JP2006239530A - Manufacturing method and manufacturing apparatus of ballast water for ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method and the manufacturing apparatus of ballast water for a ship by which plankton and bacteria in seawater at a port region where a ship anchors are efficiently removed without using a method for annihilating both plankton and bacteria. <P>SOLUTION: The manufacturing method of the ballast water for the ship includes: a plankton removing process of removing plankton in the seawater by passing the seawater at the port region where the ship anchors through a filter membrane of ≥2μm pore size; and a bacteria removing process of removing bacteria in the seawater by passing the seawater from which the plankton are removed through a bacteria filtering membrane of <1.0μm pore size. Membrane-filtered water obtained by the bacteria removing process is used as the ballast water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for manufacturing marine ballast water (hereinafter also simply referred to as “ballast water”) from which microorganisms loaded to stabilize the center of gravity during navigation of the marine vessel are removed.

  Crude oil tankers, ore carriers, car carriers, etc. may sail with low or no cargo. At that time, the hull is lifted by buoyancy, and the screw and rudder are not submerged under the surface of the water, or the hull on the surface of the water is greatly affected by the wind and the maneuverability is impaired, making it extremely dangerous. For this reason, in order to adjust the buoyancy at the time of navigation, a normal ship carries a ballast water of 30 to 40% by weight of the normal load.

  For example, transportation by crude oil tankers is a round trip between oil-producing countries and consuming countries, and there is no cargo when navigating from consuming countries to oil-producing countries. Yes. On the other hand, a ship loaded with ballast water discharges ballast water in the sea near the oil producing country or at a port and loads crude oil.

  In recent years, ballast water discharged from ships has brought planktons and bacteria that do not inherently live in specific waters, resulting in the destruction of marine ecosystems and only causing serious damage to the lives of the inhabitants. Instead, the destruction of the global marine environment has occurred, making it a serious international problem. For this reason, various methods have been studied on an international scale for the purpose of removing planktons and bacteria in ballast water.

  According to the Ocean Science and Engineering Society 2003 Fall Meeting Proceedings 73-78, ballast water obtained by passing seawater through a high-speed filter equipped with a filter with a pore size of 5 μm has a phytoplankton removal rate of 97.6. Although it is disclosed that the guideline figures discussed in the Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) in July 2003 are achieved, about bacteria other than planktons Not considered. However, it is obvious that a micro-organism that is a bacteria having a size of 5 μm or less cannot be removed with a filter having a pore size of 5 μm.

As a method of removing bacteria other than plankton in the seawater pumped as ballast water, for example, a method of heating the seawater to kill the bacteria (Japanese Patent Laid-Open No. 2003-181443), irradiating the seawater with ultraviolet rays A method of inactivating bacteria (Japanese Patent Publication No. 2000-515803, Japanese Patent Laid-Open No. 11-265684), a method of treating with iodine (Japanese Patent Publication No. 2002-504851), and a method of treating with hypochlorous acid (Japanese Patent Laid-Open No. 04-322788) has been proposed.
Ocean Science and Technology Society 2003 Autumn Conference Lecture Collection, pp. 73-78 JP 2003-181443 A (Claims) JP 2000-515803 A (Claims) JP 11-265684 A (Claims) Japanese translation of PCT publication No. 2002-504851 (Claims) JP 04-322788 A (Claims) JP 2003-154360 A (Claims)

  However, the method of heating seawater is not economical depending on the heating energy procurement means, and it is difficult to completely kill bacteria. In addition, the method of irradiating seawater with ultraviolet rays requires a huge amount of power to kill or inactivate all the bacteria, and in order to treat high flow rate seawater, many UV devices are installed in parallel. Increase the installation cost of the equipment. In addition, the method of treating seawater with chemicals such as iodine and hypochlorous acid requires a high concentration of chemicals to be killed depending on the type of bacteria, is not economical, and is contained in the discharged ballast water. Problems with the environmental impact of residual drugs also arise.

  As described above, the method of killing bacteria in seawater is difficult to completely kill bacteria, and there is a concern about the influence of contamination by carcasses on the ecosystem. Furthermore, since a small amount of bacteria remaining without being killed grow during transportation, it is desired to develop a method for completely removing these bacteria. Moreover, although the method of removing the bacteria in seawater by letting seawater pass through a microfiltration membrane is known (Unexamined-Japanese-Patent No. 2003-154360), the membrane filtration water obtained by this method is washing | cleaning of seafood, etc. It is not used for ship ballast water.

  Accordingly, an object of the present invention is to provide a ship ballast water manufacturing method and a manufacturing apparatus that efficiently remove planktons and bacteria in seawater in a harbor area where the ship is anchored together by a method other than the method of killing together. There is.

  Under such circumstances, the present inventors have conducted intensive studies. As a result, the seawater has a relatively large size such as plankton, seafood larvae and eggs, and bacteria (bacteria). Micro-organisms with a relatively small size are included, seawater is passed through a filtration membrane having a pore diameter of 2 μm or more to remove planktons in advance, and the treated water is further passed through a filtration membrane having a pore diameter of 1 μm or less. Then, it was found that if bacteria were removed, ballast water from which planktons and bacteria were almost completely removed could be produced within a short berthing time, and the present invention was completed.

  That is, the present invention relates to a plankton removal process for removing planktons in seawater by passing seawater in a harbor area where a ship is anchored through a filter membrane having a pore size of 2 μm or more; It has a bacteria removal process of removing bacteria in seawater by passing through a bacteria filtration membrane of less than 0 μm, and the membrane filtered water obtained in the bacteria removal process is used as a ballast water A method for producing ballast water is provided.

  The present invention also provides the method for producing ballast water for a ship, wherein the filtration membrane having a pore diameter of 2 μm or more is a metal filtration membrane. The present invention also provides the method for producing ballast water for ships, wherein the bacterial filtration membrane is a hollow fiber membrane. The present invention further provides a method for producing marine ballast water, further comprising a backwashing step of washing the bacterial filtration membrane by backwashing. Moreover, this invention provides the manufacturing method of the said ballast water for ships which removes at least the oil component in seawater beforehand before a plankton removal process.

  The present invention also provides a seawater supply means for supplying seawater in a harbor area where a ship is anchored, a filtration device having a filtration membrane having a pore diameter of 2 μm or more for removing planktons in the supplied seawater, and planktons being removed. It is intended to provide a marine ballast water production apparatus characterized by having a filtration device provided with a bacteria filtration membrane having a pore diameter of less than 1.0 μm for removing bacteria in seawater.

  Moreover, this invention provides the said ballast water manufacturing apparatus for ships which installs the oil removal apparatus which removes at least the oil component in seawater in the front | former stage of the filtration apparatus provided with the said filter membrane with a hole diameter of 2 micrometers or more. Moreover, this invention provides the said ballast water manufacturing apparatus for ships further provided with the backwashing water supply means which supplies backwashing water to the said bacteria filtration membrane apparatus. Moreover, this invention provides the said ballast water manufacturing apparatus for ships whose said bacteria filtration membrane apparatus is a pressurization type hollow fiber membrane apparatus or an immersion type hollow fiber membrane apparatus.

  According to the present invention, planktons and bacteria in seawater used as ballast water can be effectively removed with a filtration membrane installed in two stages in series. Planktons and bacteria that do not inhabit are not brought in, and the marine environment is not destroyed. Further, if the membrane filtered water is stored in, for example, a ballast water storage tank, it can be pumped into the ship as ballast water when necessary. Moreover, when performing each said process on a ship, the apparatus and installation space installed on land, and a land worker become unnecessary. In addition, if a metal filtration membrane is used for the previous filtration membrane and a hollow fiber membrane is used for the subsequent filtration membrane, the entire apparatus can be made compact and can be easily recovered by washing the membrane surface, and substantially continuous water flow is possible. This makes it possible to supply the ballast water to the ship within a short berthing time without extending the berthing period.

  In the method for producing ballast water according to the present invention, the seawater in the harbor area where the ship is anchored is not particularly limited, but other than planktons and bacteria, usually contains 1 to 1000 ppm of oil, and the turbidity is 1 to 100 degrees. The sea water. In the present invention, plankton refers to those having a size of 5 μm or more, and includes plankton usually classified into phytoplankton and zooplankton, as well as larvae and eggs of seafood. Specific examples of planktons include daphnia larvae, North Pacific starfish larvae, Asian kelp larvae, zebra clam larvae, and toxic algae. In the present invention, bacteria refer to micro-organisms of less than 5 μm, and examples include Escherichia coli, Vibrio cholerae, enterococci and the like. Bacteria are the smallest and are about 0.3 to 0.5 μm.

  The plankton removal step of the method for producing ballast water of the present invention is a step of removing planktons in seawater by passing seawater through a filtration membrane (pre-stage filtration membrane) having a pore diameter of 2 μm or more and usually 2 to 20 μm. Although it does not restrict | limit especially as a filtration membrane with a hole diameter of 2 micrometers or more, A metal filtration membrane, an organic filtration membrane, etc. are mentioned, Among these, a metal filtration membrane is preferable. Filters using organic filtration membranes include, for example, wind-type cartridge filters wound with polypropylene or the like, cartridge filters in which a nonwoven fabric or membrane filter is folded into a pleat shape, slit shapes inclined at a predetermined angle with respect to the radial direction An element body formed by laminating a ring-shaped flat plate made of polypropylene having a plurality of grooves. Of these, the cartridge type is not economical because it cannot normally be backwashed and is not economical because it is disposable. In addition, the replacement operation is complicated and not particularly suitable for devices on ships. In addition, the laminated element body has a drawback that the filtration area per apparatus volume is small and the apparatus space is increased because only the slit-shaped grooves formed by stacking ring-shaped flat plates are filtered. On the other hand, metal filtration membranes can increase the strength and increase the filtration speed, so that the device can be made compact by about 1/5 to 1/10 compared to organic filtration membranes, and the membrane surface can be further cleaned. This is preferable in that it can be performed by a simple method using hot water or steam.

  The pore diameter of the metal filtration membrane is displayed as a nominal value, and for example, a nominal pore diameter of 2.5 μm to 20 μm is suitable. The upper limit of the pore size of the filtration membrane used in the plankton removal process is not particularly limited, but if it is too large, the plankton removal rate will decrease, and clogging of the subsequent bacterial filtration membrane will be promoted. It is not preferable and is usually 50 μm.

  Although it does not restrict | limit especially as a metal filtration membrane, The mesh-like filter etc. which laminated | stacked and fixed the several sheets of the mesh-like sheet body etc. which laminated | stacked and sintered the felt of metal fibers of corrosion-resistant metal, such as stainless steel, etc. are mentioned. A filtration device incorporating such a metal filtration membrane is usually of a total filtration method. In addition, if the rotary filtration device is provided with a cylindrical metal filtration membrane around the pipe-shaped axis that is a filtrate outflow pipe, and a jet port for high-speed jet flow is provided in the vicinity of the metal filtration membrane surface, Planktons collected on the membrane surface while performing continuous water flow can be frequently washed with a high-speed water flow, which is preferable in that the filtration time can be shortened. Further, the plankton removal rate in the plankton removal step of the present invention is not particularly limited, but a higher removal rate is preferable in that it does not adversely affect clogging of the subsequent bacterial filtration membrane.

  The bacteria removal step of the method for producing ballast water of the present invention removes bacteria in seawater by passing the seawater from which planktons have been removed through a bacteria filtration membrane (rear filtration membrane) having a pore diameter of less than 1.0 μm. It is a process. If seawater is passed directly through a bacterial filtration membrane with a pore diameter of less than 1.0 μm, both planktons and bacteria can be removed, but it is necessary to frequently perform backwashing, or the eyes of the filtration membrane are blocked early. It may become impossible to regenerate. In contrast, in the present invention, in the plankton removal process, planktons of 2 μm or more in the seawater and other foreign matters are removed, and in the bacteria removal process, the roughly treated primary treated water is treated with bacteria. Since the treatment is performed with a filter membrane, the filtration efficiency is improved. Examples of the filtration bacteria filtration membrane include microfiltration membranes (MF) such as hollow fiber membranes, flat membranes, tubular membranes, and ultrafiltration membranes (UF). Among these, the hollow fiber membrane is preferable in that the filtration area per unit volume can be maximized.

  A hollow fiber membrane uses a large number of hollow fibers arranged in parallel, has a hollow structure, and further communicates with holes forming the hollow structure, and a large number of pores communicating with the holes on the membrane surface. There are external pressure type and internal pressure type. In the present invention, when a microfiltration membrane is used as the bacterial filtration membrane, the pore diameter of the hollow fiber membrane is 0.01 to 0.4 μm, preferably 0.01 to 0.3 μm. Moreover, when using an ultrafiltration membrane, it is 0.002-0.01 micrometer as a diameter of the pore of a hollow fiber membrane. The size of bacteria in seawater is usually several μm, and the smallest is about 0.3 to 0.5 μm. Therefore, if the hollow fiber membrane with the above pore diameter is used, these bacteria in seawater It can be almost completely removed. Also, backwashing is performed to remove bacteria attached to the membrane surface and restore its filtration ability. Separately from this backwashing, bubbles are bubbled from the outside of the membrane surface during filtration to create a membrane surface. It is preferable to use an external pressure type hollow fiber membrane in terms of being able to perform an operation of peeling and removing bacteria attached to the surface.

  The hollow fiber membrane is used as a pressure type hollow fiber membrane device or an immersion type hollow fiber membrane device. The method using a pressurized hollow fiber membrane device is a method of removing bacteria in seawater by supplying seawater to a hollow fiber loaded in a pressure vessel with a pressure pump. The method using the submerged hollow fiber membrane device is a method of removing bacteria in the seawater by sucking the inside of the hollow fiber of the device immersed in the seawater storage tank with a suction pump. In addition, as described above, both the pressure type hollow fiber membrane device and the immersion type hollow fiber membrane device generate fine bubbles from below the hollow fiber membrane, and appropriately peel off bacteria attached to the hollow fiber membrane, Filtration can be continued while washing the surface of the substrate.

  Examples of the material for the microfiltration membrane used in the present invention include polyethylene, polypropylene, polyvinyl alcohol, polysulfone, polyvinylidene chloride, polyvinylidene fluoride, chlorinated polyethylene, chlorinated polypropylene, polyacrylonitrile, and cellulose acetate.

  The method for passing seawater through the bacterial filtration membrane is not particularly limited, but two or more bacterial filtration membrane devices incorporating the bacterial filtration membrane can be arranged in parallel. In this case, even if one bacterial filtration membrane device is in the backwashing step, another bacterial filtration membrane device can also carry out the bacteria removal step, and a large amount of membrane filtered water can be obtained continuously. it can.

  Moreover, in the manufacturing method of the ballast water of this invention, it further has the process of wash | cleaning a bacteria filtration membrane by backwashing. In the bacteria removal process, as time elapses, bacteria and the like that cause clogging of the membrane adhere to the bacterial filtration membrane and the membrane differential pressure increases at the inlet and outlet of the membrane. For this reason, the filtration of seawater is stopped, and the bacterial filtration membrane is backwashed using the membrane filtration water as washing water. By performing the back washing step, the filtration function of the bacterial filtration membrane is restored. When the backwashing process is completed, the process moves to the bacteria removal process again, and this is repeated to enable filtration over a long period of time. In the present invention, since the planktons and other floating substances are roughly collected by the front filtration membrane, clogging of the rear bacterial filtration membrane is suppressed. For this reason, the time for performing backwashing can also be shortened, and the processing amount per unit time can be increased.

  In the method for producing ballast water of the present invention, the oil in the seawater is removed in advance before the plankton removal process, thereby preventing clogging of the filtration membrane used in the plankton removal process and the bacteria removal process. It is preferable at the point which can prevent the fall of capability. In other words, oil in seawater is also captured by the filtration membrane, but unlike planktons and other turbidity, if oil adheres to the membrane surface, it cannot be easily removed by the bubbling or backwashing process described above and filtered. It clogs the membrane and causes a reduction in filtration capacity.

  The method for removing oil from seawater is not particularly limited, and a known oil / water separator (oil remover) can be used. As the oil / water separator, a device using a hydrophobic adsorbent is preferable because it is a simple method and exhibits a high oil adsorption capability. Examples of the hydrophobic adsorbent include a non-woven filter made of a material such as lipophilic polyethylene or polypropylene, a powder, and a hollow fiber membrane. Specifically, when the oil adsorbent “Diamarus (registered trademark of Mitsubishi Rayon Co., Ltd.)” is used, the oil can be removed extremely efficiently. For example, seawater with an oil content of 0.05 to 1.0% can be converted into seawater with an oil content of 0.0005 to 0.002% by the oil content removal step of seawater.

  When the ship ballast water production method of the present invention is performed on land, the membrane filtrate obtained in the bacteria removal step is stored in the ballast water storage tank. Ballast water can be fed at a high flow rate, and the berthing period of the ship is not extended for pumping ballast water. Moreover, when performing the manufacturing method of the ballast water for ships of this invention on a ship, the apparatus and installation space which are installed on land, and a land worker become unnecessary. When producing ballast water on a ship, the ballast water is mainly produced while the ship is anchored, and the ballast water from which planktons and bacteria have been removed is supplied to the ballast water tank in the ship, and a predetermined amount Is loaded.

  The apparatus for producing ballast water of the present invention may be installed on land or on a ship. As an apparatus for producing ballast water on land, for example, a filtration apparatus comprising seawater supply means for supplying seawater in a harbor area where a ship is anchored, and a filtration membrane having a pore diameter of 2 μm or more for removing planktons in the supplied seawater. A filtration device including a bacteria filtration membrane having a pore diameter of less than 1.0 μm for removing bacteria in seawater from which plankton has been removed, and backwash water supply means for supplying backwash water to the bacteria filtration membrane device And a ballast water storage tank for storing the permeated water of the bacteria filtration membrane, and preferably, an oil removal device or a turbidity removal device for removing oil in seawater is provided upstream of the filtration device having a filtration membrane having a pore diameter of 2 μm or more. Install. The seawater supply means is means for supplying seawater to a filtration device including a filtration membrane having a pore diameter of 2 μm or more, and includes a seawater pump and a seawater intake pipe having one end in seawater and the other end connected to the seawater pump. Is. The number of installed ballast water tanks, tank type, etc. are not particularly limited. Further, as related equipment of the manufacturing apparatus of the present invention, there are a liquid feed pump for pumping ballast water in a ballast water storage tank, and a liquid feed pipe for connecting the liquid feed pump to a ballast water tank of a ship anchored.

  As the ballast water manufacturing apparatus of the on-ship installation form, the same configuration can be adopted except that the installation of the ballast water storage tank can be omitted in the above-mentioned ballast water manufacturing apparatus of the on-land installation form. An example of a ballast water production apparatus installed on a ship will be described with reference to the schematic diagram of FIG. The ballast water production apparatus 1 is provided with a seawater supply pump 13, a filtration apparatus 2, a hollow fiber membrane type bacteria filtration apparatus 3, and a backwash water storage tank 14 in this order from the upstream side. A seawater intake hose 131 having one end in seawater is provided on the suction side of the seawater supply pump 13, and the hollow fiber membrane type bacteria filtration device 3 and the backwash water storage tank 14 are connected by a treated water pipe 7. The backwash water storage tank 14 and the ballast water tank 15 are connected by a treated water pipe 7a. In addition, a backwash pump 9 is provided so that the filtered water in the backwash water storage tank 14 can be backwashed by the backwash pipe 10. Note that the backwashing may use air pressure by an air compressor or the like. The backwash drainage (not shown) discharged from the filtration device 2 and the hollow fiber membrane type bacteria filtration device 3 is discarded in seawater or on land. In addition, an oil-water separation apparatus and a turbidity removal apparatus can be installed in the front | former stage of the filtration apparatus 2 provided with the filtration membrane of 2 micrometers or more in pore diameter as needed. Further, the installation of the seawater supply pump 13 including the seawater intake hose 131 may be omitted, and a ballast water supply pump (not shown) including an existing seawater supply port attached to the ship hull 16 may be used. In this case, the filtration device 2, the hollow fiber membrane type bacteria filtration device 3, the backwash water storage tank 14 and the like provided with a filtration membrane having a pore diameter of 2 μm or more may be installed downstream of the existing ballast water supply pump. Cost of expenses can be reduced. The ship on which the ballast water production apparatus 1 is installed is not particularly limited as long as it has a ballast water tank.

  In the apparatus for producing ballast water of the present invention, if a metal filter is used as a filtration membrane having a pore diameter of 2 μm or more, the strength can be increased and the filtration rate can be increased as compared with those using an organic filtration membrane. The apparatus and the entire manufacturing apparatus can be made compact. In addition, it is easy to recover by cleaning the membrane surface of the metal filtration membrane, enabling substantially continuous water flow, supplying ballast water to the ship within a short berthing time, and extending the berthing period. Absent.

  EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely illustrative and does not limit the present invention.

  Seawater (hereinafter referred to as “raw seawater”) in port A in Japan where the ship is anchored was treated under the following operating conditions using the following ballast water production apparatus. The total plankton number and the bacterial number of raw seawater, primary treated water and secondary treated water (membrane filtered water) were measured by the following measuring methods. Moreover, the water flow time until the water flow differential pressure in the hollow fiber membrane type bacteria filtration device 3 reached 0.1 MPa and the differential pressure recovery rate of each filter device by backwashing were measured. The results are shown in Table 1. In Table 1, “Unmeasurable” of the number of primary treated water bacteria is a large number of bacteria and could not be measured. The raw seawater was collected from a depth of 3 m from the sea surface. Its turbidity was 3 degrees, the total plankton number was 5000 or more, and the number of bacteria was too many to measure.

(Ballast water production equipment)
The apparatus shown in FIG. 2 was used. The ballast water production apparatus 20 includes a raw seawater storage tank 31, a plankton filtration apparatus 2 having the following specifications, a hollow fiber membrane type bacteria filtration apparatus 3 having the following specifications, and a secondary treated water storage tank 6 arranged in this order. A metal filter 28 is loaded inside the plankton filter device 2, and a hollow fiber membrane element 5 is loaded inside the hollow fiber membrane type bacteria filter device 3. The raw seawater storage tank 31 and the plankton filter device 28 were connected by a raw seawater supply pipe 23 and the raw seawater pump 13 was installed. Further, the plankton filtration device 2 and the hollow fiber membrane type bacteria filtration device 3 are connected by a primary treated water supply pipe 27, and the secondary treatment water tube 7 is connected between the hollow fiber membrane type bacteria filtration device 3 and the treated water storage tank 6. An air compressor 9 a was connected to the primary treated water supply pipe 27 and the secondary treated water pipe 7. In addition, the hollow fiber membrane type bacteria filtration device 3 is scrubbed with air from below the hollow fiber membrane element 5 through the primary treated water supply pipe 27 by the air compressor 9 a and treated through the secondary treated water pipe 7. It was made possible to backwash the treated water by feeding air pressure from the water side. Similarly, the plankton filter device 2 can be back-treated with treated water by pneumatically feeding from the treated water side via the primary treated water supply pipe 27. In the ballast water production apparatus 20, the plankton filtration apparatus 2 and the hollow fiber membrane-type bacteria filtration apparatus 3 are directly connected by the primary treated water supply pipe 27. A primary treated water storage tank can also be installed in the supply pipe 27.

(Plankton filtration device)
The plankton filter device 3 is made of stainless steel with a fractional pore diameter of 3 μm (nominal), and a metal filter (“Fuji Metal Fiber Filter”; manufactured by Fuji Filter Industrial Co., Ltd.) with a diameter of 1.4 cm, a length of 20 cm, and an effective membrane area of 85 cm ² is used. Two were used, and the seawater was treated with a total filtration water flow rate of 1.2 m ³ / day.

(Hollow fiber membrane type bacteria filtration device)
The hollow fiber membrane type bacteria filtration device 3 is a hollow fiber element (outer diameter 5 cm, length 44 cm, effective membrane area 0.4 m ²⁾ made of polyethylene with a pore diameter of 0.1 μm and bundled hollow fibers with an outer diameter of 0.51 mm Sea water was treated with a total filtration flow rate of 1.2 m ³ / day using “Sterapore” (manufactured by Mitsubishi Rayon Co., Ltd.).

(how to drive)
Raw seawater was supplied to the ballast water production apparatus 20 at a throughput of 1.2 m ³ / day. The treatment was carried out by continuous water flow in the order of the plankton filtration device 2 and the hollow fiber membrane type bacteria filtration device 3 by the raw seawater pump 17. In the backwashing, when the water flow differential pressure in the hollow fiber membrane type bacterial filtration device 3 reaches 0.1 MPa, the air compressor 9a performs the treatment of the plankton filtration device 2 and the hollow fiber membrane type bacterial filtration device 3. The test was carried out by opening the inlet valve (not shown) of each device in a state where air pressure of 0.3 MPa was applied to the water pipe. In addition, backwashing performed the planktons filtration apparatus 2 after performing the hollow fiber membrane type bacteria filtration apparatus 3. FIG. After backwashing for a predetermined time, the same water flow treatment was performed again, and the recovery rate was determined by the differential pressure of the filtration device. Prior to the backwashing, the hollow fiber membrane-type bacteria filtration device 3 performed scrubbing backwashing in which air was pumped from the air compressor 9a from below the hollow fiber element to vibrate the yarn.

(Measurement method of plankton number)
Immediately after collecting the sample, 1 ml was taken on a plankton counting plate (manufactured by Koiso Co., Ltd.), and the phytoplankton number was counted with a microscope.

(Method for measuring the number of bacteria)
The number of bacteria was measured by a culture method according to JIS K 0550 using a bacteria measurement kit (trade name Analysis Monitor; manufactured by Millipore) having a sterile 0.45 μm pore size filter. A sample was collected from a sampling valve set in the immediate vicinity of each device by a disposable sterile plastic syringe, and 50 ml was sampled.

  The apparatus and operation method were the same as in Example 1 except that the fractional pore diameter of the metal filter of the plankton filter 2 was changed to 3 μm and the fractional pore diameter was 20 μm. The results are shown in Table 1.

  The same apparatus and operation method as in Example 1 were used except that the hole diameter of the hollow fiber of the hollow fiber membrane type bacteria filtration device 3 was changed to 0.12 μm and the hole diameter was 0.22 μm. The results are shown in Table 1.

  The apparatus and operation method were the same as in Example 2 except that the hole diameter of the hollow fiber of the hollow fiber membrane type bacteria filtration device 3 was changed to 0.12 μm and the hole diameter was 0.22 μm. The results are shown in Table 1.

Except that scrubbing backwashing was omitted, the same apparatus and operation method as in Example 1 were used. The results are shown in Table 1.
Comparative Example 1
The same apparatus and operation method as in Example 1 were used except that the metal filter loaded in the plankton filter device 2 was removed and the raw seawater was temporarily treated.

  As is clear from Table 1, Examples 1 to 5 can remove most of the phytoplankton by the primary treatment water, and therefore increase the water flow differential pressure of the hollow fiber membrane type bacterial filtration device used in the secondary treatment. As compared with Comparative Example 1 in which the primary treatment is not performed, it can be greatly suppressed. In addition, both metal filters and hollow fiber membranes can be easily recovered by cleaning the membrane surface in a short time by backwashing, etc., so that the amount of processing per unit time is high and useful for ship-mounted types where installation space is limited. It has been found useful in large ballast vessels with limited berthing time.

It is a schematic diagram which shows an example of the manufacturing apparatus of the ballast water installed on a ship. It is a flowchart of the ballast water manufacturing apparatus used in Example 1.

Explanation of symbols

2 Plankton filter device 3 Hollow fiber membrane type microorganism filter device 5 Hollow fiber membrane module 6 Secondary treated water storage tank 7, 7a Secondary treated water pipe 9 Backwash pump 9a Air compressor 10 Backwash pipe 13, 17 Raw seawater supply Pump 14 Backwash water storage tank 15 Ballast water tank 16 Ship hull 1, 20 Ballast water production device 28 Metal filter

Claims (9)

  Plankton removal process to remove planktons in seawater by passing seawater in the harbor area where the ship is anchored through a filter membrane with a pore size of 2 μm or more, and filtration of bacteria with a pore diameter of less than 1.0 μm from the seawater from which planktons have been removed A method for producing marine ballast water, comprising: a bacteria removal step of removing bacteria in seawater by passing through a membrane, and using membrane filtered water obtained in the bacteria removal step as ballast water.   The method for producing marine ballast water according to claim 1, wherein the filtration membrane having a pore diameter of 2 μm or more is a metal filtration membrane.   The method for producing ballast water for ships according to claim 1 or 2, wherein the bacterial filtration membrane is a hollow fiber membrane.   The method for producing ballast water for ships according to any one of claims 1 to 3, further comprising a backwashing step of washing the bacterial filtration membrane by backwashing.   2. The method for producing marine ballast water according to claim 1, wherein at least oil in seawater is removed in advance before the plankton removal step.   Seawater supply means for supplying seawater in a harbor area where a ship is anchored, a filtration device having a filtration membrane with a pore diameter of 2 μm or more for removing planktons in the supplied seawater, and bacteria in seawater from which planktons have been removed A marine ballast water production apparatus comprising a filtration device including a bacteria filtration membrane having a pore diameter of less than 1.0 μm for removing water.   The marine ballast water producing apparatus according to claim 6, wherein an oil content removing device for removing at least an oil content in seawater is installed in a preceding stage of a filtration device including a filtration membrane having a pore diameter of 2 µm or more.   The ship ballast water production apparatus according to claim 6 or 7, further comprising backwash water supply means for supplying backwash water to the bacteria filtration membrane device.   The marine ballast water production apparatus according to any one of claims 6 to 8, wherein the bacteria filtration membrane device is a pressure type hollow fiber membrane device or an immersion type hollow fiber membrane device.

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