JPS60235696A - Anaerobic digestion vessel - Google Patents

Abstract

PURPOSE:To carry out efficient anaerobic digestion with a small setting area by providing two partition plates at the upper part of a digestion vessel to separate the vessel into a liquid mixture part consisting of an ascending part and a descending part, and providing a rectifying plate extending from the lower part of the solid-liquid separation part to the liquid mixture part. CONSTITUTION:A digestion vessel 1 having an untreated liquid inflow part 2 at the bottom, a partition plate 3 extending from above the liquid surface of the vessel 1 into the liquid and separating the upper part of the vessel 1 into a solid-liquid separation part 5 and a hermetic liquid mixture part 4, a treated liquid pipe 14 communicating with the upper part of the solid- liquid separation part, and a gas discharge pipe 15 communicating with the upper part of the liquid mixture part are provided. And a partition plate 6 whose upper end is situated under the liquid surface of the liquid mixture part, whose lower part is inclined downward while keeping an interval from the leading end of the partition plate 3 and extends to the lower part of the solid-liquid separation part, and which separates the liquid mixture part into an ascending part 7 and a descending part 8, and a rectifying plate 10 are provided. Namely, the flow of generated gas into the solid-liquid separation part is prevented, and the sludge settled at the solid-liquid separation part is returned to the digestion part by utilizing a spiral flow of the generated gas. Accordingly, the anaerobic digestion is efficiently carried out with a small setting area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an anaerobic digestion tank used for water treatment etc., and particularly to a sludge blanket type anaerobic digestion tank.

[Prior art]

The sludge blanket type anaerobic digestion tank forms a sludge blanket with sludge mainly composed of anaerobic bacteria and brings it into contact with waste liquid to perform anaerobic digestion, but the gas generated during digestion rises and becomes sludge. Since the blanket is disturbed and solid-liquid separation cannot be performed, the digestion reaction section and the solid-liquid separation section are divided. Some of these digesters have a solid-liquid separation section partitioned into an inverted triangular cross-section by partition plates with an inclination of 45 degrees (USPN α4).
253956), in this device, the sludge in the solid-liquid separation section is
As the sludge flows into the digestion reaction section due to natural settling, if the properties of the sludge deteriorate and the settling properties become poor, the sludge will not be returned sufficiently, and sludge accumulation and scum will occur in the settling section, causing the set load to decrease. There was a problem that the vehicle could not be driven normally.

[Purpose of the invention]

This invention is intended to solve the above-mentioned problems. Two partition plates are provided at the top of the digester to divide the tank into a mixed liquid section and a solid-liquid separation section consisting of an ascending section and a descending section. By providing a rectifying plate that extends from the bottom of the separation section to the mixed liquid section, it is possible to prevent the generated gas from flowing into the solid-liquid separation section, and to use the swirling flow of the generated gas to digest the settled sludge in the solid-liquid separation section. The purpose of this project is to provide an anaerobic digestion tank that can be returned to the department and perform efficient anaerobic digestion in a small footprint.

[Structure of the invention]

The present invention provides a digestion tank having a raw liquid inlet at the bottom, and a first pipe extending into the liquid from above the liquid level of the digestion tank and dividing the upper part of the digestion tank into a solid-liquid part and a closed mixed liquid part. A partition plate, a processing liquid pipe communicating with the upper part of the solid-liquid separation part, a gas discharge pipe communicating with the upper part of the mixed liquid part, and a first partition plate whose upper end is located below the liquid level of the mixed liquid part and whose lower part is the first partition plate. a second partition plate that is a downwardly inclined part maintaining a distance from the tip of the solid-liquid separation part and extends to the bottom of the solid-liquid separation part and divides the mixed liquid part into an ascending part and a descending part;
The second partition plate is inclined downwardly in a direction intersecting the second partition plate, and the second
The anaerobic digestion tank is characterized by having a rectifying curve extending from the lower part of the solid-liquid separation part to the mixed liquid part while keeping a distance from the lower end of the partition plate.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to embodiments of the drawings.

The drawing is a vertical sectional view of an anaerobic digestion tank according to an embodiment of the present invention. In the drawings, reference numeral 1 denotes a digestion tank consisting of a rectangular parallelepiped-shaped container, and porous tubular stock solution inflow portions 2 are uniformly provided over the entire bottom surface. A first partition plate 3 extending from above the liquid level into the liquid is provided at the top of the digestion tank 1, and with this partition plate 3, the top of the digestion tank 1 is divided into a closed mixed liquid section 4 and an open solid-liquid separation section. It is divided into section 5. A second partition plate 6 is provided below the liquid level of the mixed liquid part 4, and its lower part becomes a downwardly inclined part 6a, keeping a distance from the lower end of the partition plate 3, and its lower end is connected to the solid-liquid separation part 5. It extends to the bottom. The mixed liquid section 4 is divided into an ascending section 7 and a descending section 8 by the partition plate 6 . The slope angle α of the slope portion 6a is 45″ or more,
The cross-sectional area of the opening 9 at the lower part of the first and second partition plates 3 and 6 is larger than the cross-sectional area of the rising part 7.

At the bottom of the solid-liquid separator 5, a rectifying plate 10 is provided which is inclined downward from one side wall 1a of the digestion tank 1 in a direction intersecting the inclined part 6a of the partition plate 6, while maintaining a distance from the lower end of the partition plate 6. and extends to the mixed liquid section 4. The inclination angle β of the current plate 10 is 45°
As described above, the opening 11 between the partition plate 6 and the opening 11 is made larger than the cross-sectional area of the rising portion 7. The lower part of the current plate 10 forms an inclined part 10a that is inclined in the opposite direction and extends to the side wall 1a, and a digester part 12 is formed on the lower side of the inclined part 10a.

The entire mixed liquid section 4 consisting of the rising section 7 and the descending section 8 and the digestion section 12 constitute a digestion reaction section. 13 is a raw solution pipe connected to the raw solution inflow section 2; 14 is a processing liquid pipe connected to the upper part of the solid-liquid separation section 5; 15 is a gas discharge pipe connected to the upper part of the mixed liquid section 4; 16 is the bottom of the digestion tank 1. The sludge removal bit provided at 17 is a sludge removal pipe.

In the above configuration, the stock solution is supplied from the stock solution pipe 13 and is caused to flow into the digestion tank 1 from the stock solution inflow section 2.

When anaerobic digestion is performed, the raw solution 4 is mixed with sludge in the digestion section 12, and the organic matter is decomposed mainly by the action of acid-producing bacteria to produce organic acids, and further, the organic acids are decomposed by the action of methanogens. Methane is produced.

In the mixed liquid section 4, due to the buoyancy of the gas generated, the mixed liquid, that is, the treated liquid that has undergone anaerobic treatment, rises in the rising section 7, and the gas is separated at the upper part. The mixed liquid from which the gas has been separated descends through the descending section 8 and enters the lower part of the solid-liquid separating section 5, and a part of it ascends through the solid-liquid separating section 5, but most of it goes down along with the settled sludge in the solid-liquid separating section 5. It descends from the lower part of the solid-liquid separation section 5 along the rectifying plate 10 and circulates to the mixed liquid section 4. Mixing of sludge from the liquid mixture part 4 to the digestion part 12 is carried out when the tip of the rectifying plate IO is connected to the rising part 7.
Since the cross-sectional area of the sludge is larger than the cross-sectional area of can.

A sludge blanket 5a is also formed in the solid-liquid separation section 5 by the sludge entrained in the mixed liquid, and while the mixed liquid flowing in portions from the descending section 8 ascends the sludge blanket 5a, the solid content of the sludge is transferred to the sludge blanket. 5a, and the separated liquid is taken out from the processing liquid pipe 14 as a processing liquid. When the cross-sectional area of the opening 9 is larger than the cross-sectional area of the rising portion 7, the sludge blanket 5a is less disturbed and the solid-liquid separability is improved. A portion of the sludge blanket 5a flows into the mixed liquid section 4 from the opening 11 together with the mixed liquid as returned sludge. Providing the inclined plate 18 in the solid-liquid separation section 5 increases the solid-liquid separation effect.

Furthermore, even if the gas generated in the digestion section 12 becomes abnormally large and the sludge blanket in the digestion section 12 is destroyed and a large amount of sludge is contained in the mixed liquid, the sludge will be effectively separated by the solid-liquid separation section 5. The anaerobic treatment can be maintained satisfactorily since the anaerobic treatment is carried out and returned to the digestion section 12 again.

Excess sludge is removed from the sludge pit 16 provided at the bottom of the digestion tank 1.
The sludge is concentrated and drained from the sludge pipe 17.

The gas collected in the upper part of the liquid mixture part 4 is discharged from the gas discharge pipe 15.

In the above-described anaerobic digestion tank, the gas generated in the digestion section 12 flows into the mixed liquid section 4 through the rectifier plate 10, and the gas generated in the digestion section 12 flows into the mixed liquid section 4.
Since the gas is blocked by the partition plate 6 and moves up the rising section 7,
Gas does not flow into the solid-liquid separation section 5, and the sludge blanket 5a is not disturbed. Therefore, even when the solid-liquid separation section 5 is disposed above the digestion section 12, solid-liquid separation can be performed sufficiently. When there is no inclined portion IQa of the rectifier FilO, the upper part of the rectifier plate IO blocks the gas from flowing into the solid-liquid separation section, and the same effect as described above can be obtained.

In addition, the mixed liquid rises in the ascending part 7 and descends in the descending part 8 due to the buoyant force of the gas, and the settled sludge in the solid-liquid separation part 5 is returned to the mixed liquid part 4 by the swirling force, so the sludge is removed without power. It is returned and there is no accumulation of sludge or generation of scum. When the amount of generated gas is insufficient, the gas is circulated from the gas discharge pipe 15 to the mixed liquid section 4 to obtain the required upward flow rate.

In the above embodiments, a rectangular parallelepiped digester 1 is shown, but it may be cylindrical or other shape. In the case of a cylindrical shape, the solid-liquid separation section 5 is provided in the center with 18 in the drawing as the central axis. Alternatively, the rising portion 7 may be provided in the center with 1b as the central axis.

As for the digestion reaction section, it is also possible to install or introduce fillers inside, attach sludge to them, and perform digestion as a fixed bed or a fluidized bed. Furthermore, the solid-liquid separation section 5 may be maintained at reduced pressure.

The present invention can be used as an anaerobic digestion tank for treating organic waste liquid, sewage sludge, human waste, and other raw solutions suitable for anaerobic digestion.

〔Effect of the invention〕

According to this invention, two partition plates are provided in the upper part of the digester to divide the tank into a mixed liquid part and a solid-liquid separation part consisting of an ascending part and a descending part. By installing a rectifying plate that extends, it prevents the generated gas from flowing into the solid-liquid separation section, and uses the swirling flow of the generated gas to return the settled sludge in the solid-liquid separation section to the digestion reaction section, making it possible to reduce the size of small installations. Efficient anaerobic digestion can be performed in the area,
It also has the effect of efficiently collecting generated gas and reducing the number of sealed parts.

[Brief explanation of drawings]

The drawing is a cross-sectional view of the embodiment, in which 1 is a digestion tank, 2 is a raw liquid inflow part, 3 and 6 are partition plates, 4 is a mixed liquid part, 5 is a solid-liquid separation part, 7 is a rising part, and 8 is a descending part. , 10 is a rectifier plate, 12 is a digestion section, 13 is a stock solution pipe, ] 4 is a processing liquid pipe, and 15 is a gas discharge pipe. Agent Patent Attorney Sei Yanagihara

Claims (5)

[Claims] (1) A digestion tank having a raw liquid inflow section at the bottom, and a first partition plate that extends from above the liquid surface of the digestion tank into the liquid and divides the upper part of the digestion tank into a solid-liquid separation section and a closed mixed liquid section. , a processing liquid pipe connected to the upper part of the liquid separation part, a gas discharge pipe connected to the upper part of the mixed liquid part, the upper end of which is located below the liquid level of the mixed liquid part, and the lower part of which is the tip of the first partition plate. a second partition plate extending to the bottom of the solid-liquid separation section as a downwardly inclined section spaced apart from the solid-liquid separation section and dividing the mixed liquid section into an ascending section and a descending section;
An anaerobic system comprising: a rectifying plate that is inclined downward in a direction intersecting with the second partition plate and extends from the lower part of the solid-liquid separation section to the mixed liquid section while keeping a distance from the lower end of the second partition plate. Digestion tank. (2) The inclined part of the second partition plate and the angle of inclination of the rectifying plate are 4
The anaerobic digestion tank according to claim 1, wherein the angle is 5° or more. (3) Claims 1 or 2 in which the cross-sectional area of the opening formed between the first and second partition plates and between the second partition plate and the current plate is larger than the cross-sectional area of the rising part. Anaerobic digester as described. (4) The anaerobic digestion tank according to any one of claims 1 to 3, wherein the baffle plate has an inclined portion inclined in the opposite direction at the lower part. (5) The anaerobic digestion tank according to any one of claims 1 to 4, wherein the digestion tank has sludge removal means at the bottom.