Process for treating organic fluorine waste water

Abstract

The application discloses a kind of organic fluorine wastewater treatment processes, belong to wastewater treatment technical field.The kind of organic fluorine wastewater treatment process, by the organic fluorine wastewater collected in turn through adjusting pool, primary defluorination reaction pool, ultrasonic synergistic ozone catalytic reaction tower (US-O3 catalytic reaction tower), secondary defluorination reaction pool, depth defluorination reaction pool and biochemical reaction pool are handled, and the effluent of low fluoride ion and low COD is obtained, to meet the emission standard.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to an organic fluorine wastewater treatment process. Background Technology

[0002] The main sources of organic fluorine wastewater are the fluorochemical and electronics industries. This wastewater often contains persistent organic fluorine pollutants such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). The CF bond energy of these pollutants is as high as 485 kJ / mol, giving them extremely strong chemical stability and bioaccumulation, making conventional treatment methods ineffective and hindering efficient degradation. While calcium precipitation can remove some inorganic fluoride ions to a certain extent, it is essentially ineffective for treating wastewater containing organic fluorides. Conventional biochemical processes and advanced oxidation technologies such as Fenton oxidation and ozone catalytic oxidation are not effective in breaking CF bonds and also suffer from drawbacks such as high reagent consumption and energy consumption. With increasingly stringent environmental protection requirements, national and local governments are gradually raising fluoride emission standards, placing higher demands on wastewater treatment. Therefore, developing a highly efficient and energy-saving organic fluorine wastewater treatment technology has become an urgent need in the environmental protection field.

[0003] Patent CN113185031B discloses a process for treating fluorinated aromatic hydrocarbon wastewater. This process utilizes an ion exchange resin tower with an automatically replaceable filter screen. The wastewater treatment process includes the following steps: 1. Pre-treating the resin; 2. Acid and alkali washing the resin within the resin tower; 3. Pre-treating the fluorinated aromatic hydrocarbon wastewater; 4. Pumping the pre-treated wastewater into the resin tower for adsorption treatment. This invention effectively treats fluorinated aromatic hydrocarbon wastewater and significantly increases the speed of filter replacement, avoiding prolonged shutdowns of wastewater treatment during filter replacement, thus improving treatment efficiency. It also allows for quick and easy attachment of the cover to the tower, greatly enhancing resin replacement efficiency and ease of use. However, while the above method improves treatment and resin replacement efficiency to some extent, it still has limitations when treating organic fluoride wastewater. Due to the complex and diverse composition of different organic fluoride wastewaters, the ion exchange resin in this process has limited selectivity for specific complex organic fluoride components, making it difficult to comprehensively and efficiently treat various organic fluoride pollutants, thus affecting the overall treatment effect. Summary of the Invention

[0004] The purpose of this invention is to provide an organic fluorine wastewater treatment process that degrades organic fluorine pollutants in wastewater from the fluorination industry into inorganic fluoride ions and performs deep treatment, thereby improving the biodegradability of the wastewater and realizing the resource utilization of calcium fluoride sludge.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a process for treating organic fluorine wastewater, comprising the following steps: Step 1: Organic fluoride wastewater is pumped through pipelines to the equalization tank. The mechanical agitator is started to mix the wastewater evenly. Then the pH is adjusted and homogenized before being pumped to the primary defluorination reaction tank. Step 2: Add calcium hydroxide to the primary defluorination reaction tank, followed by the addition of composite flocculant. After stirring and mixing, the mixture is pumped to the high-efficiency sedimentation tank. Step 3: Using inclined plate sedimentation technology, the wastewater flows in the sedimentation zone, and sediment settles. The supernatant is collected from the top overflow weir and pumped to the US-O3 catalytic reaction tower. The settled sludge is collected and transported to sludge storage tank 1 by sludge pump. The sludge contains calcium fluoride, which is dewatered and then utilized as a resource. Step 4: Ozone is generated by an ozone generator and injected into the US-O3 catalytic reaction tower using an aeration distributor. Hydrogen peroxide is added as an initiator, and the ozone oxidation is treated by ultrasonic enhancement catalysis. The oxidized wastewater is then pumped into the secondary defluorination reaction tank. Step 5: Continue to add composite flocculant and calcium hydroxide to the secondary defluorination reaction tank. After mechanical stirring, the wastewater enters the second high-efficiency sedimentation tank, the sludge is transported to the first sludge storage tank, and the supernatant is pumped into the deep defluorination reaction tank. Activated alumina is added, and after stirring and reaction, the wastewater enters the third high-efficiency sedimentation tank. Step Six: The sludge produced in the high-efficiency sedimentation tank three is stored in the sludge storage tank two. The sludge is pumped from the sludge storage tank into the sludge dewatering machine for processing, and then outsourced for further processing. Step 7: Wastewater from high-efficiency sedimentation tank 3 is pumped into the biological reaction tank for anaerobic / aerobic treatment to obtain a mixed liquor. Then, solid-liquid separation is performed. The solids are sent to sludge storage tank 2, and the supernatant is pumped into the effluent storage tank for pH adjustment and testing. If the pH meets the standards, it is pumped for discharge into the sewer system or reused in production. If the pH does not meet the standards, it is returned to the equalization tank for retreatment.

[0006] Preferably, in step one, the stirring speed is 10-30 rpm, and 1 mol / L sulfuric acid or 1 mol / L sodium hydroxide is added to adjust the pH to 6-8.

[0007] Preferably, in step two, the dosage of calcium hydroxide is 0.5-2 g / L, the dosage of composite flocculant is 0.1-0.5 g / L, the mixing speed is 30-60 rpm, and the time is 20-30 min.

[0008] Preferably, the preparation method of the composite flocculant includes the following steps: Q1: Chitosan was added to an aqueous acetic acid solution and stirred magnetically. Ethanol was then added and stirred to obtain a mixed solution. 2,6-Dimethyl-5-heptenal was added to ethanol and stirred to obtain a mixed solution. After stirring and mixing, the mixture was added dropwise to the mixed solution. After heating and reflux, sodium borohydride was added. After stirring at room temperature, the mixture was added to ethanol and freeze-dried to obtain solid product 1. Q2: Add solid product 1 to N-methylpyrrolidone, react in an ice bath, add sodium iodide, sodium hydroxide aqueous solution and iodomethane in sequence, heat under reflux, filter, wash, freeze dry to obtain solid product 2. Q3: Add solid product 2 to N-methylpyrrolidone, stir and mix, then add acrylamide, ammonium persulfate and N,N'-methylenebisacrylamide, react at a constant temperature, cool, filter, vacuum dry and purify to obtain composite flocculant.

[0009] In the above process, the amino group of chitosan undergoes a nucleophilic addition-dehydration reaction with the aldehyde group of 2,6-dimethyl-5-heptenal to generate an imine structure. Then, sodium borohydride is used as a reducing agent to reduce the imine to a secondary amine. Subsequently, in N-methylpyrrolidone, iodomethane undergoes a nucleophilic substitution reaction with the amino group in solid product 1 to obtain solid product 2. Then, solid product 2, acrylamide, and N,N'-methylenebisacrylamide undergo a free radical polymerization reaction to obtain a composite flocculant.

[0010] Preferably, in Q1, the ratio of chitosan, aqueous acetic acid solution, 2,6-dimethyl-5-heptenal, and sodium borohydride is (1.48-1.83) g : (45-55) mL : (2.71-2.94) g : (1.35-1.68) g, the volume fraction of the aqueous acetic acid solution is 1 wt%, the heating reflux temperature is 60-65℃, the time is 10-12 h, and the mixture is stirred at room temperature for 2-5 h.

[0011] Preferably, in Q2, the ratio of solid product 1, N-methylpyrrolidone, sodium iodide, sodium hydroxide, and iodomethane is (1.64-2.04) g : (70-80) mL : (4.1-4.8) g : (10-20) mL : (12.5-16.3) mL, the ice bath reaction time is 0.5-1 h, the mass fraction of the sodium hydroxide aqueous solution is 15 wt%, the reflux temperature is 55-65 °C, and the time is 2-4 h; in Q3, the ratio of solid product 2, N-methylpyrrolidone, acrylamide, and N,N'-methylenebisacrylamide is (2.21-2.84) g : (50-64) mL : (3.12-3.65) g : (2.05-2.53) g, the mixture is stirred for 10-15 min, and then ethanol is added for filtration.

[0012] Preferably, in step three, the surface load in the inclined plate deposition technique is 1-2 m.3 / m 2 • h; In step four, the ozone injection amount is 20-50 mg / L, the ultrasonic reaction frequency is 35-45 kHz, the time is 1-2 h, the hydrogen peroxide dosage is 10-15 mL / L, the treatment temperature is 30-40℃, and the hydraulic retention time is 30-45 min.

[0013] Preferably, in step five, the dosage of the composite flocculant is 0.1-0.2 g / L, the dosage of calcium hydroxide is 0.8-1.2 g / L, the mechanical stirring speed is 20-40 rpm, the reaction time is 15-25 min, the pH is 9-10, the dosage of activated alumina is 0.9-1.7 g / L, and the stirring reaction is carried out for 20-30 min.

[0014] Preferably, in step six, the pressure of the sludge dewatering machine is 0.4-0.8 MPa, and the centrifugal speed is 2000-3000 rpm.

[0015] Preferably, in step seven, during the anaerobic treatment process, the hydraulic retention time is 8-12 hours, the rotation speed is 10-20 rpm, and no aeration is performed. During the aerobic treatment process, the dissolved oxygen is controlled at 2-4 mg / L through a microporous aerator, and the hydraulic retention time is 12-24 hours.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In the process of treating organic fluoride wastewater, this invention adds a composite flocculant containing a high-strength positive charge, which can effectively neutralize negatively charged fluoride ions, organic fluoride colloids, and emulsion droplets. Its ultra-high molecular weight branched network structure can simultaneously adsorb multiple pollutant particles, accelerating sedimentation. Furthermore, the long-chain alkyl groups introduced during the preparation process can capture hydrophobic organic fluoride ions, achieving the removal of dissolved organic fluoride pollutants that is difficult to achieve with traditional flocculants.

[0017] 2. In the process of treating organic fluoride wastewater, this invention can break the carbon-fluorine bonds in organic fluoride through ultrasonic-enhanced catalytic ozone oxidation, achieving a degradation efficiency of over 90%. Furthermore, through a two-stage defluorination reaction and a deep defluorination process, the fluoride ion concentration in the effluent is reduced to below 1.5 mg / L, an effect that is difficult to achieve with existing biochemical and Fenton processes.

[0018] 3. In the process of treating organic fluoride wastewater, this invention can adjust the ozone dosage in real time by detecting the oxidation-reduction potential and the concentration of fluoride ions, and switch between different frequencies of ultrasound and adjust the ultrasound power, which can save more than 20% of the system energy consumption.

[0019] 4. This invention installs an online fluoride ion meter and pH meter in the effluent of the secondary defluorination reaction tank to detect the fluoride ion concentration in the effluent in a timely manner. This can effectively adjust the dosage of composite flocculant, calcium hydroxide and activated alumina, saving the amount of reagents used.

[0020] 5. The treatment method of the present invention can effectively remove chemical oxygen demand (COD) from wastewater, making the biochemical oxygen demand (BOD) / COD ratio in the effluent > 0.3. After further treatment in the biochemical reaction tank, the COD in the effluent is reduced to below 50 mg / L, meeting the discharge requirements. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flow chart of the organic fluorine wastewater treatment process of the present invention; Figure 2 This is a schematic diagram of the US-O3 catalytic reaction tower in this invention.

[0023] Figure reference numerals: 1. Intermediate storage tank, 2. Reactor body, 3. Honeycomb catalyst, 4. Ultrasonic generator, 5. Feed pump, 6. Jet distributor, 7. Ozone destroyer, 8. Ultrasonic generator, 9. Ultrasonic vibrator, 10. Ultrasonic enhanced gas-liquid mixer, 11. Titanium alloy microporous aerator, 12. Gas-liquid mixing dissolved air pump, 13. Hydrogen peroxide storage tank, 14. Dosing pump, 15. Ozone generator, 16. Biochemical system, 17. Aeration distribution system, 18. Aeration blower. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1: This example discloses a US-O3 catalytic reaction tower, which has been disclosed in the invention patent CN2022103200574 entitled "Ultrasonic Enhanced Ozone Catalytic Oxidation Treatment Device and Method". It includes an intermediate storage tank 1, a reactor body 2, an ozone destroyer 7, an ultrasonic enhanced gas-liquid mixer 10, a hydrogen peroxide storage tank 13, an ozone generator 15, a biochemical system 16, and an aeration distribution system 17. The reactor body 2 is externally connected to the ultrasonic generator 4 and internally contains a honeycomb catalyst 3. Its bottom is connected to a jet distributor 6. One end of the reactor body 2 is connected to the ultrasonic generator 4 via a gas-liquid mixing dissolved air pump 12. The ultrasonic-enhanced gas-liquid mixer 10 is equipped with a titanium alloy microporous aerator 11 at its bottom, and its other end is connected to an ozone generator 15. The top of the reactor body 2 is connected to an ozone destroyer 7 and an aeration blower 18. The outlet of the aeration blower is connected to an aeration distribution system 17. At the same time, a biochemical system 16 is set on the top of the aeration distribution system 17. An ultrasonic vibrating rod 9 is installed on the top of the ultrasonic-enhanced gas-liquid mixer 10. The ultrasonic vibrating rod 9 is connected to an ultrasonic generator 8. The hydrogen peroxide storage tank 13 is connected to the ultrasonic-enhanced gas-liquid mixer 10 through a dosing pump 14. The intermediate storage tank 1 supplies water to the reactor body 2 through a water supply pump 5.

[0026] Example 2: This example discloses a method for preparing a composite flocculant, including the following steps: Q1: Add 1.65g of chitosan to 50mL of acetic acid aqueous solution with a volume fraction of 1vt%, stir magnetically, add 50mL of ethanol, stir to obtain a mixed solution, add 2.82g of 2,6-dimethyl-5-heptenal to 80mL of ethanol, stir and mix, then add dropwise to the mixed solution, heat under reflux at 60℃ for 12h, add 1.45g of sodium borohydride, stir at room temperature for 5h, then add to ethanol, freeze dry to obtain solid product 1; Q2: Add 1.84g of solid product 1 to 75mL of N-methylpyrrolidone and react in an ice bath for 1h. Then add 4.4g of sodium iodide, 15mL of 15wt% sodium hydroxide aqueous solution and 14.4mL of iodomethane in sequence. After heating and refluxing at 60℃ for 4h, filter, wash and freeze dry to obtain solid product 2. Q3: Add 2.52g of solid product 2 to 57mL of N-methylpyrrolidone, stir and mix for 15min, then add 3.37g of acrylamide, 0.08g of ammonium persulfate and 2.29g of N,N'-methylenebisacrylamide, react at a constant temperature, cool, add ethanol for filtration, vacuum dry and purify to obtain the composite flocculant.

[0027] This embodiment discloses a process for treating organic fluorine wastewater, including the following steps: Step 1: Organic fluoride wastewater is pumped to the equalization tank through pipelines. The mechanical stirrer is started at a speed of 20 rpm to mix the wastewater evenly. Then, 1 mol / L sulfuric acid or 1 mol / L sodium hydroxide is added to adjust the pH to 7. After homogenization, the wastewater is pumped to the primary defluorination reaction tank. Step 2: Add calcium hydroxide to the primary defluorination reaction tank at a dosage of 1.5 g / L, followed by the addition of composite flocculant at a dosage of 0.3 g / L. After stirring and mixing at 60 rpm for 30 minutes, the mixture is pumped to the high-efficiency sedimentation tank. Step 3: Inclined plate sedimentation technology is used to allow wastewater to flow in the sedimentation zone. The surface loading rate in the inclined plate sedimentation technology is 1.5 m². 3 / m 2 ·h, sedimentation occurs, and the supernatant is collected from the top overflow weir and pumped to the US-O3 catalytic reaction tower. The settled sludge is collected and transported to sludge storage tank one by sludge pump. The sludge contains calcium fluoride, which is dewatered and then utilized as a resource. Step 4: Ozone is generated by an ozone generator and injected into the US-O3 catalytic reaction tower using a diffuser at a concentration of 35 mg / L. Hydrogen peroxide is also added at a concentration of 12 mL / L. The treatment temperature is 35℃, and the reaction is carried out with ultrasonic treatment at 45 kHz for 2 hours. The oxidized wastewater is then pumped into the secondary defluorination reaction tank. Step 5: Continue to add composite flocculant and calcium hydroxide to the secondary defluorination reaction tank. The dosage of composite flocculant is 0.1 g / L and the dosage of calcium hydroxide is 1 g / L. After mechanical stirring at 40 rpm for 25 min, the pH is 9. The wastewater enters the second high-efficiency sedimentation tank. The sludge is transported to the first sludge storage tank. The supernatant is pumped into the deep defluorination reaction tank. Activated alumina is added at a dosage of 1.2 g / L. After stirring and reacting for 30 min, the wastewater enters the third high-efficiency sedimentation tank. Step Six: The sludge produced in the high-efficiency sedimentation tank three is stored in the sludge storage tank two. The sludge is pumped from the sludge storage tank into the sludge dewatering machine. The pressure of the sludge dewatering machine is 0.6MPa and the centrifugal speed is 2500rpm. After treatment, it is outsourced for further processing. Step 7: Wastewater from high-efficiency sedimentation tank 3 is pumped into the biological reaction tank for anaerobic / aerobic treatment. During anaerobic treatment, the hydraulic retention time is 10 hours, the rotation speed is 11 rpm, and no aeration is performed. During aerobic treatment, dissolved oxygen is controlled at 3 mg / L using a microporous aerator, and the hydraulic retention time is 24 hours, resulting in a mixed liquor. Solid-liquid separation is then performed. The solids are sent to sludge storage tank 2, and the supernatant is pumped into the effluent storage tank for pH adjustment and testing. If the pH meets the standards, it is pumped for discharge into the sewer system or reused in production; if the pH does not meet the standards, it is returned to the equalization tank for retreatment.

[0028] Example 3: This example discloses a method for preparing a composite flocculant, including the following steps: Q1: 1.48 g of chitosan was added to 55 mL of acetic acid aqueous solution with a volume fraction of 1 vt. After magnetic stirring, 50 mL of ethanol was added and stirred to obtain a mixed solution. 2.71 g of 2,6-dimethyl-5-heptenal was added to 80 mL of ethanol. After stirring and mixing, the mixture was added dropwise to the mixed solution. After heating and refluxing at 60 °C for 12 h, 1.35 g of sodium borohydride was added. After stirring at room temperature for 5 h, the mixture was added to ethanol and freeze-dried to obtain solid product 1. Q2: Add 1.64g of solid product 1 to 70mL of N-methylpyrrolidone and react in an ice bath for 1h. Then add 4.1g of sodium iodide, 10mL of 15wt% sodium hydroxide aqueous solution and 12.5mL of iodomethane in sequence. After heating and refluxing at 60℃ for 4h, filter, wash and freeze dry to obtain solid product 2. Q3: Add 2.21g of solid product 2 to 50mL of N-methylpyrrolidone, stir and mix for 15min, then add 3.12g of acrylamide, 0.078g of ammonium persulfate and 2.05g of N,N'-methylenebisacrylamide, react at a constant temperature, cool, add ethanol for filtration, vacuum dry and purify to obtain the composite flocculant.

[0029] This embodiment discloses a process for treating organic fluorine wastewater, including the following steps: Step 1: Organic fluorine wastewater is pumped to the equalization tank through pipelines. The mechanical stirrer is started at a speed of 10 rpm to mix the wastewater evenly. Then, 1 mol / L sulfuric acid or 1 mol / L sodium hydroxide is added to adjust the pH to 6.6. After homogenization, the wastewater is pumped to the primary defluorination reaction tank. Step 2: Add calcium hydroxide to the primary defluorination reaction tank at a dosage of 0.5 g / L, followed by the addition of composite flocculant at a dosage of 0.1 g / L. After stirring and mixing at 30 rpm for 20 minutes, the mixture is pumped into the high-efficiency sedimentation tank. Step 3: Inclined plate sedimentation technology is used to allow wastewater to flow in the sedimentation zone. The surface loading rate in the inclined plate sedimentation technology is 1 m³. 3 / m 2 ·h, sedimentation occurs, and the supernatant is collected from the top overflow weir and pumped to the US-O3 catalytic reaction tower. The settled sludge is collected and transported to sludge storage tank one by sludge pump. The sludge contains calcium fluoride, which is dewatered and then utilized as a resource. Step 4: Ozone is generated by an ozone generator and injected into the US-O3 catalytic reaction tower using a diffuser at a rate of 20 mg / L. Hydrogen peroxide is added at a rate of 10 mL / L. The treatment temperature is 30℃. After ultrasonic reaction at 35 kHz for 1 hour, the oxidized wastewater is pumped into the secondary defluorination reaction tank. Step 5: Continue to add composite flocculant and calcium hydroxide to the secondary defluorination reaction tank. The dosage of composite flocculant is 0.15 g / L and the dosage of calcium hydroxide is 0.8 g / L. After mechanical stirring at 20 rpm for 15 min, the pH is 9.3. The wastewater enters the second high-efficiency sedimentation tank, the sludge is transported to the first sludge storage tank, and the supernatant is pumped into the deep defluorination reaction tank. Activated alumina is added at a dosage of 0.9 g / L. After stirring and reacting for 20 min, the wastewater enters the third high-efficiency sedimentation tank. Step Six: The sludge produced in the high-efficiency sedimentation tank three is stored in the sludge storage tank two. The sludge is pumped from the sludge storage tank into the sludge dewatering machine. The pressure of the sludge dewatering machine is 0.4MPa and the centrifugal speed is 2000rpm. After treatment, it is outsourced for further processing. Step 7: Wastewater from high-efficiency sedimentation tank 3 is pumped into the biological reaction tank for anaerobic / aerobic treatment. During anaerobic treatment, the hydraulic retention time is 8 hours, the rotation speed is 10 rpm, and no aeration is performed. During aerobic treatment, dissolved oxygen is controlled at 2 mg / L using a microporous aerator, and the hydraulic retention time is 12 hours, resulting in a mixed liquor. Solid-liquid separation is then performed. The solids are sent to sludge storage tank 2, and the supernatant is pumped into the effluent storage tank for pH adjustment and testing. If the pH meets the standards, it is pumped for discharge into the sewer system or reused in production; if the pH does not meet the standards, it is returned to the equalization tank for retreatment.

[0030] Example 4: This example discloses a method for preparing a composite flocculant, including the following steps: Q1: 1.83 g of chitosan was added to 45 mL of acetic acid aqueous solution with a volume fraction of 1 vt. After magnetic stirring, 50 mL of ethanol was added and stirred to obtain a mixed solution. 2.94 g of 2,6-dimethyl-5-heptenal was added to 80 mL of ethanol. After stirring and mixing, the mixture was added dropwise to the mixed solution. After heating and refluxing at 60 °C for 12 h, 1.68 g of sodium borohydride was added. After stirring at room temperature for 5 h, the mixture was added to ethanol and freeze-dried to obtain solid product 1. Q2: Add 2.04g of solid product 1 to 80mL of N-methylpyrrolidone and react in an ice bath for 1h. Then add 4.8g of sodium iodide, 20mL of 15wt% sodium hydroxide aqueous solution and 16.3mL of iodomethane in sequence. After heating and refluxing at 60℃ for 4h, filter, wash and freeze dry to obtain solid product 2. Q3: Add 2.84g of solid product 2 to 64mL of N-methylpyrrolidone, stir and mix for 15min, then add 3.65g of acrylamide, 0.082g of ammonium persulfate and 2.53g of N,N'-methylenebisacrylamide, react at a constant temperature, cool, add ethanol for filtration, vacuum dry and purify to obtain the composite flocculant.

[0031] This embodiment discloses a process for treating organic fluorine wastewater, including the following steps: Step 1: Organic fluoride wastewater is pumped to the equalization tank through pipelines. The mechanical stirrer is started at a speed of 30 rpm to mix the wastewater evenly. Then, 1 mol / L sulfuric acid or 1 mol / L sodium hydroxide is added to adjust the pH to 7.4. After homogenization, the wastewater is pumped to the primary defluorination reaction tank. Step 2: Add calcium hydroxide to the primary defluorination reaction tank at a dosage of 0.7 g / L, followed by the addition of composite flocculant at a dosage of 0.2 g / L. After stirring and mixing at 45 rpm for 25 minutes, the mixture is pumped into the high-efficiency sedimentation tank. Step 3: Inclined plate sedimentation technology is used to allow wastewater to flow in the sedimentation zone. The surface loading rate in the inclined plate sedimentation technology is 1.3 m. 3 / m 2 ·h, sedimentation occurs, and the supernatant is collected from the top overflow weir and pumped to the US-O3 catalytic reaction tower. The settled sludge is collected and transported to sludge storage tank one by sludge pump. The sludge contains calcium fluoride, which is dewatered and then utilized as a resource. Step 4: Ozone is generated by an ozone generator and injected into the US-O3 catalytic reaction tower using a diffuser at a concentration of 24 mg / L. Hydrogen peroxide is added at a concentration of 11 mL / L. The treatment temperature is 32 ℃. After ultrasonic reaction at 38 kHz for 1 h, the oxidized wastewater is pumped into the secondary defluorination reaction tank. Step 5: Continue to add composite flocculant and calcium hydroxide to the secondary defluorination reaction tank. The dosage of composite flocculant is 0.14 g / L and the dosage of calcium hydroxide is 0.9 g / L. After mechanical stirring at 35 rpm for 20 min, the pH is 9.6. The wastewater enters the second high-efficiency sedimentation tank, the sludge is transported to the first sludge storage tank, and the supernatant is pumped into the deep defluorination reaction tank. Activated alumina is added at a dosage of 1.4 g / L. After stirring and reacting for 24 min, the wastewater enters the third high-efficiency sedimentation tank. Step Six: The sludge produced in the high-efficiency sedimentation tank three is stored in the sludge storage tank two. The sludge is pumped from the sludge storage tank into the sludge dewatering machine. The pressure of the sludge dewatering machine is 0.7 MPa and the centrifugal speed is 2600 rpm. After processing, it is outsourced for further processing. Step 7: Wastewater from high-efficiency sedimentation tank 3 is pumped into the biological reaction tank for anaerobic / aerobic treatment. During anaerobic treatment, the hydraulic retention time is 12 hours, the rotation speed is 16 rpm, and no aeration is performed. During aerobic treatment, dissolved oxygen is controlled at 4 mg / L using a microporous aerator, and the hydraulic retention time is 20 hours, resulting in a mixed liquor. Solid-liquid separation is then performed. The solids are sent to sludge storage tank 2, and the supernatant is pumped into the effluent storage tank for pH adjustment and testing. If the pH meets the standards, it is pumped for discharge into the sewer system or reused in production; if the pH does not meet the standards, it is returned to the equalization tank for retreatment.

[0032] Example 5: This example discloses a method for preparing a composite flocculant, including the following steps: Q1: 1.52 g of chitosan was added to 48 mL of acetic acid aqueous solution with a volume fraction of 1 vt. After magnetic stirring, 50 mL of ethanol was added and stirred to obtain a mixed solution. 2.76 g of 2,6-dimethyl-5-heptenal was added to 80 mL of ethanol. After stirring and mixing, the mixture was added dropwise to the mixed solution. After heating and refluxing at 60 °C for 12 h, 1.39 g of sodium borohydride was added. After stirring at room temperature for 5 h, the mixture was added to ethanol and freeze-dried to obtain solid product 1. Q2: Add 1.72g of solid product 1 to 72mL of N-methylpyrrolidone and react in an ice bath for 1h. Then add 4.2g of sodium iodide, 12mL of 15wt% sodium hydroxide aqueous solution and 13.7mL of iodomethane in sequence. After heating and refluxing at 60℃ for 4h, filter, wash and freeze dry to obtain solid product 2. Q3: Add 2.38g of solid product 2 to 52mL of N-methylpyrrolidone, stir and mix for 15min, then add 3.28g of acrylamide, 0.077g of ammonium persulfate and 2.18g of N,N'-methylenebisacrylamide, react at a constant temperature, cool, add ethanol for filtration, vacuum dry and purify to obtain the composite flocculant.

[0033] This embodiment discloses a process for treating organic fluorine wastewater, including the following steps: Step 1: Organic fluorine wastewater is pumped to the equalization tank through pipelines. The mechanical agitator is started at a speed of 24 rpm to mix the wastewater evenly. Then, 1 mol / L sulfuric acid or 1 mol / L sodium hydroxide is added to adjust the pH to 7.5. After homogenization, the wastewater is pumped to the primary defluorination reaction tank. Step 2: Add calcium hydroxide to the primary defluorination reaction tank at a dosage of 1.8 g / L, followed by the addition of composite flocculant at a dosage of 0.5 g / L. After stirring and mixing at 45 rpm for 25 minutes, the mixture is pumped into the high-efficiency sedimentation tank. Step 3: Inclined plate sedimentation technology is used to allow wastewater to flow in the sedimentation zone. The surface loading of the inclined plate sedimentation technology is 1.8 m. 3 / m 2 ·h, sedimentation occurs, and the supernatant is collected from the top overflow weir and pumped to the US-O3 catalytic reaction tower. The settled sludge is collected and transported to sludge storage tank one by sludge pump. The sludge contains calcium fluoride, which is dewatered and then utilized as a resource. Step 4: Ozone is generated by an ozone generator and injected into the US-O3 catalytic reaction tower using a diffuser at a concentration of 40 mg / L. Hydrogen peroxide is added and the treatment continues at a concentration of 14 mL / L. The treatment temperature is 32°C, and the reaction is carried out using 40 kHz ultrasonication for 1.5 hours. The oxidized wastewater is then pumped into the secondary defluorination reaction tank. Step 5: Continue to add composite flocculant and calcium hydroxide to the secondary defluorination reaction tank. The dosage of composite flocculant is 0.17 g / L and the dosage of calcium hydroxide is 1.1 g / L. After mechanical stirring at 35 rpm for 23 min, the pH is 9. The wastewater enters the second high-efficiency sedimentation tank. The sludge is transported to the first sludge storage tank. The supernatant is pumped into the deep defluorination reaction tank. Activated alumina is added at a dosage of 1.6 g / L. After stirring and reacting for 24 min, the wastewater enters the third high-efficiency sedimentation tank. Step Six: The sludge produced in the high-efficiency sedimentation tank three is stored in the sludge storage tank two. The sludge is pumped from the sludge storage tank into the sludge dewatering machine. The pressure of the sludge dewatering machine is 0.7MPa and the centrifugal speed is 2800rpm. After processing, it is outsourced for further processing. Step 7: Wastewater from high-efficiency sedimentation tank 3 is pumped into the biological reaction tank for anaerobic / aerobic treatment. During anaerobic treatment, the hydraulic retention time is 12 hours, the rotation speed is 18 rpm, and no aeration is performed. During aerobic treatment, dissolved oxygen is controlled at 4 mg / L using a microporous aerator, and the hydraulic retention time is 18 hours, resulting in a mixed liquor. Solid-liquid separation is then performed. The solids are sent to sludge storage tank 2, and the supernatant is pumped into the effluent storage tank for pH adjustment and testing. If the pH meets the standards, it is pumped for discharge into the sewer system or reused in production; if the pH does not meet the standards, it is returned to the equalization tank for retreatment.

[0034] Comparative Example 1: Compared with Example 2, Comparative Example 1 did not set up a biochemical reaction tank in the process of treating organic fluorine wastewater, while all other conditions remained unchanged.

[0035] Performance testing: Organic fluoride wastewater was treated according to the methods in Examples 2-5 and Comparative Example 1. The concentrations of COD, organic fluoride, and inorganic fluoride ions in the water were measured. The influent flow rate was 2 m³ / s. 3 / h, pH=5, CODcr=2875mg / L, organic fluorine=230mg / L, inorganic fluorine=1300mg / L, the test results are shown in Table 1:

[0036] As shown in Table 1, the test results indicate that methods 2-5 can effectively remove fluoride ions and COD from organic fluoride wastewater. A comparison between Comparative Example 1 and Examples 2-5 reveals that the addition of the biochemical reaction tank can effectively reduce COD and fluoride ions in organic fluoride wastewater.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0038] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A process for treating organic fluorine wastewater, characterized in that, Includes the following steps: Step 1: Organic fluoride wastewater is pumped through pipelines to the equalization tank. The mechanical agitator is started to mix the wastewater evenly. Then the pH is adjusted and homogenized before being pumped to the primary defluorination reaction tank. Step 2: Add calcium hydroxide to the primary defluorination reaction tank, followed by the addition of composite flocculant. After stirring and mixing, the mixture is pumped to the high-efficiency sedimentation tank. Step 3: Using inclined plate sedimentation technology, the wastewater flows in the sedimentation zone, and sedimentation occurs. The supernatant overflows from the top to the intermediate storage tank and is pumped to the ultrasonic enhanced ozone catalytic reaction tower. The settled sludge is collected and transported to sludge storage tank one by sludge pump. The sludge contains calcium fluoride and can be used for resource utilization after dewatering. Step 4: Ozone is generated by an ozone generator and injected into the ultrasonic enhanced ozone catalytic reaction tower using an aeration distributor. Hydrogen peroxide (H2O2) is added as an initiator. After treatment by ultrasonic enhanced catalytic ozone oxidation, the oxidized wastewater is pumped into the secondary defluorination reaction tank. Step 5: Continue to add composite flocculant and calcium hydroxide to the secondary defluorination reaction tank. After mechanical stirring, the wastewater enters the second high-efficiency sedimentation tank, the sludge is transported to the first sludge storage tank, and the supernatant is pumped into the deep defluorination reaction tank. Activated alumina is added, and after stirring and reaction, the wastewater enters the third high-efficiency sedimentation tank. Step Six: The sludge produced in the high-efficiency sedimentation tank three is stored in the sludge storage tank two. The sludge is then pumped from the sludge storage tank to the sludge dewatering machine for processing, and then outsourced for further treatment. Step 7: Wastewater from high-efficiency sedimentation tank 3 is pumped into the biological reaction tank for anaerobic / aerobic treatment to obtain a mixed liquor. Then, solid-liquid separation is performed. The solids are sent to sludge storage tank 2, and the supernatant is pumped into the effluent storage tank for pH adjustment and testing. If the pH meets the standards, it is pumped for discharge into the municipal sewer or reused in production. If the pH does not meet the standards, it is returned to the equalization tank for retreatment. The preparation method of the composite flocculant includes the following steps: Q1: Chitosan was added to an aqueous acetic acid solution and stirred magnetically. Ethanol was then added and stirred to obtain a mixed solution. 2,6-Dimethyl-5-heptenal was added to ethanol and stirred to obtain a mixed solution. After stirring and mixing, the mixture was added dropwise to the mixed solution. After heating and reflux, sodium borohydride was added. After stirring at room temperature, the mixture was added to ethanol and freeze-dried to obtain solid product 1. Q2: Add solid product 1 to N-methylpyrrolidone, react in an ice bath, add sodium iodide, sodium hydroxide aqueous solution and iodomethane in sequence, heat under reflux, filter, wash, freeze dry to obtain solid product 2. Q3: Add solid product 2 to N-methylpyrrolidone, stir and mix, then add acrylamide, ammonium persulfate and N,N'-methylenebisacrylamide, react at a constant temperature, cool, filter, vacuum dry and purify to obtain composite flocculant.

2. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In step one, the organic fluorine wastewater mainly comes from the fluorochemical and electronics industries, and includes wastewater containing persistent organic fluorine pollutants such as perfluorooctanoic acid and perfluorooctane sulfonic acid. The stirring speed is 10-30 rpm, and 1 mol / L sulfuric acid or 1 mol / L sodium hydroxide is added to adjust the pH to 6-8.

3. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In step two, the dosage of calcium hydroxide is 0.5-2 g / L, and the dosage of composite flocculant is 0.1-0.5 g / L.

4. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In Q1, the ratio of chitosan, aqueous acetic acid solution, 2,6-dimethyl-5-heptenal and sodium borohydride is (1.48-1.83) g : (45-55) mL : (2.71-2.94) g : (1.35-1.68) g.

5. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In Q2, the ratio of solid product 1, N-methylpyrrolidone, sodium iodide, sodium hydroxide, and iodomethane is (1.64-2.04) g : (70-80) mL : (4.1-4.8) g : (10-20) mL : (12.5-16.3) mL; in Q3, the ratio of solid product 2, N-methylpyrrolidone, acrylamide, and N,N'-methylenebisacrylamide is (2.21-2.84) g : (50-64) mL : (3.12-3.65) g : (2.05-2.53) g.

6. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In step three, the surface load in the inclined plate deposition technique is 1-2 m. 3 / m 2 •h; In step four, the ozone injection amount is 20-50 mg / L, the ultrasonic reaction frequency is 35-45 kHz, and the hydrogen peroxide dosage is 10-15 mL / L.

7. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In step five, the dosage of the composite flocculant is 0.1-0.2 g / L, the dosage of calcium hydroxide is 0.8-1.2 g / L, and the dosage of activated alumina is 0.9-1.7 g / L.

8. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In step six, the pressure of the sludge dewatering machine is 0.4-0.8 MPa.

9. The organic fluoride wastewater treatment process according to claim 1, characterized in that, In step seven, during the anaerobic treatment, the hydraulic retention time is 8-12 hours, the rotation speed is 10-20 rpm, and no aeration is performed. During the aerobic treatment, the dissolved oxygen is controlled at 2-4 mg / L through a microporous aerator, and the hydraulic retention time is 12-24 hours.

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