Novel coal chemical industry wastewater treatment method

Abstract

The invention relates to the technical field of water treatment, and discloses a novel coal chemical industry wastewater treatment method. According to the method, physical and chemical pretreatment, oxidation advanced treatment, ultrafiltration and other modes are adopted, the problems that the coal chemical industry wastewater is high in toxicity and difficult to degrade can be solved, it can be guaranteed that final effluent stably reaches the standard, and meanwhile the treatment efficiency and the system impact resistance are both considered. A novel rare earth MOFs loaded Janus catalyst is adopted for oxidation advanced treatment, the catalyst efficiently activates ozone by means of multiple active sites of bimetal to generate. OH and Janus structures to achieve catalysis-salt resistance, the COD removal rate of the coal chemical industry wastewater can reach 80% or above, the chromaticity is remarkably reduced, salting-out resistance, corrosion resistance and cycle stability are excellent, and the application range is wide. The problems of low activity, non-uniform loading and poor salt resistance of the traditional catalyst are solved; tiny impurities in the deeply treated water body are removed through ultrafiltration, and the quality of the water body is further improved, so that water meeting the emission standard or recycled water is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, and in particular to a novel coal chemical industry wastewater treatment method. BACKGROUND

[0002] Coal chemical industry wastewater is high-difficulty industrial wastewater generated in the production process of coal chemical industry (such as coal-to-oil, coal-to-olefin, coal-to-methanol), which has high pollutant concentration, complex composition and strong toxicity, and is the focus and difficulty in the field of industrial wastewater treatment.

[0003] With the upgrading of environmental protection standards, coal chemical industry wastewater treatment technology is also constantly innovating. The earliest one is mainly physical and chemical pretreatment, aiming to reduce pollutant concentration and reduce toxicity, using extraction to remove phenol, combined with chemical precipitation to soften water quality, but only easy-to-treat pollutants are removed, and it cannot meet the discharge or recycling standards. In order to further reduce the content of toxic pollutants in coal chemical industry wastewater, biodegradable organic matter is degraded by using toxic-tolerant microorganisms, combined with physical and chemical pretreatment, but the biodegradable organic matter cannot be decomposed by microorganisms, such as polycyclic aromatic hydrocarbons, and the wastewater still cannot meet the discharge and recycling standards. With the continuous development of coal chemical industry, the treatment process of coal chemical industry wastewater is further iterated. On the basis of pretreatment and biochemical treatment, a deep treatment unit is added, and advanced oxidation technology, adsorption technology and membrane separation technology are used to further reduce the content of pollutants in wastewater, and resources such as phenol and ammonia in wastewater can be recycled, so as to realize the dual goals of standard discharge and resource recycling.

[0004] Chinese patent application with publication number CN101560045A discloses a coal chemical industry wastewater treatment process. The invention uses a gas floatation device to pretreat coal chemical industry wastewater, uses Fenton reagent to oxidize the wastewater, and then the treated wastewater enters an activated sludge aeration tank for deep treatment with activated carbon powder. Finally, the recycled water is obtained by ultrafiltration membrane separation, and then the recycled water is subjected to reverse osmosis through a selective semi-permeable membrane, and finally evaporation crystallization. The invention uses Fenton reagent to oxidize the wastewater. Although Fenton reagent can effectively break down part of the refractory organic matter, due to the reaction mechanism and the characteristics of coal chemical industry wastewater, Fenton reaction needs to be carried out in strong acid conditions, but the pH of raw coal chemical industry wastewater is usually 6-9, a large amount of acid needs to be added to adjust the pH, and alkali needs to be added after the reaction for neutralization. After Fenton reaction, Fe 2+ is oxidized to Fe 3+ , and Fe 3+ reacts with OH - to form Fe (OH) 3 flocs during the neutralization process, which can adsorb suspended solids, colloids and part of the organic matter in the wastewater, forming a large amount of iron-containing chemical sludge. The sludge contains heavy metals, and if not properly treated, it may cause secondary pollution. SUMMARY

[0005] The present application aims to provide a novel coal chemical wastewater treatment method. The method combines physical and chemical pretreatment such as filtration and softening, synergistic ozone catalytic oxidation advanced treatment, and ultrafiltration membrane filtration. A novel rare earth MOFs (rare earth metal-organic framework compound) loaded Janus catalyst (asymmetric amphiphilic catalyst) is used in the oxidation stage. The whole process can solve the problems of high toxicity and refractory of coal chemical wastewater, ensure that the final effluent meets the standard, and balance the treatment efficiency and system impact resistance. Filtration first removes interfering impurities such as suspended solids, coal dust, and colloidal particles from the wastewater, preventing them from clogging the catalyst pores of ozone catalytic oxidation or the ultrafiltration membrane assembly, and reducing the load of subsequent processes. Softening removes Ca 2+ , Mg 2+ , etc. to prevent high hardness ions from scaling on the inner wall of the ozone generator or forming inorganic pollutants on the surface of the ultrafiltration membrane, extending the service life of the catalyst and membrane. The rare earth MOFs loaded Janus nanoparticle catalyst is composed of multiple metal elements, has a stable single crystal structure, and has excellent corrosion resistance, which can better resist the erosion caused by complex components in high-salinity wastewater and high-temperature and high-pressure process conditions, thereby delaying the catalyst deactivation process. The wastewater is finally filtered by the ultrafiltration membrane to obtain water that meets the discharge and reuse standards.

[0006] To achieve the above purpose, the present application provides a novel coal chemical wastewater treatment method, comprising: S1, adjusting the wastewater into a multi-medium filter for filtration, and then adjusting the filtered wastewater into a softening tank for softening; S2, adjusting the softened wastewater into a flocculation tank, adding a flocculating agent, reacting, and then adjusting the filtered wastewater into a deep oxidation tank; S3, adjusting the pH of the wastewater in the deep oxidation tank to 6-7.5, adding a catalyst, introducing ozone, reacting, and obtaining deep treated wastewater; S4, separating the deep treated wastewater by an ultrafiltration membrane to obtain water meeting the discharge standard.

[0007] Preferably, in S1, the multi-medium filter is filled with three layers of filter layers, and the particle size decreases from top to bottom: the upper layer is anthracite with a particle size of 0.8-1.6 mm, the middle layer is quartz sand with a particle size of 0.5-0.8 mm, and the lower layer is refined garnet with a particle size of 0.3-0.5 mm.

[0008] Preferably, in S1, the filtration speed in the multi-medium filter is 30-50 m 3 / h, and the working pressure is 0.3-0.6 MPa.

[0009] Preferably, in the S1, the softening adopts a lime-soda softening method, and the specific steps and parameters include: adjusting the pH of the wastewater to 10-11, the mass-volume ratio of calcium hydroxide, anhydrous sodium carbonate and wastewater is (600-800) mg:(350-420) mg:1 L, the softening time is 20-40 min, and the stirring rate is 50-100 rpm.

[0010] Preferably, in the S2, the flocculant is polyacrylamide; and the mass-volume ratio of the flocculant and the wastewater is (0.5-2) mg:1 L.

[0011] Preferably, in the S2, the specific parameters of the reaction include: the reaction time is 20-40 min, the stirring rate is 20-50 rpm, the filtration adopts an inclined plate sedimentation tank, and the hydraulic retention time is 20-30 min.

[0012] Preferably, in the S3, the catalyst is a rare earth MOFs loaded Janus catalyst.

[0013] The application further provides a preparation method of the rare earth MOFs loaded Janus catalyst. A1, mixing nickel salt, copper salt and ligand, dispersing in deionized water, adjusting the pH to 6-7, microwave reaction, centrifugation, precipitation washing and drying to obtain Ni-UIO-66 (Cu) (nickel-copper bimetallic modified UIO-66 type metal organic framework material); A2, washing and drying porous titanium sheets, dispersing Ni-UIO-66 (Cu) and polyvinylpyrrolidone in deionized water, ultrasonic treatment to obtain an electrophoretic liquid, placing the electrophoretic liquid in an electrolytic cell, vertically placing the porous titanium sheets in the electrolytic cell, immersing one side in the electrophoretic liquid and shielding the other side with a polytetrafluoroethylene film, electrophoresis, drying, and forming a catalytic layer on the side immersed in the electrophoretic liquid; A3, taking out the dried porous titanium sheets, shielding one side of the catalytic layer with a polytetrafluoroethylene film, immersing the other side in a hydrophilic layer growth solution, reacting, and drying to obtain a Janus intermediate (asymmetric amphiphilic intermediate) with a hydrophilic layer only on one side surface of the porous titanium sheet; A4, dispersing methyltriethoxysilane in ethanol, adding deionized water and hydrochloric acid solution, stirring to form a silicon solution, uniformly coating the silicon solution on the surface of the Janus intermediate, drying, and solidifying into a gel film to obtain a rare earth MOFs loaded Janus catalyst.

[0014] Preferably, in the A1, the copper salt is Cu (NO3) 2·3H2O, the nickel salt is Ni (NO3) 2·6H2O, and the ligand is terephthalic acid.

[0015] Preferably, in the A1, the molar ratio of the copper salt to the nickel salt is (3-5):1, and the molar ratio of the sum of the two to the terephthalic acid is 1:1.

[0016] Preferably, in the A1, the power of the microwave reaction is 400-800 W, the temperature of the microwave reaction is 120-180℃, and the time of the microwave reaction is 1-3 h.

[0017] Preferably, in the A1, the temperature of the drying is 60℃, and the time of the drying is 4 h.

[0018] Preferably, in the A2, the temperature of the drying is 100-105℃, and the time of the drying is 2-3 h.

[0019] Preferably, in the A2, the mass ratio of the Ni-UIO-66(Cu) to the polyvinylpyrrolidone is 50:1.

[0020] Preferably, in the A2, the voltage of the electrophoresis is 10-20 V, and the time of the electrophoresis is 10-25 min.

[0021] Preferably, in the A2, the temperature of the drying is 40-50℃, and the time of the drying is 1-2 h.

[0022] Preferably, in the A3, the hydrophilic layer growth solution is a lanthanum salt-ytterbium salt double rare earth modified hydrotalcite loaded graphene oxide, wherein the main components of the hydrotalcite are Mg(NO3)2·6H2O and Al(NO3)3·9H2O, the molar ratio of Mg(NO3)2·6H2O to Al(NO3)3·9H2O is (2-4):1, the lanthanum salt is La(NO3)3·6H2O, the ytterbium salt is Yb(NO3)3·6H2O, and the molar ratio of lanthanum to ytterbium is (1-2):1.

[0023] Preferably, in the A3, the preparation method of the hydrophilic layer growth solution is: dispersing (0.05-0.1) g of graphene oxide in (50-100) mL of deionized water to obtain a graphene oxide dispersion, adding Mg(NO3)2·6H2O, Al(NO3)3·9H2O, La(NO3)3·6H2O, and Yb(NO3)3·6H2O to 100 mL of deionized water, heating in a 25-30℃ water bath, pouring into the graphene oxide dispersion under stirring, stirring, and adjusting the pH to 10; the temperature of the reaction is 70-80℃, and the time of the reaction is 2-3 h.

[0024] Preferably, in the A3, the temperature of the drying is 50-60℃, and the time of the drying is 2-3 h.

[0025] Preferably, in the A4, the volume ratio of the methyl triethoxysilane, ethanol, deionized water and hydrochloric acid is 1: (20-25): (0.5-0.75): 0.5.

[0026] Preferably, in the A4, the stirring time is 20-30 min.

[0027] Preferably, in the A4, the drying temperature is 30-40℃, and the drying time is 1-2h.

[0028] Preferably, in the A4, the concentration of the hydrochloric acid solution is 0.01-0.02 mol / L.

[0029] Preferably, in the S3, the mass-volume ratio of the catalyst and wastewater is (10-15) g: 1 L.

[0030] Preferably, in the S3, the reaction temperature is 25-35℃.

[0031] Preferably, in the S4, the specific process and parameters of the ultrafiltration membrane filtration include: the deeply treated wastewater enters a pretreatment unit to remove grease, then enters a filtration unit, is delivered to a membrane assembly by a booster pump, the working pressure is 0.1-0.3 MPa, the filtered water enters a water tank for temporary storage, and whether the discharge standard is reached or recycling is used is monitored.

[0032] Compared with the prior art, the beneficial effects of the present application are embodied in: (1) In the deep oxidation stage, the rare earth MOFs loaded Janus catalyst is used for synergistic catalytic oxidation with ozone. The rare earth MOFs loaded Janus nanoparticle catalyst has a stable single crystal phase structure composed of multiple metal elements. This structure endows the catalyst with excellent corrosion resistance, enabling it to better resist the erosion caused by complex components in high-salinity wastewater and high-temperature and high-pressure process conditions, thereby delaying the catalyst deactivation process; in the preparation process, the microwave-assisted hydrothermal method is used to prepare Ni-UIO-66 (Cu), and the uniformity and rapid heating characteristics of microwave heating can promote the uniform doping of bimetallic components, form a large number of metal ion active centers and oxygen vacancies, and efficiently activate the decomposition of ozone to produce ·OH, which can increase the mineralization rate of refractory organic matter by 20%-40%, and the COD removal rate can be more than 80%, solving the problems of single active site of traditional single-component MOF catalysts and low degradation efficiency of complex wastewater; the Ni-UIO-66 (Cu) is precisely loaded on one side of the porous titanium sheet through directional electrophoretic deposition, and the directional nature of the electric field in the deposition process can avoid the agglomeration of active components and ensure uniform exposure of active sites, with a loading uniformity of more than 90%, which significantly improves the contact efficiency of ozone, wastewater and active sites and avoids the defects of uneven loading and buried active sites in traditional impregnation methods.

[0033] (2) The present application adopts multi-medium filtration, softening, flocculation, advanced oxidation and ultrafiltration membrane separation, and specifically solves the complex pollution problems of coexistence of suspended solids, high hardness ions, colloids and refractory organic matter in industrial wastewater. The multi-medium filtration can efficiently intercept suspended solids, coal dust, silt and other large particle impurities in water, directly avoiding the problems of particle blocking the pipeline, covering the active sites of flocculants or scratching the surface of the ultrafiltration membrane, thereby prolonging the service life of the subsequent equipment; the lime-soda softening method is adopted to convert Ca 2+ , Mg 2+ and other ions in water into calcium carbonate, magnesium hydroxide and other precipitates, thereby reducing the total hardness of the water body, avoiding the formation of scale in the advanced oxidation tank and the generation of inorganic scale layer on the surface of the ultrafiltration membrane, ensuring the stability of the ozone mass transfer efficiency and the non-decay of the membrane flux; polyacrylamide is used as a flocculant to make small colloids aggregate into large flocs, which are removed by filtration to reduce COD; the advanced oxidation decomposes toxic substances in the wastewater, such as phenols, cyanide, heavy metal complexes and the like, so that the acute toxicity of the wastewater is reduced by more than 80%; finally, the ultrafiltration membrane is used to intercept small flocs, large molecular organic matter, catalyst residue particles and the like remaining after the advanced oxidation, so that the effluent meets the discharge standard. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A flow chart of a novel coal chemical industry wastewater treatment method provided by the present application.

[0035] Figure 2 A preparation flow chart of a rare earth MOFs loaded Janus catalyst provided by the present application.

[0036] Figure 3 COD removal rates of coal chemical industry wastewater treated by the methods of Example 4 to Example 6 and Comparative Example 4 to Comparative Example 6.

[0037] Figure 4 Color removal rates of coal chemical industry wastewater treated by the methods of Example 4 to Example 6 and Comparative Example 4 to Comparative Example 6.

[0038] Figure 5 A physical map of the rare earth MOFs loaded Janus catalyst prepared in Example 3.

[0039] Figure 6 A transmission electron microscope image of the rare earth MOFs loaded Janus catalyst prepared in Example 3. DETAILED DESCRIPTION

[0040] The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0041] The compounds used in the examples and comparative examples are all commercially available and are not subjected to any further purification treatment.

[0042] Example 1 like Figure 2 As shown, a rare earth MOF-supported Janus catalyst is prepared by the following method: A1. Mix 0.073g of Ni(NO3)2·6H2O, 0.181g of Cu(NO3)2·3H2O and 0.166g of terephthalic acid, disperse in 30mL of deionized water, sonicate for 30min until completely dissolved, adjust pH to 6, microwave at 120℃ for 3h at 400W, centrifuge, wash the precipitate with deionized water and dry at 60℃ for 4h to obtain Ni-UIO-66(Cu).

[0043] A2. Using porous titanium sheets as a carrier, the porous titanium sheets were ultrasonically cleaned with deionized water and ethanol for 10 min in sequence, and dried at 100℃ for 3 h. 0.5 g of Ni-UIO-66 (Cu) and 0.01 g of polyvinylpyrrolidone were dispersed in 100 mL of deionized water and ultrasonically treated for 20 min to obtain an electrophoresis solution. The solution was placed in an electrolytic cell, and the porous titanium sheets were vertically placed in the electrolytic cell with one side immersed in the electrophoresis solution and the other side covered with a polytetrafluoroethylene membrane. Electrophoresis was performed at 10 V for 25 min and dried at 40℃ for 2 h. A catalytic layer was formed on the side immersed in the electrophoresis solution.

[0044] A3. Prepare the hydrophilic layer growth solution. Disperse 0.05 g of graphene oxide in 50 mL of deionized water to obtain a graphene oxide dispersion. Add 2.307 g of Mg(NO3)2·6H2O, 1.125 g of Al(NO3)3·9H2O, 0.2598 g of La(NO3)3·6H2O, and 0.1347 g of Yb(NO3)3·6H2O to 100 mL of deionized water. Heat in a 25°C water bath and pour into the graphene oxide dispersion with stirring. Adjust the pH to 10 to obtain the hydrophilic layer growth solution.

[0045] The dried porous titanium sheet was taken out, one side of the catalyst layer was covered with a polytetrafluoroethylene film, and the other side was immersed in the hydrophilic layer growth solution prepared above. After reacting at 70°C for 3 hours and drying at 50°C for 3 hours, Janus intermediate with a hydrophilic layer modified only on one side of the porous titanium sheet was obtained.

[0046] A4. Disperse 1 mL of methyltriethoxysilane in 20 mL of ethanol, add 0.5 mL of deionized water and 0.5 mL of 0.01 mol / L hydrochloric acid solution, stir for 20 min to form a silicon solution, uniformly coat it on the surface of Janus intermediate, dry at 30 °C for 2 h to solidify into a gel film, and obtain rare earth MOFs supported Janus catalyst.

[0047] Example 2 like Figure 2As shown, a rare earth MOF-supported Janus catalyst is prepared by the following method: A1. Mix 0.058g of Ni(NO3)2·6H2O, 0.193g of Cu(NO3)2·3H2O and 0.166g of terephthalic acid, disperse in 30mL of deionized water, sonicate for 30min until completely dissolved, adjust pH to 7, microwave at 150℃ for 2h at 600W, centrifuge, wash the precipitate with deionized water and ethanol, and dry at 60℃ for 4h to obtain Ni-UIO-66(Cu).

[0048] A2. Using porous titanium sheets as a carrier, the porous titanium sheets were ultrasonically cleaned with deionized water and ethanol for 10 min in sequence, and dried at 105℃ for 3 h. 0.5 g of Ni-UIO-66 (Cu) and 0.01 g of polyvinylpyrrolidone were dispersed in 100 mL of deionized water and ultrasonically treated for 20 min to obtain an electrophoresis solution. The solution was placed in an electrolytic cell, and the porous titanium sheets were vertically placed in the electrolytic cell with one side immersed in the electrophoresis solution and the other side covered with a polytetrafluoroethylene membrane. Electrophoresis was performed at 15 V for 15 min, and then dried at 45℃ for 1.5 h. A catalytic layer was formed on the side immersed in the electrophoresis solution.

[0049] A3. Prepare the hydrophilic layer growth solution. Disperse 0.05 g of graphene oxide in 75 mL of deionized water to obtain a graphene oxide dispersion. Add 2.307 g of Mg(NO3)2·6H2O, 1.125 g of Al(NO3)3·9H2O, 0.2338 g of La(NO3)3·6H2O, and 0.1617 g of Yb(NO3)3·6H2O to 100 mL of deionized water. Heat in a 30°C water bath and pour into the graphene oxide dispersion with stirring. Adjust the pH to 10 to obtain the hydrophilic layer growth solution.

[0050] The dried porous titanium sheet was taken out, one side of the catalyst layer was covered with a polytetrafluoroethylene film, and the other side was immersed in the hydrophilic layer growth solution prepared above. After reacting at 75°C for 2.5 h and drying at 55°C for 2.5 h, Janus intermediate was obtained.

[0051] A4. Disperse 1 mL of methyltriethoxysilane in 25 mL of ethanol, add 0.75 mL of deionized water and 0.5 mL of 0.015 mol / L hydrochloric acid solution, stir for 25 min to form a silicon solution, uniformly coat it on the surface of Janus intermediate, dry at 35 °C for 1.5 h to solidify into a gel film, and obtain rare earth MOFs supported Janus catalyst.

[0052] Example 3 like Figure 2 As shown, a rare earth MOF-supported Janus catalyst is prepared by the following method: A1, 0.048 g of Ni(NO3)2·6H2O, 0.201 g of Cu(NO3)2·3H2O and 0.166 g of terephthalic acid were mixed and dispersed in 30 mL of deionized water, ultrasonic dispersion was performed for 30 min until complete dissolution, the pH was adjusted to 7, 800 W microwave was used at 180℃ for 1 h, centrifugation was performed, the precipitate was washed with deionized water, ethanol and dried at 60℃ for 4 h to obtain Ni-UIO-66(Cu).

[0053] A2, porous titanium sheets were selected as the carrier, the porous titanium sheets were sequentially cleaned with deionized water and ethanol for 10 min under ultrasonic, and dried at 105℃ for 2 h, 0.5 g of Ni-UIO-66(Cu) and 0.01 g of polyvinylpyrrolidone were dispersed in 100 mL of deionized water, ultrasonic treatment was performed for 20 min to obtain an electrophoretic solution, the electrophoretic solution was placed in an electrolytic cell, the porous titanium sheet was vertically placed in the electrolytic cell, one side was immersed in the electrophoretic solution and the other side was shielded with a polytetrafluoroethylene film, electrophoresis was performed at 20 V for 10 min, and drying was performed at 50℃ for 1 h, and the catalytic layer was formed on the side immersed in the electrophoretic solution.

[0054] A3, a hydrophilic layer growth solution was prepared, 0.1 g of graphene oxide was dispersed in 100 mL of deionized water to obtain a graphene oxide dispersion solution. 3.07 g of Mg(NO3)2·6H2O, 1.125 g of Al(NO3)3·9H2O, 0.3464 g of La(NO3)3·6H2O and 0.1796 g of Yb(NO3)3·6H2O were added to 100 mL of deionized water, heated in a 30℃ water bath, and poured into the graphene oxide dispersion solution under stirring, and the pH was adjusted to 10 to obtain the hydrophilic layer growth solution.

[0055] The dried porous titanium sheet was taken out, the catalytic layer was shielded with a polytetrafluoroethylene film, the other side was immersed in the above-prepared hydrophilic layer growth solution, and reaction was performed at 80℃ for 2 h, and drying was performed at 60℃ for 2 h to obtain a Janus intermediate.

[0056] A4, 1 mL of methyltriethoxysilane was dispersed in 20 mL of ethanol, 0.5 mL of deionized water and 0.5 mL of 0.02 mol / L hydrochloric acid solution were added, stirring was performed for 30 min to form a silicon solution, which was uniformly coated on the surface of the Janus intermediate, dried at 40℃ for 1 h, solidified into a gel film to obtain a rare earth MOFs loaded Janus catalyst, and the catalyst was as shown in Figure 5 , and the transmission electron microscope image was as shown in Figure 6 .

[0057] Comparative Example 1 A rare earth MOFs loaded Janus catalyst, the difference between the preparation method and Example 3 is that no Ni(NO3)2·6H2O is added in A1, and the other operation steps and process parameters are completely the same as those of Example 3.

[0058] Comparative Example 2 A rare earth MOFs loaded Janus catalyst, the difference between the preparation method and example 3 is that in A2, the porous titanium sheet coated with Ni-UIO-66(Cu) on one side is not used by electrophoresis, and the coating is carried out by traditional coating method, and other operation steps and process parameters are completely same as example 3.

[0059] Comparative Example 3 A rare earth MOFs loaded Janus catalyst, the difference between the preparation method and example 3 is that in A2, the porous titanium sheet coated with Ni-UIO-66(Cu) on one side is not used by electrophoresis, and the coating is carried out by traditional coating method, and other operation steps and process parameters are completely same as example 3.

[0060] Example 4 As shown in Figure 1 , a new coal chemical wastewater treatment method, comprising: S1, the wastewater is adjusted by water pump into the multi-medium filter for filtration, the wastewater is passed through the upper layer of 1.6mm particle size anthracite coal layer, the middle layer of 0.8mm particle size quartz sand, and the lower layer of 0.5mm particle size refined garnet under the working pressure of 0.3MPa at the rate of 30m 3 / h, the filtered wastewater enters the softening tank, the pH of the wastewater is adjusted to 10, calcium hydroxide and anhydrous sodium carbonate are added, stirring is carried out at the speed of 50rpm, softening is carried out for 40min, and the mass volume ratio of calcium hydroxide, anhydrous sodium carbonate and wastewater is 600mg:350mg:1L.

[0061] S2, the softened wastewater enters the flocculation tank, polyacrylamide is added, stirring reaction is carried out at the speed of 20rpm for 40min, enters the inclined plate sedimentation tank and stays for 30min, and the filtered wastewater enters the advanced oxidation tank, the mass volume ratio of polyacrylamide and wastewater is 0.5mg:1L.

[0062] S3, the pH of the wastewater in the advanced oxidation tank is adjusted to 6, the rare earth MOFs loaded Janus catalyst prepared in example 1 is added, the ozone generator is started to pass in ozone, the flow rate of ozone gas is 0.5L / min, the reaction is carried out at 25℃ for 4h, the advanced treatment wastewater is obtained, and the mass volume ratio of the rare earth MOFs loaded Janus catalyst and the wastewater is 10g:1L.

[0063] S4, the deep treated wastewater enters the pretreatment unit of the ultrafiltration system to remove the oil on the surface of the water body, then enters the filtration unit, is delivered to the membrane assembly by the booster pump, the working pressure of the membrane assembly is 0.1 MPa, the wastewater passes through the ultrafiltration membrane under this condition, water and small molecules pass through the membrane to form product water, the retentate is intercepted on the ultrafiltration membrane, and the product water is temporarily stored in the water tank to monitor whether the discharge standard is reached or recycling is used.

[0064] Example 5 As shown in Figure 1 , a new coal chemical wastewater treatment method comprises: S1, the wastewater is filtered into the multi-medium filter by the water pump, the wastewater passes through the upper layer of 1.2 mm particle size anthracite coal layer, the middle layer of 0.7 mm particle size quartz sand, and the lower layer of 0.4 mm particle size refined garnet under the working pressure of 0.4 MPa at the rate of 40 m 3 / h, the filtered wastewater enters the softening tank, the pH of the wastewater is adjusted to 11, calcium hydroxide and anhydrous sodium carbonate are added, stirring is carried out at the speed of 75 rpm, softening is carried out for 30 min, and the mass-volume ratio of calcium hydroxide, anhydrous sodium carbonate and wastewater is 700 mg:400 mg:1 L.

[0065] S2, the softened wastewater enters the flocculation tank, polyacrylamide is added, stirring is carried out at the speed of 35 rpm for 30 min, enters the inclined plate sedimentation tank and stays for 25 min, and the filtered wastewater enters the advanced oxidation tank, the mass-volume ratio of polyacrylamide and wastewater is 1 mg:1 L.

[0066] S3, the wastewater in the advanced oxidation tank is adjusted to pH 7, the rare earth MOFs loaded Janus catalyst prepared in example 2 is added, the ozone generator is started to pass in ozone, the flow rate of the ozone gas is 0.5 L / min, 30 °C is reacted for 4 h, the deep treated wastewater is obtained, and the mass-volume ratio of the rare earth MOFs loaded Janus catalyst and the wastewater is 12 g:1 L.

[0067] S4, the deep treated wastewater enters the pretreatment unit of the ultrafiltration system to remove the oil on the surface of the water body, then enters the filtration unit, is delivered to the membrane assembly by the booster pump, the working pressure of the membrane assembly is 0.2 MPa, the wastewater passes through the ultrafiltration membrane under this condition, water and small molecules pass through the membrane to form product water, the retentate is intercepted on the ultrafiltration membrane, and the product water is temporarily stored in the water tank to monitor whether the discharge standard is reached or recycling is used.

[0068] Example 6 As shown in Figure 1 , a new coal chemical wastewater treatment method comprises: S1, the wastewater is filtered into the multi-medium filter by the water pump, the wastewater passes through the upper layer of 1.2 mm particle size anthracite coal layer, the middle layer of 0.7 mm particle size quartz sand, and the lower layer of 0.4 mm particle size refined garnet under the working pressure of 0.4 MPa at the rate of 40 m 3The filtered wastewater enters a softening tank, the pH of the wastewater is adjusted to 10, calcium hydroxide and anhydrous sodium carbonate are added, stirring is carried out at a speed of 100 rpm, and softening is carried out for 20 min; the mass-volume ratio of calcium hydroxide, anhydrous sodium carbonate and wastewater is 800 mg: 420 mg: 1 L.

[0069] S2, the softened wastewater enters a flocculation tank, polyacrylamide is added, stirring is carried out at a speed of 50 rpm, and reaction is carried out for 20 min, then the wastewater enters an inclined plate sedimentation tank and stays for 20 min, and then the filtered wastewater enters a deep oxidation tank; the mass-volume ratio of polyacrylamide and wastewater is 2 mg: 1 L.

[0070] S3, the wastewater in the deep oxidation tank is adjusted to a pH of 7.5, the rare earth MOFs loaded Janus catalyst prepared in Example 3 is added, an ozone generator is started to introduce ozone, the flow rate of the ozone gas is 0.5 L / min, and reaction is carried out at 35℃ for 4 h to obtain deep treated wastewater; the mass-volume ratio of the rare earth MOFs loaded Janus catalyst and wastewater is 15 g: 1 L.

[0071] S4, the deep treated wastewater enters a pretreatment unit of an ultrafiltration system to remove oil on the surface of the water body, and then enters a filtration unit, is transported to a membrane assembly by a booster pump, the working pressure of the membrane assembly is 0.3 MPa, the wastewater passes through the ultrafiltration membrane under this condition, water and small molecular substances pass through the membrane to form product water, and the retentate is retained on the ultrafiltration membrane; the product water enters a water tank for temporary storage, and whether the discharge standard is reached or recycling is used is monitored.

[0072] Comparative Example 4 A new coal chemical wastewater treatment method, which is different from Example 4 in that S3 uses the catalyst prepared in Comparative Example 1.

[0073] Comparative Example 5 A new coal chemical wastewater treatment method, which is different from Example 4 in that S3 uses the catalyst prepared in Comparative Example 2.

[0074] Comparative Example 6 A new coal chemical wastewater treatment method, which is different from Example 4 in that S3 uses the catalyst prepared in Comparative Example 3.

[0075] The discharge standard water samples obtained in Examples 4 to 6 and Comparative Examples 4 to 6 are used to analyze COD by a water quality analyzer and to measure chroma by a spectrophotometer.

[0076] Figure 3The COD removal rates of the samples of Examples 4-6 and Comparative Examples 4-6 are shown in Table 1. The COD removal rates of the samples of Examples 4-6 are all above 80%, and the COD removal rates of the samples of Comparative Examples 4-6 are all below 50%.

[0077] Figure 4 The color reduction efficiencies of the samples of Examples 4-6 and Comparative Examples 4-6 are shown in Table 2. The color reduction efficiencies of the samples of Examples 4-6 are all above 80%, and the color reduction efficiencies of the samples of Comparative Examples 4-6 are all below 60%.

[0078] This is because the catalyst used in Comparative Example 4 does not contain metal nickel, and the catalyst changes from a bimetallic site to a single metal site, lacks the stability brought by the bimetallic site, and the active site is single, so the ozone activation efficiency drops sharply, resulting in reduced catalytic activity; the catalyst used in Comparative Example 5 is coated on the porous titanium sheet without electrophoretic orientation, but uses a traditional coating method, so the thickness of the catalyst layer of the prepared catalyst is not uniform, and the catalyst layer is easy to fall off, the active site is not exposed enough, and thus the catalytic activity is reduced; in Comparative Example 6, the catalyst layer is treated by sol-gel method during the preparation process, and the outer layer is not protected, so the salt resistance of the catalyst layer is greatly reduced, the stability of Janus is reduced, the durability in the complex water environment of coal chemical wastewater is reduced, and the effect of the synergistic ozone catalytic oxidation treatment is reduced.

[0079] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present application, and these improvements and modifications should also be considered as falling within the protection scope of the present application.

Claims

1. A novel coal chemical wastewater treatment method, characterized in that, The application relates to a method for treating wastewater, which comprises the following steps: S1, filtering wastewater into a multi-medium filter, and then softening the filtered wastewater in a softening tank; S2, adding a flocculant into the softened wastewater in a flocculation tank, and then filtering the reacted wastewater into a deep oxidation tank; S3, adjusting the pH of the wastewater in the deep oxidation tank to 6-7.5, adding a catalyst, and then introducing ozone into the wastewater to obtain deep-treated wastewater; S4, separating the deep-treated wastewater through an ultrafiltration membrane to obtain water meeting the discharge standard or being reused; The catalyst in S3 is a rare earth MOFs loaded Janus catalyst, and the preparation method of the catalyst comprises the following steps: A1, mixing a nickel salt, a copper salt and a ligand, dispersing them in deionized water, adjusting the pH to 6-7, microwave reacting, centrifuging, precipitating, washing and drying to obtain Ni-UIO-66 (Cu); A2, washing and drying porous titanium sheets, dispersing the Ni-UIO-66 (Cu) and polyvinylpyrrolidone in deionized water, ultrasonic treating to obtain an electrophoretic liquid, placing the electrophoretic liquid in an electrolytic tank, vertically placing the porous titanium sheets in the electrolytic tank, immersing one side of the porous titanium sheets into the electrophoretic liquid and shielding the other side of the porous titanium sheets with a polytetrafluoroethylene film, electrophoresing, and drying to form a catalytic layer on the side of the porous titanium sheets immersed into the electrophoretic liquid; A3, taking out the dried porous titanium sheets, shielding the side of the catalytic layer with the polytetrafluoroethylene film, immersing the other side of the catalytic layer into a hydrophilic layer growth solution, reacting, and drying to obtain a Janus intermediate with a hydrophilic layer only on one side of the surface of the porous titanium sheets; A4, dispersing methyltriethoxysilane in ethanol, adding deionized water and a hydrochloric acid solution, stirring to form a silicon solution, uniformly coating the silicon solution on the surface of the Janus intermediate, drying, and solidifying into a gel film to obtain the rare earth MOFs loaded Janus catalyst.

2. The novel coal chemical wastewater treatment method according to claim 1, characterized in that, In the S1, the multi-medium filter is filled with three layers of filter layers, and the particle size from top to bottom is from large to small: the upper layer is anthracite with a particle size of 0.8-1.6 mm, the middle layer is quartz sand with a particle size of 0.5-0.8 mm, and the lower layer is refined garnet with a particle size of 0.3-0.5 mm; in the multi-medium filter, the filtering speed is 30-50 m 3 / h, and the working pressure is 0.3-0.6 MPa. The softening adopts a lime-soda softening method, and the specific steps and parameters comprise the following steps: adjusting the pH of the wastewater to 10-11, the mass / volume ratio of calcium hydroxide, anhydrous sodium carbonate and the wastewater being (600-800) mg:(350-420) mg:1 L, the softening time being 20-40 min, and the stirring speed being 50-100 rpm.

3. The method according to claim 1, characterized in that, In S2, the flocculant is polyacrylamide; the mass / volume ratio of the flocculant and the wastewater is (0.5-2) mg:1 L; and the specific parameters of the reaction comprise the following steps: the reaction time is 20-40 min, the stirring speed is 20-50 rpm, the filtration adopts an inclined plate sedimentation tank, and the hydraulic retention time is 20-30 min.

4. The novel coal chemical wastewater treatment method according to claim 1, characterized in that, In A1, the copper salt is Cu (NO3)2.3H2O, the nickel salt is Ni (NO3)2.6H2O, and the ligand is terephthalic acid; the molar ratio of the copper salt to the nickel salt is (3-5):1, and the molar ratio of the sum of the copper salt and the nickel salt to the terephthalic acid is 1:1; the microwave reaction power is 400-800 W, the microwave reaction temperature is 120-180 DEG C, and the microwave reaction time is 1-3 h; and the drying temperature is 60 DEG C, and the drying time is 4 h.

5. The novel coal chemical wastewater treatment method according to claim 1, characterized in that, In the A2, the drying temperature is 100-105 DEG C, the time is 2-3h; the mass ratio of the Ni-UIO-66 (Cu) and polyvinylpyrrolidone is 50:1; the voltage of the electrophoresis is 10-20V, the time of the electrophoresis is 10-25min; the drying temperature is 40-50 DEG C, the drying time is 1-2h.

6. The novel coal chemical wastewater treatment method according to claim 1, characterized in that, In the A3, the hydrophilic layer growth solution is lanthanum salt-ytterbium salt double rare earth modified hydrotalcite loaded graphene oxide, wherein the main components of the hydrotalcite are Mg (NO3) 2·6H2O and Al (NO3) 3·9H2O, the molar ratio of Mg (NO3) 2·6H2O and Al (NO3) 3·9H2O is (2-4):1, the lanthanum salt is La (NO3) 3·6H2O, the ytterbium salt is Yb (NO3) 3·6H2O, and the molar ratio of lanthanum and ytterbium is (1-2):

1.

7. The novel coal chemical wastewater treatment method according to claim 1, characterized in that, In the A3, the preparation method of the hydrophilic layer growth solution is: dispersing (0.05-0.1) g of graphene oxide in (50-100) mL of deionized water to obtain a graphene oxide dispersion, adding Mg (NO3) 2·6H2O, Al (NO3) 3·9H2O, La (NO3) 3·6H2O and Yb (NO3) 3·6H2O into 100 mL of deionized water, heating in a 25-30 DEG C water bath, pouring into the graphene oxide dispersion under stirring, stirring, and adjusting the pH to 9-10; the reaction temperature is 70-80 DEG C, the reaction time is 2-3h; the drying temperature is 50-60 DEG C, and the drying time is 2-3h.

8. The novel coal chemical wastewater treatment method according to claim 1, characterized in that, In the A4, the volume ratio of methyltriethoxysilane, ethanol, deionized water and hydrochloric acid is 1:(20-25):(0.5-0.75):0.5; the stirring time is 20-30min; the drying temperature is 30-40 DEG C, the drying time is 1-2h, and the concentration of the hydrochloric acid solution is 0.01-0.02mol / L.

9. The novel coal chemical wastewater treatment method according to claim 1, characterized in that, In the S3, the mass-volume ratio of the catalyst and wastewater is (10-15) g:1L; the reaction temperature is 25-35 DEG C; in the S4, the specific process and parameters of the ultrafiltration membrane filtration include: the deep treatment wastewater enters the pretreatment unit to remove grease, then enters the filtration unit, is delivered to the membrane assembly by a booster pump, the working pressure is 0.1-0.3MPa, the filtered water enters the water tank for temporary storage, and whether the discharge standard is reached or recycling is used is monitored.

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