A method for treating thiophanate-methyl production wastewater
By combining copper sulfate pentahydrate catalytic wet oxidation with modified catalyst photocatalysis and three-stage membrane distillation, the problem of low COD and ammonia nitrogen removal rates in methyl thiophanate production wastewater in existing technologies has been solved, achieving a highly efficient wastewater treatment effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI GUANGXIN AGROCHEM
- Filing Date
- 2024-11-13
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies for treating thiophanate-methyl production wastewater have low COD and ammonia nitrogen removal rates, and the equipment is complex and expensive.
Copper sulfate pentahydrate was used for wet oxidation combined with a modified catalyst for photocatalysis, followed by three-stage membrane distillation. The modified catalyst consisted of a nano-silver-surfactant complex and modified activated carbon. The treatment efficiency was improved by utilizing the plasmonic resonance effect of nano-silver and the positive charge adsorption of the modified catalyst.
It significantly improved the removal rates of COD and ammonia nitrogen in the wastewater from thiophanate-methyl production, reaching 96.3%-98.6% and 87.5%-92.1% respectively, and reduced the concentration of organic matter and ammonia nitrogen in the wastewater.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pesticide wastewater treatment technology, specifically relating to a method for treating wastewater from the production of thiophanate-methyl. Background Technology
[0002] Thiophanate-methyl, also known as methyl thiophanate (or simply thiophanate-methyl), is a broad-spectrum systemic fungicide with low toxicity, exhibiting systemic, preventative, and curative effects. Thiophanate-methyl has both curative and preventative effects against a variety of diseases, and is therefore widely used for the control of diseases in fruit trees, vegetables, flowers, wheat, and other crops.
[0003] Currently, the main synthetic route for methyl thiophanate uses methyl chloroformate and sodium thiocyanate as raw materials, and N,N-dimethylaniline as a catalyst. Methyl isothiocyanate is first synthesized, and then condensed with o-phenylenediamine to produce methyl thiocyanate. The wastewater mainly originates from the methyl isothiocyanate synthesis, product washing, and solvent recovery stages. The wastewater primarily contains organic compounds such as N,N-dimethylaniline, thiocarbamate, methyl thiophanate, and its isomers. The pH value is approximately 3-5, the COD concentration is as high as 20,000-40,000 mg / L, and the sodium chloride content is approximately 20% (based on wastewater mass). This wastewater is characterized by a strong odor, high COD, high salinity, and high toxicity, classifying it as high-concentration, recalcitrant pesticide wastewater.
[0004] Currently, thiophanate-methyl wastewater is generally treated by incineration, but the equipment used in incineration is complex and expensive. Patent publication number CN105906100B discloses a method for treating thiophanate-methyl production wastewater, including the following steps: macroporous resin adsorption treatment, catalytic wet oxidation, photocatalysis, and membrane distillation. The catalytic wet oxidation uses a supported catalyst or a soluble transition metal salt. The supported catalyst carrier is titanium dioxide, and the active ingredient is at least one of ruthenium, rhodium, and palladium. The soluble transition metal salt is at least one of iron, copper, cobalt, nickel, and manganese salts. In the photocatalysis, the catalyst used is at least one of titanium dioxide, zinc oxide, tin oxide, zirconium dioxide, and cadmium sulfide. However, the removal rates of COD and ammonia nitrogen in the thiophanate-methyl wastewater treated by this method are still low. Summary of the Invention
[0005] In order to address the problem that the removal rates of COD and ammonia nitrogen in methyl thiophanate wastewater after treatment by existing technologies are still relatively low, the present invention aims to provide a method for treating methyl thiophanate production wastewater.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] A method for treating wastewater from methyl thiophanate production includes the following steps:
[0008] Step S1: Add copper sulfate pentahydrate to the methyl thiophanate production wastewater, and then pass it into a catalytic wet oxidation reactor to react and obtain treatment solution I;
[0009] The ratio of methyl thiophanate production wastewater to copper sulfate pentahydrate is 1L:2-5g.
[0010] In this step, copper ions in copper sulfate pentahydrate can undergo complexation or redox reactions with organic matter in wastewater, thereby altering the structure and properties of the organic matter and making it more susceptible to oxidative degradation.
[0011] Step S2: Add the modified catalyst to treatment solution I and perform photocatalysis to obtain treatment solution II;
[0012] The ratio of treatment solution I to modified catalyst is 1L:1-2g.
[0013] Step S3: Processing solution II is subjected to three-stage membrane distillation to obtain processing solution III, thus completing the processing.
[0014] Further, before step S1, a 30wt% sodium hydroxide aqueous solution is added to the wastewater to adjust the pH of the wastewater to 7-8.
[0015] Furthermore, in step S1, the oxidant for the catalytic wet oxidation reaction is air or oxygen, and the flow rate of air or oxygen is 40 L / h.
[0016] Furthermore, in step S1, the temperature of the catalytic wet oxidation reaction is 210-260℃; the reaction pressure is 2-6MPa; and the reaction time is 2-2.5h.
[0017] Furthermore, in step S2, the preparation steps of the modified catalyst are as follows:
[0018] Step A1: Add activated carbon to a 1 g / L nano silver-surfactant composite solution, stir at 160-200 r / min for 3-4 h, then wash with water and dry to obtain modified activated carbon.
[0019] The ratio of 1 g / L nano-silver-surfactant composite solution to activated carbon is 100-140 mL: 10 g.
[0020] Step A2: Mix anhydrous ethanol, tetrabutyl titanate, and glacial acetic acid to obtain mixture A; add modified activated carbon to mixture A, followed by an 80% (v / v) aqueous ethanol solution to obtain a gel; allow the gel to stand for 8 hours and then load it into a reaction vessel for hydrothermal reaction at 120-130℃ for 12 hours. After cooling to room temperature, remove the gel, wash it three times with deionized water, filter it, dry it at 90℃ for 12 hours, and grind it to obtain the modified catalyst.
[0021] The volume ratio of anhydrous ethanol, tetrabutyl titanate, and glacial acetic acid in mixture A is 2-2.5:1-2:0.15-0.25; the volume ratio of mixture A, modified activated carbon, and ethanol aqueous solution is 30-35mL:2.5-3g:13-18mL.
[0022] Furthermore, the preparation method of the nano-silver-surfactant complex solution is as follows:
[0023] A solution of 0.06 mol / L (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide, 0.01 mol / L silver nitrate, and 0.5 mol / L sodium borohydride was stirred until homogeneous and reacted at room temperature for 8 h to obtain a nano-silver-surfactant composite solution.
[0024] The volume ratio of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide aqueous solution, silver nitrate aqueous solution, and sodium borohydride aqueous solution is 5:5:1.
[0025] In the above steps, silver nitrate ionizes into silver ions in water, and sodium borohydride, as a strong reducing agent, reduces the silver ions to silver atoms, thereby forming silver nanoparticles. The thiol group in (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide has a strong interaction with silver, thus stabilizing the silver nanoparticles and preventing their aggregation, which helps to form a uniformly dispersed silver nanoparticle-surfactant complex solution.
[0026] Furthermore, in step S2, the photocatalysis time is 0.5-1 h; the photocatalysis wavelength is 400 nm.
[0027] Furthermore, in step S3, the three-stage membrane distillation system uses a polytetrafluoroethylene hollow fiber membrane with a pore size of 0.1-1 μm, a porosity of 70-90%, and a membrane thickness of 0.1-0.25 mm.
[0028] The beneficial effects of this invention are:
[0029] 1. This invention combines modified activated carbon and nano-titanium dioxide to form a modified catalyst, wherein the modified activated carbon contains a nano-silver-surfactant complex. Combining nano-titanium dioxide with the adsorbent support modified activated carbon not only significantly improves the dispersibility of nanoparticles and increases the contact area with the target pollutants, but also achieves nanoparticle immobilization, improving photocatalytic efficiency and reducing the COD and ammonia nitrogen concentrations in methyl thiophanate production wastewater. Furthermore, the silver nanoparticles in the nano-silver-surfactant complex exhibit a plasmon resonance effect under visible light irradiation. When silver nanoparticles and nano-titanium dioxide are combined, the transfer of "hot" electrons enhances the photocatalytic activity of the modified catalyst, improving catalytic efficiency and further reducing the COD and ammonia nitrogen concentrations in methyl thiophanate production wastewater.
[0030] 2. The nano-silver-surfactant composite contains quaternary ammonium salt groups, which give the modified catalyst a positive charge. Methyl thiocyanate and other surfactants containing SCN... - Positively charged modified catalysts can efficiently adsorb SCN under electrostatic interaction. - This reduces the organic matter in the wastewater, and lowers the COD value and ammonia nitrogen concentration in the wastewater from the production of thiophanate-methyl. Detailed Implementation
[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0032] The wastewater from the methyl thiophanate production process of this invention mainly contains organic compounds such as N,N-dimethylaniline, thioisoester, methyl thiocyanate, and sulfides. Measurements show that the wastewater has a pH of 2-3, a COD of 19000-20000 mg / L, and an ammonia nitrogen content of 125-136 mg / L.
[0033] Preparation Example 1
[0034] The preparation method of the nano-silver-surfactant complex solution in this preparation example is as follows:
[0035] 5 mL of 0.06 mol / L (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide aqueous solution, 5 mL of 0.01 mol / L silver nitrate aqueous solution, and 1 mL of 0.5 mol / L sodium borohydride aqueous solution were stirred until homogeneous and reacted at room temperature for 8 h to obtain a nano-silver-surfactant composite solution.
[0036] Preparation Example 2
[0037] The preparation method of the nano-silver-surfactant complex solution in this preparation example is as follows:
[0038] 5 mL of 0.06 mol / L dodecyltrimethylammonium bromide aqueous solution, 5 mL of 0.01 mol / L silver nitrate aqueous solution, and 1 mL of 0.5 mol / L sodium borohydride aqueous solution were stirred until homogeneous and reacted at room temperature for 8 h to obtain a nano-silver-surfactant composite solution.
[0039] Preparation Example 3
[0040] The method for preparing the modified catalyst in this preparation example is as follows:
[0041] Step A1: Add 10g of activated carbon to 100mL of 1g / L nano silver-surfactant composite solution, stir at 160r / min for 3h, then wash with water and dry to obtain modified activated carbon.
[0042] Step A2: Mix 20 mL of anhydrous ethanol, 10 mL of tetrabutyl titanate, and 1.5 mL of glacial acetic acid to obtain mixture A; add 2.5 g of modified activated carbon to 30 mL of mixture A, followed by 13 mL of 80% (v / v) ethanol aqueous solution to obtain a gel; allow the gel to stand for 8 h and then place it in a reaction vessel, perform a hydrothermal reaction at 120 °C for 12 h, cool to room temperature, remove and wash three times with deionized water, filter, dry at 90 °C for 12 h, and grind to obtain the modified catalyst.
[0043] The preparation method of the nano-silver-surfactant complex solution is the same as that in Preparation Example 1.
[0044] Preparation Example 4
[0045] The method for preparing the modified catalyst in this preparation example is as follows:
[0046] Step A1: Add 10g of activated carbon to 120mL of 1g / L nano silver-surfactant composite solution, stir at 180r / min for 3.5h, then wash with water and dry to obtain modified activated carbon.
[0047] Step A2: Mix 23 mL of anhydrous ethanol, 15 mL of tetrabutyl titanate, and 2 mL of glacial acetic acid to obtain mixture A; add 2.75 g of modified activated carbon to 32 mL of mixture A, followed by 16 mL of 80% ethanol aqueous solution to obtain a gel; allow the gel to stand for 8 hours and then place it in a reaction vessel for hydrothermal reaction at 125℃ for 12 hours. After cooling to room temperature, remove the gel, wash it three times with deionized water, filter it, dry it at 90℃ for 12 hours, and grind it to obtain the modified catalyst.
[0048] The preparation method of the nano-silver-surfactant complex solution is the same as that in Preparation Example 1.
[0049] Preparation Example 5
[0050] The method for preparing the modified catalyst in this preparation example is as follows:
[0051] Step A1: Add 10g of activated carbon to 140mL of 1g / L nano silver-surfactant composite solution, stir at 200r / min for 4h, then wash with water and dry to obtain modified activated carbon.
[0052] Step A2: Mix 25 mL of anhydrous ethanol, 20 mL of tetrabutyl titanate, and 2.5 mL of glacial acetic acid to obtain mixture A; add 3 g of modified activated carbon to 35 mL of mixture A, followed by 18 mL of 80% ethanol aqueous solution to obtain a gel; allow the gel to stand for 8 hours and then load it into a reaction vessel, perform a hydrothermal reaction at 130℃ for 12 hours, cool to room temperature, remove and wash three times with deionized water, filter, dry at 90℃ for 12 hours, and grind to obtain the modified catalyst.
[0053] The preparation method of the nano-silver-surfactant complex solution is the same as that in Preparation Example 1.
[0054] Preparation Example 6
[0055] The preparation method of the modified catalyst in this preparation example differs from that in Preparation Example 3 in that the "1g / L nano silver-surfactant complex solution" in Preparation Example 3 is replaced with the "product prepared in Preparation Example 2", while the other raw materials, processes and parameters are the same as in Preparation Example 3.
[0056] Preparation Example 7
[0057] The preparation method of the modified catalyst in this preparation example differs from that in Preparation Example 3 in that the "1 g / L nano silver-surfactant complex solution" in Preparation Example 3 is replaced with "1 g / L (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide aqueous solution", while the other raw materials, processes and parameters are the same as in Preparation Example 3.
[0058] Preparation Example 8
[0059] The method for preparing the modified catalyst in this preparation example is as follows:
[0060] Mix 20 mL of anhydrous ethanol, 10 mL of tetrabutyl titanate, and 1.5 mL of glacial acetic acid to obtain mixture A; add 2.5 g of activated carbon to 30 mL of mixture A, followed by 13 mL of 80% ethanol aqueous solution to obtain a gel; allow the gel to stand for 8 h and then place it in a reaction vessel, perform a hydrothermal reaction at 120 °C for 12 h, cool to room temperature, remove and wash three times with deionized water, filter, dry at 90 °C for 12 h, and grind to obtain the modified catalyst.
[0061] Example 1
[0062] This embodiment provides a method for treating wastewater from the production of methyl thiophanate, including the following steps:
[0063] Step S1: Add 30wt% sodium hydroxide aqueous solution to the wastewater to adjust the pH to 7-8. Add 2g of copper sulfate pentahydrate to 1L of thiophanate-methyl production wastewater, then pass it into a catalytic wet oxidation reactor to obtain treated solution I. The oxidant for the catalytic wet oxidation reaction is air or oxygen, with a flow rate of 40L / h; the temperature of the catalytic wet oxidation reaction is 210℃; the reaction pressure is 2MPa; and the reaction time is 2h.
[0064] Step S2: Add 1g of modified catalyst to 1L of treatment solution I and perform photocatalysis for 0.5h at a wavelength of 400nm to obtain treatment solution II;
[0065] Step S3: The treatment solution II is distilled through a polytetrafluoroethylene hollow fiber membrane (the membrane has a pore size of 0.1 μm, a porosity of 70-90%, and a membrane thickness of 0.1 mm) to obtain the treatment solution III, thus completing the treatment.
[0066] The preparation steps for the modified catalyst are the same as in Example 3.
[0067] The COD removal rate in this embodiment was measured to be 96.3%, and the ammonia nitrogen removal rate was 87.5%.
[0068] Example 2
[0069] This embodiment provides a method for treating wastewater from the production of methyl thiophanate, including the following steps:
[0070] Step S1: Add 30wt% sodium hydroxide aqueous solution to the wastewater to adjust the pH to 7-8. Add 3g of copper sulfate pentahydrate to 1L of thiophanate-methyl production wastewater, then pass it into a catalytic wet oxidation reactor to obtain treated solution I. The oxidant for the catalytic wet oxidation reaction is air or oxygen, with a flow rate of 40L / h; the temperature of the catalytic wet oxidation reaction is 240℃; the reaction pressure is 4MPa; and the reaction time is 2.4h.
[0071] Step S2: Add 1.5g of modified catalyst to 1L of treatment solution I and perform photocatalysis for 0.8h at a wavelength of 400nm to obtain treatment solution II;
[0072] Step S3: Treatment solution II is distilled through a polytetrafluoroethylene hollow fiber membrane (the membrane has a pore size of 0.4 μm, a porosity of 70-90%, and a membrane thickness of 0.2 mm) to obtain treatment solution III, thus completing the treatment.
[0073] The preparation steps for the modified catalyst are the same as in Example 4.
[0074] The COD removal rate in this embodiment was measured to be 97.6%, and the ammonia nitrogen removal rate was 89.2%.
[0075] Example 3
[0076] This embodiment provides a method for treating wastewater from the production of methyl thiophanate, including the following steps:
[0077] Step S1: Add 30wt% sodium hydroxide aqueous solution to the wastewater to adjust the pH to 7-8. Add 5g of copper sulfate pentahydrate to 1L of thiophanate-methyl production wastewater, then pass it into a catalytic wet oxidation reactor to react and obtain treated solution I. The oxidant for the catalytic wet oxidation reaction is air or oxygen, with a flow rate of 40L / h; the temperature of the catalytic wet oxidation reaction is 260℃; the reaction pressure is 6MPa; and the reaction time is 2.5h.
[0078] Step S2: Add 2g of modified catalyst to 1L of treatment solution I and perform photocatalysis for 1h at a wavelength of 400nm to obtain treatment solution II;
[0079] Step S3: Treatment solution II is distilled through a polytetrafluoroethylene hollow fiber membrane (the membrane has a pore size of 1 μm, a porosity of 70-90%, and a membrane thickness of 0.25 mm) to obtain treatment solution III, thus completing the treatment.
[0080] The preparation steps for the modified catalyst are the same as in Example 5.
[0081] The COD removal rate in this embodiment was measured to be 98.6%, and the ammonia nitrogen removal rate was 92.1%.
[0082] Comparative Example 1
[0083] A method for treating wastewater from the production of methyl thiophanate, which differs from Example 1 in that the modified catalyst in Example 1 is replaced with the product prepared in Preparation Example 6, while the other raw materials, processes and parameters are the same as in Example 1.
[0084] The COD removal rate in this embodiment was measured to be 85.5%, and the ammonia nitrogen removal rate was 81.1%.
[0085] Comparative Example 2
[0086] A method for treating wastewater from the production of methyl thiophanate, which differs from Example 1 in that the modified catalyst in Example 1 is replaced with the product prepared in Preparation Example 7, while the other raw materials, processes and parameters are the same as in Example 1.
[0087] The COD removal rate in this embodiment was measured to be 80.5%, and the ammonia nitrogen removal rate was 79.3%.
[0088] Comparative Example 3
[0089] A method for treating wastewater from the production of methyl thiophanate, which differs from Example 1 in that the modified catalyst in Example 1 is replaced with the product prepared in Preparation Example 8, while the other raw materials, processes and parameters are the same as in Example 1.
[0090] The COD removal rate in this embodiment was measured to be 74.8%, and the ammonia nitrogen removal rate was 72.4%.
[0091] Comparing Examples 1-3 with Comparative Examples 1 and 2, it can be seen that Examples 1-3 are more effective than Comparative Examples 1-3 in treating wastewater. In Comparative Example 1, the surfactant containing thiol groups was replaced with a surfactant without thiol groups, indicating that thiol groups have a strong interaction with silver, thus stabilizing the silver nanoparticles and preventing their aggregation. This helps to form a uniformly dispersed silver nanoparticle-surfactant complex solution, which can improve the removal rates of COD and ammonia nitrogen. The modified catalyst in Comparative Example 2 does not contain silver nanoparticles, indicating that silver nanoparticles are beneficial for improving catalytic efficiency, thereby reducing the COD and ammonia nitrogen concentrations of the wastewater. The modified catalyst in Comparative Example 3 does not contain silver nanoparticle-surfactant, indicating that quaternary ammonium salt groups can efficiently adsorb SCN under electrostatic interaction. - This reduces the organic matter in the wastewater, and lowers the COD value and ammonia nitrogen concentration in the wastewater from the production of thiophanate-methyl.
[0092] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for treating wastewater from the production of thiophanate-methyl, characterized in that, Includes the following steps: Step S1: Add copper sulfate pentahydrate to the methyl thiophanate production wastewater, and then pass it into a catalytic wet oxidation reactor to react and obtain treatment solution I; Step S2: Add the modified catalyst to treatment solution I and perform photocatalysis to obtain treatment solution II; Step S3: Processing solution II is subjected to three-stage membrane distillation to obtain processing solution III, thus completing the processing; In step S2, the preparation steps of the modified catalyst are as follows: Step A1: Add activated carbon to a 1 g / L nano silver-surfactant composite solution, stir at 160-200 r / min for 3-4 h, wash with water, and dry to obtain modified activated carbon; Step A2: Mix anhydrous ethanol, tetrabutyl titanate, and glacial acetic acid to obtain mixture A; add modified activated carbon to mixture A, followed by an 80% (v / v) aqueous ethanol solution to obtain a gel; age the gel for 8 hours, then react it at 120-130℃ for 12 hours, cool it to room temperature, remove it, wash it with water, filter it, dry it, and grind it to obtain the modified catalyst. The preparation method of the nano-silver-surfactant complex solution is as follows: A solution of 0.06 mol / L (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide, 0.01 mol / L silver nitrate, and 0.5 mol / L sodium borohydride was stirred until homogeneous and reacted at room temperature for 8 h to obtain a nano-silver-surfactant composite solution.
2. The method for treating methyl thiophanate production wastewater according to claim 1, characterized in that, Before step S1, add 30wt% sodium hydroxide aqueous solution to the wastewater to adjust the pH of the wastewater to 7-8.
3. The method for treating methyl thiophanate production wastewater according to claim 1, characterized in that, In step S1, the oxidant for the catalytic wet oxidation reaction is air or oxygen, and the flow rate of air or oxygen is 40 L / h; the temperature of the catalytic wet oxidation reaction is 210-260℃; the reaction pressure is 2-6 MPa; and the reaction time is 2-2.5 h.
4. The method for treating methyl thiophanate production wastewater according to claim 1, characterized in that, In step S1, the ratio of methyl thiophanate production wastewater to copper sulfate pentahydrate is 1L:2-5g.
5. The method for treating methyl thiophanate production wastewater according to claim 1, characterized in that, In step S2, the ratio of treatment solution I to modified catalyst is 1L:1-2g; the photocatalysis time is 0.5-1h; and the photocatalysis wavelength is 400nm.
6. The method for treating methyl thiophanate production wastewater according to claim 1, characterized in that, In step A1, the ratio of 1 g / L nano-silver-surfactant composite solution to activated carbon is 100-140 mL: 10 g; in step A2, the volume ratio of anhydrous ethanol, tetrabutyl titanate, and glacial acetic acid in mixture A is 2-2.5: 1-2: 0.15-0.25; the ratio of mixture A, modified activated carbon, and ethanol aqueous solution is 30-35 mL: 2.5-3 g: 13-18 mL.
7. The method for treating methyl thiophanate production wastewater according to claim 1, characterized in that, The volume ratio of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide aqueous solution, silver nitrate aqueous solution, and sodium borohydride aqueous solution is 5:5:
1.
8. The method for treating methyl thiophanate production wastewater according to claim 1, characterized in that, In step S3, the three-stage membrane distillation system uses a polytetrafluoroethylene hollow fiber membrane with a pore size of 0.1-1 μm, a porosity of 70-90%, and a membrane thickness of 0.1-0.25 mm.