JP4445758B2 - Method for treating contaminated water containing persistent substances - Google Patents

Description

  The present invention relates to a method for treating contaminated water containing persistent substances such as dioxins and other endocrine disrupting substances.

  In Japan, the Act on Special Measures against Dioxins was enacted in 1999, and in the Act on Special Measures against Dioxins, the emission standard for dioxins is regulated to 10 pg-TEQ / L or less. On the other hand, incinerator demolition work wastewater, industrial wastewater, soil leachate, etc. may contain high-concentration dioxins that greatly exceed these standards, so the development of reduction treatment technology or removal technology is strongly desired. ing.

  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.

  For removing such substances from wastewater (contaminated water) containing these hardly decomposable substances, for example, removal of dioxins, wastewater can be directly decomposed by ozone, photolysis, chemical decomposition of dioxins by hydrogen peroxide, or by microorganisms. Decomposition, separation and removal using an adsorbent and a flocculant are performed. However, such a separation and removal technique directly processes the diluted solution, and therefore, in addition to the low efficiency, a large capital investment is required. Moreover, when the waste water is polluted at a high concentration, it may not be possible to satisfy the emission standard, and it cannot be said that it is a preferable means.

On the other hand, a step of settling with contaminated water, a step of filtering through a net having an average pore size of 10 to 100 μm, a step of catalytically decomposing the permeate by ultraviolet irradiation in the presence of photocatalyst powder, and then an ultrafiltration membrane The technique about the wastewater treatment method which performs the process processed by this is reported (for example, patent document 1).
Also, a treatment method has been proposed in which wastewater is subjected to a separation treatment with a reverse osmosis membrane (RO membrane) and then introduced into an oxidation treatment step in which the concentrated solution is oxidatively decomposed with active oxygen (for example, patent document). 2 and Patent Document 3).

JP 2003-144857 A Japanese Patent Laid-Open No. 11-347591 JP 2000-354894 A

However, in the technique as disclosed in Patent Document 1 described above, in the drainage with a small scale, since the film layer of the scale deposition is not formed on the metal mesh, the scale of the fine particles including dioxin and the dissolved dioxin are not used for the metal mesh. In some cases, the light is transmitted and the processing becomes insufficient.
Further, in the techniques disclosed in Patent Document 2 and Patent Document 3, when free chlorine is present in the contaminated water, a reducing substance such as bisulfite is excessively added to neutralize this. On the other hand, since this bisulfite etc. inhibits oxidative degradation, it cannot be said to be a means for efficiently separating and removing the hardly decomposable substance.

  Accordingly, an object of the present invention is to neutralize free chlorine in removing indestructible substances such as dioxins contained in contaminated water such as incinerator demolition construction wastewater, industrial wastewater, and soil leachate. It can be applied to wastewater containing reducing substances such as bisulfite, and is not limited to the properties of the hard-to-decompose substances, but contains non-degradable substances that can be made harmless efficiently and at low cost. It is to provide a method for treating contaminated water.

In order to achieve the above object, the method for treating contaminated water containing the hardly decomposable substance of the present invention comprises halogenated dibenzodioxins, halogenated dibenzofurans, and coplanar PCBs substituted with a chlorine atom in addition to the ortho position. Dioxins selected from the group consisting of PCBs including: endocrine disrupting substances and carcinogenesis selected from the group consisting of alkylphenols, halogenated phenols, bisphenols, polycyclic aromatic hydrocarbons, and phthalates And contaminated water containing a hardly decomposable substance selected from dichloropropane, trichloroethane, trichloroethylene, tetrachloroethylene and dichloroethylene is passed through a reverse osmosis membrane having a desalination rate (sodium chloride exclusion rate) of 95% or more. The contaminated water is separated and does not pass through the reverse osmosis membrane. At least a part of the liquid is added to the contaminated water containing the hardly decomposable substance, passed again through the reverse osmosis membrane, and the inorganic adsorbent for the liquid that did not pass through the reverse osmosis membrane And the liquid containing the inorganic adsorbent is filtered through a filtration membrane, and the electrical conductivity of the liquid passing through the reverse osmosis membrane again is contaminated with the hardly decomposable substance. The electrical conductivity of water is 3 times or less.

In the method for treating contaminated water containing the hardly decomposable substance of the present invention, when decontaminating the contaminated water, an inorganic adsorbent is added to the contaminated water to adsorb the hardly decomposable substance to the adsorbent. In this state, it is filtered through a filtration membrane and does not contain oxidative decomposition reaction in the reaction system. Therefore, it can be applied to waste water containing reducing agents such as bisulfite, and it is difficult to contain. It is not limited to the properties of the substance, and can efficiently detoxify contaminated water containing a hardly decomposable substance at low cost.
Here, examples of the inorganic adsorbent include titanium oxide, zeolite, acidic clay, activated clay, diatomaceous earth, metal compound, metal powder, and the like.
Examples of applicable filter membranes include ultrafiltration membranes (UF membranes), nanofilter membranes (NF membranes), and microfiltration membranes (MF membranes).

In the method for treating contaminated water containing the hardly decomposable substance of the present invention, the contaminated water containing the hardly decomposable substance is passed through the reverse osmosis membrane in advance to separate the contaminated water, and then does not pass through the reverse osmosis membrane. An inorganic adsorbent may be added to the liquid, and the liquid added with the inorganic adsorbent may be filtered through a filtration membrane.
According to the present invention, since the separation treatment is performed on the contaminated water using the reverse osmosis membrane, the amount of waste water to be treated in the previous stage of adding the inorganic adsorbent is reduced. As a result, the amount of added can be reduced and the volume of waste can be reduced. Further, when adding the inorganic adsorbent, the amount of the inorganic adsorbent added is reduced, so that the equipment in the adsorbent adding step and the subsequent membrane filtration step can be downsized.
And if the separation process by a reverse osmosis membrane and membrane filtration processes, such as an ultrafiltration membrane, are used together, the removal of a hardly decomposable substance from contaminated water can be performed more efficiently.

In the method for treating contaminated water containing the hardly decomposable substance of the present invention, when the contaminated water is passed through the reverse osmosis membrane for separation treatment, at least a part of the liquid that has not passed through the reverse osmosis membrane is treated. It is preferable to add to the contaminated water containing the hardly decomposable substance so as to pass through the reverse osmosis membrane again.
According to the present invention, when performing the separation treatment with the reverse osmosis membrane, at least a part of the liquid that has not passed through the reverse osmosis membrane is added to the contaminated water containing the hardly decomposable substance, and the reverse osmosis is performed again. Since the membrane is allowed to pass through, the hardly decomposable substance is removed as much as possible in the separation treatment by the reverse osmosis membrane.

In the method for treating contaminated water containing the hardly decomposable substance of the present invention, the concentrate that did not pass through the filtration membrane by the treatment of filtration through the filtration membrane is irradiated with light to decompose the concentrate. Is preferred.
According to the present invention, the concentrate that did not pass through the filtration membrane by the treatment of filtration through the filtration membrane was irradiated with light to decompose the concentrate, and thus could not be removed by the filtration treatment. Persistent substances will be removed as much as possible.
Here, examples of the light irradiation include ultraviolet irradiation. A light source such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an excimer laser, natural light, or a fluorescent lamp can be used.

In the method for treating contaminated water containing the hardly decomposable substance of the present invention, the filtration membrane is preferably an ultrafiltration membrane.
According to the present invention, since the filtration membrane is an ultrafiltration membrane, fine particles such as fine adsorbent adsorbing dioxins and dioxins insoluble in water can be sufficiently removed, and operability is improved. In addition, it is economically preferable because the treatment can be performed at low cost.
Further, since the adsorption treatment with the inorganic adsorbent and the membrane filtration treatment with the ultrafiltration membrane are combined, the separation treatment of the hardly decomposable substance is performed more efficiently.

In the method for treating contaminated water containing the hardly decomposable substance of the present invention, the inorganic adsorbent was selected from the group consisting of titanium oxide, zeolite, acid clay, activated clay, diatomaceous earth, metal oxide and metal powder. It is preferable that it is 1 type, or 2 or more types.
According to the present invention, since the kind of the inorganic adsorbent is limited to a specific type, the adsorption and removal of the hardly decomposable substance of the contaminated water by the addition of the inorganic adsorbent is performed more efficiently. .

  In the method for treating contaminated water containing the hardly decomposable substance of the present invention, the contaminated water containing the hardly decomposable substance is treated by passing it through a reverse osmosis membrane, if necessary, and then an inorganic adsorbent is added. Examples of persistent substances that can be detoxified by the present invention include dioxins that are harmful pollutants in soil and sludge, other endocrine disrupting substances, and carcinogenic substances. Etc.

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 −
Bisphenols such as hydroxyphenyl) propane (bisphenol A), 1-bis) 4-hydroxyphenyl) cyclohexane, polycyclic aromatic hydrocarbons such as benzopyrene, chrysene, benzoanthracene, benzofluoranthene, picene, dibutyl phthalate, butyl And phthalic acid esters such as benzyl phthalate and di-2-ethylhexyl phthalate.

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

  The present invention includes a process of adding an inorganic adsorbent to the contaminated water containing the hardly decomposable substance as described above, and filtering the contaminated water to which the inorganic adsorbent has been added through a separation membrane. Liquid that has been treated with contaminated water by passing it through the reverse osmosis membrane in advance, added inorganic adsorbent to the liquid that did not pass through the reverse osmosis membrane, and added inorganic adsorbent. Is preferably filtered through a membrane.

[Separation by reverse osmosis membrane]
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, polyethylene, and polyvinyl alcohol. Examples thereof include resin materials such as those based on polyether 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.

Although there is no restriction | limiting in particular as a desalination rate (sodium chloride exclusion rate) of a reverse osmosis membrane, It is preferable to use a thing with a selectivity of 95% or more in general.
In addition, the liquid component (concentrated water) that has not passed through the membrane by the membrane treatment with the reverse osmosis membrane may be returned to the contaminated water and membrane treated again. In this case, the greater the electrical conductivity of the liquid, the greater the amount of wastewater that can be treated, but the concentration of dioxins also increases proportionally. In this case, since the removal rate of dioxins is almost constant, the dioxins may not be treated below the standard. Therefore, the electrical conductivity of the returned liquid is preferably about 3 times or less than the electrical conductivity of the contaminated water.

[Adsorption treatment with inorganic adsorbent]
Examples of inorganic adsorbents include inorganic compounds having adsorption performance, such as metal compounds such as titanium oxide, zeolite, acid clay, activated clay, diatomaceous earth, and iron oxide, and metal powder such as iron and zinc. 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 1000 ppm. It is preferable to set it as 100 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.

[Treatment with filtration membrane]
In the treatment with a filtration membrane, the type of membrane used for membrane separation is not particularly limited as long as it has separation performance. However, in terms of good separation performance, simplicity, etc., for example, a nanofilter membrane ( It is preferable to use an NF membrane), an ultrafiltration membrane (UF membrane), a microfiltration membrane (MF membrane) or the like.
Among these, the use of an ultrafiltration membrane (UF membrane) can sufficiently remove fine particles such as fine adsorbents adsorbing dioxins and dioxins insoluble in water, and operation. Good and economical.

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.

In addition, when using an ultrafiltration membrane, in order to prevent the fall of the filtration capability of the said filtration membrane, it is preferable to perform back washing | cleaning for about 1 minute once every 30 to 120 minutes. In performing such reverse cleaning, the permeated water treated with the reverse osmosis membrane may be used as water for performing reverse cleaning (back cleaning water). The amount of backwash water used may be about 2 to 8 times the amount of liquid that permeates the ultrafiltration membrane.
And it is preferable to add chemical | medical agents, such as sodium hypochlorite, with respect to this backwash water, As the addition amount of this sodium hypochlorite, the residual chlorine concentration after backwashing is 1-10 mg / What is necessary is just to add so that it may become in the range of L.

  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 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, an example of an embodiment of a method for treating contaminated water containing the hardly decomposable substance of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a treatment apparatus 1 for carrying out one embodiment of a method for treating contaminated water containing a hardly decomposable substance of the present invention. The processing apparatus 1 shown in FIG. 1 has a basic configuration of a reducing substance input unit 10, a reverse osmosis membrane processing unit 20, an adsorbent addition unit 30, and a membrane filtration processing unit 40.

[Reducing substance input unit 10]
The contaminated water containing a hardly decomposable substance such as dioxins is first put into the input tank 11. Free chlorine in the contaminated water is neutralized by adding sodium bisulfite from the reducing substance supply unit 12 to the charging tank 11 via the pump 13. Further, the contaminated water and sodium bisulfite are mixed in the charging tank 11 by the stirring means 14, and the residual chlorine concentration of the contaminated water is measured by a chlorine concentration meter (not shown).

[Reverse osmosis membrane treatment unit 20]
The contaminated water neutralized with sodium bisulfite can remove suspended substances and the like by passing through the prefilter 21. Then, the contaminated water that has passed through the prefilter 21 is sent to the reverse osmosis membrane 22 via the pump 24, and is subjected to membrane treatment by the reverse osmosis membrane 22. And it will be divided into the permeate which passed the said reverse osmosis membrane 22, and the liquid part (concentrate) which did not pass the film | membrane.
Among these, the permeated liquid that has passed through the reverse osmosis membrane 22 can be discharged to the outside because the content of the hardly decomposable substance is less than or equal to the discharge reference value.

Further, as shown in FIG. 1, the liquid component (concentrate) that has not passed through the reverse osmosis membrane 22 is mixed with the contaminated water after passing through the prefilter 21 again, and the membrane treatment is performed again. I do. In this case, the electric conductivity (measured by the electric conductivity meter 23a) of the returned liquid is set to the liquid amount control valve 25 with respect to the electric conductivity of the contaminated water (measured by the electric conductivity meter 23b). Is preferably 3 times or less.
In this way, the concentrate is retransmitted several times, but the concentrate that has not passed through the reverse osmosis membrane 22 by this is sent to the processing tank 31 disposed in the adsorbent charging unit 30. become.

[Adsorbent addition part 30]
In the adsorbent addition unit 30, the inorganic adsorbent sent from the adsorbent supply unit 32 through the feeder 33 is added to the contaminated water liquid (concentrate) sent to the processing tank 31. The In the treatment tank 31, the liquid component of the contaminated water and the inorganic adsorbent are mixed by the stirring means 34, so that the hardly decomposable substance remaining in the liquid component is suitable due to the addition of the inorganic adsorbent. Will be absorbed.

[Membrane filtration processing unit 40]
The contaminated liquid (concentrate) to which the inorganic adsorbent has been added passes through the pump 43a and is subjected to membrane treatment by the ultrafiltration membrane 41 in the membrane filtration unit 40. In addition, when performing membrane treatment with the ultrafiltration membrane 41, if the filtration membrane 41 is backwashed, it is possible to prevent a reduction in filtration capacity, while performing such backwashing. As shown in FIG. 1, the permeated water that has passed through the reverse osmosis membrane 22 in the reverse osmosis membrane treatment unit 20 may be used as water for reverse cleaning (reverse cleaning water).
And with respect to this backwash water, you may add sodium hypochlorite which is a chemical | medical agent from the backwash water tank 42 via the pump 43b.

  Contaminants are separated into permeate and concentrate (backwash water) by membrane treatment by the ultrafiltration membrane 41. Among these, the permeated liquid can be discharged to the outside because the content of the hardly decomposable substance is below the discharge standard value. On the other hand, the concentrate (backwash water) was rendered harmless by performing various decomposition treatments such as photodecomposition treatment by irradiation with ultraviolet rays, reductive decomposition treatment, and oxidative decomposition treatment as shown in FIGS. After that, it can be discarded.

  FIG. 2 is a schematic view of a treatment apparatus 1a for carrying out another aspect of the method for treating contaminated water containing the hardly decomposable substance of the present invention. The processing apparatus 1a shown in FIG. 2 is basically composed of an adsorbent addition unit 30 and a membrane filtration processing unit 40, and is compared with the processing apparatus 1 shown in FIG. This is applied when the membrane treatment unit 20 is removed and a separation process using the reverse osmosis membrane 22 is not required for contaminants.

Therefore, in order to use the processing apparatus 1a shown in FIG. 2, the method described in the adsorbent addition unit 30 and the membrane filtration processing unit 40 in the processing apparatus 1 of FIG.
That is, the inorganic adsorbent sent from the supply unit 32 via the feeder 33 is added to the treatment tank 31 introduced into the contaminated water, mixed by the stirring means 34, and then the membrane filtration processing unit 40. In FIG. 5, membrane treatment is performed by the ultrafiltration membrane 41.

Of the contaminants separated by the membrane treatment of the ultrafiltration membrane 41, the permeate can be discharged to the outside because the content of the hardly decomposable substance is below the discharge reference value. On the other hand, the concentrate (backwash water) was rendered harmless by performing various decomposition treatments such as photodecomposition treatment by irradiation with ultraviolet rays, reductive decomposition treatment, and oxidative decomposition treatment as shown in FIGS. Later, it will be discarded.
In addition, when the permeated water of reverse osmosis membrane filtration is used as the backwash water for ultrafiltration, reducing substances such as sodium bisulfite that inhibit photolysis are removed. High decomposition processing is performed.

[Ultraviolet irradiation unit 50]
FIG. 3 is a schematic view of a treatment apparatus 1b for carrying out another aspect of the method for treating contaminated water containing the hardly decomposable substance of the present invention. The processing apparatus 1b shown in FIG. 3 has a basic configuration of a reducing agent substance input unit 10, a reverse osmosis membrane processing unit 20, an adsorbent addition unit 30, a membrane filtration processing unit 40, and an ultraviolet irradiation unit 50, and is described above. The ultraviolet irradiation part 50 is added with respect to the processing apparatus shown by 1 and the concentrate (backwashing) which did not permeate | transmit the ultrafiltration membrane 41 in the membrane filtration processing part 40 of the processing apparatus 1 shown by FIG. Applicable when decomposition and removal of water is required.
In the following description, parts similar to the parts or members already described in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted.

That is, in order to use the processing apparatus 1c shown in FIG. 3, the reducing agent substance input unit 10, the reverse osmosis membrane processing unit 20, the adsorbent addition unit 30, the membrane filtration processing unit in the processing apparatus 1 shown in FIG. After the treatment at 40, in the ultraviolet irradiation unit 50, the concentrate (backwash solution) that has not passed through the ultrafiltration membrane 41 in the membrane filtration unit 40 is sent to the decomposition tank 51 and stirred by the stirring means 52. However, ultraviolet rays are irradiated by the ultraviolet lamp 53 to decompose and remove the hardly decomposable substance. In the ultraviolet irradiation unit 50, hydrogen peroxide solution may be added from the promoter tank 54 via the pump 55 in order to promote photolysis by ultraviolet rays.
In addition, when titanium oxide is used as the adsorbent applied in the adsorbent processing unit 30, since titanium oxide is present in the concentrate, photolysis processing with high resolution is performed.
And what is necessary is just to dispose of what becomes a liquid component among the concentrate processed by the ultraviolet irradiation part 50 as discharge water, and a solid component as discharge solid, respectively.

  Furthermore, FIG. 4 is a schematic view of a treatment apparatus 1c that implements another aspect of the method for treating contaminated water containing the hardly decomposable substance of the present invention. The processing apparatus 1c shown in FIG. 4 has a basic configuration of an adsorbent addition unit 30, a membrane filtration processing unit 40, and an ultraviolet irradiation unit 50. The processing apparatus 1a shown in FIG. The part 50 is added, and it is necessary to decompose and remove the concentrate (backwash water) that has not permeated the ultrafiltration membrane 41 in the membrane filtration processing unit 40 of the processing apparatus 1a shown in FIG. This applies to

Therefore, in order to use the processing apparatus 1c shown in FIG. 4, after the processing is performed by the adsorbent addition unit 30 and the membrane filtration processing unit 40 in the processing apparatus 1a of FIG. The concentrate (backwash liquid) that has not passed through the ultrafiltration membrane 41 in the membrane filtration processing unit 40 is sent to the decomposition tank 51 and irradiated with ultraviolet rays by the ultraviolet lamp 53 while being stirred by the stirring means 52, and hardly decomposed. Decompose and remove material. In the ultraviolet irradiation unit 50, hydrogen peroxide solution may be added from the promoter tank 54 via the pump 55 in order to promote photolysis by ultraviolet rays.
In the case where titanium oxide is used as the adsorbent applied in the adsorbent processing unit 30, since titanium oxide is present in the concentrate, the resolution is the same as in the processing apparatus 1b shown in FIG. High photodecomposition processing is performed.
Then, as in the above-described embodiment of FIG. 3, among the concentrate processed by the ultraviolet irradiation unit 50, the liquid component may be disposed as discharged water and the solid component as discharged solid.

1 to 4, the reverse osmosis membrane treatment unit 20 shows an example in which contaminated water in which free chlorine has been neutralized by sodium bisulfite passes through the prefilter 21. You may make it perform the separation process by the reverse osmosis membrane 22 directly without letting it pass.
Moreover, although the example which used the ultrafiltration membrane 41 as the filtration membrane in the membrane filtration process part 40 was shown, it is not limited to this, You may use a nano filter membrane, a microfiltration membrane, etc.

  The above-described method for treating contaminated water containing the hardly decomposable substance of the present invention is a method of adding an inorganic adsorbent to the contaminated water and filtering the hardly decomposable substance on the adsorbent with a filter membrane. Since the treatment is performed, the reaction system does not include an oxidative decomposition reaction, and can be applied to waste water containing a reducing agent such as bisulfite neutralized with free chlorine. Further, the present invention provides a method capable of detoxifying contaminated water containing a hardly decomposable substance efficiently and at a low cost without being limited to the properties of the contained hardly decomposable substance.

Furthermore, after passing the contaminated water containing the hardly decomposable substance through the reverse osmosis membrane and separating the contaminated water, an inorganic adsorbent is added to the liquid that has not passed through the reverse osmosis membrane, By including the process of filtering the liquid added with the inorganic adsorbent through a filtration membrane, by using a separation process with a reverse osmosis membrane and a membrane filtration process such as an ultrafiltration membrane together, It is possible to more efficiently remove the hardly decomposable substance.
In addition, the amount of inorganic adsorbent added can be reduced, and waste volume can be reduced. And since the addition amount of an inorganic type adsorbent decreases, size reduction of the installation in the process of adding an adsorbent and the subsequent process using membranes, such as an ultrafiltration membrane, can be achieved.

  And, if the concentrate is decomposed by irradiating light such as ultraviolet rays to the concentrate that has not passed through the filtration membrane by the filtration membrane treatment, the hardly decomposable property that could not be removed by the filtration treatment Substances are removed as much as possible.

  Therefore, according to the method for treating a hardly decomposable organic halogen compound of the present invention, various pollutants such as industrial wastewater, soil leachate, washing wastewater generated in incinerator demolition work, smoke washing wastewater, ash washing wastewater, photographs Wastewater such as drainage and medical drainage, and contaminated water such as drainage can be detoxified.

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, such as an Example, at all.
In this example, “dioxins” is a general term for the sum of halogenated dibenzodioxins, halogenated dibenzofurans, and coplanar PCBs.

[Example 1]
The treatment apparatus shown in FIG. 1 was used to detoxify contaminated water containing dioxins.
(A) Treatment with reverse osmotic pressure membrane:
Stirring sodium bisulfite to 150 mg / L, which is 3 times the amount of free chlorine, with respect to contaminated water containing dioxins (dioxin concentration 3000 pg-TEQ / L, free chlorine concentration 50 mg / L) Added under.

  The contaminated water (electric conductivity: 3000 μS / cm) added with sodium bisulfite is passed through a pre-filter to remove large suspended solids, and then membrane treatment is performed with a reverse osmosis membrane having a desalination rate of 95% or more. did. In this reverse osmosis membrane treatment, a portion of the liquid that did not permeate the reverse osmosis membrane is combined with the contaminated water that has passed through the prefilter and supplied again to the reverse osmosis membrane. The conductivity was adjusted to 9000 μS / cm or less, which is 3 times or less of contaminated water. The concentration of dioxins in the permeate was 1.9 pg-TEQ, which was below the emission standard value (10 pg-TEQ / L).

(B) Addition of inorganic adsorbent / membrane treatment with ultrafiltration membrane:
Next, 10 ppm of titanium oxide, which is an inorganic adsorbent, is added to the liquid fraction that does not pass through the reverse osmosis membrane (dioxin concentration 6300 pg-TEQ / L), and the mixture is stirred and mixed. The membrane was filtered by passing through an ultrafiltration membrane. In this membrane filtration treatment using the ultrafiltration membrane, a solution obtained by adding 3 ppm of hypochlorous acid to the permeate obtained by the treatment by the above-described (A) reverse osmosis membrane treatment was used as the backwash water. Once per minute, the ultrafiltration membrane was washed with 4 times the amount of permeated water of the ultrafiltration membrane. The concentration of dioxins in the permeated liquid that passed through the ultrafiltration membrane was 0.65 pg-TEQ / L and an emission standard value (10 pg-TEQ / L) or less.
The reverse osmotic pressure membrane permeate and the ultrafiltration membrane permeate were combined to form drained water (dioxins concentration was 1.5 pg-TEQ / L).

[Comparative Example 1]
In the step (A) of Example 1, among the liquid components that did not pass through the reverse osmosis membrane filtration, the liquid components were again supplied to the reverse osmosis membrane with respect to the contaminated water that passed through the prefilter. Of the contaminated water was set to 10000 μS / cm, which is about 3.3 times the contaminated water, and the remaining conditions were treated using the same method as in Example 1 to treat the contaminated water containing dioxins. . The concentration of dioxins in the permeate after passing through the ultrafiltration membrane was 30 pg-TEQ / L, which was higher than the wastewater standard value (10 pg-TEQ / L).

[Comparative Example 2]
10 ppm of titanium oxide, which is an inorganic adsorbent, is added to the liquid component that has not passed through the reverse osmosis membrane obtained in the step (A) of Example 1 and mixed with stirring. Instead of performing the filtration treatment, ultraviolet rays were irradiated for 1 hour. The dioxin concentration of the liquid after the ultraviolet irradiation was 2600 pg-TEQ / L, which was higher than the emission standard value (10 pg-TEQ / L). It is thought that it was not decomposed due to the presence of sodium bisulfite.

[Example 2]
Next, a detoxification process for contaminated water containing dioxins was performed using the processing apparatus shown in FIG.
After adding 100 ppm of titanium oxide, which is an inorganic adsorbent, to contaminated water containing dioxins (dioxin concentration 3000 pg-TEQ / L) and stirring and mixing, it is an ultrafiltration membrane with a molecular weight cut off of 150,000. Membrane filtration was performed. In addition, in ultrafiltration membrane treatment, 3 ppm of hypochlorous acid was added to the permeated water of the reverse osmosis membrane treatment obtained in Example 1 to obtain reverse wash water, once every 60 minutes. The ultrafiltration membrane was washed with four times as much water as the filtration membrane permeate. The concentration of dioxins in the permeate that passed through the ultrafiltration membrane was 0.05 pg-TEQ / L, which was below the emission standard value (10 pg-TEQ / L).

[Comparative Example 3]
In Example 2, titanium oxide which is an inorganic adsorbent was not added, and the remaining conditions were treated using the same method as in Example 1 to treat contaminated water containing dioxins. The dioxin density | concentration after passage was 17 pg-TEQ / L, and it was more than the waste water reference value (10 pg-TEQ / L).
From this, it was confirmed that the removal of dioxins was insufficient only by membrane filtration treatment by ultrafiltration.

[Example 3]
When the concentrate in the ultrafiltration membrane of Example 1 (backwash water: dioxins concentration 12000 pg-TEQ / L) was irradiated with ultraviolet rays for 24 hours using the ultraviolet treatment section 50 in the treatment apparatus of FIG. The dioxin concentration of the suspension after ultraviolet irradiation was 600 pg-TEQ / L.
Thus, it has been found that the concentrate can be rendered harmless by performing ultraviolet irradiation on the concentrate that has not passed through the ultrafiltration membrane.

  The present invention is widely used as a treatment method capable of removing detoxifying substances such as dioxins contained in contaminated water such as incinerator demolition construction wastewater, industrial wastewater, and soil leachate, and making them harmless. Can do.

It is a schematic diagram of the processing apparatus which enforces 1 aspect of the processing method of the contaminated water containing the hardly decomposable substance of this invention. It is a schematic diagram of the processing apparatus which enforces the other aspect of the processing method of the contaminated water containing the hardly decomposable substance of this invention. It is a schematic diagram of the processing apparatus which enforces another aspect of the processing method of the contaminated water containing the hardly decomposable substance of this invention. It is a schematic diagram of the processing apparatus which enforces another aspect of the processing method of the contaminated water containing the hardly decomposable substance of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c ... Processing apparatus 10 ... Reductive substance injection | throwing-in part 11 ... Input tank 12 ... Reducible substance supply part 13 ... Pump 14 ... Stirring means 20 ... Reverse osmosis membrane processing part 21 ... Pre filter 22 ... Reverse osmosis Membranes 23a, 23b ... Electric conductivity meter 24 ... Pump, 25 ... Flow rate control valve 30 ... Adsorbent addition unit 31 ... Treatment tank 32 ... Adsorbent supply unit 33 ... Feeder 34 ... Stirring means 40 ... Membrane filtration processing unit 41 ... Filtration Membrane (ultrafiltration membrane)
42 ... Backwash water tanks 43a, 43b ... Pump 50 ... Ultraviolet irradiation part 51 ... Decomposition tank 52 ... Stirring means 53 ... Ultraviolet lamp 54 ... Promoter tank 55 ... Pump

Claims (5)

Dioxins selected from the group consisting of halogenated dibenzodioxins, halogenated dibenzofurans and PCBs including coplanar PCBs substituted with a chlorine atom in addition to the ortho position; alkylphenols, halogenated phenols, bisphenols, polycyclic Endocrine disrupting substances and carcinogenic substances selected from the group consisting of aromatic hydrocarbons and phthalates; and pollution containing persistent substances selected from dichloropropane, trichloroethane, trichloroethylene, tetrachloroethylene and dichloroethylene Water is passed through a reverse osmosis membrane with a desalination rate (sodium chloride rejection rate) of 95% or more to separate the contaminated water,
At least a part of the liquid that did not pass through the reverse osmosis membrane is added to the contaminated water containing the hardly decomposable substance, and again passes through the reverse osmosis membrane,
Add an inorganic adsorbent to the liquid that did not pass through the reverse osmosis membrane,
Including the treatment of filtering the liquid component added with the inorganic adsorbent through a filtration membrane, and the electric conductivity of the liquid component that again passes through the reverse osmosis membrane, the electric conductivity of the contaminated water containing the hardly decomposable substance A method for treating contaminated water containing a hardly decomposable substance, characterized in that it is not more than 3 times the degree. The method for treating contaminated water containing a hardly decomposable substance according to claim 1 , wherein the filtration membrane is backwashed using permeated water of the reverse osmosis membrane filtration. 3. The hardly decomposable substance according to claim 1, wherein the concentrate that has not passed through the filtration membrane by light treatment through the filtration membrane is irradiated with light to decompose the concentrate. Contaminated water treatment method. The said filtration membrane is an ultrafiltration membrane, The processing method of the contaminated water containing the hardly decomposable substance of any one of Claims 1-3 characterized by the above-mentioned. The inorganic adsorbent is titanium oxide, zeolite, acid clay, claims 1 to 4, activated clay, diatomaceous earth, characterized in that the metal oxide and one selected from the group consisting of a metal powder or two or more The processing method of the contaminated water containing the hardly decomposable substance of any one of these.

Images