JP4270644B2 - Operating method and cleaning method of spiral membrane element and spiral membrane module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spiral membrane element and a method for operating a spiral membrane module used in membrane separators such as low pressure reverse osmosis membrane separators, ultrafiltration devices, and microfiltration devices, and a cleaning method.
[0002]
[Prior art]
In recent years, membrane separation technology has been applied to water purification technology, and membrane separation technology is being applied as a pretreatment for reverse osmosis membrane separation systems used in seawater desalination and the like. As a kind of membrane used for such membrane separation, a microfiltration membrane and an ultrafiltration membrane that can obtain a high permeate flow rate are often used, but recently, 10 kgf / cm. ² Reverse osmosis membranes that can obtain a high permeated water amount at the following ultra-low pressures have also been developed.
[0003]
As the form of the membrane element used for membrane separation, a hollow fiber membrane element is often used from the viewpoint of membrane area (volume efficiency) per unit volume. However, the hollow fiber membrane element has a drawback that the membrane is easily broken, and when the membrane is broken, the raw water is mixed with the permeated water and the separation performance is lowered.
[0004]
On the other hand, there is a spiral type membrane element as a form of the membrane element that can take a large membrane area. This spiral membrane element has the advantages that it can maintain separation performance and has high reliability as compared with the hollow fiber membrane element.
[0005]
FIG. 14 is a partially cutaway perspective view of a conventional spiral membrane element, and FIG. 15 is an external perspective view of the conventional spiral membrane element.
[0006]
As shown in FIG. 14, the spiral membrane element 21 has an envelope-like membrane (bag-like membrane) by superposing separation membranes 26 on both sides of a permeate spacer (permeate channel material) 25 and adhering three sides. 23, and the opening of the envelope-like membrane 23 is attached to the water collecting pipe 22 made of a perforated hollow tube, and is attached to the outer peripheral surface of the water collecting pipe 22 together with a net-like (net-like) raw water spacer 24 (raw water liquid channel material). It is configured by winding in a spiral shape.
[0007]
The raw water spacer 24 is provided to form a flow path through which raw water passes between the envelope-like membranes 23. When the thickness of the raw water spacer 24 is small, the filling efficiency of the separation membrane 26 is increased, but clogging with suspended substances occurs. Therefore, the thickness of the raw water spacer 24 is normally set to about 0.7 mm to 3.0 mm.
[0008]
A spiral membrane element using a zigzag corrugated raw water spacer (so-called corrugated spacer) for treating raw water containing a large amount of suspended solids such as river water has been already known.
[0009]
As shown in FIG. 15, the outer peripheral surface of the spiral membrane element 21 is covered with an exterior material 27 made of FRP (fiber reinforced plastic), a shrinkable tube or the like, and packing holders 28 called anti-telescopes are respectively provided at both ends. It is attached.
[0010]
FIG. 16 is a cross-sectional view showing an example of a method for operating a conventional spiral membrane element. As shown in FIG. 16, the pressure vessel (pressure vessel) 30 includes a cylindrical case 31 and a pair of end plates 32a and 32b. A raw water inlet 33 is formed on one end plate 32a, and a concentrated water outlet 35 is formed on the other end plate 32b. A permeated water outlet 34 is provided at the center of the other end plate 32b.
[0011]
A spiral membrane element 21 having a packing 37 attached in the vicinity of one end of the outer peripheral surface is mounted in a cylindrical case 31, and both open ends of the cylindrical case 31 are sealed with end plates 32a and 32b, respectively. One open end of the water collecting pipe 22 is fitted to the permeate outlet 34 of the end plate 32b, and an end cap 36 is attached to the other open end.
[0012]
During the operation of the spiral membrane element 21, the raw water 51 is introduced into the first liquid chamber 38 from the raw water inlet 33 of the pressure vessel 30. As shown in FIG. 16, the raw water 51 is supplied from one end face side of the spiral membrane element 21. The raw water 51 flows in the axial direction along the raw water spacer 24, and is discharged as concentrated water 53 from the other end face side of the spiral membrane element 21. In the process in which the raw water 51 flows along the raw water spacer 24, the permeated water 52 that has passed through the separation membrane 26 flows along the permeated water spacer 25 into the water collecting pipe 22 and is discharged from the end of the water collecting pipe 22.
[0013]
The permeated water 52 is taken out from the permeated water outlet 34 of the pressure vessel 30 of FIG. The concentrated water 53 is taken out from the second liquid chamber 39 in the pressure vessel 30 through the concentrated water outlet 35.
[0014]
[Problems to be solved by the invention]
When the spiral membrane element is operated, the membrane is clogged by turbid substances in the raw water, and the membrane flux is lowered. For this reason, chemical cleaning or the like is performed to remove clogging and the membrane flux is recovered. However, labor and cost required for chemical cleaning are problematic. Therefore, in order to prevent clogging, for example, in the hollow fiber membrane element, backflow cleaning with permeated water or air is periodically performed.
[0015]
However, with the conventional spiral membrane element 21, the following problems occur when backflow cleaning is performed.
[0016]
FIG. 17 is a partially cutaway perspective view showing a backwashing operation in a conventional spiral membrane element. As shown in FIG. 17, the permeated water 52 is introduced from the end of the water collecting pipe 22. Since the outer peripheral surface of the envelope-shaped membrane 23 wound around the water collection pipe 22 is covered with the exterior material 27, the permeated water 52 derived from the outer peripheral surface of the water-collection pipe 22 permeates the envelope-shaped film 23 and passes through the raw water. The gas flows in the axial direction along the spacer 24 in the spiral membrane element 21 and is discharged from the end of the spiral membrane element 21. Therefore, even if backwashing is performed, contaminants such as turbid substances that cause clogging of the membrane are easily captured by the raw water spacer 24 before being discharged from the end of the spiral membrane element 21, There is a problem that it is not sufficiently removed.
[0017]
In addition, a gap existing between the inner peripheral surface of the cylindrical case 31 of the pressure vessel 30 of FIG. 16 and the spiral membrane element 21 becomes a dead space S, and a stagnation (liquid accumulation) of fluid occurs. When the spiral membrane element 21 is used for a long time, the fluid staying in the dead space is transformed. In particular, when the fluid is a liquid containing organic matter, various germs such as microorganisms propagate, and this germ may decompose the organic matter to generate a bad odor or decompose the separation membrane. Leading to a decline.
[0018]
Further, in the conventional spiral membrane element 21, the raw water is supplied from one end of the spiral membrane element 21 and discharged from the other end, so that the envelope membrane 23 wound around the water collecting pipe 22 is shaped like a bamboo child. In order to prevent the deformation, the packing holder 28 is necessary. Further, a pressure difference is generated between the raw water inflow side and the concentrated water outlet side due to the pressure loss due to the raw water spacer 24 and the pressure loss due to clogging, and the spiral membrane element 21 is deformed. In order to prevent this deformation, the outer peripheral surface of the envelope-like film 23 wound around the water collecting pipe 22 is covered with an exterior material 27 such as FRP or a shrinkable tube. These increase the component cost and the manufacturing cost.
[0019]
Moreover, it is necessary to obtain a sufficient film surface linear velocity in order to prevent the formation of cake due to contaminants in the raw water, and for this purpose, a sufficient concentration side flow rate is required. When the flow rate on the concentration side is increased, the recovery rate per spiral membrane element is lowered, and the pump for supplying the raw water is increased, resulting in a very high system cost.
[0020]
An object of the present invention is to provide a spiral membrane element and a method for operating a spiral membrane module that can be reduced in cost, easy to clean and highly reliable.
[0021]
Another object of the present invention is to provide a cleaning method capable of easily and reliably removing contaminants trapped in a spiral membrane element.
[0022]
[Means for Solving the Problems and Effects of the Invention]
1st invention Is Operation method of spiral membrane element And spiral membrane element Includes a spiral-shaped membrane element in which a plurality of independent or continuous envelope-shaped membranes are wound on the outer peripheral surface of a perforated hollow tube via a raw liquid flow path material, and the outer peripheral portion of the spiral-shaped membrane element is Consist of the net Covered with a liquid permeable material, the outer peripheral surface side of the liquid permeable material is entirely or partially covered with an outer peripheral channel material, The permeate channel material inserted into the envelope membrane is extended from the outer peripheral side of the envelope membrane to the outside, and the extended portion of the permeate channel material is used as a net on the outer periphery of the spiral membrane element. Wound around During operation, it has a peeling or sterilizing action of pollutants from at least the outer peripheral side of the spiral membrane element. Contains medicine The stock solution is supplied and the permeate is taken out from at least one open end of the perforated hollow tube.
[0023]
According to the operation method of the spiral membrane element according to the present invention, during operation, the stock solution is supplied from at least the outer peripheral side of the spiral membrane element, and the entire amount is filtered. In this case, contaminants are captured at least at the outer periphery of the spiral membrane element.
[0024]
In addition, since dead space is not formed in the gap between the spiral membrane element and the pressure vessel due to total filtration, no fluid is retained in the gap between the spiral membrane element and the pressure vessel. Therefore, even when used for separation of a fluid containing organic matter, problems such as propagation of various germs such as microorganisms, generation of malodor due to decomposition of organic matter, decomposition of separation membrane do not occur, and high reliability is obtained.
[0025]
Furthermore, since the stock solution is supplied from at least the outer peripheral side of the spiral membrane element, pressure is applied to the spiral membrane element from all directions, and pressure that causes displacement in the axial direction is not applied. The wound envelope film does not deform into a bamboo shoot. This eliminates the need for a packing holder and an exterior material, thereby reducing component costs and manufacturing costs. Further, since the entire amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, the system cost is reduced.
[0026]
Further, since pressure is applied to the spiral type membrane element from all directions, the spiral type membrane element is not deformed even if the supply pressure of the stock solution is increased. Therefore, high pressure resistance can be obtained.
[0027]
Furthermore, it is possible to suppress the adhesion of the contaminant to at least the outer peripheral portion of the spiral membrane element by supplying the stock solution into which the chemical having the contaminant peeling action is injected to the spiral membrane element.
[0028]
Further, by supplying a stock solution into which a chemical having a bactericidal action is injected to the spiral membrane element, it is possible to suppress the propagation of germs such as microorganisms on the membrane surface of the spiral membrane element.
[0029]
From the above, the spiral membrane element can be operated stably for a long time.
[0030]
The chemical may be sodium hypochlorite, chloramine, hydrogen peroxide, peracetic acid or ozone. Since these chemicals have a pollutant peeling action, it is possible to prevent the pollutants from adhering to at least the outer periphery of the spiral membrane element. Moreover, since it has a bactericidal action, it is possible to suppress the propagation of germs on the membrane surface.
[0031]
The stock solution may contain a flocculant. In this case, since the pollutants contained in the stock solution are aggregated by the flocculant, the pollutants are easily captured at least at the outer peripheral portion of the spiral membrane element. Thereby, the load on the envelope-like film is reduced, and stable operation for a long period of time becomes possible.
[0032]
Also, at the time of cleaning, a cleaning liquid containing a chemical having a separating action or a bactericidal action for contaminants is introduced from at least one open end of the porous hollow tube, and the cleaning liquid led out from the outer peripheral surface of the porous hollow tube is spiraled. It may be discharged from at least the outer periphery of the mold membrane element.
[0033]
When the cleaning liquid is introduced from at least one open end of the effective hollow tube, the cleaning liquid led out from the outer peripheral surface of the perforated hollow tube passes through the envelope-shaped membrane and flows along the raw liquid flow path material, and the spiral type membrane It is discharged from at least the outer periphery of the element. Thereby, the contaminant trapped on at least the outer periphery of the spiral membrane element is peeled off from the spiral membrane element. Spiral type membrane elements are prevented from spreading between envelopes at the outer peripheral portion by the liquid permeable material and the peripheral portion flow path material, so that contaminants adhered to at least the outer peripheral portion of the spiral type membrane element during backflow cleaning A flow path for discharging the gas to the outside of the system is secured. For this reason, the peeled contaminants are discharged out of the system together with the cleaning liquid. Therefore, the contaminant trapped on at least the outer periphery of the spiral membrane element can be removed uniformly, and a constant permeate amount can be maintained at all times during operation.
[0034]
In this case, the contaminant attached to at least the outer peripheral portion of the spiral membrane element is easily peeled off by the chemical having the peeling action of the contaminant contained in the cleaning liquid. This makes it possible to more effectively clean the spiral membrane element.
[0035]
In addition, it becomes possible to more effectively suppress the propagation of germs such as microorganisms on the membrane surface of the spiral membrane element by the chemical having a bactericidal action contained in the cleaning liquid.
[0036]
From the above, the spiral membrane element can be operated stably for a long time.
[0037]
In particular, the liquid permeable material may be a separation membrane. In this case, since the undiluted solution is supplied from at least the outer peripheral side of the spiral membrane element and the outer peripheral portion of the spiral membrane element is covered with the separation membrane, the contaminants are separated from the separation membrane on at least the outer peripheral portion of the spiral membrane element. Captured. Therefore, it is possible to remove contaminants uniformly by backwashing with, for example, permeated water.
[0038]
Moreover, since only contaminants smaller than the pore diameter of the separation membrane in the outer peripheral portion enter between the envelope membranes of the spiral membrane element, the load on the envelope membrane is reduced, and stable operation can be performed for a long time.
[0039]
In particular, the separation membrane may be a microfiltration membrane. In this case, contaminants larger than the pore size of the microfiltration membrane are trapped at the outer periphery of the spiral membrane element and do not enter the spiral membrane element.
[0040]
Further, the separation membrane may be an ultrafiltration membrane. In this case, contaminants larger than the pore diameter of the ultrafiltration membrane are trapped at the outer periphery of the spiral membrane element and do not enter the spiral membrane element.
[0041]
The liquid permeable material may be a net. In this case, even if the back pressure generated at the time of backwashing is increased by the contaminant trapped on the outer periphery of the spiral membrane element, the outer peripheral net prevents the spiral membrane element from bulging, and the spacing between the envelope membranes Does not grow. Therefore, the membrane is prevented from being damaged due to the bulge of the envelope-like membrane, and the contaminant in the stock solution does not leak into the permeate.
[0042]
The net may be made of synthetic resin, or the net may be made of metal.
[0043]
The net is preferably 3 mesh or more and 200 mesh or less. Thereby, the swelling of the spiral membrane element due to the back pressure during backwashing can be reliably suppressed, and the stock solution can be sufficiently supplied from the outer peripheral side to the envelope membrane in the spiral membrane element during operation. it can.
[0044]
A predetermined portion of the net on the outer peripheral portion of the spiral membrane element may be reinforced with resin along the circumferential direction. Thereby, even if a high back pressure is generated during backwashing, the swelling of the spiral membrane element is surely prevented by the net on the outer peripheral portion.
[0045]
The permeate channel material inserted into the envelope membrane is extended from the outer peripheral side of the envelope membrane to the outside, and the extended portion of the permeate channel material is used as a net on the outer periphery of the spiral membrane element. It may be wound around.
[0046]
In this case, it is possible to prevent the spiral membrane element from bulging due to the back pressure during backwashing while suppressing additional component costs.
[0047]
In particular, the thickness of the outer peripheral channel material is preferably 0.6 mm or more and 30 mm or less. Accordingly, it is possible to discharge the contaminants attached to at least the outer peripheral portion of the membrane element during backflow cleaning out of the system while maintaining a large volumetric efficiency of the spiral membrane element with respect to the pressure vessel.
[0048]
The outer peripheral channel material is preferably arranged so that the stock solution flows substantially linearly in a direction substantially parallel to the axial direction of the perforated hollow tube. As a result, during the backwashing of the spiral membrane element, the contaminants adhering to the outer periphery of the spiral membrane element are pushed almost linearly in a direction substantially parallel to the axial direction of the perforated hollow tube with a small pressure loss due to the stock solution. be able to. Therefore, it is possible to easily and reliably discharge the contaminants attached to the outer peripheral portion of the spiral membrane element out of the system.
[0049]
The outer peripheral channel material may be a net-shaped channel material. In this case, the outer peripheral portion of the spiral membrane element is sufficiently protected by the net-like channel material, and the spread between the envelope-like membranes at the outer peripheral portion of the spiral membrane element is prevented. In addition, the stock solution can easily enter between the envelope-like membranes through the net-like channel material from the outer periphery of the spiral membrane element. Therefore, the handleability of the spiral membrane element is further improved, the stock solution can be efficiently supplied between the envelope membranes, and the contaminants can be reliably captured at the outer periphery of the spiral membrane element.
[0050]
Further, a permeate may be used as the cleaning liquid.
Second invention Is Cleaning method for spiral membrane element And spiral membrane element Includes a spiral membrane element in which a plurality of independent or continuous envelope-like membranes are wound around the outer peripheral surface of a perforated hollow tube via a raw liquid flow path material, and the outer peripheral portion of the spiral membrane element is Consist of the net Covered with the liquid permeable material, the outer peripheral surface side of the liquid permeable material is entirely or partially covered with the outer peripheral channel material, The permeate channel material inserted into the envelope membrane is extended from the outer peripheral side of the envelope membrane to the outside, and the extended portion of the permeate channel material is used as a net on the outer periphery of the spiral membrane element. Wound around A cleaning liquid containing a chemical having a separating action or a bactericidal action for pollutants is introduced from at least one open end of the perforated hollow tube, and the cleaning liquid led out from the outer peripheral surface of the perforated hollow tube is supplied to at least the spiral membrane element. It is discharged from the outer periphery.
[0051]
In the above spiral type membrane element, at least the outer peripheral portion is not covered with the exterior material and is in an open state, so that the stock solution can be supplied from at least the outer peripheral portion side of the spiral type membrane element and the entire amount can be filtered. . In this case, contaminants are captured at least at the outer periphery of the spiral membrane element.
[0052]
When cleaning liquid is introduced from at least one open end of the perforated hollow tube during cleaning, the cleaning liquid led out from the outer peripheral surface of the perforated hollow tube permeates the envelope membrane and flows along the undiluted liquid flow path material. The spiral membrane element is discharged from at least the outer periphery. As a result, the contaminant trapped on at least the outer periphery of the spiral membrane element is peeled off from the spiral membrane element and discharged out of the system together with the cleaning liquid. Accordingly, it is possible to uniformly remove the contaminant trapped on at least the outer periphery of the spiral membrane element.
[0053]
In this case, the contaminant attached to at least the outer peripheral portion of the spiral membrane element is easily peeled off by the chemical having the peeling action of the contaminant contained in the cleaning liquid. This makes it possible to more effectively clean the spiral membrane element.
[0054]
In addition, it becomes possible to more effectively suppress the propagation of germs such as microorganisms on the membrane surface of the spiral membrane element by the chemical having a bactericidal action contained in the cleaning liquid.
[0055]
From the above, the spiral membrane element can be operated stably for a long time.
[0056]
Further, the spiral membrane element may be immersed in a cleaning liquid containing chemicals.
In this case, a cleaning liquid containing a chemical is introduced into the spiral membrane element from the perforated hollow tube, and the spiral type membrane element is immersed in the cleaning liquid for a predetermined time. For example, in a spiral type membrane module in which a spiral type membrane element is loaded in a pressure vessel, the spiral type membrane element is immersed by filling the inside of the pressure vessel with a cleaning liquid. Thereafter, the cleaning liquid is discharged out of the system. Such immersion makes it easier for the contaminants attached to at least the outer periphery of the spiral membrane element to peel off, and the contaminants attached to the membrane surface can be easily cleaned, enabling more effective cleaning. It becomes. In addition, it is possible to more effectively suppress the propagation of germs such as microorganisms on the membrane surface of the spiral membrane element.
[0057]
From the above, the spiral membrane element can be operated stably for a long time.
[0058]
The chemicals are sodium hypochlorite, chloramine, hydrogen peroxide, It may be sulfuric acid, hydrochloric acid, sodium hydroxide, peracetic acid, isopropyl alcohol, oxalic acid or citric acid. Since these chemicals have a pollutant peeling action, it is possible to peel off the pollutants attached to at least the outer peripheral surface and perform cleaning more effectively. Moreover, since it has a bactericidal action, it becomes possible to more effectively suppress the propagation of germs on the membrane surface.
[0059]
After discharging the cleaning liquid from at least the outer periphery of the spiral membrane element, it is preferable to flow the stock solution in the axial direction along the outer periphery of the spiral membrane element. As a result, the contaminants attached to the outer periphery of the spiral membrane element can be easily peeled off, and the contaminants peeled off from the spiral membrane element can be easily and reliably discharged out of the system. .
[0060]
Alternatively, it is preferable to introduce the cleaning liquid into the perforated hollow tube after flowing the stock solution in the axial direction along the outer peripheral portion of the spiral membrane element. In this case as well, contaminants attached to the outer periphery of the spiral membrane element can be easily peeled off, and contaminants peeled off from the spiral membrane element can be easily and reliably discharged out of the system. It becomes.
[0061]
Alternatively, it is preferable to flow the stock solution in the axial direction along the outer peripheral portion of the spiral membrane element constantly or periodically in parallel with the introduction of the cleaning liquid into the perforated hollow tube. In this case as well, contaminants attached to the outer periphery of the spiral membrane element can be easily peeled off, and contaminants peeled off from the spiral membrane element can be easily and reliably discharged out of the system. It becomes.
[0062]
3rd departure Tomorrow A method of operating a spiral membrane module in which one or a plurality of spiral membrane elements are housed in a pressure vessel having a stock solution inlet, wherein the spiral membrane element is independent or on the outer peripheral surface of a perforated hollow tube Including a spiral membrane element formed by winding a plurality of continuous envelope membranes via a stock channel material, and the outer periphery of the spiral membrane element is Consist of the net Covered with the liquid permeable material, the outer peripheral surface side of the liquid permeable material is entirely or partially covered with the outer peripheral channel material, The permeate channel material inserted into the envelope membrane is extended from the outer peripheral side of the envelope membrane to the outside, and the extended portion of the permeate channel material is used as a net on the outer periphery of the spiral membrane element. Wound around During operation, a stock solution containing chemicals having a peeling or bactericidal action of contaminants is supplied from at least the outer peripheral side of the spiral membrane element through the stock solution inlet of the pressure vessel, and permeated from at least one open end of the perforated hollow tube. The liquid is taken out.
[0063]
According to the operation method of the spiral membrane module according to the present invention, the entire amount is filtered during the operation. In this case, contaminants are captured at least at the outer periphery of the spiral membrane element.
[0064]
Further, since no dead space is formed in the gap between the spiral type membrane element and the pressure vessel due to the total amount filtration, the liquid does not accumulate in the gap between the spiral type membrane element and the pressure vessel. Therefore, even when used for separation of a fluid containing organic matter, problems such as propagation of various germs such as microorganisms, generation of malodor due to decomposition of organic matter, decomposition of separation membrane do not occur, and high reliability is obtained.
[0065]
Furthermore, since the packing holder and the exterior material are not required in the spiral membrane element, the component cost and the manufacturing cost are reduced. Further, since the entire amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, the system cost is reduced.
[0066]
Furthermore, since the stock solution into which the chemical | medical agent which has the peeling action of a pollutant is inject | poured is supplied to a spiral type membrane element, it becomes possible to suppress that a pollutant adheres to at least the outer peripheral part of a spiral type membrane element.
[0067]
Moreover, since the stock solution into which the chemical | medical agent which has bactericidal action was inject | poured is supplied to a spiral type membrane element, it becomes possible to suppress miscellaneous bacteria, such as microorganisms, on the membrane surface of a spiral type membrane element.
[0068]
From the above, the spiral membrane module can be operated stably for a long time.
[0069]
4th departure Tomorrow A method for cleaning a spiral membrane module in which one or a plurality of spiral membrane elements are housed in a pressure vessel, wherein the spiral membrane element comprises a plurality of independent or continuous outer peripheral surfaces of a perforated hollow tube Including a spiral membrane element in which an envelope membrane is wound via a stock channel material, and the outer periphery of the spiral membrane element is Consist of the net Covered with the liquid permeable material, the outer peripheral surface side of the liquid permeable material is entirely or partially covered with the outer peripheral channel material, The permeate channel material inserted into the envelope membrane is extended from the outer peripheral side of the envelope membrane to the outside, and the extended portion of the permeate channel material is used as a net on the outer periphery of the spiral membrane element. Wound around A cleaning liquid containing a chemical having a separating action or a bactericidal action for pollutants is introduced from at least one open end of the perforated hollow tube, and the cleaning liquid led out from the outer peripheral surface of the perforated hollow tube is supplied to at least the spiral membrane element. It is discharged from the outer periphery and taken out of the pressure vessel.
[0070]
In the method for cleaning a spiral membrane module according to the present invention, when the cleaning fluid is introduced from at least one open end of the porous hollow tube of the spiral membrane element, the cleaning fluid derived from the outer peripheral surface of the porous hollow tube is enveloped. The membrane passes through the membrane and flows along the stock channel material, and is discharged from at least the outer peripheral portion of the spiral membrane element. As a result, the contaminant trapped on at least the outer periphery of the spiral membrane element is peeled off from the spiral membrane element and discharged together with the cleaning liquid to the outside of the pressure vessel. Accordingly, it is possible to uniformly remove the contaminant trapped on at least the outer periphery of the spiral membrane element.
[0071]
In this case, the contaminant attached to at least the outer peripheral portion of the spiral membrane element is easily peeled off by the chemical having the peeling action of the contaminant contained in the cleaning liquid. This makes it possible to more effectively clean the spiral membrane element.
[0072]
In addition, it becomes possible to more effectively suppress the propagation of germs such as microorganisms on the membrane surface of the spiral membrane element by the chemical having a bactericidal action contained in the cleaning liquid.
[0073]
From the above, the spiral membrane module can be operated stably for a long time.
[0074]
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 Reference form FIG. 3 is a partially cutaway perspective view of the spiral membrane element in FIG. 2 is a cross-sectional view showing an example of the envelope membrane of the spiral membrane element of FIG. 1, and FIG. 3 is a cross-sectional view showing another example of the envelope membrane of the spiral membrane element of FIG. is there.
[0075]
A spiral-type membrane element 1 shown in FIG. 1 is configured by winding a plurality of independent envelope-like membranes 3 or a plurality of continuous envelope-like membranes 3 around an outer peripheral surface of a water collecting tube 2 made of a perforated hollow tube. A spiral membrane element 1a. A raw water spacer (raw liquid flow path material) 4 is inserted between the envelope-shaped films 3 to prevent the envelope-shaped films 3 from coming into close contact with each other and to reduce the film area, and to form a flow path of the raw water. Has been.
[0076]
Further, the outer peripheral surface of the spiral membrane element 1a is covered with a separation membrane 9 which is a liquid permeable material. As the separation membrane 9, a microfiltration membrane or an ultrafiltration membrane is used.
[0077]
As the microfiltration membrane, a polymer organic membrane such as polyolefin, polysulfone, polypropylene, polyethylene, polystyrene, polyacrylonitrile, cellulose acetate or the like can be used. In addition, as the ultrafiltration membrane, a polymer organic membrane such as polysulfone, polypropylene, polystyrene, polyacrylonitrile, cellulose acetate, and polyethylene can be used.
[0078]
The outer peripheral surface side of the separation membrane 9 is covered with an outer peripheral channel material 5 made of a net. As the material of the net, polymer materials such as polyolefin, polysulfone, polypropylene, polyethylene, polystyrene, polyacrylonitrile, and cellulose acetate, inorganic materials such as ceramic, metal, synthetic rubber, fiber, and the like can be used.
[0079]
The pore diameter of the microfiltration membrane is preferably 0.01 μm or more and 10 μm or less. The pore size of the ultrafiltration membrane is preferably a fractional molecular weight of 20000 or more and a pore size of 0.01 μm or less. Furthermore, it is preferable that the net | network used as the outer peripheral part flow path material 5 is 4 meshes or more and 100 meshes or less.
[0080]
The pore diameter of the microfiltration membrane or ultrafiltration membrane used as the separation membrane 9 and the number of meshes of the net used as the outer peripheral channel material 5 are selected according to the quality of raw water.
[0081]
In the spiral membrane element 1 shown in FIG. 1, a microfiltration membrane having a pore diameter of 0.4 μm made of polyolefin such as ethylene vinyl alcohol is used as the separation membrane 9. Further, as the separation membrane 9, an ultrafiltration membrane made of polysulfone may be used. Furthermore, a 50 mesh net made of PET (polyethylene terephthalate) is used as the outer peripheral channel material 5.
[0082]
In addition to the outer peripheral surface of the spiral membrane element 1a, the end surface of the spiral membrane element 1a may be covered with the separation membrane 9.
[0083]
As shown in FIG. 2 and FIG. 3, the envelope-like membrane 3 is formed by superposing two separation membranes 7 on both surfaces of a permeate spacer (permeate channel material) 6 and adhering three sides. The opening of the envelope membrane 3 is attached to the outer peripheral surface of the water collecting pipe 2. As the separation membrane 7, 10 kgf / cm ² A low-pressure reverse osmosis membrane, an ultrafiltration membrane, a microfiltration membrane or the like operated in the following is used.
[0084]
In the example of FIG. 2, a plurality of envelope-like membranes 3 are formed by independent separation membranes 7. In the example of FIG. 3, a plurality of envelope-like membranes 3 are formed by folding a continuous separation membrane 7.
[0085]
When the thickness of the raw water spacer 4 is larger than 0.5 mm, it becomes difficult to capture contaminants in the raw water at least at the outer peripheral portion of the spiral membrane element 1. On the other hand, when the thickness of the raw water spacer 4 is smaller than 0.1 mm, the envelope-like films 3 are easily brought into contact with each other, and the film area is reduced. Therefore, the thickness of the raw water spacer 4 is preferably 0.1 mm or more and 0.5 mm or less.
[0086]
As shown in FIG. 1, the outer peripheral channel material 5 is formed in a lattice shape so that a plurality of wires 61 and 62 intersect at right angles. The thickness of the wire 61 is set larger than the thickness of the wire 62. As a result, the raw water 51 is likely to flow almost linearly between the wires 61 in a direction parallel to the wires 61.
[0087]
Further, as shown in FIG. 1, the outer peripheral flow path member 5 is arranged such that the wire 61 is parallel to the axial direction of the water collecting pipe 2. Therefore, the raw water easily flows in the axial direction on the outer peripheral portion of the spiral membrane element 1a.
[0088]
If the thickness t of the outer peripheral flow path member 5 is greater than 30 mm, the volumetric efficiency of the spiral membrane element 1 with respect to the pressure vessel that houses the spiral membrane element 1 is reduced. On the other hand, if the thickness t of the outer peripheral channel material 5 is smaller than 0.6 mm, raw water for discharging contaminants attached to at least the outer peripheral portion of the spiral membrane element 1 during backflow cleaning of the permeated water to the outside of the system. The flow rate is reduced. Therefore, it is preferable that the thickness of the outer peripheral channel material 5 is 0.6 mm or more and 30 mm or less.
[0089]
Moreover, the porosity in the thickness direction of the outer peripheral portion channel material 5 is set to 20% or more and 60% or less, for example. Thereby, sufficient intensity | strength of the outer peripheral part flow-path material 5 is securable, reducing the resistance of the raw | natural water which moves a contaminant to an axial direction at the time of backwashing. In addition, the vertical and horizontal pitches of the mesh of the outer peripheral flow path member 5 are, for example, 3 mm or more and 30 mm or less. Thus, the raw water can be sufficiently supplied between the envelope-like membranes 3 while preventing the outer peripheral surface of the spiral membrane element 1a from contacting the pressure vessel and narrowing the flow path of the raw water.
[0090]
The entire separation membrane 9 at the outer peripheral portion may be covered with the outer peripheral flow passage material 5, or a part of the region may be covered with the outer peripheral flow passage material 5.
[0091]
FIG. Ha It is sectional drawing which shows an example of the operating method of a spiral type | mold membrane element. As shown in FIG. 4, the pressure vessel (pressure vessel) 10 includes a cylindrical case 11 and a pair of end plates 12a and 12b. A raw water inlet 13 is formed in one end plate 12a, and a raw water outlet 15 is formed in the other end plate 12b. A permeated water outlet 14 is provided at the center of the other end plate 12b.
[0092]
The spiral membrane element 1 is accommodated in a cylindrical case 11, and both open ends of the cylindrical case 11 are sealed with end plates 12a and 12b, respectively. One end of the water collecting pipe 2 is fitted into the permeate outlet 14 of the end plate 12b, and an end cap 16 is attached to the other end. A pipe 19 is connected to the raw water inlet 13 of the end plate 12 a, and a pipe 20 is further connected to the pipe 19. The pipe 19 and the pipe 20 are provided with valves 18a and 18b, respectively. A pipe 17 is connected to the raw water outlet 15 of the end plate 12b. The pipe 17 is provided with a valve 18c.
[0093]
During the operation of the spiral membrane element 1, the valve 18a of the pipe 19 is opened, and the valve 18b of the pipe 20 and the valve 18c of the pipe 19 are closed. The raw water 51 is introduced into the pressure vessel 10 from the raw water inlet 13 of the pressure vessel 10 through the pipe 19. The raw water 51 flows along the outer peripheral channel material 5, passes through the separation membrane 9 from at least the outer peripheral portion side of the spiral membrane element 1, and enters the envelope-shaped membrane 3 along the raw water spacer 4. In the example of FIG. 4, raw water 51 enters between the envelope-shaped membrane 3 from the outer peripheral side and both ends of the spiral membrane element 1. The permeated water that has passed through the separation membrane 7 flows into the water collecting pipe 2 along the permeated water spacer 6. Thereby, the permeated water 52 is taken out from the permeated water outlet 14 of the pressure vessel 10. In this way, the entire amount is filtered.
[0094]
In this case, since the outer peripheral surface of the spiral membrane element 1 a is covered with the separation membrane 9, contaminants such as turbid substances larger than the pore diameter of the separation membrane 9 are captured at least at the outer peripheral portion of the spiral membrane element 1. Is done. That is, only contaminants smaller than the pore diameter of the separation membrane 9 enter between the envelope-like membranes 3. Accordingly, the load on the separation membrane 7 constituting the envelope membrane 3 is reduced.
[0095]
Alternatively, the raw water 54 may be partially taken out from the raw water outlet 15 by opening the valve 18 c of the pipe 17. In this case, the flow of raw water can be formed at the outer periphery of the spiral membrane element 1. Thereby, a part of the contaminant can be discharged to the outside of the pressure vessel 10 while suppressing sedimentation of the contaminant in the raw water.
[0096]
After performing filtration for a certain period of time, backflow washing with permeated water 52 is performed from the permeate side. FIG. 5 is a partially cutaway perspective view showing the backwashing operation in the spiral membrane element 1 of FIG. At the time of backwashing, the permeated water 52 is introduced into the water collection pipe 2 from the permeate outlet 14 of FIG. 4 with the valve 18 a of the pipe 19 and the valve 18 c of the pipe 17 closed and the valve 18 b of the pipe 20 opened. The permeated water 52 at the time of backwashing permeates the envelope membrane 3 from the water collecting pipe 2, peels off contaminants on the membrane surface from the membrane surface, and flows at least along the raw water spacer 4 toward the outer periphery. In addition, the contaminant trapped on at least the outer periphery of the spiral membrane element 1 is easily peeled off by the permeated water 52 during the backwashing. After that, flushing with raw water is performed. That is, the valve 18c of the pipe 17 is opened while supplying the raw water 51 from the raw water inlet 13 through the pipe 19 with the valve 18a of the pipe 19 opened and the valve 18b of the pipe 20 closed. As a result, the raw water 51 flows linearly in the axial direction along the outer peripheral channel material 5, and the polluted substances separated are discharged out of the system via the raw water outlet 15 and the pipe 17 in FIG. Contaminants remaining on the outer periphery of the membrane element 1 are peeled off from the spiral membrane element 1. As a result, the membrane flux is significantly recovered as compared with that before the backwashing. In addition, you may return the raw | natural water 54 containing the pollutant discharged | emitted out of the system by flushing to the raw | natural solution tank which stores raw | natural water.
[0097]
According to the above-described cleaning method, contaminants adhering to the outer peripheral portion of the spiral membrane element 1, particularly the separation membrane 9, can be easily and reliably discharged out of the system along the outer peripheral channel material 5. It is possible to suppress an increase in resistance of the separation membrane 9. Thereby, it is possible to always maintain a stable permeated water amount. Further, since the outer peripheral portion of the spiral membrane element 1 is covered with the outer peripheral flow passage material 5, handling (handling) properties are improved.
[0098]
Further, the gap between the spiral membrane element 1 and the pressure vessel 10 is illustrated in the filtration form as described above. 16 Since no dead space such as the dead space S shown in FIG. 5 is formed, problems such as propagation of germs such as microorganisms, generation of malodor due to decomposition of organic substances, decomposition of separation membranes, etc. do not occur, and high reliability can be obtained.
[0099]
Further, since pressure is applied to the spiral type membrane element 1 from all directions, the problem of deformation of the spiral type membrane element 1 does not occur, and a packing holder and an exterior material become unnecessary. Thereby, parts cost and manufacturing cost are reduced.
[0100]
Further, since the entire amount is filtered, it is not necessary to use a large pump for supplying the raw water 51. Thereby, the system cost is reduced.
[0101]
In the above-described backwashing, first, the permeated water 52 is introduced into the water collecting pipe 2, and the contamination trapped on the membrane surface and the outer peripheral portion of the spiral membrane element by the permeated water 52 led out from the outer peripheral surface of the water collecting pipe 2. Although the flushing with the raw water is performed after the substance is peeled off, the flushing with the raw water may be performed first, and then the permeated water 52 may be introduced into the water collecting pipe 2. According to this cleaning method, most of the contaminant trapped on the outer periphery of the spiral membrane element 1 is removed by flushing, and the permeated water 52 is further introduced, whereby the membrane surface and outer periphery of the spiral membrane element 1 are introduced. Contaminants remaining on the surface can be removed. Therefore, also in this case, the same effect as the above-described backwashing can be obtained.
[0102]
Alternatively, flushing with raw water may be performed constantly or periodically in parallel with the introduction of the permeated water 52 into the water collecting pipe 2 during the above-described backwashing. Even in this case, the same effect as the above-described cleaning method can be obtained.
[0103]
In this example, the supplied raw water 51 may contain sodium hypochlorite. When the raw water 51 containing sodium hypochlorite having a peeling action and a bactericidal action for pollutants is supplied to the spiral membrane element 1, the pollutants attached to the outer periphery of the spiral membrane element 1 are peeled off, It becomes possible to suppress deposition and to suppress the growth of microorganisms on the film surface. Thereby, in the spiral membrane element 1, more stable performance can be obtained over a long period of time.
[0104]
The raw water 51 may contain ozone, hydrogen peroxide, chloramine, or peracetic acid instead of sodium hypochlorite. Since these chemicals have a bactericidal action, it is possible to suppress the growth of microorganisms on the membrane surface of the spiral membrane element 1 as in the case of containing sodium hypochlorite.
[0105]
Here, the chemical | medical agent injection | pouring to the raw | natural water 51 is performed in the process until the raw | natural water 51 is supplied to a spiral membrane module, for example.
[0106]
Moreover, the chemical | medical agent injection | pouring to the raw | natural water 51 may be always performed continuously or may be performed intermittently. When injecting chemicals intermittently, for example, the injection of chemicals is controlled by a timer. Alternatively, the state of contamination of the spiral membrane element 1 is checked from the operating pressure or the amount of permeated water, and chemicals are injected when contaminants accumulate on the spiral membrane element 1, that is, when the operating pressure increases or the amount of permeated water decreases. May be performed. In this case, for example, measuring instruments such as an operation pressure gauge, a permeate flow meter, and a transmembrane pressure gauge are installed in an apparatus in which a spiral membrane module is incorporated, and chemicals are injected in accordance with signals from these measuring instruments. .
[0107]
Furthermore, a flocculant may be injected into the raw water 51 in addition to the above chemicals having a pollutant peeling action and a bactericidal action. In this case, since contaminants in the raw water 51 are aggregated, the contaminants are easily captured at the outer peripheral portion of the spiral membrane element 1.
[0108]
On the other hand, in this example, the permeated water 52 containing a chemical having a pollutant peeling action or a bactericidal action may be used as the washing water. For example, sodium hypochlorite having a concentration of 10 to 10000 ppm, chloramine having a concentration of 0.1 to 10 ppm, hydrogen peroxide having a concentration of 10 to 10000 ppm, sulfuric acid having a pH of 1 to 3, hydrochloric acid having a pH of 1 to 3, and sodium hydroxide having a pH of 10 to 13 Permeated water 52 containing peracetic acid with a concentration of 10 to 10000 ppm, isopropyl alcohol with a concentration of 0.1 to 50%, citric acid with a concentration of 0.2 to 2% or oxalic acid with a concentration of 0.2 to 2% is used as washing water. Use. When cleaning water containing such chemicals is used, it is possible to effectively remove contaminants adhering to the membrane surface and the outer peripheral portion of the spiral membrane element 1 and to propagate microorganisms on the membrane surface. It becomes possible to suppress.
[0109]
In particular, when the entire amount of raw water 51 with a high turbidity containing a large amount of contaminants is filtered, a large amount of turbid components (contaminants) in the raw water 51 are captured and deposited on the outer peripheral surface of the spiral membrane element 1. In addition, contaminants that are not trapped on the outer peripheral surface are deposited on the separation membrane 7. For this reason, it is difficult to completely remove the contaminants in the backflow cleaning using only the permeated water 52 as the cleaning water. In such a case, by using the permeated water 52 into which the above chemicals are injected, the accumulated contaminants can be easily peeled off, and the cleaning can be performed effectively.
[0110]
In addition, a chemical | medical agent may be continuously inject | poured into the permeated water 52, or a chemical | drug | medicine may be inject | poured after performing backflow washing | cleaning by the permeated water 52 several times.
[0111]
Further, during the back-flow cleaning using the cleaning water containing the above chemicals, after introducing the cleaning water from the end of the water collecting pipe 2, the spiral membrane element 1 is immersed in the cleaning water for several tens of minutes to several hours. May be. As a result, contaminants deposited on the membrane surface and the outer peripheral portion of the spiral membrane element 1 are more easily peeled off, and cleaning is performed more effectively. In addition, it is possible to more effectively suppress the growth of microorganisms on the membrane surface and the outer periphery. By further back-flushing the spiral membrane element 1 immersed in cleaning water containing chemicals, it becomes possible to discharge contaminants attached to the membrane surface and the outer peripheral portion to the outside of the spiral membrane module.
[0112]
The spiral type membrane element 1 is washed by such immersion once or several times a day, or for changes in the operating conditions of the spiral type membrane module, for example, an increase in operating pressure, a decrease in the amount of permeated water, etc. Do it accordingly.
[0113]
FIG. Other reference forms It is a front view of the spiral type membrane element in. In FIG. 6, illustration of the outer peripheral channel material is omitted.
[0114]
In the spiral membrane element 1 of FIG. 6A, both end portions of the spiral membrane element 1 a are sealed with a resin layer 40. In the spiral membrane element 1 in FIG. 6B, one end of the spiral membrane element 1 a is sealed with a resin layer 40.
[0115]
In the spiral membrane element 1 of FIGS. 6A and 6B, the number of work steps during manufacturing increases, but a space for supplying raw water to both ends or one end of the spiral membrane element 1 becomes unnecessary. Therefore, the pressure vessel can be miniaturized, and the spiral membrane module in which the spiral membrane element 1 is accommodated in the pressure vessel can be miniaturized.
[0116]
Also, the resin layer of the spiral membrane element 1 40 By disposing the end sealed at the raw water inlet side of the pressure vessel, it is possible to prevent the dirt from adhering to the end face of the spiral membrane element 1 due to the dynamic pressure of the raw water when the raw water is introduced.
[0117]
FIG. Still other reference forms FIG. 3 is a partially cutaway perspective view of the spiral membrane element in FIG. 8 is a cross-sectional view showing an example of an envelope-like membrane of the spiral membrane element of FIG. 7, and FIG. 9 is a cross-sectional view showing another example of the envelope-like membrane of the spiral membrane element of FIG. is there. Further, FIG. 10 is a partially cutaway front view of the spiral membrane element of FIG.
[0118]
A spiral membrane element 1 shown in FIG. 7 is configured by winding a plurality of independent envelope-like membranes 3 or a plurality of continuous envelope-like membranes 3 around the outer peripheral surface of a water collecting tube 2 made of a perforated hollow tube. A spiral membrane element 1a. A raw water spacer (raw liquid flow path material) 4 is inserted between the envelope-shaped films 3 to prevent the envelope-shaped films 3 from coming into close contact with each other and to reduce the film area, and to form a flow path of the raw water. Has been.
[0119]
As shown in FIG. 8 and FIG. 9, the envelope-like membrane 3 is formed by superposing two separation membranes 7 on both sides of a permeate spacer (permeate channel material) 6 and adhering three sides, The opening of the envelope membrane 3 is attached to the outer peripheral surface of the water collecting pipe 2. As the separation membrane 7, 10 kgf / cm ² A low-pressure reverse osmosis membrane, an ultrafiltration membrane, a microfiltration membrane or the like operated in the following is used.
[0120]
In the example of FIG. 8, a plurality of envelope-like membranes 3 are formed by independent separation membranes 7. In the example of FIG. 9, a plurality of envelope-like membranes 3 are formed by folding a continuous separation membrane 7.
[0121]
The outer peripheral surface of the spiral membrane element 1a is covered with a net 8 that is a liquid permeable material. As the material of the net 8, a synthetic resin such as polyolefin, polysulfone, polypropylene, polyester, polyethylene, polystyrene, polyacrylonitrile, polyamide, or a metal such as stainless steel or iron can be used.
[0122]
The net 8 is preferably 3 mesh or more and 200 mesh or less. Thereby, the swelling of the spiral membrane element 1a due to the back pressure during backwashing can be reliably suppressed, and raw water can be sufficiently supplied into the spiral membrane element 1a from the outer peripheral side during operation.
[0123]
In the spiral separation membrane element 1 shown in FIG. 7, the net 8 is made of a tricot cloth impregnated with an epoxy resin. The net 8 is 50 mesh, the pitch of the warp and weft is 0.5 mm, and the diameter of the warp and weft is 0.15 mm.
[0124]
In addition to the outer peripheral surface of the spiral membrane element 1a, the end surface of the spiral membrane element 1a may be covered with the net 8.
[0125]
As shown in FIG. 10, resin 81 is applied along the circumferential direction at equal intervals to three locations of the net 8 covering the outer peripheral surface of the spiral membrane element 1a, whereby the net 8 is connected to the outer periphery of the spiral membrane element 1a. It is fixed to the surface at three locations. The number of locations where the resin 81 is applied is not particularly limited because it depends on the back pressure generated during backflow cleaning. However, if the number of locations where the resin 81 is applied is greater than 3, the contamination of the outer peripheral portion of the spiral membrane element 1a during backflow cleaning is avoided. Substances are less likely to be removed. Therefore, for example, in the spiral film element 1a having a length of 944 cm, it is preferable to fix about three places with the resin 5a.
[0126]
The outer peripheral surface side of the net 8 is covered with the outer peripheral channel material 5. The material and dimensions of the outer peripheral channel material 5 are the same as those of the outer peripheral channel material 5 shown in FIG.
[0127]
In addition, the entire outer peripheral net 8 may be covered with the outer peripheral channel material 5, or a part of the area 8 may be covered with the outer peripheral channel material 5.
[0128]
The spiral type membrane element 1 shown in FIG. 7 is operated by the operating method of the spiral type membrane element shown in FIG. During the operation of the spiral membrane element 1, the valve 18a of the pipe 19 is opened, and the valve 18b of the pipe 20 and the valve 18c of the pipe 19 are closed. The raw water 51 is introduced into the pressure vessel 10 from the raw water inlet 13 of the pressure vessel 10 through the pipe 19. The raw water 51 flows along the outer peripheral channel material 5 and enters between the envelope membrane 3 from the outer peripheral side and both end sides of the spiral membrane element 1. The permeated water that has passed through the separation membrane 7 flows into the water collecting pipe 2 along the permeated water spacer 6. Thereby, the permeated water 52 is taken out from the permeated water outlet 14 of the pressure vessel 10. In this way, the entire amount is filtered.
[0129]
In this case, since the outer peripheral surface of the spiral membrane element 1 a is covered with the net 8, contaminants such as turbid substances larger than the hole diameter of the net 8 are captured at least at the outer peripheral portion of the spiral membrane element 1. . That is, only contaminants smaller than the hole diameter of the net 8 enter between the envelope films 3. Accordingly, the load on the separation membrane 7 constituting the envelope membrane 3 is reduced.
[0130]
Alternatively, the raw water 54 may be partially taken out from the raw water outlet 15 by opening the valve 18 c of the pipe 17. In this case, the flow of raw water can be formed at the outer periphery of the spiral membrane element 1. Thereby, a part of the contaminant can be discharged to the outside of the pressure vessel 10 while suppressing sedimentation of the contaminant in the raw water.
[0131]
After filtering for a certain period of time, back-flow cleaning shown in FIG. 5 is performed. At the time of backwashing, the permeated water 52 is introduced into the water collection pipe 2 from the permeate outlet 14 of FIG. 4 with the valve 18 a of the pipe 19 and the valve 18 c of the pipe 17 closed and the valve 18 b of the pipe 20 opened. The permeated water 52 at the time of backwashing permeates the envelope membrane 3 from the water collecting pipe 2, peels off contaminants on the membrane surface from the membrane surface, and flows at least along the raw water spacer 4 toward the outer periphery. In addition, the contaminant trapped on at least the outer periphery of the spiral membrane element 1 is easily peeled off by the permeated water 52 during the backwashing. After that, flushing with raw water is performed. That is, the valve 18c of the pipe 17 is opened while supplying the raw water 51 from the raw water inlet 13 through the pipe 19 with the valve 18a of the pipe 19 opened and the valve 18b of the pipe 20 closed. As a result, the raw water flows linearly in the axial direction along the outer peripheral channel material 5, and the polluted substances separated are discharged out of the system via the raw water outlet 15 and the pipe 17 in FIG. Contaminants remaining on the outer periphery of the element peel off from the spiral membrane element 1. As a result, the membrane flux is significantly recovered as compared with that before the backwashing. In addition, you may return the raw | natural water 54 containing the pollutant discharged | emitted out of the system by flushing to the raw | natural solution tank which stores raw | natural water.
[0132]
According to the above-described cleaning method, contaminants attached to the outer peripheral portion of the spiral membrane element 1, particularly the net 8 can be easily and reliably discharged out of the system along the outer peripheral flow path member 5. It is possible to suppress an increase in resistance of the net 8. Thereby, it is possible to always maintain a stable permeated water amount. Further, since the outer peripheral portion of the spiral membrane element 1 is covered with the outer peripheral flow passage material 5, handling (handling) properties are improved.
[0133]
In the spiral membrane element 1 shown in FIG. 7, since the outer peripheral surface of the spiral membrane element 1a is covered with the net 8, the reverse generated during back-flow cleaning by the contaminant trapped on the outer periphery of the spiral membrane element 1a. Even if the pressure is increased, the swell of the spiral membrane element 1a is prevented by the net 8 at the outer peripheral portion, and the interval between the envelope-like membranes 3 is not increased. Accordingly, the membrane is prevented from being damaged by the swelling of the envelope-like membrane 3, and the contaminants in the raw water 51 are not leaked into the permeated water 52.
[0134]
In particular, since the net 8 is fixed to the outer peripheral portion of the spiral membrane element 1a at a plurality of locations, the swelling of the spiral membrane element 1a is reliably prevented even when the back pressure during backflow cleaning is high.
[0135]
Furthermore, since no dead space is formed in the space between the spiral membrane element 1 and the pressure vessel, problems such as propagation of various microorganisms such as microorganisms, generation of bad odor due to decomposition of organic substances, and decomposition of the separation membrane do not occur. High reliability can be obtained.
[0136]
Further, since pressure is applied to the spiral type membrane element 1 from all directions, the problem of deformation of the spiral type membrane element 1 does not occur, and a packing holder and an exterior material become unnecessary. Thereby, parts cost and manufacturing cost are reduced.
[0137]
Further, since the entire amount is filtered, it is not necessary to use a large pump for supplying the raw water 51. Thereby, the system cost is reduced.
[0138]
In the above-described backflow cleaning, first, the permeated water 52 is introduced into the water collecting pipe 2, and the contaminant trapped on the outer peripheral portion of the spiral membrane element is peeled off by the permeated water 52 derived from the outer peripheral surface of the water collecting pipe 2. Then, flushing with raw water is performed. However, flushing with raw water may be performed first, and then the permeated water 52 may be introduced into the water collecting pipe 2. According to this cleaning method, most of the contaminants trapped on the membrane surface and the outer peripheral portion of the spiral membrane element 1 are removed by flushing, and further, by introducing permeate, the membrane surface of the spiral membrane element 1 and Contaminants remaining on the outer periphery can be removed. Therefore, also in this case, the same effect as the above-described backwashing can be obtained.
[0139]
Furthermore, the operation method of the spiral membrane element according to the present invention is shown in FIG. 12 Applied to the spiral membrane element 1 using part of the permeated water spacer 6 as shown in FIG. To do. In such a spiral membrane element 1, the permeated water spacer 6 inserted into one envelope-shaped membrane 3 is extended so as to protrude from the outer peripheral side of the envelope-shaped membrane 3 to the outside. The extended part of the spacer 6 is wound around the outer peripheral surface of the spiral membrane element 1 a as a net 8. The space between the permeated water spacer 6 protruding outward from the outer peripheral side of the envelope-like membrane 3 and the envelope-like membrane 3 is sealed with a resin 6a.
[0140]
In this case, it is possible to prevent the swelling of the spiral membrane element 1a due to the back pressure at the time of backwashing by the extended permeated water spacer 6 while suppressing the additional component cost by separately providing the net 8.
[0141]
6 and 7, as in the operation of the spiral membrane element 1 in FIG. 1, the supplied raw water 51 peels off contaminants such as sodium hypochlorite. A chemical having an action or a bactericidal action may be contained, or a flocculant may be contained. Further, the permeated water 52 used as the washing water at the time of backwashing may contain a chemical having a peeling action or a bactericidal action of contaminants such as sodium hypochlorite.
[0142]
In the above description, the spiral membrane module in which one spiral membrane element 1 is loaded in the pressure vessel 10 as shown in FIG. 4 has been described. , Su The operation method of the spiral membrane element and the spiral membrane module can also be applied to a spiral membrane module in which a plurality of spiral membrane elements 1 are loaded in a pressure vessel.
[0143]
FIG. Ha It is typical sectional drawing which shows the other example of the operating method of a spiral type membrane element and a spiral type membrane module.
[0144]
As shown in FIG. 13, the pressure vessel 100 includes a cylindrical case 111 and a pair of end plates 120a and 120b. A raw water inlet 130 is formed at the bottom of the cylindrical case 111, and a raw water outlet 131 is formed at the top. This raw water outlet 131 is also used for air venting. Further, a permeate outlet 140 is provided at the center of the end plates 120a and 120b.
[0145]
A plurality of spiral membrane elements 1 in which the water collecting pipes 2 are connected in series by an interconnector 116 are accommodated in a cylindrical case 111, and both open ends of the cylindrical case 111 are sealed with end plates 120a and 120b, respectively. The One end of the water collecting pipe 2 of the spiral membrane element 1 at both ends is fitted to the permeated water outlet 140 of the end plates 120a and 120b via the adapter 115, respectively. In this way, a spiral membrane module in which a plurality of spiral membrane elements 1 are loaded in the pressure vessel 100 is configured.
[0146]
During operation of the spiral membrane module, the raw water outlet 131 is closed, and the raw water 51 is introduced into the pressure vessel 100 from the raw water inlet 130 of the pressure vessel 100. The raw water 51 flows along the outer peripheral channel material 5 of each spiral membrane element 1. In each spiral membrane element 1, raw water 51 permeates the separation membrane 9 at least from the outer peripheral side, and enters between the envelope-shaped membranes 3 along the raw water spacer 4. The permeated water that has passed through the separation membrane 7 flows into the water collecting pipe 2 along the permeated water spacer 6, and the permeated water 52 is taken out from the permeated water outlets 140 at both ends of the pressure vessel 100. In this way, the entire amount is filtered. Even in this case, the raw water outlet 131 may be opened to partially extract the raw water, as in the method of operating the spiral membrane element and spiral membrane module shown in FIG.
[0147]
After performing filtration for a certain period of time, backflow washing with permeated water 52 is performed from the permeate side. At the time of backwashing, the permeated water 52 is introduced into the water collection pipe 2 of the spiral membrane element 1 from the permeate outlets 140 at both ends of the pressure vessel 100. In each spiral membrane element 1, the permeated water 52 permeates the envelope membrane 3 from the water collecting pipe 2, peels off contaminants on the membrane surface from the membrane surface, and flows along the raw water spacer 4 toward at least the outer peripheral portion. Further, the permeated water 52 easily separates contaminants captured at least on the outer peripheral portion of each spiral membrane element 1. Thereafter, the raw water outlet 131 is opened and the raw water 51 is supplied from the raw water inlet 130 to perform flushing. As a result, the pollutants that have peeled off are discharged to the outside of the spiral membrane module together with the raw water. In this case as well, the flushing may be performed before the backwashing, or the flushing may be performed in parallel with the backwashing, similarly to the operation method of the spiral membrane element and spiral membrane module shown in FIG. May be.
[0148]
According to the operation method of the spiral membrane element and the spiral membrane module as described above, the raw water is supplied to each spiral membrane element during the operation as in the operation method of the spiral membrane element 1 and the spiral membrane module shown in FIG. 1 is supplied from at least the outer peripheral side, and the entire amount is filtered in each spiral membrane element 1. In this case, in each spiral membrane element 1, contaminants are captured at least at the outer periphery. Accordingly, the load on the separation membrane 7 constituting the envelope membrane 3 is reduced.
[0149]
Furthermore, since the contaminants adhering to the separation membrane 7 and the outer peripheral portion of each spiral membrane element 1 can be easily discharged out of the system along the outer peripheral flow path material 5 at the time of cleaning, a stable amount of permeated water can be obtained. Can be maintained. Moreover, since the spiral membrane module is loaded with a plurality of spiral membrane elements 1, the processing capacity of the spiral membrane module is large, and the permeated water 52 can be obtained efficiently.
[0150]
In addition, since the dead space is not formed in the gap between each spiral membrane element 1 and the pressure vessel 100 by the filtration form as described above, the generation of bad odor due to the propagation of various germs such as microorganisms and the decomposition of organic substances is achieved. High reliability can be obtained without problems such as film decomposition.
[0151]
In addition, since pressure is applied from all directions in each spiral membrane element 1, the problem of deformation of the spiral membrane element 1 does not occur, and a packing holder and an exterior material become unnecessary. Thereby, parts cost and manufacturing cost are reduced.
[0152]
Further, since the entire amount is filtered, it is not necessary to use a large pump for supplying the raw water 51. Thereby, the system cost is reduced.
[0153]
Also in this example, as in the method of operating the spiral membrane element and spiral membrane module shown in FIG. 4, the supplied raw water 51 contains chemicals such as sodium hypochlorite having a pollutant peeling or sterilizing action. May be included. In this case, contaminants attached to the outer peripheral portion of each spiral membrane element 1 can be peeled off to suppress the accumulation of contaminants and to suppress the growth of microorganisms on the membrane surface. Thereby, in the spiral membrane module, more stable performance can be obtained over a long period of time.
[0154]
Moreover, you may use the permeated water 52 containing the chemical | medical agent which has the peeling action or disinfection action of contaminants, such as sodium hypochlorite, as washing water. In this case, it is possible to effectively remove contaminants attached to the membrane surface and the outer peripheral portion of each spiral membrane element 1, and it is possible to suppress the growth of microorganisms on the membrane surface. Thereby, in the spiral membrane module, more stable performance can be obtained over a long period of time.
[0155]
[ Reference example ]
[ Reference example 1]
Reference example 1 was operated using the spiral membrane element 1 (RS30-S4 manufactured by Nitto Denko Corporation) shown in FIG.
[0156]
Industrial water (pH 6-8, water temperature 10-30 ° C.) was used as the raw water 51. The supply pressure was adjusted so that a permeated water amount of 5 L / min was obtained, and filtration was performed for 30 minutes by the operation method shown in FIG. Then, the backwashing shown in FIG. 5 was performed. In addition, Reference example , The permeated water 52 was introduced into the water collecting pipe 2 and then flushed with the raw water 51 for 15 seconds. In this case, the backwashing time was 30 seconds, and the amount of permeated water 52 used for backwashing was 5 L / min.
[0157]
The spiral membrane element 1 was operated continuously for 40 days while repeating the filtration and backwashing as described above.
[0158]
Reference example 1, when the transmembrane pressure difference of the spiral membrane element 1 after 40 days from the start of operation was measured, 0.8 kgf / cm ² Met.
[0159]
[ Reference example 2]
Reference example 2 except that industrial water (pH 6-8, water temperature 10-13 ° C.) containing sodium hypochlorite with a concentration of 1 ppm was used as raw water, Reference example Filtration and backwashing were performed by the same operation method as in No. 1. Book Reference example In, sodium hypochlorite was continuously injected into industrial water.
[0160]
When the transmembrane pressure difference of the spiral membrane element 1 after 40 days from the start of operation was measured, 0.5 kgf / cm ² Met.
[0161]
[ Reference example 3]
Except for using permeated water containing sodium hypochlorite at a concentration of 5 ppm as washing water, Reference example The spiral membrane element 1 was operated by the same operation method as in FIG. Book Reference example , Sodium hypochlorite was injected continuously into the permeated water 52.
[0162]
When the transmembrane pressure difference of the spiral membrane element 40 days after the start of operation was measured, it was 0.7 kgf / cm. ² Met.
[0163]
[ Reference example 4]
After introducing permeated water containing sodium hypochlorite with a concentration of 100 ppm as washing water from the water collecting pipe 2, except that the spiral membrane element 1 was immersed in the washing water for 1 hour, Reference example The spiral membrane element 1 was filtered and backwashed by the same operation method as in No. 2. Book Reference example In the above, the above immersion was performed once every 5 days.
[0164]
When the transmembrane pressure difference of the spiral membrane element after 40 days from the start of operation was measured, it was 0.3 kgf / cm. ² Met.
[0165]
[ Reference example 5]
Reference example 5 except that industrial water (pH 6-8, water temperature 10-13 ° C.) containing ozone with a concentration of 10 ppm was used as raw water, Reference example Filtration and backwashing were performed by the same operation method as in No. 1. Book Reference example In, ozone was continuously injected into industrial water.
[0166]
When the transmembrane pressure difference of the spiral membrane element 1 after 40 days from the start of operation was measured, it was 0.7 kgf / cm. ² Met.
[0167]
[Comparative example]
In the comparative example, Reference example As with 1, the operation was performed using the spiral membrane element 1 shown in FIG. 7 (RS30-S4 manufactured by Nitto Denko Corporation).
[0168]
Reference example As in 1, industrial water (pH 6-8, water temperature 10-30 ° C.) was used as the raw water 51. The supply pressure was adjusted so that a permeated water amount of 5 L / min was obtained, and filtration was performed for 30 minutes by the operation method shown in FIG. Thereafter, backwashing was performed. However, in the comparative example, flushing with the raw water 51 was not performed, and only the backwashing with the permeated water 52 was performed.
[0169]
FIG. Reference example It is a figure which shows the time-dependent change of the transmembrane differential pressure | voltage of the spiral-type membrane element in 1 and a comparative example. As shown in FIG. Reference example In FIG. 2, since the permeated water 52 is introduced into the spiral membrane element 1 and flushing is performed with the raw water 51, it is possible to reliably remove contaminants attached to the net 8. As a result, the change in the transmembrane pressure difference in the spiral membrane element was small, and stable operation could be continued for a long time. On the other hand, in the comparative example, since the flushing with the raw water 51 is not performed, when the operation is performed for a long time, the contaminants adhere to the net 8 and the resistance of the net 8 increases. For this reason, the transmembrane pressure difference in the spiral membrane element 1 is increased.
[0170]
Also, Reference example 2, by injecting sodium hypochlorite having a pollutant peeling action and a bactericidal action into the raw water 51, the pollutants accumulate on the envelope membrane 3 and the net 8 of the spiral membrane element 1. It becomes possible to prevent effectively, and it is possible to effectively suppress the growth of microorganisms on the membrane surface. As a result, sodium hypochlorite is not injected into the raw water 51. Reference example Compared to 1, it is possible to continue a more stable operation for a long time.
[0171]
Meanwhile, sodium hypochlorite was injected into the wash water. Reference example 3, the contaminants deposited on the envelope film 3 and the net 8 can be peeled off and cleaned more effectively, and the growth of microorganisms on the film surface can be more effectively suppressed. . Thereby, only the permeated water 52 was used as washing water. Reference example Compared to 1, it is possible to continue a more stable operation for a long time. Further, the spiral membrane element 1 is immersed in cleaning water containing sodium hypochlorite. Reference example In No. 4, since it becomes possible to exfoliate pollutants more effectively, it becomes possible to continue further stable operation for a long time.
[0172]
Also, Reference example 5, it is possible to more effectively prevent the contaminants from being deposited on the envelope-like membrane 3 and the net 8 of the spiral membrane element 1 by injecting ozone having a peeling action and a bactericidal action into the raw water 51. And the propagation of microorganisms on the membrane surface can be effectively suppressed. As a result, ozone is not injected into the raw water 51. Reference example Compared to 1, it is possible to continue a more stable operation for a long time.
[Brief description of the drawings]
[Figure 1] Reference form FIG. 3 is a partially cutaway perspective view of the spiral membrane element in FIG.
2 is a cross-sectional view showing an example of an envelope membrane of the spiral membrane element of FIG. 1. FIG.
FIG. 3 is a cross-sectional view showing another example of the envelope membrane of the spiral membrane element of FIG.
4 is a cross-sectional view showing an example of a method for operating the spiral membrane element of FIG. 1. FIG.
5 is a partially cutaway perspective view showing a backflow cleaning operation in the spiral membrane element of FIG. 1. FIG.
[Fig. 6] Other reference forms It is a front view of the spiral type membrane element in.
[Fig. 7] Still other reference forms FIG. 3 is a partially cutaway perspective view of the spiral membrane element in FIG.
8 is a cross-sectional view showing an example of an envelope membrane of the spiral membrane element of FIG. 6. FIG.
FIG. 9 is a cross-sectional view showing another example of the envelope membrane of the spiral membrane element of FIG.
10 is a partially cutaway front view of the spiral membrane element of FIG. 6. FIG.
11 is a partially cutaway perspective view showing a backflow cleaning operation in the spiral membrane element of FIG. 6. FIG.
FIG. 12 uses a permeated water spacer as a net. Spiral type membrane element in one embodiment of the present invention FIG.
FIG. 13 The It is typical sectional drawing which shows the other example of the operating method of a spiral type membrane element and a spiral type membrane module.
FIG. 14 is a partially cutaway perspective view of a conventional spiral membrane element.
FIG. 15 is an external perspective view of a conventional spiral membrane element.
FIG. 16 is a cross-sectional view showing an example of a method for operating a conventional spiral membrane element.
FIG. 17 is a partially cutaway perspective view showing a backwashing operation in a conventional spiral membrane element.
FIG. 18 reference 2 shows changes with time in transmembrane pressure difference in Examples and Comparative Examples.
[Explanation of symbols]
1 Spiral membrane element
1a Spiral membrane element
2 Water collecting pipe
3 Envelope-like membrane
4 Raw water spacer
5 Outer channel material
6 Permeated water spacer
7 Separation membrane
8 Net
9 Separation membrane
10,100 pressure vessel
13,130 Raw water entrance
14,140 Permeate outlet
51 Raw water
52 Permeated water
61,62 Wire
81 resin

Claims (13)

  A method of operating a spiral membrane element, wherein the spiral membrane element is a spiral in which a plurality of independent or continuous envelope-like membranes are wound around an outer peripheral surface of a perforated hollow tube via a stock solution channel material. An outer peripheral portion of the spiral membrane element is covered with a liquid permeable material made of a net, and an outer peripheral surface side of the liquid permeable material is wholly or partially covered with an outer peripheral channel material, The permeate channel material inserted into the envelope membrane is extended from the outer peripheral side of the envelope membrane to the outside, and the extended portion of the permeate channel material is the spiral shape as the net. Wound around the outer peripheral surface of the membrane element, and during operation, a stock solution containing a chemical having a peeling action or a bactericidal action of contaminants is supplied from at least the outer peripheral side of the spiral membrane element, and at least the porous hollow tube on the other hand The method of operating a spiral type membrane element, wherein the retrieving the permeate from the open end.   2. The method of operating a spiral membrane element according to claim 1, wherein the chemical is sodium hypochlorite, chloramine, hydrogen peroxide, peracetic acid or ozone.   The method of operating a spiral membrane element according to claim 1 or 2, wherein the stock solution contains a flocculant.   At the time of cleaning, a cleaning liquid containing a chemical having a peeling action or a sterilizing action of contaminants is introduced from at least one open end of the porous hollow pipe, and the cleaning liquid led out from the outer peripheral surface of the porous hollow pipe is The method of operating a spiral membrane element according to any one of claims 1 to 3, wherein the spiral membrane element is discharged from at least an outer peripheral portion of the spiral membrane element.   5. The method of operating a spiral membrane element according to claim 4, wherein the cleaning liquid is a permeate.   A method for cleaning a spiral membrane element, wherein the spiral membrane element is a spiral formed by winding a plurality of independent or continuous envelope-like membranes around a perforated hollow tube through a stock solution channel material. An outer peripheral portion of the spiral membrane element is covered with a liquid permeable material made of a net, and an outer peripheral surface side of the liquid permeable material is wholly or partially covered with an outer peripheral channel material, The permeate channel material inserted into the envelope membrane is extended from the outer peripheral side of the envelope membrane to the outside, and the extended portion of the permeate channel material is the spiral shape as the net. A cleaning liquid that is wound around the outer peripheral surface of the membrane element and introduces a cleaning liquid containing a chemical that has a peeling action or a sterilizing action of contaminants from at least one open end of the porous hollow pipe, The cleaning liquid derived from The method of cleaning the spiral type membrane element, wherein the discharging of at least the outer peripheral portion of the Pairaru membrane element.   The method of cleaning a spiral membrane element according to claim 6, wherein the spiral membrane element is immersed in a cleaning liquid containing the chemical.   The spiral type according to claim 6 or 7, wherein the chemical is sodium hypochlorite, chloramine, hydrogen peroxide, sulfuric acid, hydrochloric acid, sodium hydroxide, peracetic acid, isopropyl alcohol, oxalic acid or citric acid. Membrane element cleaning method.   9. The stock solution is flowed in an axial direction along the outer periphery of the spiral membrane element after the cleaning liquid is discharged from at least the outer periphery of the spiral membrane element. A method for cleaning spiral membrane elements.   The stock solution is flowed in the axial direction along the outer periphery of the spiral membrane element before introducing the cleaning solution from at least one open end of the perforated hollow tube. 2. A method for cleaning a spiral membrane element according to 1. In parallel with the introduction of the cleaning liquid from at least one open end of the perforated hollow tube, the stock solution is flowed in the axial direction along the outer peripheral portion of the spiral membrane element constantly or periodically. The method for cleaning a spiral membrane element according to claim 6 .   An operation method of a spiral membrane module in which one or a plurality of spiral membrane elements are accommodated in a pressure vessel having a stock solution inlet, wherein the spiral membrane element is independent of the outer peripheral surface of a perforated hollow tube or A spiral membrane element in which a plurality of continuous envelope membranes are wound via a raw liquid flow path material is included, and an outer peripheral portion of the spiral membrane element is covered with a liquid permeable material including a net, and the liquid transmission The outer peripheral surface of the conductive material is wholly or partly covered with the outer peripheral channel material, and the permeate channel material inserted into the envelope-shaped membrane is exposed from the outer peripheral side of the envelope-shaped membrane to the outside. An extended portion of the permeate passage material is wound around the outer peripheral surface of the spiral membrane element as the net, and during operation, the spiral membrane element passes through the stock solution inlet of the pressure vessel. Spiral membrane module characterized by supplying a stock solution containing chemicals having a peeling or sterilizing action of contaminants at least from the outer peripheral side and taking out the permeate from at least one open end of the perforated hollow tube Driving method.   A method of cleaning a spiral membrane module in which one or more spiral membrane elements are housed in a pressure vessel, wherein the spiral membrane element comprises a plurality of independent or continuous outer peripheral surfaces of a perforated hollow tube An envelope membrane includes a spiral membrane element formed by winding a raw material flow path material, and an outer periphery of the spiral membrane element is covered with a liquid permeable material including a net, and an outer periphery of the liquid permeable material. The surface side is wholly or partly covered with the outer peripheral flow channel material, and the permeate flow channel material inserted into the envelope-shaped membrane is extended from the outer peripheral side of the envelope-shaped membrane to the outside, An extended portion of the permeate channel member is wound around the outer peripheral surface of the spiral membrane element as the net, and has a peeling or sterilizing action of contaminants from at least one open end of the perforated hollow tube. Contains chemicals A spiral membrane module characterized by introducing a cleaning fluid, discharging the cleaning fluid led out from the outer peripheral surface of the perforated hollow tube from at least the outer peripheral portion of the spiral membrane element, and taking it out of the pressure vessel. Cleaning method.

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