JPH04313388A - Water treatment method - Google Patents

Abstract

PURPOSE:To provide a water treatment method capable of disinfecting and purifying pool water, public bathhouse water, etc., by using a profound sterilization effect due to ozone without chlorine added. CONSTITUTION:Part of pool water 2 is circulated and bromide generating bromine ion is added to the circulating water from a bromide storage tank 26. Ozone generated by a ozone generator 16 is poured into the bromine ion containing circulating water to ozone treat the circulated water and the ozone treated circulating water is again returned to the pool 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a water treatment method for purifying and reusing water in swimming pools, public baths, etc.

0002

2. Description of the Related Art In swimming pools, public baths, and the like, the water is contaminated by the sweat and grime of visitors, so water quality is usually purified using a circulating water treatment device. At this time, substances to be purified in pool water and the like include floating suspended solids, microorganisms such as bacteria, and nitrogen compounds such as ammonia and urea.

[0003] A swimming pool will be explained below as an example. Conventionally, hair and relatively large impurities are removed from pool water using a hair collector, and smaller suspended solids are captured and removed using a filter such as a sand filter. In addition, sterilization of bacteria, decomposition of nitrogen compounds such as ammonia, etc.
This was usually done using a chlorine agent such as sodium hypochlorite solution. Currently, the water quality standards for such pool water are that the residual free chlorine concentration is 0.4 ppm or less, the potassium permanganate consumption is 12 ppm or less, and the transparency is preferably 10 meters or more.

However, in such conventional water treatment methods, although purification of pool water is achieved to some extent, problems such as improvement in transparency and reduction in potassium permanganate consumption cannot be solved. In order to solve these problems, a pool water purification method that includes ozone and activated carbon treatment is proposed in Japanese Patent Application No. 1-237912.

FIG. 6 is a block diagram of the swimming pool water purification device shown in this specification. In this figure, 1 is a pool, 2 is pool water stored in this pool 1, 3 is a water pipe that distributes a part of this pool water 2, 4 is a hair collector connected to this water pipe 3, 5 is a water pump that sucks the pool water 2 through this hair collector 4 and sends it; 6 is a filtration device to which the water that has passed through the hair collector 4 is sent; and 7 is the pool water that has passed through this filtration device 6. Part 2 is a pipe that sends water to the heat exchanger 8, 9 is a pipe that returns the pool water 2 from the heat exchanger 8 to the pool 1, and 10 is a pipe that injects chlorine from a chlorine chemical tank 11 into this pipe 10. This is a chlorine-based drug injection pump. Further, 12 is a circulation pump that sucks a part of the water that has passed through the filtration device 6, and 13 is a flow rate adjustment valve that adjusts the amount of pool water sucked by this circulation pump 12. 1
4 is an activated carbon adsorption device that removes a part of organic components from pool water; 15 is an ozone injection ejector that mixes ozone generated by an ozone generator 16 into the pool water; 18
1 is a gas-liquid separation device in which pool water is sent through a pipe 17, and ozone that has not been absorbed into the pool water is separated from the pool water by an ozone injection ejector 15. This gas-liquid separation device 18 is connected to a waste ozone separation device 19. The remaining ozone gas is released into the atmosphere. 20 is a pipe that returns ozonated pool water to the upstream side of the filtration device 6 via a flow rate adjustment valve 21, and 22 is a water supply pump 5 that transports ozonated pool water through the pipe 20 via a flow rate adjustment valve 23. The piping 24 is a piping for returning the ozonated pool water to the activated carbon-treated pool water via the flow rate adjustment valve 25.

The swimming pool water purification device constructed as described above operates as follows. Pool water in the pool 1 is sucked by a water pump 5, and first, relatively large suspended solids are removed by a capillary collector 4, and then fine particles are captured by a filtration device 6. A portion of the treated water that has passed through the filtration device 6 is heated as necessary in a heat exchanger 8, and then a chlorine-based chemical solution from a chlorine-based chemical tank 11 is added to the treated water in this piping 9 via a chemical injection pump 10. The water is then injected and sent back to pool 1. Further, a part of the treated water that has passed through the filtration device 6 is branched, passes through a circulation pump 12 and a flow rate control valve 13, and is then treated in an activated carbon adsorption device 14. Next, ozone generated by the ozone generator 16 is injected into the ozone gas injection ejector 15 for ozone treatment. After the ozonated pool water passes through the gas-liquid separator 18, the flow rate regulating valve 21,
The water is returned to the water pump 5 and the filtration device 6 via the pipes 20, 22, and 24 via the pipes 23 and 25, and is circulated there. Further, the ozone gas that was not absorbed by the water to be treated at this time is separated by the gas-liquid separator 18, and then separated by the waste ozone decomposer 19.
is decomposed and released into the atmosphere.

[0007]

[Problem to be solved by the invention] In the above water treatment method, ozone has a much higher disinfecting effect than chlorine, and ozone treatment alone can drastically reduce the number of bacteria in treated water, but ozone has a residual effect. Due to the lack of disinfectant, it is difficult to maintain the disinfecting effect for a long time. Therefore, in conventional pool water treatment methods, it was necessary to maintain the final disinfection effect by injecting chlorine. However, when chlorine is used in this way, there are problems such as a strong odor that is irritating to the eyes and nose, acceleration of corrosion of equipment, and generation of harmful organic chlorine compounds such as chloroform.

[0008] This invention was made to solve this problem, and it is possible to disinfect and purify pool water, bath water, etc. by using the strong disinfecting effect of ozone without adding chlorine. The purpose is to provide a water treatment method.

[0009]

[Means for Solving the Problems] The water treatment method of the present invention includes the steps of circulating a part of the stored water, adding a bromine compound that generates bromine ions to this circulating water, and circulating water containing this bromine ion. This system has a process of injecting ozone into the water, and is configured so that the water is returned to the stored water and used as circulating water.

0010

[Action] Ozone treatment in the presence of bromide ions achieves the disinfection effect of ozone itself, and the bromine oxide produced by the reaction between ozone and bromide ions remains, making it possible to maintain the disinfection effect. can.

[0011]

[Example] Example 1. Figure 1 regarding one embodiment of this invention
The explanation will be based on. FIG. 1 shows a swimming pool water purification device according to an embodiment of the present invention. In this figure, 26 is a bromine compound storage tank that stores a solution such as sodium bromide or potassium bromide that generates bromine ions;
Reference numeral 7 denotes an injection pump for injecting the solution in the bromine compound storage tank 26 into the pipe 3. Reference numerals 28 and 29 are flow rate control valves for returning a portion of the ozonated water taken out from the gas-liquid separation device 18 to the heat exchanger 8, and returning the remainder directly to the pool 1 again. The other configurations are almost the same as the conventional example.

Next, the operation of the pool water purification apparatus constructed as described above will be explained. First, the pool water 2 in the pool 1 is sucked by the water pump 5, and the water collector 4
After relatively large suspended solids are removed, bromine ions are injected into the pool water in the pipe 3 from the bromine compound storage tank 26 by the injection pump 27. Then, this pool water is filtered by a filter device 6, where even minute particles are captured. returned to
After passing through the water supply pump 12 and the flow control valve 13, the others are treated with the activated carbon adsorption device 14, and the ozone generated by the ozone generator 16 is injected into the ozone injection ejector 15, which is an ozone gas mixer, for ozone treatment. . After the ozonated pool water passes through the gas-liquid separator 18, part of the pool water is returned to the pool water before ozonation via the flow rate adjustment valve 21, and the remaining part is returned to the pool water after the treatment. A portion of the ozone-treated water is returned to the heat exchanger 8 via the flow control valve 28 and to the pool 1 via the flow control valve 29. Note that in the ozone injection ejector 15, ozone gas that is not absorbed into the treated water is separated in the gas-liquid separator 18, and then decomposed in the waste ozone decomposition device 19 and released into the atmosphere.

In the pool water purification device as described above, the bromide ion concentration in the pool water is 5 to 30 mg.
Approximately /l is appropriate, and if more effects of ozone treatment are expected, the concentration should be set to the low concentration side, and conversely, if more effects of bromine oxide are expected, the concentration should be set to the high concentration side. In other words, when it is desired to increase the effectiveness of ozone, the concentration of bromide ions is lowered in order to reduce the proportion of ozone consumed in reactions with bromide ions and increase the proportion of ozone used in disinfection and reactions with organic substances. On the other hand, there are cases where the effect of bromine oxide is expected, such as when you want to completely decompose ammonia nitrogen and urea, or when you want to increase the residual disinfection effect. Increase the amount of water to create conditions where ozone and bromine ions react to easily produce bromine oxide.

Next, the function of bromide ions contained in this pool water will be explained based on FIGS. 2 to 4. Figure 2
and Figure 3 are the results of investigating how the number of general bacteria decreases with and without ozone treatment in an actual swimming pool,
FIG. 2 shows the relationship between the free residual chlorine concentration and the number of general bacteria when only chlorine disinfection is performed without ozone treatment. The black circles indicate each measured value, and the white circles indicate the logarithmic average of the measured values at each free residual chlorine concentration. Pool water quality standards stipulated by the Ministry of Health and Welfare set the concentration of free residual chlorine at 0.4 mg/l or higher, but even when residual chlorine was present at this concentration or higher, a considerable amount of common bacteria was found. Moreover, FIG. 3 shows the results when ozone treatment was also used. Ozone injection amount is 0.2m
Even though the concentration was set to be quite low in terms of g/l, no common bacteria were observed when residual chlorine was present at 0.1 mg/l or more. In other words, it has become clear that the disinfecting effect of ozone is extremely strong and that it is more advantageous in terms of sterilization and disinfection than treatment with chlorine alone. However, it can be seen from FIGS. 2 and 3 that the chlorine treatment can be omitted if measures are taken to maintain the residual nature of the oxidizing agent after the ozone treatment, since the residual nature of ozone is small.

Next, it was investigated whether the bromide ion concentration changes during circulating water treatment. That is, after adjusting the bromide ion concentration to 50 mg/l, the circulating water was continuously treated with ozone, and the change in the bromide ion concentration over time was investigated. The results are shown in FIG. This result shows that the bromide ion concentration is maintained almost constant over two weeks or more. Therefore, in the pool water treatment method configured as described above, ozone slowly reacts with bromide ions in water,
It maintains strong sterilizing power without volatilizing into the atmosphere from circulating water or adsorbing onto activated carbon. In addition, ozone treatment in the presence of bromine ions not only maintains the disinfection effect, but also has water treatment effects such as decomposing ammonia nitrogen and reducing the pungent odor of halogen compounds.

Note that the amount of water sent by the water pump 12 and subjected to ozone treatment is approximately 10% of the total amount of circulating water sent by the water pump 5, which is sufficiently effective. Of course, this ratio is not fixed, and the ratio of the amount of water sent to the pump 12 may be even higher. Also, pool water 2
By increasing the bromine ion concentration in pump 1, the conversion rate of injected ozone to bromine oxide can be increased.
It is also possible to reduce the water supply ratio to No. 2 from about 10%.

Furthermore, in this embodiment, the ozonated water after passing through the gas-liquid separator 18 is branched into four locations, and the on-off valves 21, 25, 28, and 29 are connected to the four branch points. The pipes are opened and closed in order to arbitrarily select one or more locations among them and branch out. When returning to the upstream side from the filtration device 6, residual oxidizing substances such as hypobromous acid (hereinafter abbreviated as residual oxidant) flow into the filtration device 6, so the filtration layer is brought into an oxidized state and ,
It can maintain the sterilizing and disinfecting effect. Furthermore, when water is returned to the downstream side of the filtration device 6 and upstream of the activated carbon adsorption device 14, water with residual oxidants is returned to the activated carbon adsorption device 14.
This is effective when oxidizing and sterilizing effects are required in the activated carbon adsorption device 14. Furthermore, if the water is returned to the downstream side of the heat exchanger 8, which is downstream of the activated carbon adsorption device 14 and upstream of the heat exchanger 8, the consumption of bromine oxide in the water treatment device is almost eliminated, so that it is returned to the pool. This makes it possible to maintain the highest residual oxidant concentration in the treated water.

Note that, considering the meaning of injection, it is obvious that the injection point of the bromine compound is not limited to the location shown in FIG. 1, but may be anywhere as long as the circulating water flow path. be.

FIG. 5 is a block diagram of a pool water purification device according to another embodiment of the present invention. In this figure, 3
Numerals 0 to 32 are water quality measuring devices, which are sensors that measure, for example, residual oxidant concentration, bromide ion concentration, viable bacteria count, or water quality concentration in pool water. 33-38
is an on-off valve for adjusting the amount of water required for each of the water quality measuring devices 30 to 32, or for operating/stopping the water quality measuring devices 30 to 32. 39 is a data collection device that collects data from the water quality measuring devices 30 to 32, 40 is a control device that controls the ozone generator 16, etc. in accordance with the data of this data collection device 39, and 41 is an on/off valve from the makeup water tank 42. 43
This is a flow meter in which the flow rate of water supplied via the control device 40 is adjusted by the control device 40.

The pool water treatment method in this example is the same as the water treatment method in Example 1 above, in which the amount of bromine compounds added and the amount of ozone generated can be controlled. Explain the method.

First, a method for controlling the amount of bromine compound added will be described. Bromine ion concentration in pool water is measured using water quality meter 3.
0, and this measured value is transmitted to the data acquisition device 39. Then, the control device 40 compares the measured bromine ion concentration with a preset value, and if the actual measured value is lower, drives the chemical injection pump 27 to pump the bromine compound into the bromine compound storage tank 2 until the set concentration is reached. Control to inject more bromine compounds. In addition, the bromide ion concentration is not measured with the water quality measuring device 30, but with the water quality measuring devices 31 and 32.
Similar bromide ion concentration control can be achieved by measuring with . In pool 1, etc., fresh water such as tap water is replenished when the water volume decreases, but since the concentration of bromide ions contained in tap water is usually a trace amount, the concentration of bromide ions will decrease over time if left untreated. , there is no need to take any special measures to reduce the bromide ion concentration.

Further, in this embodiment, a water quality measuring device 30 for measuring the bromide ion concentration was required, but the method of controlling the injection amount according to the amount of makeup water eliminates the need for a water quality measuring device. In this method, makeup water is supplied from the makeup water tank 42 by opening the on-off valve 43. Here, the amount of make-up water is measured by a flow meter 41, and this flow rate data is transmitted to the data collection device 39. Next, the control device 40 controls the amount of the chemical solution (ml
/min) is calculated according to the amount of makeup water (l/min), and the rotational speed of the chemical injection pump 27 is changed.

Next, to control the amount of ozone generated, feedforward control (hereinafter referred to as F) is carried out based on the water quality before treatment.
F control) and feedback control (hereinafter abbreviated as FB control) based on the water quality after treatment.
FF control will be explained. When the oxidant concentration measured by the water quality meter 30 is low or when the bacterial concentration is high, the amount of ozone generated by the ozone generator 16 is increased, and in the opposite case, it is decreased.

In the FB control, when the oxidant concentration measured by the water quality meter 32 is low, the amount of ozone generated is increased, and when the opposite is the case, it is decreased. The bacterial concentration in treated water is almost zero if treatment is carried out normally, so FB
It is not appropriate as a water quality item for control, but is positioned as a water quality indicator for monitoring. Furthermore, if the upstream water quality measuring device 32 is used as the oxidant concentration for FB control instead of the water quality measuring device 32 located most downstream,
The wasted time required for control is reduced. However, from the perspective of controlling the oxidant concentration in the treated water returned to the pool, the oxidant concentration of the water quality measuring device 32 should be
It is more appropriate to use it as an index for B control.

By the way, from the point of safety management, ozone gas concentration sensors (not shown) are installed in the pool room and the machine room housing the water treatment equipment, and if the concentration becomes high, the ozone gas concentration sensor will be removed from the pipes, etc. It is also necessary to consider stopping ozone generation when the accident is determined to be due to a leak.

[0026]

[Effects of the Invention] As described above, the water treatment method according to the present invention achieves the disinfection effect of ozone itself by performing ozone treatment in the presence of bromide ions, and
Since the bromine oxide produced by the reaction between ozone and bromide ions remains, the disinfecting effect can be sustained, so chlorine treatment can be omitted compared to water treatment methods.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a pool water purification device that is an embodiment of the present invention.

FIG. 2 is a diagram showing actually measured data on the relationship between the residual chlorine concentration and the number of general bacteria in pool water that is not subjected to ozone treatment.

FIG. 3 is a diagram showing actually measured data on the relationship between the residual chlorine concentration and the number of general bacteria in ozonated pool water.

FIG. 4 is a diagram showing the results of an experiment examining changes in bromide ion concentration over time.

FIG. 5 is a configuration diagram of a pool water purification device according to another embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional pool water purification device.

[Explanation of symbols]

5 Water pump 15 Ejector for ozone injection 16 Ozone generator 26 Bromine compound storage tank 27 Chemical injection pump

Claims (1)

[Claims] Claim 1: A method comprising the steps of circulating a part of the stored water, adding a bromine compound that generates bromine ions to the circulating water, and injecting ozone into the circulating water, so that the water is recycled again. A water treatment method that uses recycled water by returning it to the water.