JP2010207657A - Wastewater treatment apparatus and wastewater treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus and a wastewater treatment method which achieve reduction in aeration power and prevention of clogging of a membrane. <P>SOLUTION: The wastewater treatment apparatus 10 includes: a denitrification tank 12a to which raw water is supplied; a nitrification tank 12b communicated with the denitrification tank 12a; an inclusively immobilized carrier 42 of a particle diameter 0.3-2.0 mm, in which microorganisms for biologically treating water to be treated in the nitrification tank 12b is inclusively immobilized; a membrane unit 14 which is immersed inside the nitrification tank 12b and performs solid-liquid separation by membrane filtration; and an air diffusion pipe 16 arranged below the membrane unit 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wastewater treatment apparatus and a wastewater treatment method, and relates to a wastewater treatment apparatus and a wastewater treatment method using membrane separation.

  Conventionally, in a wastewater treatment facility using an activated sludge treatment method, application of a membrane separation activated sludge method (MBR: membrane bioreactor) combining activated sludge treatment and membrane separation has been promoted. Since this method employs membrane filtration as a solid-liquid separation method, it is possible to prevent the turbidity of treated water from flowing out and to completely remove E. coli, which is hygienic and highly transparent. It has the characteristic that treated water can be obtained stably. In addition, since the activated sludge can be kept at a high concentration, the processing time can be shortened and the processing facility can be made compact.

  However, the conventional membrane separation apparatus using the membrane separation activated sludge method has a big problem that the membrane is clogged. In particular, when sludge properties are poor (ie, sludge flocs are fine, biological metabolites are very large, etc.), membrane clogging is likely to occur, and frequent chemical cleaning of the membrane is required. Further deterioration of the film and a decrease in the membrane life have hindered stable operation.

  As means for solving this problem, Patent Document 1 discloses a first backwash line for backwashing the membrane with backwash water to which an oxidant is added, and a reverse in which both the addition of the oxidant and the irradiation of ultraviolet rays are performed. It is described that the life of the membrane is extended by switching the second backwash line for backwashing the membrane with washing water according to the degree of contamination of the membrane.

  Patent Document 2 describes that the operation of the out-of-system discharge pump is controlled, and sludge in a tank in which no membrane element is installed is discharged out of the system to prevent clogging of the membrane. Yes.

  Patent Document 3 describes that the supply of ozone to the treated water circulating through the nitrification tank and the denitrification tank prevents the gel-like substance from adhering to the filtration membrane of the filtration unit.

Japanese Patent No. 4144394 Japanese Patent No. 3894686 Japanese Patent No. 3832232

  However, in the membrane cleaning apparatus described in Patent Document 1, there is a problem that the membrane surface is easily contaminated by activated sludge maintained at a high concentration, and clogging is likely to occur, and it is necessary to strongly aerate the membrane surface. Similarly, in the processing apparatus described in Patent Document 2, it is necessary to strongly aerate the film surface in order to prevent contamination of the film surface.

  Moreover, in the membrane separation apparatus described in Patent Document 3, the viscosity of the treated water is high because the activated sludge is kept at a high concentration. Therefore, there is a problem that aeration efficiency is poor when the film surface is aerated to prevent clogging.

  In any case of Patent Documents 1 to 3, strong aeration to the film surface is required. In particular, since the power required for aeration accounts for 2/3 of the power consumed by MBR, development of an energy-saving MBR for preventing global warming is desired.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wastewater treatment apparatus and a wastewater treatment method capable of reducing aeration power and preventing membrane clogging.

  In order to achieve the above object, the wastewater treatment apparatus of the present invention includes a reaction tank to which raw water is supplied and a microorganism for biologically treating the processing components in the raw water supplied to the reaction tank. Encapsulated immobilization carrier having a particle diameter of 0.3 mm to 2.0 mm, a membrane unit for solid-liquid separation by membrane filtration immersed in the reaction vessel, and in the reaction vessel, below the membrane unit And an aeration device arranged.

  In order to achieve the above object, the wastewater treatment method of the present invention comprises a step of supplying raw water to a reaction tank, and a particle size obtained by comprehensively immobilizing microorganisms for the treatment components in the raw water supplied into the reaction tank. A step of biological treatment with a 0.3 mm to 2.0 mm entrapping immobilization carrier, a step of performing solid-liquid separation by membrane filtration using a membrane unit immersed in the reaction vessel, and a lower portion of the membrane unit And a step of diffusing the inside of the reaction tank by the diffusing device arranged in the above.

  By applying the above-mentioned entrapping immobilization carrier, the MLSS concentration in the reaction vessel can be reduced. Thereby, the supply air amount required for the endogenous respiration rate can be reduced, and the aeration power of the diffuser can be reduced. Moreover, by reducing the MLSS concentration, the viscosity of the treated water in the reaction tank can be reduced, and the aeration efficiency of the aeration apparatus can be improved.

  By applying a entrapping immobilization carrier having a particle size of 0.3 mm to 2.0 mm, the substrate and oxygen penetrate to the central part of the entrapping immobilization carrier, and microorganisms can easily grow. The reaction rate can be increased.

  The particle size of the entrapping immobilization carrier is more preferably 0.5 mm to 1.0 mm.

  The MLSS concentration means activated sludge suspended solids (Mixed Liquor Suspended Solids) in the reaction tank.

  By applying a entrapping immobilization carrier having a particle diameter of 0.3 mm to 2.0 mm and performing aeration, the membrane surface of the membrane unit can be efficiently washed, and clogging of the membrane can be prevented. As a result, the cleaning interval of the membrane unit can be extended, and stable operation is possible. Moreover, since it is washed by the entrapping immobilization carrier, the aeration power of the aeration apparatus can be reduced.

  Here, the particle diameter means the diameter when the entrapping immobilization support is spherical, and the side length when the entrapping immobilization support is almost cubic.

  In the wastewater treatment apparatus of the present invention, in the above invention, it is preferable that the addition amount of the entrapping solidification carrier supplied to the reaction tank is 5% to 30%. In the wastewater treatment method of the present invention, in the above invention, the amount of the entrapping solidification carrier added is preferably 5% to 30%.

  Here, the amount of the entrapping immobilization carrier added will be examined. In order to determine the addition amount, it is necessary to consider (1) processing load, (2) oxygen supply, and (3) carrier flow.

Processing speed, in general entrapping immobilization pellets 1 m ³ 1 day per can process 10 kg-BOD. Next, considering oxygen supply, in the case of air aeration, 4 kg-BOD becomes a limit in a 1 m ³ reaction tank. Above that, pure oxygen is required. Therefore, in this case, the amount of the entrapping immobilization carrier added is 40% as a practical limit.

  On the other hand, since 30% is a practical limit from the fluidity of the entrapping immobilization carrier, it is preferable to operate at an upper limit of 30% or less.

  Finally, when combining (1) to (3), the practical carrier addition amount is 5 to 30%, preferably 10 to 15%.

  Here, the amount of carrier added is calculated by dividing the carrier Volume (numerator) by the reaction tank volume Volume (denominator) containing the carrier.

  In the wastewater treatment apparatus of the present invention, the MLSS concentration in the reaction tank is preferably 4000 mg / L or less. In the wastewater treatment method of the present invention, in the above invention, the MLSS concentration in the reaction tank is preferably 4000 mg / L or less.

  By setting the MLSS concentration in the reaction tank to 4000 mg / L or less, it is possible to prevent the viscosity of the mixed liquid in the reaction tank from increasing. It can prevent that the aeration efficiency of a diffuser accompanying the increase in viscosity of a liquid mixture falls.

  In the above invention, the wastewater treatment apparatus of the present invention preferably includes a discharge pipe for extracting excess sludge from the reaction tank. The wastewater treatment method of the present invention preferably has a step of extracting excess sludge from the reaction tank in the invention.

  By discharging the excess sludge from the reaction tank, it is possible to prevent the microbial concentration of the mixed liquid in the reaction tank from being increased, and as a result, increase in the viscosity of the mixed liquid.

  According to the wastewater treatment apparatus and the wastewater treatment method of the present invention, reduction of aeration power and prevention of membrane clogging can be realized.

The schematic diagram of the wastewater treatment equipment of the present invention. The flow sheet which shows the other wastewater treatment apparatus of this invention. The flow sheet which shows the other wastewater treatment apparatus of this invention. The graph which shows the relationship between the particle diameter and addition amount of a entrapping immobilization support | carrier, and the washing | cleaning interval of a membrane unit. The graph which shows the cleaning interval of the conventional membrane unit.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention will be described with reference to the following preferred embodiments, but can be modified in many ways without departing from the scope of the present invention, and other embodiments than the present embodiment can be used. be able to. Accordingly, all modifications within the scope of the present invention are included in the claims. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to”.

  FIG. 1 is a schematic diagram showing the overall configuration of a wastewater treatment apparatus 10 to which the present invention is applied. The wastewater treatment apparatus 10 is a nitrification / denitrification apparatus, and is connected to the reaction tank 12, the membrane unit 14 immersed in the reaction tank 12, the diffuser pipe 16 provided below the membrane unit 14, and the diffuser pipe 16. And at least a blower 18 formed. The reaction tank 12 is partitioned by a partition wall 20 into a denitrification tank 12a and a nitrification tank 12b. The membrane unit 14 and the air diffuser 16 are arranged in the nitrification tank 12b. A stirring device 30 is installed at the bottom of the denitrification tank 12a.

  A raw water tank 22 is installed upstream of the reaction tank 12, and a supply line 24 is provided between the raw water tank 22 and the denitrification tank 12a. Raw water is supplied from the raw water tank 22 to the denitrification tank 12 a via the supply line 24. Raw water is stored in the denitrification tank 12a.

  A raw water line 28 is connected to the raw water tank 22, and raw water is stored in the raw water tank 22 from the raw water line 28. The raw water is discharged to the supply line 24 through a fine screen 26 installed in the raw water tank 22. For example, the fine screen 26 includes a mesh having a pore diameter of 0.3 to 0.5 mm, and solids are removed by the fine screen 26.

  The reaction tank 12 is provided with a circulation line 32 for circulating the treated water from the nitrification tank 12b to the denitrification tank 12a. A pump 34 is disposed in the circulation line 32, and by driving the pump 34, part of the treated water in the nitrification tank 12 b is returned to the denitrification tank 12 a through the circulation line 32. Thereby, treated water circulates between the nitrification tank 12b and the denitrification tank 12a.

  The nitrification tank 12b is provided with a discharge line 36 for extracting excess sludge. The discharge line 36 is provided with a pump 38. By driving the pump 38, excess sludge is discharged from the nitrification tank 12b. When discharging excess sludge, for example, in order to maintain the MLSS concentration, the amount of operation of the pump 38 is controlled by calculating the amount of sludge extraction using an MLSS concentration meter (not shown) and the inflow load.

  A discharge line 44 is connected to the membrane unit 14, and a pump 46 is provided in the discharge line 44. By driving the pump 46, the treated water is taken out from the nitrification tank 12b through the membrane unit 14. When the treated water passes through the membrane unit 14, solid-liquid separation is performed. As the membrane unit 14, a known membrane unit such as a flat membrane type, a hollow fiber type, and a tubular type can be used.

  The entrapping immobilization carriers 40 and 42 in which microorganisms are entrapped and immobilized are introduced into the denitrification tank 12a and the nitrification tank 12b. In particular, the entrapping immobilization carrier 42 charged into the nitrification tank 12b has a particle diameter in the range of 0.3 mm to 2.0 mm.

  According to the type of each reaction tank, the microorganisms comprehensively immobilized on the entrapping immobilization carrier of the present invention include nitrifying bacteria or nitrifying bacteria group, denitrifying bacteria group, anaerobic ammonia oxidizing bacteria group and the like for the purpose of nitrogen removal. Suitable examples include complex microorganisms and microorganisms capable of degrading specific harmful chemicals such as dioxins (for example, pure microorganisms such as blue-green-degrading bacteria, PCB-degrading bacteria, dioxin-degrading bacteria, and environmental hormone-degrading bacteria) As mentioned. In addition to microorganisms concentrated and separated by culture or the like, microorganisms include microorganism-containing substances including various microorganisms such as activated sludge in sewage treatment plants, lakes and marshes, river and sea sludge, and soil.

  Examples of the immobilization material include monomers, prepolymers, oligomers and the like, but are not particularly limited. For example, polyacrylamide, polyvinyl alcohol, polyethylene glycol, sodium alginate, carrageenan, agar, and the like can be used. . In addition, the following can be used as the prepolymer of the fixing material.

(Monomethacrylates)
Polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, methacryloyloxyethyl hydrogen phthalate, methacryloyloxyethyl hydrogen succinate, 3chloro-2hydroxypropyl methacrylate, stearyl methacrylate, 2-hydroxy methacrylate, ethyl methacrylate and the like.

(Monoacrylates)
2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobutyl acrylate, tbutyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate, methoxytriethylene glycol acrylate, 2 ethoxyethyl acrylate, tetrahydrofur Furyl acrylate, phenoxyethyl acrylate, nonylphenoxy polyethylene glycol acrylate, nonyl phenoxy polypropylene glycol acrylate, silicon modified acrylate, polypropylene glycol monoacrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxy polyethylene glycol acrylate DOO, methoxy polyethylene glycol acrylate, acryloyl luer carboxyethyl hydrogen succinate, lauryl acrylate.

(Dimethacrylates)
1,3-butylene glycol dimethacrylate, 1,4 butanediol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, butylene glycol dimethacrylate, hexanediol dimethacrylate, neopentyl glycol di Methacrylate, polypropylene glycol dimethacrylate, 2hydroxy 1,3 dimethacryloxy propane, 2,2 bis 4 methacryloxy ethoxy phenyl propane, 3,2 bis 4 methacryloxy diethoxy phenyl propane, 2,2 bis 4 methacryloxy polyethoxy Phenylpropane and the like.

(Diacrylates)
Ethoxylated neopentyl glycol diacrylate, polyethylene glycol diacrylate, 1,6 hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 2,2 bis 4-acryloxy ethoxyphenyl propane, 2hydroxy 1 acryloxy 3 methacryloxy propane and the like.

(Trimethacrylates)
Trimethylolpropane trimethacrylate and the like.

(Triacrylates)
Trimethylolpropane triacrylate, pentaerythritol triacrylate, trimethylolpropane EO addition triacrylate, glycerin PO addition triacrylate, ethoxylated trimethylolpropane triacrylate, and the like.

(Tetraacrylates)
Pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate and the like.

(Urethane acrylates)
Urethane acrylate, urethane dimethyl acrylate, urethane trimethyl acrylate, etc.

(Other)
Acrylamide, acrylic acid, dimethylacrylamide, etc.
In addition, you may use it combining 1 type or 2 types or more among the said fixing material.

  The polymerization of the entrapping immobilization carrier is optimally radical polymerization using potassium persulfate, but may be polymerization using ultraviolet light or electron beam or redox polymerization. In polymerization using potassium persulfate, the amount of potassium persulfate added may be 0.001 to 0.25% by mass, and the amount of amine polymerization accelerator added may be 0.01 to 0.5% by mass. preferable. As the amine-based polymerization accelerator, β-dimethylaminopropionitrile, NNN′N ′ tetramethylethylenediamine or the like can be preferably used.

  The entrapping immobilization carrier having a particle size of 0.3 mm to 2.0 mm can be produced, for example, by the following method. First, a carrier block having a size larger than the size used is manufactured. Next, the carrier block is set in a cutting device having a grid-like cutting blade. While conveying the carrier block at a predetermined conveyance speed, the carrier block is passed through and cut into a lattice shape. Finally, the carrier block cut into a lattice shape is cut with a rotating cutting blade, whereby a entrapping immobilization carrier having a particle diameter of 0.3 mm to 2.0 mm can be produced.

  Next, the operation of the wastewater treatment apparatus 10 will be described. Raw water to be treated is supplied from the raw water line 28 to the raw water tank 22. The raw water in the raw water tank 22 passes through the fine screen 26 and is sent out to the supply line 24.

  Raw water is supplied from the supply line 24 as treated water to the denitrification tank 12a maintained under oxygen-free conditions. In the denitrification tank 12a, the entrapping immobilization support 40 on which the denitrifying bacteria are immobilized and the treated water come into contact. Thereby, biological treatment is performed on the mixed solution under anoxic conditions. Since the stirrer 30 is provided at the bottom of the denitrification tank 12a, contact between the entrapping immobilization carrier 40 and the treated water is promoted, and biological treatment is efficiently performed.

  The treated water treated in the denitrification tank 12a flows into the nitrification tank 12b via the communication path 48 formed by the partition wall 20. In the nitrification tank 12b, the entrapping immobilization support 42 having a particle diameter of 0.3 mm to 2.0 mm, to which nitrifying bacteria are immobilized, contacts the treated water. An air diffuser 16 is disposed at the bottom of the nitrification tank 12b. The air diffuser 16 is connected to the blower 18, and air is supplied from the blower 18, and the air is diffused as bubbles in the mixed liquid. Therefore, the inside of the nitrification tank 12b is maintained at an aerobic condition, and biological treatment is performed on the mixed solution under the aerobic condition.

  Further, when air is supplied from the blower 18, the entrapping immobilization carrier 42 and the mixed solution are agitated, and biological treatment is efficiently performed. Since the entrapping immobilization carrier 42 is agitated, the entrapping immobilization carrier 42 comes into contact with a filtration membrane (not shown) in the membrane unit 14. Thereby, the deposit | attachment adhering to the filtration membrane can be peeled, and clogging of the filtration membrane can be prevented. In particular, since the particle size of the entrapping immobilization carrier 42 is 0.3 mm to 2.0 mm, it is efficiently stirred. As a result, the number of times of contact between the entrapping immobilization carrier 42 and the filtration membrane can be increased, and the deposits can be more effectively peeled off.

  By supplying air from the blower 18, the deposits attached to the filter membrane can be peeled off by the air. At this time, since the filtration membrane is washed by the entrapping immobilization carrier 42, the aeration power of the blower 18 can be reduced. By introducing the entrapping immobilization carrier 42, the MLSS concentration in the nitrification tank 12b can be lowered, and the viscosity of the treated water can be lowered. Thereby, the cleaning efficiency of the filtration membrane by the entrapping immobilization carrier 42 and air can be improved.

  The water treated in the nitrification tank 12 b is sucked into the membrane unit 14 by driving the pump 46. At that time, the treated water passes through the filtration membrane of the membrane unit 14, is subjected to solid-liquid separation treatment, and is taken out via the discharge line 44. A part of the mixed liquid in the nitrification tank 12b is returned to the denitrification tank 12a through the circulation line 32.

  In addition to the air diffuser 16 in the nitrification tank 12b, an auxiliary air diffuser 50 is provided. By diffusing air from the auxiliary air diffusing tube 50, oxygen necessary for the microbial reaction can be supplied.

  Further, when the MLSS concentration rises, surplus sludge is discharged from the nitrification tank 12b through the discharge line 36 by driving the pump 38. The MLSS concentration can be monitored by installing the MLSS densitometer in the nitrification tank 12b.

  FIG. 2 is a flow sheet of another wastewater treatment apparatus to which the present invention is applied. The wastewater treatment apparatus 100 includes a nitrification tank 102, a denitrification tank 104, and a re-aeration tank 106. The re-aeration tank 106 is provided with a membrane unit 116. The wastewater treatment apparatus 100 is preferably used when, for example, BOD / nitrogen is approximately 1 or less.

  Raw water is supplied to the nitrification tank 102 through the raw water line 108 as raw water. A entrapping immobilization carrier 202 in which nitrifying bacteria are entrapped and fixed is introduced into the nitrification tank 102, and the entrapping immobilization carrier 202 and treated water come into contact with each other. A diffuser tube 110 is disposed at the bottom of the nitrification tank 102 and connected to the blower 112. Air is supplied from the blower 112, and the air is diffused as bubbles into the treated water through the air diffuser 110. As a result, the nitrification tank 102 is aerobic, and biological treatment is performed on the raw water in the nitrification tank 102.

  Water treated in the nitrification tank 102 is introduced into a denitrification tank 104 under anoxic conditions. The denitrification tank 104 is loaded with a entrapping immobilization carrier 204 entrapping and fixing denitrifying bacteria. The treated water and the entrapping immobilization support 204 come into contact with each other, and the treated water is biologically treated in the denitrification tank 104. Methanol is introduced into the denitrification tank 104, and the denitrification tank 104 is subjected to oxygen-free conditions. Methanol is consumed when the nitrification water is biologically processed by the entrapping immobilization carrier 204.

  The treated water treated in the denitrification tank 104 is introduced into the re-aeration tank 106. A diffuser tube 114 is disposed at the bottom of the re-aeration tank 106 and connected to the blower 112. Air is supplied from the blower 112, and the air is diffused as bubbles in the treated water via the air diffusion pipe 114. Thereby, the re-aeration tank 106 becomes an aerobic condition. The re-aeration tank 106 is charged with a entrapping immobilization carrier 206 having a particle diameter of 0.3 mm to 2.0 mm and in which BOD-degrading bacteria are entrapped and immobilized. The entrapping immobilization carrier 206 is agitated by the air from the diffusion tube 114 and comes into contact with the filtration membrane of the membrane unit 116. Thereby, the deposit | attachment adhering to the filtration membrane can be peeled, and clogging of the filtration membrane can be prevented. Also in the wastewater treatment apparatus of FIG. 2, the same effect as the wastewater treatment apparatus described in FIG. 1 can be obtained. The treated water separated into solid and liquid by the membrane unit 116 is taken out from the re-aeration tank 106 through the discharge line 118.

  Basically, the entrapping immobilization carrier circulates in the nitrification tank-denitrification tank-re-aeration tank. Therefore, microorganisms in the entrapping immobilization carrier are grown by mixing nitrifying bacteria, denitrifying bacteria, and BOD bacteria.

  FIG. 3 is a flow sheet of another wastewater treatment apparatus to which the present invention is applied. The wastewater treatment apparatus 300 includes an aeration tank 302, a membrane unit 304 immersed in the aeration tank 302, and an aeration tube 306 disposed below the membrane unit 304. For example, the wastewater treatment apparatus 300 can be suitably used for an apparatus in which a entrapping immobilization support is introduced into an aerobic tank (aeration tank) for the purpose of removing BOD and SS.

  Raw water is supplied to the aeration tank 302 as raw water through the raw water line 308. In the aeration tank 302, a entrapping immobilization carrier 310 having a particle diameter of 0.3 mm to 2.0 mm in which BOD-degrading bacteria are entrapped and fixed is introduced, and the entrapping immobilization carrier 310 and raw water come into contact with each other. An aeration tube 306 is disposed at the bottom of the aeration tank 302 and connected to the blower 312. Air is supplied from the blower 312, and the air is diffused as bubbles in the mixed solution through the air diffusion pipe 306. Thereby, the aeration tank 302 is brought into an aerobic condition. In the aeration tank 302, the mixed solution is biologically processed. The entrapping immobilization carrier 310 is agitated by the air from the diffusion tube 306 and comes into contact with a filtration membrane (not shown) of the membrane unit 304. Thereby, the deposit | attachment adhering to the filtration membrane can be peeled, and clogging of the filtration membrane can be prevented. Also in the wastewater treatment apparatus of FIG. 3, the same effect as the wastewater treatment apparatus described in FIG. 1 can be obtained. The treated water separated into solid and liquid by the membrane unit 304 is taken out from the aeration tank 302 through the discharge line 314.

  As described above, the wastewater treatment apparatus and the wastewater treatment method of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications are made without departing from the gist of the present invention. May be.

  Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. The present invention is not limited to these examples.

<Experimental conditions>
The wastewater treatment apparatus shown in FIG. 1 was used to treat the wastewater. With respect to the particle diameter, the entrapping immobilization support having the same particle diameter within the range of 0.1 mm to 2.1 mm was added to the reaction vessel while changing the addition amount to 5%, 10%, and 15%. As the entrapping immobilization carrier, an entrapping immobilization carrier having the following carrier composition was used. The wastewater treatment apparatus was operated and treated under the following operating conditions.

(Composition of entrapping immobilization carrier)
・ Sludge: Activated sludge (dehydrated cake)
・ Sludge concentration: 2% by mass / carrier / immobilization material: polyethylene glycol diacrylate 15% by mass
-Polymerization accelerator: NNN'N 'tetramethylethylenediamine 0.0500% by mass
-Polymerization initiator: Potassium persulfate 0.0025 quality (operating conditions)
MLSS: 1000 mg / L to 3000 mg / L
・ Permeation flow rate: 0.8 m ³ / m ²・ Day ・ Chemical cleaning timing: When filtration pressure reaches 20 kPa ・ Membrane material: PVDF (polyvinylidene fluoride)
Under the above operating conditions, the chemical cleaning interval was measured for each particle size and added amount of the entrapping immobilization support. FIG. 4 is a graph showing the relationship between the particle size and addition amount and the cleaning interval.

  The wastewater treatment apparatus shown in FIG. 1 was used, and activated sludge was used instead of the entrapping immobilization support, and wastewater was treated under the following operating conditions.

(Operating conditions)
MLSS: 8,000 mg / L to 15,000 mg / L
・ Permeation flow rate: 0.8 m ³ / m ²・ Day ・ Chemical cleaning timing: When filtration pressure reaches 20 kPa ・ Membrane material: PVDF (polyvinylidene fluoride)
Under the above operating conditions, the chemical cleaning interval was measured. FIG. 5 is a graph plotting the cleaning interval of chemicals with the date as the horizontal axis and the vertical axis as the filtration pressure. From the graph of FIG. 5, it can be understood that the conventional method was cleaned at intervals of about once every two months.

  Next, FIG. 4 and FIG. 5 are compared. As described above, in the conventional method, the cleaning interval is about 2 months as shown in FIG. In FIG. 4, when the particle size of the entrapped solidified support was in the range of 0.3 mm to 2.0 mm, the cleaning interval was 2 months or more. That is, it can be understood that the cleaning effect on the filtration membrane was improved by setting the particle diameter of the entrapping immobilization support to a range of 0.3 mm to 2.0 mm. In addition, it can be understood from the graph of FIG. 4 that the cleaning effect is high, particularly when the particle diameter range is 0.5 mm to 1.0 mm, and the cleaning interval is as long as 3 months or more. Furthermore, it can be understood from FIG. 4 that when the particle size is the same, the larger the carrier addition amount, the longer the cleaning interval and the higher the cleaning effect.

  DESCRIPTION OF SYMBOLS 10 ... Waste water treatment apparatus, 12 ... Reaction tank, 12a ... Denitrification tank, 12b ... Nitrification tank, 14 ... Membrane unit, 16 ... Air diffuser, 18 ... Blower, 28 ... Raw water line, 30 ... Stirrer, 32 ... Circulation line, 34, 38, 46 ... pump, 36, 44 ... discharge line, 40, 42 ... entrapping immobilization carrier, 100 ... waste water treatment device, 102 ... nitrification tank, 104 ... denitrification tank, 106 ... re-aeration tank, 110, 114 ... Air diffuser, 112 ... Blower, 116 ... Membrane unit, 202,204,206 entrapping immobilization carrier, 300 ... Waste water treatment device, 302 ... Aeration tank, 304 ... Membrane unit, 306 ... Aeration tube, 310 ... Entrapment immobilization carrier, 312 ... Blower

Claims (8)

A reaction tank to which raw water is supplied;
A entrapping immobilization support having a particle size of 0.3 mm to 2.0 mm in which microorganisms that biologically treat the treatment components in the raw water supplied into the reaction vessel are immobilized.
A membrane unit for solid-liquid separation by membrane filtration immersed in the reaction vessel;
A diffuser disposed below the membrane unit in the reaction vessel;
Wastewater treatment equipment equipped with.   The wastewater treatment apparatus according to claim 1, wherein the amount of the entrapping solidification carrier added is 5% to 30%.   The wastewater treatment apparatus according to claim 1 or 2, wherein the MLSS concentration in the reaction tank is 4000 mg / L or less.   The wastewater treatment apparatus according to any one of claims 1 to 3, further comprising a discharge pipe for extracting excess sludge from the reaction tank. Supplying raw water to the reaction vessel;
Biologically treating the treatment components in the raw water supplied into the reaction tank with a entrapping immobilization support having a particle diameter of 0.3 mm to 2.0 mm in which microorganisms are entrapped and immobilized;
A step of performing solid-liquid separation by membrane filtration with a membrane unit immersed in the reaction vessel;
Aeration of the inside of the reaction vessel by an aeration device disposed below the membrane unit;
A wastewater treatment method comprising:   The wastewater treatment method according to claim 5, wherein the amount of the entrapping solidification support added is 5% to 30%.   The wastewater treatment method according to claim 5 or 6, wherein the MLSS concentration in the reaction tank is 4000 mg / L or less.   The wastewater treatment method according to any one of claims 5 to 7, comprising a step of extracting excess sludge from the reaction tank.

Images