JP3849765B2 - Apparatus and method for treating water containing organic matter - Google Patents

Description

【００６０】
１回のキャビテーション処理のみでは、処理液中のＴＯＣ濃度は５０μｇ／Ｌまでしか減少しないが、表１から明らかなように、装置に循環ラインを設け処理液を循環させることにより、装置からの流出水すなわち処理液中のＴＯＣ濃度を１０μｇ／Ｌまで減少させることが可能であることが明らかとなった。
【００６１】
また、原水に予め過酸化水素を添加した参考例２では、参考例１と比較して処理液中のＴＯＣ濃度は２０μｇ／Ｌとやや高いものの、比較例１で得られた結果５０μｇ／Ｌと比較して十分な効果が得られることがわかった。
【００６２】
更に、参考例３においては、循環処理を施さないでキャビテーション処理液に紫外線照射処理を行うことで、最終的に処理液のＴＯＣ濃度は１０μｇ／Ｌまで減少していることがわかった。
【００６３】
また、循環ライン６での紫外線照射を行う実施例１では、最終的に処理液中のＴＯＣ濃度は５μｇ／Ｌまで低減できた。
【００６４】
【発明の効果】
以上のことから明らかなように、本発明によると、超純水製造システム一次純水系の段階において、キャビテーション装置と電気再生式脱塩装置とを組み合わせることで、非イオン性ＴＯＣ成分を簡便な処理で且つ低コストで確実に除去できるという効果を奏する。
【図面の簡単な説明】
【図１】 本発明の一参考形態にかかる処理装置の概略図である。
【図２】電気再生式脱塩装置を概念的に説明す図である。
【図３】 本発明の他の参考形態にかかる処理装置の概略図である。
【図４】 本発明の一実施形態にかかる処理装置の概略図である。
【符号の説明】
１ 逆浸透膜（ＲＯ膜）
２ 加圧ポンプ
３ キャビテーションノズル
４ 電気再生式脱塩装置
５ ＴＯＣ測定装置
６ 循環ライン
７ 紫外線照射装置（ＵＶ）
８ 薬注タンク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a treatment apparatus and treatment method for organic substance-containing water, and is particularly suitable for removing a TOC component of an ultrapure water production system primary pure water system.
[0002]
[Prior art]
Conventional ultrapure water production systems use reverse osmosis membranes (RO membranes), ion-exchange resins to remove impurities such as fine particles, organic matter, ionic components, silica components, and bacteria from city water or industrial water that is raw water. It is comprised by units, such as an ultraviolet irradiation device and an ultrafiltration membrane (UF membrane).
[0003]
Such an ultrapure water production system includes a primary pure water system that produces pure water from raw water by combining these units, and a secondary pure water system that further purifies the pure water and supplies it to the use point as ultrapure water, a so-called subsystem. It consists of.
[0004]
In the primary pure water system, the TOC component having a relatively high concentration (several mg / L or more) is decomposed and reduced to about several hundred μg / L. In the subsystem, 5 mg / L to 500 μg / L in advance in the primary pure water system. It is necessary to bring the TOC component reduced to about L close to zero. Therefore, in general, the primary pure water system performs processes such as coagulation sedimentation, ion exchange, reverse osmosis membrane filtration, deaeration, and ion exchange, and the subsystem performs processes such as ultraviolet irradiation and mixed bed ion exchange. ing.
[0005]
In recent years, due to the rapid increase in the degree of integration of VLSI, high purity water quality is required for the ultrapure water that is the cleaning water. In order to satisfy the above-mentioned required water quality, reduction of the TOC component in the primary pure water is one of important issues. In particular, in a primary pure water system, it is an important issue to remove a nonionic TOC component that cannot be removed by an ion exchange device and a reverse osmosis membrane device.
[0006]
Recently, a large amount of ultrapure water is used for cleaning in the semiconductor manufacturing process. From the viewpoint of reducing environmental impact and effective use of water resources, recovery of cleaning wastewater used at point of use Reuse is widespread. Along with this, the TOC concentration to be treated is increasing as compared with a primary pure water system using only city water and industrial water as raw water.
[0007]
Therefore, in order to solve such a problem, in the primary pure water system, the nonionic TOC component in the water is converted into carbon dioxide, organic acid, and other volatile low-molecular compounds by ultraviolet oxidation treatment. A method and apparatus for removing a nonionic TOC component in water by combining a deaeration process and an ion exchange process have been proposed.
[0008]
[Problems to be solved by the invention]
However, when the TOC component in the water to be treated increases, there is a problem that the amount of ultraviolet rays increases and the running cost increases.
[0009]
In addition, if the ionic TOC component is removed by ion exchange treatment, resin regeneration with acid or alkali is required. To perform resin regeneration in intermittent operation, ultrapure water production is performed on the one hand, and resin regeneration on the other hand. There is a problem that a large-scale apparatus is required because a plurality of series of apparatuses that alternately repeats is required.
[0010]
As a method for solving this problem, it is conceivable to apply an electric regeneration type desalting treatment. In this processing method, since the regeneration of the ion exchange resin is continuously performed, the regeneration becomes unnecessary, and the equipment cost for that can be reduced, and the equipment size is 1/3 to 1/4 of that of the conventional apparatus. It can also be installed in narrow places where installation is not possible. Moreover, since there is no discharge | emission of the resin reproduction | regeneration waste liquid generated by an ion exchange process, there exists an advantage that an environmental load can be reduced.
[0011]
However, the electric regenerative desalination equipment has a more complex structure than an ion exchange resin packed tower and is sensitive to contamination by nonionic organic substances (TOC components), so it completely removes nonionic TOC components. There is a need to. For this reason, since the ultraviolet irradiation process performed beforehand must be performed completely, there exists a problem that a running cost further increases.
[0012]
The present invention has been made in view of such a situation, and in an ultrapure water production system primary pure water system, it contains an organic substance that can efficiently remove a nonionic TOC component at a low cost with a simple device. It is an object to provide a water treatment apparatus and a treatment method.
[0013]
[Means for Solving the Problems]
As a result of intensive efforts to solve the above-mentioned problems, the present inventors have combined non-treatment water with a cavitation device and an electric regenerative desalination device in a primary pure water system of an ultrapure water production system. The inventors have found that the ionic TOC component can be reliably removed easily and at low cost, and have completed the present invention.
[0014]
According to the first aspect of the present invention, a liquid feeding means that pressurizes and feeds an organic substance-containing water that is a liquid to be treated, and a pressurized processing liquid that is pressurized and fed by the liquid feeding means are injected. A cavitation generating means for generating cavitation in the sprayed pressurized processing liquid, a circulating means for returning the cavitation processing liquid processed by the cavitation to a preceding stage of the cavitation generating means, and a stage subsequent to the cavitation generating means. And an electric regenerative desalination apparatus for removing ionic substances in the cavitation treatment liquid, and an ultraviolet irradiation apparatus for irradiating the cavitation treatment liquid with ultraviolet light provided in the circulation path of the circulation means. It is in the processing equipment of organic substance containing water.
[0016]
According to a second aspect of the present invention, there is provided an apparatus for treating organic substance-containing water according to the first aspect, further comprising a reverse osmosis membrane device upstream of the cavitation generating means.
[0018]
According to a third aspect of the present invention, in the first or second aspect, the organic substance-containing water treatment apparatus is characterized in that pressurization by the liquid feeding means is 1 MPa or less.
[0020]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the apparatus further includes an oxidizing agent adding means for adding an oxidizing agent to the liquid to be treated. It is in.
[0021]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the TOC measurement means for measuring the TOC concentration of the treatment liquid from the electric regeneration type desalting apparatus is provided, and based on the measured value. In the apparatus for treating organic substance-containing water, the circulation by the circulation means is controlled.
[0022]
Here, the circulation control by the circulation means may be a circulation amount control or a circulation number control.
[0023]
In the sixth aspect of the present invention, cavitation is generated in the organic substance-containing water that is the liquid to be treated to convert the TOC component contained therein to an ionic substance, the cavitation treatment liquid is circulated, and the treatment is repeatedly performed and circulated. After the cavitation treatment liquid is irradiated with ultraviolet rays, an ionic substance contained in the cavitation treatment liquid is removed by an electric regeneration type desalination apparatus.
[0024]
In the present invention, a liquid subjected to any of the reverse osmosis membrane treatment, pressurization treatment for generating cavitation, injection treatment, addition of an oxidant for generating radicals, ultraviolet irradiation treatment, and electric regenerative desalination treatment. Is referred to as a liquid to be treated. Among any of the above-mentioned processes, a treatment liquid that has been or has been subjected to a specific process is referred to as follows in order to distinguish it from the liquid to be treated in particular. That is, the liquid to be treated before pressurization is “prepressurized liquid”, the pressurized liquid sent to the cavitation generating means is “pressurized liquid”, and the cavitation treatment is performed by spraying the pressurized liquid. The liquid that is discharged from the cavitation generating means is referred to as “cavitation treatment liquid”.
[0025]
In the present invention, the nonionic organic substance (TOC component) contained in the liquid to be treated is efficiently ionized by the cavitation treatment, and the ionic TOC component is removed by the electric regeneration type desalting apparatus. Can efficiently remove the TOC component.
[0026]
Here, the cavitation generating means is preferably a nozzle type cavitation apparatus, and in particular, one capable of effectively generating cavitation in the pressurized treatment liquid sent by the liquid feeding means at a pressure of 1 MPa or less. Further, it is particularly preferable to provide a circulating means for returning the cavitation processing liquid to the previous stage.
[0027]
In addition, an ultraviolet irradiation device may be additionally provided for ionization or decomposition of the remaining nonionic TOC component, and the installation position is not particularly limited, but the electric regenerative desalination device is located at a stage subsequent to the cavitation generating means. The front stage is preferable, and it is preferable to provide in the middle of the circulation path for returning the cavitation treated water to the front stage of the cavitation generating means.
[0028]
Further, a reverse osmosis membrane device may be provided for desalting, and the installation position is not particularly limited, but it is preferably provided in front of the cavitation generating means.
[0029]
Further, an oxidizing agent adding means may be provided, and its installation position is not particularly limited, but it is preferable to provide it before the cavitation generating means. In this case, the oxidizing agent is added to the untreated liquid to be treated, the pressure-treated water, or the cavitation treatment liquid in the circulation path.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an outline of a reference form of an ultrapure water production system primary pure water treatment apparatus to which the present invention is applied. As shown in FIG. 1, this processing apparatus includes a reverse osmosis membrane (RO membrane) 1, a pressurizing pump 2 that pressurizes and feeds a processing liquid from the reverse osmosis membrane (RO membrane) 1, and a pressurizing pump 2. From the cavitation nozzle 3 that injects pressurized pressurized processing liquid to generate cavitation in the processing liquid, the electric regenerative desalination apparatus 4 that processes the cavitation processing liquid, the TOC measurement apparatus 5, and the cavitation nozzle 3 And a circulation line 6 for returning the sprayed processing liquid to the front stage of the pressure pump 2. The reverse osmosis membrane (RO membrane) 1 and the circulation line 6 are not necessarily provided.
[0031]
The liquid to be treated, which is the waste water of the primary pure water system of the ultrapure water production system, is desalted by the reverse osmosis membrane (RO membrane) 1, then pressurized by the pressure pump 2, and sent to the cavitation nozzle 3. The pressurized pressurized processing liquid is ejected from the constricted portion of the cavitation nozzle 3 to generate a microcavity therein, and the microcavitation acts on the nonionic TOC component in the processing liquid. That is, when the generated microcavity collapses, it is said that a high temperature and high pressure environment (hot spot) of 5000 K, 500 atm, for example, is locally generated. In such a special space, “high temperature combustion” or “direct pyrolysis” occurs, so that organic matter is directly pyrolyzed. Further, even water molecules are decomposed into OH radicals and H atoms by thermal dissociation, and the nonionic TOC component contained in the liquid to be treated is converted into an ionic substance by the generated OH radicals.
[0032]
Wherein the ability of the pressure pump 2, 1 MPa or less, in the present reference embodiment, used was the 0.4 MPa.
[0033]
Further, the cavitation nozzle 3 for injecting the pressurized treatment liquid pressurized by the pressure pump 2 is, for example, as long as it efficiently generates cavitation in the pressurized treatment liquid fed at a pressure of 1 Mpa or less. The shape and structure are not particularly limited. That is, a microcavity can be effectively generated in the pressurized treatment liquid sprayed from the constricted portion of the cavitation nozzle 3, and water molecules are locally decomposed into OH radicals and H atoms due to the collapse of the microcavity. What is necessary is just to produce a high-pressure environment.
[0034]
In this preferred embodiment, it comprises a circulating line 6 for jetting a cavitation nozzle 3 again back at least a portion of the cavitation treatment liquid ejected from the cavitation nozzle 3 on the upstream side of the pressure pump 2, cavitation treatment liquid circulation The liquid to be treated that has passed through the line 6 is pressurized again by the pressurizing pump 2 and sprayed from the cavitation nozzle 3.
[0035]
In the circulation process performed using the circulation line 6, all of the injected cavitation treatment liquid may be circulated and repeated a predetermined number of times, for example, 2 to 50 times, or only a part of the cavitation treatment liquid may be used. You may make it circulate.
[0036]
In this way, a part of the treated water that has passed through the cavitation nozzle 3 is circulated to the cavitation nozzle 3 several times, thereby giving a plurality of times that the nonionic TOC component in the liquid to be treated is converted into an ionic substance. More complete ionization becomes possible. A switching means such as a valve (not shown) is provided at a branch point with the circulation line 6 on the downstream side of the cavitation nozzle 3 so that the liquid flows into the circulation line 6 at a predetermined rate and a predetermined number of times. Or the inflow can be stopped.
[0037]
By such circulation treatment, the TOC component in the liquid to be treated can be decomposed more efficiently. In this reference embodiment, the circulation is performed by the action of the pressurizing pump 2, but a pump for circulation may be provided separately.
[0038]
The treatment liquid that has been subjected to the cavitation treatment is sent to the electric regeneration type desalination apparatus 4, and ionized ionic substances are removed by the cavitation treatment.
[0039]
Here, the electric regeneration type desalting apparatus 4 is an apparatus that combines an ion exchange membrane and an ion exchange resin and continuously desalinates water with electric energy, and its concept is shown in FIG. The module of the electric regeneration type desalination apparatus 4 is composed of a number of compartments 11, and the compartments 11 are composed of a pair of cation exchange membranes 12 and anion exchange membranes 13 called cell pairs.
[0040]
The compartment 11 comprises a desalting chamber 11a and a concentrating chamber 11b alternately. Between the cation and anion exchange membranes 12 and 13 in the desalting chamber 11a, a cation exchange resin 14 and an anion exchange are provided. The resin 15 is mixed or filled with ion exchange fibers, and the cell pairs in the concentration chamber 11b are partitioned by a spacer (not shown).
[0041]
Due to the selective permeability of the membrane and the directionality of the potential gradient, anions move to the anode side, cations move to the cathode side, ions in the solution decrease in the desalting chamber 11a, and the adjacent concentration chamber 11b. Then it will be concentrated.
[0042]
The treated water that has flowed out of the electric regenerative desalting apparatus 4 is guided to the TOC measuring apparatus 5. In the TOC measuring device 5, the TOC concentration in the processing liquid is measured. Since the nonionic TOC component that has not been ionized by the cavitation treatment is not removed by the subsequent electric regeneration type desalination apparatus 4, the TOC concentration in the treatment liquid serves as a guideline for the effect of the cavitation treatment.
[0043]
The TOC measuring device 5 measures the TOC concentration in the treatment liquid from the electric regeneration type desalting device 4 and sets the circulation of the circulation line 6 according to the measured value. That is, how much the cavitation processing liquid should be circulated in the circulation line 6 may be determined by the measured value of the TOC component in the TOC measuring device 5. By providing the TOC measuring device 5 in this manner, the TOC component in the treatment liquid can be completely ionized and removed by the electric regeneration type desalting device 4, and the TOC component can be more reliably removed. Of course, it is needless to say that the TOC measuring device 5 is not necessarily provided.
[0044]
The liquid to be processed from which the TOC component has been removed to the target level is introduced into the subsystem.
[0045]
As shown in FIG. 3, the ultraviolet irradiation device 7 may be provided at the rear stage of the cavitation nozzle 3. The ultraviolet irradiation device 7 is for irradiating the cavitation treatment liquid with ultraviolet rays to change the remaining nonionic TOC component into an ionic substance. Moreover, it has the effect | action which accelerates | stimulates generation of OH radical and decomposes | disassembles a TOC component more completely. Although the installation position of such an ultraviolet irradiation device 7 is not particularly limited, it is preferably provided between the cavitation nozzle 3 and the electric regenerative demineralizer 4.
[0046]
In this case, the treatment liquid circulated in the circulation line 6 is not irradiated with ultraviolet rays. However, as shown in FIG. 4, an ultraviolet irradiation device 7 may be incorporated in the circulation path of the circulation line 6.
[0047]
Here, the ultraviolet irradiation device 7 is not particularly limited, and a device including a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, a hydrogen discharge tube, or the like can be used. The amount of ultraviolet rays to be irradiated is not particularly limited, and may be appropriately selected according to the type and concentration of the TOC component. However, when processing a liquid to be processed containing 0.005 to 0.06 mg / L of the TOC component. Is preferably 1 to 20 w · h. Thereby, radical generation can be promoted, and the effect of changing the remaining nonionic TOC component into an ionic substance can be obtained.
[0048]
In addition, as shown in FIG. 3, a chemical injection tank 8 for adding an oxidizing agent that is a radical generation accelerator to the pre-pressurizing solution before being pressurized by the pressurizing pump 2 may be provided. The chemical injection tank 8 is one of radical generating means. When an oxidizing agent is injected from the chemical injection tank 8, the generation of OH radicals by cavitation is promoted, and the TOC component in the liquid to be treated is more efficient. Is ionized.
[0049]
Here, as an oxidizing agent as a radical generation accelerator added from the chemical injection tank 8, hydrogen peroxide can be cited as a suitable example. In addition, an ozone generator or oxygen can be used instead of the chemical injection tank 8. A supply means (for example, an air diffuser) of the contained gas may be provided to supply ozone or oxygen.
[0050]
Although the addition amount of an oxidizing agent is suitably selected according to the kind, density | concentration, etc. of the TOC component in a to-be-processed liquid, the range of 1-50 mg / L is preferable normally.
[0051]
As described above, the location of the chemical injection tank 8 can also be selected as appropriate. The upstream side of the pressurizing pump 2, between the pressurizing pump 2 and the cavitation nozzle 3, downstream of the cavitation nozzle 3, and the circulation line 6. You may install in either.
[0052]
Although the to-be-processed liquid processed with such a processing apparatus will not be specifically limited if a TOC component is contained, For example, city water, industrial water, etc. are mentioned as an example. In addition, although the density | concentration of a TOC component is not specifically limited, It can use especially suitably for the to-be-processed liquid containing 500 microgram / L-5 mg / L trace amount.
[0053]
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, it is an illustration to the last, and this invention is not limited to this.
[0054]
( Reference Example 1)
The liquid to be treated having a TOC concentration of 100 μg / L in the raw water was treated using the apparatus shown in FIG. 1, and the entire cavitation treatment liquid was circulated 10 times using the cavitation circulation line 6. The TOC concentration of the treatment liquid flowing out from the electric regeneration type desalting apparatus 4 was 10 μg / L. The results are shown in Table 1.
[0055]
( Reference Example 2)
Using the liquid to be treated having the same TOC concentration as the raw water used in Reference Example 1, 35% hydrogen peroxide as an oxidizing agent was added to the raw water before pressurization to a concentration of 5 mg / L, and the same as in Reference Example 1 The cavitation decomposition process was carried out using the apparatus. The circulation line was not used and the decomposition process by cavitation was performed only once. The TOC concentration in the treatment liquid flowing out from the electric regeneration type desalting apparatus was 20 μg / L. The results are shown in Table 1.
[0056]
( Reference Example 3)
The same raw water as that used in Reference Example 1 was subjected to cavitation decomposition treatment using the same apparatus as in Reference Example 1 without using a circulation line, and then irradiated with ultraviolet light having a wavelength of 254 nm. The nonionic TOC concentration in the treatment liquid flowing out from the electric regeneration type desalting apparatus was 10 μg / L. The results are shown in Table 1.
[0057]
( Example 1 )
In Reference Example 1, the number of circulations of the cavitation treatment liquid was set to 5 times, and the same treatment as in Reference Example 1 was performed except that the ultraviolet ray treatment apparatus used in Reference Example 3 was provided in the circulation line. It was. The TOC concentration of the treatment liquid flowing out from the electric regeneration type desalting apparatus was 5 μg / L. The results are shown in Table 1.
[0058]
(Comparative Example 1)
The raw water same as the raw water of Reference Example 1 was subjected to ultraviolet irradiation and treatment with an electric regenerative desalting apparatus without performing cavitation decomposition treatment. When the ultraviolet ray with a wavelength of 254 nm was irradiated, the TOC concentration in the treatment liquid flowing out of the electric regeneration type desalting apparatus was 50 μg / L. The results are shown in Table 1.
[0059]
[Table 1]

[0060]
The TOC concentration in the treatment liquid is reduced only to 50 μg / L by only one cavitation treatment. However, as is clear from Table 1 , the effluent from the equipment is circulated by providing a circulation line in the equipment and circulating the treatment liquid. It was revealed that the TOC concentration in water, that is, the treatment liquid, can be reduced to 10 μg / L.
[0061]
Further, in Reference Example 2 in which hydrogen peroxide was added to the raw water in advance, the TOC concentration in the treatment liquid was slightly higher than 20 μg / L compared to Reference Example 1, but the result obtained in Comparative Example 1 was 50 μg / L. It was found that a sufficient effect was obtained in comparison.
[0062]
Furthermore, in Reference Example 3, it was found that the TOC concentration of the treatment liquid was finally reduced to 10 μg / L by performing the ultraviolet irradiation treatment on the cavitation treatment liquid without performing the circulation treatment.
[0063]
Moreover, in Example 1 which irradiates the ultraviolet ray in the circulation line 6, the TOC density | concentration in a process liquid was able to be finally reduced to 5 microgram / L.
[0064]
【The invention's effect】
As is apparent from the above, according to the present invention, the non-ionic TOC component can be easily treated by combining the cavitation device and the electric regenerative desalination device in the primary pure water system stage of the ultrapure water production system. In addition, there is an effect that it can be reliably removed at low cost.
[Brief description of the drawings]
FIG. 1 is a schematic view of a processing apparatus according to a reference embodiment of the present invention.
FIG. 2 is a diagram conceptually illustrating an electric regenerative desalination apparatus.
FIG. 3 is a schematic view of a processing apparatus according to another reference embodiment of the present invention.
Figure 4 is a schematic view of a processing apparatus in an embodiment of the present invention.
[Explanation of symbols]
1 Reverse osmosis membrane (RO membrane)
2 Pressure Pump 3 Cavitation Nozzle 4 Electric Regenerative Desalination Device 5 TOC Measurement Device 6 Circulation Line 7 Ultraviolet Irradiation Device (UV)
8 medicine tank

Claims (6)

A liquid feeding means that pressurizes and feeds the organic substance-containing water, which is a liquid to be treated, and a pressurized processing liquid that is pressurized and sent by the liquid feeding means, and is injected into the ejected pressurized processing liquid A cavitation generating means for generating cavitation, a circulation means for returning the cavitation processing liquid treated by the cavitation to the previous stage of the cavitation generating means, and an ionic substance in the cavitation processing liquid provided at the subsequent stage of the cavitation generating means. An apparatus for treating organic-containing water , comprising: an electric regenerative desalination apparatus to be removed; and an ultraviolet irradiation apparatus which is provided in a circulation path of the circulation means and irradiates ultraviolet rays to a cavitation treatment liquid .   The apparatus for treating organic substance-containing water according to claim 1, further comprising a reverse osmosis membrane device upstream of the cavitation generating unit. The apparatus for treating organic substance-containing water according to claim 1 or 2 , wherein the pressure applied by the liquid feeding means is 1 MPa or less. In any one of claims 1 to 3, further wherein the organic substance-containing water, characterized by comprising an oxidizing agent adding means for adding an oxidizing agent into the processing solution processing unit. In any one of Claims 1-4 , it comprises the TOC measurement means which measures the TOC density | concentration of the process liquid from the said electric regeneration type | formula desalination apparatus, and controls the circulation by the said circulation means based on this measured value. A device for treating organic substance-containing water. The TOC component contained by generating cavitation in the organic substance-containing water, which is the liquid to be treated, is converted into an ionic substance, the cavitation treatment liquid is circulated, the treatment is repeated, and the circulated cavitation treatment liquid is irradiated with ultraviolet rays. Then, an ionic substance contained in the cavitation treatment liquid is removed by an electric regeneration type desalination apparatus.

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