A highly efficient seawater treatment method

Abstract

The present invention provides a highly efficient seawater treatment method, belonging to the technical field of seawater treatment. Specifically, an MBR membrane is prepared using polyethersulfone as a main material through a phase conversion method. The obtained MBR membrane has uniform pore size, good surface hydrophilicity, strong pollution resistance, good antibacterial properties, good adhesion between the support layer and the separation layer, and a long service life. The MBR membrane is used for seawater treatment, which can not only effectively remove organic matter such as COD and BOD, ammonia nitrogen, heavy metal ions, etc. in seawater, but also the seawater treatment method is mature, stable, and has good controllability, and is suitable for large-scale industrial applications.

Description

Technical Field

[0001] The invention belongs to the technical field of seawater treatment, and in particular relates to a high-efficiency seawater treatment method. Background Art

[0002] Seawater is a vital resource, but it is currently polluted by aquaculture wastewater, industrial wastewater discharge, oil spills, and other sources. Therefore, efficient seawater treatment is necessary to achieve sustainable utilization.

[0003] MBR (membrane bioreactor) technology is a widely used water treatment technology. It combines the ultrafiltration membrane modules used in membrane separation technology with bioreactors used in biological wastewater treatment to form a treatment system. Membrane materials are the core components of MBR technology. Currently, two types of membrane materials are used in MBR: hollow fiber and flat sheet. The main flat sheet MBR membrane materials on the market include polyvinylidene fluoride, polyethersulfone, polysulfone, and polyvinyl chloride. Polyethersulfone exhibits excellent thermal stability, chemical stability, acid and alkali resistance, corrosion resistance, and film-forming properties, as well as outstanding mechanical properties. It has been widely used in various fields, including electronics, aerospace, medical treatment, seawater desalination, and wastewater treatment. However, polyethersulfone membranes have the disadvantages of being highly hydrophobic and having poor fouling resistance. On the one hand, membrane fouling can reduce water flux and wastewater treatment efficiency. On the other hand, to minimize the impact of membrane fouling on wastewater treatment, the MBR membranes must be frequently cleaned, which damages the membrane surface, shortens the membrane life, and increases operating costs with the use of cleaning agents. Therefore, the current application of polyethersulfone membranes is significantly limited.

[0004] Therefore, there is an urgent need to improve the existing polyethersulfone MBR membrane to make up for the defects of the existing technology. Summary of the Invention

[0005] In view of this, the present invention provides a high-efficiency seawater treatment method, which filters and separates, and not only has excellent seawater treatment effect, but also has good fouling resistance, strong antibacterial properties and high peeling strength of the MBR membrane.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0007] A high-efficiency seawater treatment method, comprising:

[0008] S1: mechanical filtration;

[0009] S2: adding aluminum flocculants to the seawater for flocculation and precipitation;

[0010] S3: adjusting the pH of the seawater to 5.5-6 with a carbonated water solution, and filtering and separating the seawater using a membrane module based on the above-mentioned MBR membrane at a pressure of 0.1-0.5 MPa;

[0011] S4: adding disinfectant to the seawater for disinfection to achieve efficient treatment of the seawater;

[0012] Furthermore, the aluminum flocculant is a mixture of polyaluminum chloride and calcium hydroxide, and the mixing mass ratio is 1:0.1 to 0.15.

[0013] Furthermore, the weight ratio of the aluminum flocculant to the seawater is 0.05-0.2:1000.

[0014] Furthermore, the disinfectant is an inorganic chlorine-containing disinfectant, specifically at least one of hypochlorous acid, hypochlorite, liquid chlorine and chloramine; the weight ratio of the disinfectant to the seawater is 0.3-1:1000.

[0015] The present invention provides the above-mentioned efficient seawater treatment method, which first separates the seawater through mechanical filtration, then uses an aluminum-based flocculant to flocculate and precipitate suspended matter, ammonia nitrogen, etc. in the seawater, thereby achieving preliminary treatment of the seawater. Then, an MBR membrane module is used for separation and filtration under acidic conditions to achieve efficient treatment of the seawater. Not only can organic matter such as COD and BOD, ammonia nitrogen, heavy metal ions, etc. in the seawater be effectively removed, but the seawater treatment method is mature, stable, and has good controllability, making it suitable for large-scale industrial applications.

[0016] Furthermore, the MBR membrane is prepared by the following method:

[0017] 1) Material mixing: polyethersulfone, oxidized sodium alginate, 6-hydroxymethylsulfamethazine modified wood ash, pore-forming agent and solvent are mixed and stirred at high speed to obtain a mixed material;

[0018] 2) Preparation of casting solution: Mixing at high temperature to form a uniform casting solution and letting it stand for degassing;

[0019] 3) Preparation of MBR membrane by phase inversion method: The casting liquid is scraped onto a non-woven fabric support layer to form an initial membrane, which is then quickly immersed in a coagulation bath to undergo phase inversion to obtain an MBR membrane.

[0020] The present invention provides an MBR membrane prepared by the above-mentioned method. The MBR membrane has a two-layer membrane structure. The bottom layer is a non-woven fabric support layer, which provides the MBR membrane with high mechanical strength to withstand the shearing effect of flowing water and operating pressure during seawater treatment. The surface layer is a separation layer made of polyethersulfone as the membrane material. The membrane has uniform pore size, high surface hydrophilicity, strong fouling resistance, excellent antibacterial properties, and high seawater treatment efficiency, which compensates for the defects of existing polyethersulfone ultrafiltration membranes. In addition, the separation layer has good adhesion to the support layer, is not easy to fall off during use, and has a long service life.

[0021] Furthermore, during the material mixing process, the wood ash is obtained by burning waste of any one or two or more of the following crops: rice, wheat, corn, sorghum, and buckwheat.

[0022] Furthermore, during the material mixing process, the molecular weight of the polyethersulfone is 30,000 to 60,000.

[0023] Furthermore, during the material mixing process, the pore-forming agent is polyvinyl pyrrolidone (PVP), specifically any one of PVPK17, PVPK30, and PVPK90.

[0024] Furthermore, during the material mixing process, the solvent is dimethylformamide or dimethylacetamide.

[0025] Furthermore, during the material mixing process, the components are calculated by weight as follows: 15 to 22 parts by weight of polyethersulfone, 1 to 2.5 parts by weight of oxidized sodium alginate, 0.5 to 0.8 parts by weight of 6-hydroxymethylsulfonamide modified wood ash, 5 to 8 parts by weight of pore-forming agent, and 70 to 80 parts by weight of solvent.

[0026] Furthermore, during the material mixing process, 6-hydroxymethylsulfamethazine modified wood ash is prepared by the following method:

[0027] Grind and sieve the wood ash, soak it in a mixed aqueous solution of citric acid and oxalic acid for 0.5 to 3 hours, take it out and wash it with water until it is neutral, then ultrasonically disperse it in water, add epoxy silane coupling agent and stir to react for 2 to 6 hours, then add 6-hydroxymethylsulfonamide and p-aminobenzoic acid, stir at 40 to 50°C for 3 to 8 hours, filter, wash with water and dry to obtain the product.

[0028] Preferably, in the mixed aqueous solution of citric acid and oxalic acid, the mass percentages of citric acid and oxalic acid are 8-15% and 1-2%, respectively.

[0029] Preferably, the epoxysilane coupling agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane or β-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

[0030] Preferably, the mass ratio of the wood ash to the epoxy silane coupling agent is 1:0.8-2.

[0031] Preferably, the mass ratio of the wood ash to 6-hydroxymethylsulfamethazine is 1:0.2-0.34. Modified wood ash, a residue from burning rice and wheat, is prepared through a two-step modification process using an epoxy silane coupling agent and 6-hydroxymethylsulfamethazine. The surface of the modified wood ash contains certain highly reactive groups, which can improve its affinity with materials such as polyethersulfone, helping to form a highly connected microporous structure with uniform pore size. The hydrophilic groups present on the surface give the membrane surface a high degree of hydrophilicity, enhancing its pollution resistance and compensating for the defects of existing polyethersulfone membranes. It is effective in removing organic matter such as COD and ammonia nitrogen in seawater, and improves the removal of heavy metal ions. Wood ash also has certain antibacterial properties. Modification with 6-hydroxymethylsulfamethazine can further enhance its antibacterial properties, thereby further improving the antibacterial properties of the MBR membrane. In addition, the addition of 6-hydroxymethylsulfamethazine-modified wood ash can also improve the adhesion between the separation layer and the bottom layer, resulting in high peel strength, which can reduce the shedding of the separation layer during use of the MBR membrane and prolong its service life.

[0032] Furthermore, the oxidized sodium alginate is prepared by the following method:

[0033] Take sodium alginate and prepare it into an aqueous solution with a mass percentage of 2-5%, add sodium periodate with a mass of 0.2-0.5 times that of the sodium alginate to oxidize for 3-8 hours, then add ethylene glycol and sodium chloride to terminate the oxidation reaction, then add ethanol to precipitate it, filter it, redissolve it with water, precipitate it with ethanol, filter it, repeat the operation several times and freeze-dry it.

[0034] Preferably, during the preparation of the casting solution, the temperature is 85-100°C.

[0035] Preferably, during the preparation of the casting solution, the standing time is 8 to 24 hours.

[0036] Preferably, in the process of preparing the MBR membrane by the phase inversion method, the non-woven fabric is a polypropylene non-woven fabric with a thickness of 200 to 400 μm.

[0037] Preferably, in the process of preparing the MBR membrane by the phase inversion method, the thickness of the initial membrane is 80 to 150 μm.

[0038] Preferably, during the phase inversion method for preparing an MBR membrane, the coagulation bath is an aqueous solution containing 4-6 wt% isopropyl alcohol and 0.2-0.5 wt% methoxypolyethylene glycolamine, and the temperature is 5-10°C. Using an aqueous solution containing isopropyl alcohol and methoxypolyethylene glycolamine as a coagulation bath helps the MBR membrane form a more uniform microporous structure. This may be because, compared to adding only isopropyl alcohol, adding a small amount of methoxypolyethylene glycolamine to the coagulation bath can, to a certain extent, improve the affinity between the casting solution and the coagulation bath. The coagulation bath can slowly and comprehensively penetrate into the interior of the membrane, more evenly contacting the polymer-rich phase, reducing the diffusion gap between the upper and lower surfaces of the membrane, reducing the formation of finger-like pores or bubble-like macropores, thereby improving the uniformity of pore size and improving seawater treatment efficiency.

[0039] The present invention adopts the above method to prepare an MBR membrane using polyethersulfone as the main material through a phase inversion method. The obtained MBR membrane has uniform pore size, good surface hydrophilicity, strong pollution resistance, a flux recovery rate of up to 91.8%, and antibacterial rates against Escherichia coli and Staphylococcus aureus of 91.8% and 90.2%, respectively. It has good antibacterial properties, good adhesion between the support layer and the separation layer, and a long service life.

[0040] The present invention also provides the use of the MBR membrane prepared by the above method in seawater treatment, which includes treating seawater aquaculture wastewater, heavy metal-contaminated seawater or petroleum-contaminated seawater.

[0041] The present invention also provides the use of 6-hydroxymethylsulfamethazine modified plant ash in improving the anti-pollution performance and anti-stripping performance of the MBR membrane.

[0042] The present invention also provides the use of 6-hydroxymethylsulfamethazine modified plant ash in improving the seawater treatment effect of MBR membrane.

[0043] As a further improvement to the technical solution of the present invention, 5-benzyl-2-furoic acid and epoxy p-peucedanum ether are also added to the flocculant used during the flocculation and precipitation process. Specifically, the flocculant is a mixture of polyaluminum chloride, calcium hydroxide, 5-benzyl-2-furoic acid, and epoxy p-peucedanum ether in a mass ratio of 1:0.1-0.15:0.04-0.06:0.01-0.03. The inventors unexpectedly discovered that adding a small amount of 5-benzyl-2-furoic acid and epoxy p-peucedanum ether to the flocculant can not only further enhance the flocculant's removal of heavy metal ions from seawater, but also improve the flocculation and precipitation of antibiotics, further enhancing the seawater treatment effect.

[0044] The present invention provides a highly efficient seawater treatment method. Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The MBR membrane provided by the present invention is produced by a mature phase inversion process using polyethersulfone, oxidized sodium alginate, and 6-hydroxymethylsulfamethazine modified wood ash as raw materials. It has good pollution resistance and antibacterial properties, good separation effect, and strong adhesion between the separation layer and the support layer. It is not easy to fall off during long-term use and has a long service life. It can be used to treat marine aquaculture wastewater, heavy metal-contaminated seawater, or oil-contaminated seawater.

[0046] 2. 6-Hydroxymethylsulfamethazine modified plant ash is added to the MBR membrane as a modifier. 6-Hydroxymethylsulfamethazine modified plant ash has high hydrophilicity and antibacterial properties, which can make up for the poor pollution resistance of the MBR membrane, improve the pollution resistance and antibacterial properties, and increase the anti-peeling strength between the separation layer and the support layer, thereby increasing the service life;

[0047] 3. When preparing MBR membranes using the immersion precipitation phase conversion method, using an aqueous solution containing isopropyl alcohol and methoxypolyethylene glycol amine as a coagulation bath can reduce the formation of finger-like pores and bubble-like macropores and improve the seawater treatment effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the FTIR spectrum of 6-hydroxymethylsulfamethazine modified plant ash; in the figure, a represents unmodified plant ash, and b represents modified plant ash;

[0049] Figure 2 1 is a SEM image of an MBR membrane; (1) in the figure represents the MBR membrane prepared in Example 1, and (2) represents the MBR membrane prepared in Example 8;

[0050] Figure 3 This is a schematic diagram of the anti-pollution performance test results of the MBR membrane; in the figure, A represents the pure water flux before pollution, and B represents the pure water flux after pollution;

[0051] Figure 4 This is a schematic diagram of the antibacterial performance test results of the MBR membrane; in the figure, C represents the antibacterial rate against Escherichia coli, and D represents the antibacterial rate against Staphylococcus aureus;

[0052] Figure 5 It is a schematic diagram of the test results of the anti-stripping performance of the MBR membrane. DETAILED DESCRIPTION

[0053] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments. Any improvement or substitution based on the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0054] Example 1:

[0055] This embodiment provides a method for preparing an MBR membrane, comprising the following steps:

[0056] 1) Material mixing: 18 parts by weight of polyethersulfone (molecular weight 50,000), 2 parts by weight of oxidized sodium alginate, 0.6 parts by weight of 6-hydroxymethylsulfadimethazine modified plant ash, 6 parts by weight of PVPK30 and 75 parts by weight of dimethylacetamide were mixed and stirred at high speed to obtain a mixed material;

[0057] 2) Preparation of casting solution: The mixture prepared in step 1) was stirred at 95° C. to form a uniform casting solution, and then allowed to stand for 16 hours to degas;

[0058] 3) Preparation of MBR membrane by phase inversion method: The casting solution was scraped onto a 300 μm thick polypropylene non-woven fabric to form an initial film of 120 μm thickness. The film was then rapidly solidified in a coagulation bath at 8°C containing 5 wt% isopropanol and 0.35 wt% methoxypolyethylene glycolamine. The film was removed after 12 h, washed with water, and freeze-dried to obtain the MBR membrane.

[0059] The oxidized sodium alginate is prepared by the following method:

[0060] Take 2g of sodium alginate and prepare a 4% aqueous solution by mass. Add 0.8g of sodium periodate and oxidize in the dark for 6h. Then add 1mL of ethylene glycol and 1.5g of NaCl to terminate the oxidation reaction for 30min. Add 30mL of ethanol to precipitate it, filter it with suction, redissolve it with water, precipitate it with ethanol, filter it with suction, repeat the operation 3 times and freeze-dry it.

[0061] The 6-hydroxymethylsulfamethazine modified plant ash is prepared by the following method:

[0062] The ash is ground and passed through a 600-mesh sieve, and then soaked in a 10-times-by-weight mixed aqueous solution of citric acid and oxalic acid for 2 hours, wherein the mass percentages of citric acid and oxalic acid are 12% and 1.6% respectively. The ash is filtered and washed with water until neutral, and then ultrasonically dispersed in 10-times-by-weight water. 3-(2,3-epoxypropoxy)propyltrimethoxysilane in an amount of 1.6 times by weight of the ash is added, stirred and reacted for 4 hours, and then 6-hydroxymethylsulfonamide in an amount of 0.28 times by weight of the ash is added, and p-aminobenzoic acid in an amount of 0.02 times by weight of the ash is added. The mixture is stirred at 45° C. for 6 hours, filtered, washed with water and dried to obtain the product.

[0063] Example 2:

[0064] This embodiment provides another method for preparing an MBR membrane, and the steps are basically the same as those in Example 1, except that, during the preparation of 6-hydroxymethylsulfamethazine-modified wood ash, the mass ratio of wood ash to 6-hydroxymethylsulfamethazine is 1:0.1.

[0065] Example 3:

[0066] This embodiment provides another method for preparing an MBR membrane, and the steps are basically the same as those in Example 1, except that, during the preparation of 6-hydroxymethylsulfamethazine-modified wood ash, the mass ratio of wood ash to 6-hydroxymethylsulfamethazine is 1:0.2.

[0067] Example 4:

[0068] This embodiment provides another method for preparing an MBR membrane, and the steps are basically the same as those in Example 1, except that, during the preparation of 6-hydroxymethylsulfamethazine-modified wood ash, the mass ratio of wood ash to 6-hydroxymethylsulfamethazine is 1:0.34.

[0069] Example 5:

[0070] This embodiment provides another method for preparing an MBR membrane, and the steps are basically the same as those in Example 1, except that, during the preparation of 6-hydroxymethylsulfamethazine-modified wood ash, the mass ratio of wood ash to 6-hydroxymethylsulfamethazine is 1:0.4.

[0071] Example 6:

[0072] This embodiment provides another method for preparing an MBR membrane. The steps are basically the same as those in Example 1, except that 3-(2,3-epoxypropoxy)propyltrimethoxysilane-modified wood ash is used instead of 6-hydroxymethylsulfamethazine-modified wood ash. The 3-(2,3-epoxypropoxy)propyltrimethoxysilane-modified wood ash is prepared by the following method:

[0073] The wood ash is ground and passed through a 600-mesh sieve, and then soaked in a 10-fold by weight mixed aqueous solution of citric acid and oxalic acid for 2 hours, wherein the mass percentages of citric acid and oxalic acid are 12% and 1.6% respectively. The mixture is filtered and washed with water until neutral, and then ultrasonically dispersed in 10-fold by weight water. 3-(2,3-epoxypropoxy)propyltrimethoxysilane in an amount of 1.6 times the mass of the wood ash is added, stirred and reacted for 4 hours, filtered, washed with water, and dried to obtain the product.

[0074] Example 7:

[0075] This embodiment provides another method for preparing an MBR membrane. The steps are basically the same as those in Example 1, except that unmodified wood ash is used instead of 6-hydroxymethylsulfamethazine-modified wood ash.

[0076] Example 8:

[0077] This embodiment provides another method for preparing an MBR membrane. The steps are basically the same as those in Example 1, except that the coagulation bath is a 5 wt % isopropanol aqueous solution, i.e., no methoxypolyethylene glycolamine is added.

[0078] Test Example 1:

[0079] Infrared characterization of 6-hydroxymethylsulfamethazine modified wood ash:

[0080] The FTIR spectrum of the wood ash before and after modification in Example 1 was characterized by Fourier attenuated total reflection infrared (MAGNA-560, Nicolet, USA). Figure 1 shown.

[0081] Figure 1 FTIR images of plant ash before and after modification, a represents unmodified plant ash, b represents modified plant ash; Figure 1 It can be seen that curve a is at 1090cm -1 , 735cm -1 There is an obvious characteristic peak near it, which is attributed to CO3 2- The characteristic peak of curve a is 1021cm -1 , 1100cm -1 The antisymmetric stretching vibration peak of Si-O-Si appears near the surface, indicating that 3-(2,3-epoxypropyloxy)propyltrimethoxysilane is successfully grafted onto the surface of the plant ash. Curve b is still at 1610 cm -1 、1504cm -1 、1450cm -1 The characteristic peak of benzene ring skeleton appears near 1152cm -1 The stretching vibration of sulfonamide appeared nearby, indicating that 6-hydroxymethylsulfadimethazine was successfully grafted onto the surface of wood ash.

[0082] Test Example 2:

[0083] Morphological characterization of MBR membrane:

[0084] The cross-sectional morphology of the MBR membranes prepared in Examples 1 and 8 was characterized using a scanning electron microscope (NovaNanoSEM, FEI Company, USA). Figure 2 shown.

[0085] Figure 2 is a SEM image of the MBR membrane, in which (1) represents the MBR membrane prepared in Example 1, and (2) represents the MBR membrane prepared in Example 8; Figure 2It can be seen that the MBR membrane shown in (1) has a sponge-like pore structure with relatively uniform pore size and no finger-like or bubble-like macropores, while the MBR membrane shown in (2) also has two pore structures: sponge-like pores and irregular macropores, and the pore size is less uniform than that of (1). According to the above results, in the process of preparing MBR membranes by the phase inversion method, adding methoxypolyethylene glycol amine to the coagulation bath helps to inhibit the formation of finger-like pores or bubble-like macropores and improve the uniformity of pore size. Although the disappearance of macropores slightly reduces the pure water flux of the membrane, the separation effect is improved, and it is not easy to be compressed during use, and the service life is extended.

[0086] Test Example 3:

[0087] Anti-pollution performance:

[0088] The flux recovery rate after membrane fouling was used to characterize the anti-fouling performance. Specifically, bovine serum albumin (BSA) was used as the pollutant. The pure water flux before and after the contamination and cleaning of the MBR membranes in Examples 1 to 7 were tested. The operating pressure during the test was 0.1 MPa, and the flux recovery rate was calculated: Flux recovery rate = J w2 / J w1 ×100%; where J w2 Represents the change in pure water flux after pollution, J w1 represents the pure water flux before contamination;

[0089] The measured results are as follows Figure 3 shown.

[0090] Figure 3 Schematic diagram of the anti-pollution performance test results of the MBR membrane; in the figure, A represents the pure water flux before pollution, and B represents the pure water flux after pollution; Figure 3 It can be seen that the pure water flux of the MBR membrane prepared in Example 1 before and after pollution is 461.5 L·m -2 ·h -1 、386.9L·m -2 ·h -1, the flux recovery rate is 95.8%, and the high flux recovery rate indicates that the pollution resistance of the MBR membrane is excellent; the changes in the pure water flux of the MBR membranes obtained in Examples 2 to 5 before and after pollution show that with the increase of the amount of 6-hydroxymethylsulfonamide added in the preparation process of 6-hydroxymethylsulfonamide-modified wood ash, the degree of modification of the wood ash is higher, more hydrophilic groups are introduced, the better the hydrophilicity of the obtained MBR membrane, the higher the flux recovery rate, and the better the pollution resistance. Therefore, the flux recovery rates of Examples 4 and 5 are slightly higher than those of Example 1, but with the increase of the amount of 6-hydroxymethylsulfonamide added in the preparation process of 6-hydroxymethylsulfonamide-modified wood ash, the higher the degree of modification of the wood ash, the ... With the increase of the degree of modification, the introduced high-activity groups increase the cross-linking degree of the membrane material, resulting in a decrease in the pore size. This may be the reason why the pure water flux of Examples 4 and 5 is slightly lower than that of Example 1; the pure water flux of the MBR membrane obtained in Examples 6 and 7 is significantly lower than that of Example 1, and the pure water flux before and after pollution changes greatly, and the flux recovery rate is significantly lower than that of Example 1. It can be seen that wood ash modified with epoxy silane coupling agent and then added to the MBR membrane can improve the pollution resistance of the membrane, and the modification treatment with 6-hydroxymethylsulfonamide can further improve the pollution resistance of the membrane.

[0091] Test Example 4:

[0092] Antimicrobial properties:

[0093] The shaking flask method was used, with Escherichia coli and Staphylococcus aureus as indicator bacteria, and the antibacterial ability of the membrane was evaluated based on the inhibition rate. Specifically, the bacterial solution was cultured to 1×10 6 CFU / mL, 0.1mL of bacterial solution was added to PBS buffer, and the membranes prepared in Examples 1 to 7 were cut into 5mm×5mm sizes as the test group. After shaking culture at 37°C for 18 hours, the bacterial solution was diluted according to a 10-fold dilution factor and the viable bacteria were counted using the pour plate method. No membrane was added as the blank control group. The antibacterial rate was calculated as follows: Antibacterial rate = (1-number of colonies on the test group plate / number of colonies on the blank control group plate) × 100%. The measured results are as follows Figure 4 shown.

[0094] Figure 4 The antibacterial performance test results of MBR membranes are shown in Figure 2. In the figure, C represents the antibacterial rate against Escherichia coli, and D represents the antibacterial rate against Staphylococcus aureus. Figure 4 It can be seen that unmodified wood ash is added to the MBR membrane of Example 7, and the antibacterial property of the wood ash gives the MBR membrane a certain antibacterial property. The antibacterial rates of Examples 6 and 7 are comparable, indicating that the modification treatment of wood ash with a silane coupling agent has no obvious effect on enhancing its antibacterial property. The antibacterial properties of Examples 1 to 5 are significantly higher than those of Example 7. It can be seen that the modification treatment of wood ash with 6-hydroxymethylsulfamethazine helps to improve its antibacterial property, and the higher the degree of modification of the wood ash, the better the antibacterial property.

[0095] Test Example 5:

[0096] Peel strength:

[0097] The MBR membranes prepared in Examples 1 to 7 were tested using a universal tensile testing machine. The results are as follows: Figure 5 shown.

[0098] Figure 5 It indicates the peeling strength test result between the separation layer and the base layer of the MBR membrane, such as Figure 5 As shown in the figure, compared with the addition of unmodified wood ash (Example 7), the anti-peel strength between the separation layer and the support layer of the MBR membrane obtained by adding the modified wood ash in Examples 1 to 6 is significantly increased, which shows that the modification of wood ash can increase the anti-peel strength of the MBR membrane. This may be because highly reactive groups are introduced into the modified wood ash, which increases the chemical bonding and hydrogen bonding between the separation layer and the support layer, thereby improving the anti-peel performance and extending the service life; the anti-peel strength of the MBR membrane obtained in Examples 1 to 5 is higher than that in Example 6. It can be seen that the modification of wood ash with 6-hydroxymethylsulfamethazine can further improve the anti-peel performance of the membrane material.

[0099] Example 9:

[0100] This embodiment provides a method for efficiently treating seawater, comprising:

[0101] S1: mechanical filtration;

[0102] S2: adding an aluminum flocculant to the seawater for flocculation and precipitation; the flocculant is a mixture of polyaluminum chloride and calcium hydroxide in a mass ratio of 1:0.12, and the weight ratio of the aluminum flocculant to the seawater is 0.1:1000;

[0103] S3: adjusting the pH of seawater to 5.8 with a mixed aqueous solution containing 12 wt% sodium bicarbonate and 3.5 wt% carbonic acid, and filtering and separating the seawater using a membrane module based on the MBR membrane prepared in Example 1 at a pressure of 0.3 MPa;

[0104] S4: Add hypochlorous acid to the seawater for disinfection, with the weight ratio of disinfectant to seawater being 0.5:1000, to achieve efficient treatment of the seawater.

[0105] Example 10:

[0106] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of embodiment 9, except that a membrane assembly based on the MBR membrane prepared in embodiment 2 is used for filtration and separation.

[0107] Example 11:

[0108] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of embodiment 9, except that a membrane assembly based on the MBR membrane prepared in embodiment 3 is used for filtration and separation.

[0109] Example 12:

[0110] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of embodiment 9, except that a membrane assembly based on the MBR membrane prepared in embodiment 4 is used for filtration and separation.

[0111] Example 13:

[0112] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of embodiment 9, except that a membrane assembly based on the MBR membrane prepared in embodiment 5 is used for filtration and separation.

[0113] Example 14:

[0114] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of embodiment 9, except that a membrane assembly based on the MBR membrane prepared in embodiment 6 is used for filtration and separation.

[0115] Example 15:

[0116] This embodiment provides another high-efficiency seawater treatment method. The steps are substantially the same as those of Example 9, except that a membrane assembly based on the MBR membrane prepared in Example 7 is used for filtration and separation.

[0117] Example 16:

[0118] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of embodiment 9, except that a membrane assembly based on the MBR membrane prepared in embodiment 8 is used for filtration and separation.

[0119] Example 17:

[0120] This embodiment provides another efficient seawater treatment method. The steps are basically the same as those in Example 9, except that 5-benzyl-2-furoic acid and epoxy peucedanum ether are further added to the flocculant. That is, the flocculant includes: a mixture of polyaluminum chloride, calcium hydroxide, 5-benzyl-2-furoic acid, and epoxy peucedanum ether in a mass ratio of 1:0.12:0.05:0.02.

[0121] Example 18:

[0122] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of embodiment 17, except that the flocculant comprises a mixture of polyaluminum chloride, calcium hydroxide, and 5-benzyl-2-furoic acid in a mass ratio of 1:0.12:0.05.

[0123] Example 19:

[0124] This embodiment provides another efficient seawater treatment method, wherein the steps are substantially the same as those of Example 17, except that the flocculant comprises a mixture of polyaluminum chloride, calcium hydroxide, and epoxy peucedanum ether in a mass ratio of 1:0.12:0.02.

[0125] Test Example 6:

[0126] Seawater treatment effect:

[0127] The water quality of the self-prepared simulated seawater is shown in Table 1 below:

[0128] Table 1 Self-prepared simulated seawater quality

[0129]

[0130] The self-prepared simulated seawater was treated according to the methods described in Examples 9 to 19, and the final effluent water quality was tested. The results are shown in Tables 2 and 3 below.

[0131] Table 2 Treatment effect 1

[0132]

[0133] According to the data in Table 2, Example 9 uses the MBR membrane prepared in Example 1 to treat seawater, and its COD, BOD, ammonia nitrogen, Cu 2+ The removal rates of COD, BOD, ammonia nitrogen and metal ions were 99.2%, 98.9%, 92.1% and 78.7% respectively, and the treatment effect was good. It can be seen from Examples 9 to 15 that the combined application of epoxy silane coupling agent and 6-hydroxymethylsulfonamide modified plant ash is more conducive to improving the removal effect of COD, BOD, ammonia nitrogen and metal ions, and as the degree of plant ash modification increases, the seawater treatment effect is better. This should be the result of the combined effect of the pore structure, surface hydrophilicity and surface active groups of the membrane; in Example 16, the removal of COD, BOD, ammonia nitrogen, Cu 2+ The removal rates of Example 9 were lower than those of Example 9, which was mainly due to the presence of macroporous structure in the MBR membrane prepared in Example 8.

[0134] Table 3 Treatment effect 2

[0135]

[0136] From the results in Table 3, it can be seen that compared with Example 9, Example 17 adds a certain amount of 5-benzyl-2-furoic acid and epoxy pre-peucedanum ether to the flocculant, which has a better effect on Cu 2+ The removal rate of Cu in seawater was significantly improved, while in Example 18 and Example 19, only 5-benzyl-2-furoic acid or epoxy pre-peucedanum ether was added to the flocculant. 2+ The removal rates of 5-benzyl-2-furoic acid and epoxide p-butyl ether in the flocculant are lower than those in Example 17, which shows that the simultaneous addition of 5-benzyl-2-furoic acid and epoxide p-butyl ether in the flocculant has a certain synergistic effect, which helps to improve the removal efficiency of heavy metal ions and ciprofloxacin in seawater.

[0137] The above content is a further detailed description of the present invention in conjunction with specific embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A highly efficient seawater treatment method, characterized in that: The method comprises: S1: mechanical filtration; S2: adding aluminum flocculants to the seawater for flocculation and precipitation; S3: Adjust the pH of seawater to 5.5-6 with a mixed aqueous solution of sodium bicarbonate and carbonic acid, and filter and separate using an MBR membrane-based membrane module at a pressure of 0.1-0.5 MPa; S4: adding disinfectant to the seawater for disinfection to achieve efficient treatment of the seawater; The MBR membrane was prepared by the following method: 1) Material mixing: polyethersulfone, oxidized sodium alginate, 6-hydroxymethylsulfamethazine modified wood ash, pore-forming agent and solvent are mixed and stirred at high speed to obtain a mixed material; 2) Preparation of casting solution: Mix at 85-100°C to form a uniform casting solution and let it stand for degassing; 3) Preparation of MBR membrane by phase inversion method: The casting liquid is scraped onto a non-woven fabric support layer to form an initial membrane, which is then quickly immersed in a coagulation bath to undergo phase inversion to obtain an MBR membrane.

2. The method according to claim 1, characterized in that The aluminum flocculant is a mixture of polyaluminum chloride and calcium hydroxide, and the mixing mass ratio is 1:0.1-0.

15.

3. The method according to claim 1, characterized in that 6-Hydroxymethylsulfamethazine modified wood ash was prepared by the following method: Grind and sieve the wood ash, soak it in a mixed aqueous solution of citric acid and oxalic acid for 0.5 to 3 hours, take it out and wash it with water until it is neutral, then ultrasonically disperse it in water, add epoxy silane coupling agent and stir to react for 2 to 6 hours, then add 6-hydroxymethylsulfonamide and p-aminobenzoic acid, stir at 40 to 50°C for 3 to 8 hours, filter, wash with water and dry to obtain the product.

4. The method according to claim 3, characterized in that The mass ratio of wood ash to epoxy silane coupling agent is 1:0.8-2.

5. The method according to claim 3, characterized in that The mass ratio of wood ash to 6-hydroxymethylsulfamethazine is 1:0.2-0.

34.

6. The method according to claim 1, characterized in that The coagulation bath is an aqueous solution containing 4-6 wt % isopropyl alcohol and 0.2-0.5 wt % methoxypolyethylene glycol amine.

7. An application of an MBR membrane in seawater treatment, characterized in that: The applications include treating marine aquaculture wastewater, heavy metal-contaminated seawater or oil-contaminated seawater; The MBR membrane is prepared by the following method: 1) Material mixing: polyethersulfone, oxidized sodium alginate, 6-hydroxymethylsulfamethazine modified wood ash, pore-forming agent and solvent are mixed and stirred at high speed to obtain a mixed material; 2) Preparation of casting solution: Mix at 85-100°C to form a uniform casting solution and let it stand for degassing; 3) Preparation of MBR membrane by phase inversion method: The casting liquid is scraped onto a non-woven fabric support layer to form an initial membrane, which is then quickly immersed in a coagulation bath to undergo phase inversion to obtain an MBR membrane. The application of 8.6-hydroxymethylsulfonamide modified plant ash in improving the anti-fouling and anti-stripping properties of MBR membranes is characterized by: The MBR membrane is prepared by the following method: 1) Material mixing: polyethersulfone, oxidized sodium alginate, 6-hydroxymethylsulfamethazine modified wood ash, pore-forming agent and solvent are mixed and stirred at high speed to obtain a mixed material; 2) Preparation of casting solution: Mix at 85-100°C to form a uniform casting solution and let it stand for degassing; 3) Preparation of MBR membrane by phase inversion method: The casting liquid is scraped onto a non-woven fabric support layer to form an initial membrane, which is then quickly immersed in a coagulation bath to undergo phase inversion to obtain an MBR membrane. The application of 9.6-hydroxymethylsulfonamide modified plant ash in improving the seawater treatment effect of MBR membrane is characterized by: The MBR membrane is prepared by the following method: 1) Material mixing: polyethersulfone, oxidized sodium alginate, 6-hydroxymethylsulfamethazine modified wood ash, pore-forming agent and solvent are mixed and stirred at high speed to obtain a mixed material; 2) Preparation of casting solution: Mix at 85-100°C to form a uniform casting solution and let it stand for degassing; 3) Preparation of MBR membrane by phase inversion method: The casting liquid is scraped onto a non-woven fabric support layer to form an initial membrane, which is then quickly immersed in a coagulation bath to undergo phase inversion to obtain an MBR membrane.

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