Pressure type ceramic membrane water purification system integrating electrolysis and catalytic ozonation

Abstract

The invention discloses a pressure type ceramic membrane water purification system integrating electrolysis and catalytic ozonation, and belongs to the technical field of water treatment. The invention provides the pressure type ceramic membrane water purification system integrating electrolysis and catalytic ozonation, the ceramic membrane water purification system is high in water purification efficiency, the service life of the ceramic membrane is long, and small molecular pollutants can be effectively removed. A pressure type ceramic membrane water purification system integrating electrolysis and catalytic ozonation comprises a water inlet valve, an ozone preparation unit, an ozone mixing unit, a pressure type ceramic membrane unit, a water production valve, a backwashing pump, a dosing pump, a cleaning valve, a blow-down valve and a clear water tank. The ozone is prepared by adopting a low-voltage direct-current electrolysis technology, high-mass-concentration ozone is generated at an anode, byproducts are oxygen and hydrogen, and the ozone is clean and pollution-free; a catalytic pressure type ceramic membrane water purification process is adopted, so that the occupied area is small, and the membrane flux is greatly improved; in addition, the system cooperates with a catalytic ozonation technology, so that removal of organic matters in water pollution, especially in water, can be efficiently realized.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a pressure-type ceramic membrane water purification system integrating electrolytic ozone catalytic oxidation. Background Art

[0002] As drinking water quality standards are gradually improved, conventional water treatment processes have an urgent need for further upgrading and transformation. In recent years, the application of ultrafiltration technology in drinking water treatment has gradually increased. This advanced water treatment technology has the potential to replace traditional treatment units such as coagulation, sedimentation and sand filtration, and promote the improvement of water quality while also providing new possibilities for the shortening of water plant processes. Ultrafiltration (UF), as a membrane separation technology, is considered to be a very promising drinking water production process because of its compact space, easy automation, and high removal rate of turbidity, organic matter, Giardia and viruses. Microfiltration and ultrafiltration membranes have large pore sizes, high water flux and low transmembrane pressure. Microfiltration membranes are used to remove suspended particles and various microorganisms, while ultrafiltration pore sizes are usually between 10-100nm, which can remove colloids, viruses and high molecular weight parts of natural organic matter. Compared with nanofiltration and reverse osmosis, ultrafiltration has lower operating costs.

[0003] At present, organic membranes have been widely used in water and wastewater treatment. However, due to the hydrophobicity, poor stability to chemicals and high fouling tendency of organic membranes, not only their performance but also their long-term sustainability will be affected. In this context, the application of ceramic membranes in water and wastewater treatment has attracted widespread attention.

[0004] Ceramic membranes are attractive for water and wastewater applications due to their thermal / chemical stability, low fouling tendency and long life. Ceramic membranes can be combined with oxidation treatments, which cannot be applied to organic membranes due to the problem of membrane degradation during long-term exposure, such as in-situ ozonation. In addition, ceramic membranes outperform conventional organic membranes with higher flux, higher pollutant removal, lower fouling and higher cleaning efficiency.

[0005] According to the water quality of the source water and the required drinking water quality, multiple treatment processes such as pre-oxidation, coagulation, sedimentation, filtration and disinfection are usually required. Ceramic membranes, as a new option, are expected to replace traditional pretreatment processes to shorten the process flow. However, the membrane surface of ceramic membranes is easily contaminated by organic matter, microorganisms, colloids and other substances after long-term operation, resulting in decreased membrane flux, increased membrane resistance, reduced membrane performance and service life, and ineffective removal of small molecule pollutants, and high production costs. In order to extend the operation time of ceramic membranes, it can be combined with pretreatment processes such as oxidation and activated carbon adsorption to reduce membrane pollution and improve the removal rate of pollutants in water. However, despite the large specific surface area and high porosity of activated carbon, a single adsorbent is often difficult to cope with the removal requirements of different organic matter.

[0006] Membrane water treatment technology performs outstandingly in the water treatment process. Through the interception and adsorption effect of the membrane, it can greatly reduce suspended pollutants in the water body and significantly reduce the turbidity of the water body. However, the treatment process is often accompanied by serious membrane pollution problems, which affects the life of the membrane. At the same time, small molecular pollutants in the water cannot be effectively removed, and the production cost is high. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a pressure-type ceramic membrane water purification system integrating electrolytic ozone catalytic oxidation, which has high water purification efficiency, long service life of the ceramic membrane, and can effectively remove small molecule pollutants.

[0008] A pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation, comprising a water inlet valve 1, an ozone preparation unit 2, an ozone mixing unit 3, a pressure-type ceramic membrane unit 4, a water production valve 5, a backwash pump 6, a dosing pump 7, a cleaning valve 8, a sewage valve 9 and a clean water tank 10;

[0009] The water inlet valve 1 and the ozone preparation unit 2 are respectively connected to the two inlets of the ozone mixing unit 3; the outlet of the ozone mixing unit 3 is connected to the water inlet at the top of the pressure-type ceramic membrane unit 4; the sewage outlet at the bottom of the pressure-type ceramic membrane unit 4 is connected to the sewage valve 9; the water outlet of the pressure-type ceramic membrane unit 4 is connected to one end of the water production valve 5, and the other end of the water production valve 5 is connected to the water inlet of the clean water tank 10;

[0010] The water outlet of the clean water tank 10 is respectively connected to the water production tank and the sewage outlet of the pressure ceramic membrane unit 4; the pipeline connecting the clean water tank 10 and the sewage outlet of the pressure ceramic membrane unit 4 is provided with a backwash pump 6 and a cleaning valve 8;

[0011] The pipeline connecting the clean water tank 10 and the sewage outlet of the pressure ceramic membrane unit 4 is also connected to the drug washing unit through the drug adding pump 7.

[0012] Compared with the prior art, the present invention has the following effects:

[0013] 1. The present invention adopts low-voltage direct current electrolysis technology to prepare ozone, produces high-quality concentration ozone at the anode, and its byproducts are oxygen and hydrogen, which are clean and pollution-free;

[0014] Second, the present invention adopts a catalytic pressure ceramic membrane water purification process, which occupies a small area and greatly improves the membrane flux; in addition, the system cooperates with ozone catalytic oxidation technology to efficiently remove water pollution, especially organic matter in water;

[0015] 3. The present invention uses mechanical dredging brush physical cleaning, ozone water backwashing, online chemical cleaning and other methods to clean the pressure-type ceramic membrane, which can effectively avoid the ceramic membrane from being blocked and extend the service life of the ceramic membrane;

[0016] Fourth, the core of the ozone catalyst prepared by the present invention is ternary doped with boron, copper and potassium. Boron, copper and potassium have a synergistic effect. The ternary doping of boron, copper and potassium can change the surface chemical shape of the catalyst, generate new active sites, and generate nitrogen defects, thereby enhancing the adsorption and activation of ozone;

[0017] 5. The ozone catalyst prepared by the present invention has a core-shell structure, high catalytic activity, long life, and excellent catalytic ozone decomposition performance;

[0018] 6. The catalytic ozone functional ceramic membrane prepared by the present invention has excellent water permeability and can degrade various organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of a pressure-type ceramic membrane water purification system integrating electrolytic ozone catalytic oxidation of the present invention, in which 1 is a water inlet valve, 2 is an ozone preparation unit, 3 is an ozone mixing unit, 4 is a pressure-type ceramic membrane unit, 5 is a water production valve, 6 is a backwash pump, 7 is a dosing pump, 8 is a cleaning valve, 9 is a sewage valve, and 10 is a clean water tank. DETAILED DESCRIPTION

[0020] Specific implementation method 1: Please refer to Figure 1 , the present embodiment is a pressure-type ceramic membrane water purification system integrating electrolytic ozone catalytic oxidation, comprising a water inlet valve 1, an ozone preparation unit 2, an ozone mixing unit 3, a pressure-type ceramic membrane unit 4, a water production valve 5, a backwash pump 6, a dosing pump 7, a cleaning valve 8, a drain valve 9 and a clean water tank 10;

[0021] The water inlet valve 1 and the ozone preparation unit 2 are respectively connected to the two inlets of the ozone mixing unit 3; the outlet of the ozone mixing unit 3 is connected to the water inlet at the top of the pressure-type ceramic membrane unit 4; the sewage outlet at the bottom of the pressure-type ceramic membrane unit 4 is connected to the sewage valve 9; the water outlet of the pressure-type ceramic membrane unit 4 is connected to one end of the water production valve 5, and the other end of the water production valve 5 is connected to the water inlet of the clean water tank 10;

[0022] The water outlet of the clean water tank 10 is respectively connected to the water production tank and the sewage outlet of the pressure ceramic membrane unit 4; the pipeline connecting the clean water tank 10 and the sewage outlet of the pressure ceramic membrane unit 4 is provided with a backwash pump 6 and a cleaning valve 8;

[0023] The pipeline connecting the clean water tank 10 and the sewage outlet of the pressure ceramic membrane unit 4 is also connected to the drug washing unit through the drug adding pump 7.

[0024] As a specific implementation of a pressure-type ceramic membrane water purification system with integrated electrolytic ozone catalytic oxidation, please refer to Figure 1 : When producing water, open the water inlet valve 1, and the raw water filled with ozone enters the pressure ceramic membrane unit 4, and the ozone reacts with the organic matter adhering to the membrane surface, improves the dirt on the membrane surface, reduces membrane pollution, and extends the membrane service life; after the water production is completed, open the cleaning valve 8, turn on the backwash pump 6, and fill the water after membrane filtration with ozone, and use the ozone water to perform online backwashing on the pressure ceramic membrane to remove the pollutants adhering to the inside of the ceramic membrane, thereby realizing online ozone membrane external and internal cleaning of the pressure ceramic membrane unit 4.

[0025] In this specific embodiment, the backwash time can be set according to the membrane fouling and raw water quality. For example, if the raw water quality is poor and the membrane fouling is not serious, the backwash cycle can be set to 1-3 days, and the backwash time can be set to 5s-60s. If the raw water quality is poor and the membrane fouling is serious, the backwash cycle can be set to 2-4h, and the backwash setting time can be 1-5min.

[0026] As a specific embodiment of the pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation provided by the present invention, please refer to Figure 1 During the chemical washing process, after the cleaning valve 8 is opened, when the backwash pump 6 is turned on, the dosing pump 7 is turned on synchronously to realize the chemical washing process of the pressure ceramic membrane unit 4.

[0027] In this specific embodiment, according to the type of pollutants in the water body, sodium hypochlorite, sodium hydroxide, citric acid, hydrogen peroxide, hydrochloric acid and other agents can be selected to clean the ceramic membrane. The specific drug washing mode is determined according to the actual fouling and clogging of the ceramic membrane.

[0028] In this specific embodiment, the inside of the pressure-type ceramic membrane unit 4 can also be physically cleaned by a mechanical cleaning brush to avoid fouling and clogging of the ceramic membrane and extend the service life of the ceramic membrane.

[0029] In this specific implementation, the membrane off-gas washing time can be set according to the actual raw water quality and membrane pollution performance.

[0030] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the ozone preparation unit 2 adopts low-pressure water electrolysis technology to prepare high-concentration ozone, and the concentration of ozone is greater than 20%. Other steps are the same as those of specific embodiment 1.

[0031] Specific embodiment 3: The difference between this embodiment and specific embodiment 1 or 2 is that the water electrolyzed by the ozone preparation unit 2 contains dilute sulfuric acid or hydrochloric acid to increase conductivity; aluminum is used as the cathode and Pt, SbO 2 , glassy carbon or diamond as anode; perfluorosulfonic acid ion exchange membrane. Other steps are the same as those in the first or second embodiment.

[0032] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the ozone produced by electrolysis in the ozone preparation unit 2 is added using micro-nano bubble technology and enters the ozone mixing unit 3 so that the water to be treated and the ozone are fully mixed and reacted. The other steps are the same as those in specific embodiments 1 to 3.

[0033] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the pressure ceramic membrane unit 4 uses a catalytic ceramic membrane. The other steps are the same as those of specific embodiments 1 to 4.

[0034] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the catalytic ceramic membrane is a catalytic ozone functional ceramic membrane, and the preparation method is specifically completed according to the following steps:

[0035] 1. Preparation of ozone catalyst:

[0036] ① Disperse the nitrogen source, boron source, copper source and potassium source in a solvent, then heat and stir for a period of time; evaporate the solvent, grind and obtain a precursor powder;

[0037] ②, placing the precursor powder in a muffle furnace, heating it to a calcination temperature, and calcining it at the calcination temperature for a period of time to obtain boron-copper-potassium ternary doped carbon nitride;

[0038] ③, spraying aluminum sol onto the outer surface of boron-copper-potassium ternary doped carbon nitride, and then drying and calcining to obtain a core-shell catalyst;

[0039] ④, dissolving lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride into water to obtain a metal salt solution;

[0040] ⑤. Immerse the core-shell catalyst in a metal salt solution, then add a complexing agent solution, stir for a period of time, take it out and dry it, then calcine it at 150℃~250℃ for 1h~2h, and finally calcine it at 900℃~950℃ for 2h~3h to obtain an ozone catalyst;

[0041] 2. Preparation of catalytic ozone functional ceramic membrane:

[0042] ①. Add ceramic membrane aggregate, sintering aid, pore former and binder into a ball mill and mix them evenly, then add ozone catalyst and continue to mix them evenly to obtain a mixed powder; add water to the mixed powder and blend it to obtain a ceramic membrane blend;

[0043] ②, the ceramic membrane blend is left to stand for aging, and then subjected to a vacuum mud kneading machine for mud kneading to obtain a mixed mud material; the mixed mud material is extruded and formed into a ceramic membrane embryo, the embryo is dried in an oven, and then calcined using a gradient temperature increase program to obtain a catalytic ozone functional ceramic membrane. The other steps are the same as those in the first to fifth embodiments.

[0044] Specific embodiment 7: The difference between this embodiment and specific embodiments 1 to 6 is that: the nitrogen source described in step 1① is urea or melamine; the boron source described in step 1① is sodium metaborate, sodium tetraborate or boric acid; the copper source described in step 1① is copper nitrate, copper sulfate or copper acetate; the potassium source described in step 1① is potassium chloride, potassium carbonate or potassium sulfate; the solvent described in step 1① is water or anhydrous ethanol; the temperature of heating and stirring described in step 1① is 60℃~90℃, and the time of heating and stirring is 5h~7h; the molar ratio of nitrogen source, boron source, copper source and potassium source described in step 1① is (300~500):(10~30):(1~10):(1~10). The other steps are the same as specific embodiments 1 to 6.

[0045] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that: the heating rate described in step one ② is 5℃ / min~10℃ / min; the calcination temperature is 500℃~600℃, and the calcination time is 3h~5h; the solid content of the aluminum sol described in step one ③ is 20%; the drying temperature described in step one ③ is 100℃~110℃, and the drying time is 2h~5h; the calcination temperature described in step one ③ is 600℃~700℃, and the calcination time is 5h~7h;

[0046] The mass fraction of the shell in the core-shell catalyst described in step 1③ is 5% to 10%. The other steps are the same as those in specific embodiments 1 to 7.

[0047] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that: the molar ratio of lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride described in step 1 ④ is (8-10): (2-4): (1-3): (1-3); the complexing agent solution described in step 1 ⑤ is a citric acid solution with a concentration of 2mol / L to 4mol / L; the volume ratio of the metal salt solution to the complexing agent solution described in step 1 ⑤ is 1:1; the stirring time described in step 1 ⑤ is 2h to 4h. The other steps are the same as those of specific embodiments 1 to 8.

[0048] Specific embodiment 10: The difference between this embodiment and specific embodiments 1 to 9 is that: the mixture of one or more of alumina, zirconium oxide, titanium dioxide and silicon carbide described in step 2①; the sintering aid described in step 2① is one or more of clay, kaolin, potassium feldspar, sodium feldspar, calcium carbonate and magnesium carbonate; the pore-forming agent described in step 2① is one or more of yellow dextrin, soluble starch, glucose and sodium chloride; the binder described in step 2① is polyvinyl alcohol, methyl cellulose or polyacrylamide; the mass ratio of ceramic membrane aggregate, sintering aid, pore-forming agent, binder and water described in step 2① is (8 0~90):(10~15):(10~15):10:(15~25); the mass ratio of the ozone catalyst to the ceramic membrane aggregate described in step 2① is (10~15):(80~90); the calcination described in step 2② is firstly heating to 600℃~800℃ at a heating rate of 5℃ / min~10℃ / min, sintering at 600℃~800℃ for 3h~6h, then heating to 1200℃~1500℃ at a heating rate of 5℃ / min~10℃ / min, sintering at 1200℃~1500℃ for 8h~12h, and obtaining a catalytic ozone functional ceramic membrane. The other steps are the same as those in specific embodiments one to nine.

[0049] The following examples are used to verify the beneficial effects of the present invention:

[0050] Example 1: Figure 1 As shown, this embodiment is a pressure-type ceramic membrane water purification system integrating electrolytic ozone catalytic oxidation, comprising a water inlet valve 1, an ozone preparation unit 2, an ozone mixing unit 3, a pressure-type ceramic membrane unit 4, a water production valve 5, a backwash pump 6, a dosing pump 7, a cleaning valve 8, a drain valve 9 and a clean water tank 10;

[0051] The water inlet valve 1 and the ozone preparation unit 2 are respectively connected to the two inlets of the ozone mixing unit 3; the outlet of the ozone mixing unit 3 is connected to the water inlet at the top of the pressure-type ceramic membrane unit 4; the sewage outlet at the bottom of the pressure-type ceramic membrane unit 4 is connected to the sewage valve 9; the water outlet of the pressure-type ceramic membrane unit 4 is connected to one end of the water production valve 5, and the other end of the water production valve 5 is connected to the water inlet of the clean water tank 10;

[0052] The water outlet of the clean water tank 10 is respectively connected to the water production tank and the sewage outlet of the pressure ceramic membrane unit 4; the pipeline connecting the clean water tank 10 and the sewage outlet of the pressure ceramic membrane unit 4 is provided with a backwash pump 6 and a cleaning valve 8;

[0053] The pipeline connecting the clean water tank 10 and the sewage outlet of the pressure ceramic membrane unit 4 is also connected to the drug washing unit through the dosing pump 7;

[0054] In the ozone preparation unit 2, ozone is prepared by low-pressure water electrolysis technology. The concentration of ozone is greater than 20%. The high-concentration ozone produced is charged into the inlet water by micro-nano bubble technology for mixing. The inlet water fully mixed with ozone is filtered by a pressure ceramic membrane unit to complete the water purification process.

[0055] In this embodiment, ozone preparation unit 2 is used to generate high concentration ozone, water inlet valve 1 is opened, ozone is charged into ozone mixing unit 3 by micro-nano bubble technology for full mixing, water flows through pressure ceramic membrane unit 4 for membrane filtration, ozone and ozone catalyst on the membrane produce ozone catalytic oxidation to remove organic matter and other pollutants in the water, after membrane filtration, the turbidity of the outlet water is greatly reduced, and the quality of the outlet water is improved. Open the water production valve 5 to complete the water production process. Open the sewage valve 9 to complete the ozone water flushing and sewage discharge process;

[0056] In this embodiment, the ozone concentration generated by the ozone preparation unit 2 is greater than 20%; the electrolyzed water contains dilute sulfuric acid to increase the conductivity; aluminum is used as the cathode and Pt is used as the anode;

[0057] In this embodiment, the ozone production unit 2 uses a perfluorosulfonic acid ion exchange membrane, which has stable electrochemical properties, excellent mechanical properties, high conductivity, good selective permeability, and no selective separation effect and pressure drop phenomenon;

[0058] In this embodiment, the ozone generated by electrolysis in the ozone preparation unit 2 is added using micro-nano bubble technology and enters the ozone mixing unit 3, so that the water and ozone are fully mixed and reacted;

[0059] In this embodiment, the pressure-type ceramic membrane water purification system uses a catalytic ceramic membrane, which can achieve efficient purification of high-organic water and improve the efficiency of organic removal;

[0060] The catalytic ceramic membrane described in this embodiment is a catalytic ozone functional ceramic membrane, and the preparation method is specifically completed according to the following steps:

[0061] 1. Preparation of ozone catalyst:

[0062] ①, Disperse urea, sodium metaborate, copper nitrate and potassium chloride in water, then heat and stir at 70°C for 6 hours; then evaporate the solvent and grind to obtain a precursor powder;

[0063] The molar ratio of urea, sodium metaborate, copper nitrate and potassium chloride described in step 1① is 300:15:5:3;

[0064] ②, placing the precursor powder in a muffle furnace, heating it to a calcination temperature, and calcining it at the calcination temperature for a period of time to obtain boron-copper-potassium ternary doped carbon nitride;

[0065] The heating rate in step 1② is 10°C / min; the calcination temperature is 550°C and the calcination time is 4h;

[0066] ③, spraying aluminum sol onto the outer surface of boron-copper-potassium ternary doped carbon nitride, and then drying and calcining to obtain a core-shell catalyst;

[0067] The solid content of the aluminum sol described in step 1③ is 20%;

[0068] The drying temperature in step 1 (3) is 100°C and the drying time is 3h;

[0069] The calcination temperature in step 1 (3) is 650°C and the calcination time is 6h;

[0070] The mass fraction of the shell in the core-shell catalyst described in step 1③ is 5%;

[0071] ④, dissolving lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride into water to obtain a metal salt solution;

[0072] The molar ratio of lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride described in step 1④ is 8:3:2:1;

[0073] ⑤. Immerse the core-shell catalyst in a metal salt solution, then add a complexing agent solution, stir for 2 hours, take it out and dry it, then calcine it at 250°C for 2 hours, and finally calcine it at 900°C for 2 hours to obtain an ozone catalyst;

[0074] The complexing agent solution described in step 1⑤ is a citric acid solution with a concentration of 3 mol / L;

[0075] The volume ratio of the metal salt solution to the complexing agent solution in step 1⑤ is 1:1;

[0076] 2. Preparation of catalytic ozone functional ceramic membrane:

[0077] ①. Add ceramic membrane aggregate, sintering aid, pore former and binder into a ball mill and mix them evenly, then add ozone catalyst and continue to mix them evenly to obtain a mixed powder; add water to the mixed powder and blend it to obtain a ceramic membrane blend;

[0078] The aluminum oxide described in step 2①;

[0079] The sintering aid described in step 2① is a mixture of clay and kaolin, wherein the mass ratio of clay to kaolin is 1:1;

[0080] The pore-forming agent described in step 2① is a mixture of yellow dextrin and sodium chloride, wherein the mass ratio of yellow dextrin to sodium chloride is 1:1;

[0081] The binder described in step 2① is polyvinyl alcohol;

[0082] The mass ratio of the ceramic membrane aggregate, sintering aid, pore former, binder and water described in step 2① is 85:15:15:10:20;

[0083] The mass ratio of the ozone catalyst to the ceramic membrane aggregate described in step 2① is 10:85;

[0084] ②, the ceramic membrane blend is left to stand for aging, and is subjected to a vacuum mud kneading machine for mud kneading to obtain a mixed mud material; the mixed mud material is extruded and formed into a ceramic membrane embryo, the embryo is dried in an oven, and then calcined using a gradient temperature increase program to obtain a catalytic ozone functional ceramic membrane;

[0085] The calcination described in step 2② is to first increase the temperature to 700°C at a heating rate of 5°C / min, sinter at 700°C for 5 hours, then increase the temperature to 1300°C at a heating rate of 5°C / min, and sinter at 1300°C for 10 hours to obtain a catalytic ozone functional ceramic membrane.

[0086] After testing, the pure water flux can reach 3215Lm -2 h -1 bar -1 The turbidity removal rate was 100%, the dissolved organic carbon (DOC) removal rate was 91.7% at an ozone concentration of 2 mg / L, the total organic carbon removal rate was 85.6%, the catalytic ozone decomposition rate was 99.8%, the flux recovery rate was 98.5%, and no heavy metal leaching was detected after immersion in pure water for 30 days (1m 2 Membrane / 10L water, flat-plate products are calculated based on single-side area, and tubular products are calculated based on outer wall area of ​​the tube).

[0087] Example 2: The difference between this example and Example 1 is that the molar ratio of urea, sodium metaborate, copper nitrate and potassium chloride described in step 1① is 400:20:3:5; the molar ratio of lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride described in step 1④ is 10:2:1:3. The other steps and parameters are the same as those in Example 1.

[0088] Comparative Example 1: The difference between this embodiment and embodiment 1 is that the preparation of boron-copper-potassium ternary doped carbon nitride is omitted, that is, the method for preparing the ozone catalyst in step 1 is as follows:

[0089] ① Drying and calcining the aluminum sol to obtain a catalyst;

[0090] The solid content of the aluminum sol described in step 1① is 20%;

[0091] The drying temperature in step 1① is 100°C and the drying time is 3h;

[0092] The calcination temperature in step 1① is 650°C and the calcination time is 6h;

[0093] ②, dissolving lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride into water to obtain a metal salt solution;

[0094] The molar ratio of lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride described in step 1② is 8:3:2:1;

[0095] ③. Immerse the catalyst in a metal salt solution, then add a complexing agent solution, stir for 2 hours, take it out and dry it, then calcine it at 250°C for 2 hours, and finally calcine it at 900°C for 2 hours to obtain an ozone catalyst;

[0096] The complexing agent solution described in step 1③ is a citric acid solution with a concentration of 3 mol / L;

[0097] The volume ratio of the metal salt solution to the complexing agent solution in step 1 (3) is 1:1. The other steps and parameters are the same as those in Example 1.

[0098] Comparative Example 2: No ozone catalyst was prepared, and the ozone catalyst described in step 2 was a commercially available ozone catalyst. Other steps and parameters were the same as those in Example 1.

[0099] Comparative Example 3: No ozone catalyst was added. Other steps and parameters were the same as those in Example 1.

[0100] The properties of the catalytic ozone functional ceramic membranes prepared in various examples and comparative examples are listed in Table 1;

[0101] Table 1

[0102]

[0103] It can be seen from Table 1 that the ceramic membranes prepared in each embodiment have excellent water permeability, high catalytic ozone decomposition rate, and significantly improved catalytic efficiency compared with the control example, which can effectively alleviate membrane pollution and increase the service life of the membrane.

[0104] In summary, the present invention adopts low-voltage direct current electrolysis technology to prepare ozone, and the preparation process is clean and pollution-free. The ozone oxidation technology is combined with the pressure-type ceramic membrane filtration technology. Ozone reacts with the catalyst on the membrane surface to remove pollutants in the water through ozone catalytic oxidation, while also allowing ozone to react with pollutants on the membrane surface, improving membrane surface dirt, inhibiting ceramic membrane fouling, and extending the service life of the ceramic membrane. In addition, the present invention integrates mechanical dredging brush physical cleaning, ozone water cleaning, online chemical cleaning and other methods to clean the pressure-type ceramic membrane, which can effectively avoid ceramic membrane fouling and extend the service life of the ceramic membrane. This water purification system is a water purification technology that can achieve efficient removal of various pollutants in water, including suspended matter, organic matter, bacteria, pesticides and viruses, while achieving long-term and stable operation of ceramic membranes.

Claims

1. A pressure-type ceramic membrane water purification system with integrated electrolytic ozone catalytic oxidation, characterized in that The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation comprises a water inlet valve (1), an ozone preparation unit (2), an ozone mixing unit (3), a pressure-type ceramic membrane unit (4), a water production valve (5), a backwash pump (6), a dosing pump (7), a cleaning valve (8), a sewage valve (9) and a clean water tank (10); The water inlet valve (1) and the ozone preparation unit (2) are respectively connected to the two inlets of the ozone mixing unit (3); the outlet of the ozone mixing unit (3) is connected to the water inlet at the top of the pressure-type ceramic membrane unit (4); the sewage outlet at the bottom of the pressure-type ceramic membrane unit (4) is connected to the sewage valve (9); the water outlet of the pressure-type ceramic membrane unit (4) is connected to one end of the water production valve (5), and the other end of the water production valve (5) is connected to the water inlet of the clean water tank (10); The water outlet of the clean water tank (10) is respectively connected to the water production tank and the sewage outlet of the pressure-type ceramic membrane unit (4); a backwash pump (6) and a cleaning valve (8) are provided on the pipeline connecting the clean water tank (10) and the sewage outlet of the pressure-type ceramic membrane unit (4); The pipeline connecting the clean water tank (10) and the sewage outlet of the pressure-type ceramic membrane unit (4) is also connected to the drug washing unit through the drug adding pump (7).

2. The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation according to claim 1 is characterized in that The ozone preparation unit (2) adopts low-pressure water electrolysis technology to prepare high-concentration ozone, and the concentration of ozone is greater than 20%.

3. The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation according to claim 1 is characterized in that The water electrolyzed by the ozone preparation unit (2) contains dilute sulfuric acid or hydrochloric acid to increase conductivity; aluminum is used as the cathode and Pt, SbO2, glassy carbon or diamond is used as the anode; and a perfluorosulfonic acid ion exchange membrane is used.

4. The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation according to claim 1 is characterized in that The ozone generated by electrolysis in the ozone preparation unit (2) is added using micro-nano bubble technology and enters the ozone mixing unit (3) so that the water to be treated and the ozone are fully mixed and reacted.

5. The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation according to claim 1 is characterized in that The pressure-type ceramic membrane unit (4) adopts a catalytic ceramic membrane.

6. A pressure-type ceramic membrane water purification system integrating electrolytic ozone catalytic oxidation according to claim 5, characterized in that The catalytic ceramic membrane is a catalytic ozone functional ceramic membrane, and the preparation method is specifically completed according to the following steps:

1. Preparation of ozone catalyst: ① Disperse the nitrogen source, boron source, copper source and potassium source in a solvent, then heat and stir for a period of time; evaporate the solvent, grind and obtain a precursor powder; ②, placing the precursor powder in a muffle furnace, heating it to a calcination temperature, and calcining it at the calcination temperature for a period of time to obtain boron-copper-potassium ternary doped carbon nitride; ③, spraying aluminum sol onto the outer surface of boron-copper-potassium ternary doped carbon nitride, and then drying and calcining to obtain a core-shell catalyst; ④, dissolving lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride into water to obtain a metal salt solution; ⑤. Immerse the core-shell catalyst in a metal salt solution, then add a complexing agent solution, stir for a period of time, take it out and dry it, then calcine it at 150℃~250℃ for 1h~2h, and finally calcine it at 900℃~950℃ for 2h~3h to obtain an ozone catalyst; 2. Preparation of catalytic ozone functional ceramic membrane: ①. Add ceramic membrane aggregate, sintering aid, pore former and binder into a ball mill and mix them evenly, then add ozone catalyst and continue to mix them evenly to obtain a mixed powder; add water to the mixed powder and blend it to obtain a ceramic membrane blend; ②. The ceramic membrane blend is left to stand and age, and is subjected to a vacuum clay kneading machine to obtain a mixed clay material; the mixed clay material is extruded and formed into a ceramic membrane embryo; the embryo is dried in an oven, and then calcined using a gradient temperature increase program to obtain a catalytic ozone functional ceramic membrane.

7. A pressure-type ceramic membrane water purification system integrating electrolytic ozone catalytic oxidation according to claim 6, characterized in that The nitrogen source described in step 1① is urea or melamine; the boron source described in step 1① is sodium metaborate, sodium tetraborate or boric acid; the copper source described in step 1① is copper nitrate, copper sulfate or copper acetate; the potassium source described in step 1① is potassium chloride, potassium carbonate or potassium sulfate; the solvent described in step 1① is water or anhydrous ethanol; the heating and stirring temperature described in step 1① is 60℃~90℃, and the heating and stirring time is 5h~7h; the molar ratio of the nitrogen source, boron source, copper source and potassium source described in step 1① is (300~500):(10~30):(1~10):(1~10).

8. The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation according to claim 6 is characterized in that The heating rate described in step 1② is 5℃ / min~10℃ / min; the calcination temperature is 500℃~600℃, and the calcination time is 3h~5h; the solid content of the aluminum sol described in step 1③ is 20%; the drying temperature described in step 1③ is 100℃~110℃, and the drying time is 2h~5h; the calcination temperature described in step 1③ is 600℃~700℃, and the calcination time is 5h~7h; the mass fraction of the shell in the core-shell catalyst described in step 1③ is 5%~10%.

9. The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation according to claim 6 is characterized in that The molar ratio of lanthanum nitrate, cerium nitrate, cadmium nitrate and cuprous chloride described in step 1④ is (8-10):(2-4):(1-3):(1-3); the complexing agent solution described in step 1⑤ is a citric acid solution with a concentration of 2mol / L-4mol / L; the volume ratio of the metal salt solution to the complexing agent solution described in step 1⑤ is 1:1; the stirring time described in step 1⑤ is 2h-4h.

10. The pressure-type ceramic membrane water purification system integrated with electrolytic ozone catalytic oxidation according to claim 6 is characterized in that The step 2① is a mixture of one or more of alumina, zirconium oxide, titanium dioxide and silicon carbide; the sintering aid described in step 2① is one or more of clay, kaolin, potassium feldspar, sodium feldspar, calcium carbonate and magnesium carbonate; the pore-forming agent described in step 2① is one or more of yellow dextrin, soluble starch, glucose and sodium chloride; the binder described in step 2① is polyvinyl alcohol, methyl cellulose or polyacrylamide; the mass ratio of the ceramic membrane aggregate, sintering aid, pore-forming agent, binder and water described in step 2① is (80-90):(10-15):( 10~15):10:(15~25); the mass ratio of the ozone catalyst to the ceramic membrane aggregate described in step 2① is (10~15):(80~90); the calcination described in step 2② is firstly heating to 600℃~800℃ at a heating rate of 5℃ / min~10℃ / min, sintering at 600℃~800℃ for 3h~6h, then heating to 1200℃~1500℃ at a heating rate of 5℃ / min~10℃ / min, sintering at 1200℃~1500℃ for 8h~12h, to obtain a catalytic ozone functional ceramic membrane.

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