JPH0839092A - Method and apparatus for treating excessive sludge - Google Patents

Abstract

PURPOSE:To reduce a generation amt. of excessive sludge by digesting and decomposing excessive sludge conc. and separated in the rear stage of a waste water treatment method using bacteria by utilizing a food-chain of a protozoan or metazoan in a multistage digestion tank packed with a bacteria carrier. CONSTITUTION:At first, raw waste water is sent to a first sedimentation basin 1 and a precipitate such as metals or salts and activated sludge in raw waste water are sent to a sludge treatment process 4. The mixed soln. of waste water and activated sludge in the first sedimentation basin 1 is sent to an aeration tank 2 to be aerated by air and subjected to decomposed treatment by bacteria to be sent to a final sedimentation basin 3. Supernatant water in the final sedimentation basin 3 is discharged as purified water and a part of excessive activated sludge is returned to the first sedimentation basin 1 to be utilized as seed bacteria. Excessive sludge is digested in an excessive sludge digestion tank 5 to change org. matter to CO2 or H2O by a food-chain of a protozoan or metazoan to be reduced in vol. and the treated water is again returned to the first sedimentation basin 1.

Description

Detailed Description of the Invention

[0001]

The present invention relates to wastewater from petroleum refining, petrochemical plants, etc., industrial wastewater from food industries, large-scale cleaning industries, etc., and organic pollutants in general wastewater such as rivers, lake water, and sewage. The present invention relates to a method and a treatment apparatus for reducing excess sludge produced as a by-product when decomposing by catalytic oxidation of microorganisms by an ordinary activated sludge method or three-phase flow method.

[0002]

2. Description of the Related Art Conventionally, excess sludge produced as a by-product when decomposed by catalytic oxidation of microorganisms by a conventional activated sludge method or three-phase flow method is incinerated, decomposed or discarded after settling separation. . FIG. 2 shows a flow of the conventional normal activated sludge method. Raw wastewater is first sent to the settling tank 1, and sediments made of inorganic substances such as metals and salts in the raw wastewater and some activated sludge are treated with sludge. It is sent to step 4. The mixed liquid consisting of the wastewater from the settling tank 1 and the activated sludge is aerated by the air sent in the aeration tank 2 and decomposed by the catalytic oxidation of microorganisms, and then sent to the final settling tank 3. In the final settling tank 3, the supernatant water is discharged as it is as purified water, the surplus activated sludge that has settled is sent to the sludge treatment process, and a part of the surplus activated sludge is first returned to the settling tank 1 and used as seed bacteria. It Then, the sludge in the sludge treatment step 4 and the surplus activated sludge in the final settling tank 3 are combined and disposed of as industrial waste.

[0003]

However, in the above-mentioned conventional excess sludge treatment method, when incinerating, decomposing or discarding the excess sludge by-produced in the final settling tank 3, a large amount of fuel and labor is required. It has a problem that it is often necessary.

The present invention is to solve the above-mentioned conventional problems, and is an excess sludge treatment capable of efficiently reducing the amount of excess sludge generated by the digestive decomposition action utilizing the food chain action of protozoa and metazoans. It is an object to provide a method and a device.

[0005]

Therefore, the method for treating excess sludge according to the present invention is a method for treating excess sludge concentrated and separated in the latter stage of a wastewater treatment method by microorganisms in a multistage digester tank filled with a microbial carrier to produce protozoa and metazoans. It is characterized by reducing the amount of excess sludge generated by digesting and using the food chain of. Further, the surplus sludge treatment device of the present invention comprises a wastewater treatment tank for treating wastewater with microorganisms, a multistage digestion tank connected in parallel to the wastewater treatment tank for treating excess sludge in the wastewater treatment tank, and a multistage digestion tank And a microbial carrier that carries protozoa and metazoans that are filled in The embodiment of the surplus sludge treatment device of the present invention has the following configurations.

(1) Recycle the treated water containing a small amount of digestive residual microorganisms discharged from the wastewater treatment tank.

(2) A structure in which a plurality of multistage digestion tanks are arranged in the horizontal direction.

(3) A configuration in which a plurality of multistage digestion tanks are arranged in the vertical direction.

(4) A configuration in which a plurality of multistage digestion tanks are arranged in the circumferential direction.

[0010]

INDUSTRIAL APPLICABILITY In the present invention, excess sludge concentrated and separated in a settling tank is efficiently digested and decomposed by utilizing the food chain action of protozoa and metazoans to effectively reduce the amount of excess sludge generated. You can Further, by recycling the treated water containing a small amount of residual digestive microorganisms, it becomes possible to reduce the amount of excess sludge generated to almost zero. further,
By adding a food chain digestion tank to the existing activated sludge device, it becomes possible to easily reduce the amount of excess sludge generated to almost zero.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flow chart showing an embodiment of the method for treating surplus sludge of the present invention. This example shows a method of treating excess activated sludge in the activated sludge method of FIG.

First, the raw wastewater is first sent to the settling tank 1, and the sediment and inorganic activated sludge in the raw wastewater, which are composed of inorganic substances such as metals and salts, are sent to the sludge treatment step 4. The mixed liquid consisting of the wastewater from the settling tank 1 and the activated sludge is aerated by the air sent in the aeration tank 2 and decomposed by the catalytic oxidation of microorganisms, and then sent to the final settling tank 3. In the final settling tank 3, the supernatant water is discharged as it is as purified water, and the surplus activated sludge that has settled is sent to the surplus sludge digestion tank 5 by the food chain together with the treated water.
A part of the surplus activated sludge is first returned to the settling tank 1 and used as seed bacteria. The excess sludge digestion tank 5 converts organic matter into CO ₂ or H ₂ O by a food chain using excess sludge as food for protozoa or metazoan to reduce digestion, and returns treated water to the first settling tank 1 again. There is.

FIG. 3 shows various examples of the excess sludge digestion tank 5. In FIG. 3 (A), the surplus sludge digestion tank 5 is partitioned by a partition plate 6, and three filtration beds 5a, 5b, 5c are arranged in the lateral direction.
FIG. 3 (B) shows an example in which the excess sludge digestion tank 5 is formed.
Is divided by a net member 7 to form three filtration beds 5a, 5b, 5c in the vertical direction, and FIG.
The circular excess sludge digestion tank 5 is partitioned by a partition plate 6,
An example in which five filtration beds 5a, 5b, 5c, 5d, and 5e are formed is shown. In either case, air is introduced from the lower part of the excess sludge digestion tank 5 to treat the sludge under aerobic conditions.

Each of the filtration beds 5a-5d is filled with a large number of microbial carriers for carrying protozoa or metazoans. The microbial carrier may have any shape such as a sphere, a pellet, a dice, a perforated cylinder, a thread, a rod, or a plane, and its size is about 0.1 mm to 20 mm, and the material is It is optional regardless of whether it is a natural material, an inorganic material, a polymer material, or the like. In addition, a method of applying a protozoan or a metazoan on the surface or pores of a carrier using a gel-like substance, or a method of entrapping and fixing a microorganism or a protozoan or metazoan in a gel-like substance may be adopted.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made. For example, in the above embodiment,
An example of excess sludge of aerobic microorganisms is shown, but digestive loss can be similarly performed on excess sludge of anaerobic microorganisms. In the case of anaerobic treatment, decomposition or digestion gas (which does not contain oxygen) generated in the upstream anaerobic treatment stage is injected from the lower portion of the excess sludge digestion tank 5.

In the above embodiment, an example in which the excess sludge digestion tank 5 by the food chain is added to the activated sludge method is shown, but it is applicable to all wastewater treatment methods by other microorganisms including the three-phase flow method. Is.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of a method for treating surplus sludge of the present invention.

FIG. 2 is a diagram showing a flow of a conventional normal activated sludge method.

FIG. 3 is a diagram showing an embodiment of a surplus sludge treatment device of the present invention.

[Explanation of symbols]

1 ... First settling tank, 2 ... Aeration tank, 3 ... Final settling tank, 5 ... Excess sludge digestion tank

Front page continuation (72) Hideyuki Kuwahara Inventor Hideyuki Nishitsurugaoka 1-3-1 Oi-cho, Saitama Prefecture Tonen Corporation Research Institute (72) Inventor Shoichi Mori Nishitsurugaoka 1-chome, Oi-cho, Saitama Prefecture No. 1 Tonen Co., Ltd. Research Institute

Claims (2)

[Claims] 1. Excess sludge concentrated and separated in the latter stage of the wastewater treatment method using microorganisms is treated in a multistage digester tank filled with a microbial carrier,
A method for treating excess sludge, which comprises reducing the amount of excess sludge generated by digesting and degrading the food chain of protozoa and metazoans. 2. A wastewater treatment tank for treating wastewater with microorganisms, a multistage digestion tank which is connected in parallel to the wastewater treatment tank and treats excess sludge in the wastewater treatment tank, and a protozoa which is filled in the multistage digestion tank. A surplus sludge treatment device, comprising: a microbial carrier that carries metazoans.