Elastic microcarrier, preparation method and application thereof

Abstract

The invention provides an elastic microcarrier as well as a preparation method and application thereof, and belongs to the field of water, wastewater and sewage treatment, the elastic microcarrier comprises the following components in parts by mass: 50-75 parts of thermoplastic elastomer, 25-10 parts of diatomite, 10-5 parts of tourmaline and 15-10 parts of iron-carbon powder. The material has good elasticity, adsorbability, biocompatibility and electrochemical characteristics, and can form a microscopic primary battery effect. The elastic microcarrier is applied to sewage treatment with a membrane bioreactor, pollutants can be removed through physical adsorption, chemical action and biological enhancement, meanwhile, the surface of a membrane is kept clean in combination with flexible scraping, membrane pollution is remarkably slowed down, the running membrane flux is improved, and the service life of the membrane is prolonged. The mechanical damage of the traditional rigid filler to the membrane is avoided, and the service life of the membrane is prolonged. The preparation method of the elastic microcarrier is simple and easy to operate, the elastic microcarriers with uniform specifications can be prepared in batches, and the applicability is high.

Description

Technical Field

[0001] The present invention belongs to the field of water, wastewater and sewage treatment, and particularly relates to an elastic microcarrier, a preparation method thereof and an application thereof. Background Art

[0002] A membrane bioreactor (MBR) is a water treatment process that combines biological treatment technology with membrane separation technology, and has the advantages of simple process, high efficiency, high sludge concentration, small floor area of equipment, strong shock load resistance, etc. However, the problems of membrane fouling and high aeration energy consumption limit the popularization and application of the MBR process. Membrane fouling causes a significant decrease in the permeation flux and separation characteristics of the membrane, directly resulting in a decrease in membrane flux. Frequent cleaning will also shorten the service life.

[0003] Currently, the commonly used methods for preventing and controlling membrane fouling mainly include strengthening aeration, but too high aeration intensity will increase the energy consumption of the system. Or adding flocculants, surfactants, etc. to regulate the filtration properties of sludge; but adding chemicals will not only increase the operating cost, but also the long-term scraping of rigid fillers may cause mechanical damage to the membrane surface, resulting in a decrease in the performance of the membrane, and even membrane breakage, affecting the normal operation of the system. In addition, the addition of fillers will also increase the complexity of the system and cannot be recycled, and the economy is poor. Summary of the Invention

[0004] The main object of the present invention is to provide an elastic microcarrier, a preparation method thereof and an application thereof, aiming to solve the problems that it is difficult to continuously and effectively control membrane fouling and the cost is relatively high by using the existing technology.

[0005] To achieve the above object, the present invention provides an elastic microcarrier, which comprises, by mass parts, 50-75 parts of a thermoplastic elastomer, 25-10 parts of diatomite, 10-5 parts of tourmaline and 15-10 parts of iron-carbon powder.

[0006] Further, the particle size of the elastic microcarrier is 500-2500 µm; the true density of the elastic microcarrier is 0.95-1.05 g / cm 3 .

[0007] The present invention also provides a preparation method of the above-mentioned elastic microcarrier, comprising the steps of: Providing a mixture of a thermoplastic elastomer, diatomite, tourmaline and iron-carbon powder.

[0008] Successively performing hot melt mixing treatment, cooling treatment and crushing and screening treatment on the mixture to obtain the elastic microcarrier.

[0009] Wherein, the mixture comprises, by mass parts, 50-75 parts of the thermoplastic elastomer, 25-10 parts of the diatomite, 10-5 parts of the tourmaline and 15-10 parts of the iron-carbon powder.

[0010] Furthermore, the elastic modulus of the thermoplastic elastomer is 50 to 1000 MPa.

[0011] Furthermore, the thermoplastic elastomer includes one or more of styrenic thermoplastic elastomers (TPS), polyurethane thermoplastic elastomers (TPU), polyolefin thermoplastic elastomers (TPV), polyester thermoplastic elastomers (TPEE), polyamide thermoplastic elastomers (TPAE), and bio-based biodegradable thermoplastic elastomers.

[0012] Furthermore, the tourmaline includes one or more of iron tourmaline, lithium tourmaline, magnesium tourmaline, and manganese tourmaline; the particle size of the tourmaline is 10 to 50 µm; the Zeta potential of the tourmaline is -40 to -10 mV.

[0013] Furthermore, the iron-carbon powder includes iron element and carbon element; the mass ratio of the iron element to the carbon element is 1:1 to 4; the particle size of the iron-carbon powder is 25 to 75 µm.

[0014] Furthermore, the temperature of the hot-melt mixing treatment is 120 to 220 °C.

[0015] The present invention also provides an application of the elastic microcarrier as described above, or the elastic microcarrier prepared by the preparation method as described above, in sewage treatment. The elastic microcarrier is added to the biochemical system; the addition amount of the elastic microcarrier is 4 to 15 g / L; the sludge concentration of the biochemical system is 10 to 20 g / L; wherein, the biochemical system includes a membrane bioreactor and an elastic microcarrier recovery device.

[0016] Furthermore, the elastic microcarrier recovery device includes one or more of a grille, a screen, and a hydrocyclone.

[0017] The beneficial effects achieved by the present invention: The elastic microcarrier provided by the present invention includes, by mass, 50 to 75 parts of a thermoplastic elastomer, 25 to 10 parts of diatomite, 10 to 5 parts of tourmaline, and 15 to 10 parts of iron-carbon powder. It has good elasticity, adsorption, biocompatibility, and electrochemical properties, and can form a microscopic primary battery effect by itself. Applying this elastic microcarrier to sewage treatment with a membrane bioreactor can remove pollutants through physical adsorption, chemical action, and biological enhancement, and at the same time keep the membrane surface clean by combining with flexible scraping, significantly slowing down membrane fouling, increasing the operating membrane flux, avoiding mechanical damage to the membrane by traditional rigid fillers, and extending the service life of the membrane.

[0018] The preparation method of the elastic microcarrier provided by the present invention is simple and easy to operate, can batch-produce elastic microcarriers with uniform specifications, and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the biochemical system structure of an optional embodiment of the present invention; Figure 2 This is a comparison diagram of polyester thermoplastic elastomer (TPEE) and the elastic microcarrier prepared in Example 1 of the present invention; wherein, Figure 2 (a) is a real picture of polyester thermoplastic elastomer (TPEE); Figure 2 (b) is a real picture of the elastic microcarrier; Figure 3 The surface microstructure of the elastic microcarrier prepared in Example 1 of the present invention is shown in FIG. Figure 3 (a) is a scanning electron microscope (SEM) image of a surface area of ​​the elastic microcarrier at a magnification of 2000 times; Figure 3 (b) is a scanning electron microscope (SEM) image of another surface area of ​​the elastic microcarrier at 1000 times magnification; Figure 4 This is a comparison diagram of the transmembrane pressure difference during the operation of the biochemical system of Example 1 and the biochemical system of Comparative Example 1 when the designed membrane flux is 20LMH in Analysis Example 1 of the present invention; Figure 5 This is a comparison diagram of the transmembrane pressure difference during the operation of the biochemical system of Example 1 and the biochemical system of Comparative Example 1 when the limiting membrane flux is 25LMH in Analysis Example 1 of the present invention; Figure 6 It is a comparison chart of the total nitrogen concentration of the effluent during the operation of the biochemical system of Example 1 and the biochemical system of Comparative Example 1 under the designed membrane flux of 20LMH and the limit membrane flux of 25LMH in Analysis Example 1 of the present invention; Figure 7 It is a comparison chart of the effluent total phosphorus concentration during the operation of the biochemical system of Example 1 and the biochemical system of Comparative Example 1 under the designed membrane flux of 20LMH and the limiting membrane flux of 25LMH in Analysis Example 1 of the present invention.

[0021] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0023] It should be noted that, without conflict, the following embodiments and the features in the embodiments may be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for the purpose of describing specific embodiments, rather than limiting the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used in the present invention, based on the understanding of those skilled in the art of the prior art and the description of the present invention, may also use any methods, devices, and materials of the prior art similar or equivalent to those described in the embodiments of the present invention to implement the present invention. When the embodiments give a numerical range, it should be understood that, unless otherwise stated in the present invention, any value between the two endpoints of each numerical range and any one of the two endpoints can be selected. The test methods without specific conditions indicated in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by each manufacturer. The materials or reagents required in the following embodiments are commercially available unless otherwise specified.

[0025] In order to solve the problems that it is difficult to continuously and effectively control membrane fouling and the cost is relatively high by using the prior art, the present invention provides an elastic microcarrier. The elastic microcarrier includes, by mass, 50-75 parts of thermoplastic elastomer, 25-10 parts of diatomite, 10-5 parts of tourmaline, and 15-10 parts of iron-carbon powder. It should be noted that the biofilm carriers used in the prior art are usually rigid fillers, such as powdered activated carbon, zeolite, perlite, etc., which increase the scratching with the membrane surface.

[0026] Specifically, for the elastic microcarrier compounded according to the mass parts of 50-75 parts of thermoplastic elastomer, 25-10 parts of diatomite, 10-5 parts of tourmaline, and 15-10 parts of iron-carbon powder, a synergistic effect is generated among its various components, making the elastic microcarrier have good elasticity, adsorption, biocompatibility, and electrochemical properties. Among them, 25-10 parts of diatomite provides adsorption and biocompatibility, promoting the enrichment of functional microorganisms in the system. 10-5 parts of tourmaline has electrode polarity and spontaneous polarization effect, and 15-10 parts of iron-carbon powder has micro-electrolysis effect. Both can change the charge distribution of pollutants and reduce the adsorption ability of pollutants on the membrane surface. In addition, the microelectric field formed by the tourmaline can enhance the microscopic primary battery effect formed by the iron-carbon powder in the biochemical system, enhance the degradation ability of organic pollutants, and effectively prevent membrane fouling.

[0027] The elastic microcarrier provided by the present invention comprises, by mass parts, 50 - 75 parts of thermoplastic elastomer, 25 - 10 parts of diatomite, 10 - 5 parts of tourmaline, and 15 - 10 parts of iron-carbon powder. It has good elasticity, adsorption, biocompatibility, and electrochemical properties, and can form a microscopic primary battery effect by itself. When the elastic microcarrier is applied to sewage treatment with a membrane bioreactor, pollutants can be removed through physical adsorption, chemical action, and biological enhancement. At the same time, the membrane surface can be kept clean by combining with flexible scraping, significantly slowing down membrane fouling, increasing the operating membrane flux, avoiding mechanical damage to the membrane caused by traditional rigid fillers, and prolonging the service life of the membrane.

[0028] Furthermore, the particle size of the elastic microcarrier is 500 - 2500 µm; the true density of the elastic microcarrier is 0.95 - 1.05 g / cm 3 . Specifically, when the elastic microcarrier with a particle size of 500 - 2500 µm and a true density of 0.95 - 1.05 g / cm 3 is added to the sewage, it can be suspended in the sewage, and functional microorganisms in the sewage can quickly attach and grow on the surface of the elastic microcarrier. The diatomite in the elastic microcarrier can accelerate microbial enrichment; at the same time, through the electrochemical properties of tourmaline and iron-carbon powder in it, the content of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in the activated sludge is reduced, the viscosity of the mixed liquor is decreased, and membrane pore blockage is slowed down; and through the electrostatic attraction adsorption between tourmaline, iron-carbon powder and organic substances such as proteins, polysaccharides, humic acids, and fats, the above-mentioned organic macromolecular substances are preferentially enriched on the surface of the elastic microcarrier, and are preferentially degraded by functional microorganisms, avoiding the formation of a dense gel layer on the membrane surface and greatly increasing the filtration resistance; in addition, through the flexible scraping action of the elastic microcarrier, membrane fouling is effectively controlled.

[0029] The present invention also provides a preparation method of the above elastic microcarrier, comprising the steps of: Providing a mixture of thermoplastic elastomer, diatomite, tourmaline, and iron-carbon powder.

[0030] Performing hot melt mixing treatment, cooling treatment, and crushing and screening treatment on the mixture in sequence to obtain the elastic microcarrier. Specifically, after the mixture is subjected to hot melt mixing treatment, it is cooled to solidify by slow cooling at room temperature. Then the solidified mixture is subjected to crushing and screening treatment. Preferably, the crushing and screening treatment method is to mechanically cut and crush the solidified mixture and pass it through a target particle size sieve, and collect the screened particle product with a particle size of 500 - 2500 µm, that is, the elastic microcarrier with a particle size of 500 - 2500 µm is obtained.

[0031] Among them, the mixture includes, by mass parts, 50 to 75 parts of thermoplastic elastomer, 25 to 10 parts of diatomite, 10 to 5 parts of tourmaline, and 15 to 10 parts of iron-carbon powder.

[0032] The preparation method of the elastic microcarrier provided by the present invention is simple and easy to operate, can batch-prepare elastic microcarriers with uniform specifications, and has strong applicability.

[0033] Furthermore, the elastic modulus of the thermoplastic elastomer is 50 to 1000 MPa. Specifically, when the elastic modulus of the thermoplastic elastomer is lower than 50 MPa, its texture is soft and the treatment effect on the pollutants on the membrane surface is limited; while the thermoplastic elastomer with a high elastic modulus exceeding 1000 MPa has a high preparation cost and has no application value in large-scale sewage treatment.

[0034] Furthermore, the thermoplastic elastomer includes one or more of styrene-based thermoplastic elastomer (TPS), polyurethane-based thermoplastic elastomer (TPU), polyolefin-based thermoplastic elastomer (TPV), polyester-based thermoplastic elastomer (TPEE), polyamide-based thermoplastic elastomer (TPAE), and bio-based biodegradable thermoplastic elastomer. In sewage treatment, industrial wastes of the above thermoplastic elastomers can also be used to achieve the purpose of treating waste with waste.

[0035] Furthermore, the tourmaline includes one or more of iron tourmaline, lithium tourmaline, magnesium tourmaline, and manganese tourmaline; the particle size of the tourmaline is 10 to 50 µm; the Zeta potential of the tourmaline is -40 to -10 mV. Specifically, experiments have found that tourmaline in the particle size range of 10 to 50 µm has a larger specific surface area and microbial attachment sites, and can be evenly dispersed in the elastic microcarrier. And the Zeta potential range controlled by the tourmaline is controlled at -40 to -10 mV, which can give full play to its electrode polarity and spontaneous polarization effect, and cooperate with the iron-carbon powder to change the charge distribution of the pollutants and accelerate their enrichment and decomposition on the surface of the elastic microcarrier.

[0036] Furthermore, the iron-carbon powder includes iron element and carbon element; the mass ratio of the iron element to the carbon element is 1:1 to 4; the particle size of the iron-carbon powder is 25 to 75 µm. Specifically, controlling the mass ratio of the iron element to the carbon element at 1:1 to 4 fully guarantees the electron transfer efficiency in the microscopic primary battery formed during the use of the elastic microcarrier of the present invention, and at the same time can effectively avoid the problems of a large amount of iron ion dissolution and high preparation cost caused by too high a proportion of the iron element; and the highly uniform micron-sized particle size control of the iron-carbon powder not only guarantees the number of microscopic primary batteries formed in the elastic microcarrier, but also increases the contact probability with the tourmaline and improves its synergistic effect.

[0037] Furthermore, the temperature for hot-melt mixing treatment is 120~220 °C. Specifically, according to the melting point difference of the thermoplastic elastomer, its lowest melting temperature is determined as the temperature for hot-melt mixing treatment. Particularly, when two or more thermoplastic elastomers are used as the base materials, the melting point of the highest one of the thermoplastic elastomers should be selected as the melting temperature, and mechanical stirring is used to ensure uniform mixing of each component. The duration of hot-melt mixing treatment generally should not exceed 30 min, preferably 10~30 min, to avoid chemical reactions between components resulting in material denaturation.

[0038] The present invention also provides an application of the elastic microcarrier as described above, or the elastic microcarrier prepared by the preparation method as described above, in sewage treatment. The elastic microcarrier is added to the biochemical system; the dosage of the elastic microcarrier is 4~15 g / L; the sludge concentration of the biochemical system is 10~20 g / L. Among them, the biochemical system includes a membrane bioreactor and an elastic microcarrier recovery device 4.

[0039] Furthermore, the elastic microcarrier recovery device 4 includes one or more of a grille, a sieve, and a hydrocyclone. Specifically, referring to Figure 1 , for a membrane bioreactor with a high sludge concentration, the start-up period of the elastic microcarrier can be significantly shortened, accelerating the attachment of functional microorganisms on the surface of the elastic microcarrier, and then gradually eliminating the activated sludge through the elastic microcarrier recovery device 4.

[0040] Specifically, according to the pollutant treatment load of the membrane bioreactor, the dosage of the elastic microcarrier is adjusted to take into account the dual effects of enhancing pollutant removal and preventing membrane fouling. For example, when the elastic microcarrier is added to a biochemical system with a BOD5 load of 0.05~0.1 kgBOD5 / (kgMLSS·d), the dosage of the elastic microcarrier is 6~10 g / L. If the elastic microcarrier is added to a biochemical system with a BOD5 load of 0.15~0.3 kgBOD5 / (kgMLSS·d), the dosage of the elastic microcarrier is 10~15 g / L.

[0041] In an optional embodiment, referring to Figure 1, the elastic microcarriers are added to a biochemical system with a biochemical unit - membrane unit - elastic microcarrier recovery unit. This biochemical system includes a water inlet tank 1, a biochemical pool 2, a membrane pool 3, an elastic microcarrier recovery device 4, a stirring device 5, an aeration device 6, a water inlet pump 7, a membrane pool return water pump 8, an aerobic zone return pump 9, an anoxic zone return pump 10, and a sludge recovery pump 11. Among them, the biochemical pool 2 and the membrane pool 3 serve as the biochemical unit and the membrane unit of the biochemical system respectively, and together they form the membrane bioreactor of this biochemical system. In addition, the biochemical pool 2 is divided into an anaerobic zone, an anoxic zone, and an aerobic zone according to the dissolved oxygen content in the pool. During sewage treatment, the dosage of the elastic microcarriers is determined according to the BOD5 load, and the elastic microcarriers are put into the anaerobic zone of the biochemical pool 2, and full - pool fluidization is achieved under the action of water flow. Preferably, the elastic microcarrier recovery device 4 is a hydrocyclone. During the sewage treatment process, the elastic microcarriers attached with functional microorganisms are recovered through the differences in particle size and specific gravity between the elastic microcarriers and the activated sludge, and the suspended sludge in the system is eliminated to further reduce the content of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in the activated sludge, reduce the viscosity of the mixed liquor, and slow down the membrane pore blockage.

[0042] The elastic microcarriers added during the sewage treatment process form micro - sludge particles after microbial attachment. These micro - sludge particles have good filtration performance, can reduce the aeration intensity of the membrane pool, and avoid the adverse effects of high dissolved oxygen carried in the multi - stage reflux on denitrifying de - nitrogenation and anaerobic phosphorus release; they can be recovered by simple mechanical means, gradually eliminate the suspended sludge in the biochemical system, realize the improvement of the functional microbial biomass in the biochemical section, strengthen the simultaneous nitrification and denitrification in the aerobic section, and can also further enhance the phosphorus removal in the system through the chemical reaction between the iron ions released by the elastic microcarriers and phosphorus in the sewage. Applying this elastic microcarrier to sewage treatment effectively avoids the drawback of further increasing aeration during the membrane pollution control process of traditional fillers, and at the same time solves the problem of increased operating costs caused by the inability to recover traditional fillers; it realizes a significant extension of the membrane cleaning cycle and replacement cycle, and greatly reduces the sewage treatment cost.

[0043] For a further understanding of the present invention, the following is an example for illustration: Example 1 Preparation of elastic microcarriers: Weigh 60 parts of polyester - based thermoplastic elastomer (TPEE), 20 parts of diatomite, 5 parts of tourmaline, and 15 parts of iron - carbon powder. After mixing evenly, place them in a hot melt mixer at 150 °C. After slow cooling to room temperature until solidification, mechanically cut and crush them, and screen out micro - particles with a particle size distribution between 500 - 2500 µm, that is, the elastic microcarriers are obtained.

[0044] Figure 2 (a) is a real - shot picture of polyester - based thermoplastic elastomer (TPEE). TPEE is a transparent particle with a smooth surface and an elastic modulus of 750 MPa;Figure 2 (b) is a real - shot picture of the processed elastic micro - carrier. The elastic micro - carrier has an irregular black structure and its elastic modulus drops to 450 MPa. Figure 3 (a) and Figure 3 (b) are respectively the micro - structure diagrams of different positions on the surface of the elastic micro - carrier magnified 2000 times and 1000 times. It can be found that diatomite, tourmaline and iron - carbon powder are distributed disorderly in TPEE, indicating the successful preparation of the elastic micro - carrier; the surface is rough, which is convenient for the attachment of microorganisms, and the synergy between components is exerted through the connection of microorganisms and the surface contact of the elastic micro - carrier.

[0045] The biochemical system with a membrane bioreactor is as Figure 1 shown. It is composed of a steel structure, including three parts: a biochemical unit, a membrane unit and an elastic micro - carrier recovery device 4. The effective volume is 100 m 3 , the biochemical section is divided into an anaerobic zone, an anoxic zone and an aerobic zone, and the designed membrane flux is 20 LMH. The reflux ratio of the membrane pool to the aerobic zone is 300%, the reflux ratio of the aerobic zone to the anoxic zone is 300%, and the reflux ratio of the anoxic zone to the anaerobic zone is 200%. The inoculated sludge concentration is 12 g / L, and the dosage of the elastic micro - carrier is 8 g / L. The influent organic load is 0.12 - 0.15 kgBOD5 / (kgMLSS·d), the influent total nitrogen range is 17.6 - 44.5 mg / L, and the influent total phosphorus concentration is 4.01 - 5.06 mg / L. During operation, sludge is discharged through the elastic micro - carrier recovery device 4. The test is divided into two stages. In stage 1, it operates according to the designed membrane flux (20 LMH), and in stage 2, the membrane flux is further increased to 25 LMH.

[0046] Example 2 Preparation of the elastic micro - carrier: Weigh 50 parts of a mixture of polyester - based thermoplastic elastomer (TPEE) and polyurethane - based thermoplastic elastomer (TPU), 25 parts of diatomite, 10 parts of tourmaline and 15 parts of iron - carbon powder. After mixing evenly, place them in a hot - melt mixing at 150 °C. After cooling and solidifying, cut and crush them mechanically, and screen out micro - particles with a particle size distribution between 500 - 2500 µm to obtain the elastic micro - carrier.

[0047] Build a continuous - flow membrane biochemical reactor combined with a screen for sludge discharge as a test system (biochemical system), and its effective volume is 10 L. The designed retention time is 8 h, the water change ratio is 40%, and it operates according to the designed membrane flux of 20 LMH for testing. The inoculated sludge concentration is 15 g / L, and the dosage of the elastic micro - carrier is 10 g / L. The influent organic load is 0.15 - 0.25 kgBOD5 / (kgMLSS·d), the influent total nitrogen concentration range is 46.8 - 55.9 mg / L, and the influent total phosphorus concentration is 4.69 - 6.12 mg / L.

[0048] Comparative Example 1 Compared with Example 1, elastic microcarriers were not added to the biochemical system with a membrane bioreactor as shown in Figure 1 ; and the sludge discharge was not carried out using the elastic microcarrier recovery device 4.

[0049] Comparative Example 2 Compared with Example 2, elastic microcarriers were not added to the test system of the continuous flow membrane bioreactor combined with screen sludge discharge.

[0050] Comparative Example 3 Compared with Example 2, the components of the prepared carrier were as follows: by mass, 75 parts of a mixture of polyester thermoplastic elastomer (TPEE) and polyurethane thermoplastic elastomer (TPU), 10 parts of tourmaline, and 15 parts of iron-carbon powder, and the remaining preparation conditions were the same.

[0051] Comparative Example 4 Compared with Example 2, the components of the prepared carrier were as follows: by mass, 60 parts of a mixture of polyester thermoplastic elastomer (TPEE) and polyurethane thermoplastic elastomer (TPU), 25 parts of diatomite, and 15 parts of iron-carbon powder, and the remaining preparation conditions were the same.

[0052] Comparative Example 5 Compared with Example 2, the components of the prepared carrier were as follows: by mass, 65 parts of a mixture of polyester thermoplastic elastomer (TPEE) and polyurethane thermoplastic elastomer (TPU), 25 parts of diatomite, and 10 parts of tourmaline, and the remaining preparation conditions were the same.

[0053] Analysis Example 1 The operation conditions of the biochemical systems of Example 1 and Comparative Example 1 were monitored, and the transmembrane pressure differences during the operation at the designed membrane flux of 20 LMH and the ultimate membrane flux of 25 LMH are respectively shown in Figure 4 、 Figure 5 .

[0054] From Figure 4 and Figure 5 , it can be seen that under the operation condition of the designed membrane flux of 20 LMH, for the group without adding elastic microcarriers (Comparative Example 1), the transmembrane pressure difference had risen to the cleaning threshold in only about 11 days, and chemical cleaning had to be carried out to restore its membrane flux; while for the group adding elastic microcarriers (Example 1), the transmembrane pressure difference was stable during the whole test process, and chemical cleaning was not carried out for 32 consecutive days. Further increasing to the ultimate membrane flux of 25 LMH, the cleaning cycle of Comparative Example 1 was further shortened to about 6 days, while although the elastic microcarrier group showed an upward trend, it still stably operated for more than 30 days before reaching the cleaning threshold, greatly prolonging the membrane cleaning cycle and achieving the purpose of preventing membrane fouling.

[0055] Analysis Example 2 Monitor the operation of the biochemical systems in Example 1 and Comparative Example 1. The comparison of the total nitrogen concentration and total phosphorus concentration in the effluent during the operation at the designed membrane flux of 20 LMH and the limiting membrane flux of 25 LMH is as follows Figure 6 、 Figure 7 shown.

[0056] From Figure 6 and Figure 7 it can be seen that the average values of total nitrogen and total phosphorus in the effluent of the group with the addition of elastic microcarriers (Example 1) are 1.93 mg / L and 0.08 mg / L lower than those in Comparative Example 1 at the designed membrane flux of 20 LMH and 4.87 mg / L and 0.18 mg / L lower at the limiting membrane flux of 25 LMH. Among them, the effluent quality of the group with the addition of elastic microcarriers can stably meet the Class IV surface water standard.

[0057] Analysis Example 3 Monitor the operation of the biochemical systems in Example 2 and Comparative Examples 2 - 5. The comparison results of the cleaning cycle, total nitrogen in the effluent, and total phosphorus in the effluent during the operation of each example are shown in Table 1.

[0058] Table 1 Comparison of the operation results of the biochemical systems in Example 2 and Comparative Examples 2 - 5 It can be seen from Table 1 that when adding elastic microcarriers composed of thermoplastic elastomer, diatomite, tourmaline, and iron - carbon powder (Example 2), the membrane cleaning cycle is the longest, effectively alleviating the damage to the membrane caused by chemical cleaning; the effluent quality is better than that of other comparative examples. The synergistic effect among the components not only achieves the purpose of preventing membrane fouling but also synchronously enhances the removal efficiency of pollutants.

[0059] In summary, in the above - mentioned technical solutions of the present invention, the above are only the preferred embodiments of the present invention. It does not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. An elastic microcarrier, characterized in that, The elastic microcarrier comprises, by mass parts, 50 to 75 parts of thermoplastic elastomer, 25 to 10 parts of diatomite, 10 to 5 parts of tourmaline, and 15 to 10 parts of iron-carbon powder.

2. The elastic microcarrier according to claim 1, wherein The particle size of the elastic microcarrier is 500 - 2500 µm; the true density of the elastic microcarrier is 0.95 - 1.05 g / cm 3 .

3. A method for preparing an elastic microcarrier as described in claim 1 or 2, characterized in that, It includes the steps of: providing a mixture of thermoplastic elastomer, diatomite, tourmaline, and iron-carbon powder; performing hot melt mixing treatment, cooling treatment, and crushing and screening treatment on the mixture in sequence to obtain the elastic microcarrier; wherein, the mixture comprises, by mass parts, 50 to 75 parts of the thermoplastic elastomer, 25 to 10 parts of the diatomite, 10 to 5 parts of the tourmaline, and 15 to 10 parts of the iron-carbon powder.

4. The preparation method according to claim 3, wherein The elastic modulus of the thermoplastic elastomer is 50 to 1000 MPa.

5. The preparation method according to claim 4, wherein, The thermoplastic elastomer includes one or more of styrene-based thermoplastic elastomer (TPS), polyurethane-based thermoplastic elastomer (TPU), polyolefin-based thermoplastic elastomer (TPV), polyester-based thermoplastic elastomer (TPEE), polyamide-based thermoplastic elastomer (TPAE), and bio-based biodegradable thermoplastic elastomer.

6. The preparation method according to claim 3, characterized in that, The tourmaline includes one or more of iron tourmaline, lithium tourmaline, magnesium tourmaline, and manganese tourmaline; the particle size of the tourmaline is 10 to 50 µm; the Zeta potential of the tourmaline is -40 to -10 mV.

7. The preparation method according to claim 3, characterized in that, The iron-carbon powder includes iron element and carbon element; the mass ratio of the iron element to the carbon element is 1:1 to 4; the particle size of the iron-carbon powder is 25 to 75 µm.

8. The preparation method according to claim 3, characterized in that, The temperature of the hot melt mixing treatment is 120 to 220 °C.

9. Use of an elastic microcarrier as described in claim 1 or 2, or an elastic microcarrier prepared by the preparation method described in any one of claims 3 to 8, in sewage treatment, characterized in that, Adding the elastic microcarrier to the biochemical system; the dosage of the elastic microcarrier is 4 to 15 g / L; the sludge concentration of the biochemical system is 10 to 20 g / L; wherein, the biochemical system includes a membrane bioreactor and an elastic microcarrier recovery device.

10. The application according to claim 9, wherein The elastic microcarrier recovery device includes one or more of a grille, a screen, and a hydrocyclone.

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