TW201703846A - Water treatment method and device - Google Patents

Abstract

A water treatment method and a water treatment device therefor are provided for treating backwash wastewater, washing wastewater, recirculating water or concentrated water in a membrane separation device and using the same as cooling water in a cooling tower. After filtering with a filter 30, blowdown water of the cooling tower 1 is subjected to treatment in a pretreatment membrane device 33 such as an MF membrane, is subsequently to treatment with a reverse osmosis membrane device (an RO membrane device) 38, and the RO treated water is returned to the cooling tower 1. Washing wastewater, backwash wastewater and concentrated water from the pretreatment membrane device 33 and the RO membrane device 38 are returned to a water piping 11 leading to a side filter 14.

Description

Water treatment method and device

The present invention relates to a method and an apparatus for reusing a backwashing drain, a washing drain, circulating water, concentrated water, and the like of a membrane separation apparatus, and more particularly to a water treatment method and apparatus suitable for recovering cooling tower discharge water.

In a heat transfer surface or a pipe that is in contact with water, such as a cooling water system or a boiler water system, scale defects occur. In particular, based on the viewpoint of saving resources and energy saving, the cooling water is blown toward the outside of the system for high concentration operation, and the dissolved salts are concentrated to make the heat transfer surface easy to corrode and become poorly soluble. The salt forms a scale. If scale adheres to the wall surface of the device, the thermal efficiency is lowered, the piping is clogged, and the like, and the operation of the boiler or the heat exchanger is seriously hindered. In recent years, the tendency to use water as efficiently as possible has become remarkable for the purpose of saving water and energy, but in the case of higher concentration operation, there is a limit to suppress scale precipitation.

A technique in which a cooling water discharge water is passed through an MF membrane or a UF membrane to remove suspended matter in the discharged water, and then subjected to RO membrane treatment to remove ions, organic matters, and the like, and returned to the cooling tower is known (Patent Literature) 1,2).

[Patent Document 1] Japanese Special Opening 2002-18437

[Patent Document 2] Japan Special Open 2003-1255

The method of recovering using an MF membrane, a UF membrane, or an RO membrane must wash the membrane periodically or irregularly. In Patent Documents 1, 2, the backwashing drainage or the like after washing is discharged to the outside of the system, so that the water recovery rate is accordingly lowered. In addition, when backwashing water, circulating water, concentrated water, washing drainage, etc. are discharged outside the system, it may be necessary to perform drainage treatment according to the water quality.

An object of the present invention is to provide a method and an apparatus for using a backwashing drain, a washing drain, a concentrated water, and circulating water of a membrane separation device as cooling water for a cooling tower.

In the water treatment method of the present invention, a part or all of the membrane separation device discharge water composed of at least one of the backwashing drain, the washing drain, the circulating water, and the concentrated water of the membrane separation device is supplied to the cooling tower.

A water treatment device according to the present invention is a water treatment device having a membrane separation device, comprising: a supply device for backwashing, washing drainage, circulating water, and concentrated water of the membrane separation device A part or all of the discharged water of the membrane separation device constituted by at least one of them is supplied to the cooling tower.

Preferably, the membrane separation device comprises a pretreatment membrane device and a reverse osmosis membrane device, the pretreatment device having at least a precision filtration membrane or an ultrafiltration membrane.

In one aspect of the invention, the cooling tower is provided with a filtration device for circulating at least a portion of the cooling water.

In the present invention, it is preferred that the membrane separation device discharges water for filtration treatment and supplies it to the cooling tower. In this case, it is preferable that the filtration treatment is performed using a filtration device provided in the cooling tower for circulating filtration of at least a part of the cooling water.

In one aspect of the present invention, a cooling water pipe is connected to a water supply pipe that supplies water to a filtering device for circulating filtration of at least a portion of cooling water from the cooling tower; and the membrane separation device discharge water is supplied to the cooling device. The water supply pipe or the vicinity of the water supply pipe connection portion in the cooling tower.

In one aspect of the invention, the discharge water of the membrane separation device is temporarily stored in a water tank and supplied to a cooling tower.

In one aspect of the invention, the discharge water of the cooling tower is supplied to the membrane separation device.

In the water treatment method and apparatus of the present invention, at least one of the backwashing drain, the washing drain, and the concentrated water provided in the membrane separation apparatuses of the various water treatment lines is supplied to the cooling tower and used as cooling water to increase the water. Recovery rate. In particular, the cooling tower discharge water is fed through a membrane separation device. The treatment is carried out as a cooling water, and at least one of the backwashing drain, the washing drain, the circulating water, and the concentrated water of the membrane separation device is used as the cooling water, thereby improving the water recovery rate of the cooling tower. .

In one aspect of the present invention, after the discharge water is filtered by the MF membrane or the UF membrane, the deionized and organic matter removal treatment is performed by the RO membrane, and the RO treated water is used as the cooling water of the cooling tower. Further, the washing drainage of the backwash water, the circulating water, the concentrated water, and the RO membrane of the MF membrane or the UF membrane is filtered and supplied to the cooling tower. This filtration treatment is performed by a filtration device provided in the cooling tower system and configured to circulate and filter at least a part of the cooling water, whereby the existing equipment can be utilized.

1‧‧‧Cooling tower

4‧‧‧ heat exchanger

14‧‧‧ side filter

25‧‧‧Water treatment unit

30‧‧‧Filter

33‧‧‧Pretreatment membrane unit

38‧‧‧RO membrane device

Fig. 1 is a flow chart showing a water treatment method and apparatus according to an embodiment.

Fig. 2 is a flow chart showing a water treatment method and apparatus according to an embodiment.

Hereinafter, embodiments will be described with reference to the drawings. Figure 1 shows an example of a cooling tower system employing the method and apparatus of the present invention.

The cooling tower 1 of the cooling tower system is configured such that the cooling water sprinkled from the sprinkling pipe 1a is cooled by contact with the air introduced from the louver 1c while flowing through the filler layer 1b, and then stored in the water storage tank (pit). ) 1d (the bottom sink of the cooling tower), the air containing the vapor is by the fan 1e is discharged into the atmosphere. The cold water in the water storage tank 1d of the cooling tower 1 is supplied to the heat exchanger 4 through the pump 2 and the pipe 3, and the return water from the heat exchanger 4 is sent back to the water sprinkling pipe 1a of the cooling tower 1 through the pipe 5.

A part of the water in the water storage tank 1d is supplied to the side filter 14 through the water supply side circulation pipe 11, the pump 12, and the valve 13, and after being filtered, it is sent back to the water storage tank 1d through the return side circulation pipes 15, 17 and the valve 16. The side filter 14 is constituted by a filter device using a floating filter, a sand filter, or the like. The backwashing air can be introduced into the pipe 15 through the air pump 19 and the valve 18. On the primary side of the side filter 14, a discharge pipe 14 having a backwash drain of the valve 14a is connected.

When the side filter 14 performs the filtering process, the valves 13, 16 are opened, and the valves 14a, 18 are closed. When the side filter 14 is subjected to air backwashing, the valves 13, 16 are closed, the valves 14a, 18 are opened, the air from the air pump 19 is supplied to the side filter 14, and the backwash drain is discharged through the pipe 14b.

The makeup water is supplied from the makeup water line 8 to the cooling tower 1 by means of the float valve device 7 (or the water supply valve device having the water level sensor) to bring the water level in the water storage tank 1d to a predetermined water level.

A conductivity meter for measuring the conductivity of the cooling water in the water storage tank 1d is provided. When the conductivity detected by the conductivity meter is equal to or greater than a predetermined value, the discharge valve 21 is opened to increase the salt concentration. A part of the cooling water is discharged through the piping 22 in the form of discharged water. In the present embodiment, the drain water is sent to the water treatment device 25 through the pump 23 and the pipe 24. Pump 23 is not required if gravity can be used to deliver water. The configuration of the water treatment device 25 will be described later in detail.

In the cooling tower 1, in order to remove the heat of the process, a part of the circulating water evaporates, and the make-up water becomes a concentrated state. The concentrated cooling water is affected by the occurrence of scale and slime, which may cause deterioration of the heat exchange efficiency of the heat exchanger. Therefore, it is necessary to add a dispersant or a degreaser for preventing the occurrence of such a disintegration. Medicines.

As the dispersing agent, inorganic polyphosphoric acid such as sodium hexametaphosphate or sodium tripolyphosphate; phosphonic acid such as hydroxyethylidene diphosphonic acid or phosphonic acid butane tricarboxylic acid; maleic acid or acrylic acid; a carboxyl group-containing material such as itaconic acid; and a vinyl group having a sulfonic acid group such as vinylsulfonic acid, allylsulfonic acid, 2-methylpropenylamine-2-methylpropanesulfonic acid or the like as necessary A copolymer other than the materials listed herein can also be used as a copolymer of a monomer or a nonionic vinyl monomer such as acrylamide. As the third component of the dispersant, other components are used, and a terpolymer can also be used. For example, N-t-butyl acrylamide or the like is used as the third component.

As a dispersing agent, among them, HAPS (3-allyloxy-2-hydroxy-1-propanesulfonic acid) and a copolymer of acrylic acid and/or methacrylic acid, AMPS (2-acrylamide-2) a copolymer of -methylpropanesulfonic acid) and acrylic acid and/or methacrylic acid.

The molecular weight of the dispersant is preferably 1,000 or more and 30,000 or less. When the molecular weight is less than 1,000, a sufficient dispersion effect cannot be obtained; when it exceeds 30,000, it may be removed by the pretreatment film. One of the features of the present invention is that the cooling water medicine contained in the cooling tower discharge water can be reused as a medicine for a reverse osmosis membrane, so that the dispersion can be performed. The agent and the slime removing agent described later are effectively used.

As the degreasing agent, hypochlorite such as sodium hypochlorite (NaClO); chlorine such as chlorine gas, chloramine or chlorinated isocyanate; chlorine and amine sulfonic acid such as monochlorinated sulfonic acid; a chlorinating agent (reinforcing chlorine agent) obtained by reacting a compound having an amine sulfonic acid group; a bromine agent such as dibromoethendazole; a bromine and an amine sulfonic acid such as monobutyl sulfonic acid; An organic agent such as a bound bromine agent (stabilized bromine agent) obtained by reacting an acid group compound; DBNPA (dibromonitrienylpropionamide) or MIT (methylisothiazolinone).

In the combined chlorine agent and combined bromine agent, nitrogen compounds combined as free chlorine and free bromine include ammonia or a compound thereof, melamine, urea, acetamide, sulfonamide, chloramine, amine sulfonic acid, toluene. Sulfonamide, amber imine, quinone imine, iso-cyanuric acid, N-chlorotoluenesulfonamide, uric acid, saccharin or the like, and the like. The chlorinating agent used in the present invention is composed by combining free chlorine with these nitrogen compounds. As such a combined chlorine agent, in addition to a combined chlorine agent composed of a chloramine, a chlorine-based oxidizing agent and an aminesulfonic acid compound, chloramine-T (N-chloro-4-methylbenzenesulfonamide) can also be mentioned. Sodium salt), chloramine-B (sodium salt of N-chloro-benzenesulfonamide), sodium salt of N-chloro-p-nitrobenzenesulfonamide, sodium trichloride melamine, sodium mono- or di-chloro melamine a salt or a potassium salt, a trichloro-isocyanate, a sodium or potassium salt of mono- or di-chloroisocyanate, a sodium or potassium salt of mono- or di-chloroamine sulfonic acid, monochloroethyl guanidine or 1, 3-Dichloroethyl hydrazine, a 5,5-alkyl derivative such as 5,5-dimethylethene oxime or the like. The same applies to the bromine-binding agent, except that the chlorine moiety is changed to bromine.

As the medicine for changing the pH, for example, hydrochloric acid, sulfuric acid, nitric acid, sodium hypochlorite, sodium hydroxide, citric acid, oxalic acid or the like can be selected. The material is not particularly limited.

More than one of the drugs can be used. It is preferred to determine the concentration of the degreaser of the cooling tower, thereby controlling the amount of injection. It is preferred to control the pH of the cooling tower to be controlled within a certain range.

The water treatment device 25 for treating the discharged water will be described next.

The discharged water from the cooling tower is removed by a filter 30 such as a strainer, and then the sludge and the pH adjuster (for example, sulfuric acid) are added to the water tank 31, and then used. The pretreatment membrane device 33 performs a turbidity removal treatment. The water that has not passed through the membrane 33m is introduced into the water-supply-side circulation pipe 11 through the pipe 34. The impervious water is preferably sent directly back to the water storage tank 1d (the lower tank of the cooling tower) or returned to the water tank 31. The water that has passed through the membrane 33m is supplied to the RO membrane unit 38 via the valve 35, the water tank 36, and the piping 37, and is subjected to deionization treatment. The treated water after the deionization treatment is returned to the cooling tower 1 via the piping 39. The RO treatment water can be sent back to the makeup water line 8, and can also be returned to the circulation pipes 11, 15, 17, etc. leading to the side filter 10.

The concentrated water of the RO membrane device 38 is preferably discharged through the valve 43 and the pipe 45.

The RO membrane device 38 is intermittently subjected to rinsing washing or washing with a chemical using an alkali or an acid. The washing and draining water at this time is also recovered through the piping 42.

The filter 30 such as the above-described strainer can be operated even if it is not installed, but the pretreatment membrane device 33 may be damaged, so it is preferable to set it. An automatic strainer that automatically performs the washing process should be used. The shape of the strainer is not particularly limited, and any shape such as a Y shape or a barrel type may be employed. The pore size of the strainer is preferably from 100 to 500 μm. When it is less than 100 μm, the clogging of the strainer tends to become severe. When it exceeds 500 μm, the possibility that the pre-treated film is damaged by the coarse suspension or foreign matter that has passed through the strainer tends to be high. It is also possible to use a filter such as a wound filter or a pleated filter instead of the strainer, but it is preferable to use a strainer in consideration of replacement frequency and detergency.

The pretreatment membrane device 33 is a suspension or a colloidal component in the water for removing the cause of membrane fouling of the RO membrane device 38, and an MF membrane or a UF membrane can be used. The film type is not particularly limited, and a membrane filtration device such as a hollow fiber type or a spiral type can be used. In addition, the filtration method is not limited, and any method of internal pressure filtration, external pressure filtration, cross flow filtration, and full filtration may be employed. The molecular weight cut off of the MF membrane and the UF membrane is preferably 30,000 or more. When less than 30,000, the dispersant may be removed. The upper limit of the molecular weight cut off is not particularly limited. However, when it is 1,000,000 or less, the polymer polysaccharide or the like which causes clogging of the RO membrane in the cooling water can be removed, which is preferable. At the start of the operation of the pretreatment membrane apparatus, the venting step after the backwashing, and the like, a water injection step and a circulation step of filling the inside of the casing with water are performed, and the discharged water (circulating water) at this time is also sent through the piping 34. The water side circulation pipe 11 is returned, or directly returned to the water storage tank 1d.

Desiccant, pH which can be used in pretreatment membrane unit 33 The regulator can be the same type as that used in the cooling tower. By using the same type, it can be effectively utilized in the cooling tower. When a combined chlorine agent or a bromine agent is used in the cooling tower, by using free chlorine and free bromine in the pretreatment membrane unit 33, it can react with the combined chlorine agent (stabilizing agent) present in the cooling tower. Reduce the amount of free chlorine that must have been added to the cooling tower.

The pretreatment membrane device 33 performs periodic or irregular backwashing treatment, and discharges the suspended matter or the like accumulated in the membrane 33m to the outside of the system. The backwashing frequency is generally performed once every 10 to 60 minutes, but is not limited thereto. By adding hypochlorous acid and a salt thereof, or hypobromous acid and a salt thereof, an organic chlorine-based bactericide, a chlorine-based bactericide, a bactericidal agent such as a bromine-based bactericide, a slime controlling agent, or It is to change the pH to carry out backwashing, which can improve the recovery effect.

In order to carry out the backwashing, in the present embodiment, the membrane in the water tank 36 is permeated with water. That is, at the time of backwashing of the film 33m, the valves 32, 35 are closed, the valves 52, 54 are opened, the pump 50 is actuated, and the water in the water tank 36 is supplied to the secondary side of the film 33m via the pipes 51, 53. At this time, a chemical agent such as NaClO may be added to the pipe 53 to wash the chemical solution. The backwash drain is supplied from the pipe 34 to the pipe 11 (the suction side of the pump 12). In addition, it is also possible to carry out air backwashing instead of water backwashing. Also in this case, the backwash water is recovered through the piping 34. While backwashing, a drug such as NaClO may be added to the primary side of the membrane to perform immersion washing. The washing and draining water at this time is also returned to the water supply side circulation pipe 11 via the pipe 34, or directly returned to the water storage tank 1d.

The type of the RO membrane 38m of the RO membrane device 38 is not particularly limited, and is appropriately determined depending on the water quality of the circulating cooling water to be treated (the raw water quality supplied to the circulating cooling water system, and the concentration ratio of the circulating cooling water system). The salt rejection ratio of the RO film 38m is preferably 80% or more, and particularly preferably 85% or more. When the salt rejection rate is lower than this value, the deionization efficiency is poor, and it is difficult to obtain treated water (permeate water) having good water quality. As the RO film 38m, a film of any material such as a polyamide composite film or a cellulose acetate film can be used, and a polyamide composite film is preferably used from the viewpoint of removal rate. The shape of the RO film 38m is not particularly limited, and both a hollow fiber type and a spiral type can be used.

In the water supply of the RO membrane unit 38, it is preferred to add a degreasing agent. In the case of a polyamide composite film, as a degreasing agent, a chlorine-binding agent, a bromine-binding agent, and an organic agent are preferably used. The chlorine agent and bromine agent previously described may cause deterioration of the film, which is not preferable. This step can be omitted by sharing the cooling water drug with the dispersant and the degreaser. In the present embodiment, the pH adjuster is added to the water tank 31. However, depending on the type of the dispersant, the polymer may cause clogging of the pretreatment film. Therefore, it is preferable not to be in the front stage of the pretreatment membrane apparatus but in the RO water supply. A pH adjuster (such as sulfuric acid) is added.

By returning the backwashing water and the concentrated water to the pipe 11, the suspended matter in the backwashing water and the concentrated water is removed by the side filter 14 to prevent the concentration of the suspended matter in the cooling water system. The concentration rises. When the side filter 14 is not provided, a filter device may be additionally provided in the return line.

Returning the backwash drain of the cooling tower, circulating water, washing drainage, total water amount per hour of concentrated water, and cooling water treatment system The ratio of the retained water amount is preferably 1:100 or more. In other words, the amount of water retained in the cooling tower when the backwash water and the concentrated water are returned is preferably 100 times or more the amount of water returned. If there is more than 100 times the amount of water, it is possible to suppress the increase in concentration at the time of return and become a problem without any problem. When the backwashing water and the concentrated water are returned, in order to prevent the water quality of the cooling water from changing, a pH measuring device, an adjusting device, or a chlorine measuring device or an adjusting device may be provided.

In the present embodiment, a water tank is provided in the water treatment device that treats the discharged water, but it may not be provided. In the present invention, as shown in Fig. 2, in order to level the inflow load, the backwash drain, the concentrated water, the circulating water, and the washing drain can be temporarily stored in the water tank 55, and then returned quantitatively via the pump 56 and the piping 57. Pipe 11, cooling tower.

The water quality of the backwashing drainage, circulating water, washing drainage, and concentrated water can be detected by a detector, and when the concentration is equal to or higher than the predetermined concentration, the recovery is not performed.

As described above, in the present embodiment, the backwash water, the circulating water, the concentrated water, and the chemical liquid washing wastewater from the pretreatment membrane device 33 are recovered. The flushing drain, the chemical washing wastewater, and the circulating water from the RO membrane unit 38 are recovered.

In the above description, the pretreatment membrane device 33 and the RO membrane device 38 are used. However, other membranes and filtration means can be used, and all of the concentrated water of the cleaning means can be collected. The washing waste water can be supplied to the cooling tower via a line branched from the drain line, or can be directly supplied to the cooling tower side via the supply line. The same is true for concentrated water, which can be recycled from the pipeline. The divergent supply to the cooling tower can also supply all of the concentrated water to the cooling tower.

In the above-described embodiment, the circulating water supply pipe 11 for returning the concentrated water, the backwashing water, and the like to the side filter 14 can be returned to another portion, and can be directly returned to the water storage tank 1d, for example, the water storage tank 1d. The vicinity of the connection portion of the pipe 11. By arranging the return destination in the vicinity of the suction port of the pipe 11 of the water storage tank 1d, the water containing the suspended matter can be immediately sent to the side filter 14 through the pipe 11 when the water containing the suspended matter enters the water storage tank. deal with. It is also possible to return it via the pipe 3 depending on the water quality.

In the above embodiment, the water treatment device for collection includes the pretreatment membrane device 33 such as the filter 30 and the UF membrane device, and the RO membrane device 38, and the filter, the UF membrane, the MF membrane, and the nanofiltration membrane may be used. And one or any two or more of the RO membranes are combined.

In the present invention, the amount of the suspended matter of the backwashing drainage, the circulating water, the washing drainage, and the concentrated water is preferably less than 1000 degrees (turbidity). The turbidity of the backwashing drain can be as high as about 300 degrees, and can be reduced to less than 1 degree by filtration. The pH of the backwashing drainage, the circulating concentrated water, and the washing drainage is preferably 2 to 12.

In the above-described embodiment, the cooling tower discharge water is treated by the membrane separation device and is collected, and is used as a cooling tower for the treatment of the membrane treatment equipment such as water and drainage in a factory or a factory. The water supplier can be treated as the cooling water of the cooling tower 1 by the water treatment device 25 described above. However, if it is the cooling tower discharge water, the suspended components in the washing wastewater are the same. Points, there are benefits that are easier to apply.

In the above embodiment, the water is sent to the water treatment device via the discharge pipe 22, but the pressure of the pump 2 can be used to convey the position from the transfer pipe 3 and the return pipe 5 to the heat exchanger.

[Examples] [Example 1]

In the cooling tower using the industrial water in Chiba City, Japan as the circulating water of 5,000 m ³ /h and the retained water volume of 1,000 m ³ /h, the cooling tower discharge water was recovered at a concentration ratio of 3.5 times.

The dispersant treatment in cooling water is a dispersant using a copolymer of acrylic acid and AMPS (mole ratio 70:30) and an average weight molecular weight of 10,000. The dispersant in the initial system was maintained at a concentration of 3 mg/L. As the degreasing agent, a mixture of a base described in WO11/125762 and an aminesulfonic acid or hypochlorous acid is used. The slimming agent was added in such a manner that the initial combined chlorine concentration in the system became 1.0 mg/L. In the cooling tower, a light filter manufactured by Kurida Industrial Co., Ltd. was installed as a side filter system, and filtered at 150 m ³ /h to quantitatively remove the suspended matter in the system.

In the flow of the recovery process, the entire amount of the discharge water amount of 20 m ³ /h is recovered by using a strainer, an MF device, and an RO membrane device as in the water treatment device 25 of Fig. 1 . The screen of the strainer was 400 μm, and the MF membrane was Pyuria GS (hydrophilized PVDF, pore size 0.02 μm, external pressure type) made of Kuraray. The RO membrane was KROA-2032-SN (polyamide low pressure RO membrane) manufactured by Kurida Industry Co., Ltd. The backwashing frequency of the MF device was every 30 minutes, and sodium hypochlorite was added at a concentration of 100 mg/L during backwashing. The backwash water of the MF unit is sent back to the cooling tower. By returning the backwash water of the MF device, the water recovery rate is 100%. The amount of backwash per 1 time is 1 m ³ .

The pH of the discharged water was 8.5 to 8.7, and sulfuric acid was added in front of the RO membrane device to bring the pH to 5.5. Every three months, as the amount of water in the RO membrane device decreases, the RO membrane device is washed with a sodium hydroxide solution adjusted to pH 11, and the washed liquid is returned to the cooling tower. The amount of water in the washing liquid is 4 m ³ . The water recovery rate of the RO membrane unit is 70 to 75%. By recovering the backwash water and the washing drainage, the washing treatment does not affect the water recovery rate, and the total water recovery rate is 70 to 75%.

The suspended matter at the time of backwashing was removed by a side filter, and the turbidity was stably maintained in the range of 5 to 7 degrees. The sodium hypochlorite added during the backwashing is consumed in the cooling tower, and the chlorine concentration is 0.1 to 0.2 mg/L. The combined chlorine concentration is 0.8~1.0mg/L.

[Comparative Example 1]

The same treatment as in Example 1 was carried out except that the backwashing drainage of the MF apparatus and the washing and draining of the RO membrane apparatus were discharged outside the system without being returned to the cooling tower. The water recovery rate of the MF membrane was 90%, and the water recovery rate of the RO membrane unit was 68 to 73%. Therefore, the total water recovery rate is 61 to 65%.

In order to discharge the backwashing drain and the washing drain to the outside of the system, it is necessary to carry out a reduction treatment and a pH neutralization treatment.

[Embodiment 2]

The same treatment as in the first embodiment was carried out in the same cooling tower system as in the first embodiment except that the side filter 14 was not provided in the cooling tower system. As a result, the amount of the suspended matter in the system gradually increased, and after 10 days, it became 50 degrees (haze) or more and the treatment was stopped.

[Example 3]

The same treatment as in Example 1 was carried out except that the amount of water retained in the cooling tower was 100 m ³ . The effect of returning the backwash water of the MF device is not seen. However, when the washing drainage of the RO membrane device is returned, the pH changes, and CaCO ₃ scale is precipitated in the system, so that the return is stopped.

[investigation]

As described above, according to the method and apparatus for treating circulating cooling water according to the present invention, the backwashing drainage and the washing drainage in the recovery process can be returned to the cooling tower, thereby improving the water recovery rate without adding additional water. Drainage treatment, and stable treatment with excellent economy and high recovery rate.

The present invention has been described in detail with reference to the specific embodiments thereof.

The present application is based on Japanese Patent Application No. 2015-072960, filed on Jan.

1‧‧‧Cooling tower

1a‧‧‧ sprinkler pipe

1b‧‧‧Filling layer

1c‧‧‧ louver

1d‧‧‧storage tank

1e‧‧‧fan

2‧‧‧ pump

3‧‧‧Pipe

4‧‧‧ heat exchanger

5‧‧‧Pipe

7‧‧‧Floating ball valve device

8‧‧‧Supply water pipeline

11‧‧‧Water supply side circulation piping

12‧‧‧ pump

13‧‧‧Valve

14‧‧‧ side filter

14a‧‧‧Valve

14b‧‧‧Pipe

15‧‧‧Return side circulation piping

16‧‧‧ valve

17‧‧‧Return side circulation piping

18‧‧‧ valve

19‧‧‧Air pump

21‧‧‧Drain valve

22‧‧‧Pipe

23‧‧‧ pump

24‧‧‧Pipe

25‧‧‧Water treatment unit

30‧‧‧Filter

31‧‧‧Sink

32‧‧‧Valves

33‧‧‧Pretreatment membrane unit

33m‧‧‧ film

34‧‧‧Pipe

35‧‧‧ valve

36‧‧‧Sink

37‧‧‧Pipe

38‧‧‧RO membrane device

38m‧‧‧RO film

39‧‧‧Pipe

41‧‧‧ valve

42‧‧‧Pipe

43‧‧‧Valves

44‧‧‧Pipe

45‧‧‧Pipe

50‧‧‧ pump

51‧‧‧Pipe

52‧‧‧Valves

53‧‧‧Pipe

54‧‧‧ valve

Claims (16)

A water treatment method is characterized in that a part or all of the membrane separation device discharge water composed of at least one of a backwashing drain, a washing drain, a circulating water, and a concentrated water of a membrane separation device is supplied to a cooling tower. The water treatment method according to claim 1, wherein the membrane separation device comprises a pretreatment membrane device and a reverse osmosis membrane device, the pretreatment device having at least a precision filtration membrane or an ultrafiltration membrane. The water treatment method according to claim 1 or 2, wherein the cooling tower includes a filtration device for circulating at least a part of the cooling water. The water treatment method according to claim 1 or 2, wherein the membrane separation device discharges water for filtration treatment and supplies it to the cooling tower. The water treatment method according to claim 4, wherein the filtering treatment is performed by a filtration device provided in the cooling tower, wherein the filtration device is configured to circulate and filter at least a part of the cooling water. The water treatment method according to claim 1 or 2, wherein the cooling tower is connected to a water supply pipe that supplies water to a filtering device for circulating and filtering at least a part of the cooling water from the cooling tower. ; The membrane separation device discharge water is supplied to the water supply pipe or the vicinity of the water supply pipe connection portion in the cooling tower. The water treatment method according to any one of claims 1 to 6, wherein the membrane separation device discharge water is temporarily stored in a water tank and supplied to a cooling tower. The water treatment method according to any one of claims 1 to 7, wherein the discharge water of the cooling tower is supplied to the membrane separation device. A water treatment device is a water treatment device having a membrane separation device, characterized in that it is provided with a supplier for at least a backwashing drainage, a washing drainage, a circulating water, and a concentrated water of the membrane separation device. A part or all of the discharged water of the membrane separation device constituted by one is supplied to the cooling tower. The water treatment device according to claim 9, wherein the membrane separation device comprises a pretreatment membrane device and a reverse osmosis membrane device, the pretreatment device having at least a precision filtration membrane or an ultrafiltration membrane. The water treatment device according to claim 9 or 10, wherein the cooling tower is provided with a filtration device for circulating and filtering at least a part of the cooling water. The water treatment device according to claim 9 or 10, wherein The membrane separation device discharge water is filtered by a filtration device and supplied to the cooling tower. The water treatment device according to claim 12, wherein the filtration device is a filtration device installed in a cooling tower and configured to circulate and filter at least a part of the cooling water. The water treatment device according to claim 9 or 10, wherein the cooling tower is connected to a water supply pipe that supplies water to a filtering device for circulating and filtering at least a part of cooling water from the cooling tower. The membrane separation device discharge water is supplied to the water supply pipe or the vicinity of the water supply pipe connection portion in the cooling tower. The water treatment device according to any one of claims 9 to 14, further comprising a reservoir for temporarily storing and discharging the discharged water of the membrane separation device to the cooling tower. The water treatment device according to any one of claims 9 to 15, wherein the supply device is provided with a supply for supplying the discharge water of the cooling tower to the membrane separation device.