JP2004033812A - Cleaning method of polluted soil or the like and cleaning equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently remove a pollutant contained in polluted soil or the like. <P>SOLUTION: Soil or the like polluted with a pollutant and a surfactant are mixed and washed in a first blending tank 1 to transfer the pollutant to a liquid phase from a solid such as soil or the like. The formed mixture is subjected to solid-liquid separation in a centrifugal dehydrator and a solid phase is taken out as cleaned matter while an acid and a flocculant are blended in a second blending tank 6 and, subsequently, the bonded matter of the surfactant and the pollutant is separated from the liquid phase in a sedimentation tank 7. <P>COPYRIGHT: (C)2004,JPO

Description

【００２８】
【００２９】
【発明の効果】
本発明による処理方法は汚染土壌等と界面活性剤とを撹拌・混合することによって、汚染土壌等に含有される汚染物質を高効率に除去すると共に、洗浄水中の界面活性剤と汚染物質との結合体を効率的に水相から分離するといった効果を奏する。
【図面の簡単な説明】
【図１】本発明に係る汚染土壌等の浄化方法の実施形態を示す図。
【図２】本発明に係る汚染土壌等の浄化方法の別の実施形態を示す図。
【符号の説明】
１…第一混和槽、２…界面活性剤注入管、３…遠心脱水機、４…酸注入管、５…凝集剤注入管、６…第二混和槽、７…沈殿槽、８…ｐＨ調整槽、９…中和槽、１０…アルカリ注入管、１１…処理水循環管、１２…第三混和槽、１３…浮上分離槽、１４…加圧水注入管。[0001]
[Industrial applications]
The present invention relates to a method and an apparatus for treating soil or the like containing pollutants, and in addition to contaminated soil, landfill waste and sediment of rivers, lakes and marshes or sea areas, and sludge generated from a water treatment process. It can also be applied to the purification treatment of dehydrated cake.
[0002]
[Prior art]
As a method for purifying contaminated soil and the like, a method of thermal decomposition, a method of purifying with microorganisms, a method of cleaning with chemicals, and the like are conventionally known. The thermal decomposition method has a high energy cost to heat a large amount of contaminated soil to a temperature at which contaminants such as dioxins can be decomposed, and the method of purifying by microorganisms requires a period of years until the purification treatment is completed. However, there is a disadvantage that the Regarding the method of washing with a chemical, for example, Japanese Patent No. 3182546 discloses a method of washing soil contaminated with trichloroethylene or the like with a surfactant. However, in this method, activated carbon adsorption treatment is used to remove contaminants contained in the wash water, and the replacement frequency is high because the cleaning solution containing surfactants and various organic substances in soil at a high concentration is activated carbon treated. There has been a problem that the cost becomes high and expensive activated carbon is used in large quantities.
[0003]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above problems, and an object thereof is to provide a method and a device for purifying contaminated soil and the like, which efficiently remove contaminants contained in the contaminated soil and the like. I do.
[0004]
[Means for Solving the Problems]
The invention of claim 1 provides a step of mixing and washing a soil or the like contaminated with a contaminant and a surfactant to transfer the contaminant from a solid content of the soil or the like to a liquid phase, and after this step, A contaminated soil, comprising: a step of solid-liquid separating the mixture to remove a solid phase as a purified substance; and a step of separating a complex of a surfactant and a contaminant from the solid-liquid separated liquid phase. And so on. In this method, a contaminant and a surfactant in the liquid phase are separated from the liquid phase while being bound, so that a clear liquid phase is obtained.
[0005]
The invention according to claim 2 is characterized in that an acid or an alkali is mixed into the soil or the like before or during mixing the soil or the like contaminated with the pollutant with the surfactant. It is a method for purifying contaminated soil and the like described in the above. In this method, the washing effect can be enhanced by adding an acid or an alkali to soil or the like.
[0006]
Further, the invention of claims 3, 4, 5 and 6 relates to the binding of a surfactant and a contaminant from a liquid phase by any means of addition of acid / alkali, heating, addition of inorganic salt or aeration / injection of pressurized water. 3. The processing method according to claim 1, wherein the body is separated. Further, these processes can be appropriately combined.
The invention according to claim 7 is characterized in that a surfactant is added to the separated liquid phase of the conjugate of the surfactant and the contaminant, and the resultant is reused for cleaning soil and the like contaminated with the contaminant. A processing method according to any one of claims 1 to 6. In this method, by reusing the treated liquid phase, the amount of makeup water and the amount of drainage to the outside of the system can be significantly reduced.
[0007]
The invention according to claim 8 is characterized in that the combined substance of the surfactant and the contaminant separated from the liquid phase is put into an incinerator, a melting furnace or a pyrolysis furnace to thermally decompose the contaminant. Item 8. The processing method according to any one of Items 1 to 7. In this method, the contaminants separated from the liquid phase can be completely detoxified by thermal decomposition.
[0008]
A ninth aspect of the present invention provides a mixing means for mixing and washing a soil or the like contaminated with a pollutant and a surfactant, a solid-liquid separation means for solid-liquid separation of the mixture, and a solid-liquid separation liquid phase. An apparatus for purifying contaminated soil or the like, comprising: a separation unit that separates a combination of a surfactant and a contaminant. The purification method of the present invention can be realized by the present apparatus.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a method and a device for purifying contaminated soil according to the present invention will be described with reference to the drawings.
[0010]
(Embodiment 1)
FIG. 1 shows an embodiment of a method for purifying contaminated soil and the like according to the present invention. In the figure, 1 is a first mixing tank, 2 is a surfactant injection pipe, 3 is a centrifugal dehydrator, 4 is an acid injection pipe, 5 is a coagulant injection pipe, 6 is a second mixing tank, and 7 is a sedimentation tank. is there.
[0011]
The soil or the like containing the contaminants is mixed with the surfactant supplied from the surfactant injection pipe 2 in the first mixing tank 1, and the contaminants contained in the contaminated soil and the like are transferred to the liquid phase. Next, the mixture is supplied to the centrifugal dehydrator 3 and separated into a liquid phase containing a combination of a surfactant and a contaminant, and a solid phase from which the contaminant has been removed. The solid phase is taken out as it is as a purified substance. The liquid phase was mixed with the acid supplied from the acid injection pipe 4 and the coagulant supplied from the coagulant injection pipe 5 in the second mixing tank 6, and the combined surfactant and contaminant was insolubilized and coagulated. Thereafter, the precipitate is separated as sludge in the sedimentation tank 7. Sludge is finally incinerated in an incinerator, and pollutants are pyrolyzed.
[0012]
Here, the pollutants are dioxins, environmental hormones, pesticides, hardly decomposable organic substances such as PCBs, inorganic substances such as fluorine, boron, and heavy metals, and the binding between these substances and soil fine particles. Body, etc., and is not limited to a specific substance. The soil and the like refer to soil, landfill waste, bottom mud of rivers, lakes and marshes, or sea areas, as well as sludge generated from a water treatment process and its dewatered cake.
[0013]
If the treatment is performed with the contaminant content as high as possible in the contaminated soil, etc., the efficiency of contact between the surfactant and the contaminant will be increased. It is more preferable to mix the surfactant with the contaminated soil or the like after increasing the organic matter content in the contaminated soil or the like. Of course, when the mixing operation is difficult in the form of treating soil or the like as it is, it is possible to add water until the mixing operation can be easily performed to perform the processing.
[0014]
As the surfactant used in the present invention, various surfactants such as anionic, cationic, amphoteric, and nonionic surfactants can be used. For example, carboxylate salts such as soaps, sulfate ester salts, sulfonate salts, etc., as the anionic type, amine salts, quaternary ammonium salts, etc., as the cationic type, and amino acid type, betaine type, etc. as the amphoteric type. As the nonionic type, a polyethylene glycol type or the like can be used.
[0015]
The means for mixing and washing the contaminated soil and the like with the surfactant is not limited to this embodiment, but a mixing tank equipped with a stirrer is usually used. Also, it is preferable to use ultrasonic irradiation means in combination, because the efficiency of contact between the contaminated soil and the like and the surfactant can be increased. By doing so, the contaminants can be transferred from the solid content such as soil to the liquid phase.
[0016]
Various means such as a screen, a sedimentation tank, and a filter press can be used as a solid-liquid separation means for contaminated soil and the like, in addition to a centrifugal dehydrator.
[0017]
The means for separating the conjugate of the surfactant and the contaminant from the liquid phase can be selected from several means depending on the characteristics of the surfactant to be applied. When the applied surfactant is an amino acid type amphoteric surfactant, it can be insolubilized by adding an acid after the washing operation and adjusting the pH to the isoelectric point as in the present embodiment. In the case of a polyethylene glycol type nonionic surfactant, it can be insolubilized by heating to a temperature higher than the cloud point. In the case of an anionic surfactant, an insoluble salt can be formed by adding an inorganic compound containing calcium or the like as a main component. The conjugate of the insolubilized surfactant and the contaminant can be separated by means such as floating or sedimentation depending on the specific gravity. In some cases, centrifugation can be applied.
[0018]
In the case where separation is difficult only by simply insolubilizing, separation can be promoted by adding and mixing a flocculant to form flocs. As the coagulant used at this time, iron salts such as ferric chloride and ferric polysulfate, aluminum salts such as sulfate and PAC, and the like, and organic salts such as polyacrylamide can be used. Molecular compounds can be used in combination.
[0019]
On the other hand, when a foaming surfactant is used, a large number of bubbles are formed by aerating the liquid phase or by injecting pressurized water in which a gas is dissolved in supersaturation into the liquid phase, thereby forming an interface on the bubble surface. The conjugate of activator and contaminant can be concentrated and removed as scum.
[0020]
The liquid phase from which the conjugate of the surfactant and the contaminant has been separated can be used again for the purification treatment. For example, it is possible to add a surfactant to make it contact with contaminated soil or the like, or to use it for rinsing the surfactant remaining in the soil after washing.
[0021]
The combined amount of the surfactant and the contaminant separated from the liquid phase is significantly reduced since the condensed soil before the treatment is concentrated. Therefore, it is possible to detoxify at low cost using various means such as oxidative decomposition by ozone injection and dechlorination by ultraviolet irradiation, but it can be almost completely decomposed in a short time by a heating method. In particular, when an existing incinerator, melting furnace or pyrolysis furnace is present near the soil purification facility, the combination of the surfactant and the contaminant separated from the liquid phase is treated by the heating system. This is preferable because the construction cost of the equipment can be reduced.
[0022]
(Embodiment 2)
FIG. 2 shows another embodiment of the method for purifying contaminated soil and the like according to the present invention. In the figure, 1 is a first mixing tank, 2 is a surfactant injection pipe, 3 is a centrifugal dehydrator, 4 is an acid injection pipe, 5 is a coagulant injection pipe, 8 is a pH adjustment tank, 9 is a neutralization tank, Reference numeral 10 denotes an alkali injection pipe, 11 denotes a treated water circulation pipe, 12 denotes a third mixing tank, 13 denotes a flotation tank, and 14 denotes a pressurized water injection pipe.
[0023]
The contaminated soil and the like are mixed with the acid supplied from the acid injection pipe 4, the treatment water and the makeup water supplied from the treated water circulation pipe 11 in the pH adjusting tank 8, and dissolve the calcium compound contained in the contaminated soil and the like. Next, the pH is adjusted to neutral by mixing with the alkali supplied from the alkali injection tube 10 in the neutralization tank 9. Subsequently, after being mixed with the surfactant supplied from the surfactant injection pipe 2 in the first mixing tank 1, the liquid phase containing the combination of the surfactant and the contaminant and the contaminant are removed in the centrifugal dehydrator 3. And the separated solid phase. The liquid phase is mixed with the coagulant supplied from the coagulant injection pipe 5 and the pressurized water obtained by dissolving the air supplied from the pressurized water injection pipe 14 in the flotation tank 13 in a supersaturated state. After being concentrated on the bubble surface, it is floated and separated as scum, and the remainder is treated water. On the other hand, the solid phase taken out by the centrifugal dehydrator is once mixed with the treated water in the third mixing tank 12 and then solid-liquid separated again by the centrifugal dehydrator 3, so that the remaining surfactant and the contaminant are bound. After washing out the body, it is removed as a purifying substance.
[0024]
If the contaminated soil or the like has a high content of lime components or metal components such as iron and manganese, which prevents the contact between the contaminants and the surfactant and high cleaning efficiency cannot be obtained, the contaminated soil as in this embodiment is used. Mixing an acid before or during mixing the soil and the like with the surfactant to dissolve the lime component and the metal component improves the contact efficiency and obtains a good cleaning effect. On the other hand, if the contaminated soil or the like has a high content of organic substances such as humic acid and prevents the target contaminant from contacting the surfactant and high cleaning efficiency cannot be obtained, the contaminated soil or the like and the surfactant should not be mixed. Alternatively, if an organic substance such as humic acid is dissolved by mixing an alkali during the mixing, the contact efficiency is improved and a good cleaning effect is obtained.
[0025]
Further, by using the treated water obtained as in the present embodiment for rinsing the solid content after centrifugal dehydration, dissolving the surfactant, and adjusting the water content of the object to be purified, the total amount of water used can be reduced, and the purification cost can be reduced. This has the effect of reducing wastewater and reducing wastewater.
[0026]
【Example】
Table 1 shows the results of treating soil contaminated with dioxins by the treatment method shown in FIG. However, the processing conditions are as follows.
[0027]
[Example processing method]
・ Type of surfactant: Nonionic surfactant (alcohol)
・ Reaction time with surfactant: 30 minutes ・ Reaction temperature: normal temperature ・ Surfactant injection rate: 0.5 wt%
[Table 1]

[0028]
[0029]
【The invention's effect】
The treatment method according to the present invention removes the pollutants contained in the contaminated soil and the like with high efficiency by stirring and mixing the contaminated soil and the like with the surfactant, and also removes the surfactant and the contaminants from the washing water. This has the effect of efficiently separating the conjugate from the aqueous phase.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a method for purifying contaminated soil and the like according to the present invention.
FIG. 2 is a diagram showing another embodiment of the method for purifying contaminated soil and the like according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... First mixing tank, 2 ... Surfactant injection pipe, 3 ... Centrifugal dehydrator, 4 ... Acid injection pipe, 5 ... Coagulant injection pipe, 6 ... Second mixing tank, 7 ... Precipitation tank, 8 ... pH adjustment Tank, 9: neutralization tank, 10: alkali injection pipe, 11: treated water circulation pipe, 12: third mixing tank, 13: floating separation tank, 14: pressurized water injection pipe.

Claims (9)

Mixing and washing the soil or the like contaminated with the contaminant with a surfactant to transfer the contaminant from the solid content of the soil or the like to a liquid phase, and after this step, solid-liquid separation of the mixture A method for purifying contaminated soil or the like, comprising: a step of taking out a solid phase as a purified substance; and a step of separating a combined substance of a surfactant and a contaminant from a liquid phase subjected to solid-liquid separation. The method for purifying contaminated soil or the like according to claim 1, wherein an acid or an alkali is mixed with the soil or the like before or at the time of mixing the soil or the like contaminated with the contaminant with the surfactant. The contamination according to claim 1 or 2, wherein the step of separating the conjugate of the surfactant and the contaminant from the solid-liquid separated liquid phase includes a step of mixing an acid or an alkali with the liquid phase. How to purify soil. 4. The method according to claim 1, wherein the step of separating the conjugate of the surfactant and the contaminant from the solid-liquid separated liquid phase includes a step of heating the liquid phase to 40 to 80C. The method for purifying contaminated soil described in Crab. The step of separating the conjugate of the surfactant and the contaminant from the solid-liquid separated liquid phase includes, in the liquid phase, an inorganic material containing one or more selected from the group consisting of calcium, magnesium, silica and aluminum. The method for purifying contaminated soil or the like according to any one of claims 1 to 4, further comprising a step of adding a compound. 2. The method according to claim 1, wherein the step of separating the conjugate of the surfactant and the contaminant from the liquid phase includes the step of aerating the liquid phase or injecting pressurized water in which a gas is supersaturated into the liquid phase. 6. The method for purifying contaminated soil and the like according to any one of claims 5 to 5. The treatment method according to any one of claims 1 to 6, wherein the liquid phase from which the combination of the surfactant and the contaminant has been separated is reused for washing soil and the like contaminated with the contaminant. 8. The contaminant according to claim 1, wherein the contaminant is condensed by heating the mixture of the surfactant and the contaminant separated from the liquid phase into an incinerator, a melting furnace or a pyrolysis furnace. Processing method. Mixing means for mixing and washing the soil and the like contaminated with contaminants and the surfactant, solid-liquid separation means for solid-liquid separation of the mixture, and binding of the surfactant and the contaminant from the solid-liquid separated liquid phase An apparatus for purifying contaminated soil or the like, comprising: a separating means for separating a body.

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