JP6296069B2 - Ballast water treatment device and operation method of ballast water treatment device - Google Patents

Description

  The present invention relates to a ballast water treatment apparatus and an operation method thereof.

  Ballast water is loaded onto the ship to maintain the hull attitude or draft in a safe state. For example, after cargo is unloaded from the ship at the destination, water around the ship (seawater, fresh water, or brackish water) is collected, and the water is loaded into the ship as ballast water. Ballast water stored in the ship is discharged out of the ship at the port of call.

  In the case of ships sailing on international voyages, the area where ballast water is taken may be different from the area where ballast water is discharged. When organisms survive in ballast water, the organisms are moved to sea areas that are not their native habitat by discharging the ballast water from the ship. For this reason, there may arise a problem that the discharge of ballast water affects the marine ecosystem.

  In order to avoid this problem, devices and methods for purifying ballast water have been proposed so far. For example, Unexamined-Japanese-Patent No. 2011-194396 (patent document 1) discloses the processing apparatus for ballast water for ships. This processing apparatus has a filter arranged in a cylinder so as to surround an axis. The filter is provided so as to be rotatable about its axis. The treatment device filters the water to be treated while rotating the filter.

JP 2011-194396 A

  In the filtration device having the above-described configuration, an important point for stably and continuously filtering the water to be treated is to enhance the cleaning effect of the filter by the ejection of the water to be treated. An object of the present invention is to provide a ballast water treatment apparatus having a configuration for enhancing the cleaning effect of a filter, and an operation method thereof.

  A ballast water treatment apparatus according to an aspect of the present invention includes a cylindrical pleat filter that is rotatably held around a cylindrical axis, a drive mechanism that rotates the pleat filter, and a treatment to generate ballast water. A treated water channel for passing water, a treated water nozzle that extends from the treated water channel and flows out of the treated water toward the outer peripheral surface of the pleated filter, and is provided so as to surround the pleated filter. A case having an outer tube portion provided with a nozzle port of a treated water nozzle inside, a filtered water flow path for leading filtrate water permeated through the pleated filter from the inside of the pleated filter cylinder to the outside of the case, and not filtered by the pleated filter Adjust the differential pressure between the discharge flow path for discharging the discharged water to the outside of the case and the pressure of the water to be treated at the nozzle port of the water to be treated and the container pressure of the water to be treated in the case. And a differential pressure control mechanism for.

  According to the above, it is possible to enhance the cleaning effect of the filter provided in the ballast water treatment device.

It is a figure which shows the whole structure of the ballast water treatment system for ships provided with the ballast water treatment apparatus which concerns on one Embodiment of this invention, and the processing method of a ballast water. It is the schematic which showed schematically the structure of the filtration apparatus shown by FIG. It is sectional drawing along the III-III line of FIG. It is a perspective schematic diagram explaining the typical structure of the pleat filter shown by FIG. 2 and FIG. It is a figure explaining the force added to a pleat filter when to-be-processed water is filtered by passing to-be-processed water through a pleat filter. It is a figure which shows an example of the damage which arises in a pleat filter by pressure. It is a figure for demonstrating the pressure which arises in each part of a filtration apparatus. It is a schematic diagram for demonstrating the differential pressure | voltage adjustment mechanism which concerns on the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the differential pressure | voltage adjustment mechanism which concerns on the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the differential pressure | voltage adjustment mechanism which concerns on the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating the differential pressure | voltage adjustment mechanism which concerns on the 4th Embodiment of this invention. It is a schematic diagram for demonstrating the differential pressure | voltage adjustment mechanism which concerns on the 5th Embodiment of this invention.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described. In the following, the term “treated water” refers to water that is treated by a ballast water treatment system.

  (1) A ballast water treatment apparatus according to an aspect of the present invention is configured to generate a ballast water, a cylindrical pleat filter that is rotatably held around a cylindrical axis, a drive mechanism that rotates the pleat filter, and the like. The treated water flow path for passing the treated water, the treated water nozzle that extends from the treated water flow path and flows out the treated water toward the outer peripheral surface of the pleated filter, and is provided so as to surround the pleated filter A pleated filter, a case having an outer cylinder portion provided with a nozzle port of a water nozzle to be treated, a filtered water flow path for leading filtered water that has passed through the pleated filter from the inside of the pleated filter to the outside of the case, and The difference between the discharge flow path for discharging the unfiltered discharged water to the outside of the case, and the pressure of the water to be treated at the nozzle port of the water to be treated and the container pressure of the water to be treated in the case And a differential pressure control mechanism for adjusting.

  According to the above, it is possible to enhance the cleaning effect of the filter provided in the ballast water treatment device. The differential pressure between the pressure of the water to be treated at the nozzle port of the water to be treated and the container pressure of the water to be treated in the case is required to be within an appropriate range. When the differential pressure is small, the filtration ability of the water to be treated and the cleaning effect of the pleated filter are likely to be lowered. On the other hand, when the differential pressure is large, the pleated filter is easily damaged. Since the differential pressure can be adjusted by the differential pressure adjusting mechanism, the pleated filter can be effectively washed while filtering the water to be treated.

  (2) Preferably, the differential pressure adjusting mechanism is provided in the bypass channel, which connects the treated water channel and the case, bypasses the nozzle port, and introduces the treated water into the case. And a flow rate control mechanism for controlling the flow rate of the water to be treated flowing through the bypass flow path.

  According to the above, the differential pressure can be adjusted by adjusting the flow rate of the water to be treated flowing through the bypass flow path.

  (3) Preferably, the differential pressure adjusting mechanism includes a flow rate ratio control mechanism for controlling the ratio of the flow rate of filtrate water and the flow rate of discharged water.

According to the above, the differential pressure can be adjusted by adjusting the flow rate ratio.
(4) Preferably, the differential pressure adjusting mechanism is configured to change the opening area of the nozzle opening.

  According to the above, it is possible to adjust the pressure of the water to be treated ejected from the nozzle port by adjusting the opening area of the nozzle port. Therefore, the differential pressure can be adjusted.

  (5) Preferably, the differential pressure adjusting mechanism is configured to adjust the distance between the nozzle opening and the pleated filter.

  According to the above, the differential pressure can be adjusted by adjusting the distance between the nozzle opening and the pleated filter.

  (6) Preferably, a ballast water treatment apparatus is further provided with the control part for controlling a differential pressure regulation mechanism.

According to the above, the differential pressure can be automatically adjusted.
(7) The operation method of the ballast water treatment apparatus according to one aspect of the present invention is an operation method of the ballast water treatment apparatus having the following configuration. A ballast water treatment device includes a cylindrical pleat filter, a drive mechanism for rotating a pleat filter, and a treated water flow path for passing the treated water for generating ballast water, which is rotatably held around a cylindrical axis. And a to-be-treated water nozzle that extends from the to-be-treated water flow path and flows out of the to-be-treated water toward the outer peripheral surface of the pleated filter, and is provided so as to surround the pleated filter. A case having an outer cylindrical portion provided inside, a filtered water passage for leading filtered water that has permeated through the pleated filter from the inside of the cylinder of the pleated filter to the outside of the case, and discharged water that has not been filtered by the pleated filter outside the case And a discharge flow path for discharging to the outside. The operation method includes a step of discharging the water to be treated from the water nozzle to be treated toward the outer peripheral surface of the pleat filter while the pleat filter is rotated by the drive mechanism, and a nozzle of the water nozzle to be treated by the differential pressure adjusting mechanism. Adjusting the differential pressure between the pressure of the water to be treated in the mouth and the container pressure of the water to be treated in the case.

  According to the above, it is possible to enhance the cleaning effect of the filter provided in the ballast water treatment device.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram showing an overall configuration of a marine ballast water treatment system and a ballast water treatment method including a ballast water treatment apparatus according to an embodiment of the present invention. As shown in FIG. 1, a marine ballast water treatment system takes in water to be treated. For example, seawater is seawater. The water to be treated is sent to the pump 21 via the pipe 31. The pump 21 supplies the water to be treated to the filtration device 12 through the pipe 32. The filtration device 12 filters the water to be treated. The filtered filtered water is sent to the killing device 13 through the pipe 33. The discharged water that has not been filtered in the filtering device 12 is led out of the device through the pipe 35.

  The killing device is an ultraviolet irradiation device or an electrolysis device. The seawater that has undergone the killing process is sent to the tank 14 via the pipe 34 and stored as ballast water.

  FIG. 2 is a schematic diagram schematically showing the configuration of the filtration device 12 shown in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. Referring to FIGS. 2 and 3, cylindrical pleated filter 61 is arranged so as to surround an axis serving as a rotation center. The pleated filter 61 is rotatably attached around a central pipe 80 disposed at the center thereof. The central pipe 80 does not rotate.

  The cylindrical upper and lower surfaces of the pleated filter 61 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 63 is provided so as to cover the entire pleated filter 61. The case 63 includes an outer cylinder part 71, a lid part 72, and a bottom part 73. A discharge channel 65 connected to the pipe 33 is provided at the bottom 73.

  In order to introduce seawater as treated water, a treated water flow channel 66 and a treated water nozzle 62 are provided inside the case 63. The treated water channel 66 is connected to the pipe 32. The water nozzle 62 to be treated has a nozzle port 67. A nozzle port 67 is provided inside the outer cylindrical portion 71 of the case 63 so that the water to be treated flows out toward the outer peripheral surface of the pleated filter 61. For rotation of the pleat filter 61, a motor 90 is provided on the central axis of the pleat filter 61. An axis C indicates the central axis of the pleated filter 61 (cylinder). The motor 90 is driven by electric power from a drive control unit (not shown).

  According to the configuration shown in FIG. 2, the chemical solution inlet 70 is provided in the lid portion 72 of the case 63. However, it is not essential to provide the case 63 with a chemical injection port.

  The treated water nozzle 62 is configured to extend from the treated water flow channel 66. A nozzle port 67 is formed at the tip of the water nozzle 62 to be treated. The nozzle port 67 is disposed in the outer cylinder portion 71 of the case 63. The nozzle port 67 is formed so that the water to be treated flows out from the nozzle port 67 toward the outer peripheral surface of the pleated filter 61.

  The treated water passes through the treated water channel 66 and is ejected from the nozzle port 67 of the treated water nozzle 62. The water to be treated ejected from the nozzle port 67 is transmitted from the outside of the cylinder of the pleated filter 61 to the inside of the cylinder. As a result, the water to be treated is filtered. The water to be treated filtered by passing through the pleated filter 61 is guided to the filtered water flow path 64 through the water intake hole 81 provided in the central pipe 80 and flows out of the filtering device 12.

  Water that has not been filtered by the pleated filter 61 and turbid components that have settled on the bottom 73 of the case 63 are discharged to the outside of the filtration device 12 through the discharge channel 65. Thus, filtration is performed while the turbid component or the remaining water is continuously discharged. Thereby, the processing amount requested | required as a processing amount of to-be-processed water is securable.

  In the above operation, turbid substances such as organisms or particles adhere to the outer peripheral surface of the pleated filter 61. While the motor 90 rotates the pleated filter 61, water to be treated is ejected from the nozzle port 67. The suspended matter attached to the pleated filter 61 is easily removed by the pressure of the water to be treated. That is, according to this embodiment, the pleat filter 61 can be washed simultaneously with the filtering of the ballast water.

  FIG. 4 is a schematic perspective view illustrating a typical configuration of the pleated filter 61 shown in FIGS. 2 and 3. Referring to FIG. 4, a so-called pleated shape is formed by alternately folding a flat belt-like substrate. A cylindrical pleated filter is formed by joining both ends of a substrate formed in a pleat shape. The pleated filter has an outer end M and an inner end V.

  A porous resin sheet is used for the filter substrate. Examples of the material for the porous resin sheet include polyester, nylon, polyethylene, polypropylene, polyurethane, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and the like, such as a stretched porous body, a phase-separated porous body, and a nonwoven fabric. A porous structure is utilized. In order to perform filtration at a high flow rate, a nonwoven fabric made of polyester such as polyethylene terephthalate is particularly preferably used.

  FIG. 5 is a diagram illustrating the force applied to the pleated filter 61 when the water to be treated is filtered by passing through the pleated filter 61. In FIG. 5, five arrows indicate the direction in which the liquid to be processed is supplied from the outer end M side. The pleat is opened by the pressure P of the water to be treated ejected from the nozzle opening (not shown in FIG. 5). The treated water flows into the open part. Since the pleat filter 61 is rotating, the next pleat is opened and the previous pleat is closed. The treated water is discharged from the closed part. The suspended matter attached to the pleated filter 61 can be removed by the movement of the water to be treated accompanying the opening and closing of the pleats.

  The pressure P varies depending on the flow rate or pressure of the water to be treated. Depending on the configuration, vibration is applied to the pleated filter 61 or a force for bending the pleated filter 61 acts. When vibration or force is large, the pleat filter 61 may be damaged, or the durability of the pleat filter 61 may be reduced.

  FIGS. 6A and 6B are diagrams illustrating an example of breakage that occurs in the pleated filter 61 due to the pressure P. FIG. FIG. 6A is a diagram illustrating a state of the pleated filter 61 before breakage occurs. FIG. 6B is a diagram schematically showing the state of the pleated filter 61 at the time of breakage. As described above, the upper and lower sides of the pleated filter 61 are fixed for shape fixing and sealing. As shown in FIG. 5, when the pressure P is repeatedly applied in the direction of opening the pleats, the vicinity (part D) of the central portion of the pleat filter 61 is bent in the direction shown in FIG. Thereby, in the part D, a crack or a tear may arise and a filtration function may be impaired.

  In this embodiment, the object to be filtered is a liquid. The pressure that the pleated filter receives is larger than that of a gas such as air. For this reason, the pleated filter is easily damaged. It is required to open and close the pleat for effective cleaning while preventing damage to the pleat filter.

  FIG. 7 is a diagram for explaining the pressure generated in each part of the filtration device 12. With reference to FIG. 7, the pressure Pi is the pressure (inlet pressure) of the water to be treated in the water channel 66 to be treated. The pressure Ps is the pressure of the water to be treated ejected from the nozzle port of the water channel 66 to be treated. The pressure Pc is the pressure inside the case 63 (container pressure). The pressure Po is the pressure (outlet pressure) of the water to be treated that has passed through the pleated filter 61.

  The pressure Ps corresponds to a pressure obtained by subtracting the pressure loss due to the nozzle port from the inlet pressure (Pi). The pressure loss between the pressure Pi and the pressure Ps is constant if the opening area of the nozzle opening and the flow rate of the water to be treated are determined.

  The fluctuation of the pressure P shown in FIG. 5 corresponds to the fluctuation of the differential pressure Psc (= Ps−Pc) between the pressure Ps and the pressure Pc. This differential pressure Psc corresponds to a pressure for deforming the pleats.

  In this embodiment, the filtration device 12 includes a pressure adjustment mechanism for adjusting the differential pressure Psc. In one embodiment, the differential pressure Psc is set in the range of 5-10 kPa. Thereby, the pleat filter 61 can be effectively cleaned while preventing the pleat filter 61 from being damaged. When the differential pressure Psc is smaller than 5 kPa, the effect of cleaning the pleated filter 61 is weakened. On the other hand, if the differential pressure Psc is larger than 10 kPa, the possibility that the pleated filter 61 is generated increases. Hereinafter, each embodiment will be described in detail.

<First Embodiment>
FIG. 8 is a schematic diagram for explaining the differential pressure adjusting mechanism according to the first embodiment of the present invention. Referring to FIG. 8, differential pressure adjusting mechanism 68 includes a bypass passage 69 and a flow rate control valve 69a. The bypass channel 69 connects the water channel 66 to be treated and the case 63. The bypass channel 69 bypasses the nozzle port 67 of the treated water channel 66 and introduces the treated water into the case 63. The flow rate control valve 69 a controls the flow rate of the water to be treated that flows through the bypass channel 69. Thereby, the pressure Ps can be adjusted. Therefore, the differential pressure Psc can be adjusted. The bypass channel 69 is connected to the case 63 so that the water flow from the bypass channel 69 is in a direction along the circumferential direction of the pleat filter 61. The bypass channel 69 may be connected to the case 63 at a position excluding the side surface of the pleated filter 61.

<Second Embodiment>
FIG. 9 is a schematic diagram for explaining a differential pressure adjusting mechanism according to the second embodiment of the present invention. As shown in FIG. 9, the differential pressure adjusting mechanism 68 includes a valve 53 and a valve 56. The valve 53 is provided in the filtered water channel 64. The valve 56 is provided in the discharge channel 65.

  During the filtration operation, the water 51 to be treated is guided to the water channel 66 to be treated by opening the valve 51. By opening the valve 53, the filtered water W2 is led out from the case 63 to the outside. When the valve 56 is opened, the water to be treated that has not been filtered is discharged as effluent W3 together with turbid components.

  At least one of the valve 53 and the valve 56 is a flow control valve. By adjusting the opening degree of the flow control valve, the ratio of the flow rate of the filtered water W2 and the flow rate of the discharged water W3 can be adjusted. By adjusting the flow rate ratio, the differential pressure Psc can be adjusted. The valve 53 and the valve 56 constitute a flow rate control mechanism. The flow rate control mechanism may be used together with the bypass passage 69 and the flow control valve 69a shown in FIG.

<Third Embodiment>
FIG. 10 is a schematic diagram for explaining a differential pressure adjusting mechanism according to the third embodiment of the present invention. As shown in FIG. 10, the differential pressure adjusting mechanism 68 is configured to change the opening area of the nozzle port 67. The nozzle port 67 includes side wall portions 62c and 62d, an upper portion 62a, and a lower portion 62b. The opening area of the nozzle port 67 is represented by L × W. L is the distance between the upper part 62a and the lower part 62b. W is the width of the nozzle port 67, that is, the distance between the side wall part 62c and the side wall part 62d.

  In the form shown in FIG. 10, the differential pressure adjusting mechanism 68 is configured by a screw for changing the width W of the nozzle port 67. By turning the screw, the side wall 62d approaches or moves away from the side wall 62c. As the width W changes, the opening area of the nozzle port 67 changes. Thereby, since the pressure Ps of the to-be-processed water ejected from the nozzle port of the to-be-processed water flow path 66 can be changed, the differential pressure Psc can be adjusted. The configuration shown in FIG. 10 can also be applied to the first embodiment, the second embodiment, or a combination thereof.

<Fourth embodiment>
FIG. 11 is a schematic diagram for explaining a differential pressure adjusting mechanism according to the fourth embodiment of the present invention. As shown in FIG. 11, the for-treatment water nozzle 62 is slidable in a direction penetrating the case 63. The differential pressure adjusting mechanism 68 is configured to adjust the distance between the nozzle port 67 of the water nozzle 62 to be treated and the pleated filter 61. For example, the differential pressure adjusting mechanism 68 may be a screw for fixing the position of the water nozzle 62 to be treated.

  The pressure Ps increases as the nozzle port 67 approaches the pleat filter 61. Conversely, the pressure Ps decreases as the nozzle port 67 moves away from the pleated filter 61. The pressure Ps can be adjusted by adjusting the distance between the nozzle port 67 and the pleated filter 61. As a result, the differential pressure Psc can be adjusted. The configuration according to the fourth embodiment can also be applied to each of the first embodiment, the second embodiment, and the third embodiment, and any combination thereof.

<Fifth embodiment>
FIG. 12 is a schematic diagram for explaining a differential pressure adjusting mechanism according to the fifth embodiment of the present invention. As shown in FIG. 12, the differential pressure adjusting mechanism 68 is controlled by the control unit 100. The control unit 100 is realized by a computer such as a microcomputer. Thereby, the differential pressure Psc can be automatically adjusted. That is, the control unit 100 performs a step of adjusting the differential pressure Psc between the inlet pressure of the water to be treated in the nozzle port 67 of the water to be treated nozzle 62 and the container pressure of the water to be treated in the case 63. The other parts of the configuration shown in FIG. 12 are the same as the corresponding parts of the first embodiment.

  Similarly, the valve 53 and the valve 56 in the second embodiment may be controlled by the control unit 100. Further, in the third and fourth embodiments, the differential pressure adjusting mechanism may be controlled by a computer. With such a configuration, in the third and fourth embodiments, the control unit 100 can automatically adjust the differential pressure Psc.

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

12 Filtration device 13 Killing device 14 Tank 21 Pumps 31-35 Piping 51, 53, 56 Valve 61 Pleated filter 62 Water to be treated nozzle 62a Upper part (nozzle port)
62b Lower part (nozzle port)
62c, 62d Side wall (nozzle port)
63 Case 64 Filtrated water flow path 65 Discharge flow path 66 Processed water flow path 67 Nozzle port 68 Differential pressure adjusting mechanism 69 Bypass flow path 69a Flow rate control valve 70 Chemical liquid injection port 71 Outer cylinder part 72 Lid part 73 Bottom part 80 Central pipe 81 Water intake hole 90 Motor 100 Control part C Axis D part (pleat filter)
M Outer end (pleated filter)
P, Pc, Pi, Po, Ps Pressure Psc Differential pressure V Inner end (pleat filter)
W Width W1 Water to be treated W2 Filtered water W3 Effluent

Claims (7)

A cylindrical pleated filter held rotatably about a cylindrical axis;
A drive mechanism for rotating the pleat filter;
A treated water flow path for passing the treated water for generating ballast water,
A to-be-treated water nozzle that extends from the to-be-treated water flow path and flows out the to-be-treated water toward the outer peripheral surface of the pleated filter,
A case provided to surround the pleated filter, and having an outer tube portion provided with a nozzle port of the water nozzle to be treated inside;
A filtered water flow path for leading filtered water that has passed through the pleated filter from the inside of the cylinder of the pleated filter to the outside of the case;
A discharge flow path for discharging discharged water that has not been filtered by the pleat filter to the outside of the case;
Ballast water treatment comprising a differential pressure adjusting mechanism for adjusting a differential pressure between the pressure of the water to be treated at the nozzle port of the water to be treated nozzle and the container pressure of the water to be treated in the case. apparatus. The differential pressure adjusting mechanism is
A bypass flow path that connects the treated water flow path and the case, bypasses the nozzle opening, and introduces the treated water into the case;
The ballast water treatment apparatus according to claim 1, further comprising: a flow rate control mechanism that is provided in the bypass flow path and controls a flow rate of the water to be treated that flows through the bypass flow path. The differential pressure adjusting mechanism is
The ballast water treatment apparatus according to claim 1, comprising a flow rate ratio control mechanism for controlling a ratio between the flow rate of the filtered water and the flow rate of the discharged water.   The ballast water treatment apparatus according to any one of claims 1 to 3, wherein the differential pressure adjusting mechanism is configured to change an opening area of the nozzle port.   The ballast water treatment device according to any one of claims 1 to 4, wherein the differential pressure adjustment mechanism is configured to adjust a distance between the nozzle port and the pleated filter.   The ballast water treatment apparatus according to any one of claims 1 to 5, further comprising a control unit for controlling the differential pressure adjusting mechanism. A cylindrical pleated filter held rotatably about a cylindrical axis;
A drive mechanism for rotating the pleat filter;
A treated water flow path for passing the treated water for generating ballast water,
A to-be-treated water nozzle that extends from the to-be-treated water flow path and flows out the to-be-treated water toward the outer peripheral surface of the pleated filter,
A case provided to surround the pleated filter, and having an outer tube portion provided with a nozzle port of the water nozzle to be treated inside;
A filtered water flow path for leading filtered water that has passed through the pleated filter from the inside of the cylinder of the pleated filter to the outside of the case;
An operation method of a ballast water treatment apparatus having a discharge flow path for discharging discharged water that has not been filtered by the pleated filter to the outside of the case,
In a state where the pleated filter is rotated by the drive mechanism, the treated water flows out from the treated water nozzle toward the outer peripheral surface of the pleated filter;
Adjusting the differential pressure between the pressure of the water to be treated at the nozzle port of the water to be treated nozzle and the container pressure of the water to be treated in the case by a differential pressure adjusting mechanism. Operation method of water treatment equipment.

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