JPH10277546A - Bathtub water sterilization method and bathtub water circulation warm bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively sterilizing bacteria belonging to the genus of Legionella of bathtub water in an ultraviolet sterilizing apparatus of bathtub water using an ultraviolet irradiation lamp. SOLUTION: In a method for sterilizing bathtub water by irradiating bathtub water passing through an ultraviolet sterilizing apparatus having an utraviolet irradiation lamp 2 disposed therein and provided with the entrance and exit of bathtub water, the irradiation quantity of ultraviolet rays is set to 1,500-10,000 μW.sec/cm<2> and the Reynolds number of bathtub water flowing through the ultraviolet sterilizing apparatus is set to 6,000-18,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for disinfecting bath water and a bath water circulation hot water bath.

[0002]

2. Description of the Related Art Conventionally, various devices have been devised for sterilizing bath water in a bath water circulating warm water bath in which a circulating pump is operated to circulate bath water. As a method of sterilizing bath water, application of an ultraviolet sterilizer, an ozone generator, a photocatalyst, electrolysis sterilization, addition of a chemical, and the like are well known.

[0003] Similar proposals have been made for cooling towers and the like. In cooling towers and the like, the purpose can be achieved by completely sterilizing the inhabiting fungi. It is required that the bacteria be controlled or sterilized without causing smear.

[0004] Among the above sterilization methods, the sterilization method by ultraviolet irradiation can be carried out relatively inexpensively and is convenient. However, no effective device has been developed for fungi, especially Legionella spp. Is desired. This is because very high sterilization rates are required for effective sterilization.

[0005] For example, tap water quality standards stipulate that general bacteria are 100 CFU / ml or less, but the preferred range of Legionella spp. In cooling tower water supervised by the Ministry of Health is 100 CFU / l.
It is less than 00ml. This is 1 CFU / ml, which shows how difficult the condition is.

[0006] Therefore, assuming that the number of Legionella spp. Present in the bath water is generally 1E05CFU / 100ml (1 x 105CFU / 100ml), a sterilization rate of 99.9% or more is required to reduce the number to less than 1E02CFU / 100ml (100CFU / 100ml). Is required.

That is, the log survival rate Y expressed by the equation (1) is required to be -3 or less. Y = log (viable cell count after treatment [CFU / 100ml] / viable cell count before treatment [CFU / 100ml]) (1)

On the other hand, as a method of purifying bathtub water, at present, physical (mechanical) filtration using a fine filter or a reverse osmosis membrane causes clogging immediately, and the adsorbent is saturated in a short time even by a method using adsorption. And it is said that it cannot be put to practical use.

As a solution to this problem, a filter medium is generally used,
So-called biological purification, which purifies by generating a biofilm while partially performing mechanical filtration, is used.

[0010] It is required that bathtub water be controlled to such an extent that harmful bacteria such as Legionella spp. Do not harm a bather while using a biofilm purifying means in one system. become.

These are the reasons why a reliable method for controlling bacteria while achieving purification of bath water has not been established.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a method for disinfecting bathtub water and a bathtub water circulation warming bath for effectively disinfecting Legionella spp.

[0013]

According to the present invention, there is provided a method for disinfecting bath water according to the present invention, wherein the bath water is passed through an ultraviolet disinfection device equipped with an ultraviolet irradiation lamp and provided with a bath water inlet / outlet. In a method of sterilizing bath water by irradiating ultraviolet rays to the bathtub, the amount of ultraviolet radiation is 1,5.
It is not less than 00 μW · sec / cm ^{2 and not} more than 10,000 μW · sec / cm ² , and the Reynolds number of bath water flowing in the apparatus is not less than 6,000 and not more than 18,000.

Further, the bath tub water circulation warm bath according to the present invention comprises:
Activate the circulating pump to suck bathtub water stored in the bathtub from the suction unit, filter the sucked bathtub water,
In a bath tub water circulating warm water bath in which the bath water is circulated by blowing the bath water again from the blowing unit via a heating device, an ultraviolet sterilizing device, etc., the irradiation amount of the ultraviolet light from the ultraviolet sterilizing device is 1,500 μW · sec / cm ² or more. 2,000μW ・ se
c / cm ² or less, and the Reynolds number of the bath water flowing in the ultraviolet sterilizer is 6,000 or more and 18,000 or less.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an ultraviolet sterilizer for sterilizing bath water. This ultraviolet sterilizer comprises a cylindrical main body 1 and an ultraviolet irradiation lamp 2 arranged inside the main body 1. A bathtub water inlet 3 is formed at the bottom of the main body 1, and a bathtub water outlet 4 is formed at the top of the main body 1. Bathtub water pumped by a circulating pump (not shown) is supplied from the inlet 3 to the inside of the main body 1. Through the outlet port 4. In addition, bathtub water may be made to flow in from the upper part of the main body 1.

The ultraviolet irradiation lamp 2 is connected to a power supply via a lead wire 2a, is housed in a protective tube (quartz tube) 5 made of quartz or the like having a high ultraviolet transmittance, and has a rubber stopper at the top via an O-ring 6. Is fitted to the flange 8 sealed at 7,
The flange 8 is fitted to the main body 1 via an O-ring 9, and the bath water flowing from the inflow port 3 irradiates ultraviolet light emitted from the ultraviolet irradiation lamp 2 between the outer wall of the quartz tube 5 and the inner wall of the main body 1. And rises out of the main body 1 through the outlet 4.

The ultraviolet irradiation lamp 2 may be insulated and the bath water may flow directly around the lamp. The ultraviolet irradiation lamp 2 has various wavelengths such as 210 to 280 nanometers, but a lamp having a peak wavelength of about 254 nanometers can be suitably used.

Also, the amount of UV irradiation by the UV irradiation lamp 2 and the Reynolds number (hereinafter referred to as Re number) of the bath water flowing through the UV sterilizer are extremely important.

The amount of irradiation of ultraviolet rays (illuminance × time) is 1,50
If it is less than 0 μW · sec / cm ² , sterilization of the genus Legionella will be insufficient, and the expected log survival rate Y will not be attained. Preferably, 2,000 μW · sec / cm ² or more and 10,000 μW · sec / cm ²
cm ² or less. However, if it is 10,000 μW · sec / cm ² or more, the ultraviolet irradiation lamp becomes large, and the apparatus becomes large in size.

The log survival rate Y is also affected by the Re number of bath water flowing through the ultraviolet sterilizer. If the Re number is small, the sterilizing effect cannot be sufficiently increased. It has been found that the Re number needs to be 6,000 or more.

This is because bacteria in the bath tub water when exposed to ultraviolet rays in the range of laminar or weak turbulent flow,
This is considered to be because the relative positional relationship of the solid matter such as dirt contained in the bathtub water does not change significantly, and the sterilizing effect by ultraviolet rays becomes insufficient. However, if the Re number is increased, the pump for pumping the bathtub water becomes large, which is not practical as a home bath water circulating warm water bath, and the irradiation amount of ultraviolet rays is proportional to the time of passing through the main body. When the value is large, the irradiation amount is small.
000 or less is preferable.

Next, the results of experiments on the sterilizing effect of the ultraviolet sterilizer will be described.

In this experiment, about 300 L of hot water was put in a 400 L bath, and a family of five people was equipped with an ultraviolet sterilizer in bath water that had been bathed for 1.5 months, and the log survival rate Y was examined.
About 9E05CFU / Legionella spp.
100 ml was found. FIG. 2 shows the number of Legionella spp. In the bathtub water before passing through the ultraviolet sterilizer and entering the bathtub while changing the irradiation amount while keeping the Re number constant. FIG. 5 is a log survival rate table obtained by calculating a log survival rate Y from the number of Legionella bacteria in bath water immediately after passing through an ultraviolet sterilizer.

FIG. 3 shows an ultraviolet sterilizer having various irradiation doses and Re numbers, which is attached to bathtubs of six families in which 2 to 6 people take a bath, and water is taken after the bathing is completed and about 10 hours later. FIG. 4 is a table showing the logarithmic survival rate showing the results of experiments for measuring Legionella spp., And FIG. 4 is a graph showing the results.

FIG. 2 shows that even when the Re number satisfies the condition (6,000 or more), the irradiation amount of the ultraviolet light is
(00 μW · sec / cm ² or more), the predetermined log survival rate Y (−3 or less) cannot be achieved. From FIGS. 3 and 4, the Re number is 6,000 or more. At the same time, the irradiation amount of ultraviolet light is 1,500 μW · sec / cm ²
If it is above, it was confirmed that a log survival rate Y of −3 or less was obtained.

In each of the above experiments, purification was sufficiently performed by the filtration device, and no turbidity occurred in the bath water, and the turbidity was 1 or less. Turbidity is also said to occur when bacteria are very abundant, but usually, using a circulating warm bath, the bacteria are not as enriched as turbidity occurs. Rather, most of them occur when the dirt (proteins, fats, and possibly soap etc. that come off the skin) brought in by bathing is insufficiently purified, and this purification is carried out by bacteria and other organisms in the filtration device. Purification was generally performed, and it was confirmed that even in a state where Legionella bacteria were sterilized at a predetermined logarithmic survival rate Y, biological purification could be performed without killing bacteria and the like in the filtration device.

The irradiation amount E is ultraviolet energy: a value W (W) obtained by measuring the irradiation amount of the used ultraviolet lamp in the air at D3 below. Some 50-100 cm
The value calculated from the measured value was used. Residence time in the apparatus: T (S) Lamp diameter: D1 (cm) Quartz tube diameter: D2 (cm) Outer diameter of water channel: D3 (cm) If the cross section is not circular, use the equivalent diameter. Arc length of ultraviolet lamp: L (cm) Attenuation rate by quartz tube: a = 0.85 Attenuation rate per cm in pure water: b = 0.98 Calculated by formula (1). E = T × {W × a × b ^{(D3-D2) / 2} {πD3 × (L + D3)} ・ ・ (1)

The Re number is the flow rate Q of the water channel around the ramp.
(M ³ / SEC) divided by the average cross-sectional area S (m ² ) The average flow rate U Specific gravity: ρ A value of water at 40 ° C. of 992 kg / m ³ was used. Viscosity: μ Value of water at 40 ° C. 0.653 × 10 ⁻³ Pa · S was used. From Equation (2). Re = (D3 -D2) × 10 ^-2 Uρ / μ (2)

Next, an example of a bath tub water circulation hot water bath to which the above-described sterilization method is applied will be described. As shown in FIG. 5, the bathtub water circulation warm bath has a circulation pump 20 and a filtration device 2.
1, heating device 23, ultraviolet sterilization device 22, and control device 2
A hot water bath body A having a suction unit 4;
Circulating pump 20
The bathtub water is sucked up from the suction unit 25 disposed in the bathtub 27 and sent to the filtering device 21 to purify the bathtub water. This is a general bathtub water circulation hot water bath configured to blow out from the blowout unit 26 disposed inside the bathtub 27 again.

However, in the case of a bath provided with a device capable of adjusting the temperature by reheating, etc., the heating device can be omitted.

Although the arrangement order of the above devices can be devised depending on the configuration, the ultraviolet sterilizer 22 is preferably installed downstream of the filtration device 21 (purification tube) as shown in FIG. In addition, a display device 28 such as a liquid crystal display for displaying an operation state and setting a temperature is arranged in the bathtub water circulation hot water bath together with a control device 24 for controlling the circulation pump 20 and the heater 23a of the heating device 23. It is common.

The ultraviolet sterilizer 22 is preferably provided downstream of the filter 21 in the case of a bathtub water circulation hot water bath. This is because when installed upstream of the filtration device 21, most of the bacteria in the bathtub water sent to the filter medium 21a are sterilized, but the bacteria of the genus Legionella brought into the bathtub water by the separation from the filter medium 21a are sterilized. Because they cannot do it.

It is more preferable that a sterilizer having a sterilizing power lower than that of the sterilizer 22 installed upstream and downstream of the filter 21 is provided, and sterilization is performed before and after the filter 21.

The circulating pump 20 used is 200 to
In the case of a 300 L home tub, one having a capacity of 10 to 50 L / min can be suitably used. The circulating pump 20 is used not only for circulating the bath water but also for mixing the bath water in the bath tub. If the capacity is too small, the mixing of the bath water in the bath tub becomes insufficient and the ultraviolet water sterilizer 22 is not used. The amount of water sent is reduced, resulting in a lower bactericidal effect. On the other hand, if it is too large, the residence time (passing time) in the ultraviolet sterilizer 22 is shortened, and the ultraviolet sterilizer 22 having a large capacity is impractically necessary. Therefore, in the case of a home tub, 15-30 L / min is suitable.

Further, the ultraviolet sterilizer 22 can be attached to a bath tub water circulation bath having no sterilizer or a sterilizer with insufficient sterilizing effect even with the sterilizer. It can be attached with a screw or the like, but it can also be used easily with a suction cup attached to a bathtub water circulation warm bath. At this time, the power of the ultraviolet sterilizer 22 may be supplied from the bathtub water circulation hot water bath or may be supplied independently.

According to the bath tub water circulating warm bath having the above-mentioned structure, the circulation pump is operated to make the Re number of the bath water flowing in the ultraviolet sterilizer 22 not less than 6,000 and the irradiation amount of the ultraviolet light not less than 1,500. By doing so, as shown in FIG. 4, the logarithmic survival rate of Legionella spp. In the bath water can be set to a predetermined value (-3 or less), and a comfortable bathing life can be achieved.

In the above-mentioned bath water circulating warm bath, purification by the filtration device 21 was sufficiently performed, the bath water was not turbid, and the turbidity was 1 or less. This means that even in a state where the Legionella bacterium is sterilized at a predetermined logarithmic survival rate Y, it can be determined that biological purification has been performed without killing the bacteria and the like in the filtration device.

[0038]

According to the first aspect of the present invention, by optimizing the irradiation amount of the ultraviolet irradiation and specifying the state of the bath water flow, the bath water passing through the ultraviolet sterilizer is effectively sterilized. can do.

According to the second aspect of the present invention, bathtub water can be purified by biological filtration without preserving microorganisms in the filter medium and causing almost no turbidity in the bathtub, and effectively preventing Legionella bacteria. It can be sterilized, can perform microbial sanitary sterilization, and can provide a comfortable bathing life.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part of an ultraviolet sterilizer.

FIG. 2 is a table showing logarithmic survival rates measured by changing the amount of ultraviolet irradiation while keeping the Re number constant.

FIG. 3 is a table showing a log survival rate measured by changing the amount of ultraviolet irradiation and the number of Re.

FIG. 4 is a graph showing the relationship between the amount of ultraviolet irradiation, the Re number, and the logarithmic survival rate.

FIG. 5 is a block diagram showing a configuration of a bath tub water circulation hot water bath;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Ultraviolet irradiation lamp 3 Inlet 4 Outlet 5 Protective tube (quartz tube) 22 Ultraviolet sterilizer

Claims (2)

[Claims] 1. A method of sterilizing bath water by irradiating bath water with an ultraviolet ray and irradiating ultraviolet light to a bath water passing through an ultraviolet sterilizer having a bath water inlet and outlet provided therein, wherein the irradiation amount of the ultraviolet light is 1, 500μW · sec / cm ² or more 10,
000 μW · sec / cm ² or less, and the Reynolds number of the bath water flowing in the ultraviolet sterilizer is 6,000 or more and 1
A method for disinfecting bathtub water, which is not more than 8,000. 2. A circulating pump is operated to suck bathtub water stored in the bathtub from a suction unit, and the sucked bathtub water is blown out from a blowout unit to a bathtub again through a filtering device, a heating device, an ultraviolet sterilizing device and the like. In a bath water circulating warm water bath for circulating bath water, the ultraviolet irradiation amount of the ultraviolet sterilizer is 1,500 μW ·
A bath tub water circulation hot water bath having a sec / cm ² or more and 10,000 μW · sec / cm ² or less, and a Reynolds number of the bath water flowing through the ultraviolet sterilizer is 6,000 or more and 18,000 or less.