A device for treating fine chemical production wastewater by natural gas ammonia oxidation method

Abstract

The utility model relates to a kind of natural gas ammonia oxidation method fine chemical production wastewater treatment device, the effluent in hot hydrolysis device is connected into cyanide breaking pool, the effluent in cyanide breaking pool is connected into front fenton oxidation pool, the effluent in front fenton oxidation pool is connected into coagulation sedimentation tank, the effluent in coagulation sedimentation tank is connected into UASB anaerobic tank, the effluent in UASB anaerobic tank is connected into anaerobic ammonia oxidation tank, the effluent in anaerobic ammonia oxidation tank is connected into primary A / O pool, the effluent in primary A / O pool is connected into secondary A / O pool, the effluent in secondary A / O pool is connected into rear fenton oxidation pool, the effluent in rear fenton oxidation pool is connected into coagulation final sedimentation tank, the effluent in coagulation final sedimentation tank is connected into filtration device.Affection is as follows: using the combined process to carry out wastewater treatment, effect is good, bring new breakthrough and sustainability to wastewater treatment, play key role for the removal of refractory organic matter and SS in wastewater, also provide guarantee for effluent stability to reach standard.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically to a wastewater treatment device for fine chemical production using natural gas ammonia oxidation. Background Technology

[0002] In recent years, the continuous development of hydrogen cyanide derivatives worldwide has led to a steady increase in hydrogen cyanide production. The emergence and increased production of these derivatives have altered the supply and demand relationship for hydrogen cyanide, which has now become an important raw material for fine chemicals. Currently, both domestic and international hydrogen cyanide production capacities are around 11 million tons. In 2023, my country's hydrogen cyanide production capacity reached approximately 725,000 tons. The main production processes include acrylonitrile by-product method, light oil cracking method, and natural gas ammonia oxidation method.

[0003] The natural gas ammonia oxidation process (Angle process) is a method for synthesizing hydrogen cyanide intermediates using natural gas and ammonia as the main raw materials. This method has advantages such as high reactant conversion rate, wide range of production capacity flexibility, low energy consumption and low cost, and more and more industrial enterprises in China are adopting this method.

[0004] Wastewater generated from the natural gas ammonia oxidation process in fine chemical production mainly includes: cyanide-containing wastewater and recalcitrant wastewater. Cyanide-containing wastewater includes: wastewater from HCN and intermediate units, evaporation condensate from iminodiacetonitrile units, concentrated condensate from mother liquor from phenylaminoacetonitrile units, condensate from the DMF recovery tower of diaminomaleitrile units, acid alcohol from orthoformate units, salt washing kettle water, distillation washing tower water, and concentrated condensate from ammonium sulfate mother liquor from ammonium sulfate units. Recalcitrant wastewater includes: production wastewater from dihydroxypyrimidine units, production wastewater from sodium chloride recovery units, evaporation condensate from mother liquor from sodium ferrocyanide units, production wastewater from the mandelic acid unit's product dryer, condensate from the product drying tail gas of diaminomaleitrile units, condensate from the drying tail gas of azobisisobutyronitrile / heptane / valerate products, and concentrated condensate from the recrystallization of ammonium chloride from orthoformate units.

[0005] The components of this type of production wastewater mainly originate from raw materials, production processes, and product types. It is characterized by containing large amounts of cyanide and cyanide derivatives, having a complex composition, and exhibiting extremely strong biotoxicity and bioinhibition. In addition, it is reflected in conventional pollutants such as high concentrations of COD, ammonia nitrogen, and total nitrogen, extremely poor biodegradability, and a large amount of recalcitrant organic matter.

[0006] Currently, there are very few verifiable engineering cases of wastewater treatment in fine chemical industries using natural gas ammonia oxidation. Research on cyanide-containing wastewater mainly includes three methods: physical, chemical, and biological. Physical methods primarily involve hot water hydrolysis; chemical methods mainly include acid recovery, chlorination, hydrogen peroxide oxidation, and electrolysis; and biological methods mainly involve microbial methods. Faced with high-concentration, recalcitrant cyanide-containing wastewater, the use of a single technology is insufficient to solve the problem effectively. Often, the combined use of different processes is required to achieve compliant discharge.

[0007] The main water quality characteristics of wastewater from the common natural gas ammonia oxidation process in fine chemical production are as follows:

[0008] 1) The wastewater has complex components, high pollutant concentrations, and high levels of ammonia nitrogen, total nitrogen, and COD. cr high;

[0009] 2) BOD5 and COD cr The ratio is low, indicating extremely poor biodegradability;

[0010] 3) It contains many recalcitrant substances, is highly toxic, and has a strong biological inhibitory effect. Utility Model Content

[0011] The technical problem this invention aims to solve is that the wastewater from common natural gas ammonia oxidation processes in fine chemical production is characterized by complex components, high pollutant concentrations, and high levels of ammonia nitrogen, total nitrogen, and COD. cr High, BOD5 and COD cr Due to problems such as low ratio, extremely poor biodegradability, many recalcitrant substances, high toxicity, and significant biological inhibition, a wastewater treatment device for fine chemical production using natural gas ammonia oxidation was designed. Through experimental research and engineering practice on this type of wastewater using "hot water hydrolysis + cyanide breaking tank + Fenton oxidation + UASB + anaerobic ammonia oxidation + secondary A / O treatment", a new solution for the treatment of this type of wastewater was provided.

[0012] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0013] A wastewater treatment device for fine chemical production using natural gas ammonia oxidation includes: a hot hydrolysis unit; effluent from the hot hydrolysis unit is fed into a cyanide crushing tank; effluent from the cyanide crushing tank is fed into a pre-Fenton oxidation tank; effluent from the pre-Fenton oxidation tank is fed into a coagulation sedimentation tank; effluent from the coagulation sedimentation tank is fed into a UASB anaerobic tank; effluent from the UASB anaerobic tank is fed into an anaerobic ammonia oxidation tank; effluent from the anaerobic ammonia oxidation tank is fed into a primary A / O tank; effluent from the primary A / O tank is fed into a secondary A / O tank; effluent from the secondary A / O tank is fed into a post-Fenton oxidation tank; effluent from the post-Fenton oxidation tank is fed into a final coagulation sedimentation tank; and effluent from the final coagulation sedimentation tank is fed into a filtration device.

[0014] Based on the above technical solution, the present invention can be further improved as follows.

[0015] Furthermore, the hydraulic residence time in the hot water hydrolysis device is 3h to 4h, the pH value is greater than 9, the decomposition temperature is 140℃ to 165℃, and the reaction pressure is 0.5Mpa to 0.9Mpa.

[0016] Furthermore, the hydraulic retention time in the cyanide destruction tank is 1 to 2 hours, and the hydrogen peroxide dosage ratio is M(H2O2):M(CN). -The ratio is 2:1.

[0017] Furthermore, the hydraulic retention time in the pre-Fenton oxidation tank is 2 hours, and the dosage concentration is C(H2O2):C(COD) = 1:1 to 2:1 (mg / L), C(H2O2):C(Fe 2+ The ratio of H₂O₂ to COD was 1:1 to 3:1 (mg / L); the hydraulic retention time in the Fenton oxidation tank was 2 hours, and the dosage concentration was C(H₂O₂):C(COD) = 1:1 to 2:1 (mg / L), C(H₂O₂):C(Fe₂O₃) = 1:1 to 3:1 (mg / L); 2+ = 1:1 to 3:1 (mg / L).

[0018] Furthermore, the surface loading rate of the coagulation sedimentation tank is 0.6 m. 3 / (m 2 ·h)~2.0m 3 / (m 2 ·h).

[0019] Furthermore, the hydraulic retention time in the UASB anaerobic tank is 30-40 hours, and the COD loading is 1.5 kg COD / (m³). 3 ·d)~3.0kgCOD / (m 3 ·d), the upward flow velocity is less than 0.8 m / h.

[0020] Furthermore, the hydraulic retention time in the anaerobic ammonia oxidation tank is 2-3 days, and the ammonia nitrogen loading is 0.2 kg NH₄⁻. 3 -N / (m 3 ·d)~0.4kgNH 3 -N / (m 3 ·d), the air-to-water ratio is 50:1 to 55:1.

[0021] Furthermore, the total hydraulic retention time in the primary A / O tank is 30h–40h, with the retention time in the primary A tank being 5h–10h and the retention time in the primary O tank being 25h–30h. The nitrification liquor recirculation ratio in the primary A / O tank is 200%–400%. The total hydraulic retention time in the secondary A / O tank is 15h–20h, with the retention time in the secondary A tank being 3h–5h and the retention time in the secondary O tank being 12h–15h. The nitrification liquor recirculation ratio in the secondary A / O tank is 100%–200%.

[0022] Furthermore, the surface loading of the final coagulation settling tank is 0.6m. 3 / (m 2 ·h)~2.0m 3 / (m 2 ·h).

[0023] Furthermore, the filtration device is a sand filter + activated carbon filter. The normal filtration rate of the sand filter + activated carbon filter is 2m / h to 10m / h, the forced filtration rate is 10m / h to 20m / h, and the water backwash intensity is 5.0L / (s·m). 2 ~8.5L / (s·m 2 The air washing intensity is 10 L / (s·m). 2 )~15L / (s·m 2 ).

[0024] The beneficial effects of this utility model are as follows:

[0025] 1. In an alkaline environment, toxic and harmful substances such as cyanide in water are decomposed and reduced through high temperature and high pressure hydrolysis, thereby reducing the concentration of cyanide and alleviating the biological toxicity of wastewater. This process has a significant effect on the removal of biological toxic substances, and the cyanide removal effect can reach more than 99%, which plays a significant role in the stable operation of subsequent treatment processes.

[0026] 2. The cyanide-breaking tank operates well: It makes full use of the waste heat from hot hydrolysis to promote the chemical oxidation and decomposition of cyanide. While cooling the wastewater temperature, it also improves the cyanide-breaking effect, reduces the amount of chemicals needed, and lowers operating costs.

[0027] 3. The ring-opening and detoxification effects of pre-Fenton oxidation tanks: The use of pre-Fenton oxidation tanks can not only open up the cyclic carbon chains of recalcitrant organic matter, but also remove some of the toxic and harmful substances remaining in the water, ensuring the stable operation of subsequent biochemical processes.

[0028] 4. High efficiency of organic matter removal in UASB anaerobic tank: Fully utilize the high efficiency of the anaerobic process section to remove high concentrations of organic matter, greatly reduce organic pollutants in wastewater, reduce the organic load of the subsequent aerobic section. The anaerobic system is designed to achieve a COD removal efficiency of 50%. In addition, the high concentration of biological sludge in the anaerobic section is used to resist the impact of the incoming water, and a biological detoxification method is adopted to deal with any possible residual biological toxicity, ensuring the stability of the subsequent biological system.

[0029] 5. Anaerobic ammonia oxidation (AAO) is a core technology for efficient nitrogen removal: For wastewater with high concentrations of ammonia nitrogen and total nitrogen, conventional AO processes suffer from drawbacks such as high risk of exceeding standards, low nitrogen removal efficiency, long retention time, and large footprint. AAO is an upgraded technology for biological nitrogen removal of ammonia-containing wastewater with low C / N ratios. AAO is carried out by anaerobic bacteria, which can form a "shortcut" in the nitrogen cycle to convert ammonia nitrogen into nitrogen gas under carbon-free and low-oxygen conditions. Oxygen and alkali consumption are reduced by 58% and 50% respectively compared to traditional nitrification processes. It can withstand high ammonia nitrogen influent loads 10 times higher than traditional biological treatment, and its volumetric nitrogen treatment efficiency is 5 times higher than traditional biological treatment, significantly reducing engineering investment and operating costs. The fully mixed-flow design allows for precise control of system nitrate nitrogen concentration, greatly improving the system's nitrogen removal efficiency.

[0030] 6. The two-stage A / O tank is a strong support for the biological treatment system: Through the detoxification, improved biodegradability, and reduced pollutant concentration of the preceding pretreatment and pre-biological processes, the treatment conditions of the traditional A / O process are achieved. However, due to the excessively high absolute value of nitrogen in the wastewater (total nitrogen reaches 1450 mg / L), even after the preceding processes, the total nitrogen concentration is still higher than that of conventional wastewater. Meanwhile, the TP content in the wastewater is relatively normal and can be removed during the sedimentation stage. Therefore, biological phosphorus removal is not required in the conventional biological treatment stage. The targeted two-stage A / O tank is used directly to ensure the total nitrogen removal effect of the effluent and the stable compliance of the effluent.

[0031] 7. The embellishment of filtration + activated carbon adsorption process: This part of the treatment process is an emergency treatment process for the system. When the system is operating normally and can meet the discharge standards, no chemicals need to be added. It is only put into use when the incoming water is abnormal or the effluent does not meet the standards, which plays a safety role and ensures that the effluent meets the discharge standards.

[0032] 8. The combined process of "hot water hydrolysis + cyanide breaking tank + Fenton oxidation + UASB + anaerobic ammonia oxidation + secondary A / O treatment" has a good selection mechanism for granular sludge, ensuring good sludge stability and better shock resistance and adaptability to wastewater in the reactor. In particular, it has good targeting and treatment effect on this type of high-nitrogen toxic wastewater. This is the fundamental reason and prerequisite for its superiority over existing biological systems. In the experiment, the system sludge settled quickly, had a rich biological phase, and showed good resistance to biological inhibition after acclimatization. The effluent effect was ideal, indicating that with appropriate pretreatment measures, this wastewater is suitable for treatment by this combined process with good results. This brings a new breakthrough and sustainability to the treatment of fine chemical wastewater from natural gas ammonia oxidation.

[0033] The "post-Fenton + coagulation final sedimentation tank + filtration + activated carbon adsorption" process is now widely used in the advanced treatment of industrial wastewater. It plays a key role in removing recalcitrant organic matter and suspended solids (SS) from wastewater and ensures that the effluent meets the standards. Attached Figure Description

[0034] Figure 1 This is a structural diagram of the wastewater treatment device for fine chemical production using natural gas ammonia oxidation in this utility model.

[0035] The attached diagram lists the components represented by each number as follows:

[0036] 1. Hot water hydrolysis unit; 2. Cyanide breaking tank; 3. Pre-Fenton oxidation tank; 4. Coagulation sedimentation tank; 5. UASB anaerobic tank; 6. Anaerobic ammonia oxidation tank; 7. Primary A / O tank; 8. Secondary A / O tank; 9. Post-Fenton oxidation tank; 10. Coagulation final sedimentation tank; 11. Filtration unit. Detailed Implementation

[0037] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0038] Example 1

[0039] like Figure 1 As shown, a wastewater treatment device for fine chemical production using natural gas ammonia oxidation includes: a hot hydrolysis unit 1, a cyanide crushing tank 2, a pre-Fenton oxidation tank 3, a coagulation sedimentation tank 4, a UASB anaerobic tank 5, an anaerobic ammonia oxidation tank 6, a primary A / O tank 7, a secondary A / O tank 8, a post-Fenton oxidation tank 9, a coagulation final sedimentation tank 10, and a filtration device 11. The effluent from the hot hydrolysis unit 1 is connected to the cyanide crushing tank 2, and the effluent from the cyanide crushing tank 2 is connected to the pre-Fenton oxidation tank 3. The effluent from the pre-Fenton oxidation tank 3... The effluent from the coagulation sedimentation tank 4 is connected to the UASB anaerobic tank 5. The effluent from the UASB anaerobic tank 5 is connected to the anaerobic ammonia oxidation tank 6. The effluent from the anaerobic ammonia oxidation tank 6 is connected to the primary A / O tank 7. The effluent from the primary A / O tank 7 is connected to the secondary A / O tank 8. The effluent from the secondary A / O tank 8 is connected to the post-Fenton oxidation tank 9. The effluent from the post-Fenton oxidation tank 9 is connected to the final coagulation sedimentation tank 10. The effluent from the final coagulation sedimentation tank 10 is connected to the filtration device 11.

[0040] Example 2

[0041] like Figure 1 As shown, this embodiment is a further improvement on embodiment 1, as detailed below:

[0042] The hydraulic residence time in the hot water hydrolysis device 1 is 3h to 4h, the pH value is greater than 9, the decomposition temperature is 140℃ to 165℃, and the reaction pressure is 0.5Mpa to 0.9Mpa.

[0043] As a preferred option: the hydraulic residence time in the hot water hydrolysis device 1 is 3.4h, the pH value is greater than 9, for example, set to 10, the decomposition temperature is 140℃~165℃, the reaction pressure is 0.7Mpa, and the material of the hot water hydrolysis device 1 can be SUS304.

[0044] The hydraulic retention time in cyanide removal tank 2 is 1-2 hours, and the hydrogen peroxide dosage ratio is M(H2O2):M(CN). - The ratio is 2:1.

[0045] As a preferred option: the hydraulic retention time in cyanide breaking tank 2 is 1.2 h, and the hydrogen peroxide dosage ratio is M(H2O2):M(CN) - The ratio is 2:1. The reagents added to the cyanide breaking tank 2 include H2O2 and alkali, which is existing technology.

[0046] The hydraulic retention time in the pre-Fenton oxidation tank 3 is 2 hours, and the dosage concentration is C(H2O2):C(COD) = 1:1~2:1 (mg / L), C(H2O2):C(Fe 2+ The ratio of H₂O₂ to COD is 1:1 to 3:1 (mg / L); the hydraulic retention time in the Fenton oxidation tank 9 is 1.5h to 2.5h, and the dosage concentration (mg / L) is C(H₂O₂):C(COD) = 1:1 to 2:1 (mg / L), C(H₂O₂):C(Fe₂O₃) = 1:1 to 2:1 (mg / L). 2+ = 1:1 to 3:1 (mg / L).

[0047] As a preferred option: the hydraulic retention time in the pre-Fenton oxidation tank 3 is 2 hours, and the dosage concentration (unit: mg / L) is C(H2O2):C(COD) = 1.4:1, C(H2O2):C(Fe 2+ The ratio of sulfuric acid to alkali is 2:1. The reagents added to the pre-Fenton oxidation tank 3 include sulfuric acid, FeSO4, H2O2 and alkali, which is existing technology.

[0048] As a preferred option: the hydraulic retention time in post-Fenton oxidation tank 9 is 2 hours, and the dosage concentration (unit: mg / L) is C(H2O2):C(COD) = 1.4:1, C(H2O2):C(Fe 2+ The ratio of sulfuric acid to FeSO4 is 2:1. The reagents added to the Fenton oxidation tank 9 include sulfuric acid, FeSO4, H2O2 and alkali, which is existing technology.

[0049] The surface loading of coagulation sedimentation tank 4 is 0.6 m. 3 / (m 2 ·h)~2.0m 3 / (m2 ·h).

[0050] As a preferred option: the surface loading of coagulation sedimentation tank 4 is 1.5m. 3 / (m 2 ·h), the reagent added to the coagulation sedimentation tank 4 is PAM, which is existing technology.

[0051] The hydraulic retention time in UASB anaerobic tank 5 is 30-40 hours, and the COD loading is 1.5 kg COD / (m³). 3 ·d)~3.0kgCOD / (m 3 ·d), the upward flow velocity is less than 0.8 m / h.

[0052] As a preferred option: the hydraulic retention time in UASB anaerobic tank 5 is 35 hours, and the COD load is 2 kg COD / (m³). 3 ·d) When the upward flow velocity is less than 0.8 m / h, a pulse water distributor is used, and the pulse water distributor is equipped with a steam heating pipe.

[0053] The hydraulic retention time in anaerobic ammonia oxidation tank 6 is 2-3 days, and the ammonia nitrogen loading is 0.2 kg NH₄⁻. 3 -N / (m 3 ·d)~0.4kgNH 3 -N / (m 3 ·d), the air-to-water ratio is 50:1 to 55:1.

[0054] As a preferred option: the hydraulic retention time in anaerobic ammonia oxidation tank 6 is 2.5 days, and the ammonia nitrogen loading is 0.3 kg NH₄⁻. 3 -N / (m 3 ·d), the air-to-water ratio is 52:1, and a nutrient salt addition system is provided. The reagents added to the anaerobic ammonia oxidation tank 6 are CH3OH and alkali, which is existing technology.

[0055] The total hydraulic retention time in the primary A / O tank 7 is 30-40 hours, with the retention time in the primary A tank being 5-10 hours and the retention time in the primary O tank being 25-30 hours. The nitrification liquor recirculation ratio in the primary A / O tank 7 is 200%-400%. The total hydraulic retention time in the secondary A / O tank 8 is 15-20 hours, with the retention time in the secondary A tank being 3-5 hours and the retention time in the secondary O tank being 12-15 hours. The nitrification liquor recirculation ratio in the secondary A / O tank 8 is 100%-200%.

[0056] As a preferred embodiment: the total hydraulic retention time in the primary A / O tank 7 is 35 hours, of which the retention time in the primary A tank is 8 hours and the retention time in the primary O tank is 27 hours. The nitrification liquor recirculation ratio in the primary A / O tank 7 is 300%. The reagents added to the primary A / O tank 7 are CH3OH and alkali, which is existing technology. The total hydraulic retention time in the secondary A / O tank 8 is 16 hours, of which the retention time in the secondary A tank is 3.5 hours and the retention time in the secondary O tank is 12.5 hours. The nitrification liquor recirculation ratio in the secondary A / O tank 8 is 100%. The reagents added to the secondary A / O tank 8 are CH3OH and alkali, which is existing technology.

[0057] The surface loading of the final settling tank 10 is 0.6m. 3 / (m 2 ·h)~2.0m 3 / (m 2 ·h).

[0058] As a preferred option, the surface load of the final coagulation sedimentation tank 10 is 1.5m. 3 / (m 2 ·h), the agent added to the final sedimentation tank 10 is PAM, which is existing technology.

[0059] Filter device 11 is a sand filter + activated carbon filter. The normal filtration rate of the sand filter + activated carbon filter is 2m / h to 10m / h, the forced filtration rate is 10m / h to 20m / h, and the water backwash intensity is 5.0L / (s·m). 2 ~8.5L / (s·m 2 The air washing intensity is 10 L / (s·m). 2 )~15L / (s·m 2 ).

[0060] As a preferred embodiment, the filtration device 11 is a sand filter + activated carbon filter, which consists of an activated sand filter and an activated carbon filter connected in series. The normal filtration rate of the sand filter + activated carbon filter is 6 m / h, the forced filtration rate is 12 m / h, and the backwash intensity is 8 L / (sm). 2 The air washing intensity is 15 L / (sm). 2 The sand filter + activated carbon filter is designed to backwash every 1 to 2 days, with the activated carbon reuse rate reaching over 90%.

[0061] The wastewater treatment process for fine chemical production using natural gas ammonia oxidation includes the following steps:

[0062] S1: The collected wastewater from the natural gas ammonia oxidation process for fine chemical production is fed into the hot hydrolysis unit 1. Under high temperature and high pressure conditions, the cyanide in the wastewater is decomposed by hydrolysis and converted into ammonia, thus reducing biological toxicity.

[0063] S2: The wastewater treated by the hot water hydrolysis device 1, after preliminary cyanide removal by hot water hydrolysis, enters the cyanide removal tank 2 for further cyanide removal and detoxification to reduce the biological inhibition of the wastewater.

[0064] S3: The wastewater treated by the cyanide breaking tank 2 enters the pre-Fenton oxidation tank 3, where aniline, formaldehyde, nitriles and other substances undergo ring-opening and chain breaking, and substances that are difficult to biodegrade are chemically degraded, thereby reducing the biotoxicity of the wastewater and improving its biodegradability.

[0065] S4: The wastewater treated by the pre-Fenton oxidation tank 3 enters the coagulation sedimentation tank 4, where large flocs are formed under the action of coagulants and flocculants, and mud and water are separated.

[0066] S5: The supernatant after sedimentation in coagulation sedimentation tank 4 enters UASB anaerobic tank 5, where a large portion of the organic matter in the wastewater is initially removed through anaerobic biochemical action. At the same time, microorganisms are used for biological detoxification, and the biodegradability of the wastewater is improved, thereby improving the reaction conditions of the subsequent biological reaction tank.

[0067] S6: The wastewater treated by UASB anaerobic tank 5 enters anaerobic ammonia oxidation tank 6. Through the action of special anaerobic ammonia oxidation bacteria, the ammonia nitrogen concentration in the wastewater is decomposed and removed, reducing the ammonia nitrogen and total nitrogen load of subsequent biological treatment units.

[0068] S7: The wastewater treated by the anaerobic ammonia oxidation tank 6 enters the primary A / O tank 7, where ammonia nitrogen and total nitrogen in the wastewater are removed through nitrification and denitrification by microorganisms, while consuming and removing organic matter in the wastewater.

[0069] S8: The treated wastewater from the primary A / O tank 7 enters the secondary A / O tank 8, where microbial nitrification and denitrification further remove ammonia nitrogen and total nitrogen from the wastewater, while consuming and removing organic matter in the wastewater, thus enhancing the removal effect of pollutants and ensuring the quality of the effluent.

[0070] S9: The wastewater treated by the secondary A / O tank 8 enters the post-Fenton oxidation tank 9, where the COD substances that have not been biochemically degraded in the wastewater are decomposed and removed by the strong oxidation effect of the hydroxyl free radicals generated by the Fenton reagent.

[0071] S10: The wastewater treated by the post-Fenton oxidation tank 9 enters the coagulation final sedimentation tank 10. By adjusting the pH value and adding flocculants, large flocs are formed, which can convert the iron salt in the Fenton agent (which also acts as a coagulant) into sludge and separate it from the wastewater.

[0072] S11: The wastewater treated by the coagulation final sedimentation tank 10 enters the filtration device 11 to intercept and remove suspended matter in the wastewater, adsorb residual organic matter, color substances, etc. in the wastewater, and ensure that the effluent meets the discharge standards.

[0073] Additional notes: The pre-Fenton oxidation tank 3, post-Fenton oxidation tank 9, coagulation final sedimentation tank 10, and filtration device 11 in the advanced treatment are the guarantee process sections of this project. In particular, the sand filter + activated carbon filter device can be used without adding chemicals when it is operating normally and can meet the discharge standards. It should only be put into use when the system influent is abnormal or the effluent does not meet the standards to ensure that the effluent meets the discharge standards.

[0074] The advantages of using a natural gas ammonia oxidation process wastewater treatment unit to treat wastewater from fine chemical production are as follows:

[0075] 1. In an alkaline environment, toxic and harmful substances such as cyanide in water are decomposed and reduced through high temperature and high pressure hydrolysis, thereby reducing the concentration of cyanide and alleviating the biological toxicity of wastewater. This process has a significant effect on the removal of biological toxic substances, and the cyanide removal effect can reach more than 99%, which plays a significant role in the stable operation of subsequent treatment processes.

[0076] 2. The cyanide breaking tank 2 is operating well: it makes full use of the waste heat from hot hydrolysis to promote the chemical oxidation and decomposition of cyanide. While cooling the wastewater temperature, it also improves the cyanide breaking effect, reduces the amount of chemicals needed, and lowers operating costs.

[0077] 3. The ring-opening and detoxification effects of pre-Fenton oxidation tank 3: In addition to opening the cyclic carbon chains of recalcitrant organic matter, the application of pre-Fenton oxidation tank 3 can also remove some of the toxic and harmful substances remaining in the water, ensuring the stable operation of the subsequent biochemical process section.

[0078] 4. High-efficiency removal of organic matter in UASB anaerobic tank: Fully utilize the high-efficiency removal effect of anaerobic process section on high-concentration organic matter, greatly reduce organic pollutants in wastewater, reduce the organic load of subsequent aerobic section. The anaerobic system considers a COD removal efficiency of 50%. In addition, the high-concentration biological sludge in the anaerobic section is used to resist the impact of incoming water, and a biological detoxification method is adopted to deal with any possible residual biological toxicity, ensuring the stability of subsequent biological system.

[0079] 5. Anaerobic ammonia oxidation (AAO) is a core technology for efficient nitrogen removal: For wastewater with high concentrations of ammonia nitrogen and total nitrogen, conventional AO processes suffer from drawbacks such as high risk of exceeding standards, low nitrogen removal efficiency, long retention time, and large footprint. AAO is an upgraded technology for biological nitrogen removal of ammonia-containing wastewater with low C / N ratios. AAO is carried out by anaerobic bacteria, which can form a "shortcut" in the nitrogen cycle to convert ammonia nitrogen into nitrogen gas under carbon-free and low-oxygen conditions. Oxygen and alkali consumption are reduced by 58% and 50% respectively compared to traditional nitrification processes. It can withstand high ammonia nitrogen influent loads 10 times higher than traditional biological treatment, and its volumetric nitrogen treatment efficiency is 5 times higher than traditional biological treatment, significantly reducing engineering investment and operating costs. The fully mixed-flow design allows for precise control of system nitrate nitrogen concentration, greatly improving the system's nitrogen removal efficiency.

[0080] 6. The two-stage A / O tank is a strong support for the biological treatment system: Through the detoxification, improved biodegradability, and reduced pollutant concentration of the preceding pretreatment and pre-biological processes, the treatment conditions of the traditional A / O process are achieved. However, due to the excessively high absolute value of nitrogen in the wastewater (total nitrogen reaches 1450 mg / L), even after the preceding processes, the total nitrogen concentration is still higher than that of conventional wastewater. Meanwhile, the TP content in the wastewater is relatively normal and can be removed during the sedimentation stage. Therefore, biological phosphorus removal is not required in the conventional biological treatment stage. The targeted two-stage A / O tank is used directly to ensure the total nitrogen removal effect of the effluent and the stable compliance of the effluent.

[0081] 7. The embellishment of filtration + activated carbon adsorption process: This part of the treatment process is an emergency treatment process for the system. When the system is operating normally and can meet the discharge standards, no chemicals need to be added. It is only put into use when the incoming water is abnormal or the effluent does not meet the standards, which plays a safety role and ensures that the effluent meets the discharge standards.

[0082] 8. The combined process of "hot water hydrolysis + cyanide breaking tank + Fenton oxidation + UASB + anaerobic ammonia oxidation + secondary A / O treatment" has a good selection mechanism for granular sludge, ensuring good sludge stability and better shock resistance and adaptability to wastewater in the reactor. In particular, it has good targeting and treatment effect on this type of high-nitrogen toxic wastewater. This is the fundamental reason and prerequisite for its superiority over existing biological systems. In the experiment, the system sludge settled quickly, had a rich biological phase, and showed good resistance to biological inhibition after acclimatization. The effluent effect was ideal, indicating that with appropriate pretreatment measures, this wastewater is suitable for treatment by this combined process with good results. This brings a new breakthrough and sustainability to the treatment of fine chemical wastewater from natural gas ammonia oxidation.

[0083] The "post-Fenton + coagulation final sedimentation tank + filtration + activated carbon adsorption" process is now widely used in the advanced treatment of industrial wastewater. It plays a key role in removing recalcitrant organic matter and suspended solids (SS) from wastewater and ensures that the effluent meets the standards.

[0084] Application Example 1

[0085] A hot water hydrolysis test was conducted on a cyanide-containing water sample in a laboratory. An appropriate amount of sodium hydroxide was added to adjust the pH value to about 10. The mixture was prepared with 800 mg / L sodium cyanide, 1000 mg / L orthoiminodiacetonitrile, 100 mg / L aniline acetonitrile, and 0.5 ppm sodium cyanide as the stock solution for the test.

[0086] Take 50 ml of each of the prepared stock solutions and place them in a reaction vessel. Set the test temperature to 160℃ (the standard GB / T 32123-2015 requires a temperature of 140℃~165℃) and conduct a heat preservation test. It takes about 40 minutes for the reaction vessel to reach 160℃. Then start the heat preservation timer and set the heat preservation time to 2h, 3h and 4h respectively. After that, turn off the power and wait for the temperature of the reaction vessel to drop to room temperature. Take out the test solution and send it to test the total cyanide and free cyanide in the test solution.

[0087] Table 1 shows the results of the cyanide removal test.

[0088] Sample Name Sample number Free cyanide content (mg / l) Total cyanide content (mg / l) Test stock solution <![CDATA[1 # water sample 775 788 The test solution reacted for 2 hours. <![CDATA[2 # water sample 118 147 Reaction time 3 hours test solution <![CDATA[3 # water sample 0.522 9.53 The test solution reacted for 4 hours. <![CDATA[4 # water sample 0.338 3.56

[0089] The results of the cyanide removal test show that the hot water decomposition process does not require the addition of chemical raw materials and does not add new chlorides. Under the conditions of high temperature reactor (temperature 160℃), after 3 hours of reaction, the removal rates of free cyanide and total cyanide are as high as 99.9% and 98.8%, respectively; after 4 hours of reaction, the removal rates of free cyanide and total cyanide are as high as 99.9% and 99.5%, respectively. The operation is stable and reliable.

[0090] Application Example 2

[0091] A pilot-scale test was conducted at the wastewater treatment plant of a natural gas fine chemical company in a certain location. Using wastewater from the wastewater treatment plant's collection pool as the water source, and controlling the parameters according to the steps described above, the following pollutant removal effects were obtained.

[0092] Table 2 shows the pollutant removal efficiency along the process.

[0093]

[0094]

[0095] Note: The advanced treatment process includes: post-Fenton coagulation, final sedimentation tank, filtration + activated carbon adsorption.

[0096] The data comparison and analysis from the above pilot-scale test show that the main process route of "hot water hydrolysis + cyanide breaking tank + Fenton oxidation + UASB + anaerobic ammonia oxidation + secondary A / O treatment + post-Fenton + coagulation final sedimentation tank + filtration + activated carbon adsorption" is feasible. This system can be integrated and the process sections can be flexibly adjusted according to the influent conditions. It has advantages such as small footprint, strong resistance to water volume and water quality fluctuations, low energy consumption, and very stable effluent quality. It is efficient, low-carbon, and sustainable for the treatment of wastewater from natural gas ammonia oxidation fine chemical production.

[0097] Hot water hydrolysis and hydrogen peroxide oxidation for cyanide removal are highly effective in removing cyanide from wastewater from natural gas ammonia oxidation fine chemical production. They significantly reduce the biotoxicity of the wastewater and greatly improve its bioinhibition properties, ensuring efficient and stable operation of subsequent biochemical treatment processes. Considering both treatment effectiveness and maintenance costs, a hydraulic retention time of 3.4 h, a pH greater than 9, a decomposition temperature of 140℃~165℃, and a reaction pressure of 0.7 MPa are suitable for the hot water hydrolysis unit. A hydraulic retention time of 1.2 h is also suitable for the cyanide removal tank. The hydrogen peroxide dosage ratio is M(H2O2):M(CN). - A ratio of 2:1 is reasonable.

[0098] The application of pre-Fenton oxidation significantly improves the biodegradability of wastewater and ensures the stable operation of subsequent process stages. Experimental results show that the hydraulic retention time in the pre-Fenton oxidation tank is 2 hours, and the dosage concentration (mg / L) is C(H₂O₂):C(COD) = 1.4:1, C(H₂O₂):C(Fe₂O₃) = 1.4:1. 2+ The ratio of 2:1 is economically feasible.

[0099] The combined process of "hot water hydrolysis + cyanide breaking tank + Fenton oxidation + UASB + anaerobic ammonia oxidation + secondary A / O treatment" has a good selection mechanism for granular sludge, ensuring good sludge stability and better shock resistance and adaptability to wastewater. In particular, it has good targeting and treatment effect on this type of high-nitrogen toxic wastewater, which is the fundamental reason and prerequisite for its superiority over existing biological systems. In the experiment, the system sludge settling speed was fast, the biological phase was rich, and after acclimatization, it had good resistance to biological inhibition. The effluent effect was ideal, indicating that with appropriate pretreatment measures, this wastewater is suitable for treatment by this combined process with good results. This brings a new breakthrough and sustainability to the treatment of fine chemical wastewater from natural gas ammonia oxidation. "Post-Fenton + coagulation final sedimentation tank + filtration + activated carbon adsorption" is also widely used in the deep treatment process of industrial wastewater. It plays a key role in the removal of recalcitrant organic matter and suspended solids in wastewater and provides a guarantee for stable effluent compliance.

[0100] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A wastewater treatment device for fine chemical production using natural gas ammonia oxidation, characterized in that, include: The hot water hydrolysis device (1) is connected to the cyanide breaking tank (2), the effluent from the cyanide breaking tank (2) is connected to the pre-Fenton oxidation tank (3), the effluent from the pre-Fenton oxidation tank (3) is connected to the coagulation sedimentation tank (4), the effluent from the coagulation sedimentation tank (4) is connected to the UASB anaerobic tank (5), the effluent from the UASB anaerobic tank (5) is connected to the anaerobic ammonia oxidation tank (6), the effluent from the anaerobic ammonia oxidation tank (6) is connected to the primary A / O tank (7), the effluent from the primary A / O tank (7) is connected to the secondary A / O tank (8), the effluent from the secondary A / O tank (8) is connected to the post-Fenton oxidation tank (9), the effluent from the post-Fenton oxidation tank (9) is connected to the coagulation final sedimentation tank (10), and the effluent from the coagulation final sedimentation tank (10) is connected to the filtration device (11).

2. The wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The hydraulic residence time in the hot water hydrolysis device (1) is 3h to 4h, the pH value is greater than 9, the decomposition temperature is 140℃ to 165℃, and the reaction pressure is 0.5Mpa to 0.9Mpa.

3. The wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The hydraulic retention time in the cyanide-breaking tank (2) is 1h to 2h, and the hydrogen peroxide dosage ratio is M(H2O2):M(CN). - The ratio is 2:

1.

4. The wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The hydraulic retention time in the pre-Fenton oxidation tank (3) is 2 hours, and the dosage concentration is C(H2O2):C(COD) = 1:1 to 2:1 (mg / L), C(H2O2):C(Fe 2+ The ratio of H2O2 to COD is 1:1 to 3:1 (mg / L); the hydraulic retention time in the post-Fenton oxidation tank (9) is 1.5h to 2.5h, and the dosage concentration (mg / L) is C(H2O2):C(COD) = 1:1 to 2:1 (mg / L), C(H2O2):C(Fe 2+ = 1:1 to 3:1 (mg / L).

5. The wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The surface loading of the coagulation sedimentation tank (4) is 0.6 m. 3 / (m 2 ·h)~2.0m 3 / (m 2 ·h).

6. The wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The hydraulic retention time in the UASB anaerobic tank (5) is 30-40 hours, and the COD load is 1.5 kg COD / (m³). 3 ·d)~3.0kgCOD / (m 3 ·d), the upward flow velocity is less than 0.8 m / h.

7. The wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The hydraulic retention time in the anaerobic ammonia oxidation tank (6) is 2-3 days, and the ammonia nitrogen load is 0.2 kg NH₄⁻. 3 -N / (m 3 ·d)~0.4kgNH 3 -N / (m 3 ·d), the air-to-water ratio is 50:1 to 55:

1.

8. The wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The total hydraulic retention time in the primary A / O tank (7) is 30h to 40h, of which the retention time in the primary A tank is 5h to 10h and the retention time in the primary O tank is 25h to 30h. The nitrification liquor recirculation ratio in the primary A / O tank (7) is 200% to 400%. The total hydraulic retention time in the secondary A / O tank (8) is 15h to 20h, of which the retention time in the secondary A tank is 3h to 5h and the retention time in the secondary O tank is 12h to 15h. The nitrification liquor recirculation ratio in the secondary A / O tank (8) is 100% to 200%.

9. A wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The surface loading of the coagulation final settling tank (10) is 0.6 m. 3 / (m 2 ·h)~2.0m 3 / (m 2 ·h).

10. A wastewater treatment device for fine chemical production using natural gas ammonia oxidation as described in claim 1, characterized in that, The filtration device (11) is a sand filter + activated carbon filter. The normal filtration rate of the sand filter + activated carbon filter is 2m / h to 10m / h, the forced filtration rate is 10m / h to 20m / h, and the water backwash intensity is 5.0L / (s·m). 2 ~8.5L / (s·m 2 The air washing intensity is 10 L / (s·m). 2 )~15L / (s·m 2 ).

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