JP2004298671A - Purification device and purification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purification method capable of treating the PCBs contained in soil and waste water at a low cost in simple manner and achieving PCB emission regulation and to provide a purification device. <P>SOLUTION: The purification device is equipped with a solid introducing section 8 which introduces solids larger than the molecules of the PCBs into the waste water 30 containing the PCBs and a filtering device 3 which has a filter medium of a bore diameter greater than the molecules of the PCBs and smaller than the solids and filters the waste water containing the PCBs. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technology for purifying wastewater, and more particularly to a device and a method for purifying wastewater containing PCB.
[0002]
[Prior art]
In recent years, water pollution by harmful substances has become a serious problem. Examples of contaminants include cadmium, total cyanide, next to organic, lead, hexavalent chromium, arsenic, total mercury, alkylmercury, PCB (polychlorinated biphenyl), copper, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, tetrachloroethylene, 1,3-dichloropropene, thiuram, simazine, thiobencarb, benzene, dioxin And oil.
[0003]
Among the harmful substances, especially PCB (general formula C ₁₂ H _10-n Cl _n ) Are compounds that have been banned from production and use in 1972 because they are hardly degradable, have bioaccumulation properties (high accumulation properties), and may cause serious damage to the human body or the global environment. For this reason, businesses rarely manufacture or use PCBs at present. It is unlikely to flow into rivers and soil as factory wastewater. However, in the past, since it was widely used as an insulating oil, a heating medium, and a plasticizer, PCBs are still present in soil and wastewater. As means for treating such PCBs, there is a means for treating activated paper wastewater containing, for example, about 100 mg / l of PCB with activated sludge and further re-coagulating. There is also a method of oxidatively decomposing PCB by bringing soil into contact with a catalyst (for example, see Patent Document 1). There is also a method in which high-calorie waste is added to soil and incinerated (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-7-328595
[0005]
[Patent Document 2]
JP-A-11-148631
[0006]
[Problems to be solved by the invention]
However, in the above-described method of coagulating soil containing PCB, there are cases where the PCB cannot be sufficiently removed. In the method of re-coagulating and treating the recycled wastewater containing PCBs after the activated sludge treatment, it is possible to remove about 90% of the PCBs, but it was not possible to suppress the PCB wastewater to 0.003 mg / l or less. . In addition, the method of oxidizing PCB by contacting the soil with a catalyst or the method of burning the soil requires high caloric energy, which is expensive. The incomplete thermal oxidation treatment and incineration treatment may release highly toxic coplanar PCB into the atmosphere.
[0007]
The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and it is an object of the present invention to be able to easily and inexpensively treat PCBs contained in soil and wastewater and to achieve the PCB emission standards. It is an object of the present invention to provide a purifying device and a purifying method that are possible.
[0008]
[Means for Solving the Problems]
The first invention has a solid substance introduction portion for introducing a solid substance larger than PCB molecules into wastewater containing PCB, and a filter medium having a pore size larger than the PCB molecules and smaller than the solid substance. And a filtration device for filtering wastewater. According to the first invention, the solid matter is introduced into the wastewater containing PCB by the solid matter introduction part, and the PCB in the wastewater is adsorbed on the solid matter. Then, the solid matter on which the PCB is adsorbed is collected by a filtration device having a filtration material having a pore size larger than that of the PCB molecule. Further, even if the PCB is not adsorbed on the solid material, the PCB can be removed by passing through the flow path inside the solid deposit layer formed on the surface of the filter material when the PCB permeates the filter material. In addition, it is possible to provide a purification device that can easily and safely remove PCB using a filtering material having a pore size larger than that of PCB molecules.
[0009]
A second invention is a PCB extraction unit for extracting gas containing PCB from soil, an exhaust gas heating unit for heating gas, an exhaust gas cleaning device for cleaning gas passing through the exhaust gas heating unit with a cleaning liquid, and a cleaning liquid. A purifying apparatus comprising: a solid substance introduction part for introducing a solid substance having a particle diameter larger than the molecule of PCB; a filtration device having a filter material having a pore size larger than the molecule of PCB and smaller than the solid substance; It is. According to the second invention, the PCB-containing soil is heated in the PCB extraction unit, and the PCB-containing gas is extracted. The gas containing PCB is further heated in the exhaust gas heating section, whereby the tar component contained in the gas is removed. The gas containing PCB that has passed through the exhaust gas heating unit is cleaned by the cleaning liquid in the exhaust gas cleaning device, and the PCB components move into the cleaning liquid. The washing liquid containing PCB is added with solid matter in the solid matter introduction part, and is introduced into the filtration device. In the cleaning solution containing PCB introduced into the filtration device, solid substances are collected by the filtering material having a pore diameter larger than that of PCB molecules, and the PCB is removed. Therefore, according to the second feature, it is possible to provide a purifying device that can easily and safely remove the PCB.
[0010]
The third invention is a purification method of removing wastewater from PCB by filtering wastewater containing PCB and solid matter through a filter medium having a pore size larger than the molecule of PCB and smaller than the particle diameter of the solid matter. . According to the third aspect, the solid matter in the wastewater is collected by the filter medium having a pore size larger than the molecules of the PCB and smaller than the particle diameter of the solid matter. Since the PCB contained in the wastewater is adsorbed to the solid matter, the PCB can be easily and safely removed with a filter medium having a pore size larger than that of the PCB molecule.
[0011]
According to a fourth aspect, a step of extracting a gas containing PCB from soil, a step of heating the gas containing PCB, a step of washing the heated gas containing PCB with a cleaning liquid, A purification method comprising the steps of: introducing a solid having a large particle diameter; and filtering the cleaning liquid through a filter medium having a pore size larger than the molecules of the PCB and smaller than the particle diameter of the solid substance, and removing the PCB from the cleaning liquid. . According to the fourth invention, a gas containing PCB obtained by heating a soil containing PCB is washed with a washing solution, and the washing solution is filtered with a pore size larger than the molecule of the PCB and smaller than the particle size of the solid matter. By filtering through the material, the PCB can be easily and safely removed from the soil.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, first and second embodiments of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic and different from actual ones. In addition, it is needless to say that the drawings include portions having different dimensional relationships and ratios. The first and second embodiments described below exemplify an apparatus and a method for embodying the technical idea of the present invention. The material, shape, structure, arrangement, etc. are not specified as follows. The technical concept of the present invention can be variously modified within the scope of the claims.
[0013]
(First Embodiment)
As shown in FIG. 1, the wastewater purification device 100 according to the first embodiment of the present invention includes a solid matter introduction unit 8 that introduces a solid matter larger than molecules of PCB into wastewater 30 containing PCB, A filter device that has a filter medium having a pore size larger than the molecule and smaller than the solid substance and that filters wastewater containing PCB. The sedimentation tank 1 is arranged in the solid matter introduction part 8. The sedimentation tank 1 is connected to the water storage tank 2 on the downstream side by a water tank introduction pipe 33 connected to the upper part of the sedimentation tank 1. The water storage tank 2 is connected to the downstream filtration device 3 by a filtration device introduction pipe 35 connected to the bottom of the water storage tank 2. The filtration device 3 is connected to the downstream treatment water tank 4 by a treatment water tank introduction pipe 37 connected to the outlet side of the filtration device 3. Further, a water tank return pipe 38 is connected to the outlet side of the filtration device 3, and is connected to the water tank 2. A filter washing pipe 39 is connected to the bottom of the treated water tank 4. As shown in FIG. 1, the filtration device washing pipe 39 is connected to the upstream side of the sixth valve 15 arranged in the treated water tank introduction pipe 37.
[0014]
A drain pipe 34 is connected to the bottom of the settling tank 1. The drain pipe 34 has a first valve 10 connected to a pipe 34 at the bottom of the settling tank 1, and a second valve 11 connected to the first valve 10 via the pipe 34. The filtration device introduction pipe 35 is connected to the third valve 12 connected to the pipe 35 at the bottom of the water storage tank 2, the first pump 23 connected to the third valve 12 via the pipe 35, and the pipe 35 to the first pump 23. A fourth valve 13 connected to the fourth valve 13 via a pipe 35; and a fifth valve 14 connected to the fourth valve 13 via a pipe 35. The filtration device supply pipe 36 has a tenth valve 19 connected to the settling tank return pipe 40 and an eleventh valve 20 connected to the tenth valve 19 via the pipe 36. The treated water tank introduction pipe 37 is connected to the second pressure gauge 27 connected to the pipe 37 on the outlet side of the filtration device 3, and connected to the pipe 37 on the outlet side of the filtration apparatus 3, and is disposed downstream of the second pressure gauge 27. A sixth valve 15, and a seventh valve 16 connected to the sixth valve 15 via a pipe 37. The water tank return pipe 38 is connected to the third pressure gauge 26 connected to the pipe 38 on the outlet side of the filtration device 3, and is connected to the pipe 38 on the outlet side of the filtration apparatus 3, and is arranged downstream of the third pressure gauge 26. An eighth valve 17, and a ninth valve 18 connected to the eighth valve 17 via a pipe 38. The filter washing pipe 39 is connected to the twelfth valve 21 connected to the pipe 39 at the bottom of the treated water tank 4, the second pump 24 connected to the twelfth valve 21 via the pipe 39, and the pipe 39 to the second pump 24. A thirteenth valve 22 connected via
[0015]
The sedimentation tank 1 is a water tank that sediments the sediment 31 of the introduced wastewater 30 to the bottom and obtains a supernatant. In the sedimentation tank 1, for example, water generated during purification work of soil contaminated with harmful substances, river water, pond water, groundwater, and wastewater from factories are introduced and stored. These waters include organic matter, rocks broken into fine particles, living bodies on the earth's surface, or decomposition products of living bodies. If organic matter or rocks are not contained in industrial wastewater or the like, natural minerals such as flocculants, river sand or soil-derived kaolinite, halosite, montmorillonite, allophane, imogolite, aluminum, and iron hydroxide are added in an amount of 0. It is preferable to add about 05 to 10000 mg / l. The addition amount of the natural mineral is more preferably about 1000 mg / l. The wastewater 30 from which the sediment 31 has been separated in the sedimentation tank 1 is introduced into the water tank 2 through the water tank introduction pipe 33.
[0016]
The water storage tank 2 is a water tank for temporarily storing the water separated in the settling tank 1. The wastewater 30 containing PCB stored in the water storage tank 2 is guided to the filtration device 3 through the third valve 12, the first pump 23, the fourth valve 13, and the fifth valve 14.
[0017]
The filtering device 3 filters the wastewater 30 containing PCB supplied from the water storage tank 2 using a filtering material. Examples of the filtering material include a microfiltration membrane (MF) that blocks particles and polymers larger than 0.1 μm, an ultrafiltration membrane (UF) that blocks particles and polymers in the range of 2 nm to 0.1 μm, A reverse osmosis membrane (RO) in which the solvent moves in the direction opposite to the osmotic pressure difference by pressurization is used. The constituent material and shape of the filtering material are not particularly limited. For example, resins, ceramics, and the like can be used as the material of the film. Examples of the structure of the membrane include, but are not particularly limited to, an internal pressure type tubular module, an external pressure type tubular module, a flat plate type module, a hollow fiber module, and a spiral module. As a filtration method other than the filtration membrane, for example, cake filtration in which solid particles in a liquid are deposited on a filtration material, or sand filtration in which sand is filled in an apparatus to have a filtration function may be used. In particular, when a membrane is used as a filtering material, the pore size is larger than that of a reverse osmosis membrane, the power consumption of the device is smaller than that of a reverse osmosis membrane, which requires pressurization and the unit cost of the membrane is high, and sieving is performed. It is preferred to use a microfiltration membrane or an ultrafiltration membrane that performs the separation. Therefore, the pore size of the filtering material used in the filtering device 3 is preferably about 2 nm to 10 μm.
[0018]
The treatment water tank 4 is a water tank for storing the drainage filtered by the filtration device 3. The wastewater introduced into the treated water tank 4 is the purified water 32 from which the PCB component has been removed, and may be directly discarded and drained outside. The purified water 32 in the treated water tank 4 can be used as a cleaning liquid for the filtration device 3. For example, when using the purified water 32 as a washing liquid for the filtration device 3, the first pump 23 of the filtration device introduction pipe 35 is stopped, the fifth valve 14 and the ninth valve 18 of the water tank return pipe 38 are closed, and the The twelfth valve 21, the thirteenth valve 22, the eleventh valve 20, the tenth valve 19, and the seventh valve 16 are opened. The purified water 32 flows backward through the treatment water tank introduction pipe 37 through the filtration apparatus supply pipe 39 and is introduced into the filtration apparatus 3. The purified water 32 introduced into the filtration device 3 flows back inside the filtration device 3 to remove solid matter deposited on the surface of the filter medium. Then, the purified water 32 containing the solid matter deposited on the surface of the filter medium is introduced into the filtration device supply pipe 36, and is again supplied to the settling tank 1 through the settling tank return pipe 40.
[0019]
According to the wastewater purification apparatus 100 according to the first embodiment of the present invention, in the sedimentation tank 1, a solid having a particle size of about 1 to 1000 μm is added to the wastewater 30 containing PCB, and the PCB in the wastewater 30 is solidified. Adsorbs on objects. If the water is from a river or soil that originally contains solids, the solids need not be added. The wastewater 30 containing the solid matter adsorbed by the PCB is introduced into the filtration device 3 via the water tank 2. The filtering material having a pore size larger than that of the PCB molecules provided in the filtering device 3 collects solid substances contained in the wastewater 30, thereby removing the PCB molecules of about 1 nm adsorbed on the solid substances from the wastewater 30. Remove.
[0020]
Since PCB molecules in wastewater generally exhibit the property of adsorbing solid matter in wastewater, the solid matter used is not particularly limited. However, since the adsorptivity differs depending on the solid matter, a substance with high PCB absorbability is used. Is preferred. In addition, also about the PCB which is not adsorbed by a solid substance, when the PCB permeate | transmits a filter medium, the wastewater 30 containing PCB passes through the flow path inside the solid deposit layer formed on the filter medium surface, about 1 nm. PCB molecules can be effectively removed. As described above, according to the wastewater purification apparatus 100 including the PCB illustrated in FIG. 1, the PCB, which is a fine molecule of about 1 nm, has a pore diameter larger than the molecule of the PCB, for example, about 1.2 to 1000 times larger. By using a filter material, PCBs contained in soil and wastewater can be easily removed. In addition, since the PCB is obtained by substituting 1 to 10 chlorine atoms in the biphenyl skeleton, the sizes of the molecules are different depending on the number and positions of the substituted bases. However, according to the PCB wastewater purification apparatus 100 shown in FIG. PCBs having a diameter of about 1 nm can be effectively removed. Further, the wastewater purifying apparatus 100 shown in FIG. 1 does not require high energy at the time of heating and pressurizing, so that the cost of treating wastewater including PCB can be reduced.
[0021]
Next, a method for purifying wastewater according to the first embodiment of the present invention will be described. The method for purifying wastewater described below is merely an example, and it goes without saying that various other methods including this modification can be used.
[0022]
(A) As shown in step S100 of FIG. 2, first, wastewater 30 containing PCB is introduced into the sedimentation tank 1 shown in FIG. The sedimentation tank 1 separates the sediment 31 contained in the wastewater 30 from the supernatant. Here, about 0.1 mg / l of natural minerals such as rocks are added to the wastewater 30 introduced into the settling tank 1. The particle size of the natural mineral is selected, for example, from about 1 to 1000 μm. The sediment 31 that has settled at the bottom of the settling tank 1 is discharged from the settling tank 1 in step S101.
[0023]
(B) Next, in step S110, the tenth valve 19 and the thirteenth valve 22 are closed, and the second pump 24 is stopped. Then, the third valve 12, the fourth valve 13, the fifth valve 14, the sixth valve 15, the seventh valve 16, the eighth valve 17, and the ninth valve 18 are opened, and the first pump is operated to settle the sedimentation tank 1 Is introduced into the water storage tank 2 through the water storage tank introduction pipe 33. The introduced wastewater 30 is supplied to a filtration device introduction pipe 35.
[0024]
(C) In step S120, the drainage water 30 supplied from the filtration device introduction pipe 35 is introduced into the filtration device 3 via the third valve 12, the first pump 23, the fourth valve 13, and the fifth valve 14. The wastewater 30 is filtered and purified by a filtering material such as a microfiltration membrane or an ultrafiltration membrane having a larger pore diameter than the molecules of the PCB provided in the filtration device 3. The purified wastewater 30 is introduced into a treated water tank introduction pipe 37. The concentrated water, which does not pass through the filter material and is concentrated in solid matter, is returned to the water storage tank 2 again via the eighth valve 17 and the ninth valve 18 of the water storage pipe return pipe 38.
[0025]
(D) In step S130, the waste water purified in the filtration device 3 is introduced into the treated water tank 4 via the sixth valve 15 and the seventh valve 17 of the treated water tank introduction pipe 37. The wastewater 30 introduced into the treated water tank 4 is discharged to the outside of the wastewater purifier 100 as purified water 32 in step S140. Alternatively, in step S150, the water in the treatment water tank 4 is introduced into the filtration device 3 as washing water. When the water in the treated water tank 4 is used as washing water for the filtration device 3, the first pump 23 of the filtration device introduction pipe 35 is stopped, the fifth valve 14 and the ninth valve 18 of the water storage tank return pipe 38 are closed, Activate the second pump. Then, the purified water 32 is introduced into the filtration device 3 from the filtration device supply pipe 39 via the treated water tank introduction pipe 37. The purified water 32 introduced into the filtration device 3 flows back inside the filtration device 3 to remove solid matter deposited on the surface of the filter medium.
[0026]
(E) In step S160, the filtration device 3 is washed, purified water 32 containing solid matter is supplied to the filtration device supply pipe 36, and returned to the sedimentation tank 1 again via the sedimentation tank return pipe 40.
[0027]
As described above, according to the purification method according to the first embodiment of the present invention, a PCB having a pore size of about 1 nm is larger than a PCB molecule, for example, having a pore diameter of about 1.2 to 1000 times. , The PCB can be easily removed. Since the filtered waste water has been removed from the PCB to such an extent that it passes the emission standard of the PCB, it can be directly discarded if there is no problem with the content of other harmful substances. Further, since the wastewater purifying apparatus 100 shown in FIG. 1 does not require high-temperature heating or other work requiring high energy, it can be processed simply and inexpensively. In the purification method shown in the first embodiment, the washing of the filter medium described in step S150 is preferably performed for about 15 to 25 seconds for 20 minutes of the filtering operation.
[0028]
(Example of the first embodiment)
As shown in FIG. 3, as a filtration material used in the filtration device 3, a microfiltration membrane (MF) of 0.1 to 160 μm, an ultrafiltration membrane (UF) having a molecular weight cutoff of 3000 to 50,000 (estimated pore diameter of 2 to 6 nm) ), And a reverse osmosis membrane (RO) having a molecular weight cut off of 300 (estimated pore size of 1 nm). Samples A, D, E, F, G, and H used wastewater originally containing solids. Samples B and C used wastewater containing no solid matter, and thus the solid matter was added in the settling tank 1 shown in FIG. For sample E, a flocculant was added to the wastewater containing solids in the settling tank 1 to perform flocculation and sedimentation. The solid matter concentration [mg / l] shown as “aqueous state” in FIG. 3 is Japanese Industrial Standard (JIS) K0102, the PCB concentration [mg / l] is K0093, and the solid matter particle size distribution [μm] is laser analysis. The measurement was performed according to the scattering method. In the pass / fail judgment, those that were below the PCB emission standard of 0.03 mg / l described in the Water Pollution Prevention Act (Law No. 138 of 1970) were accepted, and those that exceeded the criteria were rejected. In addition, samples that could not be stabilized for 100 hours or more were rejected.
[0029]
According to FIG. 3, it is clear that the use of the filtering material having a pore size of 1 nm to 0.5 μm enables the removal of PCB to such an extent that it passes the PCB discharge standard of the Water Pollution Control Law. Since the molecules of PCB are about 1 nm, according to the present invention, it can be seen that PCBs can be safely and effectively removed with a filter material having a pore size that is about 1.2 to 1000 times larger than the molecules of PCB. Further, from the results shown in FIG. 3, the PCB is adsorbed on the solids contained in the wastewater containing the PCB, and the solid adsorbed by the PCB is collected by the filter medium, or the solid matter deposited on the filter medium is collected. It can be seen that the PCB contained in the wastewater can be effectively removed by passing the wastewater 30 containing the PCB through the flow path inside the deposition layer. As a comparative example, when a microfiltration membrane having a pore size of 10 to 160 μm was used as a filter material, solid substances were not collected by the filter material, so that the PCB discharge standard of the Water Pollution Control Law could not be satisfied.
[0030]
(Second embodiment)
As shown in FIG. 4, the purification device according to the second embodiment of the present invention includes a PCB extraction unit 5 that extracts a gas containing PCB from soil 50, an exhaust gas heating unit 6 that heats the gas, and an exhaust gas. An exhaust gas cleaning device (scrubber) 7 for cleaning the gas passing through the gas heating unit 6 with a cleaning liquid 56, a solid substance introduction unit 8 for introducing a solid substance having a particle size larger than PCB molecules into the cleaning liquid 56, and a cleaning liquid 56 And a purification device introduction pipe 57 for introducing the wastewater into the wastewater purification device 100 as wastewater 30 containing PCB. The same configuration as the drainage purification device 100 of the first embodiment can be employed for the drainage purification device 100. That is, a solid substance introduction unit 8 for introducing a solid substance having a particle size larger than the molecules of the PCB into the cleaning liquid 56 containing the PCB extracted from the soil 50, and a filter medium having a pore size larger than the molecules of the PCB and smaller than the solid substance. And a filtration device 3 for filtering the cleaning liquid 56. The PCB extraction unit 5 is connected to the exhaust gas heating unit 6 by a first exhaust gas introduction pipe 52. The exhaust gas heating section 6 is connected to an exhaust gas cleaning device 7 by a second exhaust gas introduction pipe 54. The exhaust gas cleaning device 7 is connected to the waste water purification device 100 shown in FIG.
[0031]
The PCB extraction unit 5 is a device that heats the soil 50 containing the PCB to gasify the PCB and water. The PCB extraction unit 5 heats the soil 50 at a normal pressure to 300 to 700 ° C. In the PCB extraction unit 5, PCBs and organic substances in the soil 50 evaporate and are removed from the soil 50, or float as a tar component in the gas. PCB gas, other organic gas, and gas containing tar component are supplied to the exhaust gas heating unit 6 through the first exhaust gas introduction pipe 52.
[0032]
The exhaust gas heating unit 6 is a device that further heats the gas supplied from the PCB extraction unit 5 at a high temperature of 700 to 1100 ° C. In the exhaust gas heating section 6, a heating medium 60 such as an electric heater is arranged around the reaction tube 53 as shown in FIG. The heat medium 60 may be arranged inside the reaction tube 53. As the heat medium 60, a heat exchanger may be used in addition to the electric heater. Alternatively, a method of mixing and heating a gas heated to a high temperature in advance may be used. Further, a reactant or an accelerator that causes an exothermic reaction upon contact with a gas may be added to the exhaust gas heating unit 6. As the reactant or accelerator, for example, oxygen, carbon dioxide, ozone and the like can be used. The gas of PCB, the gas of other organic substances, and the gas containing tar component supplied from the PCB extraction unit 5 are thermally decomposed in the exhaust gas heating unit 6. The pyrolyzed gas is supplied to an exhaust gas cleaning device (scrubber) 7 through a second exhaust gas introduction pipe 54.
[0033]
The exhaust gas cleaning device 7 is a device that cleans gas thermally decomposed at a high temperature. As the exhaust gas cleaning device 7, for example, a wet air cleaning device (scrubber) or the like is used. The exhaust gas cleaning device 7 contains a cleaning liquid 56 such as water. A pump 55 is connected to the exhaust gas cleaning device 7, and the cleaning liquid 56 pumped up by the pump 55 is sprayed into the exhaust gas cleaning device 7, and the supplied gas comes into contact with the cleaning liquid 56. Since the gas supplied from the second exhaust gas introduction pipe 54 is cooled by the cleaning liquid 56, components such as PCB contained in the gas adhere to the cleaning liquid 56. The cleaning liquid 56 is supplied to the drainage purification device 100 through a purification device introduction pipe 57 connected to the exhaust gas cleaning device 7. Note that, for example, bag dust may be provided in the exhaust gas cleaning device 7 so that solid matter in the exhaust gas scattered in the exhaust gas cleaning device 7 may be collected.
[0034]
Next, a purification method according to a second embodiment of the present invention will be described.
[0035]
(A) As shown in FIG. 5, first, in step S200, the soil 50 containing PCB is introduced into the PCB extraction unit 5 shown in FIG. Next, in step S210, the PCB extraction unit 5 is heated to about 300 ° C. to 700 ° C. at normal pressure to extract a gas containing PCB from the soil 50 containing PCB. The gas containing PCB is discharged to the first exhaust gas introduction pipe 52.
[0036]
(B) Next, in step S220, the gas containing PCB introduced into the first exhaust gas introduction pipe 52 is introduced into the exhaust gas heating unit 6. In step S230, the exhaust gas heating unit 6 is heated to about 700 ° C. to 1100 ° C. at normal pressure, and the gas containing PCB is heated to a higher temperature than the heating temperature of the PCB extracting unit 5. The gas containing PCB supplied to the exhaust gas heating unit 6 is decomposed into organic substances such as tar components contained in the gas, and is discharged to the second exhaust gas introduction pipe 54.
[0037]
(C) Next, in step S240, the gas containing PCB introduced into the second exhaust gas introduction pipe 54 is introduced into the exhaust gas cleaning device 7. The gas containing PCB comes into contact with the cleaning liquid 56 provided in the exhaust gas cleaning device 7 and is cooled. The PCB components in the gas move into the cleaning liquid 56.
[0038]
(D) Next, in step S250, the cleaning liquid 56 is introduced into the wastewater purification device 100 via the purification device introduction pipe 57. The purification method in the wastewater purification device 100 is the same as the purification method in the wastewater purification device 100 shown in FIG.
[0039]
As described above, according to the method for purifying wastewater containing PCB according to the second embodiment of the present invention, the soil 50 containing PCB is heated to 300 to 700 ° C. by the PCB extraction unit 5, and further the exhaust gas heating unit In 6 heat to 700-1100 ° C. The PCB-containing soil 50 is gasified by the PCB extraction unit 5 to become a PCB-containing gas, and the gas also includes organic substances in the soil and tar components generated by decomposing the organic substances. However, the gas containing PCB, organic matter, tar component, and the like is heated to 700 ° C. or more in the exhaust gas heating unit 6, so that the tar component is thermally decomposed and removed. Therefore, the gas supplied to the exhaust gas cleaning device 7 does not include the tar component, and the cleaning liquid 56 including the tar component is not supplied to the wastewater purification device 100. Therefore, the filter medium used in the filter device 3 shown in FIG. 1 is not clogged with the tar component, so that the trouble of frequently changing the filter medium can be omitted. In addition, since the soil 50 including the PCB is heated to about 700 ° C. to 1100 ° C. in the exhaust gas heating unit 6, there is no incomplete thermal oxidation treatment or incineration treatment. Byproducts such as highly toxic coplanar PCB are not generated. According to the purification device and the purification method shown in FIG. 4, the PCB contained in the soil 50 can be easily and inexpensively removed, and can be used for a long time.
[0040]
(Example of the second embodiment)
As shown in FIG. 6, a microfiltration membrane (MF) of 0.1 to 160 μm was used for the filtration device 3 shown in FIG. FIG. 7 shows the particle size distribution of the solids in the washing water. As shown in FIG. 7, the collected washing water contained a solid having a particle size of about 1 to 700 μm. In samples I and J, the exhaust gas heating unit 6 was heated to 800 ° C. and 1100 ° C. Samples K and L did not heat the exhaust gas heating unit 6.
[0041]
According to FIG. 6, by heating the soil 50 containing PCB to about 800 ° C. to 1100 ° C. and thermally decomposing organic substances and the like contained in the soil 50, the filter medium is not clogged and the PCB discharge standard is passed. It is clear that the PCB can be removed to the extent that it does. In the samples K and L, which are the comparative examples, since the soil 50 was not heated by the exhaust gas heating unit 6, the tar component adhered to the filter material of the filter device 3 shown in FIG. Occurred. For this reason, the filter material could not be used in a short time, and the PCB discharge standard did not pass. FIG. 8 shows the particle size distribution when a bag filter is attached to the exhaust gas cleaning device 7 shown in FIG. The particle size distribution shown in FIG. 8 is obtained by measuring the particle size distribution of the soil contained in the cleaning liquid 56 shown in FIG. As shown in FIG. 8, even when solids of 500 μm or more in the exhaust gas cleaning device 7 are removed using a bag filter and a cleaning liquid containing solids of 20 to 500 μm is introduced into the wastewater purification device 100, PCB was able to be effectively removed from the soil containing PCB.
[0042]
(Other embodiments)
As described above, the present invention has been described with reference to the first and second embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.
[0043]
In the first and second embodiments of the present invention, other organic pollution components such as BOD and COD other than PCB may be included. Further, a filter aid may be added to the filtration device 3 to aggregate suspended particles in the wastewater.
[0044]
Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the matters specifying the invention described in the claims appropriate from this disclosure.
[0045]
【The invention's effect】
Advantageous Effects of Invention According to the present invention, it is possible to provide a purification device and a purification method that can easily and inexpensively treat PCBs contained in soil and wastewater and that can achieve a PCB emission standard.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a purification device according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing a purification method according to the first embodiment of the present invention.
FIG. 3 is a table showing an example of the first embodiment of the present invention.
FIG. 4 is a schematic diagram showing a purification device according to a second embodiment of the present invention.
FIG. 5 is a flowchart showing a purification method according to a second embodiment of the present invention.
FIG. 6 is a table showing an example of the second embodiment of the present invention.
FIG. 7 is a diagram showing a particle size distribution of solids present in soil water immediately after collection in an example of the second embodiment.
FIG. 8 is a diagram showing a particle size distribution of solids present in washing water when a bag filter is attached to a drainage purification device in an example of the second embodiment.
[Explanation of symbols]
1. Settling tank
2 ... water tank
3. Filtration device
4 ... Treatment tank
5. PCB extraction unit
6 Exhaust gas heating section
7. Exhaust gas cleaning device
8 ... Solid introduction section
10 ... 1st valve
11 ... second valve
12: Third valve
13: 4th valve
14: Fifth valve
15: 6th valve
16: 7th valve
17: 7th valve
17… 8th valve
18 ... 9th valve
19 ... 10th valve
20 ... eleventh valve
21: 12th valve
22 ... thirteenth valve
23 ... First pump
24 ... second pump
25 ... first pressure gauge
26 ... third pressure gauge
27 ... second pressure gauge
30 ... drainage
31 ... sediment
32 ... Purified water
33… Reservoir introduction pipe
34 ... Drain pipe
35 ... Filtration device introduction pipe
36 ... Filtration device supply pipe
37… Treatment tank introduction pipe
38 ... Reservoir return pipe
39 ... Filter washing pipe
40 ... settling tank return pipe
50 ... Soil
52: First exhaust gas introduction pipe
53 ... Reaction tube
54: second exhaust gas introduction pipe
55… pump
56 cleaning liquid
57… Purification line
60 heat medium
100 ... waste water purification device

Claims (8)

A solids introduction section for introducing a solid matter larger than the molecules of the PCB into wastewater containing PCBs;
A purifying apparatus, comprising: a filtering material having a pore size larger than the molecules of the PCB and smaller than the solid matter, and filtering the wastewater. A PCB extraction unit for extracting a gas containing PCB from soil,
An exhaust gas heating unit that heats the gas,
An exhaust gas cleaning device that cleans the gas that has passed through the exhaust gas heating unit with a cleaning liquid,
A solid substance introduction unit for introducing a solid substance having a particle size larger than the molecule of the PCB into the cleaning liquid;
A purifying apparatus, comprising: a filtering device having a filter medium having a pore size larger than the molecules of the PCB and smaller than the solid matter, and filtering the cleaning liquid. The purifying device according to claim 1, wherein the filter is a microfiltration membrane. The purification device according to claim 1, wherein the filtration material is an ultrafiltration membrane. A purification method comprising: filtering wastewater containing PCB and solid matter through a filter medium having a pore size larger than the molecule of the PCB and smaller than the particle size of the solid matter to remove the PCB from the wastewater. Method. Extracting PCB-containing gas from the soil;
Heating a gas containing the PCB;
Cleaning the gas containing the heated PCB with a cleaning liquid;
Introducing a solid having a particle size larger than the molecules of the PCB into the cleaning liquid;
Removing the PCB from the cleaning liquid by filtering the cleaning liquid with a filter medium having a pore size larger than the molecules of the PCB and smaller than the particle size of the solid substance. The purification method according to claim 5, wherein the filtration material is a microfiltration membrane. The purification method according to claim 5, wherein the filtration material is an ultrafiltration membrane.

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