Composite biological filler, preparation method and sewage treatment method and system

Abstract

The present invention discloses a composite biological filler, which comprises: an inner core, the structure of the inner core comprises Fe3O4 nanoparticles and PEI synchronously loaded by polyurethane sponge, the loading amount of Fe3O4 is 6-8 wt% of the mass of the inner core, and the PEI grafting density is 1.5-2.0 mg / cm < 2 >; the outer layer structurally comprises a pure PEI modified polyurethane sponge layer wrapping the inner core, and the PEI grafting density is 2.0-3.0 mg / cm < 2 >; and the bonding layer is positioned between the inner core and the outer layer and is made of sodium alginate or CaCl2 gel. The invention further discloses a preparation method of the composite biological filler, a sewage treatment method and a sewage treatment system. Compared with the prior art, the efficient sewage treatment efficiency can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a composite biological filler, a preparation method, a sewage treatment method and a system. BACKGROUND

[0002] In the current field of sewage treatment, with the continuous improvement of the demand for water quality purification efficiency and advanced treatment, the aerobic granular sludge (AGS) technology has become the core hotspot of industry research due to its significant advantages. The technology not only has excellent settling performance, which can effectively solve the problems of poor sludge settling performance and sludge bulking in the traditional activated sludge method, but also has multiple microbial functions, less residual sludge, strong tolerance to biological toxins and organic load fluctuations, and can realize simultaneous nitrogen and phosphorus removal without additional complex process units, greatly simplifying the sewage treatment process and reducing the operation cost. However, although the AGS technology shows good potential in theory and laboratory research, its conversion to practical engineering application still faces three key bottlenecks: first, the start-up period is too long, usually more than 60 days are needed to form stable aerobic granular sludge, which not only prolongs the construction and commissioning period of the sewage treatment system, but also increases the early operation cost and management difficulty; second, the resistance to impact load is weak, when the water quality (such as COD, ammonia nitrogen concentration) or water volume fluctuates, the AGS is easy to loose structure and difficult to maintain stable treatment efficiency, and in severe cases, it may even lead to the treatment effluent water quality not meeting the standard; third, the granules are easy to disintegrate, in the long-term operation process, affected by factors such as hydraulic conditions, pollutant concentration changes or microbial community imbalance, the formed aerobic granular sludge is easy to break and disintegrate, leading to sludge loss and thus reducing the overall treatment efficiency of the system.

[0003] In the field of sewage treatment, traditional biological suspended fillers (such as polyurethane sponge, volcanic rock filler, MBBR filler, etc.) are often used in conventional activated sludge process, biofilm process, etc. By increasing the amount of biological carrier to increase the total amount of microorganisms in the system, the degradation efficiency of pollutants is strengthened or the sludge settling property is improved. The traditional polyurethane sponge filler is one of the commonly used biological carriers in the field of sewage treatment. Due to the special structure of the biological filler, the nitrosation reaction can be realized on the outer surface of the single biological carrier in the aeration tank, and the internal nitrite denitrification can be realized. There is not only simple physical adsorption, but also positive and negative charge attraction, so that the carrier surface has certain cationic active groups and hydrophilic groups such as hydroxyl groups, which can produce bond, valence fixed combination with the microorganisms with negative charge in the sewage, so as to firmly fix the microorganisms and biological enzymes on the carrier, so that the survived microorganisms are not easy to be lost under the shearing action of water and gas, the microorganism loading is large, the volume load is high, so as to achieve the purpose of simultaneous reduction of ammonia nitrogen and total nitrogen in sewage. It also has the advantages of strong bubble cutting ability, large space volume utilization rate, no dead zone and the like. The common defects of the polyurethane sponge filler are as follows: first, the hydrophilicity is poor, which is the typical characteristic of the traditional polyurethane sponge filler, and the contact angle is usually greater than 100°. This characteristic leads to the difficulty of microorganism adhesion on the surface of the filler, and it takes a long time to form a stable biofilm, and the biofilm forming period is generally 14-21 days; second, the mass transfer resistance is large, the pore structure is single, and there is lack of reasonable pore size gradient and connectivity, which is the inherent structural defect of the traditional polyurethane sponge filler; when the sewage flows in the filler, it is easy to form a stagnant area, which hinders the efficient transfer of oxygen, organic pollutants, nitrogen and phosphorus compounds and other key substances between the water phase (sewage) and the biological phase (microorganisms) - this not only directly reduces the degradation efficiency of microorganisms on pollutants, but also may form anaerobic dead angle due to poor local material exchange, breed harmful microorganisms such as sulfur-reducing bacteria, and destroy the balance of microbial community in the system; finally, the function is single, and the traditional polyurethane sponge filler cannot construct a differential microenvironment.

[0004] The AGS technology can enrich denitrifying bacteria and phosphorus accumulating organisms in the core anoxic zone, and enrich nitrifying bacteria in the outer aerobic zone, so as to realize simultaneous nitrogen and phosphorus removal.

[0005] Therefore, based on the common points and advantages and disadvantages of polyurethane sponge filler and AGS technology, and imitating the structural characteristics and performance characteristics of aerobic granular sludge (AGS), a composite biological filler, a preparation method, a sewage treatment method and a system are provided. SUMMARY

[0006] The purpose of the present application is to provide a composite biological filler, a preparation method, a sewage treatment method and a system to realize efficient treatment of sewage.

[0007] The above technical objective of the present application is achieved by the following technical solutions:

[0008] A composite biological filler, comprising:

[0009] The structure of the core comprises Fe3O4 nanoparticles and PEI loaded synchronously by polyurethane sponge, wherein the Fe3O4 loading amount is 6-8 wt% of the mass of the core, and the PEI grafting density is 1.5-2.0 mg / cm 2 ;

[0010] The structure of the outer layer comprises a pure PEI modified polyurethane sponge layer wrapping the core, and the PEI grafting density is 2.0-3.0 mg / cm 2 ;

[0011] The adhesive layer is located between the core and the outer layer, and the material is sodium alginate or CaCl2 gel.

[0012] The composite biological filler has a core made of polyurethane sponge as a base material, and simultaneously loaded with Fe3O4 nanoparticles accounting for 6-8 wt% of the mass of the core and PEI with a grafting density of 1.5-2.0 mg / cm 2 . This structure design can realize dual key functions: the loaded Fe3O4 nanoparticles can construct a magnetic core, help microorganisms to gather in the core area through magnetic action, and supplement essential trace elements for microbial growth by slow release of iron elements, effectively promoting microbial proliferation; and the PEI with this density can optimize the biocompatibility of the surface of the core, assist microbial adhesion and colonization, and together with the loaded Fe3O4 create a microenvironment suitable for the survival of anaerobic microorganisms, providing necessary conditions for the anaerobic metabolism process of the core. The outer layer is a pure PEI modified polyurethane sponge layer wrapping the core, and the PEI grafting density is increased to 2.0-3.0 mg / cm 2, high-density PEI can form a strong positive charge interface outside the filler, effectively capture microorganisms (especially aerobic microorganisms) in sewage through charge adsorption effect, significantly shorten the microorganism enrichment and biofilm formation time, improve the problem of poor hydrophilicity and long biofilm formation period of traditional fillers, at the same time, the outer sponge structure provides a stable attachment carrier and metabolic space for aerobic microorganisms, ensuring the efficient play of aerobic metabolic function. The adhesive layer between the core and the outer layer uses sodium alginate or CaCl2 gel as the material, which not only can realize the close connection between the core and the outer layer, ensure the stability of the overall structure of the filler, meet the strength requirements in the actual wastewater treatment process, but also can form microporous channels at the interface by using the characteristics of the gel. These channels can promote the smooth transfer of sewage, oxygen and various pollutants between the inner and outer layers, avoid the problems of large mass transfer resistance and sewage retention caused by single pore structure of traditional fillers, and at the same time, assist in dividing the spatial boundaries of the inner core anaerobic zone and the outer layer aerobic zone, providing structural support for simulating the "core-shell" layered metabolic mechanism of aerobic granular sludge. Finally, through the synergistic effect of the inner core anaerobic metabolism and the outer layer aerobic metabolism, the simultaneous nitrogen and phosphorus removal efficiency of the filler is improved, and the impact load capacity of the wastewater treatment system is enhanced.

[0013] In a preferred embodiment, the sponge pore size of the polyurethane sponge layer of the outer layer is smaller than the sponge pore size of the polyurethane sponge layer of the inner core. The pore size of the outer layer polyurethane sponge layer is designed to be smaller than the pore size of the inner core polyurethane sponge layer, which can precisely match the layered function of the filler: from the perspective of microbial colonization, the larger pores of the inner core can provide more sufficient living space for anaerobic microorganisms, which is beneficial to the aggregation and reproduction of anaerobic functional microorganisms such as denitrifying bacteria, and the larger pores also facilitate the flow of sewage in the core, which, together with the Fe3O4 magnetic core and low-density PEI, creates a suitable environment for anaerobic metabolism; while the smaller pores of the outer layer can increase the specific surface area of the sponge surface, allowing the positive charge capture interface constructed by high-density PEI to more fully contact with sewage, improving the adsorption and fixation effect of aerobic microorganisms, and the smaller pores can slow down the flow rate of sewage, prolong the contact time of aerobic microorganisms and pollutants, and strengthen the degradation effect of aerobic metabolism on pollutants. From the perspective of mass transfer efficiency, this pore size gradient can also optimize the transfer path of sewage and substances: after preliminary filtration and microbial action through the smaller pores of the outer layer, the sewage enters the larger pores of the inner core for deep anaerobic treatment, avoiding the problem of sewage retention that often occurs in traditional single-pore fillers, and also reducing the diffusion of oxygen from the outer layer aerobic zone to the inner core anaerobic zone, further consolidating the spatial separation of the inner core anaerobic environment and the outer layer aerobic environment, ensuring the stable operation of the "core-shell" layered metabolic mechanism

[0014] In a preferred embodiment, the Fe3O4 nanoparticles are carboxyl-modified, with a particle size of 30-50 nm, and the surface is treated with 0.3M HCl. Carboxyl modification introduces hydrophilic groups, combined with small particle size to reduce particle agglomeration, and 0.3M HCl treatment to remove surface impurities, all of which synergistically improve the dispersibility of the particles in the PEI mixture, ensuring uniform distribution of the magnetic core and avoiding local accumulation of microorganisms; the carboxyl groups form strong interactions with the sponge and PEI, the HCl treatment activates the surface, enhances the stability of the particle loading, reduces the shedding under the impact of water flow, and ensures the long-term functionality of the magnetic core; the 30-50 nm particle size is suitable for the magnetic response requirements of microorganisms, and the modified and treated surface is mild and non-toxic, and can also provide energy for microorganisms through iron release, helping the stable proliferation of microorganisms in the inner core anaerobic zone and supporting the efficient operation of the "core-shell" metabolic mechanism.

[0015] A method for preparing a composite biological filler, comprising:

[0016] Core preparation: soaking alkali-activated polyurethane sponge in a mixed solution containing Fe3O4 and PEI, wherein Fe3O4 is 6-8 wt%, PEI is 1.5-2.0 wt%, pH is 9.5, and vacuum impregnation reaction is carried out at 60°C for 4 hours, followed by water washing;

[0017] Outer layer preparation: soaking alkali-activated polyurethane sponge in a 2.0-3.0 wt% PEI solution, pH 10.0, 60°C reaction for 4 hours, and water washing;

[0018] Double-layer combination: after coating sodium alginate or CaCl2 gel on the surface of the inner core, wherein sodium alginate is 2 wt% and CaCl2 is 1 wt%, the outer layer sponge is wrapped and shaped by rolling.

[0019] The preparation method realizes the precise construction of the composite biological filler through step-by-step processing: the core preparation uses alkali-activated polyurethane sponge, which is soaked in a mixed solution containing 6-8 wt% Fe3O4 and 1.5-2.0 wt% PEI (pH 9.5) at 60°C for 4 hours of vacuum impregnation reaction, the vacuum environment promotes the penetration of the mixed solution into the sponge pores, ensuring uniform loading of Fe3O4 and PEI, the alkali activation pretreatment enhances the surface activity of the sponge, improves the loading stability, and water washing removes unbound components; the outer layer preparation soaks alkali-activated sponge in a 2.0-3.0 wt% PEI solution (pH 10.0) at 60°C for 4 hours, the alkaline conditions and temperature synergistically promote efficient grafting of PEI, forming a high-density positive charge interface, and water washing ensures the purity of the outer layer; the double-layer combination coats 2 wt% sodium alginate and 1 wt% CaCl2 gel, and uses rolling shaping to tightly combine the inner core and the outer layer, the gel not only ensures the bonding strength but also forms microporous channels, the overall process steps are clear and the parameters are controllable, enabling the stable preparation of composite biological fillers with layered structure and function, meeting the needs of wastewater treatment.

[0020] In a preferred embodiment, 1 mM CaCl2 is added to the mixed solution as a dispersion stabilizer during the preparation of the inner core. The addition of 1 mM CaCl2 as a dispersion stabilizer in the mixed solution during the preparation of the inner core can specifically address the dispersion problem of Fe3O4 nanoparticles: Ca 2+ CaCl2 can interact with the surface charge of the nanoparticles, weaken the agglomeration force between the particles, prevent Fe3O4 from agglomerating into large particles due to its small particle size and high surface energy, and ensure its uniform dispersion in the mixed solution containing PEI. At the same time, CaCl2 can also form weak interactions with the surface of the polyurethane sponge and PEI molecules, assisting the uniform attachment of Fe3O4 particles in the sponge pores, preventing local accumulation of particles during loading, ensuring uniform distribution of the inner core magnetic core, and then allowing the uniform enrichment of microorganisms under the action of the magnetic core, avoiding the imbalance of microbial distribution caused by uneven magnetic cores. In addition, the concentration of CaCl2 will not interfere with the combination of PEI and the sponge, nor will it have adverse effects on subsequent microbial proliferation, ensuring dispersion while maintaining the stability of the inner core preparation process.

[0021] In a preferred embodiment, the Fe3O4 nanoparticles are carboxylated and have a particle size of 30-50 nm and are treated with 0.3M HCl on the surface. The Fe3O4 nanoparticles are carboxylated, controlled to have a particle size of 30-50 nm, and treated with 0.3M HCl on the surface, which optimizes the performance of the inner core in multiple dimensions: carboxylation introduces hydrophilic carboxyl groups, which, in combination with a small particle size of 30-50 nm, greatly reduces the tendency of particle agglomeration, and 0.3M HCl treatment can remove impurities and hydroxyl contaminants on the surface of the particles, further improving their dispersion uniformity in the mixed solution containing 1 mM CaCl2, preventing local accumulation of the magnetic core, and ensuring uniform aggregation of microorganisms. At the same time, carboxylation and HCl treatment can activate the surface of the particles, enhance their adhesion to polyurethane sponge and PEI, reduce shedding under water impact, and ensure long-term stability of the magnetic core function; the particle size of 30-50 nm is suitable for the magnetic response requirements of microorganisms, the surface after modification and treatment is mild and non-toxic, and it can also provide energy for microorganisms through iron release, helping to stabilize the proliferation of microorganisms in the anaerobic zone of the inner core, and supporting the efficient operation of the "core-shell" metabolic mechanism.

[0022] In a preferred embodiment, the double-layer combination step specifically comprises: after coating the inner core surface with sodium alginate or CaCl2 gel, wherein the sodium alginate is 2wt%, the CaCl2 is 1wt%, the outer layer sponge is wrapped and rolled to shape, and then sodium alginate or CaCl2 gel is injected between the inner core and the outer layer in a multi-point uniform injection manner. First, 2wt% sodium alginate and 1wt% CaCl2 gel are coated on the surface of the inner core and wrapped with the outer layer sponge, and then rolled to shape, so as to realize the preliminary adhesion of the inner and outer layers and construct a basic structural framework. When the same kind of gel is subsequently injected in a multi-point uniform manner, the strong pressure causes the injected gel to form strong adhesion with the contact surface of the inner and outer layers, thereby significantly improving the overall adhesion strength. At the same time, the pressure generated during the injection process forms an outward supporting force on the outer layer and the inner core, forcing the initially adhered gel layer to stretch and expand, and the originally tight gel layer is pulled apart to form interconnected microporous channels, thereby solving the problem of compact structure and blocked mass transfer caused by simple rolling. The increased distance between the outer layer and the inner core caused by the supporting force further strengthens the physical isolation between the two, making the microenvironment boundary between the outer layer aerobic zone and the inner core anaerobic zone clearer, and avoiding excessive penetration of oxygen into the inner core to destroy the anaerobic metabolic conditions.

[0023] In a preferred embodiment, the injected sodium alginate or CaCl2 gel accounts for 10%-20% of the total sodium alginate or CaCl2 gel.

[0024] A sewage treatment method using the composite biological filler or using the preparation method of the composite biological filler.

[0025] A sewage treatment system using the composite biological filler, using the preparation method of the composite biological filler, or using the sewage treatment method.

[0026] Compared with the prior art, in the composite biological filler of the application, Fe3O4 nanoparticles can form a magnetic core, and the magnetic attraction force can promote the aggregation of microorganisms in the core area of the filler. In addition, the characteristics of the Fe3O4 nanoparticles can also achieve slow release of iron elements, provide necessary trace elements for microbial growth, and drive efficient microbial proliferation. The grafting density of PEI can optimize the surface properties of the inner core, further assist the adhesion of microorganisms, and cooperate with Fe3O4 to create a suitable microenvironment for anaerobic microbial colonization, laying a foundation for subsequent anaerobic metabolism. The outer layer is modified by pure PEI and the grafting density is increased to 2.0-3.0 mg / cm 2The polyurethane sponge layer, with its high density of PEI, can create a strong positive charge capture interface on the outer layer of the packing material. By relying on charge adsorption, it can efficiently capture microorganisms (especially aerobic microorganisms) in wastewater, greatly accelerating the enrichment rate of microorganisms on the surface of the packing material. This solves the problem of long biofilm formation cycles caused by poor hydrophilicity in traditional packing materials. At the same time, the outer sponge structure can also provide a stable attachment and metabolic space for aerobic microorganisms, enabling aerobic metabolic functions. The gel bonding layer, made of sodium alginate or CaCl2, located between the core and outer layers, not only ensures a tight bond between the core and outer layers, guaranteeing the overall structural stability of the packing (the bonding strength meets practical application requirements), but also utilizes the gel's own properties to form microporous channels at the interface. These channels facilitate the transfer of wastewater, oxygen, and pollutants between the inner and outer layers, avoiding the problems of high mass transfer resistance and wastewater retention caused by the single pore size of traditional packing. They also help to achieve spatial separation between the anaerobic zone of the core and the aerobic zone of the outer layer, providing structural support for the "core-shell" stratified metabolic mechanism of aerobic granular sludge. Ultimately, through the synergy of anaerobic metabolism in the core and aerobic metabolism in the outer layer, the efficiency of simultaneous nitrogen and phosphorus removal by the packing is improved, while enhancing the system's resistance to shock loads and alleviating the bottlenecks of long start-up cycles and easy particle disintegration in aerobic granular sludge technology. Attached Figure Description

[0027] Figure 1 This invention relates to a hierarchical structure diagram of a composite biological packing material.

[0028] In the picture

[0029] Kernel 1; Outer layer 2; Adhesive layer 3. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings.

[0031] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

[0032] Example 1:

[0033] like Figure 1 As shown, a composite biological packing material includes:

[0034] The core, the structure of which comprises Fe3O4 nanoparticles and PEI simultaneously loaded onto a polyurethane sponge, wherein the Fe3O4 loading is 6-8 wt% of the core mass and the PEI grafting density is 1.5-2.0 mg / cm³. 2 The Fe3O4 nanoparticles are carboxylated, have a particle size of 30-50 nm, and are treated with 0.3 M HCl.

[0035] Outer layer: the structure of the outer layer includes a pure PEI modified polyurethane sponge layer wrapping the inner core, PEI grafting density 2.0-3.0 mg / cm 2 The sponge pore size of the polyurethane sponge layer of the outer layer is smaller than the sponge pore size of the polyurethane sponge layer of the inner core;

[0036] Adhesion layer: located between the inner core and the outer layer, the material is sodium alginate or CaCl2 gel.

[0037] The composite biological filler of the embodiment forms a composite biological filler based on a "magnetic core-biological interface" double-layer biomimetic structure and a preparation method thereof. Through the layered combination of the inner core (Fe3O4 / PEI-sponge) and the outer layer (pure PEI modified sponge), the following is achieved: the inner core - magnetic core aggregation + iron release driven microbial proliferation; the outer layer - high-density positive charge interface capturing microorganisms.

[0038] The design of the structure works as follows:

[0039]

[0040] Example two:

[0041] A preparation method of a composite biological filler, comprising:

[0042] Preparation of the inner core: immerse the base-activated polyurethane sponge in a mixed solution containing PEI, wherein 6-8 wt%, PEI 1.5-2.0 wt%, pH 9.5, vacuum immersion reaction at 60°C for 4 hours, and water washing;

[0043] Preparation of the outer layer: immerse the base-activated polyurethane sponge in a 2.0-3.0 wt% PEI solution, pH 10.0, reaction at 60°C for 4 hours, and water washing;

[0044] Double-layer combination: after coating the inner core surface with sodium alginate or gel, wherein the sodium alginate is 2 wt%, 1 wt%, wrapping the outer layer sponge, and rolling and shaping.

[0045] Further, in the preparation of the inner core, 1 mM CaCl2 is contained in the mixed solution as a dispersion stabilizer.

[0046] Further, the nanoparticles are carboxyl-modified, with a particle size of 30-50 nm, and the surface is treated with 0.3M HCl.

[0047] Further, the double-layer combination step specifically includes: after coating the inner core surface with sodium alginate or gel, wherein the sodium alginate is 2 wt%, CaCl2 1 wt%, wrapping the outer layer sponge, rolling and shaping, and then injecting sodium alginate or gel between the inner core and the outer layer, with a multi-point uniform injection method.

[0048] Further, the injected sodium alginate or gel accounts for 10%-20% of the total sodium alginate or gel.

[0049] The following is an example:

[0050] 1. Core preparation:

[0051] Take the sponge ball, activate it with 5% NaOH, immerse it in a mixed solution (1.5% PEI + 8% activated Fe3O4, pH 9.5), react at 60°C for 4h, and then wash with water.

[0052] 2. Outer layer preparation:

[0053] Immerse the sponge sheet in 2.5% PEI (pH 10.0), react at 60°C for 4h, and then wash with water.

[0054] 3. Combination:

[0055] Coat the inner core with sodium alginate / CaCl2 gel, wrap the outer sponge sheet, roll it into a shape, and inject sodium alginate / CaCl2.

[0056] The following explains the advantages of the composite biological filler prepared by the preparation method of the composite organism of this embodiment:

[0057] I. Shape advantage

[0058] Spherical core-shell structure:

[0059] The inner core is a spherical sponge that optimizes fluid contact efficiency, and the outer layer is a uniform wrapping layer that ensures the integrity of the microbial capture interface.

[0060] Compared with traditional fillers: Cubes / cylinders have hydraulic dead angles, and spherical design reduces short flow (40% improvement in flow uniformity).

[0061] Gradient pore size distribution: Large pores in the inner core promote denitrifying bacteria enrichment; small pores in the outer layer enhance nitrifying bacteria adhesion.

[0062] Gel adhesion interface: The sodium alginate / CaCl2 gel layer forms microporous channels, promoting material exchange between the inner and outer layers;

[0063] The following explains the technical advantages of this embodiment:

[0064] 1. Microbial regulation advantage

[0065] The inner core attracts anaerobic bacteria through Fe3O4 magnetic core (6-8wt%) + low PEI means, and the outer layer enriches aerobic bacteria through high-density PEI (2.0-3.0mg / cm 2 ), achieving spatial separation of anaerobic / aerobic bacteria and realizing directional enrichment and metabolic synergy of microorganisms.

[0066] 2. Process compatibility:

[0067] Compatible with mainstream SBR / MBBR / IFAS / CASS process.

[0068] Example three:

[0069] A sewage treatment method, using the composite biological filler described in example one, or using the preparation method of the composite biological filler described in example two.

[0070] Example four:

[0071] A sewage treatment system, characterized by using the composite biological filler described in example one, or using the preparation method of the composite biological filler described in example two, or using the sewage treatment method described in example three.

[0072] It should be noted that, in this article, such as the first and second relationship terms are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the term "includes", "contains" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or terminal device. Without more limitations, the elements defined by the statement "include" or "contain" do not exclude the existence of other elements in the process, method, article or terminal device including the elements. In addition, in this article, "greater than", "less than", "exceed" and the like are not included in the number; "above", "below", "within" and the like are understood to include the number.

[0073] The above description of the embodiments is for the convenience of ordinary skilled in the art to understand and use the present application, and those skilled in the art can easily make various modifications to the embodiments, and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above-mentioned embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A composite biological packing material, characterized in that, include: The core, the structure of which comprises Fe3O4 nanoparticles and PEI simultaneously loaded onto a polyurethane sponge, wherein the Fe3O4 loading is 6-8 wt% of the core mass and the PEI grafting density is 1.5-2.0 mg / cm³. 2 ; Outer layer: The outer layer consists of a pure PEI-modified polyurethane sponge layer encapsulating the core, with a PEI grafting density of 2.0-3.0 mg / cm³. 2 ; Adhesive layer: Located between the core and the outer layer, the material is sodium alginate or CaCl2 gel.

2. The composite biological packing material according to claim 1, characterized in that, The pore size of the outer polyurethane foam layer is smaller than that of the polyurethane foam layer of the core.

3. The composite biological packing material according to claim 1, characterized in that, The Fe3O4 nanoparticles are carboxylated, have a particle size of 30-50 nm, and are treated with 0.3 M HCl.

4. A method for preparing a composite biological packing material, characterized in that, include: Core preparation: Alkali-activated polyurethane sponge was immersed in a mixture containing Fe3O4 and PEI, wherein Fe3O4 was 6-8 wt%, PEI was 1.5-2.0 wt%, pH 9.5, and the mixture was vacuum impregnated at 60℃ for 4 hours, followed by washing with water. Outer layer preparation: Immerse alkali-activated polyurethane sponge in 2.0-3.0 wt% PEI solution, pH 10.0, react at 60℃ for 4 hours, and then wash with water; Double-layer combination: After the core surface is coated with sodium alginate or CaCl2 gel, wherein sodium alginate is 2wt% and CaCl2 is 1wt%, the outer sponge is wrapped around it and rolled to shape.

5. The method for preparing a composite biological filler according to claim 4, characterized in that, During the preparation of the core, the mixture contains 1 mM CaCl2 as a dispersant and stabilizer.

6. The method for preparing a composite biological filler according to claim 4, characterized in that, The Fe3O4 nanoparticles are carboxylated, have a particle size of 30-50 nm, and are treated with 0.3 M HCl.

7. The method for preparing a composite biological filler according to claim 4, characterized in that, The specific steps of the double-layer combination include: coating the core surface with sodium alginate or CaCl2 gel, wherein sodium alginate is 2wt% and CaCl2 is 1wt%, wrapping the outer sponge, rolling and shaping, and then injecting sodium alginate or CaCl2 gel between the core and the outer layer in a multi-point uniform injection manner.

8. The method for preparing a composite biological filler according to claim 7, characterized in that, The injected sodium alginate or CaCl2 gel accounts for 10%-20% of the total sodium alginate or CaCl2 gel.

9. A wastewater treatment method, characterized in that, The composite biological packing material according to any one of claims 1 to 3, or the preparation method of the composite biological packing material according to any one of claims 4 to 8.

10. A wastewater treatment system, characterized in that, The composite biological packing material according to any one of claims 1 to 3, or the preparation method of the composite biological packing material according to any one of claims 4 to 8, or the wastewater treatment method according to claim 9.

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