Suppression and removal method of adhesion

Abstract

To provide a suppression and removal method of adhesion which can reliably suppress adhesion of adhering organisms to a structure or remove adhering organisms from a structure.SOLUTION: A suppression and removal method of adhesion suppresses adhesion of adhering organisms to a structure or removes adhering organisms adhering to a structure by irradiating the structure with light based on a light irradiation amount set for each adhering organism. The light irradiation amount is 160 Whm-2 or more, and an illuminance of the light irradiated based on the light irradiation amount is 20 Wm-2 or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for suppressing and removing adhesion. [Background technology]

[0002] Conventionally, there are known techniques for preventing the attachment of organisms such as barnacles to structures such as water quality meters immersed in water and seawater system facilities of thermal power plants, nuclear power plants, etc. For example, Patent Document 1 discloses a method for preventing the attachment of organisms to an underwater structure by irradiating the structure with light having a wavelength of 409 to 412 nm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-188570 A Summary of the Invention [Problem to be solved by the invention]

[0004] The method disclosed in Patent Document 1 suppresses and prevents new adhesion to the substrate, but there is room for improvement in terms of more reliably suppressing adhesion and reducing / removing numerous particles that have already adhered and grown on the substrate.

[0005] An object of the present invention is to provide a method for suppressing and removing adhesion of sessile organisms, which can reliably suppress adhesion of sessile organisms to a structure or remove sessile organisms from a structure. [Means for solving the problem]

[0006] (1) The present invention relates to a method for suppressing and removing adhesion of sessile organisms to a structure, by irradiating the structure with light based on an irradiation amount of light that is set for each sessile organism, thereby suppressing the adhesion of the sessile organisms to the structure or removing the sessile organisms that have attached to the structure.

[0007] (2) The amount of light irradiation is 160 Whm -2 The adhesion suppression and removal method described in (1) above.

[0008] (3) The amount of irradiation of the light is 480Whm -2 The adhesion suppression and removal method described in (1) above.

[0009] (4) The amount of light irradiated is 1920Whm -2 The adhesion suppression and removal method described in (1) above.

[0010] (5) The amount of irradiation of the light is 4800Whm -2 The adhesion suppression and removal method described in (1) above.

[0011] (6) The irradiance of the light irradiated based on the amount of light irradiation is 20 Wm -2 The adhesion suppression / removal method according to any one of (1) to (5) above.

[0012] (7) The irradiance of the light irradiated based on the amount of light irradiation is 24000 Wm -2 The adhesion suppression / removal method according to any one of (1) to (6), which is as described above.

[0013] (8) The adhesion suppression and removal method according to any one of (1) to (7), wherein the light irradiated based on the irradiation amount of light has a peak in a wavelength range of 400 to 490 nm.

[0014] (9) The adhesion suppression and removal method according to any one of (1) to (7), wherein the light irradiated based on the irradiation amount of light has a peak in a wavelength range of 400 to 430 nm. Effect of the Invention

[0015] According to the present invention, it is possible to reliably suppress adhesion of sessile organisms to a structure or remove sessile organisms from a structure. [Brief description of the drawings]

[0016] [Figure 1] This figure shows the change in state of the Balanus cypris larvae over time when continuously irradiated with LED light (peak wavelength: 405 nm) at an irradiance of 200 Wm-2. [Diagram 2] This figure shows the change over time in the condition of Balanus cypris larvae in the control group of the experiment from which the results shown in Figure 1 were obtained. [Diagram 3] FIG. 13 is a diagram showing the relationship between the rate of juvenile barnacles and irradiance when LED light (peak wavelength: 405 nm) was continuously irradiated for 96 hours at each irradiance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described. Note that the present invention is not limited to the following embodiment and can be appropriately modified.

[0018] <Method for preventing and removing adhesion> The adhesion suppression and removal method of this embodiment is a method for suppressing adhesion of adhesion organisms to a structure (hereinafter referred to as adhesion suppression) or removing adhesion organisms attached to a structure (hereinafter referred to as adhesion organism removal) by irradiating light onto the structure to which adhesion organisms are attached based on the light irradiation amount set for each adhesion organism.

[0019] Structures to which attached organisms attach include underwater structures (including structures that are permanently or temporarily wet with liquids such as water or sweat) or structures installed in the air, such as seawater system equipment in power generation facilities such as thermal power plants and nuclear power plants, and inspection windows used to inspect such equipment. In addition to the above, the structure may be a water quality meter, an underwater camera device, a water intake pipeline, a rotary screen, a bar screen, a drum screen, a mussel filter, a net screen, a water intake pump, a circulating water pump, a circulating water pipe, a heat exchanger, a condenser, a bearing cooling water cooler, a lubricating oil cooler, an LNG vaporizer, a generator, a discharge pipeline, a water wheel, an impeller, a valve, a rotating shaft, a water conveyance pipeline, a filter tank, a membrane, a dam, a ship, a hull in a shipyard, a ballast water tank, a ballast water inlet / outlet pipe, pumps, aquaculture equipment, aquatic research station, aquatic equipment, an aquarium, a water tank in a fish and shellfish breeding tank, piping, pumps, a water tank and a heat sink in a cooling tower, a scrubber water tank, etc. Also, for example, it may be a floor of a bathroom, a pool, a shower room, etc. It may also be, for example, a seat in a room or a car that is temporarily wet with sweat. Furthermore, it may be an outer wall / inner wall of a building, an outer surface / inner surface of a window, a desk, a chair, a hospital operating room, a patient's room, etc. The structure referred to here may also be a living organism. For example, the surfaces of oyster shells and soft parts, fish, protozoa parasitic on fish, plankton, algae, microorganisms, biological tissues and parts thereof, skin, teeth, cells and their secretions, etc., can be targets for attachment of sessile organisms. Air bubbles in water can also be structures for attachment of sessile organisms. In other words, the surfaces of air bubbles in water or liquid can be targets for the accumulation and attachment of a large number of attached microorganisms. The surfaces, inner surfaces, and food inside pack containers can also be targets for the accumulation and attachment of a large number of attached microorganisms. Foam, cream, jelly, gel, and mist can also be targets for the accumulation and attachment of attached microorganisms.

[0020] The term "sessile organisms" refers to organisms that have the property of attaching to the surface of underwater structures (including structures that are permanently or temporarily wet with liquids such as water or sweat) or structures in the air. Sessile organisms may be organisms that float in the sea during the early larval stage, and when they reach the sessile stage, attach to a suitable structure and metamorphose into adults. Examples of sessile organisms include mussels, barnacles, hydrozoans, sponges, epiphytic stages of jellyfish, tube-dwelling polychaetes, bryozoans, amphipods, and other animals, and microorganisms that belong to bacteria, viruses, fungi, blue-green algae, protozoa, and other groups. The term "sessile organisms" in this specification also includes biofilms, which are structures formed by microorganisms. Biofilms are usually membrane-like and contain extracellular polymeric substances (EPS), such as polysaccharides secreted by microorganisms. Biofilms may also contain microbial remains, excrement, feces, tubules, gene fragments, organic matter, inorganic particles, and the like. In addition, when a very thin biofilm is formed on the surfaces of seats or floors inside a vehicle, food, the surfaces, inner surfaces, or internal parts of packaging containers, individual living organisms, algae, tissues, cells, skin, teeth, etc., this biofilm can be considered to be an attached organism.

[0021] The light irradiation amount is the total amount of light irradiated to the structure to suppress adhesion or remove adhesion-related organisms. The light irradiation amount may be set, for example, according to the resistance of the adhesion-related organisms to light. In this case, the light irradiation amount may be set to the same value for a plurality of adhesion-related organisms having different resistances to light, or different values ​​may be set for each adhesion-related organism. When the light irradiation amount is set to the same value, an irradiation amount effective for suppressing adhesion or removing adhesion-related organisms having the highest resistance to light may be set. By irradiating the structure with light based on the light irradiation amount set for each adhesion-related organism, adhesion can be suppressed or adhesion-related organisms can be reliably removed.

[0022] The light irradiation amount set in this embodiment is 160 Whm -2 More preferably, 200Whm -2 More preferably, it is 400Whm or more. -2 More preferably, 480Whm or more -2More preferably, it is 1920Whm or more. -2 More preferably, it is 2400Whm or more. -2 More preferably, it is 4800Whm or more. -2 More preferably, 9600Whm or more. -2 More preferably, it is 200Whm or more. -2 By irradiating barnacles and other adhesion organisms, which have a relatively high resistance to light, with light of a dose of 400 Whm or more, it is possible to increase the number of individuals that are unable to swim (i.e., unable to attach to structures). -2 By irradiating barnacles and other attached organisms with light of this level or higher, it is possible to increase the number of individuals in what can be called a non-responsive state, such as a state where the thoracic limbs are protruding. -2 By setting the light irradiation amount at 1920Whm or more, it is possible to reduce the occurrence rate of colonies of microorganisms such as bacteria. In other words, it is possible to suppress the occurrence of biofilms, which are formed by microorganisms and act as a base to promote the attachment of large sessile organisms such as the larvae of barnacles and mussels to structures. Therefore, it is possible to suppress the attachment of sessile organisms that have a relatively high resistance to light to structures. -2 By setting the light irradiation level at 2400Whm or more, the number of barnacles adhering to the structure can be further reduced. -2 By setting the light irradiation level at 4800Whm or more, it is possible to suppress the attachment of barnacles to structures. -2 By increasing the light irradiation to 9600Whm, barnacles already attached to the structure can be removed. -2 By doing so, barnacles that have already attached to the structure can be removed more reliably.

[0023] The irradiance of the light irradiated based on the amount of light irradiation set in this embodiment is 20 Wm -2 More than 100Wm is preferable. -2 More preferably, 24000Wm -2 More preferably, the light irradiance is 20 Wm -2By irradiating the structure with the light irradiation amount set for each type of attached organism, it is possible to reliably suppress the attachment of attached organisms to the structure. -2 By doing so, adhesion inhibition or removal of attached organisms can be achieved in a shorter time. Therefore, even when light is intermittently irradiated while moving, adhesion inhibition or removal of attached organisms can be achieved in a relatively short time.

[0024] The light irradiated to the structure preferably has a peak in the wavelength range of 400 to 430 nm. Although ultraviolet light having a wavelength of 380 nm or less has an effect of suppressing adhesion of attached organisms, it has a problem of low transmittance in seawater. By setting the wavelength of the irradiated light within the above range, a preferable effect of suppressing adhesion and an effect of removing attached organisms can be obtained. The wavelength of the irradiated light may have a peak in a wavelength range other than the above range, as long as it does not impair the effects of the present invention. For example, the wavelength of the irradiated light may have a peak in the wavelength range of 430 to 490 nm.

[0025] In addition, in the adhesion inhibition or adhesion organism removal of this embodiment, the structure may be irradiated with light continuously (hereinafter referred to as continuous irradiation) or intermittently (hereinafter referred to as intermittent irradiation). EXAMPLES

[0026] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the description of the following examples.

[0027] [Test to confirm the effect of light irradiation on barnacles] The effectiveness of LED light in inhibiting the adhesion of living organisms was confirmed using cypris larvae of the striped barnacle (hereafter referred to as cypris larvae). Note that cypris larvae are nauplius larvae in the planktonic stage that undergo repeated molting and grow to the attachment stage where they can attach to structures. The juvenile barnacles described below are barnacles that metamorphose after cypris larvae attach to structures such as test containers.

[0028] 70 ml of test seawater (seawater filtered through a membrane with a pore size of 0.45 μm) and cypris larvae (number of individuals: 44 ± 12) were placed in a test container (a petri dish with a diameter of 6 cm and a height of 6 cm). As a test area, this test container was irradiated with LED light (peak wavelength: 405 nm) through a glass lid. UFL-501-08 UV-UT (manufactured by U-Technology Co., Ltd.) was used as the light source for the LED light. In order to prevent the temperature of the test seawater, etc. from increasing due to irradiation with the LED light, the outside of the bottom of the test container was immersed in tap water during the test. As a test area, a 20 Wm -2 , 50Wm -2 , 100Wm -2 , 150Wm -2 , and 200Wm -2 The test was conducted under five irradiance conditions. In the test, irradiation was performed continuously for 96 hours under each irradiance condition. During the test, the state of the cypris larvae in the test container was observed twice a day, and the appearance rate of the cypris larvae in each state was calculated. The test container was covered with aluminum foil and kept in almost constant darkness without irradiating the LED light as a control. The irradiance was measured and adjusted using an Ophir StarLite-PD300RM-8W irradiance meter through the lid of the test container. In all of the following tests, the irradiance was measured and adjusted using this irradiance meter.

[0029] (Test Results) <Irradiance 200Wm -2 Changes in the state of cyprid larvae under light irradiation Figure 1 shows the irradiance of 200 Wm -2 Figure 2 is a graph showing the change in the state of cypris larvae over time in the test area. -2 1 and 2 are graphs showing the change over time in the state of cypris larvae in the control group compared to the test group in Fig. 1. The horizontal axis of Fig. 1 and Fig. 2 shows the elapsed time from the start of the test, and the vertical axis shows the appearance rate of cypris larvae in each state.

[0030] As shown in Figure 2, in the control area, 2 hours after the start of the test, more than 80% of the cypris larvae were swimming, and after 6 hours, they gradually attached to the test container and began to metamorphose, and after 24 hours, more than 30% of the larvae had become juvenile barnacles, and after 96 hours, the emergence rate of juvenile barnacles was more than 90%. In other words, it was confirmed that more than 90% of the barnacles had attached to the test container.

[0031] On the other hand, as shown in Figure 1, the irradiance is 200 Wm -2 In the test area where irradiation was performed at 4800 Whm, 10% or more of the cypris larvae showed protruding thoracic limbs within 2 hours of the start of irradiation. -2 After 24 hours, more than 95% of the individuals were unresponsive with their shells closed or semi-closed, with their thoracic limbs protruding, or floating on the water surface. -2 The decrease starts above 4800Whm -2 is presumed to be almost completely suppressed.

[0032] <Ratio of young barnacles under light irradiation of each irradiance> Figure 3 is a graph showing the relationship between the juvenile barnacle rate and each irradiation condition when LED light was continuously irradiated for 96 hours at each irradiance. The horizontal axis of Figure 3 is the irradiance (Wm -2 ) and the vertical axis indicates the juvenile barnacle rate (%). The juvenile barnacle rate is the percentage of juvenile barnacles among the barnacles present in each test container. By evaluating the barnacles that have metamorphosed from cypris larvae to juvenile barnacles, the effect of suppressing barnacle attachment to structures can be evaluated.

[0033] As shown in Figure 3, in the control area, the rate of juvenile barnacles after 96 hours was approximately 85% or more. In other words, it was confirmed that 85% or more of the barnacles were attached to the bottom or side of the petri dish. In contrast, in the control area where the irradiance was 150 Wm -2 In the test area, the rate of juvenile barnacles after 96 hours was 0.6±1.4%, and it was confirmed that the very few juvenile barnacles that were observed were all dead. -2It was confirmed that the above measures completely inhibited the growth of cypris larvae and prevented them from attaching to structures. -2 The rate of juvenile barnacles in the test area was also reduced to about 70%. -2 It is presumed that by irradiating the structure with a dose of this amount, the amount of attached organisms on the structure can be reduced.

[0034] <Rate of Cypris larvae unable to swim 2 and 6 hours after the start of irradiation> Table 1 shows the incidence of cypris larvae unable to swim (hereinafter referred to as the "immobility rate") 2 and 6 hours after the start of irradiation with LED light of each irradiance and the irradiation dose (Whm -2 ) are shown. The non-swimming individuals referred to here are individuals with rolling over / thoracic limb movement (individuals that move their thoracic limbs while rolling over), individuals with protruding thoracic limbs, and individuals with closed or semi-closed shells (no reaction). The N numbers in the table refer to the number of tests (the same applies to the following tables).

[0035] [Table 1]

[0036] As shown in Table 1, the irradiation dose is 100Whm -2 Below this level, it was confirmed that no cypris larvae were unable to swim. On the other hand, at an irradiation dose of 200Whm -2 The rate of inability to swim was 5.8±10.1% at 900Whm -2 About 10% at 1200Wh -2 It was confirmed that the reduction was about 20% at an LED light irradiation of 200Whm -2 It is estimated that the physiological activity of barnacle larvae in the attachment stage begins to decrease at an irradiation dose of 200 Whm -2 It is assumed that barnacle attachment will begin to decrease as a result of the above.

[0037] <Distribution of barnacle attachment positions> Table 2 shows the irradiance of 20 Wm -2Table 3 shows the distribution of barnacles attached to the petri dishes in the test and control areas. -2 1 is a table showing the location distribution of barnacles attached to the petri dishes in the test plot and the control plot.

[0038] [Table 2]

[0039] [Table 3]

[0040] As shown in Tables 2 and 3, the irradiance is 20 Wm -2 and irradiance 50Wm -2 Under both conditions, in the control area, approximately 80% of the individuals attached to the bottom of the petri dish, and approximately 20% attached to the side of the dish. On the other hand, in the test area, it was confirmed that the difference in the attachment rate between the bottom and side of the petri dish was small. A multiple comparison test (Bonferroni method) was conducted on the side attachment rate in the control area and the side attachment rate in the test area, and it was confirmed that the side attachment rate of the petri dish in the test area was significantly higher (p<0.01). From this result, it is inferred that even when attaching, cypris larvae tend to avoid places where they are directly exposed to LED light (peak wavelength: 405 nm).

[0041] [Confirmation test of the effect of light irradiation on hydrozoans] The effect of light irradiation on the hydrozoan Hydra macrocarpa was examined using stem segments of Hydra macrocarpa, which were prepared by cutting off the roots and flowers of Hydra macrocarpa after isolating polyps from a colony of Hydra macrocarpa.

[0042] 70 ml of test seawater (seawater filtered through a membrane with a pore size of 0.45 μm) and Hydra stem pieces (number of individuals: 12 pieces) were placed in a test container (a petri dish with a diameter of 6 cm and a height of 6 cm). As a test area, this test container was continuously irradiated with LED light (peak wavelength: 405 nm) through a glass lid at each irradiance shown in Table 4 below. As a control area, the test container was covered with aluminum foil and kept in almost constant darkness without irradiating with LED light. The test was conducted for 96 hours, and the regeneration rate of Hydra stem pieces and the number of regenerated Hydra flowers were compared between the control area and each test area.

[0043] [Table 4]

[0044] (Test Results) Table 4 shows the irradiance of 100 Wm -2 and 200Wm -2 The regeneration rate of the stem segments of Hydra and the number of regenerated Hydra flowers after 96 hours in the test and control areas are shown in Table 4. -2 and 200Wm -2 When the two irradiances were continuously irradiated for 96 hours, the regeneration rate of the hydra stem segments and the number of regenerated hydra flowers were 0%. -2 It was confirmed that the colony formation of marine hydrozoans can be completely suppressed by irradiating the above doses.

[0045] [Comparative test of the effects of different irradiances on attached organisms] Using the cypris larvae of the Balanus arvensis, the effects of exposure to the same amount of radiation at different irradiances were compared.

[0046] 2 ml of test seawater (seawater filtered through a membrane with a pore size of 0.45 μm) and cypris larvae of the Balanus fasciatus (number of individuals: 16 ± 4) were placed in a test container (24-hole microplate). LED light (peak wavelength: 405 nm) was continuously irradiated under the irradiation conditions shown in Table 5 for the test area. UFL-501-08 UV-UT (manufactured by U-Technology Co., Ltd.) was used as the light source of the LED light. In order to prevent the temperature of the test seawater, etc. from increasing due to the irradiation of the LED light, the outside of the bottom of the test container was immersed in tap water during the test. The test container was covered with aluminum foil and kept in almost constant darkness without irradiation of the LED light for the control area. In the test, the rate of cypris larvae unable to swim was confirmed.

[0047] [Table 5]

[0048] (Test Results) Table 4 shows the irradiance of 600 Wm -2 The figures show the rate of swimming inability in the test areas with irradiation conditions of 6000Wm2, 8 hours irradiation time, and 0.8 hours irradiation time. -2 The immobilization rate was over 99% for both the irradiation conditions of irradiance 6000 and irradiation time 8 hours and the irradiation conditions of irradiance 6000 and irradiation time 0.8 hours. A significance test was conducted on the immobilization rate under these two irradiation conditions using multiple comparison test (Tukey HSD method) with statistical software R, and no significant difference was found between the two. Furthermore, the TOSTER equivalence test resulted in the two being evaluated as being statistically equivalent. These results confirmed that the adhesion inhibition and organism removal effects are roughly proportional to the product of irradiance and irradiation time, i.e., the amount of irradiation. Furthermore, at 4800 Whm -2 It is presumed that irradiation with a dose of this amount can prevent adhesion of sessile organisms to structures.

[0049] [Test to confirm adhesion removal effect] The effectiveness of irradiating light on barnacle removal from structures such as test containers was confirmed.

[0050] First, 8 ml of test seawater for attachment (seawater filtered through a 0.45 μm mesh membrane) and cypris larvae of the barnacle (number of individuals: about 30) were placed in a test container (6-hole microplate), and left to stand for 1 to 2 days to allow the cypris larvae to attach to the bottom of the test container. After that, the test seawater for attachment in the test container and the unattached cypris larvae were removed, and 8 ml of test seawater for rearing (seawater filtered through a 0.45 μm mesh cartridge filter) was placed in the test container. The juvenile barnacles attached to the test container were fed with floating diatoms (Chaetoceros calcitrans) as food during each rearing period to grow. The rearing period was 1 week, 2 weeks, 3 weeks, or 4 weeks. After each rearing period, the barnacle-attached individuals that had grown to be particularly large and actively crawling were selected as the target, and the diameter of the base plate was measured. LED light (peak wavelength: 405 nm or 460 nm) was then applied at an irradiance of 24,000 Wm -2 During the irradiation of the LED light, the condition of the barnacles attached to the specimens was observed at regular intervals. The LED light source used was UFL-501-08 UV-UT (manufactured by U-Technology Co., Ltd.).

[0051] (Test Results) Table 6 shows the percentage of barnacle-bearing individuals in each state when barnacle-bearing individuals reared for one week are irradiated with LED light with a peak wavelength of 405 nm. Table 7 shows the percentage of barnacle-bearing individuals in each state when barnacle-bearing individuals reared for two weeks are irradiated with LED light with a peak wavelength of 405 nm. Table 8 shows the percentage of barnacle-bearing individuals in each state when barnacle-bearing individuals reared for three weeks are irradiated with LED light with a peak wavelength of 405 nm. Table 9 shows the percentage of barnacle-bearing individuals in each state when barnacle-bearing individuals reared for four weeks are irradiated with LED light with a peak wavelength of 405 nm. Table 10 shows the percentage of barnacle-bearing individuals in each state when barnacle-bearing individuals reared for two weeks are irradiated with LED light with a peak wavelength of 460 nm. The basal diameter of the irradiated barnacle-bearing individuals was 1.0-2.0 mm for individuals reared for 1 week, 2.0-4.1 mm for individuals reared for 2 weeks, 2.5-5.1 mm for individuals reared for 3 weeks, and 3.1-5.2 mm for individuals reared for 4 weeks.

[0052] [Table 6]

[0053] [Table 7]

[0054] [Table 8]

[0055] [Table 9]

[0056] [Table 10]

[0057] As shown in Table 10, LED light with a peak wavelength of 460 nm is used at 24,000 Wm -2 When irradiated with 38,400 Whm -2 On the other hand, as shown in Tables 6 to 9, when LED light with a peak wavelength of 405 nm was used with an irradiance of 24,000 Wm -2 When irradiated with 800 Whm, 90-100% of the individuals raised and raised for 1-4 weeks after attachment died or became moribund within 12-24 minutes. -2 ) were observed to be in a non-responsive state. In addition, no increase in the resistance of barnacle-attached individuals to LED light was observed with growth. -2 It was confirmed that if the current is more than 4800Whm, it will have a lethal effect on the barnacles attached to it and can be removed from the structure. -2 By irradiating a structure with the above amount of light, it is possible to remove the attached organisms, including the structure, which already have attached organisms, and therefore it is possible to more efficiently and reliably inhibit attachment and remove the attached organisms.

[0058] [Test to confirm the effect of light irradiation on bacteria] The effect of light irradiation on bacterial growth was confirmed by smearing marine bacteria on an agar medium and counting the number of colonies that appeared after exposure to LED light.

[0059] 0.1 ml of seawater containing marine bacteria (all marine bacteria in seawater in barnacle breeding tanks) was dropped and smeared on the surface of the agar medium in a petri dish (diameter 9 cm x height 1.5 cm), and half of the smeared agar medium was covered with aluminum foil to serve as a control. The petri dishes were then stacked in one or two layers, and irradiated from above with LED light (peak wavelength: 405 nm) under the conditions of each irradiance and irradiation time shown in Tables 11 and 12. The number of colonies in the control and test areas on the surface of each agar medium about 24 hours after the start of irradiation was counted, and the occurrence rate of the colonies in the test area relative to the number of colonies in the control area was calculated.

[0060] The agar medium was prepared by adding a powdered medium (Marine Agar 2216, Difco) to 1 L of distilled water, dissolving it by heating, sterilizing it, and then dispensing about 20 ml of the medium into a petri dish and leaving it to stand for 30 to 60 minutes to prepare a solid agar medium. The seawater used to smear on the agar medium was seawater from a barnacle breeding tank, diluted 10-fold using a membrane with a pore size of 0.45 μm.

[0061] [Table 11]

[0062] [Table 12]

[0063] (Test Results) Table 11 shows the irradiation dose of 120Whm -2 , irradiation amount 480Whm -2 , and irradiation dose 1200Whm -2 Table 12 shows the incidence rate of colonies in the test area compared to the control area when LED light was irradiated under the above conditions. -2 , irradiation amount 1152Whm -2 , and irradiation dose 1536Whm -2 The rate of bacterial colony emergence when irradiated with LED light under the above conditions, and the irradiation dose of 1600Whm for the agar medium on the top -2 , irradiation amount 2400Whm -2 , and irradiation dose 3200Whm -2 The figure shows the bacterial colony appearance rate when irradiated with light at 1000 nm.

[0064] As shown in Tables 11 and 12, 480Whm -2 By irradiating with a dose of 1200Whm, the bacterial colony emergence rate was reduced to less than 70%. -2 By irradiating with a dose of 2400Whm, the bacterial colony emergence rate was reduced to less than 6%. -2It was confirmed that the generation of bacterial colonies can be prevented by irradiating the above amount of radiation. It was also confirmed that a high removal effect was achieved for the agar medium in the lower stage, which is not directly irradiated by the LED light, at a certain irradiance or higher.

[0065] [Test 1 to confirm the effect of light irradiation on airborne microorganisms] The microorganisms that had fallen onto LB medium were cultured and the number of colonies that appeared after exposure to LED light was counted to confirm the effect of light exposure on microorganisms attached to structures in the air.

[0066] 5g of tryptone, 2.5g of yeast extract, 5g of NaCl, 7.5g of agar, and 480ml of distilled water were added to a medium bottle and stirred, then autoclaved at 121°C for 20 minutes, and 20ml of the mixture was dispensed into a petri dish and solidified at room temperature to prepare LB medium. The three petri dishes containing this LB medium were placed on a counter about 90cm above the floor near the exit to the outdoors with the lids open, and left to stand for 8 hours. After 8 hours, the lids were closed, and the three petri dishes were designated as samples 1 to 3, and LED light (peak wavelength: 405nm) was irradiated from directly above each sample under the irradiation conditions for each sample shown in Table 13. After 8 hours from the start of irradiation, each sample was cultured for 48 hours in a constant temperature incubator set at 35°C, and the number of colonies on the medium surface of each sample was counted. UFL-501-08 UV-UT (manufactured by U-Technology Co., Ltd.) was used as the light source of the LED light. Sample 3, which was a petri dish that was left unexposed for 8 hours without being irradiated with LED light, was used as a control.

[0067] [Table 13]

[0068] (Test Results) Table 13 shows the number of colonies for each sample and the irradiation dose of 1600Whm -2The figures show the sterilization rates for the control area when LED light was irradiated continuously and intermittently. The sterilization rates for the control area shown in Table 13 are calculated by dividing the number of colonies in sample 1 or 2 after irradiation with LED light by the number of colonies in the control area of ​​sample 3. As shown in Table 13, 47 colonies of bacteria and fungi were observed in sample 3, which is the control area. In contrast, one colony was observed in sample 1 and three colonies were observed in sample 2, showing that the sterilization rates were significantly higher at an irradiation dose of 1600 Whm in both the continuous and intermittent irradiation cases. -2 The sterilization rate was 90% or more by irradiating with 1600Whm. This result shows that an irradiation dose of 1600Whm is sufficient for the removal of airborne bacteria, fungi, and other attached organisms that adhere to the surfaces of airborne structures. -2 It is estimated that this will result in almost complete removal.

[0069] [Test 2 to confirm the effect of light irradiation on airborne microorganisms] The microorganisms that had fallen onto the LB medium were cultivated, and the number of colonies that appeared after exposure to LED light at a lower irradiance than the radiation conditions shown in Table 13 was counted to confirm the effect of light exposure on the microorganisms attached to structures in the air.

[0070] LB medium was prepared using the same procedure as in "Test 1 for Confirming the Effect of Light Irradiation on Microorganisms in the Air," and the LB medium was placed on a counter about 90 cm above the floor near the exit to the outdoors with the lids open, and left to stand for 8 hours. After 8 hours, the lids were closed, and the five dishes were designated as samples 4 to 8, and LED light (peak wavelength: 405 nm) was irradiated from directly above each sample under the irradiation conditions for each sample shown in Table 14. After 8 hours from the start of irradiation, each sample was cultured for 48 hours in a constant temperature incubator set at 35°C, and the number of colonies on the medium surface of each sample was counted. UFL-501-08 UV-UT (manufactured by U-Technology Co., Ltd.) was used as the light source for the LED light. Samples 6 to 8, which were dishes that were left to stand for 8 hours without being irradiated with LED light, were used as controls.

[0071] [Table 14]

[0072] (Test Results) Table 14 shows the number of colonies for each sample and the irradiation dose of 160Whm -2 The figures show the sterilization rate relative to the average colony count in the control area when LED light was irradiated continuously and intermittently. The sterilization rate relative to the average colony count in the control area shown in Table 14 is the value obtained by dividing the number of colonies in sample 4 or 5 after irradiation with LED light by the average number of colonies in the control areas of samples 6 to 8. As shown in Table 14, 13 to 18 bacterial and fungal colonies were observed in the three control areas. In contrast, five colonies were observed each in samples 4 and 5, and the sterilization rate was 1.2% when the irradiation dose was 160 Whm. -2 Even when the 160Whm -2 It is presumed that even with an irradiation dose of this level, a high effect of inhibiting adhesion or removing attached organisms can be obtained.

Claims

1. A method for suppressing and removing adhesion of affixed organisms to a structure, the method comprising: irradiating the structure with light based on an irradiation amount of light set for each affixed organism, thereby suppressing adhesion of the affixed organisms to the structure or removing the affixed organisms that have attached to the structure.

2. The light irradiation amount is 160 Whm －２ The adhesion suppression and removal method according to claim 1 .

3. The light irradiation amount is 480Whm －２ The adhesion suppression and removal method according to claim 1 .

4. The light irradiation amount is 1920 Whm －２ The adhesion suppression and removal method according to claim 1 .

5. The light irradiation amount is 4800Whm －２ The adhesion suppression and removal method according to claim 1 .

6. The irradiance of the light irradiated based on the amount of light irradiation is 20 Wm －２ The adhesion suppression and removal method according to claim 1 .

7. The irradiance of the light irradiated based on the amount of light irradiation is 24000 Wm －２ The adhesion suppression and removal method according to claim 1 .

8. 8. The adhesion suppression and removal method according to claim 1, wherein the light irradiated based on the irradiation amount of the light has a peak in a wavelength range of 400 to 490 nm.

9. 8. The adhesion suppression and removal method according to claim 1, wherein the light irradiated based on the irradiation amount of the light has a peak in a wavelength range of 400 to 430 nm.

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