Method for treating gas containing fluorinated organic compound

Abstract

A treatment method is provided in which a fluorinated organic compound having a low molecular weight can be continuously and efficiently removed over a long period from a gas containing said fluorinated organic compound.　This method for treating a gas containing a fluorinated organic compound comprises leading a gas containing a fluorinated organic compound having a molecular weight of 1,000 or less to a wet scrubber and further leading said gas to a water-repellent filter.

Description

Method for treating gas containing fluorine-containing organic compounds

[0001] The present invention relates to a method for treating a gas containing a fluorine-containing organic compound.

[0002] Fluorine-containing organic compounds have properties such as heat resistance, chemical resistance, and water repellency, and are used in a variety of applications, such as surfactants, emulsifiers, water repellents, fire extinguishing agents, waxes, and coating agents. Meanwhile, efforts have begun to remove low-molecular-weight fluorine-containing organic compounds or to reduce their emissions into the environment. Patent Document 1 proposes a method for removing perfluoroalkyl and polyfluoroalkyl substances from liquids or gases by using a specific first adsorbent, preferably in combination with a specific second adsorbent. Patent Document 2 discloses a specific carbonaceous material and shows its application to a water purifier that removes fluorine-containing organic compounds from water containing the same.

[0003] Patent Publication No. 2022-526606 International Publication No. 2022 / 085550

[0004] When a solid adsorbent is used as a method for removing fluorine-containing organic compounds, problems arise in that the solid adsorbent must be replaced as its adsorption performance deteriorates, and in that maintenance costs, such as the manufacturing cost of the solid adsorbent itself, are high. On the other hand, the application of a scrubber system is considered as a method for removing fluorine-containing organic compounds from gases containing fluorine-containing organic compounds. However, in the scrubber system, attempts to improve the removal efficiency generally result in large-scale equipment, requiring a large installation space and high installation costs. In studying a method for treating gases containing low-molecular-weight fluorine-containing organic compounds, the present inventors discovered that fluorine-containing organic compounds can be efficiently removed by introducing the gases containing such fluorine-containing organic compounds into a wet scrubber, preferably a wet scrubber capable of generating mist or vortex flow, and further treating the passed gas by guiding it through a water-repellent filter. Furthermore, they discovered that such a method allows the treatment equipment to be miniaturized and enables continuous treatment of such gases over a long period of time, leading to the present invention. An object of the present invention is to provide a treatment method capable of removing low-molecular-weight fluorine-containing organic compounds from a gas containing such compounds continuously and efficiently over a long period of time.

[0005] The present invention has the following aspects: [1] A method for treating a gas containing a fluorine-containing organic compound, which comprises introducing a gas containing a fluorine-containing organic compound having a molecular weight of 1,000 or less into a wet scrubber and then leading the gas to a water-repellent filter. [2] A method for treating a gas containing a fluorine-containing organic compound, which comprises introducing a gas containing a fluorine-containing organic compound having a molecular weight of 1,000 or less into a wet scrubber and then leading the gas to a water-repellent filter. ３ [3] The treatment method according to [1], wherein the concentration of the fluorine-containing organic compound in the gas outside the gas outlet of the wet scrubber is greater than 10 ng / Nm ３[4] The treatment method of any of [1] to [3], wherein the water-repellent filter is provided at a gas outlet of the wet scrubber. [5] The treatment method of any of [1] to [4], wherein the water-repellent filter is made of a fluorine-based resin, a silicone-based resin, or a material that has been surface-treated with a fluorine-based resin or a silicone-based resin. [6] The treatment method of any of [1] to [5], wherein the water-repellent filter has a water contact angle of more than 100° and a water sliding angle of less than 10°, as specified in JIS Z 8122. [7] The treatment method of any of [1] to [6], wherein the water-repellent filter has a particle collection efficiency of 99.97% or more for particles with a particle size of 0.3 μm at a rated air flow rate, and an initial pressure loss of 245 Pa or less, as specified in JIS Z 8122. [8] The treatment method of any of [1] to [7], wherein a plurality of the water-repellent filters are stacked. [9] The treatment method of any one of [1] to [8], wherein the pH of the water used in the wet scrubber is greater than 8.

[10] The treatment method of [9], wherein the base for adjusting the pH of the water used in the wet scrubber to greater than 8 is a basic compound containing potassium.

[11] The treatment method of any one of [1] to

[10] , wherein the wet scrubber is a wet scrubber selected from a pooled-water type wet scrubber or a spray-type wet scrubber.

[12] The treatment method of any one of [1] to

[11] , wherein the wet scrubber is a pooled-water type wet scrubber having a mixing flow path between a gas inlet and a gas outlet, the mixing path being configured so that the gas and the water pass through while being mixed.

[13] The treatment method of

[12] , wherein the wet scrubber has a plurality of the mixing flow paths.

[14] The treatment method according to any one of [1] to

[13] , wherein the wet scrubber further has a blowing plate provided immediately before the gas outlet so as to drop the liquid blown up from the mixing channel.

[0006] According to the present invention, it is possible to remove low-molecular-weight fluorine-containing organic compounds from gases containing such compounds continuously and efficiently over a long period of time.

[0007] In this specification, the term "fluorine-containing organic compound having a molecular weight of 1,000 or less" (hereinafter also simply referred to as "fluorine-containing organic compound") means fluorine-containing organic compounds including perfluoroalkylcarboxylic acids typified by perfluorooctanoic acid (PFOA), perfluoroalkylsulfonic acids typified by perfluorooctanesulfonic acid (PFOS), polyfluoroalkyl compounds, derivatives thereof, or mixtures thereof.

[0008] The present invention is a method for treating a gas containing a fluorine-containing organic compound (hereinafter also referred to as "the method"), in which the gas containing a fluorine-containing organic compound having a molecular weight of 1,000 or less is introduced into a wet scrubber and then led to a water-repellent filter. In the method, the wet scrubber is preferably a wet scrubber capable of generating atomized water (mist) or vortex water, selected from a pooled-water wet scrubber or a spray-type wet scrubber, as described below. According to the method, the fluorine-containing organic compound can be removed efficiently and continuously over a long period of time from a gas containing the low-molecular-weight fluorine-containing organic compound.

[0009] Examples of the fluorine-containing organic compound include polyfluoroalkyl carboxylic acids, polyfluoroalkyl sulfonic acids, and derivatives thereof such as salts, esters, amides, amidoethanols, and amidoacetic acids; polyfluoroalkyl compounds; fluoroproteins, fluorotelomer carboxylic acids, fluorotelomer alcohols, fluorotelomer sulfonates, and fluorotelomer sulfonic acids. An etheric oxygen atom may be inserted between the carbon atom-carbon atom bonds of the above-mentioned fluorine-containing organic compounds. More specifically, F(CF ２ ) ７ COOM (wherein M is a hydrogen atom, a metal atom, NR １ ４ , an imidazolium group which may have a substituent, a pyridinium group which may have a substituent, or a phosphonium group which may have a substituent; R １ represents a hydrogen atom or an organic group. The same applies hereinafter.) perfluorooctanoic acid (PFOA) or a derivative thereof; F(CF ２ )５ COOM; perfluoroheptanoic acid or a derivative thereof; H(CF ２ ) ６ COOM, H. (CF ２ ) ７ COOM et al. H(CF ２ ) ｎ COOM (wherein n is an integer of 1 to 24; the same applies hereinafter), a compound represented by CF ３ O (CF ２ ) ３ OCHFCF ２ COOM, C. ３ F ７ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ OCF ２ CF ２ OCF ２ COOM, C. ２ F ５ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ３ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ２ ClCF ２ CF ２ OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF ２ CF ２ OCF ２ CF (CF ３ ) OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF２ CF (CF ３ ) OCF ２ COOM, a cyclic compound of the following formula (1);

[0010]

[0011] C ８ F １７ SO ３ perfluorooctanesulfonic acid (PFOS) or its derivatives represented by M; ２ ) ｎ SO ３ Examples of the fluorine-containing organic compounds include compounds represented by M, N-methylperfluorooctanesulfonamide, N-ethylperfluorooctanesulfonamide, N-ethylperfluorooctanesulfonamidoethanol, perfluorooctanesulfonamide, perfluorooctanesulfonamidoacetic acid, perfluorooctanesulfonamidoethanol; perfluorobutanoic acid, perfluorobutanesulfonate, perfluorobutanesulfonic acid, perfluorohexanesulfonate, and perfluorohexanesulfonic acid. In this method, fluorine-containing organic compounds, particularly PFOA, PFOS, and similar compounds, can be efficiently removed from gases containing these compounds.

[0012] In this method, the amount of fluorine-containing organic compounds contained in a gas is determined by passing 90 L of the target gas through 150 ml of methanol, concentrating the solution extracted with the fluorine-containing organic compounds in the gas under a nitrogen gas atmosphere, and analyzing the resulting sample by LC / MS / MS measurement under the following conditions. Molecular weight information is extracted from the obtained LC / MS spectrum, and after confirming that it matches the structural formula of the candidate fluorine-containing organic compound, a calibration curve of the candidate fluorine-containing organic compound prepared separately is used to convert the area of ​​the LC / MS chromatogram of the fluorine-containing organic compound in the sample into the content of the fluorine-containing organic compound. The calibration curve can be prepared by LC / MS analysis of a methanol solution containing a predetermined amount of the candidate fluorine-containing organic compound. In this measurement method, the lower detection limit of the fluorine-containing organic compound contained in the gas is 1 ng / Nm ３ is.

[0013] <Conditions> LC section: Apparatus: Agilent 1290 Infinity II Column: Agilent Zorbax RRHD Extend-C18 1.8 μm (2.1 × 50 mm) Mobile phase: Acetonitrile / 20 mM ammonium acetate aqueous solution = 60 / 40 (volume ratio) Flow rate: 0.3 mL / min Column temperature: 40°C Sample injection amount: 1 μL MS section: Apparatus: Agilent Ultivo LC / TQ Measurement mode: MRM (Multiple Reaction Monitoring) Ionization method: Electrospray ionization negative mode

[0014] This method is used when the concentration of fluorine-containing organic compounds in the gas at the gas inlet of the wet scrubber is 100 μg / Nm ３ The present method can be applied to gases having a concentration of fluorine-containing organic compounds exceeding 100 μg / Nm3, and can remove fluorine-containing organic compounds from such gases continuously and efficiently over a long period of time. ３ Super 10000μg / Nm ３ In this method, the concentration of fluorine-containing organic compounds in the treated gas outside the gas outlet of the wet scrubber is preferably in the range of less than 100 ng / Nm ３ More preferably, it is 10 ng / Nm or less. ３ More preferably, it is less than 1000 ppm, and may be at a concentration below the detection limit.

[0015] In this method, a water-repellent filter is used. Examples of materials for the water-repellent filter include fluorine-based resins such as polytetrafluoroethylene (PTFE), silicone-based resins, polyester-based resins, acrylic resins, and polyvinyl chloride-based resins. The water-repellent filter may be made of a fluorine-based resin, a silicone-based resin, or a material surface-treated with a fluorine-based resin or a silicone-based resin. Alternatively, the water-repellent filter may be a filter made of a resin other than the above-mentioned resins, or a ceramic filter surface-treated with, for example, a fluorine-based resin or a silicone-based resin. Commercially available water-repellent filters include, for example, the "Ecolter NPT" series manufactured by Eiko Filter Co., Ltd.

[0016] The reason why this method can continuously and efficiently remove fluorine-containing organic compounds over a long period of time is unclear, but is presumed to be as follows. In this method, a gas containing fluorine-containing organic compounds is introduced into a wet scrubber, and the gas is then guided to a water-repellent filter. Preferably, a pooled-water wet scrubber or a spray-type wet scrubber is used, so that atomized water (mist) stirred up in the scrubber moves along with the gas and continuously adheres to the surface of the water-repellent filter. Here, water droplets are generated by the surface tension of the water constituting the mist, which then fall under their own weight while adsorbing the fluorine-containing organic compounds, and circulate within the wet scrubber. That is, since water remains attached to the water-repellent filter until the mist that has adhered to the water-repellent filter turns into water droplets and falls, it is presumed that even if there are fluorine-containing organic compounds that have not been removed before being guided to the water-repellent filter, they can be removed at this stage. Furthermore, the mist adhering to the surface of the water-repellent filter also penetrates into the pores of the filter and disperses in the form of droplets, and these droplets grow larger as other mist adheres to them, causing the pores of the water-repellent filter to be partially blocked by the droplets. This increases the area where gas can come into contact with the water on the water-repellent filter, presumably further improving the efficiency of removing fluorine-containing organic compounds contained in the gas. Furthermore, once the water in the pores of the water-repellent filter grows to a certain size, it becomes spherical due to surface tension and falls under its own weight, making it less likely for the water-repellent filter to become clogged, allowing the differential pressure of the water-repellent filter to be maintained low and enabling continuous treatment over a long period of time.

[0017] The water contact angle of the water-repellent filter is preferably more than 100° and the water sliding angle is preferably less than 10°. When the water contact angle and the water sliding angle satisfy the above-mentioned ranges, the above-mentioned mechanism is more effectively exerted, which reduces clogging of the water-repellent filter and enables efficient removal of fluorine-containing organic compounds in the gas.

[0018] In this method, a water-repellent filter is preferred that has a particle collection efficiency of 99.97% or more for particles having a particle size of 0.3 μm at a rated air flow rate and an initial pressure loss of 245 Pa or less, as specified in JIS Z 8122, and more preferably a water-repellent filter that has a particle collection efficiency of 99.9995% or more for particles having a particle size of 0.15 μm at a rated air flow rate and an initial pressure loss of 245 Pa or less. When a water-repellent filter that satisfies these particle collection efficiency and initial pressure loss requirements is used, the above-mentioned mechanism is more effectively exerted, the occurrence of clogging of the water-repellent filter can be reduced, and fluorine-containing organic compounds in the gas can be removed efficiently and continuously over a long period of time.

[0019] In this method, it is preferable to provide a water-repellent filter at the gas outlet of a wet scrubber described below, from the viewpoint of reducing clogging and further increasing the efficiency of removing fluorine-containing organic compounds contained in the gas. In this method, the water-repellent filter may be used alone or in a state where multiple filters are stacked.

[0020] In this method, from the viewpoint of continuously and efficiently removing fluorine-containing organic compounds from gas over a long period of time, the pH of the water used in the wet scrubber (hereinafter also referred to as "scrubber water") is preferably greater than 8. From the viewpoint of increasing the efficiency of removing fluorine-containing organic compounds, the pH of the scrubber water is more preferably 10 or higher.

[0021] Examples of bases for adjusting the pH of the scrubber water to greater than 8 include basic compounds containing an alkali metal such as lithium, sodium, or potassium, or basic compounds containing an alkaline earth metal such as magnesium or calcium. Among these, basic compounds containing an alkali metal are preferred, basic compounds containing potassium are more preferred, and potassium hydroxide and potassium carbonate are even more preferred. In this case, not only is the foaming property of the scrubber water suppressed, but the generation of solids during treatment is also suppressed, making the above-mentioned presumed mechanism more likely to be realized. The scrubber water may further contain a water-soluble solvent such as acetone. When such a water-soluble solvent is contained, the surface tension of the scrubber water is adjusted, the foaming property of the scrubber water is suppressed, and the above-mentioned presumed mechanism is more likely to be realized. This reduces the occurrence of clogging of the water-repellent filter, allowing fluorine-containing organic compounds in the gas to be continuously and efficiently removed over a long period of time.

[0022] A wet scrubber is a device that removes contaminants such as dust by contacting gas with a liquid in a system and discharges the scrubbed gas. In this method, the wet scrubber is preferably a wet scrubber selected from a pooled-water wet scrubber or a spray-type wet scrubber. In other words, the wet scrubber in this method is preferably a wet scrubber that generates atomized or vortex-like scrubber water (mist), making the atmosphere inside the scrubber humid and containing the mist, and the gas to be treated and the mist are entrained and guided to a water-repellent filter. Examples of materials for the components that make up the wet scrubber include metal materials such as SUS304 and SUS316L, and fiber-reinforced plastics.

[0023] In the case of a pooled-water wet scrubber, no packing is used, and typically, the gas is scrubbed and fluorine-containing organic compounds are removed by injecting scrubber water into the introduced gas, blowing the gas into the scrubber water, or having a structure in which the gas and scrubber water are brought into contact while being raised when the gas is introduced (also called an unpacked tower scrubber, shower tower, or spray tower). In the case of a spray-type wet scrubber, typically, packing materials are preferably arranged in several layers inside the tower, and while the gas is being introduced, scrubber water is sprayed or sprinkled onto the packing materials to scrub the introduced gas and remove the fluorine-containing organic compounds (also called a packed tower scrubber). Note that the scrubber water can be circulated in the wet scrubber and replaced during long-term continuous operation, for example, depending on the amount of gas containing fluorine-containing organic compounds being treated or the amount of fluorine-containing organic compounds being removed.

[0024] In this method, the wet scrubber is preferably a pooled-water wet scrubber having a mixing flow path between a gas inlet and a gas outlet, through which gas and water pass while being mixed, from the viewpoint that the scrubber water can be raised and brought into contact with the gas when the gas is introduced. Such a mixing flow path is preferably formed of a plate-shaped material so that the gas and scrubber water pass while being mixed. The mixing flow path is preferably formed vertically, with the gas flowing in from the lower side of the flow path toward the upper side. Furthermore, it is preferable that a plurality of plates are further provided within the mixing flow path, dividing the flow path into a plurality of spaces so that the gas and scrubber water pass through in a vortex-like manner while being mixed. By passing the gas and the scrubber water in the form of mist from the lower side to the upper side within such a plurality of spaces while being mixed, fluorine-containing organic compounds in the gas can be efficiently removed. An example of a wet scrubber having such a mixing flow path is the pooled-water dust collector disclosed in JP 2023-008080 A.

[0025] A preferred embodiment of the pooled-water wet scrubber is one having a plurality of the above-described mixing channels, from the viewpoints of more efficiently removing fluorine-containing organic compounds and miniaturizing the device. In other words, in this method, a pooled-water wet scrubber is used that has a plurality of mixing channels between a gas inlet and a gas outlet, configured so that gas and water pass through while being mixed, and a water-repellent filter is provided at the gas outlet of the wet scrubber. In this case, the device can be miniaturized, and mist can be generated and contacted by raising scrubber water when introducing the gas. Furthermore, since the above-described scrubber water can be used, a special extractant for removing fluorine-containing organic compounds is not required, and this is preferred from the viewpoints of efficiently removing fluorine-containing organic compounds from the gas continuously over a long period of time.

[0026] In this method, the wet scrubber preferably further includes a blowing plate located immediately before the gas outlet so as to allow the liquid blown up from the mixing channel to fall. The blowing plate is preferably located below the gas outlet of the wet scrubber, and is preferably provided so as to be slightly inclined from the inner wall of the wet scrubber toward the inside of the scrubber, and preferably has an end on the scrubber interior bent downward. The inclusion of such a blowing plate can prevent excessive scrubber water from being discharged from the gas outlet, thereby further enhancing the water-repellent filter effect of this method. In addition, mist of scrubber water adheres to the underside of the blowing plate, condenses, grows into droplets, and falls downward, allowing the scrubber water to be circulated.

[0027] In this method, there is no particular limitation on the amount of gas to be treated introduced into the wet scrubber, and the size of the wet scrubber and the amount of scrubber water used can be appropriately set depending on the amount of gas to be treated per unit time.

[0028] In carrying out this method, a pipe for supplying the gas to be treated to the wet scrubber is connected to a gas inlet for introducing the gas to be treated into the wet scrubber, and a pipe for recovering the treated gas discharged from the wet scrubber is connected to a gas outlet for discharging the treated gas from the wet scrubber. The gas introduced into the wet scrubber from the gas inlet is guided to the lower side of the mixing channel, and as it flows into the mixing channel, it comes into contact with the scrubber water while being stirred up. The gas and the scrubber water that has become a mist mix and rise as they pass through the mixing channel, and the treated gas is then discharged from the gas outlet to the outside of the wet scrubber.

[0029] Although the present invention has been described above, the present invention is not limited to the configurations of the above-described embodiments. For example, the present invention may include any other configuration or step in addition to the configurations of the above-described embodiments, or may be substituted with any other configuration or step that produces a similar effect.

[0030] EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. The content of fluorine-containing organic compounds in gas was analyzed by the method described above.

[0031] [Example 1] A water-retention type wet scrubber having a plurality of mixing channels between a gas inlet and a gas outlet, through which gas and water pass while being mixed, was filled with an aqueous solution of potassium carbonate dissolved therein and adjusted to a pH of 9 as scrubber water, in an amount that would generate mist while stirring up the scrubber water when gas was introduced. Furthermore, two water-repellent filters made of polytetrafluoroethylene (PTFE) were installed in a stack at the gas outlet of the wet scrubber. The filters have a particle collection efficiency of 99.97% or more for particles with a particle size of 0.3 μm at the rated air flow rate, as specified in JIS Z 8122, and an initial pressure loss of 245 Pa or less. PFOA, a fluorine-containing organic compound, was introduced into the gas inlet of the water-retention type wet scrubber at a concentration of 200 μg / Nm3. ３ The gas containing PFOA was introduced into a water-storage wet scrubber. The scrubber water temperature was set to 25°C. The PFOA content of the treated gas discharged from the gas outlet was measured and found to be 5 ng / Nm３ Furthermore, no scale (limescale) was observed inside the pooled water wet scrubber after treatment.

[0032] [Example 2] Gas was treated in the same manner as in Example 1, except that potassium carbonate was replaced with sodium carbonate. The PFOA content of the treated gas discharged from the gas outlet of the pooled water type wet scrubber was measured and found to be 5 ng / Nm ３ After treatment, scale (limescale) was found inside the pooled water wet scrubber.

[0033] [Example 3] In Example 1, PFOA was added at a concentration of 200 μg / Nm3 in the same manner as in Example 1, except that two glass fiber filters, which have a particle collection efficiency of 99.97% or more for particles with a particle size of 0.3 μm at the rated air flow rate and an initial pressure loss of 245 Pa or less as specified in JIS Z 8122, were installed in the gas outlet of the wet scrubber instead of the PTFE water-repellent filter. ３ The PFOA content of the treated gas discharged from the gas outlet was measured and found to be 30 ng / Nm ３ It was.

[0034] The treatment method of the present invention can continuously and efficiently remove low-molecular-weight fluorine-containing organic compounds from gases containing such compounds over a long period of time, and is therefore useful for removing fluorine-containing organic compounds.

[0035] The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2023-155588, filed on September 21, 2023, are incorporated herein by reference as part of the disclosure of the present invention.

Claims

1. A method for treating a gas containing a fluorine-containing organic compound, comprising introducing the gas containing a fluorine-containing organic compound having a molecular weight of 1,000 or less into a wet scrubber and then leading the gas to a water-repellent filter.

2. The concentration of the fluorine-containing organic compound in the gas at the gas inlet of the wet scrubber is 100 μg / Nm ３ The method of claim 1 , wherein the temperature is greater than 100° C.

3. The concentration of the fluorine-containing organic compound in the gas outside the gas outlet of the wet scrubber is 10 ng / Nm ３ The method of claim 1 , wherein the 4. The treatment method according to claim 1, wherein the water-repellent filter is provided at a gas outlet of the wet scrubber.

5. The treatment method according to claim 1, wherein the water-repellent filter is made of a material that is surface-treated with a fluorine-based resin, a silicone-based resin, or a fluorine-based resin or a silicone-based resin.

6. The treatment method according to claim 1, wherein the water-repellent filter has a water contact angle of more than 100° and a water sliding angle of less than 10°.

7. The treatment method according to claim 1, wherein the water-repellent filter has a particle collection rate of 99.97% or more for particles having a particle size of 0.3 μm at rated air flow as specified in JIS Z 8122, and an initial pressure loss of 245 Pa or less.

8. The treatment method according to claim 1, wherein the water-repellent filters are stacked in multiple layers.

9. The process of claim 1, wherein the pH of the water used in the wet scrubber is greater than 8.

10. The treatment method according to claim 9, wherein the base for adjusting the pH of the water used in the wet scrubber to greater than 8 is a basic compound containing potassium.

11. The treatment method according to claim 1, wherein the wet scrubber is a wet scrubber selected from a pooled-water type wet scrubber or a spray type wet scrubber.

12. The treatment method according to claim 1, wherein the wet scrubber is a pooled-water wet scrubber having a mixing passage between a gas inlet and a gas outlet, the mixing passage being configured so that the gas and the water pass through while being mixed.

13. The method of claim 12, wherein the wet scrubber comprises a plurality of the mixing passages.

14. The treatment method according to claim 1, wherein the wet scrubber further comprises a blowing plate disposed immediately before the gas outlet so as to allow liquid blown up from the mixing channel to fall therethrough.

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