JP3939108B2 - Method for producing seeding agent for membrane separation activated sludge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a seeding agent for membrane separation activated sludge, and relates to a technique for producing a seeding agent used as seed sludge in human waste treatment, sewage treatment, merged treatment septic tank, and the like.
[0002]
[Prior art]
Conventionally, in the activated sludge process for treating organic wastewater, human waste and sewage generated in the area or wastewater generated in a specific facility is guided to the activated sludge tank, and pollutants in the sewage are transferred to the activated sludge in the tank. After predation, the activated sludge and the treated water were separated from each other in the sedimentation tank, and the separated activated sludge was returned to the activated sludge tank and used for the sewage treatment.
[0003]
When operation was started in a new water treatment facility, a commercially available seeding agent or surplus sludge transported from another existing water treatment facility was introduced into the activated sludge tank as seed sludge. However, commercially available seeding agents are expensive, and surplus sludge is transported in a liquid state, so that there are drawbacks such as high transportation costs.
[0004]
For this reason, in recent years, surplus sludge has been increasingly composted (aerobic fermentation) after dehydration, or dried cake with a dryer and used as a seeding agent.
[0005]
[Problems to be solved by the invention]
By the way, surplus sludge generated in a normal existing treatment plant is concentrated by a sludge concentrator and then extracted into a sludge storage tank and stored in an anaerobic state for about one week to one month. Surplus sludge is a group of microorganisms (activated sludge), and certain microorganisms are killed and decomposed to release organic matter and nitrogen in the water. That is, the biological activity is reduced.
[0006]
For this reason, if the excess sludge collected by a vacuum vehicle etc. is dried with a sludge dryer as it is, the odor is severe, deodorizing equipment and deodorizing costs become expensive, and the product unit price of the seeding agent is increased.
[0007]
In addition, conventional compost and dried cake are dried at high temperature, there is almost no biological activity of sludge, and microorganisms are almost dead. For this reason, when a high-temperature dry cake is used as a seeding agent, a biological treatment function by microorganisms cannot be expected, and it has mainly functioned as an adsorbent for organic substances in wastewater. Moreover, the effect was small, and immediately after the seeding agent was added, even though the quality of the treated water was improved, it lasted only for several hours at most. Further, when a flocculant (polymer flocculant) is used for concentration of excess sludge, there is a problem that the dispersibility of the produced seeding agent in water is impaired.
[0008]
The present invention solves the above-mentioned problems, and removes the odor in the manufacturing process of the seeding agent without using a deodorizing equipment, and can manufacture a seeding agent excellent in dispersibility at low cost. It aims at providing the manufacturing method of the seeding agent for separation activated sludge.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the method for producing a seeding agent for membrane separation activated sludge according to the present invention comprises aeration of raw material sludge in a sludge storage tank and concentration by a membrane separation device, and the concentrated sludge is dried at a low temperature vacuum dryer. Is dried to produce a seeding agent, and the odor and condensed water generated in the low-temperature vacuum dryer are introduced into the sludge storage tank for biological treatment.
[0010]
With the above-described configuration, the surplus raw material sludge was in an anaerobic state before being introduced into the system, so that the biological activity has been reduced due to the killing and decomposition of microorganisms, and it contains organic matter and nitrogen released in the anaerobic state. It is out.
[0011]
For this reason, by aeration of sludge in the sludge storage tank, organic substances dissolved in the mixed sludge in the tank under aerobic condition are utilized to restore biological activity and to promote the growth of microorganisms and to remove odor-causing substances Therefore, the generation of odor in the low temperature vacuum dryer is suppressed.
[0012]
Activated sludge can be concentrated without using a flocculant by membrane separation treatment with a membrane separator, eliminating the adverse effect of the polymer flocculant on the seeding agent. Can be adjusted. This concentrated activated sludge is dried at a low temperature under vacuum to suppress the death of microorganisms due to heating.
[0013]
Therefore, sufficient microbial content, bioactivity, solubility, diffusibility, and dispersibility of the product seeding agent can be obtained by restoring and growing the biological activity by aeration, preventing the use of flocculants, and suppressing the death of microorganisms by low-temperature vacuum drying. Can be secured.
[0014]
Condensed water and odor are generated during drying, and volatile substances are dissolved in the condensed water, and the volatile substances become the source of odor generation. For this reason, the condensed water and odor are introduced into the activated sludge storage tank to biodegrade the organic matter, nitrogen and volatile substances in the condensed water, and the odor components are biologically deodorized.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, surplus sludge (activated sludge) 1 is surplus sludge generated in domestic wastewater treatment facilities such as sewage treatment facilities and merged treatment septic tanks, and a single wastewater treatment system surplus sludge may be used alone. The surplus sludge from different wastewater treatment systems may be mixed.
[0016]
In addition, the seeding agent produced by using the activated sludge of the actual wastewater treatment system as a raw material has a group of microorganisms that use the actual pollutant components in the wastewater treatment system to be input as a nutrient source. It contains microbial species that have grown predominantly in various fields of environmental change, and exhibits excellent adaptability to environmental changes in activated sludge tanks due to the presence of these microbial species.
[0017]
The surplus sludge (activated sludge) 1 of this raw material is transferred to the sludge storage tank 2 by a vehicle. When the wastewater treatment facility and the seeding agent production facility are adjacent or the same, transfer means such as a pump may be used.
[0018]
As shown in FIG. 2, the sludge storage tank 2 has a submerged membrane separation device 3 arranged in the tank. Although the submerged membrane separation device 3 is used in the present embodiment, a membrane separation device arranged outside the tank can also be used. The submerged membrane separation device 3 includes a plurality of flat plate membrane cartridges 4 and an air diffuser 5 for ejecting a membrane surface cleaning gas from below the case 6 inside a case 6. The membrane cartridge 4 has filtration membranes arranged on both surfaces of a resin filter plate, and each membrane cartridge 4 communicates with the permeate outlet tube 7.
[0019]
The sludge storage tank 2 treats organic matter and nitrogen in the excess sludge with activated sludge in a state in which aeration air is ejected from the air diffuser 5 of the submerged membrane separation apparatus 3, and the activated sludge mixed liquid in the tank is stored in the tank. The membrane head 4 is gravity filtered with the head of water at the driving pressure (suction filtration is possible by inserting a suction pump in the permeate outlet pipe 7), and the permeate permeated through the membrane of the membrane cartridge 4 is processed. It is led out of the tank through the permeate outlet pipe 7 as water. At this time, the membrane surface of the membrane cartridge 4 is washed with bubbles of aerated air ejected from the diffuser 5 and the upward flow generated thereby, and the deterioration of the separation function is suppressed, so that the submerged membrane separation device 3 malfunctions. Is prevented.
[0020]
As shown in FIG. 3, the sludge storage tank 2 can be divided into a two-tank structure and a sludge storage section 2 a that also serves as a denitrification tank and a membrane separation activated sludge section 2 b that also serves as a nitrification tank. In this case, the mixed liquid in the tank of the sludge storage section 2a is supplied to the membrane separation activated sludge section 2b through the circulation system 2d and the screen 2e by the circulation pump 2c, and the mixed liquid in the tank of the membrane separation activated sludge section 2b is supplied to the sludge storage section. Overflow to 2a. This configuration enables nitrification and denitrification.
[0021]
The sludge storage tank 2 is provided with a second air diffuser 9 that diffuses the odor of the sludge dryer 8 described later, and communicates with the sludge dryer 8 through the odor supply system 10 and the condensed water supply system 11. . The activated sludge concentrated by the membrane separation process by the submerged membrane separation device 3 is supplied to the sludge dryer 8 through the sludge supply system 12.
[0022]
The sludge dryer 8 is a low-temperature vacuum dryer such as a thin film evaporation powderizer or a vacuum stirring dryer, and dries the activated sludge at a low temperature. The sludge dryer 8 supplies condensed water generated in the drying process to the sludge storage tank 2 through the condensed water supply system 11 and supplies exhaust gas containing odor to the sludge storage tank 2 through the odor supply system 10. The dried sludge of the sludge dryer 8 is stored in the storage tank 14 through the dried sludge supply system 13 and then supplied to the bagging machine 15, and the packed product seeding agent is transferred to a customer such as the treatment plant 16 by the vehicle.
[0023]
Hereinafter, the operation of the above configuration will be described. Since the raw material excess sludge 1 was in an anaerobic state before being introduced into the system, its biological activity has been reduced due to the killing and decomposition of microorganisms, and contains organic matter and nitrogen released in the anaerobic state.
[0024]
For this reason, in the sludge storage tank 2, the raw material activated sludge is aerated with the air diffused from the air diffuser 5 to assimilate the organic matter dissolved in the mixed sludge in the tank under aerobic condition to restore the biological activity. Let the microorganisms grow. The activated sludge can be concentrated without using a flocculant by membrane separation treatment with the submerged membrane separation device 3, and the concentration in the sludge dryer 8 can be adjusted to any desired concentration. You can save. Further, since the membrane permeate is of good quality, it may be discharged as it is, and underground infiltration treatment is also possible.
[0025]
In the drying process of the sludge dryer 8, the activated sludge is disintegrated and is granulated to an appropriate particle size to form dried fine particles or granule particles. If necessary, the dried sludge mass is pulverized to a predetermined particle size by a pulverizing means to be finely divided or granulated. Since the particles are dried at a low temperature by vacuum drying, the microorganisms are not inactivated (died) by heating in the drying process as in the past, and maintain sufficient biological activity, and the form is Since it is in the form of particles, it has excellent solubility, diffusibility, and dispersibility in water during use. It is also possible to add a chemical dispersant or a fiber component that improves the dispersibility during drying.
[0026]
Therefore, a sufficient amount of microorganisms and diffusibility can be ensured in the product seeding agent by restoring / proliferating biological activity by aeration, not using a flocculant, and suppressing microbial death by low-temperature vacuum drying.
[0027]
In the sludge dryer 8, condensed water and odor are generated at the time of drying, and volatile substances are dissolved in the condensed water, and this volatile substance becomes a source of odor generation. For this reason, the condensed water and odor are introduced into the activated sludge storage tank 2 through the condensed water supply system 11 and the odor supply system 10, respectively, to biodegrade the organic matter, nitrogen and volatile substances in the condensed water, Deodorize. For this reason, facilities, such as a deodorizing apparatus, become unnecessary, and the expense required for deodorizing can be reduced. Further, the odor can be blown into the diffuser 5 of the submerged membrane separator 3, and in this case, the amount of air for aeration can be reduced.
[0028]
【The invention's effect】
As described above, according to the present invention, activated sludge as a raw material is aerated in a sludge storage tank to recover and proliferate biological activity, and is concentrated by a membrane separator without using a flocculant. Since drying is performed while preventing the death of microorganisms due to heating, a sufficient amount of microorganisms and solubility, diffusibility, and dispersibility can be ensured in the product seeding agent. In addition, biodeodorization in the sludge storage tank eliminates the need for a separate deodorization facility and water treatment device, and the seeding agent can be manufactured at low cost by suppressing facility costs and operation management costs.
[Brief description of the drawings]
FIG. 1 is a flow sheet diagram showing a method for producing a seeding agent for membrane separation activated sludge in an embodiment of the present invention.
FIG. 2 is a schematic view showing a sludge storage tank in the same embodiment.
FIG. 3 is a schematic diagram showing a sludge storage tank in an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Excess sludge 2 Sludge storage tank 3 Submerged membrane separator 4 Flat membrane cartridge 5 Air diffuser 6 Case 7 Permeate outlet pipe 8 Sludge dryer 9 Second air diffuser 10 Odor supply system 11 Condensate supply system 12 Sludge Supply system 13 Dry sludge supply system 14 Storage tank 15 Bagging machine 16 Treatment plant

Claims (1)

In the sludge storage tank, the raw material sludge is aerated and concentrated by a membrane separator, and the concentrated sludge is dried by a low-temperature vacuum dryer to produce a seeding agent. The odor and condensed water generated by the low-temperature vacuum dryer are sludge. A method for producing a seeding agent for membrane-separated activated sludge, which is introduced into a storage tank and biologically treated.

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