Attaching and propagation prevention method, attaching and propagation prevention device, and water quality meter

Abstract

Provided are: an attaching and propagation prevention method and an attaching and propagation prevention device capable of efficiently preventing attaching organisms from attaching to and / or propagating on an object, and prolonging the life of a radiation device; and a water quality meter.　The attaching and propagation prevention method is for preventing attaching organisms from attaching to and / or propagating on an object which the attaching organisms are capable of attaching to. Said method satisfies the condition represented by expression (1), and in said method, the object is intermittently irradiated with light.　Expression (1): X×a / (a+b)≥Y, where X is the irradiance (Wm-2) of the light, a is the time period in which the light is radiated, b is the time period in which the light is not radiated, and Y is the irradiance (Wm-2) set per each attaching organism.

Description

Method for inhibiting adhesion and propagation, device for inhibiting adhesion and propagation, and water quality meter

[0001] The present invention relates to a method for inhibiting adhesion and propagation, an apparatus for inhibiting adhesion and propagation, and a water quality meter.

[0002] Conventionally, there are known techniques for preventing adhesion of sessile organisms such as barnacles to structures such as 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 adhesion of sessile 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 can suppress the adhesion of sessile organisms to areas of a structure where high-irradiance light is irradiated. However, there is a problem in that the effectiveness of suppressing the adhesion of sessile organisms is insufficient, as sessile organisms may be attracted to areas where low-irradiance light is irradiated, such as between light irradiation devices or at edges, or to areas that are shaded and not exposed to light. In addition, the irradiation devices tend to deteriorate due to heat generated by light irradiation, leaving room for improvement in terms of extending the lifespan of the irradiation devices.

[0005] The present invention has been made in consideration of the above, and aims to provide an adhesion and propagation suppression method, an adhesion and propagation suppression device, and a water quality meter that can efficiently suppress the adhesion of adhesion organisms to an object and achieve a longer lifespan of the irradiation device.

[0006] (1) The present invention relates to a method for inhibiting adhesion and / or proliferation of sessile organisms on an object to which sessile organisms may adhere, which satisfies the condition expressed by the following formula (1) and involves intermittently irradiating the object with light: X×a / (a+b)≧Y (1), where X is the irradiance (Wm －２ ), a is the time when light is irradiated, b is the time when light is not irradiated, and Y is the irradiance of light (Wm －２ )

[0007] (2) The method for inhibiting adhesion propagation according to (1), wherein Y in the formula (1) is 20.

[0008] (3) The method for inhibiting adhesion and propagation according to (1), wherein Y in the formula (1) is 150.

[0009] (4) The method for inhibiting adhesion and propagation of microorganisms according to any one of (1) to (3), wherein the light irradiated onto the object has a peak in the wavelength range of 400 to 430 nm.

[0010] (5) The present invention also relates to an anti-fouling and anti-breeding device having an irradiation device that irradiates light onto an object and a control unit that controls the irradiation device, wherein the control unit controls the irradiation device so that light is irradiated intermittently from the irradiation device onto the object, satisfying the condition expressed by the following formula (1): X×a / (a+b)≧Y Formula (1), where X is the irradiance (Wm －２ ), a is the time when light is irradiated from the irradiation device, b is the time when light is not irradiated from the irradiation device, and Y is the irradiance of light (Wm －２ )

[0011] (6) The present invention also relates to a water quality meter having the adhesion propagation suppression device described in (5) and a sensor device, wherein the irradiation device irradiates light onto a detection unit of the sensor device, the light irradiated from the irradiation device has a peak in a wavelength range of 400 to 420 nm, the sensor device performs a detection operation at each predetermined detection timing, and the control unit controls the irradiation device so that light is intermittently irradiated from the irradiation device onto the detection unit at each irradiation time other than the predetermined detection timing.

[0012] (7) The water quality meter according to (6), wherein the irradiation surface of the irradiation device is arranged opposite the detection unit.

[0013] According to the present invention, it is possible to provide an adhesion and propagation inhibition method, an adhesion and propagation inhibition device, and a water quality meter that can efficiently inhibit adhesion of adhesion organisms to an object and achieve a longer life of an irradiation device.

[0014] FIG. 1 is a block diagram showing the configuration of an adhesion and propagation inhibition device according to one embodiment of the present invention. FIG. 2 is a diagram showing the configuration of a water quality meter according to a first embodiment of the present invention. FIG. 3 is a diagram showing the configuration of a water quality meter according to a second embodiment of the present invention. FIG. 4 is a diagram showing the configuration of a water quality meter according to a third embodiment of the present invention. FIG. 5 is a diagram showing the configuration of a water quality meter according to a fourth embodiment of the present invention. A box-and-whisker plot of the results of the juvenile barnacle rate. Wavelength: 405 nm, irradiance: 20 Wm ―２ This figure shows the phototaxis of cypris larvae under continuous and intermittent irradiation conditions (1 / 1, 1 / 2). ―２ The figure shows the phototaxis of cypris larvae under continuous and intermittent irradiation conditions (1 / 1, 1 / 2). ―２ This figure shows the phototaxis of cypris larvae under continuous and intermittent illumination conditions (1 / 1, 1 / 2). ―２ The figure shows the phototaxis of cypris larvae under continuous and intermittent irradiation conditions (1 / 1, 1 / 2). ―２ The figure shows the phototaxis of cypris larvae under continuous and intermittent irradiation conditions (0.1 / 0.1, 0.1 / 0.2, 0.1 / 0.3). ―２ This figure shows the phototaxis of cypris larvae under continuous and intermittent irradiation conditions (1 / 1, 1 / 2) at an irradiance of 500 W / m. －２ This figure shows the reaction status of freshwater hydra under each intermittent irradiation condition. －２ 1 is a diagram showing an evaluation of the reaction status of freshwater hydra under each intermittent irradiation condition. FIG. 2 is a diagram explaining the experimental equipment used in Example 3 of the present invention. FIG. 3 is an image showing a test plate after a test according to Comparative Example 6 of the present invention. FIG. 4 is an image showing a test plate after a test according to Example 3 of the present invention.

[0015] 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.

[0016] <Method for inhibiting adhesion growth> The method for inhibiting adhesion growth according to this embodiment is a method for inhibiting adhesion of organisms to an object by intermittently irradiating the object with light so as to satisfy predetermined conditions (hereinafter referred to as intermittent irradiation). Note that intermittent irradiation refers to irradiating the object with light by switching between a state in which the light is irradiated and a state in which the light is not irradiated.

[0017] Examples of the object include a structure installed underwater (including a structure that is permanently or temporarily wet with liquids such as water or sweat) or a structure 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 for inspecting such equipment. In addition to the above, the object may also 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 turbine, an impeller, a valve, a rotating shaft, a water conveyance pipeline, a filtration tank, a membrane, a dam, a ship, a ship hull in a shipyard, 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 / heat sink of a cooling tower, a scrubber water tank, etc. The structure may also be, for example, a floor in a bathroom, swimming pool, shower room, toilet, kitchen, etc. It may also be a seat in a room or car, a hospital operating room, a desk, a chair, the exterior or interior walls of a building, or window glass. It may also be the surface or interior of a pack container, fresh food, synthetic food, foam, cream, jelly, gel, etc. The structure referred to here may also be a living organism. For example, it may be an oyster shell or soft body part, fish, protozoa parasitic on fish, plankton, algae, microorganisms, parts of biological tissue, teeth, skin, cells, and their secretions. The structure does not have to be solid. For example, air bubbles in water can also become structures on whose surfaces numerous attached microorganisms accumulate and adhere. Similarly, liquid droplets in the air can also become structures on which numerous attached microorganisms accumulate and adhere.

[0018] The sessile organisms that can attach to the above-mentioned objects are not particularly limited as long as they have the ability to attach 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, and examples thereof include sessile organisms such as mussels, barnacles, and hydrozoans, as well as microorganisms such as bacteria, viruses, fungi, cyanobacteria, and protozoa. Sessile organisms float in the sea during their early larval stages, and when they reach the sessile stage, they attach to a suitable object and metamorphose into adults. Also included are microalgae such as sessile diatoms, green algae, brown algae, and red algae, and the larvae of sponges, jellyfish, tube-dwelling polychaetes, bryozoans, and amphizoans.

[0019] Mussels are a general term for bivalve mollusks in the family Mytilidae, and include, for example, the subfamily Modiolinae, such as the skylark mussel; the subfamily Lithophaginae, such as the stone mussel; the subfamily Crenellinae, such as the mussel and the mussel Mytilinae; and the subfamily Mytilinae, such as the mussel, the golden mussel, and the purple mussel. Furthermore, barnacles are a general term for organisms classified into Crustacea, Cirripadia, and Thoracica, including those belonging to the Balanomorpha suborder, which includes, for example, the striped barnacle, the American barnacle, the red barnacle, the triangular barnacle, the giant red barnacle, the Japanese barnacle, the rock barnacle, the white-striped barnacle, and the European barnacle. Furthermore, hydrozoans are a general term for animals in the Hydrozoa class of the Cnidaria phylum, which includes, for example, the Hydridae family of the Anthomedusae order, such as the hydra, freshwater hydra, and green hydra. The epiphytic stage of jellyfish includes the polyps of moon jellyfish and sea jellyfish.

[0020] The sessile organisms that can adhere to the above-mentioned objects also include biofilms. Biofilms 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, habitats, gene fragments, organic particles, inorganic particles, etc. In addition, when a very thin biofilm is formed on the surface of a seat or floor in a car, food, the surface, inner surface, or internal parts of a pack container, individual organisms, algae, tissues, cells, skin, teeth, etc., this biofilm can be considered a sessile organism.

[0021] The predetermined condition for intermittent irradiation with light in the method for inhibiting adhesion and propagation is a condition expressed by the following formula (1).

[0022] X×a / (a+b)≧Y Formula (1) where X is the irradiance of light (Wm －２ ), a is the time when light is irradiated (hereinafter referred to as "on time"), b is the time when light is not irradiated (hereinafter referred to as "off time"), and Y is the irradiance of light (Wm －２ In this specification, the term "on time" refers to the time from when light irradiation of an object is started to when the next irradiation is stopped in intermittent irradiation. The term "off time" refers to the time from when irradiation is stopped to when the next irradiation is started in intermittent irradiation.

[0023] As Y, an irradiance capable of inhibiting the attachment and / or proliferation of the sessile organisms to the target object (hereinafter referred to as attachment and proliferation suppression) is set according to the type of the sessile organisms. The irradiance as Y (hereinafter referred to as irradiance Y) may be set, for example, according to the resistance of the sessile organisms to light. In this case, the irradiance Y may be set to the same value for a plurality of sessile organisms having different resistances to light, or different values ​​may be set for each. When setting the irradiance Y to the same value, an irradiance Y effective for inhibiting the attachment and proliferation of the sessile organisms with the highest resistance to light may be set. In this embodiment, the same value is set regardless of the type of sessile organisms. By using the above formula (1), the light radiation conditions for suppressing attachment and proliferation can be easily set.

[0024] In this embodiment, the irradiance Y in equation (1) is, for example, 20 Wm －２ It is preferable that the －２ It is more preferable that the irradiance Y in formula (1) is 20 Wm －２ By adjusting the irradiance X of the light, the on time a, and the off time b so that the irradiance Y of the light is 150 Wm, the adhesion and / or proliferation of the sessile organisms on the object can be suppressed. －２ By adjusting the irradiance X of the light, the on time a, and the off time b so that the adhesion and / or proliferation of sessile organisms on the target object can be almost completely suppressed. Note that the irradiance in this specification refers to the value of irradiance measured using an Ophir StarLite-PD300RM-8W irradiance meter.

[0025] The lighting time a and the extinguishing time b are not particularly limited as long as they satisfy the condition of formula (1). For example, the lighting time a may be less than 0.1 seconds, 0.1 seconds or more, 1.0 seconds or more, 1.0 minute or more, or 1 hour or more. Furthermore, the extinguishing time b may be less than 0.1 seconds, 0.1 seconds or more, 1.0 seconds or more, 1.0 minute or more, or 1 hour or more. In other words, as long as formula (1) is satisfied, the lighting time a / (lighting time a+extinguishing time b) can be freely set. For example, the lighting time a / (lighting time a+extinguishing time b) may be 0.1 or 99.9.

[0026] The irradiance X of the light is not particularly limited as long as it satisfies the condition of formula (1). For example, the irradiance X is 20 Wm －２ It is preferable that the power consumption is 50 Wm or more. －２ More preferably, it is 100 Wm or more. －２ More preferably, it is equal to or greater than this.

[0027] By irradiating light intermittently and satisfying the condition of the above-described formula (1), the adhesion and / or proliferation of sessile organisms can be more reliably and efficiently suppressed, and adhesion of foreign matter to the object irradiated with light can be more effectively suppressed than by continuous light irradiation. Specifically, when light is irradiated continuously, foreign matter such as sessile organisms do not adhere to areas irradiated with strong light, but sessile organisms may be attracted to areas around the light axis irradiated with relatively weak light due to phototaxis, resulting in proliferation of sessile organisms. By irradiating the object with light intermittently, the attraction of sessile organisms due to phototaxis can be suppressed, and the adhesion and / or proliferation of sessile organisms can be efficiently suppressed. Furthermore, by irradiating the object with light intermittently from an irradiation device, such as the irradiation device 20 described below, the deterioration of the LED elements of the irradiation device over time can be suppressed, thereby improving the durability of the irradiation device. This can extend the life of the irradiation device.

[0028] The light irradiated onto the object 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 the adhesion and proliferation 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 effect of inhibiting adhesion and proliferation and an effect of removing sessile organisms 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, or may have a peak in the wavelength range of 490 nm to 550 nm.

[0029] Next, an example of an apparatus capable of suppressing adhesion or proliferation of sessile organisms on an object by the method for suppressing adhesion and proliferation will be described.

[0030] <Attachment Reproduction Inhibition Device> First, the attachment reproduction inhibition device 1 will be described with reference to Fig. 1. As shown in Fig. 1, the attachment reproduction inhibition device 1 includes an irradiation device 20 that irradiates a target object with light, and a control unit 5 that controls the irradiation device 20.

[0031] The irradiation device 20 is, for example, an LED irradiation device, and is configured to include one or more LED elements. The irradiation device 20 is connected to the control unit 5 so as to be able to communicate with each other.

[0032] The light irradiated by the irradiation device 20 preferably has a peak in the wavelength range of 400 to 430 nm. The wavelength of the irradiated light may have a peak in a wavelength range other than the above, as long as the effect of the present invention is not impaired. For example, the wavelength of the irradiated light may have a peak in the wavelength range of 430 to 490 nm, or may have a peak in the wavelength range of 490 nm to 550 nm.

[0033] The control unit 5 is a computing device configured with a processor such as a CPU, which reads and executes various preset programs and data, and controls the irradiation device 20. The control unit 5 controls the irradiation device 20 so that the irradiation device 20 irradiates the object with light intermittently while satisfying the condition expressed by the above formula (1), thereby suppressing the adhesion of sessile organisms to the object. In other words, the irradiation device 20 irradiates intermittently so as to satisfy the condition of the above formula (1).

[0034] The irradiance X of the light irradiated from the irradiation device 20 is not particularly limited as long as it satisfies the condition of formula (1). For example, the irradiance X is set to 25 Wm －２ It is preferable that the power consumption is 50 Wm or more. －２ More preferably, it is 100 Wm or more. －２ More preferably, it is equal to or greater than this.

[0035] <Water Quality Meter> Next, the water quality meter will be described with reference to FIGS. 2 to 5. The water quality meter according to this embodiment is used to continuously measure the water quality of water in environments such as the ocean, rivers, or lakes for a predetermined period of time, for example, one day or more. Examples of water quality measurement items measured by the water quality meter include water temperature, salinity concentration, dissolved oxygen (DO) concentration, chlorophyll, organic matter, turbidity, illuminance, pH, ORP (oxidation-reduction potential), conductivity, specific gravity, depth, current direction and speed, various ion concentrations, visible light and / or infrared light images, etc. The water quality meter according to this embodiment may be capable of measuring multiple of the above water quality measurement items.

[0036] The water quality meter according to this embodiment includes a sensor device as a target, an illumination device that illuminates the detection unit of the sensor device with light, and a control unit that controls the illumination device. The combined configuration of the illumination device and control unit of the water quality meter corresponds to the adhesion and proliferation inhibition device 10.

[0037] 2, the water quality meter 1 according to this embodiment is a water temperature / salinity meter having a salinity concentration sensor (detection unit 31) and a water temperature sensor (detection unit 32) as sensor devices. In addition to the above, the water quality meter 1 also includes irradiation devices 20a and 20b, a main body 4, a control unit 5, and a support 7a.

[0038] (Irradiation Device) The irradiation devices 20a and 20b intermittently irradiate the detection unit 31 of the salinity concentration sensor and the detection unit 32 of the water temperature sensor with light having a peak in the wavelength range of 400 to 430 nm. This suppresses the adhesion of organisms to the detection unit 31 of the salinity concentration sensor and the detection unit 32 of the water temperature sensor. The irradiation devices 20a and 20b are, for example, LED irradiation devices and are configured to include one or more LED elements. The irradiation devices 20a and 20b each have a housing 21a and 21b and an irradiation surface 22a and 22b. The irradiation surface 22a is positioned opposite one opening 31a of the hole in which the detection unit 31 of the salinity concentration sensor is disposed and the detection unit 32 of the water temperature sensor. The irradiation surface 22b is positioned opposite the other opening 31b of the hole in which the detection unit 31 of the salinity concentration sensor is disposed.

[0039] The attached organisms that may adhere to the detection unit are not particularly limited as long as they have the property of adhering to the surface of an object placed in water, but examples include microorganisms such as mussels, barnacles, hydrozoans, and marine bacteria, as well as biofilms.

[0040] The light emitted from the irradiation devices 20a and 20b has a peak in the wavelength range of 400 to 430 nm. The wavelength of the irradiated light may include wavelength ranges other than the above, as long as the effect of the present invention is not impaired. For example, the irradiated light may include light in the wavelength range of 400 to 440 nm.

[0041] The irradiance of the light emitted from the irradiation devices 20a and 20b is set to 25 Wm from the viewpoint of suppressing the adhesion of attached organisms. －２ It is preferable that the power consumption is 50 Wm or more. －２ More preferably, it is 100 Wm or more. －２ More preferably, it is equal to or greater than this.

[0042] By irradiating light intermittently from the irradiation devices 20a and 20b, adhesion of foreign matter to the detection units 31 and 32, which are irradiated with light, can be more effectively suppressed than by continuous light irradiation. Specifically, when light is irradiated continuously, foreign matter such as attached organisms does not adhere to areas irradiated with strong light, but attached organisms such as algae that grow by photosynthesis may be more likely to grow in areas around the light axis irradiated with relatively weak light. This is thought to be because the light irradiated from the irradiation devices 20a and 20b includes wavelengths of light effective for photosynthesis. The intermittent irradiation of light from the irradiation devices 20a and 20b suppresses the growth of algae and the like. While the reason for this is unclear, one possible reason is that the intermittent irradiation of light results in an insufficient amount of light for photosynthesis by algae and the like, inhibiting their growth.

[0043] Intermittent light irradiation from the irradiation devices 20a and 20b has the effect of suppressing the adhesion of algae and the like to the irradiation surfaces 22a and 22b of the irradiation devices 20a and 20b. When the irradiation devices 20a and 20b are configured to include multiple LED elements and continuously irradiate light from the irradiation devices 20a and 20b, algae and the like may adhere between the multiple LED elements, resulting in a decrease in the irradiance of the irradiated light. However, by intermittently irradiating light from the irradiation devices 20a and 20b, even when the irradiation devices 20a and 20b include multiple LED elements, a decrease in the irradiance of the irradiated light can be suppressed. Furthermore, intermittent light irradiation from the irradiation devices 20a and 20b suppresses deterioration of the LED elements over time, thereby improving the durability of the water quality meter 1.

[0044] (Sensor Device) The salinity sensor is a sensor device that detects the salinity concentration in water. The detection unit 31 of the salinity sensor is provided in a hole through which liquid can flow. If the flow of liquid such as seawater is obstructed due to the adhesion of attached organisms to the hole, the salinity sensor cannot accurately measure the salinity. Light emitted from the illumination devices 20a and 20b of the water quality meter 1 according to this embodiment suppresses the adhesion of attached organisms not only to the detection unit 31 but also to the hole in which the detection unit 31 is located. This allows the salinity sensor to continuously and accurately measure the salinity.

[0045] The water temperature sensor is a sensor device that detects water temperature. Light emitted from the illumination device 20a to the detection section 32 of the water temperature sensor inhibits the adhesion of organisms to the detection section 32. This allows the water temperature sensor to continuously and accurately measure the water temperature.

[0046] The salinity concentration sensor and the water temperature sensor as the sensor device are set to perform a detection operation at a predetermined detection timing. The detection interval for performing the detection is not particularly limited, but can be, for example, 10 minutes or more to prevent the detection results of the sensor device from being affected by residual heat from the light irradiated from the irradiation device. The detection interval may be one day. It is preferable that the predetermined detection timings of the salinity concentration sensor and the water temperature sensor are the same.

[0047] (Main body) The main body 4 houses the salinity sensor and the water temperature sensor. In addition to the above, the main body 4 may also include a storage unit that stores the measurement results of the salinity sensor and the water temperature sensor.

[0048] (Controller) The controller 5 controls the irradiation timing of the irradiation devices 20a and 20b so that light is intermittently emitted from the irradiation devices 20a and 20b. The controller 5 is communicably connected to the irradiation devices 20a and 20b via wiring 6a and 6b, respectively.

[0049] The control unit 5 controls the illumination devices 20a and 20b to illuminate the detection unit 31 of the salinity concentration sensor and the detection unit 32 of the water temperature sensor with light at each illumination time other than the predetermined timing at which the salinity concentration sensor and the water temperature sensor perform their detection operations. If the salinity concentration sensor and the water temperature sensor perform their detection operations while the illumination devices 20a and 20b are irradiating the detection units 31 and 32 with light, the salinity concentration sensor and the water temperature sensor may not be able to perform accurate measurements. However, with the above configuration, the control unit 5 controls the illumination devices 20a and 20b not to irradiate the detection units 31 and 32 with light while the salinity concentration sensor and the water temperature sensor are performing their detection operations. This allows the salinity concentration sensor and the water temperature sensor to perform accurate measurements. From the perspective of accurate measurement, it is preferable that the predetermined timing at which the salinity concentration sensor and the water temperature sensor perform their detection operations be the center of the time when the illumination devices 20a and 20b are not irradiating light.

[0050] It is preferable that the control unit 5 controls the irradiation devices 20a and 20b so that the ratio of the irradiation time during which light is irradiated from the irradiation devices 20a and 20b to the detection units 31 and 32 is 30 to 70% of the total of the irradiation time and the time during which light is not irradiated from the irradiation devices 20a and 20b (i.e., the elapsed time). This has the effect of preventing the adhesion of foreign matter such as sessile organisms, and can also suppress the adhesion of algae and the like to areas irradiated with relatively weak light.

[0051] For example, if the detection interval of the sensor device is 20 minutes and the irradiation time ratio is 50%, the control unit 5 causes the irradiation devices 20a and 20b to irradiate light onto the detection units 31 and 32 five minutes after the detection timing of the sensor device. Light is continuously irradiated from the irradiation devices 20a and 20b for the 10-minute irradiation time. After the 10-minute irradiation time has elapsed, the control unit 5 stops the irradiation of light from the irradiation devices 20a and 20b. Then, five minutes later, the detection timing of the next sensor device arrives, and the sensor device performs a detection operation. This makes it possible to eliminate the influence on the detection of the sensor device, such as an increase in water temperature caused by the irradiation of light from the irradiation devices 20a and 20b.

[0052] (Support Body) The support body 7a is a support body for fixing the irradiation devices 20a and 20b, and is configured to allow water from the outside to pass through the detection units 31 and 32. The support body 7a has, for example, a frame shape, and is not particularly limited in material, and materials such as metal and resin can be used as appropriate. The support body 7a allows the irradiation surfaces 22a and 22b to be positioned so as to face the detection units 31 and 32.

[0053] Other embodiments of the present invention will be described below, and the description of the same configuration as the first embodiment may be omitted.

[0054] 3, a water quality meter 1a according to a second embodiment includes a dissolved oxygen (DO) concentration sensor (detection unit 33) and a water temperature sensor (detection unit 34) as sensor devices. In addition to the above, the water quality meter 1a also includes an irradiation device 20c, a main body 4a, a control unit 5a, a support 7b, and a wiper device 8.

[0055] The irradiation device 20c according to this embodiment includes a housing 21c and an irradiation surface 22c. In this embodiment, the irradiation device 20c is a single irradiation device, and the irradiation surface 22c is disposed opposite a detection unit 33 of the dissolved oxygen (DO) concentration sensor and a detection unit 34 of the water temperature sensor. The irradiation device 20c is fixed and supported by a support body 7b. The support body 7b has a frame shape similar to the support body 7a.

[0056] The dissolved oxygen (DO) concentration sensor is a sensor device that measures the dissolved oxygen (DO) concentration in water. The detection unit 33 of the dissolved oxygen (DO) concentration sensor and the detection unit 34 of the water temperature sensor are intermittently irradiated with light having a peak in the wavelength range of 400 to 430 nm from the illumination device 20c, thereby suppressing the adhesion of organisms to the detection unit 33 and the detection unit 34. The configuration in which the detection timing of the dissolved oxygen (DO) concentration sensor and the water temperature sensor, and the irradiation timing of light irradiation from the illumination device 20c are controlled by the control unit 5a is the same as in the water quality meter 1 according to the first embodiment. The control unit 5a is housed inside the main body 4a and is communicatively connected to the illumination device 20c via wiring 6c.

[0057] (Wiper Device) The wiper device 8 is a device that removes, by wiping, any attached organisms that adhere to the detection unit 33 of the dissolved oxygen (DO) concentration sensor and the detection unit 34 of the water temperature sensor. The wiper device 8 has abutting portions that rotatably abut against the detection units 33 and 34. The abutting portions are made of a flexible material such as resin. By having the wiper device 8 in addition to the irradiation device 20c, even if one device is unable to sufficiently inhibit or remove the attachment and proliferation of attached organisms from the detection units 33 and 34 due to a malfunction of the device or the like, the water quality meter 1a can still achieve the effect of inhibiting or removing the attachment and proliferation of attached organisms from the detection units 33 and 34 by the other device, thereby enabling more reliable and accurate measurement by the sensor device.

[0058] 5, a water quality meter 1c according to a third embodiment includes a pH / ORP sensor (detection unit 36), a chlorophyll / turbidity sensor (detection unit 37), and a depth sensor (detection unit 38) as sensor devices. In addition to the above, the water quality meter 1c also includes an irradiation device 20e, a main body 4c, and a control unit 5c.

[0059] The illumination device 20e according to this embodiment includes a housing 21e and an illumination surface 22e. In this embodiment, the illumination device 20e is a single illumination device, and the illumination surface 22e is disposed opposite the pH / ORP sensor detection unit 36, the chlorophyll / turbidity sensor detection unit 37, and the depth sensor detection unit 38. The illumination device 20e is fixed and supported by a support 7c. The support 7c has a frame shape similar to the support 7a.

[0060] The pH / ORP sensor is a sensor device that measures the hydrogen ion index and oxidation-reduction potential (ORP) in water. The chlorophyll / turbidity sensor is a sensor device that measures the chlorophyll concentration and turbidity in water. The depth sensor is a sensor device that measures the depth from the water surface.

[0061] The light having a peak in the wavelength range of 400 to 430 nm is intermittently irradiated from the illumination device 20e onto the pH / ORP sensor detection unit 36, the chlorophyll / turbidity sensor detection unit 37, and the depth sensor detection unit 38, thereby suppressing the adhesion of organisms to the detection units 36, 37, and 38. The configuration in which the detection timing of the pH / ORP sensor, the chlorophyll / turbidity sensor, and the depth sensor, and the irradiation timing of light irradiation from the illumination device 20e are controlled by the control unit 5c is the same as in the water quality meter 1 according to the first embodiment. The control unit 5c is housed inside the main body 4c and is communicatively connected to the illumination device 20e by wiring 6e.

[0062] Next, an example in which the method for inhibiting adhesion and propagation according to this embodiment is applied to an underwater camera device will be described. As shown in Figure 4, the underwater camera device 1b has an illuminance sensor (detection unit 35) as a sensor device. In addition to the above, the underwater camera device 1b also has an illumination device 20d, a main body 4b, a control unit 5b, a wiper device 8a, and an imaging unit (camera lens 9).

[0063] The underwater camera device 1b is capable of periodically capturing underwater images using an imaging unit. The underwater images are, for example, visible light images. The underwater camera device 1b is equipped with multiple illumination devices 20d around the camera lens 9. The illumination devices 20d can emit light having a peak in the wavelength range of 400 to 430 nm, and preferably can also emit white light.

[0064] The on-time a and off-time b of the light irradiated from the irradiation device 20d and having a peak in the wavelength range of 400 to 430 nm are not particularly limited as long as they satisfy the condition of formula (1). In other words, as long as formula (1) is satisfied, the control unit 5b can freely set the on-time a / (on-time a + off-time b). For example, the on-time a / (on-time a + off-time b) may be set to 0.1 or 99.9.

[0065] The illumination device 20d may be used as illumination by emitting light in synchronization with the image capturing timing of the image capturing unit. For example, when the ambient illuminance is low at the image capturing timing of the image capturing unit, white light may be emitted from the illumination device 20d, and by emitting white light as illumination, an image including color information of the object to be captured can be obtained.

[0066] When the ambient illuminance is low at the time of photographing by the imaging unit, if light having a peak in the wavelength range of 400 to 430 nm is emitted from the illumination device 20d, light having a peak in the wavelength range of 400 to 430 nm has a wavelength range that is highly transparent in the sea, so underwater images of relatively distant areas can be photographed.

[0067] In this embodiment, a plurality of (seven in this embodiment) irradiation devices 20d are provided around the camera lens 9.

[0068] The illuminance sensor (detection unit 35) measures the ambient illuminance and turns on the illumination from the irradiation device 20d when the ambient illuminance is lower than a predetermined value (dark conditions).

[0069] Next, another example of application of the method for inhibiting adhesion and proliferation according to this embodiment will be described. In the example of application to the underwater camera device described above, adhesion and proliferation was inhibited using the illumination device 20 that irradiates light intermittently, but adhesion and proliferation may also be inhibited using a device that irradiates light continuously (hereinafter referred to as continuous illumination).

[0070] For example, with the irradiation device fixed, light is continuously irradiated onto the blades of a rotating propeller. At this time, instead of irradiating the entire propeller with light from the irradiation device, the position of the propeller and the direction of light irradiation are fixed, and light is irradiated so that some of the propeller blades are irradiated with light. This makes it possible to intermittently irradiate each propeller blade while continuously irradiating from the irradiation device. Then, by adjusting the propeller rotation speed and the irradiance of light from the irradiation device to satisfy the above-mentioned formula (1), adhesion of sessile organisms can be efficiently suppressed.

[0071] For example, a large structure such as a moored ship may be continuously irradiated with light by mounting an irradiation device on a drone or the like and moving it to scan the ship. In this case, moving the irradiation device so that light is periodically irradiated at the same location on the ship achieves the same effect as intermittent irradiation. Furthermore, by adjusting the irradiance from the irradiation device and the movement speed of the irradiation device to satisfy the condition expressed by Equation (1) and performing continuous irradiation, adhesion of fouling organisms can be efficiently suppressed. Furthermore, for example, under transient seawater flow conditions, high-intensity light can be irradiated upstream, followed by suppressing adhesion in the downstream area for a certain period of time, and then allowing adhesion to recover after drainage, thereby efficiently suppressing biofouling damage within the facility without affecting the environment. This irradiation method can also be considered a type of intermittent irradiation.

[0072] 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.

[0073] [Test 1 for Confirming Adhesion Suppression Effect] The effect of LED light on the suppression of biological adhesion 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 become attachable to a target object. The juvenile barnacles described below are barnacles that have metamorphosed from cypris larvae that have attached to a target object such as a test container.

[0074] A test container (a petri dish with a diameter of 6 cm and a height of 6 cm) was filled with 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, irradiance: 1200 Wm －２ In the test area, 30±5 mm of barnacles were placed inside. LED light (peak wavelength: 405 nm) was irradiated through a glass lid into the test container under the irradiation conditions shown in Tables 1 to 3 below. 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 from rising due to the LED light irradiation, the outside of the bottom of the test container was immersed in tap water during the test. The control area was a test container covered with aluminum foil and kept in near-constant darkness without LED light irradiation. The test was conducted for 96 hours, and the juvenile barnacle rate between the control area and each test area was compared. The juvenile barnacle rate is the percentage of juvenile barnacles among the total number of Barnacles serrata present in each test container.

[0075]

[0076]

[0077]

[0078] (Test results) Table 1 shows the results at an irradiance of 100 Wm －２ Continuous irradiation, irradiance 200Wm －２ Continuous irradiation, irradiance 200Wm －２ Table 2 shows the percentage of juvenile barnacles in the test plots with intermittent irradiation (0.2 seconds on / 0.1 seconds off, 0.1 seconds on / 0.1 seconds off, 0.1 seconds on / 0.2 seconds off) and the control plots. －２ Intermittent irradiation (0.1 seconds on / 0.1 seconds off), irradiance 600Wm －２Table 3 shows the percentage of juvenile barnacles in the test area with intermittent irradiation (0.1 seconds on / 0.2 to 1.1 seconds off) and the control area. －２ Intermittent irradiation (5 minutes on / 10 minutes off), irradiance 1200Wm －２ The figures show the percentage of juvenile barnacles in the test area with intermittent illumination (12 minutes on / 60 minutes off) and the control area. The number N in Table 1 refers to the number of tests (the same applies to the following tables).

[0079] As shown in Table 1, when the irradiance is 200 Wm －２ It was confirmed that under the illumination conditions of 0.1 seconds on / 0.1 to 0.2 seconds off, barnacle attachment could be significantly reduced compared to the control area. Under the illumination conditions of continuous illumination and 0.2 seconds on / 0.1 second off, none of the very few attached individuals showed any crawling movement, confirming that attachment to the test container could be almost completely suppressed.

[0080] As shown in Table 2, the irradiance was 400 Wm －２ The illumination conditions were 0.1 seconds on / 0.1 seconds off and the irradiance was 600 Wm －２ Under the irradiation conditions of 0.1 seconds on / 0.2 seconds off, even the very few attached individuals showed no crawling movements, and it was confirmed that attachment to the test container could be almost completely suppressed. －２ It was confirmed that under the illumination condition of 0.1 seconds on / 1.1 seconds off, it was possible to suppress barnacle adhesion by approximately 0.4% compared to the control area. Under other illumination conditions, it was confirmed that it was possible to significantly reduce barnacle adhesion compared to the control area.

[0081] As shown in Table 3, the irradiance was 600 Wm －２ The illumination conditions were 5 minutes on / 10 minutes off and the irradiance was 1200 Wm －２ Under the illumination conditions of 12 minutes on / 60 minutes off, none of the very few attached individuals showed any crawling movements, confirming that attachment to the test container could be almost completely suppressed.

[0082] As shown in Tables 1 to 3, the irradiance is 200 Wm －２ The rate of juvenile barnacles in continuous irradiation (0.5±1.3%), irradiance 400Wm －２The rate of juvenile barnacles (0.5±1.2%) at 0.1 seconds on / 0.1 seconds off, irradiance 600Wm －２ The rate of juvenile barnacles (0.9±1.6%) at 0.1 seconds on / 0.2 seconds off, irradiance 600Wm －２ The juvenile barnacle rate (0.7±1.0%) at 5 minutes on / 10 minutes off and irradiance of 1200 Wm －２ The juvenile barnacle rate (1.8±2.7%) for 12 minutes on / 60 minutes off was very similar. －２ The rate of juvenile barnacles (7.5±5.8%) under continuous irradiation at an irradiance of 600 Wm －２ The results were very similar for the juvenile barnacle rate (7.5±6.5%) under the 0.1 second light on / 0.5 second off conditions.

[0083] (Significant Differences in Test Results) Here, the results of the juvenile barnacle rate under each irradiation condition in Test 1 to confirm adhesion suppression effect were tested for significant differences using a multiple comparison test (Tukey HSD method) using statistical software R. Figure 6 is a box plot of the results of the juvenile barnacle rate under each irradiation condition. The horizontal axis of Figure 6 shows each irradiation condition in Test 1 to confirm adhesion suppression effect, and the vertical axis shows the juvenile barnacle rate (%). Note that A1 is the rate of juvenile barnacles at an irradiance of 200 Wm －２ A2 is continuous irradiation with an irradiance of 400 Wm －２ Intermittent illumination of 0.1 seconds on / 0.1 seconds off, A3 is irradiance 600Wm －２ Intermittent illumination of 0.1 seconds on / 0.2 seconds off, A4 has an irradiance of 600Wm －２ Intermittent irradiation of 5 minutes on / 10 minutes off, A5 is irradiance 1200Wm －２ Intermittent irradiation of 12 minutes on / 60 minutes off, B1 is irradiance 100Wm －２ B2 is continuous irradiation with an irradiance of 600 Wm －２ This shows intermittent illumination with 0.1 seconds on and 0.5 seconds off.

[0084] The results of the significance test showed no significant differences between the results of the juvenile barnacle rates in A1 to A5 (p-value > 0.05, p-value 0.26-0.99).Similarly, no significant differences were found between the results of the juvenile barnacle rates in B1 and B2 (p-value > 0.05, p-value 0.99).

[0085] From the results of the juvenile barnacle rates between A1 to A5 and B1 and B2 and the results of the significant difference test, it can be confirmed that the radiation conditions necessary for suppressing adhesion in each intermittent irradiation are proportional to the irradiation energy. In other words, it was confirmed that the radiation conditions necessary for suppressing adhesion of organisms in intermittent irradiation satisfy the above-mentioned equation (1).

[0086] Here, the irradiance is 20 Wm －２ Continuous irradiation (peak wavelength of light: wavelength range of 400 to 430 nm) can suppress the attachment and / or reproduction of barnacle larvae to the target object, and the irradiance is 150 Wm ―２ It has been found that continuous irradiation of an object with light (peak wavelength of light: wavelength region of 400 to 430 nm) can almost completely prevent barnacle larvae from attaching to the object. Using these findings, the light irradiation conditions required to prevent barnacle attachment when light (peak wavelength of light: wavelength region of 400 to 430 nm) is irradiated intermittently can be calculated using the following formula (2) or formula (3).

[0087] X×a / (a+b)≧20...Formula (2) X×a / (a+b)≧150...Formula (3)

[0088] [Phototaxis Confirmation Test] The phototaxis of cypris larvae was confirmed. LED light (peak wavelength: 405 nm) was continuously irradiated onto cypris larvae in a test container for 96 hours using the same procedure as in Test 1 for Confirming the Adhesion Suppression Effect, except for the LED light irradiation conditions. －２ and 50Wm －２ The test was carried out under two irradiance conditions.

[0089] (Test results) Table 4 shows the results at an irradiance of 20 Wm －２ Table 5 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.

[0090]

[0091]

[0092] As shown in Tables 4 and 5, 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.

[0093] [Test to confirm effect on phototaxis] Using cypris larvae of the Balanus arvensis, the effect of LED light on the swimming behavior of the cypris larvae was confirmed.

[0094] A test tank (width 1 cm x height 1 cm x length 12 cm) was filled with 20 ml of test seawater (seawater filtered through a 0.45 μm pore size membrane), and a light source was placed at one end of the test tank in the longitudinal direction to irradiate the test tank with LED light horizontally. As light sources, UFL-501-08 UV-UT (U-Technology Co., Ltd.) (wavelength peak: 405 nm) and UFL-501-08 G-UT (U-Technology Co., Ltd.) (wavelength peak: 520 nm) were used. The test tanks were numbered 1 to 24 as lane numbers in ascending order at 5 mm intervals from the end of the light source side in the longitudinal direction. Cypris larvae were placed in lane 12 of the test tank filled with test seawater, and LED light was irradiated from the light source under each irradiation condition. The irradiation conditions will be described later. One minute after the start of irradiation, it was confirmed which lane the cypris larvae had moved to. Fifteen cypris larvae were used in each test, and five cypris larvae were placed in each test tank and observed three times. This test was repeated three times for each illumination condition. In other words, a total of 45 cypris larvae were tested under each illumination condition.

[0095] (Irradiation conditions) The LED light irradiation conditions are a wavelength peak of 405 nm or a wavelength peak of 520 nm, and an irradiance of 20 Wm ―２ , 400Wm ―２, 600Wm ―２ , or 2000Wm ―２ The phototaxis of cypris larvae was confirmed under continuous irradiation or the following intermittent irradiation under conditions combining each wavelength and irradiance. <Intermittent irradiation conditions> There were five conditions, where the light-on time (seconds) is divided by the light-off time (seconds): 0.1 / 0.1, 0.1 / 0.2, 0.1 / 0.3, 1 / 1, and 1 / 2.

[0096] (Test Results) Figures 7 to 12 show the results of this test. The horizontal axis of Figures 7 to 12 is the lane number of the test tank in which cypris larvae were confirmed one minute after the start of irradiation, and the vertical axis is the average number of cypris larvae that moved to each lane number across three tests.

[0097] 7 to 11 show the test results for radiation conditions at a wavelength of 405 nm, and FIG. 12 shows the test results for radiation conditions at a wavelength of 520 nm. ―２ The irradiation conditions are continuous irradiation and intermittent irradiation (1 / 1, 1 / 2). Figure 8 shows the irradiance of 400 Wm ―２ The irradiation conditions are continuous irradiation and intermittent irradiation (1 / 1, 1 / 2). Figure 9 shows the irradiance of 600 Wm ―２ The irradiation conditions are continuous irradiation and intermittent irradiation (1 / 1, 1 / 2). Figure 10 shows the irradiance of 2000 Wm ―２ The irradiation conditions are continuous irradiation and intermittent irradiation (1 / 1, 1 / 2). Figure 11 shows the irradiance of 600 Wm ―２ The irradiation conditions were continuous irradiation and intermittent irradiation (0.1 / 0.1, 0.1 / 0.2, 0.1 / 0.3). Figure 12 shows the irradiation conditions of 600 Wm ―２ The irradiation conditions are continuous irradiation and intermittent irradiation (1 / 1, 1 / 2).

[0098] As shown in Figures 7 to 11, it was confirmed that continuous irradiation with LED light of a wavelength of 405 nm caused the cypris larvae to tend to approach the light source and to swim in the opposite direction from the light source. ―２With continuous illumination, a clear repellent / escape behavior was observed, with the fish swimming in the opposite direction from the light source. On the other hand, with intermittent illumination, fewer individuals were attracted to the light source compared to continuous illumination, and fewer individuals tended to escape from the light source in the opposite direction. From these results, it can be inferred that intermittent illumination suppresses the movement of cypris larvae due to phototaxis in response to light illumination.

[0099] As shown in Figure 12, continuous illumination of 520 nm wavelength was confirmed to induce many larvae to swim toward the light source. On the other hand, intermittent illumination was confirmed to result in fewer individuals approaching the light source compared to continuous illumination. In other words, it is presumed that intermittent illumination suppresses the phototactic attraction of cypris larvae to light with a wavelength of 520 nm.

[0100] [Test 2 for Confirming Adhesion Inhibitory Effect] The adhesion inhibitory 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.

[0101] 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 glass petri dish, 6 cm diameter x 6 cm height). For the test group, the test container was irradiated with LED light (peak wavelength: 405 nm) through a glass lid under the irradiation conditions shown in Tables 4 and 5 below. The test container was covered with aluminum foil and kept in near-constant darkness without LED light irradiation, which served 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.

[0102]

[0103]

[0104] (Test results) Table 6 shows the results at an irradiance of 200 Wm －２ Table 7 shows the regeneration rate and number of regenerated Hydra flower in the test plot and the control plot under the irradiation condition of intermittent irradiation (1 hour on / 1 hour off) at an irradiance of 200 W / m －２As shown in Tables 6 and 7, the regeneration rate of hydra stem segments and the number of regenerated hydra flowers after 96 hours in the test plots and the control plots under the irradiation conditions of intermittent irradiation (2 hours on / 2 hours off) at an irradiance of 200 W / m －２ Under the two intermittent irradiation conditions, the regeneration rate of the hydra stem segments and the number of hydra flowers regenerated after 96 hours were confirmed to be 0%. During the test, the stem tissue of the hydra was observed to gradually regress and disintegrate from the cut area. From these results, it can be seen that under the irradiance of 200 W / m －２ It was confirmed that colony formation of marine hydroids can be completely suppressed under two intermittent illumination conditions: (1 hour on / 1 hour off) and (2 hours on / 2 hours off). Furthermore, when compared with the results of Test 1 for Confirming the Adhesion Suppression Effect, it is presumed that hydroids have lower tolerance to indigo light with a wavelength of 405±25 nm than barnacles.

[0105] [Test 3 for Confirming Adhesion Inhibitory Effect] The effect of light irradiation on freshwater hydra was confirmed. 3 ml of test water was placed in a 12-well plate, and one freshwater hydra was placed in each well. After confirming that the tentacles and body were sufficiently extended, the well plate was irradiated diagonally from above with LED light (peak wavelength: 405 nm) under each of the irradiation conditions described below. The irradiation time was 3 minutes, and the freshwater hydra were observed under a microscope to see if their bodies contracted or shrunk during irradiation. 15 individuals were observed for each irradiation condition.

[0106] The test water was prepared by adding 2 ml of each of the following solutions (a) to (c) to 1 L of pure water: (a) 0.5 M CaCl ２ , 0.5 M NaCl, 0.05 M KCl (b) 0.05 M MgSO ４ (c) 0.5 M Tris HCl (pH 7.5)

[0107] The LED light irradiation conditions were irradiance of 500 Wm －２ or 1000Wm －２ The intermittent irradiation conditions were set at each irradiance level. The lighting time was fixed at 0.1 seconds, and the lighting-off time was set as follows for each irradiance level: <500 Wm －２Light-off time at > 0 seconds (i.e., continuous irradiation), 0.1 seconds, 0.2 seconds, 0.3 seconds, 0.4 seconds, 0.5 seconds, 0.6 seconds, 0.7 seconds, 0.8 seconds, 0.9 seconds, 1.0 seconds < 1000 Wm －２ Light-off time > 0 seconds (i.e., continuous irradiation), 0.8 seconds, 0.9 seconds, 1.0 seconds, 1.3 seconds, 1.5 seconds, 2.0 seconds, 3.0 seconds

[0108] (Test results) Figure 13 shows the results at an irradiance of 500 Wm －２ The results show the evaluation of the reaction of freshwater hydra to the LED light irradiation under each intermittent irradiation condition in the case of irradiance or 1000 Wm －２ 13 and 14 show an evaluation of the reaction status of freshwater hydra to irradiation with LED light under each intermittent irradiation condition. The horizontal axis of Figures 13 and 14 shows the extinguishing time for each intermittent irradiation condition, and the vertical axis shows the proportion of freshwater hydra that showed each reaction to the total. The reaction status was evaluated as "body contraction," indicating that the body of the freshwater hydra contracted, "recovery after contraction," indicating that the body contracted and then recovered, or "no response," indicating no response to the irradiation with LED light. In Figures 13 and 14, "body contraction" is represented by the densest dot pattern, "recovery after contraction" by the next densest dot pattern, and "no response" by the sparsest dot pattern.

[0109] As shown in FIG. 13, the irradiance is 500 Wm －２ In the case of 1000Wm, it was confirmed that more than 80% of individuals showed a body contraction reaction when the light was on for 0.1 seconds and the light was off for 0.1 to 0.3 seconds. －２ In this case, it was confirmed that 80% or more of the individuals showed a body contraction response when the light was on for 0.1 seconds and off for 0.8 to 1.0 seconds. On the other hand, it was confirmed that the body contraction response rate decreased when the light was off for 1.3 seconds or more. From these results, it is inferred that, for freshwater hydra, attachment to an object can be suppressed in the same way as with continuous irradiation by using predetermined intermittent irradiation conditions set, for example, using the above formula (2).

[0110] [Test 4 for Confirming Adhesion Inhibitory Effect] 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.

[0111] 0.1 ml of seawater containing marine bacteria (all marine bacteria present in the seawater of barnacle breeding tanks) was dropped onto the surface of an agar medium in a Petri dish (diameter 9 cm x height 1.5 cm) and smeared. Half of the smeared agar medium was covered with aluminum foil to serve as a control. The Petri dish was then irradiated from above with LED light (peak wavelength: 405 nm) under each of the irradiation conditions shown in Table 8, and the number of colonies on the surface of each agar medium in the control and test groups was counted approximately 24 and 48 hours after the start of irradiation. This process was repeated three times, and the incidence rate of colonies in the irradiated group relative to the number of colonies in the control group was calculated.

[0112] 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. Seawater used for smearing on the agar medium was diluted 10-fold with seawater filtered through a membrane with a pore size of 0.45 μm.

[0113]

[0114] (Test results) Table 8 shows the results at an irradiance of 200 Wm －２ When continuously irradiated for 8 hours at an irradiance of 400 Wm －２ When the lamp is irradiated intermittently (1 minute on / 1 minute off) for 8 hours, the irradiance is 400 Wm －２ The figure shows the rate of colony appearance in the irradiated area compared to the number of colonies in the control area (hereinafter referred to as bacterial colony appearance rate) when the LED light was irradiated intermittently (1 hour on / 1 hour off) for 8 hours. The LED light irradiation amount under all three irradiation conditions was the same, 1600 Whm －２ is.

[0115] As shown in Table 8, under all irradiation conditions, the bacterial colony emergence rate was less than 10% even after 48 hours, confirming that intermittent irradiation had the same sterilization effect on marine bacteria as continuous irradiation. Furthermore, the bacterial colony emergence rate was almost the same under all irradiation conditions, confirming that the same irradiation dose exerts the same growth inhibitory effect.

[0116] [Adhesion Test 1] The test device was installed in the sea by suspending it with a metal chain or rope. The installation location was approximately 2 m underwater. The test device consisted of two test plates (made of vinyl chloride, 60 cm x 60 cm x 5 mm thick, evaluation surface 50 cm x 50 cm) spaced apart, and an underwater LED light (peak wavelength: 407 nm) fixed to a frame spaced apart between the two test plates to irradiate the two test plates with LED light. The distance between the irradiated surface of the underwater LED light and one test plate was approximately 20 cm, and the distance between the irradiated surface of the underwater LED light and the other test plate was approximately 30 cm. As a control, the test device was installed in the sea without an underwater LED light. The test period was approximately one month, from April 14 to May 18, 2022. The test was conducted under the following six conditions.

[0117] Example 1: Underwater LED light (irradiance: 200 Wm －２ (at the center of the evaluation surface of the test plate, distance from the test plate: 30 cm) was used, and irradiation and non-irradiation were switched every second to intermittently irradiate the center of the test plate. Example 2: Underwater LED lamp (irradiance: 400 Wm －２ (at the center of the evaluation surface of the test plate, distance from the test plate: 20 cm) was used, and irradiation and non-irradiation were switched every second to intermittently irradiate the center of the test plate. Comparative Example 1: Underwater LED lamp (irradiance: 200 Wm －２ Comparative Example 2: An underwater LED lamp (irradiance: 400 Wm) was used (at the center of the evaluation surface of the test plate, distance from the test plate: 30 cm) and continuous irradiation was performed toward the center of the test plate. －２ (at the center of the evaluation surface of the test plate, distance from the test plate: 20 cm) and continuously irradiated toward the center of the test plate. Comparative Example 3: No underwater LED lamp was used, and the test plate was left in the sea (test surface on the building side). Comparative Example 4: No underwater LED lamp was used, and the test plate was left in the sea (test surface on the pier side).

[0118] (Test Results) Tables 9 and 10 show the state of organism adhesion to the surface of the test plate in the control group. Table 9 shows the number of attached individuals and colony number analysis results (coverage area for Ascidians and Scutellaria) for each organism attached to the surface of the test plate. Table 10 shows the wet weight analysis results for each organism attached to the surface of the test plate (measured after each organism was removed).

[0119]

[0120]

[0121] In Comparative Examples 3 and 4, a large number of algae, colonial ascidians, amphipod mud tubes, bryozoans, etc. were observed to be attached and covering the entire surface of the test plate. On the other hand, in both Examples 1 and 2 as well as Comparative Examples 1 and 2, no attachment of organisms to the surface of the test plate, including the peripheral area, was observed at least with the naked eye. For this reason, －２ It was confirmed that even when the light was irradiated intermittently by switching between irradiation and non-irradiation every second, adhesion of organisms could be prevented.

[0122] [Adhesion Test 2] The test device shown in Figure 15 was installed by suspending it from a crane underwater near the power plant's water intake. The installation position was adjusted to be 1 m below the lowest water level so that no part of the test device would be exposed above sea level even during low tide. As shown in Figure 15, the test device consisted of test plates P1 and P2 (made of vinyl chloride, 25 cm x 25 cm), as well as an underwater LED irradiation device (peak wavelength: 405 nm, manufactured by Delphys) fixed to frame 7. The distance between the irradiation surface of the underwater LED irradiation device and test plate P2 was approximately 35 cm. Test plate P1 was not irradiated with light and served as a control. Water temperature sensor detection units S were placed in the center of test plates P1 and P2, respectively, and changes in water temperature were recorded using recording unit M. The test period was approximately one month, from August 19 to September 14, 2021. The test was conducted using the following three LED devices as test sections.

[0123] Example 3: Small LED irradiation device (6-lamp type, irradiance setting: (at the position of the test plate surface) 100 Wm －２ A laboratory timer was used to switch between irradiation and non-irradiation every 15 minutes, and intermittent irradiation was performed toward the center of the test plate P2. Comparative Example 5: A small LED irradiation device (6-lamp type, irradiance setting: 100 Wm (at the surface of the test plate) －２Comparative Example 6: A large LED irradiation device (36-lamp type, irradiance setting: 100 Wm (at the surface of the test plate) －２ ) was used and continuously irradiated toward the center of the test panel P2.

[0124] (Test Results) In all of the test plates P2 in Example 3 and Comparative Examples 5 and 6, it was confirmed that adhesion of foreign matter such as attached organisms was significantly suppressed near the center of the test plate P2 where LED light was irradiated, compared to the control test plate P1. On the other hand, adhesion of green algae was confirmed around the center of the test plate P2 where LED light was irradiated, and on the irradiated surface of the irradiation device, in Comparative Examples 5 and 6. Almost no adhesion of the above-mentioned green algae was observed on the test plate P2 in Example 3.

[0125] Figure 16 is an image taken of the foreign matter adhesion state of the test plate P2 of Comparative Example 6 after the adhesion test. Green algae A and fibrous green algae A1 were attached around the central part of the test plate P2 of Comparative Example 6 where the LED light was irradiated. Figure 17 is an image taken of the foreign matter adhesion state of the test plate P2 of Example 3 after the adhesion test. No green algae adhesion was confirmed around the central part of the test plate P2 of Example 3 where the LED light was irradiated. Therefore, it was confirmed that by intermittently irradiating LED light of a predetermined wavelength, not only can the adhesion of foreign matter such as attached organisms be suppressed at the point where the LED light is irradiated on the target object, but also the adhesion of green algae to the area surrounding the irradiated point can be suppressed.

[0126] The water temperature change detected by the water temperature sensor showed an increase of approximately 0.4°C in water temperature compared to the control area in the small LED irradiation device used in Comparative Example 5, and an increase of approximately 0.6°C in water temperature compared to the control area in the large LED irradiation device used in Comparative Example 6. On the other hand, in Example 3, it was confirmed that the water temperature quickly returned to the same level as the control area when irradiation was switched to non-irradiation.

[0127] The small LED irradiation device of Comparative Example 5 after the adhesion test had an irradiance of 100 Wm －２ from 58.2Wm －２ The small LED irradiation device of Comparative Example 6 after the adhesion test had an irradiance of 100 Wm －２ From 22.5Wm－２ When the irradiation surfaces of the LED irradiation devices of Comparative Examples 5 and 6 were cleaned and the irradiance was measured again, the irradiance was reduced to 100 Wm －２ The irradiance recovered to around 100%. Therefore, it is presumed that the decrease in irradiance in Comparative Examples 5 and 6 is due to the adhesion of foreign matter to the irradiated surface. On the other hand, no decrease in irradiance was observed in the small LED irradiation device of Example 3 after the adhesion test. Therefore, it was confirmed that the adhesion of foreign matter to the irradiated surface of the LED irradiation device can be suppressed by intermittently irradiating LED light of a predetermined wavelength.

[0128] [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.

[0129] 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 prepare 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 11. 8 hours after the start of irradiation, each sample was cultured for 48 hours in a constant temperature incubator set at 35 ° C. 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. 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.

[0130]

[0131] (Test Results) Table 11 shows the number of colonies for each sample and the irradiation dose of 1600 Whm －２The sterilization rate for the control group shown in Table 11 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 11, 47 colonies of bacteria and fungi were observed in sample 3, which is the control group. In contrast, one colony was observed in sample 1 and three colonies in sample 2, and the sterilization rate was 100 W / m when the irradiance Y in formula (1) above was 200 W / m. －２ The sterilization rate was 90% or more when the LED light was irradiated with intermittent irradiation of 200 W / m. This result shows that the sterilization rate is also effective against airborne bacteria, fungi, and other adherent organisms that adhere to the surface of airborne structures. －２ It is presumed that by adjusting the concentration as described above, it is possible to almost completely suppress the attachment and / or proliferation of sessile organisms that attach to structures in the air.

[0132] [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 12 was counted to confirm the effect of light irradiation on microorganisms attached to airborne structures.

[0133] 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.

[0134]

[0135] (Test Results) Table 12 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 12 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 12, 13 to 18 bacterial and fungal colonies were observed in the three control areas. In contrast, five colonies were observed in each of samples 4 and 5, and the sterilization rate was 13 to 18 in the control areas when the irradiance Y in formula (1) above was 20 Wm －２ Even when the LED light was irradiated with intermittent irradiation at 20 W / m s, the sterilization rate was 60% or more. From this result, it can be seen that the irradiance Y of 20 W / m s is sufficient for the removal of airborne bacteria, fungi, and other adherent organisms that adhere to the surfaces of airborne structures. －２ It is presumed that by adjusting the amount as described above, it is possible to efficiently suppress the attachment and proliferation of sessile organisms on the target object.

[0136] 1, 1a, 1b, 1c Water quality meter 10 Adhesion propagation suppression device 20, 20a, 20b, 20c, 20d, 20e Irradiation device 22a, 22b, 22c, 22d, 22e Irradiation surface 31, 32, 33, 34, 35, 36, 37, 38 Detection section 5, 5a, 5b, 5c Control section

Claims

1. A method for inhibiting adhesion and / or proliferation of sessile organisms on an object to which the sessile organisms may adhere, the method satisfies the condition represented by the following formula (1) and intermittently irradiates the object with light: X×a / (a+b)≧Y Formula (1) where X is the irradiance of light (Wm －２ ), a is the time when light is irradiated, b is the time when light is not irradiated, and Y is the irradiance of light (Wm －２ ).

2. The method for inhibiting adhesion propagation according to claim 1, wherein Y in formula (1) is 20.

3. The method for inhibiting adhesion propagation according to claim 1, wherein Y in formula (1) is 150.

4. A method for inhibiting adhesion and propagation of microorganisms described in any one of claims 1 to 3, wherein the light irradiated to the object has a peak in the wavelength range of 400 to 430 nm.

5. An adhesion and proliferation inhibition device having an irradiation device that irradiates light onto an object on which adhesion organisms adhere, and a control unit that controls the irradiation device, the control unit controlling the irradiation device so that light is irradiated from the irradiation device to the object intermittently while satisfying the condition expressed by the following formula (1): X×a / (a+b)≧Y Formula (1) where X is the irradiance (Wm －２ ), a is the time when light is irradiated from the irradiation device, b is the time when light is not irradiated from the irradiation device, and Y is the irradiance of light (Wm －２ ).

6. A water quality meter having the attachment propagation inhibition device of claim 4 and a sensor device, wherein the irradiation device irradiates light onto a detection section of the sensor device, the light irradiated from the irradiation device has a peak in a wavelength range of 400 to 430 nm, the sensor device performs a detection operation at each predetermined detection timing, and the control section controls the irradiation device so that light is intermittently irradiated from the irradiation device onto the detection section at each irradiation time other than the predetermined detection timing.

7. The water quality meter according to claim 6, wherein an irradiation surface of the irradiation device is disposed opposite to the detection section.

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