JP2012035194A - Anaerobic treatment device and anaerobic treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anaerobic treatment device capable of decomposing organic substances efficiently.SOLUTION: The anaerobic treatment device 1 includes a granule tank 21 having a granule filling layer 21a filled with granules containing acid-producing bacteria and methanogenic bacteria. Waste water including organic substances is supplied from a lower part of the granule tank 21, and treatment water is discharged from an upper part of the granule tank 21 to outside of the granule tank 21. The anaerobic treatment device 1 further includes a stirring device 22 having a rotating shaft 22a extended along the vertical direction of the granule tank 21 and stirring water on the lower side of the granule filling layer 21a in the peripheral direction of the rotating shaft 22a. A stirring region 23 where water is stirred in the peripheral direction by the stirring by the stirring device 22 is formed on the lower side of the granule filling layer 21a. In the stirring region 23, the waste water including the organic substances is supplied to inside of the granule tank 21, and an upward flow region 24 is formed above the stirring region 23.

Description

  The present invention relates to an anaerobic treatment apparatus and an anaerobic treatment method.

  Conventionally, anaerobic microorganisms (e.g., wastewater from organic matter-containing wastewater (e.g., human waste, sewage, factory wastewater (wastewater from food factories, chemical factories, electronics industry factories, pulp factories, etc.)) By treating anaerobic microorganisms with anaerobic microorganisms in an anaerobic microorganism in a granule tank containing granular sludge containing acid-producing bacteria, methanogens, etc.) Organic substances are removed from the wastewater contained. In anaerobic treatment, for example, organic substances (for example, proteins and polysaccharides) in waste water containing organic substances are converted to methane-producing bacteria through hydrolysis, reduction of molecular weight and generation of organic acids (for example, acetic acid) by acid-producing bacteria. Is decomposed into gas (for example, methane gas, carbon dioxide gas, etc.), thereby removing the organic matter from the organic matter-containing wastewater.

As an anaerobic treatment apparatus, for example, as shown in FIG. 3, a granule tank 102 having a granule packed bed 102a filled with granules and an agitator 103 for stirring the entire granule packed bed 102a are provided. The organic substance-containing wastewater 100A is supplied into the granule tank 102 from the lower part of the granule tank 102, and the organic substance-containing wastewater 100A is anaerobically treated by anaerobic microorganisms in the granule tank 102. 100B is obtained, and the anaerobic treated water 100B is discharged from the upper part of the granule tank 102 to the outside of the granule tank 102, and bubbles which are gas 100C generated by the anaerobic treatment are attached. From the granule raised by buoyancy in the water of the granule tank 102 by the gas 1 By 0C is removed, anaerobic treatment apparatus 101 of provided with a gas dome 104 to precipitate granule is known (e.g., Patent Document 1).
The anaerobic treatment device 101 has a structure in which the contact efficiency of the organic matter and anaerobic microorganisms is enhanced by agitating the entire granule packed bed 102a by the agitation device 103, thereby promoting the anaerobic treatment.

Japanese Patent No. 2952304

  However, such an anaerobic treatment apparatus has a problem that organic substances cannot be sufficiently efficiently removed from organic substance-containing wastewater.

  This invention makes it a subject to remove organic substance from organic substance containing wastewater fully efficiently in view of the said problem.

The present invention is provided with a granule tank having a granule packed bed filled with granules containing acid-producing bacteria and methanogens, and contains an organic substance in the granule tank from the lower part of the granule tank. Wastewater is supplied, and anaerobic treatment water is obtained by anaerobically treating the organic wastewater containing acid-producing bacteria and methanogens in the granule tank, and the anaerobic treated water from the upper part of the granule tank to the outside of the granule tank. Is an anaerobic treatment device configured to be discharged,
A rotating shaft extending along the vertical direction of the granule tank; and a stirring device that stirs water below the granule packed bed in the circumferential direction of the rotating shaft. A stirring region in which water is stirred in the circumferential direction by stirring by the stirring device is formed in the lower portion, and the organic substance-containing wastewater is supplied into the granule tank in the stirring region, and above the stirring region The anaerobic treatment apparatus is characterized in that an upward flow region in which water flows upward is formed.

According to such an anaerobic treatment apparatus, organic substances (for example, proteins and polysaccharides) and acid-producing bacteria are easily brought into contact with each other in the lower part (stirring region) of the granule packed bed by stirring by the stirring apparatus. Acid-producing bacteria become the preferred species, and the conditions under which organic acid generation is favorably performed can be achieved. In addition, since the entire granule packed bed is not uniformly stirred, the organic acid generated in the lower part of the granule packed bed is sequentially supplied to the upward flow region, and the conditions for good methane fermentation can be achieved. . Therefore, the reaction efficiency is improved. Furthermore, the amount of a pH adjusting agent such as alkali can be reduced.
Therefore, according to such an anaerobic treatment apparatus, first, the organic acid is actively generated in the stirring region as compared with the upward flow region, while the methane is actively generated in the upward flow region. Therefore, organic substances can be removed sufficiently efficiently from the organic substance-containing wastewater. Moreover, since organic substances can be removed sufficiently efficiently, there is an advantage that the granule tank can be made compact.

On the other hand, in the anaerobic treatment device that stirs the entire granule packed bed with the stirring device as in Patent Document 1, the granule packed bed generates organic acid by stirring the entire region where the granule exists with the stirring device. It is difficult to separate into a region where the methane is actively generated and a region where the methane production is actively performed. Therefore, such an anaerobic treatment apparatus cannot efficiently remove organic substances from organic substance-containing wastewater.
In addition, in an anaerobic treatment device that is not provided with a stirring device, the concentration of organic matter increases in the vicinity of the portion of the granule tank where the organic matter-containing wastewater is supplied, and organic acids are likely to be produced by acid-producing bacteria. As a result, the pH is locally lowered, and the activity of the methanogenic bacteria in the portion where the pH is locally lowered is lowered. Furthermore, the contact efficiency between organic matter and anaerobic microorganisms is low. Therefore, such an anaerobic treatment apparatus cannot efficiently remove organic substances from organic substance-containing wastewater.

  Further, in the anaerobic treatment apparatus according to the present invention, preferably, the anaerobic treated water discharged from the granule tank is treated with solid-liquid separation treated water having a lower granule content than the anaerobic treated water, and the anaerobic treatment water. A solid-liquid separation unit for solid-liquid separation into concentrated water having a higher granule content than the treated water is provided, and is configured to return the concentrated water to the upward flow region without passing through the stirring region. It becomes.

  Since the granules in the treated water discharged from the granule tank have a larger ratio of the amount of methanogenic bacteria to the amount of acid producing bacteria than the stirring region, according to such an anaerobic treatment apparatus, In the upward flow region, the concentration of methanogens increases, and organic acids and monosaccharides are easily contacted with methanogens and decomposed into methane gas and carbon dioxide gas. There is an advantage that can be removed more efficiently.

  Moreover, this invention exists in the anaerobic processing method characterized by removing an organic substance from an organic substance containing wastewater using the said anaerobic processing apparatus.

  As described above, according to the present invention, there is an effect that organic substances can be sufficiently efficiently removed from organic substance-containing wastewater.

  In addition, in an anaerobic treatment apparatus using a normal granule tank, a distribution mechanism for evenly flowing raw water into the granule tank is often installed in order to make the concentration of granules and organic substances at the bottom uniform. However, according to the present invention, there is an advantage that even if the distribution mechanism is simplified, the concentration of the granule and organic matter at the bottom can be made uniform by the stirring device.

1 is a schematic diagram of an anaerobic treatment apparatus according to an embodiment. Schematic of the anaerobic processing part in the anaerobic processing apparatus which concerns on one Embodiment. Schematic of the conventional anaerobic processing apparatus.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the anaerobic treatment apparatus 1 of the present embodiment is provided with a granule tank 21 having a granule packed bed 21a filled with granules containing acid-producing bacteria and methanogens, An anaerobic treatment unit 2 is provided in the granule tank 21 to obtain anaerobic treated water and biogas D by anaerobically treating the organic substance-containing wastewater A by acid producing bacteria and methanogenic bacteria. On the other hand, the granule tank 21 is not provided with a gas dome, that is, a gas-solid-liquid separation means.
The anaerobic process means a process of decomposing an organic substance contained in the organic substance-containing wastewater A with acid-producing bacteria and methane-producing bacteria without using oxygen. In the anaerobic process, as the biogas D, methane, carbon dioxide gas, etc. A gas containing is produced.

  Moreover, the anaerobic treatment apparatus 1 of the present embodiment uses the anaerobic treated water discharged from the granule tank 21 as a solid-liquid separation treated water B having a lower granule content than the anaerobic treated water, and the anaerobic treatment. The solid-liquid separation part 3 which solid-liquid-separates into the concentrated water C whose granule content rate is higher than water is provided.

Furthermore, the anaerobic treatment apparatus 1 of the present embodiment is configured such that the organic substance-containing wastewater A is supplied into the granule tank 21 from the lower part of the granule tank 21.
Moreover, the anaerobic treatment apparatus 1 of the present embodiment is configured such that the anaerobic treated water is discharged from the upper part of the granule tank 21 to the outside of the granule tank 21. Specifically, the treatment for removing the gas from the granules in the anaerobic treated water is not intentionally performed in the granule tank 21, and the anaerobic treated water is discharged from the upper part of the granule tank 21 to the outside of the granule tank 21. It is configured to be discharged.

  Moreover, in the anaerobic treatment apparatus 1 of the present embodiment, the anaerobic treated water discharged from the granule tank 21 is transferred to the solid-liquid separation unit 3, and the solid-liquid separated treated water B is stored in the solid-liquid separated treated water storage tank (FIG. The concentrated water C is transferred to the concentrated water storage tank (not shown) and the granule tank 21, and the biogas D is transferred to the biogas storage tank (not shown). It becomes.

  Furthermore, the anaerobic treatment apparatus 1 of the present embodiment includes a wastewater transfer path 4a for transferring the organic matter-containing wastewater A to the granule tank 21, an anaerobic treated water transfer path 4b for transferring the anaerobic treated water to the solid-liquid separation unit 3, and Solid-liquid separation treated water transfer path 4c for transferring solid-liquid separation treated water B to a solid-liquid separation treated water storage tank (not shown), and concentrated water for transferring concentrated water C to a concentrated water storage tank (not shown). A transfer path 4d, a concentrated water return path 4e for transferring (returning) concentrated water C to the anaerobic treatment unit 2, and a biogas transfer path 4f for transferring biogas D to a biogas storage tank (not shown). It becomes.

  The organic matter-containing wastewater A is not particularly limited as long as it contains organic matter that can be biodegraded by the anaerobic microorganisms. Examples of the organic matter-containing wastewater A include human waste wastewater, sewage, Factory waste water (waste water from factories such as food factories, chemical factories, electronics industry factories, pulp factories). The BOD concentration of the organic matter-containing wastewater A at the inlet of the granule tank 21 (inlet into the granule tank of the organic matter-containing wastewater A) is, for example, 10 to 10,000 mg / L or less, more specifically 20 to 2000 mg / L. Moreover, the CODcr concentration of the organic substance-containing wastewater A at the inlet of the granule tank 21 is 20 to 20000 mg / L or less, and more specifically 40 to 4000 mg / L.

  In the granule tank 21, the anaerobic treatment unit 2 is preferably filled with 3/4 or more of the water level from the bottom during operation (when wastewater is supplied), more preferably the tank. It is comprised so that the substantially whole inside may be filled.

  The anaerobic treatment unit 2 has a rotating shaft 22a extending in the vertical direction of the granule tank 21, and the water below the granule packed bed 21a is stirred in the circumferential direction of the rotating shaft to form a stirring region 23. The stirring device 22 is provided. The rotating shaft 22a is configured to rotate.

  The granule tank 21 is formed in a cylindrical shape.

  The anaerobic treatment unit 2 is formed such that the rotating shaft 22a and the virtual axis in the cylindrical granule tank 21 are substantially coaxial.

Furthermore, the anaerobic treatment unit 2 is formed with a stirring region 23 in which water is stirred in the circumferential direction by stirring by the stirring device 22 below the granule packed bed 21a. The organic substance-containing waste water A is supplied into the tank 21, and an upward flow region 24 in which water flows upward is formed above the stirring region 23. Since the anaerobic treatment unit 2 has such a configuration, the ratio of the amount of acid producing bacteria to the amount of methanogenic bacteria in the stirring region 23 is relatively large with respect to the ratio in the upward flow region 24. And a ratio of the amount of methanogenic bacteria to the amount of acid producing bacteria in the upward flow area 24 is relatively larger than the ratio in the stirring area 23. Can be formed in the upward flow region 24.
In the granule packed bed 21a, the concentration of granules in the stirring region 23 and the upward flow region 24 is preferably 20,000 to 100,000 mg-SS / L, more preferably 30,000 to 100,000 mg-SS / L.

  In addition, the anaerobic treatment unit 2 may adjust the pH in the vicinity of the raw water supply unit in the stirring region 23, in the vicinity of the boundary between the stirring region 23 and the upward flow region 24, and in the vicinity of the treated water outflow portion in the upward flow region 24 as necessary. Each is provided with a pH meter (not shown) for measuring pH and configured to measure pH. The anaerobic treatment unit 2 is preferably provided with a pH adjusting agent addition mechanism (not shown) for adding a pH adjusting agent to the stirring region 23 and the upward flow region 24. The position of the pH-adjusting drug addition port is preferably provided in the stirring region 23 and the upward flow region 24 and adjusted for each region. The pH range is adjusted to 6 to 8 in the upward flow region 24, but there is no problem even if it is 6 or less in the stirring region 23.

  The stirring device 22 includes a stirring blade 22b in which a paddle-shaped blade is installed so that its surface is in a vertical direction. The slats are configured to push water in the circumferential direction of the rotary shaft 22a by rotating the rotary shaft 22a.

  In addition, the anaerobic treatment unit 2 is preferably within the range from the tank inner bottom surface of the granule tank 21 to a height of 1/3 of the water surface height L, more preferably to a height of 1/4. The entire wing 22b is configured to be accommodated (size symbols are shown in FIG. 2).

Further, the anaerobic treatment unit 2 is configured such that the blade height of the stirring blade 22b (distance between the upper side and the lower side of the stirring blade 22b) with respect to the water depth (height from the bottom surface inside the tank to the water surface) L of the granule tank 21. The ratio of h is preferably 0.1 to 0.4, more preferably 0.15 to 0.2.
The anaerobic treatment apparatus 1 of the present embodiment can increase the agitation blade 22b with respect to the portion of the granule tank 21 that can accommodate water when L / h is 0.1 or more. There exists an advantage that the water of the lower part in the granule tank 21 can fully be stirred.
Moreover, since the water of the upper part in the said granule tank 21 becomes difficult for the anaerobic processing apparatus 1 of this embodiment to be 0.4 or less because L / h is 0.4 or less, the upper and lower sides of the water of the granule tank 21 are the top and bottom. Mixing in the direction is less likely to occur, and there is an advantage that the difference between the acid-producing bacteria layer and the methanogenic bacteria layer can be increased with respect to the ratio of the amount of acid-producing bacteria to the amount of methanogen. Further, the stirring blade 22b is less likely to contact the inner bottom surface of the granule tank 21, and there is an advantage that the destruction of the granules can be suppressed as much as possible.

Further, the anaerobic treatment unit 2 is configured such that the ratio (d / D) of the blade diameter of the stirring blade 22b (distance from the axis of the rotating shaft 22a to the tip of the stirring blade 22b) d with respect to the inner diameter D of the granule tank 21. However, Preferably it is 0.6-0.9, More preferably, it is 0.7-0.8.
Since the anaerobic treatment apparatus 1 of the present embodiment has a d / D of 0.6 or more, the stirring blade 22b can be enlarged with respect to the portion of the granule tank 21 that can accommodate water. There exists an advantage that the water of the lower part in the granule tank 21 can fully be stirred. Moreover, since d / D is 0.9 or less, the stirring blade 22b becomes difficult to contact the inner peripheral wall surface of the granule tank 21, and there is an advantage that the destruction of the granule can be suppressed as much as possible.

The rotation speed of the stirring blade 22b is preferably 1 to 30 rpm, more preferably 2 to 20 rpm.
The anaerobic treatment apparatus 1 of the present embodiment has an advantage that the water in the lower part in the granule tank 21 can be sufficiently stirred when the rotational speed is 1 rpm or more.
In addition, the anaerobic treatment device 1 of the present embodiment has a rotational speed of 30 rpm or less, so that the impact force generated when the stirring blade 21b collides with the granule is suppressed, so that the granule is not easily crushed. There are advantages. Moreover, mixing of water in the vertical direction of the upper part of the stirring blade of the granule tank 21 is less likely to occur, and regarding the ratio of the amount of acid producing bacteria to the amount of methanogenic bacteria, the difference between the acid producing bacteria layer and the methanogenic bacteria layer. There is an advantage that can be increased.

  The solid-liquid separation unit 3 includes a gravity sedimentation tank 31 that generates solid-liquid separation treated water B and concentrated water C from anaerobic treated water by gravity sedimentation of granules.

  The anaerobic treatment apparatus 1 according to this embodiment is attached to the granule transferred to the gravity settling tank 31 and separated in the gravity settling tank 31, and anaerobic in the gravity settling tank 31. The biogas D generated by the processing is configured to be transferred to a biogas storage tank (not shown).

  Moreover, the anaerobic treatment apparatus 1 of the present embodiment is configured to return the concentrated water C to the upward flow region 24 without passing through the stirring region 23. Specifically, the concentrated water C is returned to a position higher than the upper end of the stirring blade.

  The anaerobic treatment apparatus of the present embodiment is configured as described above. Next, the anaerobic treatment method of the present embodiment will be described.

In the anaerobic treatment method of the present embodiment, the organic matter is removed from the organic matter-containing wastewater A using the solid-liquid separation device 1 of the present embodiment.
Specifically, in the anaerobic treatment method of the present embodiment, the organic substance-containing wastewater A is supplied into the granule tank 21 from the lower part of the granule tank 21. Next, a stirring region 23 in which water is stirred in the circumferential direction by stirring by the stirring device 22 is formed in the lower part of the granule tank 21 by stirring by the stirring device 22, and above the stirring region 23. The organic matter-containing waste water A is anaerobically treated with acid-producing bacteria and methanogens while forming an upward flow region 24 in which water flows in an upward flow to obtain anaerobic treated water.

  Since the anaerobic treatment apparatus and the anaerobic treatment method of the present embodiment are configured as described above, the following advantages are provided in addition to the efficiency of the processing by the functional sharing between the stirring region 23 and the upward flow region 24. Is.

That is, the anaerobic treatment apparatus 1 of the present embodiment is such that the process of removing the gas from the granules in the anaerobic treated water is not intentionally performed in the granule tank, and the granule tank is started from the upper part of the granule tank 21. By being configured so that the anaerobic treated water is discharged to the outside of 21, that is, by not having a gas-solid-liquid separation means, the granule is filled up to just below the water surface of the granule tank 21. As a result of the expansion of the reaction region, the processing amount per unit volume of the granule tank 21 can be increased.
On the other hand, in an anaerobic treatment apparatus in which a gas-solid-liquid separation means is provided in a granule tank, the amount of treatment per unit volume is large due to the large proportion of areas where no granule exists and does not contribute to decomposition of organic matter Becomes smaller.
Therefore, in the anaerobic treatment apparatus of this embodiment, organic substances can be efficiently removed from organic substance-containing wastewater.

In addition, although the anaerobic processing apparatus and the anaerobic processing method of this embodiment had the said structure, the anaerobic processing apparatus and the anaerobic processing method of this invention are not limited to the said structure, A design change is possible suitably. .
For example, the stirring blade 22b is not limited to a single vertical paddle blade, but may be a two-stage cross paddle blade, a lattice blade, a gate blade, an inclined paddle blade, a propeller blade, or a three-blade retracted blade.

  In addition, the anaerobic treatment device 1 of the present embodiment distributes the water in the vertical direction between the stirring region 23 and the upward flow region 24 in order to more reliably separate the stirring region 23 and the upward flow region 24. A suppressing member (baffle plate, rod-shaped member, etc.) may be provided.

  Furthermore, the anaerobic treatment apparatus 1 of the present embodiment is configured such that the process of removing gas from the granules in the anaerobic treated water is not intentionally performed in the granule tank 21. The anaerobic treatment apparatus 1 may be configured such that the treatment for removing gas from the granules in the anaerobic treated water is intentionally performed in the granule tank 21. That is, the anaerobic treatment apparatus 1 of the present invention may be provided with gas-solid-liquid separation means for removing gas from granules in the granule tank 21.

  1: Anaerobic treatment device, 2: Anaerobic treatment unit, 3: Solid-liquid separation unit, 4a: Waste water transfer route, 4b: Anaerobic treatment water transfer route, 4c: Solid-liquid separation treated water transfer route, 4d: Concentrated water transfer route, 4e: Concentrated water return path, 4f: Biogas transfer path, 21: Granule tank, 21a: Granule packed bed, 22: Stirring device, 22a: Rotating shaft, 22b: Stirring blade, 23: Stirring zone, 24: Top Countercurrent region, 31: gravity sedimentation tank, A: organic matter-containing wastewater, B: solid-liquid separation treated water, C: concentrated water, D: biogas, 101: anaerobic treatment device, 102: granule tank, 102a: granule Packed bed, 103: Stirrer, 104: Gas dome, 100A: Waste water containing organic matter, 100B: Anaerobic treated water, 100C: Gas

Claims (3)

A granule tank having a granule packed bed filled with granules containing acid-producing bacteria and methanogen is provided, and organic substance-containing wastewater is supplied into the granule tank from the lower part of the granule tank. The anaerobic treated water is obtained by anaerobically treating the organic waste water with acid producing bacteria and methanogenic bacteria in the granule tank, and the anaerobic treated water is discharged from the upper part of the granule tank to the outside of the granule tank. An anaerobic treatment device configured as described above,
A rotating shaft extending along the vertical direction of the granule tank; and a stirring device that stirs water below the granule packed bed in the circumferential direction of the rotating shaft. A stirring region in which water is stirred in the circumferential direction by stirring by the stirring device is formed in the lower portion, and the organic substance-containing wastewater is supplied into the granule tank in the stirring region, and above the stirring region An anaerobic treatment device characterized in that an upward flow region in which water flows upward is formed.   Anaerobic treated water discharged from the granule tank into solid-liquid separation treated water having a lower granule content than the anaerobic treated water and concentrated water having a higher granule content than the anaerobic treated water. The anaerobic treatment apparatus according to claim 1, further comprising a solid-liquid separation unit that performs solid-liquid separation, and configured to return the concentrated water to the upward flow region without passing through the stirring region.   An anaerobic treatment method comprising removing organic matter from organic matter-containing wastewater using the anaerobic treatment device according to claim 1.

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