JP2007021287A - Ballast water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ballast water treatment method and apparatus which solve the problems of conventional technologies, show high adaptability, safety, and operability when being used in a ship, and kill harmful organisms contained in seawater taken in. <P>SOLUTION: In the ballast water treatment method where OHRs are installed in the intake pipe and drain pipe of ballast water, and in a water pipe to a ballast tank, cavitation is generated in the seawater containing the harmful organisms with the OHRs by using hydraulic pressure and water flow of a pump at drawing the seawater, and at least most of the harmful organisms are killed by exposing them under the cavitation condition and physically crushing them. The treated seawater can be discharged as ship ballast water free from biocontamination, which solves the treatment problems of harmful organisms-containing ballast water in a ship. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for treating ballast water of a ship that may contain pests.

Since the draft of a ship changes depending on the state of loading, it is necessary to ensure a certain draft for the stability of the ship, navigation safety, etc., and ballast tank seawater is taken in at the loading port corresponding to the loading state. As well as discharge. However, this ballast water contains harmful microorganisms such as bacteria and harmful plankton, and pests such as crustaceans and shellfish (hereinafter referred to as pests). As such, when such ballast water is discharged at a loading port, the port is contaminated.
Therefore, discharge of ballast water containing pests is regarded as a problem, and there is a possibility that it is prohibited by the Convention (Non-Patent Document 1).

Therefore, in the field of methods for treating harmful microorganisms, as a method for treating harmful microorganisms, chlorination methods, ozone treatment methods, electrochemical treatment methods, general methods such as a method of generating cavitation by a pipe mixer, and ballast A method for killing harmful plankton cysts by changing the seawater in the tank to hydrogen peroxide and maintaining the state for a long time (see Patent Document 1) Harmful in sediment in the ballast tank using warm water and steam The plankton is killed by heating, and the water in the ballast tank is replaced with clean seawater so that all seawater in the ballast tank becomes clean seawater (see Patent Document 2). Ballast water is applied to the fixed-bed electrode electrolytic layer. A method for killing microorganisms by supplying water (see Patent Document 3), and damaging microorganisms by impact of high-voltage pulse discharge in ballast water Various treatment methods for harmful microorganisms such as a method (see Patent Document 4) and a replacement method with nitrogen gas (see Patent 5) so that the oxygen concentration of ballast water in the ballast tank is 2% or less have been proposed. .

However, in the chlorination method, harmful substances such as trihalomethane are generated, and there is a risk of storing hypochlorous acid and chlorine gas in the ship. Chlorine dioxide treatment is effective for sterilization, but it is dangerous and increases chemical costs. In the ozone treatment method, a large amount of ozone is required to treat a large amount of seawater containing harmful microorganisms, which increases costs. Electrochemical treatment requires a fine filter to prevent electrode contamination and clogging, and its maintenance is not easy, and pressure loss due to the use of a fine filter causes a large amount of seawater containing harmful microorganisms. It is disadvantageous to do. In the conventional pipe mixer processing method, the occurrence of cavitation is insufficient and the sterilizing power is insufficient. In the ballast water replacement method, considering the stability and safety of the ship, both drainage and water intake operations are required at the same time, and the operation of switching pumps and systems becomes complicated. In addition, direct discharge of ballast water containing harmful microorganisms causes marine pollution. In the conventional technology, nitrogen replacement in the tank does not proceed quickly, there is danger to workers due to lack of oxygen in the tank, and sterilization becomes insufficient especially when the voyage is short. There are various problems.

Sea and Safety 2004 Autumn JP-A-5-910 JP-A-8-91288 Japanese Patent Laid-Open No. 2001-974 Japanese Patent Laid-Open No. 2002-192161 Japanese Patent Laid-Open No. 2002-234487

The present invention solves the problems in the prior art, and provides a ballast water treatment method and apparatus that has high adaptability, safety and operability when used on a ship, and which kills pests contained in intake seawater. This is the issue.

In order to solve the above-mentioned problems, the present invention is a method for treating ballast water, which utilizes OHR (non-patent document) by utilizing the water pressure and water flow of a pump when seawater containing pests is taken in. 2), cavitation is generated in the seawater, and the pests are exposed to cavitation to kill at least most of the pests, and the treated seawater is free from biological contamination. It can be discharged as ballast water for ships.

In order to solve the above-mentioned problems, the present invention provides a method for treating ballast water, wherein the water pressure and the water flow of the pump when seawater containing pests is taken in and the OHR is used. By physically crushing the pests, at least most of the pests are killed, and the seawater after the treatment can be discharged as ballast water of a ship free from biological contamination.

Hideto Uematsu Ultrasonic TECHNO 20001.5

According to the present invention, in the ballast water treatment method according to claims 1 and 3, cavitation is generated in the seawater using OHR using the water pressure and water flow of the pump when seawater containing pests is taken in. By exposing the pests to cavitation, at least most of the pests are killed and the treated seawater can be discharged as ballast water for ships without biological contamination. It can solve the problem of ballast water containing organisms.

Further, in the method for treating ballast water according to claims 2 and 4, by physically crushing the pest using OHR using the water pressure and water flow of the pump when seawater containing pest is taken in. Also, since at least most of the pests are killed and the treated seawater can be discharged as ballast water for ships without biological contamination, the problem of treating ballast water containing pests in ships can be solved.

Install one or more OHRs as necessary for the intake pipe, drain pipe, and water supply pipe just before the ballast tank. However, since the generated bubbles may adversely affect the piping (Non-Patent Document 3), it is considered that the water supply pipe immediately before the ballast tank is preferable for the arrangement position of the OHR. In particular, when a plurality of OHRs are installed in the water supply pipe immediately before the ballast tank, the effect of killing pests is improved by repeating the process of retreating the treated seawater between, for example, two ballast tanks. In addition, the direction of OHR is reversed with respect to the flow of seawater in the water injection process and drainage process of the ballast tank, so that the pest debris attached to OHR can be removed each time these series of processes are repeated.

NHK Science ZERO 2005.6.4 broadcast

This OHR causes sudden local pressure fluctuations in the water, and innumerable bubbles are generated as a whole, and cavitation in which the bubbles rapidly collapse is generated in the water. Pests are killed by the physical destruction caused by the shock wave generated during the collapse and the chemical oxidation caused by OH radicals generated by the decomposition of water molecules inside the cavitation.

As an example of sterilization by cavitation, even if it is a hard shell such as Cryptosporium or other oocyst shell that causes mass infection and is difficult to kill, sterilization can be achieved by destroying the protective shell by a strong shock wave. It has been reported that this is possible (Non-Patent Document 4).
From this, even if it is a pest, the cells in the body are physically destroyed by shock waves generated when bubbles are broken by ultrasound, and the chemical oxidation action by OH radicals generated by the decomposition of water molecules inside the cavitation In the case of crustaceans and shellfish, if the cells of vital organs such as respiratory organs are destroyed without destroying all the cells of the organism completely, Dies without being able to maintain. Particularly in the case of crustaceans and shellfish, the respiratory organs take in seawater and breathe, so the cells of the respiratory organs are easily affected by shock waves and OH radicals when the bubbles collapse.

Proceedings of the 10th Sonochemistry Study Group 2001 “27. Sterilization of yeast using ultrasound”

Claims (4)

In order to make it possible to discharge seawater containing pests as ship ballast water, this seawater is characterized by generating ultrasonic waves using OHR and generating cavitation bubbles to kill at least most of the pests. And ballast water treatment method. In order to make it possible to discharge seawater containing pests as ship ballast water, it is characterized in that at least a large part of the pests is killed by using OHR in this seawater and by physical crushing with a guide page and a current cutter. Ballast water treatment method. In order to enable seawater containing pests to be discharged as ship ballast water, the process of claim 1 is performed after the pests are physically pulverized by passing through a slit, and at least most of the pests are killed. A method for treating ballast water. In order to enable seawater containing pests to be discharged as ship ballast water, the process of claim 2 is performed after the pests are physically pulverized by passing the seawater through a slit, and at least most of the pests are removed. A method for treating ballast water, wherein the ballast water is killed.