JP2003080265A - Method and equipment for disinfecting water by circulating water in water storage tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for disinfecting water by circulating the water in water storage tank and which surely exhibits a disinfecting effect with a small amount of a disinfecting agent, is safe, has no adverse effect, is environmentally friend, is inexpensive and produces less resistant bacteria. SOLUTION: This disinfecting method of the circulation type relates to a circulating line system of the water to clean the water from the water storage tank and to return the water again to the water storage tank and more specifically comprises providing a disinfecting chamber in the inside of the circulating line system, adjusting the pH and hypochlorite concentration of the water in the disinfecting chamber, adjusting the pH and hypochlorite concentration of the water in the disinfecting chamber by adjusting the volume of the circulating water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for disinfecting water in a water tank by a circulation method.

[0002]

2. Description of the Related Art In recent years, mass infection in pools has become a problem. Chlorine disinfectants are often used to disinfect pool water. Chlorine (chlorine dioxide, chlorine, chlorine hypochlorite or its salt) is difficult to handle because chlorine gas may be generated if used incorrectly. It is also said that residual chlorine and chlorine compounds cause atopy. However, chlorine-based compounds have a broad antibacterial spectrum and are effective against many harmful bacteria, and resistant bacteria are less likely to form, which is preferable. However, there is a tendency to increase the amount of chlorine-based disinfectant added in order to improve the disinfecting effect, and the above problems are likely to occur. Further, although hypochlorous acid has a great disinfecting effect, it has a drawback that it is easily decomposed by light, heat, organic substances and the like.

[0003]

[Problems to be Solved by the Invention] A method of circulating disinfection of water in a water tank, which reliably exhibits a sufficient disinfecting effect with a small amount of disinfectant, that is, the disinfecting effect is large, safe, and less harmful. It is an object of the present invention to provide a disinfection method that has a low environmental load, is inexpensive, and causes less resistant bacteria. That is, it is an object of the present invention to provide a disinfection method capable of independently controlling the hypochlorous acid concentration of water in a disinfection tank and the residual chlorine concentration of water in a water storage tank and exhibiting a sufficient disinfection effect without any harmful effect. Another object of the present invention is to provide a water tank and a water circulation line system that can suppress the growth of Escherichia coli and the like even if the residual chlorine concentration of water is lowered.

[0004]

The present invention relates to a water circulation line system for purifying water from a water storage tank and returning it to the water storage tank again. More specifically, a disinfection tank is provided in the circulation line system, The present invention relates to a method of adjusting the residual chlorine concentration and pH of water in a water storage tank by adjusting the pH of water in the disinfection tank and the amount of a chlorine-based disinfectant and adjusting the amount of circulating water.

In a water circulation line system for purifying water from a water storage tank and returning it to the water storage tank, a disinfection tank is provided in the line system, and a container for supplying a chlorine-based disinfectant is connected to the disinfection tank, Further, the residual chlorine concentration is measured in the water storage tank and / or the line system, and the supply amount of the hypochlorous acid aqueous solution and / or the circulating water amount of the line system is adjusted according to the residual chlorine concentration. This is the circulating disinfection method for water. Further, it is preferable that a container of a pH adjusting agent is connected to the disinfecting tank to adjust the pH of the water in the disinfecting tank.

The chlorine-based disinfectant used in the present invention is
Examples of the aqueous solution include chlorine, chlorine dioxide, so-called chlorinated powder (salaria powder, high-grade coconut powder) and hypochlorous acid (sodium hypochlorite, aqueous solution containing potassium hypochlorite, etc.). Among them, an aqueous solution containing hypochlorous acid is preferable, and a sodium hypochlorite aqueous solution is more preferable.
The volume of the disinfection tank is 1/10000 to 10000 of the volume of the water storage tank.
1/30 is preferable, and 1/1000 to 1/100 is more preferable. The hypochlorous acid concentration of water in the disinfection tank is preferably 20 to 1000 ppm in terms of effective chlorine concentration, and 30 to 800
ppm is more preferable, and 50 to 500 ppm is even more preferable. The pH of the water in the disinfection tank is preferably 2.0 to 10, more preferably 4 to 8, and even more preferably 5 to 7.5. The pH of the water in the disinfection tank is preferably 0.5 to 3.0 lower than the pH of the water in the water storage tank, and more preferably 0.5 to 2.0 lower. Due to this difference in pH, sufficient disinfection (sterilization) can be performed in the disinfection tank, and the water tank can maintain conditions that do not adversely affect the human body.

It is preferable that the water in the disinfection tank is shielded from ultraviolet rays. The temperature of the water in the disinfection tank is 10-40
C is preferable, and 15 to 30C is more preferable, and 20 to 28
° C is more preferable.

The pH adjuster is preferably an acid, and examples of the acid include inorganic acids such as hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, acetic acid, formic acid, citric acid, tartaric acid, aliphatic carboxylic acids, and the like. Organic acids are mentioned. Of these, hydrochloric acid, acetic acid and citric acid are preferred. A pH buffering agent can also be used.
Any pH buffering agent can be preferably used as long as it has the effect of reducing fluctuations in pH.
As an example, for example, the 2nd volume 3 of the 4th edition of the revised edition of the Chemical Handbook (September 1993, Maruzen Publishing Co., Ltd.)
Any of those described on pages 36 to 339 can be preferably used.

PH and residual chlorine concentration are measured in a water storage tank and / or a circulation line, and the amount of circulating water is adjusted according to the measured values. These measurement points are preferably inside the water tank, but may be anywhere near the water tank. When the residual chlorine concentration is high, it is preferable to reduce the circulating water amount, and when the residual chlorine concentration is low, it is preferable to increase the circulating water amount. pH
If the value is high, the amount of acid added to the disinfection tank can be increased. However, the pH in the disinfectant tank should be within the preferred range described above. Also, the pH of the water storage tank can be adjusted by adjusting the amount of circulating water in the line system. It is preferable that the detection unit for measuring the concentration of residual chlorine is a sensor including a noble metal working electrode, a noble metal counter electrode, an electrolyte aqueous solution, and an ion selective diaphragm.

The circulating water disinfection device for a water tank of the present invention is
Circulation line system including water tank and disinfection tank, pH measuring device, residual chlorine concentration measuring device, and feedback of the measured values to adjust the amount of pH regulator and / or chlorine disinfectant and / or the amount of circulating water. It is desirable to have a circuit. It is desirable to measure the effective chlorine concentration and pH in the disinfection tank, and it is desirable to measure the residual chlorine concentration and pH value in the other water circulation lines (including the water storage tank). The residual chlorine concentration and pH value other than the disinfectant tank may be measured at any place where it seems to have the same measured value as the water in the water tank, but the process of discharging water from the water tank and / or the water tank to the disinfectant tank Is preferred. When making a circulation system that does not pass through the disinfectant tank, it is also preferable to measure on that line.

In addition to a disinfection tank, a pH adjusting agent charging facility can be provided, and an arbitrary alkali or acid can be charged to adjust the pH.
It is also preferable to adjust If the optimum pH value for disinfecting the water in the disinfectant tank and the optimum pH value for the water in the water tank (for example, the water quality standard value of the swimming pool) are not compatible, use this method to optimize the water in the disinfectant tank and the water tank. The pH value can be set to. The water circulation line system has a water circulation line independent of a line passing through the disinfecting tank and / or a water circulating line bypassing the disinfecting tank and / or passing through the disinfecting tank, and the amount of circulating water passing through the disinfecting tank is adjusted by the feedback circuit, and It is also preferable that the water circulation line that bypasses the disinfection tank and / or the independent water circulation line sets the circulating water amount independently thereof. P of the water
It is preferable to feed back the measured values of H, residual chlorine concentration, and available chlorine concentration to adjust the addition amount of pH adjusting agent and / or chlorine-based disinfectant and / or the circulating water amount from a remote location (remote control). .
This makes it possible to manage a large number of water tanks at once and eliminate the need for specialized personnel in each water tank.

It is also possible to provide a water circulation line that does not pass through the disinfection tank. In this case, water can be circulated in order to filter water and remove hair and dust regardless of pH and residual chlorine concentration. This water circulation line may be partly common with or independent of the water circulation line passing through the disinfection tank.

The residual chlorine concentration in the water tank is 0.1 to 1 mg
/ L is preferable, 0.3 to 0.8 mg / L is more preferable, and 0.3 to 0.6 mg / L is further preferable.

Regarding the pH adjusting agent and the chlorine-based disinfectant, it is desirable to add the pH adjusting agent first and then the chlorine-based disinfectant into the disinfecting tank. In particular, when adding a hypochlorous acid (salt) aqueous solution, it is necessary to locally adjust the pH so as not to become 3 or less. This is because chlorine gas is generated when the pH becomes 3 or less. The pH of the water circulated in the disinfectant tank is almost the same as the pH measured at the place where the water storage tank and the circulation line system are located. Therefore this pH
If the value is within the specified range, the amount of pH adjuster necessary to correct the pH change due to the addition of disinfectant such as sodium hypochlorite is estimated in advance and added, and the mixture is stirred in the disinfectant tank and uniformly mixed. It is desirable to add a disinfectant when it becomes.
According to this method, generation of chlorine gas can be prevented. Hypochlorous acid in an aqueous solution of hypochlorous acid (salt) is heat, light,
It is unstable to oxidants, so put it in a closed container and protect it from light.
It is preferable to store at low temperature.

The circulation line system of the present invention is an adsorption tank containing an adsorbent such as a sand filter, a hair collector, and activated carbon. Japanese Patent Laid-Open No. 8-
It is also possible to use a COD component removal system using a low-pressure type synthetic polymer reverse osmosis filtration membrane described in 267061, and a reducing adsorbent for reducing or adsorbing ozone and chlorine.

The working electrode of the detection unit for measuring the concentration of residual chlorine in water is preferably platinum or gold, more preferably platinum. The counter electrode is preferably silver or gold, more preferably silver. It consists of an aqueous electrolyte solution and an ion-selective diaphragm. The pH (hydrogen ion concentration) may be measured with a normal pH meter.

It is preferable that the water storage tank and / or the circulation line system of the present invention has an antibacterial agent containing at least one kind of divalent metals consisting of Mn, Fe, Co, Ni, Cu and Zn ions. In the past, even if sterilization and sterilization were once performed, the bacterium usually grew thereafter. In particular,
In a place where a large number of people enter such as a pool, it is important to suppress the growth of E. coli. In order to suppress this proliferation, there is a tendency to add a large amount of chlorine-based bactericide, which causes problems such as atopy. On the other hand, conventionally used organic antibacterial agents have a drawback that the antibacterial action does not last, and silver antibacterial agents also have a drawback that the antibacterial effect is rapidly lost because they react with chloride ions. The present inventor has found that the following antibacterial agent does not lose its antibacterial effect even when used in combination with a chlorine-based disinfectant, and is extremely suitable for imparting antibacterial properties to such a water tank system.

The antibacterial agent used in the present invention is a divalent metal M.
An oxide of n, Fe, Co, Ni, Cu and Zn ions is desirable. The content of the divalent metal in these oxides is preferably 2 to 80% by weight. 20
More preferably, it is -80% by weight.

These oxides are represented by the following formulas (1) to (5)
Those represented by are preferably used. ^{_{N 2+ 1-x M 2+ x}} O · (Al 2 O 3) k (SiO 2) g (1) ( wherein, N represents shows the Mg or Ca, M is Mn, F
at least one divalent metal ion selected from the group consisting of e, Co, Ni, Cu and Zn, and x is 0.0
Indicates a number in the range of 01 <x <0.8, and k is 0.0 ≦ k <
The number in the range of 0.8 is shown, and g is the number in the range of 0.0 ≦ g <0.8. Mg _1-y M ²⁺ _y (OH) ₂ (2) (where M is the same as formula (1) and y is 0.001 ≦
y indicates a number in the range of y ≦ 0.9) (M ²⁺ O) _z · Al ₂ O ₃ · nSiO ₂ · aH ₂ O (3) (where M is the same as formula (1), z , n and a
Represents a number that satisfies the following ranges. 0 <z ≦ 2
4 <n <30,0 ≦ a) Ca _1-w M ²⁺ _w (OH) ₂ (4) (where M is the same as in formula (1), and w is 0.005 <
indicates the number of ranges of ^{_{w <0.4) L 1+ 2y N}} 2+ 1-x-2y M 2+ x O · (Al 2 O 3) k (SiO 2) g (5) ( wherein, L is Li, Na, K, Rb, Cs are shown, N is Mg and / or Ca, M is Mn, Fe, C
at least one of transition metal ions selected from the group consisting of o, Ni, Cu and Zn, and x is 0.00 ≦ x
Indicates a number in the range of <0.8, and y is 0.00 ≦ y <0.05
, K is a number in the range 0.0 ≦ k <0.8, and g is a number in the range 0.0 ≦ g <0.8) (the above formula (1) to In (5), M is Cu or Zn
Is more preferable, and Zn is further preferable. Mg in the formulas (1) and (5) is more preferable.

Examples of preferable oxides of the present invention are shown below, but the present invention is not limited thereto. The numbers in parentheses are BET surface area (m ² / g) and particle size D 50% (μ
m) represents the content (% by weight) of Zn or Cu. (A-1) Zn _0.14 Mg _0.86 O (15, 0.5, 19.
9) (A-2) Zn _0.05 Ca _0.95 O (12, 0.6, 19.
9) (A-3) Zn _0.40 Mg _0.60 O · (Al ₂ O ₃ ).
_0.50 (60, 0.3, 24.3) (A-4) ZnO. (Al ₂ O ₃ ) _0.04 (30, 0.
4, 76.5) (A-5) Cu _0.05 Ca _0.95 O (18, 0.2, 5.
7) (A-6) Cu _0.14 Mg _0.86 O (30, 0.3, 19.
4) (A-7) (CuO) _0.4 · Al ₂ O ₃ · (SiO ₂ ) ₁₆ ·
5H ₂ O (15, 0.2, 1.3) (A-8) ZnO. (K ₂ O) _0.005 (120,
0.3, 80, 0.48) (A-9) ZnO. (Na ₂ O) _0.005 (90,
0.3, 80, 0.01) (A-10) (CuO) _0.4 · Al ₂ O ₃ · (SiO ₂ ) ₁₆
・ 5H ₂ O ・ (Na ₂ O) _0.005 (15, 0.8,
2.3, 0.02)

Further, for example, a surface treatment agent selected from the group consisting of higher fatty acids, anionic surfactants, phosphoric acid esters, coupling agents (silane series, titanate series, aluminum series) and esters of polyhydric alcohols and fatty acids. You may use after surface-treating with at least 1 type of.

The water storage tank of the present invention may be any as long as it can store water, and examples thereof include a swimming pool and a bath.

[0023]

Example 1 A water tank of 25000 liters was connected with a disinfectant tank of 100 liters by piping, and a container of an aqueous hydrochloric acid solution and a container of an aqueous solution of sodium hypochlorite were connected by a pipe to the water disinfectant tank and the disinfectant tank. A water circulation line system including The pH of the water in the disinfectant tank was controlled to 6.0, and the effective chlorine concentration was set to 100 ppm. Initially, Escherichia coli exceeding the standard value was detected in the water in the water tank. 100 liters of water was circulated and stopped once. At this point, the pH of the water in the disinfection tank was controlled to 6.5 and the effective chlorine concentration was set to 100 ppm. After 5 minutes, circulate 100 liters again and stop,
The pH of the water in the disinfection tank was controlled to 6.5, and the effective chlorine concentration was set to 100 ppm. This was repeated 50 times.
The water in the water tank was tested for E. coli but it was below the detection limit. The residual chlorine concentration is 0.4 mg / liter, pH
Was 6.5. After that, when the residual chlorine concentration decreased, the intermittent time of the circulating water was shortened to increase the circulating water amount, and conversely, when the residual chlorine concentration increased, the intermittent time was lengthened to reduce the circulating water amount. If the pH of the water in the water storage tank becomes lower than 6.0, raise the pH of the water in the disinfection tank to 7.0.
On the other hand, when it exceeded 8.0, a feedback circuit was set up so that the pH of the water in the disinfection tank was lowered to 5.0, and operation was carried out for 8 hours. The residual chlorine concentration in the water in the water storage tank was 0.4 mg / liter, and the pH was kept at 6.5, and Escherichia coli was not generated.

[0024]

Example 2 A porcelain plate containing 3 wt% of the antibacterial agent A-4 of the present invention on the wall surface of the water tank of Example 1 in contact with water was laid, and the residual chlorine concentration of water in the water tank was set to 0. 2 mg /
Example 1 was repeated except that the volume was changed to liters, and similar results were obtained.

[Example 3] Example 2 except that a basket packed with zeolite particles carrying an antibacterial agent A-4 was placed instead of the ceramic plate.
Was repeated and similar results were obtained.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 1/50 C02F 1/50 531U 540 540B 540F 550 550L A01N 59/08 A01N 59/08 A 59/16 59 / 16 G01N 27/26 361 G01N 27/26 361F 27/416 27/46 353Z 351K

Claims (20)

[Claims] 1. In a water circulation line system for purifying water from a water storage tank and returning it to the water storage tank, a disinfection tank is provided in the line system, and a container for supplying a chlorine-based disinfectant is connected to the disinfection tank. The residual chlorine concentration of water in the water tank and / or the line system is measured, and the supply amount of the chlorine-based disinfectant and / or the circulating water amount of the line system is adjusted according to the residual chlorine concentration. A method of circulating water disinfection in a water tank, which is characterized in that 2. The disinfecting method according to claim 1, wherein the chlorine-based disinfectant is an aqueous solution containing hypochlorous acid. 3. The disinfection method according to claim 1, wherein the circulation method is an intermittent circulation method of water. 4. The disinfecting method according to claim 1, wherein a container of a pH adjusting agent is connected to the disinfecting tank to adjust the pH of water in the disinfecting tank. 5. The pH of water is measured in the water storage tank and / or the line system, and the supply amount of the pH adjusting agent and / or the circulating water amount of the line system is adjusted according to the measured pH value. The disinfecting method according to any one of claims 1 to 4. 6. The hypochlorous acid concentration of water in the disinfection tank is 20 to 1000 ppm in effective chlorine concentration and the pH is 2.0 to 1.
It is 0, The disinfection method in any one of Claims 1-5. 7. The disinfecting method according to claim 1, wherein the water in the disinfecting tank is shielded from ultraviolet rays and the temperature is in the range of 10 to 40 ° C. 8. The disinfecting method according to claim 4, wherein the pH adjusting agent is an acid. 9. The pH adjusting agent contains at least one kind of inorganic acids such as hydrochloric acid, phosphoric acid, sulfuric acid and nitric acid, and organic acids such as acetic acid, formic acid, citric acid and tartaric acid. The disinfection method according to any one of 4 to 8. 10. The disinfection method according to claim 4, wherein the pH adjusting agent is a pH buffering agent. 11. The residual chlorine concentration of water in the water storage tank is 0.1.
~ 1 mg / liter.
The disinfection method according to any one of 10. 12. A detection unit for measuring the concentration of residual chlorine,
The disinfection method according to any one of claims 1 to 11, which is a sensor comprising a noble metal working electrode, a noble metal counter electrode, an aqueous electrolyte solution, and an ion-selective diaphragm. 13. The pH of water in the disinfection tank is lower than the pH of water in the water storage tank by 0.5 or more.
The disinfection method according to any one of 2. 14. A circulation type disinfection device for water in a water tank, which uses the disinfection method according to claim 1.
Circulation line system including water tank and disinfection tank, pH measuring device, residual chlorine concentration measuring device, and feedback of the measured values to adjust the amount of pH regulator and / or chlorine disinfectant and / or the amount of circulating water. A circulation type disinfection device for water in a water storage tank, which has a circuit. 15. The water circulation line system has a water circulation line independent from a line passing through the disinfecting tank and a water circulating line bypassing the disinfecting tank and / or passing through the disinfecting tank, and the amount of circulating water passing through the disinfecting tank in the feedback circuit. 15. The water of the reservoir as claimed in claim 14, characterized in that the water circulation line which regulates the and / or bypasses the disinfection tank and / or is independent of the water circulation line sets the circulation water quantity independently of the circulation water quantity passing through the disinfection tank. Circulation type disinfection device. 16. The water circulating disinfection device for a water storage tank according to claim 14, further comprising a device for introducing a pH adjusting agent for water, in addition to the disinfection tank. 17. A method for controlling the addition amount of a pH adjusting agent and / or a chlorine-based disinfectant and / or the circulating water amount by feeding back the measured values of pH, residual chlorine concentration and effective chlorine concentration of said water, The water circulation disinfection device for a water storage tank according to any one of claims 14 to 16, wherein the operation is performed from a remote place. 18. A circulating water disinfection device for a water tank, which uses the disinfection method according to any one of claims 1 to 13 and the apparatus according to any one of claims 14 to 17, wherein the water tank and / or the water tank is used. The circulation line system consists of Mn, Fe, Co,
A circulating water disinfection device for a water storage tank, which contains an antibacterial agent containing at least one kind of divalent metal composed of Ni, Cu and Zn ions. 19. The water circulating disinfection device for a water storage tank according to claim 18, wherein the antibacterial agent contains Cu and / or Zn ions. 20. The water circulating disinfection device for a water tank according to claim 19, wherein the antibacterial agent is made of a solid solution of an oxide containing Cu and / or Zn ions.