28 is used.
Place a baffle-shaped baffle slightly below the opening at the lower end of the. Each baffle plate 34 is provided with an exhaust pipe 35 for exhausting the anaerobic gas accumulated therebelow to the surface of the processing tank.

Thus, in each of the embodiments shown in FIGS. 1 and 2,
Raw water (organic wastewater) that is supplied from the water supply pipe 23 into the treatment tank and flows upward in the reaction section 21 and develops the anaerobic sludge layer 22 in a fluidized state is contained in contact with the sludge developed in a fluidized state. Organic matter is decomposed by anaerobic microorganisms and becomes treated water. The treated water accompanies the anaerobic gas generated and decomposed by the decomposition, and flows further upward from the reaction section 21 with some sludge.

A portion of the treated water flowing upward flows into the rising water passage 29 from below and rises in the water passage, and the remainder of the treated water rises outside the partition wall 28 and is contained in the treated water. The gas bubbles of the anaerobic gas floating on the water surface of the treatment tank and degassing pipe 20
And released outside. Even if the anaerobic gas is contained in some of the treated water flowing into the ascending channel 29 and rising, the anaerobic gas floats on the liquid surface of the ascending channel and is discharged from the degassing pipe 20 ′. However, if the baffle 34 is provided below and below the lower end of the rising channel, the treated water flowing into the rising channel rises mainly toward the baffle and bypasses the edge of the baffle. Therefore, the anaerobic gas contained in the treated water accumulates under the baffle plate and can be prevented from entering the ascending water channel 29, and the sludge rolled up with the gas is largely prevented from flowing into the sedimentation section. Part, can be prevented.
The anaerobic gas accumulated under the baffle plate is guided to the water surface of the treatment tank by the exhaust pipe 35, and is discharged from the gas vent pipe 20 '.

In the embodiment shown in FIG. 1, the treated water flowing into the ascending water passage 29 is supplied to a water conduit 32 opened above the water surface of the communicating means 30.
Overflows into the upper end of the pipe, descends through the water pipe, flows tangentially into the water of the sedimentation section 24 from the supply port 31, and in the embodiment of FIG. 31
Flows tangentially into the water in the sedimentation section 24. Since the upper end of the settling portion projects above the water surface in the treatment tank and the bottom is closed, the sedimentation portion may be affected by the treated water flowing upward outside the partition wall 28 or the water flow by the anaerobic gas floating. Since there is no,
Sludge contained in the treated water supplied to the sedimentation section freely settles at the bottom of the sedimentation section according to its own sedimentation property, and the supernatant treated water separated from the sludge overflows into the overflow device 25, and the drainage pipe From 26, it flows out of the tank.

In particular, the treated water in the rising water channel flows tangentially into the water of the sedimentation section 24 by the tangential supply port 31 of the communicating means, so that a swirling ascending swirl is generated in the sedimentation section, and the treated water The sludge mixed into the sediment and swirled on the swirl flows, gathers at the center of the sediment by the centripetal force of the swirl, and settles at the bottom center of the sediment. Therefore, in order to collect sludge settling from the periphery of the sedimentation part at the center of the bottom, it is not necessary to steepen the slope of the cone at the bottom of the sedimentation part or mechanically collect sludge using a rake or the like. . This means that the slope of the cone at the bottom of the sedimentation section can be reduced to increase the amount of sludge retained in the sedimentation section at the same height. By making the same as the sedimentation part, it means that the height of the sedimentation part can be reduced and the height of the entire apparatus can be reduced. In addition, the supply port 31
May be determined so that a vortex having a desired flow velocity is obtained.

Further, since the swirling current rising while turning in the sedimentation section is stabilized by the inertial force, the rising water passage 29 is determined based on the amount of raw water supplied from the water supply pipe 23.
Therefore, even if the flow rate of the treated water flowing into the sedimentation section 24 by the communication means 30 fluctuates, the fluctuation can be absorbed, so that there is no adverse effect on the sedimentation and separation of the sludge. Therefore, it is possible to reliably prevent the sludge from flowing into the overflow device 25,
Stable operation with high load. For example, since the COD _cr volume load is proportional to the sludge holding concentration, a maximum of 100 kg CO
High load operation up to about D / m ³ / day becomes possible.

The sludge deposited on the bottom of the settling section 24 is continuously or intermittently returned to the reaction section 21 by the operation of the pump P via the return pipe 33. The amount of sludge returned to the reaction section by the return pipe 31 is preferably about 1 to 10% of the amount of supernatant treated water taken out by the drain pipe 26.

In the embodiment shown in FIGS. 1 and 2, the upper end of the partition wall 28 protrudes above the water surface, whereby the ascending flow of the treated water ascending in the ascending water passage 29 is preferably not disturbed. In the embodiment, the upper end of the partition wall 28 is located below the water surface if the treated water can rise in the rising channel to the position of the tangential supply port 31 of the communicating means for flowing the treated water tangentially into the water in the settling section. It may be.

[0019]

As is clear from the above, according to the present invention, the lower end of the cylindrical sediment is closed, and the inside of the sediment is treated water that rises outside the partition wall surrounding the sediment, and the anaerobic surface that floats. It is not affected at all by the water flow of the volatile gas. And the treated water rising in the rising channel formed between the settling portion and the partition wall surrounding the outside, flows tangentially into the water in the settling portion by the tangential supply port of the communicating means, As a result, a swirling current that rises while swirling is generated in the settling portion. Since this vortex is stabilized by inertia, it absorbs fluctuations in the inflow of treated water into the sediment due to the magnitude of the inflow of raw water, and sedimentation and separation of sludge mixed with the treated water and flowing into the sediment. Sludge that has flowed into the sedimentation section due to the centripetal force of the vortex collects at the center and sinks to the center of the bottom of the sedimentation section, increasing the amount of sludge retained in the sedimentation section and lowering the height of the device Help to do. In this manner, the treated water containing no sludge can be taken out of the tank from the overflow trough in the settling section, and the sludge can be prevented from flowing out into the treated water. Therefore, even if the CODcr load of the organic wastewater is high and the amount of generated anaerobic gas is large, it is possible to collect the supernatant treated water which is not mixed with the sludge regardless of the amount. The sludge settled on the sedimentation section is forcibly returned to the reaction section by a return pipe, so that the amount of anaerobic sludge in the reaction section can be prevented and the organic matter in the raw water can be completely biologically treated. it can.

[Brief description of the drawings]

FIG. 1A is a schematic longitudinal sectional view of a first embodiment of an anaerobic treatment apparatus of the present invention, and FIG. 1B is a sectional view taken along line AB in FIG.

FIG. 2A is a schematic longitudinal sectional view of a second embodiment of the anaerobic treatment apparatus of the present invention, and FIG. 2B is a sectional view taken along line AB of FIG.

FIG. 3 is a schematic vertical sectional view of a conventional anaerobic treatment device.

[Explanation of symbols]

 Reference Signs List 20 treatment tank 21 reaction part 22 anaerobic sludge layer of reaction part 23 water supply pipe to reaction part 24 sedimentation part 24 ′ bottom of sedimentation part 25 overflow device of sedimentation part 26 drainage pipe from overflow device 27 exhaust pipe 28 partition Wall 29 rising water channel 30 communication means 31 tangential supply port of communication means 33 sludge return pipe 34 baffle plate 35 exhaust pipe

Claims (1)

[Claims] 1. Inside a treatment tank having a reaction section having an anaerobic sludge layer at the bottom and a water supply pipe for supplying organic wastewater in an upward flow in the sludge layer, above the reaction section. A bottomed cylindrical settling part whose upper end protrudes above the water surface in the tank is arranged, and an overflow device for taking out treated water out of the processing tank is provided at the upper part of the settling part. Around the sedimentation part, a partition wall is arranged around the sedimentary part, and the above-mentioned space between the sedimentation part and the partition wall is a rising waterway into which a part of the treated water rising from the reaction part flows, and this rising waterway and A communication means for communicating the inside of the sedimentation section is provided.The communication means has a tangential supply port for supplying treated water in a tangential direction inside the sedimentation section, and is provided below a lower end of the rising water channel. A baffle to prevent anaerobic gas from entering the rising channel, and between the bottom of the sedimentation section and the reaction section An anaerobic treatment apparatus for organic waste water, wherein a return pipe is provided for returning sludge settled at the bottom of a settling section to a reaction section.