Process for the preparation of a high bioaffinity active filler and its use in water treatment

Abstract

This invention discloses a method for preparing a highly biocompatible and active filler and its application in water treatment, comprising the following steps: S1, matrix preparation; S2, hydrogel coating solution preparation; S3, coating; S4, surface treatment. This invention significantly improves the biocompatibility and microbial activity stimulation of the filler through coupled magnetic doping, pre-coating with active components, and surface plasma cleaning modification, thereby enhancing the efficiency of microbial metabolic activity enhancement. The resulting filler structure comprises: a polyethylene matrix + an NdFeB magnetic functional core + a biomimetic hydrogel signal coating + a plasma-modified surface, forming a multi-layered, multifunctional integrated filler.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a method for preparing highly biocompatible and active fillers and their application in water treatment. Background Technology

[0002] Biological packing materials are widely used in water treatment and are one of the common methods for in-situ upgrading of activated sludge processes. However, when the content of nutrients in the wastewater is low, or when treating toxic and harmful wastewater (such as refining wastewater, pharmaceutical wastewater, etc.), the commonly used packing materials generally suffer from problems such as low biofilm formation efficiency, poor microbial activity, and low loading capacity.

[0003] Wastewater treatment processes such as moving bed biofilm reactors (MBBR) and biological contact oxidation improve treatment efficiency by adding packing materials to the reactor to promote the attachment and growth of microorganisms in the form of a biofilm. The packing materials provide a high specific surface area for attachment, allowing microorganisms to immobilize and form a stable biofilm, achieving efficient degradation of organic pollutants and ammonia nitrogen. Introducing packing materials into the traditional activated sludge process to form a sludge-film hybrid process can simultaneously utilize the synergistic effect of suspended sludge and attached biofilm, improving the system's resistance to shock loads and shortening the retention time.

[0004] However, existing packing materials (usually polyethylene or polypropylene plastics) have limited biocompatibility due to their hydrophobic and smooth surfaces, often resulting in slow biofilm formation rates, low initial biomass, and long system start-up periods. Microbial cells struggle to rapidly adhere and colonize on hydrophobic surfaces, often requiring several weeks to form a stable biofilm, leading to prolonged process start-up and commissioning times. Poor affinity between the packing material and microorganisms results in insufficient attached biomass, affecting pollutant removal efficiency and potentially causing biofilm detachment due to weak adhesion. Furthermore, the lack of active components in existing packing materials makes it difficult to fully stimulate microbial metabolic activity, leading to unsatisfactory packing addition effects when wastewater has low nutrient content or when treating toxic or hazardous wastewater (such as refining wastewater or pharmaceutical wastewater).

[0005] Therefore, there is an urgent need to improve the biocompatibility of packing materials by modifying their surface properties and functional components, develop highly biocompatible packing materials for water treatment, accelerate biofilm formation, and enhance the metabolic activation function of the packing materials for microorganisms. Some studies have investigated the rate of biofilm formation.

[0006] For example, patent CN201310088443 uses synthetic polymer particles as a base material, adds microporous biocompatible substances or their modified forms, and adds natural substances that simultaneously and continuously generate negative ions and far-infrared rays. These substances are then thoroughly mixed with a dispersant in a mixer to produce various types of fillers. Patent CN201610854649 adds fillers and magnetic diatomaceous earth to a traditional process formula, resulting in a high-affinity organic biological filler that maintains physical strength and lifespan while having a density closer to water, a larger specific surface area than similar products, a rougher surface, and rapid biofilm growth. 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] To address the aforementioned problems, this invention provides a method for preparing highly biocompatible and active fillers and their application in water treatment.

[0008] The technical solution of this invention is:

[0009] A method for preparing highly biocompatible and active fillers includes the following steps:

[0010] S1. Matrix preparation: Polyethylene particles and neodymium iron boron magnets are mixed at a weight ratio of 92-99:1-8, melt-extruded, cooled, stretched and granulated to obtain the filler matrix;

[0011] S2. Preparation of hydrogel coating solution: After heating the hydrogel solution to 40-50℃, add glutaraldehyde solution with a mass concentration of 40-60% to make the volume fraction of glutaraldehyde in the hydrogel solution 0.4-0.6%. Then add N-octanoylhomoserine lactone signal molecules to make the molar concentration of N-octanoylhomoserine lactone signal molecules in the hydrogel solution 10-100 μmol / L. After stirring evenly, the hydrogel coating solution is obtained for later use.

[0012] S3. Coating: The filler matrix is ​​immersed in the hydrogel coating liquid. After immersion, the filler matrix is ​​removed, excess hydrogel coating liquid is filtered out, and the filler is dried by heating to obtain a hydrogel-coated filler doped with magnetic powder.

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

[0014] Furthermore, in S1, the polyethylene particles have a melt index of 2 ± 0.2 g / 10 min and a density of 0.94–0.96 g / cm³. 3 The average particle size of the neodymium iron boron magnetic powder is 50±10μm.

[0015] Furthermore, in S1, the melt extrusion is performed using a twin-screw extruder at 140–180°C, followed by cooling to room temperature (25–28°C), and the filler matrix volume is 10–1000 mm³. 3 .

[0016] The magnetic enhancement mechanism of adding neodymium iron boron magnetic powder is as follows: the embedded neodymium iron boron magnetic powder endows the filler with the property of activating microbial metabolism. The constant weak magnetic field provided by the neodymium iron boron magnetic powder (especially in the range of magnetic field strength 0.3 to 1.2 mT) helps to activate certain physiological activities of microorganisms (it has been reported that weak magnetic fields can increase the activity of ferromagnetic ion proteins), thereby 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] Industrial grade polyvinyl alcohol was dissolved in hot water at 85-95℃ at a concentration of 5% (w / v) and stirred to obtain polyvinyl alcohol hydrogel.

[0019] Meanwhile, after adding glutaraldehyde solution, dilute hydrochloric acid solution is added 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±0.05g of gelatin in 50-80mL of warm water at 38-43℃ until completely dissolved to obtain a gelatin solution. Dissolve 1±0.05g of chitosan in 80-100mL of 1-2% acetic acid aqueous solution and stir until dissolved. Add the solution to the gelatin solution to obtain a mixture. Add water to make the total volume of the mixture 200mL and continue stirring until homogeneous to obtain a gelatin-chitosan composite hydrogel.

[0022] Furthermore, in S3, the immersion time is 3-5 minutes. The impregnated filler matrix is ​​placed in an oven and heated at 60-65°C for 1-1.5 hours to complete the glutaraldehyde crosslinking and curing. Then, the temperature is raised to 80-85°C and drying is continued for 1-1.5 hours until the polyvinyl alcohol hydrogel on the surface of the filler matrix is ​​completely dry and firmly adhered, thus obtaining polyvinyl alcohol hydrogel coated filler.

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

[0024] The mechanism by which hydrogels 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, possessing a high water content and a soft three-dimensional network structure that attracts and temporarily retains cells in the aqueous phase. The viscoelasticity of the hydrogel provides a buffering effect, reducing the impact of shear forces on initially attached bacteria during aeration and mixing, making it less likely for early-attached microorganisms to be washed away. Simultaneously, quorum sensing signaling molecules pre-embedded in the hydrogel are slowly released in the hydration environment or distributed in a gradient on the coating surface, acting as inducers of microbial chemotaxis and physiological activation. When a small number of microorganisms attach to the coating, these signaling molecules can rapidly promote inter-microbial communication, inducing the attached bacteria to initiate the expression of genes related to biofilm development, such as producing more sticky EPS and flagella, and biofilm matrix. Even when the overall bacterial concentration in external wastewater is low, the signaling molecules can still reach a threshold concentration in the local microenvironment, thereby accelerating the process of quorum sensing-triggered biofilm formation. Furthermore, the hydrophilicity and biocompatibility of the hydrogel coating itself facilitate the co-attachment of different types of microorganisms. Its surface can adsorb some nutrients or trace elements, providing favorable nutritional and signaling conditions for the initial biofilm. This "bionic substrate" effectively bridges the interfacial differences between the inorganic carrier and the living bacterial flocs, so that the packing material itself has a microenvironment conducive to colonization and growth as soon as it comes into contact with sewage.

[0025] Furthermore, in S4, the method for oxygen plasma surface treatment is as follows:

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

[0027] The plasma modification mechanism is as follows: plasma surface treatment, as the final step, further enhances the overall surface activity of the filler. For the exposed polyethylene matrix, plasma bombardment can etch nanoscale rough textures and introduce oxygen-containing functional groups such as hydroxyl and carbonyl groups onto the molecular chains, significantly reducing the water contact angle of the substrate surface and increasing wettability. The treatment only takes a few seconds to significantly increase the oxygen content of the plastic surface and maintain a certain level of stability. For areas coated with hydrogel, plasma discharge can also generate some free radicals or functional groups on the hydrogel surface, which may form slight cross-linking or bonding, thereby making the hydrogel coating more tightly bonded to the substrate surface and less prone to peeling. 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-adhere properties, continuously attracting subsequent flowing microorganisms to adhere to it.

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

[0029] Furthermore, the active packing material can be applied to the treatment of toxic and harmful wastewater in moving bed biofilm reactors or biological contact oxidation processes.

[0030] The beneficial effects of this invention are:

[0031] (1) This invention significantly improves the biocompatibility and microbial activity stimulation of the filler by coupling magnetic doping, pre-coating of active components and surface plasma cleaning modification, thereby enhancing the efficiency of microbial metabolic activity enhancement. The filler is made of polyethylene as a base material to form a hollow ring or short tubular carrier, and a certain proportion of neodymium iron boron (NdFeB) micro magnetic powder is uniformly mixed inside to give the filler body a lasting magnetic property. A biomimetic hydrogel coating is pre-coated on its surface. A small amount of microbial signal molecules (such as quorum sensing self-inducers) or other bioactive substances are pre-introduced into the hydrogel to build an initial active "biofilm induction layer" on the filler surface. Finally, the coated filler is subjected to low-temperature plasma surface treatment to further improve the energy and polar functional group content of its outer surface. The resulting filler structure includes: polyethylene matrix + NdFeB magnetic functional core + biomimetic hydrogel signal coating + plasma modified surface, forming a multi-layered and multifunctional integrated filler.

[0032] (2) The high bio-affinity and active packing material prepared by the present invention can be applied to water treatment, accelerate the biofilm formation efficiency of microorganisms in moving bed biofilm reactors or biological contact oxidation processes, improve microbial activity and loading, thereby improving the treatment efficiency of toxic and harmful wastewater. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the active filler prepared in this invention;

[0034] Figure 2 This is a schematic diagram of the gel layer containing signal-loaded molecules, displayed under an optical microscope, of the active filler prepared in this invention.

[0035] Figure 3 The scanning electron microscope shows the surface morphology of the modified filler prepared in this invention.

[0036] Figure 4 This is a graph showing the biofilm initiation test results of each group of packing materials in Experimental Example 1 of the present invention;

[0037] Figure 5 This is a graph showing the biofilm initiation test results of each group of packing materials in Experimental Example 2 of the present invention;

[0038] Figure 6 This is a graph showing the biofilm formation start-up test results of each group of packing materials in Experimental Example 3 of the present invention. Detailed Implementation

[0039] Example 1

[0040] A method for preparing highly biocompatible and active fillers includes the following steps:

[0041] S1. Matrix Preparation: Polyethylene particles and neodymium iron boron magnets were mixed at a weight ratio of 99:1. The polyethylene particles had a melt flow index of 2 g / 10 min and a density of 0.95 g / cm³. 3 The average particle size of the neodymium iron boron magnetic powder is 50±10μm. After melt extrusion, it is cooled, stretched, and pelletized to obtain a columnar filler matrix. The melt extrusion is performed using a twin-screw extruder at 160℃, followed by cooling to room temperature (26℃). The columnar filler matrix has a diameter of 5mm, a length of 5mm, and a volume of 98.17mm³. 3 ;

[0042] S2. Preparation of hydrogel coating solution: The hydrogel solution is polyvinyl alcohol hydrogel. Industrial grade polyvinyl alcohol is dissolved in hot water at 90℃ at a concentration of 5% (w / v) and stirred to obtain polyvinyl alcohol hydrogel. After heating the polyvinyl alcohol hydrogel solution to 45℃, a 50% glutaraldehyde solution is added to make the volume fraction of glutaraldehyde in the hydrogel solution 0.5%. After adding the glutaraldehyde solution, dilute hydrochloric acid solution is added to adjust the pH of the hydrogel solution to 3.5. Then, N-octanoylhomoserine lactone signal molecules are added to make the molar concentration of N-octanoylhomoserine lactone signal molecules in the hydrogel solution 50 μmol / L. After stirring evenly, the hydrogel coating solution is obtained for later use.

[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 at 62°C for 1.2 hours to complete the 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 adhered, thus obtaining the polyvinyl alcohol hydrogel coated filler.

[0044] S4. Surface Treatment: The hydrogel-coated filler doped with magnetic powder is subjected to oxygen plasma surface treatment. Oxygen is introduced into a vacuum chamber to a pressure of 29 Pa, a power of 150 W, and the treatment lasts for 600 seconds to obtain the active filler. Figure 1 As shown.

[0045] Example 2

[0046] The difference between this embodiment and Embodiment 1 is that:

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

[0048] Example 3

[0049] The difference between this embodiment and Embodiment 1 is that:

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

[0051] Example 4

[0052] The difference between this embodiment and Embodiment 1 is that:

[0053] In S2, the hydrogel solution is a gelatin-chitosan composite hydrogel. 2g of gelatin is dissolved in 60mL of 40℃ warm water until completely dissolved to obtain a gelatin solution. 1g of chitosan is dissolved in 900mL of 1.5% acetic acid aqueous solution and stirred until dissolved. This solution is then added to the gelatin solution to obtain a mixture. Water is added to make the total volume of the mixture 200mL. Stirring is continued until homogeneous to obtain the gelatin-chitosan composite hydrogel.

[0054] In S3, the immersion time is 2 minutes. The impregnated filler matrix is ​​placed on a Teflon plate and first placed in a 3°C refrigerator for 35 minutes to allow the gelatin-chitosan composite hydrogel to solidify into a gel. Then, it is transferred to a 60°C oven for 1 hour to promote the cross-linking reaction. Finally, it is dried at 82°C for another 1 hour to obtain the gelatin-chitosan composite hydrogel coated filler.

[0055] Example 5

[0056] The difference between this embodiment and Embodiment 1 is that:

[0057] The molar concentration of N-octanoylhomoserine lactone signaling molecule in the hydrogel solution was 10 μmol / L.

[0058] Example 6

[0059] The difference between this embodiment and Embodiment 1 is that:

[0060] The molar concentration of N-octanoylhomoserine lactone signaling molecule in the hydrogel solution was 100 μmol / L.

[0061] Example 7

[0062] The difference between this embodiment and Embodiment 1 is that:

[0063] S1. Matrix Preparation: Polyethylene granules and neodymium iron boron magnets were mixed at a weight ratio of 99:1. The polyethylene granules had a melt flow index of 1.8 g / 10 min and a density of 0.94 g / cm³. 3 The average particle size of the neodymium iron boron magnetic powder is 50±10μm. After melt extrusion, it is cooled, stretched, and pelletized to obtain the filler matrix. The melt extrusion is performed using a twin-screw extruder at 140℃, followed by cooling to room temperature (25℃). The volume of the filler matrix is ​​10mm. 3 ;

[0064] S2. Preparation of hydrogel coating solution: The hydrogel solution is polyvinyl alcohol hydrogel. Industrial grade polyvinyl alcohol is dissolved in hot water at 85℃ at a concentration of 5% (w / v) and stirred to obtain polyvinyl alcohol hydrogel. After heating the polyvinyl alcohol hydrogel solution to 40℃, a 40% glutaraldehyde solution is added to make the volume fraction of glutaraldehyde in the hydrogel solution 0.4%. After adding the glutaraldehyde solution, dilute hydrochloric acid solution is added to adjust the pH of the hydrogel solution to 3. Then, N-octanoylhomoserine lactone signal molecules are added to make the molar concentration of N-octanoylhomoserine lactone signal molecules in the hydrogel solution 50 μmol / L. After stirring evenly, the hydrogel coating solution is obtained for later use.

[0065] S3. Coating: Immerse the filler matrix in the hydrogel coating liquid for 3 minutes. Place the impregnated filler matrix in an oven and heat it at 60°C for 1 hour to complete the glutaraldehyde crosslinking and curing. Then raise the temperature to 80°C and continue drying for 1 hour until the polyvinyl alcohol hydrogel on the surface of the filler matrix is ​​completely dry and firmly attached, thus obtaining polyvinyl alcohol hydrogel coated filler.

[0066] S4. Surface treatment: The hydrogel-coated filler with magnetic powder is subjected to oxygen plasma surface treatment. Oxygen is introduced into the hydrogel-coated filler in a vacuum chamber to a pressure of 28 Pa and a power of 30 W for 600 s to obtain the active filler.

[0067] Example 8

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

[0069] S1. Matrix Preparation: Polyethylene particles and neodymium iron boron magnets were mixed at a weight ratio of 99:1. The polyethylene particles had a melt flow index of 2.2 g / 10 min and a density of 0.96 g / cm³. 3 The average particle size of the neodymium iron boron magnetic powder is 50±10μm. After melt extrusion, it is cooled, stretched, and pelletized to obtain the filler matrix. The melt extrusion is performed using a twin-screw extruder at 180℃, followed by cooling to room temperature (28℃). The volume of the filler matrix is ​​1000mm³. 3 ;

[0070] S2. Preparation of hydrogel coating solution: The hydrogel solution is polyvinyl alcohol hydrogel. Industrial grade polyvinyl alcohol is dissolved in hot water at 95℃ at a concentration of 5% (w / v) and stirred to obtain polyvinyl alcohol hydrogel. After heating the polyvinyl alcohol hydrogel solution to 50℃, a 60% glutaraldehyde solution is added to make the volume fraction of glutaraldehyde in the hydrogel solution 0.6%. After adding the glutaraldehyde solution, dilute hydrochloric acid solution is added to adjust the pH of the hydrogel solution to 4. Then, N-octanoylhomoserine lactone signal molecules are added to make the molar concentration of N-octanoylhomoserine lactone signal molecules in the hydrogel solution 50 μmol / L. After stirring evenly, the hydrogel coating solution is obtained for later use.

[0071] S3. Coating: Immerse the filler matrix in the hydrogel coating solution for 5 minutes. Place the immersed filler matrix in an oven and heat at 65°C for 1.5 hours to complete the glutaraldehyde crosslinking and curing. Then raise the temperature to 85°C and continue drying for 1.5 hours until the polyvinyl alcohol hydrogel on the surface of the filler matrix is ​​completely dry and firmly adhered, thus obtaining the polyvinyl alcohol hydrogel coated filler.

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

[0073] Example 9

[0074] The difference between this embodiment and embodiment 4 is that:

[0075] In S2, the hydrogel solution is a gelatin-chitosan composite hydrogel. 1.95g of gelatin is dissolved in 50mL of warm water at 38-43℃ until completely dissolved to obtain a gelatin solution. 0.95g of chitosan is dissolved in 80mL of 1% acetic acid aqueous solution and stirred until dissolved. The solution is then added to the gelatin solution to obtain a mixture. Water is added to make the total volume of the mixture 200mL. Stirring is continued until homogeneous to obtain the gelatin-chitosan composite hydrogel.

[0076] In S3, the immersion time is 2 minutes. The impregnated filler matrix is ​​placed on a Teflon plate and first placed in a 2°C refrigerator for 30 minutes to allow the gelatin-chitosan composite hydrogel to solidify into a gel. Then, it is transferred to a 55°C oven for 1 hour to promote the cross-linking reaction. Finally, it is dried at 80°C for 0.5 hours to obtain the gelatin-chitosan composite hydrogel coated filler.

[0077] Example 10

[0078] The difference between this embodiment and embodiment 4 is that:

[0079] In S2, the hydrogel solution is a gelatin-chitosan composite hydrogel. 2.05g of gelatin is dissolved in 80mL of 43℃ warm water until completely dissolved to obtain a gelatin solution. 1.05g of chitosan is dissolved in 100mL of 2% acetic acid aqueous solution and stirred until dissolved. The solution is then added to the gelatin solution to obtain a mixture. Water is added to make the total volume of the mixture 200mL. Stirring is continued until homogeneous to obtain the gelatin-chitosan composite hydrogel.

[0080] In S3, the immersion time is 3 minutes. The impregnated filler matrix is ​​placed on a Teflon plate and first placed in a 4°C refrigerator for 40 minutes to allow the gelatin-chitosan composite hydrogel to solidify into a gel. Then, it is transferred to a 65°C oven for 1.5 hours to promote the cross-linking reaction. Finally, it is dried at 85°C for 1 hour to obtain the gelatin-chitosan composite hydrogel coated filler.

[0081] Example 11

[0082] This embodiment describes the application of the highly biocompatible active packing material prepared in Example 1, applying the active packing material prepared in S4 to water treatment.

[0083] Example 12

[0084] This embodiment is an application of the highly biocompatible active packing material prepared in Example 1. The active packing material prepared in S4 is applied to the biological contact oxidation process for the treatment of toxic and harmful wastewater.

[0085] Example 13

[0086] This embodiment is an application of the high bioaffinity active packing material prepared in Example 1. The active packing material prepared in S4 is applied to the treatment of toxic and harmful wastewater in a moving bed biofilm reactor.

[0087] Experimental Example 1

[0088] Below, we conduct performance tests on the active fillers prepared in Examples 1-3: mainly comparing the effects of the NdFeB doping ratio on the filler performance in promoting microbial film formation and overall performance. The fillers in Examples 1-3 are designated as A, B, and C, respectively, with average magnetic properties of 0.1, 0.7, and 1.2 mT for A, B, and C.

[0089] Three groups of packing materials, along with ordinary PE packing material (as a control group), were placed in four parallel small-scale biological contact oxidation reactors for biofilm formation start-up tests. The reactors had identical volumes, were inoculated with the same activated sludge, and were fed the same culture medium (simulating organic wastewater, with initial chemical oxygen demand (COD) of approximately 300 mg / L and ammonia nitrogen (NH3) of... 4+ -N approximately 30 mg / L) was continuously operated for 30 days under aerobic conditions at 25°C.

[0090] Observations showed that on the third day of operation, a thin layer of microorganisms was visible on the surface of packing material B (5% NdFeB). Packing materials A and C did not show obvious biofilms until the fourth day, while ordinary PE packing material did not show obvious biofilms until the seventh day. On the tenth day of operation, the biomass of each group of packing materials was measured (calculated as volatile suspended solids (VSS) per unit surface area of ​​packing material). The results showed that the average biomass of packing material B was 1.30 mg / cm³. 2 It is higher than the 0.95 mg / cm³ of packing group A. 2 And 1.02 mg / cm of packing group C 2 The biomass of the ordinary PE group is 0.62 mg / cm³. 2 The amount of biofilm attached to the filler is more than twice that of the original filler, which shows that the filler of the present invention significantly increases the amount of biofilm attached in the initial stage.

[0091] Regarding organic matter removal performance, the COD removal rate of each packing group gradually increased with biofilm growth. Among them, the COD removal rate of the reactor with packing group B, doped with 5% NdFeB, reached 85% on day 7, higher than the 78% of group A (doped with 1% NdFeB) and the 82% of group C (doped with 8% NdFeB). After two weeks of operation, the COD removal rate of all groups stabilized above 90%, higher than the 84% of ordinary PE packing. Ammonia nitrogen removal showed no significant difference initially due to the slow proliferation of nitrifying bacteria; however, by day 14, the NH3 removal rate of group B increased significantly. 4+ The N-N removal rate was approximately 75%, slightly higher than Group A's 70% and Group C's 72%, but significantly higher than the 47% of the ordinary PE filler group. Overall, a moderate NdFeB doping ratio (e.g., 5%) helps increase the surface micro-roughness and magnetism of the filler without affecting coating uniformity, promoting faster microbial attachment and growth, thus exhibiting optimal biofilm initiation performance. However, in general, fillers within the doping range described in this method exhibit significantly better biocompatibility than traditional uncoated fillers.

[0092] Experiment Example 2

[0093] Below, we will conduct performance tests on the active packings prepared in Examples 2 (packing D) and 4 (packing E): Packing D and packing E were respectively put into two identical experimental bioreactors (consistent with the reactor used in Example 1) for parallel operation tests to compare the effects of different coatings on biofilm growth and pollutant removal. The experimental conditions were the same as in Example 1.

[0094] During the start-up process, it was observed that on the second day of operation, a visible biofilm appeared on the surface of packing material E (gelatin-chitosan coating), while the surface of packing material D was relatively clean on the second day, and a significant biofilm only appeared on the third day. On the seventh day, the biofilm density on the surface of each packing material was measured, with packing material E averaging 1.49 mg / cm³. 2 Approximately 1.25 mg / cm³ compared to packing group D. 2 19% higher.

[0095] Further microscopic observation revealed that in the coating of filler E, some of the gelatin matrix had been degraded and utilized by enzymes secreted by microorganisms, and the pores in the original gel were filled by newly grown bacterial flocs. It can be considered that the biomimetic polymer of the coating gradually integrates into the biofilm matrix, forming a fusion interface between the coating and the biofilm, which contributes to the stable adhesion of the biofilm. In contrast, the PVA coating of filler D is more inert and stable. Although it provides a hydrophilic surface, its structure is relatively dense, and microorganisms mainly attach and grow on the surface, with no significant intrusion into the coating's interior observed.

[0096] Regarding pollutant removal efficiency: With the formation of the biofilm, the removal efficiency of organic matter and ammonia nitrogen in both reactors gradually increased. On the 7th day of startup, the COD removal rate of the effluent from reactor group E was approximately 87%, slightly better than the 85% COD removal rate of reactor group D. By the 10th day, the COD removal rate of reactor group E had reached 92%, about 5% higher than that of reactor group D (87%). By the 14th day, the COD removal rates of both groups tended to a stable level above 95%.

[0097] Regarding ammonia nitrogen removal: By day 14, the NH4 content in packing group E was... + The nitrogen removal rate was approximately 86% for group D and approximately 74% for group D, indicating that the gelatin-chitosan coating also promotes the growth of nitrifying bacteria. This may be related to its higher hydrophilicity and porous structure providing a favorable microenvironment for nitrifying bacteria attachment. Notably, both coated packings showed significant advantages over the unmodified conventional packings (the ordinary PE group in Example 1).

[0098] In summary, different hydrogel systems have a certain impact on the biocompatibility of fillers. PVA cross-linked coatings are chemically stable and have high mechanical strength, making them less prone to degradation and detachment during long-term operation, and suitable for long-term use. Gelatin-chitosan composite coatings are more likely to attract microorganisms to attach and integrate into the biofilm initially, but because gelatin and some chitosan are natural polymers, they may be gradually degraded by microorganisms over a longer period of operation, resulting in a reduction in coating thickness. Therefore, both coatings have their advantages and disadvantages: the former focuses on providing stable support, while the latter emphasizes rapid initial biofilm formation and high affinity. The appropriate coating system can be selected based on actual needs. For example, the gelatin-chitosan system can be used in applications requiring rapid start-up, while the PVA system or more thorough cross-linking of the gelatin-chitosan can be used in systems that emphasize long-term stability to improve its stability.

[0099] Experimental Example 3

[0100] Below, we conduct performance tests on the active fillers prepared in Examples 1 (filler H), 5 (filler G), and 6 (filler I), and compare them with the control group. The control group (filler F) contains no signal molecules: a PVA hydrogel solution (5% PVA + 0.5% glutaraldehyde, acid catalysis, as before) was prepared, and a portion of the matrix filler was impregnated, coated, dried, and crosslinked to obtain a hydrogel coating filler without any signal molecules. Subsequently, oxygen plasma treatment was performed to impart hydrophilicity.

[0101] Signal molecule surface coating group (filler J): First, the substrate is coated with a PVA solution without signal molecules, dried and cross-linked, and then plasma treated (to obtain a substrate coating identical to that of filler F). Then, N-octanoylhomoserine lactone signal molecule C10-HSL (concentration 500 μmol / L) is additionally sprayed onto the coating surface. The spraying amount is controlled so that the total AHL loaded per unit of filler is equivalent to that pre-embedded in filler H. After spraying, the filler is placed at room temperature to air dry for 12 hours, allowing the signal molecules to be adsorbed and fixed on the coating surface, resulting in a filler with surface-loaded signal molecules.

[0102] Using the above method, five groups of active fillers with differences in signal molecule loading were obtained. It should be noted that the total amount of signal molecules added to filler H and filler J is roughly the same; the difference lies in that the former is uniformly embedded throughout the entire hydrogel layer, while the latter is mainly concentrated in the surface region.

[0103] Signal release characteristic test: Packing material H and packing material J were immersed in sterile pure water to simulate the release behavior of signal molecules in a real aquatic environment. Water samples were taken periodically to detect the AHL concentration. The results showed that packing material H (pre-embedded AHL) released about 20% of the signal molecules in the first 24 hours, and then maintained a slow release state, with the cumulative release reaching about 50% of the total by day 7, exhibiting typical slow-release characteristics. In contrast, packing material J (surface-coated AHL) released about 70% of the AHL in the first 6 hours after immersion, and the cumulative release exceeded 90% within 24 hours, after which the AHL concentration in the water rapidly decreased below the detection limit. It can be seen that the surface coating method causes a large number of signal molecules to concentrate on the surface, dissolve rapidly upon contact with water, and has a high initial concentration but a short duration; while the pre-embedded method allows the signal molecules to be temporarily retained by the gel matrix and gradually diffuse outward, providing a stable signal concentration over a longer period of time. This result indicates that pre-embedded signal molecules can ensure continuous function throughout the entire early stage of biofilm attachment, and not just in the first day.

[0104] Comparison of biofilm formation effects: The five types of packing materials were added to five parallel experimental reactors (experimental conditions were consistent with Example 1). Furthermore, to observe the instantaneous effect of the surface coating signal, an AHL dose equivalent to that released by packing group J was added once during the initial startup phase (day 1) of the control group (packing group F) to simulate the direct addition of signal molecules. During operation, significant differences were observed: Packing group GI (coated with pre-embedded AHL) showed a large number of bacteria adhering to it from day 1, and the culture medium became slightly turbid (indicating rapid activation of microbial activity); while packing group F (without AHL) showed virtually no change on the packing surface on day 1. By day 3, a thin, visible biofilm layer had formed on the surface of packing group GI, and the suspended sludge concentration in the reactor increased rapidly, with a COD removal rate reaching approximately 60%. In contrast, the COD removal rate of packing group F was less than 30% by day 3. On day 5, the dry weight of the biofilm per unit surface area on the packing surface of packing group GI was measured to be 1.19, 1.52, and 1.46 mg / cm³, respectively. 2 The dry weight of the biofilm using filler F is only about 0.21 mg / cm³. 2 After two weeks of continuous operation, the treatment performance of both reactors gradually approached stability: the COD removal rate of the GI packing group remained stable at over 95%, with biomass of 1.86, 2.23, and 2.16 mg / cm³, respectively. 2 The COD of packing material group F was still only about 83%, and the biomass was 0.93 mg / cm³. 2The above results indicate that the pre-embedded AHL signal played a positive role in the system startup phase, accelerating microbial aggregation and biofilm establishment. Furthermore, the optimal AHL concentration (50 μmol / L) showed the best effect in accelerating startup and maintaining microbial retention. For group J (surface coated with AHL), the biomass reached 1.59 mg / cm³ on day 5. 2 The COD removal rate was slightly higher than that of group H; however, due to rapid signal attenuation thereafter, after 2 weeks, the overall performance of group J was 89% COD removal rate and 1.75 mg / cm³ biomass. 2 While it is worse than filler group F, it is not as good as group GI. This shows that although the instantaneous signal provided by 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 maintaining the amount of bioretention over a long period of time.

[0105] This experimental example demonstrates the impact of adding signaling molecules (such as AHL-type) on the biocompatibility of the packing material and its optimization methods: an appropriate amount of signaling molecules can significantly shorten the biofilm cultivation and acclimatization time and improve the initial pollutant removal rate; the method of pre-embedding with hydrogel can achieve stable release of signaling molecules, ensuring that they continue to play a role throughout the start-up phase, which is more effective than simple surface coating, but better than ordinary PE or one-time addition.

[0106] In summary, the above embodiments fully illustrate the preparation method and performance advantages of the high biocompatibility and activity filler of the present invention. By selecting a PE substrate incorporating NdFeB magnetic powder, then using a biomimetic hydrogel coating (such as PVA or gelatin / chitosan) to load specific microbial signaling molecules, and further enhancing hydrophilicity through plasma surface modification, the resulting filler significantly outperforms traditional fillers in terms of biofilm formation rate, initial pollutant removal efficiency, and long-term operational stability. Different doping ratios, different coating materials, and signaling molecule addition methods can be optimized and combined according to actual needs to obtain the best performance. For example, when a rapid start-up process is required, a highly hydrophilic natural polymer coating can be used with a higher dose of signaling molecules pre-embedded; when the durability and reusability of the filler are emphasized, a stable synthetic polymer coating can be used with an appropriate reduction in degradable components. Overall, the filler preparation process of the present invention is suitable for large-scale industrial production, and the resulting product can be widely used in various water supply and wastewater biological treatment systems, significantly improving the system's start-up efficiency and stable operation capability.

Claims

1. A method for preparing a highly biocompatible and active filler, characterized in that, Includes the following steps: S1. Matrix preparation: Polyethylene particles and neodymium iron boron magnetic powder are mixed at a weight ratio of 92-99:1-8, melt-extruded, cooled, stretched and granulated to obtain the filler matrix; S2. Preparation of hydrogel coating solution: After heating the hydrogel solution to 40-50℃, add glutaraldehyde solution with a mass concentration of 40-60% to make the volume fraction of glutaraldehyde in the hydrogel solution 0.4-0.6%. Then add N-octanoylhomoserine lactone signal molecules to make the molar concentration of N-octanoylhomoserine lactone signal molecules in the hydrogel solution 10-100 μmol / L. After stirring evenly, the hydrogel coating solution is obtained for later use. S3. Coating: The filler matrix is ​​immersed in the hydrogel coating liquid. After immersion, the filler matrix is ​​removed, excess hydrogel coating liquid is filtered out, and the filler is dried by heating to obtain a hydrogel-coated filler doped with magnetic powder. S4. Surface treatment: The hydrogel-coated filler with doped magnetic powder is subjected to oxygen plasma surface treatment to obtain an active filler.

2. The method for preparing the highly biocompatible filler according to claim 1, characterized in that, In S1, the melt flow index of the polyethylene granules is 2 ± 0.2 g / 10 min, and the density is 0.94–0.96 g / cm³. 3 The average particle size of the neodymium iron boron magnetic powder is 50±10μm.

3. The method for preparing the highly biocompatible filler according to claim 1, characterized in that, In S1, melt extrusion is performed using a twin-screw extruder at 140–180°C, followed by cooling to room temperature (25–28°C). The filler matrix volume is 10–1000 mm³. 3 .

4. The method for preparing the highly biocompatible 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 as follows: Industrial grade polyvinyl alcohol was dissolved in hot water at 85-95℃ at a concentration of 5% (w / v) and stirred to obtain polyvinyl alcohol hydrogel. Meanwhile, after adding glutaraldehyde solution, dilute hydrochloric acid solution is added to adjust the pH of the hydrogel solution to 3-4.

5. The method for preparing the highly biocompatible 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 as follows: Dissolve 2±0.05g of gelatin in 50-80mL of warm water at 38-43℃ until completely dissolved to obtain a gelatin solution. Dissolve 1±0.05g of chitosan in 80-100mL of 1-2% acetic acid aqueous solution and stir until dissolved. Add the solution to the gelatin solution to obtain a mixture. Add water to make the total volume of the mixture 200mL and continue stirring until homogeneous to obtain a gelatin-chitosan composite hydrogel.

6. The method for preparing the highly biocompatible filler according to claim 4, characterized in that, In S3, the immersion time is 3-5 minutes. The impregnated filler matrix is ​​placed in an oven and heated at 60-65°C for 1-1.5 hours to complete the glutaraldehyde crosslinking and curing. Then, the temperature is raised to 80-85°C and drying is continued for 1-1.5 hours until the polyvinyl alcohol hydrogel on the surface of the filler matrix is ​​completely dry and firmly attached, thus obtaining polyvinyl alcohol hydrogel coated filler.

7. The method for preparing the highly biocompatible filler according to claim 5, characterized in that, In S3, the immersion time is 2-3 minutes. The impregnated filler matrix is ​​placed on a Teflon plate and first placed in a refrigerator at 2-4℃ for 30-40 minutes to allow the gelatin-chitosan composite hydrogel to solidify into a gel. Then, it is transferred to an oven at 55-65℃ to dry for 1-1.5 hours to promote the cross-linking reaction. Finally, it is dried at 80-85℃ for 0.5-1 hour to obtain the gelatin-chitosan composite hydrogel coated filler.

8. The method for preparing the highly biocompatible filler according to claim 1, characterized in that, In S4, the oxygen plasma surface treatment method is as follows: The hydrogel-coated filler is placed in a vacuum chamber and oxygen is introduced to a pressure of 28–30 Pa, a power of 30–200 W, and the treatment lasts for 30–600 s.

9. The application of the highly biocompatible active filler prepared by the method according to any one of claims 1 to 8 in water treatment.

10. The application as described in claim 9, characterized in that, The active packing material is applied to the treatment of toxic and harmful wastewater in a moving bed biofilm reactor or a biological contact oxidation process.

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