Method for sterilizing legionella bacteria in hot water discharged from faucet

Abstract

To provide a method for sterilizing Legionella bacteria in hot water discharged from a faucet, which can be implemented simply for each individual faucet.SOLUTION: In the method for sterilizing Legionella bacteria in hot water discharged from a faucet, at least the following steps are carried out: (A) an ultraviolet sterilization treatment step in which hot water discharged from the faucet is subjected to ultraviolet sterilization treatment, (B) a faucet interior treatment step in which a chlorine agent is applied to a biofilm adhering to the inside of the faucet, and (C) a faucet end treatment step in which a chlorine agent is applied to a biofilm adhering to a foam cap, a spray plate, or a shower head attached to the faucet.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for sterilizing Legionella bacteria in hot and cold water discharged from a faucet fixture, which can be easily implemented for each individual faucet fixture.

Background Art

[0002] Legionella bacteria are aerobic Gram-negative bacilli, which are originally environmental bacteria that inhabit natural soil and fresh water. However, it has been clarified that they also inhabit artificial water systems such as cooling tower cooling water, pool water, and hot spring facility circulating water with a high probability. When aerosol in a water system inhabited by Legionella bacteria is inhaled, airway infection with Legionella bacteria occurs, causing Legionnaires' disease such as Legionella pneumonia. Since 1980 when a Legionnaires' disease patient was first diagnosed positive in Japan, the number of reported patients has been increasing year by year.

[0003] Since no case of person-to-person infection of Legionnaires' disease has been reported, appropriate sanitation management of artificial water systems is regarded as important for preventing Legionnaires' disease. For example, regarding hot water supply facilities, in the "Maintenance and Management of Sanitary Environments in Buildings" by the Ministry of Health, Labour and Welfare in Non-Patent Document 1, it is described that for a central hot water supply system that circulates hot water, the hot water temperature should be maintained at 60°C or higher in the hot water storage tank and 55°C or higher even at the end of the hot water faucet.

[0004] As a conventional measure against Legionella bacteria, for example, the water supply system is managed by the free residual chlorine concentration of the water supply at each faucet end, and the hot water supply system is heat-sterilized by high-temperature flushing that discharges hot water at 60°C or higher for about 30 minutes every day.

[0005] Especially in facilities such as hospitals and hotels where many mixing faucets are installed, high-temperature flushing can be time-consuming for adjusting the water temperature, and there are risks such as burns, making it a difficult operation. In addition, there are problems such as the pressure of water and light heat costs, and the softening and leakage of PVC drainage pipes due to hot water.

[0006] As another countermeasure method, there is a method of sterilizing the entire hot water supply equipment with chemicals. However, in hospitals, hotels, etc., since there are no holidays, it is often difficult to implement because the hot water supply equipment cannot be stopped.

[0007] Also, in locations where the frequency of faucet use is low, biofilms adhere to the inside of the faucet fixtures and Legionella bacteria are released into the initial flowing water. As a method for preventing biofilm adhesion, it is necessary to maintain the residual chlorine concentration by heat treatment or frequent flushing, etc., which is time-consuming.

[0008] Patent Document 1 describes a method of sterilizing bacteria and viruses present in the water discharged from a mixing faucet by a plasma generator attached to the mixing faucet. However, this method can only sterilize bacteria and viruses present in the water, and cannot sterilize Legionella bacteria in the biofilm established inside the mixing faucet. Therefore, it is not possible to prevent Legionella bacteria from being released from the biofilm into the water.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] Therefore, an object of the present invention is to provide a method for sterilizing Legionella bacteria in the hot water discharged from a faucet fixture, which is simple, can be implemented for individual faucet fixtures, and solves the above-mentioned problems.

Means for Solving the Problems

[0011] The method for sterilizing Legionella bacteria in the hot water discharged from the faucet fixture according to the present invention is 〔1〕 The following steps (A) to (C), that is, (A) A UV sterilization treatment step of performing UV sterilization treatment on the hot and cold water discharged from the faucet appliance; (B) An internal faucet appliance treatment step of performing a chlorine agent treatment on the biofilm adhering to the inside of the faucet appliance; (C) A faucet appliance end portion treatment step of performing a chlorine agent treatment on the biofilm adhering to the foam cap or the water sprinkler plate or the shower head attached to the end of the faucet appliance; A method for sterilizing Legionella bacteria in the hot water discharged from a faucet appliance having the following steps: In the UV sterilization treatment step (A), the UV sterilization treatment device for performing the UV sterilization treatment is installed at the root portion of the hose portion of the faucet appliance, and UV sterilization of the hot and cold water discharged from the faucet appliance is performed. The internal faucet appliance treatment step (B) includes the following steps (b1) to (b3), that is: (b1) A tube insertion step of inserting a chemical injection tube to the root portion of the hose portion of the faucet appliance; (b2) A faucet appliance chemical injection holding step of filling the downstream of the UV sterilization device of the faucet appliance with the chlorine agent injected from the chemical injection tube and holding the chlorine agent; (b3) An internal faucet appliance water washing step of washing the inside of the faucet appliance holding the chlorine agent and flushing away the chlorine agent; The faucet appliance end portion treatment step (C) includes the following steps (c1) and (c2), that is: (c1) A faucet appliance end portion immersion step of immersing the foam cap or the water sprinkler plate or the shower head in the chlorine agent; (c2) A faucet appliance end portion water washing step of washing the foam cap or the water sprinkler plate or the shower head immersed in the chlorine agent; A method for sterilizing Legionella bacteria in the hot water discharged from a faucet appliance, characterized by having the above steps.

[0012] [2] In the internal faucet appliance treatment step (B) and the faucet appliance end portion treatment step (C), Free chlorine concentration (%) × Holding time or immersion time of chlorine agent (minutes) The free chlorine CT value represented by is 0.003%·min or more, and the free chlorine concentration is 0.0001% or more, the retention time or immersion time of the chlorine agent is 1 minute or more and 100 minutes or less A method for sterilizing Legionella bacteria in hot water discharged from the faucet fixture according to [1], characterized by the above.

[0013] 〔3〕 In the internal treatment step (B) of the faucet fixture and the end treatment step (C) of the faucet fixture Combined chlorine CT value represented by combined chlorine concentration (%) × retention time or immersion time of chlorine agent (min) is 0.0005%·min or more, and the combined chlorine concentration is 0.00005% or more, the retention time or immersion time of the chlorine agent is 1 minute or more and 100 minutes or less A method for sterilizing Legionella bacteria in hot water discharged from the faucet fixture according to [1], characterized by the above.

[0014] 〔4〕 The chlorine agent used in the internal treatment step (B) of the faucet fixture and the end treatment step (C) of the faucet fixture is One or more selected from sodium hypochlorite, sodium dichloroisocyanurate, and monochloramine. A method for sterilizing Legionella bacteria in hot water discharged from the faucet fixture according to [1], characterized by the above.

Effect of the Invention

[0015] According to the present invention, it is possible to easily sterilize Legionella bacteria in hot water discharged from a faucet fixture for each individual faucet fixture.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 1 or FIG. 2. Note that the present invention is not limited to the embodiments described below.

[0018] The method for sterilizing Legionella bacteria in the hot and cold water discharged from the faucet device according to the embodiment of the present invention sterilizes Legionella bacteria released from the biofilm adhering to the pipe upstream of the faucet device and sterilizes the biofilm inside the faucet device.

[0019] Generally, a "faucet device" is a general term for devices having a function of stopping the supply of hot water or cold water, and refers to a device equipped with a valve attached to the end of a water supply pipe or a hot water supply pipe. In particular, the "faucet device" in the present invention refers to a device including a valve 9 for adjusting the stop of hot water or cold water, a spout 2A or a shower head 2B, and a hose part (a connecting hose 5A connected to the spout 2A or a connecting hose 5B connected to the shower head 2B). Also, the method for adjusting the amount of discharged water is not limited, and it may be either a faucet device that discharges hot and cold water manually mixed or a faucet device that discharges hot and cold water automatically mixed. And the type of water discharged from the faucet device is not limited either, and it may be either a single faucet that can stop the supply of either water or hot water, or a mixing faucet that can stop the supply of both water and hot water and can adjust the temperature of the discharged water. Examples of the faucet devices 1A and 1B in the present invention are shown in FIGS. 1 and 2, but it is not intended to limit the type of faucet device. Also, the "hot and cold water" in the present invention refers to either hot water or cold water, and it is not intended to limit the temperature of the water.

[0020] [UV Sterilization Treatment Step] An ultraviolet sterilization device 6 is installed in the hose part of the faucet fixture. The hose part in the present invention refers to the connecting hose 5A connected to the spout 2A from the upstream side, or the connecting hose 5B connected to the shower head 2B from the upstream side. In the case of a mixing faucet, these hoses are connected to the automatic mixing part 12A and the manual mixing part 12B of the water supply W1 and the hot water supply W2 from the downstream side. The automatic mixing part 12A and the manual mixing part 12B may be simply referred to as the mixing part, or may be referred to as the mixing part as their general term.

[0021] In the branch pipe that branches from the main pipe of the water supply and hot water supply system (not shown in the figure) toward the faucet fixture, there are many water stagnation parts where it is difficult to maintain the water temperature and the residual chlorine concentration, and it is easy for biofilms to form and Legionella bacteria to multiply. Regarding the Legionella bacteria in the biofilm attached to the branch pipe, conventionally, measures have been taken such as maintaining the residual chlorine concentration at the end of the water supply pipe by flowing a large amount of water added with a chlorine agent, or heat sterilization by flowing a large amount of high-temperature hot water, but it is difficult to sterilize completely. That is, the water supply W1 and the hot water supply W2 contaminated with Legionella bacteria released from the biofilm attached to the branch pipe are supplied to the faucet fixture connected to the end of the branch pipe. Therefore, by using the ultraviolet sterilization device 6 in the present invention to sterilize the Legionella bacteria derived from the biofilm attached to the branch pipe mixed in the water supply W1 and the hot water supply W2, the Legionella bacteria in the hot water discharged from the faucet fixture can be surely sterilized.

[0022] The installation position of the ultraviolet sterilization device 6 in the present invention is preferably connected near the root of the hose part, that is, from the upstream end of the connecting hose 5A connected to the spout 2A or the connecting hose 5B connected to the shower head 2B. By installing at this position, the automatic mixing part 12A, the manual mixing part 12B located upstream of the ultraviolet sterilization device 6, and the Legionella bacteria derived from the biofilm attached to the branch pipe are sterilized by ultraviolet irradiation, and the possibility that the hot water discharged from the faucet fixture is contaminated by the Legionella bacteria derived from the water supply W1 and the hot water supply W2 is reduced.

[0023] The ultraviolet lamp used in the ultraviolet sterilization device 6 is not limited, and a mercury lamp, a metal halide lamp, a gallium lamp, a sodium lamp, an LED lamp, etc. can be used. Since the LED lamp is smaller than other ultraviolet lamps, it is preferable because there are fewer restrictions on the installation location. In addition, since it consumes less power, has a long lifespan, and does not require lamp cooling, the running cost can be suppressed. Also, since the rise of the irradiation dose is fast, it is preferable because a sufficient sterilization effect can be obtained even if ultraviolet irradiation is started simultaneously when water flows out. When using an LED lamp type ultraviolet sterilization device in the present invention, when a person uses it, that is, ultraviolet rays may be irradiated only when water is flowing, and the irradiation timing is not limited. For example, depending on the presence or absence of a person in front of the faucet fixture, the operation of the ultraviolet sterilization device 6 is controlled by the control unit 8 using the human sensor 7, that is, the on / off of the ultraviolet lamp is controlled, so that power saving and the lifespan of the LED lamp can be extended, which is particularly suitable. In particular, when the faucet fixture 1A is an automatic mixing faucet (Fig. 1) in which the human sensor 10 controls the water stop valve 9 by the control unit 11, the human sensor 10 simultaneously controls the water stop and the on / off of ultraviolet irradiation so that ultraviolet rays are irradiated only when water is flowing, which is more preferable because of good efficiency.

[0024] [Faucet Fixture Internal Processing Step] Remove the foam cap 3A or the water diffuser plate 3B at the water outlet 4 of the faucet fixture, and insert the chemical injection tube from the water outlet 4 of the water washing fixture. Or, when the end part of the faucet fixture is the shower head 2B, instead of the water diffuser plate 3B, remove the shower head 2B and insert the chemical injection tube from the end of the connecting hose 5B connected to the shower head 2B. That is, after removing the end part of the faucet fixture, insert the chemical injection tube from the end side of the faucet fixture. At this time, it is preferable to insert the tip of the chemical injection tube up to the root of the hose part of the faucet fixture, that is, near the outlet of the ultraviolet sterilization device 6. Thereby, since the biofilm attached downstream of the ultraviolet sterilization device 6 and the stagnant water can be sterilized, the possibility that bacteria including Legionella bacteria are contained in the hot water discharged from the faucet fixture can be more surely reduced.

[0025] Inject a chlorine agent from the tube for drug injection, hold it for a certain period of time with the downstream of the ultraviolet sterilizer 6 in the faucet appliance filled with the chlorine agent, and then open the faucet and wash it away with water. As the part filled with the chlorine agent, since it includes a hose part where biofilm is likely to adhere, Legionella bacteria can be effectively sterilized.

[0026] Here, the chlorine agent in the present invention is not limited, but (a) substances that generate free chlorine in water, such as hypochlorous acid, monochloroisocyanuric acid, dichloroisocyanuric acid, trichloroisocyanuric acid, or salts thereof (for example, sodium salt, potassium salt, calcium salt, etc.), preferably sodium hypochlorite and sodium dichloroisocyanurate, and / or a combination of two or more substances that generate free chlorine, (b) combined chlorine, such as monochloramine, dichloramine, trichloramine, and N-chlorosulfamate, preferably monochloramine, and / or a combination of two or more substances that generate combined chlorine, (c) other conventionally known chlorine agents can be used.

[0027] In addition to the chlorine agent, other cleaning agents, such as hydrogen peroxide and sodium percarbonate, which are conventionally known cleaning agents, can be used in combination.

[0028] The combined chlorine of the chlorine agent (b) is preferable because it is more likely to penetrate into biofilms and amoebas compared to the free chlorine of the chlorine agent (a), and thus a relatively high sterilization effect can be obtained against Legionella bacteria taken up by biofilms and amoebas. Also, when metal is used in the part of the faucet appliance filled with the chlorine agent (for example, inside the hose, spout, shower head, etc.), it is preferable to use the combined chlorine of the chlorine agent (b) because it is less likely to corrode the piping than free chlorine.

[0029] The part of the faucet appliance to be treated with a chlorine agent, that is, the connecting hose 5A connected to the spout 2A downstream of the ultraviolet sterilizer 6 or the connecting hose 5B connected to the shower head 2B, and the chlorine agent used when the spout 2A or the shower head 2B is made of a material other than metal, sodium hypochlorite is preferable from the viewpoints of price and availability.

[0030] It is advisable to fill the downstream of the ultraviolet sterilizer 6 of the faucet appliance with a chlorine agent, measure the overflowed water with a chlorine concentration test paper or the like, and check whether the chlorine agent fills the inside of the faucet appliance surely.

[0031] Thereafter, keep the downstream of the ultraviolet sterilizer 6 of the faucet appliance filled with a chlorine agent. At this time, when the active ingredient of the chlorine agent is free chlorine, the free chlorine concentration is preferably 0.0001% or more. When the concentration is less than 0.0001%, it tends to be difficult to sterilize Legionella bacteria. Also, even if the free chlorine concentration is higher than 12%, the bactericidal effect on Legionella bacteria can be obtained. However, since the concentration of commercially available sodium hypochlorite is usually 12% or less, it is difficult to obtain a chlorine agent with a higher free chlorine concentration, and the cost-effectiveness deteriorates. Further preferably, it is 0.001% or more, particularly preferably 0.01% or more, and most preferably 0.1% or more, so that the free chlorine concentration can be maintained at an effective concentration or more until the end of the sterilization treatment.

[0032] Also, the free chlorine CT value represented by (free chlorine concentration (%)) × (holding / immersion time of the chlorine agent (minutes)) is preferably 0.003%·min or more. When the free chlorine CT value (%·min) is 0.003%·min or more, it is easy to sterilize Legionella bacteria in the biofilm, and a sufficient sterilization effect can be obtained for a faucet fixture that is sterilized once or more a week. Furthermore, more preferably, the free chlorine CT value (%·min) is 0.01%·min or more, particularly preferably 0.1%·min or more, and most preferably 1%·min or more, so that a high sterilization effect can be obtained against Legionella bacteria present in a relatively thick biofilm adhering to a faucet fixture with insufficient management. When managing the sterilization operation by the free chlorine CT value, the holding time or immersion time is usually 1 minute or more and 100 minutes or less. Since it is difficult for the chlorine agent to penetrate into the biofilm, if the holding time or immersion time is shorter than 1 minute, it tends to be difficult to sterilize the inside of the biofilm, and if it is longer than 100 minutes, the work efficiency decreases. Also, more preferably, by setting it to 3 minutes or more and 60 minutes or less, Legionella bacteria in the faucet fixture can be efficiently sterilized.

[0033] When the active ingredient of the chlorine agent is combined chlorine, the combined chlorine concentration is preferably 0.00005% or more. When the concentration is less than 0.00005%, it tends to be difficult to sterilize Legionella bacteria. Also, even if it is higher than 0.5%, a sterilization effect on Legionella bacteria can be obtained, but it is difficult to prepare combined chlorine at that concentration. Furthermore, more preferably, by setting it to 0.0001% or more, particularly preferably 0.001% or more, and most preferably 0.1% or more, the combined chlorine concentration can be maintained at an effective concentration or more until the end of the sterilization treatment.

[0034] It is preferable that the combined chlorine CT value represented by (combined chlorine concentration (%)) × (holding / immersion time of chlorine agent (minutes)) is 0.0005%·min or more. When the combined chlorine CT value (%·min) is 0.0005%·min or more, it is easy to kill Legionella bacteria in the biofilm, and sufficient sterilization effect can be obtained for a faucet fixture that is sterilized more than once a week. Further, more preferably, the combined chlorine CT value (%·min) is 0.001%·min or more, particularly preferably the combined chlorine CT value (%·min) is 0.01%·min or more, and most preferably 0.1%·min or more, so that a high sterilization effect can be obtained against Legionella bacteria present in a relatively thick biofilm adhering to a faucet fixture with insufficient management. When managing the sterilization operation by the combined chlorine CT value, the holding time or immersion time is usually 1 minute or more and 100 minutes or less. Although combined chlorine easily penetrates into the biofilm, if the holding time or immersion time is shorter than 1 minute, it tends to be difficult to sterilize the inside of the biofilm, and if it is longer than 100 minutes, the work efficiency decreases. Further, more preferably, by setting it to 3 minutes or more and 60 minutes or less, Legionella bacteria in the faucet fixture can be efficiently sterilized.

[0035] [Faucet Fixture End Treatment Step] The foam cap 3A or the water sprinkler plate 3B or the shower head 2B removed from the faucet fixture is immersed in a chlorine agent for a certain period of time and then washed away with water.

[0036] The chlorine agent used for the chlorine agent treatment of the foam cap 3A or the water sprinkler plate 3B or the shower head 2B can be preferably used in the same free chlorine concentration range or combined chlorine concentration range, and the free chlorine CT value range or combined chlorine CT value range as the chlorine agent used in the faucet fixture internal treatment step.

[0037] The time for immersing the foam cap 3A, or the water sprinkling plate 3B, or the shower head 2B in the chlorine agent is usually 1 minute or more and 100 minutes or less. Since it is difficult for the chlorine agent to penetrate into the biofilm, if the immersion time is shorter than 1 minute, it tends to be difficult to sterilize the inside of the biofilm attached to the foam cap 3A, or the water sprinkling plate 3B, or the shower head 2B. If the immersion time is longer than 100 minutes, the working efficiency decreases. Further, preferably it is 60 minutes or less, more preferably 30 minutes or less, so that the sterilization working efficiency is good and it does not take much time.

[0038] According to the method for sterilizing Legionella bacteria in the faucet fixture of the present invention, Legionella bacteria existing downstream of the ultraviolet sterilization device inside the faucet fixture and at the end of the faucet fixture are sterilized with a chlorine agent. Further, by sterilizing the water flowing from upstream with ultraviolet irradiation by the ultraviolet sterilization device, the Legionella bacteria in the hot and cold water discharged from the faucet fixture can be surely reduced. Further, by installing an ultraviolet sterilization device inside the faucet fixture that has been made aseptic with a chlorine agent, the Legionella bacteria derived from the biofilm attached to the branch pipe are sterilized by the ultraviolet sterilization device, thereby cutting off the supply of Legionella bacteria from the water supply and hot water supply pipe to the inside of the faucet fixture. It is difficult for Legionella bacteria to propagate inside the faucet fixture and at the end of the faucet fixture, and the sterilization effect by the chlorine agent continues.

Examples

[0039] Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention.

[0040] [Generation of Biofilm] Using a biofilm generation device that circulates tap water kept at 42°C, biofilm A (biofilm 1 cm 2 with 3.2×10 3 CFU of Legionella bacteria per), or biofilm B (biofilm 1 cm 2 with 1.6×10 6CFU) were attached. The blade hoses with the biofilms attached were cut into pieces with a length of 3 cm and used in Examples 1 to 19 and Comparative Examples 1 and 2 described below.

[0041] <Examples 1 to 19, Comparative Example 1, Comparative Example 2> The 3-cm-long blade hoses with Biofilm A or Biofilm B attached were immersed in 1 L of 0.0002% sodium hypochlorite (Examples 1 to 3, abbreviated: 0.0002% NaClO), 0.001% sodium hypochlorite (Example 4, abbreviated: 0.001% NaClO), 0.002% sodium hypochlorite (Example 5, abbreviated: 0.002% NaClO), 0.01% sodium hypochlorite (Example 6, abbreviated: 0.01% NaClO), 0.12% sodium hypochlorite (Example 7, abbreviated: 0.12% NaClO), 1% sodium hypochlorite (Example 8, abbreviated: 1% NaClO), 12% sodium hypochlorite (Example 9, abbreviated: 12% NaClO), 0.00005% monochloramine (Examples 10 and 11), 0.0001% monochloramine (Examples 12 and 13), 0.0003% monochloramine (Example 14), 0.001% monochloramine (Example 15), 0.002% monochloramine (Example 16), 0.005% monochloramine (Examples 17 and 18), 0.5% monochloramine (Example 19), 1% hydrogen peroxide (Comparative Example 1), 0.5% sodium percarbonate (Comparative Example 2, abbreviated: 0.5% Na2CO3·1.5H2O2), and stirred at 300 rpm using a magnetic stirrer. After any elapsed time, the blade hoses were taken out, the attached chemicals were neutralized with 1% sodium sulfite, and then rinsed with pure water. The biofilm on the inner wall of the blade hose was wiped off using a wipe test kit, and the viable count of Legionella bacteria in the biofilm was measured to confirm the bactericidal effect against Legionella bacteria present in the biofilm. The test results are shown in Table 1. (The numerical values showing the results of the viable count measurement indicate the percentage (%) of Legionella bacteria killed by the bactericidal treatment relative to the number of Legionella bacteria per 1 cm of the biofilm before sterilization.) 2 per of the Legionella bacteria in the biofilm before sterilization, the percentage (%) of Legionella bacteria killed by the bactericidal treatment is shown.)

[0042]

Table 1

[0043] From the results of Examples 1 to 9, when sodium hypochlorite was used as the chlorine agent, sterilization was effective at a free chlorine concentration of 0.0001% or more, and particularly effective at a free chlorine concentration of 0.001% or more. Also, if the free chlorine CT value was 0.003%·min or more, there was a sufficient sterilization effect, and particularly a high sterilization effect was confirmed at a free chlorine CT value of 0.004%·min or more. From the results of Examples 10 to 19, when monochloramine was used as the chlorine agent, sterilization was effective at a combined chlorine concentration of 0.00005% or more, and particularly effective at a combined chlorine concentration of 0.0001% or more. Also, if the combined chlorine CT value was 0.0005%·min or more, there was a sufficient sterilization effect, and particularly a high sterilization effect was confirmed at a combined chlorine CT of 0.001%·min or more. Since combined chlorine (monochloramine) has a higher penetration power and higher persistence against biofilms than free chlorine, it is considered that a sterilization effect could be obtained at a lower concentration and a lower CT value. Also, in biofilm B in which there were 10 6 CFU / cm 2 or more Legionella bacteria present, when sodium hypochlorite was used as the chlorine agent, from the results of Examples 6 to 9, a sufficient sterilization effect was obtained under the conditions of a free chlorine concentration of 0.01% or more and a free chlorine CT value of 0.1%·min or more. Also, when monochloramine was used as the chlorine agent, from the results of Examples 15 to 19, a sufficient sterilization effect was obtained under the conditions of a combined chlorine concentration of 0.001% or more and a combined chlorine CT value of 0.01%·min or more. In Comparative Example 1 using hydrogen peroxide and Comparative Example 2 using sodium percarbonate, the biofilm peeled off from the surface of the blade hose due to the foaming of oxygen, respectively, but the sterilization effect was not sufficient.

[0044] Between the downstream of the mixing section of the water supply and hot water supply of a certain faucet fixture A (Automatic faucet Aqua Auto TENA41AW manufactured by TOTO Ltd.: water discharge rate 2.4 L / min) and the connecting hose connected to the spout, an ultraviolet sterilizer (ULR24A manufactured by Stanley Electric Co., Ltd.: ultraviolet irradiation dose 20 mJ / cm 2An ultraviolet sterilizer was installed, and disinfection treatment with a chlorine agent downstream of the ultraviolet sterilizer was carried out, that is, chlorine agent treatment inside the faucet fixture A and chlorine agent treatment of the foam cap attached to the end of the faucet fixture A were carried out. Sodium hypochlorite at 1% was used as the chlorine agent, and the holding time and immersion time were set to 10 minutes. The above biofilms (Examples 1 to 19, Comparative Example 1, Comparative Example 2) were immersed in tap water A collected from the faucet fixture A that had been disinfected with a chlorine agent. This tap water A was regularly replaced with newly collected tap water A at a frequency of three or more times a day, and after one week had passed, the biofilm was subjected to an inspection for Legionella bacteria.

[0045] As a result, Legionella bacteria were detected from the biofilms of Comparative Example 1 and Comparative Example 2, but were hardly detected from the biofilms of Examples 1 to 19.

[0046] <Example 20, Comparative Example 3> Disinfection was carried out on two faucet fixtures installed in the toilet of a certain facility, and the disinfection effect was evaluated. Among the two washbasins, between the downstream of the mixing section of the water supply and hot water supply of the faucet fixture installed on one side (TOTO LTD. Automatic faucet Aqua Auto TENA41AW: water discharge rate 2.4 L / min) and the connecting hose connected to the spout, an ultraviolet sterilizer (Stanley Electric Co., Ltd. ULR24A: ultraviolet irradiation dose 20 mJ / cm 2 ) was installed, and it was set so that ultraviolet rays were irradiated when a person came by means of a human presence sensor for controlling the ultraviolet sterilizer (Example 20). A test was carried out on the faucet fixture installed on the other side without installing an ultraviolet sterilizer (Comparative Example 3).

[0047] The foam cap was removed from the faucet fixture, immersed in 1% sodium hypochlorite for 10 minutes, and then thoroughly rinsed with tap water (Example 20, Comparative Example 3).

[0048] A PTFE tube was attached to a syringe filled with 1% sodium hypochlorite, and the tip of the tube was inserted from the water outlet of the faucet fixture into the faucet fixture (Example 20, Comparative Example 3). It was confirmed that the tip of the tube reached the ultraviolet sterilizer (Example 20) or the valve that controls the water shut-off (Comparative Example 3), and 1% sodium hypochlorite in the syringe was injected (Example 20, Comparative Example 3). The liquid overflowing from the water outlet of the faucet fixture was measured with a chlorine concentration test paper, and it was confirmed that the chlorine concentration was about the same as that of 1% sodium hypochlorite (Example 20, Comparative Example 3). After holding the inside of the faucet fixture filled with 1% sodium hypochlorite for 10 minutes, the inside of the faucet fixture was thoroughly rinsed with tap water (Example 20, Comparative Example 3).

[0049] Taking the sterilization operation implementation date as day 0, water discharged from two faucet fixtures was periodically sampled and subjected to a bacteria test (Example 20, Comparative Example 3). During this test period, the use of the two faucet fixtures was not restricted, and water discharge was freely carried out by the toilet users. The water sampled after about 12 hours had passed since the last use of the faucet was used as the initial water, and it was compared with the water sampled after sufficient flushing. The test results are shown in Table 2 and Table 3. (The results of heterotrophic bacteria measurement and the numerical values indicating general bacteria measurement show the number of colonies of heterotrophic bacteria or general bacteria detected per 1 mL of the test water by culture (CFU / mL). Also, the numerical values indicating the test results of Legionella bacteria show the gene amount of Legionella bacteria obtained by PCR test (copy / 100 mL). Also, "-" indicates that the measurement was not carried out.)

[0050]

Table 2

[0051]

Table 3

[0052] As a result of the tests, in both Example 20 and Comparative Example 3, the number of heterotrophic bacteria, the number of Legionella genus bacteria genes, and the number of general bacteria decreased due to the sterilization treatment on the 0th day. However, viable heterotrophic bacteria were detected in Comparative Example 3, suggesting that bacteria from the water supply pipe upstream of the faucet fixture were mixed into the water. In Example 20, since the bacteria from the water supply pipe upstream of the faucet fixture were sterilized by ultraviolet irradiation, no heterotrophic bacteria or general bacteria were detected.

[0053] On the 1st day and the 6th day, heterotrophic bacteria were detected in the initial flow water of both Example 20 and Comparative Example 3. However, the detected number of heterotrophic bacteria in Example 20 was suppressed to be at least two digits less than that in Comparative Example 3. Furthermore, although many general bacteria were detected in Comparative Example 3, almost no general bacteria were detected in Example 20, and a significant sterilization effect was confirmed. From this, it is considered that the sterilization treatment with a chlorine agent and the ultraviolet treatment made the water environment retained in the faucet fixture an environment where bacteria including Legionella genus bacteria are less likely to reproduce, and the number of bacteria mixed into the discharged water decreased. This is presumably because the number of viable bacteria brought into the discharged water from the water supply pipe located upstream of the faucet fixture was greatly suppressed by the ultraviolet sterilization of the discharged water. From the increase in the detected number of heterotrophic bacteria and general bacteria in Comparative Example 3, it is suspected that a biofilm has started to adhere again inside the faucet fixture. However, in Example 20, the installation of the ultraviolet sterilization device made this tendency small, and it is speculated that the adhesion of the biofilm or the reproduction of bacteria in the biofilm was greatly suppressed.

[0054] After the sterilization implementation date, the detected numbers of Legionella genus bacteria and heterotrophic bacteria in the water sampled after flushing showed non-detection or a low level in Example 20, but an increasing tendency was observed in Comparative Example 3. From this result, it can be seen that the sterilization effect in Example 20 particularly persists.

[0055] As a preliminary test, sterilization of the inside of the faucet fixture and the foam cap was not performed, and only ultraviolet sterilization treatment of the discharged water was carried out, but the sterilization effect was small. Also, from the results before and after sterilization (day 0) in Comparative Example 3, since the detected number of heterotrophic bacteria decreased from 600 CFU / mL to 13 CFU / mL due to sterilization, it is presumed that the contribution of bacteria present in the biofilm attached inside the faucet fixture is greater than that in the biofilm attached upstream of the faucet fixture to the number of viable bacteria present in the hot water discharged from the faucet fixture. Therefore, according to the present invention, in addition to sterilizing the inside of the faucet fixture and the end part of the faucet fixture, by performing ultraviolet sterilization of the discharged water, a more reliable and highly persistent sterilization effect on Legionella bacteria in the hot water discharged from the faucet fixture can be obtained.

Explanation of Signs

[0056] 1A Faucet fixture 1B Faucet fixture 2A Spout 2B Shower head 3A Foam cap 3B Watering plate 4 Water discharge port 5A Connecting hose 5B Connecting hose 6 Ultraviolet sterilization device 7 Human sensor 8 Control unit 9 Valve 10 Human sensor 11 Control unit 12A Automatic mixing unit 12B Manual mixing unit W1 Water supply W2 Hot water supply

Claims

1. The following steps (A) to (C), namely, (A) An ultraviolet sterilization treatment step of performing ultraviolet sterilization treatment on the hot and cold water discharged from the faucet fixture, (B) An internal treatment step of the faucet fixture for performing a chlorine agent treatment on the biofilm adhering to the inside of the faucet fixture, (C) An end part treatment step of the faucet fixture for performing a chlorine agent treatment on the biofilm adhering to the foam cap or the water diffuser plate or the shower head attached to the end of the faucet fixture, A method for sterilizing Legionella bacteria in the hot and cold water discharged from a faucet fixture having the above steps, The ultraviolet sterilization treatment device for performing the ultraviolet sterilization treatment in the ultraviolet sterilization treatment step (A) is installed at the root part of the hose part of the faucet fixture, and performs ultraviolet sterilization on the hot and cold water discharged from the faucet fixture. The internal treatment step (B) of the faucet fixture includes the following steps (b1) to (b3), namely, (b1) A tube insertion step of inserting a chemical injection tube to the root part of the hose part of the faucet fixture, (b2) A chemical injection holding step of the faucet fixture in which the downstream of the ultraviolet sterilization device of the faucet fixture is filled with a chlorine agent injected from the chemical injection tube and the chlorine agent is held, (b3) An internal water washing step of the faucet fixture in which the faucet fixture holding the chlorine agent is washed with water to wash away the chlorine agent, The end part treatment step (C) of the faucet fixture includes the following steps (c1) and (c2), namely, (c1) An end part immersion step of the faucet fixture in which the foam cap or the water diffuser plate or the shower head is immersed in the chlorine agent, (c2) An end part water washing step of the faucet fixture in which the foam cap or the water diffuser plate or the shower head immersed in the chlorine agent is washed with water, characterized by having A method for sterilizing Legionella bacteria in the hot and cold water discharged from a faucet fixture.

2. In the internal treatment step (B) of the faucet fixture and the end part treatment step (C) of the faucet fixture Free chlorine concentration (%) × Holding time or immersion time of chlorine agent (minutes) The free chlorine CT value represented by is 0.003%·min or more, and the free chlorine concentration is 0.0001% or more,[[]] the holding time or immersion time of the chlorine agent is 1 minute or more and 100 minutes or less A method for sterilizing Legionella bacteria in hot water discharged from the faucet fixture according to claim 1, characterized by the above.

3. In the internal treatment step (B) of the faucet fixture and the end treatment step (C) of the faucet fixture Combined chlorine concentration (%) × Holding time or immersion time of chlorine agent (minutes) The combined chlorine CT value represented by is 0.0005%·min or more, and the combined chlorine concentration is 0.00005% or more,[[]] the holding time or immersion time of the chlorine agent is 1 minute or more and 100 minutes or less A method for sterilizing Legionella bacteria in hot water discharged from the faucet fixture according to claim 1, characterized by the above.

4. The chlorine agent used in the internal treatment step (B) of the faucet fixture and the end treatment step (C) of the faucet fixture is one or more selected from sodium hypochlorite, sodium dichloroisocyanurate, and monochloramine A method for sterilizing Legionella bacteria in hot water discharged from the faucet fixture according to claim 1, characterized by the above.

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