JP3491666B2 - Method and apparatus for controlling TOC component removal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and apparatus for removing TOC components, and more particularly to water that does not substantially contain TOC components, such as pure water and ultrapure water used in the cleaning process of the electronics industry. The present invention relates to a control method and apparatus for TOC component removal for manufacturing and recovery.

[0002]

2. Description of the Related Art By appropriately combining ozone, hydrogen peroxide, ultraviolet rays and various oxidation catalysts, hydroxyl radicals having a stronger oxidizing power than the individual oxidation means are generated. Since these oxidizing means do not generate elements other than oxygen element and hydrogen element, the risk of secondary contamination is low and the salt load in the subsequent treatment is also low. From such characteristics, a hydroxyl radical is generated by an appropriate combination of the above-mentioned various oxidizing means or a combination of ozone and alkali (alkaline is not an oxidizing agent, but this combination generates a hydroxyl radical), whereby TOC is generated. TOC component in the component-containing water (hereinafter sometimes referred to as “raw water”) is oxidatively decomposed to produce pure water, ultrapure water, etc., and pure water after use, and TOC from the raw water for recovery of ultrapure water It is widely practiced to remove components.

As described above, various combinations of the above-mentioned various oxidizing means and combinations of ozone and alkali are
Although hydroxyl radicals are commonly generated, these combinations have different characteristics from each other.
For example, the combination of hydrogen peroxide and ultraviolet rays (UV) is a classical method of use, but the reaction rate is slow, and thus it usually takes several hours or more. The combination of ozone and ultraviolet (UV) has a very high UV absorption rate due to ozone, so the reaction speed will be considerably faster, but the initial cost and running cost (electricity fee and replacement cost of the ultraviolet lamp) due to the ultraviolet irradiation device. Both) will increase. The combination of ozone and alkali has a fast reaction rate and a low running cost, but since it reacts on the alkali side, when a high concentration of TOC component is present, carbonate ion (CO ₃ ^2- ) or bicarbonate ion (HCO
₃ ^-) The radical scavengers according to undergo reaction inhibition (the alkaline side, such as, if the carbon dioxide is one of the degradation products of TOC components is present as carbonate ion and bicarbonate ion, there is a high concentration TOC components Because, the amount of carbon dioxide produced is also large). On the other hand, the combination of ozone and hydrogen peroxide has a relatively wide range of use because it has a small reaction rate but is less affected by the radical scavenger and is economically advantageous. It should be noted that carbonate ions have a greater effect as radical scavengers than bicarbonate ions.

In any of the above hydroxyl radical generating mechanisms, since an organic acid is generated as an intermediate product, the hydroxyl radical generating mechanism causes oxidative decomposition into carbon dioxide and water to be substantially completely decomposed into TO.
As an economical treatment method, the C component is not substantially completely removed, but as an economical treatment method, a portion of the produced organic acid that is not decomposed into carbon dioxide and water is left, and the remainder of this organic acid is provided as an ion. It may be removed using a removal mechanism (for example, an ion removal device such as an ion exchange device or a reverse osmosis membrane (RO) device).

[0005]

In most cases of such TOC component removal, the amount of hydroxyl radicals generated is not controlled, so the device is operated on the safe side.
Therefore, the hydroxyl radical is always in excess.
In some cases, the TOC value of raw water (TOC concentration)
Feedforward control is performed by
Since the relationship between the C value and the required amount of hydroxyl radicals varies depending on the TOC source (type of organic substance as the TOC component) in the raw water that is the object of decomposition and removal, such feedforward control based on the TOC value of the raw water is accurate. It lacks in size. On the other hand, the TO of the treated water obtained from the ion removal device
If the amount of hydroxyl radicals generated is feedback-controlled by the C value, it is inevitable that the time lag becomes long, and the TOC component is adsorbed or released by the activated carbon of the activated carbon contacting device for decomposing the oxidant provided in front of the ion removal device. Therefore, it is difficult to ensure stable control, and since the TOC value of the treated water obtained from the ion removing device is extremely low, it is difficult to secure a sufficient control range.

The present invention solves the above-mentioned drawbacks of the prior art, decomposes the TOC component in the TOC component-containing water to at least an organic acid by a hydroxyl radical, and further removes the organic acid in the obtained treated water by an ion removal mechanism. The present invention provides a control method and apparatus for TOC component removal that enables stable and accurate control of the amount of hydroxyl radicals generated when pure water is produced by removing TOC components by treatment.

[0007]

The present invention has been completed based on the results of the following experiments conducted to solve the above problems. That is, the present invention
When the TOC component in the C component-containing water is decomposed to at least an organic acid by a hydroxyl radical and the resulting organic acid in the treated water is further treated by an ion removing means to remove the TOC component to produce pure water, a hydroxyl radical is used. The TOC value of the treated water treated by the above is monitored, the generation amount of hydroxyl radicals is automatically controlled so that the TOC value becomes 0.5 to 2.5 mg / L, and the final treatment performed by the ion removing means. Underwater TOC
TO, characterized in that a value of less than 0.3 5 mg / L
Control method for removal of C component, and hydroxy radical generation device for decomposing TOC component in TOC component-containing water to at least organic acid by hydroxyl radical,
TO in treated water from the hydroxy radical generator
Ion removal device for removing organic acid as C component, TOC value of treated water from the hydroxyl radical generator is monitored, and the TOC value is 0.5 to 2.5 mg.
The amount of hydroxyl radicals generated is automatically controlled so that
There is provided an apparatus TOC component removing characterized in that it comprises a feedback control mechanism for the C value below 0.3 5 mg / L.

According to the result of the experiment conducted by the present inventor, the TOC of the treated water obtained from the ion removing device as described above is shown.
Value is 0.3 5 mg / L or less, preferably 0.2 mg / L
According to the following, when ultrapure water is produced from the treated water from the ion removing device, U in the latter ultrapure water producing device is used.
It was found that the TOC value can be further reduced to 0.02 mg / L or less by V (ultraviolet) oxidation, RO treatment (reverse osmosis membrane treatment) and the like.

In general, TO by hydroxyl radical
The decomposition route (a series of reactions) of the C component varies depending on the kind of the decomposition target substance, but most organic substances are converted into carbon dioxide and water through a low molecular organic acid such as propionic acid, acetic acid, and formic acid in the final stage. Therefore, even if the TOC value of the raw water (TOC component-containing water) and the TOC source (type of organic substance as the TOC component) are different, most of the TOC component was converted to at least a low-molecular organic acid by the oxidation treatment with hydroxyl radicals. At the stage, since the amount converted into carbon dioxide and water is no longer the TOC component, the TOC value in the treated water after the treatment with the hydroxyl radical falls within a fairly narrow range.

Taking a treatment with a combination of ozone and hydrogen peroxide as an example, the TOC value range of the treated water is about 0.5 to 2.5 mg / L. In particular, when the alcoholic organic substance is the main TOC source, the TOC value range of the treated water by the hydroxyl radicals of this combination is about 0.5 to 1.5 mg / L. When the main TOC source of raw water is a surfactant having a large molecular weight, the TOC value range of the treated water by the hydroxyl radical of this combination is about 0.5 to 2.5 mg / L. Thus further performing ion removal for treated water obtained, TOC values in the treated water after the ion removal 0.3 5 mg / L or less, and less in most cases 0.2 mg / L.

As described above, since the TOC value of the treated water from the hydroxyl radical generator has a certain correlation with the TOC value of the treated water from the ion removal device in the latter stage, the TOC value of the treated water from the hydroxyl radical generator is constant. If the amount of hydroxyl radical generation is controlled so that the value becomes a predetermined value, T of the treated water from the hydroxyl radical generator is controlled.
TOC of treated water from the ion removal device corresponding to OC value
The value is obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited thereto.

The TOC value of the treated water from the ozone / hydrogen peroxide reaction tank (hydroxyl radical generator) is 0.5 to
Range of 2.5 mg / L, preferably 0.5-1.5 mg
If the amount of ozone generated is controlled to fall within the range of / L,
For example, TOC value of the treated water after the ion exchange resin treatment (ion removal treatment) is 0.3 5 mg / L or less, and less in most cases 0.2 mg / L. In this case, it is preferable that the supply amount of hydrogen peroxide is controlled so as to be proportional to the ozone generation amount, and the hydrogen peroxide / ozone weight ratio is controlled to be 0.2 / 1 to 0.4 / 1.

T due to the combination of ozone and alkali
The OC component removal is almost the same. That is, the TOC value of the treated water from the ozone / alkali reaction tank (hydroxyl radical generator) is in the range of 0.5 to 2.5 mg / L, preferably in the range of 0.5 to 1.5 mg / L. to controlling the amount of generated ozone, ion exchange resin treatment TOC values (ion removal) after the treated water is 0.3 5 mg / L or less, and less in most cases 0.2 mg / L. In this case, the amount of alkali added is preferably controlled by the pH value of the treated water instead of being proportional to the amount of ozone generated. The pH of the clogging and treated water may be adjusted to the alkaline side, preferably 8 to 11, and more preferably 8.5 to 10.5. Generally, when the pH value is increased, the reaction rate is increased, but since the amount of the alkali added is large, the salt load in the ion removal treatment such as the ion exchange resin treatment is also increased, and the carbon dioxide is changed into the carbonate ion. Also, the ratio of carbonic acid ions existing as bicarbonate ions, particularly carbonate ions, increases, so that the action as a radical scavenger also increases. As the alkali, for example, sodium hydroxide or potassium hydroxide can be used.

The TOC component removal by the combination of ozone and ultraviolet rays (UV) is almost the same. That is, ozone /
The amount of ozone generated so that the TOC value of the treated water from the UV reaction tank (hydroxyl radical generator) is in the range of 0.5 to 2.5 mg / L, preferably 0.5 to 1.5 mg / L. controlling the, TOC values of the treated water after the ion exchange resin treatment (ion removal) is 0.3 5 mg / L or less,
In most cases, it will be 0.2 mg / L or less. In this case, for example, it is preferable to control the output amount of the ultraviolet (UV) lamp in conjunction with the ozone generation amount. The UV lamp output amount is clogged so that the UV lamp output amount is proportional to the ozone generation amount, and the UV lamp output amount / ozone generation amount. the ratio of the amount may be controlled such that the 0.2~5kw / kg-O _3. The main wavelength of the UV lamp used is 254 nm, or the main wavelength is 254n.
m and 185 nm low-pressure mercury lamp, and the dominant wavelength is 3
A 65 nm high-pressure mercury lamp may be used, but a low-pressure mercury lamp having a main wavelength of 254 nm is preferably used.

In the above-described preferred embodiment, ozone / hydrogen peroxide, as a hydroxyl radical generating mechanism,
The case of each combination of ozone / alkali and ozone / ultraviolet (UV) was described, but Fenton oxidation (Fe ²⁺
+ H ₂ O ₂ / UV (UV), ozone / oxidation catalyst, catalyst (TiO ₂ etc.) / UV (UV) AOP method (ad
Various methods called "vanced oxidation processes" may be used, or a plurality of methods may be selected from the detailed combination method and the method called AOP method and further combined. For example, they can be combined in multiple stages, or can be combined and used in one stage such as ozone / hydrogen peroxide / ultraviolet (UV). As a method of generating ozone, various methods such as a silent discharge method and a water electrolysis method can be used.

The treated water after the treatment with hydroxyl radicals avoids the adverse effect of the remaining oxidizing agent on the deterioration of the materials such as the ion exchange resin and the reverse osmosis membrane used in the ion removal device in the subsequent stage, and therefore the residual oxidizing agent Removal is usually performed prior to ion removal. Examples of the method for removing the residual oxidizing agent include activated carbon treatment, reducing agent (for example, sodium sulfite) injection, ultraviolet irradiation, and reduction catalyst (for example, palladium-based catalyst) contact, but activated carbon treatment is low cost. In addition, it is simple and preferable in terms of equipment.

In the above-described preferred embodiment, the case where the ion removal is performed by the ion exchange resin treatment has been described as an example, but the ion removal is performed by various ion exchange methods (apparatus) or reverse osmosis membrane (RO) method ( Can be performed by using an ion removal method (apparatus) such as (apparatus).

[0019] In addition to the above-described control of the present invention method, the TOC value of the treated water from the ion removal device monitoring (monitoring), TOC value of the treated water after the ion removal 0.3 5 mg / L adding the operation to control the hydroxyl radical generation amount such that the following auxiliary manner is also effective, and thereby more reliably 0.3 5 mg / L or less TOC value of the treated water after the ion removal can do.

[0020]

[Example] TO by combination of ozone / hydrogen peroxide
The present invention will be described in more detail with reference to the following examples, using C component removal processing as an example, but the present invention is not limited thereto.

FIG. 1 shows the TOC component removing device used in the embodiment, which is also a system flow chart showing an example of the device of the present invention. The reactor 101 is a hydroxyl radical generator, and raw water is supplied to the reactor 101 from a raw water line 141 by a raw water pump 140. The TOC value of a part of the treated water after the hydroxyl radical treatment in the reactor 101 is measured by the TOC meter 120, the control signal 122 is transmitted from the PID controller 121 based on this TOC value, and the ozone generator 130 is controlled. At the same time, the hydrogen peroxide pump control signal 123 linked with the ozone generation amount is generated to control the hydrogen peroxide pump 150. The ozonized gas generated in the ozone generator 130 is passed through the ozonized gas line 131 to the reactor 10
It is injected into the circulation line 133 connected to 1, and is supplied to the reactor 101 by the circulation pump 132. In addition,
Dissolution of ozone can be done by diffuser, ejector, line mixer (in
-line mixer) and various other means. Hydrogen peroxide line 150 by hydrogen peroxide pump 150
Hydrogen peroxide is supplied to the reactor 101 through 51. Most of the treated water after the hydroxyl radical treatment is sent to the activated carbon tower 111 through the hydroxyl radical treated water line 110, where the oxidant (hydrogen peroxide, ozone) is decomposed, and the treated water treated with the activated carbon is ,
Water is sent to the ion exchange resin tower 112, where organic acids and the like are removed by ion exchange, and flows out to the ion exchange treated water line 113 as treated water after ion exchange. In addition, 160 is an exhaust gas discharge pipe.

Example 1 In the apparatus shown in FIG. 1, a reactor 10 having a capacity of 10 L was used.
1, while passing raw water of various TOC values at a flow rate of 6 L / hr, the circulation line 133 on the suction side of the circulation pump 132.
The ozone generated by the silent discharge was supplied to and the hydrogen peroxide was continuously supplied by the hydrogen peroxide pump 150. The TOC source was isopropyl alcohol (IPA). The TOC value of the treated water 110 after being treated with hydroxyl radicals (oxidation treatment of TOC components) in the reactor 101 is a seabass 810 TOC meter 120.
Measured online by [manufactured by Seabass (USA)],
The measurement signal from the TOC meter 120 is sent to the PID controller 121, the ozone generation amount is controlled by the PID controller 121 so that the measured value of the TOC meter 120 becomes a predetermined value, and the hydrogen peroxide / ozone weight ratio = 0. The hydrogen peroxide pump 150 was controlled so as to be 0.31 / 1, and the hydroxyl radical generation amount was automatically controlled by both of them. The pH value of water in the reactor 101 was kept substantially constant at around 7.5. Treated water from the reactor 101 is the activated carbon tower 1
After decomposing the oxidizers (O ₃ , H ₂ O ₂ ) by treatment with 11, the ionic organic substance (organic acid) is generated by the ion exchange resin tower 112.
Was removed. The results of this TOC component removal process are shown in Table 1.

[0023]

[Table 1]   ───────────────────────────────────       Raw water TOC value TOC value immediately after oxidation treatment TOC value after ion exchange       (Mg / L) (mg / L) (mg / L)   ───────────────────────────────────           2 1.4 0.35           2 0.6 0.08           4 1.8 0.32           4 0.7 0.07           6 1.7 0.28           6 0.5 0.04   ───────────────────────────────────

As can be seen from Table 1, even if the TOC value of the raw water fluctuates, if the TOC value of the treated water immediately after the oxidation treatment (before the activated carbon treatment) is kept constant, the treated water after the ion exchange treatment is treated. Therefore, it was found that it is effective to control the hydroxyl radical generation amount by the TOC value of the treated water immediately after the oxidation treatment. Further, for comparison, an attempt was made to control the amount of hydroxyl radical generation by the TOC value of the treated water after the ion exchange treatment, but the lag time was too long, and stable control could not be performed.

Example 2 In the apparatus shown in FIG. 1, raw water containing a surfactant as a TOC source was treated under the same conditions as in Example 1. The main components of the surfactant are polyoxyethylene alkyl ether, sulfosuccinic acid alkyl ether, diethylene glycol monobenzyl ether and olefin. The treated water from the reactor 101 was treated in the activated carbon tower 111, the oxidants (O ₃ , H ₂ O ₂ ) were decomposed, and the ionic organic matter (organic acid) was removed by the ion exchange resin tower 112. The results of this TOC component removal process are shown in Table 2.

[0026]

[Table 2]   ───────────────────────────────────       Raw water TOC value TOC value immediately after oxidation treatment TOC value after ion exchange       (Mg / L) (mg / L) (mg / L)   ───────────────────────────────────         4.3 2.5 0.25         4.5 1.8 0.11         6.6 2.6 0.22         6.5 1.9 0.09   ───────────────────────────────────

As can be seen from Table 2, even if the TOC value of the raw water fluctuates, if the TOC value of the treated water immediately after the oxidation treatment (before the activated carbon treatment) is kept constant, the treated water after the ion exchange treatment is treated. Therefore, it was found that it is effective to control the hydroxyl radical generation amount by the TOC value of the treated water immediately after the oxidation treatment. Further, for comparison, an attempt was made to control the amount of hydroxyl radical generation by the TOC value of the treated water after the ion exchange treatment, but the lag time was too long, and stable control could not be performed.

[0028]

INDUSTRIAL APPLICABILITY Generally, T due to hydroxyl radical
The decomposition route (a series of reactions) of the OC component varies depending on the type of the decomposition target substance, but most organic substances are converted into carbon dioxide and water through a low molecular organic acid such as propionic acid, acetic acid, and formic acid in the final stage. Therefore, even if the TOC value of the raw water (TOC component-containing water) or the TOC source (type of organic substance as the TOC component) is different, at the stage where the TOC component is converted to at least a low-molecular organic acid by the oxidation treatment with hydroxyl radicals. Since the amount converted into carbon dioxide and water is no longer the TOC component, according to the method of the present invention,
T in treated water after oxidation treatment with hydroxyl radicals
OC value within a fairly narrow range (0.5-2.5 mg / L)
You can get in.

Further, since the TOC value of the treated water from the hydroxyl radical generator has a certain correlation with the TOC value of the treated water from the ion removing device in the subsequent stage, according to the method of the present invention, the TOC value from the hydroxyl radical generator is When the amount of generated hydroxyl radicals is controlled so that the TOC value of the treated water becomes a predetermined value (0.5 to 2.5 mg / L), the ion removal device from the ion removal device corresponding to the TOC value of the treated water from the hydroxyl radical generator is controlled. TOC value of the treated water is obtained, 0.3 5 mg of TOC value of the treated water after the ion removal /
It can be L or less. Therefore, according to the method of the present invention, stable and accurate control of TOC component removal can be performed.

[0030] In addition to the above control, the TOC value of the treated water from the ion removal device monitoring (monitoring), as TOC value of the treated water after the ion removal becomes less 0.3 5 mg / L It is also effective to supplementarily add an operation to control the amount of hydroxyl radicals generated, which allows
More surely the TOC value of treated water after ion removal is 0.3 5
It can be less than or equal to mg / L.

Thus, the TO of the treated water after removing the ions
If the C value below 0.3 5 mg / L, the treated water can be sent to the manufacturing process of ultra-pure water, UV oxidation in subsequent ultrapure water production apparatus, the TOC value by RO treatment, etc. Further It can be 0.02 mg / L or less.

[Brief description of drawings]

FIG. 1 is a system flow diagram showing an example of an apparatus for removing TOC components of the present invention used in Examples.

[Explanation of symbols]

101 reactor 110 Hydroxyl radical treated water line 111 activated carbon tower 112 Ion exchange resin tower 113 Ion exchange treated water line 120 TOC meter 121 PID controller 122 control signal 123 Hydrogen peroxide pump control signal 130 Ozone generator 131 Ozone gas line 132 Circulation pump 133 circulation line 140 Raw water pump 141 Raw water line 150 hydrogen peroxide pump 151 hydrogen peroxide line 160 Exhaust gas exhaust pipe

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C02F 1/78 C02F 1/72 C02F 1/42 C02F 1/32 C02F 1/00

Claims (5)

(57) [Claims] 1. A TOC component in water containing a TOC component is decomposed to at least an organic acid by a hydroxyl radical,
When the TOC component is removed by further treating the organic acid in the obtained treated water with an ion removing means to produce pure water, the TOC value of the treated water treated with hydroxyl radicals is monitored, and the TOC value is 0. .5-2.
Amount of generated hydroxyl radicals so that 5 mg / L and automatic control, TOC component removing characterized by a final process TOC value of water treated by the ion removing means below 0.3 5 mg / L Control method. 2. The TOC value of the treated water treated with the hydroxyl radicals is 0.1 when the hydroxyl radicals are generated by a combination of ozone and hydrogen peroxide.
It is possible to automatically control the amount of hydroxyl radicals generated by controlling the amount of hydrogen peroxide supplied in conjunction with the amount of ozone generated while controlling the amount of ozone generated so as to be 5 to 2.5 mg / L. The control method for removing the TOC component according to claim 1, which is characterized in that. 3. The TOC value and pH of the treated water generated by the hydroxyl radicals generated by the combination of ozone and alkali.
Value is monitored, and the TOC value of the treated water is 0.5 to 2.5 m
It is possible to automatically control the amount of hydroxyl radicals generated by controlling the amount of alkali added so that the pH value of the treated water is on the alkaline side while controlling the amount of ozone generated so as to be g / L. The control method for removing the TOC component according to claim 1, which is characterized in that. 4. The ozone generation amount so that the hydroxyl radicals are generated by a combination of ozone and an ultraviolet lamp, and the TOC value of the treated water treated with the hydroxyl radicals is 0.5 to 2.5 mg / L. The method for controlling the removal of TOC components according to claim 1, wherein the amount of hydroxyl radicals generated is automatically controlled by controlling the amount of output of the ultraviolet lamp in conjunction with the amount of ozone generated while controlling the amount of ozone. . 5. A hydroxy radical generator for decomposing a TOC component in TOC component-containing water to at least an organic acid by a hydroxyl radical, and for removing an organic acid as a TOC component in treated water from the hydroxy radical generator. Ion removal device, monitoring the TOC value of the treated water from the hydroxyl radical generator,
Its TOC value is automatically controls the generation of hydroxyl radicals so that 0.5 to 2.5 / L, the TOC value of the final treated water 0.3 5 mg from the ion removing device
A device for removing a TOC component, which includes a feedback control mechanism for controlling the amount to be equal to or lower than / L.