JPH1199394A - Method for removing organic matter in water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for removing org. matter in the water using a sulfur compd. contg. a peroxide group by which the consumption of the compd. is cut down, the cost to remove the org. matter is reduced, the corrosion of a reaction vessel for removing the org. matter is suppressed, the load on the treatment of the sulfate ion as a by-product is decreased, and the scaling up of the equipment is restricted. SOLUTION: This method consists of the first stage for adding hydrogen peroxide and/or ozone to the water to be treated to decompose and remove the org. matter and the second stage for adding a sulfur compd. contg. a peroxide group to the water treated in the first stage to decompose and remove the org. matter. For example, hydrogen peroxide and/or ozone are added to the water to be treated by the adding means 2 to bring about a reaction in the first reactor, 4 (the first stage) and then a sulfur compd. contg. a peroxide group is added to the water treated in the first stage from the adding means 6 to cause a reaction in the second reactor 8 (the second stage).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for decomposing and removing organic substances contained in water to be treated. The organic matter removing method of the present invention is, for example, a manufacturing process of pure water used in a semiconductor manufacturing plant, a liquid crystal manufacturing plant, a nuclear power plant, a pharmaceutical manufacturing plant or the like, or factory wastewater, human wastewater, leachate from a garbage treatment plant. Etc. are suitably used for the treatment of wastewater. Note that, in this specification, high-purity water, which is generally described in terms of pure water, ultrapure water, and the like, which are not necessarily clearly defined, is collectively referred to as “pure water”.

[0002]

2. Description of the Related Art The amount of pure water used as semiconductor manufacturing water is increasing year by year, and at the same time, further improvement in water quality is required with an increase in LSI integration. In the production of pure water, an inorganic substance and an organic substance contained in the raw water are removed. Among them, the removal of the organic substance is extremely important in improving the quality of pure water.

[0003] The removal of organic substances contained in water is generally performed by combining various unit operations. For example,
Coagulation sedimentation, adsorption with activated carbon, ion exchange, separation using reverse osmosis membrane or ultrafiltration membrane, etc. are performed, and after removing most of the organic matter by these treatments, the remaining organic matter is further decomposed. Elimination has been done. Further, washing wastewater after using pure water as washing water in semiconductor manufacturing is collected, dissolved organic matter is decomposed and removed, and then reused.

[0004] Organic wastes are also decomposed and removed in wastewater treatment processes such as industrial wastewater, human wastewater, and leachate from garbage disposal plants. These wastewaters are required to be discharged into the environment after removal treatment of harmful substances and pollutants. Among the methods for treating organic substances, conventionally, ozone oxidation, ultraviolet oxidation, biological Processing methods and the like are used.

As a method for decomposing organic substances in water, ozone oxidation, ultraviolet oxidation, catalytic wet oxidation, and biological treatment have been mainly used. In the ozone oxidation method, ozone is dissolved in water to be treated, and organic substances are oxidatively decomposed and removed by the oxidizing power of ozone. However, there are organic substances which are difficult to decompose in this method, and therefore it is difficult to significantly reduce the organic substances by the ozone oxidation method.

The ultraviolet oxidation method irradiates the water to be treated with ultraviolet light having a specific wavelength from an ultraviolet light source to oxidatively decompose and remove organic substances contained in the water to be treated. In recent years,
In order to further increase the efficiency of oxidative decomposition of organic substances, a method of adding hydrogen peroxide or ozone to water to be treated in advance and then irradiating the water to be treated with ultraviolet rays has been used. In this method, hydrogen peroxide or ozone that has absorbed ultraviolet rays generates highly reactive chemical species such as hydroxyl radicals, and these chemical species react with organic substances contained in the water to be treated.
Organic matter is removed by oxidative decomposition.

However, in the above-described method of irradiating the water to be treated with hydrogen peroxide or ozone with ultraviolet rays, there are organic substances which are difficult to decompose as in the ozone oxidation method. It is difficult to make it. For example, it is known that tetramethylammonium hydroxide used as a stripping agent in a semiconductor developing process is hardly decomposed even when ultraviolet light is irradiated after adding hydrogen peroxide or ozone to water to be treated.

Organic substances which are difficult to decompose by the ozone oxidation method or the ultraviolet oxidation method include, in addition to the above-mentioned tetramethylammonium hydroxide, for example, butyl acetate and the like as esters, glycine and the like as amino acids, and ethylenediamine tetra as a nitrogen compound. Acetic acid, triethanolamine, diethanolamine, monoethanolamine, melanin,
Hexamethylenetetramine, monoethylaniline, diethylaniline, acrylonitrile, formamide, nitrobenzene, etc .; sulfur compounds such as dimethyl sulfoxide; ketones such as methyl isobutyl ketone; ethers such as ethyl ether, diethyl ether, dioxane; alcohols such as tertiary alcohol Butyl alcohol, diethylene glycol and the like, phenols such as pyrogallol, aromatic hydrocarbons such as benzene, toluene, xylene and naphthalene, substituted aromatic hydrocarbons such as α-methylnaphthalene, and halogenated hydrocarbons such as trichloroethylene, ethylene dichloride, chloroform, Carbon tetrachloride, monochlorobenzene, polychlorinated biphenyl,
Examples include dioxins and the like, and other organic substances similar to these.

In the catalytic wet oxidation method, water to be treated containing organic substances is passed through a packed tower filled with catalyst particles such as manganese dioxide, and the organic substances are oxidatively decomposed and removed under high pressure and high temperature. However, this method requires processing under high pressure and high temperature, so that the processing cost increases. Also, special considerations are required in terms of safety, which further increases processing costs.

[0010] The biological treatment method decomposes and removes organic substances in the water to be treated by living organisms constituting activated sludge and the like. The biological treatment method has a very low treatment cost, but the organic matter to be degraded is limited to those that have biodegradability.
Even with this method, it is difficult to significantly reduce organic matter.

Therefore, a method using the oxidizing power of a sulfur compound containing a peroxide group has been proposed as a more powerful and safer method for decomposing organic substances. For example, German Patent Specification 149799 discloses a method for producing pure water using peroxydisulfate. in this way,
Add peroxydisulfate and catalyst to the water to be treated,
The organic matter is oxidatively decomposed by heating to ８０80 ° C., and pure water is obtained by further performing a distillation treatment.

[0012]

Since a sulfur compound containing a peroxide group has a very strong oxidizing power, the above-mentioned method for removing an organic substance using the compound effectively removes the organic substance regardless of the kind of the organic substance. Has the advantage of being able to be oxidatively decomposed and removed, but has the disadvantage of requiring large amounts of sulfur compounds containing peroxide groups.

For example, the case where the organic substance is isopropyl alcohol and the sulfur compound containing a peroxide group is a peroxydisulfate ion will be described. The oxidative decomposition reaction of the organic substance at this time is represented by the following formula (1). You. _{C 3 H 7 OH + 9S 2} O 8 2- + 5H 2 O → 3CO 2 + 18SO 4 2- + 18H + ... (1)

As is apparent from the formula (1), 9 moles of peroxydisulfate ions are required to oxidize and decompose 1 mole of isopropyl alcohol. As described above, the method of oxidatively decomposing and removing an organic substance using a sulfur compound containing a peroxide group has the following problems since the compound is required in a large amount.

First, since a large amount of a sulfur compound containing a peroxide group is used, the chemical cost of the sulfur compound containing a peroxide group increases, and the treatment cost increases.

Secondly, since a sulfur compound containing a peroxide group has a very strong oxidizing power, when a large amount of the compound is used, a reaction vessel for removing organic substances easily corrodes. For example, in this method, a reaction vessel made of stainless steel is usually used. However, in a reaction vessel made of stainless steel 304, when a large amount of a sulfur compound containing a peroxide group is used, it is easily corroded.

Third, in order to obtain high-purity water, it is necessary to remove a sulfate ion as a by-product by performing a deionization treatment step after the organic matter removal step. If a large amount of the sulfur compound is used, the amount of by-products of sulfate ions increases, which increases the load of the deionization process and increases the size of the equipment for the deionization process. For example, assuming that the organic substance is isopropyl alcohol and the sulfur compound containing a peroxide group is a peroxydisulfate ion, as apparent from the formula (1), when 1 mol of isopropyl alcohol is oxidized and decomposed, 18 moles of sulfate ions are produced as by-products. This sulfate ion
It can be separated and removed by ordinary deionization treatment such as distillation treatment, ion exchange treatment, reverse osmosis membrane treatment, but the load on the deionization treatment equipment increases as the amount of sulfate ion by-product increases. In addition, the equipment scale of the deionization processing equipment becomes large.

The present invention has been made in view of the above circumstances, and is a method for removing organic substances in water using a sulfur compound containing a peroxide group.
Thus, the organic substance removing method which reduces the cost of the organic substance removing treatment, suppresses the corrosion of the reaction vessel for removing the organic substance, and reduces the load of the treatment step of sulfate ion as a by-product and suppresses the enlargement of equipment in the step. The purpose is to provide.

[0019]

Means for Solving the Problems The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, when decomposing and removing organic substances contained in the water to be treated, first, A first organic substance treatment step of decomposing and removing organic substances by adding hydrogen peroxide and / or ozone to water is performed, and then a sulfur compound containing a peroxide group is added to the treated water of the first organic substance treatment step to form an organic substance. By performing a second organic matter treatment step of decomposing and removing the above, the amount of use of the sulfur compound containing a peroxide group is reduced and the above-described first to third substances are reduced.
The inventors have found that the above problem can be solved, and have accomplished the present invention.

That is, in the organic substance removing method using hydrogen peroxide and / or ozone, there are organic substances which are difficult to decompose. First, an organic substance which can be removed with hydrogen peroxide and / or ozone in the first organic substance treatment step. Removed from the water to be treated,
By removing the remaining hydrogen peroxide and / or organic substances that cannot be removed by ozone using a sulfur compound containing a peroxide group in the second organic substance treatment step,
In addition to being able to remove organic substances that were difficult to remove by conventional organic substance removal methods, the amount of organic substances to be removed by using a sulfur compound containing a peroxide group is reduced, so that the amount of the compound used can be reduced. As a result, they have found that the cost of removing organic substances can be reduced.

Therefore, according to the present invention, in decomposing and removing the organic matter contained in the water to be treated, a first step in which hydrogen peroxide and / or ozone is added to the water to be treated to decompose and remove the organic matter, A second step of adding a sulfur compound containing a peroxide group to treated water in one step to decompose and remove organic substances, and a method for removing organic substances in water.

Further, the present inventors have found that the object of the present invention can be more effectively achieved by adding the following constitutions to the above-mentioned basic constitutions as described later. And performing a third step of deionizing the treated water in the second step. In the first step, the water to be treated to which hydrogen peroxide and / or ozone has been added is irradiated with ultraviolet rays to decompose and remove organic substances. In the first step, organic matter is decomposed and removed while the water to be treated is heated. In the second step, the treated water in the first step to which a sulfur compound containing a peroxide group is added is irradiated with ultraviolet rays to decompose and remove organic substances. In the second step, the treated water in the first step to which the sulfur compound containing a peroxide group is added is irradiated with ultraviolet rays while heating the treated water to decompose and remove organic substances. In the second step, the treated water of the first step to which the sulfur compound containing a peroxide group is added is heated to 70 ° C. or more to decompose and remove organic substances. Performing the second step after removing or decomposing the oxidizable inorganic substance contained in the treated water in the first step.

Hereinafter, the present invention will be described in detail. FIG. 1 shows an example of a process chart for carrying out the present invention. In FIG. 1, reference numeral 2 denotes a hydrogen peroxide and / or ozone adding means for adding hydrogen peroxide and / or ozone to the water to be treated, 4 denotes a first reactor, 6
Denotes a sulfur compound adding means for adding a sulfur compound containing a peroxide group to the treated water of the first reactor 4, and 8 denotes a second reactor. As shown in this process diagram, first, an appropriate amount of hydrogen peroxide and / or ozone is added to the water to be treated by the hydrogen peroxide and / or ozone adding means 2, and the reaction is performed in the first reactor 4. The organic matter is oxidatively decomposed and removed (first step). Next, an appropriate amount of a sulfur compound containing a peroxide group is added to the treated water in the first step from the sulfur compound adding means 6 to cause a reaction in the second reaction device 8, and organic substances are oxidatively decomposed and removed. 2 steps). Although not particularly shown, an appropriate amount of hydrogen peroxide and / or ozone may be directly added to the water to be treated in the first reactor 4 by the hydrogen peroxide and / or ozone adding means 2, and the sulfur compound may be added. Means 6 may be used to directly add an appropriate amount of a sulfur compound containing a peroxide group to the water to be treated in the second reactor 8. Further, if necessary, another step may be performed between the first step and the second step.

As can be seen from the above description, according to the present invention, first, a first step of decomposing and removing organic substances by adding hydrogen peroxide and / or ozone to the water to be treated is carried out, whereby the water contained in the water to be treated is contained. Decompose organic substances that are relatively easily oxidized.

In the first step, a catalyst for accelerating the oxidation reaction may be arranged in the reaction vessel, and the oxidative decomposition reaction may be performed while bringing the water to be treated into contact with the catalyst. As the catalyst, a known catalyst having an effect of accelerating an oxidation reaction such as a platinum-based catalyst, a palladium-based catalyst, and a manganese-based catalyst can be used. Further, a method of oxidatively decomposing organic substances by using nickel oxide as a catalyst for hydrogen peroxide, which is introduced in PPM Magazine, June 1984, p. 54, can also be used.

In the first step, as described in, for example, JP-A-10-85770, a method in which water to be treated is made alkaline and then ozone is dissolved to oxidatively decompose organic substances can be employed. .

Further, in the first step, hydrogen peroxide and ozone may be used in combination.
ol. 33, no. 6, page 273 (1992), a method of oxidatively decomposing organic substances in the presence of ozone and hydrogen peroxide.

Next, in the present invention, the treated water in the first step is
Of the first step by adding a sulfur compound containing
A second step of decomposing and removing organic substances remaining in the water
U. Here, a sulfur compound containing a peroxide group refers to a molecule
Sulfur compound containing a peroxide group [-OO-] in the structure
And such sulfur compounds include, for example,
Peroxydisulfate ion S_TwoO₈ ^2-Salts or acids containing
Roxysulfate ion SO _Five ^-And salts or acids containing
be able to. Peroxides that can be suitably used in the present invention
More specifically, as a sulfur compound containing a group,
Nato peroxydisulfate is easy and easy to handle.
Lithium salt Na_TwoS_TwoO₈, Ammonium peroxydisulfate
Salt (NH_Four)_TwoS_TwoO₈, Potassium peroxydisulfate K_Two
S_TwoO₈And the like. Also, peroxysulfuric acid
Oxone, a double salt containing ions
Is also preferable.

In the second step, as in the first step,
A catalyst for accelerating the oxidation reaction may be disposed in the reaction vessel, and the oxidative decomposition reaction may be performed while bringing the water to be treated into contact with the catalyst. As the catalyst, a known catalyst having an effect of accelerating an oxidation reaction such as a platinum-based catalyst, a palladium-based catalyst, and a manganese-based catalyst can be used.

As the reaction vessel for performing the organic substance removing reaction in the first step and the second step, a known reaction vessel such as a cylindrical reaction vessel for forming an extruded flow or a tank-type reaction vessel for forming a completely mixed flow may be used. Can be. Also, to make the concentration distribution in the reaction vessel uniform,
It is also preferred to equip the reaction vessel with a stirrer. As the stirring device, a known device can be used, for example,
A device for generating and stirring air bubbles from a diffuser plate provided at the bottom of the reaction vessel, a device for installing and stirring a fluid circulation pump inside or outside the reaction vessel, and the like can be used.

When the first step and the second step are performed in this order as shown in FIG. 1, organic substances contained in the water to be treated can be significantly reduced. Also,
Since the organic matter that can be removed with hydrogen peroxide and / or ozone in the first step is previously removed from the water to be treated, the amount of the organic matter to be removed in the second step using a sulfur compound containing a peroxide group is reduced, and the second step is reduced. Since the amount of the sulfur compound containing a peroxide group used in the above is reduced, it is possible to effectively prevent the reaction vessel in the second step from corroding.

Further, in the present invention, by using hydrogen peroxide and / or ozone in the first step, when high-purity water is obtained, the deionization treatment step (third step) performed after the second step is performed. The load can be reduced. That is,
In the method of oxidatively decomposing organic substances by adding hydrogen peroxide and / or ozone to the water to be treated, a hydroxyl radical, which is a highly reactive active radical generated from hydrogen peroxide and / or ozone, converts organic substances. In this method, oxygen is produced as a by-product, but it does not produce an ionic substance. Therefore, an extra load may be applied to the deionization treatment step subsequent to the second step. Absent.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION The organic substance removing method of the present invention to which the above constitutions are added will be described. First, the point will be described. The present inventors have found that in the method for removing organic substances using a sulfur compound containing a peroxide group, sulfate ions are generated as by-products.
It has been conceived that the third step of deionizing the treated water in the step may be further performed to remove the sulfate ions.

Sulfate ions generated as a by-product of the reaction in the second step are usually removed by performing the third step. The type of the deionization treatment used in the third step is not limited, and examples thereof include an ion exchange treatment using an ion exchange resin and a deionization treatment using a reverse osmosis membrane.

However, in the present invention, hydrogen peroxide and / or ozone which does not generate ionic substances in the first step are used, and the amount of the sulfur compound containing a peroxide group used in the second step is reduced. The amount of by-products of sulfate ions in the two steps is reduced. Therefore, according to the present invention, it is possible to reduce the load in the third step and to reduce the size of the equipment in the third step.

FIG. 2 shows an example of a process diagram for carrying out the present invention with the addition of the configuration described above. In FIG. 2, reference numeral 10 denotes hydrogen peroxide adding means for adding hydrogen peroxide to the water to be treated, 4 denotes a first reactor, 6 denotes a sulfur compound adding means, 8 denotes a second reactor, 1
Reference numeral 2 denotes a deionizer. As shown in this process diagram, first, an appropriate amount of hydrogen peroxide is added to the water to be treated by the hydrogen peroxide adding means 10, and the reaction is carried out in the first reactor 4 to oxidatively decompose organic substances. And removed (first step). Next, an appropriate amount of a sulfur compound containing a peroxide group is added to the treated water in the first step from the sulfur compound adding means 6 to cause a reaction in the second reaction device 8, and organic substances are oxidatively decomposed and removed. 2 steps). Further, by passing the treated water of the second step through the deionization treatment apparatus 12 (third step)
Step), it is possible to obtain pure water in which the concentration of organic substances and the concentration of ions such as sulfate ions are significantly reduced.

FIG. 3 shows an example of a process diagram when ozone is used in the first step. In FIG. 3, 14 is an ozone dissolving device for adding ozone to the water to be treated, 16 is an ozone generating device for supplying ozone to the ozone dissolving device 14, 4 is a first reactor, 6 is a sulfur compound adding means, and 8 is a 2 reactors, 1
Reference numeral 2 denotes a deionizer. As shown in this process diagram, first, ozone generated by an ozone generator 16 is dissolved in water to be treated by an ozone dissolving device 14, and a reaction is performed by a first reaction device 4 to remove organic matter. It is removed by oxidative decomposition (first step). Thereafter, by performing the second step and the third step in the same manner as in the example shown in FIG. 2, pure water in which the concentration of organic substances and the concentration of ions such as sulfate ions are significantly reduced can be obtained.

The point will be described. The present inventors improve the efficiency of removing organic substances in the first step by irradiating the water to be treated with hydrogen peroxide and / or ozone with ultraviolet rays to decompose and remove organic substances in the first step, It has been conceived that organic matter can be significantly reduced.

In the method of irradiating the water to be treated with hydrogen peroxide and / or ozone with ultraviolet rays to oxidize and decompose organic substances, the hydrogen peroxide and / or ozone absorbing the ultraviolet rays has high reaction activity such as hydroxyl radicals. Generate chemical species,
These chemical species react with organic substances contained in the water to be treated, thereby oxidatively decomposing and removing the organic substances. In this method, the substance to be added is hydrogen peroxide and / or ozone, which does not increase the salt load at all, and can improve the efficiency of removing organic substances. It can be used particularly effectively.

As an example of carrying out the present invention with the addition of the configuration described above, there is a method of installing a light source for irradiating ultraviolet rays in the reaction vessel of the first reaction apparatus 4 in the system shown in FIGS. . As a light source for irradiating ultraviolet rays,
Known high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, halogen lamps, metal halide lamps, xenon lamps, indium lamps, thallium lamps, and ultraviolet light emitting lasers can be used.
High-pressure, medium-pressure, and low-pressure mercury lamps can be particularly preferably used in that organic substances can be efficiently decomposed.

In the present invention to which the above-mentioned structure is added, the oxidation reaction is performed by irradiating the reaction vessel in the first step with ultraviolet rays such as titanium dioxide and tungsten oxide instead of or together with the above-mentioned catalyst. A photocatalyst that promotes the reaction can be provided.

The point will be described. In performing the first step of decomposing and removing organic substances by adding hydrogen peroxide and / or ozone to the water to be treated, the present inventors perform the second step by performing the treatment while heating the water to be treated. It has been conceived that the amount of the sulfur compound containing a peroxide group can be reduced and the amount of sulfate ion by-products in the second step can be reduced.

In the present invention with the addition of the structure, the oxidative decomposition rate of the organic matter tends to increase as the temperature of the water to be treated is higher. Therefore, the higher the water temperature of the water to be treated, the higher the efficiency of removing the organic matter is. . However, preferred is
The temperature of the water to be treated is set to 40 ° C. or higher and lower than 100 ° C. When the temperature of the to-be-treated water reaches 100 ° C., boiling occurs and handling becomes troublesome. When the temperature is lower than 40 ° C., the improvement of the efficiency of removing organic substances by heating is not worth the cost required for heating. More preferably, the temperature of the water to be treated is 40 ° C. or more and 70 ° C.
It is as follows. If it exceeds 70 ° C, the heating cost will increase,
Not economically feasible.

The point will be described. The present inventors improve the efficiency of removing organic substances in the second step by irradiating the treated water in the first step to which the sulfur compound containing a peroxide group is added with ultraviolet rays in the second step to decompose and remove the organic substances. Thus, the present inventors have conceived that organic substances can be significantly reduced.

Sulfur compounds containing a peroxide group generate free radicals when irradiated with ultraviolet rays. For example, the reaction of generating free radicals by irradiating peroxydisulfate ions with ultraviolet rays is as shown in the following formula (2). S ₂ O ₈ ^2- → 2SO ₄・^- (2)

[0046] The free radical SO ₄ · ^- has a very strong oxidizing power, oxidized organic matter according to the reaction shown in equation (3), eventually allowed to reach completely oxidize and decompose organic matter Is possible. Note that e ⁻ in the formula (3) is an electron deprived of an organic substance. The sulfate ion generated as a by-product of the reaction is usually removed by performing the third step. SO ₄・⁻ + e ⁻ → SO ₄ ^2- … (3)

As an example of carrying out the present invention with the addition of the configuration described above, there is a method of installing a light source for irradiating ultraviolet rays in the reaction vessel of the second reaction apparatus 8 in the system shown in FIGS. . As a light source for irradiating ultraviolet rays,
There are various types as described above. However, according to the findings of the present inventors, a sulfur compound containing a peroxide group absorbs only ultraviolet light having a wavelength of 300 nm or less, and generates free radicals using the energy of the absorbed ultraviolet light. Therefore, when a low-pressure mercury lamp whose main emission wavelength is 254 nm is used as a light source, most of the light energy is absorbed by a sulfur compound containing a peroxide group.
Free radicals can be efficiently generated, and the power cost required for ultraviolet irradiation can be significantly reduced. Therefore, in the present invention to which the above configuration is added, a low-pressure mercury lamp is particularly preferable as a light source for irradiating ultraviolet rays used in the second step.

The reaction of the above formulas (2) and (3) in the present invention with the addition of the above structure proceeds regardless of the pH of the water to be treated. The pH of the water is preferably 2 to 12. Also,
If necessary, a pH adjusting agent injection device for adding an acid or alkali solution to the water to be treated may be provided in order to adjust the pH of the water to be treated.

In the present invention to which the above-mentioned structure is added, the oxidation reaction is performed by irradiating the reaction vessel in the second step with ultraviolet rays such as titanium dioxide and tungsten oxide instead of or together with the above-mentioned catalyst. A photocatalyst that promotes the reaction can be provided.

The point will be described. The present inventors irradiate the treated water of the first step, to which a sulfur compound containing a peroxide group is added, with ultraviolet rays in the second step to decompose and remove organic substances, and in a state where the treated water of the first step is heated. It has been conceived that by performing the treatment, the efficiency of removing organic substances in the second step can be improved and the amount of organic substances can be significantly reduced.

In the present invention to which the structure of the first step is added, the higher the temperature of the treated water in the first step to which a sulfur compound containing a peroxide group is added, the higher the rate of oxidative decomposition of organic substances tends to increase. The higher the water temperature of the water, the higher the organic matter removal efficiency. However, it is preferable that the temperature of the treated water in the first step be 40 ° C. or more and less than 100 ° C. When the temperature of the treated water reaches 100 ° C., boiling occurs and handling becomes troublesome. When the temperature of the treated water is lower than 40 ° C., an improvement in the efficiency of removing organic substances by heating is not worth the cost required for heating. The temperature of the treated water in the first step is more preferably 40 ° C. or more and 70 ° C. or less. If the temperature exceeds 70 ° C., the efficiency of removing organic substances is not so much improved although the heating cost is increased, so that it is not economically advantageous.

It is preferable that the present invention to which the configuration is added is used together with the invention to which the configuration is added. FIG. 4 shows an example of a process diagram for carrying out the present invention with the addition of the configuration shown in FIG.
Shown in In FIG. 4, 18 is a heat exchanger, 20 is an auxiliary heating device, 10 is hydrogen peroxide addition means, 4 is a first reactor, 6 is a sulfur compound addition means, 8 is a second reactor, 12
Indicates a deionization apparatus. The heat exchanger 18 performs heat exchange between the water to be treated and the treated water in the second step, and
At 0, the water to be treated flowing out of the heat exchanger 18 is heated.
A light source for irradiating ultraviolet rays is installed in the reaction vessel of the second reaction device 8. Further, a light source for irradiating ultraviolet rays may be provided in the reaction vessel of the first reaction device 4. Further, although not particularly shown, the hydrogen peroxide adding means 10 may be provided before the auxiliary heating device 20 or the heat exchanger 18.

As shown in this process chart, first,
The to-be-treated water is passed through the heat exchanger 18 to recover heat energy from the treated water in the second step in a heated state to heat the to-be-treated water. Further, after the water to be treated is heated to a predetermined temperature by the auxiliary heating device 20, the first step is performed by the hydrogen peroxide adding means 10 and the first reactor 4, and further, the sulfur compound adding means 6 and the second reactor 8 Performs the second step. Next, the treated water of the second step is passed through the heat exchanger 18 to supply heat energy to the water to be treated and to lower the temperature of the treated water of the second step. Then, by passing the treated water of the second step through the deionization treatment device 12, it is possible to obtain pure water in which the concentration of organic substances and the concentration of ions such as sulfate ions are significantly reduced.

Here, as the heating means of the auxiliary heating device 20, known means such as means using an electric heater or means using steam heating can be applied. Although not particularly shown, the auxiliary heating device 20 may be installed in the first reaction device 4. Further, if necessary, an auxiliary heating device for further heating the treated water in the first step can be installed at an arbitrary position on a route from the first reactor 4 to the second reactor 8.

The point will be described. The present inventors heated the treated water in the first step to which the sulfur compound containing a peroxide group was added in the second step to 70 ° C. or more to decompose and remove the organic substances, thereby removing the organic substances in the second step. And that organic substances can be significantly reduced.

The sulfur compound containing a peroxide group is 70%
Free radicals are generated by heating above ℃. The reaction is the same as in the above formula (2). This free radical SO
₄ · ^-has a very strong oxidizing power, and can oxidize organic substances according to the reaction shown in the above formula (3), and finally can completely cause oxidative decomposition of the organic substances.

The amount of free radicals generated from a sulfur compound containing a peroxide group tends to increase as the water temperature increases. Therefore, the higher the water temperature, the higher the organic matter removal efficiency.

This configuration is particularly effective when the organic matter is decomposed only by adding a sulfur compound containing a peroxide group without performing ultraviolet irradiation in the second step. In the case where the above-described configuration in which the ultraviolet irradiation is performed in the second step is employed, a strong oxidizing power is obtained by a synergistic effect of the sulfur compound containing a peroxide group and the ultraviolet light. It is.

FIG. 5 shows an example of a process diagram for carrying out the present invention with the addition of the configuration described above. In FIG. 5, reference numeral 10 denotes a hydrogen peroxide adding unit, 4 denotes a first reactor, 18 denotes a heat exchanger, 20 denotes an auxiliary heating unit, 6 denotes a sulfur compound adding unit, and 8 denotes a second reactor. The heat exchanger 18 performs heat exchange between the treated water of the first step and the treated water of the second step, and the auxiliary heating device 20 heats the treated water of the first step flowing out of the heat exchanger 18.
Although not particularly shown, the sulfur compound adding means 6 may be provided before the auxiliary heating device 20 or the heat exchanger 18.

As shown in this process chart, first,
The first step is performed by the hydrogen peroxide addition means 10 and the first reactor 4. Next, the treated water of the first step is transferred to the heat exchanger 1
8, heat energy is recovered from the treated water of the second step in a heated state, and the treated water of the first step is heated. Next, after the treated water of the first step is heated to a predetermined temperature by the auxiliary heating device 20, the second step is performed by the sulfur compound adding means 6 and the second reactor 8, and the treated water of the second step is subjected to heat exchange. Heat energy is supplied to the treated water of the first step through the vessel 18 and the temperature of the treated water of the second step is lowered.

Here, as the heating means of the auxiliary heating device 22, a means using an electric heater as described above,
Known means such as means using steam heating can be applied. Although not particularly shown, the auxiliary heating device 22 may be installed in the second reaction device 8.

The reaction of the above formulas (2) and (3) in the present invention with the addition of the structure described above proceeds regardless of the pH of the water to be treated. The pH of the water is preferably 2 to 12. Also,
If necessary, a pH adjusting agent injection device for adding an acid or alkali solution to the water to be treated may be provided in order to adjust the pH of the water to be treated.

The present invention with the added configuration is preferably used together with the invention with the aforementioned configuration added. FIG. 6 shows an example of a process chart for carrying out the present invention with the addition of the above configurations. In FIG. 6, 18 is a heat exchanger, 10
Denotes a hydrogen peroxide adding means, 4 denotes a first reactor, 20 denotes an auxiliary heating device, 6 denotes a sulfur compound adding means, and 8 denotes a second reactor. The heat exchanger 18 performs heat exchange between the water to be treated and the treated water in the second step, and the auxiliary heating device 20 heats the treated water in the first step.

As shown in this process diagram, the water to be treated is passed through the heat exchanger 18 to recover heat energy from the treated water in the second step in a heated state, thereby heating the water to be treated.
Next, the first step is performed by the hydrogen peroxide adding means 10 and the first reactor 4. After the treated water of the first step is heated to a predetermined temperature by the auxiliary heating device 20, the second step is performed by the sulfur compound adding means 6 and the second reactor 8, and the treated water of the second step is removed by the heat exchanger 18. To supply heat energy to the water to be treated and reduce the temperature of the water to be treated in the second step.

In the embodiment shown in FIGS. 5 and 6, the treated water of the second step, which has passed through the heat exchanger 18 and whose temperature has decreased, is further passed through a deionization apparatus to remove pure water. It may be obtained.

The point will be described. When the oxidizable inorganic substance is contained in the treated water of the first step, the present inventors remove or decompose the oxidizable inorganic substance contained in the treated water in advance, and then prepare the sulfur-containing peroxide group in the treated water of the first step. It has been found that the amount of the sulfur compound containing a peroxide group in the second step can be further reduced by adding the compound.

Here, the oxidizable inorganic substance refers to a sulfur compound containing a peroxide group or an inorganic substance which can be oxidized by free radicals generated when the compound is irradiated with ultraviolet rays. When the oxidizable inorganic substance is contained in the treated water of the first step, the sulfur compound containing a peroxide group is added to the amount necessary for oxidatively decomposing the organic matter contained in the treated water of the first step, and is added to the sulfur compound. An extra amount is consumed to oxidize the oxidizable inorganic substance. Therefore, after removing the oxidizable inorganic substance from the treated water in the first step in advance, the sulfur compound containing a peroxide group is added, whereby the second
The effect is obtained that the amount of the sulfur compound containing a peroxide group used in the process can be reduced.

The oxidizable inorganic substance includes, for example, ionic species such as sulfite ion and hypochlorite ion. These are usually deionized, for example, adsorbed by ion exchange resin, or reverse osmosis. It can be removed by applying a separation treatment using a membrane or the like.

Hydrogen peroxide, ozone and the like are also sulfur compounds containing a peroxide group or inorganic substances which can be oxidized by free radicals generated when the compound is irradiated with ultraviolet rays. It is preferable to remove or decompose in advance. hydrogen peroxide,
Known methods can be used for removing or decomposing ozone or the like. For example, a removal method using decomposition or adsorption treatment using activated carbon or the like, a decomposition treatment method using a catalyst, or the like can be applied. In the case of ozone, it can also be removed by aeration using air or nitrogen gas.

In the present invention, since hydrogen peroxide and / or ozone are used in the first step, hydrogen peroxide and / or ozone may remain in the treated water in the first step.
Therefore, after removing or decomposing these oxidizable inorganic substances contained in the treated water of the first step in advance, adding a sulfur compound containing a peroxide group to the treated water of the first step requires the peroxide in the second step. This is particularly effective in reducing the amount of the sulfur compound containing a group.

In addition, the present inventors carried out a treatment for removing a sulfur compound containing a peroxide group present in the treated water in the second step between the second step and the third step, whereby the third step was carried out. It has been found that the deterioration of the deionization equipment used due to oxidation is significantly reduced.

In the second step, the sulfur compound containing the added peroxide group is not always consumed, and the compound may remain in the treated water in the second step. After removing the remaining sulfur compound containing a peroxide group by removing the sulfur compound containing a peroxide group,
By passing water through the deionizer, an effect of preventing a sulfur compound containing a peroxide group from adversely affecting the deionizer can be obtained.

As the apparatus used for the removal treatment of the sulfur compound containing a peroxide group, for example, a catalyst packed tower or an activated carbon tower filled with a suitable catalyst, or an apparatus using both of them can be used. As the catalyst to be packed in the catalyst packed tower, any catalyst can be used as long as it decomposes a sulfur compound containing a peroxide group, and for example, a platinum-based, zeolite-based, alumina-based catalyst or the like can be used. . As the activated carbon to be filled in the activated carbon tower, any activated carbon can be used as long as the object can be achieved. For example, coconut-based activated carbon, coal-based activated carbon and the like can be used. Further, as an apparatus used for the removal treatment of a sulfur compound containing a peroxide group, a device that decomposes a sulfur compound containing a peroxide group by ultraviolet irradiation may be used.

After removing or decomposing the oxidizable inorganic substances contained in the treated water of the first step in advance, the above-mentioned constitution of adding a sulfur compound containing a peroxide group to the treated water of the first step is added. FIG. 7 shows an example of a process chart in which between the step and the third step, a treatment for removing a sulfur compound containing a peroxide group present in the treated water in the second step is performed.

The system shown in FIG. 7 is different from the system shown in FIG. 2 in that the oxidizable inorganic substance contained in the treated water in the first step is removed between the first reactor 4 and the installation position of the sulfur compound adding means 6. Or decomposable oxidizable inorganic material treatment device 22
And a sulfur compound removing device 24 for removing a sulfur compound containing a peroxide group present in the treated water in the second step is provided between the second reactor 8 and the deionizing device 12. is there. Therefore, in FIG. 7, the same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 7, there are two configurations, the above configuration and a configuration in which a sulfur compound containing a peroxide group present in the treated water in the second step is removed between the second step and the third step. Although an example in which both are adopted is shown, an apparatus employing only one of the two configurations may be manufactured by removing one of the oxidizable inorganic substance treating device 22 and the sulfur compound removing device 24. Needless to say.

As described above, the organic matter removing method of the present invention comprises:
Applicable in various fields such as treatment of various wastewaters, production of ultrapure water for the electronics industry such as water for semiconductor production and water for liquid crystal display production, water production for pharmaceuticals, and condensate water recovery for thermal power plants and nuclear power plants. Although it can be used, it can be suitably used particularly for the production of ultrapure water for the electronic industry.

The production process of ultrapure water is divided into several processes as described below, and the present invention can be applied to a system including an oxidation treatment of organic substances in the process. In other words, the ultrapure water production process consists of a primary pure water system that removes most of the impurities contained in the raw water, and a small amount of impurities contained in the primary pure water that is completely removed to an impurity concentration close to theoretical pure water. The system includes a subsystem for producing ultrapure water with improved water quality, and a wastewater recovery system for collecting and reusing cleaning wastewater after using the produced ultrapure water as semiconductor cleaning water or the like.

In the primary pure water system, the raw water is passed through a coagulation filtration device, a reverse osmosis membrane device, a degassing device, an ion exchange device equipped with a regenerating facility, etc., and the inorganic and organic substances contained in the raw water are removed.
Further, most of the fine particles and the like are removed. In the subsystem, the primary pure water obtained in the primary pure water system is passed through an ultraviolet oxidizer, a cartridge type ion exchange device without regeneration equipment, an ultrafiltration device, etc., and inorganic and organic substances in the primary pure water, The concentration of fine particles and the like is reduced to the utmost limit to obtain the desired ultrapure water. In the wastewater recovery system, the washing wastewater is passed through an activated carbon filtration device, an ultraviolet oxidation device, and an ion exchange device to remove inorganic and organic substances in the wastewater.

The present invention can be applied to the organic substance removal processing performed in the above subsystem and wastewater recovery system. As described above, when the present invention is applied to ultrapure water production, usually, the primary pure water treated in the primary pure water system, and the primary pure water mixed with the wastewater recovered treated water treated in the wastewater recovery system. The waste water or the collected waste water will be used as the water to be treated in the present invention, but is not limited thereto.

[0081]

The following examples, comparative examples and experimental examples are given below.
The present invention is specifically described. Example 1 Raw water containing isopropyl alcohol as an organic substance (TOC (total organic carbon) concentration: 6 pp) was placed in a glass reaction vessel.
m) was added thereto, and the pH of the raw water was adjusted to 11 using sodium hydroxide. The reaction was performed for 10 minutes while dissolving ozone generated by the ozone generator in the raw water using a balloon. (First step). The water temperature during the reaction was 24 ° C., and the amount of dissolved ozone was 3 g. Table 1 shows the TOC concentration in the water at the end of the first step.

Next, the dissolution of ozone was stopped, and nitrogen aeration was performed for 5 minutes to release dissolved ozone into the gaseous phase.
150 mg of sodium peroxydisulfate as a sulfur compound containing a peroxide group was dissolved in water. Further, a low-pressure mercury lamp (SGL manufactured by Chiyoda Kohan Co., Ltd.)
-500) One was placed so as to be located in water, and ultraviolet irradiation was performed for 15 minutes (second step). Table 1 shows the TOC concentration in the water at the end of the second step.

[0083]

[Table 1]

Example 2 10 liters of raw water (TOC concentration: 6 ppm) containing isopropyl alcohol as an organic substance was placed in a glass reaction vessel, and hydrogen peroxide was added thereto to a concentration of 20 ppm. The reaction was performed for 30 minutes while dissolving the generated ozone in the raw water using a balloon (first step). The water temperature during the reaction was 24 ° C., and the ozone concentration in the raw water was about 4 ppm on average. Table 2 shows the TOC concentration in the water at the end of the first step.

Next, the dissolution of ozone was stopped, and nitrogen aeration was performed for 5 minutes to release dissolved ozone into the gaseous phase.
72 mg of sodium peroxydisulfate as a sulfur compound containing a peroxide group was dissolved in water. Further, one low-pressure mercury lamp (same as above) was set in the reaction vessel so as to be located in water, and ultraviolet irradiation was performed for 15 minutes (second step). Table 2 shows the TOC concentration in the water at the end of the second step.

[0086]

[Table 2]

Example 3 10 liters of raw water containing 10 ppm of TOC concentration of dimethyl sulfoxide as an organic substance was placed in a glass reaction vessel, and hydrogen peroxide was added thereto to a concentration of 50 ppm. The reaction was performed for 30 minutes while dissolving the generated ozone in the raw water using a balloon (first step). The water temperature during the reaction is 24
The average ozone concentration in the raw water at ℃ was about 4 ppm. Table 3 shows the TOC concentration in water at the end of the first step.

Next, the dissolution of ozone was stopped, and nitrogen aeration was performed for 5 minutes to release dissolved ozone into the gaseous phase.
Sodium peroxydisulfate as a sulfur compound containing a peroxide group was dissolved in water to a concentration of about 500 ppm. Further, one low-pressure mercury lamp (same as above) was set in the reaction vessel so as to be located in water, and ultraviolet irradiation was performed for 15 minutes (second step). Table 3 shows the TOC concentration in the water at the end of the second step.

[0089]

[Table 3]

Example 4 An experiment was conducted using the system shown in FIG. In FIG. 8, 26 is a TOC source adding means for adding a TOC source to the water to be treated, 10 is a hydrogen peroxide adding means, 4 is a first reactor,
Reference numeral 22 denotes an oxidizable inorganic substance treatment device, 6 denotes a sulfur compound adding means, 8 denotes a second reaction device, and 12 denotes a deionization treatment device.

The first reactor 4 has a capacity 5 as a reaction vessel.
The 0 liter stainless steel tank, and the second reactor 8 is provided with a 30 liter stainless steel tank as a reaction vessel. First reactor 4
In the second reactor 8, two low-pressure mercury lamps (the same as above) were installed in the center of the tank so as to be located in the water, the inlet for the water to be treated was provided at the lower part of the tank, and the outlet for the treated water was provided at the upper part of the tank. .

As the oxidizable inorganic substance treating device 22, an activated carbon column was used. As the deionization processing device 12,
An ion exchange resin column packed with a strongly acidic cation exchange resin in the H form and a strongly basic anion exchange resin in the OH form at a ratio of 1: 2 by volume was used.

As a TOC source, isopropyl alcohol and tetramethylammonium hydroxide were used.
A solution dissolved so as to have a C concentration of 1 to 1 was used. As the water to be treated, pure water was continuously passed through the line 28 at a flow rate of 100 liter / hour.

The experiment was performed in the following steps. (A) The TOC source was added to the water to be treated flowing through the line 28 from the TOC source adding means 26 so that the TOC concentration in the water to be treated was 6 ppm. (B) Hydrogen peroxide was added to the water to be treated to which the TOC source had been added from the hydrogen peroxide adding means 10 so that the concentration thereof was 60 ppm. Further, in the first reactor 4,
The water to be treated was irradiated with ultraviolet rays to decompose and remove organic substances (first step). The temperature of the water to be treated in the first reactor 4 was 24 ° C. (C) In the oxidizable inorganic substance treating apparatus 22, hydrogen peroxide remaining in the treated water in the first step was removed. (D) To the treated water in the first step, sodium peroxydisulfate was added by the sulfur compound adding means 6 at a concentration of 100 pp.
m. Further, in the second reactor 8, the water to be treated was irradiated with ultraviolet rays to decompose and remove organic substances (second step). (E) In the deionization treatment device 12, sulfate ions remaining in the treated water in the second step were removed to obtain highly pure treated water (pure water) (third step).

The TOC concentration in the water flowing out of the first reactor 4, the TOC concentration and the sulfate ion concentration in the water flowing out of the second reactor 8, and the sulfate ion concentration and the treated water specific resistance flowing out of the deionizer. Was measured. Table 4 shows the results.

[0096]

[Table 4]

COMPARATIVE EXAMPLE 1 An apparatus for performing the first step and the third step from the apparatus used in Example 4, that is, a hydrogen peroxide adding means 10, a first reaction apparatus 4, an oxidizable inorganic substance processing apparatus 22, a deionization apparatus The processing apparatus 12 was removed, and processing was performed only in the second step. The flow rate of the water to be treated and the composition and concentration of the TOC component were the same as in Example 4. Experiments were performed for each case where the amount of sodium peroxydisulfate added was 100 ppm, 200 ppm, or 300 ppm, and the TOC concentration and the sulfate ion concentration in the water at the time of flowing out of the second reactor 8 were measured. Table 5 shows the results. From Table 5, it is clear that it is necessary to add 300 ppm of sodium peroxydisulfate to reduce the TOC concentration to the same level as in Example 4.

[0098]

[Table 5]

Comparative Example 2 An apparatus for performing the second step and the third step from the apparatus used in Example 4, that is, an oxidizable inorganic substance treatment apparatus 22, a sulfur compound adding means 6, a second reaction apparatus 8, and a deionization treatment The apparatus 12 was removed, and processing was performed only in the first step. The flow rate of the water to be treated and the composition and concentration of the TOC component were determined in Example 4.
And the same. The amount of hydrogen peroxide added was 30 ppm, 60 ppm.
Experiments were performed for each of the cases of ppm, 100 ppm, 200 ppm, and 300 ppm, and the TOC concentration in the water at the time of flowing out of the first reactor 4 was measured. Table 6 shows the results.

[0100]

[Table 6]

According to Table 6, the amount of hydrogen peroxide added was 60 ppm.
As described above, the TOC concentration becomes almost constant regardless of the amount of hydrogen peroxide added. Therefore, the TOC component used in this experiment, which contains tetramethylammonium hydroxide in addition to isopropyl alcohol as an organic substance, can be decomposed by a conventional method, that is, a method in which only water to be treated to which hydrogen peroxide is added is irradiated with ultraviolet rays. Obviously it is difficult.

Compared with Examples 1 to 4 and Comparative Examples 1 and 2, in order to significantly reduce organic substances, the method of the present invention shown in Examples 1 to 4 or the sodium peroxydisulfate shown in Comparative Example 1 was used. It turns out that the method is preferred. In order to obtain pure water with significantly reduced organic matter,
As shown in Example 4, it is understood that the third step is preferably performed after the second step.

However, in the method shown in Comparative Example 1, TO
To reduce the C concentration to the same level as in Examples 1 to 4,
It is necessary to use a large amount of sodium peroxydisulfate (comparing Example 4 and Comparative Example 1 three times the present invention),
The amount of sodium peroxydisulfate used increases.

Therefore, in the method shown in Comparative Example 1, the reaction vessel for removing organic substances is easily corroded. The chemical cost of the sulfur compound containing a peroxide group and the processing cost of sulfate ion as a by-product increase, and the processing cost increases.
Furthermore, since the amount of by-products of sulfate ions increases (compared with Example 4 and Comparative Example 1 three times the present invention), pure water in which impurity ions such as sulfate ions are significantly reduced together with organic substances is obtained. However, the load of the deionization process increases, and equipment for the deionization process increases. In contrast, it is clear that the method of the present invention does not cause such disadvantages.

Example 5 In the apparatus used in Example 4, an electric heater was installed in the first reactor 4 and an apparatus for performing the third step, that is, an apparatus in which the deionization apparatus 12 was removed was manufactured. An experiment was performed using the apparatus. As the TOC source, a solution in which isopropyl alcohol and tetramethylammonium hydroxide were dissolved so that the TOC concentration became 1: 1 was used. As the water to be treated, pure water was continuously supplied to the line 28 at a flow rate of 200 liter / hour.

The experiment was performed in the following steps. (A) The TOC source was added to the water to be treated flowing through the line 28 from the TOC source adding means 26 so that the TOC concentration in the water to be treated was 6 ppm. (B) Hydrogen peroxide was added to the water to be treated to which the TOC source had been added from the hydrogen peroxide adding means 10 so that the concentration thereof was 60 ppm. Further, the water to be treated is heated by the electric heater so that the temperature of the water to be treated in the first reactor 4 becomes 25 ° C., 45 ° C., 60 ° C., and 70 ° C., and the water to be treated is irradiated with ultraviolet rays. Then, organic substances were decomposed and removed (first step). (C) In the oxidizable inorganic substance treating apparatus 22, hydrogen peroxide remaining in the treated water in the first step was removed. (D) To the treated water in the first step, sodium peroxydisulfate was added by the sulfur compound adding means 6 at a concentration of 100 pp.
m. Further, in the second reactor 8, the water to be treated was irradiated with ultraviolet rays to decompose and remove organic substances (second step).

The water temperature in the first reactor 4 and the second reactor 8 and the TOC concentration in the water at the time of flowing out of the second reactor 8 were measured. Table 7 shows the results. As shown in Table 7, the organic matter is decomposed and removed while the water to be treated is heated, so that TO
It is clear that the C concentration can be efficiently reduced.

[0108]

[Table 7]

Experimental Example 1 An isopropyl alcohol (TO) as an organic substance was placed in a stainless steel water tank equipped with a heater and a stirrer.
C concentration 6 ppm) and 360 ppm of sodium peroxydisulfate as a sulfur compound containing a peroxide group
50 liters of raw water containing water at a concentration of 45 ° C,
Maintain at 60 ° C and 75 ° C, respectively.
The reaction was allowed to run for minutes. The TOC concentration in the treated water after the completion of the stirring was measured. Table 8 shows the results. This experimental example corresponds to the second step of the present invention.

[0110]

[Table 8]

As shown in Table 8, in the second step of the present invention,
The higher the temperature of the water to be treated, the higher the efficiency of decomposing organic substances. However, it was found that the decomposition of the organic substances proceeded more rapidly when the water to be treated was heated to 70 ° C. or more. Therefore, in the second step, the treated water of the first step to which the sulfur compound containing a peroxide group is added is heated to 70 ° C. or more, thereby improving the efficiency of removing organic substances in the second step and significantly reducing the TOC concentration. Obviously you can.

Experimental Example 2 The apparatus used in Example 4 was replaced with the oxidizable inorganic substance treating apparatus 22.
And removing the deionization apparatus 12, the step (c)
An experiment was performed in the same manner as in Example 4 except that (e) and (e) were not performed. In this case, 20 ppm of hydrogen peroxide remained in the treated water in the step (b). This hydrogen peroxide concentration was measured by a titration method using potassium permanganate. The TOC concentration in the water at the time of flowing out of the first reactor 4 and the second reactor 8 was measured. Table 9 shows the results.

[0113]

[Table 9]

According to Table 9, if the treated water in the first step contains hydrogen peroxide, the sulfur compound containing a peroxide group is also consumed to oxidize the hydrogen peroxide.
It can be seen that the efficiency of removing organic substances in the process decreases. Therefore, performing the second step after removing or decomposing the oxidizable inorganic substance contained in the treated water in the first step is particularly effective in reducing the amount of the sulfur compound containing a peroxide group in the second step. It is clear that

[0115]

As described in detail above, according to the present invention, the amount of organic substances contained in the water to be treated can be significantly reduced. Further, it is possible to obtain pure water in which the concentration of organic substances is significantly reduced. Moreover, according to the present invention,
Reduce the amount of sulfur compounds containing peroxide groups, reduce the cost of organic substance removal treatment, suppress corrosion of the reaction vessel for organic substance removal, and reduce the load on the treatment step of sulfate ion as a by-product and It is possible to reduce the size of the equipment.

[Brief description of the drawings]

FIG. 1 is a process diagram showing an example of a process for carrying out the present invention.

FIG. 2 is a process chart showing an example of a process for carrying out the present invention.

FIG. 3 is a process chart showing an example of a processing step for carrying out the present invention.

FIG. 4 is a process chart showing an example of a process for carrying out the present invention.

FIG. 5 is a process chart showing an example of a process for carrying out the present invention.

FIG. 6 is a process chart showing an example of a process for carrying out the present invention.

FIG. 7 is a process chart showing an example of a process for carrying out the present invention.

FIG. 8 is a process chart showing the processing steps of Example 4.

[Description of Signs] 2 Hydrogen peroxide and / or ozone addition means 4 First reactor 6 Sulfur compound addition means 8 Second reactor 10 Hydrogen peroxide addition means 12 Deionization treatment device 14 Ozone dissolution device 16 Ozone generation device 18 Heat exchanger 20 Auxiliary heating device 22 Oxidizable inorganic material treatment device 24 Sulfur compound removal device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 1/42 C02F 1/42 D 1/78 1/78

Claims (8)

[Claims] A first step of decomposing and removing organic substances contained in the water to be treated by adding hydrogen peroxide and / or ozone to the water to be treated to decompose and remove the organic substances;
A second step of decomposing and removing organic substances by adding a sulfur compound containing a peroxide group to the treated water of the step. 2. The method for removing organic substances in water according to claim 1, further comprising a third step of deionizing the treated water in the second step. 3. The method according to claim 1, wherein, in the first step, the water to be treated to which hydrogen peroxide and / or ozone has been added is irradiated with ultraviolet rays to decompose and remove organic substances. 4. The method according to claim 1, wherein in the first step, the organic matter is decomposed and removed while heating the water to be treated.
The method for removing organic substances in water according to the above item. 5. The method according to claim 1, wherein in the second step, the treated water in the first step to which a sulfur compound containing a peroxide group is added is irradiated with ultraviolet rays to decompose and remove organic substances.
The method for removing organic substances in water according to the above item. 6. The method according to claim 5, wherein in the second step, the treated water in the first step to which the sulfur compound containing a peroxide group is added is irradiated with ultraviolet rays while heating the treated water to decompose and remove organic substances. How to remove organic matter in water. 7. The process according to claim 1, wherein in the second step, the treated water in the first step to which the sulfur compound containing a peroxide group is added is heated to 70 ° C. or more to decompose and remove organic substances. Of removing organic matter in water. 8. The second step is performed after removing or decomposing oxidizable inorganic substances contained in the treated water in the first step.
The method for removing organic substances in water according to any one of claims 7 to 7.