JP2010200965A - Processing method and device for aromatic chlorine compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing method and device for aromatic chlorine compound, capable of processing harmful substances of aromatic chlorine compound, such as PCB, dioxin, TCB, etc., correctly at low cost. <P>SOLUTION: In the processing method for aromatic chlorine compound, persulfate and chelate iron are added to the aromatic chlorine compound to decompose the aromatic chlorine compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for safely and efficiently treating an aromatic chlorine compound.

  Polychlorinated biphenyl (PCB), which is known as an aromatic chlorine compound, is a substance that has properties such as being hardly decomposed by heat, good insulating properties, non-flammable properties, and a wide range of insulating oils for transformers and capacitors. Used in the field. However, PCB is a substance that may cause damage to human health and living environment. Due to its indegradability, high accumulation, and the nature of moving long distances through air and mobile species. , Bring about environmental pollution.

  In view of such circumstances, in Japan, PCB waste is obligated to be disposed of under the Special Measures for PCB Disposal Law, and in the past 30 years using established methods such as hydrothermal oxidative decomposition and reductive thermal chemical decomposition. Processing that has not progressed has started to move (see Non-Patent Document 1).

  On the other hand, it has become apparent that there is PCB contamination even in soil, groundwater, etc., which are not subject to the PCB Special Measures Law, even though the concentration is low. The disposal method based on the PCB Processing Special Measures Law aims to reliably process high-concentration PCBs, and there are problems in terms of energy, cost, and processing safety in order to apply to low-concentration contaminants. For this reason, development of a method capable of performing appropriate processing at low cost is desired. Further, regarding aromatic chlorine compounds such as trichlorobenzene other than PCB, the indication of harmfulness and the presence of contamination have been clarified, and a method capable of appropriate treatment at low cost is desired.

  Against this background, in recent years, a method for soil purification by Fenton treatment at a heating temperature (150 to 250 ° C.) lower than the conventional high-temperature and high-pressure treatment (for example, see Patent Document 1), activated carbon is added to Fenton oxidation. A method of soil purification (for example, see Patent Documents 2 and 3), a method of adding iron powder to contaminated soil, heating with microwaves, volatilizing organochlorine compounds, and then reducing (for example, see Patent Document 4) Proposed.

  In addition, a method using persulfuric acid or the like has been proposed as a method for removing chemical contamination (see, for example, Patent Documents 5 to 9).

Japanese Patent No. 3553454 Japanese Patent Laid-Open No. 2006-247483 JP 2007-215552 A JP 2004-202290 A JP 2002-307049 A JP 2006-75469 A JP 2006-341195 A Special table 2008-506511 gazette Special table 2007-521940

Yamamoto, “Environmental Purification Technology”, vol. 4, no. 8, p. 1-5

  However, these methods also have problems in operation management and safety due to heating, gas volatilization, and the like. Moreover, the specific examples about aromatic chlorine compounds, such as PCB, dioxins, and trichlorobenzene (TCB), are not shown by the method of patent documents 2, 5-9.

  Accordingly, an object of the present invention is to provide an aromatic chlorine compound processing method and processing apparatus capable of appropriately processing harmful substances of aromatic chlorine compounds such as PCB, dioxins, and TCB at low cost. is there.

  (1) In the method for treating an aromatic chlorine compound of the present invention, a persulfate and chelated iron are added to the aromatic chlorine compound to decompose the aromatic chlorine compound.

  (2) In the method for treating an aromatic chlorine compound according to (1) above, the chelated iron is preferably an organic acid iron.

  (3) In the method for treating an aromatic chlorine compound according to (2) above, the organic acid iron is preferably iron citrate, and is preferably adjusted by mixing citric acid and an iron salt.

  (4) In the method for treating an aromatic chlorine compound according to any one of the above (1) to (3), it is preferable that the pH at the time of decomposing the aromatic chlorine compound is an alkaline condition.

  (5) The apparatus for treating an aromatic chlorine compound of the present invention comprises a decomposition reaction tank for decomposing and treating the aromatic chlorine compound by adding persulfate and chelate iron to the aromatic chlorine compound, and the decomposition Persulfate addition means for adding the persulfate to the reaction tank and chelate iron addition means for adding the chelate iron to the decomposition reaction tank.

  (6) In the aromatic chlorine compound treatment apparatus according to (5), the chelated iron is preferably an organic acid iron.

  (7) In the apparatus for treating an aromatic chlorine compound as described in (6) above, the organic acid iron is iron citrate, and a production reaction for producing citric acid and an iron salt to produce the iron citrate It is preferable to provide a tank.

  (8) The method for treating an aromatic chlorine compound of the present invention is to decompose the aromatic chlorine compound by adding persulfate and chelated iron to soil and groundwater contaminated with the aromatic chlorine compound. is there.

  (9) In the method for treating an aromatic chlorine compound according to (8), it is preferable to add the persulfate and the chelated iron to the soil and groundwater contaminated with the aromatic chlorine compound.

  (10) In the method for treating an aromatic chlorine compound according to the above (8) or (9), it is preferable that the pH at the time of decomposing the aromatic chlorine compound is an alkaline condition.

  ADVANTAGE OF THE INVENTION According to this invention, the harmful | toxic substance of aromatic chlorine compounds, such as PCB, dioxins, and TCB, can be processed appropriately at low cost.

It is a schematic diagram which shows an example of a structure of the processing apparatus of the aromatic chlorine compound which concerns on embodiment of this invention. It is a schematic diagram which shows an example of a structure of the processing apparatus of the aromatic chlorine compound which concerns on other embodiment of this invention. It is a schematic diagram which shows an example of a structure of the processing apparatus of the aromatic chlorine compound which concerns on other embodiment of this invention. It is a schematic diagram which shows an example of a structure of the processing system of the aromatic chlorine compound which concerns on other embodiment of this invention. It is a schematic diagram which shows an example of a structure of the processing system of the aromatic chlorine compound which concerns on other embodiment of this invention. It is a schematic diagram which shows an example of a structure of the purification system of the aromatic chlorine compound which concerns on other embodiment of this invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic diagram showing an example of the configuration of an aromatic chlorine compound processing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the aromatic chlorine compound processing apparatus 1 includes a decomposition reaction tank 10 for decomposing an aromatic chlorine compound, a first pump 12 and a persulfate supply line 14 provided with a persulfate supply line 14. A chelate iron addition means comprising a persulfate tank 16, a second pump 18 and a chelate iron supply line 20, a chelate iron tank 22, a treated water inflow line 24, and a treated water discharge line 26. Is.

  A treated water inflow line 24 is connected to the treated water supply port (not shown) of the decomposition reaction tank 10, and the treated water discharge line 26 is connected to the treated water discharge port (not shown) of the decomposition reaction tank 10. Is connected. The persulfate supply port (not shown) of the decomposition reaction tank 10 and the persulfate tank 16 are connected by a persulfate supply line 14. Further, a chelate iron supply line 20 connects the chelate iron supply port (not shown) of the decomposition reaction tank 10 and the chelate iron tank 22. The persulfate supply line 14 is provided with a first pump 12, and the chelate iron supply line 20 is provided with a second pump 18.

  In the present embodiment, the persulfate addition means is configured by the first pump 12 and the persulfate supply line 14, but is not necessarily limited as long as the persulfate can be supplied to the decomposition reaction tank 10. The configuration is not limited to the above. Similarly, the chelate iron addition means is configured by the second pump 18 and the chelate iron supply line 20, but is not necessarily limited to the above configuration as long as the chelate iron can be supplied to the decomposition reaction tank 10. Is not to be done.

  If the decomposition reaction tank 10 is a tank for adding a persulfate and chelated iron to a solution containing an aromatic chlorine compound to decompose the aromatic chlorine compound, its structure is not particularly limited. However, it is preferable to provide a stirrer (a stirrer, a diffuser, a submersible pump, etc.) in the decomposition reaction tank 10 in order to increase the decomposition efficiency of the aromatic chlorine compound. The pH during the reaction in the decomposition reaction tank 10 is 7 or less, preferably in the range of 2-5. Further, in the purification of groundwater, soil, etc. contaminated with aromatic chlorine compounds as described later, when there is a risk of elution of heavy metals, the pH may be treated from weakly acidic to alkaline (pH 5-10). Is possible. Moreover, although the temperature at the time of reaction can be implemented at normal temperature of 15-30 degreeC, it is also possible to heat and implement as needed.

  Below, the process of the aromatic chlorine compound using the processing apparatus 1 which concerns on this embodiment is demonstrated.

  Persulfate is supplied from the first pump 12 to the treated water flowing into the decomposition reaction tank 10 from the treated water inflow line 24 via the persulfate supply line 14, and chelate iron is supplied by the second pump 18. It is supplied via the chelated iron supply line 20. Thereby, in the decomposition reaction tank 10, the decomposition process of an aromatic chlorine compound is performed. In the decomposition reaction tank 10, it is preferable to mix the oxidizing agent and the substance to be decomposed with a stirrer, a mixer, a submersible pump, an aeration, or the like. Further, the residence time (reaction time) of water is preferably at least 5 minutes. Furthermore, when the decomposition target substance has a low concentration of 1 mg / L or less, it is more efficient to perform the multistage treatment by connecting the decomposition reaction tanks 10 in two or three stages in series. As a result, the aromatic chlorine compound can be efficiently decomposed at normal temperature and normal pressure.

  For example, the inventors of the present inventors have intensively studied that aromatic chlorine compounds, which are hardly decomposable substances such as TCB, which is also a model substance for PCB decomposition experiments, can be decomposed by adding persulfate and chelated iron. This is the first knowledge obtained. And the processing method which decomposes | disassembles an aromatic chlorine compound by adding persulfate and chelate iron can raise decomposition efficiency rather than decompose | disassembling an aromatic chlorine compound with persulfuric acid alone.

  Although the mechanism involved in this phenomenon has not been clarified, the addition of chelated iron such as iron citrate only promotes the generation of sulfate radicals effective in the decomposition of aromatic chlorine compounds resulting from the decomposition of persulfuric acid. However, it is considered that the aromatic chlorine compound is efficiently decomposed at normal temperature and normal pressure by releasing sulfuric acid radicals in a sustained manner, and further by generating organic radicals by adding an organic substance such as citric acid.

  Note that the present inventors have disclosed a method for purifying organic pollutants using persulfuric acid (Japanese Patent Laid-Open No. 2002-307049, Japanese Patent No. 4027209), after Fenton treatment with iron containing hydrogen peroxide and chelated iron. A method for purifying organic pollutants using sulfate (Japanese Patent Laid-Open No. 2006-341195) and a method for purifying organic pollutants in the presence of iron containing persulfuric acid, hydrogen peroxide and chelated iron (Japanese Patent Laid-Open No. 2006-341195) 2006-75469). However, Japanese Patent Application Laid-Open No. 2002-307049 and Japanese Patent No. 4027209 do not specifically show a case where an aromatic chlorine compound is decomposed. Japanese Patent Application Laid-Open No. 2006-341195 discloses a method of decomposing by the oxidizing power of persulfuric acid after being decomposed by hydroxy radicals generated by Fenton treatment, and not a method using sulfuric acid radicals. Further, in Japanese Patent Application Laid-Open No. 2006-75469, the presence of hydrogen peroxide is an essential technique, and specific examples of specific promotion effects using chelated iron, particularly organic acid iron, are also available regarding the form of iron. Not shown. In both methods, the decomposition target is trichlorethylene or the like which is decomposed at normal temperature and normal pressure with ozone, hydroxy radicals, etc., which are conventionally known, and is different from the present embodiment. Furthermore, this embodiment does not require an apparatus for adding hydrogen peroxide, has a low chemical cost, and is also applicable to substances that were previously considered not to be decomposed at normal temperature and normal pressure. It is effective for.

  The persulfate concentration in the decomposition reaction tank 10 is not particularly limited, but is preferably at least 10 times the concentration of the aromatic chlorine compound, and more preferably at least 10 mg / L or more. Preferably, it is more preferably in the range of 500-50000 mg / L, more preferably in the range of 500-20000 mg / L, and still more preferably in the range of 500-10000 mg / L. Further, the mixing ratio of persulfate and chelate iron is not particularly limited, but a large amount of persulfate is preferable, and persulfate: chelate iron is 2: 1 to 50: 1 in molar mixing ratio. More preferably, it is the range.

  In the present embodiment, the treated water is discharged from the treated water discharge line 26 after completion of the aromatic chlorine compound decomposition reaction. The pH of the treated water passing through the treated water discharge line 26 may become acidic due to sulfuric acid generated by the decomposition of persulfuric acid in the decomposition reaction tank 10. Therefore, it is preferable to neutralize by injecting an alkaline agent such as caustic soda into the decomposition reaction tank 10 or the treated water discharge line 26 (during or after the reaction). In addition, since unreacted persulfate may remain in the treated water, in order to treat the persulfate, for example, sodium sulfite, sodium thiosulfate solution, etc. It is preferable to inject a reducing agent to reduce the persulfate.

  FIG. 2 is a schematic view showing an example of the configuration of an aromatic chlorine compound processing apparatus according to another embodiment of the present invention. In the aromatic chlorine compound processing apparatus 2 shown in FIG. 2, the same components as those of the aromatic chlorine compound processing apparatus 1 shown in FIG.

  The aromatic chlorine compound treatment apparatus 2 shown in FIG. 2 includes a decomposition reaction tank 10 for decomposing an aromatic chlorine compound, a persulfate addition means including a first pump 12 and a persulfate supply line 14; A chelate iron addition means comprising a persulfate tank 16, a second pump 18 and a chelate iron supply line 20, a production reaction tank 28 for producing chelate iron, a treated water inflow line 24, and a treated water discharge A line 26, a citric acid supply line 30 as a citric acid addition means, and an iron salt supply line 32 as an iron salt addition means are provided.

  A citric acid supply line 30 is connected to a citric acid supply port (not shown) of the production reaction tank 28, and an iron salt supply line 32 is connected to an iron salt supply port (not shown) of the production reaction tank 28. Has been. A chelate iron supply line 20 connects the chelate iron discharge port (not shown) of the production reaction tank 28 and the chelate iron supply port (not shown) of the decomposition reaction tank 10. The other structure is the same as that of the aromatic chlorine compound processing apparatus 1 shown in FIG.

  The production reaction tank 28 is a tank for producing iron citrate, and a stirrer (stirrer, air diffuser, submersible pump, etc.) is provided in the production reaction tank 28 in order to increase the production efficiency of iron citrate. It is preferable.

  Below, the process of the aromatic chlorine compound using the processing apparatus 2 which concerns on this embodiment is demonstrated.

  Citric acid is supplied from the citric acid supply line 30 and iron salt is supplied from the iron salt supply line 32 to the production reaction tank 28 and mixed to produce iron citrate. Then, persulfate is supplied from the first pump 12 to the treated water flowing into the decomposition reaction tank 10 from the treated water inflow line 24 via the persulfate supply line 14, and the second pump 18 Acid iron is supplied via the chelate iron supply line 20. Also by such a method, the aromatic chlorine compound can be decomposed in the same manner as described above. In addition, it is possible to generate iron citrate from citric acid and iron salts, and use the generated iron citrate for the decomposition of aromatic chlorine compounds, significantly reducing processing costs compared to purchasing commercially available iron citrate. can do. However, when citric acid and an iron salt are mixed as in this embodiment, it is preferable to supply iron citrate to the decomposition reaction tank 10 after sufficiently generating iron citrate. It should be noted that the citric acid supply line 30 and the iron salt supply line 32 are not necessarily required if citric acid and iron salt can be mixed in the production reaction tank 28 to produce iron citrate.

  FIG. 3 is a schematic diagram showing an example of the configuration of an aromatic chlorine compound processing apparatus according to another embodiment of the present invention. In the aromatic chlorine compound processing apparatus 3 shown in FIG. 3, the same components as those of the aromatic chlorine compound processing apparatus 1 shown in FIG.

  The aromatic chlorine compound treatment apparatus 3 shown in FIG. 3 includes a decomposition reaction tank 10 for decomposing an aromatic chlorine compound, a persulfate addition means including a first pump 12 and a persulfate supply line 14; A chelate iron addition means comprising a persulfate tank 16, a second pump 18 and a chelate iron supply line 20, a chelate iron tank 22, a treated water inflow line 24, treated water discharge lines 26 and 27, and activated carbon The apparatus 34 is provided. The decomposition reaction tank 10 and the activated carbon device 34 are connected by a treated water discharge line 26.

  The treated water treated by the decomposition reaction tank 10 may contain unreacted persulfate and aromatic chlorine compounds. Therefore, in this embodiment, the unreacted persulfate or aromatic chlorine compound can be treated by passing treated water through the activated carbon device 34 and performing activated carbon treatment. Examples of the activated carbon treatment by the activated carbon device 34 include activated carbon treatment by a complete mixing tank using powdered activated carbon, treatment by a fixed bed of granular activated carbon using an activated carbon tower, treatment by a fluidized bed using granular activated carbon, and the like. . However, it is not necessarily limited to these.

  When passing the treated water through the activated carbon device 34, a pH adjuster such as caustic soda is injected into the treated water discharge line 26 to neutralize the treated water or the pH of the treated water in the range of 5.5 to 7.5. It is preferable to adjust to the point that the life of the activated carbon can be extended. Moreover, it is preferable that the superficial velocity at the time of water flow to the activated carbon device 34 is in a range of 1 to 20 (1 / hr).

  Furthermore, it is more preferable to reduce the remaining persulfate by injecting a reducing agent such as sodium sulfite, sodium thiosulfate, and hydrogen peroxide into the treated water discharge line 26 in terms of extending the life of the activated carbon.

  The aromatic chlorine compound to be treated in the present embodiment is not particularly limited as long as it is a compound in which the hydrogen atom of the aromatic compound is replaced with a chlorine atom. For example, PCB, dioxins, TCB, etc. Can be mentioned.

  As the persulfate used in the present embodiment, potassium persulfate or sodium persulfate can be preferably used, but is not limited thereto. Moreover, although the citric acid used for this embodiment can use a citric acid or sodium citrate suitably, it is not limited to these. As the iron salt used in the present embodiment, divalent iron, trivalent iron, iron chloride, iron sulfate, or the like can be preferably used, but is not limited thereto.

  The chelated iron used in the present embodiment includes organic acid irons such as EDTA-iron, iron citrate, and iron gluconate. Among them, iron citrate is more preferable from the viewpoint of cost, decomposition effect, and handling. .

  The treatment method of this embodiment is suitably used for treatment of contaminants such as water, drainage, soil, sediment, sludge, and groundwater contaminated with aromatic chlorine compounds. An example is described below.

  FIG. 4 is a schematic diagram showing an example of the configuration of an aromatic chlorine compound processing system according to another embodiment of the present invention. As shown in FIG. 4, the aromatic chlorine compound processing system 4 includes a persulfate addition means including a first pump 36 and a persulfate supply line 38, a persulfate tank 40, a second pump 42 and a chelate. A chelated iron addition means including an iron supply line 44, a chelated iron tank 46, a line mixer 48, an injection line 50, an injection well 52, a third pump 54, a pumping line 56, a pumping well 58, and a pumping tank 60 are provided. A pumping means, a fourth pump 62, a fifth pump 64, pipes 66a and 66b, and an activated carbon device 34 are provided.

  The persulfate tank 40 and the line mixer 48 are connected by a persulfate supply line 38, and the chelate iron tank 46 and the line mixer 48 are connected by a chelate iron supply line 44. The persulfate supply line 38 is provided with a first pump 36, and the chelate iron supply line 44 is provided with a second pump 42. One end of the injection line 50 is connected to the line mixer 48, and the other end is disposed in the injection well 52.

  The persulfate and the chelate iron are supplied from the persulfate addition means and the chelate iron addition means via the line mixer 48 and the injection line 50 to the soil or groundwater contaminated with the aromatic compound. However, the line mixer 48 and the injection line 50 are not necessarily required. For example, the persulfate supply line 38 and the chelate iron supply line 44 are installed in the injection well 52, and the persulfate supply line 38 and the chelate iron supply line 44 are installed. Persulfate and chelated iron may be supplied directly to the soil and groundwater.

  The pumping means pumps ground water after purification treatment to the surface. Here, the pumping well 58 constituting the pumping means needs to be disposed at least downstream of the groundwater from the injection well 52 in order to pump up the groundwater after the purification treatment. A third pump 54 is provided in the pumping line 56 disposed in the pumping well 58. The pumping line 56 is connected to the pumping tank 60.

  The pumping tank 60 and the activated carbon device 34 are connected by a pipe 66a, and a fourth pump 62 is provided in the pipe 66a. The activated carbon device 34 and the line mixer 48 are connected by a pipe 66b, and a fifth pump 64 is provided in the pipe 66b.

  Hereinafter, a method for treating soil and groundwater contaminated with an aromatic chlorine compound according to the present embodiment will be described.

  The first pump 36 converts the persulfate in the persulfate tank 40 from the persulfate supply line 38 to the line mixer 48, and the second pump 42 converts the chelate iron in the chelate iron tank 46 into the chelate iron supply line. 44 to the line mixer 48. After the persulfate and the chelated iron are mixed by the line mixer 48, the mixture is supplied from the injection line 50 to the soil and groundwater contaminated with the aromatic chlorine compound through the injection well 52. Then, while the groundwater to which persulfate and chelated iron are added flows through the contaminated area X, the aromatic chlorine compound existing in the contaminated area X is decomposed.

  Next, the groundwater purified by the addition of persulfate and chelated iron is fed from the pumping line 56 to the pumping tank 60 by the third pump 54. When the water in the pumping tank 60 is supplied again to the groundwater contaminated with the aromatic chlorine compound, the fourth pump 62 and the fifth pump 64 are operated, and the groundwater in the pumping tank 60 is supplied by the activated carbon device 34. It is preferable to treat the activated carbon to remove the remaining aromatic chlorine compound. Then, the treated water treated with the activated carbon device 34 is supplied from the pipe 66b to the line mixer 48, and is supplied again to the original position of the soil and groundwater. Moreover, when discharging the water in the pumping tank 60 to the ground surface, it is preferable to perform activated carbon treatment with the activated carbon device 34 to remove the remaining aromatic chlorine compound and persulfate.

  In this embodiment, in the purification of groundwater and soil contaminated with aromatic chlorine compounds, the concentration of persulfate in the contaminated area X is not particularly limited, but for example, at least 10 times the concentration of aromatic chlorine compounds. It is preferable to inject the persulfate so as to be above, and it is more preferable to inject the persulfate so as to be in the range of 500 to 50000 mg / L, and further in the range of 500 mg / L to 20000 mg / L. It is more preferable to inject the persulfate as described above, and it is more preferable to inject the persulfate so as to be in the range of 500 to 10,000 mg / L. When the persulfate concentration is less than 500 mg / L, the persulfate is consumed due to the influence of organic substances and inorganic ions present in the soil and groundwater, so that it is difficult to sufficiently decompose the aromatic chlorine compound. On the other hand, if the persulfate concentration exceeds 50000 mg / L, the amount of chemicals used increases and the cost increases.

  Further, in purification of groundwater and soil contaminated with aromatic chlorine compounds, the pH of the contaminated area X is changed from weakly acidic to alkaline (pH 5) rather than making the pH of the contaminated area X acidic (for example, in the range of 2 to 5). It is preferable to be more than 10). When the pH of the contaminated area X is 5 or less, elution of heavy metals from the soil may occur. In addition, the impact on the ecosystem will increase. For these reasons, by changing the pH of the contaminated area X from weakly acidic to alkaline (pH 5 to 10), when purifying the pollution under the building or in areas where lakes and ponds exist around the purification area Can be applied. And it is the knowledge obtained for the first time by this inventor that an aromatic chlorine compound can be processed also in alkaline conditions when adding a persulfate and chelate iron and decomposing | disassembling an aromatic chlorine compound.

  Usually, since the pH of the contaminated area X may be acidic due to sulfuric acid generated by the decomposition of persulfuric acid, an alkaline agent is supplied to the soil and groundwater contaminated with the aromatic chlorine compound, and the contaminated area X It is preferable to adjust the pH of X from weakly acidic to an alkaline region (pH above 5 to 10). FIG. 5 is a schematic diagram showing an example of a configuration of an aromatic chlorine compound treatment system according to another embodiment of the present invention. In the aromatic chlorine compound treatment system 5 shown in FIG. 5, the same components as those in the aromatic compound treatment system 4 shown in FIG. The aromatic chlorine compound treatment system 5 shown in FIG. 5 includes an alkaline agent supply means for supplying an alkaline agent and an alkaline agent tank 68 to the soil and groundwater contaminated with the aromatic chlorine compound. The alkaline agent supply means includes a sixth pump 70 and an alkaline agent addition line 72.

  The alkaline agent is added by the alkaline agent addition means so that the pH of the contaminated region X is in the range from weakly acidic to alkaline (pH 5 to 10). Here, it is preferable to provide pH monitoring means such as a pH meter for monitoring the pH of the contaminated region X, and adjust the amount of alkali agent added by the alkali agent addition means based on the monitored pH value. The monitoring of the pH of the contaminated area X is performed, for example, by installing a pH meter in the pumping line 56 or the pumping well 58 and measuring the pH of groundwater passing through the pumping line 56 (or accumulating in the pumping well 58). This is done by monitoring the pH of the contaminated area X.

  The above-described embodiment is an example, and for example, pollutants such as water, drainage, soil, sediment, sludge, and groundwater contaminated with organic pollutants proposed by the present inventors are oxidized in situ. A method of kneading with an agent (see Japanese Patent Application Laid-Open No. 2007-105556), excavating contaminants such as water, drainage, soil, sediment, sludge, and groundwater contaminated with organic contaminants, and kneading with an oxidant on the ground An aromatic chlorine compound can be decomposed using a method (see Japanese Patent No. 3784654, Japanese Patent Laid-Open No. 2003-71425, or Japanese Patent Laid-Open No. 2002-326080). An example is described below.

  FIG. 6 is a schematic diagram showing an example of a configuration of an aromatic chlorine compound purification system according to another embodiment of the present invention. The aromatic chlorine compound purification system 6 shown in FIG. 6 includes a base machine 74 (a machine in which a driven member can be replaced), a rotary shaft 78 having a rotary stirring blade 76 at the bottom, and a rotary shaft 78. Rotation drive source 80 for driving, persulfate supply means including a persulfate supply line 82 and a first pump 84, chelate iron supply means including a persulfate tank 86, a chelate iron supply line 88 and a second pump 90, and a chelate An iron tank 92 is provided.

  The persulfate and the chelate iron are supplied to the upper portion of the rotating shaft 78 from the persulfate supply line 82 and the chelate iron supply line 88 by the first pump 84 and the second pump 90. The rotary shaft 78 has a hollow structure or a double-pipe structure, transfers persulfate and chelate iron supplied to the upper part of the rotary shaft 78, and injects the contaminated soil and groundwater from the opening provided in the lower part. , And can be directly kneaded with contaminants and purification chemicals.

  Also by such a method, it is possible to purify groundwater, soil, etc. contaminated with aromatic chlorine compounds. If the contaminated area is shallow with organic pollutants, excavate the contaminated soil etc. by the method of purifying the contaminated soil etc. It is preferable to purify by adding and kneading chelated iron.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

Example 1
A decomposition test of 1,3,5-trichlorobenzene (TCB) was performed. In Example 1, groundwater containing TCB at a concentration of 0.1 mg / L was added to sodium persulfate at a concentration of 10000 mg / L, citric acid at a concentration of 1376 mg / L and iron sulfate heptahydrate at 996 mg / L (as divalent iron). 200 mg / L) was added iron citrate prepared by mixing. The initial pH in the TCB decomposition reaction was 7.8, and the final pH was 1.5. And 120 hours after the reaction start, the TCB density | concentration in waste_water | drain was measured by GC-MS. In addition, the water temperature in a decomposition test was implemented in the range of 15-20 degreeC.

(Example 2)
In Example 2, groundwater containing TCB at a concentration of 0.1 mg / L was added to sodium persulfate at a concentration of 10,000 mg / L, citric acid at a concentration of 1376 mg / L and iron sulfate heptahydrate at 996 mg / L (as divalent iron). 200 mg / L) was added iron citrate prepared by mixing. Further, sodium hydroxide having a molar ratio of 0.5 to persulfuric acid was added. The initial pH in the TCB decomposition reaction was 12.4 and the final pH was 7.8. And 120 hours after the reaction start, the TCB density | concentration in waste_water | drain was measured by GC-MS. In addition, the water temperature in a decomposition test was implemented in the range of 15-20 degreeC.

(Comparative Example 1)
In Comparative Example 1, groundwater containing TCB with a concentration of 0.1 mg / L was left for 120 hours, and then the TCB concentration in the wastewater was measured by GC-MS.

(Comparative Example 2)
In Comparative Example 2, sodium persulfate having a concentration of 10,000 mg / L was added to groundwater containing TCB having a concentration of 0.1 mg / L, and the TCB concentration in the wastewater was measured by GC-MS 120 hours after the start of the reaction.

  Table 1 summarizes the TCB concentrations of Examples 1 and 2 and Comparative Examples 1 and 2. As can be seen from Table 1, in Examples 1 and 2 in which sodium persulfate and iron citrate were added to TCB-containing water, the decomposition efficiency of TCB was improved compared to Comparative Example 2 in which only sodium persulfate was added. did it. Moreover, Example 2 which added sodium hydroxide and adjusted pH showed the decomposition efficiency similar to Example 1 without sodium hydroxide addition. Thereby, it was confirmed that the treatment method can be suitably used even in actual contaminated groundwater and soil, which are preferably treated with weak alkali to weak alkali in terms of suppression of elution of heavy metals.

(Example 3)
Hereinafter, a PCB decomposition test was performed. In Example 3, water containing PCB at a concentration of 0.01 mg / L, sodium persulfate at a concentration of 10000 mg / L, citric acid at a concentration of 1376 mg / L, and 996 mg / L of iron sulfate heptahydrate (as divalent iron) 200 mg / L) was added iron citrate prepared by mixing. The initial pH in the PCB decomposition reaction was 7.8, and the final pH was 1.5. Then, 2 hours, 24 hours and 168 hours after the start of the reaction, the PCB concentration in the waste water was measured by GC-MS. In addition, the water temperature in a decomposition test was implemented in the range of 15-20 degreeC.

Example 4
In Example 4, in water containing 0.01 mg / L PCB, sodium persulfate at a concentration of 10000 mg / L, citric acid at a concentration of 1376 mg / L and iron sulfate heptahydrate at 996 mg / L (as divalent iron) 200 mg / L) was added iron citrate prepared by mixing. Further, sodium hydroxide having a molar ratio of 0.5 to persulfuric acid was added. The initial pH in the PCB decomposition reaction was 12.4 and the final pH was 7.8. Then, 2 hours, 24 hours and 168 hours after the start of the reaction, the PCB concentration in the waste water was measured by GC-MS. In addition, the water temperature in a decomposition test was implemented in the range of 15-20 degreeC.

(Comparative Example 3)
In Comparative Example 3, water containing PCB having a concentration of 0.01 mg / L was allowed to stand for 168 hours, and then the PCB concentration in the water was measured by GC-MS.

  Table 2 summarizes the PCB concentrations of Examples 3 and 4 and Comparative Example 3. Conventionally, in the decomposition of PCB, which was difficult at normal temperature and normal pressure, in Examples 3 and 4 in which sodium persulfate and iron citrate were added to water containing PCB, it was confirmed that PCB could be treated by 90%. Moreover, Example 3 which added sodium hydroxide and adjusted pH showed the decomposition efficiency similar to Example 4 which does not add sodium hydroxide. Thereby, it was confirmed that the treatment method can be suitably used even in actual contaminated groundwater and soil, which are preferably treated with weak alkali to weak alkali in terms of suppression of elution of heavy metals.

  1 to 3 treatment devices, 4, 5 treatment systems, 6 purification systems, 10 decomposition reaction tanks, 12, 36, 84 first pumps, 14, 38, 82 persulfate supply lines, 16, 40, 86 persulfate tanks 18, 42, 90 Second pump, 20, 44, 88 Chelated iron supply line, 22, 46, 92 Chelated iron tank, 24 treated water inflow line, 26, 27 treated water discharge line, 28 production reaction tank, 30 Citric acid supply line, 32 Iron salt supply line, 34 Activated carbon device, 48 Line mixer, 50 Injection line, 52 Injection well, 54 3rd pump, 56 Pumping line, 58 Pumping well, 60 Pumping tank, 62 4th pump, 64 5th pump, 66a, 66b piping, 68 alkaline agent tank, 70 6th pump, 72 alkaline agent addition line, 74 bases Machine, 76 rotary stirring blades, 78 rotary shaft, 80 a rotary drive source.

Claims (10)

  A method for treating an aromatic chlorine compound, comprising adding persulfate and chelated iron to an aromatic chlorine compound to decompose the aromatic chlorine compound.   The method for treating an aromatic chlorine compound according to claim 1, wherein the chelated iron is an organic acid iron.   The method for treating an aromatic chlorine compound according to claim 2, wherein the organic acid iron is iron citrate, and the organic acid iron is prepared by mixing citric acid and an iron salt.   The method for treating an aromatic chlorine compound according to any one of claims 1 to 3, wherein a pH at the time of decomposing the aromatic chlorine compound is set to an alkaline condition. A decomposition reaction tank for adding persulfate and chelating iron to the aromatic chlorine compound to decompose the aromatic chlorine compound;
Persulfate addition means for adding the persulfate to the decomposition reaction tank;
An apparatus for treating an aromatic chlorine compound, comprising: chelate iron addition means for adding the chelate iron to the decomposition reaction tank.   6. The apparatus for treating an aromatic chlorine compound according to claim 5, wherein the chelated iron is an organic acid iron.   The said organic acid iron is iron citrate, The citric acid and iron salt are mixed, The production | generation reaction tank for producing | generating the said iron citrate is provided, The aromatic chlorine compound of Claim 6 characterized by the above-mentioned. Processing equipment.   A method for treating an aromatic chlorine compound, comprising adding persulfate and chelated iron to soil and groundwater contaminated with an aromatic chlorine compound to decompose the aromatic chlorine compound.   The method for treating an aromatic chlorine compound according to claim 8, wherein the persulfate and the chelated iron are added to the soil and groundwater contaminated with the aromatic chlorine compound.   The method for treating an aromatic chlorine compound according to claim 8 or 9, wherein the pH at the time of decomposing the aromatic chlorine compound is set to an alkaline condition.

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