JP4334084B2 - Start-up method of membrane separation activated sludge treatment tank - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for starting up a membrane separation activated sludge treatment tank, and relates to a technique for starting up an operation of an aeration tank using a membrane separation activated sludge method in human waste treatment, sewage treatment, septic tank, and the like.
[0002]
[Prior art]
Conventionally, the activated sludge method has been used as a method for treating organic wastewater. This activated sludge is a collective term for a group of microorganisms, and the types and number of microorganisms that grow are limited by the pollutant components contained in the wastewater and the amount thereof.
For this reason, as shown in FIG. 3, human waste and sewage generated in a specific area to be treated or waste water generated in a specific facility is led to an activated sludge tank (aeration tank) 1 to activate the activated sludge in the tank. By precipitating pollutants in the wastewater, specific activated sludge is acclimatized under specific wastewater. The sludge mixed liquid in the activated sludge tank 1 is separated into activated sludge and treated water in the sedimentation tank 2, and the activated sludge is returned again to the activated sludge tank 1 for sewage treatment, and the treated water is taken out of the system.
[0003]
The activated sludge that grows in the system is periodically withdrawn from the sedimentation tank 2 to the sludge storage tank 3 as excess sludge and stored, and then dehydrated, dried, incinerated in the facility where the sludge is generated, or removed by vacuum vehicle 4 It is taken out and disposed of.
By the way, in the activated sludge method, as shown in FIG. 3, the submerged membrane separator 6 is immersed inside the activated sludge tank 5, and the sludge mixed liquid in the tank is solid-liquid separated by the submerged membrane separator 6. There is a membrane separation activated sludge method that prevents the activated sludge in the tank from flowing out of the system by taking out the filtered water that has passed through the filtration membrane as treated water, and maintains the activated sludge in the tank at a high concentration. .
[0004]
In this membrane-separated activated sludge method, seeding sludge is thrown into an aeration tank for performing the membrane-separated activated sludge method during the initial operation of a new facility, and the operation is started. This type of sludge is collected from the aeration tank of an existing water treatment facility that treats wastewater of the same quality as the treated water flowing into the facility. The aeration tank mixture containing activated sludge, or excess sludge It is. The aeration tank of this existing water treatment facility is often a contact aeration tank using a standard activated sludge method or a long-time aeration method in addition to a membrane separation activated sludge method.
[0005]
By the way, if the amount of seed sludge to be input is less than a sufficient amount necessary for operation startup, or an aeration tank mixed solution or surplus of an existing water treatment facility that treats wastewater of the same quality as the facility If the sludge is not available, as a convenient method, the aeration tank mixture or surplus sludge from an existing water treatment facility that treats wastewater of different water quality is used as seed sludge. Appropriate microbial species slightly contained in the plant are allowed to grow naturally, and the initial operation is performed to acclimate the activated sludge in the tank to the microorganism group suitable for the treated water flowing into the facility.
[0006]
As another method, as disclosed in Japanese Patent Publication No. 6-73451, the seed sludge is dried and solidified to improve the storage stability, and a high concentration is prepared. There are some that apply to the general activated sludge process.
[0007]
[Problems to be solved by the invention]
By the way, in order to prevent the seed sludge from deteriorating, it is necessary to carry it out quickly within a short time when transporting it from other facilities. However, if the newly established membrane separation activated sludge process facility is geographically distant from the existing water treatment facility, it is difficult to transport the seed sludge within a short time, and the cost of the transport is also low. In many cases, they gave up collecting a large amount of seed sludge because of the increase.
[0008]
Seed sludge collected from an aeration tank using the standard activated sludge method or the long-term aeration method, or from a contact aeration tank, usually has a low concentration of microorganisms contained in the sludge. To secure it, it is necessary to collect and transport a large amount. For this reason, it has been expensive to transport a large amount of useless water. Furthermore, these seed sludges contain microorganism metabolites as well as microorganisms, and the membranes used in the membrane separation activated sludge method tend to be clogged due to their particle size and hydrophilicity.
[0009]
As disclosed in Japanese Examined Patent Publication No. 6-73451, when creating and storing seed sludge, it is possible to increase the amount if it is dried for a sufficient time, but the above-mentioned quality problems are the same. It is in. This method has a problem that the biological activity is low because a large amount of microbial metabolites are contained together with microorganisms, and the target organic matter of the water to be treated is difficult to diffuse inside the solid matter. The sludge produced is a solid substance, and there is no problem in using microorganisms in a fixed state by methods such as the biofilm method and filter bed method, but the microorganisms can be obtained by aeration as in the membrane separation activated sludge method. In the method of using the cocoon in a floating state, the solidified microorganisms sink, and the microorganisms in the solid matter are difficult to come into contact with water. Further, even if the aeration intensity is increased and suspended, the solid material may damage the film surface.
[0010]
The present invention solves the above-mentioned problems, microorganisms are present in high concentration in the seed sludge, and no substances harmful to membrane separation such as microbial metabolites are contained, and the microorganisms in the seed sludge are solidified. It is an object of the present invention to provide a method for starting up a membrane separation activated sludge treatment tank that can be easily dispersed in water without using it.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, membrane separation active operation start-up process of the sludge treatment tank of the present invention according to claim 1, charged with activated sludge withdrawn from the existing waste water treatment system to membrane separation acclimatization vessel, membrane separation acclimatization A part of the wastewater flowing into the existing wastewater treatment system is introduced into the tank, air is diffused to supply oxygen, and the microorganism group of activated sludge is sludge in a state where a few nutrient sources flow in and nutrient resources are insufficient. The activated sludge is acclimatized by microbial decomposition and growth of the organic adhesive substance contained in it, and the separated liquid is separated from the tank by solid-liquid separation using a submerged membrane separator immersed in the membrane separation habitation tank. The activated sludge concentration in the tank is increased by taking it out to the tank, and wet seed sludge consisting of high-concentration activated sludge extracted from the membrane separation acclimatization tank is introduced into the newly installed membrane separation activated sludge treatment tank for initial operation. Is.
[0012]
With the above configuration, in the membrane separation acclimation tank, oxygen is supplied by air diffused into the tank, and if activated sludge is acclimatized with a small amount of nutrients flowing in, the microorganism group of activated sludge becomes a lack of nutrient sources. As an adhesive substance made of organic substances such as sugar and protein contained in sludge, it is proliferated by microbial decomposition.
This activated sludge is solid-liquid separated with a submerged membrane separator and the solid concentration of the activated sludge in the tank is maintained at, for example, SS20000 mg / L or more, so that microorganisms are present in the seed sludge at a high concentration. The amount of seed sludge transported to the membrane separation activated sludge treatment tank can be reduced. In addition, by removing microbial metabolites such as polysaccharides and cell wall debris by microbial decomposition, the activated sludge extracted from the membrane separation and acclimatization tank is replaced with the membrane in the newly installed membrane separation activated sludge treatment tank. Without clogging, it is easily dispersed in water and the microbial population grows in a short time, so that the operation can be started quickly.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, an existing wastewater treatment system 10 is a facility that performs a standard activated sludge method, and excreta and sewage generated in a specific area to be treated, or wastewater generated in a specific facility is an activated sludge tank (aeration tank). ) Lead to 11, and treat the wastewater with activated sludge. In the existing wastewater treatment system 10, it is desirable that the quality of the wastewater is similar to the quality of the water to be treated in the new treatment facility.
[0016]
The sludge mixed liquid in the activated sludge tank 11 is separated into activated sludge and treated water in the sedimentation tank 12, and the activated sludge is returned to the activated sludge tank 11 again for sewage treatment, and the treated water is taken out of the system. The activated sludge in the sedimentation tank 12 is extracted and stored in the sludge storage tank 13, and is put into the membrane separation habitation tank 14 as a seed sludge raw material. The seed sludge of this standard activated sludge method is SS5000 mg / L. A part of the wastewater flowing into the existing wastewater treatment system 10 is guided to the membrane separation habituation tank 14, and the activated sludge is acclimatized by diffusing air.
[0017]
The membrane separation acclimatization tank 14 has a submerged membrane separator 15 immersed therein, and the submerged membrane separator 15 has a membrane module 16 and an air diffuser 17 disposed below the membrane module 16. 17 is provided with a blower (not shown). The membrane module 16 is a parallel arrangement of a plurality of flat membrane cartridges arranged along the vertical direction. The membrane cartridge is a filtration membrane made of an organic membrane on both surfaces of a filter plate made of a rigid body such as ABS resin. Is arranged. The membrane module 16 employs a gravity filtration system that uses the water head in the tank as a drive system. The driving method of the membrane module 13 may be a forced suction method.
[0018]
In the membrane separation acclimatization tank 14, when oxygen is supplied by air diffused from the air diffuser 17 into the tank, and the activated sludge is acclimatized with a small amount of nutrients flowing in, the activated sludge microbial group becomes deficient in nutrients. It grows by microbial degradation of sticky substances made of organic substances such as sugar and protein contained in sludge as a source.
The activated sludge mixed solution in the membrane separation habituation tank 14 is solid-liquid separated by the submerged membrane separation device 15, and the separated liquid is taken out to the treated water tank 19 through the permeate pipe 18. At this time, the upward flow generated by the air lift action of the air diffused from the air diffuser 17 acts as a scavenging on the membrane surface of the membrane module 16 and suppresses the adhesion of the cake layer.
[0019]
By this operation, the activated sludge concentration (solid concentration) in the tank is maintained at, for example, SS 20000 mg / L or more, and the high-concentration activated sludge in the membrane separation habituation tank 14 is taken out into the sludge storage tank 21 through the sludge extraction pipe 20 and stored. .
The high-concentration activated sludge in the sludge storage tank 21 is put into a newly installed membrane separation activated sludge treatment tank 23 by a vacuum wheel 22 as wet seed sludge. Since the microorganisms are present in a high concentration in the wet seed sludge, the amount of seed sludge transported to the newly installed membrane separation activated sludge treatment tank 23 can be reduced.
[0020]
The membrane separation activated sludge treatment tank 23 has a submerged membrane separation device 24 immersed therein, and the submerged membrane separation device 24 is the same as that described above, and a description thereof will be omitted. In the newly installed membrane separation activated sludge treatment tank 23, human waste and sewage generated in a new area to be treated or waste water generated in the facility is guided to the tank to perform the initial operation of the activated sludge treatment and acclimatize the microorganisms.
[0021]
At this time, since the seed sludge has removed the sticky substance by microbial decomposition, it is easily dispersed in water without clogging the membrane of the submerged membrane separation device 24 in the newly installed membrane separation activated sludge treatment tank 23. As the floating microorganisms suitable for the membrane separation activated sludge method grow in a short time, the operation can be started quickly. Moreover, since the seed sludge is wet, the membrane surface of the submerged membrane separator 24 is not damaged.
[0022]
FIG. 2 shows another embodiment of the present invention. In FIG. 2, the high-concentration activated sludge in the sludge storage tank 21 is taken out as raw material sludge, dehydrated, dried and powdered by the dehydrator 25 and dryer 26 to form dry seed sludge, and a newly installed membrane separation activated sludge treatment tank. 23 to perform initial operation.
This makes it possible to reduce the seed sludge and increase its concentration, and it is possible to easily carry the dried seed sludge by the transport vehicle 27. Since the dry sludge has adhesive substances removed by microbial decomposition, the floating microorganisms of the seed sludge are easily dispersed in water without solidification, and without clogging the membrane in the newly installed membrane separation activated sludge treatment tank 23 In a short time, microorganisms can grow and start up quickly. In addition, the increase in storage stability makes it possible to store seed sludge and introduce many microorganisms at once.
[0023]
【The invention's effect】
As described above, according to the present invention, by acclimatizing activated sludge in a membrane separation habitation tank, an adhesive composed of organic substances such as sugar and protein contained in the sludge as a nutrient source lacking the microorganism group of the activated sludge. Since the microorganisms are decomposed and propagated, the microorganisms are present in high concentrations in the seed sludge, and the sticky substances such as polysaccharides and cell wall debris, which are microbial metabolites that clog the membrane, are removed. In the newly installed membrane separation activated sludge treatment tank, the seed sludge is easily dispersed in the water and the microorganism group grows in a short time, so that the operation can be quickly started up. In dry seed sludge, it becomes possible to input many microorganisms at a time due to an increase in storage stability.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing a method for starting operation in an embodiment of the present invention.
FIG. 2 is a flow sheet showing an operation start-up method according to another embodiment of the present invention.
FIG. 3 is a flow sheet showing wastewater treatment by a conventional activated sludge method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Existing waste water treatment system 11 Activated sludge tank 14 Membrane separation acclimatization tank 15 Immersion type membrane separator 16 Membrane module 17 Air diffuser 21 Sludge storage tank 23 Membrane separated activated sludge treatment tank

Claims (1)

Activated sludge extracted from the existing wastewater treatment system is introduced into the membrane separation habitation tank, and a part of the wastewater flowing into the existing wastewater treatment system is guided to the membrane separation habitation tank, and air is diffused to supply oxygen. The activated sludge microorganisms break down the organic sticky substances contained in the sludge and proliferate, and the activated sludge is acclimatized and the membrane separation acclimatized. Wet seeds consisting of high-concentration activated sludge extracted from the membrane separation acclimatization tank by increasing the activated sludge concentration in the tank by solid-liquid separation with a submerged membrane separator immersed in the tank and taking out the separated liquid from the tank. An operation start-up method of a membrane separation activated sludge treatment tank, wherein sludge is introduced into a newly installed membrane separation activated sludge treatment tank and an initial operation is performed.

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