JPH04322788A - Method and device for disinfecting ballast water of ship - Google Patents

Abstract

PURPOSE:To offer the method and device for disinfecting ballast water, especially to extinguish cyst of harmful algae in ballast water. CONSTITUTION:The method for disinfecting ballast water features that cyst of harmful algae in ballast water is extinguished by using a chlorine-base microbicide or hydrogen peroxide and that pollution of harbors due to discharging of ballast water can be prevented. The device for disinfecting ballast water features that a supplying and discharging device for ballast water comprising a pump 3, sucking line 3a, and discharging line 3b, provided in a ship 10 is used, and that a microbicide tank 1 is connected to the sucking line 3a through a supply line 2 to add and mix the microbicide with the ballast water while the water is supplied with the pump 3. Moreover, an ejecting line 21 of a compressor 24 is connected to the discharging line 3b so that the ballast water while discharged with the pump 3 can be aerated and that the residual chlorine in the water is made harmless.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a sterilization method and a sterilization device used for sterilizing ballast water of ships, and more particularly to a ballast water sterilization method and a sterilization device for killing harmful algae cysts contained in the ballast water. Regarding.

0002

[Prior Art] In general, when ships that import ore, chips, etc. from other countries are dispatched to the other country, in order to avoid a lack of stability when the ship is empty, the ship's ballast tank is Seawater from the home port is injected into the vessel and used as ballast water.

[0003] When the above ship arrives at the other country,
This ballast water is discharged without any special treatment within the port of the partner country, and the imported goods are loaded.

0004

[Problem to be solved by the invention] In recent years, in countries such as Australia, shellfish poison that is toxic to clams, oysters, and other bivalve molluscs, and red tides have been occurring. ballast water.

[0005] That is, when ballast water is injected, shellfish poison from the coast of Japan, plankton from red tide, or cysts that are dormant cells thereof are also taken in, and these are discharged from the coast of Australia, causing the outbreak of shellfish poison, etc. There is.

[0006] In fact, Australian researchers have reported that they have discovered cysts of harmful algae unique to Japan (toxic dinoflagellate, alexandrium, which is said to live in temperate and low-temperature waters) in the ballast water of Japanese ships. ing.

[0007] Therefore, in view of the above-mentioned situation, many ships in Japan are currently voluntarily performing ballast water replacement (reballasting) while on the open ocean during navigation.

[0008] However, reballast has several problems as described below. (1) Extra cost is required. (2) Putting an extra burden on the hull strength. (3) Due to the hull structure, this is not possible for all ships. (4) There is a risk of causing environmental pollution in the sea area where it will be reballasted.

[0009] The present invention aims to solve these problems, and provides a ship that uses chemicals to kill harmful algae cysts in ballast water and that does not cause environmental pollution due to the chemicals. An object of the present invention is to provide a ballast water sterilization method and a ballast water sterilization device.

0010

[Means for Solving the Problems] In order to achieve the above-mentioned object, the ship ballast water sterilization method of the present invention eliminates cysts of harmful algae by adding chlorine-based disinfectant or hydrogen peroxide to ship ballast water. It is characterized by killing.

Further, the ballast water sterilization device for a ship according to the present invention includes a ballast tank, a pump for pouring and draining ballast water into the ballast tank, and suction piping and discharge piping connected to the pump, A sterilizer mixing device capable of mixing a sterilizer into the ballast water being poured into the ballast tank by the pump, and a waterfall device capable of blowing air into the ballast water being drained by the pump. It is said that

0012

[Function] In the ship ballast water sterilization method of the present invention described above, harmful algal cysts are killed by the chlorine-based disinfectant (sodium hypochlorite, calcium hypochlorite) or hydrogen peroxide added to the ballast water. do. The chemical has an effective chlorine amount of 2 to 100 ppm, and a hydrogen peroxide solution of 100 ppm.
~1000 ppm is suitable.

[0013] At this time, (1) Since sunlight does not shine inside the ballast tank, the vegetative cells (plankton) of harmful algae cannot grow and there is no need to take any measures against this. , remaining plankton will also be exterminated. (2) The chlorine content of the added chemicals disappears during the approximately one-week voyage, and by the time the ballast water is discharged in the destination country, the residual chlorine concentration is low enough not to degrade the environment. (3) Hydrogen peroxide becomes non-toxic within a short time after it exerts its sterilizing power, so there is no risk of degrading the environment when ballast water is discharged in the recipient country.

[0014] Although chlorine-based disinfectants and hydrogen peroxide are common disinfectants, they have never been used to exterminate red tide or shellfish poison cysts. However, although algal cysts are also called dormant cells, experiments have shown that unlike cysts or spores of bacteria or fungi, their outer walls are easily permeable to water-soluble substances, and the above-mentioned fungicides can be used to exterminate cysts of harmful algae. It has also been proven through experiments that it is effective.

[0015] Furthermore, in a ship's ballast water sterilization system, a disinfectant mixing device mixes disinfectant into the ballast water being injected by a pump, and a cascading device mixes air into the ballast water being drained by a pump. The residual chlorine in the ballast water can be rendered harmless by the action of oxygen in the air.

[0016]

[Example] An example will be explained below.

First, a ballast water sterilizer for ships as an embodiment of the present invention will be explained with reference to FIG. 2. FIG. 2 is a schematic side view.

In this embodiment, a ballast tank 11 is formed at the bottom of the ship 10.
A pump 3 is equipped for injecting and discharging seawater into 1.

A suction pipe 3a and a discharge pipe 3b are connected to the pump 3, and the tip of the suction pipe 3a opens into the ballast tank 11, and a valve 15 is interposed in the middle. The valve 1 is a suction pipe 13 that communicates with the suction port 14 that opens at the bottom 10a and has a valve 12 on the way.
5 and the suction port of the pump 3.

On the other hand, the discharge pipe 3b is constructed such that its tip opens outward from the hull, and a valve 16 is interposed in the middle thereof. Further, between the valve 16 and the discharge port of the pump 3, a water injection pipe 17 whose tip end opens into the ballast tank 11 is provided.
is connected, and a valve 18 is interposed in the middle of the water injection pipe 17. The reference numeral in the figure indicates a reinforcing member made of a perforated plate.

[0021] The above-mentioned configuration is almost the same as that of a conventional ship ballast tank filling/draining device.

Next, reference numeral 1 designates a disinfectant tank, to which a disinfectant take-out pipe 2 is connected, a valve 19 is interposed in the take-out pipe 2, and a distal end of the take-out pipe 2 is connected to the take-out pipe 2. A nozzle 2a is attached to the pump 3, and the nozzle 2a opens near the suction port of the pump 3 on the suction pipe 3a.

[0023] Also, reference numeral 24 indicates a compressor,
The discharge pipe 21 opens downstream of the valve 16 on the discharge pipe 3b. Reference numeral 22 indicates a motor for driving the compressor 19.

Furthermore, a mixing device 23 is installed in the water injection pipe 17.
is installed.

With the above configuration, water is poured into the ballast tank 11 by driving the pump 3 with the valves 15 and 16 closed and the valves 12 and 18 open. During this water injection, by opening the valve 19 by a predetermined amount, a predetermined amount of the disinfectant stored in the disinfectant tank 1 is mixed into the seawater (ballast water) sucked in from the suction port 14 through the nozzle 2a. Can be done.

Furthermore, by operating the mixing device 23, the disinfectant mixed into the ballast water in the water supply can be stirred to make the concentration of the disinfectant uniform within the ballast tank 11.

Drainage of ballast water from the ballast tank 11 opens valves 15 and 16 as well as valves 12, 18 and 19.
This is done by driving the pump 3 with the pump closed. At the time of this drainage, the compressor 24 is driven to blow compressed air into the discharge pipe 3b through the discharge pipe 21, thereby giving oxygen to the ballast water being discharged, that is, by performing a waterfall, residual chlorine is removed. Can be rendered harmless.

As described above, according to the sterilizer of this embodiment, a predetermined amount of sterilizer can be mixed into the ballast water by adjusting the valve 19, and the ballast water being discharged can be cascaded to can be rendered harmless.

Furthermore, by operating the mixing device, the concentration of the disinfectant in the ballast tank can be made uniform.

Next, an embodiment of a method for sterilizing ship ballast water will be described.

The present inventor conducted the following experiment in order to confirm the killing effect of alexandrium cysts (hereinafter referred to as "cysts") using sodium hypochlorite (sodium hypochlorite). Ta.

1. The protoplasm of the cyst is light green in color and the outer shell is bale-shaped, and when treated with normal seawater,
There was no apparent change in the cyst.

2. 10 ppm of sodium hypochlorite (available chlorine amount: 1 ppm) was added, and changes in the morphology of the cysts were observed for 30 minutes. The results are as follows. (1) There was no change in the outer shell. (No change in appearance) (
2) The light green color became slightly transparent, and the color of the protoplasm became slightly faded. When the cells were then returned to normal seawater, the color of the protoplasm returned to almost its original color.

3. 20 ppm of sodium hypochlorite (available chlorine amount: 2 ppm) was added, and changes in the morphology of the cysts were observed for 30 minutes. The results are as follows. (1) The color of the protoplasm turned dark within 30 minutes. (2) This cyst was returned to normal seawater, but one portion did not return to its original state.

4. Next, sodium hypochlorite 1000
ppm (available chlorine amount: 100 ppm) was added, and changes in the morphology of the cysts were observed for 30 minutes. The results are as follows. (1) The color of the inner protoplasm rapidly darkened within 10 minutes. (2) After 30 years, the outer shell contracted and changed into a gourd shape. (3) Even when these cysts were returned to normal seawater, none of them returned to their original state.

The results of experiments 1 to 4 above are shown in FIG.

It was also found through experiments that the chlorine content of the added sodium hypochlorite disappeared in approximately one week.

The above experiment revealed that chlorine-based disinfectants are effective in exterminating cysts of harmful algae. According to experiments conducted by the present inventors, it has been confirmed that calcium hypochlorite and hydrogen peroxide are also effective in exterminating cysts of harmful algae.

[0039]

Effects of the Invention As detailed above, according to the method and apparatus for sterilizing ship ballast water of the present invention, the following effects and advantages can be obtained. (1) The effects of the disinfectant killed the harmful algal cysts in the ballast water, and by the end of the approximately one-week voyage, chlorine and hydrogen peroxide remained in amounts that would have a negative impact on the environment. Therefore, even if ballast water is discharged at a port in the other country, it will not pollute the environment of the port. (2) Since ballast water can be discharged at the port of the partner country,
There will be no need to reballast in the open ocean during a voyage. (3) Since conventional ballast water injection and drainage equipment can be used, it is advantageous in terms of cost. (4) By blowing air into the ballast water being discharged, even if chlorine remains in the ballast water, the residual chlorine can be rendered harmless and there is no risk of contaminating the environment.

[Brief explanation of drawings]

FIG. 1 is an effect test result diagram when sodium hypochlorite is added as an example of the ship ballast water sterilization method of the present invention.

FIG. 2 is a schematic side view of a ballast water sterilization device for a ship as an embodiment of the present invention.

[Explanation of symbols]

1 Sterilizer tank 2 Disinfectant removal pipe 2a Nozzle 3 Pump 3a Suction piping 3b Discharge piping 10 Ship 11 Ballast tank 12, 15, 16, 18, 19 valve 13 Water suction pipe 14 Suction port 17 Water injection pipe 20 Reinforcement member 21 Discharge pipe 23 Mixing device 24 Compressor

Claims (2)

[Claims] [Claim 1] In a ship ballast water sterilization method,
A method for sterilizing ballast water for ships, characterized in that cysts of harmful algae are killed by adding a chlorine-based disinfectant or hydrogen peroxide to the ballast water. [Claim 2] In a ship's ballast water sterilizer,
The ship is equipped with a ballast tank, a pump for injecting and draining ballast water into the ballast tank, and suction piping and discharge piping connected to the pump, and a disinfectant is applied to the ballast water being injected into the ballast tank by the pump. A ballast water sterilization device for a ship, comprising: a sterilizer mixing device capable of mixing a sterilizing agent; and a cascading device capable of blowing air into the ballast water being drained by the pump.