JPH01163599A - Method of preventing oceanic life from pollution - Google Patents

Abstract

PURPOSE:To prevent oceanic life from pollution by supplying a bacteriophage solution carrying bacteriophage subjecting stained microorganisms to bacteriolysis, to a device utilizing seawater. CONSTITUTION:In the case of cleaning a condenser, a cleaning member 11 is supplied to a cleaning member recovery apparatus 9 to contain water. Thereafter, the water-containing cleaning member 11 is sent into a phage culture tank 10. Suitable quantities of aseptic air 13 and a nutrition source 14 are supplied thereto and bacteriophage which subjects polluted microorganisms to bacteriolysis is supplied thereto as a seed culture phage 12 to carry out the culture of the phage and carrying of the phage on the cleaning member 11. At the time of cleaning the condenser, the phage carrying-cleaning member 11 is supplied to the cleaning pipe group of the condenser 5. When the cleaning member 11 makes contact or slide with the inner surface of a water chamber and a cooling pipe, the carried phage associates with staining adhered bacteria adhering to pipe wall surfaces and subjects the same to bacteriolysis to display cleaning effects, and the phage oozing out from the cleaning member 11 associates the staining adhered bacteria existing in seawater moving in the tube and subjects the same to bacteriolysis.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to seawater heat exchange equipment, which is widely used in waterfront power plants and waterfront industrial complexes, heat recovery and cooling equipment from waterfront plant equipment, This law relates to the Marine Biological Fouling Prevention Law for seawater cooling systems in ships, seawater desalination systems, vaporization systems at LNG terminals, etc.

[Prior Art] The conventional art will be explained below with reference to FIG. 1 (this figure will also be used to explain one embodiment of the present invention) using a condensate cooling system in a coastal thermal power plant as an example. .

Intake water (seawater) 1 obtained from the intake sea area is separated from the scree (referred to as scree) and then discharged to the discharge sea area as discharge water 7.

During the operation of such system equipment that utilizes seawater, shellfish such as oysters, oysters, and mussels, insects such as snails, other algae, and microorganisms such as bacteria are sprayed onto the walls of waterways, inner walls of pipes, and heat exchanger ice chambers. They like to breed.

The damage caused by the growth of these fouling organisms not only fouls the entire heat transfer surface and lowers the heat transfer coefficient, but also increases the water head loss of the system and causes blockage of equipment and branch pipes. If the condenser or heat transfer tube is blocked, the protective coating of the heat transfer tube is destroyed, promoting erosion and causing local corrosion. For power plants located on the coast, measures against marine life are the most pressing issue, and it is no exaggeration to say that most of the problems and maintenance costs associated with reed seawater cooling systems are caused by marine fouling organisms.

In order to solve all of the above problems, various measures have been taken in the past from the viewpoint of both suppressing the growth of attached organisms and cleaning and removing them. As typified by chlorine injection, it has a large effect on the organisms targeted for abatement, and its use is restricted from the standpoint of environmental conservation.

In addition, physical treatment methods such as hot water treatment and osmotic shock methods, and mechanical removal methods such as bran cleaning and sponge ball cleaning are also being investigated. However, it is known that each of these can be effective if appropriate countermeasures are taken during the larval stage of the sessile organisms. It can be said that it is impractical to regulate all such processing conditions because it requires a large amount of energy.

Therefore, at present, the use of chlorine injection is limited to ponds with strictly controlled residual chlorine concentration, mechanical cleaning with brushes is applied to remove shells from sea channel walls, and sponge ball cleaning is used to remove slime from heat exchangers. However, none of them have been adopted due to their lack of practicality due to their lack of economic efficiency and certainty of antifouling effects. Based on the above, we are looking forward to the emergence of an antifouling technology that is environmentally friendly, practical, and can replace chlorine injection.
This method is based on the unique concept of controlling microorganisms using microorganisms, which prevents slime staining and, in turn, prevents fouling of attached organisms by intervening microorganisms (hereinafter simply referred to as phages).

To give an overview of this antifouling technology using bacteriophage, biological fouling of surfaces that come into contact with seawater is thought to proceed through the following mechanism.

(1) Organic matter in seawater adheres to solid surfaces that come into contact with seawater.

(2) Bacteria attach reversibly (and irreversibly) to the organic film.

(3) The attached bacteria secrete sticky extracellular polymeric substances and form a slime-like microbial film.

(4) This film attracts larvae and spores of attached organisms,
They grow into macroorganisms such as shellfish and seaweeds.

The essence of this method is to examine the mechanism of this biological fouling generation and utilize bacteriophages, which can be called natural enemies in (2).

Cleaning of the condenser shown in FIG. 1 by bacteriophage is carried out as follows. Normally, one pipe group of the condenser 5 composed of a plurality of pipe groups is cleaned with seawater flowing through it (-1: carried out. The cleaning body 11 is transferred to the cleaning body recovery device 9 in the figure). After the washed body 11 is immersed in water in the recovery vessel 9, the washed body collection valve 17 is opened and the washed body is sent to the phage culture tank 10 together with seawater.

Phage culture tank 10 is supplied with sterile air 16 and appropriate amounts of nutrient source 14 . A bacteriophage which has been searched in advance and is capable of lysing all of the fouling microorganisms present in the intake water (seawater) 1 is added to the phage culture tank 10 as a seed phage 12.

In the phage culture tank 10 containing the washed body 11, 77-
The phages are cultured and the phages are carried on the washed body 11.

When cleaning the condenser with the thus obtained phage-carrying cleaning body 11, the cleaning body supply valve 18 is opened, and the cleaning body recovery vessel 1
6 and then supplied to the cleaning pipe group of condenser/water unit 5.

When the phage-carrying cleaning body 11 supplied to the water type 5 contacts or slides on the inner surface of the water chamber and the cooling pipe, the phage-carrying phage interacts with the fouling adhering bacteria adhering to the pipe wall surface. It lyses bacteria and has a cleaning effect. -! Cleaning body 11
The phage exuded from the tube also associates with fouling adhering bacteria present in the seawater flowing through the tube and lyses them. The cleaning body 11 that has cleaned the condenser 5 is separated from the effluent water 7 in the cleaning body collector 6, and then the cleaning body collection valve 15 and the circulating water pump 8'f:
After that, it is sent to the cleaning body recovery device 9.

The above circulation operation is continued for a predetermined period of time to complete the cleaning f-1.

When the cleaning is completed, the cleaning body collection valve 15 and the circulation valve 16 are closed and the circulating water pump 8 is stopped. This cleaning operation is normally performed intermittently on a regular basis to prevent wear of the heat transfer tubes.

[Problems to be Solved by the Invention] Bacteriophages that lyse attached bacteria are also called bacterial viruses, and are composed only of nucleic acids and proteins, and do not have the ability to self-replicate. In addition, they are extremely small and special microorganisms that do not self-migrate. This phage associates with and attaches to a particular bacterium called a host, and the phage's genes are injected into the cells of the host bacterium. The injected phage genes reproduce the phage genes and constituent proteins within the host cell to form new phages, and then the host cell is lysed and a large number of newly formed phages are released outside the cell. The shape and properties of the released phage are exactly the same as the original 7-age, and it again associates with other host bacteria, lyses, and repeats multiplication.

As described above, the bacteriolytic action of adherent bacteria that causes biological stains is first achieved through association and contact between host bacteria and phage having bacteriolytic activity. For this reason, since the efficiency of association contact is proportional to the respective concentrations of bacteria and phages, it is desirable to increase the injection concentration of phages as much as possible.

[Purpose of the invention]

In response to the above-mentioned needs, the present invention aims to increase the concentration of phage by using an immobilization carrier with a wide area for carrying phage, and the present invention has developed a device that uses seawater to obtain highly loaded phages using a porous elastic material. A marine-based cleaning method characterized by supplying a chitosan porous elastic body carrying a bacteriophage that lyses staining microorganisms or a bacteriophage solution containing the elastic body to an apparatus that utilizes all seawater. This is the City Law on Prevention of Biological Fouling.

That is, in the present invention, a porous chitosan material is selected as an immobilization carrier that supports a large amount of phages. Chitosan is a polyglucosamine obtained by deacetylating chitin, and since it is easily soluble in organic acids and mineral acids, it has high reactivity and can be molded into various forms.

In addition, since chitosan has no highly reactive amine groups in its molecule, it adsorbs and supports various proteins, including enzymes and phages. Therefore, it is added to equipment to clean it and prevent fouling of attached organisms. Ah, 6
It is used to include those coated with a porous material and those made of porous chitosan itself molded into a spherical shape.

Furthermore, the degree of deacetylation and average molecular weight of chitosan used in the present invention are not particularly limited, but the degree of deacetylation is 70 to 90, and the average molecular weight is about 10,000 to 600,000, which is a relatively low molecular weight. It is preferable to use Note that the higher the degree of deacetylation, the higher the protein immobilization ability.

[Effect]

In the present invention, a large amount of phages supported and added to the chitosan porous elastic material lyses all the fouling bacteria attached to the solid surface of the structure or the fouling microorganisms scraped off the solid surface by the same elastic material. ,Sterilize. moreover,
It also efficiently contacts and lyses polluting microorganisms contained in newly inflowing seawater, thereby sterilizing them. In addition, it is known that the relationship between phage and host bacteria is generally one-to-one. Moreover, since it uses naturally occurring microorganisms called bacteriophages, it does not cause secondary pollution due to bioaccumulation.

As described above, if the cleaning body composed of chitosan porous bullets and heel bodies is loaded with a variety of phages and the solid surface of seawater contact insects in seawater system equipment is cleaned, fouling microorganisms and phages can be efficiently removed. It can prevent biological contamination from bacteriolysis and sterilization.

〔Example〕

An embodiment of the present invention will be explained with reference to the flow shown in FIG. Normally, cleaning is performed in the same manner as in the past, with seawater flowing through one tube group 1t of the condenser 5, which is composed of a plurality of tube groups.

The cleaning body f-j that supports phages has an inner layer made of an open-celled elastic material (e.g. natural rubber foamed elastic material) to maintain elasticity, and a surface layer made of chitosan porous material with a thickness of less than a few inches. 71 was attached so as to cover the chitosan, and it was easily dissolved in a phage culture tank 1o with a total of 36% acetic acid solution to obtain an acidic chitosan solution.
Next, a resistant solution consisting of 7% caustic soda, 60% ethanol, and 66% water is sprayed dropwise through a nozzle to solidify and regenerate into granules.

After that, thoroughly wash with neutral water to reduce the particle size to 50-10.
Chitosan porous granules with 0 mesh are obtained. The chitosan porous elastic body (cleaning material) with chitosan porous material attached to the surface layer is coated on the surface of the elastic body constituting the entire inner layer of the cleaning body with the above-mentioned chitosan granules as a gold base and an adhesive such as Epoquin resin. body) is formed.

A 0.5 cm sample of the chitosan porous material constituting the surface layer of this chitosan porous elastic material was taken, and a phage preservation solution 1 was taken.
After water replacement in 07, sterilization was performed at 121°C for 20 minutes in an autoclave, and after removing the phage storage solution, the adherent bacteria (
Incubate for 4 hours at 25°C in a phage lysate containing 4/- 117 x 10 I of bacteriophages whose hosts are Durham-negative bacilli of the Pseudomonas layer.
: 1t, h The number of chemotactic bacteriophages is the wavelength of the phage lysate (undiluted solution) and the fixed f-treated residual solution: 256
3,93X1012 determined from the difference in absorbance in nm
/- chitosan porous body was measured.

Next, adherent bacteria (Durum-negative bacteria of the genus Pseudomonas) were grown on an agar plate medium at pH 7.8 containing 05% peptone, 0.1% yeast extract, 0.1 part glucose, and 1.5 part agar. The phage immobilized on the chitosan porous material was implanted on this material, and as a result of static culture at 25°C for 24 hours, milky white [Q'
On the surface of the medium exhibiting Th, clear lytic plaques were observed around the implantation site of the phage carrier immobilized on the chitosan porous material. This confirmed that the bacteria attached to the host were lysed and purified by the chitosan porous elastic material on which the phage was immobilized.

Due to its physical properties, chitosan can be dropped into a basic coagulation bath to form granules, extruded from a nozzle to form fibers, and so on.
Specific surface area (manufactured by Takafusa Seisakusho, specific surface area measuring machine J)
(measured by the BET method) is significantly large, and is prepared so that it is 60 m2/g or more. The measured specific surface area of conventional cleaning bodies is 0.1 m2/? The following shows that the amount of immobilized phages in the cleaning body whose surface is coated with chitosan porous material is significantly increased compared to the conventional cleaning body.

Further, the cleaning body itself may be composed of a porous chitosan material, and the specific surface area can be adjusted to an appropriate value by setting conditions during solidification and regeneration.

This chitosan porous elastic body (hereinafter referred to as chitosan cleaning body 11a)
) ff: The procedure for cleaning the condenser 5 using
To explain according to the flow shown in the figure, the chitosan cleaning body 11a
i After being soaked in water in the washed body recovery device 9, the washed body recovery valve 17 is opened and sent to the phage culture tank 10. The phage culture tank 10 is supplied with sterile air 16 and a nutrient source 14 . As a nutrient source 14, marine heterotrophic bacteria are relatively high;
And organic +V! The nutrient source 14 does not necessarily need to be added if nutrients for microorganisms such as IJ are sufficient or if there is sufficient interval between cleaning operations of the equipment.

After culturing the adherent bacteria by holding in this manner for 4 to 24 hours, preferably 6 to 8 hours, seed phage 12 is added. Seed phage 12 is extracted from previously explored water (seawater)
A phage that lyses staining microorganisms present in 1 is used.

Thereafter, the culture solution containing the chitosan-washed body 11a is stirred for 60 minutes or more, preferably for 2 to 5 hours, while supplying sterile air 13, to make the chitosan-washed body 11a support the phage. The amount of phage immobilized and supported on the chitosan-washed body 11a varies depending on the chemical modification treatment such as cross-linking reaction carried out on the chitosan and its degree; Most of it was washed out with water and no phage immobilization function was observed.

Cleaned chitosan body 1 obtained in phage culture tank 10
1 a'i When cleaning the condenser, the cleaning body supply valve 18 is opened and the cleaning body is supplied to the cleaning pipe group of the condenser 5 via the cleaning body circulation valve 16. The cleaning operation of the condenser 5 is performed and completed in the same manner as in the prior art.

In addition, when comparing the chances of association and contact between adherent bacteria and bacteriophages with lytic activity with the phage liquid injection method, it was found that the phage liquid injection method was effective against normal seawater containing 108 bacteria/l. The addition is carried out so that the concentration of phages is 1010 to 106, preferably 109 to 107. In contrast, the immobilized chitosan product had a phage concentration of 3.93 x 1012 phages/d-chitosan porous material as described above, and the phage concentration was 107 using the phage liquid injection method.
Since the phages are present at twice the volume ratio concentration, the chance of association contact with fouling bacteria is greatly increased. Furthermore, the diameter of the cooling pipe near the surface where fouled organisms adhere is generally 3 mm.
It is taken from 254 pharynx. Here, it is sufficient to have a high concentration of phages in a fluid layer 1 mm from the wall surface, which is said to be the limit of the influence of the wall surface flow velocity of the fluid in the tube, so the volume ratio will be 13 to 17 times the normal flow rate in the tube. , the amount of phages required can be reduced.

In this respect as well, the chitosan cleaning body 11ai is effective because the high MU-carrying surface of the phage comes into contact with the predicted adhesion surface of the attached bacteria. Since it is used repeatedly, it contributes to increasing the chances of meeting and contacting as intended by the present invention.

The chitosan washed body 11a carrying phage is supplied to the condenser 5 together with the culture solution in the phage culture tank 10, so that the chitosan washed body 11a scratches the surface of the solid to be cleaned and the phages are transferred to the condenser 5. Because of the association, the cleaning and sterilizing effect increases synergistically.

In the technique, phages are first established when they associate with staining adherent bacteria, but as shown in the present invention, chitosan porous elastic material with the highest concentration of phage supported on the solid surface on which adherent bacteria are attached. Since the surface layer is in contact with each other, it is possible to achieve efficient association between phages and fouling-prone attached bacteria, which contributes to the development and practical application of marine fouling prevention technology that utilizes phages, which is industrially beneficial. It is.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining aspects of the method for preventing marine biological fouling according to the present invention and the prior art. In the figure, 1 is water intake, 2 is screen equipment, 3 is water intake pump, 4 is safety filter, 5 is condenser, 6 is cleaning body collector, 7 is discharge water, 8 is circulating water pump, 9 is cleaning Body recovery device, 10 is a phage culture tank, 11id washing body, 11a
id chitosan cleaning body, 12 is a seed phage, 16 is sterile air, 14 is a nutrient source, 15 is a cleaning body collection valve, and 16 is a circulation well.

Claims (1)

[Claims] In a method for cleaning equipment that uses seawater with a porous elastic body, a chitosan porous elastic body carrying a bacteriophage that lyses fouling microorganisms or a bacteriophage solution containing the elastic body is supplied to the equipment that uses seawater. The Marine Biological Fouling Prevention Act is characterized by: