JP3385306B2 - Wastewater treatment equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a wastewater treatment device for efficiently treating wastewater containing organic substances and / or inorganic substances. More particularly, at least, the waste water treatment tank and the membrane module comprising a denitrification tank and / or the nitrification tank was charged carrier particles with immobilized microorganisms - relates to a compact waste water treatment apparatus constituted by Le.

[0002]

2. Description of the Related Art Conventionally, organic wastewater containing nitrogen compounds, such as rural village wastewater, domestic wastewater, urban sewage, fish farm wastewater, various industrial wastewater, generally uses aerobic and anaerobic microorganisms. It has been treated by an activated sludge method to purify pollutants. For example, as shown in FIG. 12, the wastewater 1 is introduced into the anaerobic tank 32, and then in the aerobic tank 33 under the aerobic condition.
Oxidation of OD components and nitrification of nitrogen compounds by nitrifying bacteria, and part of the treated water flowing out from the aerobic tank 33 is removed from the anaerobic tank 32.
And denitrifying using denitrifying bacteria under anaerobic conditions.
The runoff water from the remaining aerobic tank was subjected to sedimentation and separation of sludge in the settling tank 34, and then the supernatant water 26 was discharged.

In the case of the conventional activated sludge method, the retention time of wastewater in the aeration tank is designed to be 6 to 8 hours, but the amount of wastewater tends to increase with the recent diversification of industry and life. Therefore, if a large amount of waste water is to be treated by the activated sludge method using an existing treatment tank, the residence time will be shortened and abnormalities such as bulking will occur, making it impossible to perform satisfactory treatment. Therefore, new equipment is required to deal with a large amount of wastewater treatment, which requires vast land and huge construction cost.

On the other hand, from the viewpoint of nitrogen removal, in the conventional nitrogen removal, the water to be treated is introduced into the denitrification tank and the nitrification tank in this order.
Part of the nitrification-treated water flowing out of the nitrification tank is returned to the denitrification tank.
With circulation, the remaining nitrification water is sent to the final settling tank for treatment, or the nitrification tank and denitrification tank are introduced in this order.
This is done by a method in which the entire amount of denitrification treated water flowing out of the denitrification tank is sent to the final sedimentation tank for treatment. At this time, in the nitrification tank, Kjeldahl nitrogen is oxidized to nitrite nitrogen or nitrate nitrogen, and in the denitrification tank, nitrite nitrogen or nitrate nitrogen is converted to nitrogen gas and removed, but in these methods, Nitrogenation and denitrification are generally performed by activated sludge to remove nitrogen.

Even when the waste water is treated by such a nitrogen removing method, the total residence time in the nitrification tank and the denitrification tank is required to be 12 to 24 hours on the basis of inflow water, and the residence time is designed to be about 6 to 8 hours. In existing sewage treatment plants only for removing BOD, the retention time is insufficient and nitrogen cannot be removed satisfactorily. In order to deal with a large amount of wastewater treatment, a new treatment device is required as described above, which requires vast land and huge construction cost.

On the other hand, in order to shorten the treatment time and stabilize / advance the treatment, the treatment is carried out by utilizing a microbial carrier for the purpose of increasing the concentration of microorganisms in the wastewater treatment tank and increasing the residence time of the microorganisms. Methods and devices are being developed. As such an example, Japanese Patent Publication No. 59-16516 discloses a fluidized bed type biological treatment method and apparatus in which microorganisms are attached to a granular carrier and the carrier is fluidized to remove organic substances in waste water. Or, Japanese Examined Japanese Patent Publication Sho 63-52556
The publication discloses a method for biologically treating wastewater by filling a wastewater treatment tank with a carrier in which activated sludge is entrapped and fixed on a polymer carrier and contacting the wastewater treatment tank under aerobic conditions.

As another example, Japanese Patent Publication No. 1-37988, Japanese Patent Publication No. 2-7716, and Japanese Patent Laid-Open No. 4-31029.
No. 8, JP-A-7-68282, and JP-A-7-6.
Japanese Patent No. 8287 discloses a method and an apparatus for treating wastewater in which a carrier in which a denitrifying bacterium and a nitrifying bacterium are entrapped and fixed in a polymer carrier is filled in an anaerobic tank and an aerobic tank and used.

[0008] In recent years, studies have been made to fill a treatment tank with a carrier on which microorganisms adhere and proliferate to reduce the size of a wastewater treatment device. As a carrier, various ceramics, granular materials such as plastics, or a honeycomb structure is used. The body is being developed. The carrier used for wastewater treatment is required to have a high water content, excellent permeability to oxygen and substrates, and high affinity with living organisms. From such a viewpoint, for example, polyvinyl alcohol -Water solution (hereinafter polyvinyl alcohol is abbreviated as PVA) is poured into a mold and then frozen and partially dehydrated (Japanese Patent Laid-Open No. 58-36630).
Japanese Patent Publication No.), a method in which an aqueous solution of PVA is brought into contact with a saturated aqueous solution of boric acid to form a gel (Sewerage Society Journal, Volume 23 (198).
6) p41; Water and Wastewater, Volume 30 (1986) p3
6), a method in which a mixed aqueous solution of PVA and sodium alginate is brought into contact with an aqueous calcium chloride solution to be spheroidized, followed by freeze-thawing (JP-A-64-43188), and further acetalization with formaldehyde (JP-A-7-74).
-41516) and the like are known.

On the other hand, with the progress of the membrane separation technology, the separation membrane is often used for the purpose of improving the quality of treated water. For example, Japanese Examined Patent Publication 64-5960
Japanese Patent Laid-Open Publication No. 64-9071 discloses a waste water treatment device for communicating a hollow fiber membrane module with the bottom surface of a treatment tank for filtration treatment. Japanese Patent Publication No. 64-9071 discloses a treatment of a hollow fiber membrane module. There is disclosed a wastewater treatment device which is disposed on the upper part of a tank and performs a filtering process.

Further, a method for efficiently performing wastewater treatment by circulating treated water has been studied. For example, Japanese Patent Publication No. 64-9074 has a membrane module above the anaerobic tank and aeration means. Disclosed is a wastewater treatment device configured to return a part of the treated water from the aerobic tank to the anaerobic tank in a treatment tank including an aerobic tank provided with a tank.

However, in all of these, since the membrane module is installed inside the treatment tank, the settled sludge treated with the polymer carrier easily adheres to the surface of the membrane or between the hollow fiber membrane bundles, and Since the hole of No. 1 is closed, the drainage flow load cannot be taken very large, and there is a limit to downsizing of the device. Also, due to the synergistic effect of the deposition of the settled sludge on the membrane surface and the vibration of the water for water vapor and the collision of carrier particles,
The film was apt to crack or break.

On the other hand, there is also disclosed an apparatus in which a membrane module is provided outside the treatment tank by a method in which treated water is circulated. For example, in Japanese Patent Publication No. 6-45035, waste liquid is first denitrifying bacteria. Bioreactor used (I), then B
Bioreactor using OD oxidizing bacteria and nitrifying bacteria (II)
And then the treated liquid was introduced into a membrane separation device, and the non-permeated liquid that did not permeate the membrane was treated with the bioreactor (I
The permeated liquid that has permeated the membrane is transferred to the bioreactor (I) in (I).
Disclosed is a wastewater treatment method that circulates each.

Further, in Japanese Patent Laid-Open No. 4-200697, a circulation type biological treatment apparatus comprising an air-lift type flow tank and an expansion type flow tank for flowing a granular microbial carrier for treatment, and an ultrafiltration membrane device are disclosed. Disclosed is an apparatus for treating organic waste water, which comprises a part or all of the circulating water of the ultrafiltration membrane device, which is press-fitted from the bottom of the expansion type flow tank.

However, in the method disclosed in Japanese Patent Publication No. 6-45035, although the membrane module is installed outside the treatment tank, the concentration of floating activated sludge containing nitrifying bacteria is high and the membrane still remains. It has a drawback that it is apt to cause clogging. Further, in the treatment device disclosed in Japanese Patent Laid-Open No. 4-200697, a part or all of the circulating water of the ultrafiltration device is pressed from the bottom of the expansion type flow tank (denitrification tank), but the microorganism carrier overflows. Since the flow rate is limited so as not to occur, there is a drawback in that the fluidity of the carrier is insufficient and the denitrification performance is deteriorated. In addition, when the circulation amount of the liquid is large, the concentration of dissolved oxygen in the tank becomes high and the denitrification performance deteriorates.

[0015]

All of the above wastewater treatment apparatuses using membranes contribute to downsizing of the apparatus to some extent, but this type of apparatus is typified by a combined septic tank. In addition, there is a demand for an extremely compact and highly durable product that is capable of improving the quality of treated water, and no waste water treatment device that satisfies this point has yet been found.

[0016] In addition, a bad odor is often generated in wastewater treatment, and it has been pointed out as a new environmental problem. The conventional wastewater treatment method using a carrier has a wastewater treatment capacity but cannot remove odors, so that it is necessary to take measures such as providing a separate malodor treatment device. Therefore, also from the viewpoint of a bad odor, there is a demand for a carrier that does not increase in size and is economically advantageous. Therefore, an object of the present invention is to provide a wastewater treatment device which is compact, has excellent durability, has a high treatment capacity, and has a long membrane life. Another object of the present invention is to provide a wastewater treatment device that is compact, has excellent durability, and has a high treatment capacity. Another object of the present invention is to provide a wastewater treatment device which is compact, has excellent durability, has a high treatment capacity, and can be applied to wastewater that produces a foul odor.

[0017]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies, and at least a wastewater treatment tank into which carrier particles having immobilized microorganisms are added, and a membrane module for filtering treated water flowing out from the treatment tank. In the wastewater treatment equipment with, the non-permeated water that did not permeate the membrane module is returned to the treatment tank.
It has been found that the above problems can be solved by a wastewater treatment device configured to circulate, and the present invention has been completed.

That is, according to the present invention, at least a effluent treatment tank for introducing carrier particles on which microorganisms are immobilized and decomposing and removing organic matter and / or inorganic matter in wastewater, and a membrane for filtering treated water flowing out from the treatment tank. In a wastewater treatment device having a module, the non-permeated water that has not permeated the membrane module is configured to be returned and circulated to the treatment tank.

[0019]

[0020]

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the wastewater treatment apparatus of the present invention will be described more specifically with reference to the drawings. FIG. 1 is a flow chart showing an example of the wastewater treatment apparatus of the present invention, which is a wastewater treatment tank in which carrier particles having immobilized microorganisms for decomposing and removing organic substances and / or inorganic substances in wastewater are introduced. Composed of membrane module. The wastewater treatment tank may be a denitrification tank in which carrier particles having denitrifying bacteria immobilized therein are brought into contact with wastewater under anaerobic conditions, and / or carrier particles having nitrifying bacteria immobilized therein are introduced into wastewater under aerobic conditions. It is a nitrification tank to be contacted.

In the wastewater treatment equipment shown in FIG. 1, wastewater 1 containing organic substances and / or inorganic substances flows into a wastewater treatment tank 2. The carrier particles 3 on which microorganisms are immobilized are put into the wastewater treatment tank 2, and the wastewater is treated under anaerobic conditions or aerobic conditions. The waste water treatment tank 2 of FIG. 1 is an example in which an air diffuser 4 is provided. 5 is a blower for aeration. In order to prevent the outflow of the microorganism-immobilized carrier, it is preferable to provide the screen 6 in the wastewater treatment tank. The treated water flowing out of the wastewater treatment tank 2 is introduced into the membrane module 8 by the pump 7 in a cross-flow system, and the non-permeated water that has not permeated the membrane is returned and circulated from the return line 9 to the treatment tank. The ratio of the non-permeated water to the permeated water cannot be determined unconditionally because it depends on the characteristics of the membrane, but it is usually about 5 to 10 times. The treated water that has permeated the membrane is further subjected to treatment such as sterilization and discharged as treated water 10.

FIG. 2 shows that the treatment tank is preferably charged with denitrifying tank 11 in which carrier particles having denitrifying bacteria immobilized thereon are brought into contact with waste water under anaerobic conditions, and carrier particles having nitrifying bacteria immobilized therein. It is composed of a nitrification tank 16 that is brought into contact with wastewater under atmospheric conditions, and these treatment tanks are arranged in this order from the introduction side of the wastewater so that the nitrification-treated water flowing out from the nitrification tank is supplied to the membrane module 8 and A flow chart showing an example in which a part of the treated water is returned and circulated to the denitrification tank, and the non-permeated water that has not permeated the membrane module is returned and circulated to the nitrification tank and / or the denitrification tank. Is.

In the wastewater treatment equipment shown in FIG. 2, the wastewater 1 containing organic substances and / or inorganic substances flows into the denitrification tank 11. The denitrification tank 11 has carrier particles 12 on which denitrifying bacteria are immobilized.
Is put in, and the wastewater is treated under anaerobic conditions. The denitrification tank is preferably provided with a baffle plate 13 to prevent outflow of carrier particles and sludge, and it is effective and preferable to bend the tip of the baffle plate in the tank. In the denitrification tank 11, the carrier particles on which the denitrifying bacteria are immobilized are flown by the stirring device 14 provided at the bottom of the denitrification tank 11, so that sufficient carrier flow is ensured and inflow of more liquid than necessary. Therefore, the residence time can be increased.

Next, the denitrification treated water flows into the nitrification tank 16 and is treated under aerobic conditions. 4 is an air diffuser, 5
Is a blower for aeration. Further, 15 is carrier particles on which nitrifying bacteria are immobilized. As described above, it is preferable to provide each tank with a screen in order to prevent carrier particles from flowing out. The nitrification-treated water flowing out from the nitrification tank 16 is introduced into the membrane module 8 by the pump 7, and the non-permeated water that has not permeated the membrane is returned and circulated from the return line 17 to the denitrification tank and / or the nitrification tank. Further, part of the nitrification-treated water is returned and circulated from the nitrification-treated water return line 18 to the denitrification tank 11. Since nitrification-treated water contains nitrate nitrogen, if a part of the nitrification-treated water is returned to the denitrification tank for denitrification treatment, the wastewater can be efficiently treated. It is convenient to use an air lift pump (not shown) to return the nitrification-treated water to the denitrification tank. In that case, if the nitrification-treated water returned to the denitrification tank can be returned to the nitrification tank, the operation of adjusting the flow rate becomes easy.

The rate of returning the nitrification-treated water to the denitrification tank may be appropriately changed according to the properties of the wastewater to be treated, but it is usually about 1 to 5 times the permeated water of the membrane module. The ratio of the non-permeated water to the permeated water cannot be determined unconditionally because it depends on the characteristics of the membrane, but it is usually about 5 to 10 times.
Further, the rate of returning the non-permeated water to the denitrification tank and the nitrification tank is appropriately carried out depending on the nature of the drainage, and may be equally divided, for example. Hereinafter, in the waste water treatment equipment of the present invention using the membrane module, the return ratios thereof are the same. Treated water that has permeated the membrane is further treated as necessary, such as disinfection, and treated water 1
Released as 0.

In the wastewater treatment equipment of the present invention, it is more effective to provide an anaerobic filtration device or an initial settling tank for anaerobic treatment before the denitrification tank. FIG. 3 shows an example in which the anaerobic filtration device 19 or the first settling tank 20 is provided in front of the denitrification tank. Since nitrification-treated water contains nitrate nitrogen, a part of the liquid is returned to the anaerobic filtration device so as not to load the membrane module, and anaerobic filtration treatment and denitrification treatment are performed. In this case, it is preferable to install the membrane module outside the nitrification tank because the membrane life tends to be extended. The nitrification-treated water is returned by the return line 21 to the denitrification tank 11, the anaerobic filtration device 19 or the first settling tank 20, and the non-permeated water that has not permeated the membrane module is returned to the nitrification tank 16 by the non-permeated water return line 22. .

By returning and circulating the treatment liquid in this manner, the function of the immobilization carrier can be sufficiently brought out, and a more compact device can be obtained. According to such an apparatus, since the excess sludge is also reduced to a fraction of that in the case of the usual activated sludge method, the sludge load on the membrane module is reduced,
The merit of placing the membrane module on the outside can be fully utilized, and the life of the membrane can be extended. The rate of return from the nitrification tank to the anaerobic filtration device can be appropriately changed depending on the nature of the wastewater, but it is usually 1 to 5 times that of the permeate in the membrane module, and non-permeate in the membrane module. The ratio of the liquid returned to the nitrification tank is about 1 to 10 times that of the treated permeate.

In the anaerobic filtration device 19, suspended matters in the waste water are removed, but since anaerobic bacteria adhere to the filter material, the anaerobic filtration device also performs anaerobic treatment. In addition, since a part of the nitrification-treated water is circulated, the nitrification-treated water is responsible for a part of the denitrification process, and the capacity of the denitrification tank can be smaller than that when the nitrification-treated water is circulated to the denitrification tank. The filter material used in the anaerobic filtration device is not particularly limited as long as the suspended matter can be removed, and for example, fibers, plastics, and molded products thereof can be used. It is preferable that these filter materials have a small pressure loss and a large amount of adherence of microorganisms, and it is preferable to use a filter material molded in a lattice shape.

In FIG. 3, when the anaerobic filtration device is used, the wastewater 1 is first introduced into the anaerobic filtration device 19 to remove suspended matters and the like. As described above, in the anaerobic filtration device 19, since anaerobic bacteria adhere to the filter material, anaerobic treatment is also performed at the same time. In the wastewater treatment equipment of the present invention, a precipitation tank may be installed first before the denitrification tank. In this case, the wastewater 1 is first introduced into the settling tank 20, where the suspended solids in the wastewater are settled in advance.

FIG. 4 shows an example in which the wastewater treatment tanks are a nitrification tank and a denitrification tank, which are arranged in this order from the wastewater introduction side. In this case, it is necessary to supplement the denitrification tank with an organic carbon source for the growth of denitrifying bacteria. In recent years, merger processing for simultaneously treating human waste and household wastewater has been spreading, but removal of nitrogen components has become a major issue as a measure for eutrophication of water bodies as well as treatment of BOD components. The waste water treatment apparatus of the present invention solves such a problem, and since it requires a small installation space, it is suitable for use as a combined septic tank. FIG. 5 is an example in which the wastewater treatment device of FIG. 3 is integrated as a combined septic tank. FIG. 5 shows an example in which the membrane module is provided outside the nitrification tank and the nitrification-treated water is pumped into the membrane module by a pump, but it goes without saying that suction filtration or gravity filtration may be used. The blower for aerating to the nitrification tank is not shown.

A carrier on which microorganisms such as denitrifying bacteria and nitrifying bacteria are immobilized is introduced into the denitrification tank and / or the nitrification tank. By using such a carrier, the load of the SS component is reduced. As a carrier for immobilizing denitrifying bacteria or nitrifying bacteria as microorganisms, vinyl alcohol resin, acrylic resin, acrylamide resin, olefin resin,
Examples thereof include styrene-based resins, polyurethane-based resins, polysaccharides, polyethers, porous inorganic compounds, and the like. Specifically, PVA-based, polyethylene glycol-based, polyacrylamide-based, calcium alginate, carrageenan, Examples thereof include agar, polymer gels such as photocurable resins, activated carbon, polyurethane sponge, polyacrylonitrile, polyethylene, polypropylene, polystyrene, cellulose derivatives, and polyester.

As the carrier, when bacteria are attached, BO
D A high molecular weight hydrogel is preferable from the viewpoints of removal ability, nitrification ability and denitrification ability. When a hydrogel is used, the hydrogel flows in a treatment tank to come into contact with the membrane surface and clear the membrane surface. The effect of training is great. Among them, since the PVA-based hydrogel has a network structure on the surface and inside of the carrier, microorganisms can easily inhabit it, and it is excellent in capturing organic compounds, and is also excellent in mechanical strength. preferable. Moreover, since the higher the average degree of polymerization and / or the degree of saponification of PVA, the lower the concentration of PVA,
The water content of the gel can be increased, and thus the habitability of microorganisms is improved, which is preferable. From this point, the average degree of polymerization of PVA is preferably 1000 or more, and particularly 1
It is more preferably 500 or more. The degree of saponification of PVA is preferably 95 mol% or more, and particularly 98
More preferably, it is at least mol%.

The concentration of PVA is preferably high from the viewpoint of the strength of the carrier, and is preferably low from the habitability of microorganisms, so 1 wt% to 40 wt% is preferable, and 3 wt% to 2 wt%.
0 wt% is more preferable.

In order to prevent elution and deterioration of PVA, P
It is desirable to acetalize the VA. Examples of the acetalizing agent include formalin, glutaraldehyde, glyoxal, terephthalaldehyde, ω, ω′-nonanedial and the like. Polyvinyl polymer
Are preferred examples of such acetalized PVA. If the degree of acetalization is too low, the water resistance will be low, and if it is too high, it will be hydrophobized and the habitation of microorganisms will be impaired, so 10 to 60 mol% is preferable, and 20 to 55 mol% is more preferable.

Acids for acetalization include acids such as sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, acetic acid and oxalic acid, and
Acid salts such as sodium hydrogensulfate and ammonium hydrogensulfate are used. However, in the presence of an aldehyde compound or an acid, the hydrous gel may swell or dissolve. As its inhibitor, PVA
You may add sodium sulfate etc. which have the synergic action.

Within a range that does not inhibit the acetalization of PVA, for example, a molding aid such as sodium alginate, carrageenan, boric acid, or two or more kinds of carbonate ion, hydrogen carbonate ion, sulfate ion, phosphate ion and the like. A monovalent or polyvalent anion that causes phase separation of the polymer may be added.
The acetalized PVA-based gel has an uneven structure on the surface and has finger-shaped communication holes from the surface to the central portion, and is suitable for inhabiting microorganisms.

The acetalized PVA hydrogel used in the present invention has hydrophilicity because it has a hydroxyl group in the molecule, and has high habitability for microorganisms. This acetalized PVA-based hydrogel is a wastewater treatment tank for treating organic wastewater under aerobic conditions, and a denitrification tank for biological denitrification under anaerobic conditions and / or organisms under aerobic conditions. The microorganisms existing in the water to be treated are effectively attached / bonded and immobilized on the outer surface and the inside of the carrier by being placed in a nitrification tank that performs nitrification. The acetalized PVA-based hydrogel has a specific gravity of 1.00 to 1.05 when the attachment and binding of microorganisms reaches a steady state in the tank, so that it can flow uniformly in the tank. From the viewpoint of, it is also preferable.

The acetalized PVA gel-like carrier is separated from the acetalized liquid, and is subjected to treatments such as washing with water and neutralization,
It becomes a carrier that can be used for wastewater treatment and deodorization. The gel carrier may be dried once. When immersed in water, it becomes a hydrogel again. The higher the water content is, the more preferable is 50 to 99% on a wet weight basis, and the more preferable is 60 to 9%.
8%. The water content based on wet weight is measured by immersing the carrier in water at 25 ° C for 24 hours or more, and then measuring the weight of the carrier excluding water adhering to the surface (wet weight).
After drying for 4 hours, the weight is measured (dry weight). Moisture content based on wet weight is (wet weight-dry weight) / wet weight x 100
It is represented by (%).

The most preferred hydrogel is the one already filed by the applicant as Japanese Patent Application No. 9-11057, in which 10 or more concave portions having an average diameter of 10 to 100 μm and a depth of 10 to 100 μm are formed on the surface per 1 mm of the surface length. An acetalized PVA-based hydrogel having a water content of 50% by weight or more, the content of which is further supplemented by Japanese Patent Application No. 9-34204.
PV having a net-like structure formed by intertwining fibrous materials having a diameter of 0.1 to 50 μm, applied as No. 7, as a surface layer
It is an A-type hydrous gel. The method for producing this hydrous gel is
As described in detail in the above specification, as an example, PVA8w having an average polymerization degree of 1700 and a saponification degree of 99.8 mol% is used.
t%, sodium alginate 1 wt%, sodium hydrogen carbonate 0.3 wt% was prepared, and the aqueous solution was added dropwise to a 0.1 mol / liter calcium chloride aqueous solution to obtain a spherical molded product. It can be obtained by immersing in formaldehyde 20 g / liter, sulfuric acid 200 g / liter and sodium sulfate 100 g / liter in an aqueous solution for acetalization and washing with water.

The shape of the carrier is not particularly limited, and any shape such as a fibrous shape, a dice shape, a film shape, a cylindrical shape, a hollow cylindrical shape, a spherical shape, or a disc shape can be used. From the viewpoint of the fluidity of the carrier, the spherical one is preferable.

Activated carbon is excellent not only in its ability of adsorbing and removing deodorant organic substances which it originally has, but also in its ability to remove BOD, denitrification and nitrifying ability of microorganisms attached to activated carbon and proliferated. It is a preferred carrier. When activated carbon is used as a carrier, the organic matter adsorbed by activated carbon is decomposed and removed by microorganisms, whereby activated carbon is bioregenerated, the adsorption capacity can be maintained for a long time, and the load of SS components is also reduced. Furthermore, activated carbon has good durability and mechanical abrasion resistance. When using activated carbon in a floating flow,
The effect of cleaning the surface of the film is great. However, activated carbon is not so good in fluidity as other water-containing gels and is liable to be aggravated by a rapid flow. Therefore, in order to fully bring out the performance of activated carbon, it is preferable to fix it to a waste water treatment tank. The carrier may include activated carbon as part of the carrier.

As the activated carbon, charcoal, coal, coke,
Those produced by using coconut husk, resin, petroleum pitch, etc. as raw materials are used, but various raw material carbides such as wood-based, coal-based, resin-based, pitch-based, etc. are gas activated, steam activated, and chemical activated. Those activated by the method described above are preferred. As an activation method, a method of activation with zinc chloride or phosphoric acid is effective and preferable.

The quality of activated carbon has a packing specific gravity of 0.10 to 0.
70 g / cm ³ , preferably 0.15 to 0.60 g / c
m ³ , specific surface area 300 to 2800 m ² / g, preferably 600 to 2500 m ² / g, pore radius 10 nm to 500
The pore volume in the range of μ is 0.1 to 2.5 ml / g, preferably 0.5 to 2.0 ml / g, and the particle diameter is 0.1 to 8 mm. Among them, the wood-based one is preferable because it has a network structure on the surface and inside of the carrier, and thus microorganisms are easily attached to it and it is excellent in capturing organic compounds and odorous components. Since activated carbon is easily broken when it flows, it is preferable to use it in the form of a fixed bed or the like in order to fully bring out the function of activated carbon.

Waste water often gives off a bad odor, and in such a case, it is preferable to use a carrier containing activated carbon. To produce such a carrier, for example, PV
A mixed water suspension of a carrier raw material such as A, a molding aid such as sodium alginate, and activated carbon may be prepared and gelled. The concentration of the aqueous suspension is not particularly limited, but from the viewpoint of easy gelation, the carrier raw material is usually 1 to 40 w.
t%, molding aid 0.1 to 5 wt% and activated carbon 0.1 to 5
It is carried out at wt%. A spherical gel can be obtained by dropping this aqueous suspension into a calcium chloride aqueous solution from a nozzle.

The distribution state of the activated carbon on the surface and / or inside of the carrier is not particularly limited, but it is of course preferable that the activated carbon is uniformly distributed. If the content ratio of the activated carbon in the carrier is too small, the deodorizing effect is small, so that the content ratio of 0.5 to 5 wt% is preferable. When the PVA-based gel is an acetalized PVA-based gel, since the surface has an uneven structure and has a communication hole from the surface to the center, the effect of not only the activated carbon on the surface but also the activated carbon inside is effective. It is suitable because it can be pulled out to the outside.

The quality of the activated carbon contained in the carrier raw material has a packing specific gravity of 0.10 to 0.70 g / cm ³ , preferably 0.
15-0.60 g / cm ³ , specific surface area 300-2800
m ² / g, preferably 600~2500m ² / g, a pore volume in the range of pore radius 10 nm to 1 m 0.1 to 2.5
ml / g, preferably 0.5 to 2.0 ml / g, and a particle size of 1 μm to 100 μm are suitable. Among them, the wood-based one is preferable because it has a network structure on the surface and inside of the carrier, and thus microorganisms are easily attached to it and it is excellent in capturing organic compounds and odorous components.

As the shape of the activated carbon, various shapes such as granular shape, powder shape and fibrous shape can be used, but the powder shape is preferable in order to make it uniformly exist in the carrier. As an example of activated carbon, Kuraray Chemical Co., Ltd., trade name Kuraray Kol, Toyo Calgon Co., Ltd., trade name F
400, trade name BAC manufactured by Kureha Chemical Industry Co., Ltd., trade name FX-300 manufactured by Toho Rayon Co., Ltd., and the like.

The denitrification tank and the nitrification tank are filled with carrier particles on which denitrifying bacteria or nitrifying bacteria are immobilized. The same carrier particles may be used in each tank, or different carrier particles may be used. Good. For example, a case using hydrous gel such as PVA for both the denitrification tank and the nitrification tank, a case using activated carbon for both the denitrification tank and the nitrification tank, activated carbon for the denitrification tank, and hydrous gel for the nitrification tank. There are various cases such as a case in which a hydrogel is used in a case and a denitrification tank and a case in which activated carbon is used in a nitrification tank, which can be appropriately implemented as desired. The denitrifying bacteria and the nitrifying bacteria may be used after being immobilized on carrier particles in advance, but it is also possible to put the carrier particles in a tank and use that the bacteria naturally adhere.

The material of the separation membrane used in the membrane module should be durable, for example, polysulfone type, polyacrylonitrile type, polyolefin type, cellulose type,
Examples thereof include polyamide-based, polyester-based, polyvinyl alcohol-based, poly (meth) acrylic acid ester-based, and polyimide-based resins. From the viewpoint of separation performance, it is preferable to use a microfiltration membrane or an ultrafiltration membrane.

When a hydrophilic or hydrophilized membrane is used for the membrane module, SS components are less likely to adhere to the membrane,
Even if the components adhere, they are preferable because they are easily peeled off by backwashing with air or a permeate. Vinyl alcohol-based resins such as polyvinyl alcohol are preferred examples of hydrophilic membranes. In addition, hydrophobic resins such as polysulfone type and polyolefin type are used for vinyl alcohol such as polyvinyl alcohol.
You may use the film hydrophilized by the resin of a resin type. Needless to say, a vinyl alcohol-based resin may be used in the form of acetal.

As these membranes, any shape such as hollow fiber or flat membrane can be used. However, it is preferable to use the hollow fiber shape from the viewpoint of handleability and compactness, for example, an inner diameter of 200. Those having a thickness of about 2,500 μm are preferably used. The hollow fiber membrane module is used in a required number in series or in parallel according to the amount of treatment.

The membrane module may be used by immersing it inside the nitrification tank or installed outside the nitrification tank. When the membrane module is immersed in the nitrification tank for use, the nitrification-treated water is usually subjected to suction filtration or gravity filtration. When the membrane module is installed outside the nitrification tank and used, the nitrification-treated water may be injected by a pump, suction filtration or gravity filtration. In Fig. 1, the membrane module is installed outside the nitrification tank,
This is an example of press-fitting nitrification-treated water with a pump. When a hollow fiber membrane module is used as the membrane module, an internal pressure filtration method in which treated water is passed inside the hollow fiber or an external pressure filtration method in which treated water is passed outside the hollow fiber may be used. The use of is preferable because clogging of the film can be reduced.

FIG. 6 shows a wastewater treatment apparatus according to the present invention, which is a wastewater treatment apparatus comprising a wastewater treatment tank in which at least carrier particles on which microorganisms are immobilized are charged and organic substances and / or inorganic substances in wastewater are decomposed and removed. 1 is an example of a waste water treatment apparatus using a carrier in which microorganisms are immobilized on an acetalized PVA-based hydrogel, and is a flowchart in the case of decomposing and removing organic substances in waste water under aerobic conditions. 2 is a wastewater treatment tank, and 24 is a final settling tank. First, the wastewater 1 is first supplied to the wastewater treatment tank 2 from a settling tank (not shown). In the wastewater treatment tank 2, the acetalized PV was previously added to the drainage at the lower limit of operation.
A water-containing gel 23 is put in and fluidized by an air diffuser 4 provided at the bottom of the wastewater treatment tank 2. A blower 5 is connected to the air diffuser 4, and is a drive unit of the air diffuser 4. The wastewater is biologically treated in the wastewater treatment tank 2.

When the air is blown from the air diffuser 4 while introducing the wastewater 1 into the wastewater treatment tank 2, oxygen is supplied to the mixed liquid in the wastewater treatment tank 2, and the rising bubble flow causes Circulating flow occurs in the processing tank. By this circulating flow,
In the process in which the acetalized PVA hydrogel 23 flows in the wastewater treatment tank 2, microorganisms that decompose and remove organic substances are attached, bonded and immobilized to the hydrogel 23. Therefore, as a result of sufficient contact between the microorganisms and the organic matter, the organic matter in the mixed solution is
It is decomposed and removed very efficiently and at high speed. In addition, the microorganisms immobilized inside the carrier do not easily peel off when the acetalized PVA water-containing gel 23 flows in the mixed solution.
Various screens and the like may be appropriately provided in the treatment tank in order to prevent the acetalized PVA-based hydrogel from overflowing.

The biologically treated treated water is sent to the final settling tank 24, where the sediment is removed from the sludge discharge pipe 25, and the supernatant water 26 is discharged. The wastewater treatment tank used in the wastewater treatment apparatus of the present invention can improve the efficiency of wastewater treatment by using an acetalized PVA-based hydrogel, but a water-containing solution obtained by mutually combining the above conditions. The use of gel can dramatically improve the wastewater treatment effect.

FIG. 7 is a flow chart showing another embodiment of the present invention in which the denitrification tank and the nitrification tank are arranged in this order from the side of introducing the water to be treated. Reference numeral 11 is a denitrification tank, and 16 is a nitrification tank. When the wastewater 1 is supplied to the denitrification tank 11, the wastewater 1 is biologically denitrified by the microorganisms in the denitrification tank under anaerobic conditions (oxygen-free conditions) and sent to the nitrification tank 16 as denitrification water 27. . The denitrification-treated water sent to the nitrification tank 16 is biologically nitrified by the microorganisms in the nitrification tank under aerobic conditions. A part of the nitrification-treated water 28 is circulated and returned to the denitrification tank 11 by the nitrification-treated water return line 29, and the remaining nitrification-treated water is sent to the final settling tank 24 to remove the sediment, and then the supernatant water 26. Released as. The rate of returning the nitrification-treated water 28 to the denitrification tank 11 is about 1 to 5 times that of the supernatant water 26. The generated sludge is taken out of the system by the sludge discharge pipe 25.

A stirrer 14 is installed in the denitrification tank 11, and a spherical acetalized PVA water-containing gel 23 is put into the mixed solution containing microorganisms in the denitrification tank 11. An organic carbon source is supplied to the denitrification tank as needed.

At the bottom of the nitrification tank 16, an air diffuser 4 for supplying a gas such as air containing oxygen is connected to a blower 5 and installed in the nitrification tank 16 for mixing a mixture containing microorganisms. The same spherical acetalized PVA water-containing gel 23 as that used in the denitrification tank is charged. Acetalized P
The VA-based hydrogel may be put into both the denitrification tank and the nitrification tank for use, or may be put into either one, but it is more efficient to put it in both. , It is usually used by putting it in both tanks. Different types of acetalized PVA may be added to each tank.

In this device, drainage 1 is placed in the denitrification tank 11.
When the stirrer 14 is operated in a state where the denitrification treated water 27 is allowed to flow into the nitrification tank 16 while introducing P, a circulating flow of the mixed liquid is generated in the denitrifying tank 11, and this circulating flow causes acetalization P
The VA hydrous gel 23 flows in the denitrification tank 11, and microorganisms mainly in the denitrifying bacterium existing in the mixed liquid adhere to, bond to and be immobilized on the hydrous gel 23 during the period. The mixed liquid in the tank is denitrified by the immobilized denitrifying bacteria and the floating denitrifying bacteria. The organic matter in the mixed solution is used as a respiratory substrate for denitrifying bacteria or as a carbon source for cell synthesis, but as described above, the carbon source may be added from outside the system as necessary.

In the nitrification tank 16, when the denitrification-treated water 27 is supplied from the denitrification tank 11 and the nitrification-treated water 28 in the nitrification tank 16 flows out from the air diffuser 4, the inside of the nitrification tank 16 is changed. While oxygen is supplied to the mixed solution of (1) and a circulating flow of the mixed solution is generated by the rising bubble flow at this time, microorganisms mainly composed of nitrifying bacteria present in the mixed solution adhere to the acetalized PVA hydrogel 23. -It is fixed by binding. The immobilized nitrifying bacteria and floating nitrifying bacteria biologically nitrify the mixed solution in the tank.

As a result, the microorganisms adhere to, bond to and are immobilized on the surface and / or the inside of the acetalized PVA hydrogel 23, so that the components to be treated and the microorganisms come into sufficient contact with each other. In addition, the microorganisms immobilized inside the carrier are
Even when the acetalized PVA hydrogel 23 flows in each tank, it does not easily peel off. As a result, nitrogen in the water to be treated is decomposed and removed extremely efficiently and at high speed. Of course, a screen or the like may be provided in the denitrification tank and / or the nitrification tank in order to prevent the hydrous gel from overflowing outside the tank.

FIG. 8 is another flow chart of the present invention in which a denitrification tank and a nitrification tank are arranged in this order from the waste water introduction side, and an anaerobic filter or a first precipitation tank is provided in front of the denitrification tank. Drainage 1
Is biologically denitrified by the microorganisms in the denitrification tank under anaerobic conditions, and then the denitrified water 27 is biologically nitrified by the microorganisms in the nitrification tank under aerobic conditions. A part of the nitrification-treated water 28 is circulated and returned to the denitrification tank 11 and the anaerobic filtration device 19 or the first settling tank 20, and the rest of the nitrification-treated water is sent to the final settling tank 24 to remove the sediment. It is discharged as clear water 26. The ratio of the denitrification tank 11 and the anaerobic filtration device 19 to the supernatant water 26 or the nitrification-treated water 28 returned to the first precipitation tank 20 is about 1 to 5 times. The rate of return to the denitrification tank 11 and the anaerobic filtration device 19 or the first settling tank 20 may be appropriately performed according to the properties of the wastewater. These return ratios are the same in the wastewater treatment equipment that does not use the membrane module of the present invention. The generated sludge is taken out of the system by the sludge discharge pipe 25.

FIG. 9 is another flow chart of the present invention in which the nitrification tank and the denitrification tank are arranged in this order from the waste water introduction side. The waste water 1 is biologically nitrified by the microorganisms in the nitrification tank under aerobic conditions, and then the nitrification-treated water 30 is biologically denitrified by the microorganisms in the denitrification tank under anaerobic conditions. The denitrification-treated water 31 is sent to the final settling tank 24, and after removing the sediment, it is discharged as the supernatant water 26. The generated sludge is taken out of the system by the sludge discharge pipe 25. The wastewater treatment device described above is suitable as a combined septic tank, and FIG.
6 is an example in which the wastewater treatment equipment shown in FIG. 6 is used as a combined purification tank using the first settling tank, and FIG. 11 is an example in which the wastewater treatment apparatus shown in FIG. 8 is used as a combined purification tank using the first settling tank. is there. Although not shown, the sludge accumulated in the final settling tank may be appropriately returned to the first settling tank and discharged from the first settling tank.

[0065]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. Reference Experimental Example 1 PVA (average degree of polymerization: 1700, saponification degree: 99.8 mol%) 8% by weight, sodium alginate (Kibun Fudochemifa "Duck Algin NSPL") 1% by weight, sodium hydrogencarbonate 0.3% by weight % Mixed aqueous solution was prepared.
The mixed aqueous solution was phase-separated into a suspension and was cloudy. This phase-separated liquid was sent at a rate of 5 ml / min using a roller pump equipped with a silicon tube having an inner diameter of 4 mm and a nozzle having an inner diameter of 3 mm attached to the tip thereof, and was stirred with a stirrer to a concentration of 0.1 mol / liter. Was added dropwise to the aqueous calcium chloride solution. At least the sodium alginate on the surface of the dropped liquid droplets solidified and settled in the calcium chloride aqueous solution. The solidified product obtained was spherical.

This spherical solidified product was treated with formaldehyde 20
By dipping in an aqueous solution containing g / liter, 200 g / liter of sulfuric acid, and 100 g / liter of sodium sulfate at 40 ° C. for 60 minutes, coagulation and gelation were performed, and at the same time, acetalization treatment was performed. The obtained acetalized gel was washed with water to produce a flexible spherical hydrogel having a diameter of about 5 mm.

Observing the structure of the obtained gel, the surface layer has a net-like structure formed by intertwining fibrous substances having a diameter of about 0.3 to 10 μm, and the thickness of the surface layer is 5% /
It was about the maximum diameter of the gel. In addition, a dense inner layer having pores with a pore diameter of about 1 to 10 μm was formed inside the gel, and the thickness of the inner layer was about 75% / gel maximum diameter. Further, between the surface layer and the inner layer, there is formed an intermediate layer in which a large number of finger-shaped voids having a pore diameter of about 100 μm oriented from the surface layer to the inner layer are formed, and the thickness of the intermediate layer is 20%. Degree / maximum gel diameter.

Example 1 20% by volume of the PVA water-containing gel prepared in Reference Experimental Example 1 was placed in a 1 m ³ aerobic tank, and the hollow fiber inner diameter was 2 mm and the membrane area was 1
0 m ^2, was combined with membrane module made of polysulfone UF membrane having a cut-off molecular weight 13000 (manufactured by Kuraray Co. 6304 film) constitute a waste water treatment apparatus as shown in FIG. BOD2500mg / liter (L) drainage 1m
^It was supplied to the aerobic tank at ³ / day, the aerobic treated water was introduced into the inside of the hollow fiber membrane, and the mixture was filtered by a cross flow method. The non-permeate that did not permeate the membrane module was returned to the aerobic tank at a flow rate 10 times that of the permeate that permeated the membrane module.
After continuous treatment for 6 months, the BOD of the treated water is 200
˜300 mg / L, SS was stable at 0 mg / L.
The membrane was hardly clogged and the membrane module cleaning operation was completely unnecessary.

[0069] Example 2 0.2 m ³ of the PVA hydrogel used in Example 1 to nitrification tank denitrification and 0.2 m ³ was charged 20% by volume, Example 1
The same wastewater treatment equipment as shown in FIG. 2 was constructed by combining the same membrane modules as above and arranging them in this order from the wastewater introduction side. Waste water containing 200 mg / L of BOD and 50 mg / L of total nitrogen was supplied to the denitrification tank at 1.3 m ³ / day, the nitrification-treated water was introduced into the inside of the hollow fiber membrane, and the mixture was filtered by a cross flow method. The nitrification-treated water was returned to the denitrification tank at a flow rate three times that of the permeate that passed through the membrane module, and the non-permeate that did not permeate the module was returned to the nitrification tank at a flow rate of ten times that of the permeate, for one year. After continuous treatment, the BOD of the treated water was 6-9 mg /
L and SS were stable at 0 to 3 mg / L. Further, the clogging of the film was hardly recognized.

Example 3 A 0.5 m ³ first settling tank was provided in front of the denitrifying tank of Example 2, and the nitrification-treated water was returned to the denitrifying tank and the first settling tank, as shown in FIG. Configured wastewater treatment equipment. The nitrification-treated water was continuously treated for 1 year in the same manner as in Example 2 except that it was returned to the denitrification tank and the first settling tank at a ratio of 50:50 at a flow rate three times that of the permeated water that passed through the membrane module. BOD of finished water is 2-6 mg / L, SS is 0-3
It was stable at mg / L. Further, the clogging of the film was hardly recognized.

Example 4 A nitrification tank, a denitrification tank and a membrane module were arranged in this order from the side where the waste water was introduced to construct the waste water treatment apparatus shown in FIG. The same PV used in Example 1 for the nitrification tank and the denitrification tank
20% by volume of gel A was added, and waste water containing 200 mg / L of total nitrogen was supplied to the nitrification tank at 0.4 m ³ / day. The non-permeate that did not permeate the membrane module was returned to the nitrification tank at a flow rate of 10 times the permeate that permeated the membrane module and continuously treated for 1 year. The total nitrogen in the treated water was 10 to 15 mg /
L and SS were stable at 0 to 3 mg / L. Further, the clogging of the film was hardly recognized.

Example 5 0.5 m ³ first settling tank, 0.2 m ³ denitrification tank, 0.2
Using the m ³ nitrification tank and the same membrane module as in Example 1, a combined septic tank as shown in FIG. 5 was constructed. 20% by volume of the polyvinyl formalized hydrous gel prepared in Reference Experimental Example 1 was added to the denitrification tank and the nitrification tank, and domestic wastewater of a family of 5 was supplied to the first precipitation tank at 1.3 m ³ / day. The nitrification-treated water was first returned to the settling tank and the denitrification tank at a ratio of 50:50 at a flow rate three times as high as the permeated water that passed through the membrane module.
In addition, non-permeated water that did not permeate the membrane module was returned to the nitrification tank at a flow rate of 10 times the permeated water that permeated the membrane module, and was continuously treated for 1 year.
Was stable at 7 to 10 mg / L, and SS was stable at 0 to 3 mg / L. Further, the clogging of the film was hardly recognized.

Comparative Example 1 Example 1 except that the aerobic treated water was totally filtered through a membrane module.
When operated in the same manner as above, the membrane became clogged on the 8th day, and the operation became difficult. When the operation was continued without cleaning the membrane, the operation was stopped because the treated water overflowed from the aerobic tank.

Example 6 20% by volume of the acetalized PVA water-containing gel prepared in Reference Experimental Example 1 was added to a 1 m ³ aerobic tank and combined with a 0.6 m ³ final precipitation tank as shown in FIG. Configured wastewater treatment equipment. BOD 2500 mg / liter (L) of waste water was supplied to the aerobic tank at 1 m ³ / day and continuously treated for 6 months. The BOD of the treated water was 200 to 300 mg / day.
L and SS were stable at 20 to 30 mg / L.

[0075] Example 7 0.2 m ³ and that used in Example 6 to nitrification denitrification tank and 0.2 m ³ of the same PVA hydrogel was charged 20% by volume, and a final sedimentation tank of 0.6 m ³ By combining them, a wastewater treatment device as shown in FIG. 7 was constructed. BOD 200mg /
L, total nitrogen 50 mg / L wastewater was supplied to the denitrification tank at 1.3 m ³ / day, and the nitrification-treated water was returned to the denitrification tank at a flow rate three times that of the supernatant water and continuously treated for 1 year. Jishui B
The OD was stable at 8 to 10 mg / L and the SS was stable at 10 to 15 mg / L.

Example 8 A 0.5 m ³ first settling tank was provided in front of the denitrifying tank of Example 7, and the nitrification-treated water was returned to the denitrifying tank and the first settling tank, as shown in FIG. Configured wastewater treatment equipment. The nitrification-treated water was continuously treated for 1 year in the same manner as in Example 7 except that it was returned to the denitrification tank and the first settling tank at a ratio of 50:50 at a flow rate three times that of the supernatant water. 6
-9 mg / L, SS was stable at 6-8 mg / L.

Example 9 A nitrification tank, a denitrification tank, and a final precipitation tank were arranged in this order from the waste water introduction side to construct a waste water treatment apparatus as shown in FIG. When the wastewater containing 200 mg / L of total nitrogen was supplied to the nitrification tank at a rate of 0.4 m ³ / day and continuously treated for 1 year, the total nitrogen of the treated water was 10 to 15 mg / L and the SS was 10 to 20.
It was stable at mg / L.

Example 10 0.5 m ³ of first settling tank, 0.2 m ³ of aerobic tank and 0.
A combined septic tank as shown in Fig. 10 was constructed using a final settling tank of 3 m ³ . The same PVA water-containing gel as used in Example 6 was added to the aerobic tank in an amount of 20% by volume, and domestic wastewater of a family of 5 was first supplied to the precipitation tank at 1.3 m ³ / day. 1
After continuous treatment for a year, the BOD of treated water is 8-10
The mg / L and SS were stable at 10 to 15 mg / L.

Example 11 0.5 m ³ first settling tank, 0.2 m ³ denitrification tank, 0.2
Figure 1 using m ³ nitrification tank and 0.3 m ³ final settling tank
A combined septic tank as shown in 1 was constructed. 20% by volume of the same PVA water-containing gel as used in Example 6 was put into the denitrification tank and the nitrification tank, and the domestic wastewater of a family of 5 was 1.3 m ³ /
It was first supplied to the settling tank in the day. The nitrification-treated water was returned to the denitrification tank and the first sedimentation tank at a ratio of 50:50 at a flow rate three times that of the supernatant water, and continuously treated for 1 year.
OD was stable at 6-9 mg / L and SS was stable at 6-8 mg / L.

[0080] The nitrification tank denitrification and 0.2 m ³ of Comparative Example 2 0.2 m ^3, the activated sludge was introduced so that 6000 mg / L, shown in Figure 12 in combination with the settling tank of 0.3 m ³ The wastewater treatment equipment was constructed as follows. The nitrification-treated water was returned to the denitrification tank at a flow rate three times that of the supernatant water, and the wastewater containing 200 mg / L of BOD and 50 mg / L of total nitrogen was continuously treated at 1.3 m ³ / day. Is 90 to 120 mg / L,
Total nitrogen had an insufficient water quality of 25 to 35 mg / L.
Further, the SS concentration of the treated water is as high as 150 to 250 mg / L, and it was necessary to pull out excess sludge from the settling tank every week in order to maintain this water quality.

Reference Experimental Example 2 PVA (average degree of polymerization: 1700, saponification degree: 99.8 mol%) 8 wt%, sodium alginate 1 wt%, activated carbon (P-6 manufactured by Kuraray Chemical Co., Ltd.)
0) An aqueous suspension containing 1 wt% was prepared. This water suspension has an inner diameter of 4 m with a 3 mm inner diameter nozzle attached to the tip.
A roller pump equipped with an m silicon tube was used to feed the solution at a rate of 5 ml / min, and the solution was added dropwise to a 0.1 mol / l calcium chloride aqueous solution stirred by a stirrer. The dropped droplets were spheroidized and settled in an aqueous calcium chloride solution.

This spherical molded product was treated with formaldehyde 20
g / l, sulfuric acid 200 g / l, sodium sulfate 100 g /
It was immersed in 1 of 40 ° C. aqueous solution for 60 minutes and washed with water to obtain a flexible spherical hydrogel having a diameter of about 5 mm. This gel had an acetalization degree of 39 mol% and a water content of 93%. As a result of observing with an optical microscope and an electron microscope,
1 μm from the surface of the acetalized PVA carrier to the center
There were innumerable finger-shaped communication holes in the front and back.

Reference Experimental Example 3 As PVA, the average degree of polymerization was 4000 and the degree of saponification was 99.8.
The diameter was the same as in Example 1 except that an aqueous suspension containing 8% by weight of PVA, 0.25% by weight of sodium alginate, and 1% by weight of activated carbon (P-60) manufactured by Kuraray Chemical Co. was used. A hydrogel of about 5 mm was obtained. The degree of acetalization of this carrier was 37 mol% and the water content was 92%. As a result of observing the carrier with a microscope in the same manner as in Example 1, similar communication holes were observed.

Example 12, Example 13 1 L of the carrier obtained in Reference Experimental Examples 2 and 3 was placed in a 10 L aeration tank for aeration, and the TOC 100 ppm drainage was 42 m.
It was introduced continuously at L / min. 2 openings at the exit of the aeration tank
mm wire mesh was attached to prevent the carrier from flowing out. The TOC of the treated water after 10 days was 8.6 ppm and 7.5, respectively.
It was ppm, and sufficient treatment was performed. After that, remove the carrier, put it in a 20 L closed container, and add water to
I put L. Air containing 10 ppm of hydrogen sulfide was caused to flow in the gas phase of this container at 10 L / min, and after 5 minutes, ventilation was stopped and the container was sealed. After standing for 15 minutes, the gas phase was collected with a microsyringe and analyzed by gas chromatography. The hydrogen sulfide concentration was below the detection limit.

Reference Experimental Example 4 18% by weight of acrylamide, 1% by weight of methylenebisacrylamide, activated carbon (P-
60) NNN'N'-tetramethylethylenediamine 0.
5 wt% and 0.25 wt% potassium persulfate were added, and the mixture was polymerized at room temperature with stirring and cast to form a sheet having a thickness of 4 mm.
A gourd was obtained. This was cut into 4 mm dice to obtain a carrier. The water content of this carrier was 80%. As a result of observing with a microscope, the activated carbon was almost uniformly dispersed from the vicinity of the surface of the carrier to the central part, but no communication hole was observed.

Example 14 A wastewater treatment test was conducted in the same manner as in Examples 12 and 13, and the TOC was 43.2 ppm and the hydrogen sulfide concentration was 0.7 ppm.

In order to confirm the effect of the microorganism-immobilized carrier having activated carbon, the same procedure as in Reference Experimental Example 2 was used without using activated carbon, and the degree of acetalization was 38 mol% and the water content was 93%.
% Hydrous gel was obtained. The presence of the communication holes was the same as in Reference Experimental Example 2 or 3, but when a test similar to that in Example 12 was performed, the hydrogen sulfide concentration was 8.7 ppm, which was hardly reduced.

[0088]

Industrial Applicability According to the present invention, it is possible to provide a wastewater treatment apparatus which is compact, has excellent durability, has a high treatment capacity, and can be stably operated for a long period of time. Also, denitrification tank and /
Alternatively, when a microbial carrier having an acetalized PVA gel as a carrier is used in the nitrification tank, the durability of the carrier is excellent, so that the wastewater can be treated economically advantageously. Further, according to the present invention, it is possible to provide a wastewater treatment device using a carrier having a deodorizing ability, and it is preferably used for treating organic wastewater accompanied by odor. The wastewater treatment equipment of the present invention,
Since it is extremely compact and durable and can treat wastewater with high quality, it is particularly suitable for use as a combined septic tank.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a wastewater treatment apparatus of the present invention.

FIG. 2 is a flow chart showing an example in which the wastewater treatment tank of the wastewater treatment apparatus of the present invention is arranged in this order from the wastewater introduction side to a denitrification tank and a nitrification tank.

FIG. 3 is a flow diagram showing an example in which the wastewater treatment tanks of the wastewater treatment apparatus of the present invention are arranged in this order from the wastewater introduction side to a denitrification tank and a nitrification tank, and an anaerobic filter or a first settling tank is provided in front of the denitrification tank. It is a chart.

FIG. 4 is a flow chart showing an example in which the wastewater treatment tanks of the wastewater treatment apparatus of the present invention are arranged in this order from the wastewater introduction side to a nitrification tank and a denitrification tank.

FIG. 5 is an example in which the wastewater treatment device of the present invention is used as a small combined septic tank.

FIG. 6 is a flowchart showing another example of the wastewater treatment equipment of the present invention.

FIG. 7 is a flow chart showing an example in which the wastewater treatment tank of the wastewater treatment apparatus of the present invention is arranged in this order from the wastewater introduction side to a denitrification tank and a nitrification tank.

FIG. 8 is a flow diagram showing an example in which the wastewater treatment tanks of the wastewater treatment apparatus of the present invention are arranged in this order from the wastewater introduction side to a denitrification tank and a nitrification tank, and an anaerobic filter or a first settling tank is provided in front of the denitrification tank. It is a chart.

FIG. 9 is a flow chart showing an example in which the wastewater treatment tank of the wastewater treatment apparatus of the present invention is arranged in this order from the wastewater introduction side to a nitrification tank and a denitrification tank.

FIG. 10 is another example in which the wastewater treatment device of the present invention is used as a small combined septic tank.

FIG. 11 is another example in which the wastewater treatment device of the present invention is used as a small combined septic tank.

FIG. 12 is a flowchart showing a conventional organic wastewater treatment device.

[Explanation of symbols]

1 drainage 2 Wastewater treatment tank 3 Microorganism immobilization carrier 4 Air diffuser 5 blowers 6 screen 7 pumps 8 membrane module 9 Non-permeate water return line 10 treated water 11 denitrification tank 12 Denitrifying bacterium immobilization carrier 13 baffle 14 Stirrer 15 Nitrifying bacteria immobilization carrier 16 Nitrification tank 17 Non-permeate water return line 18 Nitrification treated water return line 19 Anaerobic filter 20 First settling tank 21 Nitrification treated water return line 22 Non-permeate water return line 23 Acetalized PVA hydrogel 24 Final settling tank 25 Sludge discharge pipe 26 Clear water 27 Denitrification treated water 28 Nitrification treated water 29 Nitrification treated water return line 30 Nitrification treated water 31 Denitrification treated water 32 Anaerobic tank 33 aerobic tank 34 Settling tank

─────────────────────────────────────────────────── ─── Continuation of front page (31) Priority claim number Japanese Patent Application No. 9-141305 (32) Priority date May 30, 1997 (May 30, 1997) (33) Priority claim country Japan (JP) (72) Inventor Hiroaki Fujii 1-2-1, Kaigan-dori, Okayama City, Okayama Prefecture Kuraray Co., Ltd. (72) Inventor Nao Nakagawa 1 2045 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd. (72) Inventor Shinji Komori 3-8-2 Nihonbashi, Chuo-ku, Tokyo Inside Kuraray Co., Ltd. (72) Inventor Yuio Shiotani 1-1239 Umeda, Kita-ku, Osaka City Kuraray Co., Ltd. (72) Inventor Masanobu Abe Okayama 1-2-1 Kaigan-dori, Okayama, Japan (56) References Japanese Patent Laid-Open No. 3-275197 (JP, A) Japanese Patent Laid-Open No. 4-48995 (JP, A) Japanese Patent Laid-Open No. 7-41516 ( JP, A) JP 7-68287 (JP, A) Flat 2-86700 (JP, U) Japanese Patent 6-45035 (JP, B2) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C02F 3/00 C02F 3/02-3/10 C02F 3 / 34 101

Claims (12)

(57) [Claims] 1. A waste water treatment tank for at least introducing carrier particles on which microorganisms are immobilized to decompose and remove organic matter and / or inorganic matter in waste water, and a membrane module for filtering treated water flowing out from the treatment tank. In wastewater treatment equipment,
A wastewater treatment device configured to return and circulate non-permeated water that has not passed through the membrane module to the treatment tank. 2. A denitrification tank in which carrier particles having denitrifying bacteria immobilized therein are introduced into the wastewater treatment tank for contact with wastewater under anaerobic conditions, and carrier particles having nitrifying bacteria immobilized therein are introduced into the wastewater treatment tank under aerobic conditions. A nitrification tank that is brought into contact with wastewater below, and these wastewater treatment tanks are arranged in this order from the wastewater introduction side, and the nitrification-treated water flowing out from the nitrification tank is supplied to the membrane module and Part of the water is returned to the denitrification tank and circulated, and the non-permeated water that has not permeated the membrane module is converted into a nitrification tank and / or
Alternatively, the wastewater treatment device according to claim 1, which is configured to be returned and circulated to a denitrification tank. 3. A first settling tank or an anaerobic filtration device for performing anaerobic treatment is provided in front of the denitrification tank, and the nitrification-treated water flowing out from the nitrification tank is supplied to the membrane module, and one of the treated water is discharged. 3. The wastewater treatment system according to claim 2, wherein the part is returned and circulated to the denitrification tank, the first settling tank or the anaerobic filtration device, and the non-permeated water that has not permeated the membrane module is returned and circulated to the nitrification tank. apparatus. 4. The effluent treatment tank, into which nitrifying bacteria-immobilized carrier particles are introduced into contact with wastewater under aerobic conditions, and denitrifying bacteria-immobilized carrier particles are introduced into anaerobic conditions. The denitrification tanks to be brought into contact with the wastewater below, and these wastewater treatment tanks are arranged in this order from the introduction side of the wastewater, and the denitrification treated water flowing out of the denitrification tanks is supplied to the membrane module and -The wastewater treatment device according to claim 1, which is configured to return and circulate the non-permeated water that has not permeated through the degassing tank to the denitrification tank and / or the nitrification tank. 5. The wastewater treatment equipment according to claim 1, wherein the wastewater treatment equipment is a combined septic tank. 6. The wastewater treatment device according to claim 1, wherein the carrier on which the microorganisms are immobilized is a polyvinyl alcohol-based hydrogel. 7. The wastewater treatment equipment according to claim 1, wherein the carrier on which the microorganisms are immobilized is an acetalized polyvinyl alcohol hydrogel. 8. The wastewater treatment apparatus according to claim 1, wherein the carrier on which the microorganisms are immobilized is a polyvinyl formal hydrogel. 9. A carrier on which microorganisms are immobilized has a diameter of 0.1 to 10.
The waste water treatment apparatus according to claim 1, which is a polyvinyl alcohol-based hydrogel having a surface layer of a network structure formed by intertwining fibrous substances of 50 μm. 10. The wastewater treatment equipment according to claim 1, wherein the carrier on which microorganisms are immobilized is a carrier containing activated carbon on the surface and / or inside. 11. The wastewater treatment equipment according to claim 1, wherein the membrane used in the membrane module is a microfiltration membrane or an ultrafiltration membrane. 12. The wastewater treatment equipment according to claim 1, wherein the membrane used in the membrane module is a hydrophilic membrane or a hydrophilized membrane.