JP2018192407A - Water treatment system and water treatment method - Google Patents

Abstract

To provide a system for treating raw water containing an organic matter and a method for treating raw water containing an organic matter capable of maintaining stable operation by reducing membrane blockage caused by excessive sludge that has been separated, using a carrier method and MBR together.SOLUTION: There is provided a water treatment system, including: a carrier treatment tank 11 for biological treatment of raw water containing an organic matter in the presence of a carrier 17; an MBR conditioning tank 12 into which air with an aeration intensity of 0.1 to 1 m/mh is blown; and an MBR reaction tank 13 and a separation membrane on the downstream of the MBR conditioning tank 12.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a water treatment system and a water treatment method.

Conventionally, as an organic matter-containing wastewater treatment system, a carrier method that can efficiently treat organic matter by attaching microorganisms to a carrier and a membrane separation activated sludge treatment method (hereinafter referred to as “MBR”) that performs solid-liquid separation using a separation membrane. (For example, Patent Document 1).
However, the excess sludge separated from the carrier treatment has a problem of promoting the clogging of the separation membrane. Therefore, it is necessary to manage both the reduction of the exfoliation of the exfoliated sludge and the proper tension of the dissolved oxygen concentration in the MBR reaction tank, and the operation management becomes substantially difficult.

JP 2006-123920 A

  The present invention has been made in view of the above problems, and by reducing membrane clogging due to excess sludge that has been peeled off, a treatment system for raw water containing organic substances that can maintain a stable operation by using the carrier method and MBR together, and It aims at providing the processing method of the raw | natural water containing an organic substance.

The present disclosure includes the following inventions.
(1) a carrier treatment tank for biologically treating raw water containing organic matter in the presence of a carrier;
An MBR conditioned tank into which air having an aeration intensity of 0.1 to ¹ m ³ / m ³ · h is blown, an MBR reaction tank including a separation membrane for filtering waste water treated in the MBR conditioned tank, and a separation membrane Water treatment system characterized by
(2) The water treatment system as described above, wherein a filling rate of the carrier in the carrier treatment tank is 10 to 40%.
(3) The water treatment system as described above, wherein the dissolved oxygen is 2 to 4 mg / L and the activated sludge amount is 5,000 to 20,000 mg / L in the MBR reactor.
(4) The water according to the above, wherein the separation membrane is a ultrafiltration membrane having a single layer structure of a chlorinated vinyl chloride resin having a chlorine content of 58 to 73.2% and a molecular weight cut-off of 150,000 or less. Processing system.
(5) Raw water containing organic matter is treated in a carrier treatment tank for biological treatment in the presence of a carrier, an MBR conditioned tank in which air with an aeration intensity of 0.1 to ¹ m ³ / m ³ · h is blown, and the MBR conditioned tank. The water treatment method is characterized in that the waste water is passed through an MBR reaction tank equipped with a separation membrane for filtering, and treated with a membrane separation module.
(6) The water treatment method as described above, wherein the carrier is disposed in the carrier treatment tank at a filling rate of 10 to 40% to treat the organic matter-containing treated waste water.
(7) The water treatment method as described above, wherein the dissolved oxygen in the MBR reactor is 2 to 4 mg / L and the amount of activated sludge is 5,000 to 20,000 mg / L.

  By using the carrier method and MBR of the present invention in combination, the treatment capacity of raw water containing organic matter can be improved by both the carrier and the activated sludge. Furthermore, since the dispersibility of the sludge peeled off from the carrier can be reduced in the MBR tank, it contains organic substances that can reduce the membrane clogging by the sludge and maintain the operation in which the transmembrane pressure difference of the membrane separation module is stabilized. It is possible to provide a raw water treatment system and a method for treating raw water containing organic matter using the system.

It is a mimetic diagram showing an example of the composition of the water treatment system of this embodiment.

[Water treatment system]
As shown in FIG. 1, the water treatment system according to an embodiment of the present application includes a carrier treatment tank 11, an MBR conditioned tank 12, and an MBR reaction tank 13 downstream of the MBR conditioned tank 12. A membrane separation module 15 is connected to the MBR reaction tank 13. In addition, the MBR acclimation tank 12 and the MBR reaction tank 13 satisfy the conditions of both the MBR acclimation tank 12 and the MBR reaction tank 13 as will be described later, and are configured as one tank that combines both tanks. Also good.
Such three kinds of tanks having different roles are provided, optionally, further tanks having different roles are provided, and by adjusting the operating conditions and / or the optimum aeration amount in each tank, particularly the MBR acclimation tank, membrane separation The risk of blockage in the module 15 can be reduced, and the carrier method and the membrane-separated activated sludge treatment method can be combined to realize stable and efficient water treatment at high speed, space-saving. Can do.

(Carrier processing tank 11)
The carrier treatment tank 11 is loaded with a carrier 17. Various known carriers can be used as the carrier 17. The shape and material of the carrier 17 are not limited, and can be selected from, for example, a gel-like carrier, a plastic carrier, and a fibrous carrier. These may be used alone or in combination of two or more. Of these, from the viewpoint of processing performance and / or fluidity, an acetal or polyvinyl alcohol gel carrier is preferable, and from the viewpoint of adhesion of microorganisms, a porous carrier such as a porous polyurethane fluid sponge carrier is preferred. Various biological species such as bacteria, fungi, protozoa, and metazoans that are usually used in the art are supported on the carrier so that they coexist with each other and have a predatory relationship. The species and amount of these organisms can be appropriately adjusted and used.

As for the filling rate of the carrier, for example, when the tank capacity of the carrier treatment tank 11 is 100%, 5 to 50% is mentioned, and 10 to 40% is preferable. By filling the carrier in such a range, the microorganism can be held in an appropriate holding amount, and the treatment with the microorganism can be appropriately performed.
The carrier 17 may be either a fluid type that flows in the carrier processing tank 11 or a fixed type in which a cartridge or the like filled with the carrier 17 is installed in the carrier processing tank 11.

In the carrier processing tank 11, an air supply line 18a connected to a blower for aeration is arranged, and air is supplied from the air supply line 18a. As the blower is driven, air is supplied into the carrier treatment tank 11 and an aerobic treatment associated therewith is performed. As will be described later, the blower may have a function of increasing or decreasing the pressure of the supply air with a compressor or the like. The carrier treatment tank 11 is preferably set so that, for example, air with an aeration strength of 0.1 to ¹ m ³ / m ³ · h is blown into the carrier treatment tank 11. From another viewpoint, the dissolved oxygen (DO) is preferably an oxygen amount necessary for general biological treatment, for example, 0.5 mg / L or more, and more preferably 1 mg / L or more.

  A drainage line 14 a is connected to the drainage inlet of the carrier treatment tank 11, and raw water containing organic matter for processing is supplied. Further, a drainage line 14b is connected to the drainage outlet of the carrier treatment tank 11, and the other end is connected to a drainage inlet of the MBR acclimation tank 12 described later. It is comprised so that it can supply to the MBR acclimatization tank 12 to do.

  The raw water containing organic matter that is the treatment target of the water treatment system of the present application is not particularly limited as long as it is generally wastewater containing organic matter that can be biologically treated. For example, sewage, electronic industrial wastewater, chemical factory wastewater, Examples include factory wastewater such as food factory wastewater. The organic matter concentration in the wastewater to be treated includes a biochemical oxygen demand concentration (BOD concentration) of 100 mg / L or more from the viewpoint of biological treatment speed, and a range of 300 to 2000 mg / L is preferable.

(MBR acclimatization tank 12)
Activated sludge is introduced into the MBR acclimation tank 12. The activated sludge contains various biological species such as bacteria, fungi, protozoa, and metazoans that are commonly used in the field. The biological species here may be substantially the same as the biological species supported on the carrier, but the same biological species may not necessarily coexist due to environmental factors. The amount can be adjusted as appropriate.

An air supply line 18b connected to a blower for aeration is disposed in the MBR acclimatization tank 12, and air is supplied from the air supply line 18b. As the blower is driven, air is supplied into the MBR accordion tank 12 and an aerobic process is performed. The blower may have a function of increasing or decreasing the pressure of the supply air with a compressor or the like. It is preferable that the MBR acclimatization tank 12 is set so that, for example, air with an aeration intensity of 0.1 to ¹ m ³ / m ³ · h is blown. By blowing air, the main biological species contained in the sludge can be changed, and the sludge itself peeled off from the organism holding carrier contains highly dispersible microorganisms (for example, filamentous fungi). The dispersibility of can be reduced. This balances the rate of growth and autooxidation of major species in sludge, prevents the increase of major species in sludge, and adjusts the rate of growth and autooxidation of other species, It is possible to promote the increase of other species in the sludge. As a result, it is possible to avoid the inflow of the species causing the blockage into the membrane in the membrane separation module in the MBR reactor described later, and to effectively reduce the risk of the membrane clogging of the separation membrane. it can.

The treated water inlet of the MBR acclimatization tank 12 is connected to the other end of the drainage line 14b whose one end is connected to the drainage outlet of the carrier treatment tank 11, and the treated water treated in the carrier treatment tank 11 is MBR. It is comprised so that it may be supplied to the acclimatization tank 12.
A drainage line 14c is connected to the treated water outlet of the MBR conditioned tank 12, and the other end is connected to a treated water inlet of the MBR reaction tank 13 described later, and water treated in the MBR conditioned tank 12 will be described later. It is preferable to be configured to be able to supply to the MBR reaction tank 13.

(MBR reactor 13)
In the MBR reaction tank 13, activated sludge is introduced, for example, activated sludge from a sewage treatment plant is introduced.
The MBR reaction tank 13 is provided with an air supply line 18c connected to a blower for aeration, and air is supplied from the air supply line 18c. As the blower is driven, air is supplied into the MBR reaction tank 13 and the aerobic treatment associated therewith is performed. The blower may have a function of increasing or decreasing the pressure of the supplied air with a compressor or the like.

  In the MBR reaction tank 13, for example, the dissolved oxygen is preferably 0.5 to 10 mg / L, and more preferably 2 to 4 mg / L. The amount of activated sludge is preferably 1,000 to 50,000 mg / L, and more preferably 5,000 to 20,000 mg / L. Furthermore, it is still more preferable that dissolved oxygen is 2-4 mg / L and the amount of activated sludge is 5,000-20,000 mg / L.

  The dissolved oxygen can be measured by, for example, a chemical analysis method (titration method), an electrochemical analysis method (diaphragm electrode method), a photochemical analysis method (fluorescence method), or the like. The amount of activated sludge can be measured by, for example, a sewage test method, an activated sludge suspended solid (MLSS) measurement method (centrifugation method, glass fiber filter paper method, etc.). Specifically, dissolved oxygen can be measured automatically and continuously by installing a field-installed diaphragm-type DO meter and MLSS installing a field-installed optical MLSS meter in the MBR reactor. preferable.

  Such dissolved oxygen amount and activated sludge amount reduce or increase the supply of air to the MBR acclimatization tank 12 when measured outside the above-mentioned range while measuring periodically or continuously during water treatment. Thus, it can be adjusted to the above-described range. Further, in addition to or instead of this method, the sludge can be added or extracted to adjust to the above-described range.

The treated water inlet of the MBR reaction tank 13 is connected to the other end of the drainage line 14c whose one end is connected to the drainage outlet of the MBR conditioned tank 12, and the treated water treated in the MBR conditioned tank 12 is MBR. It is configured to be supplied to the reaction tank 13.
Further, a membrane separation module 15 is connected to the MBR reaction tank 13. The membrane separation module 15 may be accommodated in the MBR reaction tank 13 or may be disposed outside the tank.

  The carrier treatment tank 11, the MBR acclimation tank 12, and / or the MBR reaction tank 13 may be provided with a stirring means capable of stirring the liquid. Examples of the stirring means include a stirring blade and a stirring rod. Moreover, what combined these and a baffle plate may be used. In these tanks, as described above, it may be effective to provide a stirring means for supplementing the stirring effect associated with the reduction of the blowing amount by the blower or improving the dissolution efficiency by extending the residence time of the air. .

In addition, the pH of the carrier treatment tank 11, the MBR acclimation tank 12 and / or the MBR reaction tank 13 may be in a range suitable for general biological treatment, and is preferably in the range of 6 to 9, for example, 6.5 to 6.5. A range of 7.5 is more preferred. The pH adjustment is performed by adding a pH adjuster to each tank. Examples of the pH adjuster include acid agents such as hydrochloric acid and alkali agents such as sodium hydroxide.
The water temperature of the carrier treatment tank 11, the MBR acclimation tank 12 and / or the MBR reaction tank 13 may be in a range suitable for general biological treatment, and is preferably in the range of 15 to 35 ° C, for example, 20 to 30 ° C. A range is more preferred.
A nutrient may be added to the carrier treatment tank 11, the MBR acclimation tank 12 and / or the MBR reaction tank 13. As a nutrient, what is necessary is just to maintain the decomposition activity of microorganisms well, for example, a nitrogen source, a phosphorus source, other inorganic salts, etc. are mentioned.

(Membrane separation module 15)
As the membrane separation module 15 connected to the MBR reaction tank 13, those known in the art can be used.
The means for supplying activated sludge / treated water from the MBR reaction tank 13 to the membrane separation module 15 may use a pump or may use a water head difference. In addition, the driving force of filtration in the membrane separation module may be a pressurization from the primary side, a suction from the secondary side, a combination of pressurization and suction, A siphon phenomenon may be used.

  Examples of the membrane separation module 15 include those disclosed in Japanese Patent Application Laid-Open No. 62-140607, Japanese Patent Application Laid-Open No. 6-319961, Japanese Patent Application Laid-Open No. 2009-183822, Japanese Patent Application Laid-Open No. 2012-166201, and Japanese Patent No. 4809503. It can be used, and a plurality of hollow fiber membranes are housed in a case. The outer diameter, length, number and the like of the hollow fiber membrane can be appropriately adjusted according to the characteristics of the membrane separation module to be obtained. The hollow fiber membrane preferably has a so-called large diameter (for example, an outer diameter of about 3.6 mm or more and about 4.0 mm or more, further about 5.3 mm or more and about 10 mm or less, and an inner diameter of 3.2 mm or more). The hollow fiber membrane is preferably a membrane having a self-supporting structure and having a separation function on both sides. The separation function here means a separation function more than microfiltration. Especially, it is more preferable that the main constituent material is a single material, and a hollow fiber membrane that can take a self-supporting structure without using a support member or the like made of another material at a site that functions as a hollow fiber membrane.

Examples of the resin forming the hollow fiber membrane include a vinyl chloride resin, a chlorinated vinyl chloride resin, a polysulfone (PS) system, a polyvinylidene fluoride (PVDF) system, a polyolefin system such as polyethylene (PE), and cellulose acetate. Examples include (CA), polyacrylonitrile (PAN), polyether sulfone, polyvinyl alcohol (PVA), polyimide (PI), and the like. Of these, vinyl chloride resins and chlorinated vinyl chloride resins are preferred. This resin preferably accounts for 50% by mass or more (preferably 60% by mass or more, more preferably 70% by mass or more, 80% or more, further preferably 85% or more) of the resin forming the hollow fiber membrane. .
In particular, a chlorinated vinyl chloride resin having a chlorine content of 58 to 73.2% is suitable. By using a resin having such a chlorine content, a sponge-like dense layer can be easily formed, and the strength of the film can be increased.

  Examples of the case include a cylindrical case that can accommodate a plurality of hollow fiber membranes. For example, a predetermined number of hollow fiber membranes are bundled in the case and accommodated in a straight shape as a hollow fiber membrane bundle, and both end surfaces thereof are sealed with a sealing material. A pipe communicating with the outer space of the hollow fiber membrane is connected between the sealing materials, and a primary pipe port is disposed as a filtered water outlet. Further, to-be-filtered water communicating with the inner (hollow) space of the plurality of hollow fiber membranes described above is supplied to or removed from another part of the case, for example, the end surface (one end surface or both end surfaces) side of the sealing material. A secondary pipe port to which a pipe for connecting is connected is arranged.

The membrane separation module is suitable to have a molecular weight cut-off of 300,000 or less, regardless of the configuration form, and is preferably classified into a so-called ultrafiltration membrane of 150,000 or less, preferably 10,000 to 50,000. More preferably, it is in the range of about. Further, the membrane separation module preferably has a pure water permeation amount of 500 L / m ² · hr · atm or more, and more preferably 1000 L / m ² · hr · atm or more. Further, the strength of the hollow fiber membrane constituting the membrane separation module is suitably 6 MPa or more in terms of tensile strength, preferably 8 MPa or more, and more preferably 10 MPa or more.
Only one membrane separation module may be used, or two or more membrane separation modules may be connected in series, in parallel, or a combination of series and parallel.

(Other facilities)
A blower or the like for introducing air may be connected to the membrane separation module. For example, when the membrane separation module is configured to be able to supply air with an internal pressure type, the introduced air passes through the membrane (membrane surface) and effectively acts on the dirt substance. be able to. As a result, it is possible to suppress the amount of introduced air and reduce energy consumption for supplying air to the membrane separation module.

  Furthermore, it is preferable that the membrane separation module includes at least one of a filtrate water tank, a chemical liquid tank, a backwash pump and / or a chemical liquid pump, a pipe for arbitrarily connecting them, in addition to the blower. The blower may also be used as a blower for supplying air to other tanks. In addition to or instead of these, an on-off valve, an ultrasonic generator, and the like may be provided at an arbitrary site. In addition, you may use the apparatus which can perform backwashing etc. using a water level difference, an air pressure, etc., without using a backwash pump and / or a chemical | medical solution pump, or a supply pump and / or a backwash pump, You may utilize as a chemical | medical solution injection pump.

(Blower)
The blower is a device that supplies gas (preferably compressed air). Generally, a blower, a compressor, or the like that generates microbubbles (for example, about several tens of μm to several hundreds of μm) is used. Usually, air is supplied as the gas, but an apparatus capable of supplying ozone, nitrogen gas, inert gas, or the like may be used. In particular, if a compressor is used in addition to or instead of the blower, the pressure of the supply air can be raised or lowered, and if the supply of high-pressure (high flow) air is temporarily intended, the contamination of the membrane It is possible to effectively reduce the increase in the supply water pressure due to the progress of the above.

The air can be removed by using a bubble for macro bubbles of about several tens to several hundreds of μm or an air discharge hole of about 1 mm to several tens of mm in stainless steel, ceramic, plastic, rubber, etc. The size can be adjusted as appropriate.
An ultrasonic generator may be used instead of or in addition to the blower. Examples of the ultrasonic wave include those having a frequency of about a dozen kHz to a few GHz.

  In particular, by applying a blower and / or ultrasonic generator to the membrane separation module, fine bubbles can be introduced into the membrane separation module, and sludge and the like adhering to the inner surface of the hollow fiber membrane can be efficiently removed. It can be peeled off and washed with air, and a high-throughput and low-energy apparatus can be operated during filtration.

(Filtration water tank)
The filtrate water tank is arranged downstream of the membrane separation module 1 to accommodate the water filtered by the membrane separation module.
In the filtrate tank, a part of the filtrate water can be used for backwashing, through a backwash pump in a route completely or partially different from the pipe through which the filtrate water from the membrane separation module passes. It is preferable that a pipe connected to the membrane separation module (particularly the secondary pipe port) is provided.

(Backwash pump)
The backwash pump is a pump used for supplying filtrate to the membrane separation module during backwashing. By driving such a backwash pump, it is possible to easily peel and remove the solid matter adhering to the inner surface of the hollow fiber membrane of the membrane separation module, and to stably perform filtration operation with high capacity. And the performance of the activated sludge treatment system can be improved. As a result, the amount of treated water obtained per unit time can be increased (high flux), and high-performance water treatment can be realized.

The chemical tank is usually arranged downstream of the membrane separation module. The chemical tank has a pipe connected to the membrane separation module (particularly, the secondary pipe port) via a chemical pump in a path different from or partially separate from the pipe through which the filtered water for backwashing passes. It is preferable that it is provided. Thereby, it can replace with the filtered water at the time of backwashing, or can add a chemical | medical solution in addition to filtered water. As the chemical solution, those usually used in the art can be used, and examples thereof include organic or inorganic acid or alkali aqueous solutions, oxidizing agents, detergents, surfactants, organic solvents, and the like, or combinations thereof. . By using the chemical solution for backwashing, the chemical solution can be washed in a shorter time, and the chemical solution can easily penetrate into the pores in the hollow fiber membrane by pressurization in the backwashing in a short time. Effective cleaning can be performed.
In addition, the pipe used for backwashing and the pipe used for chemical liquid washing are each equipped with a single pump at a site where the pipes are connected or shared, instead of being equipped with a backwash pump and a chemical liquid pump. The washing pump may be used as it is for chemical cleaning.

[Water treatment method]
The water treatment system described above can be used for water treatment by a method known in the art depending on the object, purpose, application, and the like.
For example, raw water containing organic matter is introduced into the carrier treatment tank 11 from the drainage line 14a. At that time, the blower is operated to supply air into the carrier processing tank 11 from the air supply line 18a. The amount of air introduced is preferably set so that, for example, the aeration intensity is 0.1 to ¹ m ³ / m ³ · h. In the carrier treatment tank 11, the organic matter (soluble BOD) in the wastewater is oxidatively decomposed by the biological species attached to the carrier 17 under aerobic conditions.

Thereafter, the treated water treated in the carrier treatment tank 11 is discharged from the drainage line 14 b and introduced into the MBR acclimation tank 12. At that time, the blower is operated, and air is supplied into the MBR acclimation tank 12 from the air supply line 18b. The amount of air introduced is preferably set such that the aeration intensity is 0.1 to ¹ m ³ / m ³ · h, for example. The sludge generated and / or propagated in the carrier treatment tank has been confirmed to have a risk of membrane clogging, but by introducing air at the above-mentioned aeration amount in the MBR acclimatization tank, the type of major species is changed. be able to. As a result, it is possible to effectively suppress the inflow of biological species that cause the membrane clogging in the membrane separation in the subsequent stage, and to reduce the risk of membrane clogging.

Subsequently, the treated water treated in the MBR acclimation tank 12 is discharged from the drain line 14 c and introduced into the MBR reaction tank 13. At that time, the blower is operated to supply air into the MBR reaction tank 13 from the air supply line 18c. The amount of air introduced is preferably set so that, for example, the aeration intensity is 0.1 to ¹ m ³ / m ³ · h. More preferably, the dissolved oxygen is 2 to 4 mg / L and the amount of activated sludge is 5,000 to 20,000 mg / L.

  Then, the treated water introduced into the MBR reaction tank 13 is supplied from the MBR reaction tank 13 to the membrane separation module 15 using the supply pump 16, for example. In the membrane separation module 15, for example, a certain pressure difference between the inner and outer membranes is loaded, and by using the pressure difference between the membranes, only water permeates the hollow fiber membrane, and suspended matter (dirt etc.) It is collected. Thereby, filtered water is obtained, and the obtained filtered water is fed into the filtrate water tank.

  The pressurization method in the membrane separation module 15 may be either an internal pressure type or an external pressure type, but in particular, an internal pressure type, that is, a sludge-containing liquid is supplied inside the hollow fiber membrane and filtered outside the hollow fiber membrane. A method of taking out water is preferred. Since the hollow fiber membrane used in the membrane separation module has a large diameter as described above, it can be processed without blocking high-turbidity water. Moreover, when pressurizing by internal pressure filtration, a high pressure filtration operation can be performed exceeding a relatively high transmembrane pressure difference.

  The membrane separation module 15 may be either dead end filtration (total filtration) or cross flow filtration. When the hollow fiber membrane used in the membrane separation module has a large diameter, it can process a larger amount of raw water in a shorter time than a small diameter, and it can be compared with a small diameter. And since a hollow fiber membrane is harder to obstruct | occlude, dead end filtration is preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and the raw | natural water system and the processing method containing the organic substance of this invention are demonstrated more concretely in detail, this invention is not limited to a following example.

(Examples and Comparative Examples)
In this example and comparative example, the raw water treatment system containing the organic substance shown in FIG. 1 was used.
This raw water treatment system containing organic matter includes a carrier treatment tank 11, an MBR acclimation tank 12, and an MBR reaction tank 13.
A drainage line 14 a is connected to the drainage inlet of the carrier treatment tank 11, and raw water containing organic matter for processing is supplied. Further, a drainage line 14b is connected to the drainage outlet of the carrier treatment tank 11, and the other end is connected to the drainage inlet of the MBR acclimation tank 12, and after the processing here, MBR which will be described later is completed. It is comprised so that it can supply to the acclimatization tank 12.
A drainage line 14c is connected to the treated water outlet of the MBR conditioned tank 12, and the other end is connected to the treated water inlet of the MBR reaction tank 13, so that the MBR reaction described below is performed on the water treated in the MBR conditioned tank 12. It is configured so that it can be supplied to the tank 13. Further, a membrane separation module 15 is connected to the MBR reaction tank 13.

  The membrane separation module 15 is configured by accommodating a plurality of hollow fiber membranes in an airtight state in a cylindrical case. The hollow fiber membrane has a self-standing structure with a large diameter (outer diameter is about 3.6 mm or more, inner diameter is 3.2 mm or more), and has a separation function on both sides (chlorine content: 58 to 73.2%), a pipe connected to the outer space of the hollow fiber membrane is connected to the case, and a primary pipe port is disposed as a filtered water outlet. A secondary pipe port to which a pipe for supplying or removing filtered water communicating with the inner (inside of the hollow) space of the hollow fiber membrane is connected to another part of the case. The fractional molecular weight of the membrane separation module 15 is classified as a so-called ultrafiltration membrane of 150,000 or less.

The MBR acclimatization vessel 12 with a raw water treatment system comprising the above-described organic, aeration intensity set so that 0~3.0m ³ / m ³ · h, and the membrane filtration flux of the membrane separation module 15 0 Adjusting to 3 m / D, water treatment was continuously performed for 1 month, and membrane filtration stability was measured.
The filtration flux is the amount of treated water per unit membrane area of the separation membrane, and is a value calculated as follows.
Filtration flux = treated water flow rate / membrane area of separation membrane Further, the carrier in the carrier treatment tank 11 was a polyolefin, and the filling rate of the carrier in the carrier treatment tank 11 was 25%.

  In the MBR reactor, the dissolved oxygen was adjusted to 2 to 4 mg / L, and the activated sludge amount was adjusted to the range of 5,000 to 20,000 mg / L. That is, an on-site diaphragm type DO meter and an optical MLSS meter are installed in the MBR reactor, respectively, and dissolved oxygen and MLSS are measured automatically and continuously. When the dissolved oxygen becomes 2 mg / L or less, the blower Air was supplied more, and when it reached 4 mg / L or more, the blower was stopped and controlled. Similarly, when the MLSS was 20000 mg / L or more, the extraction pump was operated and the amount of sludge was adjusted.

Here, the membrane filtration stability evaluated the transmembrane pressure difference of the membrane separation module 15 according to the following criteria.
When the transmembrane pressure difference after one month with respect to the first day shows an increase of 10 kPa or less:
When the transmembrane pressure difference after one month with respect to the first day shows an increase of 15 kPa or less,
When the transmembrane pressure difference after one month with respect to the first day shows an increase of 20 kPa or less: Δ
When the transmembrane pressure difference after one week with respect to the first day shows an increase of 20 kPa or more: ×
The amount of dissolved oxygen and activated sludge is a value measured with a water quality meter.
The transmembrane pressure difference of the membrane separation module 15 is a value measured by pressure gauges installed at the inlet and outlet of the treated water.

11: Carrier treatment tank 12: MBR acclimation tank 13: MBR reaction tanks 14a, 14b, 14c: Drain line 15: Membrane separation module 16: Supply pump 17: Carriers 18a, 18b, 18c: Air supply line

Claims (7)

A carrier treatment tank for biologically treating raw water containing organic matter in the presence of the carrier;
An MBR conditioned tank into which air having an aeration intensity of 0.1 to ¹ m ³ / m ³ · h is blown, an MBR reaction tank including a separation membrane for filtering waste water treated in the MBR conditioned tank, and a separation membrane Water treatment system characterized by   The water treatment system according to claim 1, wherein a filling rate of the carrier in the carrier treatment tank is 10 to 40%.   The water treatment system according to claim 1 or 2, wherein the dissolved oxygen in the MBR reactor is 2 to 4 mg / L and the amount of activated sludge is 5,000 to 20,000 mg / L.   The separation membrane is a ultrafiltration membrane having a single layer structure of a chlorinated vinyl chloride resin having a chlorine content of 58 to 73.2% and a molecular weight cutoff of 150,000 or less. The water treatment system as described in any one. A carrier treatment tank for biologically treating raw water containing organic matter in the presence of a carrier, an MBR conditioned tank into which air with an aeration intensity of 0.1 to ¹ m ³ / m ³ · h is blown, and wastewater treated in the MBR conditioned tank A water treatment method characterized by passing through an MBR reactor equipped with a separation membrane to be filtered and treating with a membrane separation module.   The water treatment method according to claim 5, wherein the carrier is disposed in the carrier treatment tank at a filling rate of 10 to 40% to treat the organic matter-containing treated waste water.   The water treatment method according to claim 5 or 6, wherein the dissolved oxygen in the MBR reactor is 2 to 4 mg / L and the amount of activated sludge is 5,000 to 20,000 mg / L.