JP4848641B2 - Pure water production method and apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for producing pure water used in semiconductor manufacturing processes and the like, and in particular, after treating raw water with biological activated carbon, if necessary, an ion exchange resin, a membrane separation apparatus, and electrodeionization. The present invention relates to a method and an apparatus for producing pure water which are processed by an apparatus or the like.

  Conventionally, ultrapure water used as semiconductor cleaning water is raw water (industrial water, city water, well water, etc.) in an ultrapure water production system consisting of a pretreatment system, primary pure water system and subsystems. Manufactured by processing.

  The pretreatment system includes agglomeration, pressurized flotation (precipitation), filtration (membrane filtration) apparatus and the like. In this pretreatment system, suspended substances and colloidal substances in raw water are removed. In addition, this pretreatment system can remove high molecular organic substances, hydrophobic organic substances, and the like.

  The primary pure water system includes a reverse osmosis membrane separation device, a deaeration device, an ion exchange device (such as a mixed bed type or a 4-bed type 5 tower type) and the like. In this primary pure water system, ions and organic components in the raw water are removed. The reverse osmosis membrane separation apparatus removes salts and ionic and colloidal TOC. The ion exchange apparatus removes salts and removes ionic contaminants such as fluorine ions adsorbed or ion exchanged by an ion exchange resin. In the deaerator, inorganic carbon (IC) and dissolved oxygen are removed.

The subsystem includes a low-pressure ultraviolet oxidizer, an ion-exchange pure water device, an ultrafiltration membrane separator, and the like. In this subsystem, the purity of water is further increased to ultrapure water. In the low-pressure ultraviolet oxidizer, TOC is decomposed into organic acids and further to CO ₂ by 185 nm ultraviolet rays emitted from a low-pressure ultraviolet lamp. Ions and CO ₂ produced by the decomposition are removed by an ion exchange resin in the subsequent stage. In the ultrafiltration membrane separation device, the fine particles are removed, and the outflow particles of the ion exchange resin are also removed.

  The present applicant, as an ultrapure water production method and apparatus that can efficiently remove organic matter (TOC) components in water, after turbidity treatment of raw water, membrane deaeration, and then biological activated carbon treatment, Japanese Patent Laid-Open No. 2002-355683 proposes a method and apparatus for RO (reverse osmosis membrane) treatment, ion exchange treatment or electrodeionization treatment. In JP 2002-336886 A and JP 2003-340481, a primary deionized water system includes a decarbonation tower, a biological activated carbon tower, a first RO device, an ion exchange device, a degassing device, and a second RO device. Are proposed to be installed in this order.

  The organic matter removal mechanism of this biological activated carbon is: (i) Organic matter adsorption effect by activated carbon; (ii) Organic matter decomposition effect by biological membrane; (iii) Microorganisms in activated carbon decompose organic matter adsorbed on activated carbon to restore pore volume It consists of three mechanisms of biological regeneration effect.

  In this biological activated carbon tower, the time until the adsorption ability of the activated carbon itself reaches saturation is remarkably long. However, if water is passed for a long time, the activated carbon wears out or the particle size becomes smaller due to oxidation with hydrogen peroxide in water.

Therefore, it is necessary to replace the activated carbon of the biological activated carbon device with a new one regularly or irregularly such as for two years. However, when the activated carbon is replaced with a new one, the biofilm does not adhere to the new activated carbon, so that the treated water quality becomes insufficient for a while after the replacement.
JP 2002-355683 A JP 2002-336886 A JP 2003-340481

  An object of the present invention is to provide a pure water production method and apparatus in which the quality of treated water is sufficiently high even immediately after the replacement of activated carbon and restarting the pure water production operation.

The pure water production method according to claim 1, wherein the raw water containing the TOC component is passed through an activated carbon tower for treatment and an activated carbon exchange process for exchanging activated carbon in the activated carbon tower . After the activated carbon exchange step, a raw water containing a TOC component is circulated through the activated carbon tower to perform a habituation step for breeding organisms on the activated carbon, and then the pure water production method moves to the adsorption step , It has a step of further treating the treated water from the activated carbon tower with an ion exchange resin tower, and two or more systems comprising a combination of the activated carbon tower and the ion exchange resin tower at the subsequent stage are installed in parallel. When the acclimatization process is being performed in the activated carbon tower of a part of the system, the raw water is passed through the other system to continue the production of pure water, and the effluent of the activated carbon tower in the acclimatization process is removed from the ion exchange resin tower. Instead of circulating in the raw tank The flow path is selected .

Water purifying apparatus 請 Motomeko 2 includes a water tank Hara, and activated carbon tower raw water containing the TOC components in the raw water tank is passed through the ion exchange resin column treated water of the activated carbon column is passed through And a pure water production apparatus having a habituation means for circulating the raw water containing the TOC component in the activated carbon tower and propagating the organism on the activated carbon, comprising a combination of the activated carbon tower and the ion exchange resin tower at the subsequent stage. Two or more systems are installed in parallel, and when the activated carbon tower is acclimatized in some of the activated carbon towers, the raw water is passed to other systems and the production of pure water is continued. It has a flow path selection means for circulating the effluent of the activated carbon tower that is circulating to the raw water tank instead of the ion exchange resin tower .

In the pure water production method 請 Motomeko 1, even when replacing the activated carbon with new activated carbon, perform acclimatization step after the activated carbon replacement bred organism activated carbon was fully formed biofilm After that, pure water production is performed. Therefore, even immediately after resuming the pure water production operation, the quality of the treated water is sufficiently high.

To do this acclimatization process, it is convenient and suitable for circulating water passage a TOC component containing water to activated carbon bed.

In the pure water production method 請 Motomeko 1, since the high-order processing by the higher-order processing unit of the treated water from the activated carbon bed, a better quality of water is obtained.

In the pure water production method 請 Motomeko 1, since the production of pure water in the other of the activated carbon bed, even when performing the replacement or acclimatization of the activated carbon in a part of the activated carbon bed, to pure water demand locations Pure water can be continuously supplied.

According to the pure water production apparatus of the second aspect , the pure water production method of the first aspect can be easily carried out .

According to the water purifying system of 請 Motomeko 1, pure water can be supplied continuously to the demand position.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a system diagram of a pure water production apparatus according to an embodiment, and FIGS. 2 to 6 are explanatory views of the water flow state.

  As shown in FIG. 1, raw water is introduced into a raw water tank 2 through a pipe 1 for introducing raw water. The raw water in the raw water tank 2 can be passed through an activated carbon tower (AC tower) 14 via a pipe 3, a branch pipe 3 a branched from the pipe 3, a pump 11, a pipe 12, and a valve 13. The treated water in the tower 14 passes through the pipe 15, the valve 16, the pipe 17, and the valve 18 and is further supplied to the weak anion exchange tower (WA tower) 32 through the pipe 31, or the pipe 35, the valve 36, and the pipe 37. It is possible to supply to the WA tower 38 via

  The raw water from the pipe 3 passes through the branch pipe 3b, the pump 21, the pipe 22, the valve 23, the activated carbon tower (AC tower) 24, the pipe 25, the valve 26, the pipe 27, and the valve 28, and further through the pipes 39 and 37. It can be supplied to the WA tower 38 via the pipe 39, the valve 36, and the pipes 35, 31.

  An activated carbon bed is provided in the activated carbon towers 14 and 24. This activated carbon bed may be a fluidized bed or a fixed bed.

  In order to acclimatize the activated carbon in the activated carbon tower 14, the effluent water from the activated carbon tower 14 can be circulated to the raw water tank 2 through the pipe 17, the pipe 19, the valve 19 a and the collective pipe 9. Similarly, in order to acclimatize the activated carbon in the activated carbon tower 24, the effluent water of the activated carbon tower 24 can be circulated to the raw water tank 2 through the pipe 27, the pipe 29, the valve 29 a, and the collective pipe 9.

  A pipe 51 is branched from the pipe 15 to discharge the regenerated waste water when the WA towers 32 and 38 are regenerated, and is connected to a discharge pipe 54 through a valve 52 and a pipe 53. A pipe 55 branches from the pipe 25 and is connected to the pipe 54 via a valve 56 and a pipe 57.

  Although not shown, three or more systems comprising a combination of the activated carbon tower and the WA tower may be provided. Two or more activated carbon towers may be provided in series in one system.

  Next, with reference to FIG. 2, the water flow method in the case of performing a pure water production operation in the activated carbon tower 14 will be described. In this case, the valves 13, 16, 18, and 34 are opened, the other valves are closed, and the pump 11 is started. Thereby, raw | natural water flows in order of piping 3, 3a, 12, activated carbon tower 14, piping 15, 17, 31, WA tower 32, and piping 33, and becomes treated water (pure water). In FIG. 2, water is passed through the WA tower 32, but the valve 34 is closed and the valves 36 and 41 are opened, so that the outflow water from the activated carbon tower 14 can be passed through the WA tower 38.

  When pure water production operation is performed in the activated carbon tower 24, as shown in FIG. 3, the valves 23, 26, 28 and 41 are opened, the other valves are closed, and the pump 21 is started. Thereby, raw | natural water flows in order of piping 3, 3b, 22, activated carbon tower 24, piping 25, 27, 39, 37, WA tower 38, and piping 40, and turns into pure water. In FIG. 3, water is passed through the WA tower 38, but the valves 36 and 34 are opened and the valve 41 is closed, so that the outflow water from the activated carbon tower 24 can be passed through the WA tower 32.

  Although not shown in the figure, pure water is supplied to both the system of the activated carbon tower 14 and the WA tower 32 and the system of the activated carbon tower 24 and the WA tower 38 by performing the water flow shown in FIGS. Manufacturing is also possible.

  With reference to FIG. 4, after replacing | exchanging the activated carbon in the activated carbon tower 14, the acclimatization operation is performed in the activated carbon tower 14, and the water flow condition in the case of performing the pure water production operation in the activated carbon tower 24 will be described.

  In this case, the valves 13, 16, 19a and the valves 23, 26, 28, 41 are opened, and the other valves are closed. When both the pumps 11 and 21 are operated, water is passed through the activated carbon tower 24 and the WA tower 38 as in FIG. On the other hand, the effluent water of the activated carbon tower 14 flows in the order of the pipes 17, 19, 9 and is circulated to the raw water tank 2. This circulating water flow is performed until the biofilm is sufficiently adhered to the new activated carbon in the activated carbon tower 14, and then the pure water production operation is also performed in the system of the activated carbon tower 14 and the WA tower 32. As a result, high-quality pure water can be obtained from the pipe 33 immediately after resumption of the pure water production operation in this system.

  In FIG. 4, the outflow water from the activated carbon tower 24 is passed through the WA tower 38, but it may be passed through the WA tower 32.

  With reference to FIG. 5, the case where the acclimatization operation is performed in the activated carbon tower 24 after the activated carbon tower 24 is replaced and the pure water production operation is performed in the activated carbon tower 24 and the WA tower 32 will be described.

  In this case, the valves 13, 16, 18, and 34 and the valves 23, 26, and 29a are opened, and the other valves are closed. When the pumps 11 and 21 are operated, the raw water in the raw water tank 2 flows through the activated carbon tower 14 and the WA tower 32 and pure water is obtained from the pipe 33. On the other hand, the effluent water of the activated carbon tower 24 is circulated to the raw water tank 2 through the pipes 27, 29 and 9. This circulating water flow is continued until the biofilm sufficiently adheres to the new activated carbon in the activated carbon tower 24. Thereafter, the pure water production operation by the activated carbon tower 24 and the WA tower 38 is resumed. Even immediately after the restart, high-quality pure water is obtained from the pipe 41.

  In the above-described embodiment, the WA towers 32 and 38 are disposed after the activated carbon towers 14 and 24, but other ion exchange resin towers, membrane separation devices, electrodeionization devices and the like are used. Or two or more of these may be combined.

Figure 6 omits the higher order processing means, such as WA tower 32, showing a reference example in parallel installed activated carbon column 14 and 24. In FIG. 6, the piping 31, the WA tower 32, the piping 33, and the valve 34 are omitted, and the piping 37, the WA tower 38, the piping 40, and the valve 41 are omitted. Other configurations are the same as those in FIG. In this case, biological activated carbon treatment of raw water can be performed in one or both of the activated carbon towers 14 and 24. In addition, biological activated carbon treatment can be performed in one activated carbon tower, while raw water circulation can be performed in the other activated carbon tower for acclimatization of new activated carbon .

Below, it will be described experimental examples.

Experiment Example 1, Comparative Example 1
In the pure water producing apparatus having two series of activated carbon beds shown in FIG. 6, as the raw water of the raw water tank 2, a nonionic surfactant containing polyoxyalkylene alkyl ether in ultrapure water (“NCW” manufactured by Wako Pure Chemical Industries, Ltd.) −1002 ”) added as a TOC at 2000 μg / L.

  First, the raw water was supplied to the first series so that the residence time in the activated carbon tower 14 was 15 minutes.

  After 8 weeks from the start of water flow, the TOC concentration of the treated water in the activated carbon tower was stabilized at 10 μg / L. On the other hand, after 3 months, new activated carbon was filled in a series different from the above, and the raw water was supplied so that the residence time was 15 minutes, and then all the treated water was returned to the raw water tank. When this state was continued for 8 weeks, the TOC of the treated water became 10 μg / L, so that the treated water was taken out of the system together with the first series of treated water without returning it to the raw water tank.

  The first series of water was interrupted six months after the first series operation. And all the activated carbon of the activated carbon bed was replaced with new activated carbon. And it was acclimatized for 8 weeks by the operation | movement which returns all the treated water of an activated carbon bed to a raw | natural water tank similarly to the above-mentioned. During this time, the second series was normally operated, and the TOC of the treated water did not change at 10 μg / L as shown in FIG.

  On the other hand, when the treated water of the second series was analyzed, the TOC exceeded 10 μg / L as shown in FIG. 7 for 6 weeks after the start of the habituation operation. Therefore, when this conditioned water is discharged out of the system, the water quality deteriorates.

It is a systematic diagram of the pure water manufacturing apparatus which concerns on embodiment. It is explanatory drawing of the water flow condition to the pure water manufacturing apparatus of FIG. It is explanatory drawing of the water flow condition to the pure water manufacturing apparatus of FIG. It is explanatory drawing of the water flow condition to the pure water manufacturing apparatus of FIG. It is explanatory drawing of the water flow condition to the pure water manufacturing apparatus of FIG. It is explanatory drawing of the water flow condition to the pure water manufacturing apparatus which concerns on a reference example . Is a graph showing the results of experimental examples and comparative experimental examples.

2 Raw water tank 14, 24 Activated carbon tower 32, 38 Weak anion exchange tower

Claims (2)

An adsorption process in which raw water containing a TOC component is passed through an activated carbon tower for treatment;
In a pure water production method having an activated carbon exchange step of exchanging activated carbon of the activated carbon tower ,
After the activated carbon exchange step, a raw water containing a TOC component is circulated through the activated carbon tower to perform a habituation step for breeding organisms on the activated carbon, and then the pure water production method moves to the adsorption step ,
Further comprising a step of further treating the treated water from the activated carbon tower with an ion exchange resin tower,
Two or more systems consisting of a combination of an activated carbon tower and an ion exchange resin tower at the subsequent stage are installed in parallel, and when the acclimatization process is performed in the activated carbon tower of some systems, raw water is supplied to other systems. Continue to produce pure water by passing water,
A method for producing pure water, comprising: selecting a flow path for circulating the effluent of the activated carbon tower in the acclimatization step to the raw water tank instead of the ion exchange resin tower . A raw water tank, an activated carbon tower through which raw water containing the TOC component in the raw water tank is passed, an ion exchange resin tower through which treated water of the activated carbon tower is passed, and the activated carbon tower contains a TOC component In a pure water production apparatus having a habituation means for circulating raw water and breeding organisms on activated carbon ,
Two or more systems consisting of a combination of an activated carbon tower and an ion exchange resin tower at the subsequent stage are installed in parallel, and raw water is supplied to other systems when the activated carbon tower is acclimatized in the activated carbon tower of some systems. Continue to produce pure water by passing water,
An apparatus for producing pure water, comprising flow path selection means for circulating the effluent of the activated carbon tower that circulates the raw water to the raw water tank instead of the ion exchange resin tower .

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