Cathode dynamic membrane for organic wastewater treatment and preparation method and application thereof

Abstract

The application provides a cathode dynamic membrane for organic wastewater treatment and a preparation method and application thereof, and belongs to the field of organic wastewater treatment; specifically provides a cathode dynamic membrane for organic wastewater treatment and a preparation method thereof, the preparation method comprises the following steps: mixing a pre-coating agent with water to obtain a pre-coating agent mixture; making the obtained pre-coating agent mixture uniformly pass through a dynamic membrane base net to form a film, and obtaining the cathode dynamic membrane; the pre-coating agent comprises powdered activated carbon and / or polyaluminum chloride of two particle sizes. The application also provides application of the cathode dynamic membrane for organic wastewater treatment in treatment of organic wastewater; compared with the prior art, the application adopts a composite mode of activated carbon and / or polyaluminum chloride of different particle sizes to prepare the cathode dynamic membrane for organic wastewater treatment; effective removal of pollutants in the organic wastewater can be achieved earlier; and the cathode dynamic membrane can be used as an electrocatalytic cathode, and has a longer service life.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic wastewater treatment, and particularly relates to a cathode dynamic membrane for organic wastewater treatment and a preparation method and application thereof. BACKGROUND

[0002] Wastewater produced by pharmaceutical, printing and dyeing, petroleum, coking and other industries is a main source of refractory organic wastewater. The refractory organic wastewater has complex composition, high organic matter concentration and poor biodegradability, and can rapidly pollute natural elements such as water bodies and soil after being discharged into the natural water bodies and soil, and the organic pollutants have great toxicity and harm. It is difficult to achieve ideal treatment effect by using traditional biological method and physical and chemical method to treat the refractory organic wastewater, and the operation process is complex and the cost is relatively high.

[0003] In order to effectively remove the organic components in wastewater, electro-catalytic oxidation is a typical advanced oxidation technology, which directly decomposes organic matter on the electrode through electron gain and loss reaction, or indirectly makes organic matter degrade through the generation of strong oxidizing substances such as hydroxyl radicals and hydrogen peroxide, and is a green and environmentally friendly technology. In order to further improve the removal efficiency of the organic components in wastewater, the existing technology often uses activated sludge for microbial treatment at the same time and combines with electro-catalytic oxidation and other means to treat the organic components in wastewater.

[0004] Dynamic membrane is one of the structures that can be combined with microbial treatment and electro-catalytic oxidation technology to purify wastewater, and the dynamic membrane refers to a new membrane formed on the surface of the membrane by a pre-coating agent or activated sludge itself, which is also called secondary membrane. The pre-coating dynamic membrane technology is to improve the biological layer in the biological dynamic membrane technology into a pre-coating layer formed by one or more natural or artificially synthesized inorganic or organic substances. The pre-coating layer ensures that the particles are large, so that the dynamic porosity formed is not compressible, and the permeability is enhanced. The commonly used substrates during pre-coating include stainless steel mesh, ordinary screen mesh, industrial filter cloth, ceramic tube and the like, and the coating materials include ZrO2, MnO2, kaolin, diatomite, TiO2 and the like, and the particle size of the pre-coating agent needs to be in the micron level. When the dynamic membrane is seriously polluted, the pre-coating agent can carry the pollutants away from the surface of the membrane. The dynamic membrane has attracted more attention and research due to its low cost and good anti-pollution performance.

[0005] Chinese patent application CN113003877A discloses an electro-catalysis coupled aerobic self-generating dynamic membrane reactor for treating refractory organic wastewater and a treatment method of refractory organic wastewater. The wastewater enters the aerobic sludge reaction tank through the water inlet system, and the sludge-water mixture treated by the aerobic process is separated by the self-generating dynamic membrane on the cathode net, and the wastewater in the membrane body is degraded, mineralized and disinfected by the strong oxidizing substances such as hydroxyl radicals and hydrogen peroxide generated by the electro-catalysis process, and then discharged from the outlet pipe. The electric current can further alleviate the pollution of the self-generating dynamic membrane and prolong the working time.

[0006] The dynamic membrane often depends on the accumulation of film-forming substances. For example, the self-generating dynamic membrane formed by the accumulation of activated sludge, activated sludge adsorbents and other substances on the membrane as disclosed in the above patent, or the dynamic membrane formed by pre-coating the above coating material; however, through experiments, it is found that although these dynamic membranes can effectively intercept macromolecular organic matter or insoluble particulate matter, due to the need for time to generate the self-generating dynamic membrane or pre-coat the material with large voids to maintain the wastewater flux, the dynamic membrane often has pollutants passing through the base net of the self-generating dynamic membrane which is not completely formed or the coating material with large voids in the early stage of use, resulting in excessive pollutants in the purified water before wastewater treatment. At the same time, in order to form an effective dynamic membrane as soon as possible, simply using a coating material with small pores to prepare a dynamic membrane often leads to membrane pollution of the dynamic membrane and reduces the service life of the dynamic membrane.

[0007] Therefore, how to provide a cathode dynamic membrane for electro-catalysis which can take effect quickly and has a longer service life is one of the key problems for researchers in the field. SUMMARY

[0008] In the present application, the "particle size" is taken from the following particle size ranges, each size range being a particle size fraction:

[0009] 0.053-0.063mm, 0.063-0.075mm, 0.075-0.090mm, 0.090-0.106mm and 0.106-0.125mm.

[0010] The relationship between the particle size and the mesh number (per inch) of the screen is as follows:

[0011] 0.053mm: 270 mesh;

[0012] 0.063mm: 230 mesh;

[0013] 0.075mm: 200 mesh;

[0014] 0.090mm: 170 mesh;

[0015] 0.106mm: 140 mesh;

[0016] 0.125 mm: 120 mesh.

[0017] In the present application, when the passing rate of any amount of particles on a screen with small mesh size is 80-90% and the passing rate on a screen with large mesh size is 10-20% in a particle size fraction, the particles can be considered as the particles in the particle size fraction.

[0018] To solve the problems of slow dynamic membrane activation speed, short service life and poor combination with electro-catalytic means in the prior art, the present application provides a cathode dynamic membrane for organic wastewater treatment and a preparation method and application thereof.

[0019] A preparation method of a cathode dynamic membrane for organic wastewater treatment, comprising the following steps:

[0020] (1) mixing a pre-coating agent with water to obtain a pre-coating agent mixture;

[0021] (2) making the pre-coating agent mixture obtained in step (1) uniformly pass through a dynamic membrane base web to form a film, to obtain the cathode dynamic membrane;

[0022] The pre-coating agent comprises two particle size fractions of powdered activated carbon and / or polyaluminum chloride.

[0023] Preferably, the pre-coating agent in step (1) comprises two particle size fractions of 0.053-0.090 mm and 0.090-0.125 mm of powdered activated carbon and / or polyaluminum chloride, and the mass usage ratio of the two particle size fractions of 0.053-0.090 mm and 0.090-0.125 mm of powdered activated carbon and / or polyaluminum chloride is 1-3:1.

[0024] Further preferably, the pre-coating agent comprises two particle size fractions of 0.053-0.075 mm and 0.090-0.125 mm of powdered activated carbon and / or polyaluminum chloride, and the mass usage ratio of the two particle size fractions of 0.053-0.075 mm and 0.090-0.125 mm of powdered activated carbon and / or polyaluminum chloride is 2-3:1.

[0025] More preferably, the pre-coating agent comprises two particle size fractions of 0.063-0.075 mm and 0.106-0.125 mm of powdered activated carbon and / or polyaluminum chloride, and the mass usage ratio of the two particle size fractions of 0.063-0.075 mm and 0.106-0.125 mm of powdered activated carbon and / or polyaluminum chloride is 2:1.

[0026] Most preferably, the pre-coating agent comprises activated carbon of 0.063-0.075 mm and polyaluminum chloride of 0.106-0.125 mm; the mass ratio of the activated carbon of 0.063-0.075 mm and the polyaluminum chloride of 0.106-0.125 mm is 2:1.

[0027] Preferably, the concentration of the pre-coating agent in the pre-coating agent mixture in step (1) is 50-300 mg / L.

[0028] Further preferably, the concentration of the pre-coating agent in the pre-coating agent mixture is 100-235 mg / L.

[0029] Most preferably, the concentration of the pre-coating agent in the pre-coating agent mixture is 185 mg / L.

[0030] Preferably, the mixing method in step (1) is micro-bubble aeration for 3-20 min or magnetic stirrer stirring: stirring at 300 r / min for 0.5-1.0 min, then stirring at 150 r / min for 3-10 min, and then stirring at 70 r / min for 8-20 min.

[0031] Preferably, the dynamic membrane base net in step (2) comprises at least one of stainless steel net, titanium net, nickel net and copper net.

[0032] Preferably, the pore size of the dynamic membrane base net in step (2) ranges from 200 to 270 mesh.

[0033] Preferably, the shape of the dynamic membrane base net in step (2) comprises but is not limited to cylinder, layer, sheet and pleat.

[0034] Preferably, the time for film formation in step (2) is 30-120 min.

[0035] The application also provides a cathode dynamic membrane for organic wastewater treatment prepared by the above preparation method.

[0036] The application also provides the use of the cathode dynamic membrane for organic wastewater treatment prepared by the above preparation method in treating organic wastewater.

[0037] The application also provides a method for treating organic wastewater by using the cathode dynamic membrane for organic wastewater treatment prepared by the above preparation method, comprising the following steps:

[0038] (1) treating wastewater by using activated sludge to obtain pretreated wastewater;

[0039] (2) treating the pretreated wastewater obtained in step (1) by using the cathode dynamic membrane to obtain intermediate treated wastewater;

[0040] (3) electrocatalytic oxidation of the intermediate treatment wastewater obtained in step (2) to obtain purified water.

[0041] Preferably, the membrane flux in the process of treating the organic wastewater is controlled in the range of 20-150 L / (m 2 ·h).

[0042] Preferably, the concentration of organic pollutants in the wastewater in step (1) is: COD 60-8000 mg / L.

[0043] Preferably, the mixed liquor suspended solids concentration (MLSS) of the activated sludge in step (1) is: 3800-4200 mg / L.

[0044] Preferably, the cathode dynamic membrane treatment in step (2) includes the step of using a cathode dynamic membrane filter.

[0045] Preferably, the electrocatalytic oxidation in step (3) uses the cathode dynamic membrane in step (2) as a cathode.

[0046] Further preferably, the electrocatalytic oxidation uses a metal-organic framework (MOF) electrode as an anode.

[0047] Most preferably, the metal-organic framework electrode is a NiFe bimetallic metal-organic framework (NiFe-MOF) electrode;

[0048] The preparation method of the NiFe-MOF electrode includes the following steps:

[0049] (1) immerse the electrode substrate in a mixed solution of Ni(Ac)2·4H2O, Fe(NO3)3·9H2O and 2,6-naphthalene dicarboxylic acid tetrahydrate, the mass ratio of Ni(Ac)2·4H2O, Fe(NO3)3·9H2O, organic ligand 2,6-naphthalene dicarboxylic acid tetrahydrate and deionized water being 8:2:10:1, to obtain a soaked substrate;

[0050] (2) seal the soaked substrate obtained in step (1), react at 60°C for 20 h, cool, ultrasonic clean for 1 min, and deionized water clean, to obtain a NiFe-MOF electrode;

[0051] The electrode substrate is selected from one or both of a stainless steel mesh and a nickel mesh.

[0052] Preferably, the process parameters of the electrocatalytic oxidation in step (3) are: constant voltage mode, applied voltage 1.6-2 V.

[0053] Compared with the prior art, the present application has the following beneficial effects:

[0054] This invention uses activated carbon of different particle sizes and / or polyaluminum chloride to prepare a dynamic membrane for organic wastewater treatment. Compared with the prior art, the dynamic membrane prepared by the method provided by this invention can achieve effective removal of pollutants from organic wastewater earlier and has a longer service life. Detailed Implementation

[0055] It is worth noting that the raw materials used in this invention are all commercially available products, and their sources are not specifically limited.

[0056] The activated sludge used in this invention comes from the return sludge of a local wastewater treatment plant.

[0057] The test container used in this embodiment of the invention is a cubic container with a length, width and height of 60mm. The cubic container has no top surface and has a 30mm circular opening at the center of two opposite sides. Electrodes can be fixed inside the cubic opening, and water inlet pipes and water outlet pipes are connected to the outside of the opening.

[0058] I. Examples and Comparative Examples

[0059] Example 1: A method for preparing a cathode dynamic membrane for organic wastewater treatment

[0060] (1) Preparation of pre-coating agent mixture:

[0061] Activated carbon with a particle size of 0.053-0.063 mm and polyaluminum chloride with a particle size of 0.090-0.106 mm were mixed at a mass ratio of 1:1, and water was added to prepare a pre-coating agent solution of 185 mg / L. The solution was aerated with microbubbles for 8 min to obtain the pre-coating agent mixture.

[0062] (2) Selection of dynamic membrane base network:

[0063] A stainless steel base mesh with a 270-mesh aperture and a diameter of 40mm is selected.

[0064] (3) Preparation of the dynamic cathode film:

[0065] Dynamic membranes were prepared using vacuum filtration. A stainless steel mesh was fixed in a 40mm diameter Buchner funnel using conventional methods. The Buchner funnel was then fixed to the mouth of a vacuum filtration flask. The flask was filled with water until the liquid level was slightly higher than the metal mesh. At this point, the pre-coating agent mixture prepared in step (1) was added to the funnel above the metal mesh. Water was pumped from the filtration flask to control the membrane flux at 160 L / (m²). 2 ·h), filter for 30 min to obtain the cathode dynamic membrane.

[0066] Example 2: A method for preparing a cathode dynamic membrane for organic wastewater treatment

[0067] (1) Preparation of the pre-coating agent mixture solution:

[0068] The activated carbon with a particle size of 0.075-0.090 mm and the activated carbon with a particle size of 0.106-0.125 mm were mixed in a mass ratio of 3:1, water was added to prepare a pre-coating agent solution of 50 mg / L, and micro-bubble aeration was performed for 3 min to obtain the pre-coating agent mixture solution.

[0069] (2) Selection of the dynamic membrane base net:

[0070] A stainless steel base net with a pore size of 200 mesh and a diameter of 40 mm was selected.

[0071] (3) Preparation of the cathode dynamic membrane:

[0072] The dynamic membrane was prepared by suction filtration. The stainless steel base net was fixed in a Buchner funnel with a diameter of 40 mm in a conventional manner, the Buchner funnel was fixed on the mouth of the suction filter bottle, the suction filter bottle was filled with water so that the liquid level was slightly higher than the metal base net, and the pre-coating agent mixture solution prepared in (1) was added into the funnel above the metal base net at this time. The water pump was used to pump water in the suction filter bottle, and the membrane flux was controlled at 160 L / (m 2 ·h). The cathode dynamic membrane was obtained after suction filtration for 120 min.

[0073] Example 3: A preparation method of a cathode dynamic membrane for organic wastewater treatment

[0074] (1) Preparation of the pre-coating agent mixture solution:

[0075] The activated carbon with a particle size of 0.063-0.075 mm and the polyaluminum chloride with a particle size of 0.106-0.125 mm were mixed in a mass ratio of 2:1, water was added to prepare a pre-coating agent solution of 300 mg / L, and micro-bubble aeration was performed for 20 min to obtain the pre-coating agent mixture solution.

[0076] (2) Selection of the dynamic membrane base net:

[0077] A stainless steel base net with a pore size of 230 mesh and a diameter of 40 mm was selected.

[0078] (3) Preparation of the cathode dynamic membrane:

[0079] The dynamic membrane was prepared by suction filtration. The stainless steel base net was fixed in a Buchner funnel with a diameter of 40 mm in a conventional manner, the Buchner funnel was fixed on the mouth of the suction filter bottle, the suction filter bottle was filled with water so that the liquid level was slightly higher than the metal base net, and the pre-coating agent mixture solution prepared in (1) was added into the funnel above the metal base net at this time. The water pump was used to pump water in the suction filter bottle, and the membrane flux was controlled at 160 L / (m 2·h), filter for 75 min to obtain the cathode dynamic membrane.

[0080] Example 4: A method for preparing an electrocatalytic anode for organic wastewater treatment

[0081] Immersion electrode substrate:

[0082] A nickel mesh was immersed in a mixed solution of Ni(Ac)2·4H2O, Fe(NO3)3·9H2O, and 2,6-naphthalenedicarboxylic acid tetrahydrate, with a mass ratio of Ni(Ac)2·4H2O, Fe(NO3)3·9H2O, organic ligand 2,6-naphthalenedicarboxylic acid tetrahydrate, and deionized water of 8:2:10:1, to obtain an immersed substrate.

[0083] Preparation of NiFe-MOF electrocatalytic anodes:

[0084] The soaking substrate obtained in step (1) was sealed and reacted at 60°C for 20 h. After cooling, it was ultrasonically cleaned for 1 min and then cleaned with deionized water to obtain the NiFe-MOF electrocatalytic anode.

[0085] Example 5: Application of a cathode dynamic membrane in organic wastewater treatment

[0086] Preparation:

[0087] Wastewater with COD of 4000 mg / L was treated in activated sludge with MLSS of 3800 mg / L for 6 hours; the microbially treated wastewater was then collected.

[0088] Organic wastewater treatment:

[0089] The cathode dynamic membrane from Example 1, which is already connected to a power source, and the electrocatalytic anode prepared in Example 4, which has the same dynamic membrane area, are fixed parallel to each other in a test container. The circular surfaces of the cathode dynamic membrane and the anode are placed perpendicular to the water flow. The wastewater treated by the microorganisms is pumped into the cathode dynamic membrane from the cathode side using a water pump, and the membrane flux is controlled to be 80 L / (m²) within 5 minutes at the start of the test. 2 •h); Collect purified water samples after passing through the electrocatalytic anode.

[0090] The power supply is set to constant voltage mode with a voltage of 2V.

[0091] Example 6: Application of a cathode dynamic membrane in organic wastewater treatment

[0092] Preparation:

[0093] Wastewater with COD of 100 mg / L was treated in activated sludge with MLSS of 4200 mg / L for 6 hours; the microbially treated wastewater was then collected.

[0094] Organic wastewater treatment:

[0095] The cathode dynamic membrane of Example 2 connected with power supply and the electro-catalytic anode prepared in Example 4 were fixed in a test container in parallel, the circular surface of the cathode dynamic membrane and the anode was perpendicular to water flow; the microorganism treated wastewater was pumped from the cathode dynamic membrane part by using a water pump, the membrane flux was controlled to be 20 L / (m 2 ·h) within 5 min at the beginning of the test; the purified water sample passing through the electro-catalytic anode was collected.

[0096] The power supply was set to constant voltage mode, and the voltage was 1.6 V.

[0097] Example 7 Application of a cathode dynamic membrane for organic wastewater treatment in organic wastewater treatment

[0098] Preparation work:

[0099] The COD 8000 mg / L wastewater was treated in the activated sludge with MLSS of 4000 mg / L for 6 h; the microorganism treated wastewater was collected.

[0100] Organic wastewater treatment:

[0101] The cathode dynamic membrane of Example 3 connected with power supply and the electro-catalytic anode prepared in Example 4 were fixed in a test container in parallel, the circular surface of the cathode dynamic membrane and the anode was perpendicular to water flow; the microorganism treated wastewater was pumped from the cathode dynamic membrane part by using a water pump, the membrane flux was controlled to be 150 L / (m 2 ·h) within 5 min at the beginning of the test; the purified water sample passing through the electro-catalytic anode was collected.

[0102] The power supply was set to constant voltage mode, and the voltage was 1.8 V.

[0103] Comparative Example 1

[0104] The difference between this comparative example and Example 1 is only that (1) the pre-coating agent mixed solution is prepared only by using activated carbon with a particle size of 0.053-0.063 mm and polyaluminum chloride; specifically:

[0105] (1) Preparation of the pre-coating agent mixed solution:

[0106] The activated carbon with a particle size of 0.053-0.063 mm and the polyaluminum chloride with a particle size of 0.053-0.063 mm were mixed according to a mass ratio of 1:1, water was added to prepare a pre-coating agent solution with a concentration of 185 mg / L, and micro-bubble aeration was performed for 8 min to obtain the pre-coating agent mixed solution.

[0107] Comparative Example 2

[0108] The difference between the present comparative example and Example 1 is only that (1) the mass ratio of the activated carbon with a particle size of 0.053-0.063 mm and the polyaluminum chloride with a particle size of 0.090-0.106 mm in the preparation of the precoating agent mixture is different, specifically:

[0109] (1) Preparation of the precoating agent mixture:

[0110] The activated carbon with a particle size of 0.053-0.063 mm and the polyaluminum chloride with a particle size of 0.090-0.106 mm were mixed according to a mass ratio of 4:1, water was added to prepare a precoating agent solution of 185 mg / L, and micro-bubble aeration was performed for 8 min to obtain the precoating agent mixture.

[0111] Comparative Example 3

[0112] The difference between the present comparative example and Example 1 is only that (1) the mass ratio of the activated carbon with a particle size of 0.053-0.063 mm and the polyaluminum chloride with a particle size of 0.090-0.106 mm in the preparation of the precoating agent mixture is different, specifically:

[0113] (1) Preparation of the precoating agent mixture:

[0114] The activated carbon with a particle size of 0.053-0.063 mm and the polyaluminum chloride with a particle size of 0.090-0.106 mm were mixed according to a mass ratio of 1:2, water was added to prepare a precoating agent solution of 185 mg / L, and micro-bubble aeration was performed for 8 min to obtain the precoating agent mixture.

[0115] Comparative Example 4

[0116] The difference between the present comparative example and Example 1 is only that (1) the activated carbon with a particle size of 0.106-0.125 mm is also added in the preparation of the precoating agent mixture. Specifically:

[0117] (1) Preparation of the precoating agent mixture:

[0118] The activated carbon with a particle size of 0.053-0.063 mm, the polyaluminum chloride with a particle size of 0.090-0.106 mm, and the activated carbon with a particle size of 0.106-0.125 mm were mixed according to a mass ratio of 1:2:1, water was added to prepare a precoating agent solution of 185 mg / L, and micro-bubble aeration was performed for 8 min to obtain the precoating agent mixture.

[0119] Comparative Example 5

[0120] The difference between the present comparative example and Example 1 is only that (1) the polyaluminum chloride with a particle size of 0.090-0.106 mm in the preparation of the precoating agent mixture is replaced by the polyaluminum chloride with a particle size of 0.125-0.150 mm, specifically:

[0121] (1) Preparation of the pre-coating agent mixture

[0122] The activated carbon with particle size of 0.053-0.063 mm and the polyaluminum chloride with particle size of 0.125-0.150 mm were mixed in a mass ratio of 1:2, water was added to prepare a pre-coating agent solution with a concentration of 185 mg / L, and micro-bubble aeration was performed for 8 min to obtain the pre-coating agent mixture.

[0123] Comparative Example 6

[0124] The difference between this comparative example and Example 5 is that the cathode dynamic membrane prepared in Comparative Example 1 is used to replace the cathode dynamic membrane in Example 1 in the organic wastewater treatment step.

[0125] Comparative Example 7

[0126] The difference between this comparative example and Example 5 is that the cathode dynamic membrane prepared in Comparative Example 2 is used to replace the cathode dynamic membrane in Example 1 in the organic wastewater treatment step.

[0127] Comparative Example 8

[0128] The difference between this comparative example and Example 5 is that the cathode dynamic membrane prepared in Comparative Example 3 is used to replace the cathode dynamic membrane in Example 1 in the organic wastewater treatment step.

[0129] Comparative Example 9

[0130] The difference between this comparative example and Example 5 is that the cathode dynamic membrane prepared in Comparative Example 4 is used to replace the cathode dynamic membrane in Example 1 in the organic wastewater treatment step.

[0131] Comparative Example 10

[0132] The difference between this comparative example and Example 5 is that the cathode dynamic membrane prepared in Comparative Example 5 is used to replace the cathode dynamic membrane in Example 1 in the organic wastewater treatment step.

[0133] Comparative Example 11

[0134] The difference between this comparative example and Example 5 is that a common stainless steel mesh connected to a power source is used as a cathode in the organic wastewater treatment step, which is parallel to the electro-catalytic anode prepared in Example 4 and is fixed at the same height as the electro-catalytic anode in the test container at a distance of 50 mm from the electro-catalytic anode to improve the electro-catalytic effect; the cathode dynamic membrane in Example 1 is still fixed in the original position as a dynamic membrane.

[0135] Comparative Example 12

[0136] The difference between the present comparative example and Example 5 is that, in the organic wastewater treatment step, a common stainless steel mesh connected to a power source is used as a cathode, which is fixed in the test container at the same height as the electrocatalytic anode prepared in Example 4 and at a distance of 50 mm from the electrocatalytic anode to improve the electrocatalytic effect; and the cathode dynamic membrane in Example 1 is replaced with the cathode dynamic membrane in Comparative Example 1, which is fixed at the original position of the cathode dynamic membrane in Example 1 and used as a dynamic membrane.

[0137] II. Test of wastewater quality after treatment

[0138] Since there is no national standard for testing dynamic membranes, the water samples after dynamic membrane treatment are tested to confirm whether the dynamic membrane is running normally. Since industrial wastewater is treated, the turbidity of the effluent is less than 5 NTU, the suspended solids (SS) are not detected (detection limit 4 mg / L), and the effluent flux is required to remain stable.

[0139] The water sample with a turbidity of less than 5 NTU and no suspended solids (SS) (detection limit 4 mg / L) is used as the dynamic membrane formation time; to reduce the test period, the transmembrane pressure difference reaching 10 kPa is considered as membrane clogging, and the time elapsed after the dynamic membrane formation to the membrane clogging is recorded as the running time.

[0140] The turbidity is measured by a 2100Q type portable turbidimeter produced by the American Hashi Company, which meets the International Organization for Standardization Standard "Determination of Turbidity in Water - Colorimetric Method" ISO 7027-2016.

[0141] The determination of suspended solids is carried out in accordance with the national standard "Determination of Suspended Solids in Water - Gravimetric Method" GB 11901-89.

[0142] The purified water samples obtained in Examples 5-7 and Comparative Examples 6-12 are subjected to water quality testing. For the obtained purified water samples, samples are collected every 3 min from the effluent, and after 5 collections; samples are collected every 5 min, and after 5 collections, samples are collected every 30 min until the dynamic membrane is formed; the transmembrane pressure difference is recorded every 12 h.

[0143] The dynamic membrane formation time and running time of the cathode dynamic membrane prepared in each example and comparative example are recorded respectively.

[0144] Table 1 Dynamic membrane formation time and running time of cathode dynamic membrane

[0145]

[0146] As can be seen from Table 1 above, the dynamic membranes of Examples 5-7 prepared by using the dynamic membranes provided by the present application have a significantly shorter formation time (≤12 min) and the longest running time (≥6d 12h) among the examples and comparative examples;

[0147] Comparative Example 6, Comparative Example 7 and Comparative Example 8, however, show a significant decrease in the formation time and running time of the dynamic membranes due to the use of the dynamic membranes (Comparative Examples 1 and 2) not prepared by using the particle size and mass amount provided by the present application. This is because the use of the too fine pre-coated agent material in Comparative Example 6 results in a denser dynamic membrane, which, although showing a good formation time of the dynamic membrane, hinders the function of the dynamic membrane as a cathode due to the use of the same as the cathode, and at the same time, the filtration of impurities in the microbial treatment wastewater results in a rapid decrease in the membrane flux. In Comparative Example 7, the use of the excessive small particle size pre-coated agent results in a similar situation as in Comparative Example 6, but the use of the pre-coated agent with a larger particle size in Comparative Example 7 can result in a better effect of the dynamic membrane as a cathode on the improvement of the membrane flux, which prolongs the running time compared to Comparative Example 6, but correspondingly increases the formation time of the dynamic membrane. In Comparative Example 8, the use of the excessive large particle size pre-coated agent results in a loose structure of the dynamic membrane, which greatly increases the formation time of the dynamic membrane, but due to the unreasonable addition amount, the uniformity of the composition of the dynamic membrane decreases, which more easily leads to the occurrence of membrane clogging and reduces the running time, but the addition of the large particle size pre-coated agent significantly prolongs the running time compared to Comparative Example 6.

[0148] In Comparative Example 9, three particle sizes of pre-coated agent are used, and the newly added particle size of the pre-coated agent is large, which results in an uneven deposition of the pre-coated agent during the formation of the dynamic membrane, and the dynamic membrane shows poor performance in the formation time and running time.

[0149] In Comparative Example 10, the particle size of the pre-coated agent with a larger size is increased, which results in an obvious delamination of the pre-coated agent when passing through the dynamic membrane base web with a smaller size during the preparation of the dynamic membrane, and the synergistic effect of the particles of different particle sizes decreases, which also shows a significant increase in the formation time and a decrease in the running time.

[0150] Comparative Examples 11 and 12 are comparative tests on the performance of different dynamic membranes as cathodes, and the results show that the formation time of the dynamic membrane is shortened compared to the case of being powered on, but the running time is significantly decreased. It is shown that the use of the dynamic membrane as a cathode can effectively improve the running time of the dynamic membrane, but can increase the formation time of the dynamic membrane. At the same time, the comparison of Comparative Examples 11 and 12 shows that the dynamic membrane prepared by using two particle sizes has a greater effect on the running time of the cathode, which indicates that the dynamic membrane prepared by using two particle sizes is more suitable for the preparation of the dynamic membrane cathode with the cathode material to improve the service life of the dynamic membrane.

[0151] It should be pointed out finally that the above is only used to explain the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A method for preparing a cathode dynamic membrane for organic wastewater treatment, characterized in that, Includes the following steps: (1) Mix the pre-coating agent with water to obtain a pre-coating agent mixture; (2) The pre-coating agent mixture obtained in step (1) is uniformly passed through the dynamic membrane base network to form a film, thereby obtaining the cathode dynamic membrane; The pre-coating agent in step (1) includes component 1 and component 2; component 1 is powdered activated carbon with a particle size of 0.053-0.090 mm, and component 2 is powdered activated carbon or polyaluminum chloride with a particle size of 0.090-0.125 mm. The mass ratio of component 1 to component 2 is 1-3:

1.

2. The preparation method according to claim 1, characterized in that: Component 1 is powdered activated carbon with a particle size of 0.063-0.075 mm, and component 2 is powdered activated carbon or polyaluminum chloride with a particle size of 0.106-0.125 mm. The mass ratio of component 1 to component 2 is 2:

1.

3. The preparation method according to claim 2, characterized in that: The pre-coating agent comprises 0.063-0.075mm activated carbon and 0.106-0.125mm polyaluminum chloride; the mass ratio of the 0.063-0.075mm activated carbon to the 0.106-0.125mm polyaluminum chloride is 2:

1.

4. The preparation method according to claim 1, characterized in that: The concentration of the pre-coating agent in the pre-coating agent mixture in step (1) is 50-300 mg / L.

5. The preparation method according to claim 1, characterized in that: The mixing method described in step (1) is as follows: microbubble aeration for 3-20 min or magnetic stirrer stirring: stir at 300 r / min for 0.5-1.0 min, then stir at 150 r / min for 3-10 min, then stir at 70 r / min for 8-20 min.

6. The preparation method according to claim 1, characterized in that: The dynamic membrane base mesh mentioned in step (2) includes at least one of stainless steel mesh, titanium mesh, nickel mesh and copper mesh; the aperture range of the dynamic membrane base mesh mentioned in step (2) is 200-270 mesh.

7. The preparation method according to claim 1, characterized in that: The film formation time in step (2) is 30-120 min.

8. The cathode dynamic membrane for organic wastewater treatment prepared by any of the preparation methods described in claims 1-7.

9. The application of the cathode dynamic membrane for organic wastewater treatment prepared by any of the preparation methods described in claims 1-7 in the treatment of organic wastewater.

10. The method for treating organic wastewater using the cathode dynamic membrane according to claim 8, characterized in that: Includes the following steps: (1) The wastewater is treated with activated sludge to obtain pretreated wastewater; (2) The pretreated wastewater obtained in step (1) is treated with the cathode dynamic membrane to obtain intermediate treated wastewater; (3) Electrocatalytic oxidation is performed on the intermediate wastewater obtained in step (2) to obtain purified water.

11. The method according to claim 10, characterized in that: The concentration of organic pollutants in the wastewater mentioned in step (1) is: COD 60-8000 mg / L.

12. The method according to claim 10, characterized in that: The cathode dynamic membrane treatment in step (2) includes the step of using cathode dynamic membrane filtration.

13. The method according to claim 10, characterized in that: The electrocatalytic oxidation in step (3) uses the cathode dynamic membrane described in step (2) as the cathode and the metal-organic framework electrode as the anode.

14. The method according to claim 13, characterized in that: The metal-organic framework electrode is a NiFe bimetallic metal-organic framework electrode.

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