JP2012196634A - Method and system for treatment of water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treatment of water, capable of inhibiting fouling of a reverse osmosis (RO) membrane without deironing and acid addition, and of maintaining favorable water permeating performance over a long term.SOLUTION: The water treatment method includes: an iron modification process of modifying a raw water W1 containing iron particulates as an impurity in a cation-exchange resin bed tower; a first division process by a reverse osmosis membrane, of dividing the modification-treated water W2 into a permeated water W5 and a concentrated water W6; and a deaeration process of the permeated water W5. The cation-exchange resin bed tower is operated by including a modification process of producing the modified water W2 by making the raw water W1 pass through the cation-exchange resin bed, and a regeneration process of making a regeneration liquid W3 pass through the resin bed. In the regeneration process, the resin bed is regenerated by supplying the aqueous solution of an alkali metal salt, and in the modification process after regeneration, the linear velocity to the resin bed is set to be 5-60 m/h to make water to flow without the deironing and acid addition treatments.

Description

  The present invention relates to a water treatment method and a water treatment system using a reverse osmosis membrane separation device.

  Conventionally, high-purity pure water (purified water) that does not contain impurities is used in semiconductor manufacturing processes, electronic component cleaning, medical instrument cleaning, and the like. This type of pure water is generally produced by treating raw water such as ground water or tap water with a reverse osmosis membrane (hereinafter also referred to as “RO membrane”).

  In a water treatment system using an RO membrane, when iron (typically insoluble colloidal iron) is contained in the raw water, this iron deposits on the membrane surface of the RO membrane, which is called fouling. A phenomenon occurs, and the salt removal rate and the amount of permeated water decrease. For this reason, it is common to perform pre-processing with an iron removal device.

  For example, a water treatment system that can cope with various operation variations by independently controlling a pretreatment block including an iron removal device and a water supply treatment block including an RO membrane device has been proposed (patent) Reference 1).

JP 2009-112921 A

  The iron removal apparatus described above is a facility that adds an oxidizing agent to raw water to insolubilize and remove iron. However, if the oxidant remains in the water supplied to the RO membrane, the membrane itself deteriorates. Therefore, it is necessary to provide an activated carbon filtration device for removing the residual oxidant after the iron removal device. Therefore, in the conventional water treatment system, it is inevitable that the pretreatment with respect to the supplied water becomes complicated and the cost of water production increases.

  In addition, it may be possible to suppress fouling in the RO membrane by adding an acid to the raw water to ionize all the colloidal iron, but this treatment may cause deterioration of the quality of the permeated water. That is, the addition of the acid promotes the change of hydrogen carbonate ions or carbonate ions contained in the raw water to free carbonic acid, so that the produced free carbonic acid permeates the RO membrane.

  Therefore, the present invention is a water treatment that can suppress fouling occurring in the RO membrane and maintain good water permeation performance over a long period of time without performing iron removal treatment and acid addition treatment as pretreatment. It is an object to provide a method and a water treatment system.

  The present invention provides raw water having a total iron concentration of 0.2 mg Fe / L or less, a weight ratio of 0.45 μm or more of iron fine particles occupying the whole iron fine particles of 80% or more, and a pH of 5.5 to 8.5. An iron reforming process for reforming in the cation exchange resin bed tower, and a treated water reformed in the iron reforming process is separated into permeated water and concentrated water by the first reverse osmosis membrane module. A reverse osmosis membrane separation step, and a deaeration treatment step of degassing the permeated water obtained in the first reverse osmosis membrane separation step with a gas separation membrane module. A modification process for producing soft water by passing raw water through a cation exchange resin bed having a length of 300 to 1500 mm; passing the regenerated solution through the cation exchange resin bed, Driven including regeneration process to regenerate In the regeneration process, an aqueous solution of an alkali metal salt is supplied to regenerate the cation exchange resin bed, while in the reforming process after the regeneration process, the cation is removed without removing the raw water and adjusting the pH. The present invention relates to a water treatment method in which a linear velocity with respect to an exchange resin bed is set to 5 to 60 m / h and water is passed.

Moreover, it is preferable to include a deionization process step of deionizing the treated water degassed in the deaeration process step with an electrodeionization module, an ion exchange resin mixed bed tower or a cation exchange resin single bed tower.
Moreover, it is preferable to include a second reverse osmosis membrane separation step in which the treated water degassed in the deaeration treatment step is further separated into permeated water and concentrated water by the second reverse osmosis membrane module.
Moreover, it is preferable to include a deionization treatment step of deionizing the permeated water obtained in the second reverse osmosis membrane separation step with an electrodeionization module, an ion exchange resin mixed bed tower or a cation exchange resin single bed tower. .
Further, in the regeneration process, a partial counter-current with a regeneration liquid amount of 1 to 6 eq / LR with respect to a hardness leak prevention bed set at a depth of 100 mm with the bottom of the cation exchange resin bed as a base point. It is preferable to perform regeneration.

  In the present invention, the total iron concentration is 0.2 mg Fe / L or less, the weight ratio of 0.45 μm or more of iron fine particles to the whole iron fine particles is 80% or more, and the pH is 5.5 to 8.5. An iron reformer that reforms raw water with a cation exchange resin bed tower, and a treated water that is reformed with the iron reformer is separated into permeated water and concentrated water by a first reverse osmosis membrane module. A first reverse osmosis membrane separation device, a deaeration treatment device for degassing the permeated water obtained by the first reverse osmosis membrane separation device with a gas separation membrane module, and the cation exchange resin bed tower A softening process for producing soft water by passing raw water through a cation exchange resin bed having a depth of 300 to 1500 mm; the cation exchange resin bed by passing a regenerated solution through the cation exchange resin bed Switch to playback process Effective valve means, regeneration solution supply means for supplying an aqueous solution of an alkali metal salt as a regeneration solution to the cation exchange resin bed in the regeneration process, and raw water removal treatment in the reforming process after the regeneration process Further, the present invention relates to a water treatment system comprising: raw water supply means configured to pass water by setting a linear velocity with respect to the cation exchange resin bed to 5 to 60 m / h without adjusting pH.

Moreover, it is preferable to provide the electrodeionization module, the ion exchange resin mixed bed tower, or the cation exchange resin single bed tower which deionizes the treated water deaerated by the said deaeration processing apparatus.
Moreover, it is preferable to provide the 2nd reverse osmosis membrane separation apparatus which isolate | separates the treated water deaerated by the said deaeration processing apparatus into a permeated water and concentrated water further by a 2nd reverse osmosis membrane module.
Moreover, it is preferable to provide the electrodeionization module, the ion exchange resin mixed bed tower, or the cation exchange resin single bed tower which deionizes the permeate obtained with the said 2nd reverse osmosis membrane separator.
In addition, the valve means is partially applied with a regenerative liquid amount of 1 to 6 eq / LR with respect to a hardness leak prevention floor set to a depth of 100 mm with the bottom of the cation exchange resin bed as a base point. It is preferable to be configured to be switchable to a regeneration process for performing stream regeneration.

  According to the present invention, water treatment capable of suppressing fouling occurring in the RO membrane and maintaining good water permeation performance over a long period of time without performing iron removal treatment and acid addition treatment as pretreatment. A method and water treatment system can be provided.

1 is an overall configuration diagram of a water treatment system 1 according to a first embodiment. 1 is a schematic cross-sectional view of an iron reforming device 3. FIG. 4 is a flowchart of a process executed by the control unit 10. (A)-(c) is explanatory drawing which shows the basic process performed by the control part 10. FIG. It is a whole block diagram of the water treatment system 1A which concerns on 2nd Embodiment. It is a whole block diagram of the water treatment system 1B which concerns on 3rd Embodiment.

(First embodiment)
First, the water treatment system 1 which concerns on 1st Embodiment of this invention is demonstrated, referring drawings. The water treatment system 1 is applied to, for example, a pure water production system that produces pure water from fresh water. FIG. 1 is an overall configuration diagram of a water treatment system 1 according to the first embodiment. FIG. 2 is a schematic cross-sectional view of the iron content reforming apparatus 3. FIG. 3 is a flowchart of a process executed by the control unit 10. 4A to 4C are explanatory diagrams illustrating a basic process executed by the control unit 10.

As shown in FIG. 1, the water treatment system 1 according to the present embodiment includes a raw water pump 2, an iron reforming device 3, a salt water tank 4, a reverse osmosis membrane separation device 5, a deaeration treatment device 6, And a control unit 10. The water treatment system 1 includes a raw water line L1, a treated water line L2, a salt water line L3, a drainage line L4, water flow lines L5 and L7, and a concentrated water line L6.
The “line” in the present specification is a general term for lines capable of flowing a fluid such as a flow path, a radial path, and a pipeline.

  The upstream end of the raw water line L1 is connected to a supply source (not shown) of the raw water W1. On the other hand, the downstream end of the raw water line L1 is connected to a process control valve 32 (described later) of the iron reforming device 3.

  The raw water W1 to be purified using the water treatment system 1, that is, the raw water W1 supplied to the raw water line L1, contains insoluble colloidal iron as a contaminant component, and the total iron concentration is 0.2 mgFe / L or less, In addition, the weight ratio of 0.45 μm or more of iron fine particles to the whole iron fine particles is 80% or more and the pH is 5.5 to 8.5. In general, water such as industrial water, groundwater (shallow well water, deep well water, spring water or underground water, etc.) and surface water (river water or lake water, etc.) often contains colloidal iron derived from the water source. It can be a processing target in the processing system 1. In addition, although tap water rarely contains colloidal iron, it can be a treatment target in the water treatment system 1 when it contains iron due to corrosion of water pipes or the like.

The pH of the raw water W1 can be measured using a commercially available pH electrode. The total iron concentration of the raw water W1 can be measured according to the quantification of iron according to JIS K0101 “Industrial Water Test Method”. Furthermore, the weight ratio of the iron fine particles in the raw water W1 can be measured by the following method (the same applies to the treated water W2).
(1) Using a membrane filter having a pore diameter of 0.45 μm, the sample liquid of raw water W1 is filtered at a pressure of 2.1 kg / cm ² (= 0.206 MPa) for 30 seconds, and the filtrate is collected.
(2) For each of the sample liquid and the filtrate, the total iron concentration is measured according to JIS K0101 “Industrial Water Test Method” iron quantification.
(3) The total iron concentration of the sample solution is A [mgFe / L], the total iron concentration of the filtrate is B [mgFe / L], and the capture rate of iron in the membrane filter is obtained by the following equation.
Capture rate [%] = (A−B) / A × 100
This capture rate is defined as “weight ratio of iron fine particles of 0.45 μm or more in the whole iron fine particles”. For example, when the total iron concentration of the sample liquid is 0.2 mg Fe / L and the total iron concentration of the filtrate is 0.04 mg Fe / L, the weight ratio is (0.2−0.04) /0.2×100= It is calculated as 80 [%].

  The raw water pump 2 is provided in the raw water line L1. The raw water pump 2 pumps the raw water W <b> 1 supplied from the supply source toward the iron reformer 3. The raw water pump 2 is electrically connected to a control unit 10 (described later) via a signal line (not shown). Operation (drive and stop) of the raw water pump 2 is controlled by the control unit 10.

  The raw water line L1 is provided with a raw water flow valve (not shown). The raw water flow valve opens and closes the raw water line L1. In the raw water flow valve, the valve body drive unit is electrically connected to the control unit 10 via a signal line (not shown). The opening and closing of the raw water flow valve is controlled by the control unit 10.

  The raw water line L1, the raw water pump 2, the raw water flow valve (not shown), and the raw water flow meter (or timer) (not shown) constitute raw water supply means in the water treatment system 1.

  In addition, the raw water line L1, the raw water pump 2, and the raw water flow valve (not shown) are used for the raw water W1 in the reforming process ST1 after the second regeneration process ST5 described later, without subjecting the raw water W1 to iron removal treatment and acid addition treatment. It also functions as raw water supply means for passing water by setting the linear velocity of the reformer 3 to the cation exchange resin bed 311 (described later) to 5 to 60 m / h.

  The iron reformer 3 passes the raw water W1 having the above water quality through a cation exchange resin bed 311 (described later), and the weight ratio of iron fine particles of 0.45 μm or more to the whole iron fine particles is 30% or less. It is the equipment which manufactures the treated water W2 reformed. That is, the iron content reformer 3 is a facility for the purpose of changing the particle size distribution by refining the fine iron particles contained in the raw water W1. The weight ratio of the iron fine particles of the treated water W2 can be measured by the same method as the weight ratio of the iron fine particles of the raw water W1 described above.

  As shown in FIG. 2, the iron content reformer 3 is mainly composed of a pressure tank 31 as a cation exchange resin bed tower and a process control valve 32 as a valve means. Since the iron reformer 3 has a cation exchange resin bed 311 (described later), when the raw water W1 contains hardness components (calcium ions and magnesium) and iron ions, these contaminant components are removed. , Softened treated water W2 can be obtained.

  The pressure tank 31 is a bottomed cylindrical body having an opening at the top, and the opening is sealed with a lid member. Inside the pressure tank 31, a cation exchange resin bed 311 made of cation exchange resin beads and a support bed 312 made of filtered gravel are accommodated.

  The cation exchange resin bed 311 functions as a treatment material for refining the iron fine particles contained in the raw water W1. The cation exchange resin bed 311 is stacked on the support bed 312 inside the pressure tank 31. The depth D1 of the cation exchange resin bed 311 is set in the range of 300 to 1500 mm.

  The support bed 312 functions as a fluid rectifying member for the cation exchange resin bed 311. The support floor 312 is accommodated on the bottom side of the pressure tank 31.

  In the pressure tank 31, a top screen 321 for preventing the cation exchange resin beads from flowing out is provided on the top of the cation exchange resin bed 311. The top screen 321 is connected to various lines constituting the process control valve 32 via a first flow path (not shown).

  The liquid distribution position and the liquid collection position by the top screen 321 are set near the top of the cation exchange resin bed 311. The top screen 321 functions as a top liquid distribution unit provided at the top of the cation exchange resin bed 311 and a top liquid collection unit provided at the top of the cation exchange resin bed 311.

  In the pressure tank 31, a bottom screen 322 for preventing the cation exchange resin beads from flowing out is provided at the bottom of the cation exchange resin bed 311. The bottom screen 322 is connected to various lines constituting the process control valve 32 through a second flow path (not shown).

  The liquid distribution position and the liquid collection position by the bottom screen 322 are set near the bottom of the cation exchange resin bed 311. The bottom screen 322 functions as a bottom liquid distribution unit provided at the bottom of the cation exchange resin bed 311 and a bottom liquid collection unit provided at the bottom of the cation exchange resin bed 311.

  In the pressure tank 31, an intermediate screen 323 for preventing the cation exchange resin beads from flowing out is provided at an intermediate portion in the depth direction of the cation exchange resin bed 311 above the reforming region 313 (described later). It has been. The intermediate screen 323 is connected to various lines constituting the process control valve 32 via a third flow path (not shown).

  The liquid collection position by the intermediate screen 323 is set near the intermediate part of the cation exchange resin bed 311. The intermediate part screen 323 functions as an intermediate part liquid collection part provided in the intermediate part of the cation exchange resin bed 311.

  The process control valve 32 includes various lines and valves therein. The process control valve 32 passes at least the raw water W1 through the cation exchange resin bed 311 in a downward flow to produce the treated water W2, and the raw water W1 in the reforming process ST1; The salt water W3 in the first regeneration process ST3 in which the downward flow of the salt water W3 is generated by collecting at the bottom while being distributed to the top of the cation exchange resin bed 311 to regenerate the entire cation exchange resin bed 311. And, after the first regeneration process ST3, the salt water W3 is collected to the bottom of the cation exchange resin bed 311 and collected at an intermediate portion to generate an upward flow of the salt water W3, thereby producing a cation exchange resin. The flow of the salt water W3 in the second regeneration process ST5 for regenerating a part of the floor 311 can be switched.

  In the modification process ST1 in the present embodiment, the total iron concentration is 0.2 mg Fe / L or less, the weight ratio of 0.45 μm or more of iron fine particles occupying the whole iron fine particles is 80% or more, and the pH is 5.5-8. .5 is performed as an iron content reforming process in which the cation exchange resin bed 311 reforms the raw water W1.

  The regeneration process in the present embodiment includes a first regeneration process ST3 and a second regeneration process ST5 performed after the end of the first regeneration process ST3. The first regeneration process ST3 is a cocurrent regeneration process in which the entire cation exchange resin bed 311 is regenerated. The second regeneration process ST5 is a partial countercurrent regeneration process in which a part of the cation exchange resin bed 311 is regenerated. The regeneration of the cation exchange resin bed 311 in this embodiment is operated by a two-stage regeneration process. Specifically, the operation is performed by executing the cocurrent regeneration process as the first regeneration process, and executing the partial countercurrent regeneration process as the second regeneration process after the completion of the first regeneration process.

  In a second regeneration process ST5 described later, as shown in FIG. 2, with respect to a modified region 313 (described later) in which the depth D2 is set to 100 mm with the bottom (that is, the bottom) of the cation exchange resin bed 311 as a base point. Then, the salt water W3 is supplied in such an amount that the regeneration level is 1 to 6 eq / LR. Here, the regeneration level refers to the amount of the regenerant used for regenerating the unit volume ion exchange resin. Further, when sodium chloride is used as a regenerant, 1 eq corresponds to 58.5 g.

  The modified region 313 is a cation in order to reliably produce treated water W2 in which the weight ratio of 0.45 μm or more of iron fine particles occupying the entire iron fine particles is modified to 30% or less in the modification process ST1. This is an area that needs to be sufficiently regenerated in the exchange resin bed 311. The depth of the reforming region 313 may be 100 mm, and at least the limited region is regenerated at a predetermined regeneration level, so that the treated water W2 modified to the target water quality can be stably obtained. . In addition, when the raw | natural water W1 contains a hardness component, the modification | reformation area | region 313 functions also as a process area | region which reduces the amount of hardness leaks of the treated water W2 to the limit.

  Further, the process control valve 32 collects the raw water W1 with respect to the cation exchange resin bed 311 at the bottom while distributing the raw water W1 to the top of the cation exchange resin bed 311 after the first regeneration process ST3. A flow of raw water W1 in the first extrusion process ST4 that generates a downward flow of the raw water W1 and pushes out the introduced salt water W3; and after the second regeneration process ST5, the raw water W1 is moved to the bottom of the cation exchange resin bed 311 While the liquid is being distributed, an upward flow of the raw water W1 is generated by collecting at the intermediate portion, and the flow of the raw water W1 in the second extrusion process ST6 for pushing out the introduced salt water W3 can be switched.

  The process control valve 32 is connected to the upstream end of the drain line L4. From the drainage line L4, salt water W3 and raw water W1 used in the regeneration process, extrusion process, and the like are discharged as drainage W4.

  Further, in the process control valve 32, the valve body drive section provided therein is electrically connected to the control section 10 via a signal line (not shown). Switching of the valve in the process control valve 32 is controlled by the control unit 10.

Here, each process carried out in the iron content reformer 3 will be described.
In the water treatment system 1 of the present embodiment, the control unit 10 to be described later performs the following processes ST1 to ST8 shown in FIG. 3 by switching the flow path of the process control valve 32.
(ST1) A reforming process (iron reforming process) in which the raw water W1 is passed from the top to the bottom with respect to the entire cation exchange resin bed 311.
(ST2) Reverse washing process in which raw water W1 as washing water is passed from bottom to top with respect to the whole cation exchange resin bed 311 (ST3) Salt water W3 as a regenerating solution is given to the whole cation exchange resin bed 311 First regeneration process (ST4) that passes from top to bottom Raw water W1 as extrusion water passes from top to bottom with respect to the entire cation exchange resin bed 311. Salt water as regeneration liquid. Second regeneration process in which W3 passes mainly from the bottom to the top of the modified region 313 of the cation exchange resin bed 311 (ST6) The raw water W1 as the extrusion water is mainly modified region of the cation exchange resin bed 311 2nd extrusion process (ST7) which passes from bottom to top with respect to 313 Rinsing process which passes raw water W1 as rinsing water from top to bottom with respect to cation exchange resin bed 311 (ST8) rehydration process of supplying the raw water W1 as makeup water to the brine tank 4

  Next, an operation method of the reforming process ST1, the first regeneration process ST3, and the second regeneration process ST5 which are main processes among the processes ST1 to ST8 will be described.

  In the reforming process ST1, as shown in FIG. 4A, the raw water W1 is distributed from the top screen 321, and the raw water W1 is passed through the entire cation exchange resin bed 311 in a descending flow. Water W2 is produced. The produced treated water W2 is collected from the bottom screen 322.

In the reforming process ST1 after the second regeneration process ST5, which will be described later, the raw water W1 is passed through the cation exchange resin bed 311 with a linear velocity set to 5 to 60 m / h without performing iron removal treatment and acid addition treatment. Water. The linear velocity of the fluid such as the raw water W1 is obtained by dividing the fluid flow rate by the cross-sectional area of the cation exchange resin bed 311 and is represented by the following equation.
Linear velocity [m / h] = flow rate [m ³ / h] ÷ cross-sectional area [m ² ]

  In the first regeneration process ST3, as shown in FIG. 4 (b), salt water W3 is distributed from the top screen 321, and the salt water W3 is passed through the entire cation exchange resin bed 311 in a downward flow. The cation exchange resin bed 311 is regenerated. In the first regeneration process ST3, the salt water W3 is passed through the cation exchange resin bed 311 at a linear velocity of 0.7 to 2 m / h. The used salt water W3 obtained by regenerating the cation exchange resin bed 311 is collected from the bottom screen 322. In the first regeneration process ST3, the entire cation exchange resin bed 311 is regenerated by cocurrent regeneration.

  In 1st extrusion process ST4 implemented after completion | finish of 1st reproduction | regeneration process ST3, as shown in FIG.4 (b), raw water W1 is distributed from the top screen 321, and with respect to the whole cation exchange resin bed 311. Then, the raw water W1 is passed in a downward flow, and the salt water W3 introduced into the cation exchange resin bed 311 is pushed out. The raw water W1 that has passed through the cation exchange resin bed 311 is collected from the bottom screen 322.

  In the first regeneration process ST3 and the first extrusion process ST4, cocurrent regeneration is performed on the entire cation exchange resin bed 311. Therefore, the entire amount of the cation exchange resin bed 311 is regenerated almost uniformly, so that in the reforming process ST1, the sampled amount of the treated water W2 is increased to the maximum.

  In the second regeneration process ST5, as shown in FIG. 4 (c), the salt water W3 is distributed from the bottom screen 322, and the salt water W3 is passed through the cation exchange resin bed 311 in an upward flow. The lower region including the modified region 313 of the exchange resin bed 311 is regenerated. The salt water W3 regenerated in the lower region including the modified region 313 of the cation exchange resin bed 311 is collected from the intermediate screen 323. In the second regeneration process ST5, an amount of salt water W3 that provides a regeneration level of 1 to 6 eq / LR is supplied to the reforming region 313 set at the bottom of the cation exchange resin bed 311. In the second regeneration process ST5, the lower region including the modified region 313 of the cation exchange resin bed 311 is mainly regenerated by partial countercurrent regeneration.

  By performing the first regeneration process ST3 and the second regeneration process ST5, in the subsequent reforming process ST1, the total iron concentration is 0.2 mg Fe / L or less, and the iron fine particles of 0.45 μm or more occupying the entire iron fine particles When raw water having a weight ratio of 80% or more and a pH of 5.5 to 8.5 was supplied, the weight ratio of 0.45 μm or more of iron fine particles in the whole iron fine particles was modified to 30% or less. The treated water W2 can be manufactured reliably and stably.

  In the second extrusion process ST6 performed after the end of the second regeneration process ST5, as shown in FIG. 4C, the raw water W1 is distributed from the bottom screen 322, and the cation exchange resin bed 311 is mainly modified. The raw water W <b> 1 is passed through the mass region 313 in an upward flow, and the salt water W <b> 3 introduced into the lower region including the modified region 313 of the cation exchange resin bed 311 is pushed out. The raw water W1 that has passed through the reforming region 313 is collected from the intermediate screen 323.

  In the second regeneration process ST5 and the second extrusion process ST6, partial countercurrent regeneration is performed on the lower region of the cation exchange resin bed 311. Therefore, by regenerating the reforming region 313 with priority, in the reforming process ST1, it is possible to stably obtain the treated water W2 that has been reformed to the target water quality.

  Note that the illustration of the back cleaning process ST2, the rinsing process ST7, and the water replenishment process ST8 is omitted.

Again, the structure of the water treatment system 1 is demonstrated, referring FIG.
The salt water tank 4 stores salt water W3 as a regenerating solution for regenerating the cation exchange resin bed 311. As the salt water W3, an aqueous solution of an alkali metal salt (for example, a sodium chloride aqueous solution or a potassium chloride aqueous solution) is used. The upstream end of the salt water line L3 is connected to the salt water tank 4. The downstream end of the salt water line L3 communicates with the process control valve 32 and is connected to various lines constituting the process control valve 32, respectively. The salt water line L3 is provided with a salt water valve (not shown). The salt water valve opens and closes the salt water line L3. The salt water valve is incorporated in the process control valve 32, and the drive unit of the valve body is electrically connected to the control unit 10 via a signal line (not shown). The opening and closing of the salt water valve is controlled by the control unit 10. The salt water tank 4 sends salt water W3 for regenerating the cation exchange resin bed 311 to the pressure tank 31 in the first regeneration process ST3 and the second regeneration process ST5. The salt water tank 4, a salt water valve (not shown), an ejector (not shown), and a salt water flow meter constitute a regenerating liquid supply unit in the present embodiment.

  The reverse osmosis membrane separation device 5 dissolves the treated water W2 reformed by the iron content reformer 3 with the permeated water W5 from which dissolved salts and the like have been removed by the reverse osmosis membrane (RO membrane module 5b described later). This is a facility for membrane separation treatment with concentrated water W6 in which salts and the like are concentrated. The reverse osmosis membrane separation device 5 is connected to the downstream side of the iron content reforming device 3 via the treated water line L2.

  The reverse osmosis membrane separation device 5 includes a pressure pump 5a and an RO membrane module 5b as a reverse osmosis membrane. The pressurizing pump 5a pressurizes the treated water W2 sent from the iron reforming device 3 and sends it to the RO membrane module 5b. The RO membrane module 5b includes a single or a plurality of RO membrane elements (not shown). The reverse osmosis membrane separation device 5 performs membrane separation treatment of the treated water W2 with these RO membrane elements to produce permeated water W5 and concentrated water W6.

  The upstream end of the water flow line L5 is connected to the permeate outlet of the RO membrane module 5b. The permeated water W5 obtained by the reverse osmosis membrane separation device 5 is sent to the deaeration treatment device 6 through the water passage line L5. The upstream end of the concentrated water line L6 is connected to the concentrated water outlet of the RO membrane module 5b. The concentrated water W6 obtained by the reverse osmosis membrane separation device 5 is discharged to the outside through the concentrated water line L6. In addition, in order to keep the flow velocity on the film surface within a predetermined range, a cross flow configuration may be used. That is, a part of the concentrated water W6 is recirculated to the treated water line L2 on the upstream side of the reverse osmosis membrane separation device 5, and the other concentrated water W6 is discharged to the outside.

The RO membrane module 5b in the present embodiment is not particularly limited, but the RO membrane module 5b has a reverse osmosis membrane (not shown) in which a negatively charged skin layer made of a crosslinked wholly aromatic polyamide is formed on the membrane surface. preferable. The reverse osmosis membrane has a water permeability coefficient of 1.3 × when a sodium chloride aqueous solution having a concentration of 500 mg / L, pH 7.0, and temperature of 25 ° C. is supplied at an operating pressure of 0.7 MPa and a recovery rate of 15%. 10 ⁻¹¹ m ³ · m ⁻² · s ⁻¹ · Pa ⁻¹ or more and a salt removal rate of 99% or more are preferable. Such a reverse osmosis membrane also includes a nanofiltration membrane with loose pores (having a larger water permeability coefficient).

Here, the operating pressure is an average operating pressure defined by JIS K3802-1995 “Membrane Term”. The operating pressure indicates an average value of the primary side inlet pressure and the primary side outlet pressure of the RO membrane module 5b.
Recovery and the feed water to the RO membrane module 5b (here, aqueous sodium chloride solution), the amount of the flow rate _{Q 2} of the permeate to the flow rate to _{Q 1 (i.e., Q 2 / Q 1 × 100} ) refers to.
The water permeation coefficient is a value obtained by dividing the permeated water amount [m ³ / s] by the membrane area [m ² ] and the effective pressure [Pa], and is an index indicating the water permeation performance of the reverse osmosis membrane. That is, the water permeation coefficient means the amount of water that permeates the unit area of the membrane per unit time when a unit effective pressure is applied. The effective pressure is defined by JIS K3802-1995 “Membrane Term” and is a pressure obtained by subtracting the osmotic pressure difference and the secondary pressure from the operating pressure (average operating pressure).
The salt removal rate is a value calculated from the concentration of specific salts before and after permeating the membrane (here, sodium chloride concentration), and is an index indicating the solute blocking performance of the reverse osmosis membrane. The salt removal rate is determined by (1−C ₂ / C ₁ ) × 100 from the inlet concentration (C ₁ ) to the RO membrane module 5 b and the permeated water concentration (C ₂ ).

  The reverse osmosis membrane that satisfies the conditions of the water permeability coefficient and the salt removal rate of this embodiment is commercially available as a reverse osmosis membrane element. As the reverse osmosis membrane element, for example, Toray Industries, Inc .: model name “TMG20-400”, Unjin Chemical, Inc .: model name “RE8040-BLF”, Nitto Denko Corporation: model name “ESPA1”, etc. may be used. it can.

  The degassing treatment device 6 degasses the free carbonic acid (dissolved carbon dioxide gas) contained in the permeated water W5 produced by the reverse osmosis membrane separation device 5 with a gas separation membrane module, and degassed water as purified water It is equipment to obtain W7. The deaeration treatment device 6 is provided on the downstream side of the reverse osmosis membrane separation device 5 via the water flow line L5. An upstream end portion of the water flow line L7 is connected to the deaeration water outlet of the deaeration treatment device 6. The deaerated water W7 obtained by the deaeration treatment device 6 is sent to the secondary purification device and the demand point via the water passage line L7.

  In the deaeration treatment device 6 of this embodiment, an internal perfusion type gas separation membrane module made of a hollow fiber membrane is used. Examples of gas separation membrane modules suitable for such applications include DIC Corporation product names “SEPAREL PF-015”, “SEPAREL PF-030”, and the like.

  The control unit 10 includes a microprocessor (not shown) including a CPU and a memory. The control unit 10 controls the operation of the process control valve 32 based on a detection signal or the like input from a raw water flow meter (not shown) or a salt water flow meter. The memory stores in advance a control program for performing the operation of the iron reforming apparatus 3 of the present embodiment. The CPU controls the process control valve 32 so as to sequentially switch the reforming process ST1 to the water refill process ST8 described above in accordance with a control program stored in the memory.

  In the water treatment system 1 configured as described above, the raw water W1 supplied from the supply source (not shown) of the raw water W1 through the raw water line L1 is supplied from the raw water pump 2 to the process control valve 32 of the iron content reformer 3. Is sent to. The raw water W1 is reformed by passing through the cation exchange resin bed 311 of the pressure tank 31 to produce treated water W2. The treated water W2 is further sent to the reverse osmosis membrane separation device 5 via the treated water line L2. In the reverse osmosis membrane separation device 5, the treated water W2 is subjected to membrane separation treatment in the RO membrane module 5b, and the permeated water W5 and the concentrated water W6 are produced. The permeated water W5 is further sent to the deaeration treatment device 6. In the degassing treatment device 6, the permeated water W5 is degassed by the gas separation membrane module to obtain degassed water W7. Thereafter, the obtained deaerated water W7 is sent as purified water to the secondary purification device and the demand point via the water flow line L7.

  According to the water treatment system 1 of the present embodiment, in the reforming treatment, the total iron concentration is 0.2 mg Fe / L or less, and the weight ratio of the iron fine particles of 0.45 μm or more in the whole iron fine particles is 80% or more, and The raw water W1 having a pH of 5.5 to 8.5 is set to a linear velocity of 5 to 60 m / h with respect to the cation exchange resin bed 311 of the pressure tank 31 without performing iron removal treatment and acid addition treatment. Pass water. Thereby, the treated water W2 in which the weight ratio of 0.45 μm or more of iron fine particles to the whole iron fine particles is modified to 30% or less can be produced.

  In this reforming treatment, since the iron removal treatment and the acid addition treatment are not performed, the concentration of iron fine particles in the produced treated water W2 hardly changes from the raw water W1. However, the weight ratio of 0.45 μm or more of iron fine particles to the whole iron fine particles is 30% or less. That is, the iron fine particles having a large particle size contained in the raw water W1 are refined, and the weight ratio of the iron fine particles of less than 0.45 μm to the whole iron fine particles becomes approximately 70% or more. When the treated water W2 containing the finely divided iron fine particles is supplied to the RO membrane module 5b, the iron fine particles are hardly deposited on the membrane surface of the RO membrane module 5b, and most of the iron fine particles are contained in the concentrated water W6. It is discharged outside while being dispersed. For this reason, generation | occurrence | production of the fouling in the RO membrane module 5b is suppressed. Therefore, good water permeation performance can be maintained over a long period of time.

According to the water treatment system 1 which concerns on 1st Embodiment mentioned above, the following effects are show | played, for example.
In the water treatment system 1 of this embodiment, the raw water W1 is reformed in the cation exchange resin bed tower, and the obtained treated water W2 is supplied to the RO membrane module 5b. According to this, since the iron fine particles having a large particle size are miniaturized, the deposition of iron fine particles on the membrane surface of the RO membrane module 5b is reduced, and the occurrence of fouling in the RO membrane module 5b is suppressed. Therefore, good water permeation performance can be maintained over a long period of time without performing iron removal treatment and acid addition treatment as pretreatment.

  In the water treatment system 1 of the present embodiment, the cation exchange resin bed 311 of the iron reformer 3 collects the salt water W3 on the bottom screen 322 while distributing the salt water W3 to the top screen 321 of the cation exchange resin bed 311. A first regeneration process ST3 for regenerating the entire cation exchange resin bed 311 by generating a downward flow of the salt water W3 by liquefying; and the salt water W3 after the first regeneration process ST3 in the cation exchange resin bed 311 While the liquid is distributed to the bottom screen 322, the upward flow of the salt water W3 is generated by collecting the liquid on the intermediate screen 323 to regenerate a part of the cation exchange resin bed 311 (mainly the modified region 313). 2 It is operated including the regeneration process ST5. Therefore, it is possible to stably obtain the treated water W2 that has been modified to the target water quality while increasing the amount of collected water of the treated water W2 to the maximum.

  Further, in the water treatment system 1 of the present embodiment, in the second regeneration process ST5, with respect to the reforming region 313 in which the depth D2 (see FIG. 2) is set to 100 mm with the bottom of the cation exchange resin bed 311 as a base point. Then, partial countercurrent regeneration is performed with the salt water W3 in an amount such that the regeneration level is 1 to 6 eq / LR. Therefore, when the raw water W1 contains a hardness component while stably obtaining the treated water W2 modified to the target water quality, the hardness leak amount of the treated water W2 can be reduced to the limit.

  Furthermore, the water treatment system 1 of the present embodiment includes a deaeration treatment device 6 on the downstream side of the reverse osmosis membrane separation device 5. Therefore, free carbonic acid that cannot be removed by the reverse osmosis membrane separation device 5 can be sufficiently removed by the subsequent deaeration treatment device 6. Therefore, purified water with higher purity can be produced.

(Second Embodiment)
Next, a water treatment system 1A according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is an overall configuration diagram of a water treatment system 1A according to the second embodiment. In the second embodiment, differences from the first embodiment will be mainly described. For this reason, the same code | symbol is attached | subjected about the same (or equivalent) structure as 1st Embodiment, and detailed description is abbreviate | omitted. The description of the first embodiment is appropriately applied to points that are not particularly described in the second embodiment.

  As shown in FIG. 5, the water treatment system 1A according to the present embodiment includes a raw water pump 2, an iron reforming device 3, a salt water tank 4, a reverse osmosis membrane separation device 5, a degassing treatment device 6, An electrodeionization device 7 as an electrodeionization module and a control unit 10 are provided. The water treatment system 1 includes a raw water line L1, a treated water line L2, a salt water line L3, a drainage line L4, water flow lines L5, L7, and L8, and concentrated water lines L6 and L9.

In the present embodiment, the “concentrated water W6” in the first embodiment is referred to as “first concentrated water W6”, and the concentrated water obtained by the electrodeionization apparatus 7 is referred to as “second concentrated water W9”.
In this embodiment, the point provided with the electrodeionization apparatus 7 in the downstream of the deaeration processing apparatus 6 differs from 1st Embodiment. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  In the present embodiment, the upstream end of the water flow line L7 is connected to the deaerated water outlet of the deaeration treatment device 6. The electrodeionization device 7 is connected to the downstream side of the deaeration treatment device 6 via a water passage line L7. The deaerated water W7 obtained by the deaeration treatment device 6 is sent to the electrodeionization device 7 through the water passage line L7.

  The electric deionizer 7 is a facility for performing a membrane separation process for separating the deaerated water W7 obtained by the deaeration processor 6 into a deionized water W8 and a second concentrated water W9 by an ion exchange membrane (not shown). It is. Specifically, the electrodeionization apparatus 7 includes a demineralization chamber and a concentration chamber (both not shown). The desalting chamber and the concentration chamber are formed by alternately arranging a cation exchange membrane and an anion exchange membrane (both not shown) between a pair of electrodes. Among these, the cation exchange resin and the anion exchange resin are accommodated in the desalting chamber. The desalting chamber only needs to contain at least a cation exchange resin (the reason will be described later).

  The electrodeionization device 7 is electrically connected to a power supply circuit (not shown). In addition to the function of the first embodiment, the control unit 10 of this embodiment has a function of applying a predetermined DC voltage to the electrodeionization device 7 via a power supply circuit.

  In the electrodeionization apparatus 7, when a DC voltage is applied between the pair of electrodes, the permeated water W5 that could not be removed by the reverse osmosis membrane separation apparatus 5 due to the selective movement of ions through the ion exchange membrane. Residual ions contained are removed in a desalting chamber. Thereby, deionized water (purified water) W8 is manufactured in the desalting chamber. In the electrodeionization apparatus 7, the second concentrated water W9 having a high ion concentration is produced from the degassed water W7 in the concentration chamber.

  The upstream end of the water flow line L8 is connected to the demineralization chamber of the electrodeionization apparatus 7. The deionized water W8 produced by the electrodeionization device 7 is sent as purified water to the secondary purification device and the demand point through the water passage line L8. On the other hand, the upstream end of the concentrated water line L9 is connected to the concentration chamber of the electrodeionization apparatus 7. The second concentrated water W9 produced by the electrodeionization apparatus 7 is discharged to the outside through the concentrated water line L9. The second concentrated water W9 can be returned to the treated water line L2 upstream of the pressurizing pump 5a via the concentrated water line L9 without being discharged to the outside.

  According to 1 A of water treatment systems of 2nd Embodiment mentioned above, the effect similar to the water treatment system 1 of 1st Embodiment is show | played. In particular, in the water treatment system 1 </ b> A of the present embodiment, an electrodeionization device 7 is further provided on the downstream side of the deaeration treatment device 6. Therefore, ions contained in the permeate W5 that could not be removed by the reverse osmosis membrane separation device 5 can be further removed by the electrodeionization device 7. Therefore, purified water with higher purity can be produced.

In addition, in this embodiment, although the structure provided with the electrodeionization apparatus 7 in the downstream of the deaeration processing apparatus 6 was demonstrated, not only this but an ion exchange resin mixed bed tower or a cation exchange resin single bed tower It is good also as a structure provided with.
The ion exchange resin mixed bed tower is one in which a cation exchange resin and an anion exchange resin are mixed in one tower. In the ion-exchange resin mixed bed tower, cations and anions contained in the degassed water W7 are simultaneously removed.

On the other hand, the cation exchange resin single-bed column contains only the cation exchange resin in one column (also called a cation polisher). In the present embodiment, when the RO membrane module 5b includes a reverse osmosis membrane having a negatively charged skin layer, the RO membrane module 5b tends to remove anions, but tends to easily transmit cations. (This tendency becomes more prominent when the pH of the treated water W2 is increased in order to promote ionization of weak acids such as carbonic acid, silicic acid (silica), and boric acid). In this case, the cation that has permeated through the reverse osmosis membrane separation device 5 is removed by a cation exchange resin single-bed column provided on the downstream side. Thus, when a cation exchange resin single bed column is used, anions and cations are removed stepwise.
In the electrodeionization apparatus 7 described above, even when only the cation exchange resin is accommodated in the demineralization chamber, the anion and the cation are stepped in the same manner as in the case where the single cation exchange resin bed is used. Can be removed. That is, in the electrodeionization apparatus 7, cations that have permeated through the reverse osmosis membrane separation apparatus 5 are removed.

  As described above, the reverse osmosis membrane separation device 5 could not completely remove the deionization treatment even when the ion exchange resin mixed bed tower or the cation exchange resin single bed tower was used. Ions contained in the permeated water W5 can be further removed.

(Third embodiment)
Next, a water treatment system 1B according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is an overall configuration diagram of a water treatment system 1B according to the third embodiment. In the third embodiment, differences from the first embodiment will be mainly described. For this reason, the same code | symbol is attached | subjected about the same (or equivalent) structure as 1st Embodiment, and detailed description is abbreviate | omitted. Moreover, the description of 1st Embodiment is used suitably about the point which is not demonstrated especially in 2nd Embodiment.

  As shown in FIG. 6, the water treatment system 1B according to the present embodiment includes a raw water pump 2, an iron content reformer 3, a salt water tank 4, a first reverse osmosis membrane separation device 5, and a deaeration treatment device 6. And a second reverse osmosis membrane separation device 8 and a control unit 10. The water treatment system 1 includes a raw water line L1, a treated water line L2, a salt water line L3, a drainage line L4, water flow lines L5, L7, and L10, and concentrated water lines L6 and L11.

In the present embodiment, the “reverse osmosis membrane separation device 5” in the first embodiment is referred to as a “first reverse osmosis membrane separation device 5”. In the first reverse osmosis membrane separation device 5 of the present embodiment, the treated water W2 is subjected to membrane separation treatment to produce the first permeated water W5 and the first concentrated water W6.
In the present embodiment, the permeated water W5 of the first embodiment is referred to as “first permeated water W5”, and the concentrated water W6 of the first embodiment is referred to as “first concentrated water W6”. In this embodiment, the permeated water produced by the second reverse osmosis membrane separator 8 is referred to as “second permeate W10”, and the concentrated water produced by the second reverse osmosis membrane separator 8 is designated as “second concentrated water”. Water W11 ”.

  In the water treatment system 1B according to the present embodiment, the second reverse osmosis membrane separation device 8 is further provided on the downstream side of the first reverse osmosis membrane separation device 5 via the degassing treatment device 6. Different from form. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  The configuration of the second reverse osmosis membrane separation device 8 in the present embodiment is the same as that of the first reverse osmosis membrane separation device 5. That is, the pressure pump 8 a of the second reverse osmosis membrane separation device 8 is the same as the pressure pump 5 a of the first reverse osmosis membrane separation device 5. Further, the RO membrane module 8b of the second reverse osmosis membrane separation device 8 may have the same characteristics as the RO membrane module 5b of the first reverse osmosis membrane separation device 5, or may have different characteristics. As the RO membrane module 8b, for example, an NF membrane module having a nanofiltration membrane having pores looser than those of a normal reverse osmosis membrane can be used. The second reverse osmosis membrane separation device 8 performs membrane separation treatment on the first permeated water W5 produced by the first reverse osmosis membrane separation device 5 by the RO membrane module 8b, and the second permeated water W10 and the second concentrated water W11. Manufacturing.

  The upstream end of the water flow line L10 is connected to the permeate outlet of the RO membrane module 8b. The 2nd permeated water W10 manufactured with the 2nd reverse osmosis membrane separation apparatus 8 is sent to a secondary refinement | purification apparatus and a demand point as purified water via the water flow line L10. The upstream end of the concentrated water line L11 is connected to the concentrated water outlet of the RO membrane module 8b. The second concentrated water W11 produced by the second reverse osmosis membrane separation device 8 is discharged to the outside through the concentrated water line L11. Note that the second concentrated water W11 can be returned to the treated water line L2 upstream of the pressurizing pump 5a via the concentrated water line L11 without being discharged to the outside.

  According to water treatment system 1B of a 3rd embodiment mentioned above, the same effect as water treatment system 1 of a 1st embodiment is produced. In particular, the water treatment system 1B of the present embodiment further includes a second reverse osmosis membrane separation device 8 via a degassing treatment device 6 on the downstream side of the first reverse osmosis membrane separation device 5. Therefore, ions contained in the first permeated water W5 that could not be removed by the first reverse osmosis membrane separation device 5 can be further removed by the second reverse osmosis membrane separation device 8. Therefore, purified water with higher purity can be produced.

  In addition, in this embodiment, it is good also as a structure further equipped with the electrodeionization apparatus 7 shown in 2nd Embodiment as an apparatus which performs a deionization process in the downstream of the 2nd reverse osmosis membrane separation apparatus 8. FIG. Moreover, it is good also as a structure provided with the ion exchange resin mixed bed tower or the cation exchange resin single bed tower instead of the electrodeionization apparatus 7. FIG. In such a configuration, ions contained in the second permeated water W10 that could not be removed by the first reverse osmosis membrane separation device 5 and the second reverse osmosis membrane separation device 8 can be further removed. Therefore, purified water with higher purity can be produced.

  As mentioned above, although preferred embodiment of this invention was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above.

  For example, in the first to third embodiments, an alkaline agent addition device (not shown) is provided in the treated water line L2, and the treated water W2 supplied to the reverse osmosis membrane separation device (first reverse osmosis membrane separation device) 5 is used. It is good also as a structure which adds an alkaline agent. Examples of the alkaline agent include sodium hydroxide and potassium hydroxide. When an alkaline agent is added to the treated water W2 produced by the iron reforming device 3 to raise the pH to 8 or more, free carbonic acid contained in the treated water W2 is ionized and changed to hydrogen carbonate ions or carbonate ions. For this reason, in the reverse osmosis membrane separation device (first reverse osmosis membrane separation device) 5 provided on the downstream side, ionized free carbonic acid (hydrogen carbonate ions or carbonate ions) can be removed. Therefore, purified water with higher purity can be produced.

  Moreover, since the free carbonic acid contained in the treated water W2 is sufficiently removed by the reverse osmosis membrane separation device (first reverse osmosis membrane separation device) 5 by adding the alkaline agent, the load on the deaeration treatment device 6 is reduced. Can be reduced. That is, the deaeration processing device 6 can be downsized.

  Moreover, since the solubility of the silicic acid (silica) contained in the treated water W2 increases when an alkali agent is added to the treated water W2, it is possible to suppress the generation of silica-based scale, resulting in the recovery of purified water. The rate can be improved. Moreover, since the dissociation (ionization) of boric acid is accelerated | stimulated by adding an alkaline agent to the treated water W2 and setting pH to 9 or more, the removal rate of boric acid can be improved.

  In the third embodiment, when an ion exchange resin mixed bed tower is provided on the downstream side of the second reverse osmosis membrane separation device 8, by adding an alkali agent to the degassed water W7, silicic acid (silica ) Is promoted in dissociation (ionization), the life of the ion-exchange resin mixed bed tower can be extended. That is, when undissociated silicic acid remains in the second permeated water W10, the nonionic silicic acid is physically adsorbed and accumulated in the pores of the anion exchange resin. Therefore, it becomes difficult to recycle the anion exchange resin. On the other hand, when the dissociated silicic acid remains in the second permeated water W10, the ionic silicic acid is removed by ion exchange with the anion exchange resin. Is possible. For this reason, in the latter case, the load of the ion-exchange resin mixed bed tower is reduced, and the life can be extended.

Furthermore, about the structure which provided the alkaline agent addition apparatus, there exist the following embodiments.
In the configuration in which the deaeration treatment device 6 is connected to the downstream side of the reverse osmosis membrane separation device 5 as in the first embodiment, the carbonate load of the permeate W5 supplied to the deaeration treatment device 6 is unstable. In the deaeration treatment device 6, removal of free carbonic acid becomes insufficient, and the purity of the purified water produced becomes unstable.

  Therefore, as described in the second embodiment, in a configuration in which a cation exchange resin single-bed tower is connected to the downstream side of the degassing treatment device 6, the carbon dioxide concentration detection means (not shown) is connected to the treated water line L2 ( It is provided on the inlet side of the reverse osmosis membrane separation device 5. As the carbonic acid concentration detection means, for example, there is a combination of a pH meter and an M alkalinity meter in addition to a carbonic acid concentration meter. These carbonic acid concentration detection means are electrically connected to the control unit 10 through a signal line. The measurement value detected by the carbonic acid concentration detection means is transmitted to the control unit 10. The alkaline agent addition device is electrically connected to the control unit 10 through a signal line. The addition or non-addition of the alkaline agent to the treated water line L2 by the alkaline agent addition device is controlled by the control unit 10.

  The control unit 10 controls addition or non-addition of the alkaline agent by the alkaline agent addition device based on the measurement value detected by the carbonic acid concentration detection means. The controller 10 uses the measured value of the carbonic acid concentration when the carbonic acid concentration detecting means is a carbonic acid concentration meter in the determination of the addition or non-addition of the alkaline agent. Further, when the carbonic acid concentration detecting means is a pH meter and an M alkalinity meter, the control unit 10 uses an estimated value of the carbonic acid concentration calculated based on the respective measured values.

  The control part 10 controls the addition amount of the alkaline agent to the treated water line L2 by the following control procedures, for example. The control unit 10 compares the measured value (or the calculated estimated value) A transmitted from the carbonic acid concentration detecting means with the carbonic acid concentration value (set value) B that can be removed by the deaeration processing device 6. And the control part 10 controls an alkaline agent addition apparatus so that an alkaline agent may be added to the treated water line L2 when measurement value A> = carbonic acid concentration value B. In addition, when the measurement value A <carbonic acid concentration value B, the control unit 10 controls the alkaline agent adding device so that the alkaline agent is not added to the treated water line L2. This control is performed at predetermined time intervals or in real time.

  Thus, when the addition or non-addition of the alkaline agent is controlled based on the measured value (or estimated value) of the carbonic acid concentration contained in the treated water W2, the carbonic acid load of the treated water W2 is unstable. Also, the free carbonic acid can be sufficiently removed in the reverse osmosis membrane separation device 5. Therefore, the purity of the purified water produced can be stabilized. Moreover, since the addition amount of the alkaline agent can be optimized, the amount of the alkaline agent to be used can be minimized.

  In addition, when a cation exchange resin single-bed tower is connected to the downstream side of the degassing treatment device 6, the interval between the regeneration treatments with the regenerant can be extended, so that the amount of the regenerant used can be reduced. It becomes possible. Incidentally, when an ion exchange resin mixed bed tower is connected to the downstream side of the degassing treatment device 6, the purity of the purified water can be increased, but the amount of the regenerant used in the regeneration treatment increases. Increase.

  The carbonic acid concentration detection means described above may be provided in the water flow line L7 (exit side of the deaeration device 6). In this case, the carbonic acid concentration of the deaerated water W7 delivered from the deaeration treatment device 6 is measured.

  Moreover, it is good also as a structure which provided the electrical conductivity detection means (not shown) instead of a carbonic acid concentration detection means. An example of the electrical conductivity detection means is an electrical conductivity meter. In the determination of addition or non-addition of the alkaline agent, the control unit 10 uses a measured value of electrical conductivity when the electrical conductivity detecting means is an electrical conductivity meter. The electric conductivity detection means is provided on the outlet side of the water flow line L5 (the outlet side of the reverse osmosis membrane separation device 5) or the cation exchange resin single bed tower.

  In this case, the control unit 10 compares the measured value A transmitted from the electrical conductivity detecting means with the electrical conductivity (set value) B corresponding to the carbonic acid concentration value that can be removed by the degassing device 6. To do. And the control part 10 controls an alkaline agent addition apparatus so that an alkaline agent may be added to the treated water line L2 when measurement value A> = electric conductivity B. Moreover, when the measured value A <electrical conductivity B, the control unit 10 controls the alkaline agent adding device so that the alkaline agent is not added to the treated water line L2.

  In the above-described embodiment in which the alkaline agent is added, the example in which the addition amount of the alkaline agent is controlled while the addition amount of the alkaline agent is constant has been described. Not limited to this example, the amount of alkali agent added may be controlled to be variable according to the measured amount of carbonic acid concentration.

  Further, as described in the third embodiment (see FIG. 6), in the case where the cation exchange resin single bed tower (not shown) is further provided on the downstream side of the second reverse osmosis membrane separation device 8. Moreover, the same effect can be acquired by applying the technique which controls the addition or non-addition of an alkaline agent based on the measured value (or estimated value) of the carbonic acid concentration contained in the treated water W2.

  Further, as described in the second embodiment (see FIG. 5), a configuration in which an ion exchange resin mixed bed tower is provided on the downstream side of the deaeration treatment device 6 may be adopted. Even in such a configuration, the same effect can be obtained by applying a method of controlling the addition or non-addition of the alkaline agent based on the measured value (or estimated value) of the carbonic acid concentration contained in the treated water W2. Can be obtained. In this case, the carbonic acid concentration detection means is provided in the treated water line L2 (inlet side of the reverse osmosis membrane separation device 5) or the water flow line L7 (outlet side of the degassing device 6). Moreover, when using an electrical conductivity detection means, an electrical conductivity detection means is provided in the water flow line L5 (exit side of the reverse osmosis membrane separation apparatus 5) or the exit side of an ion exchange resin mixed bed tower.

  Furthermore, also in the structure of 3rd Embodiment (refer FIG. 6), the method of controlling the addition or non-addition of an alkaline agent based on the measured value (or estimated value) of the carbonic acid concentration contained in the treated water W2 is applied. Thus, the same effect can be obtained. In this case, the carbonic acid concentration detection means is provided in the treated water line L2 (the inlet side of the first reverse osmosis membrane separation device 5) or the water flow line L7 (the outlet side of the deaeration treatment device 6). Moreover, when using an electrical conductivity detection means, an electrical conductivity detection means is the water flow line L5 (outlet side of the 1st reverse osmosis membrane separation apparatus 5) or the water flow line L10 (2nd reverse osmosis membrane separation apparatus 8). On the exit side).

  In each of the above embodiments, the iron reforming apparatus 3 that performs a two-stage regeneration process including cocurrent regeneration and partial countercurrent regeneration has been described. However, the present invention is not limited to this, and split flow regeneration is performed. An iron reformer may be used. Split flow regeneration refers to cation exchange resin that generates a counter flow of the regenerated liquid by collecting it at the middle while distributing the regenerated liquid from both the top and bottom of the cation exchange resin bed 311. This is a regeneration process for regenerating the entire floor 311. In this split flow regeneration, the regenerated liquid distributed from the bottom of the cation exchange resin bed 311 is collected at the intermediate portion, thereby performing partial countercurrent regeneration.

  Moreover, in each said embodiment, the raw | natural water tank which supplies raw | natural water W1 to the raw | natural water line L1 is provided separately from the supply source of the raw | natural water W1, and the installation containing this raw | natural water tank is good also as a raw | natural water supply means. In this case, the raw water W1 stored in the raw water tank is supplied to the iron content reformer 3 as washing water, extrusion water, and rinsing water.

<Experimental example>
Next, effects of the embodiment will be described in more detail based on experimental examples and comparative experimental examples. The present invention is not limited to the following examples.

[Test 1] Iron content reforming test using a cation exchange resin bed tower In order to confirm the reforming effect of the iron content reforming equipment, the raw fine water not modified and the treated water treated with The weight ratio was verified.

  Here, in the reforming process, a cation exchange resin bed (resin amount: 11 L-) in which Matsuyama City industrial water having a total iron concentration of 0.2 mg Fe / L and pH 7.2 is used as raw water and the bed depth is set to 600 mm. R) was passed at a linear velocity of 50 m / h. The cation exchange resin bed was regenerated in advance using an aqueous sodium chloride solution in an amount such that the regeneration level was 2 eq / LR, and the counter ion of the cation exchange resin bed was converted to sodium.

  About each of raw | natural water and treated water, the weight ratio of the 0.45 micrometer or more iron fine particle which occupies for the whole iron fine particle was measured according to the method mentioned above. In the raw water, the weight ratio of 0.45 μm or more of iron fine particles in the whole iron fine particles was 86%. On the other hand, in the treated water, the weight ratio of 0.45 μm or more of iron fine particles to the whole iron fine particles was 5%. As a result, it was confirmed that refinement of iron fine particles having a large particle diameter was promoted by carrying out the modification treatment.

[Test 2] Water permeability performance test
Experimental Example Treated water that has been subjected to iron modification treatment under the conditions of Test 1 is supplied as feed water to a reverse osmosis membrane module loaded with one “SUL-G10” element manufactured by Toray Industries, Inc., and the amount of permeated water is 200 L / h. And operated under conditions of a recovery rate of 75% and a temperature of 25 ° C. The permeate flow rate was adjusted to the above flow rate by adjusting the number of rotations of the pressure pump. In addition, the water flow to the reverse osmosis membrane module is a cross flow method, and a part of the concentrated water is circulated to the primary side of the pressure pump so that the circulation flow rate in the system is five times the permeate flow rate. I let you.

Comparative Experimental Example The feed water was treated under the same conditions as in the experimental example, except that the raw water not subjected to the modification treatment was used as the feed water.

In each of the evaluation experiment example and the comparative experiment example, the change in the effective pressure of the reverse osmosis membrane element during the water treatment operation was measured over time. And the water permeation coefficient was calculated from the measured value of the effective pressure, the set value of the permeated water flow rate, and the effective membrane area of the reverse osmosis membrane element, and used as an index of the water permeation performance in the reverse osmosis membrane module. In addition, since the water permeation coefficient in the initial state varies somewhat depending on individual differences of the reverse osmosis membrane elements, the numerical value at the time when one hour has elapsed from the start of the water treatment operation is used as the initial value. The results are shown in Table 1.

  According to the test results shown in Table 1, in the experimental example in which the reforming treatment was performed, it can be seen that the water permeation coefficient after the lapse of 800 hours maintained the initial value, and fouling due to iron fine particles was suppressed. . On the other hand, in the comparative experimental example in which the reforming treatment is not performed, the water permeation coefficient after 800 hours of operation is reduced to 80% of the initial value, and it can be seen that fouling by the iron fine particles is progressing.

1, 1A, 1B Water treatment system 3 Iron reformer 4 Salt water tank 5 Reverse osmosis membrane separator (first reverse osmosis membrane separator)
6b RO membrane module (reverse osmosis membrane)
6 Electrodeionization equipment (Electrodeionization module)
8 Second reverse osmosis membrane separation device 10 Control unit 31 Pressure tank (cation exchange resin bed tower)
32 Process control valve (valve means)
311 Cation exchange resin bed 313 Reforming region 321 Top screen 322 Bottom screen 323 Intermediate screen L1 Raw water line L2 Treated water line L3 Salt water line L4 Drain lines L5, L6, L8, L10 Water flow lines L7, L9, L11 Concentrated water Line W1 Raw water W2 Treated water W3 Brine (regenerated liquid)
W4 Drainage W5 Permeate (first permeate)
W6 Concentrated water (first concentrated water)
W7 Deaerated water W8 Deionized water W9, W11 Second concentrated water W10 Second permeated water

Claims (10)

Cation exchange is performed on raw water having a total iron concentration of 0.2 mg Fe / L or less, a weight ratio of iron fine particles of 0.45 μm or more occupying the whole iron fine particles of 80% or more, and a pH of 5.5 to 8.5. An iron reforming process for reforming in a resin bed tower;
A first reverse osmosis membrane separation step of separating the treated water modified in the iron content reforming step into permeated water and concentrated water by a first reverse osmosis membrane module;
A degassing treatment step of degassing the permeated water obtained in the first reverse osmosis membrane separation step with a gas separation membrane module,
In the cation exchange resin bed tower, a modification process for producing soft water by passing raw water through a cation exchange resin bed having a depth of 300 to 1500 mm; Operated including a regeneration process to regenerate the cation exchange resin bed by passing through,
In the regeneration process, an aqueous solution of an alkali metal salt is supplied to regenerate the cation exchange resin bed, while in the reforming process after the regeneration process, the cation exchange is performed without removing the raw water and adjusting the pH. Set the linear velocity with respect to the resin bed to 5 to 60 m / h and pass water;
Water treatment method. A deionization treatment step of deionizing the treated water degassed in the deaeration treatment step with an electrodeionization module, an ion exchange resin mixed bed tower or a cation exchange resin single bed tower;
The water treatment method according to claim 1. A second reverse osmosis membrane separation step of separating the treated water degassed in the deaeration treatment step into permeated water and concentrated water by a second reverse osmosis membrane module;
The water treatment method according to claim 1. Including a deionization treatment step of deionizing the permeated water obtained in the second reverse osmosis membrane separation step with an electrodeionization module, an ion exchange resin mixed bed tower or a cation exchange resin single bed tower,
The water treatment method according to claim 3. In the regeneration process, partial counter-current regeneration is performed with a regeneration liquid amount of 1 to 6 eq / LR for a hardness leak prevention bed set at a depth of 100 mm with the bottom of the cation exchange resin bed as a base point. Do,
The water treatment method as described in any one of Claims 1-4. Cation exchange is performed on raw water having a total iron concentration of 0.2 mg Fe / L or less, a weight ratio of iron fine particles of 0.45 μm or more occupying the whole iron fine particles of 80% or more, and a pH of 5.5 to 8.5. An iron content reformer for reforming treatment in a resin bed tower;
A first reverse osmosis membrane separation device for separating treated water modified by the iron content reformer into permeated water and concentrated water by a first reverse osmosis membrane module;
A degassing treatment device for degassing the permeated water obtained by the first reverse osmosis membrane separation device with a gas separation membrane module;
A softening process for producing soft water by passing raw water through a cation exchange resin bed having a depth of 300 to 1500 mm housed in the cation exchange resin bed tower; regenerating liquid for the cation exchange resin bed; Valve means switchable to a regeneration process for regenerating the cation exchange resin bed by passing
In the regeneration process, a regeneration solution supply means for supplying an aqueous solution of an alkali metal salt as a regeneration solution to the cation exchange resin bed,
In the reforming process after the regeneration process, the raw water is provided with raw water supply means for passing water by setting the linear velocity to the cation exchange resin bed to 5 to 60 m / h without removing iron and adjusting pH. ,
Water treatment system. An ionization module, an ion exchange resin mixed bed tower or a cation exchange resin single bed tower for deionizing treated water degassed by the degassing apparatus;
The water treatment system according to claim 6. A second reverse osmosis membrane separation device for separating the treated water deaerated by the deaeration treatment device into permeated water and concentrated water by a second reverse osmosis membrane module;
The water treatment method according to claim 6. Comprising an electrodeionization module, an ion exchange resin mixed bed tower or a cation exchange resin single bed tower for deionizing the permeated water obtained by the second reverse osmosis membrane separation device,
The water treatment system according to claim 8. The valve means performs partial countercurrent regeneration with a regeneration liquid amount of 1 to 6 eq / LR with respect to a hardness leak prevention bed set to a depth of 100 mm with the bottom of the cation exchange resin bed as a base point. Configured to switch to the playback process
The water treatment system according to any one of claims 6 to 9.

Images