JP3976435B2 - Cleaning member for flat membrane separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning member for a flat membrane surface in a flat membrane separation apparatus that separates solid and liquid by a flat membrane module in which a plurality of rectangular plate-like flat membranes are provided in the horizontal direction at predetermined intervals.
[0002]
[Prior art]
Conventionally, activated sludge treatment equipment that treats organic wastewater in aerobic or anaerobic biological treatment tanks, sludge concentration and human waste treatment plants to maintain high-load operation of biological treatment tanks in nitrification / denitrification treatment equipment, etc. Cylindrical membranes or flat rectangular membranes using microfiltration membranes or ultrafiltration membranes for subsidence basins in sewage treatment plants, concentration of excess sludge, or microfiltration in pharmaceuticals, foods, and other industries A filtration membrane separation apparatus that separates solid and liquid by a filtration membrane module is used.
[0003]
The filtration membrane separation device attaches a slime or the like formed of a polymer material such as sludge or protein to the membrane surface of the filtration membrane module, so that chemical cleaning or air is diffused from below the filtration membrane module. The filtration membrane separation device (hereinafter referred to as flat membrane separation device) using a flat membrane module in which a plurality of flat membranes are provided together is used to prevent adhesion to the membrane surface and to remove and remove the adhered substances. In other words, a flat membrane separation apparatus in which a cleaning member is disposed between flat membranes is described in Japanese Patent Application Laid-Open Nos. 8-131783, 8-309161, and 9-890.
[0004]
The cleaning member described in Japanese Patent Application Laid-Open No. 8-131783 is a member in which a flexible member such as a plastic net is supported at the upper end, and the cleaning member described in Japanese Patent Application Laid-Open No. 8-309161. Is one in which the upper and lower ends of the thread-like or string-like member are fixed to the membrane module, and the cleaning member described in JP-A-9-890 supports the upper and lower ends of the long fiber bundle. .
[0005]
[Problems to be solved by the invention]
In filtration membrane devices that diffuse turbulent flow by the conventional gas and peel off deposits by shearing force, polymer substances such as sludge and proteins in biological treatment liquids adhere to the membrane surface very much. Since it is easy and sticky, it is difficult to peel off only by the turbulent effect, and the effect as expected is not obtained. Therefore, scales and slimes are formed in a short period of time, the amount of membrane permeate decreases, the operation is stopped and the number of times of washing is increased, and the amount of aeration is increased more than necessary. is there.
[0006]
In addition, in a conventional flat membrane separation apparatus in which a cleaning member for preventing sludge from adhering to the surface of a filtration membrane or peeling and removing deposits is disposed, a large number of thread-like or string-like cleaning members are used as upper and lower support members. It takes a lot of effort to support, and it is necessary to conduct an extremely complicated preliminary survey in order to select an optimal cleaning member of a material that has appropriate flexibility and lightness, has sufficient strength and does not damage the filtration membrane, There is also a problem that the production is expensive.
[0007]
Therefore, the present invention has a long life by disposing a cleaning member that can effectively prevent sludge from adhering to the surface of the filtration membrane and effectively remove the attached matter from the filtration membrane after adhering without fear of damaging the membrane. The purpose of the present invention is to provide a cleaning member for a flat membrane separation apparatus that can maintain the filtration performance of a filtration membrane for a long period of time, can greatly reduce the frequency of cleaning, and can greatly extend the life of the cleaning member. It has been done.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the gist of the present invention is that, in the invention described in claim 1, a plurality of rectangular plate-like flat membranes are provided at predetermined intervals in the horizontal direction, and the gaps between the flat membranes are the liquid flow to be treated. The flat membrane module formed as a channel is vertically run along the liquid flow path to be treated, the upper and lower ends are supported by a support member and stretched over substantially the entire surface of the flat membrane filtration surface, and the vertical slit is horizontal. In the cleaning member having a plurality of sheet portions provided at predetermined intervals in the direction, the sheet portion is a waterproof lattice-like woven sheet, and the upper and lower end portions of the sheet are respectively supported on the upper and lower sides. The cleaning member of the flat membrane separation apparatus is characterized in that the top end is supported by sewing in the horizontal direction, and the vertical slit is provided to the vicinity of the end of the end portion.
[0009]
In the invention according to claim 2, a flat membrane module in which a plurality of rectangular plate-like flat membranes are provided at predetermined intervals in the horizontal direction and a gap between the flat membranes is formed as a liquid flow path to be treated. A sheet that passes vertically along the liquid flow path to be treated, has upper and lower ends supported by a support member and stretched over substantially the entire surface of the flat membrane filtration surface, and a large number of vertical slits are provided at predetermined intervals in the horizontal direction. The cleaning member for a flat membrane separation apparatus according to the present invention is characterized in that the upper and lower end portions of the sheet portion are respectively sandwiched between both ends of the reinforcing member suspended around the upper and lower support members.
[0010]
According to a third aspect of the present invention, in the cleaning member of the flat membrane separation device according to the second aspect, the vertical slits provided in the sheet portion of the cleaning member reach both ends of the reinforcing member and extend. It is a cleaning member of a flat membrane separator characterized by being provided slits.
[0011]
Further, in the invention according to claim 4, in the cleaning member of the flat membrane separation device according to claim 2, both ends of the upper and lower reinforcing members suspended around the support member have different lengths in the vertical direction, A cleaning member for a flat membrane separation apparatus, wherein the vertical slit provided in the sheet portion of the member is a slit extending to the vicinity of the tip of the shorter end of the reinforcing member.
[0012]
Further, in the invention described in claim 5, in the cleaning member of the flat membrane separation device described in claim 2, claim 3 or claim 4, the clamping means for clamping the cleaning member is in the horizontal direction. The cleaning member of the flat membrane separation device is characterized in that the sewing machine is sewn.
[0013]
The flat membrane is made of an organic material such as a cellulose acetate type, an aromatic polyamide type or a polysphonic type on both sides of a nonwoven fabric molded body surrounded by a rectangular plate frame having a permeate channel. The filter membrane is preferably attached, but is not limited to this, and may be formed of an inorganic material such as a ceramic membrane. As the filtration membrane, a microfiltration membrane having a pore size of 0.1 to several μm, an ultrafiltration membrane having a fractional molecular weight of about several tens of thousands to several hundred thousand, and the like are used, but it is preferable to use a microfiltration membrane.
[0014]
Further, the sheet portion of the cleaning member is preferably 0.01 to 0.1 mm thick because polyethylene, polypropylene, nylon, or the like sheet is strong and flexible and does not damage the filter membrane. It is preferable that the slits in the direction are provided at intervals of 3 to 15 mm in the horizontal direction because appropriate swinging can be obtained.
[0015]
In the above, if the sheet thickness is 0.01 mm or less, the sheet strength is too weak and it is easy to cut, and if it is 0.1 mm or more, it is difficult to obtain appropriate swing and the flexibility is lost. If the slit distance is 3 mm or less, the strength of the sheet becomes too weak and it is easy to cut, and if it is 15 mm or more, it is difficult to obtain an appropriate swing and a wide surface contact. Therefore, the effect of peeling off the deposit is also reduced.
[0016]
In addition, when the sheet portion is a grid-like woven sheet or the like, the upper and lower end portions of the sheet are hung around the upper and lower support members without using reinforcing members because of the strength, and the tip The part may be supported by sewing in the horizontal direction. However, in normal smooth polypropylene sheets, etc., it is easy to break due to the notch effect at the slit end. It is necessary to support.
[0017]
In order to support the supporting member using the reinforcing member, the upper and lower end portions of the seat portion are sandwiched between the both ends of the upper and lower reinforcing members suspended around the supporting member, and the sewing machine is sewn in the horizontal direction. It is preferable that the material is clamped by the clamping means and is loosely stretched so that the gas supplied from the air diffusing means can swing with an appropriate amplitude and be in uniform contact with the entire surface of the filtration membrane. Note that it is not preferable to use an adhesive alone as a sandwiching means because it is easy to peel off, but it is preferable to use an adhesive in combination with a sewing machine because the strength increases.
In addition, the vertical slits are slits extending to reach both ends of the reinforcing member together with the sheet portion, and both ends of the vertical reinforcing member hung around the support member in the vertical direction. Appropriate rocking can be obtained because the length is different and the vertical slit provided in the sheet portion of the cleaning member extends to the position near the tip of the shorter end of the reinforcing member. Therefore, it is preferable.
[0019]
Further, the support member can be suitably used as a long rectangular plate, rod or tube, etc., but the long rectangular plate-like support member retains strength and is to be processed in the liquid flow path to be processed. This is preferable because there is little possibility of obstructing the upward flow of the liquid, and proper oscillation of the cleaning member can be obtained.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. 1 is a schematic view of a cleaning member of a flat membrane separation apparatus according to one embodiment of the present invention, FIG. 2 is a schematic view of a cleaning member of a flat membrane separation apparatus according to another embodiment, and FIG. 3 is a flat membrane of another embodiment. FIG. 4 is a schematic longitudinal sectional view of a flat membrane separation device arranged in a sludge separation treatment tank.
[0021]
Reference numeral 1 denotes a cleaning member having upper and lower ends supported by support members 6 (6a, 6b), and a sheet portion 2 in which a number of vertical slits 3 are provided at predetermined intervals in the horizontal direction. -It passes along the to-be-processed liquid flow path, and is stretched over substantially the entire flat membrane filtration surface.
[0022]
The sheet member 2 of the cleaning member is preferably a sheet of polyethylene, polypropylene, nylon or the like having a thickness of 0.01 to 0.1 mm, which is strong and flexible and does not damage the filter membrane. It is preferable that the slits 3 are provided at intervals of 3 to 15 mm in the horizontal direction because appropriate rocking can be obtained.
[0023]
In the above, if the sheet thickness is 0.01 mm or less, the sheet strength is too weak and it is easy to cut, and if it is 0.1 mm or more, it is difficult to obtain appropriate swing and the flexibility is lost. If the slit distance is 3 mm or less, the strength of the sheet becomes too weak and it is easy to cut, and if it is 15 mm or more, it is difficult to obtain an appropriate swing and a wide surface contact. Therefore, the effect of peeling off the deposit is also reduced.
[0024]
Further, the sheet portion 2 in FIG. 1 is formed of a waterproof lattice-like woven fabric sheet or the like referred to as HIPE (trademark) or blue sheet, and is strong. Without using a reinforcing member, the upper and lower end portions 4 of the sheet are hung around the support member 6, and the end portion 4 is supported by sewing 5 in the horizontal direction.
[0025]
Further, the sheet portion 2 in FIG. 2 is formed of a normal smooth polypropylene sheet or the like, and is weak in strength and easily broken by the notch effect at the slit end portion. The reinforcing member 7 is supported by the supporting member 6 using a strong reinforcing member 7. To support the supporting member 6, the sheet portion 2 is provided at each end portion 8 of the upper and lower reinforcing members 7 suspended around the supporting member 6. The upper and lower end portions of the upper and lower ends are respectively clamped by a clamping means such as a sewing machine 5 in the horizontal direction and loosely stretched. In addition, it is preferable because it is in uniform contact with the entire membrane surface. In addition, since it is easy to peel off only with an adhesive as the sandwiching means, it is not preferable, but it is preferable to use an adhesive in combination with a sewing machine because strength is increased.
[0026]
In addition, the sheet portion 2 in FIG. 2 is a slit 3 in which the vertical slit 3 extends to reach both end portions 8 of the reinforcing member 7 together with the sheet portion 2. In the groove portion 2, both ends 8 of the reinforcing member 7 hung around the support member 1 are different in length in the vertical direction by a, and the vertical slit 3 provided in the sheet portion 2 of the cleaning member 1 is the reinforcing member. The slit 3 extending to the position in the vicinity of the tip of the shorter end of 7 is preferable because appropriate swinging can be obtained.
[0027]
In FIG. 4, the upper and lower end surfaces 11 are open, the lower end opening is provided as an inlet 22 for the liquid to be processed, and the upper end opening is provided as a concentrate outlet 23. The sludge separation treatment tank 21 is fixed from the bottom by a support leg. A flat membrane module 12 in which a plurality of rectangular plate-like flat membranes 13 are arranged at predetermined intervals in the horizontal direction inside a cylindrical rectangular casing 17 which is soaked and placed at intervals. The flat membrane separation apparatus is provided with an air diffuser means 16 for diffusing gas into a liquid flow path 15 to be treated which is formed by a gap between the flat membranes 13 below the flat membrane module 12.
[0028]
The flat membrane module 12 includes a plurality of rectangular plate-like flat membranes 13 that are provided side by side with appropriate support members at predetermined intervals in the horizontal direction, and are connected to a permeate flow path provided in the flat membrane 13. A permeate discharge pipe 20 that discharges permeate that has passed through the respective flat membranes 13 is provided, and is connected to a permeate discharge means (not shown).
[0029]
The flat membrane 13 is formed by filtering organic material such as cellulose acetate type, aromatic polyamide type and polysphonic type on both sides of a nonwoven fabric molded body surrounded by a rectangular plate frame having a permeate channel. Although it is preferable to stick a film, it is not limited to this, and it may be formed of an inorganic material such as a ceramic film. As the filtration membrane, a microfiltration membrane having a pore size of 0.1 to several μm, an ultrafiltration membrane having a fractional molecular weight of about several tens of thousands to several hundred thousand, and the like are used, but it is preferable to use a microfiltration membrane.
[0030]
Further, the flat membrane separation device 11 passes through a liquid flow path 15 to be treated, which is a gap formed between the flat membranes 13 of the flat membrane module 12, and passes through the entire surface of the flat membrane filtration surface. A sheet-like cleaning member 1 is arranged, which is stretched over and has upper and lower ends supported by support members 6a and 6b and provided with a number of vertical slits at predetermined intervals in the horizontal direction.
[0031]
In addition, as a gas that causes an upward flow of the liquid to be treated and is diffused from the aeration means 16 for swinging the cleaning member 1, air is mainly used when used aerobically. Although used, it is preferable to use an anaerobic gas generated by biological treatment when used anaerobically.
[0032]
The sludge separation treatment tank 21 is a treatment tank for solid-liquid separation of a biological treatment liquid after aerobic treatment of organic wastewater with a biological treatment apparatus into sludge and a clear treatment liquid. The flat membrane separation device 11 may be disposed directly in the treatment tank, and as the biological treatment apparatus, a device for repeatedly treating anaerobic and aerobic in a single treatment tank, An apparatus or the like in which a plurality of biological treatment tanks are separately provided to improve the biological denitrification / dephosphorization effect by combining aerobic and anaerobic treatments.
[0033]
The support member has a long rectangular plate shape because the support member retains strength and is less likely to hinder upward flow of the liquid to be processed in the liquid flow path to be processed. However, a rod shape or a tubular shape can be used as appropriate.
[0034]
The operation of the flat membrane separator 11 having the above-described configuration will be described below. The biological treatment liquid in which the organic matter in the organic wastewater is decomposed by the biological action of microorganisms in the biological treatment apparatus to reduce BOD, COD, etc. is supplied from the biological treatment liquid supply pipe 24 to the sludge separation treatment tank 21. The liquid to be processed flows into the rectangular casing 17 from the liquid inlet 22 to be processed at the lower end of the flat membrane separation apparatus 11, and is formed between the flat films 13 by the air lift effect of the gas supplied from the air diffuser 16. During the upward flow through the liquid passage 15 to be treated, suction filtration is performed by the flat membrane 13 decompressed by a discharge means (not shown) connected to the permeate discharge pipe 20, and only moisture passes through the filtration membrane. Thus, a concentrated permeate and a concentrated liquid in which sludge is concentrated can be obtained.
[0035]
In the filtration process, the suction pressure by the discharging means is 0 to −600 mmHg, and the concentrated liquid is circulated in the sludge separation processing tank 21 from the concentrated liquid discharge port 23 at the upper end of the rectangular casing 17 and is appropriately concentrated. The sludge discharge pipe 25 circulates and supplies the biological treatment apparatus and the like as sludge for high-load operation, and a part of the sludge is supplied to the sludge treatment apparatus as surplus sludge. Further, the permeated liquid is discharged from the discharge pipe 20 as a clear processing liquid.
[0036]
Further, even if the operation of filtering the liquid to be treated by the flat membrane separation device 11 is continued, the side surface of the cleaning member 1 to which the oscillation of an appropriate amplitude is given by the gas supplied from the air diffuser 16 is the flat membrane 13. In addition to preventing sludge from adhering to the surface of the film, it is always peeled and removed even if sludge is attached, and the membrane surface is washed with gas from the air diffuser, so sludge and proteins such as proteins Slime due to substances is extremely difficult to form.
[0037]
The amount of gas supplied from the air diffuser 16 is 80 to 130 m <3> per flat membrane installation projected area in the conventional filtration membrane device in which gas is diffused to cause turbulent flow and the deposits are peeled off by shearing force. However, the flat membrane separator of the present invention can be operated at 40 to 80 m 3 / m 2 · h per flat membrane installation projected area.
[0038]
Next, a test example in which a biological treatment solution after aerobic biological treatment of food factory wastewater is used as raw water and solid-liquid separation is performed using a flat membrane separation apparatus arranged outside the biological treatment tank will be described.
Example 1
A flat membrane module having 240 flat membranes having a width of 610 mm, a height of 1060 mm, and a thickness of 13 mm is provided in a rectangular casing, and a tarpaulin is used as a reinforcing member as a cleaning member. Using a flat membrane separator with a polypropylene sheet of 07 mm and a slit interval of 10 mm, the amount of air blown from the diffuser is blown at 45 m 3 / m 2 · h per flat membrane installation area, and the cleaning member is swung. The raw water was made to flow upward. As a result of testing using a mixed liquid having a sludge concentration of 12000 mg / l as raw water, a permeate having a solid content of 0 mg / l was obtained at an initial permeate amount of 0.42 m 3 / m 2 · day, even after 4 months. There was almost no decline, and no signs of decline thereafter.
[0039]
(Comparative Example 1)
A flat membrane module having five flat membranes as in Example 1 is provided in a rectangular casing, and air is diffused at a rate of 100 m 3 / m 2 · h per flat membrane installation projection area without using a cleaning member. As a result of operating using the same raw water as in Example 1 using a flat membrane separation device that causes turbulent flow and peels off deposits by shearing force, a permeate having a solid content concentration of 0 mg / l is 0. Although the initial permeate volume was 42m3 / m2 · day, the permeate pressure began to increase from about the 10th day, so the air supply was gradually increased, but no significant improvement could be achieved. On the 25th day, the operation was stopped because the allowable pressure was exceeded.
[0040]
As a result of the above test, in the flat membrane separation apparatus of the present invention, an extremely clear permeate having a solid concentration of 0 mg / l was obtained, an initial permeate amount was obtained over a long period of 3 to 6 months, and washing was performed. Since there is no need to replace the parts, it has become possible to operate without much maintenance work. Further, it has been found that the amount of supplied air can be reduced by 20 to 40% compared to the conventional apparatus, and the operation cost such as the power cost can be saved. Furthermore, it can be easily installed and has appropriate flexibility and lightness compared to conventional devices that use thread-like or string-like cleaning members, and does not damage the filter membrane with sufficient strength. The optimum cleaning material of the material could be selected easily.
[0041]
【The invention's effect】
The present invention has a long period of time by disposing a cleaning member that can effectively prevent sludge from adhering to the surface of the filtration membrane and effectively remove the attached matter from the filtration membrane after adhering without fear of damaging the membrane. The cleaning member flat membrane separation device of the flat membrane separation device can maintain the filtration performance of the filtration membrane, can greatly reduce the frequency of washing, and can greatly extend the life of the washing member.
[Brief description of the drawings]
FIG. 1 is a schematic view of a cleaning member of a flat membrane separation apparatus according to an embodiment of the present invention. FIG. 2 is a schematic view of a cleaning member of a flat membrane separation apparatus according to another embodiment. Schematic diagram of the cleaning member of the membrane separator [Fig. 4] Schematic longitudinal sectional view of the flat membrane separator arranged in the sludge separation treatment tank [Explanation of symbols]
1: Cleaning member 2: Sheet portion 3: Slit 4: Sheet portion end portion 5: Sewing machine sewing 6: Support member 6a: Upper end portion support member 6b: Lower end portion support member 7: Reinforcement member 8: Reinforcement member end Part 11: Flat membrane separator 12: Flat membrane module 13: Flat membrane 15: Liquid to be treated 16: Aeration means 17: Rectangular casing 20: Permeate discharge pipe 21: Sludge separation treatment tank 22 : Inlet 23 for liquid to be treated: Condensate outlet 24: Biological treatment liquid supply pipe 25: Sludge discharge pipe

Claims (5)

A plurality of rectangular plate-like flat membranes are provided at predetermined intervals in the horizontal direction, and a gap between the flat membranes is vertically passed along the to-be-treated liquid channel of the flat membrane module formed as the to-be-treated channel. In the cleaning member having a sheet portion in which upper and lower ends are supported by a support member and stretched over substantially the entire surface of the flat membrane filtration surface, and a plurality of vertical slits are provided at predetermined intervals in the horizontal direction. Is a waterproof lattice-like woven fabric sheet, the upper and lower ends of the sheet are suspended around the upper and lower support members, the ends are supported by sewing in the horizontal direction, and the vertical slits are the ends. A cleaning member for a flat membrane separation device, which is provided up to the vicinity of the tip of the flat membrane separation device. A plurality of rectangular plate-like flat membranes are provided at predetermined intervals in the horizontal direction, and a gap between the flat membranes is vertically passed along the to-be-treated liquid channel of the flat membrane module formed as the to-be-treated channel. In the cleaning member having upper and lower ends supported by a support member and stretched over substantially the entire surface of the flat membrane filtration surface, and having a plurality of vertical slits provided at predetermined intervals in the horizontal direction, the upper and lower support members A cleaning member for a flat membrane separation device, wherein upper and lower end portions of a sheet portion are sandwiched between both ends of a reinforcing member that is hung around. The cleaning member for a flat membrane separator according to claim 2, wherein the slits in the vertical direction provided in the sheet portion of the cleaning member are slits that extend to reach both ends of the reinforcing member. Both ends of the vertical reinforcing member suspended around the support member have different lengths in the vertical direction, and the vertical slit provided in the sheet portion of the cleaning member extends to the vicinity of the tip of the shorter end of the reinforcing member. The cleaning member for a flat membrane separator according to claim 2, wherein the cleaning member is a slit provided. 5. The cleaning member for a flat membrane separator according to claim 2, wherein the clamping means for clamping the cleaning member is a horizontal sewing machine.

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