JPH1142497A - Waste water treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact waste water treating device excellent in durability, having a high capacity and capable of being operated for a long period. SOLUTION: This waste water treating device has a water treating tank 2 charged with a microorganism immobilizing carrier 3, decomposing and removing the org. matter and/or inorg. matter in the waste water and a membrane module 8 for filtering the treated water discharged from the treating tank 2. The water which has not been permeated through the module 8 is returned to the treating tank 2 and circulated. In the waste water treating device consisting of the waste water treating tank 2, an acetalized PVA-base hydrogel is used as the carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus for efficiently treating wastewater containing organic substances and / or inorganic substances. More specifically, at least a compact wastewater treatment apparatus comprising a wastewater treatment tank comprising a denitrification tank and / or a nitrification tank into which carrier particles having microorganisms immobilized and a membrane module, and at least a wastewater treatment apparatus comprising: A wastewater treatment apparatus comprising a wastewater treatment tank for decomposing and removing organic substances and / or inorganic substances, wherein a compact wastewater treatment apparatus in which a carrier in which microorganisms are immobilized in an acetalized polyvinyl alcohol-based hydrogel is charged into the wastewater treatment tank. About.

[0002]

2. Description of the Related Art Conventionally, organic wastewater containing nitrogen compounds, such as rural settlement wastewater, household wastewater, urban wastewater, fish culture wastewater and various industrial wastewater, generally uses aerobic microorganisms and anaerobic microorganisms. It has been treated by an activated sludge method for purifying pollutants. For example, as shown in FIG. 12, the wastewater 1 flows into the anaerobic tank 32, and then flows into the aerobic tank 33 under aerobic conditions.
Oxidation of OD components and nitrification of nitrogen compounds by nitrifying bacteria are performed, and a part of the treated water flowing out of the aerobic tank 33 is removed from the anaerobic tank 32.
Circulates and denitrification using denitrifying bacteria under anaerobic conditions,
The effluent from the remaining aerobic tank sedimented and separated sludge in the sedimentation tank 34, and then discharged the supernatant water 26.

[0003] In the case of the conventional activated sludge method, the residence time of the wastewater in the aeration tank is designed to be 6 to 8 hours. However, recently, the amount of the wastewater is increasing with the diversification of industry and life. In addition, if a large amount of wastewater is to be treated by the activated sludge method using an existing treatment tank, the residence time will be short, and abnormalities such as bulking will occur, making satisfactory treatment impossible. Therefore, a new device is required to cope with a large amount of wastewater treatment, which requires vast land and huge construction costs.

On the other hand, from the viewpoint of nitrogen removal, conventional nitrogen removal involves introducing water to be treated into a denitrification tank and a nitrification tank in this order.
Part of the nitrification treatment water flowing out of the nitrification tank is returned to the denitrification tank.
While circulating, the remaining nitrification treated water is sent to the final sedimentation tank for treatment, or introduced in the order of nitrification tank, denitrification tank,
It is performed by a method in which the entire amount of denitrification treatment water flowing out of the denitrification tank is sent to a final sedimentation basin for treatment. At this time, Kjeldahl nitrogen is oxidized to nitrite nitrogen or nitrate nitrogen in the nitrification tank, and nitrite nitrogen or nitrate nitrogen is converted to nitrogen gas and removed in the denitrification tank.In these methods, Generally, nitrogen is removed by nitrification and denitrification using activated sludge.

[0005] Even when the wastewater is treated by such a nitrogen removal method, the total residence time in the nitrification tank and the denitrification tank is required to be 12 to 24 hours based on the inflow water, and the residence time is designed to be about 6 to 8 hours. In existing sewage treatment plants only for the purpose of removing BOD, the residence time is insufficient, and satisfactory nitrogen removal cannot be achieved. To cope with a large amount of wastewater treatment, as described above, a new treatment device is required, which requires vast land and huge construction costs.

On the other hand, in order to increase the concentration of microorganisms in the wastewater treatment tank and increase the residence time of the microorganisms, the treatment is carried out using a microorganism carrier in order to shorten the treatment time and to stabilize and enhance the treatment. Methods and equipment have been developed. As such an example, Japanese Patent Publication No. 59-16516 discloses a fluidized-bed biological treatment method and apparatus in which microorganisms are attached to a granular carrier and organic substances in wastewater are removed by flowing the carrier. Yes, JP-B 63-52556
Japanese Patent Laid-Open Publication No. H11-163873 discloses a method of biologically treating wastewater by filling a carrier in which activated sludge is entrapped and fixed in a polymer carrier into a wastewater treatment tank and contacting the carrier under aerobic conditions.

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

In recent years, studies have been made to reduce the size of a wastewater treatment apparatus by filling a treatment tank with a carrier to which microorganisms adhere and grow, and as a carrier, various granular materials such as ceramics and plastics and a honeycomb-shaped structure have been proposed. The body is being developed. The carrier used for wastewater treatment is required to have a high water content, excellent oxygen and substrate permeability, high affinity with living organisms, etc., and from such a viewpoint, for example, polyvinyl alcohol (Hereinafter, polyvinyl alcohol is abbreviated as PVA) into a mold, followed by freezing partial dehydration (JP-A-58-36630).
), A method in which a PVA aqueous solution is brought into contact with a saturated boric acid aqueous solution to form a gel (Sewer Association of Japan, Vol. 23 (198)).
6) p41; irrigation and wastewater, Vol. 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 form a spheroid, followed by freezing and thawing (JP-A-64-43188), and a method of acetalizing with formaldehyde (JP-A-Hei 7).
No. 41516) is known.

On the other hand, with the advance of membrane separation technology, the use of separation membranes for the purpose of improving the quality of treated water is increasing. One example is JP-B 64-5960.
Japanese Patent Application Publication No. JP-A-64-9071 discloses a wastewater treatment apparatus for filtering a hollow fiber membrane module by communicating the hollow fiber membrane module with the bottom surface of a treatment tank. There is disclosed a wastewater treatment device that is disposed above a tank and performs a filtration treatment.

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

However, in each of these cases, 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. However, since the hole in the hole is closed, the flow rate of the drainage water cannot be increased so much, and there is a limit in reducing the size of the apparatus. In addition, due to the synergistic effect of the adhesion of the settled sludge to the membrane surface,
The film was easily cracked or broken.

[0012] On the other hand, an apparatus in which a treated water is circulated and a membrane module is provided outside the treatment tank is also disclosed. For example, Japanese Patent Publication No. 6-45035 discloses a waste liquid and a denitrifying bacterium. Treatment with the used bioreactor (I) followed by B
Bioreactor using OD oxidizing bacteria and nitrifying bacteria (II)
, And the treated liquid is introduced into a membrane separation device, and the non-permeated liquid that has not passed through the membrane is removed from the bioreactor (I).
In I), the permeated liquid permeated through the membrane is added to the bioreactor (I).
Discloses a wastewater treatment method circulating respectively.

Japanese Patent Application Laid-Open No. 4-200697 discloses a circulating biological treatment apparatus comprising an air-lift type fluid tank and an inflatable type fluid tank for treating granular microbial carriers by flowing them, an ultrafiltration membrane apparatus, and the like. And an organic wastewater treatment apparatus for injecting a part or all of the circulating water of an ultrafiltration membrane device from the bottom of an inflatable fluidized tank is disclosed.

However, according to the method disclosed in Japanese Patent Publication No. 6-45035, although the membrane module is installed outside the treatment tank, the concentration of suspended activated sludge containing nitrifying bacteria is high, and the membrane module is still used. There is a disadvantage that clogging is easily caused. Further, in the treatment apparatus disclosed in Japanese Patent Application Laid-Open No. 4-200697, a part or all of the circulating water of the ultrafiltration apparatus is injected from the bottom of the expansion type fluidized tank (denitrification tank), but the microorganism carrier overflows. Since the flow rate is restricted so as not to cause the problem, there is a disadvantage that the fluidity of the carrier is insufficient and the denitrification performance is lowered. In addition, when the circulation amount of the liquid is large, the concentration of dissolved oxygen in the tank increases, and the denitrification performance decreases.

[0015]

Any of the wastewater treatment apparatuses using the above-mentioned membranes contributes to the downsizing of the apparatus to some extent, but this type of apparatus is typified by a combined septic tank. In addition, there has been a demand for an extremely compact, highly durable one capable of improving the quality of treated water, and no wastewater treatment apparatus satisfying this point has been found yet.

[0016] Further, in wastewater treatment, bad odor is often generated, and it is pointed out as a new environmental problem. A conventional wastewater treatment method using a carrier has a wastewater treatment ability but cannot remove odors. Therefore, it is necessary to take measures such as providing a separate odor treatment device. Therefore, from the viewpoint of bad smell, there is a demand for an economically advantageous carrier that does not increase the size of the apparatus. Therefore, an object of the present invention is to provide a wastewater treatment apparatus that is compact, has excellent durability, has a high treatment capacity, and has a long membrane life. It is another object of the present invention to provide a wastewater treatment apparatus that is compact, has excellent durability, and has a high treatment capacity. Another object of the present invention is to provide a wastewater treatment apparatus that is compact, has excellent durability, has a high treatment capacity, and is applicable to wastewater that emits offensive odor.

[0017]

Means for Solving the Problems The present inventors have made intensive studies and have at least studied a wastewater treatment tank into which carrier particles having microorganisms immobilized are introduced, and a membrane module for filtering treated water flowing out of the treatment tank. The non-permeated water that has not passed through the membrane module is returned to the treatment tank
Using a wastewater treatment device configured to circulate, or at least a wastewater treatment device into which an acetalized PVA-based hydrogel immobilized with microorganisms is charged, and using a microorganism-immobilized carrier containing activated carbon As a result, the above-mentioned problems have been solved, and the present invention has been accomplished.

That is, the present invention provides a wastewater treatment tank for introducing at least carrier particles having microorganisms immobilized thereon and decomposing and removing organic and / or inorganic substances in wastewater, and a membrane for filtering treated water flowing out of the treatment tank. A wastewater treatment apparatus having a module, wherein non-permeated water that has not passed through the membrane module is returned and circulated to the treatment tank.

According to another aspect of the present invention, at least
In a wastewater treatment apparatus comprising a wastewater treatment tank into which carrier particles on which microorganisms are immobilized are injected and organic and / or inorganic substances in the wastewater are decomposed and removed, the carrier on which microorganisms are immobilized is an acetalized PVA-based hydrogel. It is a wastewater treatment device characterized by the above-mentioned.

Another aspect of the present invention is a wastewater treatment apparatus in which a carrier on which microorganisms are immobilized contains activated carbon on its surface and / or inside.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The waste water treatment apparatus of the present invention will be described more specifically with reference to the drawings. FIG. 1 is a flowchart showing an example of a wastewater treatment apparatus according to the present invention. The wastewater treatment tank contains carrier particles immobilized with microorganisms for decomposing and removing organic substances and / or inorganic substances in wastewater. Consists of a membrane module. The wastewater treatment tank is a denitrification tank in which carrier particles with immobilized denitrifying bacteria are charged and brought into contact with the wastewater under anaerobic conditions, and / or a carrier particle with immobilized nitrifying bacteria is charged and discharged under aerobic conditions. It is a nitrification tank to be brought into contact.

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

FIG. 2 shows that the treatment tank is preferably charged with carrier particles on which denitrifying bacteria are immobilized and brought into contact with wastewater under anaerobic conditions, and carrier particles on which nitrifying bacteria are immobilized. A nitrification tank 16 which is brought into contact with wastewater under pneumatic conditions, these treatment tanks are arranged in this order from the wastewater introduction side, and nitrification treatment water flowing out of the nitrification tank is supplied to the membrane module 8. A flowchart 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 passed through the membrane module is returned and circulated to the nitrification tank and / or the denitrification tank. It is.

In the waste water treatment apparatus shown in FIG. 2, waste water 1 containing organic substances and / or inorganic substances flows into a denitrification tank 11. In the denitrification tank 11, carrier particles 12 immobilized with denitrification bacteria
And the wastewater is treated under anaerobic conditions. The denitrification tank is preferably provided with a baffle plate 13 in order to prevent carrier particles and sludge from flowing out, 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 stirrer 14 provided at the bottom of the denitrification tank 11, so that a sufficient flow of the carrier is ensured and the flow of the liquid more than necessary is required. Since there is no such time, 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. Reference numeral 15 denotes carrier particles on which nitrifying bacteria are immobilized. As described above, it is preferable to provide a screen in each tank in order to prevent the carrier particles from flowing out. The nitrification treatment water flowing out of 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, a 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, wastewater can be efficiently treated by returning a part of the water to the denitrification tank and performing the denitrification treatment. It is convenient to use an air lift pump (not shown) to return the nitrified water to the denitrification tank. In this case, if the nitrification treatment 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 return of 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 carried out at about 1 to 5 times the permeated water of the membrane module. The ratio of non-permeated water to permeated water cannot be unconditionally determined because it depends on the properties of the membrane, but is usually about 5 to 10 times.
The rate of returning the non-permeated water to the denitrification tank and the nitrification tank is appropriately performed according to the properties of the wastewater, and may be, for example, equal. Hereinafter, these return rates are the same in the wastewater treatment apparatus of the present invention using a membrane module. The treated water that has passed through the membrane is subjected to further treatment, such as disinfection, if necessary, and treated water 1
Released as 0.

In the wastewater treatment apparatus of the present invention, it is more effective to provide an anaerobic filter or an initial settling tank for performing anaerobic treatment before the denitrification tank. FIG. 3 shows an example in which an anaerobic filter 19 or a first settling tank 20 is provided before the denitrification tank. Since the nitrification water contains nitrate nitrogen, a part of the liquid is returned to the anaerobic filter so as not to load the membrane module, and the anaerobic filtration and the denitrification are performed. In this case, it is desirable to install the membrane module outside the nitrification tank because the membrane life tends to be extended. The nitrification-treated water is returned to the denitrification tank 11 or the anaerobic filter 19 or the first settling tank 20 by the return line 21, and the non-permeated water that has not passed through 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 extracted, and a more compact apparatus can be obtained. According to such an apparatus, excess sludge is reduced to a fraction of that in the case of the ordinary activated sludge method, so that the sludge load on the membrane module is reduced.
The advantage of placing the membrane module outside can be fully utilized, and the life of the membrane can be extended. Normally, the rate of return from the nitrification tank to the anaerobic filtration device can be appropriately changed depending on the properties of the wastewater. However, it is usually 1 to 5 times the permeate in the membrane module, and is not permeated in the membrane module. The rate of returning the liquid to the nitrification tank is about 1 to 10 times that of the permeate.

In the anaerobic filtration device 19, suspended matter and the like in the wastewater are removed. However, since anaerobic bacteria adhere to the filtration material, anaerobic treatment is also performed simultaneously in the anaerobic filtration device. In addition, since a part of the nitrification treatment water is circulated, it plays a part in the denitrification step, and the capacity of the denitrification tank is smaller than when the nitrification treatment water is circulated to the denitrification tank. The filtration material used in the anaerobic filtration device is not particularly limited as long as the above-mentioned suspended matter can be removed, and for example, fibers, plastics, and molded products thereof are used. It is preferable that these filter media have a small pressure loss and increase the adhesion of microorganisms, and it is preferable to use a filter material molded in a lattice shape.

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

FIG. 4 shows an example in which the wastewater treatment tanks are a nitrification tank and a denitrification tank, and are arranged in this order from the wastewater introduction side. In this case, it is necessary to replenish the denitrification tank with an organic carbon source for the growth of the denitrifying bacteria. In recent years, merger treatment for simultaneously treating human waste and household wastewater has been spreading, but not only the treatment of BOD components but also the removal of nitrogen components as a measure for eutrophication of water bodies has become a major issue. The wastewater treatment apparatus of the present invention solves such a problem, and requires a small installation space, so that 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 a membrane module is provided outside a nitrification tank and nitrification-treated water is press-fitted into the membrane module by a pump. However, it is a matter of course that the filtration may be performed by suction filtration or gravity filtration. The illustration of the blower for diffusing air into the nitrification tank is omitted.

A carrier in 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-based resins, acrylic resins, acrylamide-based resins, olefin-based resins,
Styrene-based resins, polyurethane-based resins, polysaccharides, polyethers, porous inorganic compounds, and the like. Specific examples include PVA-based, polyethylene glycol-based, polyacrylamide-based, calcium alginate, carrageenan, Examples thereof include agar, a polymer gel such as a photocurable resin, activated carbon, a polyurethane sponge, polyacrylonitrile, polyethylene, polypropylene, polystyrene, a cellulose derivative, and polyester.

As a carrier, when bacteria are adhered, BO
D Hydrogel with high molecular weight is preferable in terms of D removing ability, nitrification ability and denitrification ability. When using hydrous gel, the hydrous gel flows in the treatment tank and comes into contact with the membrane surface to clean the membrane surface. The effect is great. Above all, the PVA-based hydrogel has a network structure on the surface and inside of the carrier, so that microorganisms can easily inhabit, and is excellent in capturing organic compounds, and is also excellent in mechanical strength. preferable. In addition, the higher the average degree of polymerization and / or degree of saponification of PVA, the lower the concentration of PVA.
The water content of the gel can be increased, and therefore, the habitability of microorganisms is improved, which is preferable. From this point, the average degree of polymerization of PVA is preferably 1,000 or more,
More than 500 are more preferred. Further, the degree of saponification of PVA is preferably 95 mol% or more, especially 98%.
Those having mol% or more are more preferable.

The concentration of PVA is preferably higher from the viewpoint of the strength of the carrier, and is preferably lower from the viewpoint of microbial habitat. Therefore, the concentration is preferably 1 wt% to 40 wt%, and more preferably 3 wt% to 2 wt%.
0 wt% is more preferable.

In order to prevent the elution and deterioration of PVA, P
It is desirable that VA is acetalized. Examples of the acetalizing agent include formalin, glutaraldehyde, glyoxal, terephthalaldehyde, ω, ω'-nonandial, and the like. Polyvinyl former
Is a preferred example of such an 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 inhabitation of microorganisms will deteriorate, so it is preferably from 10 to 60 mol%, more preferably from 20 to 55 mol%.

Examples of the acid for acetalization include acids such as sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, acetic acid and oxalic acid;
Acid salts such as sodium hydrogen sulfate and ammonium hydrogen sulfate are used.However, in the presence of an aldehyde compound or acid, the hydrogel may be excessively swollen or dissolved, so As its inhibitor, PVA
You may add sodium sulfate etc. which have the syneresis effect of.

As long as the acetalization of PVA is not inhibited, molding aids such as sodium alginate, carrageenan, boric acid, and two or more kinds of carbonate ions, hydrogen carbonate ions, sulfate ions, phosphate ions, etc. A monovalent or polyvalent anion for phase separation of the polymer may be added.
The acetalized PVA-based gel is suitable for microorganisms because it has an uneven structure on the surface and has finger-shaped communication holes from the surface to the center.

The acetalized PVA-based hydrogel used in the present invention has a hydroxyl group in the molecule and thus exhibits hydrophilicity and high microbial habitability. The acetalized PVA-based hydrogel is used in a wastewater treatment tank for treating organic wastewater under aerobic conditions, a denitrification tank for biologically denitrifying under anaerobic conditions, and / or a biological treatment under aerobic conditions. By being charged into a nitrification tank that performs chemical nitrification, microorganisms present in the water to be treated are effectively attached to and bound to the outer surface and the inside of the carrier. The specific gravity of the acetalized PVA-based hydrogel becomes 1.00 to 1.05 when the adhesion and immobilization of microorganisms reach a steady state in the tank, so that the gel can flow uniformly in the tank, It is preferable also from the point of.

The acetalized PVA gel-like carrier is separated from the acetalized solution, and subjected to treatment 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 it is 50 to 99% on a wet weight basis, and more preferable is 60 to 9%.
8%. The method of measuring the moisture content on a wet weight basis is as follows: a carrier is immersed in water at 25 ° C. for 24 hours or more, and then the weight of the carrier excluding water adhering to the surface is measured (wet weight).
After drying for 4 hours, the weight is measured (dry weight). The moisture content based on wet weight is (wet weight−dry weight) / wet weight × 100
(%).

The most preferred hydrogel is the one which has been filed by the applicant as Japanese Patent Application No. 9-11057 and has at least 10 concave portions having an average diameter of 10 to 100 μm and a depth of 10 to 100 μm per 1 mm of the surface. An acetalized PVA-based hydrogel having a water content of 50% by weight or more.
No. 7, filed as a surface layer with a network structure formed by entanglement of fibrous materials having a diameter of 0.1 to 50 μm.
It is an A-type hydrogel. The method of producing this hydrogel is as follows:
As described in detail in the above specification, for example, PVA8w having an average degree of polymerization of 1700 and a degree of saponification of 99.8 mol% is given as an example.
t%, 1 wt% of sodium alginate and 0.3 wt% of sodium hydrogen carbonate are prepared, and the aqueous solution is dropped into a 0.1 mol / L calcium chloride aqueous solution to obtain a spherical molded product. It can be obtained by dipping in an aqueous solution for acetalization containing 20 g / l of formaldehyde, 200 g / l of sulfuric acid, and 100 g / l of sodium sulfate, followed by washing with water.

The shape of the carrier is not particularly limited, and a carrier formed into an arbitrary shape such as a fiber, a die, a film, a column, a hollow cylinder, a sphere, and a disk can be used. From the viewpoint of the fluidity of the carrier, those having a spherical shape are preferred.

Activated carbon is excellent in the ability to remove and deodorize organic substances that are inherently possessed by adsorption and deodorization, as well as the ability to remove BOD, denitrification, and nitrification by microorganisms attached to activated carbon. Preferred carriers. When activated carbon is used as a carrier, the microorganisms decompose and remove the organic matter to which the activated carbon has been adsorbed, whereby biological regeneration of the activated carbon is performed, the adsorption capacity can be maintained for a long time, and the load of the SS component is reduced. Further, activated carbon has good durability and mechanical wear resistance. When using floating activated carbon,
The effect of cleaning the surface of the film is great. However, activated carbon has poor fluidity compared to other hydrogels and is easily damaged by rapid flow. Therefore, in order to sufficiently bring out the performance of activated carbon, it is preferable to use the activated carbon fixed to a wastewater treatment tank. The carrier may include activated carbon as a part of the carrier.

As activated carbon, charcoal, coal, coke,
It is manufactured using coconut husk, resin, petroleum pitch, etc. as raw materials. These raw materials, such as wood, coal, resin, and pitch, can be converted into gas, steam, and chemical. Those activated by such a method are preferable. As an activation method, a method of activating with zinc chloride or phosphoric acid is effective and preferable.

The quality of the activated carbon is between 0.10 and 0.1.
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, wood-based ones are preferable because they have a network structure on the surface and inside of the carrier, so that microorganisms can be easily attached thereto and are excellent in capturing organic compounds and odorous components. Activated carbon is easily broken when it flows, and it is preferable to use it in the form of a fixed bed or the like in order to sufficiently bring out the function of the activated carbon.

[0045] Wastewater often produces a bad smell. In such a case, it is preferable to use a carrier containing activated carbon. To produce such a carrier, for example, PV
A mixed aqueous suspension of a carrier 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 usually from 1 to 40 w
t%, molding aid 0.1-5 wt% and activated carbon 0.1-5
It is performed in wt%. When this aqueous suspension is dropped from a nozzle into an aqueous solution of calcium chloride, a spherical gel can be obtained.

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 of activated carbon in the carrier is too small, the deodorizing effect is small, so that the content is preferably 0.5 to 5 wt%. When the PVA-based gel is an acetalized PVA-based gel, since the surface has an uneven structure and has a communicating hole from the surface to the center, not only the effect of activated carbon on the surface but also the effect of activated carbon inside is effective. This is preferable because it can be extracted to

The quality of the activated carbon contained in the carrier raw material is 0.10 to 0.70 g / cm ³ , preferably 0.1 to 0.70 g / cm ³ .
15 to 0.60 g / cm ³ , specific surface area 300 to 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, wood-based ones are preferable because they have a network structure on the surface and inside of the carrier, so that microorganisms can be easily attached thereto and are excellent in capturing organic compounds and odorous components.

As the shape of the activated carbon, various shapes such as a granular shape, a powdery shape, and a fibrous shape can be used, but a powdery shape is preferable in order to make the activated carbon uniformly exist in the carrier. As an example of activated carbon, Kuraray Chemical Co., Ltd. product name Kuraray Kol, Toyo Calgon Co., Ltd. product 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. Good. For example, a case using a hydrogel 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, using activated carbon for the denitrification tank, and using a hydrogel for the nitrification tank There are various cases such as a case using a hydrogel in a denitrification tank and a case using activated carbon in a nitrification tank, and the case can be appropriately implemented as desired. The denitrifying bacteria and the nitrifying bacteria may be used by being immobilized on carrier particles in advance. Alternatively, the carrier particles may be charged into a tank and the bacteria may be naturally attached.

The material of the separation membrane used in the membrane module may be durable, for example, polysulfone-based, polyacrylonitrile-based, polyolefin-based, cellulose-based, and the like.
Examples of the resin include polyamide-based, polyester-based, polyvinyl alcohol-based, poly (meth) acrylate-based, and polyimide-based resins. It is preferable to use a microfiltration membrane or an ultrafiltration membrane from the viewpoint of separation performance.

When a hydrophilic film or a hydrophilicized film is used for the membrane module, the SS component hardly adheres to the film,
Even if the component adheres, it is preferable because it is easily peeled off by backwashing with air or a permeate. Vinyl alcohol resins such as polyvinyl alcohol are preferred examples of the hydrophilic film. In addition, hydrophobic resins such as polysulfone and polyolefin resins may be replaced with vinyl alcohol such as polyvinyl alcohol.
You may use the film | membrane hydrophilized with the toluene-type resin etc. Of course, a vinyl alcohol-based resin may be used after being acetalized.

These membranes may be of any shape such as a hollow fiber or a flat membrane, but it is preferable to use a hollow fiber shape in terms of handleability and compactness. Those having a thickness of about 2500 m are preferably used. The required number of hollow fiber membrane modules is used in series or in parallel according to the processing amount.

The membrane module may be used immersed in the nitrification tank or may be installed outside the nitrification tank. When the membrane module is used by immersing it in a nitrification tank, the nitrification-treated water is usually carried out by suction filtration or gravity filtration. When the membrane module is installed outside the nitrification tank and used, the nitrification treatment water may be injected by a pump, or may be performed by suction filtration or gravity filtration. FIG. 1 shows that the membrane module is provided outside the nitrification tank,
This is an example in which nitrification-treated water is injected by a pump. When a hollow fiber membrane module is used as the membrane module, an internal pressure filtration method in which treated water passes through the inside of the hollow fiber or an external pressure filtration method in which treated water passes through the outside of the hollow fiber may be used. Is preferred because clogging of the film can be reduced.

FIG. 6 shows a waste water treatment apparatus according to the present invention, which comprises at least carrier particles having microorganisms immobilized thereon and decomposing and removing organic and / or inorganic substances in the waste water. It is an example of a wastewater treatment apparatus using a carrier obtained by immobilizing microorganisms on an acetalized PVA-based hydrogel, and is a flowchart in the case of decomposing and removing organic substances in wastewater under aerobic conditions. 2 is a wastewater treatment tank and 24 is a final sedimentation tank. First, waste water 1 is supplied to a waste water treatment tank 2 from a first sedimentation tank (not shown). The wastewater treatment tank 2 contains the acetalized PV
A hydrogel 23 is charged and fluidized by the air diffuser 4 provided at the bottom of the wastewater treatment tank 2. Reference numeral 5 denotes a blower connected to the diffuser 4, which is a driving unit for the diffuser 4. The wastewater is biologically treated in a wastewater treatment tank 2.

When air is blown out from the air diffuser 4 while introducing the wastewater 1 into the wastewater treatment tank 2, oxygen is supplied to the mixed solution in the wastewater treatment tank 2 and the rising bubble flow at this time causes A circulating flow is generated in the processing tank. With this circulating flow,
In the process of the acetalized PVA hydrogel 23 flowing in the wastewater treatment tank 2, microorganisms that decompose and remove organic substances are attached to and bound to the hydrogel 23. Therefore, as a result of sufficient contact between the microorganisms and the organic matter, the organic matter in the mixture is
Decomposed and removed very efficiently and at high speed. In addition, the microorganisms immobilized inside the carrier are less likely to be exfoliated when the acetalized PVA hydrogel 23 flows in the mixed solution.
Various screens or the like may be appropriately provided in the treatment tank in order to prevent the acetalized PVA-based hydrogel from overflowing.

The biologically treated water is sent to the final sedimentation 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 increase the efficiency of wastewater treatment by using an acetalized PVA-based hydrogel. The use of gel can dramatically increase the wastewater treatment effect.

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

A stirring device 14 is provided in the denitrification tank 11, and a spherical acetalized PVA hydrogel 23 is charged into a 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 the blower 5. The same spherical acetalized PVA hydrogel 23 used in the denitrification tank is charged. Acetalization P
The VA-based hydrogel may be charged into both the denitrification tank and the nitrification tank and used, or may be charged into one or the other, but it is more efficient to charge both. Usually, it is used by charging both tanks. Different types of acetalized PVA may be charged into each tank.

In this apparatus, the waste water 1
When the stirrer 14 is operated in a state where the denitrification treatment water 27 is allowed to flow into the nitrification tank 16 while introducing the mixed gas, a circulating flow of the mixed liquid is generated in the denitrification tank 11, and the circulating flow causes acetalization P
The VA hydrogel 23 flows in the denitrification tank 11, during which the microorganisms mainly composed of denitrifying bacteria present in the mixed solution adhere to and are immobilized on the hydrogel 23. The mixed solution in the tank is denitrified by the immobilized denitrifying bacteria and floating denitrifying bacteria. The organic matter in the mixed solution is used as a respiratory substrate for denitrifying bacteria or a carbon source for cell synthesis. However, as described above, a carbon source may be added from outside the system as needed.

In the nitrification tank 16, when the denitrification water 27 is supplied from the denitrification tank 11, and the nitrification water 28 in the nitrification tank 16 flows out, air is blown out from the air diffuser 4. While oxygen is supplied to the mixed liquid of the above, and the circulating flow of the mixed liquid is generated by the rising bubble flow at this time, microorganisms mainly composed of nitrifying bacteria present in the mixed liquid adhere to the acetalized PVA hydrogel 23.・ It is bonded and fixed. The liquid mixture in the tank is biologically nitrified by the immobilized nitrifying bacteria and the suspended nitrifying bacteria.

As a result, microorganisms adhere and bind to and immobilize on the surface and / or inside of the acetalized PVA hydrogel 23, so that the components to be treated and the microorganisms come into sufficient contact. In addition, the microorganisms immobilized inside the carrier,
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 very efficiently and at a high speed. It is a matter of course that a screen or the like may be provided in the denitrification tank and / or the nitrification tank in order to prevent the hydrogel from overflowing out of the tank.

FIG. 8 is another flowchart of the present invention in which a denitrification tank and a nitrification tank are arranged in this order from the wastewater introduction side, and an anaerobic filter or a first settling tank is provided before the denitrification tank. Drainage 1
Is biologically denitrified by microorganisms in a denitrification tank under anaerobic conditions, and then denitrified water 27 is biologically nitrified by microorganisms in a nitrification tank under aerobic conditions. A portion 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 remaining nitrification-treated water is sent to the final settling tank 24 to remove the sediment. It is discharged as supernatant water 26. The ratio of the nitrification-treated water 28 returned to the denitrification tank 11 and the anaerobic filtration device 19 or the first settling tank 20 to the supernatant water 26 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 apparatus not using the membrane module of the present invention. The generated sludge is drawn out of the system by a sludge discharge pipe 25.

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

[0065]

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

This spherical solid was converted to formaldehyde 20
By immersing in an aqueous solution containing g / l, sulfuric acid 200 g / l, and sodium sulfate 100 g / l 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.

Observation of the structure of the obtained gel shows that the surface layer has a network structure formed by entanglement of fibrous materials having a diameter of about 0.3 to 10 μm, and the thickness of the surface layer is 5% /
The gel was about the maximum diameter. Further, a dense internal layer having a pore size of about 1 to 10 μm was formed inside the gel, and the thickness of the internal layer was about 75% / the maximum gel diameter. Further, between the surface layer and the inner layer, there is formed an intermediate layer in which a number of finger-shaped voids having a hole 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 / gel maximum diameter.

Example 1 Into a 1 m ³ aerobic tank, 20% by volume of the PVA hydrogel prepared in Reference Experimental Example 1 was charged, and the inner diameter of the hollow fiber was 2 mm and the membrane area was 1
A wastewater treatment apparatus as shown in FIG. 1 was constructed by combining with a membrane module made of a polysulfone UF membrane (Kuraray 6304 membrane) having a molecular weight cut off of 1 m ² and a molecular weight of 13,000. 1m drainage of BOD 2500mg / L (L)
^The water was supplied to the aerobic tank ³ / day, and aerobic treated water was introduced into the inside of the hollow fiber membrane and filtered by a cross-flow method. The non-permeate which has not passed through the membrane module is returned to the aerobic tank at a flow rate 10 times that of the permeate which has passed through the membrane module.
After continuous treatment for months, the BOD of treated water is 200
３００300 mg / L, SS was stable at 0 mg / L.
There was almost no clogging of the membrane, and no washing operation of the membrane module was required.

[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
In combination with the same membrane module as above and arranged in this order from the wastewater introduction side, a wastewater treatment device as shown in FIG. 2 was configured. A wastewater having a BOD of 200 mg / L and a total nitrogen of 50 mg / L was supplied to the denitrification tank at 1.3 m ³ / day, nitrification-treated water was introduced into the inside of the hollow fiber membrane, and filtered by a cross flow method. Nitrified water is returned to the denitrification tank at a flow rate three times as high as the permeated water that has passed through the membrane module, and non-permeate liquid that has not passed through the module is returned to the nitrification tank at a flow rate ten times as high as the permeated water 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. Also, almost no clogging of the film was observed.

Example 3 A 0.5 m ³ primary sedimentation tank was provided in front of the denitrification tank of Example 2, and the nitrification treatment water was returned to the denitrification tank and the first sedimentation tank, as shown in FIG. A wastewater treatment device was configured. The nitrification treatment water was continuously treated for one year in the same manner as in Example 2 except that the nitrification treatment water was returned to the denitrification tank and the first sedimentation tank at a flow rate of 3 times the permeated water permeated through the membrane module at a ratio of 50:50. BOD of finished water is 2-6mg / L, SS is 0-3
mg / L. Also, almost no clogging of the film was observed.

Example 4 A waste water treatment apparatus shown in FIG. 4 was constructed by arranging a nitrification tank, a denitrification tank and a membrane module in this order from the waste water introduction side. In the nitrification tank and the denitrification tank, the same PV as used in Example 1 was used.
The A gel was charged at 20% by volume, and a wastewater with a total nitrogen of 200 mg / L was supplied to the nitrification tank at 0.4 m ³ / day. When the non-permeate which did not pass through the membrane module was returned to the nitrification tank at a flow rate 10 times that of the permeated water which passed through the membrane module and was continuously treated for one year, the total nitrogen of the treated water was 10 to 15 mg /
L and SS were stable at 0 to 3 mg / L. Also, almost no clogging of the film was observed.

Example 5 0.5 m ³ primary sedimentation tank, 0.2 m ³ denitrification tank, 0.2 m ³
A combined purification tank as shown in FIG. 5 was constructed using a nitrification tank of m ³ and the same membrane module as in Example 1. 20% by volume of the polyvinyl formalized hydrogel prepared in Reference Experimental Example 1 was introduced into the denitrification tank and the nitrification tank, and domestic wastewater of a family of five was supplied to the first settling tank at 1.3 m ³ / day. The nitrification-treated water was returned to the first settling tank and the denitrification tank at a ratio of 50:50 at a flow rate three times that of the permeated water that passed through the membrane module.
Further, the non-permeated water that did not pass through the membrane module was returned to the nitrification tank at a flow rate 10 times that of the permeated water that passed through the membrane module, and was continuously treated for one year.
Was stable at 7 to 10 mg / L, and SS was stable at 0 to 3 mg / L. Also, almost no clogging of the film was observed.

Comparative Example 1 Example 1 except that aerobic treated water was completely filtered with a membrane module.
As a result, the membrane was clogged on the eighth day, and the operation became difficult. When the operation was continued without performing the membrane washing operation, the operation was stopped because the treated water overflowed from the aerobic tank.

Example 6 20% by volume of the acetalized PVA hydrogel prepared in Reference Experimental Example 1 was charged into a 1 m ³ aerobic tank and combined with a 0.6 m ³ final sedimentation tank as shown in FIG. A wastewater treatment device was configured. The wastewater of 2500 mg / L (L) of BOD was supplied to the aerobic tank at 1 m ³ / day and continuously treated for 6 months, and the BOD of the treated water was 200 to 300 mg / L.
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 A wastewater treatment device as shown in FIG. 7 was configured in combination. BOD 200mg /
L, wastewater with a total nitrogen of 50 mg / L 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 as high as that of the supernatant water. Jesui 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 primary sedimentation tank was provided in front of the denitrification tank of Example 7, and the nitrification treatment water was returned to the denitrification tank and the first sedimentation tank, as shown in FIG. A wastewater treatment device was configured. The nitrification treatment water was continuously treated for one year in the same manner as in Example 7 except that the nitrification treatment water was returned to the denitrification tank and the first sedimentation tank at a flow rate of three times the supernatant water at a ratio of 50:50. 6
９9 mg / L, SS was stable at 6-8 mg / L.

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

Example 10 0.5 m ³ primary sedimentation tank, 0.2 m ³ aerobic tank and 0.1 m ³
A combined septic tank as shown in FIG. 10 was constructed using a final settling tank of 3 m ³ . 20% by volume of the same PVA hydrogel as used in Example 6 was introduced into the aerobic tank, and domestic wastewater of a family of five was supplied to the first settling tank at 1.3 m ³ / day. 1
After continuous treatment for a year, the BOD of treated water is 8-10
mg / L and SS were stable at 10 to 15 mg / L.

Example 11 0.5 m ³ primary sedimentation tank, 0.2 m ³ denitrification tank, 0.2 m ³
FIG using final sedimentation tank of the nitrification tank and 0.3 m ³ of m ³ 1
A combined septic tank as shown in Fig. 1 was constructed. 20% by volume of the same PVA hydrogel as used in Example 6 was put into the denitrification tank and the nitrification tank, and the household wastewater of a family of 5 was 1.3 m ³ /
In the first day, it was supplied to the settling tank. The nitrification-treated water was returned to the denitrification tank and the first settling tank at a flow rate of three times the supernatant water at a ratio of 50:50, and treated continuously for one 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 device 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 having a BOD of 200 mg / L and a total nitrogen of 50 mg / L was continuously treated at 1.3 m ³ / day. Is 90 to 120 mg / L,
The total nitrogen was 25-35 mg / L, which was an insufficient water quality.
In addition, the SS concentration of the treated water was as high as 150 to 250 mg / L, and it was necessary to extract excess sludge from the sedimentation tank every week in order to maintain this water quality.

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

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

Reference Experimental Example 3 As PVA, the average degree of polymerization was 4000 and the degree of saponification was 99.8.
Mol%, using a water suspension consisting of 8 wt% of PVA, 0.25 wt% of sodium alginate, and 1 wt% of activated carbon (P-60) manufactured by Kuraray Chemical Co., Ltd. About 5 mm of hydrogel was obtained. The carrier had an acetalization degree of 37 mol% and a water content of 92%. As a result of observing the carrier with a microscope in the same manner as in Example 1, similar communication holes were found.

Examples 12 and 13 One liter of the carrier obtained in Reference Experimental Examples 2 and 3 was placed in a 10 L aeration tank and aerated.
It was introduced continuously at L / min. Aperture 2 at outlet of aeration tank
mm was attached to prevent the carrier from flowing out. The TOC of the treated water after 10 days has passed is 8.6 ppm and 7.5 respectively.
ppm, indicating that sufficient treatment was performed. Thereafter, the carrier is taken out, placed in a 20 L closed container, and further water is added for 5 times.
L was put. Air containing 10 ppm of hydrogen sulfide was flowed at 10 L / min into the gas phase of this container, 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, and the hydrogen sulfide concentration was below the detection limit.

Reference Experimental Example 4 Acrylamide 18 wt%, methylene bisacrylamide 1 wt%, activated carbon (P-
60) NNN′N′-tetramethylethylenediamine as a polymerization initiator was added to a 1 wt% aqueous suspension.
5% by weight and 0.25% by weight of potassium persulfate were added, and the mixture was polymerized at room temperature with stirring and cast to form a 4 mm thick sheet.
A product 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 observation with a microscope, the activated carbon was dispersed almost uniformly from the vicinity of the surface of the carrier to the center, but no communication hole was observed.

Example 14 A wastewater treatment test was carried out in the same manner as in Examples 12 and 13. As a result, 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 degree of acetalization was 38 mol% and the water content was 93 in the same manner as in Reference Example 2 without using activated carbon.
% Hydrogel was obtained. The existence of the communication hole was the same as in Reference Experimental Example 2 or 3, but the same test as in Example 12 was carried out. As a result, the concentration of hydrogen sulfide was 8.7 ppm, and was hardly reduced.

[0088]

According to the present invention, it is possible to provide a wastewater treatment apparatus which is compact, has excellent durability, has high treatment capacity, and can be operated stably for a long period of time. In addition, a denitrification tank and / or
Alternatively, when a microbial carrier using an acetalized PVA gel as a carrier is used in the nitrification tank, the durability of the carrier is excellent, so that wastewater treatment can be carried out economically and 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 suitably used for treating organic wastewater with odor. The wastewater treatment device 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 the drawings]

FIG. 1 is a flowchart showing an example of a wastewater treatment apparatus according to the present invention.

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

FIG. 3 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 the order of a denitrification tank and a nitrification tank from the wastewater introduction side, 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 flowchart showing an example in which the wastewater treatment tanks of the wastewater treatment apparatus of the present invention are arranged in the order of a nitrification tank and a denitrification tank from the wastewater introduction side.

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

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

FIG. 7 is a flowchart showing an example in which the wastewater treatment tanks of the wastewater treatment apparatus of the present invention are arranged in the order of a denitrification tank and a nitrification tank from the wastewater introduction side.

FIG. 8 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 the order of a denitrification tank and a nitrification tank from the wastewater introduction side, 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 flowchart showing an example in which the wastewater treatment tanks of the wastewater treatment apparatus of the present invention are arranged in the order of a nitrification tank and a denitrification tank from the wastewater introduction side.

FIG. 10 is another example in which the wastewater treatment apparatus of the present invention is a small-sized combined septic tank.

FIG. 11 is another example in which the wastewater treatment apparatus of the present invention is a small-sized combined septic tank.

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drainage 2 wastewater treatment tank 3 microorganism immobilization carrier 4 air diffuser 5 blower 6 screen 7 pump 8 membrane module 9 non-permeated water return line 10 treated water 11 denitrification tank 12 denitrifying bacteria immobilization carrier 13 baffle plate 14 stirrer 15 nitrifying bacteria immobilization carrier 16 nitrification tank 17 non-permeated water return line 18 nitrification treated water return line 19 anaerobic filtration device 20 first settling tank tank 21 nitrification treated water return line 22 non-permeated water return line 23 acetalized PVA containing water Gel 24 Final sedimentation tank 25 Sludge discharge pipe 26 Supernatant water 27 Denitrification water 28 Nitrification water 29 Nitrification water return line 30 Nitrification water 31 Denitrification water 32 Anaerobic tank 33 Aerobic tank 34 Precipitation tank

 ──────────────────────────────────────────────────続 き Continuation of the front page (31) Priority claim number Japanese Patent Application No. Hei 9-141305 (32) Priority date Hei 9 (1997) May 30 (33) Priority claim country Japan (JP) (72) Inventor Takeda Matsuda 1-2-1, Kaigan-dori, Okayama-shi, Okayama Pref. Kuraray Co., Ltd. (72) Inventor Hiroaki Fujii 1-2-1, Kaigan-dori, Okayama-shi, Okayama Pref. Kuraray Co., Ltd. (72) Nao Nakagawa Okayama 2045-1, Sakurazu, Kurashiki-shi Kuraray Co., Ltd. (72) Inventor Shinji Komori 3-8-2 Nihombashi, Chuo-ku, Tokyo Inside Kuraray Co., Ltd. (72) Inventor Tadao Shioya 1-1-12 Umeda, Kita-ku, Osaka 39 Kuraray Co., Ltd. (72) Inventor Masanobu Abe 1-2-1, Kaigandori, Okayama City, Okayama Prefecture Kuraray Co., Ltd.

Claims (18)

[Claims] 1. A wastewater treatment tank for introducing at least carrier particles having microorganisms immobilized thereon and decomposing and removing organic and / or inorganic substances in wastewater, and a membrane module for filtering treated water flowing out of the treatment tank. In wastewater treatment equipment,
A wastewater treatment apparatus, wherein non-permeated water that has not passed through the membrane module is returned and circulated to the treatment tank. 2. A denitrification tank in which carrier particles having denitrifying bacteria immobilized therein are brought into contact with wastewater under anaerobic conditions, and an aerobic condition in which carrier particles having immobilized nitrifying bacteria are fed into the wastewater treatment tank. A nitrification tank to be brought into contact with the wastewater below.These wastewater treatment tanks are arranged in this order from the introduction side of the wastewater, and the nitrification treatment water flowing out of the nitrification tank is supplied to the membrane module. Part of the water is returned to the denitrification tank and circulated, and the non-permeated water that has not passed through the membrane module is removed from the nitrification tank and / or
The wastewater treatment device according to claim 1, wherein the wastewater treatment device is configured to be returned and circulated to a denitrification tank. 3. An anaerobic filtration device for performing an initial sedimentation tank or anaerobic treatment is provided before the denitrification tank to supply nitrification treatment water flowing out of the nitrification tank to the membrane module, 3. The wastewater treatment according to claim 2, wherein the section is returned and circulated to the denitrification tank or the first settling tank or the anaerobic filter, and the non-permeated water which has not passed through the membrane module is returned and circulated to the nitrification tank. apparatus. 4. A wastewater treatment tank into which a carrier particle on which nitrifying bacteria are immobilized is charged and brought into contact with wastewater under aerobic conditions, and an anaerobic condition by introducing carrier particles on which denitrifying bacteria are immobilized. A denitrification tank that is brought into contact with wastewater underneath.These wastewater treatment tanks are arranged in this order from the wastewater introduction side, and the denitrification treatment water flowing out of the denitrification tank is supplied to the membrane module. The wastewater treatment apparatus according to claim 1, wherein the non-permeated water that has not passed through the wastewater is returned and circulated to the denitrification tank and / or the nitrification tank. 5. The wastewater treatment device according to claim 1, wherein said wastewater treatment device is a combined septic tank. 6. The wastewater treatment apparatus according to claim 1, wherein the carrier on which the microorganisms are immobilized is a polyvinyl alcohol-based hydrogel. 7. The wastewater treatment apparatus according to claim 1, wherein the carrier on which the microorganism is immobilized is an acetalized polyvinyl alcohol-based 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. The carrier on which microorganisms are immobilized has a diameter of 0.1 to 0.1.
The wastewater treatment device according to claim 1, wherein the wastewater treatment device is a polyvinyl alcohol-based hydrogel having a network structure formed by entanglement of 50 µm fibrous materials. 10. The wastewater treatment apparatus according to claim 1, wherein the microorganism-immobilized carrier is a carrier containing activated carbon on its surface and / or inside. 11. The wastewater treatment apparatus according to claim 1, wherein the membrane used for the membrane module is a microfiltration membrane or an ultrafiltration membrane. 12. The wastewater treatment apparatus according to claim 1, wherein the membrane used for the membrane module is a hydrophilic membrane or a hydrophilized membrane. 13. A wastewater treatment apparatus comprising at least a wastewater treatment tank for introducing carrier particles having microorganisms immobilized thereon and decomposing and removing organic substances and / or inorganic substances in the wastewater, wherein the carrier on which microorganisms are immobilized is acetal. A wastewater treatment apparatus characterized in that the wastewater treatment apparatus is a hydrated polyvinyl alcohol-based hydrogel. 14. A wastewater treatment tank into which carrier particles on which denitrifying bacteria are immobilized are charged and brought into contact with wastewater under anaerobic conditions, and an aerobic condition by introducing carrier particles on which nitrifying bacteria are immobilized. A nitrification tank to be brought into contact with the wastewater underneath, these wastewater treatment tanks are arranged in this order from the introduction side of the wastewater, and a part of the nitrification treatment water flowing out of the nitrification tank is returned and circulated to the denitrification tank. 14. The wastewater treatment apparatus according to claim 13, wherein: 15. An anaerobic filtration device for performing an initial sedimentation tank or an anaerobic treatment before the denitrification tank, and a part of the nitrification treatment water flowing out of the nitrification tank is supplied to the denitrification tank or the first sedimentation tank or the anaerobic filtration device. 14. The wastewater treatment device according to claim 13, wherein the wastewater treatment device is configured to be returned and circulated. 16. The wastewater treatment tank is charged with carrier particles having nitrifying bacteria immobilized thereon, and is brought into contact with wastewater under aerobic conditions. The effluent treatment tank is charged with carrier particles having denitrifying bacteria immobilized thereon under anaerobic conditions. 14. The wastewater treatment apparatus according to claim 13, wherein the wastewater treatment tank is a denitrification tank that is brought into contact with wastewater below, and the wastewater treatment tanks are arranged in this order from a wastewater introduction side. 17. The wastewater treatment device according to claim 13, wherein the wastewater treatment device is a combined septic tank. 18. The wastewater treatment according to claim 13, wherein the acetalized polyvinyl alcohol-based hydrogel is a polyvinyl alcohol-based hydrogel having a network structure formed by entanglement of fibrous materials having a diameter of 0.1 to 50 μm. apparatus.