JPH0263510A - Method of cleaning pool water - Google Patents

Abstract

PURPOSE:To maintain pool water at the water quality at which the water is transparent and has no sticky feel by guiding part of the treated water treated with a filter machine to a precision filter line having a hollow system filter machine and a reverse osmosis membrane device, treating the water and returning this water as highly purified water to a pool. CONSTITUTION:The pool water in the pool 1 is treated in a coarse cleaning treatment line A having a hair catcher 2 and the filter machine 3 and is returned to the pool 1. Part of the treated water treated by the filter machine 3 is guided to the precision filter line B having the hollow system filter machine 7 contg. a porous hollow system filter membrane and the reverse osmosis membrane device 9 and is treated therein. The treated water is returned as the highly cleaned water to the pool. The economical execution of the high- grade cleaning treatment of the pool water is executed simply by adding the relatively simple additional equipment to the device. The pool water is thus maintained at the good water quality at which the water is transparent and has no sticky feel.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a purification method for maintaining the quality of pool water in a swimming pool at a good level through economical treatment.

[Conventional technology]

Regarding the quality of pool water in swimming pools, standards are set by law and are required to maintain a constant water quality. However, the reality is that the quality of the water varies greatly depending on the number of pool users and the pool water purification system adopted by each pool.

If you go to a pool where the pool water is not purified enough, you can get eye diseases or get so-called pool fever. Also, to prevent this from happening, if you use stronger chlorine disinfection,
Problems arose in that swimmers were unable to open their eyes underwater and the color of their hair and swimsuits was bleached.

Further, although large amounts of suspended solids contained in pool water are not necessarily harmful, swimmers experience sensory discomfort due to decreased water clarity.

Conventional pool water purification treatment generally involves introducing a portion of the pool water to pool water circulation treatment equipment, first removing hair with a hair catcher, then treating it with various filters, and then sterilizing it with chlorine. This was done by returning the water to the pool. As the filters used here, sand filters, diatomaceous earth filters, cartridge filters, etc. have generally been used.

However, pool water purification using Kowara's filter can only remove particles with a particle size of about 5 μs at most, which removes not only bacteria but also particles that have a large effect on water clarity.
．． It was not possible to remove fine particles having a particle size of about 0.05 to 5 scale. Therefore, in order to maintain good transparency of pool water, it is necessary to replenish fresh water in an amount of about 5 to 15% of the pool capacity per day. In addition, since bacteria could not be removed at all, it was necessary to carry out strong chlorine sterilization.

As a filtration technology to remove bacteria and particulates from water,
Methods using membrane filtration using hollow fibers and reverse osmosis membranes are known, but if these treatment techniques were used to treat the entire amount of circulating water in a pool, the purification cost would increase significantly.
This method is not practical as a method of purifying swimming pool water.

Furthermore, sodium hypochlorite, which has traditionally been used as a disinfectant for swimming pools, loses its disinfecting power and becomes Na
Disassemble into 1 liter. Therefore, even if a porous hollow fiber filtration membrane is used to perform advanced purification of pool water, the porous hollow fiber membrane cannot remove salts.
Even if the amount of sodium hypochlorite consumed could be reduced, reducing the amount of freshly supplied water would increase the concentration of salts in the pool water, giving swimmers an unpleasant sticky feeling.

On the other hand, to remove salts, it is sufficient to use the aforementioned reverse osmosis membrane, but if a reverse osmosis membrane is used for pool water, it may clog the membrane or deteriorate due to disinfectant chlorine. Although there are problems, in reality, it is safe to say that there are no examples of using reverse osmosis membranes to purify pool water.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an economical treatment method for maintaining the water quality of a swimming pool to be transparent and of good quality without a sticky feeling.

Another object of the present invention is to provide a pool water purification method that can significantly improve the quality of pool water by adding simple additional equipment to existing pool purification equipment.

Still another object of the present invention is to provide a method for purifying pool water that can reduce the amount of fresh make-up water and disinfectant chlorine used in the pool.

(Means for Solving the Problems) That is, the pool water purification method of the present invention includes the steps of treating pool water in a pool with a rough purification treatment line having a hair catcher and a filter and returning it to the pool. , A part of the treated water processed by the filter is guided to a precision filtration line having a hollow fiber filter with a built-in porous hollow fiber filtration membrane and a reverse osmosis membrane device, where it is treated and sent to the pool as highly purified water. It is characterized by having a step of returning.

[Preferred mode for carrying out the invention]

The pool water purification method of the present invention will be explained based on the flow sheet shown in FIG.

The pool water purification method of the present invention includes the steps of treating the pool water in the pool 1 in the rough purification treatment line (A) and returning it to the pool, and the process of treating the water ice treated in the rough purification treatment line (after passing through the filter). A part of the water) is guided to the precision purification treatment line (B),
Here, a two-stage precision purification process is carried out using a hollow fiber filter with a built-in porous hollow fiber filtration membrane and a reverse osmosis membrane device, and the resulting highly purified water is returned to the pool.

The rough purification treatment line CA) in the present invention may be any treatment line conventionally used as a pool purification treatment device, as long as it is provided with at least a hair catcher 2 and a filter 3. good. Therefore, in addition to the hair catcher and the filter, various conventionally known treatment means may be attached, such as a heat exchanger, a sterilization means,
A circulation pump or the like may be attached. In the example shown in FIG. 1, a pump 4 and a disinfectant tank 5 for storing disinfectant are attached.

Note that the hair catcher referred to herein is a strainer mainly for removing hair, etc., and a typical example thereof is a perforated metal basket having holes with a diameter of about 1+nmφ. Further, typical filters used here include a sand filter, a diatomaceous earth filter, a cartridge filter, and the like.

There is no particular restriction on the flow rate of the rough purification treatment line as long as it is at least 3 times the pool capacity per day as defined by law, but normally about 6 to lθ times the capacity per day is appropriate.

In the precision purification treatment line (B) in the pool water purification method of the present invention, treatment by the hollow fiber filter 7 having a built-in porous hollow fiber filtration membrane and treatment by the reverse osmosis membrane device 9 are carried out. The highly purified water is returned to the pool.

Various types of hollow fiber filters with a built-in porous hollow fiber filtration membrane used in the method of the present invention can be used, and are not particularly limited. It is preferable to use a cross-flow type hollow fiber filter because it is suitable for this purpose. A particularly preferable cross-flow type hollow fiber filtration machine has an inlet and an inlet for the water to be treated at both ends of a straight pipe, a hollow fiber filtration membrane is arranged within the straight pipe almost parallel to the straight pipe, and a hollow fiber filtration membrane For example, Japanese Patent Laid-Open No. 61-291008 and No. 62 shown in Figs. -1325
Examples include those disclosed in No. 03.

The porous hollow fiber filtration membrane built into the hollow fiber filtration machine 7 used in the method of the present invention can filter out fine particles with a particle size of up to about 0.05μ, and has a relatively high throughput per unit membrane area. A microporous hollow fiber made of polyolefin that can be made into a large size is suitable, and a typical example is polyethylene porous hollow fiber (EHF, manufactured by Mitsubishi Rayon ■), which has been appropriately made hydrophilic. used.

The reverse osmosis membrane device 9 used in the method of the present invention includes:
Various types of rings such as spiral type, tube type, capillary type, and flat membrane type can be used, but 8 to 15 g/cm2
It is preferable to use one that can be used at moderately low pressures. Further, as the material for the reverse osmosis membrane, cellulose acetate-based materials are suitable. Cellulose acetate-based membranes are susceptible to acids, alkalis, and bacteria, but since the raw water to be treated is swimming pool water, there are no problems in terms of acid and alkali resistance. In addition, since the water to be treated is supplied after being sterilized with chlorine and passed through a hollow fiber filter, bacteria will not reach the membrane surface of the reverse osmosis membrane, so there will be no problem in terms of bacterial resistance. be. In the case of an aramid-based or polyether-based membrane, it is not preferable to subject the membrane to oxidative decomposition due to free chlorine in the water to be treated, since the membrane is likely to deteriorate.

When a reverse osmosis membrane contains suspended particles or the like in the water to be treated, the membrane becomes clogged in a relatively short period of time, which tends to cause a decrease in the amount of permeated water. However, as in the method of the present invention, when a hollow fiber filtration machine is disposed in front of the filter and permeated water from which most of the suspended particles have been removed is supplied, the filtration process can be carried out without any special regeneration treatment.
It was found that it can withstand continuous operation for about several months.

In the method of the present invention, the larger the amount of water to be treated led from the rough purification treatment line to the precision purification treatment line, the more highly the pool water can be purified. It is not practical as it requires equipment. Usually, the amount is preferably about 0.3 to 0.9 times the capacity of the pool/day.

Even with this level of treatment flow rate, the bacteria in the pool water is 0.0
It is possible to reduce by half the concentration of fine particles with a particle size of about 5 to 5, and furthermore, the concentration of salts in water.

The water to be treated that is led to the precision purification treatment line is suitably that which has been previously treated in the rough purification treatment line (treated water after passing through a filter). It is also possible to treat the pool water by directing it to the precision filtration circulation line, but in this case, there are too many suspended substances in the water to be treated, so the hollow fiber filtration membrane in the hollow fiber filtration machine may become clogged. It tends to occur early.

The water to be treated that is led to the precision purification treatment line is first treated with zero hollow fibers! ! It is processed by a passing machine. The non-permeable water of the hollow fiber filter is
Normally, it is discharged outside the system as wastewater.

The arrangement of the hollow fiber filters in the precision purification treatment line is not particularly limited, but as shown in FIG. 2, a plurality of cross-flow type hollow fiber filters 7a
7e are preferably connected in series with the circulation pump 10 to form a circulation flow path (C), and the water to be treated is preferably circulated and treated.

When forming a circulation channel, the appropriate number of cross-flow type hollow fiber filters to be connected and arranged in series in one circulation channel is about 2 to 10, and 3 to 8. It is preferable that it is a group. If a sufficient processing flow rate cannot be obtained due to the membrane area of the hollow fiber filtration membrane with this number of hollow fiber filtration machines, the processing flow rate can be increased by arranging multiple circulation channels in parallel. It is better to increase it. If the number of hollow fiber filters disposed in the circulation channel is too large, the flow resistance of the circulation channel increases, which is not preferable.

When the filtration process using the hollow fiber membrane in the circulation channel is continued for a long time, the non-permeated water in the circulation channel is concentrated, and suspended substances in the water to be treated are filtered through the hollow fibers in the cross-flow filter. Since it adheres and deposits on the surface of the filtration membrane, the treatment efficiency gradually decreases and the flow rate of the obtained permeated water decreases.

Therefore, by supplying part of the permeated water that passes through the cross-flow type hollow fiber filtration machine and sent to the reverse osmosis membrane device to one or more of the cross-flow type filtration machines, the cross-flow type filtration is performed. It is preferable to perform an operation intermittently to wash and remove deposits attached to the outer surface of the hollow fiber filtration membrane in the machine (hereinafter, this washing operation will be abbreviated as 1 backwashing). In other words, when performing filtration, the external side of the hollow fiber filtration membrane is pressurized to allow the water to be treated to permeate into the hollow part of the hollow fibers and take out the permeated water from the side pipe. The backwash control valves 12a to +3e are operated so that the permeated water flows from the side pipe to the inside of the hollow fiber (1
Close one or two of 2a to 12e, and close the corresponding 13a
13e), and by applying water pressure, the deposits adhering to the outer surface of the hollow fibers are washed away into the straight pipe.

This backwashing operation can be done by using other hollow fiber filters when backwashing some of the hollow fiber filters arranged in series, so that even during backwashing, the circulation flow path can be maintained. The processing capacity will not decrease much. That is, the hollow fibers 11 connected in series
If the number of filters is 10 or less, backwash one or two hollow fiber filters at a time, and after the backwashing is finished or after a specified period of time, backwash the next hollow fiber filter. After backwashing of all the hollow fiber filters is completed, the backwashing may be repeated in order from the hollow fiber filter that was backwashed first. As a result, even during backwashing, the filtration function of each cross-flow type filter can be recovered in sequence without significantly reducing the processing capacity, and the precision purification processing line can always exhibit sufficient filtration function. Although backwashing may be carried out on two cross-flow type filters at a time, it is preferable to carry out backwashing on only one filter at a time since this allows safer operation.

When backwashing is performed, the deposits adhering to the outer surface of the hollow fibers are discharged into the straight pipe, so that backwash waste water with concentrated dirt is generated in the circulation flow path. Therefore, in conjunction with the execution of this cleaning, the drain port 11 provided in the circulation flow path is opened to discharge this backwash waste water. The number of drainage ports is not limited to one, and for example, the same number as the number of cross-flow filters may be provided. To open and close the drain port +1, for example, a drain port control valve may be operated.

If the circulation channel is configured by connecting five cross-flow type hollow fiber filters in series, for example, backwash each hollow fiber filter for 20 seconds every 10 minutes sequentially. It is possible to complete one cycle of backwashing of the entire circulation channel in 50 minutes. At this time, by operating the backwash control valves +2a to 13e as appropriate, normally only one or two hollow fiber filters are backwashed, and the remaining hollow fiber filters continue normal membrane filtration. It is a good idea to do so.

The opening and closing of the drain port 11 during backwashing is determined by taking into account the distance from the hollow fiber filters 78 to 7e that perform backwashing to the branch pipe for drainage, so that the backwash wastewater passes near the branch pipe for drainage. At the same time, open the drainage control valve and discharge the backwash drainage.

It is appropriate that the amount of backwash wastewater discharged is approximately 0.005 to 0.02 times the capacity of the pool for seven days. In the case of a pool that only has a conventional rough purification treatment line, it is necessary to use 5 to 15 of the pool capacity per day to maintain good pool water clarity.
Considering that it was necessary to supply as much fresh water as 1/1 in the method of the present invention,
There is an advantage that it can be reduced to about 0 to 115. For example, when a cartridge filter is used as a filtration machine in a rough purification treatment line, the cartridge filter itself is not backwashed, so only the backwash wastewater from the hollow fiber filtration machine needs to be discharged. When a filter is used, 1 to 3% of the pool capacity is required per day to clean the filter. Therefore, the amount of fresh make-up water will be reduced to about 1/] 0 when a cartridge filter is used as the filter in the rough purification treatment line, and to about I75 when a diatomaceous earth filter or sand filter is used. can.

In the method of the present invention, the permeated water thus filtered with the hollow fiber filter is then treated with a reverse osmosis membrane device,
Highly purified water from which salts and organic matter with a particle size of less than 0.05 u1 have been removed is obtained as permeated water, and this highly purified water is returned to the pool. On the other hand, the non-permeated water from the reverse osmosis membrane device may be discharged outside the system, but this water has been purified to a fairly high level, except for the high salt concentration.
It is not preferable to discharge the entire amount out of the system. however,
If the non-permeated water was returned to the pool as is, there would be no point in installing a reverse osmosis membrane device. Therefore, it is preferable to return this non-permeated water to the previous stage of the hollow fiber filter.

When some or all of the non-permeated water is returned to the previous stage of the hollow fiber filtration machine, the non-permeated water of the reverse osmosis membrane device circulates between the hollow fiber filtration machine and the reverse osmosis membrane device, so this route The salt concentration of will increase. However, since a solution containing a high concentration of salts is supplied to the water to be treated from which suspended particles have not been removed by the hollow fiber source membrane A, the salts precipitate in the form of flocs together with the suspended particles. It also has the effect that it cannot pass through the filtration membrane and is removed in solid form. Moreover, since the non-permeated water of the hollow fiber filtration membrane is continuously or intermittently discharged to the outside of the system, the salt concentration here does not exceed a certain concentration. Therefore, there is usually no need to consider the reduction in the processing flow rate in the reverse osmosis membrane device due to the circulation of unpermeated concentrated water to the reverse osmosis membrane device.

In addition, in the method of the present invention, the ratio of permeated water to non-permeated water in the reverse osmosis membrane device is usually 50 to 9.
It is preferable to operate at a pressure such that the ratio of non-permeated water to 0 parts by weight is 50 to 10 parts by weight.

〔Effect of the invention〕

According to the pool purification method of the present invention, advanced purification of pool water can be carried out economically by simply adding relatively simple additional equipment to conventional pool purification equipment.

In particular, regarding the quality of the pool water, the salt concentration is low, so it does not give swimmers a sticky feeling, and it has been difficult to maintain the clarity of the pool at around 15 meters, but now it is possible to increase the clarity of the pool to 25 meters or more. The amount of organic matter (potassium permanganate [t]) including bacteria in water can also be significantly reduced.

Furthermore, the amount of fresh water supplied to the pool has been reduced from 1/10 to 1/1 of the previous level.
15, and the amount of chlorine used for disinfection can be reduced to 2.
It is possible to reduce the amount by about 0 to 30%.

〔Example〕

EXAMPLES Hereinafter, the pool water treatment method and apparatus of the present invention will be explained in more detail according to Examples.

Example 1 Pool water was purified using the pool water purification equipment whose flow sheet is shown in FIG.

The capacity of pool 1 is 400nf, and the rough purification treatment line (A
), pool water was flowed at a flow rate of 100 m'/hr.

Hair catcher 2 has a diameter of 200o+mφ and a depth of 300ffIII with a large number of circular holes with a hole diameter of 1ffIIn.
+ stainless steel hook, 1 for filter 3
Using a sand filter for 00rn'/hr processing, a sodium hypochlorite aqueous solution 12wt%7 (
0,3j! It was supplied at a flow rate of /hr. In addition, a part of the treated water filtered by the filter 3 is pumped through the pump 6 at a rate of 8rn'/h.
It was supplied to the precision purification treatment line (B) at a flow rate of r. Five cross-flow precision filters 78 to 7e having the structure shown in FIG. 3 are installed in the circulation flow path (C) in the hollow fiber purification treatment line.
The pump 10 is constructed by connecting the base and the circulation pump 10 in series, and three such circulation channels are arranged in parallel (only one circulation channel is shown in FIG. 2). The inner diameter of the straight pipe of each cross-flow type hollow fiber filtration machine is 6.5 cm, and a porous polyethylene hollow fiber filtration membrane (
The effective membrane area of EHF (manufactured by Mitsubishi Rayon ■) was 10 rn''.

The permeated water obtained from the side pipe of each hollow fiber filter has a diameter of 20
A reverse osmosis membrane device 9 equipped with a spiral reverse osmosis membrane module made of cellulose acetate with an effective membrane area of 20 cm was supplied at a rate of 15 Kg/cm by a pump 8.The permeated water was 8 rrP/hr minus the drainage amount. ,
The entire amount was returned to the pool.

On the other hand, the average amount of non-permeated water in a reverse osmosis membrane device is approximately 1.5rn'/
hr, and the entire amount was returned to the circulation channel (C) via the non-permeated water return channel (D).

One hour after the precision purification treatment line starts operating, the cross-flow type filters in each circulation flow path are cleaned from the side pipes.
Backwashing was performed by backflowing the permeate for 20 seconds at a flow rate of 1.2 m3/hr. In addition, as the backwash wastewater generated by backwashing passes near the drain port,
1 was opened and discharged by operating the control valve. The amount of water discharged was 4 tons/day. Backwashing was carried out sequentially for each cross-flow type filter every 10 minutes, so that one cycle of backwashing for the entire circulation channel was completed in 50 minutes, and this backwashing operation was continued thereafter. Ta.

The pool was replenished with the same amount of fresh water as the backwash water discharged from the outlet. Additionally, there are an average of 400 swimmers in the pool each day.

Table 1 shows the quality of the pool water after purifying the pool water in this way for 10 days.

Comparative Example 1 In the pool used in Example 1, only the rough purification line was operated, and the pool water was purified without operating the fine purification line. The pool was replenished with about 50 ha of fresh water per day, and the same amount of pool water was discharged outside the system. In addition, there are an average of 400 swimmers in the pool per day, and the amount of disinfectant consumed is 0.3
It was 5 B, /hr.

Table 1 shows the quality of the pool water after purifying the pool water in this way for 10 days.

Comparative Example 2 In the pool water purification system used in Example 1,
Pool water purification treatment was carried out in exactly the same manner as in Example 1, except that the reverse osmosis membrane device was removed from the precision purification treatment line.

In this example as well, the average number of swimmers in the pool per day was 400, but the consumption of disinfectant was fl/hr. Table 1 shows the quality of the pool water after purification of the pool water was continued for 10 days in this manner.

Table 1 F I (fouling index) values and other than transparency were determined according to the clean water test method.

Transparency was determined by visual inspection.

The FI value was calculated by the following formula by filtering the sample water using a membrane filter with a pore size of 0.2p and a diameter of 25p by applying a pressure of 3.0kg/cm2.

(T1: Time until obtaining filtrate 4011, T2: Time until obtaining 20 kl of filtrate, T,: Time until obtaining filtrate 400-)

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing a basic example of the pool water purification method of the present invention, and FIG. 2 is a flow sheet showing a more preferred embodiment of the pool water purification method of the present invention. FIG. 3 and FIG. 4 are schematic cross-sectional views showing a typical example of a cross-flow type hollow fiber filter used in the method of the present invention. 1: Pool 2: Hair catcher 3 =
Filtration machine 4.6.8.14: Bump 5: Disinfectant tank 7.78-7C: Hollow fiber filtration machine 9: Reverse osmosis membrane device IO = Circulation pump ll: Drain port +2a-+3e 15: Straight pipe 17: Side Pipe A: Rough purification treatment line C: Circulation flow path E2 Backwash line: Backwash control valve 16: Hollow fiber 18: Fixing member B: Tight purification treatment line D: Non-permeated water return flow path Figure 3] 5 Figure 1 Figure 4

Claims (1)

[Claims] 1) A step in which pool water in the pool is treated in a rough purification treatment line having a hair catcher and a filter and returned to the pool, and a part of the treated water treated with the filter is purification of pool water, comprising the step of guiding the water to a precision filtration line having a hollow fiber filtration machine incorporating a porous hollow fiber filtration membrane and a reverse osmosis membrane device, treating the water, and returning it to the pool as highly purified water. Method. 2) As the hollow fiber filtration machine, inlets and outlets for the water to be treated are arranged at both ends of a straight pipe, a porous hollow fiber filtration membrane is arranged in the straight pipe, and hollow fiber filtration is carried out from a side pipe connected to the straight pipe. A cross-flow type hollow fiber filtration machine having a structure to obtain permeated water filtered through a membrane is used to precisely purify a circulation channel formed by connecting a plurality of the cross-flow type filtration machines and a circulation pump in series. A method for purifying pool water in which highly purified water is obtained by treating the permeated water with a reverse osmosis membrane device, the permeated water being intermittently flowed back into one or more cross-flow filters. Clean the cross-flow type filter by
2. The method for purifying pool water according to claim 1, further comprising the step of opening a drain provided in the circulation flow path in conjunction with the cleaning to discharge a portion of the cleaning wastewater. 3) The pool water treatment method according to claim 2, wherein non-permeated water from the reverse osmosis membrane device is returned to the circulation channel.