A method for treating high-concentration organic sulfur-containing pharmaceutical intermediate wastewater

Abstract

A kind of high concentration organic sulfur-containing pharmaceutical intermediate waste water treatment method, first carries out rough electrolysis, electric oxidation adds high-frequency vibration equipment, utilize the high strong oxidizability of hydroxyl radical, make the organic matter or group of benzene ring, sulfonic acid group, C-S, S-H, S-N, S-O, C-N in waste water with toxicity, carry out chain breaking, bond breaking, in this process, due to sulfur-containing group is oxidized into sulfate and hydrogen ion, make waste water become acidic, add sodium hydroxide, obtain higher purity sodium sulfate product;Again carry out fine electrolysis, and the COD value of waste water is reduced to below 200mg / L, continue to freeze crystallization sodium sulfate, and the remaining waste water continues to return and carry out fine electrolysis.The present application efficiently oxidizes the pollutants such as sulfur-containing organic matter, heterocyclic compound, organic solvent in waste water, quickly removes the toxicity in waste water;The sulfur element in waste water is recycled as a resource;The purity of sodium sulfate product prepared in steps is high, and the purity of sodium sulfate is greater than or equal to 98%.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical wastewater treatment, and in particular to a method for treating wastewater containing high concentrations of organic sulfur-containing pharmaceutical intermediates. Background Technology

[0002] Pharmaceutical wastewater mainly originates from the production processes of organic and inorganic pharmaceuticals and pharmaceutical intermediates. Pharmaceutical wastewater is characterized by high organic content, high toxicity, complex structure, high salt content, poor biodegradability, and intermittent discharge. Pollutants in pharmaceutical production wastewater are generally difficult to degrade. If the treatment is not up to standard, it will affect the soil, water quality, vegetation, and the health of surrounding residents. The soil has limited filtration capacity for wastewater. If toxic substances, heavy metals, acids, alkalis, etc. enter the soil, the harm to the soil will be particularly obvious. Wastewater generated from high-concentration organic sulfur-containing pharmaceutical intermediates is characterized by high pollution, complex composition, poor biodegradability, and high potential biological toxicity. It is a typical high-concentration organic chemical wastewater that is difficult to treat. Its specific characteristics mainly depend on the synthetic route and specific process steps used, but it usually has the following common characteristics: (1) Extremely high COD (chemical oxygen demand): usually reaching tens of thousands of mg / L or even higher. It mainly comes from unreacted raw materials, intermediate products, by-products, solvent residues, etc. (2) Relatively low BOD (biochemical oxygen demand): The BOD / COD ratio is usually low (often below 0.3), indicating that the wastewater contains a large amount of recalcitrant organic matter and has poor biodegradability. (3) Aromatic / heterocyclic compounds: The core structure includes benzene rings, thiophene rings, glucosides, etc. The wastewater may contain various substituted benzene, thiophene, furan derivatives and their ring-opening or cracking products. The thiophene ring is the key structural unit of canagliflozin, and its synthesis or degradation may produce sulfur-containing organic matter. (4) The sulfur-containing organic matter, certain heterocyclic compounds, residual organic solvents, and high salt content itself may all have inhibitory or toxic effects on microorganisms. (5) Frequent use of acids and bases (such as sodium hydroxide, sodium carbonate, hydrochloric acid, sulfuric acid) for pH adjustment, neutralization, salt formation, hydrolysis, etc. during the synthesis process results in very high total dissolved solids (TDS) and conductivity of the wastewater, which may reach tens of thousands or even hundreds of thousands of mg / L. High salt content can inhibit microbial activity, increase the difficulty of subsequent biochemical treatment, and may cause equipment corrosion and scaling.

[0003] CN116002912A discloses a process for treating pharmaceutical intermediate wastewater, including homogenization for 22-26 hours; after homogenization, the wastewater directly enters an ozone catalytic oxidation system for COD degradation; the ozone catalytic oxidation system uses ozone, under the action of a solid catalyst, to generate highly oxidizing hydroxyl radicals, which decompose organic matter into minerals, carbon dioxide, and water; pH adjustment to 3-4; secondary COD degradation; impurity removal; activated carbon adsorption; MVR evaporation treatment: the wastewater enters the MVR system for evaporation treatment to obtain condensate and mixed salts; tertiary COD degradation; organic matter degradation; filtration; ultimately, the turbidity of the wastewater is less than or equal to 1 NTU, and the final wastewater quality meets the requirements for industrial circulating water makeup water. However, it does not treat the mixed salts obtained from MVR evaporation, and the waste salts obtained from the evaporation of pharmaceutical intermediate wastewater are also hazardous waste.

[0004] CN114262121A discloses a wastewater treatment process for pharmaceutical intermediates in fine chemicals, including a pretreatment section consisting of an "Fe / C micro-electrolysis unit + multi-effect evaporation unit + advanced oxidation unit", a biochemical section consisting of an "enhanced AO biological contact oxidation unit + MBR unit", a deep treatment section consisting of a "DTRO membrane reuse" section, a pyrolysis section consisting of a "concentrated brine pyrolysis and gasification unit + flue gas treatment unit", and a sludge treatment section. However, it has too many sections and requires a large investment.

[0005] CN117023897A discloses a pharmaceutical wastewater treatment process, which first involves pretreatment: degrading high-molecular-weight organic matter in the pharmaceutical wastewater to improve its biodegradability; after fully removing organic matter from the wastewater through biological treatment technology, the water is discharged into a clear water tank, where a screen intercepts and removes larger suspended solids, floating matter, and impurities; sludge is removed from a secondary sedimentation tank, and flocculants are removed from a coagulation sedimentation tank; the removed solids are dried, and then the dried material is placed in a compressor for compression into blocks. However, this process uses biological pretreatment, limiting its applicability.

[0006] CN111268825A discloses a COD treatment process for pharmaceutical intermediate wastewater. The process involves discharging the wastewater into an equalization tank, adding dilute sulfuric acid to adjust the pH to 2.5-3.0, then discharging the adjusted wastewater into an advanced oxidation reaction tank where an oxidant and a catalyst are simultaneously added and the reaction is carried out with continuous stirring. The reaction water is then discharged into an alkali precipitation tank, where sodium hydroxide solution is added to adjust the pH to 9-11, and an alkali precipitation reaction is performed to co-precipitate impurities in the wastewater. The treated water is then discharged into a PERFECT membrane system, where the pH is adjusted after reaching the required standard before discharge. The sludge trapped by the PERFECT membrane is introduced into a filter press for dewatering, and the press water is returned to the upstream treatment stage. The sludge cake is then transported out. However, this process generates a significant amount of solid waste, requiring a large treatment volume.

[0007] CN118812063A discloses a pretreatment process for pharmaceutical intermediate wastewater before biochemical treatment, relating to the technical field of pretreatment of pharmaceutical intermediate wastewater before biochemical treatment. The treatment steps include: determining the required iron and carbon mass water level for the wastewater's COD value; adjusting the wastewater's pH value; transporting the wastewater for micro-electrolysis and Fenton reaction; dynamically controlling the wastewater's pH value within a certain range during the reaction; adjusting the pH value of the effluent after the Fenton oxidation reaction; adding coagulants and flocculants for flocculation and sedimentation; and obtaining the effluent after filtration. However, this pretreatment of pharmaceutical intermediate wastewater still requires a biochemical reaction. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for treating high-concentration organic sulfur-containing pharmaceutical intermediate wastewater, which has a better treatment effect and allows for the resource recovery and reuse of sulfur elements in the wastewater.

[0009] The technical solution adopted by this invention to solve its technical problem is a method for treating high-concentration organic sulfur-containing pharmaceutical intermediate wastewater, which is achieved through the following technical solution: First, crude electrolysis is performed, followed by electro-oxidation and high-frequency vibration equipment. Utilizing the strong oxidizing power of hydroxyl radicals, toxic organic compounds or groups such as benzene rings, sulfonic acid groups, CS, SH, SN, SO, and CN in the wastewater undergo chain and bond breaking. During this process, the sulfur-containing groups are oxidized to sulfate and hydrogen ions, making the wastewater acidic. Sodium hydroxide is then added to obtain a high-purity sodium sulfate product. Next, fine electrolysis is performed, which can reduce the COD value of the wastewater to below 200 mg / L. Sodium sulfate is then further frozen and crystallized, and the remaining wastewater is returned for further fine electrolysis.

[0010] Furthermore, the high-concentration organic sulfur-containing pharmaceutical intermediate wastewater is wastewater with COD > 50000 mg / L and S content > 3000 mg / L. It is further classified as production wastewater from pharmaceutical intermediates used in hypoglycemic drugs such as dapagliflozin and canagliflozin.

[0011] Specifically, the following steps are included:

[0012] S1, Crude Electrolysis: High-concentration organic sulfur-containing pharmaceutical intermediate wastewater is fed into an electrocatalytic oxidation device for electrolysis; the resulting electro-oxidation product water is fed into a storage tank, in which two high-frequency vibrating rods are placed;

[0013] S2, when the high-concentration organic sulfur-containing pharmaceutical intermediate wastewater is electrolyzed to 0.5≤pH≤1, add sodium hydroxide solution to the wastewater to adjust the pH to neutral. At this time, the sulfate concentration in the wastewater is too high, and a large amount of sodium sulfate crystals will precipitate; stir and age for 1-4 hours.

[0014] Studies have shown that when pharmaceutical intermediate wastewater is electrolyzed to a pH of 0.5 ≤ pH ≤ 1, benzene rings, CS, SH, SN, SO, CN, etc. are oxidized and broken under the action of strong oxidizing groups such as hydroxyl radicals, generating a large number of sulfate ions and hydrogen ions, which leads to a decrease in the pH value of the solution. However, if the pH is too low, it will affect the efficiency of electro-oxidation of organic matter and damage the equipment. When the pH value of the wastewater is < 0.5, electro-oxidation must be stopped.

[0015] S3, filtration, yields sodium sulfate and crude electrolytic pharmaceutical intermediate wastewater;

[0016] Because a large amount of water forms a solid in the form of water of crystallization during the precipitation of sodium sulfate, the amount of wastewater is greatly reduced and organic pollutants are concentrated.

[0017] S4, Precision Electrolysis: The crude electrolytic pharmaceutical intermediate wastewater obtained from step S3 is connected to an electrocatalytic oxidation device for precision electrolysis, and the pH of the wastewater is adjusted to neutral with sodium hydroxide solution; electrolysis is stopped when the COD in the wastewater drops below 200 mg / L.

[0018] S5, freezing nitrate: filter the mixture after electrolysis in step S4 to obtain sodium sulfate crystals and sodium precipitation tail liquid;

[0019] S6. The sodium tail liquid obtained in step S5 is concentrated through a reverse osmosis membrane to obtain concentrated water and fresh water. The concentrated water is returned to step S4, and the fresh water can be directly reused or discharged in compliance with standards.

[0020] Furthermore, in step S1, the electrode current density during electrolysis is 30-70 mA / cm². 2 The voltage is adjusted between 1-10V. The wastewater flow rate is 2-6m / s. 3 / h.

[0021] Furthermore, in step S1, the high-frequency vibrating rod vibrates at a frequency of 10-500 Hz. High-frequency vibration can rapidly cause dissolved carbon dioxide, air, and other substances in the water to escape quickly, significantly reducing the resistance of the wastewater and improving the electro-oxidation efficiency.

[0022] Furthermore, in step S2, the mass concentration of the sodium hydroxide solution is 10% to 30%.

[0023] Furthermore, in step S2, the stirring speed during aging is 50-100 rad / min. Aging is carried out at room temperature. Sodium sulfate crystals will still precipitate during the aging process. Controlling the aging conditions can ensure that the resulting sodium sulfate particles are uniform in size and have high purity.

[0024] Furthermore, in step S4, the specific parameters for precision electrolysis are: current density of 50-70 mA / cm². 2 The voltage is between 3.5-8.5V, and the flow rate is 5-15m.3 / h, connects to high-frequency vibration equipment, vibration frequency 10-500HZ.

[0025] Furthermore, in step S4, the mass concentration of the sodium hydroxide solution is 10% to 30%.

[0026] Furthermore, in step S5, the nitrate is frozen at -10 to 25°C for 2-6 hours.

[0027] Furthermore, in step S6, reverse osmosis concentration is carried out under a pressure range of 0.1 MPa to 0.5 MPa.

[0028] In summary, the present invention has the following main beneficial effects:

[0029] (1) It efficiently oxidizes sulfur-containing organic matter, heterocyclic compounds, organic solvents and other pollutants in wastewater, and quickly removes toxicity from wastewater;

[0030] (2) Resource recovery and reuse of sulfur in wastewater;

[0031] (3) The sodium sulfate product obtained by stepwise preparation has high purity, with a purity of greater than or equal to 98%;

[0032] (4) The sodium sulfate product obtained in steps has a high sulfur content in the wastewater, reaching over 96%;

[0033] (5) The water resources in the wastewater are efficiently purified, achieving "zero discharge" of high-concentration organic sulfur-containing pharmaceutical intermediate wastewater. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments.

[0035] Example 1

[0036] Wastewater from a pharmaceutical intermediate in Hunan Province was used as raw material for treatment.

[0037] Table 1. Water quality composition of pharmaceutical intermediate wastewater from a pharmaceutical factory in Hunan Province

[0038] Example 1 COD, mg / L pH TDS S, mg / L Wastewater before treatment 140980 6.5 56246 6350 Treated freshwater 18 7.0 ＜200 ≈0

[0039] S1, Crude Electrolysis: High-concentration organic sulfur-containing pharmaceutical intermediate wastewater is fed into an electrocatalytic oxidation device for electrolysis; the resulting electro-oxidation product water is fed into a storage tank, in which two high-frequency vibrating rods are placed;

[0040] Electro-oxidation conditions; Electrolysis electrode current density 50 mA / cm² 2 Voltage 2.34V, connected to high-frequency vibration equipment, vibration frequency 50Hz; wastewater flow velocity 3m / s. 3 / h.

[0041] S2, when the pharmaceutical intermediate wastewater was electrolyzed to pH=1, the COD value decreased to 178mg / L. Electro-oxidation was stopped, and a 10% sodium hydroxide solution was added to adjust the pH to 7. The mixture was then stirred at 75rad / min at room temperature and aged for 2 hours.

[0042] S3, filtration, yielding sodium sulfate crystals and crude electrolytic pharmaceutical intermediate wastewater. The sodium sulfate purity was 98.3 wt%, and the COD value of the crude electrolytic pharmaceutical intermediate wastewater was 5780 mg / L.

[0043] S4, Precision Electrolysis: The filtered crude electrolytic pharmaceutical intermediate wastewater is subjected to precision electrolysis, connected to an electrocatalytic oxidation device, with a current density of 70 mA / cm². 2 Voltage 6.06V, wastewater flow rate 7m / s 3 / h, connect to high-frequency vibration equipment, vibration frequency 40HZ, and at the same time adjust the pH of wastewater to neutral with 10wt% sodium hydroxide solution. Stop electrolysis when COD drops to 200mg / L;

[0044] S5 was frozen at 0℃ for 2 hours to obtain Glauber's salt, with a sodium sulfate purity of 99.1%.

[0045] In step S6, the sodium-precipitated tail liquid is concentrated by reverse osmosis at a pressure of 0.3 MPa to obtain concentrated water and desalinated water. The concentrated water is returned to step S4 for further electro-oxidation to remove organic matter. The desalinated water has a COD value of 18 mg / L, a pH value of 7.0, a TDS value of <200 mg / L, and a sulfur content of ≈0, which meets the national standard GB 21904-2008 Discharge Standard for Water Pollutants from Chemical Synthesis Pharmaceutical Industry.

[0046] The recovery rate of sulfur in the wastewater during the entire process was 96.3%.

[0047] Example 2

[0048] Wastewater from a pharmaceutical intermediate in Hunan Province was used as raw material for treatment.

[0049] Table 2. Water quality composition of pharmaceutical intermediate wastewater from a pharmaceutical factory in Hunan Province

[0050] Example 2 COD, mg / L pH TDS S, mg / L Wastewater before treatment 140980 6.5 56246 6350 Treated freshwater 21 7.2 ＜200 ≈0

[0051] S1, Crude Electrolysis: High-concentration organic sulfur-containing pharmaceutical intermediate wastewater is fed into an electrocatalytic oxidation device for electrolysis; the resulting electro-oxidation product water is fed into a storage tank, in which two high-frequency vibrating rods are placed;

[0052] Electro-oxidation conditions; Electrolysis electrode current density 70 mA / cm² 2 Voltage 2.17V, connected to high-frequency vibration equipment, vibration frequency 100HZ; wastewater flow velocity 6m / s. 3 / h.

[0053] S2, when the pharmaceutical intermediate wastewater was electrolyzed to pH=0.8, the COD value decreased to 156mg / L. Electro-oxidation was stopped, and 10wt% sodium hydroxide solution was added to adjust the pH to 7. The mixture was then aged for 4 hours at room temperature with stirring at 75rad / min.

[0054] S3, filtration, yielding sodium sulfate crystals and crude electrolytic pharmaceutical intermediate wastewater. The sodium sulfate purity was 98.7%, and the COD value of the crude electrolytic pharmaceutical intermediate wastewater was 5100 mg / L.

[0055] S4, Precision Electrolysis: The filtered crude electrolytic pharmaceutical intermediate wastewater is subjected to precision electrolysis, connected to an electrocatalytic oxidation device, with a current density of 70 mA / cm². 2 Voltage 6.00V, wastewater flow rate 15m / s 3 / h, connect to high-frequency vibration equipment, vibration frequency 100HZ, and at the same time adjust the pH of the wastewater to neutral with 30wt% sodium hydroxide solution. Stop electrolysis when COD drops to 185mg / L.

[0056] S5 was frozen at 0℃ for 2 hours to obtain Glauber's salt, with a sodium sulfate purity of 99.3%.

[0057] In step S6, the sodium-precipitated tail liquid is concentrated by reverse osmosis at a pressure of 0.3 MPa to obtain concentrated water and desalinated water. The concentrated water is returned to step S4 for further electro-oxidation to remove organic matter. The desalinated water has a COD value of 21 mg / L, a pH value of 7.2, a TDS value of <200 mg / L, and a sulfur content of ≈0, which meets the national standard GB 21904-2008 Discharge Standard for Water Pollutants from Chemical Synthesis Pharmaceutical Industry.

[0058] The recovery rate of sulfur in the wastewater during the entire process was 97.9%.

[0059] Example 3

[0060] Wastewater from a pharmaceutical intermediate in Hunan Province was used as raw material for treatment.

[0061] Table 3. Water quality composition of pharmaceutical intermediate wastewater from a pharmaceutical factory in Hunan Province

[0062] Example 3 COD, mg / L pH TDS S, mg / L Wastewater before treatment 140980 6.5 56246 6350 Treated freshwater 20 7.1 ＜200 ≈0

[0063] S1, Crude Electrolysis: High-concentration organic sulfur-containing pharmaceutical intermediate wastewater is fed into an electrocatalytic oxidation device for electrolysis; the resulting electro-oxidation product water is fed into a storage tank, in which two high-frequency vibrating rods are placed;

[0064] Electro-oxidation conditions; Electrolysis electrode current density 70 mA / cm² 2 Voltage 2.17V, connected to high-frequency vibration equipment, vibration frequency 80Hz; wastewater flow velocity 5m / s. 3 / h.

[0065] S2, when the pharmaceutical intermediate wastewater was electrolyzed to pH=0.8, the COD value decreased to 171mg / L. Electro-oxidation was stopped, and 10wt% sodium hydroxide solution was added to adjust the pH to 7. The mixture was then aged for 4 hours at room temperature with stirring at 100rad / min.

[0066] S3, filtration, yielding sodium sulfate crystals and crude electrolytic pharmaceutical intermediate wastewater. The sodium sulfate purity is 98.0%, and the COD value of the crude electrolytic pharmaceutical intermediate wastewater is 5300 mg / L.

[0067] S4, Precision Electrolysis: The filtered crude electrolytic pharmaceutical intermediate wastewater is subjected to precision electrolysis, connected to an electrocatalytic oxidation device, with a current density of 70 mA / cm². 2 Voltage 6.00V, wastewater flow rate 10m 3 / h, connect to high-frequency vibration equipment, vibration frequency 70HZ, and at the same time adjust the pH of the wastewater to neutral with 20wt% sodium hydroxide solution. When the COD drops to 192mg / L, stop electrolysis;

[0068] S5 was frozen at 0℃ for 2 hours to obtain Glauber's salt, with a sodium sulfate purity of 99.1%.

[0069] In step S6, the sodium-precipitated tail liquid is concentrated by reverse osmosis at a pressure of 0.35 MPa to obtain concentrated water and desalinated water. The concentrated water is returned to step S4 for further electro-oxidation to remove organic matter. The desalinated water has a COD value of 20 mg / L, a pH value of 7.1, a TDS value of <200 mg / L, and a sulfur content of ≈0, which meets the national standard GB 21904-2008 Discharge Standard for Water Pollutants from Chemical Synthesis Pharmaceutical Industry.

[0070] The recovery rate of sulfur in the wastewater during the entire process was 96.9%.

[0071] Example 4

[0072] Wastewater from a pharmaceutical intermediate in Hebei Province was used as raw material for treatment.

[0073] Table 4. Water quality composition of pharmaceutical intermediate wastewater from a pharmaceutical factory in Hebei Province

[0074] Example 3 COD, mg / L pH TDS S, mg / L Wastewater before treatment 196820 7.6 120246 9580 Treated freshwater 23 7.0 ＜200 ≈0

[0075] S1, Crude Electrolysis: High-concentration organic sulfur-containing pharmaceutical intermediate wastewater is fed into an electrocatalytic oxidation device for electrolysis; the resulting electro-oxidation product water is fed into a storage tank, in which two high-frequency vibrating rods are placed;

[0076] Electro-oxidation conditions; Electrolysis electrode current density 70 mA / cm² 2 Voltage 1.96V, connected to high-frequency vibration equipment, vibration frequency 100HZ; wastewater flow velocity 2m. 3 / h.

[0077] S2, when the pharmaceutical intermediate wastewater was electrolyzed to pH=0.5, the COD value decreased to 151mg / L. Electro-oxidation was stopped, and 10wt% sodium hydroxide solution was added to adjust the pH to 7. The mixture was then aged for 4 hours at room temperature with stirring at 50rad / min.

[0078] S3, filtration, yielding sodium sulfate crystals and crude electrolytic pharmaceutical intermediate wastewater. The sodium sulfate purity was 98.3%, and the COD value of the crude electrolytic pharmaceutical intermediate wastewater was 5163 mg / L.

[0079] S4, Precision Electrolysis: The filtered crude electrolytic pharmaceutical intermediate wastewater is subjected to precision electrolysis, connected to an electrocatalytic oxidation device, with a current density of 70 mA / cm². 2 Voltage 6.50V, wastewater flow rate 15m / s 3 / h, connect to high-frequency vibration equipment, vibration frequency 100HZ, and at the same time adjust the pH of the wastewater to neutral with 10wt% sodium hydroxide solution. Stop electrolysis when COD drops to 185mg / L.

[0080] S5 was frozen at 0℃ for 2 hours to obtain Glauber's salt, with a sodium sulfate purity of 99.2%.

[0081] In step S6, the sodium-precipitated tail liquid is concentrated by reverse osmosis at a pressure of 0.45 MPa to obtain concentrated water and desalinated water. The concentrated water is returned to step S4 for further electro-oxidation to remove organic matter. The desalinated water has a COD value of 23 mg / L, a pH value of 7.0, a TDS value of <200 mg / L, and a sulfur content of ≈0, which meets the national standard GB 21904-2008 Discharge Standard for Water Pollutants from Chemical Synthesis Pharmaceutical Industry.

[0082] The recovery rate of sulfur in the wastewater during the entire process was 97.3%.

[0083] Example 5

[0084] Wastewater from a pharmaceutical intermediate in Hebei Province was used as raw material for treatment.

[0085] Table 5. Water quality composition of pharmaceutical intermediate wastewater from a pharmaceutical factory in Hebei Province

[0086] Example 3 COD, mg / L pH TDS S, mg / L Wastewater before treatment 196820 7.6 120246 9580 Treated freshwater 19 7.0 ＜200 ≈0

[0087] S1, Crude Electrolysis: High-concentration organic sulfur-containing pharmaceutical intermediate wastewater is fed into an electrocatalytic oxidation device for electrolysis; the resulting electro-oxidation product water is fed into a storage tank, in which two high-frequency vibrating rods are placed;

[0088] Electro-oxidation conditions; Electrolysis electrode current density 70 mA / cm² 2 Voltage 1.96V, connected to high-frequency vibration equipment, vibration frequency 100HZ; wastewater flow velocity 3m / s. 3 / h.

[0089] When the S2 pharmaceutical intermediate wastewater was electrolyzed to pH=1.0, the COD value decreased to 192 mg / L. Electro-oxidation was stopped, and 10 wt% sodium hydroxide solution was added to adjust the pH to 7. The mixture was then aged for 4 hours at room temperature with stirring at 50 rad / min.

[0090] S3, filtration, yielding sodium sulfate crystals and crude electrolytic pharmaceutical intermediate wastewater. The sodium sulfate purity was 98.9%, and the COD value of the crude electrolytic pharmaceutical intermediate wastewater was 4820 mg / L.

[0091] S4, Precision Electrolysis: The filtered crude electrolytic pharmaceutical intermediate wastewater undergoes precision electrolysis, connected to an electrocatalytic oxidation device with a current density of 50 mA / cm². 2 Voltage 4.89V, wastewater flow rate 15m / s 3 / h, connect to high-frequency vibration equipment, vibration frequency 100HZ, and at the same time adjust the pH of the wastewater to neutral with 30wt% sodium hydroxide solution. Stop electrolysis when COD drops to 185mg / L.

[0092] S5 was frozen at 0℃ for 2 hours to obtain Glauber's salt, with a sodium sulfate purity of 99.5%.

[0093] In step S6, the sodium-precipitated tail liquid is concentrated by reverse osmosis at a pressure of 0.40 MPa to obtain concentrated water and desalinated water. The concentrated water is returned to step S4 for further electro-oxidation to remove organic matter. The desalinated water has a COD value of 19 mg / L, a pH value of 7.0, a TDS value of <200 mg / L, and a sulfur content of ≈0, which meets the national standard GB 21904-2008 Discharge Standard for Water Pollutants from Chemical Synthesis Pharmaceutical Industry.

[0094] The recovery rate of sulfur in the wastewater during the entire process was 97.8%.

Claims

1. A method for treating high-strength organic sulfur-containing pharmaceutical intermediate wastewater, characterized in that, First, rough electrolysis, electro-oxidation and high-frequency vibration equipment, using the high oxidation of hydroxyl radicals, the benzene ring, sulfonic acid group, C-S, S-H, S-N, S-O, C-N toxicity of organic matter or group in wastewater, chain breaking, bond breaking, in this process, due to the oxidation of sulfur-containing groups into sulfate and hydrogen ions, the wastewater becomes acidic, adding sodium hydroxide, get higher purity of sodium sulfate product; then the fine electrolysis, the wastewater COD value is reduced to 200mg / L or less, continue to freeze crystallization of sodium sulfate, the remaining wastewater continue to return for fine electrolysis; Specifically comprising the following steps: S1, rough electrolysis: the high concentration of organic sulfur-containing pharmaceutical intermediates wastewater into the electro-catalytic oxidation equipment for electrolysis; the generated electro-oxidation water into the water tank, the tank placed two high-frequency vibration rod; S2, when the high concentration of organic sulfur-containing pharmaceutical intermediates wastewater electrolysis to 0.5≤pH≤1, sodium hydroxide solution is added to the wastewater, the pH value is adjusted to neutral, at this time the wastewater sulfate concentration is too high, a large number of sodium sulfate crystals will be precipitated; stirring and aging 1-4h; S3, filtration, get sodium sulfate and rough electrolysis of pharmaceutical intermediates wastewater; S4, fine electrolysis: the step S3 filtration of the rough electrolysis of pharmaceutical intermediates wastewater into the electro-catalytic oxidation equipment for fine electrolysis, and the pH value of the wastewater is adjusted to neutral with sodium hydroxide solution; when the COD in the wastewater is reduced to 200mg / L or less, stop electrolysis; S5, freeze nitrate: the mixed solution after step S4 electrolysis is filtered to obtain sodium sulfate crystals and sodium precipitation tail liquid; S6, the sodium precipitation tail liquid obtained in step S5 is concentrated by reverse osmosis membrane to obtain concentrated water and dilute water, the concentrated water is returned to step S4, and the dilute water is directly reused or discharged.

2. The treatment method of high concentrated organic sulfur-containing pharmaceutical intermediate wastewater according to claim 1, characterized in that, The high concentration of organic sulfur-containing pharmaceutical intermediates wastewater is wastewater with COD>50000mg / L and S content>3000mg / L.

3. The treatment method of high concentrated organic sulfur-containing pharmaceutical intermediate wastewater according to claim 1 or 2, characterized in that, The high concentration of organic sulfur-containing pharmaceutical intermediates wastewater is daglitin, caglitin hypoglycemic drug intermediates wastewater.

4. The treatment method of high concentrated organic sulfur-containing pharmaceutical intermediate wastewater according to claim 1 or 2, characterized in that, In step S1, the current density of the electrolysis electrode plate is 30-70 mA / cm 2 , and the voltage regulation is between 1-10 V.

5. The treatment method of high concentrated organic sulfur-containing pharmaceutical intermediate wastewater according to claim 1 or 2, characterized in that, In step S2, the mass concentration of sodium hydroxide solution is 10%-30%; and / or, in step S2, the stirring speed of stirring and aging is 50-100rad / min.

6. The treatment method of high concentrated organic sulfur-containing pharmaceutical intermediate wastewater according to claim 1 or 2, characterized in that, In step S4, the mass concentration of sodium hydroxide solution is 10%-30%.

7. The treatment method of high concentrated organic sulfur-containing pharmaceutical intermediate wastewater according to claim 1 or 2, characterized in that, In step S6, reverse osmosis concentration is carried out under a pressure of 0.1Mpa-0.5Mpa.