Method for electro-catalytic oxidation treatment of triazinone wastewater

Abstract

The present application belongs to the technical field of pesticide industrial wastewater treatment, and particularly relates to a method for treating triazinone wastewater by electro-catalytic oxidation. The treatment process comprises the following steps: (1) adding a composite microbial inoculum to triazinone production wastewater, and carrying out anaerobic culture to obtain degraded triazinone production wastewater; (2) heating the degraded triazinone production wastewater, and evaporating a fraction under stirring to obtain distilled wastewater; (3) using ultraviolet light in combination with electro-catalysis to electro-catalytically oxidize the distilled wastewater to obtain wastewater containing pivalic acid; (4) adding an extraction liquid to the wastewater containing pivalic acid under the condition of 25-30 DEG C to obtain an extraction liquid layer and a water layer; (5) adjusting the pH of the water layer to neutral with liquid alkali, and carrying out reduced-pressure distillation to obtain recovered water; and carrying out reduced-pressure distillation on the extraction liquid layer to recover the extraction liquid by condensation, while obtaining a residue containing pivalic acid. The treatment method can reduce the amount of COD and ammonia nitrogen, and at the same time, improve the pivalic acid recovery rate.

Description

Technical Field

[0001] This invention belongs to the field of pesticide industrial wastewater treatment technology, specifically relating to a method for electrocatalytic oxidation treatment of triazine ketone wastewater. Background Technology

[0002] Triazinone is an organic compound and an important intermediate in the synthesis of the herbicide metribuzin. The wastewater generated during the production of triazinone has many special characteristics, which make it difficult to treat. If it is discharged directly without proper treatment, it will have a significant negative impact on the environment: (1) Large discharge volume: Triazinone is a widely used chemical intermediate, and its production scale is usually large, so the amount of wastewater generated is also relatively large. The discharge of a large amount of wastewater will increase the load on sewage treatment facilities, which may exceed the treatment capacity of local sewage treatment plants, resulting in some untreated or incompletely treated wastewater entering natural water bodies. (2) High chemical oxygen demand (COD) concentration: A high COD value indicates that the wastewater contains a large amount of organic matter, which requires more oxygen to decompose, increasing the difficulty and cost of biological treatment. When such high COD wastewater is discharged into rivers, lakes and other water bodies, it will consume dissolved oxygen in the water, which may lead to the death of aquatic organisms due to lack of oxygen and disrupt the ecological balance. (3) High salt content: The reaction and separation steps in the production process of triazinone may introduce a certain amount of inorganic salts, such as sodium chloride and sodium sulfate. High salt content in wastewater can affect the activity of microorganisms, reduce the efficiency of biological treatment, and even inhibit the growth of some microorganisms, making biological treatment methods infeasible. Salt can also affect soil structure, leading to soil salinization and affecting crop growth. (3) High content of recalcitrant compounds: Triazine ketones and their derivatives may be complex and stable organic compounds that are not easily decomposed by conventional microbial communities. These recalcitrant substances accumulate in the environment and may be passed through the food chain, ultimately posing a threat to human health. (4) Strong odor: Wastewater may contain volatile organic compounds (VOCs), which not only have a strong odor but may also be harmful to human health.

[0003] The industrial production of triazinone generates wastewater containing various organic compounds, including pivalic acid. Pivalic acid is a valuable chemical substance with important applications in several industries, such as as a raw material for solvents, coatings, plastics, and pharmaceuticals. Therefore, from both environmental and economic perspectives, the separate separation and recovery of pivalic acid is highly significant. Current technologies typically involve extraction with organic solvents to remove total organic matter from the triazinone industrial wastewater. However, this method removes pivalic acid along with other organic pollutants, making pivalic acid recovery impossible and failing to address the issue of separate separation and recycling of pivalic acid from triazinone production wastewater. Summary of the Invention

[0004] The purpose of this invention is to provide a method for electrocatalytic oxidation treatment of triazine ketone wastewater. This method can treat the COD in triazine ketone production wastewater and effectively reduce the total organic matter concentration in the wastewater.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for electrocatalytic oxidation treatment of triazine ketone wastewater includes the following steps:

[0007] (1) Add compound bacterial agent to triazine ketone production wastewater and anaerobic culture to obtain degraded triazine ketone production wastewater;

[0008] (2) The degraded triazine ketone production wastewater is heated and distilled off under stirring conditions to obtain distilled wastewater;

[0009] (3) The distilled wastewater was electrocatalytically oxidized using ultraviolet light combined with electrocatalysis to obtain wastewater containing pentyl acid;

[0010] (4) At 25-30℃, add the extract to the wastewater containing pentylene acid, stir for 20-40 min, let stand for 30-40 min, separate the liquid and separate the extract layer; then repeat the extraction once with the same method for the water layer; combine the extract layers from the two extractions.

[0011] (5) The pH of the aqueous layer is adjusted to neutral with liquid alkali and distilled under reduced pressure to obtain the recovered water; the extract layer is distilled under reduced pressure, and the extract is condensed and recovered, while the residue containing pentanoic acid is obtained.

[0012] Furthermore, the conditions for electrocatalytic oxidation in step (3) are: constant current: 6A, anode: ruthenium-iridium electrode, cathode: titanium electrode, electrolysis time: 1-3h.

[0013] Furthermore, in step (3), a 300-350W xenon lamp is used to provide ultraviolet light irradiation.

[0014] This invention first heats the wastewater and evaporates approximately 20% of low-boiling-point organic matter and water under stirring conditions. This process removes some volatile organic compounds, such as solvents or other low-molecular-weight organics, thereby initially reducing the COD in the wastewater. The invention then utilizes strong oxidizing free radicals generated by an electrochemical reaction to decompose organic pollutants in the wastewater. In this process, ruthenium-iridium electrodes are selected as the anode and titanium electrodes as the cathode, enabling highly efficient oxidation at relatively low voltages.

[0015] Furthermore, the anaerobic culture conditions in step (1) are: anaerobic culture at 30-35℃ for 6-8 days.

[0016] Furthermore, the compound microbial agent in step (1) includes Bacillus subtilis, Bacillus cereus, and Bacillus amyloliquefaciens.

[0017] Furthermore, the amount of Bacillus subtilis used in step (1) is 10. 6 ~10 7 CFU / mL; the dosage of Bacillus cereus was 10. 7 ~10 8 CFU / mL; the dosage of Bacillus amyloliquefaciens was 10. 8 ~10 9 CFU / mL.

[0018] During the experiment, it was found that although ultraviolet light combined with electrocatalysis could reduce COD, the recovery rate of pentavolic acid was not ideal. This invention pretreats the triazine ketone production wastewater with a compound microbial culture, which can improve the pentavolic acid recovery rate. Analysis shows that the compound microbial culture, through biodegradation and metabolic activities during the pretreatment stage, removes or transforms complex organic matter and other interfering substances in the wastewater, thus creating more favorable conditions for subsequent ultraviolet light combined with electrocatalytic treatment. The wastewater may also contain unreacted raw materials, byproducts, solvents, and other organic matter. These substances may compete with pentavolic acid for adsorption sites, forming co-precipitates or co-crystallizations, affecting the separation and recovery of pentavolic acid. The compound microbial culture can reduce their interference with pentavolic acid by biodegrading these organic pollutants.

[0019] Furthermore, in step (2), 18-22% (v / v) fraction is distilled off under stirring conditions.

[0020] Further, in step (4), 50g of extract is added to 1000g of wastewater containing pentavalerate.

[0021] Furthermore, in step (5), the extract layer is distilled under reduced pressure at 55-57°C.

[0022] Furthermore, the extract is toluene and cyclohexane in a volume ratio of (1.3-1.5):1.

[0023] After sequential fermentation and ultraviolet light combined with electrocatalytic treatment, this invention uses toluene and cyclohexane as extraction solvents for layered extraction, which can further improve the recovery rate of pentavonic acid. The ratio of toluene to cyclohexane affects the selectivity of the system for other impurities. By optimizing the ratio, pentavonic acid can be selectively extracted, reducing interference from other impurities and improving the purity and recovery rate of pentavonic acid.

[0024] Bacillus subtilis, purchased from Shanghai Microbiology Preservation Center, product number: SMHCC D10486.

[0025] Bacillus cereus, purchased from Beijing Zhongke Quality Inspection Biotechnology Co., Ltd., product number: ZKCC25597.

[0026] Bacillus amyloliquefaciens, purchased from Shanghai Microbiology Preservation Center, product number: SMHCC D10875.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0028] (1) This invention combines electrocatalytic oxidation with ultraviolet irradiation to reduce toxicity and the generation of organochlorine compounds. Furthermore, active chlorine can undergo photolysis mediated by ultraviolet radiation, producing highly reactive oxidizing substances such as ·H₂O and ·Cl. Therefore, introducing ultraviolet irradiation into the electrocatalytic oxidation process for high-sodium chloride concentration wastewater is a way to solve the problem of achieving complete mineralization of pollutants in high-sodium chloride concentration wastewater through electrocatalytic oxidation.

[0029] (2) The present invention pre-treats the wastewater from the production of triazine ketone with compound bacteria, which can improve the recovery rate of tervastatin.

[0030] (3) After sequential fermentation and ultraviolet light combined with electrocatalytic treatment, the present invention uses toluene and cyclohexane as extraction liquids for layered extraction, which can further improve the recovery rate of terpentine. Detailed Implementation

[0031] The bacteria used in this invention are commercially available products:

[0032] Bacillus subtilis, purchased from Shanghai Microbiology Preservation Center, product number: SMHCC D10486.

[0033] Bacillus cereus, purchased from Beijing Zhongke Quality Inspection Biotechnology Co., Ltd., product number: ZKCC25597.

[0034] Bacillus amyloliquefaciens, purchased from Shanghai Microbiology Preservation Center, product number: SMHCC D10875.

[0035] Sulfate-reducing bacteria, purchased from Shanghai Microbiology Preservation Center, product number: SHBCC D24615.

[0036] Example 1

[0037] This embodiment provides a method for electrocatalytic oxidation treatment of triazine ketone wastewater, including the following steps:

[0038] (1) A compound microbial agent is added to the triazine ketone production wastewater. The compound microbial agent includes Bacillus subtilis, Bacillus cereus, and Bacillus amyloliquefaciens. The dosage of Bacillus subtilis is 10... 6 CFU / mL; the dosage of Bacillus cereus was 10.8 CFU / mL; the dosage of Bacillus amyloliquefaciens was 10. 9 CFU / mL. After anaerobic culture at 32℃ for 8 days, the degraded triazine ketone production wastewater was obtained.

[0039] (2) The degraded triazine ketone production wastewater was heated to 106℃ and distilled off a 20 (v / v)% fraction under stirring conditions to obtain distilled wastewater;

[0040] (3) The distilled wastewater was electrocatalytically oxidized using ultraviolet light combined with electrocatalysis; a 320W xenon lamp was used to provide ultraviolet light irradiation; the electrocatalytic oxidation conditions were: constant current: 6A, anode: ruthenium-iridium electrode, cathode: titanium electrode, electrolysis time: 2h. Wastewater containing pentavalerate was obtained;

[0041] (4) Add 50g of extract to 1000g of wastewater containing pentylene acid at 25℃. The extract is a mixture of toluene and cyclohexane with a volume ratio of 1.4:1. Stir for half an hour, let stand for half an hour, separate the liquids, and separate the extract layer. Repeat the extraction process once with the aqueous layer. Combine the extract layers from the two extractions.

[0042] (5) The pH of the aqueous layer was adjusted to neutral with liquid alkali and then distilled under reduced pressure to obtain the recovered water; the extract layer was distilled under reduced pressure at 55°C and the extract was condensed and recovered, while the residue containing pentanoic acid was obtained.

[0043] Example 2

[0044] This embodiment provides a method for electrocatalytic oxidation treatment of triazine ketone wastewater, including the following steps:

[0045] (1) A compound microbial agent is added to the triazine ketone production wastewater. The compound microbial agent includes Bacillus subtilis, Bacillus cereus, and Bacillus amyloliquefaciens. The dosage of Bacillus subtilis is 10... 6 CFU / mL; the dosage of Bacillus cereus was 10. 7 CFU / mL; the dosage of Bacillus amyloliquefaciens was 10. 8 CFU / mL. After anaerobic culture at 35℃ for 8 days, the degraded triazine ketone production wastewater was obtained.

[0046] (2) When the degraded triazine ketone production wastewater is heated to 105℃, a 22 (v / v)% fraction is distilled off under stirring conditions to obtain distilled wastewater;

[0047] (3) The distilled wastewater was electrocatalytically oxidized using ultraviolet light combined with electrocatalysis; a 300W xenon lamp was used to provide ultraviolet light irradiation; the conditions for electrocatalytic oxidation were: constant current: 6A, anode: ruthenium-iridium electrode, cathode: titanium electrode, electrolysis time: 1h. Wastewater containing pentylene acid was obtained.

[0048] (4) Add 50g of extract to 1000g of wastewater containing pentylene acid at 25℃. The extract is a mixture of toluene and cyclohexane with a volume ratio of 1.3:1. Stir for half an hour, let stand for half an hour, separate the liquids, and separate the extract layer. Repeat the extraction process once with the aqueous layer. Combine the extract layers from the two extractions.

[0049] (5) The pH of the aqueous layer was adjusted to neutral with liquid alkali and then distilled under reduced pressure to obtain the recovered water; the extract layer was distilled under reduced pressure at 55°C and the extract was condensed and recovered, while the residue containing pentanoic acid was obtained.

[0050] Comparative Example 1

[0051] The difference between this comparative example and Example 1 is that no degradation is performed.

[0052] A method for electrocatalytic oxidation treatment of triazine ketone wastewater includes the following steps:

[0053] (1) When the wastewater from the production of triazine was heated to 106°C, 20% (v / v) fraction was distilled off under stirring conditions to obtain the distilled wastewater;

[0054] (2) The distilled wastewater was electrocatalytically oxidized using a combination of ultraviolet light and electrocatalysis; a 320W xenon lamp was used to provide ultraviolet light irradiation; the electrocatalytic oxidation conditions were: constant current: 6A, anode: ruthenium-iridium electrode, cathode: titanium electrode, electrolysis time: 2h. Wastewater containing pentavalerate was obtained.

[0055] (3) Add 50g of extract to 1000g of wastewater containing pentylene acid at 25℃. The extract is a mixture of toluene and cyclohexane with a volume ratio of 1.4:1. Stir for half an hour, let stand for half an hour, separate the liquids, and separate the extract layer. Repeat the extraction process once with the aqueous layer. Combine the extract layers from the two extractions.

[0056] (4) The pH of the aqueous layer was adjusted to neutral with liquid alkali and then distilled under reduced pressure to obtain the recovered water; the extract layer was distilled under reduced pressure at 55°C and the extract was condensed and recovered, while the residue containing pentanoic acid was obtained.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 1 is that the amount of Bacillus subtilis used is 10. 8 CFU / mL; the dosage of Bacillus cereus was 10. 6 CFU / mL; the dosage of Bacillus amyloliquefaciens was 10. 7 CFU / mL.

[0059] Comparative Example 3

[0060] The difference between this comparative example and Example 1 is that the compound microbial agent includes Bacillus subtilis, sulfate-reducing bacteria, and Bacillus amyloliquefaciens. The dosage of Bacillus subtilis is 10... 6 CFU / mL; the dosage of sulfate-reducing bacteria was 10. 8 CFU / mL; the dosage of Bacillus amyloliquefaciens was 10. 9 CFU / mL.

[0061] Comparative Example 4

[0062] The difference between this comparative example and Example 1 is that the extract is a mixture of toluene and cyclohexane in a volume ratio of 1:1.

[0063] Comparative Example 5

[0064] The difference between this comparative example and Example 1 is that the extract is toluene.

[0065] Performance testing

[0066] The wastewater from the production of triazine is as follows: COD is 15280 mg / L, ammonia nitrogen is 820 mg / L, and tertivalic acid content is 1 wt%.

[0067] The above-mentioned triazine ketone production wastewater was treated using the processes of Examples 1-2 and Comparative Examples 1-5.

[0068] The COD, ammonia nitrogen, and TOC in the recovered water were determined. The COD detection method was carried out in accordance with HG 828-2017; the ammonia nitrogen detection method was carried out in accordance with HG 535-2009.

[0069] Determination of pentovalin recovery: Pterovalin was determined by HPLC external standard method under the following conditions: mobile phase: acetonitrile:water = 8:2 (pH adjusted to 4.0 with formic acid); chromatographic column: C18 silica gel column; wavelength: 214nm; flow rate: 1ml / min; column temperature: 30℃.

[0070] Pteropenic acid recovery rate = mass of teropenic acid remaining in the reactor residue / mass of teropenic acid in the wastewater before treatment * 100%.

[0071] The results after processing are shown in Table 1.

[0072] Table 1. Wastewater parameters after treatment

[0073]

[0074] The results show that the treatment processes in Examples 1-2 recover low amounts of COD, ammonia nitrogen, and TOC from the water, while the recovery rate of tervastatin is higher than 95%.

[0075] In Comparative Example 1, no pre-degradation treatment was performed, resulting in increased levels of COD, ammonia nitrogen, and TOC in the recovered water, and a decreased recovery rate of tervastatin.

[0076] The different types and amounts of bacteria used in Comparative Examples 2 and 3 resulted in varying degrees of reduction in the recovery rate of pentylene acid.

[0077] The compositions of the extracts in Comparative Examples 4 and 5 were different, resulting in a decrease in the recovery rate of tervastatin.

[0078] The above experimental results further demonstrate the importance of the technical solution defined in this invention to its technical effect.

[0079] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for electrocatalytic oxidation treatment of triazine ketone wastewater, characterized in that, Includes the following steps: (1) Add compound bacterial agent to triazine ketone production wastewater and anaerobic culture to obtain degraded triazine ketone production wastewater; (2) The degraded triazine ketone production wastewater is heated and distilled off under stirring conditions to obtain distilled wastewater; (3) The distilled wastewater was electrocatalytically oxidized using ultraviolet light combined with electrocatalysis to obtain wastewater containing pentyl acid; (4) At 25-30℃, add the extract to the wastewater containing pentylene acid, stir for 20-40 min, let stand for 30-40 min, separate the liquid and separate the extract layer; then repeat the extraction once with the same method for the water layer; combine the extract layers from the two extractions. (5) The pH of the aqueous layer is adjusted to neutral with liquid alkali and distilled under reduced pressure to obtain the recovered water; the extract layer is distilled under reduced pressure, and the extract is condensed and recovered, while the residue containing pentanoic acid is obtained.

2. The method according to claim 1, characterized in that, The conditions for electrocatalytic oxidation in step (3) are: constant current: 6A, anode: ruthenium-iridium electrode, cathode: titanium electrode, electrolysis time: 1-3h.

3. The method according to claim 1, characterized in that, In step (3), a 300-350W xenon lamp is used to provide ultraviolet light irradiation.

4. The method according to claim 1, characterized in that, The anaerobic culture conditions in step (1) are: anaerobic culture at 30-35℃ for 6-8 days.

5. The method according to claim 1, characterized in that, The compound microbial agent in step (1) includes Bacillus subtilis, Bacillus cereus, and Bacillus amyloliquefaciens.

6. The method according to claim 5, characterized in that, The dosage of Bacillus subtilis in step (1) is 10 6 ~10 7 CFU / mL; the dosage of Bacillus cereus was 10. 7 ~10 8 CFU / mL; the dosage of Bacillus amyloliquefaciens was 10. 8 ~10 9 CFU / mL.

7. The method according to claim 1, characterized in that, In step (2), 18-22% (v / v) fraction is distilled off under stirring conditions.

8. The method according to claim 1, characterized in that, In step (4), 50g of extract is added to 1000g of wastewater containing pentavalerate.

9. The method according to claim 1, characterized in that, In step (5), the extract layer is distilled under reduced pressure at 55-57°C.

10. The method according to claim 1, characterized in that, The extract in step (4) is toluene and cyclohexane in a volume ratio of (1.3-1.5):1.

Images