JP2008055352A - Method and apparatus for maintaining fine bubble of ozone gas in water, and ballast water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for maintaining fine bubbles of ozone gas in water which can maintain the fine bubbles of ozone gas generated in water for a long time, and to provide a ballast water treatment method. <P>SOLUTION: The method for maintaining fine bubbles of ozone gas in water comprises a seawater introduction process for introducing seawater into an ozone dissolving tank, and an electrolytic water generating process for electrolyzing the seawater to generate strong acid electrolytic water on the anode side. The seawater introduction process comprises a fine bubble dissolving process for atomizing bubbles of ozone gas to generate fine bubbles and dissolving the fine bubbles in the seawater. The strong acid electrolytic water is added to a process before or after the fine bubble dissolving process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a maintenance method, maintenance device, and ballast water treatment method for ozone gas in water, and more specifically, a method, an apparatus, and a device capable of maintaining ozone gas refinement bubbles dissolved in seawater, for example, over a long period of time. The present invention relates to a method for treating ballast water.

A cargo ship that transports crude oil or the like is provided with a ballast tank in order to maintain the stability of the hull during navigation. Usually, when crude oil or the like is not loaded, the inside of the ballast tank is filled with ballast water, and when the crude oil or the like is loaded, the ballast water is discharged to adjust the buoyancy of the hull and stabilize the hull.

As described above, the ballast water is water necessary for the safe navigation of the ship, and the seawater of the port that performs cargo handling is usually used. The amount is said to exceed 10 billion tons per year worldwide.

By the way, aquatic organisms inhabiting the port where the water is taken are mixed in the ballast water, and these aquatic organisms are transported to foreign countries at the same time as the ship moves.

Therefore, the destruction of ecosystems, such as the replacement of existing species with species that did not originally live in the sea, has become serious.

Against this background, a convention for the regulation and management of ship ballast water and sediment (hereinafter referred to as the Convention) was adopted at the diplomatic meeting of the International Maritime Organization (IMO), and the ballast water treatment device was used. The obligation to carry out ballast water management is expected to be applied from 2009 onwards.

  In addition, the discharge standards for ballast water are defined by the Convention as shown in Table 1 below.

For this reason, when discharging ballast water, it is necessary to remove or kill up to about 1/100 of the number of organisms present in the open ocean.

In view of the above background, there is an urgent need to develop ballast water treatment technology that can solve the above-described problems.

Conventionally, Patent Document 1 discloses a technique for injecting ozone into seawater at the same time as or after injection of steam.
JP 2004-160437 A

  According to Patent Document 1, when steam is injected into the ballast water from the steam injection pipe, the injected steam expands in the ballast water, and bubbles are generated in the ballast water. The bubbles are rapidly cooled with the ballast water. It is described that ozone is refined and activated by the shock wave accompanying the collapse of the bubbles.

  However, the refined ozone bubbles are combined with the passage of time, and the bubble size increases, resulting in a disadvantage that the ozone activity is lost.

  Then, the subject of this invention is providing the maintenance method of the refinement | miniaturization bubble of the ozone gas in water which can maintain the refinement | miniaturization bubble of the ozone produced | generated in water for a long period of time, and the processing method of a ballast water.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
A seawater introduction step of introducing seawater into the ozone dissolution tank, and an electrolyzed water generation step of electrolyzing the seawater to produce strongly acidic electrolyzed water on the anode side,
In the seawater introduction step, there is a refined bubble dissolution step of refining ozone gas bubbles to generate refined bubbles and dissolving them in the seawater,
A method for maintaining the refined bubbles of ozone gas in water, wherein the strongly acidic electrolyzed water is added in a pre-process or a post-process of the refined-bubble dissolving process.

(Claim 2)
The diameter of the ozone gas refined bubbles is in the range of 5 to 500 µm, and the method for maintaining the refined bubbles of ozone gas in water according to claim 1.

(Claim 3)
In the path for introducing seawater into the ozone-dissolved water tank, there is a refined bubble dissolving means for refining ozone gas bubbles to generate refined bubbles and dissolving them in the seawater,
Having electrolyzed water generating means for introducing strong seawater electrolyzed water on the anode side by introducing seawater and electrolysis,
An apparatus for maintaining finely divided bubbles of ozone gas in water, wherein a pipe for supplying strongly acidic electrolyzed water generated by the electrolyzed water generating means is connected to the front or rear of the refined bubble dissolving means.

(Claim 4)
4. The apparatus for maintaining fine gas bubbles of ozone gas according to claim 3, wherein the fine gas bubble dissolving means comprises a venturi tube or a perforated plate.

(Claim 5)
In the ballast water treatment method for treating aquatic organisms in seawater by providing a filtration membrane or a slit plate in a path for introducing seawater into a ballast tank, the aquatic organism is treated with the filtration membrane or the slit plate, and then the claim 1 or 2. A method for treating ballast water, which comprises adding ozone-dissolved water produced by the method for maintaining the refined bubbles of ozone gas in water.

  ADVANTAGE OF THE INVENTION According to this invention, the maintenance method of the refinement | miniaturization bubble of the ozone gas in water which can maintain the refinement | miniaturization bubble of the ozone produced | generated in water for a long term, a maintenance apparatus, and the processing method of ballast water can be provided.

  Hereinafter, an example of the maintenance apparatus which implements the maintenance method of the refined | miniaturized bubble of ozone gas which concerns on this invention is demonstrated based on drawing.

  In FIG. 1, reference numeral 1 denotes a ballast tank, in which ballast water is introduced and stored. As the ballast water, for example, seawater or fresh water is used. In the present invention, an example in which seawater is mainly used will be described.

  Ballast water includes aquatic organisms such as zooplankton, phytoplankton, and bacteria, and seawater containing such aquatic organisms is pumped up by a pump (not shown), for example, removes microorganisms and the like up to a predetermined diameter by the membrane treatment apparatus 2, Thereafter, it is treated with ozone and sent to the ballast tank 1. This ballast water can be removed by the membrane treatment apparatus 2 by supplying a predetermined amount of ozone-dissolved water containing ozone that has been microbubbled to the ballast tank liquid delivery pipe 10 extending from the membrane treatment apparatus 2 to the ballast tank 1. The aquatic organisms that have not existed are killed or sterilized so that ballast water that does not contain aquatic organisms can be stored in the ballast tank 1.

  Reference numeral 3 denotes an ozone dissolution tank. At the inlet of the tank 3, a fine bubble dissolution means 4 is provided. The refined bubble dissolving means 4 uses a Venturi tube 40 in the illustrated example.

  Reference numeral 41 denotes an introduction pipe for introducing seawater by a seawater pump (not shown), and is connected to an inlet 42 of the venturi pipe 40.

  Reference numeral 5 denotes an ozone generator, and the ozone generated by the generator 5 is supplied to the front of the venturi tube 40 through the pipe 50.

  Due to the presence of the venturi tube 40, the ozone bubbles introduced into the seawater become fine bubbles (this bubbles are also referred to as microbubbles). The diameter of the fine bubbles is preferably in the range of 5 to 500 μm, more preferably in the range of 50 to 300 μm.

  The refined bubbles are present in a state of being dispersed and mixed in seawater, and this state is expressed as dissolution of the refined bubbles in the present invention.

  6 is electrolyzed water production | generation means. The electrolyzed water generating means 6 includes an anode 60 and a cathode 61, and the anode chamber 62 and the cathode chamber 63 are partitioned by a diaphragm 64.

  When seawater is introduced into the electrolyzed water generating means 6, electrolysis generates oxygen at the anode 60 and hydrogen at the cathode 61, as in the case of dilute saline electrolysis, and a dilute hydrochloric acid aqueous solution is formed near the anode 60. A dilute aqueous sodium hydroxide solution is generated in the vicinity of the cathode 61.

  The electrolytic reaction is shown below.

(+) Anodic reaction 2Cl ⁻ → 2Cl + 2e

The atomic chlorine Cl generated at the anode reacts with water to generate a trace amount of HCl.
2Cl + H ₂ O → 2HCl + 1 / 2O ₂

(−) Cathode reaction 2Na ⁺ + 2H ₂ O → 2NaOH + H ₂

  From the above electrolytic reaction, hydrochloric acid is generated on the anode 60 side, and strongly acidic electrolyzed water is obtained. This strongly acidic electrolyzed water is supplied to either the front or the rear of the refined bubble dissolving means 4 through the pipe 65. Accordingly, the pipe 65 is connected to either the front or the rear of the fine bubble dissolving means 4.

  In the present invention, by supplying strong acidic electrolyzed water, the refined bubbles are dissolved, and the seawater becomes acidic, which has an effect of preventing recombination of the refined bubbles.

  In the present invention, if electrolyzed water generating means 6 for electrolyzing seawater is provided, it is not necessary to separately prepare a strongly acidic liquid. In particular, a ship loaded with ballast water satisfies the demand because cost reduction is desired.

  Next, in the present invention, an operation capable of preventing recombination of fine bubbles will be described.

H ⁺ and OH ⁻ present at the gas-liquid interface in seawater are electrically balanced, but when seawater becomes acidic and pH decreases, the zeta potential at the gas-liquid interface decreases (the absolute value of minus decreases). ), It becomes presumed that by making OH ⁻ easier to polarize, bubbles repel each other and coalescence (recombination) of ozone gas fine bubbles is suppressed.

  Therefore, it becomes possible to maintain the fine bubbles (micro bubbles) for a long period of time, and when the ozone-dissolved water is added to the ballast tank or the preceding ballast water introduction pipe via the pipe 30, the bactericidal effect can be efficiently performed in a short time. Demonstrate.

  In the above description, the example of the film treatment has been described as the pretreatment of the ozone treatment, but a slit plate as shown in FIG. 2 can also be used.

  The slit plate 20 is formed with a plurality of linear slits 200 as shown in FIG. 3, and the opening width of the slits 200 is preferably in the range of 200 μm to 500 μm.

  Ballast water is pumped through the pipe 21 toward the slit plate 20, and the pumped ballast water attempts to pass through the slit 200 of the slit plate 20 in a turbulent state. A shearing phenomenon occurs when trying to pass through the slit 200, thereby destroying and killing aquatic organisms in the liquid.

  In addition, a slit is not limited to linear form, A circular arc shape (an example of curvilinear shape) may be sufficient. The number of slit plates may be one, but may be two or more.

  In the above embodiment, the venturi tube 40 is used as the microbubble-dissolving means 4, but the invention is not limited to this, and a porous plate or an orifice plate can be used, and various devices can be used as long as microbubbles can be generated. For example, a mixer such as an ejector or a static mixer can be used.

The injection rate of ozone with respect to the total ballast water is preferably 5 ppm (g ozone / m ³ ballast water) at the maximum in order to sterilize bacteria that cannot be separated or killed by membrane treatment or slit plates, and more preferably is 0. It is in the range of 5 to 5 ppm.

  In the present invention, sodium hydroxide generated on the cathode 61 side by electrolysis of seawater is neutralized to pH by injecting into the ballast tank liquid feeding pipe 10 in front of the ballast tank 1, for example. Is promoted to prevent ozone gas from being mixed into the ballast tank 1.

Flow chart showing an embodiment of the present invention Schematic sectional view showing a slit plate that can be used in the present invention Fig. 2 is a schematic sectional view taken along line III-III in Fig. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Ballast tank 10: Ballast tank liquid feeding piping 2: Membrane processing apparatus 20: Slit board 200: Slit 21: Piping 3: Ozone dissolution tank 30: Piping 4: Fine bubble dissolving means 40: Venturi pipe 41: Introducing pipe 42 : Inlet part 5: Ozone generator 50: Piping 6: Electrolyzed water generating means 60: Anode 61: Cathode 62: Anode chamber 63: Cathode chamber 64: Diaphragm 65: Piping

Claims (5)

A seawater introduction step of introducing seawater into the ozone dissolution tank, and an electrolyzed water generation step of electrolyzing the seawater to produce strongly acidic electrolyzed water on the anode side,
In the seawater introduction step, there is a refined bubble dissolution step of refining ozone gas bubbles to generate refined bubbles and dissolving them in the seawater,
A method for maintaining the refined bubbles of ozone gas in water, wherein the strongly acidic electrolyzed water is added in a pre-process or a post-process of the refined-bubble dissolving process.   The diameter of the ozone gas refined bubbles is in the range of 5 to 500 µm, and the method for maintaining the refined bubbles of ozone gas in water according to claim 1. In the path for introducing seawater into the ozone-dissolved water tank, there is a refined bubble dissolving means for refining ozone gas bubbles to generate refined bubbles and dissolving them in the seawater,
Having electrolyzed water generating means for introducing strong seawater electrolyzed water on the anode side by introducing seawater and electrolysis,
An apparatus for maintaining finely divided bubbles of ozone gas in water, wherein a pipe for supplying strongly acidic electrolyzed water generated by the electrolyzed water generating means is connected to the front or rear of the refined bubble dissolving means.   4. The apparatus for maintaining the micronized bubbles of ozone gas in water according to claim 3, wherein the micronized bubble dissolving means comprises a venturi tube or a perforated plate. In the ballast water treatment method for treating aquatic organisms in seawater by providing a filtration membrane or a slit plate in a path for introducing seawater into a ballast tank, the aquatic organism is treated with the filtration membrane or the slit plate, and then the claim 1 or 2. A method for treating ballast water, which comprises adding ozone-dissolved water produced by the method for maintaining the refined bubbles of ozone gas in water.