JP2017023943A - Anaerobic fermentation method of waste water, microorganism carrier for anaerobic fermentation, and anaerobic fermentation treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anaerobic fermentation method of waste water, a microorganism carrier for the anaerobic fermentation, and an anaerobic fermentation treatment apparatus, enabling excellent water quality to be obtained only by the anaerobic fermentation.SOLUTION: The anaerobic fermentation method of waste water is provided in which waste water 14 is supplied from a position of a reaction tank 12 lower than a fixed filter bed 22 disposed inside the reaction tank 12 and treated water 18 is discharged from an upper portion of the reaction tank 12 while treating the waste water 14 by anaerobic fermentation with a sludge composed of microorganism in the reaction tank 12. In the anaerobic fermentation method of waste water, the treated water 18 is solid-liquid separated to recover the sludge and the sludge is solidified to form a microorganism carrier 46, followed by disposing the microorganism carrier 46 on an upper portion of the fixed filter bed (fixed filter bed 22a).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wastewater anaerobic fermentation treatment method, a microorganism carrier for anaerobic fermentation treatment, and an anaerobic fermentation treatment apparatus.

  Anaerobic fermentation is a low-cost water treatment technique that does not require aeration like aerobic treatment (see Patent Document 1). This anaerobic fermentation treatment is effective for the treatment of wastewater with a high organic matter concentration, but its effect is limited for wastewater with a medium to low organic matter concentration. For this reason, an aerobic treatment was necessary after the anaerobic fermentation treatment in order to obtain good treated water quality.

JP2013-240768A

  However, in an area where the power situation is not good, it is difficult to obtain power for constantly performing an aerobic treatment, and it is required to have a better treated water quality only by anaerobic fermentation treatment.

  Then, an object of this invention is to provide the anaerobic fermentation processing method of the waste_water | drain which can obtain a favorable treated water quality only by anaerobic fermentation processing, the microorganism carrier for anaerobic fermentation processing, and an anaerobic fermentation processing apparatus.

  In order to achieve the above object, the method for anaerobic fermentation of wastewater according to the present invention firstly supplies wastewater from the position of the reaction tank that is lower than the fixed filter bed disposed inside the reaction tank, In the anaerobic fermentation treatment method for wastewater, in which the treated water is discharged from the upper part of the reaction tank while the wastewater is subjected to anaerobic fermentation treatment with sludge composed of microorganisms in the reaction tank, the treated water is separated into solid and liquid and the sludge is recovered. The sludge is solidified to form a microbial carrier and is disposed on the fixed filter bed.

  In the above-described method, there are many microorganisms that effectively perform anaerobic fermentation of wastewater in the region above the fixed filter bed. However, the sludge composed of the microorganisms is discharged together with the treated water.

  However, according to the above method, the apparent specific gravity of the microorganism carrier using the sludge collected by solid-liquid separation from the treated water as a raw material can be made higher than that of the waste water. As a result, even if the microbial carrier is arranged on the upper part of the fixed filter bed, the microbial carrier is not discharged together with the treated water, and the microbial leakage that effectively performs the anaerobic fermentation treatment of the waste water in the region above the fixed filter bed. And anaerobic fermentation treatment of waste water can be performed efficiently and stably.

2ndly, the organic substance density | concentration of the said waste_water | drain in the area | region above the said fixed filter bed is 1 mg / L or more and 100 mg / L or less by a TOC density | concentration, It is characterized by the above-mentioned.
By the above method, microorganisms that are effectively anaerobically fermented at the organic matter concentration are present in a high density in the region above the fixed filter bed of the wastewater. An anaerobic fermentation process can be performed efficiently.

Third, the solid-liquid separation is performed by introducing the treated water into a sedimentation tank and allowing the sludge to settle into the sedimentation tank.
By the above method, sludge can be recovered by a simple method without requiring electric power.

  The microorganism carrier for anaerobic fermentation treatment according to the present invention firstly supplies waste water from the position of the reaction tank that is lower than the fixed filter bed disposed inside the reaction tank, and from microorganisms in the reaction tank. The treated water is discharged from the upper part of the reaction tank while the wastewater is subjected to anaerobic fermentation treatment with the sludge, and the treated water is separated into solid and liquid to collect the sludge and the sludge is solidified.

  By the said structure, the apparent specific gravity of the microorganisms carrier made from the sludge collect | recovered by solid-liquid separation from a treated water can be made higher than a waste_water | drain. As a result, even if the microbial carrier is arranged on the upper part of the fixed filter bed, the microbial carrier is not discharged together with the treated water, and the microbial leakage that effectively performs the anaerobic fermentation treatment of the waste water in the region above the fixed filter bed. And anaerobic fermentation treatment of waste water can be performed efficiently and stably.

Second, the minimum air quality concentration at which the sludge obtained by the solid-liquid separation can maintain metabolism is TOC concentration of 1 mg / L or more and 100 mg / L or less.
With the above configuration, microorganisms that are effectively anaerobically fermented at the organic substance concentration are present in a high density in the region above the fixed filter bed of the wastewater. An anaerobic fermentation process can be performed efficiently.

  The anaerobic fermentation treatment apparatus according to the present invention is an anaerobic fermentation treatment apparatus using the above-described microbial carrier for anaerobic fermentation treatment, wherein the fixed filter bed is disposed and waste water is stored, and the sludge composed of microorganisms A reaction tank for anaerobic fermentation of waste water, and an introduction pipe for introducing new waste water to a position lower than the fixed filter bed of the reaction tank and discharging treated water from the upper part of the reaction tank, Separation means for solid-liquid separation of the sludge from treated water is provided, and the microbial carrier solidified with the sludge can be disposed on the fixed filter bed.

  Although the microorganism carrier can be formed by using the sludge collected by solid-liquid separation from the treated water as a raw material, the apparent specific gravity can be made higher than that of the wastewater. As a result, even if the microbial carrier is arranged on the upper part of the fixed filter bed, the microbial carrier is not discharged together with the treated water, and the microbial leakage that effectively performs the anaerobic fermentation treatment of the waste water in the region above the fixed filter bed. Therefore, an anaerobic fermentation treatment apparatus capable of efficiently and stably performing anaerobic fermentation treatment of waste water is provided.

  According to the method for anaerobic fermentation of waste water, the microbial carrier for anaerobic fermentation, and the anaerobic fermentation treatment apparatus according to the present invention, the apparent specific gravity of the microbial carrier made from sludge recovered by solid-liquid separation from the treated water is used. Can be higher than drainage. As a result, even if the microbial carrier is arranged on the upper part of the fixed filter bed, the microbial carrier is not discharged together with the treated water, and the microbial leakage that effectively performs the anaerobic fermentation treatment of the waste water in the region above the fixed filter bed. And anaerobic fermentation treatment of waste water can be performed efficiently and stably.

It is a schematic diagram of the anaerobic fermentation processing apparatus of 1st Embodiment. It is a schematic diagram of the anaerobic fermentation processing apparatus of 2nd Embodiment. It is a figure which shows the relationship of the specific air quality consumption rate by the difference in the air quality density | concentration of the sludge in each position of a reaction tank.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  In FIG. 1, the schematic diagram of the anaerobic fermentation processing apparatus of 1st Embodiment is shown. The anaerobic fermentation apparatus 10 according to this embodiment includes a reaction tank 12 and a separation unit 34. The reaction tank 12 is a cylindrical container substantially blocked by the outside air, in which the drainage 14 is stored, and sludge (microorganisms) (not shown) for anaerobic fermentation of the drainage 14 is mixed. ing. The lower part of the reaction tank 12 has a tapered shape with a diameter decreasing toward the bottom, and the accumulated sludge 20 (microorganisms) can be taken out from the lowermost part.

  In the reaction tank 12, many (multistage) fixed filter beds 22 are arranged at positions above the lower part of the reaction tank 12. The fixed filter bed 22 is a circular plate material, and is arranged so as to be supported by wires 24 or the like and arranged in the height direction at regular intervals. The fixed filter bed 22a in the upper part (the uppermost stage) is arranged at substantially the same height position, but is a fixed filter bed 22 arranged below it and attached to one of the wires 24 adjacent to each other. The fixed filter bed 22 and the fixed filter bed 22 attached to the other are arranged in a staggered arrangement in the height direction. In addition, although the fixed filter beds 22 and 22a separate the methane generated by the anaerobic fermentation treatment and the sludge taken in the methane, a microbial carrier 46 for anaerobic fermentation treatment can be disposed as described later. it can.

  A discharge part 26 having an outer wall inside the side wall of the reaction tank 12 is formed in the upper part of the reaction tank 12, and the treated water 18 is discharged so as to overflow from the upper end of the discharge part 26.

  An introduction pipe 28 is disposed in the center of the reaction tank 12, and the introduction pipe 28 passes through an upper lid 30 that seals the upper part of the reaction tank and is inserted from the discharge unit 26, and is formed in a lower part (fixed filter bed) inside the reaction tank 12. 22 at a position lower than the lower portion of 22). And the introduction pipe | tube 28 introduces the waste_water | drain 14 (life drainage, industrial waste_water | drain, etc.), and supplies the waste_water | drain 14 from an opening part.

  In the above configuration, the reaction tank 12 does not have a device for mechanically stirring the drainage 14. Accordingly, the drainage 14 forms a high organic matter concentration region in a portion below the fixed filter bed 22, and the organic matter concentration decreases as it moves upward, and the medium and low organic matter is near the uppermost fixed filter bed 22a. A density region is formed.

  In this state, when a new drainage 14 is introduced from the introduction pipe 28, the treated water 18 (the supernatant of the drainage 14) is discharged from the discharge portion 26 in a form where the new drainage 14 is introduced and the new drainage 14 is pushed out. The The new wastewater 14 is subjected to anaerobic fermentation by sludge (microorganisms) that can be subjected to favorable anaerobic fermentation treatment in the high organic matter concentration region, and the fixed filter bed 22 is disposed by the new wastewater 14 in the wastewater 14 that has already been in the high organic matter concentration region. Pushed up to the marked area.

  In the area where the fixed filter bed 22 is arranged, methane generated by anaerobic fermentation of sludge (microorganisms) takes in the sludge, and the incorporated sludge rises due to buoyancy by the methane and the fixed filter bed 22 (fixed filter bed 22a). It contacts the lower surface of the. And when methane reaches | attains the end surface of the fixed filter bed 22, methane will isolate | separate and raise from the sludge taken in by itself, and sludge will fall. In the region where the fixed filter bed 22 is arranged in this way, the sludge repeatedly rises and falls, and the drainage 14 rises, for example, according to the flow path 32 shown in the figure.

  However, if the sludge in the area above the fixed filter bed 22a (medium / low organic substance concentration area) is attached to methane, it rises as it is to the water surface of the drainage 14 and is discharged from the discharge part 26. In other words, the sludge can be effectively anaerobically fermented in the medium and low organic matter concentration region, but will be discharged into the treated water 18 before sufficiently fulfilling its role. Therefore, the present embodiment is characterized in that the sludge mixed and leaked into the treated water 18 is collected by the separation means 34, and the microorganism carrier 46 is formed from this sludge and is introduced into the reaction tank 12.

  The separation means 34 is attached to the main pipe 36 to which the treated water 18 connected to the reaction tank 12 and discharged from the discharge section 26 is introduced, the branch pipe 38 connected in parallel to the main pipe 36, and the branch pipe 38. And a separation membrane 42 for solid-liquid separation of sludge from the treated water 18. A valve 40 is attached to the branch pipe 38, and a sludge discharge line 44 for discharging the sludge separated into solid and liquid is attached to the separation membrane 42. The treated water 18 is introduced into the separation membrane 42 at a constant pressure, and is separated into permeated water that passes through the separation membrane 42 and is discharged to the outside, and concentrated water in which sludge remains without passing through the separation membrane 42. . The concentrated water is taken out from the separation membrane 42 through the sludge discharge line 44, and the sludge obtained from the concentrated water becomes the raw material of the microorganism carrier 46.

  The microorganism carrier 46 is obtained by solidifying the sludge solid-liquid separated from the treated water 18 by the separating means 34 into a size of about 1 mm to 2 mm in diameter with a gel (polymer material). Any material can be applied as long as it allows water to pass through and does not kill microorganisms in the sludge. Further, the microbial carrier 46 is introduced from the discharge unit 26 (the water surface of the drainage 14) and is disposed on the fixed filter bed 22a (and the fixed filter bed 22).

  By the way, the organic substance concentration in the region above the fixed filter bed 22 of the waste water 14 is 1 mg / L or more and 100 mg / L or less in the TOC (Total Organic Carbon) concentration as described later. And since the sludge which carries out the anaerobic fermentation effectively in organic substance density | concentration exists in the above-mentioned area | region in high density, the anaerobic fermentation treatment of the waste_water | drain 14 is efficiently performed by collect | recovering and returning this as the microorganism carrier 46. Can do.

  In the present embodiment, since the diameter of the microbial carrier 46 is about 1 mm to 2 mm, the apparent specific gravity of the microbial carrier 46 using the sludge collected by solid-liquid separation from the treated water 18 as a raw material is drained. It can be higher than 14. Thereby, even if the microbial carrier 46 is arranged on the upper part of the fixed filter bed 22a, the microbial carrier 46 is not discharged together with the treated water 18, and the anaerobic fermentation treatment of the waste water 14 in the region above the fixed filter bed 22a is performed. It is possible to effectively and stably perform the anaerobic fermentation treatment of the waste water 14 while preventing the leakage of microorganisms that is effectively performed.

  In the anaerobic fermentation treatment apparatus 10 of the present embodiment, the treated water 18 having a constant organic matter concentration is discharged at first, but the organic matter concentration is lowered by introducing the microbial carrier 46 described above. become. When the organic matter concentration becomes a certain concentration or less, the valve 40 can be closed to omit the sludge recovery.

  In FIG. 2, the schematic diagram of the anaerobic fermentation processing apparatus of 2nd Embodiment is shown. The anaerobic fermentation treatment apparatus 10 </ b> A of the second embodiment is different from the anaerobic fermentation treatment apparatus 10 of the first embodiment in that the separation means 34 is a precipitation tank 48.

  The sedimentation tank 48 stores the treated water 18 discharged from the discharge unit 26 and discharges the supernatant. The bottom of the sedimentation tank 48 is an inclined surface 48a, and a sludge discharge line 44 is provided at the bottom thereof. Therefore, the sludge 50 in the treated water 18 introduced into the settling tank 48 does not receive the above-described methane buoyancy, so it gradually settles and reaches the bottom, and reaches the sludge discharge line 44 along the inclined surface 48a. To do.

  In the separation membrane 42 of the first embodiment, a pump (not shown) that applies the treated water 18 to the separation membrane 42 at a constant pressure and electric power for driving the pump may be required. Further, the separation membrane 42 is clogged with time. However, in the sedimentation tank 48 of the second embodiment, since the sludge is separated from the treated water 18 by sedimentation, no pump or electric power is required, and sludge (drainage having a high concentration of sludge) is always taken out from the sludge discharge line 44. Therefore, the above-mentioned clogging problem does not occur. As another separation means 34, a horizontally extending ridge (not shown) may be applied, and the treated water 18 may be poured into the basin to collect sludge accumulated on the bottom surface of the ridge.

  In FIG. 3, the relationship of the specific air quality consumption rate by the difference in the air quality density | concentration of the sludge in each position of a reaction tank is shown. The inventor of the present application investigated the specific air quality consumption rate of sludge (microorganisms) at each position of the reaction tank 12 when the air quality concentration (organic matter concentration) in the waste water was changed.

  The inventor of the present application has sludge A floating in the vicinity of the water surface (A) of the drainage 14 (medium / low organic matter concentration region), and sludge B floating in the vicinity (B) (medium / low organic matter concentration region) of the fixed filter bed 22a, Collect sludge C floating in the lower part (bottom) of fixed filter bed 22 (C) (high organic matter concentration region) and sludge D deposited in the lower part (D) of reaction tank 12 (high organic matter concentration region). did. Then, each was introduced into wastewater having a temperament concentration of 500 mg TOC / L, and the rate of decrease in the organic substance concentration, that is, the specific temperament consumption rate [gTOC / gMLVSS (Mixed Liquid Volatile Suspended Solid) -day] was calculated.

  In the initial state, that is, the air quality concentration is 500 mg TOC / L, the sludge D has the fastest specific air quality consumption rate, and then the specific air quality consumption rate becomes slow in the order of sludge C, sludge B, and sludge A. However, as for the sludge D, the specific air quality consumption rate rapidly decreases as the air quality concentration decreases, and becomes zero when the air quality concentration is 200 mg TOC / L. That is, the sludge D shows that the activity is stopped in the wastewater having a temperament concentration of 200 mg TOC / L or less, and further purification of the sludge becomes impossible. Similarly, the activity of the sludge C is stopped in the waste water having a temperament concentration of 150 mg TOC / L or less, and further purification of the sludge becomes impossible.

  On the other hand, sludge B has a specific air quality consumption rate of about 1.5 gTOC / gMLVSS-day even when the air quality concentration is 200 mg TOC / L, and can purify the waste water until the air quality concentration reaches 100 mg TOC / L. Furthermore, the sludge A has a specific air quality consumption rate of about 1.7 gTOC / gMLVSS-day even when the air quality concentration is 200 mg TOC / L, and the waste water can be purified until the air quality concentration reaches 1 mg TOC / L. Therefore, in order to purify the waste water, the sludges A and B have a specific air quality consumption rate of 1.5 g TOC / g MLVSS-day that can sufficiently purify the domestic waste water at an air quality concentration equivalent to domestic waste water of 200 mg TOC / L. It is effective sludge. From this, in the height direction of the reaction tank 12, the organic substance concentration between the vicinity of the water surface (A) and the vicinity of the fixed filter bed 22a (B) (medium low organic substance concentration region) is 1 mg TOC / L to 100 mg TOC / L. There are many sludges (microorganisms) having a minimum air quality concentration (organic substance concentration at which microorganisms maintain metabolism) of 1 mg TOC / L to 100 mg TOC / L.

  Here, since the sludges A and B are floating in the region above the fixed filter bed 22a, they are taken up by methane generated by the anaerobic fermentation process and are discharged from the discharge unit 26. In the embodiment, the microorganism carrier 46 having a diameter of 1 mm to 2 mm made of sludge (sludge A, sludge B) recovered by solid-liquid separation from the treated water 18 is used as the anti-fixed filter bed 22a (and fixed filter bed 22). It is arranged.

  It can be used as an anaerobic fermentation treatment method for waste water that can obtain good treated water quality only by anaerobic fermentation treatment, a microorganism carrier for anaerobic fermentation treatment, and an anaerobic fermentation treatment apparatus.

10 ......... Anaerobic fermentation treatment apparatus, 12 ......... Reaction tank, 14 ......... Drainage, 18 ......... Treatment water, 20 ...... Sediment sludge, 22 ...... Fixed filter bed, 22a ...... Fixed filter Floor, 24 ......... Wire, 26 ......... Discharge section, 28 ......... Introduction pipe, 30 ......... Top cover, 32 ......... Flow path, 34 ......... Separating means, 36 ......... Main pipe, 38 ......... Branch piping, 40 ......... Valve, 42 ......... Separation membrane, 44 ......... Sludge discharge line, 46 ... Microbial carrier, 48 ......... Settling tank, 48a ......... Inclined surface.

Claims (6)

Waste water is supplied from the position of the reaction tank that is lower than the fixed filter bed disposed inside the reaction tank, and the treated water is treated from the upper part of the reaction tank while the waste water is subjected to anaerobic fermentation treatment with sludge composed of microorganisms in the reaction tank. In the anaerobic fermentation treatment method of wastewater that discharges
A method for anaerobic fermentation treatment of waste water, wherein the treated water is separated into solid and liquid to collect the sludge, and the sludge is solidified to form a microorganism carrier and disposed on the fixed filter bed.   The organic matter concentration of the waste water in the region above the fixed filter bed is 1 mg / L or more and 100 mg / L or less in terms of TOC concentration.   The method for anaerobic fermentation of waste water according to claim 1 or 2, wherein the solid-liquid separation is performed by introducing the treated water into a settling tank and precipitating the sludge in the settling tank.   Waste water is supplied from the position of the reaction tank that is lower than the fixed filter bed disposed inside the reaction tank, and the treated water is treated from the upper part of the reaction tank while the waste water is subjected to anaerobic fermentation treatment with sludge composed of microorganisms in the reaction tank. A microorganism carrier for anaerobic fermentation treatment, wherein the sludge is collected by solid-liquid separation of the treated water and the sludge is solidified.   The minimum air quality concentration at which the sludge obtained by the solid-liquid separation can maintain metabolism is 1 mg / L or more and 100 mg / L or less in terms of TOC concentration. Microbial carrier. An anaerobic fermentation treatment apparatus using the microbial carrier for anaerobic fermentation treatment according to claim 4 or 5,
A reaction tank in which the fixed filter bed is disposed and waste water is stored, and the waste water is subjected to anaerobic fermentation treatment with sludge composed of microorganisms;
An introduction pipe for introducing new waste water to a position lower than the fixed filter bed of the reaction tank and discharging treated water from the upper part of the reaction tank;
Have
Separation means for solid-liquid separation of the sludge from the treated water is provided,
An anaerobic fermentation treatment apparatus, wherein the microbial carrier solidified with the sludge can be disposed on an upper part of the fixed filter bed.

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