JP4816671B2 - Ballast water treatment method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide firstly a method and apparatus for treating ballast water capable of lowering a treatment cost by diminishing an amount of a bactericide used as far as possible, and secondly a method for treating ballast water capable of properly controlling an amount of supplying the bactericide without generating a trouble with the apparatus used. <P>SOLUTION: The method of treating ballast water includes: a definite amount supply process for supplying a definite amount of a bactericide into sea water in order to become a saturated state; a saturation determination process for determining as to whether a residual concentration of the bactericide is saturated; a diminution supply process for supplying an amount of a diminished bactericide by obtaining a concentration difference between a saturated bactericide concentration at the time and a targeted bactericide concentration to find an amount of bactericide to diminish from the supplying amount at the definite amount supply process. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method and apparatus for treating ballast water loaded in a ballast tank of a ship, and more particularly to a method and apparatus for efficiently killing harmful bacteria and plankton contained in ballast water.

In general, a ship with an empty load or a small load will inject ballast water into the ballast tank before leaving the port because of the necessity of ensuring the depth of the propeller submersion and ensuring safe navigation when empty. Conversely, when loading in the port, the ballast water is discharged.
By the way, when 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 ballast water discharged from ships is 10 or less in 1 m ³ , 10 μm. The number of organisms less than 50 μm (mainly phytoplankton) is 10 or less in 1 ml, Vibrio cholerae is less than 1 cfu in 100 ml, Escherichia coli is less than 250 cfu in 100 ml, and Enterococci are less than 100 cfu in 100 ml. Yes.

As ballast water treatment technology, a filtration device that filters seawater to trap aquatic organisms, a bactericide supply device that supplies bactericides that kill bacteria in the seawater into the filtered seawater, and a bactericide supply And a venturi tube that receives a supply of filtered water and generates cavitation in the filtered water to diffuse the disinfectant in the filtered water and damage or kill aquatic organisms in the filtered water. It has been proposed (see, for example, Patent Document 1).
International Publication WO2006 / 132157

In the method described in Patent Document 1, it is disclosed to kill bacteria in seawater using sodium hypochlorite or the like as a bactericidal agent. However, in order to reduce processing costs, a bactericidal agent is used as much as possible. It is preferable to suppress the amount and to use the minimum necessary amount.
For this reason, it is necessary to adjust the concentration of the bactericide so as not to be excessively supplied by detecting the concentration of the bactericide in the seawater to obtain an appropriate concentration.
However, due to clogging of filters arranged in the processing path, fluctuations in the supply flow rate to the ballast tank, etc., the residual concentration of the bactericide may differ even when the same amount of bactericide is supplied.
In addition, time delays such as the time from supply of a bactericidal agent to diffusion into seawater and the time until the bactericidal agent exhibits a bactericidal effect (the time until free chlorine is generated in sodium hypochlorite). There is also.
For this reason, there is a problem that proper supply amount control is difficult in general feedback (PID) control.

  In order to adjust the supply amount of the bactericidal agent, it is necessary to adjust the output of the pump for supplying the bactericidal agent and the opening degree of the valve provided in the bactericidal agent supply line. If the concentration of the sterilizer is adjusted to be higher or lower than the predetermined sterilizer concentration and the sterilizer supply amount is adjusted, the pump output and valve opening must be adjusted frequently. Failure may occur.

The present invention has been made to solve such a problem. First, it is an object of the present invention to provide a ballast water treatment method and apparatus capable of reducing the treatment cost by reducing the amount of the bactericide used as much as possible. Yes.
A second object of the present invention is to provide a ballast water treatment device capable of appropriately controlling the supply amount of a bactericide without causing trouble in the equipment used.

  In the ballast water treatment method according to the first aspect of the present invention, a constant amount supplying step of supplying a certain amount of bactericidal agent that is set as being saturated into seawater, and whether or not the residual concentration of the bactericide is saturated A saturation determination step for determining the concentration, and when it is determined that saturation has occurred, a concentration difference between the saturated bactericide concentration at that time and a target bactericide concentration is obtained, and the constant amount supply step based on the concentration difference The present invention is characterized by comprising a reduction supply step for obtaining the amount of the bactericidal agent to be reduced from the supply amount supplied and supplying the reduced amount of the bactericide supply.

The disinfectant is supplied to kill bacteria in seawater. The disinfectant supplied is sodium hypochlorite, chlorine, chlorine dioxide, hydrogen peroxide, ozone, peracetic acid, or Mixtures of two or more of these can be used.
The fixed amount supplied in the fixed amount supplying step is set in consideration of the amount of the bactericide decomposed in the ballast water, and is set to an amount corresponding to twice the residual chlorine concentration target value, for example.
Whether or not the bactericide concentration in the saturation determination step is saturated may be determined by a predetermined method. For example, when the residual chlorine concentration is sampled every predetermined time and the rate of change becomes a predetermined value or less It is determined that saturation has occurred.
The target bactericidal concentration is a value set in advance by, for example, an experiment conducted in advance.

  The ballast water treatment method according to the second aspect of the present invention is the one according to the first aspect, wherein the saturation determination step is determined based on whether or not the time change amount of the bactericide concentration is equal to or less than a predetermined change amount. It is characterized by doing.

The ballast water treatment apparatus according to the third aspect of the present invention includes a bactericide supply device that supplies bactericides into seawater, and a bactericide concentration detection that detects the bactericide concentration in seawater after the bactericides are supplied. Means and a bactericide supply amount control device for controlling a bactericide supply amount by the bactericide supply device,
The sterilizing agent supply amount control device is based on a constant amount supply instructing means for instructing the sterilizing agent supply device to supply a predetermined amount of sterilizing agent at the beginning of supplying the sterilizing agent, and a detection value of the sterilizing agent concentration detecting means. Saturation determination means for determining whether or not the bactericidal concentration is saturated, and when the saturation determination means determines that the concentration is saturated, the bactericidal concentration at that time and a predetermined bactericidal concentration target A sterilizing agent supply amount calculating means for calculating a sterilizing agent supply amount to be reduced based on the concentration difference, and a sterilizing agent to be reduced based on the calculated value of the reducing sterilizing agent supply amount calculating means And a weight reduction supply instructing unit for instructing the agent supply amount to the disinfectant supply device.

  A disinfectant supply device supplies a disinfectant to seawater to be processed. An example of the equipment constituting the sterilizing agent supply apparatus is as follows: a sterilizing agent storage tank for storing the sterilizing agent, a pipe for supplying the sterilizing agent in the sterilizing agent storage tank to seawater, and a sterilizing agent provided at the front end side of the pipe And the like, a supply pump for supplying the sterilizing agent in the sterilizing agent storage tank to the pipe, a valve for adjusting the supply amount of the sterilizing agent, and the like.

  The ballast water treatment apparatus according to the fourth aspect of the present invention is the one according to the third aspect, wherein the saturation determination means determines whether or not the amount of time change of the bactericide concentration is equal to or less than a predetermined change amount. It is characterized by doing.

The ballast water treatment apparatus according to the fifth aspect of the present invention is the one according to the third aspect or the fourth aspect, and the sterilizing agent supply amount control device is a sterilizer to be supplied after the reduced amount supply instruction is given. Feedback control means for feedback control of the agent supply amount, the feedback control means measures the concentration of the bactericide in the seawater, obtains the average value of the bactericide concentration for a predetermined time, and the bactericide concentration average value is predetermined. When the dead zone range of the bactericide concentration is deviated, the bactericide supply amount supplied by the bactericide supply device is set to the bactericide supply amount according to the target bactericide concentration. it is characterized in that the adjustment to the supply amount obtained by multiplying the rate R _n.
R _n = R _n−1 + (x _s −x _ave ) · a · w (1)
R _n ; dead zone control rate R _n-1 ; dead zone control rate x _s ; previous bactericidal agent concentration target value x _ave ; bactericidal agent concentration average value a; predetermined coefficient w; dead zone control width

As an example of the feedback control means, a measuring device for measuring the concentration of the bactericide in the seawater discharged from the venturi pipe, a storage means for storing various data, a calculation means for calculating the bactericidal agent supply amount, and a calculation means Control means for controlling the device based on the calculation result.
The measuring device measures the concentration of the bactericide in the seawater supplied with the bactericide and outputs it to the calculation means.
Data shown in the following (a) to (c) is stored in the storage means.
(A) Bactericide concentration target value (x _s ) determined in advance as a minimum concentration target value of a bactericide necessary for killing bacteria in seawater
(B) Dead zone range (x _s (1−c _L ) ≦ dead zone range ≦ x _s (1 + c _H )) that is predetermined as an upper and lower limit range of the bactericide concentration that can be allowed with respect to the fungicide concentration target value. ,
c _L ; dead zone lower limit width (for example, greater than 0 and less than 0.20)
c _H : Deadband upper limit width (for example, greater than 0 and less than 0.50)
In some cases, c _L and c _H are equal.
(C) Predetermined relational expression (y = ax + b, a; predetermined coefficient (slope) as a relation between the bactericidal agent supply amount (y) and the bactericidal agent concentration (x), a number greater than 0 and less than 1 B; intercept, a number greater than 0 and less than 1)
The above relational expression takes into account the conditions that affect the process until the supplied bactericidal agent is diffused and becomes effective as an effective bactericidal component, and the bactericidal agent supply amount (y) and bactericidal agent concentration (x) The relationship is established.
Incidentally, bactericide supply amount _{y s} for fungicides density target value _{x s becomes} y s = _ax s + b.

The calculation means inputs the measurement result of the measuring device and obtains the average value of the bactericide concentration for a predetermined time. Then, it is determined whether or not the average value of the bactericidal agent concentration deviates from the upper and lower limit range (dead zone range) of the bactericidal agent concentration that can be allowed with respect to the bactericidal concentration target value. The sterilizing agent supply amount to be calculated is calculated based on the data stored in the storage means.
The control means performs adjustment control of the output of the supply pump and the like and / or the opening of the supply amount adjustment valve based on the calculation result of the calculation means.
The control procedure is as follows.

<Example of feedback control procedure>
After a reduced amount supply instruction, after a predetermined time (for example, 5 minutes) has elapsed, the measuring device measures the concentration of the bactericide in seawater and outputs the measurement result to the calculation means.
The calculation means inputs the measurement result and obtains the bactericide concentration average value x _ave for a predetermined time. Then, it is determined whether or not this germicide concentration average value x _ave deviates from a predetermined dead zone range of the germicide concentration, and when it is deviated, the germicide supply amount y is set as a target germicide concentration. The sterilizing agent supply amount y (y = y _s · R _n ) obtained by multiplying the sterilizing agent supply amount y _s by the dead zone control rate R _n is obtained.
By adjusting the bactericidal agent supply amount so as to obtain the obtained bactericidal agent supply amount y, the bactericidal agent concentration average value x _ave exceeds the upper and lower limit ranges of the bactericidal agent concentration that can be allowed for the bactericidal agent concentration target value. If so, the bactericide concentration average value x _ave is adjusted to fall within the upper and lower limits.
Note that the dead zone control rate R _n is expressed by the equation (1).
R _n = R _n−1 + (x _s −x _ave ) · a · w (1)
R _n-1 : Dead band control rate before 1 time a: Predetermined coefficient (greater than 0 and less than 1)
w: Dead band control width (greater than 0 and less than 1)

  When the sterilizing agent supply amount y is obtained, the control means inputs the obtained sterilizing agent supply amount y, and outputs and / or supplies such as the rotation speed of the supply pump so as to obtain the obtained sterilizing agent supply amount. Performs adjustment control of the opening of the quantity adjustment valve.

According to the fifth aspect of the present invention, since the supply amount of the bactericide is adjusted based on the average value of the bactericide concentration for an appropriate time, the residual concentration of the bactericide varies or the bactericidal agent is supplied before the seawater Even if there is a time delay such as the time for diffusion inside and the time until the bactericidal agent exhibits the bactericidal effect, the amount of bactericidal agent supplied can be controlled with high accuracy.
Further, an upper and lower limit range of the sterilizing agent concentration that can be allowed with respect to the sterilizing agent concentration target value is determined in advance as a dead zone range, and when the dead zone is deviated, an operation for adjusting the sterilizing agent supply amount is performed. Therefore, it is not necessary to frequently adjust the output such as the rotation speed of the supply pump and the opening degree of the valve, and it is difficult for each device to be defective.

  The ballast water treatment apparatus according to the sixth aspect of the present invention is the one according to the fifth aspect, wherein the bactericide supply amount control apparatus measures the flow rate of the seawater to be processed and obtains the average flow rate value for a predetermined time. The sterilizing agent supply amount is adjusted according to the average flow rate.

When the seawater flow rate fluctuates, it is necessary to correct the disinfectant supply amount. However, if an attempt is made to control the supply amount of the bactericidal agent based only on the residual concentration of the bactericidal agent, a time delay such as the time for supplying the bactericidal agent to diffuse into the seawater or the time for the bactericidal agent to exert a bactericidal effect There are cases where proper control is not possible.
Therefore, by performing control in consideration of fluctuations in the seawater flow rate, it is possible to control the supply amount of the sterilizing agent more appropriately.
Specifically, the disinfectant supply amount y is adjusted based on the following formula.
y = y _s · R · (Q _ave / Q _s )
Q _ave ; Average flow rate Q _s ; Reference flow rate

In the sixth embodiment of the present invention, since the bactericidal agent supply amount is corrected according to the fluctuation of the seawater flow rate, the bactericidal agent supply amount can be controlled with higher accuracy.
The average flow rate is an average flow rate for a predetermined time. Further, the reference flow rate is seawater flow rate when determining the sterilizing agent supply amount y _s corresponding to disinfectant concentration as a target.

  The ballast water treatment apparatus according to the seventh aspect of the present invention is the one according to the fifth aspect or the sixth aspect, wherein the disinfectant decomposing agent is supplied to the seawater supplied with the disinfectant. An antibacterial agent supply amount control device that measures the concentration of the disinfectant remaining in the seawater and adjusts the disinfectant agent supply amount of the disinfectant agent supply device based on the measured disinfectant concentration; , Provided.

  By providing such a sterilizing agent decomposing agent supply device, the sterilizing agent remaining in the seawater can be decomposed and the influence on the sea area where the ballast water is discharged can be eliminated. Moreover, by providing the bactericide decomposition agent supply amount control device, the bactericide decomposition agent supply amount can be appropriately adjusted according to the concentration of the bactericide remaining in the seawater.

An example of the equipment constituting the bactericidal agent supply control device is as follows: a measuring device that measures the concentration of bactericidal agent in seawater discharged from the ballast tank, storage means for storing various data, and bactericidal agent decomposition Computation means for computing the agent supply amount and control means for controlling the equipment based on the computation results of the computation means are provided.
The storage means includes a supply amount (z) of a disinfectant necessary for decomposing the disinfectant in seawater discharged from the ballast tank, and a disinfectant concentration (x) in seawater discharged from the ballast tank. (Z = cx + d, c; predetermined coefficient (slope), d: intercept).

In the sterilizing agent decomposing agent supply amount control device configured as described above, the measuring device measures the sterilizing agent concentration in the seawater discharged from the ballast tank. And a calculating means inputs the measured value of a measuring device, and calculates _| requires disinfectant density _| concentration average value _xave of predetermined time. Then, the computing means computes the disinfectant disinfectant supply amount (z) corresponding to the disinfectant concentration average value x _ave based on the relational expression stored in the storage means. The control means adjusts and controls the sterilizing agent decomposing agent supply pump and the valve opening of the sterilizing agent decomposing agent supply device based on the sterilizing agent decomposing agent supply amount (z) calculated by the calculating means.

  Sodium sulfite, sodium bisulfite (sodium hydrogen sulfite), and sodium thiosulfate can be used as the disinfectant decomposing agent supplied to chlorine disinfectants such as sodium hypochlorite and chlorine. Enzymes such as sodium sulfite, sodium bisulfite (sodium hydrogen sulfite), sodium thiosulfate, and catalase can be used as the disinfectant decomposer supplied to hydrogen oxide.

  The ballast water treatment apparatus according to an eighth aspect of the present invention is the one according to the seventh aspect, wherein the disinfectant supply agent control apparatus measures the flow rate of seawater to be treated and averages the flow rate for a predetermined time. And the supply amount of the bactericide decomposer is adjusted based on the average value of the flow rate.

When the flow rate of the seawater to be processed fluctuates, it is necessary to correct the supply amount of the disinfectant decomposer. Therefore, in the eighth embodiment of the present invention, the disinfectant supply amount z ′ is adjusted based on the following equation.
z ′ = z · (Q _ave / Q _s )
Q _ave : Flow rate average value Q _s : Reference flow rate In the eighth embodiment of the present invention, since the bactericidal agent decomposing agent supply amount is corrected according to the fluctuation of the seawater flow rate, the bactericide decomposing agent supply amount is controlled with higher accuracy. can do.
The average flow rate is an average flow rate for a predetermined time. Further, the reference flow rate is the flow rate of seawater when the bactericide decomposing agent supply amount z _s corresponding to the reference bactericide concentration is obtained.

  The ballast water treatment apparatus according to the ninth aspect of the present invention is the apparatus of any one of the third to eighth aspects described above, which receives the supply of seawater supplied with a disinfectant and generates cavitation in the seawater. A venturi tube that diffuses the disinfectant into the seawater and damages or kills aquatic organisms in the seawater, and the disinfectant concentration detecting means determines the disinfectant concentration in the seawater at the outlet side of the venturi tube. It is comprised so that it may detect.

Venturi tubes cause cavitation in seawater supplied with disinfectants to damage or kill relatively small aquatic organisms such as phytoplankton. Further, the sterilizing agent is rapidly diffused into seawater by cavitation to promote the sterilizing action of bacteria by the sterilizing agent.
In this way, since the mixing of the bactericide into the seawater is promoted by the diffusion action of cavitation by the venturi tube, the supply amount of the bactericide can be reduced as compared with the case where only the bactericide is supplied. For this reason, the influence on the environment by a disinfectant can be reduced, and supply of a disinfectant decomposer for rendering the disinfectant harmless can be eliminated or reduced.

  In addition, when a venturi pipe is provided, it is preferable that a disinfectant supply apparatus supplies a disinfectant to the upstream of a venturi pipe and / or the throat part of a venturi pipe. When supplying the bactericidal agent to the upstream side of the venturi pipe, the bactericidal agent is diffused to some extent in the pipe before reaching the throat of the venturi pipe where cavitation occurs, and then the diffusion and mixing of the bactericidal agent are advanced by cavitation. Furthermore, since the penetration of the fungicide into the bacteria can be promoted, the killing effect of the fungicide can be promoted.

In order to supply the bactericidal agent to the upstream side of the venturi pipe, a bactericidal agent inlet may be provided on the straight pipe upstream of the venturi pipe.
Further, when supplying the sterilizing agent to the throat of the venturi pipe, the supply pump is not necessary because the self-priming is performed by the ejector action of the venturi pipe.

A ballast water treatment apparatus according to a tenth aspect of the present invention is the filtration apparatus according to any one of the third to ninth aspects, wherein seawater is filtered to capture aquatic organisms upstream of the disinfectant supply apparatus. A device is provided.
In order to capture and remove relatively large aquatic organisms such as zooplankton in seawater with a filtration device, supply a bactericidal agent necessary to kill relatively small aquatic organisms such as phytoplankton and bacteria. The supply amount of the bactericidal agent can be reduced, the influence on the environment can be reduced, and the supply of the bactericidal agent decomposing agent for detoxifying the bactericidal agent can be made unnecessary or reduced.

  In the present invention, a certain amount of fungicide set as saturated is supplied into seawater, and when saturated, the concentration difference between the saturated concentration at that time and the target fungicide concentration is determined, Since the amount of the bactericidal agent to be reduced is obtained from the supply amount that is supplied in a certain amount based on the concentration difference and the reduced supply amount is injected, it is necessary to reach the target residual concentration of the bactericide. Time is shortened and hence the amount of disinfectant supplied can be reduced.

Further, in the fifth to tenth aspects of the present invention, there is provided feedback control means for feedback-controlling the supply amount of the bactericide to be supplied after the reduction supply instruction is given. Since the amount of fungicide supplied is adjusted based on the average value of the fungicide concentration over time, the residual concentration of the fungicide may fluctuate, or the time and fungicide that diffuses into the seawater after supplying the fungicide will exhibit a bactericidal effect Even if there is a time delay such as the time to do so, the amount of the bactericide supplied can be accurately controlled.
Further, an upper and lower limit range of the sterilizing agent concentration that can be allowed with respect to the sterilizing agent concentration target value is determined in advance as a dead zone range, and when the dead zone is deviated, an operation for adjusting the sterilizing agent supply amount is performed. Therefore, it is not necessary to frequently adjust the output of the supply pump, such as the rotation speed, and the opening of the valve, so that problems such as the supply pump are less likely to occur.

[Embodiment 1]
Hereinafter, an example of the best mode of the ballast water treatment apparatus according to the present invention will be specifically described with reference to the drawings.
FIG. 1 is a block diagram showing a ballast water treatment apparatus according to the first embodiment of the present invention.
The ballast water treatment device of the present embodiment includes a seawater intake line 1, a coarse filtration device 2, a pump 3, a filtration device 4, a bactericidal agent supply device 5, a venturi pipe 6, and a bactericide decomposing agent supply. A device 7, a sterilized water supply line 8, a ballast tank 9, a sterilizing agent decomposition processing line 11, and a sterilizing agent decomposition processing water drain line 12 are provided.

The detoxification treatment of ballast water is based on the amount of microorganisms inhabiting the area of the water to be taken and the operating conditions of the ship, when the ballast water is loaded into the ballast tank, at the time of drainage, or both. Can be determined by.
In the following description, when the ballast water is loaded, the biocidal process is performed in the seawater, and the ballast water stored in the ballast tank 9 is supplied when the ballast water is discharged, and the disinfectant is supplied to the ballast water. A case where the disinfectant is decomposed and discharged into the sea will be described.
First, each component used in this case will be described in detail.

  Seawater intake line 1 takes seawater into the ship. The coarse filtration device 2 removes coarse substances in the seawater taken from the seawater intake line 1. The pump 3 takes in seawater or discharges ballast water in a ballast tank 9 described later into the sea through a disinfectant disinfectant supply device 7 described later.

  The filtration device 4 removes planktons present in the seawater from which coarse substances have been removed by the coarse filtration device 2. The disinfectant supply device 5 supplies the disinfectant to the seawater filtered by the filter device 4 to kill bacteria and plankton. The venturi 6 introduces seawater (filtered water) to which a bactericidal agent is added, generates cavitation in the seawater, damages or kills aquatic organisms in the seawater, and disinfects the bactericidal agent supply device 5. Disperse the disinfectant supplied in the seawater.

The sterilized water supply line 8 sends the seawater after the biocidal process discharged from the venturi 6 to a ballast tank 9 described later. The ballast tank 9 stores seawater after the biocidal treatment sent from the sterilized treated water feed line 8 as ballast water. The disinfectant decomposition processing line 11 sends the ballast water in the ballast tank 9 to the disinfectant disinfectant supply device 7 by the pump 3.
The disinfectant decomposer supply apparatus 7 supplies the disinfectant decomposer to the ballast water in which the disinfectant remains. The sterilizing agent decomposition treatment water drain line 12 is supplied with the sterilizing agent decomposing agent and discharges the ballast water after the sterilizing agent decomposing process to the sea.
Hereinafter, each device will be described in more detail.

1. Coarse filter device Coarse filter device 2 receives water from a sea chest (seawater inlet) provided on the side of the ship and is taken by seawater intake line 1 by pump 3 and contains various small and large contaminants and aquatic organisms. Among them, coarse materials of about 10 mm or more are removed.
As the coarse filtration device, a cylindrical strainer (strainer) having a hole of about 10 mm, a hydrocyclone that separates coarse matter in the water flow by the difference in specific gravity, a device that captures and collects the coarse matter with a rotating screen, etc. are used. be able to.

2. Filtration device The filtration device 4 removes planktons present in the seawater from which coarse substances have been removed by the coarse filtration device 2, and has a mesh size of 10 to 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. Conversely, 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 is increased and the ballast water treatment time at the port of call is increased. Since it becomes long, it is not preferable. In particular, it is preferable to use a material having an opening of about 20 to 35 μm because the capture rate and the backwashing frequency can be set optimally.
Moreover, the filtration device 4 is preferably 1 day 200 meters ³ or more filtration rate per filtration area 1 m ² is obtained. However, there is no particular limitation when the size can be further reduced by integrating the filtration modules.

As a specific example of the filtration device 4, it is preferable to use a notch wire filter or a wedge wire filter.
A notch wire filter is a cylindrical element in which a wire with a notch (protrusion) is wound around a frame and the distance between the wires is maintained by the notch so that the size of the filtration passage is 10 to 200 μm. , Provided with valves and piping for water supply and backwashing. A specific example of this notch wire filter is a notch wire filter manufactured by Kanagawa Kikai Kogyo.
Japanese Laid-Open Patent Publication No. 2001-170416 discloses a plurality of notch wire filters as filtration elements and backwashing means. By attaching a small ultrasonic vibrator to the filtration element assembly substrate and each filtration element and adding ultrasonic vibration during backwashing, the backwashing effect is increased and the backwashing interval is extended to increase the filtration efficiency. Can do.
A wedge wire filter is a tubular element that has a triangular cross-section wound around a frame and adjusts the distance between the wires to maintain a filtration passage size of 10 to 200 μm in the casing. A valve and piping are provided. As a specific example of this wedge wire filter, there is a wedge wire filter manufactured by Toyo Screen Industries.

Another preferred specific example of the filtration device 4 is a laminated disk type filter. A laminated disk type filter is a ring-shaped disk formed by pressing doughnut-shaped disks having a plurality of oblique grooves formed on both sides in an axial direction to form a ring, and a gap formed by grooves of adjacent disks. The aquatic organisms are filtered through the water. By appropriately setting the size of the oblique grooves, the openings are set to 10 to 200 μm and filtered.
In the laminated disk type filter, the disk pressure is released during backwashing to increase the gap and remove the filtration residue.
A specific example of this laminated disk type filter is Spin Klin Filter Systems manufactured by Arkal Filtration Systems.
In addition to the two types of filtration devices described above, other various filtration devices such as a sealed sand filter, a filter cloth filter, and a metal fiber filter can be used as the filtration device 4.

3. Disinfectant supply device The disinfectant supply device 5 supplies the disinfectant that kills bacteria to the seawater filtered by the filtration device 4 and supplied to the venturi tube 6.
As shown in FIG. 2, the disinfectant supply device includes a disinfectant storage tank 21 for storing disinfectant, a pipe 23 for supplying the disinfectant in the disinfectant storage tank 21 to the venturi pipe side, and a distal end side of the pipe 23. It is provided with an inlet 25 for injecting a sterilizing agent into a supply destination, a supply pump 27 for supplying the sterilizing agent in the sterilizing agent storage tank to the venturi pipe side, a valve 29 for adjusting the supply amount of the sterilizing agent, and the like. .
As the disinfectant to be supplied, chlorine, chlorine dioxide, sodium hypochlorite, hydrogen peroxide, ozone, peracetic acid or a mixture of two or more of these can be used, but other disinfectants can also be used. It is.

In addition, when using sodium hypochlorite as a disinfectant, it is preferable to supply so that the density | concentration of the amount of effective chlorine in seawater may be 1-100 mg / l.
The reason is that when the concentration of effective chlorine is less than 1 mg / l, hypochlorous acid does not remain after reacting with reducing substances and organic substances in water, and when it is greater than 100 mg / l, corrosion problems and hypochlorous acid occur. This is because there is a problem that the storage tank for sodium becomes large and the cost is high, resulting in problems.

The disinfectant is supplied to the upstream side of the venturi 6 and / or the throat of the venturi 6. When supplying the disinfectant to the upstream side of the venturi 6, disinfect the disinfectant to some extent in the tube until it reaches the throat of the venturi tube where cavitation occurs, and then proceed with diffusion and mixing of the disinfectant by cavitation. Furthermore, the disinfecting effect of the disinfectant can be promoted by promoting the penetration of the disinfectant into the bacteria.
In order to supply the bactericidal agent to the upstream side of the venturi pipe 6, a bactericidal agent inlet may be provided on the straight pipe upstream of the venturi pipe 6.
Further, when the sterilizing agent is supplied to the throat portion of the venturi pipe 6, it is self-primed by the ejector action of the venturi pipe 6, so that a supply pump becomes unnecessary.
The sterilizing agent supply device 5 is controlled by the sterilizing agent supply amount control device 101 shown in FIG. 2, and an appropriate amount of sterilizing agent is supplied to a predetermined location.

4). Disinfectant supply amount control device The disinfectant supply amount control device 101 measures the disinfectant concentration meter 33 for measuring the disinfectant concentration in the seawater discharged from the venturi tube 6 and the flow rate of the seawater discharged from the venturi tube 6. A flow meter 35 for storing, a storage means 103 for storing various data, a constant amount supply instruction means 105 for instructing a sterilizing agent supply device to supply a predetermined amount of sterilizing agent at the beginning of the supply of the sterilizing agent, Saturation determination means 107 for determining whether or not the bactericide concentration is saturated based on the detection value of the agent concentration detection means, and when the saturation determination means 107 determines that the concentration is saturated, A reduced bactericidal supply amount calculating means 109 for calculating a concentration difference between the bactericidal agent concentration and a predetermined bactericidal concentration target value and calculating a bactericidal agent supply amount to be reduced based on the concentration difference; Based on the computed value of the computing means 109, the sterilizing agent supply device 111 for instructing the sterilizing agent supply amount to be reduced to the sterilizing agent supply device 5, and the feedback control of the sterilizing agent supply amount to be supplied after the reduced amount supply instruction is given. Feedback control means 113 for performing the operation.
The disinfectant concentration meter 33 measures the disinfectant concentration in the seawater discharged from the venturi pipe 6 and outputs it to the saturation determination means 107 and the reduced disinfectant supply amount calculation means 109. The flow meter 35 measures the flow rate of the seawater discharged from the venturi pipe 6 and outputs it to the weight loss sterilizer supply amount calculation means 109.

The storage means 103 stores a predetermined fungicide concentration target value (x _s ) as a minimum target value of the bactericide necessary for killing bacteria in seawater.
The storage means 103 stores the supply amount of the bactericidal agent to be supplied at the beginning of the supply of the bactericidal agent.

The fixed amount supply instructing means 105 reads the amount of sterilizing agent to be supplied at the beginning of supplying the sterilizing agent stored in the storage means 103 and instructs the sterilizing agent supply device 5 to supply it.
The saturation determination unit 107 determines whether or not the bactericide concentration is a saturation value based on the detection value of the bactericide concentration detection unit.
The determination of whether or not the bactericide concentration is saturated by the saturation determination means 107 is made based on whether or not the amount of time change of the bactericide concentration is equal to or less than a predetermined change amount. More specifically, the bactericide concentration by the bactericide concentration meter 33 is input every predetermined time, and whether the difference between the current input concentration and the previous input concentration is equal to or less than a predetermined value. When the difference is equal to or less than a predetermined value for three consecutive times, it is determined that the state is saturated.

The reduced amount bactericide supply amount calculation unit 109 obtains a concentration difference between the bactericide concentration at that time and a predetermined bactericide concentration target value when it is determined that the saturation determination unit 107 is saturated. Based on the difference, the disinfectant supply amount to be reduced is calculated.
For example, a specific example of the case where sodium hypochlorite is injected as a bactericide is as follows.
y: Sodium hypochlorite constant injection [L / min]
dy: Sodium hypochlorite injection amount to be reduced calculated from the saturation value
dC: Difference between the saturated fungicide concentration and the predetermined fungicide concentration target value
Qr: Rated flow [m ³ / h]
given that,
dy = (dC × Qr) / (0.12 × 1.1 × 60 × 10 ³ )

The reduced amount supply instructing unit 111 instructs the sterilizing agent supply device 5 on the sterilizing agent supply amount to be reduced based on the calculated value of the reduced amount sterilizing agent supply amount calculating unit 109.
The feedback control unit 113 feedback-controls the supply amount of the bactericide to be supplied after the reduction supply instruction is given. The feedback control may be, for example, general feedback (PID) control, or dead zone control described in the second embodiment. However, the dead zone control does not require frequent adjustment of output such as the rotation speed of the supply pump and adjustment of the opening of the valve, so that it is possible to obtain an effect that problems such as supply pumps are less likely to occur.

  Each means is realized when a CPU provided in the computer executes a predetermined computer program.

5). Venturi tube Venturi tube 6 causes organisms that have passed through filtration device 4 to be damaged or killed by cavitation generated by the venturi tube, and disinfects the disinfectant supplied from disinfectant supply device 5 into seawater. It is.
The Venturi pipe 6 is composed of a throttle portion where the pipe cross-sectional area gradually decreases, a throat portion which is the minimum cross-sectional area portion, and a widened portion (diffuser portion) where the pipe cross-sectional area gradually increases. Cavitation bubbles are generated by a rapid decrease in static pressure accompanying a rapid increase in flow velocity at the throat, and the cavitation bubbles that have grown due to a rapid increase in pressure accompanying a decrease in flow velocity at the spreading portion are rapidly collapsed. Aquatic organisms in seawater are damaged or destroyed by the action of OH radicals with impact pressure, shearing force, high temperature, and strong oxidizing power due to the collapse of cavitation bubbles.
According to the cavitation of this Venturi tube 6, it is possible to destroy and kill the protozoan having a relatively hard shell, the outer shell of zooplankton, in particular.

  In addition, cavitation is generated by the Venturi tube 6 to cause damage or death to relatively small aquatic organisms such as phytoplankton, and the fungicide is rapidly diffused into the seawater by cavitation, so that the bacteria by the fungicide Promotes the bactericidal action of In this way, mixing of the bactericidal agent into seawater is promoted by the diffusion action of cavitation, so the supply amount of the bactericidal agent can be reduced compared to the case of simply injecting the bactericidal agent, and the influence on the environment can be reduced. Further, it is possible to eliminate or reduce the supply of the disinfectant disinfectant for detoxifying the disinfectant.

In addition, when supplying seawater to the venturi pipe 6, it is preferable to feed the seawater so that the flow rate of seawater at the throat of the venturi pipe 6 is 10 to 40 m / sec.
The reason for this is that when a ballast water treatment device is installed in the middle of a pipe that takes seawater and passes it to the ballast tank, the flow rate of seawater in the pipe is usually 2 to 3 m / s at the venturi pipe entrance. When the flow velocity at the throat of the pipe is less than 10 m / sec, the rate of increase in the flow velocity at the throat is not sufficient, and the rapid decrease in static pressure associated therewith is not sufficient, so that cavitation does not occur even under atmospheric pressure. On the other hand, if the flow velocity at the venturi pipe throat is greater than 40 m / s, the cavitation phenomenon will occur excessively, the pressure loss associated with the passage through the venturi pipe will be excessive, and the energy consumed for water supply will be excessive, so the pump power will be excessive. This is because the cost becomes high.

6). Disinfectant decomposer supply device The disinfectant decomposer supply device 7 detoxifies the disinfectant by supplying the disinfectant decomposer to the seawater to which the disinfectant is added to decompose the disinfectant remaining in the seawater. .
In this embodiment, the sterilizing agent decomposing agent supply device 7 is provided in the sterilizing agent decomposing treatment line 11, and the sterilizing agent decomposing agent is added to the ballast water in which the sterilizing agent stored in the ballast tank 9 remains when the ballast water is discharged. The disinfectant is decomposed and discharged into the sea.
As shown in FIG. 3, the disinfectant decomposer supply device 7 stores the disinfectant decomposer storage tank 51 for storing the disinfectant decomposer and the disinfectant decomposer in the disinfectant decomposer storage tank 51 in the disinfectant decomposition treatment line 11. A pipe 53 for supply, provided on the front end side of the pipe 53, and provided on the upstream side of the pump 3 of the bactericidal agent decomposition treatment line 11, injecting the bactericidal agent decomposing agent into the ballast water in which the bactericidal agent remains. And a supply pump 57 for supplying the disinfectant decomposition agent in the disinfectant storage tank 51 to the disinfectant decomposition processing line 11, a valve 59 for adjusting the supply amount of the disinfectant disassembly agent, and the like. .

Sodium sulfite, sodium bisulfite (sodium hydrogen sulfite), and sodium thiosulfate can be used as a disinfectant decomposer supplied to chlorine disinfectants such as sodium hypochlorite and chlorine.
Moreover, as a disinfectant decomposer supplied with respect to hydrogen peroxide, enzymes such as sodium sulfite, sodium bisulfite (sodium hydrogen sulfite), sodium thiosulfate, and catalase can be used. However, it is not limited only to these. An enzyme such as catalase works as a catalyst for the decomposition reaction and has a long reaction time.
The sterilizing agent decomposing agent supply device 7 is controlled by the sterilizing agent decomposing agent supply amount control device 61 shown in FIG. 3, and an appropriate amount of the sterilizing agent decomposing agent is supplied to a predetermined location.

7). Bactericide Degradant Supply Amount Control Device A bactericide decomposer supply amount control device 61 is discharged from the ballast tank 9 and a bactericide concentration meter 63 that measures the residual concentration of the bactericide in the seawater discharged from the ballast tank 9. A flow meter 65 that measures the flow rate of seawater, a bactericide concentration meter 66 that measures the residual concentration of bactericide in seawater supplied with a bactericide decomposer and decomposed, and a storage means 67 that stores various data. And a calculation means 69 for calculating the supply amount of the bactericidal agent decomposition agent, and a control means 71 for controlling the equipment based on the calculation result of the calculation means 69.

The disinfectant concentration meter 63 measures the disinfectant concentration in the seawater discharged from the ballast tank 9 and outputs it to the calculation means 69. The flow meter 65 measures the flow rate of seawater discharged from the ballast tank 9 to the sea and outputs it to the computing means 69. The disinfectant concentration meter 66 measures the residual disinfectant concentration in the seawater supplied with the disinfectant decomposer and decomposed, and outputs it to the calculation means 69.
As the disinfectant concentration meter 63, for example, when measuring residual chlorine derived from a chlorine disinfectant, a high concentration residual chlorine meter (for example, the measurement range is 0 to 30 mg / l) and a low concentration residual chlorine meter (for example, the measurement range is 0). By performing split detection of residual chlorine concentration using ˜3 mg / l), the detection accuracy of low concentration residual chlorine can be improved.

As the disinfectant concentration meter 66 for measuring the disinfectant residual concentration in the seawater in which the disinfectant is decomposed, a low concentration disinfectant concentration meter capable of detecting a low concentration disinfectant concentration is preferable. It is preferable to use a low-concentration residual chlorine meter having a mechanism for measuring a reduction current corresponding to the free residual chlorine concentration. By using such a low-concentration residual chlorine meter that has high detection accuracy for low-concentration residual chlorine and can detect the absence of residual chlorine, the amount of chlorinated agent supplied is controlled to ensure that residual chlorine is eliminated. In addition, it can be confirmed that the residual chlorine is decomposed and the residual chlorine is gone.
The storage means 67 stores a relational expression (z = cx + d, c; predetermined coefficient (slope), d; intercept, which is predetermined as a relation between the disinfectant supply amount (z) and the disinfectant residual concentration (x). ) Is stored.
The above relational expression is based on the condition that affects the process until the supplied disinfectant decomposer is diffused and exhibits its effectiveness as an effective disinfectant disinfectant, and the disinfectant disinfectant supply amount (z) And the disinfectant residual concentration (x).

The calculation means 69 inputs the measurement result of the bactericide concentration meter 63 and obtains the average value of the bactericide residual concentration for a predetermined time. Further, the measurement result of the flow meter 65 is input, and the average value of the flow rate in a predetermined time is obtained.
Further, the supply amount of the sterilizing agent decomposing agent to be supplied is calculated based on the sterilizing agent residual concentration average value and the data stored in the storage means 67. A specific method for calculating the disinfectant supply amount of the disinfectant will be described later.
Based on the calculation result of the calculation means 69, the control means 71 performs output control such as the rotation speed of the supply pump 57 and / or adjustment of the opening of the valve 59 for adjusting the supply amount.
Further, the calculation means 69 inputs the measurement result of the bactericide concentration meter 66, and when the bactericidal residual concentration is larger than the allowable value, the control means 71 adjusts the bactericidal agent supply amount to be supplied. Or the bactericide concentration indicator may be output to a bactericide concentration indicator (not shown).

The operation of the present embodiment configured as described above will be described.
Using the ballast water treatment device shown in Fig. 1, the bacteria and plankton are killed when the ballast water is loaded, and the disinfectant remaining in the seawater is decomposed and detoxified when the ballast water is discharged. A method for treating ballast water will be described.

<Operation when loading ballast water>
When the ballast water is loaded, the pump 3 is operated to take seawater from the seawater intake line 1 into the ship, the coarse filter 2 removes coarse material, and the filter 4 is sized according to the opening of the filter 4. Remove plankton.
A bactericidal agent is supplied to the seawater filtered by the filtering device 4 by the bactericide supplying device 5. The supply amount of the sterilizing agent is controlled by the sterilizing agent supply amount control device 101.

  FIG. 4 is a flow chart showing the procedure of the bactericide supply amount control by the bactericide supply amount control apparatus 101. FIG. 5 is a graph showing the time change of the bactericide concentration and the time change of the injection amount of the bactericide when the bactericide supply amount control in the present embodiment is performed. In the graph of FIG. 5, the left side of the vertical axis is the residual chlorine concentration (ppm), the right side of the vertical axis is the amount of sodium hypochlorite supply (L / min), and the horizontal axis is the time (min). It is.

Hereinafter, the procedure for controlling the supply amount of the bactericidal agent will be described with reference to FIG. 4, and the change over time of the bactericide concentration and the injection amount of the bactericide will be described with reference to FIG. In this example, hypochlorous acid soda is used as a disinfectant.
When the operation of the disinfectant supply device 5 is started, first, the start-up operation is started for a time T1 by a timer (S1). The start-up operation is an operation performed until the disinfectant supplied from the disinfectant storage tank 21 reaches the position where the disinfectant concentration meter 33 is installed.

The start-up operation is started and it is determined whether or not a predetermined time T1 has elapsed (S3). When the time T1 has elapsed, the fixed amount supply instructing means 105 is initially supplied with the sterilizing agent stored in the storage means 103. The supply amount of the sterilizing agent to be supplied is read out and a supply instruction is given to the sterilizing agent supply device 5 to start the operation of supplying a constant amount of sterilizing agent (S5). In this example, the constant supply amount of sodium hypochlorite is 0.495 L / min.
When the operation of supplying a constant amount of bactericide is started, the counter I is set to I = 0, and the bactericide concentration meter 33 measures the bactericide concentration (S9). The disinfectant concentration increases rapidly as shown in FIG. 5, and the rate of increase gradually decreases.
When the bactericide concentration measurement is started, the saturation determination means 107 determines whether or not the bactericide concentration is a saturated value. The determination whether or not the saturation value is reached is performed as follows.
It is determined whether the difference (dXc) between the previous (one time before) fungicide concentration measurement value and the latest measurement value is smaller than a predetermined value (dXs) (S11). If dXc is greater than dXs Repeat the concentration measurement.
When it is determined that dXc is smaller than dXs, the counter I is set to I = I + 1 (S13), and the process is repeated until the counter I = 3 or more (S15).
In this example, as shown in FIG. 5, it was determined that the saturated state was reached 10 minutes after the start of control.

When the counter I = 3 or more, the reduced bactericide supply amount calculating means 109 obtains a concentration difference between the bactericide concentration at that time and a predetermined bactericide concentration target value, and reduces the amount based on the concentration difference. The amount of sterilizing agent to be supplied is calculated (S17). The calculation method of the supply amount of the bactericide to be reduced is as described above, and a specific calculation example shown in FIG. 5 is shown below.
y: Sodium hypochlorite constant injection [L / min] = 0.495 L / min
dC: Difference between saturated fungicide concentration and predetermined fungicide concentration target value = 5ppm
Qr: Rated flow [m ³ / h] = 250m ³ / h
dy: Sodium hypochlorite injection amount to be reduced calculated from the saturation value,
dy = (5 [ppm] × 250 [m ³ /h])/(0.12×1.1×60×10 ³ ) = 0.158 [L / min]
Therefore, if the injection amount after reducing the dose is yt,
yt = 0.495 [L / min]-0.158 [L / min] = 0.337 [L / min]
It becomes.

When the sterilizing agent supply amount to be reduced is calculated, the declining supply instructing unit 111 instructs the sterilizing agent supply device 5 on the sterilizing agent supply amount to be reduced based on the calculated value of the reduced sterilizing agent supply amount calculating unit 109. Thus, the reduced amount of the bactericide is supplied (S19).
When a predetermined time (for example, 5 minutes) elapses after the reduced amount supply instruction is given, the feedback control means 113 performs feedback control using the bactericide concentration as a target value (S21). In the example shown in FIG. 5, the feedback control performs the dead zone control shown in the second embodiment, and the supply amount of the bactericide is changed 15 minutes after the start of the control.
It is determined whether or not the feedback control is to be ended (S23).

Seawater to which a bactericidal agent is added is introduced into the venturi pipe 6. In the venturi tube 6, cavitation is generated to damage aquatic organisms, and diffusion of the bactericidal agent into seawater is promoted to increase the bactericidal effect.
Seawater treated by the venturi pipe 6 is sent to the ballast tank 9 via the sterilized treated water feed line 8 and stored. In the seawater stored in the ballast tank 9, it is preferable that the disinfectant supplied by the disinfectant supply device 5 remains at an appropriate concentration. Thereby, regrowth of bacteria and plankton can be controlled.

As described above, in the present embodiment, zooplankton and phytoplankton of 10 to 200 μm or more are removed by the filtration device 4 and the bacteria and plankton that have passed through the filtration device 4 by the venturi 6 are damaged. In addition, since bacteria and plankton were killed by killing them and supplying appropriate amounts of bactericides, treatment of ballast water that meets the ballast water standards set by IMO was realized reliably and inexpensively regardless of the water quality. it can.
And in this embodiment, a certain amount of bactericide set as being saturated is supplied into seawater, and when saturated, the saturated bactericide concentration at that time and the target bactericide concentration Since the concentration difference is obtained, the amount of the bactericidal agent to be reduced is obtained from the supply amount that is supplied in a certain amount based on the concentration difference, and the reduced bactericidal agent supply amount is supplied. The time required to reach the chlorine concentration is shortened, and therefore the amount of disinfectant supplied can be reduced.

<Operation when discharging ballast water>
At the time of discharging the ballast water, the pump 3 is operated to introduce the ballast water from the ballast tank 9, and the bactericide decomposer is supplied from the bactericide decomposer supply device 7 provided in the bactericide decompose treatment line 11 and remains. Decomposes the disinfectant.
The supply amount of the bactericide decomposer is controlled by the bactericide decomposer supply amount controller 61, and an appropriate amount of bactericide decomposer is supplied to a predetermined location. Hereinafter, a method for controlling the supply amount of the disinfectant decomposition agent will be described.

The disinfectant concentration meter 63 measures the disinfectant residual concentration in the seawater discharged from the ballast tank 9 and outputs it to the calculation means 69.
The calculating means 69 inputs the measurement result of the bactericide concentration meter 63 and obtains the bactericide residual concentration average value x _ave for a predetermined time. When the average disinfectant residual concentration value x _ave is obtained, the disinfectant supply amount z of the disinfectant is obtained based on the relational expression (z = cx + d, c; predetermined coefficient (slope), d: intercept).
Based on the calculation result of the calculation means 69, the control means 71 performs output control such as the rotation speed of the supply pump 57 and / or adjustment of the opening of the valve 59 for adjusting the supply amount.
The ballast water that has been supplied with an appropriate amount of the bactericide decomposing agent and has been subjected to the disinfecting process of the bactericide is discharged into the sea via the bactericide decomposing water drain line 12.
Further, the calculation means 69 inputs the measurement result of the bactericide concentration meter 66, and when the bactericidal residual concentration is larger than the allowable value, the control means 71 adjusts the bactericidal agent supply amount to be supplied. Or a bactericide concentration indicator may be output to a bactericide concentration indicator. It is possible to confirm that the residual germicide is not decomposed by displaying the germicide concentration on the germicide concentration indicator.

In addition, by measuring the flow rate of seawater at which the disinfectant is decomposed to obtain a flow average value for a predetermined time, and adjusting the disinfectant disintegrant supply amount according to the flow average value, a more appropriate amount of disinfectant can be decomposed. The agent can be supplied. In this case, the calculation means may calculate the disinfectant disinfectant supply amount z ′ based on the following formula.
z ′ = z · (Q _ave / Q _s )
Q _ave ; Average flow rate Q _s ; Reference flow rate

The above example is a case in which the biological killing process is performed when seawater is loaded into the ballast tank 9, but when the seawater is loaded into the ballast tank, the biological killing process is not performed and the ballast tank 9 is discharged. In some cases, the organism is killed.
In this case, untreated seawater is stored in the ballast tank 9 via an untreated seawater water supply line (not shown). When this ballast water is discharged from the ballast tank 9, untreated ballast water in the ballast tank 9 is introduced to the filtration device 4 side via a ballast water supply line (not shown), and thereafter the same as above. Perform the process.
The ballast water that has been subjected to the biocidal treatment is introduced into the disinfectant disinfectant supply device 7 and supplied with the disinfectant decomposer, so that the remaining disinfectant is decomposed. The ballast water after the disinfecting process of the disinfectant is discharged into the sea.
Further, the biological killing process in the ballast water may be performed both when the seawater is loaded into the ballast tank 9 and when the seawater is discharged from the ballast tank 9. In that case, the biological killing process at the time of discharge of ballast water may be mild.

  In addition, although the example shown in FIG. 1 assumes that the detoxification treatment of ballast water is performed at the time of loading into a ballast tank and / or at the time of draining into the sea, either at the time of loading or at the time of draining The timing at which the treatment is performed can be determined depending on the amount of microorganisms inhabiting the water intake area and the operational conditions of the ship.

[Embodiment 2]
FIG. 6 shows a configuration when dead zone control is performed as the feedback control means 113. 2 that are the same as those shown in FIG. 2 are denoted by the same reference numerals, and those other than the feedback control means 113 are omitted from the configuration of the disinfectant supply control device 31.
The feedback control unit 113 according to the present embodiment includes a storage unit 37 that stores various data, a calculation unit 39 that calculates a bactericidal agent supply amount, and a control unit that controls the apparatus based on the calculation result of the calculation unit 39. 41.
The disinfectant concentration meter 33 measures the disinfectant concentration in the seawater discharged from the venturi pipe 6 and outputs it to the calculation means 39. The flow meter 35 measures the flow rate of the seawater discharged from the venturi pipe 6 and outputs it to the computing means 39.

The storage unit 37 stores the following data (a) to (c).
(A) Bactericide concentration target value (x _s ) determined in advance as a minimum concentration target value of a bactericide necessary for killing bacteria in seawater
(B) Dead zone range (x _s (1−c _L ) ≦ dead zone range ≦ x _s (1 + c _H )) that is predetermined as an upper and lower limit range of the bactericide concentration that can be allowed with respect to the fungicide concentration target value. ,
c _L ; dead zone lower limit width (for example, greater than 0 and less than 0.20)
c _H : Deadband upper limit width (for example, greater than 0 and less than 0.50)
In some cases, c _L and c _H are equal.
The reason why the range of the dead zone lower limit width c _L is made smaller than the range of the dead zone upper limit width c _H is to increase the lower limit of the concentration of the bactericide so as to ensure that the organism killing process is performed.
(C) Predetermined relational expression (y = ax + b, a; predetermined coefficient (slope) as a relation between the bactericidal agent supply amount (y) and the bactericidal agent concentration (x), a number greater than 0 and less than 1 ; Predetermined coefficient, b; intercept, number greater than 0 and less than 1)
The above relational expression takes into account the conditions that affect the process until the supplied bactericidal agent is diffused and becomes effective as an effective bactericidal component, and the bactericidal agent supply amount (y) and bactericidal agent concentration (x ).
Incidentally, bactericide supply amount _{y s} for fungicides density target value _{x s becomes} y s = _ax s + b.

The calculation means 39 inputs the measurement result of the bactericide concentration meter 33 and obtains the bactericide concentration average value for a predetermined time. In addition, the measurement result of the flow meter 35 is input to obtain the average flow rate value for a predetermined time.
Further, it is determined whether or not the average value of the bactericidal agent concentration deviates from the upper and lower limit ranges of the bactericidal agent concentration that can be allowed with respect to the target value of the bactericide concentration. And when it has deviated, the bactericidal agent supply amount which should be supplied is calculated based on the data memorize | stored in the memory | storage means 37. FIG. A specific method of calculating the bactericidal agent supply amount will be described later.
The control means 41 controls the output of the supply pump 27 and / or the opening of the supply amount adjusting valve 29 based on the calculation result of the calculation means 39.

The operation of the present embodiment configured as described above will be described.
Since the operation from the start of operation to the feedback control operation is the same as that described in the first embodiment (see FIG. 4), the feedback control will be described below.
FIG. 7 is a flowchart showing the procedure of feedback control of the present embodiment. Hereinafter, feedback control operation will be described with reference to FIG.

When the feedback operation is started, the timer is set at time T2 (S31), and the bactericide concentration is measured by the bactericide concentration meter (S33). It is determined whether or not the time T2 has elapsed (S35). If it is determined that the time has elapsed, the average value x _ave of the measured concentration during the time T2 is obtained (S37). x _ave is obtained by dividing the sum of the measured concentrations by the number of measurements.
Then, the disinfectant concentration average value x _ave dead band range of disinfectant concentration predetermined _{(x s (1-c L} ) ≦ deadband range _{≦ x s (1 + c H} ), c L; dead zone lower limit width (e.g. greater than 0, less than 0.20), c _H; dead zone upper width (e.g., greater than 0, it is determined whether the deviation less than 0.50)) (S39).

And when it is judged that it has deviated, the disinfectant supply amount y (y) obtained by multiplying the disinfectant supply amount y by the dead zone control rate R _n to the disinfectant supply amount y _s corresponding to the target disinfectant concentration. = Y _s · R _n ) is obtained (S41). When the sterilizing agent supply amount y is obtained, the control means 41 inputs the obtained sterilizing agent supply amount y to obtain the obtained sterilizing agent supply amount. Alternatively, adjustment control of the opening degree of the supply amount adjustment valve 29 is performed. Then, it is determined whether or not the feedback control operation is finished (S43). If not finished, the process returns to the process of S31, the timer is reset, and the same process is repeated.
Note that the dead zone control rate R _n is expressed by the equation (1).
R _n = R _n−1 + (x _s −x _ave ) · a · w (1)
R _n-1 : dead zone control rate before 1 time (initial value of R R ₁ = 1)
a: Predetermined coefficient (greater than 0 and less than 1)
w: Dead band control width (greater than 0 and less than 1)

It should be noted that a more appropriate amount of bactericidal agent can be supplied by measuring the flow rate of the seawater to be processed, obtaining the flow rate average value for a predetermined time, and adjusting the bactericidal agent supply amount according to the flow rate average value. In this case, the calculation means 39 may calculate the bactericidal agent supply amount y based on the following formula.
y = y _s · R _n · (Q _ave / Q _s )
Q _ave ; Average flow rate Q _s ; Reference flow rate

According to the feedback control operation of the second embodiment, in order to adjust the supply amount of the bactericide based on the average value of the bactericide concentration for an appropriate time, there may be fluctuations in the residual concentration of the bactericide, Therefore, even if there is a time delay such as the time for diffusing into seawater or the time until the bactericidal agent exhibits the bactericidal effect, the bactericidal agent supply amount can be accurately controlled.
Further, an upper and lower limit range of the sterilizing agent concentration that can be allowed with respect to the sterilizing agent concentration target value is determined in advance as a dead zone range, and when the dead zone is deviated, an operation for adjusting the sterilizing agent supply amount is performed. Therefore, it is not necessary to frequently adjust the output of the supply pump, such as the rotation speed, and the opening of the valve, so that problems such as the supply pump are less likely to occur.

It is explanatory drawing of the ballast water treatment apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the disinfectant supply apparatus and the disinfectant supply amount control apparatus in the ballast water treatment apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the bactericidal agent decomposition agent supply apparatus in the ballast water treatment apparatus which concerns on one embodiment of this invention. It is a flowchart explaining operation | movement of the ballast water treatment apparatus in one embodiment of this invention. It is a graph which shows the time change of a residual chlorine concentration when supplying a disinfectant with the ballast water treatment apparatus in one embodiment of the present invention, and a disinfectant supply amount. It is explanatory drawing of the bactericide supply amount control apparatus in the ballast water treatment apparatus which concerns on other embodiment of this invention. It is a flowchart explaining operation | movement of the ballast water treatment apparatus in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seawater intake line 2 Coarse filtration device 3 Pump 4 Filtration device 5 Disinfectant supply device 6 Venturi pipe 7 Disinfectant supply device 8 Disinfection water supply line 9 Ballast tank 11 Disinfectant decomposition treatment line 12 Disinfectant decomposition treatment water 12 Drainage line 33 Disinfectant concentration meter 35 Flow meter 37, 103 Storage means 39 Calculation means 41 Control means 101 Disinfectant supply amount control device 105 Uniform supply instruction means 107 Saturation determination means 109 Decreasing disinfectant supply amount calculation means 111 Decrease supply instruction Means 113 Feedback Control Means

Claims (10)

When it is determined that it has become saturated, a certain amount supply step for supplying a certain amount of fungicide set as being saturated into seawater, a saturation determination step for determining whether the residual concentration of the disinfectant is saturated, and saturation In addition, the concentration difference between the saturated fungicide concentration at that time and the target fungicide concentration is obtained, and based on the concentration difference, the amount of the bactericide to be reduced from the supply amount injected in the constant amount supply step is determined. And a reduced weight supply step for supplying the reduced amount of the sterilizing agent supplied, and a ballast water treatment method. 2. The ballast water treatment method according to claim 1, wherein the saturation determination step determines whether or not the time change amount of the bactericide concentration is equal to or less than a predetermined change amount. A bactericide supply device that supplies bactericides into seawater, a bactericide concentration detection means that detects the bactericide concentration in seawater after the bactericides have been supplied, and a bactericide supply amount controlled by the bactericide supply device A bactericide supply amount control device
The sterilizing agent supply amount control device is based on a constant amount supply instructing means for instructing the sterilizing agent supply device to supply a predetermined amount of sterilizing agent at the beginning of supplying the sterilizing agent, and a detection value of the sterilizing agent concentration detecting means. Saturation determination means for determining whether or not the bactericidal concentration is saturated, and when the saturation determination means determines that the concentration is saturated, the bactericidal concentration at that time and a predetermined bactericidal concentration target A sterilizing agent supply amount calculating means for calculating a sterilizing agent supply amount to be reduced based on the concentration difference, and a sterilizing agent to be reduced based on the calculated value of the reducing sterilizing agent supply amount calculating means A ballast water treatment apparatus, comprising: a weight reduction supply instructing unit for instructing the agent supply amount to the disinfectant supply device. 4. The ballast water treatment apparatus according to claim 3, wherein the saturation determination means determines whether or not the time change amount of the bactericide concentration is equal to or less than a predetermined change amount. The sterilizing agent supply amount control device has feedback control means for feedback control of the sterilizing agent supply amount to be supplied after the reduced amount supply instruction is given. The feedback control means measures the concentration of the sterilizing agent in the seawater and determines the predetermined amount. The fungicide concentration average value for the time is obtained, and when the germicide concentration average value deviates from the dead zone range of the germicide concentration determined in advance, 5. The ballast water treatment according to claim 3, wherein the supply amount is adjusted by multiplying the supply amount of the bactericide according to the concentration of the bactericide to be obtained by multiplying the dead zone control rate R _n represented by the formula (1). apparatus.
R _n = R _n−1 + (x _s −x _ave ) · a · w (1)
R _n ; dead zone control rate R _n-1 ; dead zone control rate x _s ; previous bactericidal agent concentration target value x _ave ; bactericidal agent concentration average value a; predetermined coefficient w; dead zone control width The sterilizing agent supply amount control device measures the seawater flow rate to be processed, obtains an average flow rate value for a predetermined time, and adjusts the sterilizing agent supply amount according to the average flow rate value. Ballast water treatment equipment. A bactericidal agent supply device that supplies a bactericidal agent to the seawater supplied with the bactericide, and measures the concentration of the bactericide remaining in the seawater, and supplies the bactericide decomposer based on the measured bactericide concentration. The ballast water treatment apparatus according to claim 5, further comprising a bactericide decomposer supply amount control device that adjusts a bactericide decomposer supply amount of the apparatus. The sterilizing agent decomposing agent supply amount control device measures the flow rate of seawater to be processed, obtains an average flow rate value for a predetermined time, and adjusts the sterilizing agent decomposing agent supply amount based on the average flow rate value. The ballast water treatment apparatus according to 7. A venturi that receives supply of seawater supplied with a disinfectant, generates cavitation in the seawater, diffuses the disinfectant in the seawater, and damages or kills aquatic organisms in the seawater; The ballast water treatment apparatus according to any one of claims 3 to 8, wherein the disinfectant concentration detecting means is configured to detect a disinfectant concentration in seawater on the outlet side of the venturi tube. . The ballast water treatment device according to any one of claims 3 to 9, further comprising a filtration device that filters seawater and captures aquatic organisms upstream of the disinfectant supply device.

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