Exhaust gas or waste liquid treatment method and exhaust gas or waste liquid treatment device

Abstract

Provided is a waste gas or waste liquid treatment method and a waste gas or waste liquid treatment device that can efficiently decompose acrylonitrile. The waste gas or waste liquid treatment method of the present embodiment includes a first step of contacting acrylonitrile in a waste gas or waste liquid, a biocatalyst, and a solvent for activating the biocatalyst to convert into acrylamide and / or an acrylate, and a second step of decomposing the acrylamide and / or the acrylate.

Description

Technical Field

[0001] This embodiment relates to a method for treating acrylonitrile-containing waste gas or waste liquid, and an apparatus for treating waste gas or waste liquid. Background Technology

[0002] Acrylonitrile is frequently used as a material in acrylic synthetic fibers and other similar products. However, acrylonitrile is highly toxic and is legally classified as a hazardous substance. Furthermore, acrylonitrile is volatile and highly flammable. Therefore, when acrylonitrile is present in waste gas and / or waste liquid, it is necessary to recover and reuse it, or to convert it into a safe substance.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Application Publication No. 2015 / 19006

[0006] Non-patent literature

[0007] Non-patent literature 1: "Removal of acrylonitrile vapor from waste gases by atrickle-bed air biolter", Chungsying Lu et al. Bioresource Technology, 75(2000), 35-41

[0008] Non-patent document 2: "Environmental Pollution Load Minimum Wastewater Treatment System Evaluation", Koichi Eto (Research Project No. 04832020), FY2005 Scientific Research Funding Grant (General Research (C)) Research Result Report, Yokohama National University Library

[0009] Non-patent document 3: "Biodegradation of high acrylamide concentrations inintegrated fixed film activated sludge (IFAS) wastewater treatment system", Tongchai Sriwiriyarat et.al. Biochemical Engineering Journal, 159 (2020), 107566 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] People considered using microorganisms to biodegrade acrylonitrile. However, acrylonitrile is highly volatile and difficult to decompose, making it difficult for conventional biological treatment devices to efficiently decompose it.

[0012] Therefore, this embodiment aims to solve the above-mentioned problems and provide a method and apparatus for efficiently treating acrylonitrile waste gas or waste liquid.

[0013] Problem-solving methods

[0014] The waste gas or waste liquid treatment method based on this embodiment includes a first step of contacting acrylonitrile, a biocatalyst, and a solvent for activating the biocatalyst in the waste gas or waste liquid to convert them into acrylamide and / or acrylate, and a second step of decomposing acrylamide and / or acrylate.

[0015] The biocatalyst is one or more biocatalysts selected from microorganisms and enzymes with nitrile hydratase activity and microorganisms and enzymes with nitrile hydrolase activity.

[0016] Microorganisms with nitrile hydratase activity are selected from one or more of the genera Rhodococcus and Trichophyton.

[0017] The microorganism possessing nitrile hydratase activity is Rhodococcus roseum.

[0018] Microorganisms with nitrile hydrolase activity are selected from one or more of the genera Rhodococcus, Acinetobacter, Alcaligenes, and Delft.

[0019] The first and second processes are independent processes.

[0020] The reaction temperature in the first process is 20~30℃.

[0021] The pH value of acrylonitrile, biocatalyst, and solvent in the first process is pH 6-8.

[0022] In the first process, the gas flow rate to acrylonitrile, biocatalyst, and solvent is below 5 vvm.

[0023] The concentration of acrylonitrile in the waste gas or waste liquid is below 10,000 ppm.

[0024] The first step involves passing acrylonitrile and the solvent of the activated biocatalyst through the biocatalyst along the direction of gravity to convert them into a solution containing acrylamide and / or acrylate.

[0025] The waste gas or waste liquid treatment apparatus of this embodiment includes an acrylonitrile converter and a processor. The acrylonitrile converter has a housing for housing an immobilized biocatalyst, an acrylonitrile inlet for introducing waste gas or waste liquid containing acrylonitrile into the housing, a solvent inlet for introducing a solvent for activating the immobilized biocatalyst, and a drain outlet for discharging a solution containing acrylamide and / or acrylate generated from acrylonitrile through the immobilized biocatalyst from the housing. The processor treats the solution containing acrylamide and / or acrylate discharged from the acrylonitrile converter.

[0026] The solvent inlet is an acrylonitrile inlet.

[0027] The acrylonitrile converter is a fixed-layer catalytic reactor in which an immobilized biocatalyst is filled in the shell.

[0028] The acrylonitrile inlet and solvent inlet are located at the upper end of the housing.

[0029] The acrylonitrile converter has an exhaust port that discharges the waste gas that has passed through the immobilized biocatalyst from the housing.

[0030] The carriers for immobilized biocatalysts are activated carbon or lignocarbons.

[0031] The acrylonitrile converter also includes: a temperature sensor for detecting the temperature of the immobilized biocatalyst, a temperature regulating unit for adjusting the temperature of the immobilized biocatalyst, and a temperature controller for controlling the temperature regulating unit based on the temperature measurement value from the temperature sensor.

[0032] The acrylonitrile converter also includes: a pH sensor for detecting the pH value of the immobilized biocatalyst, a pH adjuster introduction unit for introducing a pH adjuster that adjusts the pH value of the immobilized biocatalyst into the solvent, and a pH controller for controlling the pH adjuster introduction unit based on the pH measurement value from the pH sensor.

[0033] The processor stores activated sludge that has been processed for acrylamide and / or acrylate.

[0034] Activated sludge has amidase activity. Attached Figure Description

[0035] Figure 1 This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the first embodiment.

[0036] Figure 2 This is a diagram showing a processing example in the waste gas and / or waste liquid treatment apparatus of the first embodiment.

[0037] Figure 3 It is a table showing the characteristics of substances produced in each treatment stage of the waste gas and / or waste liquid treatment device.

[0038] Figure 4 This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the second embodiment.

[0039] Figure 5 This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the third embodiment.

[0040] Figure 6A This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the fourth embodiment.

[0041] Figure 6B This is a block diagram showing a structural example of the waste liquid treatment apparatus according to the fifth embodiment.

[0042] Figure 7 This is a schematic diagram showing the structure of the processing device of Comparative Example 1.

[0043] Figure 8 This is a schematic diagram showing the structure of the processing apparatus for Comparative Example 2 and Comparative Example 3.

[0044] Figure 9 This is a table showing the comparison results of Comparative Examples 1-3 and Examples 1-4. Detailed Implementation

[0045] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. These embodiments are not intended to limit the present invention. The drawings are schematic or conceptual, and the proportions of the parts may not be identical to reality. In the specification and drawings, the same reference numerals are used for elements that appear in the drawings and are described above, and detailed descriptions are omitted where appropriate.

[0046] (First Implementation)

[0047] Figure 1 This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the first embodiment. The waste gas and / or waste liquid treatment apparatus 1 includes an acrylonitrile converter 10 and a solvent processor 20. Additionally, in Figure 1 In the diagram, solid arrows indicate the flow of piping, liquids, or gases. Dashed arrows indicate the flow of signals.

[0048] The acrylonitrile converter 10 includes a housing 11, a first inlet In1, a second inlet In2, an exhaust port Out1, a drain port Out2, a biocatalyst 12, and a pump 13. The acrylonitrile converter 10 is a fixed-layer catalytic reactor in which the biocatalyst 12 is filled inside the housing 11.

[0049] The shell 11 is, for example, a hollow cylindrical shape, serving as a sealed container to prevent acrylonitrile from leaking to the outside. The shell 11 is constructed, for example, from a metallic material such as stainless steel (SUS) resistant to acrylonitrile, or a resin material such as rigid polyvinyl chloride. The biocatalyst 12 is contained within the shell 11. The shell 11 is constructed in a gas-tight manner to prevent the volatile acrylonitrile from leaking to the outside. For example, the gas flow rate of the shell 11 is preferably 5 vvm (gas volume per liquid volume per minute, where liquid is the volume of liquid held by the carrier, approximated as the carrier volume in this invention) or less, and more preferably 0.5 vvm or less. This is to prevent the volatile acrylonitrile from leaking to the outside of the shell 11. If the gas flow rate is too high, the pressure applied to the container increases, thus increasing the risk of acrylonitrile leakage. Furthermore, if the gas flow rate is too high, the acrylonitrile carrier passes through at a rate exceeding the decomposition rate, increasing the amount discharged in an unreacted state. Additionally, the acrylonitrile concentration in the gas or waste liquid is preferably 10,000 ppm or less, and more preferably 5,000 ppm or less. This is because when the acrylonitrile concentration exceeds 10,000 ppm, the concentrations of acrylamide and acrylate decomposed by the acrylonitrile converter also increase, thus increasing the decomposition load in step 2. It should be noted that there is no particular limitation on the lower limit of the acrylonitrile concentration in the gas or waste liquid, but it is preferably 1 ppm or higher, and more preferably 10 ppm or higher.

[0050] The biocatalyst 12 is, for example, an immobilized biocatalyst formed by immobilizing a microorganism with nitrile hydratase activity or an enzyme with nitrile hydratase activity on a support. Alternatively, the biocatalyst 12 is, for example, a catalyst formed by immobilizing a microorganism with nitrile hydrolase activity or an enzyme with nitrile hydrolase activity on a support. That is, the biocatalyst 12 is one or more biocatalysts selected from microorganisms and enzymes with nitrile hydratase activity and microorganisms and enzymes with nitrile hydrolase activity. The support may be, for example, made of polyurethane, activated carbon, lignocarbide, glass beads, silica gel, polyacrylamide, polyvinyl alcohol, carrageenan, alginate, agar, gelatin, or resin tubes. The microorganisms with nitrile hydratase activity are, for example, one or more microorganisms selected from the genera *Rhodococcus*, *Trichophyton*, *Pseudomonas*, *Arthrobacter*, *Bryophyton*, and *Streptomyces*, more preferably *Rhodococcus roseum*. Furthermore, the enzyme is, for example, an enzyme with nitrile hydratase activity produced by *Rhodococcus* bacteria, more preferably an enzyme produced by *Rhodococcus roseum*. Microorganisms or enzymes possessing nitrile hydrolase activity can convert acrylonitrile to acrylamide more efficiently than activated sludge through the hydration reaction. Furthermore, microorganisms possessing nitrile hydrolase activity are, for example, one or more microorganisms selected from the genera *Rhodococcus*, *Acinetobacter*, *Alcaligenes*, *Delftibacter*, *Pseudomonas*, *Trichomonas*, *Bacillus*, *Arthrobacter*, *Fusarium*, and *Klebsiella*, with *Rhodococcus*, *Acinetobacter*, *Alcaligenes*, and *Delftibacter* being more preferred. Microorganisms or enzymes possessing nitrile hydrolase activity can directly convert acrylonitrile to acrylate.

[0051] The first inlet (acrylonitrile inlet) In1 introduces acrylonitrile-containing waste gas and / or waste liquid into the housing 11. The first inlet In1 is located at one end of the housing 11 (e.g., the upper end) and is connected to the pump 13 via pipe P1. The pump 13 and the first inlet In1 are in airtight communication via pipe P1. Pipe P1 delivers waste gas and / or waste liquid from the pump 13 to the first inlet In1. The pump 13 delivers external waste gas and / or waste liquid into the housing 11 via pipe P1.

[0052] The second inlet (solvent inlet) In2 introduces the solvent for activating the aforementioned microorganisms or enzymes into the housing 11, supplying the solvent to the biocatalyst 12. The second inlet In2 is located at one end (e.g., the upper end) of the housing 11 and is connected to pipe P2. The second inlet In2 is in airtight communication with the outside via pipe P2, allowing external solvent to be supplied to the second inlet In2. Pipe P2 supplies external solvent to the second inlet In2. The solvent can be, for example, water. Water is used in the hydration reaction of acrylonitrile with microorganisms and enzymes possessing nitrile hydratase activity during acrylamide formation. Water is also used in the hydration reaction of acrylonitrile with microorganisms and enzymes possessing nitrile hydrolase activity during acrylate formation. Examples of water include pure water or aqueous solutions formed by dissolving acids, salts, etc. in water. Examples of acids include phosphoric acid, acetic acid, citric acid, boric acid, acrylic acid, formic acid, etc. Examples of salts include sodium salts, potassium salts, ammonium salts, etc., of the aforementioned acids. Specific examples of water are not particularly limited; for example, pure water, ultrapure water, tap water, etc., and buffer solutions such as Tris buffer, phosphate buffer, acetate buffer, citrate buffer, and borate buffer can be listed. The pH (at 20°C) of the raw water is 5-9, preferably close to neutral. The pH of the mixture of acrylonitrile, biocatalyst 12, and solvent is preferably 6-8. This is because the microorganisms proliferate rapidly and have high enzyme activity. The reaction temperature of the mixture of acrylonitrile, biocatalyst 12, and solvent is preferably 20°C-30°C. This is because the microorganisms proliferate rapidly and have high enzyme activity; therefore, when treating waste liquid containing acrylonitrile, if the solvent is already present in the waste liquid or the necessary components are added beforehand, the inlet port In2 may not be required.

[0053] Inlet ports In1 and In2 can also be shared. That is, the acrylonitrile converter 10 has a single inlet port from which waste liquid (waste gas) and solvent can be introduced.

[0054] Exhaust port Out1 discharges the waste gas from biocatalyst 12 through housing 11. Exhaust port Out1 is located at the other end of housing 11 (e.g., the lower end) and connected to pipe P3. Exhaust port Out1 communicates with the outside in an airtight manner through pipe P3, conveying the waste gas that has passed through biocatalyst 12 to the outside. The exhaust gas from exhaust port Out1 may also be discharged into the atmosphere depending on the residual amount of acrylonitrile contained in the exhaust gas. Alternatively, the exhaust gas from exhaust port Out1 may be reintroduced into the first inlet In1 of acrylonitrile converter 10, or further introduced into other waste gas converters for treatment. If only acrylonitrile-containing waste liquid is to be treated, exhaust port Out1 may not be provided.

[0055] Outlet 2 discharges the solvent supplied to biocatalyst 12 from housing 11. Acrylonitrile in the waste gas and / or waste liquid is converted to acrylamide by microorganisms or enzymes with nitrile hydratase activity when passing through and contacting biocatalyst 12. Alternatively, acrylonitrile in the waste gas and / or waste liquid is converted to acrylate by microorganisms or enzymes with nitrile hydrolase activity when passing through and contacting biocatalyst 12. The solvent supplied to biocatalyst 12 activates the microorganisms or enzymes and dissolves the acrylamide or acrylate. Therefore, the solvent discharged from outlet 2 of housing 11 contains acrylamide or acrylate.

[0056] The solvent discharged from the drain outlet Out2, in a state containing acrylamide or acrylate, is transported to the solvent processor 20 via piping P4. The drain outlet Out2 is located at the other end (e.g., the lower end) of the housing 11 and is connected to piping P4. The drain outlet Out2 is in airtight communication with the solvent processor 20 via piping P4, supplying the solvent containing acrylamide or acrylate to the biocatalyst 12 to the solvent processor 20.

[0057] The acrylonitrile converter 10 is preferably configured such that the first and second inlets In1 and In2 are located at the top (opposite to the direction of gravity), and the exhaust port Out1 and the drain port Out2 are located at the bottom (in the direction of gravity). Thus, the acrylonitrile converter 10 allows acrylonitrile and the solvent for activating the biocatalyst to pass relative to the biocatalyst 12 in the direction of gravity, smoothly converting it into a solution containing acrylamide and / or acrylate.

[0058] The acrylonitrile converter 10 also includes a temperature sensor Stmp, a temperature controller Ctmp, a temperature regulating unit Atmp, a pH sensor SpH, a pH controller CpH, and a pH adjuster inlet TpH.

[0059] Temperature sensor Stmp is located on pipe P4 near drain outlet Out2 to detect the temperature of the solvent passing through pipe P4. The temperature of the solvent just discharged from housing 11 is approximately equal to the temperature of biocatalyst 12. Therefore, it can be said that temperature sensor Stmp detects the temperature of biocatalyst 12.

[0060] The temperature controller Ctmp controls the temperature regulator Atmp based on the temperature measurement value from the temperature sensor Stmp. For example, when the temperature of the biocatalyst 12 is maintained at room temperature (approximately 25°C to approximately 30°C), the temperature controller Ctmp controls the temperature regulator Atmp to be turned on or off so that the temperature measurement value from the temperature sensor Stmp is equal to the room temperature (approximately 25°C to approximately 30°C).

[0061] A temperature regulating unit Atmp is provided on the outside or inside of the housing 11 to regulate the temperature of the biocatalyst 12. For example, the temperature regulating unit Atmp is a heater that raises the temperature of the biocatalyst 12 or a cooler that lowers the temperature of the biocatalyst 12. When the temperature regulating unit Atmp is a heater, it may be, for example, a heating wire. When the temperature regulating unit Atmp is a cooler, it may be, for example, a Peltier element. The temperature regulating unit Atmp is controlled by a temperature controller Ctmp to electrically raise or lower the temperature of the biocatalyst 12, thereby regulating the temperature of the biocatalyst 12 to a desired range (e.g., 20°C to 30°C). To regulate the temperature of the solvent injected into the housing, the temperature regulating unit Atmp may be provided on the outside or inside of the piping P2, or on the outside or inside of the solvent tank.

[0062] The pH sensor SPH is located on pipe P4 near the drain outlet Out2 to detect the pH value of the solvent passing through pipe P4. The solvent discharged from housing 11 has a pH value approximately equal to that of biocatalyst 12. Therefore, it can be said that the pH sensor SPH detects the pH value of biocatalyst 12.

[0063] The pH controller CpH controls the pH regulator inlet TpH based on the pH measurement value from the pH sensor SPH. For example, when maintaining the pH value of the biocatalyst 12 within a desired range (e.g., pH = 5 to 9), the pH controller CpH controls the opening or closing of the pH regulator inlet TpH so that the pH measurement value from the pH sensor SPH falls within the desired range (e.g., pH = 5 to 9, which is a range where microbial proliferation is vigorous and enzyme activity is high, preferably pH = 6 to 8).

[0064] The pH adjuster inlet contains a pH adjuster that adjusts the pH value of the biocatalyst 12. This pH adjuster is then introduced into the solvent within the pipe P2 of the predetermined inlet housing 11. The pH adjuster may be, for example, hydrochloric acid, sulfuric acid, phosphoric acid, or nitric acid when lowering the pH value, or sodium hydroxide, potassium hydroxide, calcium hydroxide, or ammonia when raising the pH value.

[0065] The solvent processor 20 includes a container 21, a gas supply unit 22, a third inlet In3, and a drain outlet Out3.

[0066] Container 21 stores activated sludge, which receives solvent from the waste gas and / or waste liquid converter 10 and treats acrylamide or acrylate contained in the solvent. The activated sludge preferably has amidase activity, which converts acrylamide into acrylate, etc. The activated sludge further decomposes the acrylate into other harmless organic and inorganic substances. Thus, acrylamide is detoxified and can be discharged externally. Alternatively, when using microorganisms and enzymes with nitrile hydrolase activity as the biocatalyst 12, acrylonitrile is directly converted into acrylate; therefore, the activated sludge only needs to convert the acrylate into harmless organic and inorganic substances. Thus, acrylonitrile treatment is relatively simple and can be completed in a short time.

[0067] The third inlet In3 introduces solvent from the acrylonitrile converter 10 via pipe P4, supplying the solvent into container 21. The third inlet In3 is located at one end (e.g., the upper end) of housing 11 and connected to pipe P4. Pipe P4 delivers solvent from waste gas and / or waste liquid converter 10 to the third inlet In3.

[0068] The gas supply unit 22 supplies gas (e.g., air) in the form of bubbles to the activated sludge within the container 21. Thus, the gas supply unit 22 aerates the activated sludge within the container 21. The activated sludge remains active for an extended period through aeration, enabling the efficient conversion of acrylamide into acrylate, or the efficient conversion of acrylate into harmless organic or inorganic substances.

[0069] A drain outlet Out3 is located at the top of container 21 and connected to piping P5. Drain outlet Out3 discharges acrylate, harmless organic or inorganic substances treated with the activated sludge in container 21 to the outside via piping P5. For example, drain outlet Out3 may transfer the liquid treated with activated sludge to equipment for separating activated sludge components via piping P5, or discharge the supernatant produced when activated sludge settles after aeration is temporarily stopped to the outside via piping P5. Since the activated sludge is aerated, container 21 is preferably not a closed container; its upper side is open or has an open section.

[0070] The liquid discharged from the Out3 outlet can also be discharged into rivers or other bodies of water after further disinfection and other treatments.

[0071] Figure 2 This is a diagram showing a processing example in the waste gas and / or waste liquid treatment apparatus of the first embodiment. Figure 3 It is a table showing the properties of substances generated in each treatment stage of the exhaust and / or waste liquid treatment unit.

[0072] like Figure 2As shown, waste gas and / or waste liquid containing acrylonitrile (AN) is introduced into an acrylonitrile converter 10, where it is converted into acrylamide (AA) through a hydration reaction using microorganisms or enzymes with nitrile hydration enzyme activity immobilized on a biocatalyst 12 within the acrylonitrile converter 10 (first step). Figure 3 It is known that acrylonitrile has a high Henry's coefficient and high volatility. Furthermore, acrylonitrile has low water solubility, making it non-water-soluble. In addition, acrylonitrile is designated as a hazardous substance under the Toxic and Hazardous Substances Control Law. That is, acrylonitrile is a volatile and non-water-soluble hazardous substance. Therefore, acrylonitrile needs to be converted into acrylamide in a closed atmosphere without external leakage. Based on this embodiment, the acrylonitrile converter 10 contacts waste gas and / or waste liquid with a biocatalyst 12 within a sealed, airtight housing 11. Therefore, acrylonitrile does not leak to the outside and can be converted into acrylamide in a closed atmosphere.

[0073] On the other hand, such as Figure 3 As shown, acrylamide has a very low Henry's coefficient compared to acrylonitrile, and a very high water solubility compared to acrylonitrile. Therefore, although acrylamide is designated as a hazardous substance by the toxicity law, it is non-volatile and water-soluble. Thus, a solvent (e.g., water) can easily dissolve acrylamide without dissolving acrylonitrile, and the acrylamide-containing solvent moves from the acrylonitrile converter 10 to the solvent processor 20 in a state where it is separated from acrylonitrile. Furthermore, the acrylamide-containing solvent is aerated in the activated sludge within the open container 21 of the solvent processor 20. However, acrylamide is non-volatile and water-soluble, so it is unlikely to volatilize and leak to the outside. Therefore, the solvent processor 20 can safely aerate acrylamide, a hazardous substance, in the open container 21 of the activated sludge. Thus, the solvent processor 20 treats the acrylamide in the solvent discharged from the acrylonitrile converter 10 (second step).

[0074] like Figure 2 As shown, acrylamide generates acrylate and ammonia through the hydration reaction of activated sludge with amidase activity.

[0075] Acrylates, such as Figure 3 As shown, it is not designated as a hazardous substance by the Toxic Substances Act and has lower toxicity compared to acrylonitrile and acrylamide. However, considering its toxicity to aquatic organisms, it is preferable to exclude it from liquids discharged into the environment as much as possible.

[0076] If the biocatalyst 12 is a microorganism and enzyme with nitrile hydrolase activity, then acrylonitrile is directly converted into acrylate in the acrylonitrile converter 10.

[0077] Thus, the waste gas and / or waste liquid treatment apparatus 1 of this embodiment can safely convert acrylonitrile into acrylamide or acrylate in a closed state in the acrylonitrile converter 10 (first step). Continuously, acrylamide can be efficiently converted into low-toxicity acrylates in the solvent processor 20 through aeration, and then the acrylates can be converted into harmless organic and inorganic substances (second step). As a result, according to this embodiment, acrylonitrile can be efficiently decomposed and treated.

[0078] In addition, in order to safely handle volatile acrylonitrile in a closed environment and to efficiently treat acrylamide and / or acrylates by aeration, it is preferable that the first and second processes are independent processes.

[0079] (Second Implementation)

[0080] Figure 4 This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the second embodiment. The waste gas and / or waste liquid treatment apparatus 1 of the second embodiment includes a plurality of acrylonitrile converters 10. The drain ports Out2 of the plurality of acrylonitrile converters 10 are commonly connected to the third inlet In3 of a solvent processor 20. That is, the plurality of acrylonitrile converters 10 are connected in parallel with respect to one solvent processor 20. The internal structure of each acrylonitrile converter 10 may be the same as that of the acrylonitrile converter 10 based on the first embodiment.

[0081] Solvent processor 20 introduces solvent from multiple acrylonitrile converters 10 for aeration in activated sludge. Thus, solvent processor 20 can further decompose the acrylamide or acrylate contained in the large quantities of solvent through microbial metabolism.

[0082] When the housing 11 of the acrylonitrile converter 10 and the biocatalyst 12 are elongated, microorganisms and enzymes are easily deactivated. In contrast, in the second embodiment, by connecting multiple acrylonitrile converters 10 in parallel with respect to one solvent processor 20, the length of the housing 11 and biocatalyst 12 of each acrylonitrile converter 10 can be shortened. As a result, the active state of microorganisms and enzymes can be maintained for a longer period of time.

[0083] Other structures in the second embodiment can be the same as the corresponding structures in the first embodiment. Therefore, the second embodiment can also achieve the same effects as the first embodiment.

[0084] (Third implementation method)

[0085] Figure 5This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the third embodiment. The waste gas and / or waste liquid treatment apparatus 1 of the third embodiment includes a plurality of acrylonitrile converters 10 and a plurality of solvent processors 20. The plurality of acrylonitrile converters 10 correspond to the plurality of solvent processors 20. The drain outlets Out2 of the plurality of acrylonitrile converters 10 are connected to the third inlet In3 of their respective solvent processors 20.

[0086] Furthermore, the exhaust port Out1 of the first acrylonitrile converter 10 is connected to the first inlet In1 of its subsequent second acrylonitrile converter 10 via pipe P3. That is, the multiple acrylonitrile converters 10 are connected in series via exhaust port Out1 and first inlet In1. The exhaust gas discharged from the first acrylonitrile converter 10 is treated again in the second acrylonitrile converter 10. Thus, even if acrylonitrile remains in the exhaust gas discharged from the first acrylonitrile converter 10, it can be converted into acrylamide or acrylate in the second acrylonitrile converter 10. In this way, the multiple acrylonitrile converters 10 can continuously treat the exhaust gas, ensuring that more acrylonitrile is converted from the exhaust gas into acrylamide or acrylate. Alternatively, the number of acrylonitrile converters 10 connected in series (continuously) can be three or more.

[0087] When the housing 11 and biocatalyst 12 of the exhaust gas converter 10 are elongated, microorganisms and enzymes are easily deactivated. In contrast, in the third embodiment, by connecting multiple acrylonitrile converters 10 in series, the length of the housing 11 and biocatalyst 12 of each acrylonitrile converter 10 can be shortened. As a result, the active state of microorganisms and enzymes can be maintained for a longer period of time.

[0088] The other structures in the third embodiment can be the same as the corresponding structures in the first embodiment. Therefore, the third embodiment can also achieve the same effects as the first embodiment.

[0089] (Fourth Implementation)

[0090] Figure 6A This is a block diagram showing a structural example of the waste gas and / or waste liquid treatment apparatus according to the fourth embodiment. The waste gas and / or waste liquid treatment apparatus 1 of the fourth embodiment is a combination of the second and third embodiments. Therefore, the waste gas and / or waste liquid treatment apparatus 1 includes a plurality of acrylonitrile converters 10, and the drain ports Out2 of the plurality of acrylonitrile converters 10 are commonly connected to the third inlet In3 of a solvent processor 20. That is, the plurality of acrylonitrile converters 10 are connected in parallel with respect to a solvent processor 20.

[0091] Furthermore, the exhaust port Out1 of the first acrylonitrile converter 10 is connected to the first inlet In1 of the subsequent second acrylonitrile converter 10 via pipe P3. That is, the multiple acrylonitrile converters 10 are connected in series via exhaust port Out1 and first inlet In1. Alternatively, the number of acrylonitrile converters 10 connected in series (connected in succession) may be three or more.

[0092] Other structures in the fourth embodiment can be the same as the corresponding structures in the second or third embodiments. Therefore, the fourth embodiment can achieve the same effects as the second and third embodiments.

[0093] (Fifth Implementation)

[0094] Figure 6B This is a block diagram showing a structural example of the wastewater treatment apparatus according to the fifth embodiment. The wastewater treatment apparatus 1 of the fifth embodiment includes a plurality of acrylonitrile converters 10 and a solvent processor 20. The drain outlet Out2 of the first acrylonitrile converter 10 is connected to the first inlet In1 of the next-stage second acrylonitrile converter 10 via a pipe P3. That is, the plurality of acrylonitrile converters 10 are connected in series via the drain outlet Out2 and the first inlet In1. The effluent discharged from the first acrylonitrile converter 10 is treated again in the second acrylonitrile converter 10. Thus, even if acrylonitrile remains in the effluent discharged from the first acrylonitrile converter 10, the acrylonitrile can be converted into acrylamide or acrylate in the second acrylonitrile converter 10. In this way, the plurality of acrylonitrile converters 10 can continuously treat the wastewater to ensure that more acrylonitrile is converted into acrylamide or acrylate from the wastewater. In addition, the plurality of acrylonitrile converters 10 connected in series (continuously) may be three or more.

[0095] The drain port Out2 of the final acrylonitrile converter 10 is connected to the third inlet In3 of a solvent processor 20. That is, multiple acrylonitrile converters 10 are connected in series with respect to a solvent processor 20. The internal structure of each acrylonitrile converter 10 may be the same as that of the acrylonitrile converter 10 based on the first embodiment, but it may also lack a drain port Out1.

[0096] Example

[0097] The present invention will be specifically described below with reference to comparative examples and embodiments.

[0098] Acrylonitrile-containing waste gas was prepared by evaporating it through an aqueous acrylonitrile solution and then supplied to the treatment devices of the comparative examples and embodiments. Specifically, 50 mL of a 2% by weight aqueous acrylonitrile solution was placed in a sealed glass bottle, and aeration was carried out through a tube inserted into the aqueous acrylonitrile solution to cause the acrylonitrile to evaporate. The gas phase in the glass bottle was then connected to the pharmaceutical tube and flowed into the respective treatment devices.

[0099] It should be noted that, Figure 9 The acrylonitrile content in the provided exhaust gas is calculated from the change in acrylonitrile content in the acrylonitrile aqueous solution before and after venting. The acrylonitrile content in the acrylonitrile aqueous solution is determined by high-performance liquid chromatography (HPLC). The acrylonitrile content in the waste liquid, the acrylonitrile content in the discharged effluent, the acrylamide content, and the acrylate content are all determined by HPLC. The amount of volatile or unreacted acrylonitrile is calculated by subtracting the amount of acrylamide and acrylate in the discharged effluent from the acrylonitrile content in the provided exhaust gas and waste liquid.

[0100] (Comparative Example 1)

[0101] Figure 7 This is a schematic diagram showing the treatment apparatus based on Comparative Example 1. In treatment apparatus 200, activated sludge is stored in an open container, and acrylonitrile-containing wastewater is introduced for aeration. That is, treatment apparatus 200 is an activated sludge wastewater treatment apparatus using the conventional activated sludge process.

[0102] However, acrylonitrile is volatile and not water-soluble, so it volatilizes in the activated sludge after aeration and leaks to the outside.

[0103] Specifically, such as Figure 9 As shown, when the amount of acrylonitrile (AN) in the wastewater (aqueous solution) supplied to the activated sludge was approximately 7.5 mmol, the amount of acrylonitrile volatilized was approximately 4.0 mmol. After treatment, no acrylonitrile was detected in the effluent discharged from the treatment unit. Only approximately 0.2 mmol of acrylamide and approximately 1.5 mmol of acrylate were detected in the effluent discharged from the treatment unit.

[0104] (Compare Examples 2 and 3)

[0105] Figure 8This is a schematic diagram showing the treatment apparatus based on Comparative Examples 2 and 3. In the treatment apparatus 300, a catalyst 312, formed by immobilizing conventional activated sludge on a carrier, is housed within the casing. In Comparative Example 2, acrylonitrile-containing waste gas is the target for treatment, and a solvent is introduced into the casing of the treatment apparatus 300 to activate the activated sludge. In Comparative Example 3, acrylonitrile-containing waste liquid is the target for treatment, and no solvent is introduced into the treatment apparatus 300. Other structures and conditions are the same for Comparative Examples 2 and 3.

[0106] Waste gas and / or waste liquid are introduced into the housing of treatment unit 300, where they come into contact with the catalyst and pass through. Acrylonitrile in the waste gas and / or waste liquid in contact with the catalyst within the housing is partially converted into metabolites of acrylamide and below using activated sludge. The water-soluble metabolites of acrylamide and below are dissolved in the waste liquid within the housing and discharged from the drain outlet. Unreacted acrylonitrile is discharged outside the housing, either partially dissolved in the solvent or contained in the waste gas.

[0107] In this experiment, the catalyst 312, formed by immobilizing activated sludge on a carrier, used a polyurethane sponge approximately 1 cm square. A polyurethane sponge with a bulk volume of 150 mL was added to 100 mL of activated sludge, and after shaking and stirring for 2-3 days, the polyurethane sponge was recovered, washed with water, and then used as catalyst 312 to fill the shell.

[0108] In this treatment device 300, the volatilization of acrylonitrile is almost zero because the shell is sealed. However, in the activated sludge, acrylonitrile is not efficiently converted into acrylamide, and a large amount is discharged in an unreacted state.

[0109] Specifically, in Comparative Example 2, which treats acrylonitrile-containing waste gas, such as Figure 9 As shown, approximately 2.8 mmol of acrylonitrile was emitted as unreacted gas, and no acrylonitrile was detected in the effluent from the treatment unit. Only approximately 0.2 mmol of acrylamide and approximately 3.5 mmol of acrylate were detected.

[0110] In addition, in Comparative Example 3, which treats acrylonitrile-containing wastewater, such as Figure 9 As shown, approximately 1.9 mmol of residual acrylonitrile was detected in the effluent from the acrylonitrile converter 10. Approximately 0.6 mmol of acrylamide was detected. Approximately 2.5 mmol of acrylate was detected.

[0111] Thus, although Comparative Examples 2 and 3 showed good performance with less volatilized or unreacted acrylonitrile than Comparative Example 1, a large amount of acrylamide or acrylate remained in the discharged effluent, making it impossible to release directly into the environment.

[0112] (Example 1)

[0113] use Figure 1 The first embodiment shown in the schematic diagram treats acrylonitrile-containing waste gas. The biocatalyst 12 is not activated sludge, but a catalyst formed by immobilizing microorganisms or enzymes with nitrile hydratase activity (e.g., Rhodococcus bacteria, more specifically Rhodococcus roseum, and even more specifically Rhodococcus roseum strain J1 (accession number: FERM-BP-1478)) on a carrier.

[0114] The carrier for the biocatalyst 12 in this experiment was a polyurethane sponge approximately 1 cm square, similar to that in Comparative Example 2. Furthermore, 100 mL of microbial culture medium prepared by the following method was used instead of activated sludge to prepare the biocatalyst 12, following the same method as in Comparative Example 2.

[0115] (Cultivation of microorganisms with nitrile hydratase activity)

[0116] Rhodococcus roseum strain J1 (preservation number: FERM-BP-1478) was inoculated into 5 mL of LB medium and cultured using a shaking incubator at 30°C and 120 rpm. After confirming proliferation, it was subcultured in 100 mL of medium (pH 7.0) containing 2% glucose, 1% urea, 0.5% peptone, 0.3% yeast extract, and 0.01% cobalt chloride hexahydrate, and cultured at 30°C and 120 rpm to obtain a culture medium containing nitrile hydratase activity.

[0117] exist Figure 9 In the experimental results showing acrylonitrile-containing waste gas, the amount of unreacted acrylonitrile emitted as gas is approximately 0.2 mmol, which is very small. The intermediate effluent is from... Figure 1 The solvent discharged from the acrylonitrile converter 10 (the solvent in pipe P4) was not detected in the intermediate effluent. Approximately 7.2 mmol of acrylamide was detected. Approximately 0.1 mmol of acrylate was detected. These results indicate that most of the acrylonitrile in the exhaust gas supplied to the acrylonitrile converter 10 is converted to acrylamide by the biocatalyst 12.

[0118] Subsequently, the intermediate effluent containing acrylamide was supplied to solvent processor 20 and aerated in activated sludge, thereby preventing the detection of acrylonitrile and acrylamide in the final effluent discharged from solvent processor 20. Approximately 0.2 mmol of acrylate was detected. This result indicates that most of the acrylamide in the intermediate effluent supplied to solvent processor 20 is converted into substances in a metabolic pathway preceding acrylate through activated sludge.

[0119] (Example 2)

[0120] Except that the acrylonitrile-containing wastewater was treated without using a solvent, the experiment was conducted using the same method as in Example 1. Approximately 0.2 mmol of acrylonitrile remained in the intermediate effluent, indicating a very small amount of acrylonitrile that could not be completely converted by biocatalyst 12. Approximately 7.2 mmol of acrylamide was detected. Approximately 0.1 mmol of acrylate was detected. These results indicate that most of the acrylonitrile in the waste gas supplied to the acrylonitrile converter 10 was converted to acrylamide by biocatalyst 12.

[0121] Subsequently, the intermediate effluent containing acrylamide was supplied to solvent processor 20, where it was aerated in activated sludge. As a result, acrylonitrile and acrylamide were not detected in the final effluent discharged from solvent processor 20. Approximately 0.1 mmol of acrylate was detected. This result indicates that most of the acrylamide in the intermediate effluent supplied to solvent processor 20 is metabolized into acrylate through activated sludge.

[0122] (Example 3)

[0123] The biocatalyst 12 of Example 3 was prepared using the same method as in Example 1, except that granular activated carbon was used in the support. Experiments were conducted using the same method as in Example 2, except that the acrylonitrile content in the acrylonitrile-containing waste liquid was approximately 4.2 mmol. No residual acrylonitrile was detected in the intermediate effluent. Approximately 4.1 mmol of acrylamide was detected. Approximately 0.1 mmol of acrylate was detected. These results indicate that most of the acrylonitrile in the waste gas supplied to the acrylonitrile converter 10 was converted to acrylamide by the biocatalyst 12.

[0124] Subsequently, the intermediate effluent containing acrylamide was supplied to solvent processor 20 and aerated in activated sludge. As a result, no acrylonitrile, acrylamide, or acrylate was detected in the final effluent discharged from solvent processor 20. This result indicates that the acrylamide in the intermediate effluent supplied to solvent processor 20 is a metabolite before it is converted into acrylate through activated sludge.

[0125] (Example 4)

[0126] In Example 4, the biocatalyst 12 is a catalyst containing microorganisms and enzymes with nitrile hydrolase activity, replacing microorganisms or enzymes with nitrile hydratase activity. The support is bamboo charcoal broken into 5-10 mm pieces. The waste liquid supplied to the acrylonitrile converter 10 contains 3300 ppm acrylonitrile and is continuously supplied using a tubular pump. The feed rate is 18 mL / hr. The reaction is carried out indoors at a temperature maintained between 24 and 26°C.

[0127] In the solvent processor 20, in addition to activated sludge, 0.1 g / L potassium dihydrogen phosphate, 0.2 g / L dipotassium hydrogen phosphate, 0.05 g / L magnesium sulfate heptahydrate, 0.05 g / L sodium chloride, 0.004 g / L calcium chloride dihydrate, and 0.0005 g / L ferric sulfate heptahydrate are added, and a decomposition reaction is carried out at 30°C. Other structures in Example 4 can be the same as any one of the structures in Examples 1 to 3.

[0128] (Cultivation of microorganisms with nitrile hydrolase activity)

[0129] One species of Acinetobacter, one species of Alcaligenes, and one species of Delftobacterium were isolated from wastewater samples from Toray Industries, Inc.'s Chiba plant. Each species was inoculated into 5 mL of LB medium and cultured in a shaking incubator at 30°C and 120 rpm. Subcultures were then performed in 100 mL of LB medium and cultured at 30°C and 120 rpm, yielding a culture medium containing nitrile hydrolase activity.

[0130] exist Figure 9 In the experimental results of the acrylonitrile-containing wastewater shown, acrylonitrile was not detected in the intermediate effluent. Acrylamide was also not detected in the intermediate effluent. Approximately 13 mmol of acrylate was detected in the intermediate effluent. These results indicate that most of the acrylonitrile in the wastewater supplied to the acrylonitrile converter 10 is directly converted to acrylate by the biocatalyst 12 in the first stage of the acrylonitrile converter 10. Furthermore, it can be assumed that a portion of the acrylate is further metabolized and used for microbial growth.

[0131] Subsequently, the intermediate effluent containing acrylate was supplied to solvent processor 20 and aerated in activated sludge, thereby eliminating the detection of acrylonitrile and acrylate in the final effluent discharged from solvent processor 20. This result indicates that most of the acrylate in the intermediate effluent supplied to solvent processor 20 is converted into substances from the metabolic pathway prior to acrylate formation via activated sludge.

[0132] so, Figure 1 The waste gas and / or waste liquid treatment device of the first embodiment shown in the schematic diagram can efficiently convert acrylonitrile into acrylamide or acrylate in the acrylonitrile converter 10, and then efficiently convert acrylamide into acrylate in the solvent processor 20, or convert acrylate into harmless organic or inorganic substances.

[0133] Several embodiments of the present invention have been described, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments or variations thereof are included in the scope or spirit of the invention, as well as in the scope of the invention as described in the claims and its equivalents.

[0134] Symbol Explanation

[0135] 1. Exhaust gas and / or treatment equipment

[0136] 10 Acrylonitrile Converter

[0137] 11. Shell

[0138] 12 Biocatalysts

[0139] 13 pumps

[0140] In1 First Inlet Port

[0141] In2 Second Inlet Port

[0142] Out1 Exhaust Port

[0143] Out2 drain port

[0144] Stmp temperature sensor

[0145] Ctmp Temperature Controller

[0146] Atmp Temperature Control Unit

[0147] SpH pH sensor

[0148] CpH pH controller

[0149] TpH pH adjuster inlet

[0150] 20 Solvent Processors

[0151] 21 Containers

[0152] 22 Gas Supply Department

[0153] In3 Third Inlet Port

[0154] Out3 drain port

Claims

1. A method for treating waste gas or waste liquid, comprising a first step of contacting acrylonitrile, a biocatalyst, and a solvent for activating the biocatalyst in the waste gas or waste liquid to convert them into acrylamide and / or acrylate, and a second step of decomposing acrylamide and / or acrylate.

2. The waste gas or waste liquid treatment device according to claim 1, wherein the biocatalyst is one or more selected from microorganisms and enzymes with nitrile hydratase activity and microorganisms and enzymes with nitrile hydrolase activity.

3. The waste gas or waste liquid treatment device according to claim 2, wherein the microorganism with nitrile hydratase activity is selected from one or more of the genera Rhodococcus and Trichophyton.

4. In the waste gas or waste liquid treatment device according to claim 2, the microorganism with nitrile hydratase activity is Rhodococcus roseum.

5. The waste gas or waste liquid treatment device according to claim 2, wherein the microorganism having nitrile hydrolase activity is selected from one or more of the genera Rhodococcus, Acinetobacter, Alcaligenes, and Delft.

6. The waste gas or waste liquid treatment method according to claim 1, wherein the first step and the second step are separate and independent steps.

7. The waste gas or waste liquid treatment method according to claim 1, wherein the reaction temperature in the first step is 20~30℃.

8. The waste gas or waste liquid treatment method according to claim 1, wherein the pH value of the acrylonitrile, the biocatalyst and the solvent in the first step is pH 6 to 8.

9. The waste gas or waste liquid treatment method according to claim 1, wherein the gas flow rate of the acrylonitrile, the biocatalyst and the solvent in the first step is less than 5 vvm.

10. The waste gas or waste liquid treatment method according to claim 1, wherein the acrylonitrile concentration in the waste gas or waste liquid is 10,000 ppm.

11. The waste gas or waste liquid treatment method according to claim 1, wherein the first step is a step of converting the acrylonitrile and the solvent of the activated biocatalyst into a solution containing acrylamide and / or acrylate by passing the biocatalyst along the direction of gravity.

12. A waste gas or waste liquid treatment device, comprising an acrylonitrile converter and a processor, The acrylonitrile converter includes a housing for containing an immobilized biocatalyst, an acrylonitrile inlet for introducing waste gas or waste liquid containing acrylonitrile into the housing, a solvent inlet for introducing a solvent to activate the immobilized biocatalyst, and a drain outlet for discharging a solution containing acrylamide and / or acrylate generated from acrylonitrile through the immobilized biocatalyst from the housing. The processor processes the solution containing the acrylamide and / or the acrylate discharged from the acrylonitrile converter.

13. The waste gas or waste liquid treatment device according to claim 12, wherein the solvent inlet is the acrylonitrile inlet.

14. The waste gas or waste liquid treatment device according to claim 12, wherein the acrylonitrile converter is a fixed-layer catalytic reactor in which the immobilized biocatalyst is filled in the housing.

15. The waste gas or waste liquid treatment device according to claim 12, wherein the acrylonitrile inlet and the solvent inlet are disposed at the upper end of the housing.

16. The waste gas or waste liquid treatment apparatus according to claim 12, wherein the acrylonitrile converter has an exhaust port for discharging the waste gas after passing through the immobilized biocatalyst from the housing.

17. The waste gas or waste liquid treatment device according to claim 12, wherein the carrier of the immobilized biocatalyst is activated carbon or lignocarbon.

18. The waste gas or waste liquid treatment apparatus according to claim 12, wherein the acrylonitrile converter further comprises: Temperature sensor for detecting the temperature of the immobilized biocatalyst Temperature control unit for adjusting the temperature of the immobilized biocatalyst, and A temperature controller that controls the temperature regulation unit based on temperature measurements from the temperature sensor.

19. The waste gas or waste liquid treatment apparatus according to claim 12, wherein the acrylonitrile converter further comprises: A pH sensor for detecting the pH value of the immobilized biocatalyst. A pH adjuster for adjusting the pH value of the immobilized biocatalyst is introduced into the pH adjuster inlet of the solvent, and... The pH controller controls the pH adjuster inlet based on the pH measurement value from the pH sensor.

20. The waste gas or waste liquid treatment apparatus according to claim 12, wherein the processor stores activated sludge for treating acrylamide and / or acrylate.

21. The waste gas or waste liquid treatment device according to claim 20, wherein the activated sludge has amidase activity.

Images