JP2005237778A - Method for treating hardly decomposable organic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating hardly decomposable organic compounds, which enables contamination containing the hardly decomposable organic compounds such as dioxins to be detoxified by decomposition treatment easily at a low cost no matter what properties or concentration of the hardly decomposable organic compounds, when they are detoxified by an oxidative degradation treatment using a persulfate. <P>SOLUTION: Under the presence of a metal oxide, the contamination containing hardly decomposable organic compounds are treated to be detoxified by adding the persulfate for oxidative decomposition reaction. When the contamination is a liquid contaminated water, a separation treatment such as sedimentation or membrane separation may be performed as pretreatment to make it concentrate, or adsorption or flocculation treatment may be performed before the separation treatment by adding adsorbent or a flocculating agent to the contaminated water. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a treatment method for detoxifying and removing degradable organic compounds such as dioxins by oxidative decomposition.

  In Japan, the Act on Special Measures against Dioxins was enacted in 1999, and the emission standards for dioxins in soil, wastewater, and air are regulated. On the other hand, due to the generation of industrial waste and general waste, incinerators, surrounding soil, low-quality soil, and wastewater, industrial wastewater, soil leachate, etc. in incinerator demolition work have high concentrations that greatly exceed discharge standards. In some cases, dioxins may be contained, and a reduction treatment technique is strongly desired.

  In addition, endocrine disrupting substances such as bisphenol other than dioxins (so-called environmental hormones, also called endocrine disrupting chemical substances) and various organochlorine compounds typified by trichloroethane are also non-degradable substances, and their emission standards are On the other hand, as with the dioxins described above, development of a reduction treatment technique or removal technique is strongly desired.

  As a means for detoxifying such a hardly decomposable organic compound, for example, as a method for removing dioxins, ozone, photolysis, chemical decomposition by hydrogen peroxide, decomposition by microorganisms, adsorption on the dioxins Means such as separation and removal using an agent and a flocculant are known. On the other hand, in this point, because the operation is simple, an oxidizing agent is added to dioxins to oxidize and decompose to make them harmless, and as an oxidizing agent to oxidize and decompose dioxins For example, a technique using a persulfate is provided (for example, Patent Document 1 and Patent Document 2).

JP 2003-93999 A JP 2003-285043 A

  However, when the persulfate is added to the hardly decomposable organic compound and the compound is oxidatively decomposed as disclosed in Patent Document 1 and Patent Document 2, the hardly decomposable organic compound is used. Since the decomposition rate of the compound was poor, it was extremely difficult to cope with a high concentration. On the other hand, as a means for treating such a high concentration of hardly decomposable organic compound, a metal salt such as ruthenium salt may be added to persulfate, but such a metal salt is very expensive. In terms of cost, it was not practical.

  Accordingly, an object of the present invention is to characterize a hardly decomposable organic compound in order to detoxify a pollutant containing a hardly decomposable organic compound such as dioxins by peroxidation using persulfate. Another object of the present invention is to provide a method for treating a hardly decomposable organic compound that can be easily detoxified by decomposing at low cost regardless of the concentration.

  In order to achieve the above object, the method for treating a hardly decomposable organic compound of the present invention is to decompose a pollutant containing a hardly decomposable organic compound by adding a persulfate in the presence of a metal oxide. It is characterized by processing.

  The method for treating a hardly decomposable organic compound according to the present invention is to oxidize a liquid or solid contaminant containing a hardly decomposable organic compound such as dioxins by adding a persulfate in the presence of a metal oxide. Since the persulfate added to the pollutant acts as an oxidant and an oxidation reaction occurs, and the metal oxide serves as a catalyst for the oxidation reaction. The compound is efficiently oxidized and decomposed, and the compound is suitably detoxified.

According to the present invention, a contaminant containing a hardly decomposable organic compound is subjected to an oxidative decomposition treatment using the persulfate in the presence of a metal oxide. It is not limited to the properties and concentration of the above, and it is possible to efficiently and easily detoxify the persistent organic compounds such as dioxins.
In addition, since persulfate used as an oxidizing agent is inexpensive, it is possible to detoxify a hardly decomposable organic compound at a low cost.

  On the other hand, the method for treating a hardly decomposable organic compound is such that when the contaminant containing the hardly decomposable organic compound to be treated is liquid contaminated water, A separation treatment may be performed to obtain a concentrate, and the concentrate may be decomposed by adding a persulfate in the presence of a metal oxide.

As described above, the contaminated water containing the hardly-decomposable organic compound is subjected to a separation treatment in advance to be in a fluid or solid concentrate state, and then the presence of metal oxides in the concentrate. If a persulfate is added under the oxidative decomposition treatment, a certain amount of the hardly decomposable organic compound in the contaminated water will be separated in advance. The detoxification process by decomposition is performed more efficiently.
Here, as an example of the separation treatment, a membrane separation membrane such as a reverse osmosis membrane (RO membrane), a nanofilter membrane (NF membrane), an ultrafiltration membrane (UF membrane), a microfiltration membrane (MF membrane) or the like was used. Examples include membrane separation treatment, sedimentation separation, and centrifugal separation.

And in this processing method of the hardly decomposable organic compound of the present invention, it is preferable to include a step of adding an adsorbent and / or a flocculant to the contaminated water in carrying out the separation process. .
Thus, by adding an adsorbent and a flocculant before the separation treatment for contaminated water,
The separation of the hardly decomposable organic compound in the contaminated water in the separation treatment is further promoted.

In the method for treating a hardly decomposable organic compound of the present invention, the adsorbent is one selected from the group consisting of titanium oxide, zeolite, acidic clay, activated clay, diatomaceous earth, metal oxide, metal powder and activated carbon. Or it is preferable that they are 2 or more types.
According to this invention, since the specific thing is selected as the said adsorbent, removal of the hard-to-decompose organic compound by pre-processing will be performed still more efficiently.

In the method for treating a hardly decomposable organic compound of the present invention, the weight ratio of the metal oxide to the persulfate is preferably persulfate: metal oxide = 1: 0.0001 to 1: 1.
According to the present invention, since the weight ratio of the metal oxide and the persulfate used for the oxidative decomposition of the hardly decomposable organic compound is within a specific range, the metal oxide is efficiently converted into the persulfate. By acting as an accelerator, the oxidative decomposition treatment of the hardly decomposable organic compound is more reliably performed.

In the method for treating a hardly decomposable organic compound of the present invention, the metal oxide is one or more selected from the group consisting of molybdenum oxide, manganese oxide, titanium oxide, magnesium oxide, iron oxide and cobalt oxide. Preferably there is.
According to this invention. Since a specific metal oxide is selected, the oxidative decomposition treatment is further promoted.

  The method for treating a hardly decomposable organic compound of the present invention (hereinafter sometimes referred to as “the method of the present invention”) is a method of treating a metal oxide with respect to a liquid or solid contaminant containing a hardly decomposable organic compound. Examples of persistent substances that can be detoxified by the method of the present invention are added with persulfate in the presence of dioxins that are harmful pollutants in soil and sludge. And other endocrine disrupting substances and carcinogenic substances.

Here, examples of dioxins include halogenated dibenzodioxins, halogenated dibenzofurans, PCBs (particularly, coplanar PCBs substituted with a chlorine atom in addition to the ortho position) and the like.
Examples of halogenated dibenzodioxins include 2,3,7,8-tetrachlorodibenzo-P-dioxin, 1,2,3,7,8-pentachlorodibenzo-P-dioxin,
1,2,3,4,7,8-hexachlorodibenzo-P-dioxin, 1,2,3,4,6,7,8-heptachlorodibenzo-P-dioxin, 1,2,3,4,6 7,8,9-octachlorodibenzo-P-dioxin and the like.

  Examples of halogenated dibenzofurans include 2,3,7,8-tetrachlorodibenzofuran, 1,2,3,7,8-pentachlorodibenzofuran, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzofuran, 1,2,3,4,6,7,8,9-octachlorodibenzofuran and the like.

  Examples of PCBs (particularly coplanar PCBs substituted with a chlorine atom other than the ortho position) include 3,3 ′, 4,4 ′, 5-tetrachlorobiphenyl, 3,3 ′, 4,4 ′, 5 -Pentachlorobiphenyl, 3,3 ', 4,4', 5,5'-hexachlorobiphenyl and the like.

  Examples of endocrine disrupting substances and carcinogenic substances other than dioxins include alkylphenols such as t-butylphenol, nonylphenol and octylphenol, halogenated phenols such as tetrachlorophenol and pentachlorophenol, and 2,2-bis (4 -Hydroxyphenyl) propane (bisphenol A), 1-bis) 4-hydroxyphenyl) cyclohexane and other bisphenols, benzopyrene, chrysene, benzoanthracene, benzofluoranthene, picene and other polycyclic aromatic hydrocarbons, dibutyl phthalate, Examples thereof include phthalic acid esters such as butylbenzyl phthalate and di-2-ethylhexyl phthalate.

  In addition to the dioxins and PCBs described above, refractory organic halogen compounds such as dichloropropane, trichloroethane, trichloroethylene, tetrachloroethylene, and dichloroethylene can also be removed by oxidative decomposition using the method of the present invention.

The method of the present invention uses a persulfate as an oxidizing agent as a means for detoxifying a hardly decomposable organic compound, and the persulfate used in the present invention includes, for example, sodium persulfate. (Sodium peroxodisulfate), potassium persulfate (potassium peroxodisulfate), and ammonium sulfate (ammonium peroxodisulfate) can be mentioned, and these can be used alone or in combination of two or more.
In addition, the shape of persulfate may be various shapes such as granular, powder, and crystalline, and may be applied as a persulfate aqueous solution in which persulfate is dissolved in water.

  The amount of persulfate added to the pollutant may be appropriately determined according to the type and concentration of the persistent organic compound in the pollutant, and the type and concentration of the coexisting substance, but when the pollutant is in the form of a solution Is preferably 100 to 100,000 ppm, particularly preferably 1000 to 50,000 ppm. On the other hand, when the contaminant is a solid, the content is preferably 0.01 to 100% by mass, and particularly preferably 0.1 to 20% by mass with respect to the contaminant.

  In the method of the present invention, the persulfate described above is added to the oxidative decomposition treatment of the hardly decomposable organic compound in the presence of the metal oxide. Examples of the metal oxide used in the present invention include molybdenum oxide, manganese oxide, titanium oxide, magnesium oxide, iron oxide (such as ferric oxide), cobalt oxide, and the like, and such metal oxide is selected. As a result, the oxidative decomposition reaction is further promoted. These metal oxides may be used individually by 1 type, or can be used in combination of 2 or more type. In the method of the present invention, it is particularly preferable to use molybdenum oxide or manganese oxide from the viewpoint of promoting decomposition.

  In the method of the present invention, a persulfate and a metal oxide are added to the hardly decomposable organic compound as described above to perform an oxidative decomposition treatment. The weight ratio of persulfate to metal oxide is preferably persulfate: metal oxide = 1: 0.0001 to 1: 1, particularly 1: 0.01 to 1: 1. preferable. If the ratio of the metal oxide to the persulfate is less than 0.0001 as the weight ratio, the amount of the metal oxide may be too small to promote the oxidative decomposition reaction. On the other hand, if the ratio of the metal oxide is larger than 1, the oxidative decomposition reaction may be promoted, but as a result, the cost is increased, which is not preferable.

In the present invention, an appropriate amount of persulfate and a metal oxide are added to a contaminant containing a hardly decomposable organic compound such as dioxins, and water is added if necessary, for example, at about 50 to 100 ° C. It can be simply carried out by heating to oxidatively decompose the hardly decomposable organic compound in the pollutant.
Then, after such oxidative decomposition, it is confirmed that the content of the hardly decomposable organic compound in the concentrate is equal to or less than the reference value, and discarded in the same manner as normal industrial waste.

In the case where the pollutant containing the hardly decomposable organic compound is liquid polluted water, it is subjected to separation treatment such as sedimentation separation and / or membrane separation treatment in advance to obtain a fluid or solid concentrate. , Adding persulfate and metal oxide, adding water as necessary, and then heating to about 50-100 ° C. to oxidatively decompose the hardly decomposable organic compound in the pollutant. Is preferred.
Moreover, you may make it include the process of adding an adsorption agent and / or a coagulant | flocculant with respect to the said contaminated water, and performing an adsorption process or a coagulation process before the said separation process.

  In this way, if a certain amount of the hardly decomposable organic compound in the contaminated water is separated in advance, detoxification by oxidative decomposition using a persulfate and a metal oxide in the subsequent step becomes more efficient. Will be done. Furthermore, the separation of the hardly decomposable organic compound in the contaminated water in the separation treatment can be further promoted by adding an adsorbent or a flocculant before the separation treatment for the contaminated water.

Further, the adsorption process, the aggregation travel, and the separation process (hereinafter, these may be collectively referred to as “pretreatment”) may be performed as follows, for example.
[Adsorption treatment]
The adsorption treatment is preferably performed using various adsorbents such as inorganic adsorbents. Examples of the inorganic adsorbent include inorganic compounds having adsorption performance, such as titanium oxide, zeolite, acid clay, activated clay, diatomaceous earth, iron oxide and other metal compounds, iron and other metal powders, activated carbon and the like. One kind can be used alone, or two or more kinds can be used in combination.

The amount of adsorbent added may be appropriately determined in consideration of the type of adsorbent, the adsorption performance, the type and amount of contaminants to be treated, the cost, etc. In general, it may be 1 to 10000 ppm. It is preferable to set it as 1000 ppm.
In addition, the longer the contact time of the adsorbent with the contaminant, the better the adsorption efficiency, but it may be appropriately determined in consideration of the size of the treatment tank, for example, about 1 to 2 hours. Is preferred.

[Aggregation treatment]
The aggregating treatment is preferably performed using an aggregating agent. As the flocculant, either an inorganic flocculant or an organic flocculant can be used alone or in combination.
Examples of the inorganic flocculant include aluminum sulfate, ferric chloride, ferrous sulfate, polyaluminum chloride, mosnite, zeolite and the like.
Examples of the organic flocculants include various anionic polymer flocculants such as sodium polyacrylate, a copolymer of sodium acrylate and acrylamide, and cationic polymer flocculants.

  The addition amount of the flocculant may be appropriately determined in consideration of the kind of the flocculant, the adsorption performance, the cost, etc., as in the case of the adsorbent, but generally may be 1 to 10000 ppm, and may be 10 to 1000 ppm. preferable.

[Separation process]
Separation treatment can be carried out by membrane separation using a membrane, centrifugation, etc., sedimentation separation, etc., but membrane separation is preferred in terms of separation performance, simplicity and the like.
The type of membrane used for membrane separation is not particularly limited as long as it has separation performance. For example, reverse osmosis membrane (RO membrane), nanofilter membrane (NF membrane), ultrafiltration membrane (UF) Membrane), microfiltration membrane (MF membrane) and the like are preferably used.

  Here, the constituent materials of the reverse osmosis membrane (RO membrane) include polyamide (including cross-linked polyamide and aromatic polyamide), aliphatic amine condensate, heterocyclic polymer, cellulose acetate, and polyethylene. Resin materials such as polyvinyl alcohol and polyether.

The membrane form of the reverse osmosis membrane is not particularly limited, and can be an asymmetric membrane or a composite membrane.
Further, as the membrane module, a flat membrane type, a hollow fiber type, a spiral type, a cylindrical type, a breez type, etc. can be appropriately employed.

  The constituent material of the nanofilter membrane (NF membrane) includes polyamide (including cross-linked polyamide and aromatic polyamide), aliphatic amine condensate, heterocyclic polymer, cellulose acetate, polyethylene, and polyvinyl alcohol. Examples thereof include resin materials such as those based on polyether and polyether.

There is no restriction | limiting in particular as a film | membrane form of a nano filter film | membrane, It can be set as an asymmetric membrane or a composite film similarly to the above-mentioned reverse osmosis membrane.
In addition, as the membrane module, a flat membrane type, a hollow fiber type, a spiral type, a cylindrical type, a pleated type and the like can be appropriately employed.

Examples of the constituent material for the ultrafiltration membrane (UF membrane) include cellulose acetate-based, polyacrylonitrile-based, polysulfine-based, and polyethersulfone-based resin materials.
In addition, as the membrane module, a flat membrane type, a hollow fiber type, a spiral type, a cylindrical type, a pleated type and the like can be appropriately employed.
And although there is no restriction | limiting in particular as a fraction molecular weight of an ultrafiltration membrane, What is necessary is just about 3000-150,000.

Examples of the constituent material of the microfiltration membrane (MF membrane) include cellulose ester-based, polyacrylonitrile-based, polysulfine-based, and polyethersulfone-based resin materials. Further, as the format, a flat membrane, a filter cartridge, a disposal cartridge, etc. may be selected as required.
The size of the pores (pores) of the microfiltration membrane may be determined as appropriate depending on, for example, the particle size of the adsorbent used in the adsorption treatment, but may be about 0.01 to 1 μm.

  Next, the procedure for performing oxidative decomposition treatment using persulfate in the presence of a metal oxide after pretreatment of the contaminated water of the hardly decomposable organic compound will be described with reference to FIG. .

As shown in FIG. 1, first, an adsorbent or an aggregating agent may be added to contaminated water containing a hardly-decomposable organic halogen compound such as dioxins to perform an adsorption treatment or an agglomeration treatment.
When the adsorbent or the flocculant is added, the effectiveness of the flocculant or the adsorbent can be enhanced by desirably using a stirring means.

  Next, separation processes such as sedimentation separation, membrane separation, and centrifugation are performed. The separation process separates the waste water into a separated liquid and a concentrate. Of these, the separated liquid is drained after confirming that the content of the hardly decomposable organic compound is below the reference value, and the remaining fluid state. Or, the solid concentrate is subjected to oxidative decomposition treatment using persulfate in the presence of a metal oxide.

  In the oxidative decomposition treatment with persulfate and metal oxide, an appropriate amount of persulfate is added in the presence of metal oxide, and water is added if necessary. Oxidative decomposition of a hardly decomposable halogen compound. After the decomposition, the content of the hardly decomposable organic compound in the concentrate can be confirmed to be equal to or lower than the reference value, and can be discarded in the same manner as ordinary industrial waste.

  According to the above-described present invention, a contaminant containing a hardly decomposable organic compound is subjected to separation treatment as a pretreatment if necessary, and then the persulfate is used in the presence of a metal oxide, and the compound is used. As a result, the persulfate added to the pollutant acts as an oxidant to cause an oxidation reaction, and a metal oxide serves as a catalyst to promote the oxidation reaction. Therefore, the organic compound can be detoxified efficiently and simply without being limited by the properties and concentration of the hardly decomposable organic compound. In addition, since persulfate is inexpensive, it is possible to detoxify a hardly decomposable organic compound at a low cost.

  And by the processing method of the hardly decomposable organic compound of the present invention, various pollutants, for example, industrial wastewater, soil leachate, washing wastewater generated in incinerator demolition work, smoke washing wastewater, ash washing wastewater, photographic wastewater In addition, it is possible to detoxify contaminants such as wastewater such as medical effluent, drainage and their concentrates, incinerated ash, contaminated soil, contaminated residues, sludge, and the like.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the content of an Example etc. at all.

[Example 1]
In accordance with the procedure shown in FIG. 1, the oxidative decomposition treatment of contaminated water containing dioxins which are hardly decomposable organic compounds was performed.
(1) Separation process:
To 1 L of contaminated water containing dioxins (dioxin concentration: 3000 pg-TEQ / L), 300 ppm of diatomaceous earth was added as an inorganic adsorbent and stirred for 1 hour, and then 100 ppm of mosnite was added as a flocculant. The mixture was sufficiently stirred for 2 hours for adsorption treatment and aggregation treatment, and then left overnight.

  The contaminated water left overnight was centrifuged by a conventional method to separate it into a separated solution and a concentrate. And while draining a separated liquid, the concentrate (400 mg as a dry matter) whose dioxins amount is 6700pg-TEQ / g was obtained.

(2) Oxidative decomposition treatment process:
0.04 g of powdered molybdenum oxide, which is a metal oxide, with respect to the obtained concentrate,
0.4 g of powdered sodium persulfate was added and the whole volume was adjusted to 40 ml with water, and then the temperature was set to 70 ° C. and heated in a stirring state for 24 hours to carry out oxidative decomposition treatment. The amount of dioxins in the concentrate after oxidative decomposition was 680 pg-TEQ / g.

[Example 2]
As in Example 1, the oxidative decomposition treatment of contaminated water containing dioxins, which are hardly decomposable organic compounds, was performed according to the procedure shown in FIG.
(1) Separation process:
To 1 L of contaminated water containing dioxins (dioxins concentration: 3000 pg-TEQ / L), 300 ppm of titanium oxide was added as an inorganic adsorbent, stirred for 1 hour, and then 100 ppm of mosnite as a flocculant was added. The mixture was sufficiently stirred for 2 hours for adsorption treatment and aggregation treatment, and then left overnight.

  The contaminated water left overnight was centrifuged by a conventional method to separate it into a separated solution and a concentrate. And while draining a separated liquid, the concentrate (400 mg as a dry matter) whose dioxins amount is 6800pg-TEQ / g was obtained.

(2) Oxidative decomposition treatment process:
To this concentrate, 0.2 g of powdered molybdenum oxide, which is a metal oxide, and 2.0 g of powdered sodium persulfate were added, and the whole volume was adjusted to 40 ml with water. Oxidative decomposition treatment was performed by heating at 70 ° C. for 24 hours while stirring. The amount of dioxins in the concentrate after oxidative decomposition was 380 pg-TEQ / g.

[Example 3]
(1) Separation process:
Contaminated water containing dioxins (dioxins concentration: 3000 pg-TEQ / L) is filtered using a hollow fiber ultrafiltration membrane (manufactured by Asahi Kasei Co., Ltd.) using a polyethersulfone material, and separated liquid. And concentrate (concentrate). Then, the separated liquid was drained, and a concentrated liquid having a dioxin content of 23000 pg-TEQ / L was obtained.

(2) Oxidative decomposition treatment process:
To this concentrate, 100 mg of powdered molybdenum oxide, which is a metal oxide, and 50 ml of 2% aqueous sodium persulfate solution (corresponding to 1 g of sodium persulfate) were added, so that the total volume was 100 ml with water. Then, the oxidative decomposition process was performed by heating at a temperature of 70 ° C. for 24 hours while stirring. The amount of dioxins in the concentrate after oxidative decomposition was 8.0 pg-TEQ / L.

  As shown in Examples 1 to 3, the amount of dioxins in the concentrate oxidatively decomposed by the method of the present invention is 3000 pg-TEQ / g or less, which is a standard value for industrial waste (liquid examples) 3 is 10 pg-TEQ / L or less), and the same treatment as ordinary industrial waste is possible.

[Comparative Example 1]
In Example 1, oxidative decomposition treatment of contaminated water containing dioxins that are hardly decomposable organic compounds was performed in the same manner as in Example 1 except that 0.04 g of molybdenum oxide that was a metal oxide was not added. It was. The amount of dioxins in the concentrate after oxidative decomposition was 1800 pg-TEQ / g, which was inferior to that of Example 1.

[Comparative Example 2]
In Example 2, oxidative decomposition treatment of contaminated water containing dioxins, which are hardly decomposable organic compounds, was performed in the same manner as in Example 2 except that 0.2 g of molybdenum oxide, which is a metal oxide, was not added. It was. The amount of dioxins in the concentrate after oxidative decomposition was 1300 pg-TEQ / g, which was inferior to that of Example 2.

[Comparative Example 3]
In Example 3, oxidative decomposition treatment of contaminated water containing dioxins which are hardly decomposable organic compounds was performed in the same manner as in Example 3 except that 100 mg of molybdenum oxide which is a metal oxide was not added. The amount of dioxins in the concentrate after oxidative decomposition was 14.8 pg-TEQ / L, which was inferior to Example 3.

[Example 4]
To 2 g of dioxin-contaminated metal scale (dioxins amount: 20000 pg-TEQ / g), 0.1 g of powdered molybdenum oxide which is a metal oxide and 1.0 g of powdered sodium persulfate were added, and water was added. The total volume was made 100 ml, and the oxidative decomposition treatment was performed by heating and stirring at 70 ° C. for 7 hours. The amount of dioxins in the metal scale after the oxidative decomposition treatment was 900 pg-TEQ / g.

[Example 5]
To 2 g of dioxin-contaminated metal scale (dioxins amount: 20000 pg-TEQ / g), 0.1 g of powdered manganese oxide which is a metal oxide and 1.0 g of powdered sodium persulfate were added, and water was added. The total volume was made 100 ml, and the oxidative decomposition treatment was performed by heating and stirring at 70 ° C. for 7 hours. The amount of dioxins in the metal scale after the oxidative decomposition treatment was 720 pg-TEQ / g.

  As shown in Example 4 and Example 3, the amount of dioxins in the concentrate oxidatively decomposed by the method of the present invention is 3000 pg-TEQ / g or less, which is a standard value as industrial waste, The same treatment as that of industrial waste is possible.

[Comparative Example 4]
In Example 4, oxidative decomposition treatment of contaminated water containing dioxins which are hardly decomposable organic compounds was performed in the same manner as in Example 2 except that 1.0 g of molybdenum oxide which is a metal oxide was not added. It was. The amount of dioxins in the concentrate after oxidative decomposition was 1300 pg-TEQ / g, which was inferior to Example 4.

  The present invention is non-hazardous by oxidizing and decomposing refractory organic compounds such as dioxins and PCBs contained in industrial wastewater, soil leachate, cleaning wastewater generated in incinerator demolition work, etc., and concentrates thereof. It can be widely used as a processing method that can be realized.

It is explanatory drawing which showed the procedure of the one aspect | mode of the processing method of the hardly decomposable organic compound of this invention.

Claims (6)

    A method for treating a hardly decomposable organic compound, comprising adding a persulfate to a contaminant containing a hardly decomposable organic compound in the presence of a metal oxide for oxidative decomposition.     It is characterized by separating the contaminated water containing the hardly decomposable organic compound into a concentrate, and oxidatively decomposing the concentrate by adding a persulfate in the presence of a metal oxide. A method for treating a hardly decomposable organic compound. In the processing method of the hardly decomposable organic compound of Claim 2,
In carrying out the separation process,
A method for treating a hardly decomposable organic compound, comprising a step of adding an adsorbent and / or a flocculant to the contaminated water. In the processing method of the hardly decomposable organic compound of Claim 3,
The adsorbent is one or more selected from the group consisting of titanium oxide, zeolite, acidic clay, activated clay, diatomaceous earth, metal oxide, metal powder, and activated carbon. Processing method. In the processing method of the hardly decomposable organic compound in any one of Claims 1 thru | or 4,
The method for treating a hardly decomposable organic compound, wherein a weight ratio of the persulfate to the metal oxide is persulfate: metal oxide = 1: 0.0001 to 1: 1. In the processing method of the hardly decomposable organic compound in any one of Claims 1 thru | or 5,
The method for treating a hardly decomposable organic compound, wherein the metal oxide is one or more selected from the group consisting of molybdenum oxide, manganese oxide, titanium oxide, magnesium oxide, iron oxide and cobalt oxide. .

Images