JP3628478B2 - Organochlorine compound decomposition equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for decomposing organochlorine compounds, and more specifically, after dechlorinating organochlorine compounds such as polychlorinated biphenyl contained in electrical insulating oil, heat medium, organic drainage, etc. The present invention relates to a method for treating a reaction product to be processed and an apparatus used for the method.
[0002]
[Prior art and problems to be solved by the invention]
As is well known, polychlorinated biphenyl is very stable and difficult to be decomposed and has high insulation (electrical resistance). Therefore, it has been used in insulating materials such as transformers and capacitors, heat media, carbonless copying paper, etc. It has been used but is now prohibited for environmental reasons.
[0003]
However, it has been used for a long time, and in addition to the material itself, it may still remain as a trace component in organic drainage and wastewater, and how to disassemble and treat them is an important issue. It has become.
[0004]
As a means of decomposing and treating such polychlorinated biphenyls, incineration is generally used in many cases, and the incineration law is recognized as the only treatment method by law. May cause other harmful substances such as the like, and it is not always sufficient from the viewpoint of environmental destruction and safety, and at present, materials and wastes containing this compound are not processed.
[0005]
Therefore, as another means for solving this, for example, a method of decomposing and treating polychlorinated biphenyl by reacting with alkali metal carbonate or hydroxide such as sodium carbonate or sodium hydroxide and polyethylene glycol, or sodium metal In addition, chemical means such as a method of decomposing and treating polychlorinated biphenyl by reacting butoxy alcohol has been developed, but it remains within the scope of the dechlorination reaction control method from polychlorinated biphenyl.
[0006]
According to these chemical means, the purpose of decomposition and treatment of polychlorinated biphenyl can be achieved, but by-products such as biphenyl newly produced by dechlorination of polychlorinated biphenyl are themselves toxic substances. This remains undesired per se, and has not been established as an original complete detoxification method.
[0007]
The present invention has been made to solve such problems, and can achieve the object of dechlorination treatment of polychlorinated biphenyl, and can be achieved even after the dechlorination treatment of polychlorinated biphenyl. It is an object to provide a decomposition method that does not generate or generate toxic substances.
[0008]
[Means for Solving the Problems]
The present invention has been made in order to solve such problems . The feature of the present invention is that a reaction tank 1 for reacting polychlorinated biphenyl with an alkali metal, an alkaline earth metal, or an alkali metal or alkaline earth metal compound. And a biological treatment device 11 for biologically decomposing the reaction product produced in the reaction tank 1, and polychlorinated biphenyl, alkali metal, alkaline earth metal, or alkali contained in the insulating oil An extraction tank 4 is provided between the reaction tank 1 and the biological treatment apparatus 11 for separating and extracting the reaction product produced by the reaction with the metal or alkaline earth metal compound from the insulating oil. and it is that it is.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
FIG. 1: shows the schematic side view of the decomposition | disassembly apparatus of the organochlorine compound as one Embodiment.
[0012]
In FIG. 1, 1 is a batch-type reaction tank for reacting polychlorinated biphenyl with metallic sodium, and a stirrer 2 is provided inside.
[0013]
3 shows a sodium storage tank for storing metallic sodium to be supplied to the reaction tank 1.
[0014]
4 is an extraction tank for separating reaction products such as biphenyl and sodium chloride produced by the reaction between polychlorinated biphenyl and metallic sodium from the insulating oil, and a stirrer 5 is provided inside.
[0015]
Reference numeral 6 denotes a pH adjusting tank for adjusting the pH of an aqueous solution of by-products such as biphenyl extracted from the extraction tank 4 and sodium chloride, and a stirrer 7 is provided therein.
[0016]
Reference numeral 8 denotes a centrifugal separator for further separating the insulating oil from the extraction tank 4. The insulating oil separated by the centrifugal separator 8 is reused, and the secondary oil such as biphenyl separated by the centrifugal separator 8 is reused. An aqueous solution of the product and sodium chloride is supplied to the pH adjustment tank 6.
[0017]
If polychlorinated biphenyl is contained in the insulating oil separated by the centrifugal separator 8, the concentration of the polychlorinated biphenyl is detected by the analyzer 21, and the polychlorinated biphenyl recovery step 18 is performed. After being returned and concentrated by the separation membrane 19, it is supplied to the reaction vessel 1 again. The separation membrane 19 may be a method such as solvent extraction.
[0018]
Reference numeral 9 denotes a centrifugal separator for further separating the insulating oil remaining in the pH adjusting tank 6. The insulating oil separated by the centrifugal separator 9 is supplied to the centrifugal separator 8 and centrifuged. The aqueous solution of by-products such as biphenyl and sodium chloride separated by the apparatus 9 is supplied to the biological treatment process which is the next process.
[0019]
Reference numeral 10 denotes a storage tank for storing an aqueous solution of a by-product such as biphenyl and sodium chloride separated by the centrifugal separator 9, and 11 denotes a decomposition of a by-product such as biphenyl supplied from the storage tank 10. In the biological treatment apparatus for processing, an aeration tube 12 is provided so as to enable aeration and stirring.
[0020]
13 is a concentrating device for separating and concentrating the product decomposed by the biological treatment apparatus 11 and the by-products such as biphenyl and sodium chloride which have not been decomposed, and concentrated, such as an electrodialysis membrane and an ion exchange membrane. It is constituted by.
[0021]
The decomposed compound is discharged as treated water, and byproducts such as biphenyl that have not been decomposed are separated and returned to the extraction tank 4.
[0022]
Next, a method for decomposing an organic chlorine compound using the organic chlorine compound decomposing apparatus having the above-described configuration will be described.
[0023]
The method for decomposing the organochlorine compound of the present embodiment includes a polychlorinated biphenyl dechlorination step as shown in FIG. 2, a by-product such as biphenyl and sodium chloride separation step as shown in FIG. The biodegradation process as shown in FIG.
[0024]
In the polychlorinated biphenyl decomposition step, first, a liquid to be treated containing polychlorinated biphenyl and insulating oil is supplied to the reaction tank 1.
[0025]
When supplying the liquid to be treated, it is possible to concentrate polychlorinated biphenyl in advance using a separation membrane, and the separated and concentrated polychlorinated biphenyl is mixed with the stock solution again.
[0026]
Next, sodium metal is supplied from the sodium reservoir 3 to the reaction tank 1 to react the polychlorinated biphenyl with sodium.
[0027]
In this case, in order to improve reaction efficiency, the inside of the reaction tank 1 is stirred with the stirrer 2.
[0028]
This reaction between polychlorinated biphenyl and sodium produces organic by-products such as biphenyl and sodium chloride.
[0029]
A liquid to be treated containing an organic by-product such as biphenyl and sodium chloride produced in the reaction tank 1 is supplied to the separation and recovery process, which is the next process, but is not reacted in the supplied liquid to be treated. If polychlorinated biphenyl remains, it is detected by the analyzer 14 and returned to the reaction vessel 1 again to react with sodium chloride.
[0030]
When polychlorinated biphenyl is not detected by the analyzer 14, the liquid to be treated containing organic by-products such as biphenyl and sodium chloride generated in the reaction tank 1 is supplied to the extraction tank 4 in the next step. Water is supplied from the water storage tank 15 to the extraction tank 4.
[0031]
The inside of the extraction tank 4 is stirred by a stirrer 5 to extract sodium chloride into water. The insulating oil is separated from the aqueous solution and reused.
[0032]
The extracted and separated biphenyl, organic by-product and sodium chloride are supplied to the pH adjustment tank 6, and hydrochloric acid is supplied from the hydrochloric acid storage tank 16 to the pH adjustment tank 6 to adjust the pH.
[0033]
The inside of the pH adjusting tank 6 is also stirred by the stirrer 7.
[0034]
As described above, the insulating oil separated from the extraction tank 4 is centrifuged by the centrifugal separator 8 before being reused, and the separated insulating oil is reused and contained in a trace amount. An aqueous solution of organic by-products such as biphenyl and sodium chloride is supplied to the pH adjustment tank 6.
[0035]
The liquid to be treated whose pH has been adjusted in the pH adjusting tank 6 is centrifuged by another centrifugal separator 9, and the remaining insulating oil is supplied to the centrifugal separator 8, where it is centrifuged again.
[0036]
On the other hand, the liquid to be treated containing organic by-products such as biphenyl and sodium chloride separated by the centrifugal separator 9 is supplied to the biological treatment process which is the next process. If unreacted polychlorinated biphenyl remains, it is detected by the analyzer 17 and returned to the polychlorinated biphenyl concentration step 18, and the insulating oil is separated by the separation membrane 19. Supplied.
[0037]
When polychlorinated biphenyl is not detected by the analyzer 17, the liquid to be treated containing by-products such as biphenyl produced in the reaction tank 1 and sodium chloride is supplied to the storage tank 10 in the next biological treatment process. The
[0038]
Next, a liquid to be treated containing a by-product such as biphenyl and sodium chloride is supplied from the storage tank 10 to the biological treatment apparatus 11.
[0039]
In the biological treatment apparatus 11, organic by-products such as biphenyl are decomposed by microorganisms.
[0040]
In this case, aeration and agitation are performed by supplying air from the air diffuser 12.
[0041]
The biologically-treated liquid to be treated is separated by the concentrating device 13, and byproducts such as biphenyl and sodium chloride that have not been decomposed are separated and returned to the extraction tank 4 in the separation and recovery step.
[0042]
If the treated water to be discharged contains polychlorinated biphenyl, it is detected by the analyzer 20 and returned to the polychlorinated biphenyl concentration step.
[0043]
In the present embodiment, in the treatment process as described above, the reaction rate of metallic sodium in the reaction vessel 1 was 95%, and no polychlorinated biphenyl was detected after the reaction.
[0044]
The concentration of the polychlorinated biphenyl in the stock solution supplied into the reaction vessel 1 was 1000 ppm.
[0045]
On the other hand, the BOD of the treated water to be discharged was 10 ppm.
[0046]
Further, the treated water did not contain other water quality control substances.
[0047]
In the above embodiment, sodium is used as a substance to be reacted with polychlorinated biphenyl. However, the present invention is not limited to this, and other alkaline metals such as potassium and rubidium, and alkaline earth metals such as calcium, strontium and magnesium are used. It is also possible to use these, and it is also possible to use these alkali metal and alkaline earth metal compounds, and also mixtures thereof.
In some cases, a hydrogen donor is added to promote the reaction efficiently. However, when naphthalene is added as a hydrogen donor, a biphenyl derivative such as naphthylbiphenyl may be produced.
[0048]
For example, when potassium is used, an organic by-product such as biphenyl and potassium chloride are produced by reaction with polychlorinated biphenyl.
[0049]
Further, the biological treatment means is not limited to the means using the fixed bed type biological treatment apparatus 11 as in the above embodiment. For example, it is possible to use the activated sludge method or the like. It is also possible to use these means.
[0050]
In this case, for example, a floating carrier made of synthetic resin can be suspended in the biological treatment apparatus, and the microorganism can be supported on the carrier.
[0051]
Furthermore, in the above embodiment, the means by centrifugal separation is used as the means for separating the insulating oil, but it is also possible to separate by means of membrane separation or electrophoretic separation means in addition to the centrifugal separation.
[0052]
Furthermore, in the above embodiment, since the pH adjustment tank 6 is provided, there is an advantage that the pH of the liquid to be treated after the extraction and separation can be suitably adjusted so as not to incline to the alkali side. Providing the tank 6 is not an essential condition for the present invention.
[0053]
In addition, analyzers 14, 17, 20, and 21 for detecting the concentration of the remaining polychlorinated biphenyl are provided in the polychlorinated biphenyl decomposition step, the separation and recovery step of the reaction by-products such as biphenyl, and the biodegradation treatment step, respectively. This is not necessarily an essential condition for the present invention, but it is desirable to provide at least one analyzer for continuous monitoring.
[0054]
Furthermore, the type of liquid to be treated is not limited to waste water, but also an insulating oil containing polychlorinated biphenyl, a heat medium, a polychlorinated biphenyl-containing liquid extracted from a polychlorinated biphenyl-containing material, etc. In short, what is necessary is just to include polychlorinated biphenyl.
[0055]
【The invention's effect】
As described above, the present invention reacts an alkali metal with polychlorinated biphenyl to produce biphenyl, and then decomposes the biphenyl by biological treatment.
In addition to being able to achieve the original purpose of polychlorinated biphenyl decomposition treatment, organic by-products such as biphenyl, which has been a problem with conventional chemical decomposition methods, can also be suitably decomposed. effective.
[0056]
Accordingly, the toxicity of the liquid after treatment can be remarkably reduced and made virtually harmless.
[0057]
Moreover, unlike incineration generally performed, there is no possibility of generating another harmful substance such as dioxin, which is preferable from the viewpoint of environmental destruction and safety.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing an entire organochlorine compound decomposition treatment apparatus according to an embodiment.
FIG. 2 is a schematic side view showing a dechlorination step of polychlorinated biphenyl in a decomposition treatment apparatus.
FIG. 3 is a schematic side view of a separation processing step.
FIG. 4 is a schematic side view of a biodegradation process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reaction tank 4 ... Extraction tank 6 ... pH adjustment tank 11 ... Biological treatment apparatus

Claims (2)

A reaction vessel (1) for reacting polychlorinated biphenyl with an alkali metal, alkaline earth metal, or an alkali metal or alkaline earth metal compound, and biologically decomposing the reaction product produced in the reaction vessel (1) The reaction produced by the reaction of polychlorinated biphenyl contained in the insulating oil and the alkali metal, alkaline earth metal, or alkali metal or alkaline earth metal compound Organochlorine compound characterized in that an extraction tank (4) for separating and extracting the product from the insulating oil is provided between the reaction tank (1) and the biological treatment apparatus (11) . Disassembly equipment. A pH adjustment tank (6) for adjusting the pH of the liquid to be treated containing the reaction product extracted and separated in the extraction tank (4) is provided between the extraction tank (4) and the biological treatment apparatus (11). and partial dismantlement location according to claim 1 organochlorine compound according has.

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