JP2010036183A - Separating membrane module for treating wastewater containing oil, and method and device for treating wastewater containing oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separating membrane module suitable for filtration of wastewater containing oil. <P>SOLUTION: The separating membrane module for treating wastewater containing oil which separates water-insoluble oil contents from highly turbid and/or high-temperature wastewater containing oil is composed of an alkali resistant porous membrane selected from among PTFE (polytetrafluoroethylene), PSF (polysulfone) and PES (polyethersulfone), and uses a hollow fiber membrane of a tensile strength of 30 N or larger. A heat distortion temperature of the hollow fiber membrane and an end sealing material for the hollow fiber membrane is 100°C or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a separation membrane module for oil-containing wastewater treatment, an oil-containing wastewater treatment method using the same, and an oil-containing wastewater treatment device provided with a cleaning device for the separation membrane module. It separates well.

Conventionally, a treatment apparatus and a treatment method for removing water-insoluble oil from oil-containing wastewater containing water-insoluble oil are provided.
One type of oil-containing wastewater is oilfield associated water, and it is necessary to remove water-insoluble oil from the oilfield associated water. That is, when crude oil is mined, it is generally performed to inject seawater into the oil layer of the formation to increase the pressure of the water-insoluble oil and to secure the production amount. Since “oil field associated water”, which is wastewater used for crude oil mining, contains a large amount of water-insoluble oil, it is discarded after the water-insoluble oil is removed.
However, in recent years, regulations on water-insoluble oil content in wastewater have been tightened because it causes pollution of oceans, lakes and marshes, and in the most stringent countries and regions, water-insoluble water of less than 5 mg / L It is required to have the content of the essential oil.

  Usually, oilfield-associated water is subjected to gravity separation, solid separation with solid / liquid hydrocyclone, etc., followed by primary treatment with plate filters, liquid / liquid hydrocyclone, etc., and secondary treatment with coagulation sedimentation, pressurized flotation, etc. The tertiary treatment such as filtration and activated carbon treatment is performed, but the higher the primary, secondary, and tertiary treatment, the lower the treated water volume. There is a problem that disappears. As a result, in the treatment of oilfield-associated water discharged in large quantities, precise separation means cannot be applied in terms of the treatment speed, and as a result, practically treatment up to a water-insoluble oil content of 20 mg / L. Is said to be the limit. Also, processing costs are a problem.

  Therefore, it is considered promising to use a separation membrane module for the treatment of oil-containing wastewater. The separation membrane module has an advantage that a high amount of treated water can be secured and advanced water treatment can be performed. For example, in Japanese Patent Laid-Open No. 5-245472 (Patent Document 1), as shown in FIG. 9, the primary side S1 of a filtration device 102 provided with a ceramic separation membrane 101 having an oil-containing wastewater 100 having an average pore diameter smaller than oil particles. And a processing method for removing the treated water from the secondary side S2 of the ceramic separation membrane 101 and circulatingly supplying the concentrated water to the primary side of the filtration device until the concentrated water on the primary side reaches a predetermined concentration. ing.

JP-A-5-245472

  However, in the continuous treatment of oil-containing wastewater, the flow rate decreases due to the non-water-soluble oil adhering to the membrane surface of the separation membrane. Therefore, in order to decompose and remove the water-insoluble oil and continuously perform filtration, chemical cleaning using a strong alkaline agent such as sodium hydroxide is essential. However, in Patent Document 1 using a ceramic membrane as a separation membrane, there is a problem that chemical cleaning of the membrane surface cannot be sufficiently performed because durability to a high-concentration alkaline aqueous solution effective for cleaning a water-insoluble oil is not sufficient. . In addition, although the original physical strength is strong, as the cumulative frequency of chemical cleaning with alkali increases, the strength gradually begins to deteriorate, and even though it is a trace amount during physical cleaning such as backwashing and aeration, it is loaded. It is easy to generate troubles such as cracks. Furthermore, in patent document 1, since the separation membrane is made into a flat membrane, the amount of treated water is also limited and it is not suitable for continuous treatment of oil-containing wastewater discharged in large quantities.

  In addition, separation membranes made of polyvinylidene fluoride (PVDF), which are currently marketed as having excellent chemical resistance, are not durable against high-concentration alkaline aqueous solutions, like the above-mentioned ceramic membranes. There is a problem of insufficient physical strength.

In addition, in a device that separates heated oil-containing wastewater without lowering the temperature, the heat resistance and the low temperature when stopped and the high temperature when heated are repeated periodically, and the installation location of the oil-containing wastewater treatment device is For example, it is required to have resistance to a heat cycle in which a difference between a low temperature and a high temperature is 100 ° C. or more in a cold region.
However, resin filtration membranes that have been widely used for oil-water separation treatment have not been sufficiently heat resistant.
For example, in PP, PE, and PVDE, when heated oil-impregnated wastewater at 60 ° C. or higher is always supplied, the pore size changes due to softening, and PE tends to break.
Furthermore, as a conventionally used high-temperature oil-water separator, there is a case where it is formed of a ceramic powder sintered body, but in this case, there is a problem such as having heat resistance but an increase in weight, and Cracks are likely to occur due to thermal failure during temperature changes in the heat cycle.
In addition, a conventional apparatus having a ceramic separator has a large membrane element volume per membrane area, and thus requires a large installation area. There is a problem that the apparatus becomes heavy and large, and it is difficult to remove the filtration device for cleaning or investigation.

  The present invention has been made in view of the above problems, has high-performance filtration performance for oil-containing wastewater, and has durability against alkali that is effective for removing water-insoluble oil, and can be repeatedly regenerated. Furthermore, it is excellent in heat resistance and has a problem of maintaining high-performance filtration over a long period of time.

In order to solve the above-mentioned problem, as a first invention, a separation membrane module for oil-containing wastewater treatment that separates water-insoluble oil from high-turbidity or / and high-temperature oil-containing wastewater,
Using a hollow membrane having an alkali resistance selected from PTFE (polytetrafluoroethylene), PSF (polysulfone) and PES (polyethersulfone), and having a tensile strength of 30 N or more,
The hollow fiber membrane has a heat deformation temperature of 100 ° C. or higher,
The hollow fiber membrane end-sealing material is composed of a thermosetting resin having a heat deformation temperature of 100 ° C. or higher, or a heat-melting resin having a melting point of 1.5 times or more of the use temperature. Separation membrane module for wastewater treatment is provided.

  In the case of separating a water-insoluble oil component from high-turbidity, high-temperature oil-containing wastewater, the present inventors have selected a porous material selected from PTFE (polytetrafluoroethylene), PSF (polysulfone), and PES (polyethersulfone). Separation membrane modules using separation membrane hollow fibers or flat membranes have excellent water-insoluble oil removal performance and chemical resistance, especially alkali resistance and durability (usable period of normal filtration performance) ). As a result, while realizing high-performance filtration that can reduce the water-insoluble oil content to a low concentration of less than 5 mg / L and even less than 1 mg / L, the water-insoluble oil adhering to the membrane surface is chemically treated with an alkaline aqueous solution High performance filtration can be maintained for a long time because it can be repeatedly removed by dissolving and removing by washing.

PTFE (polytetrafluoroethylene), PSF (polysulfone), and PES (polyethersulfone) constituting the filtration membrane have a tensile strength of 30 N or more. Therefore, even if it repeatedly filters with a high concentration alkaline cleaning liquid, filtration performance and intensity | strength do not fall, and high performance filtration can be maintained over a long period of time. The tensile strength is preferably 50 N or more, and the upper limit is about 150 N.
The tensile strength was based on JIS K 7161, and the hollow fiber membrane itself was used as a test body. The tensile speed during the test was 100 mm / min, and the distance between the marked lines was 50 mm.

Further, PTFE (polytetrafluoroethylene), PSF (polysulfone), and PES (polyethersulfone) constituting the filtration membrane have a heat distortion temperature of 100 ° C. or higher. Specifically, PTFE is 121 ° C., PSF is 181 ° C., and PES is 210 ° C. The heat distortion temperature can be selected from the above membrane according to the temperature of the oil-containing wastewater to be treated.
Further, the end sealing material of the filtration membrane is also formed by using a resin having a heat deformation temperature of 100 ° C. or more similar to the formation material of the filtration membrane, or a fluororesin having a high heat resistance temperature in the case of a thermomeltable resin.
Thus, since the filtration membrane and the terminal sealing material are heat resistant, even when used as a filtration membrane for heated oil-containing wastewater, thermal deterioration can hardly occur.

  The oil-containing wastewater filtered by the filtration membrane is preferably used for oil-containing wastewater containing a water-insoluble oil component having a viscosity of 0.1 to 5.0 mPa · s at 20 ° C. The oil content is set to 10 mg / L to 0.1 mg / L. On the other hand, when the temperature of the waste water is a high temperature such as 100 ° C., the viscosity decreases, so that even a higher viscosity on a normal temperature basis can be filtered.

The viscosity at 20 ° C. of the oil-containing wastewater treated by the separation membrane module for oil-containing wastewater treatment of the present invention is 0.1 to 5.0 mPa · s because the viscosity of the contained water-insoluble oil is 5.0 mPa · s. If it exceeds, adhesion to the porous material will increase, irreversible membrane clogging will occur, and it will be difficult to ensure a sufficient amount of treated water. On the other hand, when the viscosity is less than 0.1 mPa · s, minute water-insoluble oil components are bonded to each other, and are not easily coarsened and formed into particles.
The water-insoluble oil contained in the oil-containing wastewater is not limited as long as it is in the above-mentioned viscosity range and is a water-insoluble substance that separates from water in water to form particles, but mainly petroleum-based carbonization such as naphtha. A hydrogen solvent is mentioned.
As described later, the oil-containing wastewater is separated from floating oil that can be separated by weight separation or the like, the water-insoluble oil content is adjusted to 10 to 2000 mg / L, and the water-insoluble oil content is from micron to submicron. It is preferable that the fine particles having an order particle diameter exist in water in the state of dispersed oil.
The viscosity of the water-insoluble oil is measured at 20 ° C. using a Hidehiro Seiki rheometer.

  Moreover, the oil-containing wastewater filtered by the filtration membrane is suitably used for oily wastewater having a high turbidity with a suspended substance concentration of 5 to 20000 mg / L, particularly 100 mmg / L or more.

  Moreover, it is used suitably also when the temperature of the said oil-containing wastewater filtered with the said filter membrane is 60-200 degreeC heated high temperature oil-containing wastewater. As described above, according to the temperature of the oil-containing wastewater, the filtration membrane and the terminal sealing material have a heat resistant temperature at which thermal deformation does not occur at the oil-containing wastewater temperature.

The hollow fiber membrane may be a single layer, or a porous multilayer or an asymmetric filtration membrane provided with a support layer and a filtration layer laminated on at least the outside of the support layer.
The average pore diameter of the filtration membrane is preferably 0.01-1 μm.

  The hollow fiber membrane has an inner diameter of 0.3 to 12 mm, an outer diameter of 0.8 to 14 mm, a bubble point of 50 to 400 kPa, a film thickness of 0.2 to 1 mm, a porosity of 30 to 90%, and a maximum allowable membrane. It is preferable that the differential pressure has a pressure resistance of 0.1 to 1.0 MPa.

As described above, isopropyl alcohol (IPA) was used as the bubble point in accordance with the method described in JIS K3832, and the hollow fiber membrane itself was used as a test specimen.
The porosity of the hollow fiber membrane was determined by the Archimedes method. At the time of calculation, the specific gravity of PTFE was 2.17.
In the case of the internal pressure filtration type, the maximum allowable transmembrane pressure is measured by applying water to the hollow fiber membrane surface to make the pressure surface non-porous, and then water in which 1500 mg / l iron hydroxide particles are dispersed. The internal pressure was loaded using as a medium. The pressure difference between the primary side and the secondary side of the membrane in a range where the size of the membrane before and after loading did not substantially change was measured every 10 kPa.
In the case of the external pressure filtration type, both ends of the hollow fiber membrane are fixed in a fixed state with a predetermined length, and in a state where the water permeated to the inside of the tube can be extracted from both ends, the same condition is applied to the outer surface of the tube with silicon grease. This was put in a sealed housing and water pressure was applied. At that time, after the tube released the load pressure, the maximum pressure when returning to the outer diameter before pressurization was measured every 10 kPa.

  As long as the hollow fiber membrane has alkali resistance and has the above-described bubble point, porosity, and maximum allowable inter-membrane differential pressure, it may be a single-layer or multi-layer hollow fiber membrane as described above. The hollow fiber membrane is particularly preferably made of porous expanded PTFE in terms of alkali resistance and excellent strength and durability.

The hollow fiber membrane preferably has a tensile strength of 30 N to 150 N and an IPA bubble point of 50 kPa to 400 kPa.
The IPA bubble point of the hollow fiber membrane is set to 50 kPa or more and 400 kPa or less. When the pressure is below 50 kPa, the pore diameter is too large and the liquid water-insoluble oil component passes through the pores of the porous membrane and contains a water-insoluble oil component. This is because it is impossible to obtain treated water whose amount is less than 5 mg / L. On the other hand, if it exceeds 400 kPa, it is difficult to ensure the amount of treated water because the pore size is too small, and the cleaning recoverability is poor because the permeability of the cleaning liquid used for chemical cleaning of the membrane is poor.
The lower limit value of the IPA bubble point is preferably 80 kPa or more, more preferably 100 kPa or more, and the upper limit value is preferably 380 kPa or less, more preferably 350 kPa or less.
In addition, the IPA bubble point was based on the method of JISK3832 using isopropyl alcohol (IPA), and used the hollow fiber membrane itself as a test body.

As the hollow fiber membrane, a porous multilayer hollow fiber membrane in which a porous expanded PTFE sheet as a filtration layer is wound around a porous expanded PTFE tube as a support layer is suitably used.
In the PTFE porous multilayer hollow fiber membrane, the filtration layer, which is the outer layer, has a sheet winding structure. The porous sheet is easy to perform both uniaxial stretching and biaxial stretching, and the shape and size of the pores on the surface. This is because such adjustments are easy and lamination with a thin film is easy. By using an extruded tube as the inner support layer, the moldability is good, the thickness is certain, the strength is sufficient, and the porosity is easily increased.

Both the support layer and the filtration layer may be extended in at least one axial direction, and can be extended in the axial direction, circumferential direction, radial direction, etc. of the tube, uniaxial in the axial direction, or axial direction and circumferential direction. 2 axes or the like. The draw ratio can be set as appropriate. In the case of an extruded tube, it is 50% to 700% in the axial direction, 5% to 100% in the circumferential direction, and 50% in the longitudinal direction in the case of a porous sheet. ˜1000%, and in the lateral direction 50% ˜2500%. In particular, when a porous stretched PTFE sheet is used, it is easy to stretch in the lateral direction. Therefore, when wound in a tube shape, the strength in the circumferential direction can be improved. Durability against pressure load due to cleaning can be improved.
Furthermore, since the support layer and the filtration layer made of a porous expanded PTFE tube are integrated and the respective pores communicate with each other in three dimensions, good permeability can be obtained.

  The average maximum length of each hole present in large numbers on the outer peripheral surface of the filtration layer is set to be smaller than the average maximum length of each hole surrounded by the fibrous skeleton present in large numbers in the support layer. Specifically, the average length of the pores in the filtration layer is preferably 1% to 30% of the average length of the pores in the support layer, and is preferably as small as possible. Thereby, the permeability | transmittance from the outer peripheral surface side to an inner peripheral surface side can be improved.

  In the outer surface of the filtration layer, the area occupation ratio of the pores with respect to the total surface area of the outer surface is preferably 30% to 90% as measured by image processing. Even if the maximum length of the holes is small, if the area occupation ratio of the holes is large to some extent, the flow rate is not reduced and the filtration performance can be improved efficiently.

  Specifically, the porosity of the filtration layer is preferably 30% to 80%, and the porosity of the support layer is preferably 50% to 85%. Thereby, the permeability | transmittance from the outer peripheral surface side of a hollow fiber membrane to an inner peripheral surface side can further be improved, maintaining a balance with intensity | strength. If the porosity is too small, the flow rate tends to decrease, and if the porosity is too large, the strength tends to decrease.

  The thickness of the filtration layer is preferably 5 μm to 100 μm. This is because if it is smaller than the above range, it is difficult to form a filtration layer, and if it is larger than the above range, it is difficult to expect an effect on the improvement of the filtration performance. The thickness of the support layer is preferably 0.1 mm to 5 mm. As a result, good strength can be obtained in any of the axial direction, radial direction, and circumferential direction, and durability against internal / external pressure, bending, and the like can be improved. In addition, it is preferable that the internal diameter of a support layer is 0.3 mm-12 mm.

The separation membrane module for oil-containing wastewater treatment of the present invention may be any of an external pressure type, an external pressure circulation type, an internal pressure type, an internal pressure circulation type, and an immersion type.
Specifically, it is a converging body provided with a plurality of the hollow fiber membranes, the converging body is accommodated in an outer cylinder,
The hollow fiber membrane is open at one end and closed at the other end, an introduction portion for introducing the oil-containing drainage into the outer cylinder, a filtered treatment liquid outlet portion communicating with the one end opening of the hollow fiber membrane, and not filtered In addition, an external pressure filtration type or an external pressure circulation filtration type in which a non-filtrate discharge portion is provided in communication with the outer cylinder.
Alternatively, the hollow fiber membrane is open at both ends, the introduction portion that introduces the oil-containing drainage into one end opening of the hollow fiber membrane, the discharge portion that discharges the non-filtrate that has not been filtered from the other end opening, and the outer cylinder It is an internal pressure filtration type or an internal pressure circulation filtration type equipped with a filtered treatment liquid lead-out portion communicating with the inside.
In the case of the immersion filtration type, a converging body provided with a plurality of the hollow fiber membranes, the converging body is disposed in the immersion tank of the oil-containing drainage, the hollow fiber membrane is open at one end, closed at the other end, It is assumed that a filtered treatment liquid outlet portion communicated with one end opening of the hollow fiber membrane is provided.

The hollow fiber membrane used as the external pressure filtration type or the external pressure circulation filtration type preferably has an outer diameter of 1 to 5 mm, an inner diameter of 0.5 to 4 mm, and a porosity of 30 to 90%.
The hollow fiber membrane used as the internal pressure filtration type or internal pressure circulation type preferably has an outer diameter of 1.3 to 20 mm, an inner diameter of 1 to 10 mm, and a porosity of 30 to 90%.

The bundle of hollow fiber membranes is provided with a large number of hollow fiber membranes of about 500 to 8000, which are excellent in chemical resistance and water-insoluble oil content filtration performance.
It is preferable that the hollow fiber membrane filling rate in the bundling body is about 20 to 60%, and the dimensions of the adjacent hollow fibers are widened so as to ensure a flow path for the oil-containing drainage.
When the separation membrane module is an external pressure filtration type that allows oil-containing wastewater to pass from the outside to the inside of the hollow fiber membrane, and an external pressure circulation type that recirculates unfiltered oil-containing wastewater to the separation membrane module, the flow of the liquid to be treated Thus, the dirt on the membrane surface of the hollow fiber membrane can be removed. Therefore, even if the water-insoluble oil content of the liquid to be treated and the concentration of suspended substances are high, filtration can be continued while suppressing contamination and clogging of the membrane surface. If filtration of the liquid is easy and clogging is difficult, it may be an external pressure type of total filtration that does not circulate the liquid to be treated.On the other hand, if the particles in the raw water are sufficiently larger than the pore size of the support layer, the hollow fiber membrane An internal pressure filtration that allows the treated water to permeate from the inside toward the outside, or an internal pressure circulation filtration type may be employed.

When the oil-containing wastewater to be treated has high turbidity and high temperature, it is preferable that the dimensional average value between the hollow fiber membranes in the convergent body is relatively wide as 0.5 mm to 5 mm.
Moreover, it is preferable that the filling rate of the said hollow fiber membrane with respect to the cross-sectional area of the said focusing body shall be 20%-60%.
Thus, by taking the separation dimension between the hollow fiber membranes relatively large, highly turbid oil-containing wastewater can be allowed to flow while suppressing the occurrence of clogging between the hollow fiber membranes.

In the present invention, since the hollow fiber membrane is washed with an alkaline aqueous solution as described later, other members such as a fixing material other than the hollow fiber membrane, a water collection header, a sealing resin, a liquid to be treated introduction pipe, and an outer cylinder are also included. It is desirable to form with an alkali resistant resin.
Specifically, for a sealing material that closes one end opening of the hollow fiber membrane and fixes it as a converging body, and a fixing material that fixes the other end opening of the hollow fiber membrane in an open state, epoxy resin, polyurethane resin, silicon resin (Rubber), thermosetting resins such as unsaturated polyester resins, or thermoplastic resins such as polyolefin resins and fluororesins are used.
The outer cylinder is preferably formed of a metal material such as stainless steel or an engineering plastic such as ABS resin, PVC, FRP, PTFE, PSF, PES, or PEEK.
The piping and its accessory parts are also made of stainless steel, PVC or the like.
In the case of a thermosetting resin, the member constituting the hollow fiber membrane module has a heat distortion temperature of 100 ° C. or higher, or in the case of a thermomeltable resin, the melting point is 1 of the use temperature. .5 times.

In the separation membrane module of the present invention, an air pipe for aeration is disposed below the converging body of the hollow fiber membranes arranged in the vertical direction, and the inside of the hollow fiber membrane is disposed from the treated liquid outlet. It is preferable to provide a reverse cleaning means for feeding the treated liquid with a reverse cleaning liquid under pressure.
By providing the air pipe for air diffusion, during normal filtration operation, bubbling of air for air diffusion is generated from the lower part of the separation membrane module or the pipe connected to the lower part of the module, and the hollow fiber membrane is swung. The fine particles adhering to the outer surface of the hollow fiber membrane can be screened off.
Further, the filtration performance can be maintained by periodically feeding the treated liquid as backwash water into the hollow fiber membrane of the separation membrane module and backwashing.

As a second invention, there is provided an oil-containing wastewater treatment method using the separation membrane module for oil-containing wastewater treatment. The oil-containing wastewater treatment method is:
An oil-containing wastewater having a water-insoluble oil content (n-hexane value) of 3 to 5000 mg / L, the IPA bubble point of the hollow fiber membrane is 50 kPa or more and less than 100 kPa, the transmembrane pressure difference is 50 kPa or less, and the IPA bubble point is The filtration conditions are 100 kPa or more and less than 150 kPa and the transmembrane differential pressure is 100 kPa or less, the IPA bubble point is 150 kPa or more and 400 kPa or less and the transmembrane differential pressure is 200 kPa or less. In the following cases, the water-insoluble oil content of the filtered water is less than 5 mg / L, and the water-insoluble oil content of the oil-containing wastewater is 3 mg / L or more and less than 10 mg / L, water-insoluble in the filtered water The oil content is less than 1 mg / L.

In this treatment method, by balancing the IPA bubble point of the hollow fiber membrane and the inter-membrane differential pressure, the water-insoluble oil component does not permeate through the pores of the porous membrane of the hollow fiber membrane, and it is efficiently removed from the oil-containing wastewater. The water-soluble oil is adjusted so that it can be removed.
In each condition of the IPA bubble point of the hollow fiber membrane, when the specified upper limit value of the transmembrane pressure difference is exceeded, water-insoluble oil easily penetrates into the pores of the porous membrane, and less than 5 mg / L or less than 1 mg / L This is not preferable because the water-insoluble oil content is difficult to obtain.
When the IPA bubble point of the hollow fiber membrane is 50 kPa or more and less than 100 kPa, the transmembrane pressure difference is preferably 50 kPa or less.
When the IPA bubble point is 100 kPa or more and less than 150 kPa, the transmembrane pressure difference is preferably 100 kPa or less.
When the IPA bubble point is 150 kPa or more and 400 kPa or less, the transmembrane pressure difference is preferably 200 kPa or less.
As for the lower limit value, it is desirable to maintain a lower pressure, but the differential pressure gradually increases as filtration continues. It is desirable to perform chemical cleaning of an alkaline aqueous solution or the like when the pressure reaches the above-described pressure.
For the transmembrane pressure difference, the raw water inlet pressure P1 closest to the separation membrane module in operation and the pressure P2 closest to the module permeated water outlet are measured, and (P1-P2) is calculated from these values.

In this treatment method, the oil-containing wastewater treated with the filtration membrane has a water-insoluble oil content (n-hexane value) of 3 to 2000 mg / L. If it exceeds 2000 mg / L, the content of water-insoluble oil is large. This is because the hollow fiber membrane is likely to be clogged, and it becomes difficult to secure the amount of treated water.
On the other hand, when it is less than 3 mg / L, when the water-insoluble oil component is dispersed as extremely small particles, minute particles are aggregated inside the membrane and are difficult to coarsen. This is because it cannot be removed.
The water-insoluble oil content of the oil-containing wastewater treated by this treatment method is preferably 10 to 2000 mg / L, particularly preferably 20 to 1000 mg / L.
The separation membrane module for oil-containing wastewater treatment according to the present invention has a low water-insoluble oil content, specifically, if it is an oil-containing wastewater of less than 30 mg / L, naturally 5 mg / L or less is less than 1 mg / L. Can be processed.
Water-insoluble oil content is obtained by the n-hexane value by the measuring method based on JISK0102 24.2.

  When the concentration of suspended solids (SS) measured in JIS K 0102 14.1 in the oil-containing wastewater is 5 to 2000 mg / L, the oil-containing wastewater usually contains suspended solids and is in a heterogeneous dispersion state. ing. In addition, the temperature of the oil-containing waste water to process is about 25-90 degreeC normally.

In the method for treating oil-containing wastewater of the present invention, when the water-insoluble oil content of the oil-containing wastewater is 3 to 200 mg / L and the concentration of suspended solids (SS) is 100 mg / L or less, the liquid to be treated It is preferable to carry out the total amount of the above by external pressure-type total filtration through a hollow fiber membrane.
When the water-insoluble oil content is more than 200 mg / L and not more than 2000 mg / L and the suspended solid (SS) is 100 to 20000 mg / L, the external pressure circulation type or the internal pressure circulation type is used. The cross flow method is preferable.
In particular, when the water-insoluble oil content is 1000 mg / L or more or the suspended substance is 500 mg / L or more, it is preferable to filter by circulation filtration.
As described above, the treatment can be efficiently performed by changing the treatment method according to the concentration of the water-insoluble oil and the suspended substance, and the amount of treated water can be ensured.

  The oil-containing wastewater treatment method described above is used when oil-containing wastewater after pretreatment of oilfield-associated water and reducing the water-insoluble oil content (n-hexane value) is subjected to microfiltration with the separation membrane module.

In addition, an oil-containing wastewater treatment method using the separation membrane module for oil-containing wastewater treatment,
When the oil-containing wastewater has a high oil content of 20 to 2000 mg / L, a suspended component content of 100 to 10,000 mg / L, and a high temperature of 60 to 200 ° C., the high-temperature oil-containing wastewater is filtered by the separation membrane module. In addition, an oil-containing wastewater treatment method in which the water-insoluble oil content in the treated water is 5 mg / L or less and the suspended component content is 0 to 1 mg / L is provided.

Furthermore, as a third invention, an oil-containing wastewater treatment apparatus provided with the separation membrane module for oil-containing wastewater treatment is provided.
The oil-containing wastewater treatment apparatus is equipped with a cleaning means for sending a cleaning liquid made of an alkaline aqueous solution to the surface of the hollow fiber membrane for removing the water-insoluble oil adhering to the surface of the hollow fiber membrane of the separation membrane module. It is characterized by that.

  The separation membrane module for oil-containing wastewater treatment used in the present invention forms a hollow fiber membrane with PTFE or the like and has extremely excellent alkali resistance, so that it is like 4% by mass sodium hydroxide aqueous solution (1 mol / L) Even if a cleaning solution of a high-concentration alkaline solution is fed, the hollow fiber membrane is not damaged and high-performance filtration performance can be maintained. Therefore, the captured water-insoluble oil adhering to the surface can be sufficiently dissolved and removed, and the porous membrane can be reused repeatedly.

The oil-containing wastewater treatment apparatus of the present invention communicates the oil-containing wastewater storage tank, the cleaning liquid storage tank of the cleaning means, the oil-containing wastewater storage tank and the cleaning liquid storage tank, and the introduction portion of the separation membrane module and is provided with a pump. An introduction pipe, and a circulation pipe that communicates the oil-containing drainage storage tank and the cleaning liquid storage tank with the non-treatment liquid discharge part of the separation membrane module,
The branch pipe of the introduction pipe and the branch pipe of the circulation pipe are preferably configured to communicate with the oil-containing drainage storage tank and the cleaning liquid storage tank, respectively.

As described above, the oil-containing wastewater is provided with a circulation pipe between the oil-containing wastewater storage tank and the separation membrane module, and the oil-containing wastewater of the liquid to be treated is supplied to the separation membrane module and filtered in a circulating manner. A circulation pipe is also provided between the cleaning liquid storage tank for storing the cleaning liquid made of the alkaline aqueous solution and the separation membrane module, and the cleaning liquid is circulated and supplied to the separation membrane module.
The circulation of the liquid to be treated and the circulation of the cleaning liquid are alternately performed to prevent a decrease in the filtration performance of the separation membrane module.

  The discharge pressure of the pump interposed in the introduction pipe is preferably 50 to 300 kPa. In addition, a switching valve is provided at the branch position of the branch pipe, and the liquid to be treated and the cleaning liquid are switched to the separation membrane module and fed.

As described above, the water-insoluble oil content exceeds 200 mg / L and is 2000 mg / L or less, and the suspended solid (SS) is 100 to 20000 mg by using a cross-flow method in which oil-containing wastewater is circulated to the separation membrane module. Even if the liquid to be treated is / L, it can be processed to less than 5 mg / L and less than 1 mg / L when the suspended solid (SS) and water-insoluble oil content are small.
Moreover, the transmembrane differential pressure of the hollow fiber membrane which has an IPA bubble point mentioned above can be made into the range mentioned above by supplying the discharge pressure of a pump with the said oil-containing waste water as 50-300 kPa.
Furthermore, by providing the washing means, the oil-containing drainage introduction pipe can be switched to the alkaline aqueous washing liquid introduction pipe, and the removal of the trapped water-insoluble oil on the membrane surface of the hollow fiber membrane can be performed periodically. Therefore, it is possible to easily regenerate the filtration membrane.

The oil-containing wastewater treatment apparatus of the present invention pretreats oil field-associated water to reduce the water-insoluble oil content, for example, the water-insoluble oil content (n-hexane value) is 10 to 2000 mg / L. Later, the oil-containing wastewater can be suitably used as a device for microfiltration.
Specifically, oil field-associated water is separated into coarse water-insoluble oil and oil-containing moisture by existing oil-water separation treatment means, and the separated oil-containing water is separated into water-insoluble oil and metal by means of electrocoagulation / levitation. It is used as an oil-containing wastewater treatment device that finely filters oil-containing wastewater that has been agglomerated and roughly removed as a liquid to be treated.

Since the raw water of the oilfield-associated water usually contains a large amount of oil such as floating oil and contains sludge, oil-containing wastewater after roughly removing water-insoluble oil by oil-water separation treatment means and electrocoagulation / flotation means in advance Used in the apparatus of the present invention for microfiltration. The oil content at this time is 10 to 100 mg / L.
With this configuration, since most of the water-insoluble oil such as floating oil has been removed in advance, clear treated water can be obtained while ensuring the amount of treated water. For example, it can be used as irrigation water.

In the hollow fiber membrane type separation membrane module used for the high-temperature oil-containing wastewater treatment, the dimensional average value between the hollow fiber membranes in the converging body is relatively wide as 0.5 mm to 5 mm, and the cross-sectional area of the converging body The filling rate of the hollow fiber membrane is preferably 20% to 60%.
Thus, when the dimension between the hollow fiber membranes is wide, leakage due to cracks or strain is likely to occur in the terminal sealing material. On the other hand, the present invention uses the following method as a manufacturing method for fixing a large number of hollow fiber membranes and a terminal sealing material for connecting and fixing at least one end thereof, and the terminal sealing material is cracked. It does not occur.

(When using thermosetting resin as sealing material)
For example, a heat-resistant epoxy resin (aromatic amine-based curing agent) having a heat deformation temperature of 120 ° C. or less is injected and filled in a container, preheated at 50 ° C. to 60 ° C., and then at room temperature for at least 3 hours, preferably 6 Pre-harden for more than an hour.
Next, heating is performed for 1 hour or more at a temperature not lower than the use temperature and not higher than 120 ° C. which is a heat distortion temperature (when used at 100 ° C., not lower than 100 ° C. and not higher than 120 ° C.).
Then, it is cooled for at least 6 hours with a temperature gradient of 1 ° C./min.
(When using a hot-melt resin as a sealing material)
The body of the terminal sealing material is heated in a state in which holes are made in advance according to the size of the hollow fiber membrane at a predetermined position of a rod molded into a terminal shape in advance, the hollow fiber membranes are inserted therein and arranged at predetermined intervals. Preheating is carried out until the temperature is equal to or higher than the melting point of the resin, followed by heating for 1 hour or more at the melting temperature, and then cooling is carried out with a temperature gradient of at least 6 hours and 1 ° C./min.

  Thus, after preheating, it hold | maintains for a predetermined time, after that, it heat-molds, and it takes the required time after heating and is cooled. In the hollow fiber membrane separation module manufactured by this method, even if the heat cycle is repeated at a temperature difference of about 100 ° C., the terminal sealing material itself and the cracking between the terminal sealing material and the hollow fiber are prevented. The present inventor has found through experiments that this can be done.

  As described above, when the separation membrane module of the present invention is used, it is possible to realize high performance filtration that can reduce the water-insoluble oil content of oil-containing wastewater to a low concentration of less than 5 mg / L and even less than 1 mg / L. .

  Moreover, according to the oil-containing wastewater treatment method of the present invention, when the oil-containing wastewater from the oil field or the heated high-temperature oil-containing wastewater is treated using the separation membrane module, the water-insoluble oil component does not permeate and is efficient. In addition, water-insoluble oil can be removed from the oil-containing wastewater, and a clean treated liquid can be obtained without reducing the amount of treated water.

  In addition, the oil-containing wastewater treatment apparatus of the present invention is equipped with a cleaning means for periodically cleaning the separation membrane module, and dissolves and removes the water-insoluble oil adhering to the membrane surface of the hollow fiber membrane by chemical cleaning with an alkaline aqueous solution. Therefore, high-performance filtration of oil-containing wastewater can be sustained over a long period of time.

  When used for oil-bearing wastewater treatment of oilfield-associated water, since most water-insoluble oils such as floating oil are removed in advance and then subjected to microfiltration with a separation membrane module, 5 mg / L while securing a high amount of treated water If the content of water-insoluble oil is less, a clear treated liquid of less than 1 mg / L can be obtained.

It is sectional drawing of the separation membrane module for oil-containing wastewater treatment of 1st Embodiment. It is a general view which shows the oil-containing wastewater treatment equipment provided with the separation membrane module of 1st Embodiment. (A) (B) is a schematic block diagram of a porous multilayer hollow fiber membrane. It is sectional drawing of the separation membrane module for oil-containing wastewater treatment of 2nd Embodiment. It is a general view which shows the oil-containing wastewater treatment equipment provided with the separation membrane module of 2nd Embodiment. It is sectional drawing of the separation membrane module for oil-containing wastewater treatment of 3rd Embodiment. It is a general view which shows the oil-containing wastewater treatment equipment provided with the separation membrane module of 3rd Embodiment. (A) (B) is sectional drawing of the separation membrane module of 4th Embodiment. It is a figure which shows a prior art example.

Embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a separation membrane module 1 for oil-containing wastewater treatment according to a first embodiment of the present invention.
The separation membrane module 1 of the first embodiment is used to precisely separate oil-containing wastewater obtained by subjecting oilfield-associated water to rough separation treatment in advance, and is not limited to the oilfield-associated water. It can be used for separating water-insoluble oil from oil-containing wastewater containing water-insoluble oil having a viscosity of 0.1 to 5.0 mPa · s, including domestic wastewater.
The separation membrane module 1 is configured to obtain treated water having a water-insoluble oil content of less than 1 mg / L from wastewater having a water-insoluble oil content of 3 to 2000 mg / L.

The separation membrane module 1 is used for an external pressure circulation filtration method (external pressure cross flow method) for circulating the oil-containing wastewater.
A converging body 3 in which a plurality of hollow fiber membranes 2 (3500 in this embodiment) are bundled is provided, the lower end of the converging body 3 is sealed with a sealing material 4, and the lower end opening of each hollow fiber membrane 2 is closed. ing. The upper end of the converging body 3 is fixed by a fixing material 5 with the upper end opening 2a of the hollow fiber membrane 2 being opened.
The converging body 3 is accommodated in the outer cylinder 6. An upper cap 7 is bonded and attached to the upper end of the outer cylinder 6, and a lead-out port 7 a that connects the inside of the top cap 7 with the hollow portion of each hollow fiber membrane 2 is provided. It is connected to the lead-out pipe 8.
A lower cap 9 is bonded and fixed to the lower end of the outer cylinder 6, an inlet 9a for the liquid to be treated is formed in the lower cap 9, and the inlet 9a for introducing the liquid to be processed is provided in the inlet 9a. Connected.
A space S is secured between the sealing material 4 at the lower end of the converging body 3 and the inner wall of the outer cylinder 6, and the oil-containing drainage introduced from the introduction port 9 a immediately flows into the converging body 3 in the outer cylinder 6. I am doing so.
Further, a non-processed liquid discharge port 11 is provided on the peripheral wall near the upper end of the outer cylinder 6, and the discharge port 11 communicates with the circulation pipe 12.

  Further, the air introduction pipe 14 for aeration is inserted from the lower peripheral wall of the outer cylinder 6 and is passed through the inside of the focusing body 3. As shown in FIG. 2, the air diffusion introduction pipe 14 is connected to the blower 15. A predetermined amount of air is introduced from the blower 15 to the aeration air introduction pipe 14 when necessary, and is diffused toward the hollow fiber membranes 2 of the focusing body 3. Thereby, the hollow fiber membrane 2 is vibrated and the solid content etc. which are contained in the oil-containing waste water adhering to the outer peripheral surface are screened off.

Further, the central portion of the upper fixing member 5 and the lower sealing member 4 is connected by a reinforcing rod 16. The reinforcing rod 16 is used to prevent the non-rigid hollow fiber membrane 2 from being lifted by the force of the water flow of the oil-containing drainage from the lower portion and to ensure verticality.
The outer cylinder 6, the upper cap 7, and the lower cap 9 are made of ABS resin, the fixing material 5 and the sealing material 4 are made of epoxy resin, and the connecting rod 16 is made of stainless steel or heat-resistant resin.

As shown in FIG. 3, the hollow fiber membrane 2 is a porous layer comprising a support layer made of a porous expanded PTFE tube 2b, and a filtration layer made of a porous membrane extended PTFE sheet 2c on the outer surface of the support layer. It consists of a multilayer hollow fiber membrane.
The hollow fiber membrane 2 has an inner diameter of 0.3 to 12 mm, an outer diameter of 0.8 to 14 mm, an IPA bubble point of 50 kPa to 400 kPa, a film thickness of 0.2 to 1 mm, a porosity of 50 to 90%, and a maximum. The pressure resistance of the allowable transmembrane pressure is 0.1 to 1.0 MPa, and the tensile strength is 30 to 150 N. These physical properties are measured by the same method as described above.

The hollow fiber membrane 2 composed of the porous multilayer hollow fiber membrane is formed by winding a porous expanded PTFE sheet 2c around the outer peripheral surface of a porous expanded PTFE tube 2b obtained by extrusion molding.
Specifically, after the outer peripheral surface of the porous expanded PTFE tube 2b is provided with irregularities by flame treatment or the like, the porous expanded PTFE sheet 2c is wound around the entire circumference without being displaced, and then a load is applied through a die or the like to be brought into close contact therewith. Thereafter, heat sintering is performed at a temperature equal to or higher than the melting point of PTFE, and both are fused and integrated.

The oil-containing wastewater treatment apparatus 20 provided with the separation membrane module 1 is configured as shown in FIG.
An oil-containing wastewater storage tank 21 into which oil-containing wastewater OL is continuously supplied from the pipe 19, a cleaning liquid storage tank 22 that stores a cleaning liquid of an alkaline aqueous solution (hereinafter abbreviated as an alkali cleaning liquid) AL, an oil-containing drainage storage tank 21, and a cleaning liquid storage tank 22. And the inlet 9a of the liquid to be treated of the separation membrane module 1, and the introduction pipe 10 provided with the pump 23 and the switching valve 24, the oil-containing drainage storage tank 21, the cleaning liquid storage tank 22, and the separation membrane module 1 and the circulation pipe 12 communicating with the discharge port 11 of the non-processed untreated liquid.

The introduction pipe 10 includes a switching valve 24 upstream of the pump 23, the pipe is branched by the switching valve 24, the branch pipe 10 </ b> A is connected to the oil-containing drainage storage tank 21, and the branch pipe 10 </ b> B is connected to the cleaning liquid storage tank 22. is doing. The introduction pipe 10 is connected to the backwash water discharge pipe 10 </ b> C via the switching valve 25 downstream of the pump 23.
The circulation pipe 12 serving as the cleaning liquid path is also branched, the branch pipe 12A is connected to the oil-containing drainage storage tank 21, and the branch pipe 12B is connected to the cleaning liquid storage tank 22. Further, a non-processed liquid that has not been filtered is returned to the oil-containing drainage storage tank 21 via the switching valve 29 at the branch position, and the alkali cleaning liquid is returned to the cleaning liquid storage tank 22 and circulated during alkali cleaning.

The discharge pressure of the pump 23 is 50 to 300 kPa, and the oil-containing wastewater OL and the alkaline cleaning liquid AL are pressurized and fed to the separation membrane module 1.
The discharge pressure of the pump 23 is 50 to 300 kPa, and is adjusted to the transmembrane differential pressure at the IPA bubble point of the hollow fiber membrane 2.
Thus, in this apparatus, the alkaline cleaning liquid AL and the oil-containing wastewater OL are periodically and alternately supplied to the separation membrane module 1, and the hollow fiber membrane 2 is periodically cleaned with the alkaline cleaning liquid AL.
As the alkaline cleaning liquid AL, a 0.5 to 20% by mass sodium hydroxide aqueous solution is used.

  A derivation pipe 8 for connecting the filtered treatment liquid outlet 7 a to take out the treatment liquid is connected to the treatment liquid storage tank 26. In addition, in order to use the processing liquid stored in the processing liquid storage tank 26 as backwashing water, a backwashing water pipe 28 provided with a backwashing pump 27 is connected to the processing liquid storage tank 26 and the outlet piping 8. Connected between.

Next, the operation of the oil-containing wastewater treatment apparatus provided with the separation membrane module 1 will be described.
The oil-containing wastewater OL continuously supplied to the oil-containing wastewater storage tank 21 is separated into water-insoluble oil and oil-containing water by the oil-water separation processing means of the oil field-associated water, and the separated oil-containing water is electrocoagulated / floating means. The water-insoluble oil content and the water content of the water-insoluble oil content (n-hexane value) after roughly removing the water and the metal content are about 1000 mg / L or less.

  The oil-containing wastewater OL is pressurized by the pump 23 from the oil-containing wastewater storage tank 21 and is introduced from the introduction pipe 10 into the inlet 9a at the lower end of the separation membrane module 1. The introduced oil-containing wastewater OL flows upward in the outer cylinder 6 and flows into the outer periphery of the hollow fiber membrane 2 in the focusing body 3 in the meantime. External pressure filtration is performed from the outer periphery of the hollow fiber membrane 2 to the hollow portion of the hollow fiber membrane 2.

The filtered processing liquid SL is stored in the processing liquid storage tank 26 from the hollow portion of the hollow fiber membrane 2 through the outlet outlet port 7a through the outlet pipe 8.
On the other hand, the non-treated liquid that has not been filtered is discharged from the discharge port 11 to the circulation pipe 12 and returned to the oil-containing drainage storage tank 21 or the cleaning liquid storage tank 22 via the branch pipe 12A.

As described above, when the oil-containing wastewater OL is filtered through the hollow fiber membrane 2, when the IPA bubble point is 50 kPa or more and less than 100 kPa as the hollow fiber membrane 2, the transmembrane pressure difference is adjusted to 50 kPa or less. Yes.
When an IPA bubble point of 100 kPa or more and less than 150 kPa is used, the transmembrane pressure difference is adjusted to 100 kPa or less.
When the IPA bubble point is 150 kPa or more and 200 kPa or less, the filtration condition is set to 200 kPa or less exceeding the transmembrane pressure difference.

  Thus, by balancing the IPA bubble point of the hollow fiber membrane 2 and the transmembrane pressure difference, the water-insoluble oil component does not permeate through the pores of the hollow fiber membrane 2, and the water-impervious drainage OL is effectively made water-insoluble. The treated water having a water-insoluble oil content of less than 1 mg / L can be obtained.

Instead of continuously supplying the oil-containing wastewater OL to the oil-containing wastewater storage tank 21, it may be supplied intermittently. In this case, the oil-containing wastewater OL is concentrated by repeating the circulation filtration a plurality of times, so that the filtration proceeds. When the concentration of the oil-containing wastewater OL reaches, for example, around 2000 mg / L, the liquid to be treated remaining in the oil-containing wastewater storage tank 21 may be discharged, and the oil-containing wastewater OL may be newly replaced.
Also, as another operation method, a certain amount of water-insoluble oil and solid content can be removed by discharging concentrated wastewater containing the same amount of the water-insoluble oil and solid content to be newly added to the system. You may filter continuously, maintaining.

The filtration operation of the oil-containing wastewater OL is performed for a certain time, and when the processing flow rate is reduced, the operation of the pump 23 is stopped and the switching valve 24 is switched to the alkali cleaning flow path. Thereafter, the pump 23 is restarted, and the alkaline cleaning liquid AL is introduced into the inlet 9 a of the separation membrane module 1 through the introduction pipe 10.
The alkaline cleaning liquid AL flows into the outer cylinder 6 and cleans and removes the trapped water-insoluble oil component deposited and deposited on the surface of the hollow fiber membrane 2. The alkaline cleaning liquid AL is discharged from the discharge port 11 to the circulation pipe 12 and is circulated from the circulation pipe 12 to the cleaning liquid storage tank 22.
In this manner, the filtration of the oil-containing wastewater OL and the cleaning with the alkaline cleaning liquid AL are periodically performed alternately.

Further, the processing liquid SL that has been filtered from the processing liquid storage tank 26 is periodically pumped from the outlet pipe 8 to the hollow portion of the hollow fiber membrane 2, and the hollow fiber membrane 2 is back-washed from the inside. The backwash water is discharged through the discharge pipe 10C by switching the switching valve 25.
Note that instead of the filtered treatment liquid, an alkaline washing liquid may be used as the back washing water and left for a short time, for example, about 1 hour.

  When treating oil-containing wastewater with a non-water-soluble oil content (n-hexane value) of 3 to 200 mg / L, especially oily wastewater with little adhesion to the membrane, supply oil-containing wastewater from the inlet 9a. The treated water from which the water-insoluble oil has been removed while flowing toward the upper end side of the bundling body 3 is circulated on the inner peripheral side of the hollow fiber membrane 2 and led out from the outlet 7a. It is preferable to use an external pressure filtration type that is led out to the pipe 8 and oil-filtered wastewater OL is totally filtered and is not circulated.

In the case of the external pressure filtration type, for example, the backwash pump 27 is operated once every 30 minutes, and the reverse pressure (internal pressure) is applied to the hollow fiber membrane 2 in the separation membrane module using the filtered treated water. Wipe away any solid matter that accumulates on the surface.
At that time, air is simultaneously fed from the blower 15 to vibrate the hollow fiber membrane 2 to wipe off the solid content. Thereafter, the liquid to be treated containing the solid content is drained from the lower part of the separation membrane module 1. The backwash pressure at this time is, for example, 200 kPa, and the time is 30 seconds. The amount of air is 50 L / min for 20 seconds. Thus, in the case of oil-containing wastewater with a lean water-insoluble oil content, it is preferable to filter the entire amount.

4 and 5 show an internal pressure circulation filtration type oil-containing wastewater treatment apparatus 30 of the second embodiment.
The oil-containing wastewater treatment device 30 is not used for oilfield associated water but for oily water separation of factory wastewater containing oil. In addition, you may use as an oil-containing wastewater treatment apparatus for oil field accompanying water similarly to 1st Embodiment.
The separation membrane module 31 shown in FIG. 4 has both ends of the hollow fiber membrane 32 as openings, the oil-containing wastewater OL of the liquid to be treated is passed through the hollow part of the hollow fiber membrane 32, and the filtration is performed from the inside to the outside of the hollow fiber membrane 32. Thus, an internal pressure circulation filtration type module that allows the filtered treatment liquid to permeate outside the hollow fiber membrane 32 is provided.

Specifically, the converging body 33 of the hollow fiber membrane 32 having the openings at both ends is accommodated in the outer cylinder 6. The upper and lower sides of the converging body 33 are fixed by fixing members 34 and 35 with both ends of the hollow fiber membrane 32 being opened. An upper cap 37 provided with a non-filtered non-processing liquid discharge port 37a is bonded and fixed to the fixing member 34 at the upper end, and the upper cap 37 and the circulation pipe 12 are connected to the discharge port 37a.
The fixing member 35 at the lower end is closely fixed to the inner peripheral surface of the outer cylinder 6 and is fixed to the lower cap 36. The lower cap 36 is provided with an inlet 36a for the liquid to be treated made of oil-containing waste water, and the inlet 36a is It is connected to the introduction pipe 10.
Further, a filtered processing liquid outlet 6c is provided on the peripheral wall near the upper end of the outer cylinder 6, and the outlet 6c is connected to a outlet pipe 8 for extracting the processing liquid.

As shown in FIG. 5, the oil-containing wastewater treatment apparatus 30 having the internal pressure circulation filtration type separation membrane module 31 has an introduction pipe 10 connected to the introduction port 36a of the separation membrane module 31 as in the first embodiment. The oil-containing drainage storage tank 21 and the cleaning liquid storage tank 22 are connected via the pump 23, the switching valve 24, and the branch pipes 10A and 10B.
Similarly to the first embodiment, the circulation pipe 12 connected to the discharge port 37a of the separation membrane module 31 connects the branch pipes 12A and 12B to the oil-containing drainage storage tank 21 and the cleaning liquid storage tank 22, respectively.
Similarly to the first embodiment, the outlet piping 8 connected to the filtered processing liquid outlet 6 c is also connected to the processing liquid storage tank 26, and reversely passed through the processing liquid storage tank 26 and the backwash pump 27. The washing pipe 28 is connected to the outlet pipe 8. The back washing pump 27 is intermittently operated to introduce the treatment liquid into the outer cylinder 6 as a back washing liquid and spray it toward the outer peripheral surface of the hollow fiber membrane 32 to perform the back washing. Yes.
Further, the air diffuser introduction pipe 14 connected to the blower 15 is inserted into the pipe 10 close to the inlet 36a of the separation membrane module 31, and the air diffuser is supplied to the inside of each hollow fiber membrane 32. Yes.

  The hollow fiber membrane 32 of the second embodiment is composed of a single-layer tube made of porous expanded PTFE, as in FIG. 3 of the first embodiment. The porous hollow fiber membrane 32 has an inner diameter of 1 to 12 mm, an outer diameter of 1.6 to 14 mm, an IPA bubble point of 50 kPa to 400 kPa, a film thickness of 0.2 to 1 mm, a porosity of 50 to 90%, and a maximum allowable transmembrane pressure. It has a pressure resistance of 0.1 to 1.0 MPa. These physical properties are measured by the same method as described above.

The separation membrane module 31 circulates oil-containing wastewater OL having a water-insoluble oil content (n-hexane value) of 1000 to 2000 mg / L. The internal pressure circulation filtration system is different from the external pressure circulation filtration system of the first embodiment.
The oil-containing wastewater OL is introduced into the hollow fiber membrane 32 from the introduction port 36a and flows toward the upper end side of the converging body 33, as indicated by an arrow in the figure. The treated water that has been filtered through the hollow fiber membrane 32 in this distribution process and from which the water-insoluble oil has been removed passes through the outer peripheral side of the hollow fiber membrane 32, and leads out the treatment liquid provided on the peripheral wall of the outer cylinder 6. 6c is led out to the lead-out piping 8.
Further, the non-filtered non-processed liquid containing water-insoluble oil and solid particles is discharged from the discharge port 37 a provided in the upper cap 37 to the circulation pipe 12.
In the case of the internal pressure circulation method, the flow rate increases because the flow passage cross-sectional area flowing through the separation membrane module 31 is small even at the same circulation flow rate, and the separation effect of the solid content and water-insoluble oil content deposited on the surface of the hollow fiber membrane 32 is large. Therefore, it is particularly effective in a region where the water-insoluble oil concentration is large.

In the second embodiment, an oil-containing wastewater OL having a high concentration of a water-insoluble oil content is used as a liquid to be treated, and a treated liquid having a water-insoluble oil content of less than 5 mg / L can be obtained by a single filtration. .
Since other configurations and effects are the same as those of the first embodiment, members having the same functions and functions are denoted by the same reference numerals and description thereof is omitted.

6 and 7 show the separation membrane module 40 and the oil-containing wastewater treatment apparatus 60 of the third embodiment.
The separation membrane module 40 for oil-containing wastewater treatment immerses and arranges the converging body 42 of the hollow fiber membrane 41 in the immersion tank 50 storing the oil-containing wastewater OL, and sucks the oil-containing wastewater OL from the inside of the hollow fiber membrane 41. The module is an immersion type that allows oil-containing wastewater OL to permeate from the outside to the inside of the hollow fiber membrane 41.

As in the first embodiment, the converging body 42 of the hollow fiber membrane 41 is fixed with the fixing material 5 with the upper end opening of the hollow fiber membrane being opened, and the fixing material 5 is fixed to the upper cap 7. The upper cap 7 is connected to an outlet piping 8 for taking out the filtered processing liquid.
Similarly to the first embodiment, the lower end of the converging body 42 is also fixed by the sealing material 4 with the lower end opening of the hollow fiber membrane 41 closed. The outer peripheral portions of the fixing member 5 at the upper end and the sealing member 4 at the lower end are connected by a connecting rod 43 to hold and reinforce the focusing body 42 in the vertical direction.
The sealing material 4 at the lower end and the lower end of the connecting rod 43 are fixed to the skirt material 46. A diffuser port of the diffuser air introduction pipe 14 connected to the blower 15 is disposed below the skirt member 46. During filtration operation, air is constantly diffused from below, and upward bubbling is caused in the oil-containing wastewater OL in the immersion tank 50 by bubbling.

As shown in FIG. 7, the lead-out piping 8 for taking out the processing liquid is connected to the processing liquid storage tank 26 as in the first embodiment. A backwash pipe 28 provided with a backwash pump 27 is connected to the treatment liquid storage tank 26, and the pipe 28 is connected to the outlet pipe 8.
Further, the cleaning liquid storage tank 22 storing the alkaline cleaning liquid AL is introduced into the immersion tank 50 through the pipe 45, and after removing the oil-containing wastewater OL in the immersion tank 50, the alkaline cleaning liquid AL is introduced into the immersion tank 50. Thus, the focusing body 42 is immersed and cleaned for a required time.

Similar to the hollow fiber membrane 2 of the first embodiment, the hollow fiber membrane 41 of the third embodiment includes a support layer made of a porous stretched PTFE tube, and a porous membrane stretched PTFE on the outer surface of the support layer. It is set as the porous multilayer hollow fiber membrane provided with the filtration layer which consists of a sheet | seat.
The hollow fiber membrane 41 has an inner diameter of 0.3 to 2.0 mm, an outer diameter of 0.8 to 3.0 mm, and a maximum outer diameter of 20 mm when a support such as a cylindrical net is used on the inner surface.
The IPA bubble point has a pressure resistance of 50 kPa to 400 kPa, a film thickness of 0.2 to 1 mm, a porosity of 50 to 90%, and a maximum allowable transmembrane pressure (external pressure) of 0.1 MPa. These physical properties are measured by the same method as described above. The immersion type of the third embodiment is used for treating oil-containing wastewater OL having a water-insoluble oil content (n-hexane value) of 10 to 200 mg / L.

Oil-containing wastewater OL is supplied to the immersion tank 50 via the pipe 19. The supply of the oil-containing wastewater OL from the pipe 19 to the immersion tank 50 is performed intermittently.
Specifically, when the oil-containing wastewater OL in the immersion tank 50 is filtered and the water-insoluble oil content of the oil-containing wastewater OL that has not been filtered becomes 200 mg / L, the oil-containing wastewater OL is discharged out of the system from the immersion tank 50, New oil-containing wastewater OL is supplied into the immersion tank 50.
Alternatively, when the water content of the water-insoluble oil content is 100 mg / L, the oil-contained waste water OL having a dilute concentration is introduced into the immersion tank 50, and a predetermined amount of water content of the water-insoluble oil content of 100 mg / L is accumulated in the immersion tank 50. It is discharged out of the system in a short time.
For example, when 1000 liters of oil-containing wastewater is added and the water-insoluble oil content of the oil-containing wastewater is 5000 mg, only 50 liters are discharged as the water-insoluble oil content in the immersion tank 50 is 100 mg / L. It operates so that this balance may be maintained, and it is continuing, maintaining the water-insoluble oil content in the immersion tank 50 constant.

In the immersion type of the third embodiment, during the filtration operation, air is constantly sprayed from the air diffuser air insertion pipe 14 to the lower part of the focusing body 42, and the oil-containing wastewater OL in the immersion tank 50 is raised by the bubbling. While the flow is generated and the hollow fiber membrane 41 is vibrated, the water-insoluble oil component and the solid component are attached to the membrane surface of the hollow fiber membrane 41, and the attached solid component and the water-insoluble oil component are sieved off.
Further, as described above, the oil-containing wastewater is periodically discharged from the immersion tank 50 to the outside of the system, and after discharge, the alkaline cleaning liquid AL is supplied to the immersion tank 50 through the pipe 45, and the focusing body 42 is immersed in the alkaline cleaning liquid AL. Cleaning is performed. Further, the back washing pump 27 is driven to introduce the filtered processing liquid SL into the hollow fiber membrane 41 as a back washing liquid, and the hollow fiber membrane 41 is back washed.

By periodically washing as described above, it is possible to remove the trapped water-insoluble oil adhering to the membrane surface of the hollow fiber membrane 42 with the alkaline washing liquid AL and almost completely restore the filtration performance of the hollow fiber membrane. it can.
As a result, a treated liquid having a water-insoluble oil content of less than 5 mg / L, and further 1 mg / L can be obtained continuously over a long period of time without reducing the amount of treated water. Are better. The treated liquid thus obtained can be used as irrigation water, for example.
The oil-containing wastewater treatment device of the third embodiment can be used as an oil-containing wastewater treatment device in any field, such as for oil field accompanying water and factory wastewater containing oil.

8A and 8B show a high-temperature oil-containing wastewater treatment apparatus according to the fourth embodiment.
The oil-containing wastewater to be treated has a temperature of 60 to 200 ° C., an oil content of 20 to 2000 mg / L, a suspended component content of 100 to 10,000 mg / L, and a filtration device (oil-containing wastewater treatment device) provided with a separation membrane module 62 ) 63 is microfiltered.

  The separation membrane module 62 of the filtration device 63 uses a hollow fiber membrane 2 made of an expanded PTFE porous tube similar to that of the first embodiment, and the overall configuration of the filtration device 63 is as shown in FIG. Are also provided with the same reference numerals and the description thereof is omitted.

Each hollow fiber membrane 2 of the separation membrane module 62 may be either a single layer or a multi-layer, and each hollow fiber membrane 2 has an outer diameter of 1 to 5 mm and an inner diameter of 0 when used as the external pressure filtration type or the external pressure circulation filtration type. 0.5 to 4 mm, and the porosity of the filtration surface is 30 to 90%, preferably 40 to 80%.
When the internal pressure filtration type or the internal pressure circulation type is used, the outer diameter is 1.3 to 20 mm, the inner diameter is 1 to 10 mm, and the porosity of the filtration surface is 30 to 90%, preferably 40 to 80%.

  Further, the tensile strength of the hollow fiber membrane 2 is 30 N or more and 150 N or less, and the IPA bubble point is 50 kPa or more and 400 kPa or less.

As shown in FIG. 8 (B), the separation membrane module 62 provided with the converging body 3 obtained by concentrating a large number of hollow fiber membranes 2 circulates a relatively high viscosity oil-containing wastewater. The filling area of the hollow fiber membrane is 20 to 60% with respect to the area.
In this embodiment, the separation membrane module 62 has a sealing material 4 at the lower end of the converging body 3 in which the hollow fiber membranes 2 are bundled and a fixing material 5 (upper end sealing material) that seals by opening an upper end opening, having a diameter of 100 to 500 mm. And the spacing between adjacent hollow fiber membranes 2 (separation dimension of the hollow fiber membrane) is widened as 0.5 mm to 5 mm for the widely used hollow fiber membrane type separation membrane module, and the flow path of the oil-containing drainage Is secured.

The sealing material 4 at the lower end and the fixing material 5 (upper end sealing material) that seals by opening the upper end opening, the outer cylinder 6 that houses the focusing body 3, the upper cap 7, and the lower cap 9 have a heat deformation temperature of 120. It is made of a heat resistant resin at a temperature of ℃ or higher.
As the heat resistant resin, aromatic amine curable epoxy resin, PFA, PEF, PVDE, or the like is used. The connecting rod 16 is SUS. The outer cylinder may also be made of metal such as SUS.
The O-ring interposed between the upper and lower caps 7 and 9 and the outer cylinder 6 has heat resistance as Teflon, Viton, or a combination of metal and Teflon.

In the filtration device 63 provided with the hollow fiber membrane module 62, the heated oil-containing wastewater is subjected to filtration treatment in the same manner as in the first embodiment, and the treatment liquid that has passed through the separation membrane module 62 is treated with water-insoluble water in the treated water. The essential oil content is 5 mg / L or less, and the suspended component content is 0 to 1 mg / L.
Further, the hollow fiber membrane module 62 is subjected to a cleaning process in the same manner as in the first embodiment.

Since the separation membrane module 62 has a heat cycle with a large temperature difference between the stop time and the operation time, the separation distance of the hollow fiber membrane 2 is increased, so that cracks are easily generated in the upper and lower sealing materials. .
Therefore, the separation membrane module 62 of this embodiment is manufactured by the following method.

A plurality of hollow fiber membranes 2 are arranged at predetermined intervals in the container. At that time, as described above, the separation distance L1 between the hollow fiber membranes is set to be relatively wide as 0.5 to 5 mm.
The container is filled with a thermosetting resin having a heat distortion temperature of 120 ° C. or higher, preheated at 50 ° C., and then preliminarily cured by holding at room temperature for at least 6 hours.
Next, heating is performed for 1 hour or more under a temperature condition of 100 ° C. or higher during use and a heat distortion temperature of 120 ° C. or lower.
Then, it cools with a temperature gradient of at least 6 hours and 1 ° C./min.

  As described above, by producing the separation membrane module, it is possible to reduce or prevent the occurrence of cracks even when used in the heat cycle at the time of use, and the sealing material even if the separation distance between the hollow fiber membranes is widened The present inventor has confirmed through experiments that no cracks occur.

In the heated oil-containing wastewater treatment apparatus having the above-described configuration, since the hollow fiber membrane is formed of heat-resistant PEFE, it can be prevented from softening and changing the pore diameter, and it can be broken by repeated thermal shock. And cracks can be prevented. Furthermore, it is possible to make it difficult for cracks to occur between the hollow fiber membrane and the upper and lower sealing materials or in the sealing material itself.
Furthermore, it can be reduced in weight and size as compared with conventionally used processing apparatuses, and does not take up installation space. In addition, there is also an advantage that the separation membrane module can be easily taken out at the time of cleaning or investigation of the membrane state.

The present invention is not limited to the above-described embodiment, and as the hollow fiber membrane, a multilayer or asymmetric hollow fiber membrane composed of a support layer and a filtration layer may be used, or a single layer composed of one uniform porous tube. It is good. Moreover, it is good also as a converging body which bent the hollow fiber membrane in U shape, opened both sides of the upper end, and was fixed with the fixing material. Furthermore, it is preferable that the cleaning liquid is cleaned using an alkaline cleaning liquid, but only back cleaning using the treated liquid may be performed.
Various forms within the scope of the present invention are included.

  As the liquid to be treated used in the present invention, it is suitably used for the treatment of oilfield associated water described in the embodiment, but in addition to the treatment of industrial wastewater containing cutting oil, etc., food wastewater containing water-insoluble oil, etc. Can also be applied.

DESCRIPTION OF SYMBOLS 1, 31, 40, 62 Separation membrane module for oil-containing wastewater treatment 20, 30, 60 Oil-containing wastewater treatment device 2, 32, 41 Hollow fiber membrane 3, 33, 42 Converging body 6 Outer cylinder 8 Leading pipe 10 Introducing pipe 12 Pipe for Circulation 21 Oil-Containing Drainage Reservoir 22 Cleaning Liquid Reservoir 23 Pump 26 Treatment Liquid Reservoir OL Oil-Containing Drain AL Alkaline Cleaning Liquid

Claims (21)

A separation membrane module for oil-containing wastewater treatment that separates water-insoluble oil from high-turbidity or / and high-temperature oil-containing wastewater,
Using a hollow membrane having an alkali resistance selected from PTFE (polytetrafluoroethylene), PSF (polysulfone) and PES (polyethersulfone), and having a tensile strength of 30 N or more,
The hollow fiber membrane has a heat deformation temperature of 100 ° C. or higher,
The hollow fiber membrane end-sealing material is composed of a thermosetting resin having a heat deformation temperature of 100 ° C. or higher, or a heat-melting resin having a melting point of 1.5 times or more of the use temperature. Separation membrane module for wastewater treatment.   The oil-containing wastewater filtered by the filtration membrane is an oil-containing wastewater containing 3 mg / L to 2000 mg / L of a water-insoluble oil having a viscosity of 0.1 to 5.0 mPa · s at 20 ° C., and depending on the filtration membrane. The separation membrane module for oil-containing wastewater treatment according to claim 1, wherein the oil content of the filtered water is 0.1 mg / L to 10 mg / L.   The separation membrane module for oil-containing wastewater treatment according to claim 1 or 2, wherein the oil-containing wastewater filtered by the filtration membrane has a suspended solid concentration of 5 to 10,000 mg / L.   The separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 3, wherein the temperature of the oil-containing wastewater filtered by the filtration membrane is 60 to 200 ° C.   5. The hollow fiber membrane according to any one of claims 1 to 4, wherein the hollow fiber membrane is a single layer, or a porous multilayer or an asymmetric filtration membrane having a support layer and a filtration layer laminated at least outside the support layer. The separation membrane module for oil-containing wastewater treatment as described.   The separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 5, wherein the hollow fiber membrane has a tensile strength of 30N to 150N and an IPA bubble point of 50kPa to 400kPa.   The separation membrane for oil-containing wastewater treatment according to any one of claims 1 to 6, wherein the hollow fiber membrane is a porous multilayer hollow fiber membrane in which a porous expanded PTFE sheet is wound around a porous expanded PTFE tube. module.   The separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 7, wherein an average pore diameter of the hollow fiber membrane is 0.01 to 1 µm. A focusing body comprising a plurality of the hollow fiber membranes, the focusing body is accommodated in an outer cylinder,
The hollow fiber membrane is open at one end and closed at the other end, an introduction portion for introducing the oil-containing drainage into the outer cylinder, a filtered treatment liquid outlet portion communicating with the one end opening of the hollow fiber membrane, and not filtered The non-filtrate discharge part is connected to the outer cylinder and is an external pressure filtration type or an external pressure circulation filtration type,
Alternatively, the hollow fiber membrane is open at both ends, the introduction portion for introducing the oil-containing drainage into one end opening of the hollow fiber membrane, the discharge portion for leading the non-filtrated liquid not filtered from the other end opening, and the outer cylinder An internal pressure filtration type or an internal pressure circulation filtration type equipped with an outlet for the filtered treatment liquid communicating with the inside,
Alternatively, a converging body provided with a plurality of the hollow fiber membranes, the converging body being disposed in the immersion tank of the oil-containing wastewater, the hollow fiber membrane being open at one end and the other end being closed, and being open at one end of the hollow fiber membrane The separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 8, wherein the separation membrane module is a submerged filtration type including a filtered treatment liquid lead-out portion in communication with the oil treatment waste water. The hollow fiber membrane used as the external pressure filtration type or external pressure circulation filtration type has an outer diameter of 1 to 5 mm, an inner diameter of 0.5 to 4 mm, and a porosity of 30 to 90%.
The separation for oil-impregnated wastewater treatment according to claim 9, wherein the hollow fiber membrane used as the internal pressure filtration type or the internal pressure circulation type has an outer diameter of 1.3 to 20 mm, an inner diameter of 1 to 10 mm, and a porosity of 30 to 90%. Membrane module.   The separation membrane module for oil-containing wastewater treatment according to claim 9 or 10, wherein a dimensional average value between hollow fiber membranes in the converging body is 0.5 mm to 5 mm.   The separation membrane module for oil-containing wastewater treatment according to any one of claims 9 to 11, wherein a filling rate of the hollow fiber membrane with respect to a cross-sectional area of the converging body is 20% to 60%.   An air pipe for aeration is arranged at the lower part of the concentrator of the hollow fiber membrane arranged in the vertical direction or the pipe connected to the lower part of the outer cylinder of the separation membrane module, and from the treated liquid outlet The separation membrane module for oil-containing wastewater treatment according to any one of claims 9 to 12, further comprising reverse cleaning means for pressure-feeding the treated liquid as a reverse cleaning liquid inside the hollow fiber membrane. An oil-containing wastewater treatment method using the separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 13,
An oil-containing wastewater having a water-insoluble oil content (n-hexane value) of 3 to 2000 mg / L, the IPA bubble point of the hollow fiber membrane is 50 kPa or more and less than 100 kPa, the transmembrane pressure difference is 50 kPa or less, and the IPA bubble point is The filtration conditions are 100 kPa or more and less than 150 kPa and the transmembrane differential pressure is 100 kPa or less, the IPA bubble point is 150 kPa or more and 400 kPa or less and the transmembrane differential pressure is 200 kPa or less. In the following cases, the water-insoluble oil content of the filtered water is less than 5 mg / L, and the water-insoluble oil content of the oil-containing wastewater is 3 mg / L or more and less than 10 mg / L, water-insoluble in the filtered water An oil-containing wastewater treatment method in which the oil content is less than 1 mg / L. An oil-containing wastewater treatment method using the separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 13,
When the water-insoluble oil content of the oil-containing wastewater is 3 to 200 mg / L and the concentration of the suspended solid (SS) is 100 mg / L or less, the total amount of liquid to be treated is externally filtered through the hollow fiber membrane. When the water-insoluble oil content of the oil-containing wastewater exceeds 200 mg / L and is 2000 mg / L or less, or the suspended solid (SS) is 100 to 20000 mg / L, the internal pressure circulation type or external pressure circulation for circulating the liquid to be treated An oil-containing wastewater treatment method characterized by being filtered by a formula. An oil-containing wastewater treatment method using the separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 13,
An oil-containing wastewater treatment method in which oil-containing wastewater after pretreatment of oilfield-associated water and reducing the water-insoluble oil content (n-hexane value) is precisely filtered by the separation membrane module.   The oil-containing wastewater treatment method according to claim 16, wherein the pretreatment is pressure levitation treatment, electrocoagulation / electrolevitation treatment, and the n-hexane value after the treatment is 10 to 100 mg / L. An oil-containing wastewater treatment method using the separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 13,
The oil-containing wastewater is heated at a temperature of 20-2000 mg / L, the content of suspended components is 100-10000 mg / L, 60-200 ° C., and the oil-containing wastewater is separated. An oil-containing wastewater treatment method in which a water-insoluble oil content in the treated water is 5 mg / L or less and a suspended component content is 0 to 1 mg / L by filtration with a membrane module. A filtration device comprising the separation membrane module for oil-containing wastewater treatment according to any one of claims 1 to 13,
An oil-containing wastewater treatment apparatus comprising cleaning means for feeding a cleaning liquid made of an alkaline aqueous solution to the surface of the hollow fiber membrane for removing the water-insoluble oil adhering to the surface of the hollow fiber membrane of the separation membrane module. An oil-containing drainage storage tank, a cleaning liquid storage tank of the cleaning means, the oil-containing drainage storage tank and the cleaning liquid storage tank, and an introduction pipe having a pump interposed therebetween, and an introduction pipe connected to the separation membrane module, and the oil-containing drainage A circulation pipe that communicates the storage tank and the cleaning liquid storage tank and the discharge portion of the non-treatment liquid of the separation membrane module;
20. The oil-containing wastewater treatment apparatus according to claim 19, wherein a branch pipe for the introduction pipe and a branch pipe for the circulation pipe are communicated with the oil-containing wastewater storage tank and the cleaning liquid storage tank, respectively.   21. The oil-containing wastewater treatment apparatus according to claim 20, wherein a discharge pressure of the pump provided in the introduction pipe is 50 to 300 kPa, and a switching valve is provided in a branch position of the branch pipe.

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