JP6305368B2 - Water treatment method and apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for reusing backwash wastewater, washing wastewater, circulating water, concentrated water, etc. of a membrane separator, and more particularly to a water treatment method and apparatus suitable for recovering cooling tower blow water.

  Scale failure occurs on heat transfer surfaces and piping that come into contact with water such as cooling water systems and boiler water systems. In particular, from the standpoint of resource saving and energy saving, when high concentration operation is performed with less discharge (blow) of cooling water outside the system, dissolved salts are concentrated and the heat transfer surface is likely to corrode. At the same time, it becomes a sparingly soluble salt and scales. If the scale adheres to the wall surface of the apparatus, a serious obstacle occurs in the operation of the boiler and heat exchanger, such as a decrease in thermal efficiency and blockage of piping. In recent years, for the purpose of saving water and saving energy, the movement of effectively using water as much as possible has become remarkable. However, in the case of further highly concentrated operation, there is a limit in suppressing the precipitation of scale.

  Therefore, after cooling water blow water is passed through the MF membrane or UF membrane to remove turbidity in the blow water, RO membrane treatment is performed to remove ions, organic substances, etc., and return to the cooling tower (patent) References 1, 2).

JP2002-18437 JP2003-1255

  In the method of performing the recovery process using the MF membrane, UF membrane, and RO membrane, it is necessary to clean the membrane regularly or irregularly. In Patent Documents 1 and 2, since the backwash drainage and the like at the time of washing are discharged out of the system, the water recovery rate is low accordingly. Moreover, when draining backwash water, circulating water, concentrated water, washing waste water, etc., out of the system, waste water treatment may be required depending on the quality of the water.

  An object of this invention is to provide the method and apparatus which process the backwash waste_water | drain, membrane waste_water | drain, concentrated water, and circulating water of a membrane separator, and use them as cooling water of a cooling tower.

Water treatment method of the present invention is to provide a blow water cooling tower to the membrane separation unit supplies the permeate of the membrane separation device to the cooling tower, a part of the membrane separator water discharged from the membrane separation unit Or a water treatment method for supplying the whole to the cooling tower, wherein the membrane separation device includes a pretreatment membrane device and a reverse osmosis membrane device, and the pretreatment membrane device is at least a microfiltration membrane or an ultrafiltration membrane. The membrane separation device discharge water is at least one of backwash waste water, circulating water, concentrated water, and chemical washing waste water from the pretreatment membrane device, and the circulating water is the pretreatment membrane device. Water discharged when performing a water injection step or a circulation step for filling the housing with water at the start of operation or after the back-flushing step, the membrane separation device discharge water is directly discharged from the membrane separation device. It supplies to the said cooling tower, It is characterized by the above-mentioned.

The water treatment device of the present invention comprises a membrane separation device, means for supplying cooling tower blow water to the membrane separation device, means for supplying permeated water of the membrane separation device to the cooling tower, and the membrane separation device. some or all of the membrane separator water discharged from a water treatment device provided with means for supplying to the cooling tower, the membrane separation device comprises a pretreatment membrane device and the reverse osmosis membrane apparatus, The pretreatment membrane device has at least a microfiltration membrane or an ultrafiltration membrane, and the drainage water of the membrane separation device is at least backwash wastewater, circulating water, concentrated water, and chemical washing wastewater from the pretreatment membrane device. The circulating water is water discharged when performing a water injection step or a circulation step for filling the housing with water at the start of operation of the pretreatment membrane device or at the time of the air venting after backwashing. The membrane separator discharge water is supplied directly from the membrane separator to the cooling tower. It is an feature.

  In one aspect of the present invention, the cooling tower includes a filtration device for circulating and filtering at least a part of the cooling water.

  In the present invention, it is preferable that the membrane separator discharge water is filtered and then supplied into the cooling tower. In this case, it is preferable to perform the filtration treatment with a filtration device for circulating and filtering at least a part of the cooling water provided in the cooling tower.

  In one aspect of the present invention, the cooling tower is connected to a water supply pipe for supplying water to a filtration device for circulating and filtering at least a part of the cooling water from the cooling tower, and the membrane separator discharge water is supplied to the water supply pipe. It is supplied to the vicinity of the pipe or the water supply pipe connection in the cooling tower.

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

  In the water treatment method of the present invention, at least one of backwash waste water, wash waste water and concentrated water of membrane separation devices installed in various water treatment lines is supplied to the cooling tower and used as cooling water. Recovery rate is improved. In particular, the cooling tower blow water is treated with a membrane separation device and reused as cooling water, and at least one of backwash waste water, washing waste water, circulating water and concentrated water of this membrane separation device is used as cooling water. Thus, the water recovery rate of the cooling tower can be increased.

  In one embodiment of the present invention, blow water is filtered with an MF membrane or a UF membrane, and then treated with an RO membrane for deionization and organic matter removal treatment. This RO treated water is used as cooling water for a cooling tower. In addition, the MF membrane or UF membrane backwash wastewater, circulating water, concentrated water, and RO membrane washwater are filtered and supplied to the cooling tower. By performing this filtration process with a filtration device for circulating and filtering at least a part of the cooling water installed in the cooling tower system, existing equipment can be used.

It is a flowchart which shows the water treatment method and apparatus which concern on embodiment. It is a flowchart which shows the water treatment method and apparatus which concern on embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 shows a cooling tower system to which the method and apparatus of the present invention are applied.

  The cooling tower 1 of this cooling tower system is cooled in contact with the air introduced from the louver 1c while the cooling water sprinkled from the sprinkling pipe 1a flows down the filler layer 1b, and the pit 1d (lower part of the cooling tower) The air that is stored in the water tank and contains the steam is exhausted to the atmosphere by the fan 1e. The cold water in the pit 1d of the cooling tower 1 is supplied to the heat exchanger 4 via the pump 2 and the pipe 3, and the return water from the heat exchanger 4 is returned to the water spray pipe 1a of the cooling tower 1 via the pipe 5. The

  Further, a part of the water in the pit 1d is supplied to the side filter 14 through the water supply side circulation pipe 11, the pump 12, and the valve 13 and filtered, and then is returned through the return side circulation pipes 15 and 17 and the valve 16. Is returned to the pit 1d. The side filter 14 includes a filtration device such as a floating filter or a sand filter using a floating filter medium. Backwashing air can be introduced into the pipe 15 via an air pump 19 and a valve 18. A backwash drain discharge pipe 14 having a valve 14 a is connected to the primary side of the side filter 14.

  When the side filter 14 is filtering, the valves 13 and 16 are open and the valves 14a and 18 are closed. When the side filter 14 is back-air washed, the valves 13 and 16 are closed, the valves 14b and 18 are opened, air is supplied from the air pump 19 to the side filter 14, and the backwash waste water is discharged through the pipe 14b. Is done.

The cooling tower 1 is supplied with make-up water from the make-up water line 8 so that the water level in the pit 1d is always at a predetermined level by the ball tap valve device 7 (or a water supply valve device with a level sensor).

  When the electrical conductivity of the cooling water in the pit 1d exceeds a predetermined value, the blow valve 21 is opened, and a part of the cooling water having a high salt concentration is discharged through the pipe 22 as blow water. . In this embodiment, blow water is sent to the water treatment device 25 via the pump 23 and the pipe 24. Moreover, if water can be fed by gravity, the pump 23 becomes unnecessary. The configuration of the water treatment device 25 will be described later.

  By the way, in the cooling tower 1, in order to remove the heat of the process, a part of the circulating water evaporates and the makeup water is concentrated. Concentrated cooling water is affected by the occurrence of scale and slime, which deteriorates the heat exchange efficiency of the heat exchanger. Therefore, chemicals such as a dispersant and an anti-slime agent are added to prevent them.

  Dispersants include inorganic polyphosphoric acids such as sodium hexametaphosphate and sodium tripolyphosphate, phosphonic acids such as hydroxyethylidene diphosphonic acid and phosphonobutane tricarboxylic acid, carboxyl group-containing materials such as maleic acid, acrylic acid, and itaconic acid. Depending on this, it is possible to use a vinyl monomer having a sulfonic acid group such as vinyl sulfonic acid, allyl sulfonic acid, 2-methacrylamide-2-methylpropane sulfonic acid, or a copolymer combining nonionic vinyl monomers such as acrylamide. However, materials other than those listed here can also be applied. Further, as the third component of the dispersant, a terpolymer can be used by using other components. For example, N-tert-butylacrylamide is used as the third component.

  Among these, as a dispersant, a polymer containing HAPS (3-allyloxy-2-hydroxy-1-propanesulfonic acid), AMPS (2-acrylamido-2-methylpropanesulfonic acid) and acrylic acid and / or methacrylic acid Most preferably.

  The molecular weight of the dispersant is preferably 1,000 or more and 30,000 or less. If the molecular weight is less than 1,000, a sufficient dispersion effect cannot be obtained, and if it exceeds 30,000, it may be removed by the pretreatment film. The present invention is also characterized in that the cooling water chemical contained in the cooling tower blow water is reused as a chemical for the reverse osmosis membrane, and the above-mentioned dispersant, the slime inhibitor described later and the like are effectively used.

  Anti-slime agents include hypochlorites such as sodium hypochlorite (NaClO), chlorine agents such as chlorine gas, chloramine, and chlorinated isocyanurates, chlorine such as monochlorosulfamic acid, amide sulfate, and amide sulfate groups. Bonded chlorinating agent (stabilized chlorinating agent) reacted with a compound having a bromide such as dibromohydantoin, brominated agent such as monobutylsulfamic acid, conjugated sulfuric acid or amide sulfate group, and a combined bromine agent (stabilized bromine agent) ), DBNPA (dibromonitrilopropion acid), MIT (methylisothiazolone), and other organic agents can be applied.

  In the bound chlorine agent and bound bromine agent, the nitrogen compound to which free chlorine and free bromine bind is ammonia or its compound, melamine, urea, acetamide, sulfamide, cyclolamic acid, sulfamic acid, toluenesulfonamide, succinimide, Examples thereof include phthalimide, isocyanuric acid, N-chlorotoluenesulfonamide, uric acid, saccharin, and salts thereof. The combined chlorine agent used in the present invention is a compound in which free chlorine is bonded to these nitrogen compounds. Examples of such bonded chlorinating agents include chloramine, chlorinated oxidant and chloramic acid compound, chloramine-T (sodium salt of N-chloro-4-methylbenzenesulfonamide), chloramine-B. (Sodium salt of N-chloro-benzenesulfonamide), sodium salt of N-chloro-paranitrobenzenesulfonamide, trichloromelamine, sodium salt or potassium salt of mono- or di-chloromelamine, trichloro-isocyanurate, mono- or 5, sodium salt or potassium salt of di-chloroisocyanuric acid, sodium salt or potassium salt of mono- or di-chlorosulfamic acid, monochlorohydantoin or 1,3-dichlorohydantoin, 5,5-dimethylhydantoin - alkyl derivatives. The bonded bromine is the same except that the chlorine part is bromine.

  Moreover, as a chemical | medical agent which changes pH, hydrochloric acid, a sulfuric acid, nitric acid, sodium hypochlorite, sodium hydroxide, a citric acid, an oxalic acid etc. can be selected, for example. There are no restrictions on the material.

  Among these, one or more kinds of chemicals are preferably used. In addition, it is preferable to control the injection amount by measuring the concentration of the slime inhibitor in the cooling tower. Further, it is preferable to measure the pH of the cooling tower and control it within a certain range.

  Next, the water treatment device 25 for treating blow water will be described.

The blow water from the cooling tower removes coarse turbidity and foreign matters with a filter 30 such as a strainer, and then a slime inhibitor and a pH adjuster such as sulfuric acid are added to the tank 31 and then a pretreatment membrane device 33. Then, turbidity treatment is performed. The water that has not permeated the membrane 33m is introduced into the water supply side circulation pipe 11 through the pipe 34. The water that has not permeated is preferably returned directly into the pit 1 d (cooling tower lower water tank), or may be returned to the tank 31. The permeated water of the membrane 33m is supplied to the RO membrane device 38 through the valve 35, the tank 36, and the pipe 37, and deionization processing is performed. The deionized treated water is returned to the cooling tower 1 via the pipe 39. The RO treated water may be returned to the makeup water line 8 or may be returned to the circulation pipes 11, 15, 17, etc. to the side filter 14 .

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

  The RO membrane device 38 is intermittently flushed or chemically cleaned using alkali or acid. The washing waste water at this time is also collected through the pipe 42.

  The filter 30 such as the strainer can be operated without it, but is preferably installed because the pretreatment membrane device 33 may be damaged. An auto strainer that performs a washing process automatically is preferably used. The shape of the strainer is not particularly limited, and any shape such as a Y shape or a bucket shape can be used. The strainer preferably has a pore diameter of 100 to 500 μm. If it is less than 100 μm, the strainer is severely blocked, which is not preferable. When the thickness exceeds 500 μm, there is a high possibility that coarse turbidity or foreign matter that has passed through the strainer may damage the pretreatment film. A filter such as a thread winding filter or a pleated filter may be used in place of the strainer, but the strainer is more preferable in view of the replacement frequency and cleaning properties.

  The pretreatment membrane device 33 is for removing turbidity and colloidal components in water that cause membrane contamination of the RO membrane device 38, and an MF membrane or a UF membrane can be used. There is no particular limitation on the membrane type, and a hollow fiber type, spiral type membrane filtration device or the like can be employed. Moreover, there is no restriction | limiting also in the filtration system, Any system of internal pressure filtration, external pressure filtration, crossflow filtration, and total amount filtration is applicable. The molecular weight cutoff of the MF membrane and the UF membrane is preferably 30,000 or more. If it is less than 30,000, the dispersant is removed, which is not preferable. The upper limit of the molecular weight cut off is not particularly limited, but it is preferably 1,000,000 or less because it is possible to remove macromolecular polysaccharides and the like that can cause the RO membrane to be clogged in the cooling water. A water injection process and a circulation process for filling the housing with water, such as at the start of operation of the pretreatment membrane device and the air venting process after backwashing, are carried out. Through the water supply side circulation pipe 11 and directly to the pit 1d.

  As the slime inhibitor and the pH adjuster that can be used in the pretreatment film device 33, the same type as that used in the cooling tower can be used. By using the same type, it can be used effectively in the cooling tower. In the case where a combined chlorine agent and a combined bromine agent are used in the cooling tower, the combined chlorine agent (stable in the cooling tower) can be obtained by using free chlorine and free bromine in the pretreatment membrane device 33. The amount of free chlorine originally required to be added in the cooling tower can be reduced.

  The pretreatment membrane device 33 performs backwashing treatment periodically or irregularly, and discharges turbidity accumulated in the membrane 33m to the outside of the system. The backwash frequency is generally about once every 10 to 60 minutes, but is not limited thereto. Hypochlorous acid and salts thereof, or hypobromite and salts thereof, organic chlorine-based fungicides, bonded chlorine-based fungicides, bonded bromine-based fungicides, and slime control agents during backwashing The effect of recovery can be improved by adding backwashing or carrying out backwashing by changing the pH.

  In order to perform this back washing, in this embodiment, the membrane permeated water in the tank 36 is used. That is, when the membrane 33m is backwashed, the valves 32 and 35 are closed, the valves 52 and 54 are opened, the pump 50 is operated, and the water in the tank 36 is moved to the secondary side of the membrane 33m via the pipes 51 and 53. Supply. At this time, a chemical such as NaC1O may be added to the pipe 53 to perform chemical cleaning. Backwash waste water is supplied from the pipe 34 to the pipe 11 (the suction side of the pump 12). Note that air backwashing may be performed instead of water backwashing. Also in this case, the backwash waste water is collected through the pipe 34. Also, immersion cleaning can be performed by adding a chemical such as NaClO to the primary side of the film together with backwashing. The washing waste water at this time is also returned to the water supply side circulation pipe 11 or directly to the pit 1d through the pipe 34.

  The type of the RO membrane 38m of the RO membrane device 38 is not particularly limited and is appropriately determined depending on the quality of the circulating cooling water to be treated (the quality of the raw water supplied to the circulating cooling water system or the concentration ratio in the circulating cooling water system). The salt rejection is preferably 80% or more, particularly 85% or more. If the desalting rate is worse than this, the deionization efficiency is poor, and treated water (permeated water) with good water quality cannot be obtained. As a material, a film of any material such as a polyamide composite film or a cellulose acetate film can be used, but a polyamide composite film is preferably used from the viewpoint of the removal rate. The shape is not particularly limited, and either a hollow fiber type or a spiral type can be used.

  An anti-slime agent is preferably added to the water supply of the RO membrane device 38. In the case of a polyamide composite film, a bonded chlorine agent, bonded bromine agent, and organic agent are preferably used as the slime inhibitor. The chlorinating agent and bromine agent described above are not preferable because there is a concern of film deterioration. In addition, this process can also be made unnecessary by sharing a cooling water chemical | medical agent, a dispersing agent, and a slime prevention agent. Further, in this embodiment, the pH adjuster is added in the tank 31, but depending on the type of the dispersant, the polymer may block the pretreatment film, so it is not in the front stage of the pretreatment film device, It is preferable to add a pH adjuster (for example, sulfuric acid) to the RO water supply.

  As described above, by returning the backwash wastewater and concentrated water to the pipe 11, turbid components in the backwash wastewater and concentrated water can be removed by the side filter 14, and the concentration of turbidity in the cooling water system and the increase in concentration are prevented. It becomes possible. In addition, when the side filter 14 is not provided, you may make it provide a filtration apparatus separately in a return line.

  It is preferable that the total amount of water per hour returned to the cooling tower, the circulating water, the washed water, and the concentrated water and the amount of water retained in the cooling water treatment system is 1: 100 or more. That is, the amount of water retained in the cooling tower when returning the backwash waste water and the concentrated water is preferably 100 times or more the return amount. If the amount of water is 100 times or more, the increase in concentration can be suppressed to a low level at the time of return, and a problem-free level can be obtained. Moreover, when returning backwash waste water and concentrated water, in order to prevent the water quality fluctuation | variation of a cooling water, you may install a pH measuring device, an adjusting device, a chlorine measuring device, and an adjusting device.

  In this invention, although the tank is provided in the water treatment apparatus which processes blow water, these are not necessary. In the present invention, as shown in FIG. 2, in order to level the inflow load, the backwash waste water, concentrated water, circulating water, and wash waste water are once stored in the water tank 55 and quantitatively measured through the pump 56 and the pipe 57. Then, it may be returned to the pipe 11 or the cooling tower.

  The water quality of backwash waste water, circulating water, wash waste water or concentrated water may be detected by a sensor, and if the concentration exceeds a specified concentration, recovery may not be performed.

  As described above, in this embodiment, backwash wastewater, circulating water, concentrated water, and chemical solution wastewater from the pretreatment membrane device 33 are collected. Flushing waste water, chemical cleaning waste water, and circulating water from the RO membrane device 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 may be used, and all of these washing means, concentrated water, and the like are to be collected. The washing wastewater may be supplied to the cooling tower via a line branched from the drainage line, or may be supplied directly to the cooling tower side via the supply line. The same applies to the concentrated water, and it may be branched from the circulation line and supplied to the cooling tower, or all of the concentrated water may be supplied to the cooling tower.

  In the above embodiment, concentrated water, backwash drainage, and the like are returned to the circulation water supply pipe 11 to the side filter 14, but may be returned to other locations, for example, directly into the pit 1d, for example, the pit 1d. It is good also in the connection part vicinity of the piping 11 in. By arranging the return destination near the connection portion of the pipe 11 of the pit 1d, that is, in the vicinity of the suction port, when water containing turbidity enters the pit, it is immediately sent to the side filter 14 through the pipe 11 for processing. It will be. Moreover, you may return via the piping 3 depending on the water quality.

  In the said embodiment, although the water treatment apparatus for collection | recovery is equipped with the filter 30, the pretreatment membrane apparatus 33, such as a UF membrane apparatus, and the RO apparatus 38, a filter, UF membrane, MF membrane, One or any combination of two or more nanofiltration membranes and RO membranes may be used.

  In this invention, it is preferable that the turbid mass of backwash waste water, circulating water, wash waste water, and concentrated water is less than 1000 degrees. Although the turbidity of the backwash wastewater instantaneously becomes about 300 degrees at maximum, it is reduced to 1 degree or less by performing filtration. The pH of the backwash waste water, circulating concentrated water, and wash waste water is preferably 2-12.

In the above embodiment, the cooling tower blow water is processed and recovered by the membrane separator, but even in the waste water of the membrane processing equipment such as water and waste water installed in factories, plants, etc. If there is what can be applied as cooling tower feed water, it may be treated by the water treatment device 25 and used as cooling water for the cooling tower 1. However, if it is cooling tower blow water, there is an advantage that it is easy to apply because the turbid content in the washing waste water is the same component.
In addition, in the said embodiment, although it sends to the water treatment apparatus via the blow piping 22, it can also send from the position of the feed piping 3 and the return piping 5 to a heat exchanger using the pressure of the pump 2. .

[Example 1]
A cooling tower blowwater recovery process that is performed at a concentration factor of 3.5 times in a cooling tower with a circulating water volume of 5,000 m ³ / h and a retained water volume of 1,000 m ³ / h using Chiba industrial water as raw water. went.

For the treatment of the cooling water with a dispersant, a copolymer of acrylic acid and AMPS (70:30) and a dispersant with an average weight molecular weight of 10,000 were used. The dispersant retention concentration in the initial system was 3 mg / L. The slime control treatment used a mixture of alkali, sulfamic acid, and hypochlorous acid described in WO11 / 125762. The initial bond chlorine concentration in the system was adjusted and added so as to be 1.0 mg / L. A light filter manufactured by Kurita Kogyo was installed as a side filter in the cooling tower, and filtration was performed at 150 m ³ / h to remove a predetermined amount of turbidity in the system.

The flow of the recovery process was a strainer, an MF apparatus, and an RO apparatus as shown in the water treatment apparatus 25 of FIG. 1, and the entire amount of blow water amount 20 m ³ / h was recovered. The strainer mesh used was 400 μm, and the MF membrane used was Kuraray Puree GS (hydrophilic PVDF, pore size 0.02 μm, external pressure type). As the RO membrane, KROA-2032-SN (polyamide ultra-low pressure RO membrane) was used. The frequency of backwashing of the MF apparatus was 30 minutes, and sodium hypochlorite was added at 100 mg / L during backwashing. The backwash water of the MF apparatus was returned to the cooling tower. By returning the backwash water of the MF apparatus, the water recovery rate became 100%. The amount of backwash water per one time was 1 m ³ .

The pH of the blow water was 8.5 to 8.7, but sulfuric acid was added in front of the RO device so that the pH was 5.5. Every three months, the RO device was washed with a sodium hydroxide solution adjusted to pH 11 as the amount of water in the RO device decreased, and the washed liquid was returned to the cooling tower. The amount of water in the cleaning liquid was 4 m ³ . The water recovery rate of the RO device remained at 70 to 75%. By the collection of backwash water and washing waste water, the washing process did not affect the water recovery rate, and the total water recovery rate was 70 to 75%.

  The turbidity at the time of backwashing was removed by the side filter, and the turbidity was stably changed at 5 to 7 degrees. Moreover, the sodium hypochlorite added at the time of backwashing was consumed in the cooling tower, and chlorine concentration changed with 0.1-0.2 mg / L. The combined chlorine concentration changed from 0.8 to 1.0 mg / L.

[Comparative Example 1]
The same treatment as in Example 1 was performed except that the MF device backwash wastewater and the RO membrane washwater were discharged out of the system and not returned to the cooling tower. The water recovery rate of the MF membrane was 90%, and the water recovery rate of the RO device was 68-73%. Therefore, the total water recovery rate was 61-65%.

  Moreover, reduction treatment and pH neutralization treatment are required to discharge backwash wastewater and wash wastewater out of the system.

[Example 2]
The same processing as in Example 1 was performed in the same cooling tower system as in Example 1 except that the side filter 14 was not installed in the cooling tower system. As a result, the turbid mass in the system gradually increased and became 50 ° C. or more in 10 days, so the treatment was stopped.

[Example 3]
The same treatment as in Example 1 was performed except that the amount of water held in the cooling tower was 100 m ³ . There was no effect of returning the MF backwash water. However, when the RO washing waste water was returned, the pH fluctuated and CaCO ₃ scale was deposited in the system, so the return was stopped.

[Discussion]
As mentioned above, according to the processing method and the processing apparatus of the circulating cooling water of the present invention, the water recovery rate can be increased by returning the backwash waste water and the cleaning waste water during the recovery process to the cooling tower. Eliminating wastewater treatment, it is economically superior and stable treatment is possible with a high recovery rate.

DESCRIPTION OF SYMBOLS 1 Cooling tower 4 Heat exchanger 14 Side filter 25 Water treatment apparatus 30 Filter 33 Pretreatment membrane apparatus 38 RO membrane apparatus

Claims (6)

Supplying a blowing water cooling tower to the membrane separation device, supplying the permeate of the membrane separation device is supplied to the cooling tower, a part or all of the membrane separator water discharged from the membrane separation unit to the cooling tower A water treatment method for
The membrane separation device includes a pretreatment membrane device and a reverse osmosis membrane device, and the pretreatment membrane device has at least a microfiltration membrane or an ultrafiltration membrane,
The drainage water of the membrane separation device is at least one of backwash waste water, circulating water, concentrated water, and chemical cleaning wastewater from the pretreatment membrane device, and the circulating water is used when the pretreatment membrane device starts operation or Water discharged when performing a water injection process or a circulation process for filling water in the housing during the air venting process after backwashing,
A water treatment method, wherein the water discharged from the membrane separator is supplied directly from the membrane separator to the cooling tower.   The water treatment method according to claim 1, wherein the cooling tower includes a filtration device for circulating and filtering at least a part of the cooling water. In claim 1, the cooling tower is connected to a water supply pipe for supplying water from the cooling tower to a filtration device for circulating and filtering at least a part of the cooling water.
A water treatment method, characterized in that the membrane separator discharge water is supplied to the vicinity of the water supply pipe connection in the cooling tower. A membrane separator;
A means for supplying blow water of the cooling tower to the membrane separation device, a means for supplying permeated water of the membrane separation device to the cooling tower, and a part or all of the water discharged from the membrane separation device from the membrane separation device a water treatment apparatus provided with means for supplying to the cooling tower,
The membrane separation device includes a pretreatment membrane device and a reverse osmosis membrane device, and the pretreatment membrane device has at least a microfiltration membrane or an ultrafiltration membrane,
The drainage water of the membrane separation device is at least one of backwash waste water, circulating water, concentrated water, and chemical cleaning wastewater from the pretreatment membrane device, and the circulating water is used at the start of operation of the pretreatment membrane device or Water discharged when performing a water injection process or a circulation process for filling water in the housing during the air venting process after backwashing,
Water discharged from the membrane separator is directly supplied to the cooling tower from the membrane separator. 5. The water treatment apparatus according to claim 4 , wherein the cooling tower includes a filtration device for circulating and filtering at least a part of the cooling water. In claim 4 , the cooling tower is connected to a water supply pipe for supplying water from the cooling tower to a filtration device for circulating and filtering at least a part of the cooling water.
A water treatment apparatus, wherein the water discharged from the membrane separator is supplied to the vicinity of the water supply pipe connection in the cooling tower.

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