JP2011092899A - Ballast water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ballast water treatment apparatus capable of completely killing plankton and bacteria in ballast water, suppressing plankton and bacteria from regrowing during a storage period of ballast water in a ballast tank, and reducing usage of the chlorine agent. <P>SOLUTION: The ballast water treatment apparatus 1 includes a chlorine agent supply apparatus 5 for supplying chlorine agent into sea water poured into a marine ballast tank 8. The chlorine agent supply apparatus includes a hypochlorite supply apparatus 11 for supplying hypochlorite into the sea water poured into the ballast tank and isocyanuric acid compound supply apparatus 12 for supplying an isocyanuric acid compound into the sea water poured into the ballast tank. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a ballast water treatment apparatus for efficiently killing harmful aquatic organisms and microorganisms contained in ballast water loaded in a ballast tank of a ship.

  In general, a ship with an empty load or a small load carries water injection of ballast before leaving the port because of the necessity of ensuring the depth of submersion of the propeller and ensuring safe navigation during empty loading. Conversely, when loading in the port, the ballast water is discharged. By the way, if ballast water is poured and drained by a ship that goes back and forth between loading and unloading ports in different environments, there is a concern that it may adversely affect the coastal ecosystem due to the difference in microorganisms contained in the ballast water. Has been. Therefore, an international convention for the regulation and management of ship ballast water and sediment was adopted in February 2004 at an international conference on ship ballast water management, which required the treatment of ballast water.

The standard established by the International Maritime Organization (IMO) as a standard for the treatment of ballast water is that the number of organisms (mainly zooplankton) of 50 μm or more contained in the ballast water discharged from the ship is less than 10 in 1 m ³ , 10 μm or more The number of organisms less than 50 μm (mainly phytoplankton) is less than 10 in 1 ml, the number of Vibrio cholerae is less than 1 cfu in 100 ml, the number of E. coli is less than 250 cfu in 100 ml, and the number of enterococci is 100 cfu in 100 ml Is less than

  As a conventional technique of ballast water treatment technology, a method of killing organisms in seawater by mixing a chlorine-based disinfectant or hydrogen peroxide into seawater poured into a ballast tank is disclosed (for example, Patent Documents). 1).

JP-A-4-322788

In patent document 1, the sodium hypochlorite aqueous solution is used as a chlorine-type disinfectant mixed in order to kill the organism in seawater. Sodium hypochlorite becomes hypochlorous acid in water, and O (a single molecule of oxygen O ₂ ) generated when free chlorine is decomposed in water has a bactericidal action.

  When using an aqueous sodium hypochlorite solution as a chlorine-based disinfectant for ballast water treatment, there are the following problems. Supplying sodium hypochlorite aqueous solution to seawater that is poured into the ballast tank kills plankton and bacteria in the seawater. To prevent plankton and bacterial regrowth during the period when the ballast water is stored in the ballast tank. In addition, effective chlorine must remain in the ballast water at an appropriate concentration. Since sodium hypochlorite decomposes in ballast water and the effective chlorine concentration decreases over time, in order to maintain the remaining effective chlorine concentration at an appropriate level, It is necessary to increase the amount of sodium chlorite supplied, so a large storage tank for storing sodium hypochlorite is required, contrary to the demand for a compact device to be mounted on a ship, In addition, there is a problem that the cost of medicine is increased, and there is a concern that the amount of trihalomethane generated from hypochlorous acid increases and the influence on the environment is concerned.

  In view of such a situation, the present invention is a ballast water treatment apparatus including a chlorinating agent supply device that supplies a chlorinating agent to seawater poured into a ballast tank of a ship, and reliably kills plankton and bacteria in the ballast water. In addition, it is an object of the present invention to provide a treatment apparatus for ballast water that can suppress regrowth of plankton and bacteria during a period in which ballast water is stored in a ballast tank, and that can reduce the amount of chlorine agent used. .

  As a result of intensive studies to provide a ballast water treatment apparatus that solves the above problems, the present inventors have found that when an isocyanuric acid compound is added to seawater supplied with hypochlorite, effective chlorine in seawater It has been found that a decrease in concentration over time can be suppressed.

  Furthermore, it is found that there is a relationship between the molar ratio of cyanuric acid ions and hypochlorous acid in seawater and the degree of temporal decrease in effective chlorine concentration, and by adjusting the molar ratio, an isocyanuric acid compound It has been clarified that the reduction of the effective chlorine concentration in seawater can be surely suppressed without excessively supplying the water, and the present invention has been invented.

  The ballast water treatment apparatus according to the present invention includes a chlorinating agent supply device that supplies a chlorinating agent to seawater poured into a ballast tank of a ship.

  In such a ballast water treatment apparatus, in the present invention, the chlorinating agent supply device includes hypochlorite supply means for supplying hypochlorite to seawater injected into the ballast tank, and isocyanuric acid in seawater injected into the ballast tank. And an isocyanuric acid compound supplying means for supplying the compound.

  In such a ballast water treatment device, by supplying hypochlorite and isocyanuric acid compounds to the seawater supplied to the ballast tank, the seawater stored in the ballast tank is compared with the case of supplying only hypochlorite. High effective chlorine concentration is maintained. Therefore, the regrowth of plankton and bacteria is effectively suppressed, and the supply amount of hypochlorite is reduced.

  Hypochlorite supply amount and isocyanuric acid compound supply amount so that the molar ratio of cyanuric acid ion and hypochlorous acid in seawater supplied with hypochlorite and isocyanuric acid compound is within a predetermined range. It is preferable to provide a control means for controlling.

  Based on the relationship between the molar ratio of cyanuric acid ions and hypochlorous acid in seawater found by the present inventor and the degree of decrease in the effective chlorine concentration over time, the control means determines the molar ratio. By controlling the supply amount of hypochlorite and the supply amount of isocyanuric acid compound so as to be within a predetermined range, the decrease in effective chlorine concentration in seawater is reliably suppressed without excessive supply of isocyanuric acid compound. be able to.

  It is preferable that a salinity concentration measuring unit that measures a salinity concentration of seawater taken from the sea is provided, and the control unit determines a predetermined range of the molar ratio based on the salinity concentration of seawater measured by the salinity concentration measuring unit.

  By setting the predetermined range of the molar ratio based on the salinity concentration of seawater taken from the sea, the supply amount of hypochlorite and the supply amount of isocyanuric acid compound can be adjusted more accurately.

  The control means determines the upper limit (y) of the molar ratio based on the following relational expression between the measured salt concentration (xPSU) of seawater and the hypochlorous acid concentration (Amg / L) to be injected. It is preferable.

  As described above, by supplying hypochlorite and isocyanuric acid compounds to the seawater supplied to the ballast tank, compared to the case of supplying only hypochlorite, the seawater stored in the ballast tank The effective chlorine concentration can be kept high, the regrowth of plankton and bacteria can be effectively suppressed, and the supply amount of hypochlorite can be reduced.

It is a graph which shows the measurement result of the change of the effective chlorine concentration in the object water to which the sodium hypochlorite solution and the sodium cyanurate aqueous solution were supplied. It is a graph which shows the relationship between the salinity concentration of object water, and the upper limit of the molar ratio of cyanuric acid ion and hypochlorous acid. It is a figure which shows the ballast water treatment apparatus which concerns on embodiment.

  Hereinafter, embodiments of a ballast water treatment apparatus according to the present invention will be described with reference to the accompanying drawings.

  Before describing the specific configuration of the ballast water treatment apparatus, first, the procedure for determining the supply amount of the isocyanuric acid compound found by the present inventors will be described. In the following description, the salinity concentration is expressed in units of PSU (practical salinity), which is a value obtained by converting the electrical conductivity of seawater into a salinity value.

  Using brackish water with a salinity of 8 PSU as the target water, a sodium hypochlorite solution having an effective chloric acid concentration of 20 mg / L is supplied to the target water, and the molar ratio of cyanuric acid ions to hypochlorous acid (cyanuric acid ions / Hypochlorous acid) was determined to be in the range of 0.03 to 0.3, and the supply amount of the aqueous sodium cyanurate solution was determined and supplied to the target water. The molar ratio was 0.03, 0.05, 0.1, 0.2, 0.3.

  FIG. 1 shows the measurement results of changes in the effective chlorine concentration in the target water until 40 days have passed since the supply of the sodium hypochlorite solution and the sodium cyanurate aqueous solution. As can be seen in FIG. 1, the higher the molar ratio, the higher the effective chlorine concentration, and the higher the molar ratio, the less the effective chlorine concentration decreases with time.

  Here, the ratio of the effective chlorine concentration after the lapse of 40 days to the effective chlorine concentration at the beginning of the supply of the sodium hypochlorite solution and the sodium cyanurate aqueous solution, that is, the residual ratio is 64% when the molar ratio is 0.1. The ratio was 85% when the ratio was 0.2, and 90% when the molar ratio was 0.3.

  In order to suppress the suppression of regrowth of plankton and bacteria in the ballast water, the residual ratio of effective chlorine after 40 days is preferably 50% or more. On the other hand, from the viewpoint of avoiding an excessive supply of the isocyanuric acid compound, it is not necessary to set the residual ratio to 80% or more, so the molar ratio is preferably set to be smaller than 0.2. Therefore, when supplying a hypochlorous acid concentration at 20 mg / L to brackish water having a salinity of 8 PSU, a preferable upper limit of the molar ratio is set to 0.2.

  Next, a plurality of types of brackish water (salinity concentration: 0, 2, 3, 4, 5, 6, 8, 12 PSU) in a salinity range of 0 to 12 PSU is used as a target water, and a hypochlorous acid concentration is 20 mg / L. In the case of supplying, by supplying the sodium hypochlorite solution and the sodium cyanurate aqueous solution to the respective target water in the same procedure as described above, the residual rate of effective chlorine concentration after 40 days should be 50% or more. The upper limit of the above molar ratio was investigated, which can prevent the excessive supply of sodium cyanurate. As a result, when the hypochlorous acid concentration was supplied at 20 mg / L, the relationship as shown in FIG. 2 was obtained for the salinity concentration (x) of the target water and the upper limit value (y) of the molar ratio.

  The relationship shown in FIG. 2 is expressed by the following equation (1).

  Further, when the concentration of hypochlorous acid to be injected is changed within the range of 10 to 50 mg / L, the relationship between the salinity concentration of the target water and the upper limit value of the molar ratio similar to those shown in FIG. 2 is examined. When the slope a in the above equation (1) is obtained, the result shown in the following Table 1 is obtained. The slope a is -1 / A when the hypochlorous acid concentration to be injected is Amg / L. I found the equivalent. Here, hypochlorous acid concentration is 10, 15, 20, 30, 40, 50 mg / L, and salinity concentration of the target water is 0, 2, 3, 4, 5, 6, 8, 12, 15, 20, 25, 30, 35 PSU.

  From this, the residual ratio of effective chlorine concentration after a long period of time can be 50% or more, and the molar ratio of cyanurate ion and hypochlorous acid that can avoid excessive supply of sodium cyanurate The relationship between the upper limit (y) and the salinity concentration (x) of the target water is expressed by the following equation (2).

  From the results of the above experiments, the present inventors have found that the supply amount of the isocyanuric acid compound can be determined as follows.

  First, the salinity concentration (PSU) (x in FIG. 2) of the target water is measured, and from the above formula (2) corresponding to the concentration of hypochlorous acid supplied, the cyanuric acid ion and hypochlorous acid The upper limit value of the molar ratio (y in FIG. 2) is derived, and the amount of the isocyanuric acid compound that realizes the upper limit value of the molar ratio, in other words, the upper limit value of the supply amount of the isocyanuric acid compound is obtained. And by supplying an isocyanuric acid compound in an amount smaller than the upper limit, the effective chlorine concentration in the ballast water being stored can be maintained high for a long period of time, and the regrowth of organisms in the ballast water can be suppressed. Can do. Furthermore, if an isocyanuric acid compound in an amount smaller than the above upper limit is supplied, the supply amount of the isocyanuric acid compound does not become excessive, which is economical.

  FIG. 1 is a view showing a ballast water treatment apparatus 1 according to this embodiment. As shown in FIG. 1, a ballast water treatment device 1 is present in seawater, a seawater intake line 2 for taking seawater into the ship, a pump 3 for taking seawater by the seawater intake line 2 and feeding it to the filtration device 4. From the chlorinating agent supply device 5 to the seawater filtered by the filtering device 4 for removing the plankton, the chlorinating agent supplying device 5 for supplying the chlorine agent for killing bacteria to the seawater filtered by the filtering device 4, and the seawater filtered by the filtering device 4 A cavitation device 6 that also serves as a diffuser for diffusing the supplied chlorine agent, a treated water supply line 7 for supplying treated water to which the chlorine agent has been added to the ballast tank 8, and treated water supplied from the treated water supply line 7 are stored. The ballast tank 8 is provided.

  Hereinafter, each device will be described in more detail.

1. Filtration device 4
The filtration device 4 removes plankton present in seawater taken from a sea chest (seawater intake port) provided on the side of the ship and taken through the seawater intake line 2 by the pump 3. Use a filter with a filter of ~ 200 μm. The reason why the mesh opening is 10 to 200 μm is to reduce the frequency of backwashing and shorten the ballast water treatment time in the port of call while keeping the capture rate of zooplankton and phytoplankton at a certain level. In other words, if the mesh size is larger than 200 μm, the capture rate of zooplankton and phytoplankton is remarkably reduced. If the mesh size is smaller than 10 μm, the frequency of backwashing increases and the ballast water treatment time at the port of call becomes longer. Therefore, it is not preferable. In particular, it is preferable to use one having an opening of about 50 μm because the capture rate and the backwashing frequency can be set optimally.

2. Chlorine agent supply device 5
The chlorinating agent supply device 5 supplies a chlorinating agent that kills bacteria to the seawater filtered by the filtering device 4 and supplied to the cavitation device 6. The chlorinating agent supply device 5 includes a hypochlorite supply device 11 as a hypochlorite supply unit for supplying hypochlorite to the seawater, and an isocyanuric acid compound for supplying an isocyanuric acid compound to the seawater. The isocyanuric acid compound supply device 12 as the supply means, the salinity concentration meter 9 as the salinity concentration measurement means for measuring the salinity concentration of the seawater taken from the sea in the seawater intake line 2, and the salinity meter 9 measured. And a control device 10 as control means for controlling the supply amounts of the isocyanuric acid compound and the hypochlorite based on the salinity of the seawater.

(1) Hypochlorite feeder 11
The hypochlorite supply device 11 includes a hypochlorite storage tank 13 that stores a hypochlorite solution, and a pump 14 that supplies the hypochlorite solution to a hypochlorite injection device 15. And a hypochlorite injection device 15 for injecting the hypochlorite solution into the seawater supplied from the filtration device 4.

  The hypochlorite storage tank 13 stores a hypochlorite solution. Examples of hypochlorite include sodium hypochlorite and potassium hypochlorite.

  The hypochlorite injection device 15 injects the hypochlorite solution extracted from the hypochlorite storage tank 13 by the pump 14 into the seawater filtered by the filtration device 4. The hypochlorite injecting device 15 has, for example, a plurality of nozzles (not shown) for injecting a hypochlorite solution into the piping provided in the piping for feeding the filtered seawater. The injection amount of the hypochlorite solution can be controlled by the pump 14 or a flow rate adjusting valve (not shown).

  The hypochlorite solution is supplied to the upstream side of the cavitation device 6 and / or to at least one of the cavitation devices 6. When a venturi tube described later is used as the cavitation device 6, the hypochlorite solution is supplied to either the upstream side of the venturi tube or the throat portion of the venturi tube. In addition, when supplying the hypochlorite solution to the upstream side of the venturi tube, the hypochlorite solution is diffused to some extent in the flow path until reaching the throat of the venturi tube where cavitation occurs, Proceed with diffusion and mixing of hypochlorite by cavitation. In order to supply the hypochlorite solution to the upstream side of the venturi pipe, a hypochlorite solution inlet may be provided in the flow path upstream of the venturi pipe. Further, when the hypochlorite solution is supplied to the throat of the venturi tube, the hypochlorite solution injection pump is not required because the hypochlorite solution is self-primed by the ejector action of the venturi tube.

(2) Isocyanuric acid compound supply device 12
The isocyanuric acid compound supply device 12 includes an isocyanuric acid compound storage tank 16 that stores the isocyanuric acid compound, a cutting device 17 that supplies the isocyanuric acid compound stored in the isocyanuric acid compound storage tank 16 to the dissolution tank 18, and seawater. A dissolving tank 18 for dissolving an isocyanuric acid compound in a solution to produce an isocyanuric acid compound solution, a pump 19 for supplying the isocyanuric acid compound solution to the isocyanuric acid compound injection device 20, and seawater supplied from the filtration device 4 And an isocyanuric acid compound injection device 20 for injecting the isocyanuric acid compound solution.

  The isocyanuric acid compound storage tank 16 is a hopper that stores a granular isocyanuric acid compound. Examples of the isocyanuric acid compound include isocyanuric acid salts such as chlorinated isocyanuric acid salt, sodium cyanuric acid salt, potassium cyanuric acid, isocyanuric acid compounds other than the isocyanuric acid salt, cyanuric acid, chlorinated isocyanuric acid, and the like. .

  In particular, when a chlorinated isocyanurate is used as the isocyanurate compound, when the chlorinated isocyanurate is dissolved in seawater, it is hydrolyzed to produce cyanurate ions and hypochlorous acid, and hypochlorous acid. It is preferable because it also serves as a supply source. Examples of the chlorinated isocyanurate include sodium dichloroisocyanurate, potassium dichloroisocyanurate, sodium monochloroisocyanurate, potassium monochloroisocyanurate, sodium trichloroisocyanurate and potassium trichloroisocyanurate.

  The cutting device 17 should just be an apparatus suitable for cutting out the isocyanuric acid compound of a granular material, such as a rotary valve, for example.

  A stirrer (not shown) is provided in the dissolution tank 18, and the isocyanuric acid compound cut out from the isocyanuric acid compound storage tank 16 is dissolved in seawater or the like to generate an isocyanuric acid compound solution. When cyanuric acid is used as the isocyanuric acid compound, in the dissolution tank 18, the cyanuric acid is dissolved in an alkaline solution such as an aqueous sodium hydroxide solution to produce an aqueous sodium cyanurate solution. Moreover, when chlorinated isocyanurate, chlorinated isocyanuric acid, sodium cyanurate, potassium cyanurate, or the like is used as the isocyanuric acid compound, the dissolution tank 18 generates an aqueous solution dissolved in water or seawater. .

  The isocyanuric acid compound injection device 20 injects the isocyanuric acid compound solution generated by dissolving the isocyanuric acid compound in seawater or the like in the dissolution tank 18 into the seawater filtered by the filtration device 4. As a result, cyanuric acid ions are supplied to the seawater. The isocyanuric acid compound injection device 20 has, for example, a plurality of nozzles (not shown) for injecting an isocyanuric acid compound solution into the piping provided in a piping for feeding the filtered seawater. The injection amount of the isocyanuric acid compound solution can be controlled by a pump 19 or a flow rate adjusting valve (not shown).

  The isocyanuric acid compound solution is supplied to at least one of the upstream side of the cavitation device 6 and the cavitation device 6. When a venturi tube described later is used as the cavitation device 6, the isocyanuric acid compound solution is supplied to either the upstream side of the venturi tube or the throat portion of the venturi tube. In addition, when supplying the isocyanuric acid compound solution upstream of the venturi tube, the isocyanuric acid compound solution is diffused to some extent in the flow path until reaching the throat of the venturi tube where cavitation occurs, and isocyanuric acid by cavitation. Advance the diffusion and mixing of compounds. In order to supply the isocyanuric acid compound solution to the upstream side of the venturi tube, an inlet for the isocyanuric acid compound solution may be provided in the flow channel upstream of the venturi tube. Further, when the isocyanuric acid compound solution is supplied to the throat of the venturi tube, it is self-primed by the ejector action of the venturi tube, so that the isocyanuric acid compound solution pump is not required.

  In the present embodiment, either the hypochlorite solution or the isocyanuric acid compound solution may be supplied to seawater first, or may be supplied simultaneously.

(3) Salinity meter 9
The salinity concentration of the seawater taken from the sea is measured, and the salinity concentration data is output to the control device 10 (broken line in FIG. 3).

(4) Control device 10
The control device 10 sets the weight concentration of the effective chlorine amount in the seawater of hypochlorite to be supplied to 5 to 100 mg / L based on the data of the type and amount of organisms in the seawater to be taken and the concentration of chlorine consuming substances. The operation of the pump 14 is controlled so as to adjust the supply amount of hypochlorite within a range (dashed line in FIG. 3).

  Based on the weight concentration of the effective chlorine amount of hypochlorite and the salinity concentration data from the salinity concentration meter 9, the control device 10 uses the equation (2) to calculate the cyanurate ion and hypochlorite. The upper limit value of the molar ratio is derived, the supply amount of the isocyanuric acid compound corresponding to the upper limit value (upper limit supply amount) is determined, and the pump 19 is operated so as to supply the isocyanuric acid compound in an amount less than the upper limit supply amount. Is controlled (broken line in FIG. 3).

3. Cavitation device 6
The cavitation device 6 also serves as a diffuser for diffusing hypochlorite and an isocyanuric acid compound in the seawater filtered by the filtration device 4, and for example, a venturi tube is preferably used. The Venturi tube diffuses hypochlorite and isocyanuric acid compounds in seawater, and damages or kills plankton that has passed through the filtration device 4 by cavitation generated by the Venturi tube.

  The Venturi pipe is composed of a throttle part where the pipe cross-sectional area gradually decreases, a throat part which is the minimum cross-sectional area part, and a widened part (diffuser part) where the pipe cross-sectional area gradually increases. Cavitation bubbles are generated due to a sudden drop in static pressure accompanying a rapid increase in flow velocity at the throat, and cavitations that cause the cavitation bubbles to grow rapidly collapse due to a sudden increase in pressure due to a decrease in flow velocity at the spreading portion are generated. To do.

  Hypochlorite and isocyanuric acid compounds are rapidly diffused into seawater by cavitation to promote the bactericidal action of bacteria by hypochlorite. In order to promote mixing of hypochlorite and isocyanuric acid compound into seawater by the diffusion action of cavitation in this way, hypochlorous acid is compared with the case of simply injecting hypochlorite and isocyanuric acid compound. Since the supply amount of salt can be reduced, the supply amount of a chlorine reducing agent for detoxifying hypochlorite can be reduced.

  In addition, aquatic organisms in seawater are damaged or destroyed and killed by the action of OH radicals with strong impact pressure, shearing force, high temperature and strong oxidizing power due to the collapse of cavitation bubbles. According to the venturi cavitation, the protozoan having a relatively hard shell, the outer shell of zooplankton, can be destroyed, and the penetration of the chlorine agent can be promoted to be surely killed.

  As a cavitation device that also serves as a diffuser, a stirrer that rotates a stirrer blade or a static mixer that generates a stirring flow in the seawater channel may be used in addition to the venturi tube.

  Next, the ballast water treatment by the ballast water treatment apparatus 1 according to the present embodiment will be described.

  First, by operating the pump 3, seawater is taken into the ship from the seawater intake line 2 and fed to the filtration device 4. In the filtration device 4, zooplankton, phytoplankton, etc. having a size corresponding to the opening of the filtration device 4 are removed. The aquatic organisms captured by the filtration device 4 are washed away by backwashing the filter of the filtration device 4 and returned to the sea. Even if aquatic organisms captured by the filtration device 4 are returned to the sea, the ecosystem is not adversely affected because they are in the same sea area. That is, in this embodiment, since processing is performed when ballast water is loaded, the backwash water of the filtration device 4 can be discharged as it is. The seawater filtered in the filtration device 4 is supplied to the chlorinating agent supply device 5.

  The control device 10 of the chlorinating agent supply device 5 determines the weight concentration of the effective chlorine amount in the seawater of the hypochlorite to be supplied based on the data of the type and amount of organisms in the seawater to be taken and the concentration of chlorine consuming substances. The operation of the pump 14 is controlled so as to adjust the supply amount of hypochlorite within a range of 5 to 100 mg / L (broken line in FIG. 3). As a result, the hypochlorite injection device 15 of the chlorinating agent supply device 5 supplies the amount of hypochlorite determined by the control device 10 to the seawater filtered by the filtration device 4.

  Further, the control device 10 uses the formula (2) based on the weight concentration of the effective chlorine amount of hypochlorite and the salinity concentration data from the salinity concentration meter 9 to calculate cyanuric acid ions and hypochlorous acid. Deriving the upper limit of the molar ratio with the salt, further determining the supply amount (upper limit supply amount) of the isocyanuric acid compound corresponding to the upper limit value, and supplying the isocyanuric acid compound in an amount less than the upper limit supply amount 19 is controlled (broken line in FIG. 3). As a result, the isocyanuric acid compound injection device 20 of the chlorinating agent supply device 5 supplies the amount of isocyanuric acid compound determined by the control device 10 to the seawater filtered by the filtration device 4.

  In the cavitation device 6, cavitation is generated by the above-described mechanism, and the diffusion of the isocyanuric acid compound and the hypochlorite, that is, the chlorinating agent into the seawater is promoted, and the bacteria killing effect is enhanced. In addition, OH radicals with strong impact pressure, shearing force, high temperature, and oxidizing power act on aquatic organisms in seawater by cavitation, thereby damaging or destroying aquatic organisms to kill the aquatic organisms.

  Seawater in which the chlorine agent is diffused by the cavitation device 6 is fed to the ballast tank 8 through the treated water feed line 7 and stored in the ballast tank 8. Then, plankton and bacteria in the seawater are killed by the process of supplying water to the ballast tank 8 and the effective chlorine generated from the chlorine agent during storage in the ballast tank 8.

  As described above, in the present embodiment, zooplankton and phytoplankton having a size of 10 to 200 μm or more are removed with a filtration device, a chlorinant is supplied, and plankton and bacteria contained in the filtered seawater are killed. Since it was made to do, the process of the ballast water which satisfy | fills the ballast water reference | standard which IMO establishes reliably is realizable.

  In this embodiment, by supplying hypochlorite and an isocyanuric acid compound to the seawater supplied to the ballast tank 8, the seawater stored in the ballast tank 8 is compared to the case of supplying only hypochlorite. The effective chlorine concentration in the inside can be maintained high. Therefore, the regrowth of plankton and bacteria contained in seawater can be effectively suppressed, and the amount of hypochlorite supplied can be reduced.

  In addition, an amount of isocyanuric acid compound that realizes a predetermined upper limit value of the molar ratio of cyanuric acid ion to hypochlorite, that is, an amount of isocyanuric acid compound that is smaller than the upper limit value of the supply amount of the isocyanuric acid compound is supplied. Thereby, since the supply amount of the isocyanuric acid compound does not become excessive, an increase in cost can be suppressed accordingly.

  In the present embodiment, since the upper limit value of the molar ratio is derived based on the salinity concentration of seawater taken from the sea, the supply amount of hypochlorite and the supply amount of isocyanuric acid compound are more accurately determined. Can be adjusted.

DESCRIPTION OF SYMBOLS 1 Ballast water treatment apparatus 5 Chlorine agent supply apparatus 8 Ballast tank 9 Salinity meter (salt concentration measuring means)
10 Control device (control means)
11 Hypochlorite supply equipment (hypochlorite supply means)
12 Isocyanuric acid compound supply device (isocyanuric acid compound supply means)

Claims (4)

A ballast water treatment apparatus comprising a chlorinating agent supply device for supplying a chlorinating agent to seawater poured into a ballast tank of a ship,
The chlorinating agent supply device includes hypochlorite supply means for supplying hypochlorite to seawater injected into the ballast tank, and isocyanuric acid compound supply means for supplying isocyanuric acid compound to seawater injected into the ballast tank. A ballast water treatment device comprising:   Hypochlorite supply amount and isocyanuric acid compound supply amount so that the molar ratio of cyanuric acid ion and hypochlorous acid in seawater supplied with hypochlorite and isocyanuric acid compound is within a predetermined range. The ballast water treatment apparatus according to claim 1, further comprising control means for controlling It is equipped with a salinity measurement means that measures the salinity of seawater taken from the sea,
The ballast water treatment apparatus according to claim 2, wherein the control means determines the predetermined range of the molar ratio based on the salinity concentration of seawater measured by the salinity concentration measurement means. The control means determines the upper limit (y) of the molar ratio based on the following relational expression between the measured salt concentration (xPSU) of seawater and the hypochlorous acid concentration (Amg / L) to be injected. The ballast water treatment apparatus according to claim 3.

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