JP2020040001A - Water treatment system, and water treatment method - Google Patents

Abstract

To provide a water treatment system and a water treatment method capable of achieving cost-reduction and improvement of the utilization rate, by decreasing the possibility of clogging of a RO membrane, even when the RO membrane is used in a highly alkaline environment.SOLUTION: The water treatment system according to an embodiment of the present invention, comprises a degassing device, a desalination unit, and bubble transferring means. The degassing device applies a degassing treatment to water to be treated, and acquires degassed water which is degassed water to be treated, and gas separated from water to be treated. The desalination unit applies a desalination treatment to degassed water to separate the degassed water into desalinated water of a decreased salt content prepared from the degassed water, and a concentrated water which is degassed water of an increased salt concentration. The bubble generating device generates bubbles by mixing and decompressing desalinated water and gas. The bubble transferring means transfers the bubbles to the desalination unit.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to a water treatment system and a water treatment method.

  In recent years, laws and regulations for realizing a sound water circulation have been strengthened. ZLD (Zero Liquid Discharge) regenerates and uses water in factories to reduce the risk of water pollution, regenerates and reuses wastewater, and further reduces wastewater discharged from factories to zero. This is a concept for preserving the water environment.

  In order to reduce wastewater to zero, it is necessary to finally separate the solid content and deionized water by an evaporation method. The evaporation method is a method in which wastewater is heated to generate steam, and the steam is cooled to obtain deionized water, thereby separating solid content and deionized water. In this method, a two-stage flash evaporation method, a multi-stage flash evaporation method, and the like have been put to practical use, and have the advantage of obtaining deionized water of extremely high purity. There is a disadvantage that efficiency is low. Therefore, from the viewpoint of energy consumption reduction, it is required to minimize the amount of wastewater treated by the evaporation method by increasing the concentration of wastewater as much as possible.

  For these reasons, a reverse osmosis (RO) membrane (hereinafter, referred to as an “RO membrane”) is used to separate concentrated wastewater containing solids and fresh water before the evaporation method. . In a desalination / concentration system using an RO membrane, water to be treated is introduced under pressure into the RO membrane, and deionized water, which is water permeated through the RO membrane, and concentrated, not permeated through the RO membrane. It consists of a basic process of obtaining water.

  The RO film has an effect of removing almost all of ionic substances, fine particles, organic substances, some dissolved gases, and the like, and does not require discontinuous processes such as regeneration unless clogging or trouble occurs. It is widely used from the viewpoint of goodness and the like.

  However, RO membranes can be clogged by silica, hardness scale, and biofouling.

  When the RO membrane is clogged, the entire water treatment system needs to be stopped in order to clean the RO membrane, so that the operation rate of the water treatment system decreases. In addition, since the concentrated water that has not been concentrated to the assumed concentration is subjected to the evaporation treatment, the heat energy required for the evaporation increases, and the overall treatment cost also increases.

  Clogging of the RO film with silica can be suppressed by using the RO film in a highly alkaline (eg, pH ≧ 10) environment in which most of the silica exists in an ionic state.

  However, controlling the pH does not reduce the likelihood of hardness scale or biofouling. In particular, in a highly alkaline environment, the generation of the hardness scale is accelerated, so that the risk of clogging of the RO film due to the hardness scale tends to be increased.

U.S. Pat.No. 6,537,456

  The problem to be solved by the present invention is to reduce both the possibility of clogging of the RO film and to reduce both the cost and the operation rate even when using the RO film in a highly alkaline environment. It is an object of the present invention to provide a water treatment system and a water treatment method that can be realized.

  The water treatment system according to the embodiment includes a deaerator, a desalination unit, and a bubble transfer unit. The degassing device performs degassing processing on the water to be treated, and obtains degassed water that is degassed water to be treated and gas degassed from the water to be treated. The desalination unit performs a desalination process on the degassed water, and converts the degassed water into demineralized water in which the salt content is reduced from the degassed water, and degasified water in which the salt content is concentrated. Separate into concentrated water. The bubble generation device generates bubbles by mixing demineralized water and gas and reducing the pressure. The bubble transfer means transfers the bubbles to the desalination unit.

It is a block diagram showing the schematic structure of the water treatment system to which the water treatment method of an embodiment was applied. It is a block diagram showing the example of composition of the water treatment system of a 1st embodiment. It is a conceptual diagram showing the example of composition of the introduction unit in the water treatment system of a 1st embodiment. It is a conceptual diagram showing the example of composition of the separation unit in the water treatment system of a 1st embodiment. It is a conceptual diagram showing the example of composition of the bubble generation device in a 1st embodiment. It is a flowchart (1/2) which shows the operation example of the water treatment system of 1st Embodiment. It is a flowchart (2/2) which shows the operation example of the water treatment system of 1st Embodiment. It is a block diagram showing the example of composition of the water treatment system of a 2nd embodiment. It is a block diagram showing the example of composition of the water treatment system of a 3rd embodiment. It is a key map showing the example of composition of the bubble generation device in a 3rd embodiment. It is a block diagram showing the example of composition of the water treatment system of a 4th embodiment. It is a block diagram showing the example of composition of the water treatment system of a 5th embodiment. It is a conceptual diagram showing the example of composition of the bubble generation device in a 5th embodiment. It is a block diagram showing the example of composition of the water treatment system of a 6th embodiment.

  FIG. 1 is a block diagram illustrating a schematic configuration of a water treatment system to which the water treatment method according to the embodiment is applied.

  That is, the water treatment system 100 includes the deaerator 20, the desalination unit 40, the bubble generator 60, the bubble transfer line 80, and the heat treatment device 90.

  The deaerator 20 performs a deaeration process on the water to be treated a such as, for example, factory wastewater, and is degassed from the deaerated water b that is the deaerated water to be treated a and the water to be treated a. A gas c such as carbon dioxide is obtained, and the deaerated water b is provided to the desalination unit 40 and the gas c is provided to the bubble generation device 60.

  The desalination unit 40 generally includes a plurality of RO membranes, and performs a desalination process on the deaerated water b provided from the deaerator 20 using the plurality of RO membranes. The water b is separated from the degassed water b into demineralized water d with reduced salt content and concentrated water e that is degassed water b with concentrated salt. Then, the desalinated water d is provided to the bubble generation device 60, and the concentrated water e is provided to the heat treatment device 90.

  The bubble generation device 60 mixes the demineralized water d provided from the desalination unit 40 and the gas c provided from the deaeration device 20 and reduces the pressure after mixing, thereby forming the bubbles f in the demineralized water d. generate.

  The bubble transfer line 80 is a line (for example, a pipe) from the bubble generation device 60 to the desalination unit 40. The bubble transfer line 80 is provided with a pump 82, and the desalinated water d including the bubbles f generated by the bubble generation device 60 is desalinated by being transferred in the bubble transfer line 80 by the pump 82. It is supplied to the unit 40. In addition, as shown in FIG. 2 described later, when an auxiliary unit such as the introduction unit 30 is provided before the desalination unit 40, the desalted water d including the bubbles f generated by the bubble generation device 60 is discharged. Instead of the desalination unit 40, the connection destination of the bubble supply line 80 may be changed so that it can be supplied to an auxiliary unit such as the introduction unit 30.

  In the technical field, a device for transferring a liquid, such as a pump, an airlift, a steam jet, and a siphon, is referred to as a transfer device. In the embodiment, an example is described in which a pump is applied as the transfer device. However, the pumps described herein may alternatively use other transfer equipment, such as airlifts, steam jets, siphons.

  The heat treatment apparatus 90 concentrates and evaporates and dries the concentrated water e provided from the desalination unit 40, thereby converting the concentrated water e from the salt g, which is a soluble solid content, the water content h, and the gaseous volatile component. Collect k. The salt g is disposed of as concentrated waste. The water h is returned to, for example, a factory from which the water to be treated a has been discharged as reclaimed water, and is reused. Volatile components k are released to the environment.

  Specific embodiments of the water treatment system 100 having such a schematic configuration will be described below. In the following description of each embodiment, the same portions as those shown in FIG. 1 will be denoted by the same reference numerals, and redundant description will be avoided.

(First embodiment)
The water treatment system according to the first embodiment will be described.

  FIG. 2 is a block diagram illustrating a configuration example of the water treatment system according to the first embodiment.

  The water treatment system 100a includes a pretreatment unit 10, an introduction unit 30, a desalination unit 40, a bubble generation device 60, a bubble transfer line 80, and a heat treatment device 90.

  The pretreatment unit 10 is a unit that performs a pretreatment including a solid content removal treatment, a water softening treatment, a deaeration treatment, and the like on the water to be treated a such as a factory wastewater. The apparatus includes a solid content removing device 12, a water softening device 14, and the above-described deaerator 20.

  A pump (not shown) is provided at the preceding stage of the solid content removing device 12, the water softening device 14, and the degassing device 20 as needed, respectively. The solid content removing device 12, the water softening device 14, and the degassing device are provided. In 20, the water to be treated a may be sent from the upstream side by a pump provided in each preceding stage.

  The solid content removing device 12 is realized by using a membrane separation technique such as a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, and an MBR (Membrane Bioreactor) method. Such a solid content removing device 12 filters the water to be treated a and removes solids from the water to be treated a. The to-be-processed water a1 from which the solid content has been removed is sent from the solid content removing device 12 to the water softening treatment device 14 by, for example, a pump (not shown) provided in the preceding stage of the water softening treatment device 14.

  The water softening device 14 is realized using, for example, an ion exchange resin, a coagulating sedimentation device, or the like. Such a water softening device 14 softens the water 1 to be treated by removing hardness components such as calcium and magnesium from the water to be treated a1 that has been sent. The water component a2 from which the hardness component has been removed and the water softened in this manner is deaerated from the water softening device 14 by, for example, a pump (not shown) provided upstream of the deaerator 20. The liquid is sent to the device 20.

As the deaerator 20, an existing deaerator used in the production of pure water or the like can be used. For example, the deaerator 20 is realized by using a packed decarbonation tower, an aeration device, a membrane deaerator, a vacuum deaerator, or the like. In any case, in order to improve the deaeration efficiency, an acid such as hydrochloric acid or sulfuric acid may be added to the water to be treated a2 to lower the pH of the water to be treated a7 to 7 or less, more preferably 5.5 or less. desirable. In the case of the gas-liquid contact type, the G / L ratio (N-m ³ / m ³ ) is preferably in the range of 5 to 20. In addition, the deaerator 20 can be realized using a known technique, and there is no limitation in application.

  Such a degassing device 20 performs deaeration processing on the water to be treated a2, and degassed water b that is the degassed water to be treated a2 and, for example, degassed from the water to be treated a2. A gas c such as carbon dioxide is obtained, and the degassed water b is supplied to the introduction unit 30 provided in front of the desalination unit 40, and the gas c is supplied to the bubble generation device 60.

  The introduction unit 30 is a facility for adjusting the deaerated water b introduced into the desalination unit 40.

  FIG. 3 is a conceptual diagram illustrating a configuration example of the introduction unit.

  As illustrated in FIG. 3, the introduction unit 30 includes a liquid mixing tank 31 for storing the degassed water b, liquid supply lines 32 and 34, a chemical liquid line 33, pumps 35 and 36, and a water quality meter 37. It has. Further, a bubble transfer line 80 is also guided to the liquid mixing tank 31.

  The liquid sending line 32 is, for example, a line such as a pipe for guiding the deaerated water b from the deaerator 20 to the liquid mixing tank 31.

  The pump 35 is provided in the liquid sending line 32 and sends the deaerated water b from the deaerator 20 to the liquid mixing tank 31.

  The chemical liquid line 33 is a pipe for supplying the chemical liquid m to the liquid mixing tank 31. The chemical liquid m contains, for example, a pH adjuster, a bactericide, a scale inhibitor, a biofouling inhibitor, a membrane cleaning agent, and the like. The chemical liquid m is properly used depending on, for example, the water quality measured by the water quality meter 37 and the material and performance of the RO membrane used in the desalination unit 40. The chemical liquid m can be further used depending on, for example, the time of steady operation and the time of maintenance.

  As the pH adjuster, for example, an alkaline agent such as caustic soda and potassium hydroxide is used. Thus, the introduction unit 30 sets the pH of the degassed water b in the liquid mixing tank 31 to 7 or more, preferably 8.5 or more, and more preferably 10.5 or more.

  In addition, a bubble transfer line 80 is also guided to the liquid mixing tank 31, and the desalinated water d containing the bubbles f from the bubble generation device 60 is transferred to the liquid mixing tank 31 via the bubble transfer line 80. .

  The water quality meter 37 includes a pH meter that measures the pH of the degassed water b stored in the liquid mixing tank 31. Further, it may include a water level meter for measuring the water level of the degassed water b stored in the liquid mixing tank 31, a conductivity meter for measuring the conductivity, and the like.

  The liquid sending line 34 is, for example, a pipe-like line for sending the degassed water b stored in the liquid mixing tank 31 to the desalination unit 40.

  The pump 36 has been detected by the water quality meter 37 that the water quality such as the pH of the degassed water b stored in the liquid mixing tank 31 has reached an appropriate value to be introduced into the desalination unit 40. In this case, the deaerated water b stored in the liquid mixing tank 31 is raised to a preset pressure and sent to the desalination unit 40.

  The preset pressure is a pressure higher than the osmotic pressure of the RO membrane 47 (the RO membrane 47A of the separation unit 41A described later) of the most upstream separation unit 41 in the desalination unit 40, and is about 0 to 3 MPa. It is suitable.

  The desalination unit 40 includes three separation units 41A, 41B, 41C arranged in series, and a final unit 49 commonly arranged downstream of each of the separation units 41A, 41B, 41C.

  Each of the separation units 41A, 41B, 41C and the final unit 49 includes a pressure vessel 42A, 42B, 42C, 42D, respectively. Further, RO membrane element portions 43A, 43B, 43C, 43D are arranged inside the pressure vessels 42A, 42B, 42C, 42D.

  The configuration of the desalination unit 40 is an example, and includes two separation units 41A and 41B arranged in series instead of the three separation units 41A, 41B and 41C arranged in series. May be adopted. Further, a configuration including more than three separation units 41A, 41B, 41C,... Arranged in series may be employed. Even in such a case, each separation unit 41 includes a pressure vessel 42 in which an RO membrane element 43 is disposed.

  FIG. 4 is a conceptual diagram illustrating a configuration example of the separation unit 41 according to the first embodiment.

  The configuration of the separation unit 41 shown in FIG. 4 is common to the configurations of the separation units 41A, 41B, 41C and the final unit 49. Therefore, hereinafter, the configurations of the separation units 41A, 41B, 41C and the final unit 49 will be collectively described with reference to FIG.

  As described above, the separation unit 41 includes the pressure vessel 42, and further, the RO membrane element unit 43 is disposed inside the pressure vessel 42. FIG. 4 shows an example in which the separation unit 41 includes one pressure vessel 42 and the pressure vessel 42 includes one RO membrane element unit 43 as an example. However, the number of pressure vessels 42 provided in each separation unit 41 is not limited to one, and may be plural. Further, the number of the RO membrane element portions 43 installed inside the pressure vessel 42 is not limited to one, and may be plural.

  The RO membrane element section 43 has an RO membrane 47 inside, and also has one introduction section 44 and two discharge sections 45 and 46.

  The introduction unit 44 converts the water to be treated supplied from the upstream side via the introduction line 50 (for example, in the case of the separation unit 41A, the deaerated water b sent from the introduction unit 30) into the RO membrane element unit 43. It is an entrance for introducing inside.

  As the RO membrane 47, for example, a membrane in a spiral shape or a hollow fiber shape is applied, and the water introduced from the introduction portion 44 is filtered, and the permeated water d that has passed through the RO membrane 47 and the permeated water that has passed through the RO membrane 47. Instead, it is separated into concentrated water e in which TDS (Total Dissolved Solid) is concentrated.

  The discharge unit 45 is an outlet for discharging the concentrated water e from the RO membrane element unit 43, and the discharge unit 46 is an outlet for discharging the permeated water d from the RO membrane element unit 43. The concentrated water e discharged from the discharge part 45 is guided to the separation unit 41 on the downstream side through the concentrated water line 52, and the permeated water d discharged from the discharge part 46 is converted into the final unit through the permeated water line 51. Guided to 49. In the example shown in FIG. 2, in the case of the most downstream separation unit 41, which is the separation unit 41C, the concentrated water e3 discharged from the discharge part 45C is guided to the heat treatment apparatus 90 via the concentrated water line 52C.

  According to the above-described configuration, in the case of the separation unit 41A, the deaerated water b that has been pressurized to a high pressure and introduced from the introduction unit 30 is supplied from the introduction unit 44A to the RO membrane element via the introduction line 50A. The permeated water introduced into the section 43A and transmitted through the RO membrane 47A is discharged as desalinated water d1 from the discharge section 46A to the final unit 49 via the permeated water line 51A, and the TDS is concentrated by the RO membrane 47A. The concentrated water e1 discharged is discharged from the discharge part 45A to the separation unit 41B via the concentrated water line 52A.

  The concentrated water line 52A is provided with a pump 48A, which pumps the concentrated water e1 flowing in the concentrated water line 52A to a pressure higher than the osmosis membrane of the RO membrane 47B of the separation unit 41B, preferably 3 The pressure is increased to about 8 MPa, and the solution is sent to the separation unit 41B.

  The separation unit 41B introduces the concentrated water e1 sent from the separation unit 41A in this way to the RO membrane element unit 43B via the introduction line 50B. The introduction line 50B is a line continuous from the concentrated water line 52A, and is defined as a concentrated water line 52A when viewed from the separation unit 41A side, and is defined as an introduction line 50B when viewed from the separation unit 41B side. You.

  Of the concentrated water e1 introduced into the RO membrane element unit 43B, the permeated water that has passed through the RO membrane 47B is discharged as demineralized water d2 from the discharge unit 46B to the final unit 49 via the permeated water line 51B. , RO film 47B causes concentrated water e2 in which TDS is further concentrated than concentrated water e1 to be discharged from discharge section 45B to separation unit 41C via concentrated water line 52B.

  The concentrated water line 52B is provided with a pump 48B. The pump 48B converts the concentrated water e2 flowing in the concentrated water line 52B to a pressure higher than that of the permeable membrane of the RO membrane 47C of the separation unit 41C, preferably 8 psi. The pressure is increased to about 12 MPa, and the solution is sent to the separation unit 41C. In addition, the TDS concentration of the concentrated water e2 is preferably 40,000 (mg / L) or more, and more preferably 80,000 (mg / L) or more.

  The separation unit 41C introduces the concentrated water e2 sent from the separation unit 41B into the RO membrane element unit 43C via the introduction line 50C. The introduction line 50C is a line continuous from the concentrated water line 52B, and is defined as a concentrated water line 52B when viewed from the separation unit 41B side, and is defined as an introduction line 50C when viewed from the separation unit 41C side. You.

  Of the concentrated water e2 introduced into the RO membrane element unit 43C, the permeated water that has passed through the RO membrane 47C is discharged as demineralized water d3 from the discharge unit 46C to the final unit 49 via the permeated water line 51C. And RO film 47C, concentrated water e3 in which TDS is further concentrated than concentrated water e2 is discharged from discharge section 45C to heat treatment apparatus 90 via concentrated water line 52C. The concentrated water line 52C is provided with a pump 48C. The pump 48C sends the concentrated water e3 discharged from the discharge unit 48C to the concentrated water line 52C to the heat treatment device 90.

  The permeate lines 51A, 51B, and 51C join before the final unit 49 to form the permeate line 51. Therefore, the desalted waters d1, d2, and d3 join in the permeated water line 51.

  The permeated water line 51 is provided with a pump 48D, and the desalinated water d flowing in the permeated water line 51 is reduced to a pressure higher than the permeable membrane of the RO membrane 47D of the final unit 49, preferably to about 0 to 2 MPa. The pressure is increased and the liquid is sent to the final unit 49 via the introduction line 50D.

  The final unit 49 introduces the supplied desalted water d into the RO membrane element 43D.

  In the final unit 49, when the fed demineralized water d permeates the RO membrane 47D, alkali components such as caustic soda and dissolved salts are further removed, resulting in deionized regenerated water i, which is not permeated through the RO membrane 47D. In d ′, the alkaline components such as caustic soda and dissolved salts are more concentrated than the supplied desalted water d.

  The final unit 49 separates the desalted water d into the regenerated water i and the desalted water d 'in this way. The reclaimed water i is returned, for example, to the factory that discharged the water to be treated a, and is reused. On the other hand, the desalinated water d 'is supplied to the bubble generator 60 via the concentrated water line 52D. A pump 53 is provided in the concentrated water line 52D, and the pump 53 sends the desalinated water d 'flowing in the concentrated water line 52D to the bubble generation device 60.

  The bubble generating device 60 mixes the demineralized water d ′ supplied through the concentrated water line 52D and the gas c supplied from the degassing device 20 and reduces the pressure after mixing, so that the inside of the demineralized water d ′ is reduced. Generates a bubble f.

  FIG. 5 is a conceptual diagram illustrating a configuration example of the bubble generation device 60 according to the first embodiment.

  A bubble generation device 60 illustrated in FIG. 5 is a Venturi-type bubble generation device, and includes a venturi tube 61 having a reduced and enlarged cross-sectional area, and a gas c from the deaerator 20 connected to the venturi tube 61. And a gas introduction line 62 for introduction into the bubble generation device 60.

  In the bubble generating device 60, the desalinated water d ′ from the final unit 49 is introduced into the venturi pipe 61 by the pump 53 via the concentrated water line 52 </ b> D. On the other hand, the gas c supplied from the deaerator 20 is introduced from the gas introduction line 62.

  The gas introduction line 62 is connected to the Venturi tube 61 on the upstream side of the nozzle portion 63 where the cross-sectional area of the Venturi tube 61 is minimized. As a result, the demineralized water d 'is mixed with the gas c and enters the nozzle section 63 in a state containing bubbles of the gas c.

  When the desalinated water d ′ passes through the nozzle portion 63 in a state containing bubbles of the gas c, the bubbles of the gas c expand due to rapid decompression, and the bubbles are finely pulverized by the subsequent rapid pressure recovery, and the bubbles are bubbled. f occurs.

  The desalinated water d 'including the bubbles f thus generated by the bubble generation device 60 is provided to the liquid mixing tank 31 via the above-described bubble transfer line 80. A pump 82 is provided in the bubble transfer line 80, and the pump 82 sends desalinated water d ′ containing bubbles f to the liquid mixing tank 31.

  The bubble f generated by the bubble generation device 60 is preferably a bubble having an average diameter of 1000 nm or less, called a fine bubble.

  Fine bubbles having an average diameter of 1000 nm or less have high stability in liquid and high permeability to the RO film 47, and enhance the effect of preventing scale and biofouling in the RO film 47. In addition, since the surface of the fine bubble is hydrophobic and charged, it becomes easy to attach a scale inhibitor, a biofouling inhibitor, a pH adjuster, a bactericide, and a membrane cleaning agent. Thereby, bubble stability and permeability to the RO membrane 47 can be enhanced, and the scale and the effect of preventing biofouling can be enhanced.

  Further, since the scale and the effect of preventing biofouling increase as the average diameter of the bubbles f decreases, the average diameter of the bubbles f is preferably 150 nm or less, which is even smaller.

  The bubble generating device 60 is not limited to the venturi type as illustrated in FIG. 5, but may be an ejector type that introduces a gas from the outside. In the ejector system, a gas c supplied from the deaerator 20 is suctioned by using a negative pressure generated by an amount of liquid passing through a narrow flow path at a high speed, and the suction gas is generated by cavitation generated by expansion of a downstream pipe. Are finely crushed to generate bubbles.

  In any of the venturi type and the cavitation type, if the bubble f is carbon dioxide, the sterilizing effect and the biofouling suppressing effect can be enhanced. Therefore, carbon dioxide is preferable as the type of the gas c.

  The heat treatment apparatus 90 includes, for example, an evaporative concentration apparatus, an evaporative drying apparatus, an organic substance heat treatment apparatus, and the like, and at least one or more of heat treatment processes such as distillation and recovery using heat, evaporative drying processing, incineration, and catalytic oxidation. Perform a heat treatment process. For example, when the main component of the ionic component in the concentrated water e3 is an organic amine such as an alkanolamine, the organic substance can be separated, concentrated, and disposed of by the heat treatment process of the organic substance heat treatment apparatus. In addition, heat-treated carbon is generated by the heat treatment process of the organic matter heat treatment apparatus, and moisture h is recovered.

  As described above, the heat treatment device 90 collects the salt g, the water content h, and the volatile component k, which are soluble solids, from the concentrated water e3 by performing the concentration / evaporation drying processing on the concentrated water e3. The salt g is disposed of as concentrated waste. The water h is returned to, for example, a factory from which the water to be treated a has been discharged as reclaimed water, and is reused. Volatile components k are released to the environment.

  For example, when the main component of the ionic component in the concentrated water e3 is an inorganic ionic component, the ionic component can be recovered as a solid salt g by the concentration / evaporation and drying treatment by the heat treatment device 90.

  Note that the heat treatment device 90 may be provided with a crystallization device, a centrifugal separator, or the like. This makes it possible to smoothly recover the solid salt g.

  Next, an operation example of the water treatment system 100a according to the first embodiment configured as described above will be described.

  6A and 6B are flowcharts illustrating an operation example of the water treatment system 100a according to the first embodiment.

  As an operation example of the water treatment system 100a according to the first embodiment, a case where treated water a such as factory wastewater is treated will be described.

  The water a to be treated, which is treated by the water treatment system 100a, is sent to the solid content removing device 12 of the pretreatment unit 10 by, for example, a pump, and is filtered by the solid content removing device 12 to remove the solid content (S1). . The water a1 from which solids have been removed is sent to the water softening device 14 by, for example, a pump.

  In the water softening device 14, hardness components such as calcium and magnesium are removed from the water to be treated a1. Thereby, the water 1 to be treated is softened (S2). The softened water a2 is sent to the deaerator 20 by, for example, a pump.

  In the deaerator 20, the deaeration process is performed on the water a 2, and the deaerated water b, which is the deaerated water of the water a 2, is pumped by the pump 35 into the liquid mixing tank 31 of the introduction unit 30. The gas c, for example, carbon dioxide, which has been sent to the water a2 and degassed from the water a2, is provided to the bubble generator 60 (S3).

  Thereby, the deaerated water b having a concentration of, for example, about 1000 mg / L to several thousand mg / L is supplied to the liquid mixing tank 31. In addition, the chemical liquid m is also supplied to the liquid mixing tank 31 from the chemical liquid line 33 as necessary. Further, the desalted water d 'including the bubbles f generated by the bubble generation device 60 in step S31 described later is also transferred to the liquid mixing tank 31 via the bubble transfer line 80. Thus, in the liquid mixing tank 31, the degassed water b is adjusted by being mixed with the chemical liquid m and the demineralized water d '(S4).

  The pH of the adjusted deaerated water b is measured by a water quality meter 37, and when it is detected that the pH is 7 or more, more preferably 8.5 or more, and still more preferably 10.5 or more, the pump 36 Through the liquid feed line 34 in a state where the pressure is increased to a pressure higher than the osmotic pressure of the RO membrane 47A of the separation unit 41A of the desalting unit 40, for example, about 0 to 3 MPa. The liquid is sent to the first-stage separation unit 41A (S5).

  The degassed water b sent to the separation unit 41A is introduced from the introduction part 44A into the RO membrane element part 43A through the introduction line 50A, and the permeated water that has passed through the RO membrane 47A is converted into demineralized water d1, The water is discharged from the discharge section 46A to the final unit 49 via the permeated water line 51A. On the other hand, the concentrated water e1 in which the TDS is concentrated without passing through the RO membrane 47A is discharged from the discharge part 45A (S6).

  The discharge part 45A is connected to the concentrated water line 52A. The concentrated water line 52A is provided with a pump 48A, and the concentrated water e1 flowing in the concentrated water line 52A is pumped by the pump 48A to a pressure higher than the osmosis membrane of the RO membrane 47B of the separation unit 41B, for example, up to 3%. The liquid is sent to the second-stage separation unit 41B in a state where the pressure is increased to about 8 MPa (S7).

  The concentrated water e1 sent to the separation unit 41B is introduced from the introduction part 44B to the RO membrane element part 43B via the introduction line 50B, and the permeated water that has passed through the RO membrane 47B is converted into demineralized water d2 as the discharge part 46B. Is discharged to the final unit 49 through the permeated water line 51B. On the other hand, the concentrated water e2, which does not pass through the RO membrane 47B and is more concentrated in TDS than the concentrated water e1, is discharged from the discharge unit 45B (S8).

  The discharge part 45B is connected to the concentrated water line 52B. Further, the concentrated water line 52B is provided with a pump 48B, and the concentrated water e2 flowing in the concentrated water line 52B is pumped by the pump 48B to a pressure higher than the osmosis membrane of the RO membrane 47C of the separation unit 41C, for example, by 8%. The liquid is sent to the third-stage separation unit 41C in a state where the pressure is increased to about 12 MPa (S9).

  The concentrated water e2 sent to the separation unit 41C is introduced from the introduction part 44C to the RO membrane element part 43C through the introduction line 50C, and the permeated water that has passed through the RO membrane 47C is converted into the desalted water d3 as the discharge part 46C. Is discharged to the final unit 49 through the permeated water line 51C. The TDS concentration of the concentrated water e2 is preferably 40,000 (mg / L) or more, more preferably 80,000 (mg / L) or more. On the other hand, the concentrated water e3, which does not pass through the RO membrane 47C and is more concentrated in TDS than the concentrated water e2, is discharged from the discharge unit 45C (S10).

  The discharge part 45C is connected to the concentration line 52C. The concentrated water line 52C is provided with a pump 48C, and the concentrated water e3 flowing in the concentrated water line 52C is sent to the heat treatment device 90 by the pump 48C (S11).

  The permeate lines 51A, 51B, and 51C join before the final unit 49 to form the permeate line 51. Therefore, the desalinated water d1, d2, and d3 obtained in steps S6, S8, and S10 merge in the permeated water line 51. The permeated water line 51 is provided with a pump 48D, and the combined desalinated water d is pressurized to a pressure higher than the osmosis membrane of the RO membrane 47D of the final unit 49, preferably to about 0 to 2 MPa. Is sent to the final unit 49 (S21).

  In the final unit 49, the fed desalted water d is introduced from the introduction part 44D to the RO membrane element part 43D via the introduction line 50D, and is separated into the regenerated water i and the desalted water d 'by the RO membrane 47D ( S22). That is, the demineralized water d becomes the regenerated water i from which the alkali components such as caustic soda and the dissolved salts have been further removed by permeating the RO membrane 47D, and the demineralized water d ′ which does not permeate the RO membrane 47D is supplied by Alkaline components such as caustic soda and dissolved salts are more concentrated than the salt water d.

  The reclaimed water i is returned, for example, to the factory from which the water a has been discharged, and is reused (S23). The desalted water d 'is provided from the final unit 49 to the bubble generator 60 via the concentrated water line 52D for step S31 described below (S24).

  In step S31, the gas c provided from the deaerator 20 in step S3 and the demineralized water d 'provided from the final unit 49 in step S24 are mixed in the bubble generation device 60, and the pressure is reduced after the mixing. As a result, desalinated water d ′ containing bubbles f such as fine bubbles having an average diameter of 1000 nm or less, preferably 150 nm or less is generated (S31).

  The desalted water d 'including the bubbles f thus generated by the bubble generation device 60 is transferred to the liquid mixing tank 31 via the bubble transfer line 80 in step S4.

  In this way, the degassed water b is supplied to the desalination unit 40 after being mixed with the bubbles f such as fine bubbles. Since fine bubbles have the effect of suppressing the scale deposition and the occurrence of biofouling in each RO film 47 of the desalination unit 40, the film blocking due to the scale and biofouling in the RO films 47A, 47B, 47C, and 47D is suppressed. Is done. As a result, the long-term operation of each of the separation units 41A, 41B, 41C and the final unit 49 becomes possible, thereby improving the operation rate.

  As a result, in the desalination unit 40, the concentration of TDS contained in the concentrated waters e1, e2, and e3 in each of the RO membranes 47A, 47B, and 47C is higher than in the related art. Thereby, for example, the TDS concentration of the concentrated water e3 sent to the heat treatment apparatus 90 in step S11 is set to an extremely high value, for example, 80,000 mg / L or more, preferably 100,000 mg / L or more. It becomes possible.

  In the heat treatment device 90, for example, the concentrated water e3 is subjected to, for example, a concentration / evaporation / drying process, whereby the salt g, the water h, and the volatile component k, which are soluble solids, are recovered from the concentrated water e3 ( S12). The higher the TDS concentration of the concentrated water e3, the smaller the amount of water contained in the concentrated water e3. Therefore, the heat energy consumed in the concentration / evaporation drying process in the heat treatment device 90 is also reduced. In the present embodiment, as described above, since the TDS concentration of the concentrated water e3 can be made higher than before, the amount of water contained in the concentrated water e3 also decreases, and the concentration / evaporation / drying performed in the heat treatment apparatus 90 is performed. The heat energy consumed for processing is reduced as compared to the prior art.

  The salt g recovered in step S12 is discarded (S13), the volatile component k is released to the environment (S14), and the moisture h is returned to the factory that discharged the for-treatment water a as regenerated water, It is reused (S15).

  As described above, according to the water treatment system of the present embodiment, the solid content, the hardness component, the carbonic acid component, and the like that cause clogging of the RO membranes 47 of the desalination unit 40 are removed from the pretreatment unit 10. In, the water can be removed from the water to be treated a in advance.

  Further, for example, a bubble f such as a fine bubble is generated in the bubble generator 60 and dissolved in the degassed water b, and then the degassed water b can be provided to the desalination unit 40. For example, a bubble f such as a fine bubble has an effect of suppressing scale deposition and biofouling from occurring in each RO film 47 of the desalination unit 40.

  Therefore, it is possible to reduce the possibility of clogging of each RO film 47 of the desalination unit 40, scale deposition, and occurrence of biofouling.

  When the clogging of the film, scale deposition, or biofouling occurs, the function of each RO film 47 is reduced, so that the clogging, scale, and biofouling are removed from the RO film 47 by washing or the like. In addition, the operation of the water treatment system 100a must be stopped. This results in a decrease in the operating rate of the water treatment system 100a.

  However, according to the water treatment system 100a of the present embodiment, clogging of the RO membrane 47, the possibility of scale deposition and the occurrence of biofouling are reduced, and the separation units 41A, 41B, 41C and the final The long-term operation of the unit 49 is made possible, so that the operation rate can be improved.

  In addition, since the long-term operation of each of the separation units 41A, 41B, and 41C and the final unit 49 has been enabled, the TDS enrichment of the concentrated waters e1, e2, and e3 obtained in each RO membrane 47 is calculated as follows. It becomes possible to increase it more than before.

  As a result, the TDS concentration in the concentrated water e3 provided from the RO membrane element 43C to the heat treatment device 90 becomes higher than before, and the amount of water contained in the concentrated water e3 is correspondingly reduced.

  By reducing the amount of water contained in the concentrated water e3, the heat energy consumed for the concentration and evaporative drying performed in the heat treatment device 90 is also reduced. This makes it possible to reduce costs.

  As described above, according to the water treatment system 100a of the present embodiment, even when the RO film 47 is used in a highly alkaline environment, the RO film 47 may be clogged due to fouling or the like. , The waste liquid can be concentrated to a high degree of concentration, thereby making it possible to realize both cost reduction and operation rate improvement.

(Second embodiment)
A water treatment system according to a second embodiment will be described.

  This embodiment is a modification of the first embodiment, and therefore, in the following description, the same parts as those in the first embodiment will be denoted by the same reference numerals, and redundant description will be avoided.

  FIG. 7 is a block diagram illustrating a configuration example of a water treatment system according to the second embodiment.

  That is, in the water treatment system 100b of the second embodiment, the bubble transfer line 80 from the bubble generation device 60 is connected not only to the introduction unit 30 but also to the solids removal device 12 of the pretreatment unit 10. The configuration is different from the water treatment system 100a.

  With such a configuration, in the water treatment system 100b, the desalinated water d ′ containing the bubbles f from the bubble generation device 60 is supplied not only to the introduction unit 30 but also to the solid content removal device 12 of the pretreatment unit 10. Is mixed with the water to be treated a, so that the bubbles f are dissolved in the water to be treated a.

  The water to be treated a is processed by the pretreatment unit 10 and becomes the deaerated water b and is sent to the liquid mixing tank 31 of the introduction unit 30. After being mixed with d ′, the solution is sent to the desalination unit 40.

  As described above, even in a configuration in which the bubbles f are transferred to both the fixed component removing device 12 and the liquid mixing tank 31, the generation of scale deposition and biofouling in each RO film 47 is suppressed, and therefore water Similarly to the water treatment system 100a, the treatment system 100b can realize both an improvement in operation rate and a reduction in cost.

(Third embodiment)
A water treatment system according to a third embodiment will be described.

  This embodiment is also a modification of the first embodiment, and therefore, in the following description, the same parts as those in the first embodiment will be denoted by the same reference numerals, and redundant description will be avoided.

  FIG. 8 is a block diagram illustrating a configuration example of a water treatment system 100c according to the third embodiment.

  That is, the water treatment system 100c of the third embodiment includes a bubble generation device 70 instead of the bubble generation device 60. The bubble generation device 70 uses air taken in from the surroundings without using the gas c from the degassing device 20 to generate the bubble f. The gas c from the deaerator 20 is released to the environment.

  FIG. 9 is a conceptual diagram illustrating a configuration example of the bubble generation device 70.

  The bubble generation device 70 illustrated in FIG. 9 also shows a venturi-type bubble generation device as in FIG. And a gas introduction line 62 for taking in.

  The desalinated water d 'from the final unit 49 is sent to the venturi tube 61 by the pump 53 via the concentrated water line 52D. On the other hand, air from the surroundings is introduced from the gas introduction line 62.

  The gas introduction line 62 is connected to the Venturi tube 61 on the upstream side of the nozzle portion 63 where the cross-sectional area of the Venturi tube 61 is minimized. As a result, the desalted water d is mixed with the air and enters the nozzle portion 63 in a state containing air bubbles.

  When the desalinated water d ′ passes through the nozzle portion 63 while containing air bubbles, the air bubbles expand due to rapid decompression, and the bubbles are finely pulverized by the subsequent rapid pressure recovery, and the bubbles f are formed. appear.

  The desalted water d 'including the bubbles f thus generated by the bubble generation device 70 is transferred to the liquid mixing tank 31 via the bubble transfer line 80 described above.

  Like the bubble f generated by the bubble generation device 60, the bubble f generated by the bubble generation device 70 is also a bubble called a fine bubble having an average diameter of 1000 nm or less, preferably 150 nm or less.

  As described above, even when the bubble f is generated by using air taken in from the surroundings instead of the gas c from the deaerator 20, the generation of scale deposition and biofouling in each RO film 47 is suppressed. Therefore, similarly to the water treatment system 100a, the water treatment system 100c can also achieve both improvement of the operation rate and cost reduction.

Note that the bubble generation device 70 uses air taken from an air cylinder or carbon dioxide taken from a carbon dioxide cylinder instead of using air taken from the surroundings as described above to generate the bubble f. May be used. In particular, the bubble f generated using the carbon dioxide taken in from the carbon dioxide cylinder has a higher CO ₂ content than the bubble f generated using the air. For this reason, when using the bubble f generated using the carbon dioxide taken in from the carbon dioxide cylinder, the sterilizing effect of the bubble becomes higher, and the biofouling suppressing effect can be further increased.

(Fourth embodiment)
A water treatment system according to a fourth embodiment will be described.

  This embodiment is a modification of the third embodiment, and therefore, in the following description, the same portions as those in the first and third embodiments will be denoted by the same reference numerals, and redundant description will be avoided.

  FIG. 10 is a block diagram illustrating a configuration example of a water treatment system according to the fourth embodiment.

  That is, in the water treatment system 100d of the fourth embodiment, the bubble transfer line 80 from the bubble generation device 70 is connected not only to the introduction unit 30 but also to the solids removal device 12 of the pretreatment unit 10. The configuration is different from the water treatment system 100c.

  With such a configuration, in the water treatment system 100c, the desalinated water d ′ containing the bubbles f from the bubble generation device 70 is transferred not only to the introduction unit 30 but also to the solids removal device 12 of the pretreatment unit 10. Is mixed with the water to be treated a, so that the bubbles f are dissolved in the water to be treated a.

  The water to be treated a is treated by the pretreatment unit 10, becomes the degassed water b, and is transferred to the liquid mixing tank 31 of the introduction unit 30. After being mixed with d ′, the solution is sent to the desalination unit 40.

  As described above, even in a configuration in which the bubbles f generated using air are transferred to both the fixed component removing device 12 and the liquid mixing tank 31, scale deposition and biofouling of each RO film 47 can be performed. Since the generation is suppressed, the water treatment system 100d can also achieve both an improvement in operation rate and a reduction in cost, similarly to the water treatment system 100a.

(Fifth embodiment)
A water treatment system according to a fifth embodiment will be described.

  This embodiment is also a modification of the first embodiment, and therefore, in the following description, the same parts as those in the first embodiment will be denoted by the same reference numerals, and redundant description will be avoided.

  FIG. 11 is a block diagram illustrating a configuration example of a water treatment system 100e according to the fifth embodiment.

  That is, the water treatment system 100e of the fifth embodiment includes a bubble generation device 75 instead of the bubble generation device 60. The gas c from the deaerator 20 is released to the environment. The bubble generation device 75 generates bubbles f by reducing the pressure of the desalted water d.

  FIG. 12 is a conceptual diagram illustrating a configuration example of the bubble generation device 75.

  The bubble generation device 75 illustrated in FIG. 12 is also a Venturi-type bubble generation device, and includes a Venturi tube 61 having a reduced and enlarged cross-sectional area. The portion where the cross-sectional area is reduced is the nozzle portion 63.

  The desalinated water d 'from the final unit 49 is sent to the venturi tube 61 by the pump 53 via the concentrated water line 52D.

  When the demineralized water d 'passes through the nozzle portion 63, the gas dissolved in the demineralized water d' expands due to rapid decompression, and bubbles are generated, and the bubbles are finely pulverized by the subsequent rapid pressure recovery. A bubble f occurs.

  The desalted water d 'including the bubbles f thus generated by the bubble generating device 75 is transferred to the liquid mixing tank 31 via the above-described bubble transfer line 80.

  Like the bubble f generated by the bubble generation device 60, the bubble f generated by the bubble generation device 75 is also a bubble called a fine bubble having an average diameter of 1000 nm or less, preferably 150 nm or less.

  As described above, even when the bubble f is generated by using the gas dissolved in the demineralized water d ′ instead of the gas c from the deaerator 20, scale deposition or biofouling in each RO film 47 is performed. Since the occurrence of the ring is suppressed, the water treatment system 100e can also achieve both an improvement in the operation rate and a reduction in cost, similarly to the water treatment system 100a.

(Sixth embodiment)
A water treatment system according to a sixth embodiment will be described.

  This embodiment is a modification of the fifth embodiment, and therefore, in the following description, the same portions as those of the first and fifth embodiments are denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 13 is a block diagram illustrating a configuration example of a water treatment system according to the sixth embodiment.

  That is, in the water treatment system 100f of the sixth embodiment, the bubble transfer line 80 from the bubble generation device 75 is connected not only to the introduction unit 30 but also to the solids removal device 12 of the pretreatment unit 10. The configuration is different from the water treatment system 100e.

  With such a configuration, in the water treatment system 100f, the desalinated water d ′ containing the bubbles f from the bubble generation device 75 is supplied not only to the introduction unit 30 but also to the solids removal device 12 of the pretreatment unit 10. Is mixed with the water to be treated a, so that the bubbles f are dissolved in the water to be treated a.

  The water to be treated a is treated by the pretreatment unit 10, becomes the degassed water b, and is transferred to the liquid mixing tank 31 of the introduction unit 30. After being mixed with d ′, the solution is sent to the desalination unit 40.

  As described above, even if the bubble f generated by utilizing the gas dissolved in the demineralized water d 'is transferred to both the fixed component removing device 12 and the liquid mixing tank 31, each RO membrane Since the occurrence of scale deposition and biofouling in the process 47 is suppressed, the water treatment system 100f can also achieve both an improvement in operation rate and a reduction in cost, similarly to the water treatment system 100a.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

  10 pre-treatment unit, 12 solid removal device, 14 softening device, 20 degassing device, 30 introduction unit, 31 liquid mixing tank, 32 liquid feed line, 33 ... chemical liquid line, 34 ... liquid sending line, 35 ... pump, 36 ... pump, 37 ... water quality meter, 40 ... desalting unit, 41 ... separation unit, 49 ... final unit, 42 ... · Pressure vessel, 43 · · · RO membrane element section, 44 · · · introduction section, 45 · · · discharge section, 46 · · · discharge section, 47 · · · RO membrane, 48 · · · pump, 50 · · · introduction line, 51 · · · Permeated water line, 52 concentrated water line, 53 pump, 60 bubble generator, 61 venturi tube, 62 gas introduction line, 63 nozzle section, 70 bubble generator, 75 ..Bubble generator, 80.Bubble transfer Inn, 82 ... pumps, 90 ... heat treatment apparatus, 100 ... water treatment system.

Claims (10)

A deaeration process is performed on the water to be treated, and degassed water that is the degassed water to be treated, and a deaerator that acquires gas degassed from the water to be treated,
The degassed water is subjected to a desalination treatment, and the degassed water is demineralized water in which the salt content is reduced from the degassed water, and the degassed water in which the salt content is concentrated is the degassed water. A desalination unit that separates into water;
By mixing and depressurizing the demineralized water and the gas, a bubble generation device that generates bubbles,
The bubble transfer means for transferring the bubble to the desalination unit,
Water treatment system with.   The water treatment system according to claim 1, further comprising a water softening treatment device that performs a water softening treatment on the water to be treated before being provided to the degassing device.   The water treatment system according to claim 2, further comprising a solid content removing device that removes a solid content from the water to be treated before being provided to the water softening device.   The water treatment system according to claim 3, wherein the bubble transfer unit further supplies the bubble generated by the bubble generation device to the solid content removing device.   The heat treatment apparatus according to any one of claims 1 to 4, further comprising a heat treatment device that recovers salt and water from the concentrated water by subjecting the concentrated water separated by the desalination unit to an evaporative drying process. Water treatment system. The desalination unit includes a plurality of separation units arranged in series, and a final unit commonly arranged on the downstream side of each of the plurality of separation units,
Among the plurality of separation units, the separation unit disposed on the most upstream side performs a desalination process on the degassed water obtained by the deaerator, and removes the degassed water from the degassed water. Demineralized water with reduced salt content from steam water, and separated into concentrated water with more concentrated salt than the degassed water, providing the demineralized water to the final unit, the concentrated water on the downstream side To the separation unit located in
Each of the separation units disposed on the downstream side separates the concentrated water provided from the separation unit disposed on the upstream side into demineralized water having reduced salt content, and concentrated water having further concentrated salt content. Providing the demineralized water to the final unit, and providing the retentate to a downstream downstream separation unit;
The final unit, by concentrating the demineralized water provided from each of the plurality of separation units, to obtain concentrated demineralized water and demineralized water with reduced salt content, the concentrated demineralized water, The water treatment system according to any one of claims 1 to 5, wherein the water treatment system is provided to the bubble generation device. The deaerated water obtained by the deaerator is provided with an introduction unit for adjusting before being introduced into the desalination unit, between the deaerator and the desalination unit,
The water treatment system according to claim 1, wherein the bubble transfer unit transfers the bubble to the introduction unit instead of transferring the bubble to the desalination unit.   The bubble generation device has a function of taking in air, and instead of the gas obtained by the degassing device, generates the bubble by mixing the air taken in by the function with the demineralized water and depressurizing the air. The water treatment system according to any one of claims 1 to 7.   The bubble generator, the demineralized water, without mixing with the gas obtained by the deaerator, by reducing the pressure of the demineralized water, to generate the bubbles from the gas dissolved in the demineralized water, The water treatment system according to claim 1. Using a degassing device, performing degassing treatment on the water to be treated, and obtaining degassed water that is the degassed water to be treated and gas degassed from the water to be treated. When,
Using a reverse osmosis membrane, the degassed water is subjected to a desalination treatment, and the degassed water is demineralized water having reduced salt content from the degassed water, and the salt is concentrated. A step of separating into concentrated water that is deaerated water,
Mixing the demineralized water and the gas and reducing the pressure to generate bubbles,
Mixing the bubble with the degassed water before the desalination treatment by the reverse osmosis membrane;
A step of separating the concentrated water into salt and water by evaporative concentration treatment using a heat treatment apparatus,
A water treatment method comprising: