JP4896782B2 - Membrane filtration system and membrane cleaning method - Google Patents

Description

The present invention relates to a membrane filtration system suitable for water treatment of fresh water such as river water, ground water, lake water, sewage such as rainwater storage, industrial wastewater, sewage, seawater such as ballast water, and the like . It relates to a cleaning method .

  Conventionally, in the water treatment field, raw water (fresh water such as river water, groundwater, lake water, etc., rainwater storage, industrial wastewater, sewage such as sewage, seawater such as ballast water) is filtered, and used for domestic water, industrial water, and agriculture. As a method for obtaining water, for example, membranes such as microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, and reverse osmosis membranes are used.

  The membrane has a high separation performance with respect to solids such as microorganisms, algae, and clay in the raw water, and its application in the water treatment field is expanding. In recent years, it is common to use a hydrophilic material as the material of the membrane. Even when a hydrophobic material is used, it has been studied to improve the filtration performance by hydrophilizing the membrane surface with a sulfuric acid solution of potassium dichromate or the like (see, for example, Patent Document 1).

  However, when the membrane is continuously passed through the raw water, solid content in the raw water is deposited on the membrane surface or inside, and the filtration resistance may increase, and the filtration performance may deteriorate. In this case, in order to obtain the necessary amount of treated water, the membrane differential pressure increases, and there is a risk that the energy required for operation of the membrane filtration system will increase.

  Therefore, in such a membrane filtration system, when the membrane shows a predetermined differential pressure increase at a preset period or when the membrane shows a predetermined differential pressure increase, the filtered treated water is allowed to flow from the treated water side or compressed air from the raw water side or treated water side. Physical remediation such as sending a film to remove reversible material from the surface of the film and internal deposits.

  On the other hand, since deposits that are difficult to remove by such physical cleaning gradually accumulate on the membrane surface and inside, the membrane filtration treatment is stopped when the membrane differential pressure exceeds the preset upper limit value. Chemical cleaning is used to remove deposits that could not be removed by physical cleaning.

And even if chemical cleaning, deposits such as the membrane surface and inside can not be removed, and recovery of membrane differential pressure is not recognized, or when the usage period of the membrane exceeds a certain period, The membrane is replaced when it is judged that it has reached the end of its life.
Japanese Patent Laid-Open No. 5-23553

  In such a membrane filtration system, a membrane in which a polymer material that reversibly expands / shrinks at a predetermined temperature is added to the outer surface side of the membrane substrate in order to suppress the cost required for chemical cleaning and membrane replacement. In addition, it has been studied to wash the deposits on the membrane surface or inside the membrane with warm water.

  However, in such a membrane filtration system, when the temperature of the water to be treated is significantly lower than the lower critical solution temperature (LCST) of the polymer material, the cost required to obtain hot water has increased. . In addition, when the temperature of the water to be treated is higher than the LCST of the polymer material, the effect of filtration and washing due to the action of the polymer material that reversibly expands / contracts may not be sufficiently obtained.

The present invention has been made in view of the above, and membrane filtration that can perform effective filtration and washing while reducing the cost required to obtain hot water used for membrane washing and reducing the total running cost It is an object to provide a system and a method for cleaning a membrane .

In order to achieve the above object, a membrane filtration system according to the present invention is responsive to changes in temperature and pH on a membrane substrate having a plurality of through holes and an outer surface side of the membrane substrate. a membrane module becomes integrated by filling a membrane having a pore size adjusting material added with the reversibly expandable / contracting polymeric material container, the supplied raw water to membrane filtration, it is discharged as treated water Te Cleaning means for supplying the raw water or the treated water into the membrane module and cleaning the membrane; and changing the temperature and pH around the pore size adjusting material to adjust the pore size during membrane filtration. Condition variable means for expanding the material and contracting the hole diameter adjusting material during the cleaning, the condition variable means for adjusting the temperature around the hole diameter adjusting material during the cleaning. Or the treated water Part, characterized in that circulating through the periphery of the membrane module while controlling the temperature.

Also, membrane filtration system of the present invention, as described in claim 2, in a membrane filtration system according to claim 1, detecting means for detecting at least one of the temperature or pH of the surrounding of the pore size adjusting agent And a control means for controlling the condition variable means so that at least one of the ambient temperature and pH of the pore diameter adjusting material becomes a predetermined target value according to the detection result by the detection means. It is characterized by.

The method of cleaning membranes according to the present invention, as described in claim 3, a film substrate having a plurality of through holes, reversibly in response to changes in temperature and pH on the outer surface of the membrane substrate expansion / A membrane having a pore size adjusting material to which a shrinking polymer material is added is filled in a container and integrated, and the membrane in a membrane filtration system comprising a membrane module that membrane-filters the supplied raw water and discharges it as treated water. A cleaning method comprising: changing a pH of a part of the raw water or the treated water; supplying the raw water or the treated water having a changed pH into the membrane module; and supplying the raw water or the treated water. A step of circulating a part of the pore diameter adjusting material by circulating a part of the membrane module while adjusting the temperature, and shrinking the pore diameter adjusting material; Characterized in that it comprises a step of discharging the supplied water.

Further, the method of cleaning membranes according to the present invention, as described in claim 4, in the membrane cleaning method according to claim 3, for detecting at least one of the temperature or pH of the surrounding of the pore size adjusting agent And a step of adjusting so that at least one of the ambient temperature and pH of the pore diameter adjusting material becomes a predetermined target value according to a detection result in the detecting step. .

According to the onset bright, using membranes obtained by adding reversible expansion / contraction polymeric material in response to physical or chemical environmental changes on the outer surface of the membrane substrate, combined with temperature control and chemical additives Thus, effective filtration and cleaning can be performed, and the cost required to obtain hot water used for cleaning the membrane can be reduced, and the total running cost can be reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(First embodiment)
First, the membrane used in the membrane filtration system according to the first embodiment of the present invention will be described. FIG. 1 is a cross-sectional configuration diagram showing a membrane used in the membrane filtration system according to the first embodiment of the present invention.

  As shown in FIG. 1, a film 10 used in the first embodiment is made of a polymer material such as polyethylene, and has a film substrate 1 having a plurality of through holes (film holes), and physical or chemical environmental changes. And a pore diameter adjusting material 2 to which a polymer material that expands / shrinks reversibly in response to the above is added. The pore diameter adjusting material 2 is added to the outer surface side of the membrane substrate 1. An example of the pore diameter adjusting material 2 is N-isopropylacrylamide.

  The membrane substrate 1 and the pore diameter adjusting material 2 are composed of carbon atoms, hydrogen atoms, oxygen atoms, and nitrogen atoms, and reversibly expand / contract in response to physical or chemical environmental changes as shown in FIG. To do.

  As shown in Fig. 1 (a), raw water containing solute 3 such as solids (fresh water such as river water, groundwater, lake water, sewage such as rainwater storage, industrial wastewater, sewage, seawater such as ballast water, etc.) By the sieving action of the membrane 10 having pores of 100 μm or less, a substance larger than the pores is captured by the membrane surface and the pore diameter adjusting material 2. Examples of the solute 3 contained in the raw water include inorganic substances such as silica colloid, bentonite and clay, bacteria such as Escherichia coli, protozoa such as Cryptosporidium and Giardia, and plankton. These solutes 3 have a carboxyl group, an amino group, a hydroxyl group, and the like.

  As described above, N-isopropylacrylamide is responsive to temperature and pH.

  Filtration and backwashing are performed by utilizing the change in expansion / contraction of the polymer chain of N-isopropylacrylamide corresponding to such a physical or chemical environmental change. That is, using the membrane 10 shown in FIG. 1, raw water is passed from the outer surface side of the membrane to the inner surface side to capture the solute 3 in the raw water on the outer surface side. Then, when backwashing from the inner surface side to the outer surface side of the membrane 10, by performing at least one of temperature adjustment and pH adjustment on the raw water staying on the outer surface side, N-isopropyl is obtained. Shrink acrylamide polymer chains. At this time, as shown in FIG. 1B, the pore diameter of the membrane hole expands (opens) as the polymer chain contracts.

  N-isopropylacrylamide expands due to strong interaction between the amide group and water below the lower critical solution temperature (LCST) at which the property changes, but as the temperature rises, the amide group and water Shrink as hydrogen bonds become unstable.

  The pore size adjusting material 2 of N-isopropylacrylamide has an amide group in its side chain, and expands at about 32 ° C. or less, which is LCST, as shown in FIG. However, as shown in FIG. 2 and FIG. 3B, when it exceeds about 25 ° C., it dehydrates and contracts, and at around 40 ° C., the contraction is also almost saturated.

  Further, the pore size adjusting material 2 of N-isopropylacrylamide shrinks as the pH becomes an acidic region, and expands as it becomes a neutral or alkaline region. Therefore, when the pH of the cleaning water is adjusted, the pore diameter adjusting material 2 is preferably contracted by setting the pH of the cleaning water to an acidic region.

  In addition, the membrane differential pressure at this time is usually about 5 to 30 kPa, but according to the “Guidelines for Introducing Membrane Filtration Facilities in Small-Scale Waterworks” of the Water Technology Research Center, “Maximum 150 kPa for microfiltration membranes, In the case of an ultrafiltration membrane, it is said that it is 300 kPa or less.

  As described above, in the conventional film, the solute 3 having a carboxyl group, an amino group, a hydroxyl group, and the like adheres to the film surface by hydrogen bonding, so that it is difficult to remove by simply backwashing. For this reason, at the time of backwashing, by performing at least one of temperature adjustment and pH adjustment of the washing water, it is possible to weaken the bonding force between the solid content 3 and the film surface to facilitate peeling.

The polymer material of the pore diameter adjusting material 2 is (1) a polymer obtained by copolymerizing acrylic acid, 2-carboxyisopropylacrylamide, 3-carboxy-n-propylacrylamide with N-isopropylacrylamide, and (2) N -Vinyl isobutyric acid amide-based polymer, (3) poly-N-alkylacrylamide derivative, (4) copolymer of polyacrylamide derivative represented by polyisopropylacrylamide and polyvinyl derivative, (5) N-vinylisobutyric acid amide, etc. A copolymer of N-vinyl C _3-9 acylamide of N-vinyl C _1-3 acylamide such as N-vinylacetamide, (6) polyacrylamide derivative and poly-N-vinylacylamide, (7) N A polymer of monomers composed of isopropylacrylamide, and N-vinyl A monomer polymer composed of ruisobutyric acid amide can be considered. The pore diameter adjusting material 2 is not limited to these polymers, and may be any polymer material that reversibly expands / contracts in response to physical or chemical environmental changes.

  Next, the membrane module used in the membrane filtration system according to the first embodiment of the present invention will be described. FIG. 4 shows an example of a membrane module used in the membrane filtration system according to the first embodiment.

  As shown in FIG. 4, a large number of films are loaded in the cylindrical casing in the cylindrical casing. As the membrane loaded in this membrane module, the membrane 10 shown in FIG. 1 is used. Raw water is filtered while passing through the membrane, and separated into membrane filtrate (treated water) and concentrated water (drainage).

  In this case, raw water containing solute 3 such as solids (see Fig. 1) (fresh water such as river water, groundwater, lake water, sewage such as rainwater storage, industrial wastewater, sewage, seawater such as ballast water, etc.) A substance larger than the pores is trapped by the membrane surface and the pore diameter adjusting material 2 by the sieving action of the membrane having pores of 100 μm or less. When integrated into a container, the raw water flows along the membrane surface, the treated water flows in a direction perpendicular to the raw water, and a part of the raw water circulates, or the whole amount is filtered without circulating the raw water. It becomes possible to perform filtration by the total amount filtration method.

  Next, the membrane filtration system according to the first embodiment of the present invention will be described. FIG. 5 is a block diagram showing a membrane filtration system according to the first embodiment of the present invention.

  A membrane filtration system 100 shown in FIG. 5 uses the membrane module 13 having the configuration shown in FIG. 4, and includes a raw water tank 11 for temporarily storing raw water guided by a water pump not shown, and raw water in the raw water tank 11. Is supplied to the membrane module 13, a membrane module 13 for membrane filtering raw water guided by the raw water pump 12, and a treated water tank 14 for storing treated water membrane-filtered by the membrane module 13. . In addition, a cleaning water tank 15 that introduces and stores a part of the raw water stored in the raw water tank 11 as cleaning water, a heater 16 that heats the raw water stored in the cleaning water tank 15 to a predetermined temperature, and the raw water tank 11 and a chemical injection facility 17 for injecting chemicals for pH adjustment into the washing water tank 15. Further, a compressor 18 for supplying pressurized air at the time of cleaning is also provided. In addition, V1-V10 in the figure shows the valve | bulb provided in each piping.

  FIG. 6 is a diagram for explaining filtration processing in the membrane filtration system according to the present invention, and FIG. 7 is a diagram for explaining an example of physical cleaning in the membrane filtration system according to the present invention. 6 and FIG. 7 show only the portions necessary for explaining the filtration process and physical cleaning in the membrane filtration system 100 shown in FIG.

  In FIG. 6, the raw water is led to the raw water tank 11 by a water pump not shown. The raw water is introduced into the membrane module 13 by pressurization of the raw water pump 12, and the treated water that has permeated through the membrane module 13 is stored in the treated water tank 14.

  Normal cleaning is performed according to the following procedure described with reference to FIG.

(1) Back pressure process The valve V9 is opened and pressurized air is supplied from the treated water side of the membrane by the compressor 18 to apply pressure to the inner surface side of the membrane.

(2) Backflow process Valves V1 and V4 on the raw water side of the membrane and a valve V6 on the upper side of the membrane module 13 are opened, and the treated water on the upper side (secondary side) of the membrane module 13 is pushed out to the raw water side and discharged. The discharged water may be returned to the raw water tank 11 in order to improve the recovery rate.

(3) Air scrubbing step While maintaining the pressure, the valve V8 is opened and pressurized air is supplied from the raw water side lower portion of the membrane module 13 by the compressor 18 for a certain time, and the membrane module 13 is swung by the air.

(4) Drain process After air scrubbing for a certain period of time, the valve V10 and the valve V5 below the membrane module 13 are opened to discharge the water in the membrane module 13. At this time, the adhering substance can be discharged more effectively when the compressed air is kept flowing from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(5) Raw Water Rinsing Valves V1 and V4 and valve V6 above the membrane module 13 are opened, the raw water pump 12 is activated, and the membrane module 13 is rinsed. At this time, rinsing can be performed more effectively if the compressed air is allowed to flow from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(6) Filtration The valve V6 at the top of the membrane module 13 is closed and the filtration side valve V7 is opened to resume filtration. If the compressor 18 is moving in the previous process, it stops.

  In the membrane filtration system 100 shown in FIG. 5, normal cleaning is performed according to the above procedure, and cleaning is performed at a predetermined frequency using at least one of temperature adjustment and pH adjustment by chemical addition according to the following procedure.

(1) Drain process The valve V10 and the valve V5 below the membrane module 13 are opened, and the water in the membrane module 13 is discharged. The discharged water may be returned to the raw water tank 11 in order to improve the recovery rate.

(2) Hot water process The chemical injection facility 17 adds chemicals to the raw water introduced into the raw water tank 11 or the washing water tank 15, and the heater 16 adjusts the temperature to the LCST of the polymer material of the pore diameter adjusting material 2 in the washing water tank 15 A portion of the raw water is circulated by the raw water pump 12 through the raw water side in the membrane module 13. In this manner, the pore diameter adjusting material 2 added to the outer surface of the membrane is reversibly contracted by at least one of temperature adjustment of raw water in the membrane module 13 and addition of chemicals to the raw water.

(3) Back pressure / back flow process The valve V9 is opened, and pressurized air from the compressor 18 is supplied from the treated water side of the membrane module 13 to apply pressure to the inner surface side of the membrane. Further, the valve V6 at the upper part of the membrane module 13 is opened, and the treated water at the upper part (secondary side) of the membrane module 13 is pushed out to the raw water circulation line.

(4) Air scrubbing step While maintaining the pressure, the valve V8 is opened and pressurized air is supplied from the raw water side lower portion of the membrane module 13 by the compressor 18 for a certain period of time, and the membrane module 13 is swung by the air.

(5) Drain process After performing air scrubbing for a certain period of time, the valve V10 and the valve V5 below the membrane module 13 are opened to discharge the water in the membrane module 13. At this time, the adhering substance can be discharged more effectively when the compressed air is kept flowing from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(6) Raw Water Rinsing Valves V1 and V4 and the valve V6 in the circulation line above the membrane module 13 are opened, the raw water pump 12 is activated, and the membrane module 13 is rinsed. The rinse water may be discharged out of the system similarly to the raw water rinsing step in the procedure described with reference to FIG. At this time, rinsing can be performed more effectively if the compressed air is allowed to flow from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(7) Filtration The valve V6 at the top of the membrane module 13 is closed, and the filtration side valve V7 is opened to resume filtration. If the compressor 18 is moving in the previous process, it stops.

  According to the first embodiment, by changing the condition of at least one of the temperature and pH of the raw water flowing into the membrane module 13, the expansion / reversibility in response to a physical or chemical environmental change / Depending on the properties of the shrinking polymer material, the solute 3 captured by the pore diameter adjusting material 2 on the outer surface of the membrane in the membrane module 13 can be effectively discharged out of the system.

(Modification of the first embodiment)
FIG. 8 is a configuration diagram showing a modification of the membrane filtration system according to the first embodiment of the present invention.

  The membrane filtration system 110 shown in FIG. 8 is different from the membrane filtration system 100 shown in FIG. 5 in that the sensor 19 for detecting the temperature, pH value, etc. of the raw water in the washing water tank 15 and the temperature inside the membrane module 13 are used. In this configuration, a sensor 20 for detecting the pH value and the like, and a monitoring control device 21 for controlling the temperature, the pH value and the like according to the values detected by the sensors 19 and 20 are added.

  The washing procedure in the membrane filtration system 110 is the same as that in the membrane filtration system 100. However, the monitoring controller 21 in the hot water process determines the inside of the membrane module 13 (of the pore diameter adjusting material) according to the detection results of the sensors 19 and 20. The heater 16 and the chemical injection equipment 17 are controlled so that at least one of the ambient temperature and pH becomes a predetermined target value. Here, it is preferable to control at least one of the temperature and the chemical addition amount so that the sum of the cost for changing the temperature and the cost required for the chemical addition is minimized.

  According to the modification of the first embodiment, the cost and chemicals for changing the temperature are controlled by controlling at least one of the temperature and the chemical addition amount according to the temperature and pH of the raw water flowing into the membrane module 13. While suppressing the cost required for the addition, it is possible to perform effective filtration and washing taking advantage of the characteristics of the polymer material that reversibly expands / contracts in response to physical or chemical environmental changes.

(Second Embodiment)
FIG. 9 is a block diagram showing a membrane filtration system according to the second embodiment of the present invention.

  The membrane filtration system 120 shown in FIG. 9 stores water in an outer cylinder 13a provided to cover the periphery of the membrane module 13 via a predetermined space and the washing water tank 15 with respect to the membrane filtration system 100 shown in FIG. The raw water pump 22 is supplied to the outer cylinder 13 a and circulated through the outside of the membrane module 13. The chemical injection equipment 17 injects chemicals into the raw water tank 11 but does not inject into the cleaning water tank 15.

  The filtration process and normal washing in the membrane filtration system 120 are performed in the same procedure as the membrane filtration system 100 described above. Then, cleaning is performed at a predetermined frequency using at least one of temperature adjustment and pH adjustment by chemical addition according to the following procedure.

(1) Drain process The valve V10 and the valve V5 below the membrane module 13 are opened, and the water in the membrane module 13 is discharged. The discharged water may be returned to the raw water tank 11 in order to improve the recovery rate.

(2) Hot water process The raw | natural water which added the chemical | medical agent to the raw | natural water tank 11 is supplied in the membrane module 13. FIG. Further, a part of the raw water in the washing water tank 15 whose temperature is adjusted to the LCST of the polymer material of the pore diameter adjusting material 2 by the heater 16 is supplied to the outer cylinder 13a by the raw water pump 22 and circulated through the outside of the membrane module 13. Let In this manner, the pore diameter adjusting material 2 added to the outer surface of the membrane is reversibly contracted by at least one of temperature adjustment of raw water in the membrane module 13 and addition of chemicals to the raw water. The circulation may be stopped when the temperature in the membrane module 13 can ensure LCST or higher in the following steps.

(3) Back pressure / back flow process The valve V9 is opened, and pressurized air from the compressor 18 is supplied from the treated water side of the membrane module 13 to apply pressure to the inner surface side of the membrane. Further, the valve V6 at the upper part of the membrane module 13 is opened, and the treated water at the upper part (secondary side) of the membrane module 13 is pushed out to the raw water circulation line.

(4) Air scrubbing step While maintaining the pressure, the valve V8 is opened and pressurized air is supplied from the raw water side lower portion of the membrane module 13 by the compressor 18 for a certain period of time, and the membrane module 13 is swung by the air.

(5) Drain process After performing air scrubbing for a certain period of time, the valve V10 and the valve V5 below the membrane module 13 are opened to discharge the water in the membrane module 13. At this time, the adhering substance can be discharged more effectively when the compressed air is kept flowing from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(6) Raw Water Rinsing Valves V1 and V4 and the valve V6 in the circulation line above the membrane module 13 are opened, the raw water pump 12 is activated, and the membrane module 13 is rinsed. The rinsed water may be returned to the washing water tank 15 in order to improve the recovery rate. At this time, rinsing can be performed more effectively if the compressed air is allowed to flow from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(7) Filtration The valve V6 at the top of the membrane module 13 is closed, and the filtration side valve V7 is opened to resume filtration. If the compressor 18 is moving in the previous process, it stops.

  According to the second embodiment, the condition of at least one of the temperature and pH of the raw water in the membrane module 13 is changed to reversibly expand / contract in response to a physical or chemical environmental change. Depending on the characteristics of the polymer material to be used, the solute 3 captured by the pore diameter adjusting material 2 on the outer surface of the membrane in the membrane module 13 can be effectively discharged out of the system.

  In addition, since the temperature inside the membrane module 13 is adjusted by circulating the raw water heated by the heater 16 through the outside of the membrane module 13, the heated raw water can be used effectively and the amount of the heated raw water is saved. can do.

  In the above description, the temperature inside the membrane module 13 is adjusted by circulating the temperature-adjusted raw water through the outside of the membrane module 13, but any method can be used to adjust the temperature of the membrane module 13 itself from the outside. It is not limited to the temperature adjustment method described above.

(Modification of the second embodiment)
FIG. 10 is a configuration diagram showing a modification of the membrane filtration system according to the second embodiment of the present invention.

  The membrane filtration system 130 shown in FIG. 10 circulates outside the membrane module 13 and the sensor 19 for detecting the temperature, pH value, etc. of the raw water in the washing water tank 15 with respect to the membrane filtration system 120 shown in FIG. In this configuration, a sensor 23 for detecting the temperature, pH value, and the like of the raw water to be performed and a monitoring control device 21 for controlling the temperature, pH value, etc. according to the values detected by the sensors 19, 23 are added.

  The washing procedure in the membrane filtration system 130 is the same as that in the membrane filtration system 120. However, the monitoring controller 21 determines the temperature or pH in the membrane module 13 based on the detection results of the sensors 19 and 23 in the hot water process. The heater 16 and the chemical injection facility 17 are controlled so that at least one of them reaches a predetermined target value. Here, it is preferable to control at least one of the temperature and the chemical addition amount so that the sum of the cost for changing the temperature and the cost required for the chemical addition is minimized.

  According to the modification of the second embodiment, the cost of changing the temperature and the chemical addition are controlled by controlling at least one of the temperature and the chemical addition amount according to the temperature and pH of the raw water in the membrane module 13. Therefore, it is possible to perform effective filtration and washing taking advantage of the characteristics of a polymer material that reversibly expands / contracts in response to a physical or chemical environmental change.

(Third embodiment)
FIG. 11 is a block diagram showing a membrane filtration system according to the third embodiment of the present invention.

  The membrane filtration system 140 shown in FIG. 11 omits the cleaning water tank 15, the heater 16, and the chemical injection equipment 17 from the membrane filtration system 100 shown in FIG. 5, and the treated water stored in the treated water tank 14. A washing water tank 24 that introduces and stores a part of the water as washing water, a heater 25 that heats treated water in the washing water tank 24, and a chemical injection facility 26 that injects chemicals for pH adjustment into the washing water tank 24, In this configuration, a backwash water pump 27 for supplying wash water in the wash water tank 24 to the membrane module 13 from the treated water side is added.

  FIG. 12 is a diagram for explaining another example of physical cleaning in the membrane filtration system according to the present invention. In FIG. 12, only the part necessary for explaining the physical cleaning in the membrane filtration system 140 shown in FIG. 11 is shown.

  The filtration process in the membrane filtration system 140 is performed according to the same procedure as that of the membrane filtration system 100 described above, but normal cleaning is performed according to the following procedure described with reference to FIG.

(1) Back-pressure water process The treated water in the treated water tank 14 is caused to flow backward from the treated water side of the membrane module 13 by the backwash water pump 27 and from the raw water side below the membrane module 13 or from the raw water side above the membrane module 13. Discharge. At this time, the compressed air is supplied from the raw water side below the membrane module 13 by the compressor 18 to swing the membrane module 13.

(2) Raw Water Rinsing The valves V1 and V4 and the valve V6 above the membrane module 13 are opened, the raw water pump 12 is activated, and the membrane module 13 is rinsed. At this time, rinsing can be performed more effectively if the compressed air is allowed to flow from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(3) Filtration The valve V6 at the top of the membrane module 13 is closed and the filtration side valve V7 is opened to resume filtration. At this time, if the compressor 18 is moving, it stops.

  In the membrane filtration system 140 shown in FIG. 11, normal cleaning is performed by at least one of the procedure described with reference to FIG. 12 or the procedure described with reference to FIG. 7. According to the procedure, washing is performed using at least one of temperature adjustment and pH adjustment by chemical addition.

(1) Back-pressure water process Chemicals are added to the treated water introduced into the washing water tank 24 by the chemical injection facility 26, and backflowed from the treated water side of the membrane by the backwash water pump 27. Or, it is discharged from the raw water side above the membrane module 13. At this time, the compressed air is supplied from the raw water side below the membrane module 13 by the compressor 18 to swing the membrane module 13.

  At the same time, treated water in the washing water tank 24 whose temperature is adjusted to the LCST of the polymer material of the pore diameter adjusting material 2 by the heater 25 is supplied from the treated water side of the membrane module 13 by the backwash water pump 27. In this manner, the pore diameter adjusting material 2 added to the outer surface of the membrane is reversibly contracted by at least one of temperature adjustment in the membrane module 13 and chemical addition to the treated water.

(2) Raw Water Rinsing The valves V1 and V4 and the valve V6 above the membrane module 13 are opened, the raw water pump 12 is activated, and the membrane module 13 is rinsed. At this time, the rinsing water may be circulated to the raw water tank 11. At this time, rinsing can be performed more effectively if the compressed air is allowed to flow from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(3) Filtration The valve V6 at the top of the membrane module 13 is closed and the filtration side valve V7 is opened to resume filtration. At this time, if the compressor 18 is moving, it stops.

  According to the third embodiment, by changing the condition of at least one of temperature and pH in the membrane module 13, a high level that reversibly expands / contracts in response to a physical or chemical environmental change. Depending on the characteristics of the molecular material, the solute 3 captured by the pore diameter adjusting material 2 on the outer surface of the membrane in the membrane module 13 can be effectively discharged out of the system.

(Modification of the third embodiment)
FIG. 13: is a block diagram which shows the modification of the membrane filtration system which concerns on the 3rd Embodiment of this invention.

  The membrane filtration system 150 shown in FIG. 13 is different from the membrane filtration system 140 shown in FIG. 11 in that the sensor 20 for detecting the temperature, pH value, etc. of the membrane module 13 and the treated water in the washing water tank 24 are used. In this configuration, a sensor 28 for detecting temperature, pH value, and the like, and a monitoring control device 21 for controlling temperature, pH value, etc. according to the values detected by the sensors 20, 28 are added.

  The washing procedure in the membrane filtration system 150 is the same as that in the membrane filtration system 140. However, the monitoring control device 21 detects the temperature in the membrane module 13 or the temperature in the reverse pressure water process based on the detection results of the sensors 20 and 28. The heater 25 and the chemical injection facility 26 are controlled so that at least one of the pH becomes a predetermined target value. Here, it is preferable to control at least one of the temperature and the chemical addition amount so that the sum of the cost for changing the temperature and the cost required for the chemical addition is minimized.

  According to the modification of the third embodiment, the cost of changing the temperature by controlling at least one of the temperature and the chemical addition amount according to the temperature and pH of the treated water flowing into the membrane module 13. In addition, it is possible to perform effective filtration and washing taking advantage of the characteristics of a polymer material that reversibly expands / contracts in response to a physical or chemical environmental change, while suppressing the cost required for chemical addition.

(Fourth embodiment)
FIG. 14 is a block diagram showing a membrane filtration system according to the fourth embodiment of the present invention.

  The membrane filtration system 160 shown in FIG. 14 has the same configuration as the membrane filtration system 140 shown in FIG.

  The filtration process and normal cleaning in the membrane filtration system 160 are performed in the same procedure as the membrane filtration system 140 described above. Then, cleaning is performed at a predetermined frequency using at least one of temperature adjustment and pH adjustment by chemical addition according to the following procedure.

(1) Drain process The valve V10 and the valve V5 below the membrane module 13 are opened, and the water in the membrane module 13 is discharged. The discharged water may be returned to the raw water tank 11 in order to improve the recovery rate.

(2) Warm water process A chemical is added to the treated water introduced into the washing water tank 24 by the chemical injection equipment 26, and the treated water in the washing water tank 24 whose temperature is adjusted to the LCST of the polymer material of the pore diameter adjusting material 2 by the heater 25 is used. The backwash water pump 27 supplies from the treated water side of the membrane module 13, and the membrane module 13 is filled with warm water to which a chemical is added. In order to improve the recovery rate, the hot water to which the chemical discharged from the membrane module 13 is added may be returned to the raw water tank 11. In this manner, the pore diameter adjusting material 2 added to the outer surface of the membrane is reversibly contracted by at least one of temperature adjustment in the membrane module 13 and chemical addition to the treated water.

(3) Back pressure / back flow process The valve V9 is opened, and pressurized air from the compressor 18 is supplied from the treated water side of the membrane module 13 to apply pressure to the inner surface side of the membrane. Further, the valve V6 at the top of the membrane module 13 is opened, and the treated water at the top (secondary side) of the membrane module 13 is pushed out. At this time, in order to improve the recovery rate, the discharged water may be returned to the raw water tank 11.

(4) Air scrubbing step While maintaining the pressure, the valve V8 is opened and pressurized air is supplied from the raw water side lower portion of the membrane module 13 by the compressor 18 for a certain period of time, and the membrane module 13 is swung by the air.

(5) Drain process After performing air scrubbing for a certain period of time, the valve V10 and the valve V5 below the membrane module 13 are opened to discharge the water in the membrane module 13. At this time, the adhering substance can be discharged more effectively when the compressed air is kept flowing from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(6) Raw Water Rinsing Valves V1 and V4 and the valve V6 in the circulation line above the membrane module 13 are opened, the raw water pump 12 is activated, and the membrane module 13 is rinsed. The rinsed water may be returned to the raw water tank 11. At this time, rinsing can be performed more effectively if the compressed air is allowed to flow from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(7) Filtration The valve V6 at the top of the membrane module 13 is closed, and the filtration side valve V7 is opened to resume filtration. If the compressor 18 is moving in the previous process, it stops.

  According to the fourth embodiment, by changing the condition of at least one of the temperature and pH of the treated water supplied to the membrane module 13, it expands reversibly in response to a physical or chemical environmental change. / Depending on the characteristics of the shrinkable polymer material, the solute 3 captured by the pore diameter adjusting material 2 on the outer surface of the membrane in the membrane module 13 can be effectively discharged out of the system.

(Modification of the fourth embodiment)
FIG. 15 is a block diagram showing a modification of the membrane filtration system according to the fourth embodiment of the present invention.

  The membrane filtration system 170 shown in FIG. 15 is different from the membrane filtration system 160 shown in FIG. 14 in that the sensor 20 for detecting the temperature, pH value, etc. of the membrane module 13 and the treated water in the washing water tank 24 are used. In this configuration, a sensor 28 for detecting temperature, pH value, and the like, and a monitoring control device 21 for controlling temperature, pH value, etc. according to the values detected by the sensors 20, 28 are added.

  The washing procedure in the membrane filtration system 170 is the same as that in the membrane filtration system 160. However, the monitoring controller 21 determines the temperature or pH in the membrane module 13 according to the detection results of the sensors 20 and 28 in the hot water process. The heater 25 and the chemical injection facility 26 are controlled so that at least one of them reaches a predetermined target value. Here, it is preferable to control at least one of the temperature and the chemical addition amount so that the sum of the cost for changing the temperature and the cost required for the chemical addition is minimized.

  According to the modification of the fourth embodiment, according to the temperature and pH of the treated water flowing into the membrane module 13, by controlling at least one of the temperature and the chemical addition amount, the cost of changing the temperature and It is possible to perform effective filtration and cleaning taking advantage of the characteristics of a polymer material that reversibly expands / contracts in response to a physical or chemical environmental change while suppressing the cost required for chemical addition.

(Fifth embodiment)
FIG. 16 is a block diagram showing a membrane filtration system according to the fifth embodiment of the present invention.

  The membrane filtration system 180 shown in FIG. 16 is different from the membrane filtration system 160 shown in FIG. 14 in the outer cylinder 13a provided so as to cover the periphery of the membrane module 13 via a predetermined space, and in the washing water tank 24. A backwash water pump 29 that supplies wash water to the outer cylinder 13a and circulates it through the outside of the membrane module 13 is added.

  The filtration process and normal cleaning in the membrane filtration system 160 are performed in the same procedure as the membrane filtration system 140 described above. Then, cleaning is performed at a predetermined frequency using at least one of temperature adjustment and pH adjustment by chemical addition according to the following procedure.

(1) Back-pressure water process Chemicals are added to the treated water introduced into the washing water tank 24 by the chemical injection facility 26, and backflowed from the treated water side of the membrane by the backwash water pump 27. Or, it is discharged from the raw water side above the membrane module 13. At this time, the compressed air is supplied from the raw water side below the membrane module 13 by the compressor 18 to swing the membrane module 13.

  At the same time, the treated water in the washing water tank 24 whose temperature is adjusted to the LCST of the polymer material of the pore diameter adjusting material 2 by the heater 25 is supplied to the outer cylinder 13a by the backwash water pump 29 and circulated through the outside of the membrane module 13. Let In this manner, the pore diameter adjusting material 2 added to the outer surface of the membrane is reversibly contracted by at least one of adjusting the temperature of the treated water in the membrane module 13 and adding chemicals to the treated water. The circulation may be stopped when the temperature in the membrane module 13 can ensure LCST or higher in the following steps.

(2) Raw Water Rinsing The valves V1 and V4 and the valve V6 above the membrane module 13 are opened, the raw water pump 12 is activated, and the membrane module 13 is rinsed. At this time, the rinsing water may be circulated to the raw water tank 11. At this time, rinsing can be performed more effectively if the compressed air is allowed to flow from the compressor 18, but the compressed air may be stopped to reduce the power cost.

(3) Filtration The valve V6 at the top of the membrane module 13 is closed and the filtration side valve V7 is opened to resume filtration. At this time, if the compressor 18 is moving, it stops.

  According to the present embodiment, the polymer material that reversibly expands / contracts in response to a physical or chemical environmental change by changing at least one of temperature and pH in the membrane module 13. With this characteristic, the solute 3 captured by the pore diameter adjusting material 2 on the outer surface of the membrane in the membrane module 13 can be effectively discharged out of the system.

  Moreover, since the temperature inside the membrane module 13 is adjusted by circulating the treated water heated by the heater 25 through the outside of the membrane module 13, the heated raw water can be used effectively, and the amount of the heated raw water can be reduced. Can be saved.

  In the above description, the temperature inside the membrane module 13 is adjusted by circulating the temperature-adjusted treated water through the outside of the membrane module 13. However, the temperature of the membrane module 13 itself may be adjusted from the outside. For example, the present invention is not limited to the temperature adjustment method described above.

(Modification of the fifth embodiment)
FIG. 17 is a configuration diagram showing a modification of the membrane filtration system according to the fifth embodiment of the present invention.

  The membrane filtration system 190 shown in FIG. 17 is different from the membrane filtration system 180 shown in FIG. 16 in the cleaning water tank 24 and the sensor 23 for detecting the temperature, pH value, etc. of the raw water circulating outside the membrane module 13. In this configuration, a sensor 28 for detecting the temperature, pH value, etc. of the treated water and a monitoring control device 21 for controlling the temperature, pH value, etc. according to the values detected by the sensors 23, 28 are added. .

  The washing procedure in the membrane filtration system 190 is the same as that in the membrane filtration system 180. However, the monitoring control device 21 detects the temperature in the membrane module 13 or the The heater 25 and the chemical injection facility 26 are controlled so that at least one of the pH becomes a predetermined target value. Here, it is preferable to control at least one of the temperature and the chemical addition amount so that the sum of the cost for changing the temperature and the cost required for the chemical addition is minimized.

  According to the modification of the fifth embodiment, the temperature and the chemical addition amount are controlled by controlling at least one of the temperature and the chemical addition amount according to the temperature and pH in the membrane module 13 and required for the chemical addition. It is possible to perform effective filtration and cleaning taking advantage of the characteristics of a polymer material that reversibly expands / contracts in response to changes in physical or chemical environment while suppressing costs.

(Sixth embodiment)
FIG. 18 shows an example of a membrane module used in the membrane filtration system according to the sixth embodiment.

  As shown in FIG. 18, this membrane module is configured by laminating a plurality of membrane modules formed in a planar shape. As shown in FIG. 18 (a), raw water flows into the module from a flat plate surface. Then, as shown in FIG. 18B, it passes through the membrane and becomes membrane filtered water (treated water). As the membrane loaded in the membrane module shown in FIG. 18, the membrane 10 shown in FIG. 1 is used. This membrane module can be used in a state where it is immersed in a tank (open type or sealed type) into which raw water flows.

  FIG. 19 is a configuration diagram showing a membrane filtration system according to a sixth embodiment of the present invention.

  A membrane filtration system 200 shown in FIG. 19 shows a configuration in which the membrane module 55 having the configuration shown in FIG. 18 is immersed in a tank (open type or sealed type) into which raw water is flowing, and water is introduced to guide the raw water. Pump 51, raw water tank 52 for temporarily storing the raw water guided by water transfer pump 51, raw water pump 53 for supplying the raw water in raw water tank 52 to membrane immersion tank 54, and filtering the raw water guided by raw water pump 53 A membrane immersion tank 54, a membrane module 55 immersed in the membrane immersion tank 54, a suction pump 56 for sucking treated water after membrane filtration, and a treated water tank for storing treated water sucked by the suction pump 56 57 and a heater 58 for heating the raw water in the treated water tank 57 to a predetermined temperature. Moreover, the thermometer 59 which measures the raw | natural water temperature of the raw | natural water tank 52, and the heater 60 for heating the raw | natural water in the raw | natural water tank 52 to predetermined temperature are provided. Further, a cleaning water tank 61 that introduces and stores a part of the treated water stored in the processing water tank 57 as cleaning water, a thermometer 62 that measures the temperature of the cleaning water in the cleaning water tank 61, and the cleaning water tank 61. A heater 63 for heating the cleaning water stored therein to a predetermined temperature, and a backwash water pump 64 for supplying the cleaning water in the cleaning water tank 61 to the membrane module 55 are provided. Furthermore, a heater 65 for heating the raw water in the film immersion tank 54, a heater 66 for heating the raw water itself introduced into the film immersion tank 54, and a heater 67 for heating the cleaning water during backwashing are provided. In addition, a chemical injection facility 68 for injecting chemicals for pH adjustment into the raw water tank 52 is also provided. In addition, V31-V41 in the figure shows the valve | bulb provided in each piping.

  In the membrane filtration system 200 shown in FIG. 19, the raw water is guided to the raw water tank 52 by the water transfer pump 51. Raw water is introduced into the membrane immersion tank 54 by the raw water pump 53, and the treated water that has permeated through the membrane module 55 is sucked into the treated water tank 57 by a suction pump 56 disposed outside the tank. In this case, the raw water permeates through the membrane by the differential pressure generated by the water level difference method or the suction method and the combination thereof.

  And at the time of washing | cleaning, after adding a chemical | medical agent to the raw | natural water tank 52 and heating the raw | natural water temperature in the film | membrane immersion tank 54 with either of heater 60,65,66 or those combination, it supplies from the backwash water pump 64. The cleaning water is heated to 25 to 60 ° C. by any one of the heaters 58, 63 and 67 or a combination thereof and supplied to the membrane module 55 to execute the cleaning process. That is, heating on the raw water side is performed by any one of the heaters 60, 65, 66 or a combination thereof, and heating on the treated water side is performed by any one of the heaters 58, 63, 67 or a combination thereof.

  In this way, a simple system can be configured by immersing the membrane module 55 composed of a membrane responsive to a physical or chemical environmental change in the membrane immersion tank 54 into which raw water flows. Exchange of the membrane becomes easy, and stable operation can be executed even when the turbidity of the membrane feed water is high.

  In FIG. 19, the heating on the raw water side is constituted by the heaters 60, 65, 66, and the heating on the treated water side is constituted by the heaters 58, 63, 67. However, the heating is limited to this. It is not a thing. That is, on the raw water side, a heater 60 that heats the raw water in the raw water tank 52, a heater 66 that heats the raw water supplied from the raw water tank 52 to the membrane immersion tank 54, or a heater 65 that heats the raw water in the film immersion tank 54 Any configuration including at least one of them may be used. On the treated water side, a heater 63 that heats the treated water in the cleaning water tank 61, a heater 58 that heats the treated water in the treated water tank 57, or a heater 67 that heats the treated water supplied to the film immersion tank 54. Any configuration including at least one of them may be used. Further, the chemical injection facility 68 may be configured to inject the chemical into the cleaning water tank 61 instead of the raw water tank 52.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

It is a section lineblock diagram showing the membrane used with the membrane filtration system concerning a 1st embodiment of the present invention. It is explanatory drawing which shows the relationship between the expansion-contraction rate and liquid temperature in the film | membrane shown in FIG. It is a schematic diagram which shows the surface structure of the film | membrane shown in FIG. It is a schematic block diagram of the casing storage type | mold cylindrical membrane module which is an example of the membrane module used with the membrane filtration system which concerns on the 1st Embodiment of this invention. It is a lineblock diagram showing the membrane filtration system concerning a 1st embodiment of the present invention. It is a figure for demonstrating the filtration process in the membrane filtration system which concerns on this invention. It is a figure for demonstrating an example of the physical washing | cleaning in the membrane filtration system which concerns on this invention. It is a lineblock diagram showing the modification of the membrane filtration system concerning a 1st embodiment of the present invention. It is a block diagram which shows the membrane filtration system which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the modification of the membrane filtration system which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the membrane filtration system which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating another example of the physical washing | cleaning in the membrane filtration system which concerns on this invention. It is a block diagram which shows the modification of the membrane filtration system which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the membrane filtration system which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the modification of the membrane filtration system which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the membrane filtration system which concerns on the 5th Embodiment of this invention. It is a block diagram which shows the modification of the membrane filtration system which concerns on the 5th Embodiment of this invention. It is a schematic block diagram of the flat membrane module which is an example of the membrane module used with the membrane filtration system which concerns on the 6th Embodiment of this invention. It is a block diagram which shows the membrane filtration system which concerns on the 6th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Membrane substrate 2 Pore diameter adjusting material 3 Solute 10 Membrane 11 Raw water tank 12, 22 Raw water pump 13 Membrane module 14 Treated water tank 15, 24 Washing water tank 16, 25 Heater 17, 26 Chemical injection equipment 18 Compressor 19, 20, 23, 28 Sensor 21 Monitoring and Control Device 27, 29 Backwash Water Pump 51 Water Transfer Pump 52 Raw Water Tank 53 Raw Water Pump 54 Membrane Immersion Tank 55 Membrane Module 56 Suction Pump 57 Treatment Water Tank 58, 60, 63, 65-67 Heater 59, 62 Thermometer 61 Cleaning Water tank 64 Backwash water pump 68 Chemical injection equipment 100-190 Membrane filtration system

Claims (4)

A film substrate having a plurality of through-holes, the membrane container having a pore size adjusting material added with a polymeric material which reversibly expansion / contraction in response to changes in temperature and pH on the outer surface of the membrane substrate a membrane module becomes integrated by filling, the supplied raw water to membrane filtration, is discharged as treated water,
A cleaning means for cleaning the membrane by supplying the raw water or the treated water into the membrane module;
By changing the ambient temperature and pH of the pore diameter adjusting material, the pore diameter adjusting material is expanded at the time of the membrane filtration, and the condition variable means for contracting the pore diameter adjusting material at the time of the cleaning,
The condition variable means circulates part of the raw water or the treated water through the periphery of the membrane module while adjusting the temperature in order to adjust the temperature around the pore diameter adjusting material during the cleaning. membrane filtration system characterized in that it makes. Detecting means for detecting at least one of temperature and pH around the pore diameter adjusting material;
Control means for controlling the condition variable means so that at least one of the ambient temperature and pH of the pore diameter adjusting material becomes a predetermined target value according to a detection result by the detection means. The membrane filtration system according to claim 1 . A container having a membrane substrate having a plurality of through-holes and a pore size adjusting material in which a polymer material that reversibly expands / contracts in response to changes in temperature and pH is added to the outer surface side of the membrane substrate. A membrane cleaning method in a membrane filtration system comprising a membrane module that is filled and integrated, membrane-filtered supplied raw water and discharged as treated water,
Changing the pH of a portion of the raw water or the treated water;
The raw water or the treated water having a changed pH is supplied into the membrane module, and a part of the raw water or the treated water is circulated through the periphery of the membrane module while adjusting the temperature. Changing the temperature around the hole diameter adjusting material to shrink the hole diameter adjusting material;
Discharging water supplied into the membrane module;
A method for cleaning a film, comprising: Detecting at least one of temperature and pH around the pore diameter adjusting material;
A step of adjusting so that at least one of a temperature and a pH around the pore diameter adjusting material becomes a predetermined target value according to a detection result in the detecting step;
The film cleaning method according to claim 3, further comprising:

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