Attachment suppression / removal method

Abstract

The purpose of the present invention is to provide an attachment suppression / removal method with which it is possible to reliably suppress the attachment of a sessile organism to a structure or reliably remove a sessile organism from a structure. This attachment suppression / removal method includes irradiating a structure having a sessile organism attached thereto with light on the basis of a light irradiation amount set for every sessile organism, thereby suppressing the attachment of the sessile organism to the structure or removing the sessile organism attached to the structure. The light irradiation amount is 160 Whm-2 or more, and the irradiance of the light irradiated on the basis of the light irradiation amount is 20 Wm-2 or more.

Description

Adhesion suppression and removal method

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

[0002] Conventionally, there are known techniques for preventing the attachment of organisms such as barnacles to structures such as submerged water quality meters 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 a structure by irradiating the underwater structure with light having a wavelength of 409 to 412 nm.

[0003] JP 2016-188570 A

[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 or removing the numerous adhesions that have already 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 reliably remove sessile organisms from a structure.

[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 set for each of the sessile organisms, thereby suppressing adhesion of the sessile organisms to the structure or removing the sessile organisms that have attached to the structure.

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

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

[0009] (4) The irradiation amount of the light is 1920 Whm －２ The adhesion suppression and removal method according to (1) above.

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

[0011] (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 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 and removal method according to any one of (1) to (6) 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.

[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.

[0016] LED light (peak wavelength: 405 nm) with irradiance of 200 Wm －２ Fig. 2 is a diagram showing the change in state over time of Balanus cypris larvae when continuously irradiated with LED light (wavelength peak: 405 nm) at each irradiance for 96 hours. Fig. 3 is a diagram showing the change in state over time of Balanus cypris larvae in the control area of ​​the test from which the results shown in Fig. 1 were obtained. Fig. 4 is a diagram showing the relationship between the rate of juvenile barnacles and irradiance when continuously irradiated with LED light (wavelength peak: 405 nm) at each irradiance for 96 hours.

[0017] Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments and can be modified as appropriate.

[0018] <Method for suppressing and removing adhesion> The method for suppressing and removing adhesion of adhesion organisms to a structure according to this embodiment is a method for suppressing adhesion of adhesion organisms to a structure (hereinafter referred to as "suppressing adhesion") or removing adhesion organisms attached to a structure (hereinafter referred to as "removing adhesion organisms") by irradiating the structure with light based on the amount of light irradiation 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 shipyard hull, a ballast water tank, a ballast water inlet / outlet pipe, a pump, an aquaculture facility, a fisheries research station, a fishery facility, an aquarium, a fish tank in a fish and shellfish breeding tank, a pipe, a pump, a water tank and a heat sink in a cooling tower, a scrubber water tank, etc. It may also be a floor of a bathroom, a swimming pool, a shower room, etc. It may also be a seat in a room or a car that is temporarily wet with sweat, for example. It may also be an exterior or interior wall of a building, an exterior or interior surface of a window, a desk, a chair, a hospital operating room, a patient 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 surface of air bubbles in water or liquid can be targets for the accumulation and attachment of numerous sessile microorganisms. The surface, inner surface, and food inside a pack container can also be targets for the accumulation and attachment of numerous sessile microorganisms. Foam, cream, jelly, gel, and mist can also be targets for the accumulation and attachment of sessile microorganisms.

[0020] Periphyton refers to organisms that have the property of attaching to the surface of underwater structures (including structures permanently or temporarily wet with liquids such as water or sweat) or structures in the air. Periphyton may be, for example, an organism that floats in the ocean during its early larval stage and, when it reaches the sessile stage, attaches to a suitable structure and metamorphoses into an adult. Examples of periphyton include mussels, barnacles, hydrozoans, sponges, epiphytic stages of jellyfish, tube-dwelling polychaetes, bryozoans, amphipods, and other animals, as well as microorganisms belonging to bacteria, viruses, fungi, cyanobacteria, protozoa, and other groups. Periphyton 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, burrows, gene fragments, organic matter, inorganic particles, etc. When a very thin biofilm is formed on the surface of a seat or floor in a room or vehicle, food, the surface, inner surface, or internal parts of a pack container, an individual organism, algae, tissue, cells, skin, teeth, etc., this biofilm can be considered an attached organism.

[0021] The light irradiation dose is the total amount of light irradiated onto the structure to inhibit adhesion or remove sessile organisms. The light irradiation dose may be set, for example, according to the resistance of the sessile organisms to light. In this case, the light irradiation dose may be set to the same value for multiple sessile organisms with different resistances to light, or different values ​​may be set for each. When setting the same value, the irradiation dose effective for inhibiting adhesion or removing sessile organisms with the highest resistance to light may be set. By irradiating the structure with light based on the light irradiation dose set for each sessile organism, adhesion inhibition or removal of sessile organisms can be reliably carried out.

[0022] The light irradiation amount set in this embodiment is 160 Whm －２ Preferably, it is 200 Whm or more. －２ More preferably, it is 400 Whm or more. －２ More preferably, it is 480 Whm or more. －２More preferably, it is 1920 Whm or more. －２ More preferably, it is 2400 Whm or more. －２ More preferably, it is 4800 Whm or more. －２ More preferably, it is 9600 Whm or more. －２ It is particularly preferable that the power consumption is 200 Whm or more. －２ By irradiating the above amount of light to barnacles and other sessile organisms that have a relatively high resistance to light, 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 at the above dose, it is possible to increase the number of individuals in a state that can be called unresponsive, such as a state where the thoracic limbs are protruding. －２ By setting the light irradiation amount to 1920 Whm 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 larvae of barnacles and mussels to structures. Therefore, it is possible to suppress the attachment of sessile organisms that are relatively resistant to light to structures. －２ By setting the light irradiation amount at 2400 Whm or more, the number of barnacles adhering to the structure can be further reduced. －２ By setting the light irradiation amount at 4800 Whm or more, it is possible to suppress the attachment of barnacles to the structure. －２ By setting the light irradiation amount to 9600 Whm or more, it is possible to remove barnacles that have already attached to the structure. －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 It is preferable that the power consumption is 100 Wm or more. －２ More preferably, it is 24,000 Wm or more. －２ It is more preferable that the irradiance of the light is 20 Wm or more. －２By irradiating the structure with a light irradiation amount set for each type of sessile organism, it is possible to reliably suppress the adhesion of sessile organisms to the structure. －２ By doing so, adhesion prevention or removal of attached organisms can be achieved in a shorter time. Therefore, even when light is irradiated intermittently while the reef is being moved, adhesion prevention or removal of attached organisms can be achieved in a relatively short time.

[0024] The light irradiated onto the structure preferably has a peak in the wavelength range of 400 to 430 nm. Ultraviolet light with a wavelength of 380 nm or less is effective in inhibiting adhesion of sessile organisms, but has the problem of low transmittance in seawater. By setting the wavelength of the irradiated light within the above range, a preferable adhesion inhibition effect and sessile organism removal effect can be obtained. The wavelength of the irradiated light may have a peak in a wavelength range other than the above, 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 prevention or attachment 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).

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

[0027] [Test to confirm the effect of light irradiation on barnacles] The effect of LED light on inhibiting the adhesion of organisms was confirmed using cypris larvae of the barnacle Balanus nigricans (hereinafter referred to as cypris larvae). Note that cypris larvae are nauplius larvae in the planktonic stage that have repeatedly molted and grown to the attachment stage where they can attach to structures. The juvenile barnacles described below are barnacles that have metamorphosed from cypris larvae that have attached to structures such as test containers.

[0028] 70 ml of test seawater (seawater filtered through a 0.45 μm pore size membrane) and cypris larvae (number of individuals: 44±12) were placed in a test container (a 6 cm diameter × 6 cm height petri dish). 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. To prevent the temperature of the test seawater, etc. from rising due to irradiation with LED light, the outside of the bottom of the test container was immersed in tap water during the test. As a test area, 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 carried out 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 cypris larvae in each state was determined. The test container was covered with aluminum foil and kept in almost constant darkness without irradiating with LED light, which served as a control group. The irradiance was measured and adjusted through the lid of the test container using an Ophir StarLite-PD300RM-8W irradiance meter. In all of the following tests, the irradiance was measured and adjusted using this irradiance meter.

[0029] (Test results) <Irradiance 200Wm －２ Figure 1 shows the change in the state of cypris larvae under the irradiation of light with an irradiance of 200 Wm －２ 2 is a graph showing the change in the state of cypris larvae over time in the test area under an irradiance of 200 W / m －２ 1 and 2 are graphs showing the change in the state of cypris larvae over time in the control group compared to the test group. In Figures 1 and 2, the horizontal axis 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 cyprid larvae were swimming, and after 6 hours, they gradually attached to the test container and began metamorphosis, and after 24 hours, more than 30% of the individuals had become juvenile barnacles, and after 96 hours, the appearance 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 under 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 in a closed or semi-closed shell state, with their thoracic limbs protruding, or floating on the water surface. －２ The decrease begins above 4800Whm －２ It is estimated that this is almost completely suppressed.

[0032] <Ratio of juvenile barnacles under irradiation of light of various irradiances> Figure 3 is a graph showing the relationship between the ratio of juvenile barnacles and each irradiation condition when LED light is continuously irradiated at various irradiances for 96 hours. The horizontal axis of Figure 3 is irradiance (Wm －２ ) and the vertical axis shows 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 transformed from cypris larvae into juvenile barnacles, the effectiveness of the structure in inhibiting barnacle attachment 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 had attached to the bottom or side of the petri dish. In contrast, in the control area where the irradiance was 150 W / m －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 found were all dead. －２ It was confirmed that the above measures completely inhibited the growth of cypris larvae and prevented them from attaching to structures. －２The rate of juvenile barnacles in the test area was also reduced to about 70%. －２ It is estimated that by irradiating with this amount of radiation, the amount of adhesion of sessile organisms to structures can be reduced.

[0034] <Rate of cypris larvae unable to swim 2 hours and 6 hours after the start of irradiation> Table 1 shows the rate of occurrence of cypris larvae unable to swim (hereinafter referred to as "rate of unable to swim") 2 hours 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 that roll over / move their thoracic limbs (individuals that move their thoracic limbs while rolled over), individuals with protruding thoracic limbs, and individuals with closed or semi-closed shells (no reaction). The number N in the table refers to the number of tests (the same applies to the following tables).

[0035]

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

[0037] <Distribution of barnacle attachment positions> Table 2 shows the distribution of barnacle attachment positions at an irradiance of 20 Wm －２ Table 3 shows the distribution of barnacles attached to the petri dishes in the test area and the control area. －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]

[0039]

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

[0041] [Test to confirm the effect of light irradiation on hydroids] The effect of light irradiation on hydroids was confirmed using stem segments of the hydroid Hydra spp. The stem segments were prepared by separating polyps from a colony of Hydra spp. and then cutting off the roots and flowers of the Hydra spp.

[0042] 70 ml of test seawater (seawater filtered through a 0.45 μm pore size membrane) and hydra stem segments (number of segments: 12) were placed in a test container (a 6 cm diameter x 6 cm high petri dish). For the test group, the test container was continuously irradiated with LED light (peak wavelength: 405 nm) through a glass lid at the irradiance levels shown in Table 4 below. The test container was covered with aluminum foil and kept in near-constant darkness without LED light irradiation, serving as a control group. The test was conducted for 96 hours, and the regeneration rate of hydra stem segments and the number of regenerated hydra flowers were compared between the control group and each test group.

[0043]

[0044] (Test results) Table 4 shows the results at an irradiance of 100 Wm －２ and 200Wm －２ The regeneration rate of the hydra stem segments and the number of hydra flowers regenerated after 96 hours in the test and control plots are shown in Table 4. －２ and 200Wm －２When the hydra was continuously irradiated for 96 hours at two irradiance intensities of 9600 Whm, the regeneration rate of the hydra stem segments and the number of regenerated hydra flowers were confirmed to be 0%. －２ It was confirmed that the colony formation of marine hydrozoans can be completely suppressed by irradiating with the above doses.

[0045] [Comparative test of the effects of different irradiances on sessile organisms] Using cypris larvae of the Balanus nigricans, the effects on the cypris larvae of different irradiances exposed to the same amount of radiation were compared.

[0046] 2 ml of test seawater (seawater filtered through a 0.45 μm pore size membrane) and cypris larvae of the Balanus fasciatus (number of individuals: 16 ± 4) were placed in a test container (24-well microplate). For the test area, LED light (peak wavelength: 405 nm) was continuously irradiated under the irradiation conditions shown in Table 5. UFL-501-08 UV-UT (manufactured by U-Technology Co., Ltd.) was used as the light source for the LED light. To prevent the temperature of the test seawater, etc. from rising due to irradiation with 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 maintained in nearly constant darkness without LED light irradiation, which served as a control area. The rate of cypris larvae unable to swim was confirmed during the test.

[0047]

[0048] (Test results) Table 4 shows the results at an irradiance of 600 Wm －２ As shown in Table 5, the rate of swimming inability in the test areas under the irradiation conditions of 600 Wm irradiance and 8 hours irradiation time, and the irradiation conditions of 600 Wm irradiance and 0.8 hours irradiation time is shown. －２ The immobilization rate under the irradiation conditions of 6000 irradiance and 8 hours of irradiation time and 0.8 hours of irradiation time was 99% or more. A significance test was performed on the immobilization rate under these two irradiation conditions using a multiple comparison test (Tukey HSD method) using statistical software R, and no significant difference was found between the two. Furthermore, the TOSTER equivalence test resulted in the two being evaluated as statistically equivalent. From these results, it was confirmed that the adhesion inhibition and organism removal effects are approximately proportional to the product of the irradiance and irradiation time, i.e., the amount of irradiation. Furthermore, at 4800 Whm －２It is presumed that irradiation with this amount can prevent adhesion of sessile organisms to structures.

[0049] [Test to confirm adhesion removal effect] The adhesion removal effect of light irradiation on barnacles attached to structures such as test containers was confirmed.

[0050] First, 8 ml of test seawater for adhesion (seawater filtered through a 0.45 μm mesh membrane) and cypris larvae of the Balanus fasciatus (number of individuals: approximately 30) were placed in a test container (6-hole microplate), and the container was left to stand for 1 to 2 days, allowing the cypris larvae to attach to the bottom of the test container. Subsequently, the test seawater for adhesion and any unattached cypris larvae were removed from the test container, and 8 ml of rearing test seawater (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 and allowed 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 particularly large and were actively crawling were selected, and their base diameters were measured. LED light (peak wavelength: 405 nm or 460 nm) was applied at an irradiance of 24,000 W / m. －２ During the irradiation of the LED light, the state of the barnacle-attached individuals 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-infested individuals in each state when barnacle-infested individuals reared for one week were irradiated with LED light having a peak wavelength of 405 nm. Table 7 shows the percentage of barnacle-infested individuals in each state when barnacle-infested individuals reared for two weeks were irradiated with LED light having a peak wavelength of 405 nm. Table 8 shows the percentage of barnacle-infested individuals in each state when barnacle-infested individuals reared for three weeks were irradiated with LED light having a peak wavelength of 405 nm. Table 9 shows the percentage of barnacle-infested individuals in each state when barnacle-infested individuals reared for four weeks were irradiated with LED light having a peak wavelength of 405 nm. Table 10 shows the percentage of barnacle-infested individuals in each state when barnacle-infested individuals reared for two weeks were irradiated with LED light having a peak wavelength of 460 nm. The basal diameter of the barnacle-attached individuals irradiated was 1.0 to 2.0 mm for individuals reared for one week, 2.0 to 4.1 mm for individuals reared for two weeks, 2.5 to 5.1 mm for individuals reared for three weeks, and 3.1 to 5.2 mm for individuals reared for four weeks.

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] As shown in Table 10, LED light with a peak wavelength of 460 nm was used at 24,000 W / m －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 at an irradiance of 24,000 W / m, it was confirmed that approximately half of the barnacle-attached individuals were in a moribund state. －２ When irradiated with 800 Whm, it was confirmed that 90-100% of the individuals raised and grown 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 power is above 4800 Whm / s, it will have a lethal effect on the barnacles attached to it and will be possible to remove them from the structure. －２ By irradiating the structure with light at the above dose, it is possible to remove the attached organisms, including the structure itself, so that attachment can be suppressed and the attached organisms can be removed more efficiently and reliably.

[0058] [Test to confirm the effect of light irradiation on bacteria] Marine bacteria were smeared on an agar medium, and the number of colonies that appeared after irradiation with LED light was counted to confirm the effect of light irradiation on bacterial growth.

[0059] 0.1 ml of seawater containing marine bacteria (general marine bacteria in seawater in barnacle breeding tanks) was dropped onto the surface of an agar medium in a Petri dish (diameter 9 cm × height 1.5 cm) and smeared, 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 the irradiance and irradiation time shown in Tables 11 and 12. Approximately 24 hours after the start of irradiation, the number of colonies on the surface of each agar medium in the control and test groups was counted, and the occurrence rate of colonies in the test group relative to the number of colonies in the control group was calculated.

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

[0061]

[0062]

[0063] (Test Results) Table 11 shows the results for an irradiation dose of 120 Whm －２, irradiation amount 480Whm －２ , and irradiation dose 1200Whm －２ Table 12 shows the incidence rate of colonies in the test area relative to the number of colonies in the control area when LED light was irradiated under the conditions of 1. －２ , irradiation amount 1152Whm －２ , and irradiation dose 1536Whm －２ The bacterial colony appearance rate when irradiated with LED light under the conditions of 1600 Whm for the upper agar medium. －２ , irradiation amount 2400Whm －２ , and irradiation dose 3200Whm －２ The figure shows the bacterial colony appearance rate when irradiated with 10 ...

[0064] As shown in Tables 11 and 12, 480 Whm －２ By irradiating with a dose of 1200Whm, the bacterial colony occurrence rate is reduced to less than 70%. －２ By irradiating with a dose of 2400Whm, the bacterial colony occurrence rate was reduced to less than 6%. －２ It was confirmed that the generation of bacterial colonies can be prevented by irradiating the above-mentioned amount of radiation. It was also confirmed that a high removal effect was achieved even on 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] Microorganisms that had fallen onto LB medium were cultured, and the number of colonies that appeared after irradiation with LED light was counted to confirm the effect of light irradiation on microorganisms attached to airborne structures.

[0066] 5 g of tryptone, 2.5 g of yeast extract, 5 g of NaCl, 7.5 g of agar, and 480 ml of distilled water were added to a medium bottle and stirred. The mixture was autoclaved at 121 ° C. for 20 minutes, and 20 ml of the mixture was dispensed into a Petri dish and solidified at room temperature to create LB medium. Three Petri dishes containing this LB medium were placed on a counter approximately 90 cm high from the floor near the indoor 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 samples 1 to 3, respectively. Each sample was irradiated with LED light (peak wavelength: 405 nm) from directly above under the irradiation conditions for each sample shown in Table 13. 8 hours after 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 LED light source. Sample 3, which was a petri dish that had been left standing for 8 hours without being irradiated with LED light, was used as a control.

[0067]

[0068] (Test Results) Table 13 shows the number of colonies for each sample and the irradiation dose of 1600 Whm －２ The sterilization rate for the control group shown in Table 13 is the value obtained by dividing the number of colonies in sample 1 or 2 after irradiation with LED light by the number of colonies in the control group of sample 3. As shown in Table 13, 47 colonies of bacteria and fungi were observed in sample 3, the control group. In contrast, one colony was observed in sample 1 and three colonies were observed in sample 2, and the sterilization rate was 1600 Whm in both the continuous and intermittent irradiation groups. －２ This result shows that the sterilization rate is 90% or more when irradiated with a 1600 Whm dose. －２ It is estimated that this will remove it almost completely.

[0069] [Test 2 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 irradiation with LED light at an irradiance lower than the radiation conditions shown in Table 13 was counted to confirm the effect of light irradiation on microorganisms attached to airborne structures.

[0070] LB medium was prepared using the same procedure as in "Test 1 to Confirm the Effect of Light Irradiation on Airborne Microorganisms," and five petri dishes containing LB medium were placed with the lids open on a counter approximately 90 cm above the floor near the outdoor exit in a room and allowed to stand for 8 hours. After 8 hours, the lids were closed, and the five petri dishes were designated Samples 4 to 8. LED light (peak wavelength: 405 nm) was irradiated from directly above each sample under the irradiation conditions for each sample shown in Table 14. Eight hours after 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 LED light source. Samples 6 to 8, which were petri dishes that had been left standing for 8 hours without being irradiated with LED light, served as controls.

[0071]

[0072] (Test Results) Table 14 shows the number of colonies for each sample and the irradiation dose of 160 Whm －２ The table shows the sterilization rate relative to the average colony count in the control area when LED light was continuously irradiated and when it was intermittently irradiated. 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 in samples 4 and 5, and the irradiation dose was 160 Whm －２ Even when the filtration rate was 160 Whm, the sterilization rate was 60% or more. From this result, it can be seen that the sterilization rate of 160 Whm is effective against airborne bacteria, fungi, and other adherent organisms that adhere to the surfaces of airborne structures. －２ It is estimated that even with a radiation 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, by irradiating the structure with light based on an irradiation amount of light set for each affixed organism, thereby suppressing the 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 160Whm －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 1920Whm －２ The adhesion suppression and removal method according to claim 1 .

5. The irradiation amount of the light 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 above-mentioned light irradiation amount is 24000 Wm －２ The adhesion suppression and removal method according to claim 1 .

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

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

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