JPS62298497A - Method for preventing spoiling of marine organisms by intermittent injection of phage - Google Patents

Abstract

PURPOSE:To sterilize the spoiling microorganisms in a closed loop by isolating a sea water system in a plant from the sea water intake area and release area of said plant and injecting bacteriophage intermittently into the sea water retained in the closed loop obtd. in such a manner during the stop of the sea water flow. CONSTITUTION:An intake shut off gate 8 and a release water shut off gate 9 are closed to provide the closed loop of the sea water system in the plant during the stoppage of the sea water flow in the plant utilizing the sea water. The bacteriophage 7 is intermittently injected into the sea water retained in the closed loop to sterilize the spoiling microorganisms existing in the closed loop. As a result, the spoiling of the marine organisms is effectively prevented without giving any ill effects at all to the other marine organisms.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to the cooling of equipment that uses seawater for cooling, such as coastal power plants, and other equipment that uses seawater for cooling. Recovery cooling equipment, LNG vaporization equipment at LNG terminals,
This invention relates to a method for preventing marine biofouling in a cooling device for a drive device in a ship.

[Conventional technology]

The conventional technology will be explained below with reference to FIG. 3, taking a thermal power plant as an example.

Intake water (seawater) 1 obtained from the intake area is passed through screen equipment 2
After removing solid substances such as seaweed and shellfish, the intake pump 3 pumps the condenser aa.

4b, and after heat exchange, the water is discharged as effluent 5. At the sea power plant, in order to respond to daily and weekly fluctuations in power demand, the power generation load is reduced, Dis (Daily 5tar
t and 5toop) or WSS (Weekl
yStart and 5top).

Accordingly, the supply of seawater to some condensers has been stopped, or the entire seawater system, such as DSS or WSS, is stopped at night or on weekends.

In the operation of such a seawater system, Fujibo, oysters,
Large organisms such as shellfish such as mussels, insects such as bulrushes, and microorganisms such as bacteria are present on the water intake side walls, pipe inner walls,
Preferably breeds in the water chamber of a heat exchanger. The adhesion process of these fouling organisms is: ■ Attachment of bacteria to the surface of the structure; ■ Increase in the biofouling film due to the proliferation of attached bacteria and promotion of attachment of fine particles (microorganisms and inorganic substances) due to the production of extracellular mucilage; ■Formation of complex biofouling films due to the growth of yeast and mold, and ■Various blanking.

The phenomenon caused by the adherent growth of the above-mentioned fouling organisms not only causes an increase in head loss in the seawater system, but also causes blockage of equipment and branch pipes,
It also causes blockage of the condenser and condenser tubules, and destruction of the protective coating inside the tubules, promoting erosion and local corrosion.

Conventionally, the following methods have been known as means for solving such problems.

(1) Antifouling agents containing compounds such as chlorine, ozone, bromine, bromine chloride, hydrogen peroxide, permanganates, arsenates, arsenites, cyanide compounds, metal salts, organometallic compounds, and phenols. A method of killing attached organisms by mixing directly into the intake water and applying it to the surface of the structure.

12) Methods for preventing biological fouling without using an antifouling agent include hot water treatment, osmotic shock method, ultraviolet irradiation method, ultrasonic vibration method, sponge pole or plastic method using the antifouling agent described in (1) above. Antifouling agents are expensive and are also toxic to marine organisms that are not involved in biofouling, so their use is restricted from the standpoint of environmental conservation. In addition, some antifouling agents can accumulate in marine organisms through regular use, potentially causing secondary pollution.

In method (2) above, the mechanical cleaning method using a brush removes shellfish from water intake side walls, the inner walls of large-diameter pipes, and the inner walls of heat transfer tubes in heat exchangers, while the mechanical cleaning method using a sponge pole removes shellfish using heat. This method is only used to remove slime from exchanger ice chambers and thin tubes; other methods are impractical due to cost and antifouling effects. Furthermore, if the cleaning is carried out excessively, the surface of the structure may be damaged and corrosion or biological fouling may progress, but if the number of cleanings is too small, attached microorganisms cannot be sufficiently removed.

Each of the above methods also solves the problems of environmental conservation as described above. The present invention solves the above problems by: Either install a circulation line inside the condenser where the seawater supply has been stopped and inject bacteriophage intermittently, or +2) Use DSS or WSS operation to transform the entire seawater system within the power plant into a water intake area. The basic invention related to the earlier application (
This was done in the process of studying the practical application of Japanese Patent Laid-Open Publication No. 159596/1983).

That is, the present invention provides: (1) In a plant that uses seawater, a bacteriophage is intermittently injected into seawater held in a seawater passageway to sterilize fouling microorganisms present in the closed loop. A method for preventing marine biofouling by intermittent injection of phage; The present invention relates to a method for preventing fouling of marine organisms by intermittent injection of bacteriophage, which is characterized by intermittently injecting bacteriophage into seawater retained in a closed loop to sterilize fouling microorganisms present in the closed loop.

Furthermore, in the present invention, the bacteriophage specifically kills only the attached microorganisms involved in biofouling and acts as an antifouling agent, so it does not have an adverse effect on other microorganisms not involved in biofouling, animals and plants. In addition, the water is treated with antifouling treatment.
Since this is done in a closed loop that is separate from the discharge area, the possibility of the above effects can be further reduced.

Moreover, in the present invention, bacteriophage can achieve a large antifouling effect with an extremely small amount of injection.
Adhering microorganisms can be sufficiently removed without damaging the surface of the structure.

Furthermore, since the present invention uses bacteriophage, a natural product that already exists in nature, secondary pollution due to accumulation does not occur.

〔Example〕

Next, specific embodiments of the present invention and their specific effects will be described.

Example FIG. 1 is a flowchart showing an example of an embodiment of the present invention.

Water intake (seawater) 1. Screen equipment 2. Water intake pump 3. Condenser 4. The discharged water 5 is the same as in FIG.

During normal operation, water intake (
The seawater) 1 is supplied to the condenser 4 via the water intake cutoff gate 8, the screen equipment 2, and the water intake pump 3, and is discharged through the discharge water cutoff gate 9. During this time, the discharge water branch valve 10 and the circulating water valve 11 are closed.

In DSS or WSS operation, when power generation is stopped, the water intake cutoff gate 8 and the discharged water cutoff gate 9 are closed, the discharged water branch valve 10 and the circulating water valve 11 are opened, and the withdrawal valve 13 is closed.

In this state, by operating the water intake pump 5, the seawater held in the system is circulated within the closed loop of the screen equipment 2, water intake pump 3, condenser 4, discharge water branch valve 10, and circulating water valve 11. be done.

Next, a bacteriophage (or "
phage (also referred to as "phage") is injected into the loop as a seed phage 7.

The amount of phages to be injected is 10! for a bacteria concentration of 108 cells/l like in normal seawater. It is added at a concentration of 0 to 106 pieces/l, preferably 109 to 107 pieces/l. The circulation time in the loop can be carried out during the downtime of DSS'i or WSS operation, but normally 30 minutes or more is sufficient.

After the fouling microorganisms are lysed by the circulation in the loop, the withdrawal valve 13 is opened and part or all of the water retained in the loop is discharged as the phage-containing liquid 12 to the outside of the system.

With the restart of power generation, the discharge water branch valve 10 and the circulating water valve 1
1, close the intake water cutoff gate 8 and the discharge water cutoff gate 9.
Open it and let water intake (seawater) 1 flow through it again.

FIG. 2 is a flow sheet showing another embodiment of the present invention.

Water intake 1, screen equipment 2, water intake pump 3, condenser 4,
The discharged water 5 is the same as in FIG.

During normal operation, the intake water (
Seawater) 1 passes through the screen equipment 2, water intake pump 3, water intake cutoff valves 8a, 8b, condensers aa, ab, and then flows to the discharge water cutoff valve 9.
It is discharged as discharge water 5 from a and 9b. Meanwhile, discharge water branch valves 10a, 10b and circulating water valves 115L, 1 l
b is closed.

When the power generation load is reduced, the water intake cutoff valve 8a and the discharge water cutoff valve 9a are closed, and the flow of intake water (seawater) 1 to the condenser 4a is stopped.

On the other hand, the intake water continues to flow into the condenser 4b.

In this state, by opening the discharge water branch valve 10a and the circulating water valve 11a and operating the circulation pump 6,
Seawater held within a closed loop system of the condenser 4a, the discharge water cutoff valve 10a, the circulation pump 6, and the circulation water valve 11a is circulated.

Next, a phage that lyses the staining microorganisms present in the loop, which has been searched in advance, is injected into the loop as a seed phage 7. The amount of phage injected and the circulation time within the loop are the same as in the embodiment shown in FIG. 1 above.

After the fouling microorganisms are lysed by the circulation in the loop, the withdrawal valve 13 is opened and part or all of the water retained in the loop is discharged as the phage-containing liquid 12 to the outside of the system.

As the power generation load increases, the discharge water branch valve 10a and the circulating water 11a are closed, the water intake cutoff valve 8a and the discharge water cutoff valve 9a are opened, and intake water (seawater) is allowed to flow again.

In addition, when the power generation load decreases, water (seawater) is taken into the condenser 4b.
10 Even when the water flow is stopped, the method is exactly the same as the above method.

2. Effects (1) As already mentioned, fouling microorganisms first adhere to and proliferate on the surface of structures that come into contact with seawater.

The type varies depending on the water intake area and season.

(2) Bacteriophage (or simply “phage”)
Also called bacterial viruses, they are composed only of nucleic acids and proteins and do not have the ability to self-replicate. It has the effect of parasitizing certain bacteria and lysing them.

More specifically, the propagation of a phage involves the attachment of a phage to a bacterium, the injection of phage nucleic acid into the bacterium, the synthesis of phage nucleic acid and protein within the bacterium, the subsequent formation of phage particles, and the subsequent lysis of the bacterium. This occurs through the process of releasing tens to hundreds of new phages. In the present invention, a phage that has a bacteriolytic effect on a specific microorganism that causes biological fouling on the surface of a structure, which is present in the closed loop water, is searched and obtained in advance.
By intermittently injecting the seed phage into the loop, the microorganisms in the growth phase are selectively sterilized.

(3) Microorganisms that have already grown attached to structures are lysed, and fouling microorganisms floating in the still water are also lysed.

(4) New phages are released into the retained water in the circulation loop due to the lysis of the above-mentioned fouling microorganisms, and the phage concentration in the phage solution is much higher than that in the loop where the seed phage was initially injected. is obtained.

〔Effect of the invention〕

(1) The lytic effect (lysis time, amount released) of a phage is greatly influenced by its surrounding conditions. That is, the lytic effect of the phage is highest when the staining microorganism to be lysed is in the growth phase. At power plants operated by DSS or WSS,
Start and stop water flow to the condenser 24 hours a day or once a week. Even when the power generation load is reduced, load adjustment is performed approximately every 24 hours. usually,
Since staining microorganisms enter their most active growth phase and form colonies during this period, in the present invention, the strongest bacteriolytic effect can be obtained by injecting the phages during this period.

(2) The required lysis time and amount of phages released are also influenced by water temperature. That is, when the temperature is optimal for fouling microorganisms, the required lysis time is the shortest and the amount released is the largest. In the case of power plants, the intake water (seawater) temperature varies seasonally, so the present invention, which provides a closed loop, easily determines the optimum water temperature and circulation time for the lysis of a wide variety of fouling microorganisms that differ from season to season. Can be set.

(3) In the present invention where a closed loop is provided, a high concentration of phages can be obtained in the retained water and can be used again as seed phage to be injected into the next closed loop.

(41 The present invention uses phages that selectively act on specific fouling microorganisms, so it does not have any adverse effects on other marine organisms, and because the present invention proliferates phages in a closed loop, This possibility can be further reduced.

I5) In the present invention, it is possible to prevent the adhesion of fouling microorganisms to the structure surface at the earliest stage in the adhesion process of fouling organisms, and it is also possible to prevent the subsequent growth of large fouling organisms. .

(6) According to the present invention, the processing cost can be reduced by 115 to 1/9 compared to the conventional chlorine injection method.

[Brief explanation of the drawing]

1 and 2 are flowcharts showing an embodiment of the present invention. Third
The figure is a flow showing a conventional technique. 1...Water intake (seawater), 2...Screen equipment, 3.
...Water intake pump, a, 4a, ab...Condenser, 5...
・Effluent water, 6... Circulation pump, 7... Seed phage,
8, 8a, 8b...water intake cutoff gate or valve, 9.9a
, 9b... discharge water cutoff gate or valve, 10, 10a,
10b...Discharge water branch valve, 11゜11a, 11b...
・Circulating water valve, 12...phage-containing liquid, 13...withdrawal valve Fig. 1 Fig. 2

Claims (2)

[Claims] (1) In a plant that uses seawater, when seawater flow is stopped, the plant's internal seawater system is isolated from the plant's seawater intake area and discharge area, a closed loop is established for the plant's internal seawater system, and bacteriophage 1. A method for preventing fouling of marine organisms by intermittent injection of bacteriophage, comprising intermittently injecting bacteriophage to sterilize fouling microorganisms present in the closed loop. (2) In a device that uses seawater, when seawater flow is stopped, the device is isolated from the seawater intake area and discharge area of the device,
A method for preventing marine biofouling by intermittent injection of bacteriophage, which is characterized by providing a closed loop of seawater within the device, and intermittently injecting bacteriophage into the seawater held within the closed loop to sterilize fouling microorganisms present in the closed loop. How to prevent it.