Preparation method of active filler with high biological affinity and application of filler in water treatment

Abstract

The invention discloses a preparation method of active filler with high biological affinity and application of the filler in water treatment. The preparation method comprises the following steps: S1, preparing a matrix; s2, preparing a hydrogel coating solution; s3, coating is carried out; and S4, surface treatment. By coupling magnetic doping, active component pre-coating and surface plasma cleaning modification, the biocompatibility and microbial activity stimulation effect of the filler are remarkably improved, and the microbial metabolic activity enhancing efficiency is improved; the obtained filler structurally comprises a polyethylene matrix, an NdFeB magnetic functional core, a bionic hydrogel signal coating and a plasma modified surface, and a multi-layer and multifunctional integrated filler is formed.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and specifically relates to a preparation method of a high bio-affinity active filler and its application in water treatment. Background Art

[0002] Biological fillers are widely used in water treatment and are one of the common methods for in-situ upgrading of the activated sludge process. However, when the nutrient element content in sewage is low, or when treating toxic and harmful wastewater (such as refining wastewater, pharmaceutical wastewater, etc.), the existing common fillers generally have problems such as low film hanging efficiency, poor microbial activity, and low loading capacity.

[0003] Sewage treatment processes such as moving bed biofilm reactor (MBBR) and biological contact oxidation promote the attached growth of microorganisms in the form of biofilms by adding fillers to the reactor, thereby improving the treatment efficiency. The fillers provide an attachment carrier with a high specific surface area, enabling microorganisms to be fixed and form a stable biofilm, achieving efficient degradation of organic pollutants and ammonia nitrogen. Introducing fillers on the basis of the traditional activated sludge process to form a mud-film hybrid process can utilize the synergistic effect of suspended sludge and attached biofilm simultaneously, improving the system's shock load resistance ability and shortening the residence time.

[0004] However, existing filler materials (usually polyethylene or polypropylene plastics) have limited bio-affinity due to their hydrophobic and smooth surfaces, often resulting in problems such as slow film hanging rate, low initial biomass, and long system startup period. It is difficult for microbial cells to achieve rapid adhesion and colonization on the hydrophobic surface, and it often takes several weeks to form a stable biofilm, resulting in a long process startup and commissioning time. The poor affinity between the filler and microorganisms leads to insufficient attached biomass, affecting the pollutant removal efficiency and possibly causing biofilm shedding due to weak adhesion. In addition, the lack of active components in the existing fillers makes it difficult to fully stimulate the metabolic activity of microorganisms, resulting in unsatisfactory filler dosing effects when the nutrient element content in sewage is low, or when treating toxic and harmful wastewater (such as refining wastewater, pharmaceutical wastewater, etc.).

[0005] Therefore, it is urgent to improve the bio-affinity activity of fillers by improving the surface properties and functional components, develop high bio-affinity active fillers for water treatment, accelerate biofilm hanging, and enhance the metabolic activation function of fillers on microorganisms. In some studies, some people have studied the biofilm hanging speed.

[0006] For example, patent CN201310088443 uses synthetic polymer particles as a base material, adds microporous bio-affinity substances or their modified substances, and adds natural substances that can automatically and continuously generate negative ions and far-infrared rays. These substances are then added to a dispersant in a blender and thoroughly mixed to form various types of fillers. Patent CN201610854649 adds fillers and magnetic diatomaceous earth to the traditional process formula to produce a high-affinity organic biofiller with a density closer to water, a larger specific surface area than similar products, a rougher surface, and rapid biofilm growth while ensuring physical strength and service life. Similarly, patent CN202410708168 proposes a magnetically modified MBBR water purification filler and its corresponding preparation process. However, the above research results still have room for improvement. Summary of the Invention

[0007] In view of the above problems, the present invention provides a method for preparing a high bioaffinity active filler and its application in water treatment.

[0008] The technical solution of the present invention is:

[0009] The preparation method of the high bioaffinity active filler comprises the following steps:

[0010] S1. Matrix preparation: polyethylene particles and NdFeB magnets are mixed in a weight ratio of 92-99:1-8, melt-extruded, cooled, stretched, and pelletized to obtain a filler matrix;

[0011] S2. Preparation of a hydrogel coating solution: After heating the hydrogel solution to 40-50° C., a 40-60% mass concentration of glutaraldehyde solution is added to adjust the volume fraction of glutaraldehyde in the hydrogel solution to 0.4-0.6%. Then, N-octanoyl homoserine lactone signal molecule is added to adjust the molar concentration of the N-octanoyl homoserine lactone signal molecule in the hydrogel solution to 10-100 μmol / L. After stirring, the hydrogel coating solution is obtained for use.

[0012] S3, coating: immersing the filler matrix in the hydrogel coating liquid. After the immersion is completed, the filler matrix is taken out and the excess hydrogel coating liquid is filtered out. The filler matrix is heated and dried to obtain a hydrogel-coated filler doped with magnetic powder;

[0013] S4. Surface treatment: subjecting the hydrogel-coated filler doped with magnetic powder to oxygen plasma surface treatment to obtain an active filler.

[0014] Furthermore, in S1, the melt index of the polyethylene particles is 2±0.2 g / 10 min and the density is 0.94-0.96 g / cm 3 The average particle size of NdFeB magnetic powder is 50±10μm.

[0015] Further, in S1, during melt extrusion, a twin-screw extruder is used to melt and co-extrude at 140-180°C, and then cooled to room temperature of 25-28°C. The volume of the filler matrix is 10-1000 mm 3 .

[0016] The magnetic enhancement mechanism of adding NdFeB magnetic powder is as follows: the embedded NdFeB magnetic powder endows the filler with the property of activating microbial metabolism. The constant weak magnetic field provided by the NdFeB magnetic powder (especially in the magnetic field intensity range of 0.3-1.2 mT) helps to activate certain physiological activities of microorganisms (it is reported that weak magnetic fields can increase the activity of proteins containing ferromagnetic ions), thus indirectly promoting the metabolism and reproductive function of microorganisms.

[0017] Further, in S2, the hydrogel solution is a polyvinyl alcohol hydrogel, and the preparation method of the polyvinyl alcohol hydrogel is as follows:

[0018] Take industrial-grade polyvinyl alcohol and dissolve it in hot water at a concentration of 5% (w / v) at 85-95°C and stir to obtain a polyvinyl alcohol hydrogel;

[0019] Meanwhile, after adding the glutaraldehyde solution, add a dilute hydrochloric acid solution to adjust the pH of the hydrogel solution to 3-4.

[0020] Further, in S2, the hydrogel solution is a gelatin-chitosan composite hydrogel, and the preparation method of the gelatin-chitosan composite hydrogel is as follows:

[0021] Dissolve 2±0.05 g of gelatin in 50-80 mL of warm water at 38-43°C until completely dissolved to obtain a gelatin solution. Dissolve 1±0.05 g of chitosan in 80-100 mL of acetic acid aqueous solution with a mass concentration of 1-2% and stir to dissolve it, then add it to the gelatin solution to obtain a mixture. Add water to make the total volume of the mixture 200 mL, and continue to stir evenly to obtain a gelatin-chitosan composite hydrogel.

[0022] Furthermore, in S3, the immersion time is 3-5 min. Place the impregnated filler matrix in an oven and heat it at 60-65°C for 1-1.5 h to complete glutaraldehyde cross-linking and curing. Then raise the temperature to 80-85°C and continue to dry for 1-1.5 h until the polyvinyl alcohol hydrogel on the surface of the filler matrix is completely dry and firmly attached, obtaining a polyvinyl alcohol hydrogel-coated filler.

[0023] Furthermore, in S3, the immersion time is 2 to 3 minutes, and the impregnated filler matrix is placed on a Teflon plate, first placed in a refrigerator at 2 to 4°C and cooled for 30 to 40 minutes to solidify the gelatin-chitosan composite hydrogel into a gel, and then transferred to a 55 to 65°C oven and dried for 1 to 1.5 hours to promote the cross-linking reaction, and finally dried at 80 to 85°C for another 0.5 to 1 hour to obtain a gelatin-chitosan composite hydrogel coated filler.

[0024] The mechanism by which the hydrogel and signaling molecules promote biofilm formation is as follows: The biomimetic hydrogel coating on the filler surface mimics the hydration environment of natural microbial biofilms. Its high water content and flexible three-dimensional network structure attract and temporarily retain cells in the aqueous phase. The hydrogel's viscoelasticity provides a buffering effect, mitigating the shear forces on initially attached bacteria during aeration and agitation, preventing early-attached microorganisms from being washed away. Simultaneously, quorum sensing signaling molecules embedded in the hydrogel are slowly released within the hydration environment or distributed in a gradient across the coating surface, acting as inducers of microbial chemotaxis and physiological activation. When a small number of microorganisms attach, these signaling molecules rapidly promote interbacterial communication, inducing the expression of genes involved in biofilm development in attached bacteria, such as the production of more sticky EPS, flagella, and biofilm matrix. Even when the overall bacterial concentration in the external wastewater is low, the signaling molecules can still reach a threshold concentration in the local microenvironment, accelerating the quorum sensing-triggered biofilm formation process. Furthermore, the hydrophilicity and biocompatibility of the hydrogel coating facilitate the co-attachment of diverse microorganisms. Its surface can absorb nutrients and trace elements, providing favorable nutritional and signaling conditions for the nascent biofilm. This "bionic base film" effectively bridges the interface between the inorganic carrier and the living bacterial flocs, creating a microenvironment conducive to bacterial colonization and growth upon contact with wastewater.

[0025] Furthermore, in S4, the method of oxygen plasma surface treatment is:

[0026] The hydrogel-coated filler is placed in a vacuum chamber and oxygen is introduced to a pressure of 28 to 30 Pa, a power of 30 to 200 W, and the treatment is carried out for 30 to 600 seconds.

[0027] The plasma modification mechanism is as follows: Plasma surface treatment, as the last step, further enhances the overall surface activity of the filler. For the exposed polyethylene matrix part, plasma bombardment can etch out nanoscale rough textures and introduce oxygen-containing functional groups such as hydroxyl and carbonyl groups on the molecular chains, significantly reducing the water contact angle of the substrate surface and increasing the wettability. The treatment can raise the oxygen content on the plastic surface to a significant level within just a few seconds and maintain a certain stability. For the area covered with hydrogel, plasma discharge can also generate some free radicals or functional groups on the hydrogel surface layer, which may form slight cross-linking or bonding effects, thus making the hydrogel coating more tightly bonded to the substrate surface and not easily peeled off. At the same time, after plasma activation, the entire filler surface (including the outside of the hydrogel layer) has a higher surface energy, which means that even after the initial signal molecules are exhausted, the filler surface itself still maintains highly hydrophilic and easy-to-attach characteristics and can continuously attract subsequent flowing microorganisms to adhere to it.

[0028] The present invention also provides the application of the highly bioaffinity-active filler prepared by the above method in water treatment.

[0029] Furthermore, the active filler is applied to the treatment of toxic and harmful sewage in a moving bed biofilm reactor or a biological contact oxidation process.

[0030] The beneficial effects of the present invention are as follows:

[0031] (1) By coupling magnetic doping, pre-coating of active components, and surface plasma cleaning modification, the present invention significantly improves the bioaffinity of the filler and its stimulating effect on microbial activity, enhances the efficiency of microbial metabolic activity. The filler is made of polyethylene as the substrate into a hollow annular or short tubular carrier, and a certain proportion of neodymium iron boron (NdFeB) fine magnetic powder is uniformly mixed inside, making the filler body have persistent magnetism. A biomimetic hydrogel coating is pre-coated on its surface, and a small amount of microbial signal molecules (such as quorum sensing autoinducers) or other bioactive substances are pre-introduced into the hydrogel to construct an initial active "biofilm induction layer" on the filler surface; finally, the coated filler is subjected to low-temperature plasma surface treatment to further increase the energy and polar functional group content of its outer surface. The obtained filler structure includes: polyethylene matrix + NdFeB magnetic functional core + biomimetic hydrogel signal coating + plasma-modified surface, forming a multi-layered and multi-functional integrated filler.

[0032] (2) The highly bioaffinity-active filler prepared by the present invention can be applied in water treatment, accelerating the microbial film formation efficiency in a moving bed biofilm reactor or a biological contact oxidation process, improving microbial activity and loading capacity, and thus improving the treatment efficiency of toxic and harmful sewage. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the active filler prepared by the present invention;

[0034] Figure 2 It is a schematic diagram of the gel layer loaded with signal molecules shown by an optical microscope of the active filler prepared by the present invention;

[0035] Figure 3 It is the surface morphology of the modified filler shown by a scanning electron microscope of the active filler prepared by the present invention;

[0036] Figure 4 It is a data graph of the film-forming start test results of each group of fillers in Experimental Example 1 of the present invention;

[0037] Figure 5 It is a data graph of the film-forming start test results of each group of fillers in Experimental Example 2 of the present invention;

[0038] Figure 6 It is a data graph of the film-forming start test results of each group of fillers in Experimental Example 3 of the present invention. Detailed implementation manners

[0039] Example 1

[0040] A preparation method of a highly bioaffine active filler, comprising the following steps:

[0041] S1. Substrate preparation: Mix polyethylene particles and neodymium iron boron magnet in a weight ratio of 99:1. The melt index of the polyethylene particles is 2 g / 10 min, and the density is 0.95 g / cm 3 , the average particle size of the neodymium iron boron magnetic powder is 50 ± 10 μm. After melt extrusion, cool, stretch and pelletize to obtain a columnar filler substrate. When melt extruding, use a twin-screw extruder to melt and blend and extrude at 160 °C, cool to room temperature of 26 °C. The diameter of the columnar filler substrate is 5 mm, the length is 5 mm, and the volume is 98.17 mm 3 ;

[0042] S2. Preparation of hydrogel coating solution: The hydrogel solution is a polyvinyl alcohol hydrogel. Take industrial-grade polyvinyl alcohol and dissolve it in hot water at 90 °C at a concentration of 5% (w / v) and stir to obtain a polyvinyl alcohol hydrogel. After heating the polyvinyl alcohol hydrogel solution to 45 °C, add a glutaraldehyde solution with a mass concentration of 50% to make the volume fraction of glutaraldehyde in the hydrogel solution 0.5%. After adding the glutaraldehyde solution, add a dilute hydrochloric acid solution to adjust the pH of the hydrogel solution to 3.5, and then add N-octanoyl homoserine lactone signal molecule to make the molar concentration of N-octanoyl homoserine lactone signal molecule in the hydrogel solution 50 μmol / L. Stir evenly and set aside the hydrogel coating solution;

[0043] S3. Coating: Immerse the filler matrix in the hydrogel coating solution for 4 minutes. Place the impregnated filler matrix in an oven and heat it at 62 °C for 1.2 hours to complete glutaraldehyde crosslinking and curing. Then raise the temperature to 82 °C and continue drying for 1.2 hours until the polyvinyl alcohol hydrogel on the surface of the filler matrix is completely dry and firmly attached, obtaining the polyvinyl alcohol hydrogel-coated filler;

[0044] S4. Surface treatment: Perform oxygen plasma surface treatment on the hydrogel-coated filler doped with magnetic powder. Introduce oxygen into the vacuum chamber with the hydrogel-coated filler until the pressure reaches 29 Pa, with a power of 150 W, and treat for 600 s to obtain the active filler, as Figure 1 shown.

[0045] Example 2

[0046] The difference between this example and Example 1 is that:

[0047] In S1, the polyethylene particles and neodymium iron boron magnet are mixed in a weight ratio of 95:5.

[0048] Example 3

[0049] The difference between this example and Example 1 is that:

[0050] In S1, the polyethylene particles and neodymium iron boron magnet are mixed in a weight ratio of 92:8.

[0051] Example 4

[0052] The difference between this example and Example 1 is that:

[0053] In S2, the hydrogel solution is a gelatin-chitosan composite hydrogel. Dissolve 2 g of gelatin in 60 mL of warm water at 40 °C until completely dissolved to obtain a gelatin solution. Dissolve 1 g of chitosan in 900 mL of acetic acid aqueous solution with a mass concentration of 1.5% and stir to dissolve, then add it to the gelatin solution to obtain a mixed solution. Add water to make the total volume of the mixed solution 200 mL, and continue to stir evenly to obtain the gelatin-chitosan composite hydrogel;

[0054] In S3, the immersion time is 2 minutes. Place the impregnated filler matrix on a Teflon plate, first cool it in a refrigerator at 3 °C for 35 minutes to solidify the gelatin-chitosan composite hydrogel into a gel, then transfer it to an oven at 60 °C for drying for 1 hour to promote the crosslinking reaction, and finally dry it at 82 °C for 1 hour to obtain the gelatin-chitosan composite hydrogel-coated filler.

[0055] Example 5

[0056] The difference between this example and Example 1 is that:

[0057] The amount-of-substance concentration of the N-octanoyl homoserine lactone signaling molecule in the hydrogel solution is 10 μmol / L.

[0058] Example 6

[0059] The difference between this example and Example 1 is that:

[0060] The amount-of-substance concentration of the N-octanoyl homoserine lactone signaling molecule in the hydrogel solution is 100 μmol / L.

[0061] Example 7

[0062] The difference between this example and Example 1 is that:

[0063] S1. Substrate preparation: Mix polyethylene particles and neodymium iron boron magnetic powder in a weight ratio of 99:1. The melt index of the polyethylene particles is 1.8 g / 10 min, and the density is 0.94 g / cm 3 , the average particle size of the neodymium iron boron magnetic powder is 50 ± 10 μm. After melt extrusion, cool, stretch, and pelletize to obtain a filler substrate. During melt extrusion, a twin-screw extruder is used to melt and blend and extrude at 140 °C, and then cool to room temperature of 25 °C. The volume of the filler substrate is 10 mm 3 ;

[0064] S2. Preparation of hydrogel coating solution: The hydrogel solution is a polyvinyl alcohol hydrogel. Take industrial-grade polyvinyl alcohol and dissolve it in hot water at 85 °C at a concentration of 5% (w / v) and stir to obtain a polyvinyl alcohol hydrogel. After heating the polyvinyl alcohol hydrogel solution to 40 °C, add a glutaraldehyde solution with a mass concentration of 40% to make the volume fraction of glutaraldehyde in the hydrogel solution 0.4%. After adding the glutaraldehyde solution, add a dilute hydrochloric acid solution to adjust the pH of the hydrogel solution to 3. Subsequently, add the N-octanoyl homoserine lactone signaling molecule to make the amount-of-substance concentration of the N-octanoyl homoserine lactone signaling molecule in the hydrogel solution 50 μmol / L. After stirring evenly, obtain a hydrogel coating solution for standby;

[0065] S3. Coating: Immerse the filler substrate in the hydrogel coating solution for 3 min. Place the impregnated filler substrate in an oven and heat it at 60 °C for 1 h to complete glutaraldehyde cross-linking and curing. Subsequently, raise the temperature to 80 °C and continue to dry for 1 h until the polyvinyl alcohol hydrogel on the surface of the filler substrate is completely dry and firmly attached to obtain a polyvinyl alcohol hydrogel-coated filler;

[0066] S4. Surface treatment: Perform oxygen plasma surface treatment on the hydrogel-coated filler doped with magnetic powder. Pass oxygen into the vacuum chamber with the hydrogel-coated filler until the pressure is 28 Pa and the power is 30 W, and treat for for 600 s to obtain an active filler.

[0067] Example 8

[0068] The difference between this embodiment and Embodiment 1 is as follows:

[0069] S1. Substrate preparation: Polyethylene particles and neodymium iron boron magnet are mixed at a weight ratio of 99:1. The melt index of the polyethylene particles is 2.2 g / 10 min, and the density is 0.96 g / cm 3 , the average particle size of the neodymium iron boron magnetic powder is 50 ± 10 μm. After melt extrusion, it is cooled, stretched and pelletized to obtain a filler substrate. During melt extrusion, a twin-screw extruder is used for melt blending and extrusion at 180 °C, and it is cooled to room temperature of 28 °C. The volume of the filler substrate is 1000 mm 3 ;

[0070] S2. Preparation of hydrogel coating solution: The hydrogel solution is a polyvinyl alcohol hydrogel. Industrial-grade polyvinyl alcohol is dissolved in hot water at 95 °C at a concentration of 5% (w / v) and stirred to obtain a polyvinyl alcohol hydrogel. After heating the polyvinyl alcohol hydrogel solution to 50 °C, a glutaraldehyde solution with a mass concentration of 60% is added to make the volume fraction of glutaraldehyde in the hydrogel solution 0.6%. After adding the glutaraldehyde solution, a dilute hydrochloric acid solution is added to adjust the pH of the hydrogel solution to 4. Subsequently, N-octanoyl homoserine lactone signaling molecules are added to make the molar concentration of N-octanoyl homoserine lactone signaling molecules in the hydrogel solution 50 μmol / L. After stirring evenly, it is reserved as the hydrogel coating solution;

[0071] S3. Coating: The filler substrate is immersed in the hydrogel coating solution for 5 min. The impregnated filler substrate is placed in an oven and heated at 65 °C for 1.5 h to complete glutaraldehyde crosslinking and curing. Subsequently, the temperature is raised to 85 °C and dried for another 1.5 h until the polyvinyl alcohol hydrogel on the surface of the filler substrate is completely dried and firmly attached, obtaining a polyvinyl alcohol hydrogel-coated filler;

[0072] S4. Surface treatment: The hydrogel-coated filler doped with magnetic powder is subjected to oxygen plasma surface treatment. Oxygen is introduced into the vacuum chamber to a pressure of 30 Pa and a power of 200 W for 30 s to obtain an active filler.

[0073] Embodiment 9

[0074] The difference between this embodiment and Embodiment 4 is as follows:

[0075] In S2, the hydrogel solution is a gelatin-chitosan composite hydrogel. 1.95 g of gelatin is dissolved in 50 mL of warm water at 38 - 43 °C until completely dissolved to obtain a gelatin solution. 0.95 g of chitosan is dissolved in 80 mL of acetic acid aqueous solution with a mass concentration of 1% and stirred and dissolved, then added to the gelatin solution to obtain a mixed solution. Water is added to make the total volume of the mixed solution 200 mL, and it is continuously stirred evenly to obtain a gelatin-chitosan composite hydrogel;

[0076] In S3, the immersion time was 2 min. The impregnated filler matrix was placed on a Teflon plate, first cooled in a 2 °C refrigerator for 30 min to solidify the gelatin-chitosan composite hydrogel into a gel, then transferred to a 55 °C oven and dried for 1 h to promote the cross-linking reaction, and finally dried at 80 °C for another 0.5 h to obtain the gelatin-chitosan composite hydrogel-coated filler.

[0077] Example 10

[0078] The difference between this example and Example 4 is as follows:

[0079] In S2, the hydrogel solution was a gelatin-chitosan composite hydrogel. 2.05 g of gelatin was dissolved in 80 mL of warm water at 43 °C until completely dissolved to obtain a gelatin solution. 1.05 g of chitosan was dissolved in 100 mL of an acetic acid aqueous solution with a mass concentration of 2%, and after stirring and dissolving, it was added to the gelatin solution to obtain a mixed solution. Water was added to make the total volume of the mixed solution 200 mL, and stirring was continued until evenly mixed to obtain the gelatin-chitosan composite hydrogel;

[0080] In S3, the immersion time was 3 min. The impregnated filler matrix was placed on a Teflon plate, first cooled in a 4 °C refrigerator for 40 min to solidify the gelatin-chitosan composite hydrogel into a gel, then transferred to a 65 °C oven and dried for 1.5 h to promote the cross-linking reaction, and finally dried at 85 °C for another 1 h to obtain the gelatin-chitosan composite hydrogel-coated filler.

[0081] Example 11

[0082] This example is the application of the highly biocompatible active filler prepared in Example 1. The active filler prepared in S4 was applied to water treatment.

[0083] Example 12

[0084] This example is the application of the highly biocompatible active filler prepared in Example 1. The active filler prepared in S4 was applied to the treatment of toxic and harmful sewage in a biological contact oxidation process.

[0085] Example 13

[0086] This example is the application of the highly biocompatible active filler prepared in Example 1. The active filler prepared in S4 was applied to the treatment of toxic and harmful sewage in a moving bed biofilm reactor.

[0087] Experimental Example 1

[0088] Next, we conduct performance tests on the active fillers prepared in Examples 1 to 3: mainly compare the effects of the NdFeB doping ratio on the performance of promoting microbial film formation and the properties of the fillers. The fillers in Examples 1 to 3 are respectively denoted as A, B, and C, and the average magnetisms of A, B, and C are 0.1, 0.7, and 1.2 mT.

[0089] The three groups of fillers and ordinary PE fillers (as the control group) are put into 4 parallel small-scale biological contact oxidation reactors for biofilm startup tests. The reactors have the same volume, are inoculated with the same activated sludge and fed with the same culture medium (simulating organic wastewater, with an initial chemical oxygen demand COD of about 300 mg / L and ammonia nitrogen NH 4+ -N of about 30 mg / L), and are continuously operated for 30 days under aerobic conditions at 25°C.

[0090] After observation, on the 3rd day of operation of the filler B (5% NdFeB) group, a visible microbial thin layer could be seen on the surface of the filler. In the filler A and filler C groups, obvious biofilms appeared on the 4th day, while obvious biofilms on the ordinary PE filler appeared on the 7th day. On the 10th day of operation, the fillers of each group were taken out to measure the attached biomass (counted by the volatile suspended solids VSS per unit filler surface area). The results showed that the average attached biomass of the filler B group was 1.30 mg / cm 2 , higher than 0.95 mg / cm 2 of the filler A group and 1.02 mg / cm 2 of the filler C group, and more than twice the biomass of the ordinary PE group (0.62 mg / cm 2 ). It can be seen that the filler of the present invention greatly improves the initial biofilm formation amount.

[0091] In terms of the performance of organic matter removal, the COD removal rate of each group of fillers gradually increases with the growth of the biofilm. Among them, the COD removal rate of the reactor in the filler B group doped with 5% NdFeB reached 85% on the 7th day, higher than 78% of the group doped with 1% (filler A) and 82% of the group doped with 8% (filler C). After two weeks of operation, the COD removal rate of each group stabilized above 90%, higher than 84% of the ordinary PE filler. The removal of ammonia nitrogen was not significantly different at the initial stage due to the slow proliferation of nitrifying bacteria. By the 14th day, the NH 4+ -N removal rate of the filler B group was about 75%, slightly higher than 70% of the A group and 72% of the C group, but significantly higher than 47% of the ordinary PE filler group. Generally speaking, a moderate NdFeB doping ratio (such as 5%) helps to increase the surface micro-roughness and magnetism of the filler without affecting the coating uniformity, promotes the faster attachment and growth of microorganisms, and thus shows the best biofilm startup performance. However, generally speaking, the fillers within the doping range described in this method have much better bioaffinity than traditional uncoated fillers.

[0092] Experimental Example 2

[0093] Next, we conduct performance tests on the activated fillers prepared in Example 2 (Filler D) and Example 4 (Filler E): Filler D and Filler E are respectively put into two identical experimental bioreactors (the same as those used in Example 1) for parallel operation tests to compare the effects of different coatings on biofilm growth and pollutant removal. The experimental conditions are the same as those in Example 1.

[0094] During the start-up operation, it was observed that on the second day of the operation of Filler E (gelatin-chitosan coating), visible biofilms had appeared on the surface, while the surface of Filler D was still relatively clean on the second day and obvious attached biofilms did not appear until the third day. On the seventh day, the attached biomass on the surface of each filler was measured. The average of the Filler E group reached 1.49 mg / cm 2 , which was about 19% higher than 1.25 mg / cm 2 of the Filler D group.

[0095] Further microscopic observations found that in the coating of Filler E, part of the gelatin matrix had been degraded and utilized by the enzymes secreted by microorganisms, and the pores in the original gel were filled with newly grown zoogloea; it can be considered that the coating biomimetic polymer gradually integrated into the biofilm matrix, forming a fusion interface between the coating and the biofilm, which contributed to the stable attachment of the biofilm. In contrast, the PVA coating of Filler D was more inert and stable. Although it provided a hydrophilic surface, its structure was relatively dense, and microorganisms mainly grew by attaching to the surface, and no obvious invasion into the interior of the coating was observed.

[0096] In terms of pollutant removal effect: With the formation of the biofilm, the removal efficiencies of organic matter and ammonia nitrogen in the two reactors gradually increased. On the seventh day of start-up, the effluent COD removal rate of the reactor in the Filler E group was about 87%, slightly better than the COD removal rate of 85% in the Filler D group; by the tenth day, the COD removal rate of the Filler E group had reached 92%, about 5% higher than that of the Filler D group (87%). By the fourteenth day, the COD removal rates of both groups had stabilized at over 95%.

[0097] Regarding ammonia nitrogen removal: By the fourteenth day, the NH4 + -N removal rate of the Filler E group was about 86%, and that of the Filler D group was about 74%, indicating that the gelatin-chitosan coating also had a certain promoting effect on the growth of nitrifying bacteria. This may be related to its higher hydrophilicity and porous structure providing a microenvironment conducive to the attachment of nitrifying bacteria. It should be noted that the fillers with the two coatings had significant advantages compared with the uncoated traditional fillers (the ordinary PE group in Example 1).

[0098] In summary, different hydrogel systems have a certain impact on the bioaffinity of fillers. The PVA cross-linked coating is chemically stable and has high mechanical strength, and is not easily degraded and peeled off during long-term operation, making it suitable for long-term use. The gelatin-chitosan composite coating is more likely to attract microbial attachment and integrate into the biofilm in the initial stage. However, since gelatin and some chitosan in it are natural polymers, they may be gradually degraded by microorganisms during long-term operation, and the coating thickness will be reduced. Therefore, the two coatings have their own advantages and disadvantages: the former focuses on providing stable support, while the latter emphasizes rapid film formation and high affinity in the initial stage. The appropriate coating system can be selected according to actual needs. For example, the gelatin-chitosan system can be selected in cases where rapid startup is required, and the PVA system or more sufficient cross-linking of gelatin-chitosan can be used to improve its stability in systems that emphasize long-term stability.

[0099] Experimental Example 3

[0100] Next, we carried out performance tests on the activated fillers prepared in Example 1 (filler H), Example 5 (filler G), and Example 6 (filler I), and compared them with the control group. Among them, the no-signal-molecule group (control group, filler F): Prepare a PVA hydrogel solution without signal molecules (5% PVA + 0.5% glutaraldehyde, acid-catalyzed, same as before), impregnate and coat a part of the matrix filler and dry and cross-link it to obtain a hydrogel-coated filler without loading any signal molecules. Subsequently, oxygen plasma treatment was carried out to impart hydrophilicity.

[0101] The signal molecule surface coating group (filler J): First, coat the matrix with a PVA solution without signal molecules and dry and cross-link it, and perform plasma treatment (to obtain the same matrix coating as filler F), and then additionally spray the N-octanoyl homoserine lactone signal molecule C10-HSL (concentration 500 μmol / L) on the surface of the coating. The spraying amount is controlled so that the total amount of AHL loaded per unit filler is equivalent to that pre-embedded in filler H. After spraying, the filler was placed in the shade at room temperature for 12 hours to allow the signal molecules to adsorb and adhere to the surface of the coating, obtaining a filler with signal molecules surface-loaded.

[0102] Through the above method, 5 groups of activated fillers with differences in signal molecule loading were obtained. It should be noted that the total amount of signal molecules added in filler H and filler J is equivalent, and the difference is that the former is evenly embedded in the entire hydrogel layer, while the latter is mainly concentrated in the surface layer area.

[0103] Signal release characteristics were tested: Fillers H and J were immersed in sterile pure water to simulate the release behavior of signal molecules in a real water environment. Water samples were taken regularly to measure the AHL concentration. The results showed that filler H (pre-embedded with AHL) released approximately 20% of the signal molecules within the first 24 hours, then maintained a slow release pattern, with the cumulative release reaching approximately 50% of the total by the seventh day, demonstrating a typical sustained-release profile. In contrast, filler J (surface-coated with AHL) released approximately 70% of the AHL within the first six hours after immersion, with cumulative release exceeding 90% within 24 hours. The AHL concentration in the water then rapidly decreased to below the detection limit. This suggests that the surface-coating method concentrates the signal molecules on the surface, where they dissolve rapidly upon contact with water, resulting in high initial concentrations but short-lived release. In contrast, the pre-embedded method temporarily traps the signal molecules within the gel matrix, allowing them to gradually diffuse outward, maintaining a stable signal concentration over a longer period. This result suggests that pre-embedded signal molecules ensure sustained activity throughout the early stages of biofilm formation, not just within the initial day.

[0104] Comparison of Biofilm Formation: The five fillers described above were added to five parallel experimental reactors (experimental conditions remained consistent with those in Example 1). Furthermore, to observe the transient effect of the surface-coated signal, a single dose of AHL equivalent to that released by filler J was added to the control reactors containing filler F at the initial startup (day 1), simulating direct addition of the signal molecule. Significant differences were observed during operation: From day 1, the GI filler (pre-coated with AHL) showed significant bacterial attachment, and the culture medium became slightly turbid (indicating rapid stimulation of microbial activity). In contrast, the filler surface of the F filler (no AHL) remained largely unchanged on day 1. By day 3, a thin, visible biofilm layer had formed on the GI filler surfaces, and the suspended sludge concentration in the reactors increased rapidly, with a COD removal rate reaching approximately 60%. In contrast, the COD removal rate of the F filler group was less than 30% by day 3. On day 5, the dry weight of biofilm per unit surface area measured on the GI filler surfaces was 1.19, 1.52, and 1.46 mg / cm, respectively. 2 The dry weight of biofilm of filler F is only about 0.21 mg / cm 2 After two weeks of continuous operation, the treatment performance of the two groups of reactors gradually approached stability: the COD removal rate of the GI group was stable at more than 95%, and the biomass was 1.86, 2.23 and 2.16 mg / cm, respectively. 2 The COD of filler group F is still only about 83%, and the biomass is 0.93 mg / cm 2The above results indicate that the pre-embedded AHL signal played a positive role in the system startup stage, accelerating the aggregation of microorganisms and the establishment of biofilms, and the effect of accelerating startup and maintaining the microbial retention amount was optimal at a moderate AHL concentration (50 μmol / L). For the effect of packing group J (with AHL coated on the surface), the biomass reached 1.59 mg / cm 2 , slightly higher than that of group H; but thereafter, due to the rapid attenuation of the signal, the overall performance of packing group J after 2 weeks was a COD removal rate of 89% and a biomass of 1.75 mg / cm 2 , which was also better than that of packing group F, but not as good as that of groups G-I. Thus, it can be seen that although instantaneously providing signals on the surface can have a certain effect on rapid film formation in the very early stage, it is not as good as the pre-embedded method in terms of maintaining the biological retention amount for a long time.

[0105] This experimental example proves the influence of the addition of signal molecules (such as AHLs) on the biological performance of the packing and its optimization method: an appropriate amount of signal molecules can significantly shorten the biofilm cultivation and domestication time and improve the initial pollutant removal rate; the method of pre-embedding with hydrogel can achieve the stable release of signal molecules, ensuring continuous action throughout the startup stage, which is more effective than simple surface coating, but both are better than the case of ordinary PE or one-time dosing.

[0106] In summary, the above embodiments fully illustrate the preparation method and performance advantages of the high bio-affinity active packing of the present invention. By selecting a PE substrate doped with NdFeB magnetic powder, and then using a biomimetic hydrogel coating (such as PVA or gelatin / chitosan) to load specific microbial signal molecules, and supplemented with plasma surface modification to enhance hydrophilicity, the prepared packing is significantly superior to traditional packing in terms of biofilm formation speed, initial pollutant removal efficiency, and long-term operation stability. Different doping ratios, different coating materials, and signal molecule addition methods can be optimized and combined according to actual needs to obtain the best performance. For example, when rapid startup of the treatment process is required, a highly hydrophilic natural polymer coating and a higher dose of signal molecules can be pre-embedded; when emphasizing the durable reuse of the packing, a stable synthetic polymer coating and an appropriate reduction of the biodegradable components can be used. Generally speaking, the packing preparation process of the present invention is suitable for large-scale industrial production, and the obtained products can be widely applied to various water supply and wastewater biological treatment systems, significantly improving the startup efficiency and stable operation ability of the systems.

Claims

1. Preparation method of high biological affinity active filler, characterized in that, It includes the following steps: S1. Substrate preparation: Mix polyethylene particles and neodymium iron boron magnets in a weight ratio of 92 - 99:1 - 8, melt and extrude, then cool, stretch and pelletize to obtain a filler substrate; S2. Preparation of hydrogel coating solution: Heat the hydrogel solution to 40 - 50 °C, add a glutaraldehyde solution with a mass concentration of 40 - 60% so that the volume fraction of glutaraldehyde in the hydrogel solution is 0.4 - 0.6%, then add N - octanoyl homoserine lactone signaling molecules so that the molar concentration of N - octanoyl homoserine lactone signaling molecules in the hydrogel solution is 10 - 100 μmol / L, stir evenly and reserve the hydrogel coating solution for later use; S3. Coating: Immerse the filler substrate in the hydrogel coating solution, after impregnation, take out the filler substrate and filter off the excess hydrogel coating solution, heat and dry to obtain a hydrogel - coated filler doped with magnetic powder; S4. Surface treatment: Perform oxygen plasma surface treatment on the hydrogel - coated filler doped with magnetic powder to obtain an active filler.

2. The preparation method of the high bioaffinity active filler according to claim 1, characterized in that, In S1, the melt index of the polyethylene particles is 2 ± 0.2 g / 10 min, and the density is 0.94 - 0.96 g / cm 3 , and the average particle size of the neodymium iron boron magnetic powder is 50 ± 10 μm.

3. The preparation method of the high biological affinity active filler according to claim 1, characterized in that, In S1, during melt extrusion, a twin-screw extruder is used to melt and co-extrude at 140 - 180 °C, and then cooled to room temperature of 25 - 28 °C. The volume of the filler matrix is 10 - 1000 mm 3 .

4. The preparation method of the high biological affinity active filler according to claim 1, characterized in that, In S2, the hydrogel solution is a polyvinyl alcohol hydrogel, and the preparation method of the polyvinyl alcohol hydrogel is: Take industrial - grade polyvinyl alcohol and dissolve it in hot water at a concentration of 5% (w / v) and stir at 85 - 95 °C to obtain a polyvinyl alcohol hydrogel; Meanwhile, after adding the glutaraldehyde solution, add a dilute hydrochloric acid solution to adjust the pH of the hydrogel solution to 3 - 4.

5. The method for preparing a high bioaffinity active filler according to claim 1, characterized in that: In S2, the hydrogel solution is a gelatin - chitosan composite hydrogel, and the preparation method of the gelatin - chitosan composite hydrogel is: Dissolve 2 ± 0.05 g of gelatin in 50 - 80 mL of warm water at 38 - 43 °C until completely dissolved to obtain a gelatin solution, dissolve 1 ± 0.05 g of chitosan in 80 - 100 mL of an acetic acid aqueous solution with a mass concentration of 1 - 2% and stir to dissolve, then add it to the gelatin solution to obtain a mixture, make up water to make the total volume of the mixture 200 mL, and continue to stir evenly to obtain a gelatin - chitosan composite hydrogel.

6. The preparation method of the high biological affinity active filler according to claim 4, wherein, In S3, the immersion time is 3 - 5 min, place the impregnated filler substrate in an oven and heat at 60 - 65 °C for 1 - 1.5 h to complete glutaraldehyde cross - linking and curing, then raise the temperature to 80 - 85 °C and continue to dry for 1 - 1.5 h until the polyvinyl alcohol hydrogel on the surface of the filler substrate is completely dry and firmly attached to obtain a polyvinyl alcohol hydrogel - coated filler.

7. The preparation method of the high biological affinity active filler according to claim 5, characterized in that, In S3, the immersion time is 2 - 3 min, place the impregnated filler substrate on a Teflon plate, first cool it in a refrigerator at 2 - 4 °C for 30 - 40 min to make the gelatin - chitosan composite hydrogel solidify into a gel, then transfer it to an oven at 55 - 65 °C and dry for 1 - 1.5 h to promote the cross - linking reaction, and finally dry at 80 - 85 °C for another 0.5 - 1 h to obtain a gelatin - chitosan composite hydrogel - coated filler.

8. The preparation method of the high biological affinity activity filler according to claim 1, characterized in that, In S4, the method of oxygen plasma surface treatment is: Introduce oxygen into the vacuum chamber where the hydrogel - coated filler is located until the pressure is 28 - 30 Pa, with a power of 30 - 200 W, and treat for 30 - 600 s.

9. Application of the highly bio - compatible active filler prepared by the method according to any one of claims 1 - 8 in water treatment.

10. The application according to claim 9, characterized in that, Apply the active filler to the treatment of toxic and harmful sewage in a moving bed biofilm reactor or a biological contact oxidation process.

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