JP2014188484A - Pleat filter, ballast water treatment apparatus using the same, and ballast water treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pleat filter that contributes to stable long-term use by preventing a rupture caused by the use, and a ballast water treatment apparatus using the same.SOLUTION: In a pleat filter, a filter base material has folds in such a manner that a crest part and a valley part are repeated, and assumes a cylindrical shape in which a ridgeline direction of the fold is set to be an axial direction. A reinforcement plate is provided in the valley part seen from the inside of the cylindrical shape.

Description

  The present invention relates to a structure of a pleated filter mainly used for liquid filtration, and more particularly to a pleated filter used in a system for treating ballast water stored in a ship and used for filtering a large amount of water. Related to the device.

  A wide variety of filters are used for the purpose of separating and removing solids as contaminants from gases and liquids, and pleated filters that have a larger filtration area by making the filter into a pleated shape are also mainly used for gases such as air purifiers. It is used in. Patent Document 1 discloses an example in which a pleated filter formed in a cylindrical shape is used as a filter device for removing sludge from a cutting fluid of a machine tool. In this device, it is said that a filter device having a high filter cleaning effect can be provided by ejecting liquid toward the outer surface of the filter while rotating the cylindrical filter.

  On the other hand, in recent years, the treatment of ballast water loaded on ships has become a problem. Ballast water is seawater that is loaded on a ship for safe navigation even in an empty state, and various methods for purifying ballast water to remove or kill or inactivate microorganisms have been studied. A method of using filtration for the purpose of removing relatively large microorganisms has also been studied. For example, Patent Document 2 discloses a ballast water treatment apparatus using a filtration membrane by the applicant of the present application.

JP 2008-93783 A Japanese Patent No. 4835785

  When using brackish water and seawater such as seawater desalination and ballast water, or water treatment such as sewage, domestic wastewater, and industrial wastewater, pre-filtration treatment is required to remove foreign substances, dust, and microorganisms in the water. The inventors of the present application are considering the application of a pleated filter to such filtration. Here, it is necessary to filter a large amount of water in as short a time as possible. However, large-scale, high-flow operation is a technical problem that generally tends to cause a reduction in throughput and filtration function due to early clogging. Yes.

The device disclosed in Patent Document 2 is a filtration device that incorporates a cylindrical filter in a cylindrical container and collects the liquid flowing into the inside from the outside of the cylindrical filter as a filtrate. The filtration target liquid is sprayed from a nozzle provided on the side surface of the cylindrical container to a part of the filter filtration surface to clean the filtrate deposited on the filter surface to restore the permeation flux and to filter the washed filtrate. By draining from the front chamber, a stable filtration state is continuously continued. What is important for such a system to stably maintain continuous filtration is the cleaning effect due to the ejection of the liquid to be filtered onto the filter filtration surface. In order to efficiently and effectively clean the entire filter by changing the cleaning part of the filter over time, the cylindrical filter is rotated by a motor drive or the like during filtration, and the ejection from the ejection nozzle The hit location is changed continuously and periodically. In order to reliably perform this rotary cleaning and keep a high filtration flow rate stable, it is necessary to maintain the ejection of the liquid to be filtered from the nozzle at a flow rate level that is higher than a certain level. As a result of receiving a high flow rate, the cylindrical filter may deteriorate over time, break, and part of the liquid to be filtered may be mixed directly into the filtrate without passing through the filter. found.
Therefore, the present invention provides a pleated filter that can be used stably for a long period of time, preventing deterioration and breakage due to use, and a ballast water treatment device and a treatment method as a filtration device using the pleat filter. Objective.

  As a result of diligent studies on the deterioration of the filter, the inventors of the present application have confirmed that a rupture is likely to occur at a bent portion corresponding to a peak and a valley of a pleat of a filter that has been ejected at a high flow rate, and has reached the present invention.

  That is, the filter substrate has a fold so that the peak portion and the valley portion are repeated, and is a pleated filter having a cylindrical shape with the ridge line direction of the fold as an axial direction, the valley portion seen from the inside of the cylindrical shape It is a pleated filter equipped with a reinforcing plate.

Further, the present application is a ballast water treatment apparatus using the pleated filter as a filtration membrane, the pleated filter seals the upper surface and the bottom surface of the cylinder in a watertight manner, and is rotatably held around a cylindrical axis. A water-treatment nozzle that flows out the water to be treated toward the outer peripheral surface of the pleated filter, and a case having an outer cylinder portion that is provided so as to surround the pleated filter and includes a nozzle port of the water-treatment nozzle inside. A filtrate flow path for leading the filtrate water that has passed through the pleat filter from the inside of the cylinder of the pleat filter to the outside of the case;
A ballast water treatment apparatus including a discharge flow path for discharging discharged water that has not been filtered by the pleated filter to the outside of the case;

  Further, the ballast water treatment device is mounted in the hull, seawater obtained from the outside of the hull is used as treated water, and after further killing treatment is performed on the filtered water treated by the ballast water treatment device, the ballast water treatment As a method for treating ballast water stored in the hull.

  According to the above invention, it is possible to provide a pleated filter that prevents breakage due to use and contributes to stable use for a long period of time, a ballast water treatment apparatus using the pleat filter, and a ballast water treatment method. .

It is a perspective schematic diagram explaining the typical structural example of a pleat filter. It is a part of pleat filter of FIG. 1, Comprising: It is an expansion schematic diagram for demonstrating the relationship with to-be-processed water. (A) It is a figure which shows a part which looked at the pleated filter of FIG. 1 from the side surface. (B) It is a figure explaining one form of the state which a fracture | rupture produces in the pleat filter of FIG. 3 (A). It is a perspective schematic diagram which shows the structural example of the pleated filter provided with the reinforcement board as an embodiment of this invention. FIG. 5 is a schematic top view illustrating a part of the pleated filter of FIG. 4 in an enlarged manner. It is a side surface schematic diagram explaining the fixing structure of the pleat filter of FIG. It is a perspective view explaining the structure of the mesh board as an example of a reinforcement board. It is a perspective schematic diagram which shows another structural example of the pleat filter provided with the reinforcement board as an embodiment of this invention. It is an upper surface enlarged schematic diagram which shows another structural example of the pleat filter provided with the reinforcement board as an embodiment of this invention. It is a figure which shows an example of the embossing of a filtration membrane. (A) It is a figure which shows an example of the ballast water treatment apparatus which is the embodiment of this invention, and is a cross-sectional schematic diagram which shows the structure of the vertical cross section containing an axis line. (B) It is a figure which shows typically the structure of the horizontal AA cross section in FIG. 11 (A). It is a figure which shows typically another structural example of the horizontal AA cross section in FIG. 11 (A). It is a block diagram explaining the example of whole structure of the ballast water treatment system using the ballast water treatment apparatus which is the embodiment of this invention.

[Description of Embodiments of Present Invention]
Hereinafter, aspects of the present invention will be listed and described. Aspects of the present application 1 are: (1) a pleated filter having a fold so that the filter base material repeats crests and troughs, and having a cylindrical shape with the ridge line direction of the fold as an axial direction. It is a pleated filter provided with the reinforcement board in the trough part seen from the inside. Such a structure prevents breakage due to use and enables stable use for a long period of time.

  (2) As the reinforcing plate, it is preferable to use a flat substrate having a large number of holes penetrating from the front surface to the back surface, that is, a porous plate material. In particular, it is easy to use a mesh plate as the porous plate. The reinforcing plate may be a member having a strength that prevents the filter from being bent and deformed. At the same time, it is necessary to consider that the pleats of the filter do not excessively prevent the filter pleats from spreading due to the pressure of the water to be treated. Furthermore, it is preferable to improve the flow of the filtrate and consider the weight reduction of the entire filter.

  (3) The material of the reinforcing plate is selected from the group consisting of polypropylene, polyethylene (especially medium to low density polyethylene in terms of restoring force), polyamide resin such as nylon, polyester resin such as polyethylene terephthalate, and vinyl chloride. It is good to be formed with resin of. A resin member having strength necessary for ease of handling in manufacturing, weight reduction, cost, etc. is preferably used. Particularly preferred is polypropylene because it has moderate strength and restoring force. Some non-metallic materials, such as metal and glass / ceramics, have a performance superior to resin in terms of strength. However, in this embodiment, a restoring force against deformation is also required. Therefore, if it is a metal, a spring material, quenching process, etc. are needed, but the above-mentioned resin material is suitable considering the processing to a net structure and the corrosivity by seawater comprehensively.

  The size of the hole is preferably about 0.5 to 8 mm (pitch is 1 to 10 mm in the case of mesh) in terms of the balance between the permeation of the filtrate and the plate strength, more preferably 3 to 5 mm (as the case of mesh) The pitch is 3 to 5 mm). The plate thickness is selected in consideration of the pitch of the pleats (interval between adjacent valleys) and the desired strength. 0.3 to 2 mm is preferably used, and more preferably 0.5 to 1,5 mm.

  (4) The reinforcing plate is not limited to an independent plate material one by one. For example, the reinforcing plate has a fold so as to repeat a crest and a trough, and is provided along the cylindrical inner surface of the filter base. It may be done. With such a shape, an even higher reinforcing effect can be obtained.

  (5) The filter base material is preferably embossed. Embossing is a processing method that is generally used as a process for providing a filter substrate with a large number of continuous irregularities. By using the filter substrate 11 having such a surface, the filter itself is not easily bent. Moreover, it is suitable at the point which the clearance gap which arises by embossing becomes a flow path which does not prevent the inflow of the to-be-processed water to the back | inner side of the folded pleat and the outflow of the filtered treated water.

  (6) Moreover, in this application, the ballast water treatment apparatus which used the above-mentioned cylindrical pleated filter as a filtration membrane is shown. That is, the pleated filter has a cylindrical upper surface and a cylindrical bottom surface sealed in a water-tight manner, is rotatably held around a cylindrical axis, and has a treated water nozzle that discharges the treated water toward the outer peripheral surface of the pleated filter; A case having an outer cylindrical portion provided inside the pleated filter and provided with a nozzle port of the water nozzle to be treated, and filtered water that has passed through the pleated filter from the inside of the cylinder of the pleated filter. It is a ballast water treatment apparatus provided with the filtered water flow path led out outside, and the discharge flow path which discharges the discharged water which was not filtered with the pleat filter outside the case.

  In the apparatus having such a structure, the water to be treated is ejected from the nozzle port outside the cylinder of the cylindrical pleated filter toward the outer surface of the pleat filter, and therefore the pressure of the water to be treated is concentrated on a part of the pleat. Then, pressure is applied in the direction in which the pleats are opened, and the possibility that the filter breaks at each of the valley and the peak as described above increases. Therefore, by adopting the above-described breakage prevention structure with the reinforcing plate, it is possible to expect effects such as suppression of the occurrence of defective filtration, long-term operation of the apparatus due to the long life of the pleated filter, and reduction of operation costs.

  (7) In addition, after the ballast water treatment device is mounted in the hull, seawater obtained from the outside of the hull is used as water to be treated, and the killed water is further added to the filtered water treated by the ballast water treatment device. It is preferable to use a method for treating ballast water stored in the hull as ballast water.

  By using such a device or method, the filter can be prevented from being broken more than before, and can be used stably for a long time without causing defective filtration. Therefore, it is possible to suppress the maintenance personnel cost and the cost as a replacement material, and it is possible to further facilitate the production of the ballast water itself.

[Details of the embodiment of the present invention]
Configurations of a pleated filter and a ballast water treatment apparatus as embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

(Configuration of pleat filter)

  A typical structure example of a pleated filter as an object is shown in FIG. The pleated filter 10 in FIG. 1 is formed by forming a pleat shape by repeatedly folding plate-like filter base materials 11 alternately in peaks and troughs, and connecting the both end portions into a cylindrical shape as a whole. In actual use, the upper and lower surfaces of the cylinder are closed with different members and the shape is fixed. Filtration is performed from the inside to the outside of the cylindrical filter or vice versa. In the following description of the present application, mountains and valleys viewed from the outside of the cylinder are used as names. That is, the V part of the figure which is a fold protruding to the inside of the cylinder is called a valley part, and the M part of the figure which is a fold protruding to the outside of the cylinder is called a peak part. The valley portion viewed from the inside of the cylinder represents the space on the back side of the M portion between the V portion and the V portion.

  A porous resin sheet is used as the filter substrate. For example, a porous structure such as a stretched porous body, a phase-separated porous body, or a nonwoven fabric made of polyester, nylon, polyethylene, polypropylene, polyurethane, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), etc. is used. However, for the purpose of performing a high flow rate treatment, a nonwoven fabric made of polyester such as polyethylene terephthalate is particularly preferably used.

  A configuration is assumed in which the liquid to be filtered is supplied from the outer peripheral side of the cylinder of the pleated filter 10 having the shape of FIG. 1 and is filtered to the inner side of the cylinder. FIG. 2 is a diagram for explaining the force applied to the filter base 11 in that case. In FIG. 2, five arrows indicate the direction in which the liquid to be processed is supplied from the peak M side. A force P is applied to the filter base 11 in the direction in which the pleats are opened. Furthermore, the applied pressure P varies depending on the flow rate and pressure variation of the liquid to be treated, and acts on the filter substrate 11 as vibration or repeated bending depending on the configuration.

  FIG. 3A and FIG. 3B show one form of breakage that occurs in the pleated filter due to the pressure P described above. FIG. 3 (A) schematically shows a state before breakage, and FIG. 3 (B) schematically shows a state at breakage. The top and bottom of the filter are fixed for shape fixing and sealing. Therefore, when the pressure is repeatedly applied in the direction of opening the peak as shown in FIG. 2, the portion D near the center of the filter is bent in the direction shown in FIG. Thereby, the filter base 11 may be cracked or broken at the D portion, and the filtration function may be impaired. In particular, when the liquid to be filtered is a liquid such as water, the pressure received by the filter is larger than that of a gas such as air, and the filter is likely to break at the bent portion.

  Opening (bending) the central portion of the filter in the direction as shown in FIG. 3B is effective in that the liquid to be treated is supplied to the back of the pleat and the flow of the filter facilitates cleaning. However, it is necessary to prevent breakage or the like caused by bending. Then, it becomes possible to suppress said bending by providing a reinforcement board in the trough part seen from the cylindrical inside. FIG. 4 is a perspective view showing the structure of a pleated filter 10 as a representative example. Each trough has a reinforcing plate. In such a structure, the reinforcing plate may be a member having a strength that prevents the filter from being bent and deformed, and it is preferable not to excessively prevent the pleats of the filter from spreading due to the pressure of the water to be treated. That is, as shown in FIG. 3B, it is prevented from being bent into a “<” shape, but has a restoring force that returns to its original shape when it is released from the pressure of the water to be treated, while being curved with a gentle curve. preferable.

  In order to explain this state in an easy-to-understand manner, FIG. 5 is an enlarged schematic diagram of a part of FIG. The provision of the reinforcing plate in the trough means that the reinforcing plate is provided in the concave portion when viewed from the trough side, that is, the concave portion between the V portion and the adjacent V portion in the drawing. As shown in FIG. 5, the plate-like reinforcing plate 2 may be mounted near the center of the adjacent V portion so as to face the back of the M portion that becomes the peak portion. FIG. 6 is a schematic side view of the portion of FIG. 5 as viewed from the inside of the cylinder, and is a view for explaining a fixed state of the shape. The reinforcing plate 2 is fixed together with the filter base 11 by a fixing member 12 provided at the upper part of the cylinder and a fixing member 13 provided at the lower part of the cylinder. The fixing member is a disk-like or annular member disposed above and below the cylinder, and is a member that maintains the water-tightness of the fixing portion while fixing the shapes of the filter base 11 and the reinforcing plate 2. Preferably, the upper end portion and the lower end portion of the filter base 11 and the reinforcing plate 2 may be fixed with a resin as an adhesive, respectively.

  As a typical example used as a reinforcing plate, FIG. 7 shows a mesh-like plate. FIG. 7 shows an example of a mesh plate made of resin. By using a mesh plate having such irregularities, it is possible to prevent the reinforcement plate and the filter base material from being in close contact with each other, and the effect of preventing the flow of the filtrate from being hindered. can get. In addition, as the porous plate material, a punching material in which a large number of holes are formed in the plate material, a plate material having a three-dimensional network-like communication hole, or the like can be used.

  The reinforcing plate is not limited to an independent plate material one by one. For example, the reinforcing plate has a fold so as to repeat a crest and a trough, and is provided along the cylindrical inner surface of the filter base. Also good. FIG. 8 is a perspective view showing a representative example. The reinforcing plate 2 is also processed into a pleated shape in the same manner as the filter base material 11, and the filter base material 11 and the reinforcing plate 2 are formed in a double pleated shape as a whole.

  Furthermore, as a different aspect, the reinforcing plate is not limited to those arranged evenly along the valley center and the filter surface on the valley side, and is provided along one side of the valley side inner surface as shown in FIG. May be. FIG. 9 shows an example in which the reinforcing plate 3 is provided so as to cover the valley of the filter base material 11, and the reinforcing effect is enhanced by folding the reinforcing plate 3 so as to cover the valley.

  Thus, in the structure which arrange | positions a reinforcement board along a filter base material, it is preferable that the filter base material is further embossed. FIG. 10 shows an example in which the filter base 11 is embossed. A large number of circular concave portions and convex portions are repeatedly and continuously formed on the filter base 11 itself. The shape of the embossing is not limited, and any embossing may be used as long as it has a concave portion, a convex portion, or both. The embossing prevents the filter surface and the surface of the reinforcing plate from adhering to each other. By securing an appropriate gap on the filter surface, it is difficult to hinder the flow of the filtrate.

(Filtering device)
As a preferred application example of the filtration apparatus using the pleated filter described above, the configuration of a ballast water treatment apparatus will be described with reference to the drawings. FIG. 11 (A) and FIG. 11 (B) are diagrams showing an example of a ballast water treatment apparatus for ships as an embodiment of the present invention. FIG. 11A is a diagram schematically showing a configuration of a vertical cross section including an axis, and FIG. 11B is a diagram schematically showing a configuration of a horizontal AA cross section in FIG. The cylindrical pleated filter 101 is disposed so as to surround an axis serving as a rotation center, and is attached so as to be rotatable around a central pipe 140 (pipe does not rotate) disposed at the center. The upper and lower surfaces of the pleated filter are closed watertight. The rotatable mounting structure also needs to be a watertight structure, but a known structure is used without any particular limitation. A case 103 is provided so as to cover the entire filter. The case 103 includes an outer cylinder part 131, a lid part 132, and a bottom part 133, and the bottom part 133 is provided with a discharge channel 108. A treated water channel 106 and a treated water nozzle 102 are provided for introducing seawater as treated water into the case 103. The treated water nozzle 102 is extended from the treated water flow path 106 so that the nozzle port 121 is provided in the outer cylinder part 131 of the case 103 so that the treated water flows out toward the outer peripheral surface of the pleated filter. It is configured. A motor 190 is provided on the central axis of the pleat filter for rotating the pleat filter. The motor 190 is covered and accommodated by a motor cover 191 and is driven by electric power from a drive control unit (not shown).

  In the case of this example, the water to be treated ejected from the water nozzle to be treated hits the pleated outer peripheral surface of the pleated filter, and the cleaning effect of the pleated filter is obtained by the pressure. The untreated water to be treated and the suspended matter settled in the case are sequentially discharged from the discharge channel at the bottom of the case. The characteristic of this apparatus is that the filtration proceeds while the turbid component and the remaining water to be treated are continuously discharged, and 10 to 20 tons / hour or even 100 tons / hour required for ballast water. It is effective to secure a processing amount exceeding. In the figure, a valve or the like is not shown in the discharge flow path, but equipment necessary for maintenance and flow rate adjustment is provided. The filtered water filtered by the pleated filter 101 is guided to the filtered water flow path 107 through the water intake hole 141 provided in the central pipe 140 inside the filter, and flows out of the case.

  As an example of an apparatus that performs processing at 100 tons / hour, an outer diameter of a pleat filter is 700 mm, an axial length is 320 mm, an effective area is height 280 mm, a pleat depth is 70 mm, and a pleat number is 420 folds. The treated water nozzle 102 may have a rectangular nozzle opening 121. When a large amount of water is ejected from the water nozzle to be treated onto the pleated filter surface, vibration in the direction in which the fold of the pleated filter opens and closes is generated, so that holes such as tears are easily opened. By using the pleated filter provided with the reinforcing plate as described above, the breakage can be effectively suppressed, and the apparatus can be operated stably for a long time.

  FIG. 12 is a schematic cross-sectional view illustrating another configuration example corresponding to FIG. It is an example at the time of using the pleat filter of the structure of FIG. 8 which has a crease | fold so that a peak part and a trough part may be repeated as the pleat filter 101, and was provided along the cylindrical shape inner surface of the said filter base material. .

(Experimental example)
In order to confirm the effect by a reinforcement board, it filtered using the ballast water treatment apparatus shown to FIG. 11 (A) and FIG. 11 (B).
The materials used are as follows.
Filter base material: Non-woven fabric made of polyethylene terephthalate (trade name: Axter G2260-1S BK0 manufactured by Toray)
Reinforcement plate: Polypropylene mesh plate (trade name: Tricarnet SN-598, manufactured by Takiron)
Mesh pitch 4.8mm x 4.8mm
Thickness 1.5mm (1.5mm warp, 1.2mm weft)

  The reinforcing plate was cut into strips and attached to the filter troughs as shown in FIG. When the reinforcing plate was not used, the filter peak portion was damaged in the filtration operation for 50 hours, and when the reinforcing plate was provided in the filtration under the same conditions, the damage was not generated until 155 hours. .

Further, as another structural example, in the case of FIG. 12 in which the next reinforcing plate is folded together with the filter base material, the effect of preventing damage can be obtained in the same manner as described above. Furthermore, by embossing the filter substrate, the contact between the filter substrate surface and the reinforcing plate can be suppressed, which is more effective.
Filter base material: Non-woven fabric made of polyethylene terephthalate (trade name: Axter G2260-1S BK0 manufactured by Toray)
Reinforcement plate: Polypropylene mesh plate (trade name: Takiron Tricarnet SN-11)
Mesh pitch 3.9mm x 3.9mm
Thickness 0.9mm (warp thread 0.9mm, weft thread 0.5mm)

  In the structure, no breakage occurred for 79 hours or more. On the other hand, it has been confirmed that the structure of FIG. 11B is preferable to the structure of FIG.

  FIG. 13 is an explanatory diagram schematically showing the overall configuration of a marine ballast water treatment system using the above-described ballast water treatment device as a filtration device. In FIG. 13, water to be treated which is seawater taken from the ocean is sent by a pump 21 through a pipe 31 and supplied to a filtration device 22 which is a filtering means through a pipe 32. The filtered water filtered in the filtering device 22 is sent to a killing device 23 (not essential) such as an ultraviolet irradiation device or an electrolysis device via a pipe 33. Further, the discharged water that has not been filtered in the filtering device 22 is led out of the device through the pipe 35. The seawater subjected to the killing process is sent to the tank 24 through the pipe 34 and the pipe 36.

  The pleated filter of the present invention is superior in durability without causing degradation in performance due to breakage, and therefore, when using brackish water and seawater such as seawater desalination and ballast water, or in water treatment such as sewage, domestic wastewater, and industrial wastewater, It can be suitably used for pre-filtration treatment for removing foreign matters, dust, and microorganisms. In addition, because it is excellent in water treatment and concentration treatment with high turbidity and high SS, it can be applied in the field of valuable resources recovery such as the food field.

2 Reinforcing plates 10, 101 Pleated filter 11 Filter base materials 12, 13 Fixing member
21 Pump 22 Filtration device 23 Killing device 24 Tank 31, 32, 33, 34, 35, 36 Pipe 102 Water to be treated nozzle 103 Case 106 Water flow to be treated 107 Filtration water flow passage 108 Discharge flow passage 121 Nozzle port 131 Outer cylinder 132 Lid 133 Bottom 140 Central piping 141 Water intake 190 Motor 191 Motor cover

Claims (7)

  The filter substrate has a fold so that the peak and valley are repeated, and is a pleated filter having a cylindrical shape with the ridge line direction of the fold as the axial direction, and is reinforced to the valley as viewed from the inside of the cylindrical shape Pleated filter with a plate.   The pleated filter according to claim 1, wherein the reinforcing plate is formed of a flat substrate having a large number of holes penetrating from the front surface to the back surface.   The pleated filter according to claim 1 or 2, wherein the reinforcing plate is formed of any resin selected from the group consisting of polypropylene, polyethylene, polyamide, polyester, and vinyl chloride.   The said reinforcement board has a crease | fold so that a peak part and a trough part may be repeated, It is provided so that the cylindrical inner surface of the said filter base material may be followed. The pleated filter described.   The pleated filter according to any one of claims 1 to 4, wherein the filter substrate is embossed. A ballast water treatment device using the cylindrical pleated filter according to any one of claims 1 to 5 as a filtration membrane,
The pleated filter seals the upper surface and the bottom surface of the cylinder in a watertight manner, and is held rotatably about the cylinder axis.
A treated water nozzle for flowing the treated water toward the outer peripheral surface of the pleat filter,
A case having an outer tube portion provided inside the pleated filter and provided with a nozzle port of the water nozzle to be treated inside;
A filtrate flow path for leading the filtrate water that has passed through the pleat filter from the inside of the cylinder of the pleat filter to the outside of the case;
A ballast water treatment apparatus comprising: a discharge flow path for discharging discharged water that has not been filtered by the pleated filter to the outside of the case.   After the ballast water treatment device according to claim 6 is installed in the hull, seawater obtained from the outside of the hull is used as water to be treated, and after further killing treatment is performed on the filtered water treated by the ballast water treatment device A method for treating ballast water stored in the ship's body as ballast water.

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