JP3115038B2 - Sludge digestion and concentration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge digestion / concentration apparatus for digesting and concentrating sludge such as sewage and wastewater in a single tank.

[0002]

2. Description of the Related Art Conventionally, when digesting sludge accompanying treatment of sewage or wastewater, a mixed sludge mixed with raw sludge drawn from a first settling tank and excess sludge drawn from a final settling tank is used. After concentrating the sludge in the concentrator,
Anaerobic digestion in the first digester. And the first
The sludge digested in the digestion tank is further digested in the second digestion tank, solids and liquids are separated by gravity sedimentation, solids in the solid-liquid separated sludge are taken out as digested sludge, and separated water is desorbed. Removed as liquid.

[0003]

However, in the conventional configuration in which the first digestion tank and the second digestion tank are provided, there is a problem that a large installation area is required because the equipment becomes large. In addition, in recent years, the properties of sewage and wastewater flowing into a treatment facility tend to hardly settle, so that the concentration performance of the concentrator becomes unstable, and the concentration of the concentrated sludge fed into the first digester decreases. At the same time, there is a problem that the SS concentration of the desorbed liquid in the concentrator becomes high and the load on the subsequent water treatment step increases. In addition, since methane gas generated in the first and second digesters adheres to the periphery of the digested sludge, sedimentation of solids is hindered, the concentration of the digested sludge is reduced, and the sludge treatment performance in the next step is reduced. There was a problem to do.

[0004] The present invention solves the above-mentioned problems, and can reduce the installation area, reduce the amount of sludge by digestion, and stably concentrate sludge. It is an object to provide a concentrating device.

[0005]

In order to solve the above-mentioned problems, a sludge digestion / concentration apparatus of the present invention is provided with a reaction tank having an appropriate depth, and sludge is mainly condensed and settled on the bottom side in the reaction tank. A bed zone where sludge flows is formed on the upper side following the bed zone, a stirrer having a length over the blanket zone and the bed zone is provided in the reaction tank, and the blanket zone is communicated with the blanket zone. A sludge supply pipe is provided to connect the lower part and the upper part of the blanket zone, and a sludge circulation pipe is provided.A circulation pump is interposed in the middle of the sludge circulation pipe to communicate with the bottom of the reaction tank. It has a configuration in which a drawing pipe is provided and a desorbed liquid discharge pipe is provided so as to communicate with the upper side of the reaction tank following the blanket zone.

[0006] An umbrella-shaped gas-solid separator disposed so as to be immersed in a reaction tank above the blanket zone is provided so that the lower opening of the gas-solid separator surrounds the upper region of the blanket zone. The gas discharge pipe is provided in communication with the top of the separator.

[0007]

According to the above construction, raw sludge is supplied from the sludge supply pipe to the blanket zone in the reaction tank, and the stirrer is slowly rotated to slowly stir the raw sludge and digested sludge retained in the reaction tank. While mixing, the circulating pump is driven to supply digested sludge and raw sludge that accumulate in the lower part of the blanket zone to the upper part of the blanket zone through the sludge circulation pipe, and the digested sludge and raw sludge are directed downward in the blanket zone Stir and mix while circulating in a stream. In this state, the organic matter in the sludge is anaerobically digested to reduce the amount of sludge, and the anaerobic digestion of the sludge is promoted by stirring and mixing the sludge. Also, when methane gas or carbon dioxide gas generated during digestion floats as bubbles,
Part of the sludge adheres to the solid sludge particles, and the sludge particles tend to float together with the bubbles. However, in the blanket zone, the sludge circulates in a downward flow, so that the floating of the sludge particles is suppressed. Furthermore, the gas is separated from the sludge particles by slow stirring by the stirrer and mixing by circulation,
As the separated gas floats above the blanket zone, the sludge particles settle by gravity in the bed zone.

In the bed zone, the settling sludge is further digested, and the gas and the sludge particles are separated by slow stirring by the stirrer. Further, the separated gas floats to the top of the reaction tank through the blanket zone, and the separated sludge particles are compacted and concentrated. Further, the sludge particles floating in the blanket zone without being separated from the gas in the bed zone are gas-solid separated by stirring and mixing in the blanket zone.

Since the floating of sludge particles is suppressed in the blanket zone, the desorbed liquid staying in the reaction tank above the blanket zone has a reduced SS concentration and passes through the desorbed liquid discharge pipe through the reaction tank. It is discharged outside. The concentrated sludge that is concentrated and flows to the bottom of the bed zone is discharged to the outside of the reaction tank through a sludge drawing pipe.

Furthermore, the sludge particles floating above the blanket zone with the gas bubbles attached without being gas-solid separated in the blanket zone collide with the umbrella-shaped inclined inner wall surface of the gas-solid separator or gas-solid separation. Gas-solid separation by floating on the water surface formed in the vessel. further,
The gas separated from the sludge particles is discharged from the top of the gas-solid separator to the outside through the gas discharge pipe, and the sludge particles from which the gas has been separated are settled by gravity through the blanket zone to the bed zone.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a column 1 forming a reaction tank is formed at a predetermined depth, an inverted cone is formed at the bottom, and a center is formed at the lowest. The bottom of the column 1 is formed in the bed zone 2 while the bed zone 2 is formed.
Is formed in the blanket zone 3, and a refining zone 4 is formed in the upper portion following the blanket zone 3. A picket fence 5 serving as a stirrer is arranged inside the column 1, and the picket fence 5 has a length extending over the blanket zone 3 and the bed zone 2. In addition, the picket fence 5 is formed in a vertical lattice shape in which vertical aggregates 5a are arranged at appropriate intervals in the horizontal direction, and the lower end is formed in a chevron shape corresponding to the bottom shape of the column 1. Each aggregate 5a is formed of a round bar. The aggregate 5a is not limited to a round bar but may be a plate. Further, the picket fence 5 is rotatably provided around a vertical rotation support shaft 6 provided at the upper end, and a drive motor 7 is connected to the rotation support shaft 6.

A sludge supply pipe 8 is provided in communication with the blanket zone 3, and a sludge pump 9 is provided in the middle of the sludge supply pipe 8. In addition, a sludge circulation pipe 10 is provided so as to communicate the lower part and the upper part of the blanket zone 3, and a circulation pump 11 is provided in the middle of the sludge circulation pipe 10. Further, a sludge extraction pipe 12 is provided in communication with the bottom of the column 1, and a sludge extraction pump 13 is interposed in the middle of the sludge extraction pipe 12.

An overflow weir 14 is formed at the inner peripheral edge of the upper end opening of the column 1, and a desorbed liquid discharge pipe 15 communicating with the column 1 outside the overflow weir 14 is provided with a desorbed liquid at the tip end. It is provided in communication with the storage tank 16. An umbrella-shaped gas-solid separator 17 is immersed in the fining zone 4 of the column 1, and the lower opening of the gas-solid separator 17 surrounds an area above the blanket zone 3. Further, a gas discharge pipe 18 is provided in communication with the top of the gas-solid separator 17.
Communicates with the gas storage tank 19. Between the blanket zone 3 and the refining zone 4, a filter bed 20 for accelerating gas-solid separation is provided as necessary.

The operation of the above configuration will be described below. Raw sludge is supplied to the blanket zone 3 of the column 1 through the sludge supply pipe 8 by driving the sludge pump 9.
Then, the picket fence 5 is rotated at a low speed, for example, at 1 rpm, so that the raw sludge and the digested sludge retained in the column 1 are slowly stirred and mixed. The digested sludge and the raw sludge are supplied to the upper portion of the blanket zone 3 through the sludge circulation pipe 10, and the digested sludge and the raw sludge are circulated in the blanket zone 3 in a downward flow to be stirred and mixed. In this state, the organic matter in the sludge is anaerobically digested to reduce the amount of the sludge, and the anaerobic digestion of the sludge is promoted by stirring and mixing the sludge. In addition, when methane gas or carbon dioxide gas generated with anaerobic digestion floats as bubbles, a part of it adheres to solid sludge particles,
Although the sludge particles tend to float together with the air bubbles, in the blanket zone 3, since the sludge circulates in a downward flow, the rising of the sludge particles is suppressed. Further, in the blanket zone 3, the gas is separated from the sludge particles by slow stirring and mixing by the downward flow by the picket fence 5, and the separated gas floats to the clarification zone 4 and the sludge particles move to the bed zone 2 by gravity. Settles. The sludge particles floating in the fining zone 4 without gas-solid separation in the blanket zone 3 with gas bubbles attached thereto flow into the gas-solid separator 17 and are inclined in an umbrella shape of the gas-solid separator 17. Gas-solid separation is performed by collision with the inner wall surface or floating on the water surface formed inside the gas-solid separator 17.
The gas separated from the sludge particles is discharged to the outside through the gas discharge pipe 18 from the top of the gas-solid separator 17, and the separated sludge particles pass through the blanket zone 3 and settle in the bed zone 2 by gravity. I do. Further, the desorbed liquid 21 staying in the fining zone 4 flows into the desorbed liquid discharge pipe 15 over the overflow weir 14 and is supplied from the desorbed liquid discharge pipe 15 to the desorbed liquid storage tank 16.

Therefore, the floating of sludge particles is suppressed in the blanket zone 3, so that the desorbed liquid 21 staying in the fining zone 4 above the blanket zone 3 is S
The S concentration is low. If the SS concentration of the desorbed liquid 21 is too high, a filter bed 20 may be provided if necessary.
Filter the SS with.

In the bed zone 2, the settling sludge is further digested, and the picket fence 5
The gas and the sludge particles are separated by the gentle stirring by. Further, the separated gas floats to the fining zone 4 through the blanket zone 3, and the separated sludge particles are condensed and concentrated. Then, the concentrated sludge is driven from the bottom of the column 1 by the operation of the sludge extraction pump 13.
It is discharged outside through 12. At this time, since the bottom of the column 1 is formed in an inverted conical shape, the sludge is removed from the sludge extraction pipe 12.
The sludge which moves easily toward the opening of the bed zone and stays at the bottom of the bed zone 2 is uniformly extracted.

[0017]

As described above, according to the present invention, the sludge is circulated in the downward direction in the blanket zone and is slowly stirred by the stirrer, so that the floating of the sludge particles with air bubbles is suppressed. The anaerobic digestion can be promoted while the SS concentration of the desorbed solution can be reduced. In the bed zone, the gas is separated from the sludge particles and the sludge particles that settle by gravity can be concentrated by consolidation by slow stirring by the stirrer, thereby improving the sludge concentration rate. Furthermore, by digesting in the blanket zone and concentrating in the bed zone, sludge can be digested and concentrated in one tank, and the installation area for arranging equipment can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a sludge digestion / concentration apparatus showing one embodiment of the present invention.

[Explanation of symbols]

 1 Column 2 Bed zone 3 Blanket zone 5 Picket fence 8 Mud supply pipe 10 Sludge circulation pipe 12 Sludge withdrawal pipe 17 Gas-solid separator

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akio Toriyama 1-2-47 Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka Kubota Corporation (72) Inventor Ichiro Nakano 1 Shikitsuhigashi, Namiwa-ku, Osaka-shi, Osaka No. 2-47 Kubota Co., Ltd. (56) References JP-A-4-74597 (JP, A) JP-A 62-114699 (JP, U) JP-A 57-55513 (JP, U) JP-A 61-121998 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 11/04 WPI (DIALOG)

Claims (2)

(57) [Claims] 1. A reaction tank having an appropriate depth is provided, a bed zone is formed on a bottom side in the reaction tank, and a blanket zone is formed on an upper side following the bed zone, and a blanket zone and a bed are formed in the reaction tank. A stirrer having a length over the zone is provided, a sludge supply pipe is provided in communication with the blanket zone, a sludge circulation pipe is provided in communication with a lower part and an upper part of the blanket zone, and a middle part of the sludge circulation pipe is provided. A circulation pump is interposed in the sludge, and a sludge withdrawing pipe is provided in communication with the bottom of the reaction tank, and a desorbed liquid discharge pipe is provided in communication with an upper side of the reaction tank following the blanket zone. Digestion / concentration equipment. 2. An umbrella-shaped gas-solid separator immersed and disposed in a reaction tank above the blanket zone so that a lower opening of the gas-solid separator surrounds an upper region of the blanket zone. The sludge digestion / concentration apparatus according to claim 1, wherein a gas discharge pipe is provided in communication with the top of the separator.