JP2012035146A - Water treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment method which controls the generation of scum and malodor, and the deposite of an indraft organic matter in a treatment tank, and raises the organic matter decomposition speed and the rate of organic matter removal.SOLUTION: The water treatment method which performs water treatment under facultative anaerobic condition at least includes: a process which makes sewage flow in at least one treatment tank 2; a process which feeds in a facultative anaerobic microorganism material in the treatment tank 2; and a process which agitates inside the treatment tank 2 continuously or intermittently. The facultative anaerobic microorganism material is a powder, solid or liquefied material which has compounded facultative anaerobiosis microorganisms containing at least two of lactic acid bacteria, yeast cell, filamentous fungi, and actinomyceses. The treatment tank 2 includes: a stirring tank 2a which agitates the sewage and the facultative anaerobic microorganism material; and a settling tank 2b which separates solid and liquid after stirring, and returns the solid separated by the settling tank 2b to the stirring tank 2a through gravity.

Description

  The present invention relates to a water treatment method for performing water treatment under facultative anaerobic conditions.

As a conventionally known water treatment apparatus, for example, there is a waste water treatment apparatus disclosed in JP-A-2003-205297. This waste water treatment apparatus comprises an absolute anaerobic first filter bed provided at the bottom of the treatment tank, an oxygen-free second filter bed provided above the first filter bed, and its second filter. An aerobic third filter bed provided at the upper part of the floor. Moreover, the raw | natural water inflow part is provided below the 1st filter bed part, and the sludge concentration part and the sedimentation sludge extraction part are provided in the bottom part of the processing tank. Further, a treated water discharge part is provided above the third filter bed part, and an air diffuser is provided below the third filter bed part. In this waste water treatment apparatus, a part of the treated water above the third filter bed is extracted and allowed to flow below the second filter bed through the nitrification liquid circulation path.
JP 2003-205297 A

  However, in the conventional technology, since anaerobic decomposition is mainly used in water treatment, the following problems exist. That is, (1) Since it is an anaerobic subject, scum is generated and a bad odor is generated. (2) Since it is mainly anaerobic, the organic matter decomposition rate is slow. Since the organic matter decomposition rate is slow, the inflowing organic matter tends to accumulate in the treatment tank. For this reason, when organic substance accumulates in a processing tank, sludge extraction work will be needed regularly. (3) Since it is mainly anaerobic, the organic matter removal rate is low, and a burden is imposed on the biological treatment in the next step. Moreover, since biological treatment is burdened, it is difficult to obtain highly treated water.

  The present invention has been made in view of such circumstances, and is capable of suppressing the generation of scum and malodor and the accumulation of inflowing organic matter in the treatment tank, and can increase the organic matter decomposition rate and the organic matter removal rate. An object is to provide a processing method.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the water treatment method of the present invention is a water treatment method for performing water treatment under facultative anaerobic conditions, the step of flowing sewage into at least one treatment tank, and the facultative anaerobic microbial material as described above. It is characterized by including at least the process of throwing into a processing tank and the process of stirring the inside of the said processing tank continuously or intermittently.

  In this way, sewage is allowed to flow into at least one treatment tank, the facultative anaerobic microbial material is introduced into the treatment tank, and the inside of the treatment tank is stirred continuously or intermittently. It becomes possible to maintain a microaerobic environment in which sex microorganisms are easy to act. As a result, scum and odor are not generated unlike an anaerobic subject. Moreover, since it is facultative anaerobic, the organic substance decomposition | disassembly rate is quicker than an anaerobic main body, and it is hard to generate | occur | produce an excess sludge. For this reason, the sludge extraction work can be reduced or eliminated. Furthermore, the organic matter removal rate is higher than that of the anaerobic main body, and it becomes possible to obtain highly treated water.

  (2) Moreover, in the water treatment method of the present invention, the facultative anaerobic microorganism material is a powder that is a composite of facultative anaerobic microorganisms including at least two of lactic acid bacteria, yeasts, filamentous fungi, and actinomycetes. It is a solid or liquid material.

  With this configuration, it is possible to perform water treatment under facultative anaerobic conditions rather than anaerobic subjects.

  (3) Moreover, in the water treatment method of the present invention, the treatment tank is composed of a stirring tank for stirring sewage and facultative anaerobic microorganism material, and a settling tank for separating solid and liquid after the stirring. The solid separated in the settling tank is returned to the stirring tank through gravity.

  Thus, since stirring is performed in the stirring tank instead of aeration, the inside of the stirring tank can be maintained in a slightly aerobic environment. In addition, since the solid separated in the sedimentation tank is returned to the stirring tank via gravity, the bacterial density in the stirring tank becomes higher than the organic matter flowing into the stirring tank due to the cells returned to the stirring tank, and the decomposition of the organic matter is accelerated. Is possible. As a result, the decomposition rate of the organic matter increases, and the self-digestion of the bacterial cells proceeds, and it becomes possible to suppress the generation of excess sludge. As a result, the sludge extraction work can be reduced or eliminated, the organic matter removal rate is higher than that of the anaerobic main body, and highly treated water can be obtained. Moreover, scum and odor are not generated unlike an anaerobic subject.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to maintain in the microaerobic environment where facultative anaerobic microorganisms act easily in a processing tank. As a result, scum and odor are not generated unlike an anaerobic subject. Moreover, since it is facultative anaerobic, the organic substance decomposition | disassembly rate is quicker than an anaerobic main body, and it is hard to generate | occur | produce an excess sludge. For this reason, the sludge extraction work can be reduced or eliminated. Furthermore, the organic matter removal rate is higher than that of the anaerobic main body, and it becomes possible to obtain highly treated water.

  In the water treatment method according to the present invention, the inside of the treatment tank is maintained in a microaerobic environment in which facultative anaerobic microorganisms including at least two of lactic acid bacteria, yeasts, filamentous fungi, and actinomycetes are most likely to be active. , Promoting the degradation of these facultative anaerobic microorganisms. As a result, the purification is advanced while suppressing malodor and excess sludge. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an outline of a water treatment method according to the present embodiment. The water treatment facility 1 includes a treatment tank 2, and the treatment tank 2 includes a stirring tank and a sedimentation tank described later. In the water treatment method according to this embodiment, first, sewage is caused to flow into the treatment tank 2. Next, the facultative anaerobic microorganism material is put into the treatment tank 2. This facultative anaerobic microbial material is a powdery, solid or liquid material in which facultative anaerobic microorganisms containing at least two of lactic acid bacteria, yeasts, filamentous fungi and actinomycetes are combined. Next, the inside of the processing tank 2 is stirred continuously or intermittently. And treated water is obtained.

  FIG. 2 is a diagram showing a schematic configuration of the processing tank 2. The treatment tank 2 includes a stirring tank 2a that stirs sewage and facultative anaerobic microorganism material, and a settling tank 2b that separates solid and liquid after stirring. In the agitation tank 2a, the inflowing organic substance is agitated continuously or intermittently using aeration, rotating blades, agitation plates, or the like. The inclined portion 2c serves to return the solid separated in the sedimentation tank 2b to the stirring tank 2a via gravity. The partition plate 2d divides the treatment tank 2 into a stirring tank 2a and a settling tank 2b. The water treated in this way is taken out from the outlet 2e as treated water.

  Thus, since stirring is performed in the stirring tank 2a instead of aeration, the inside of the stirring tank 2a can be maintained in a slightly aerobic environment. In addition, since the solid separated in the sedimentation tank 2b is returned to the stirring tank 2a via gravity, the bacterial density in the stirring tank 2a is higher than the organic matter flowing into the stirring tank 2a by the cells returned to the stirring tank 2a. Decomposition can be accelerated. As a result, the decomposition rate of the organic matter increases, and the self-digestion of the bacterial cells proceeds, and it becomes possible to suppress the generation of excess sludge. As a result, the sludge extraction work can be reduced or eliminated, the organic matter removal rate is higher than that of the anaerobic main body, and highly treated water can be obtained. Moreover, scum and odor are not generated unlike an anaerobic subject.

  In the conventional water treatment technology, anaerobic decomposition was used in the primary treatment. However, anaerobic decomposition had a slow organic decomposition rate and generated scum and odor. In the water treatment method according to the present embodiment, the generation of scum and malodor can be suppressed by stirring the sewage using facultative anaerobic microorganisms to bring it into a microaerobic state. Moreover, although the aeration performed by the conventional water treatment technique was aimed at the growth of aerobic bacteria, the generation of excess sludge has been promoted by the aeration. According to the water treatment method according to the present embodiment, a facultative anaerobic bacterium (microaerobic decomposition) is performed by continuously or intermittently stirring while keeping the inside of the treatment tank not aerated but stirring. Generation of new sludge can be suppressed.

  Further, as shown in FIG. 2, when organic matter (sewage) flows into the processing tank 2 having both the stirring tank 2a and the settling tank 2b in the same tank, first, the solid matter is decomposed in the stirring tank 2a, and the settling tank Move to 2b. However, the settled residual solid matter returns to the stirring tank 2a again through gravity by the inclined portion 2c. Thereby, being decomposed by the facultative anaerobic microorganism group in the treatment tank 2 is repeated. Here, in order to increase the bacterial density in the stirring tank 2a and stabilize the sedimentation in the settling tank 2b, the partition balance between the stirring tank 2a and the settling tank 2b in the same treatment tank 2 is the capacity of the settling tank 2b. Is preferably at least twice the capacity of the stirring tank 2a.

  Due to the bacteria separated from the solid and the liquid in the settling tank 2b and returned to the stirring tank 2a by the inclined portion 2c, the density of the staying bacteria inside the stirring tank 2a becomes higher than the density of the inflowing organic matter. For this reason, in the processing tank 2, it becomes a starvation state with respect to a microbial cell, and self-digestion of a microbial cell will advance. Thereby, generation | occurrence | production of excess sludge can be suppressed. Since the cell density in the stirring tank 2a is high, the decomposition rate of the organic matter is increased, and the organic matter removal rate is increased. Thereby, in the water treatment method according to the present embodiment, when biological treatment is performed in the next step, the treatment load can be reduced.

  Further, according to the water treatment method according to the present embodiment, as described above, it is excellent in the decomposition of solid organic matter and can suppress the generation of excess sludge, thereby reducing or eliminating sludge extraction work. be able to. Furthermore, the water treatment facility according to the present embodiment can reduce the capacity of the treatment tank as compared with the conventional anaerobic decomposition treatment facility that is the primary treatment, and the overall facility can be made compact. Furthermore, the water treatment facility according to the present embodiment is economically advantageous because the stirring tank 2a and the settling tank 2b can be configured by simply partitioning the treatment tank 2 with the partition plate 2d.

  FIG. 3 is a diagram illustrating a comparative example of the effects of the water treatment method according to the present embodiment and the conventional water treatment method. Although FIG. 2 demonstrated using the single processing tank 2, the example which connected and used the two processing tanks 2 is shown here. That is, through the first and second microaerobic decomposition tanks having the same function as the treatment tank 2, then the rectification layer, then the first and second contact aeration tanks, and finally the precipitation / disinfection tank Water treatment is performed. Here, BOD (Biochemical Oxygen Demand) is used as a standard indicating the effect of water treatment. This BOD (biochemical oxygen demand) is the amount of oxygen required when pollutants (organic substances) in river water and factory effluent are mineralized or gasified by microorganisms.

  In the conventional water treatment method, when sewage having a BOD of 200 ppm is introduced, the BOD can be reduced to 100 to 80 ppm in an anaerobic filter bed tank. The removal rate of BOD is 50-60%. Next, BOD can be reduced to 20 ppm or less in a biological treatment tank. The BOD removal rate for sewage flowing from the anaerobic filter bed tank is 80%.

  On the other hand, in the water treatment method of the present invention, when sewage having a BOD of 200 ppm is introduced, the BOD can be reduced to 25 ppm or less in the microaerobic decomposition tank. The removal rate of BOD is 87.5% or more. Thus, even with only the microaerobic decomposition tank, it is possible to remove more BOD than the conventional water treatment method. Next, BOD can be reduced to 5 ppm or less in a contact aeration tank. The BOD removal rate with respect to the sewage flowing from the microaerobic decomposition tank is 80% or more. Thus, it turns out that the water treatment method which concerns on this embodiment is very excellent compared with a prior art.

It is a figure which shows the outline | summary of the water treatment method which concerns on this embodiment. FIG. 2 is a diagram showing a schematic configuration of a processing tank 2 It is a figure which shows the comparative example of the effect of the water treatment method which concerns on this embodiment, and the conventional water treatment method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water treatment facility 2 Treatment tank 2a Stirring tank 2b Settling tank 2c Inclined part 2d Partition plate 2e Outlet

Claims (3)

A water treatment method for water treatment under facultative anaerobic conditions,
Flowing sewage into at least one treatment tank;
Introducing a facultative anaerobic microbial material into the treatment tank;
And a step of stirring the inside of the treatment tank continuously or intermittently.   The facultative anaerobic microbial material is a powdery, solid or liquid material in which facultative anaerobic microorganisms containing at least two of lactic acid bacteria, yeasts, filamentous fungi, and actinomycetes are combined. Item 2. A water treatment method according to Item 1.   The treatment tank is composed of a stirring tank that stirs sewage and facultative anaerobic microorganism materials, and a sedimentation tank that separates the solid and liquid after the stirring, and the solid separated in the sedimentation tank is subjected to gravity. The water treatment method according to claim 1, wherein the water treatment method is returned to the agitation tank.

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