Composite biological filler and method for its preparation

Abstract

The present application relates to sewage treatment technical field, especially to a kind of composite biological filler and preparation method thereof, including filler main body, filler main body is formed by basalt fiber and composite filament mixed weaving three-dimensional staggered structure;Composite filament includes biodegradable polymer matrix, biodegradable polymer matrix can be degraded in water environment and release organic small molecule;The present application can continuously, stably degrade and release organic small molecule in water environment by introducing biodegradable polymer matrix in composite filament, provides long-term electron donor for denitrifying bacteria, perfectly solves the core pain point of carbon source shortage in wastewater denitrification process, reduces additional carbon source dosage, significantly reduces processing cost and secondary pollution risk;While slow-release carbon source can significantly promote the adhesion and growth of microorganisms on the surface of filler, improve the biofilm formation rate of filler, and the biofilm formation amount can reach more than twice of the commercial filler in 3 days, significantly improve the start-up speed and stability of biological treatment system.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular, to a composite biological packing material and its preparation method. Background Technology

[0002] With the rapid development of industry, the discharge of high-concentration, recalcitrant industrial wastewater continues to increase. This type of wastewater is complex in composition, highly toxic, and has poor biodegradability, making it difficult for traditional treatment processes to achieve efficient and compliant treatment. Basalt fiber, as a natural inorganic fiber material, possesses excellent chemical stability, corrosion resistance, high specific surface area, and good biocompatibility, showing broad application prospects in the field of water treatment.

[0003] In existing technologies, biological packing materials based on basalt fiber have been used for general wastewater treatment. However, when treating industrial wastewater rich in complex organic matter (such as high benzoic acid content) and high concentrations of dyes, which are difficult to degrade, they suffer from insufficient COD removal efficiency and insufficient carbon source supply in the denitrification process. This requires the addition of external carbon sources such as sodium acetate and methanol, which not only results in high treatment costs and difficult control, but also easily causes secondary pollution. To solve this problem, the industry often adopts a combination process of "Fenton pretreatment + biochemical treatment". However, this process has the disadvantages of being lengthy, requiring a large area, requiring large amounts of reagents, and having high costs for iron sludge disposal, which seriously restricts treatment efficiency and economic benefits.

[0004] Furthermore, the structural design of existing biological packing materials often focuses on enhancing a single function, failing to achieve microscopic synergy between advanced oxidation, carbon source supply, and biodegradation. For example, while directly adding small molecule carbon sources (such as sodium acetate or methanol) can improve denitrification efficiency in the short term, it is costly and complex to control.

[0005] Therefore, this invention aims to provide a composite biological packing material that combines the function of slow-release carbon source supply with efficient biofilm formation, so as to achieve spatial synergy between carbon source release and microbial growth and improve the treatment efficiency of recalcitrant wastewater. Summary of the Invention

[0006] The present invention aims to overcome the defects of the prior art and provide a composite biological packing material of slow-release carbon source and high-efficiency biofilm formation and its preparation method.

[0007] This invention is implemented as follows: A composite biological packing material includes a packing body, which includes a packing backing plate (1) and a mixed fiber bundle (2). The mixed fiber bundle (2) is uniformly woven on the surface of the packing backing plate (1) to form a three-dimensional seaweed-like network structure. The mixed fiber bundle (2) is composed of basalt fiber (21) and composite filament (22). The composite filament (22) is made by melt spinning a biodegradable polymer matrix. The biodegradable polymer matrix is ​​a blend of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT). The mass ratio of PLA to PBAT is 1:3-3:1. The biodegradable polymer matrix can degrade and release small organic molecules in an aquatic environment, serving as a slow-release carbon source in the biological treatment of wastewater. The mass ratio of the composite filament (22) to basalt fiber (21) is 1:3-1:12.

[0008] As a further improvement, the composite filaments (22) within the mixed fiber bundle (2) are twisted and plyed to form a spiral composite filament bundle (23).

[0009] As a further improvement, the composite filament (22) also includes reinforcing fibers, which are polyethylene terephthalate (PET) staple fibers and / or polypropylene terephthalate (PTT) fibers, to increase the strength of the filler and make the filler less susceptible to damage.

[0010] As a further improvement, the amount of the reinforcing fiber added is 10-30 wt% of the mass of the PLA / PBAT matrix.

[0011] As a further improvement, the surface of the packing body is also coated with an inorganic binder layer, which is used to further fix the packing backing plate (1) and the mixed fiber bundle (2).

[0012] As a further improvement, the inorganic binder layer is a silica sol-alumina system with a solid content of 10-30%, wherein the mass ratio of SiO2 to Al2O3 is 1:1-5:1.

[0013] As a further improvement, the filler backing plate (1) is formed by interlacing mutually perpendicular warp yarns (11) and weft yarns (12), with a gap formed between the warp yarns (11) and weft yarns (12) for the mixed fiber bundles (2) to pass through.

[0014] A method for preparing a composite biological packing material includes the following steps: S1: Preparation of composite filament (22): The biodegradable polymer matrix is ​​melt-spun to obtain composite filament (22); the biodegradable polymer matrix can degrade and release small organic molecules in an aqueous environment, serving as a slow-release carbon source in the biological treatment of wastewater; S2: Packing weaving: The composite filaments (22) and basalt fibers (21) are mixed in proportion and woven on one side of the packing back plate (1) to form a packing body with a three-dimensional seaweed network structure, thus obtaining the composite biological packing.

[0015] As a further improvement, the biodegradable polymer matrix is ​​a blend of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) in a mass ratio of 1:3 to 3:1.

[0016] As a further improvement, in step S1, the preparation of the composite filament (22) is specifically as follows: PLA and PBAT are mixed in proportion, dried and then added to a twin-screw extruder for melt blending, and then cooled and pelletized to obtain composite particles; the composite particles are spun and drawn in a melt spinning machine to obtain composite filament (22).

[0017] As a further improvement, the drying temperature is 40-110℃ and the drying time is 4-12h.

[0018] As a further improvement, the barrel temperature zones of the twin-screw extruder are set as follows: 110-130℃ in the feeding section, 240-290℃ in the mixing section, and 190-210℃ in the die section; the screw speed is 10-600 rpm.

[0019] As a further improvement, the spinning temperature of the melt spinning machine is 240-270℃, and the draw ratio is 2.5-3.5.

[0020] As a further improvement, in step S2, the composite filaments (22) are twisted and twisted to form a spiral composite filament bundle (23), and then woven together with basalt fibers (21) onto the surface of the filler backing plate (1).

[0021] As a further improvement, in step S2, the mass ratio of composite filament (22) to basalt fiber (21) is 1:3-1:12.

[0022] As a further improvement, in step S1, reinforcing fibers are added to the biodegradable polymer matrix, and composite filaments (22) are obtained by melt blending and spinning; the reinforcing fibers are polyethylene terephthalate (PET) short fibers and / or polypropylene terephthalate (PTT) fibers, and the amount added is 10-30 wt% of the mass of the PLA / PBAT matrix.

[0023] As a further improvement, after step S2, step S3 is also included to fix the structure: an inorganic binder is coated on the surface of the filler body, the inorganic binder is used to further fix the filler back plate (1) and the mixed fiber bundle (2), and the structure is fixed after curing after coating.

[0024] As a further improvement, the inorganic binder is a silica sol-alumina system with a solid content of 10-30%, wherein the mass ratio of SiO2 to Al2O3 is 1:1-5:1; after coating, it is cured at 120℃ for 1-2 hours or naturally cooled to complete the fixation.

[0025] The beneficial effects of this invention are: 1. This invention introduces a biodegradable polymer matrix into the composite filament, which can continuously and stably degrade and release small organic molecules in the aquatic environment, providing a long-term electron donor for denitrifying bacteria. This perfectly solves the core pain point of insufficient carbon source in the wastewater denitrification process, reduces the amount of external carbon source added, and significantly reduces treatment costs and the risk of secondary pollution. At the same time, the slow-release carbon source can significantly promote the attachment and growth of microorganisms on the surface of the packing material, increase the biofilm formation rate of the packing material, and the biofilm formation in 3 days can reach more than twice that of commercially available packing materials, greatly improving the start-up speed and stability of the biological treatment system.

[0026] 2. This invention uses basalt fiber as the core skeleton to provide high-strength support and a rough surface for the filler, promoting biofilm adhesion and extracellular electron transfer. By adding reinforcing fibers, the wear resistance, flexibility, and web stability of the composite filaments are significantly improved, preventing the filler from cracking and being damaged under long-term hydraulic scouring. The inorganic binder layer enhances the bonding strength of the fiber cross-linking nodes, enabling the filler to withstand acid and alkali environments and hydraulic impacts for a long time. Its chemical stability and mechanical durability are significantly better than existing biological fillers, and the system's resistance to impact loads is greatly improved.

[0027] 3. The composite biological packing material of the present invention can be directly added into the bioreactor to achieve simultaneous oxidation and biochemical treatment. It is suitable for the transformation and new construction projects of various existing sewage treatment processes and can be widely used in the treatment of various high-concentration and difficult-to-degrade industrial wastewaters such as printing and dyeing, chemical, pharmaceutical, and food industries, with both treatment efficiency and economic benefits. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a cross-sectional structural schematic diagram of the composite biological packing material provided by the present invention; Figure 2 This is a schematic diagram of the structure of the hybrid fiber bundle provided by the present invention; Figure 3 This is a three-dimensional structural diagram of the composite filament bundle provided by the present invention; Figure 4This is a top view structural schematic diagram of the packing backplate provided by the present invention; Figure 5 This is a micro-electron microscope image of the composite filament provided by the present invention; Figure 6 This is a micro-electron microscope image of basalt fibers provided by the present invention; Figure 7 This is a micro-electron microscopy image of the composite filament and basalt fiber mixture provided by the present invention.

[0030] In the diagram: filler backing plate-1, mixed fiber bundle-2, basalt fiber-21, composite filament-22, composite filament bundle-23, warp yarn-11, weft yarn-12. Detailed Implementation

[0031] All embodiments of the present invention are intended to fall within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] Existing basalt fiber packing materials suffer from low efficiency in treating recalcitrant wastewater, and traditional combined processes are complex, costly, and have unstable carbon source supply. To address these technical problems, this paper proposes the following technical solution: Reference Figures 1 to 7 As shown, a composite biological packing material includes a packing body, which includes a packing backing plate (1) and a mixed fiber bundle (2). The mixed fiber bundle (2) is uniformly woven on the surface of the packing backing plate (1) to form a three-dimensional seaweed-like network structure. The mixed fiber bundle (2) is composed of basalt fiber (21) and composite filament (22). The composite filament (22) is made by melt spinning of a biodegradable polymer matrix. The biodegradable polymer matrix is ​​a blend of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT). The mass ratio of PLA to PBAT is 1:3-3:1 (preferably 1:1). The biodegradable polymer matrix can degrade and release small organic molecules in an aquatic environment, serving as a slow-release carbon source in the biological treatment of wastewater. The mass ratio of the composite filament (22) to basalt fiber (21) is 1:3-1:12 (preferably 1:4).

[0033] The composite filaments (22) within the mixed fiber bundle (2) are twisted and twisted to form a spiral composite filament bundle (23).

[0034] The composite filament (22) also includes reinforcing fibers, which are polyethylene terephthalate (PET) staple fibers and / or polypropylene terephthalate (PTT) fibers, used to increase the strength of the filler and make the filler less susceptible to damage.

[0035] The amount of reinforcing fiber added is 10-30 wt% (preferably 20 wt%) of the mass of the PLA / PBAT matrix.

[0036] The surface of the packing body is also coated with an inorganic binder layer, which is used to further fix the packing backing plate (1) and the mixed fiber bundle (2).

[0037] The inorganic binder layer is a silica sol-alumina system with a solid content of 10-30%, wherein the mass ratio of SiO2 to Al2O3 is 1:1-5:1 (preferably 5:1).

[0038] The filler back plate (1) is formed by interlacing mutually perpendicular warp yarns (11) and weft yarns (12), with gaps formed between the warp yarns (11) and weft yarns (12) for the mixed fiber bundles (2) to pass through.

[0039] A method for preparing a composite biological packing material includes the following steps: S1: Preparation of composite filament (22): The biodegradable polymer matrix is ​​melt-spun to obtain composite filament (22); the biodegradable polymer matrix can degrade and release small organic molecules in an aqueous environment, serving as a slow-release carbon source in the biological treatment of wastewater; S2: Packing weaving: The composite filaments (22) and basalt fibers (21) are mixed in proportion and woven on one side of the packing back plate (1) to form a packing body with a three-dimensional seaweed network structure, thus obtaining the composite biological packing.

[0040] The biodegradable polymer matrix is ​​a blend of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) in a mass ratio of 1:3 to 3:1 (preferably 1:1).

[0041] In step S1, the preparation of the composite filament (22) is specifically as follows: PLA and PBAT are mixed in proportion, dried and then added to a twin-screw extruder for melt blending, and then cooled and pelletized to obtain composite particles; the composite particles are spun and drawn in a melt spinning machine to obtain composite filament (22).

[0042] The drying temperature is 40-110℃, and the drying time is 4-12h.

[0043] The barrel temperature zones of the twin-screw extruder are set as follows: 110-130℃ in the feeding section, 240-290℃ in the mixing section, and 190-210℃ in the die section; the screw speed is 10-600 rpm (preferably 110-130 rpm).

[0044] The spinning temperature of the melt spinning machine is 240-270℃, and the draw ratio is 2.5-3.5.

[0045] In step S2, the composite filaments (22) are twisted and twisted to form a spiral composite filament bundle (23), and then woven together with basalt fibers (21) onto the surface of the filler backing plate (1).

[0046] In step S2, the mass ratio of composite filament (22) to basalt fiber (21) is 1:3-1:12 (preferably 1:4).

[0047] In step S1, reinforcing fibers are added to the biodegradable polymer matrix, and composite filaments (22) are obtained by melt blending and spinning. The reinforcing fibers are polyethylene terephthalate (PET) short fibers and / or polypropylene terephthalate (PTT) fibers, and the amount added is 10-30 wt% of the mass of the PLA / PBAT matrix.

[0048] After step S2, step S3, structural fixation, is also included: an inorganic binder is coated on the surface of the filler body, which is used to further fix the filler backing plate (1) and the mixed fiber bundle (2). After coating and curing, structural fixation is completed.

[0049] The inorganic binder is a silica sol-alumina system with a solid content of 10-30%, wherein the mass ratio of SiO2 to Al2O3 is 1:1-5:1 (preferably 5:1); after coating, it is cured at 120℃ for 1-2 hours or naturally cooled to complete the fixation.

[0050] The composite filler prepared by the above method has significantly enhanced carbon source supply capacity by using PLA / PBAT as the main material to make fibers. Furthermore, the woven structure enables direct spatial contact between the carbon source and microorganisms. Microorganisms can attach to the surface of the carbon source fibers and grow without penetrating any physical barriers, and the carbon source release and the metabolic needs of microorganisms are spatially matched. Specifically, the slow degradation of the composite filaments releases small organic molecules, providing a stable carbon source for denitrifying bacteria and ensuring the continuous denitrification reaction; the rough surface and mineral components (Ca, Mg, Si) of the basalt fibers promote biofilm adhesion and extracellular electron transfer. Furthermore, the composite filaments, as continuous fibers, run through the entire packing body, ensuring the uniformity and continuity of carbon source release; at the same time, the surface irregularities and internal pores formed by the woven structure provide multi-level attachment sites for microorganisms; the seaweed-like structure allows the packing to flexibly swing under water impact, reducing biofilm shedding. Because the composite filament has a built-in slow-release carbon source, the amount of external carbon source used is reduced, thus reducing the cost of reagents and the risk of secondary pollution, and significantly improving the economic benefits of enterprises. In addition, the composite filaments (22) in the mixed fiber bundle (2) are twisted to form a spiral composite filament bundle (23). Its spiral configuration provides structural support while significantly increasing the specific surface area and water flow disturbance effect, enhancing mass transfer efficiency, and promoting the directional diffusion of carbon source molecules to the biomembrane interface. Meanwhile, the addition of reinforcing fibers (PET / PTT) improves the wear resistance and flexibility of the filler, and the inorganic binder enhances the stability of the fiber cross-linking nodes, enabling the filler to withstand long-term hydraulic erosion and acid and alkali environment corrosion. Its chemical stability and mechanical durability are significantly better than existing biological fillers. At the same time, PET / PTT, as a non-degradable fiber, forms a "permanent skeleton-slow-release carbon source" dual network structure with degradable PLA / PBAT, which not only ensures the long-term mechanical stability of the filler, but also realizes the controlled release of carbon source.

[0051] This application achieves a balance between flexibility and bonding strength by coating an inorganic binder layer on the surface of the filler and acting on the inorganic-organic interface between the filler backing plate and the mixed fiber bundle, and by adjusting the SiO2 / Al2O3 ratio (preferably 5:1).

[0052] The warp yarn (11) and weft yarn (12) of this application are made of nylon. Its high strength and wear resistance and excellent dimensional stability ensure that the woven structure does not loosen or deform under long-term hydraulic disturbance. The nylon warp yarn and weft yarn are woven in a high-density plain weave to form a dense and elastic base grid, which provides a stable mechanical anchor for the composite filament bundle. At the same time, the microporous structure is conducive to water flow penetration and uniform distribution of biofilm. The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0053] Example 1 (corresponding to filler A in the table) Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 1:1. Polyethylene terephthalate (PET) short fibers accounting for 20 wt% of the total mass of the PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120 rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 3.0 to obtain composite filament.

[0054] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:4 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0055] S3 Structure Fixation: Spray a silica sol-alumina binder (SiO2:Al2O3=5:1) with a solid content of 30% onto the filler surface and cure it at 120℃ for 2 hours to obtain the composite biological filler of this embodiment.

[0056] Example 2 (corresponding to filler B in table) Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 3:1. Polyethylene terephthalate (PET) short fibers accounting for 10 wt% of the total mass of the PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120 rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 2.8 to obtain composite filament.

[0057] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:8 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0058] S3 Structure Fixation: Spray a silica sol-alumina binder (SiO2:Al2O3=3:1) with a solid content of 20% onto the filler surface and cure it at 120℃ for 1.5h to obtain the composite biological filler of this embodiment.

[0059] Example 3 (corresponding to filler C in the table) Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 1:3. Polyethylene terephthalate (PET) short fibers accounting for 20wt% of the total mass of the PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 3.2 to obtain composite filament.

[0060] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:12 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0061] S3 Structure Fixation: Spray a silica sol-alumina binder (SiO2:Al2O3=1:1) with a solid content of 10% onto the filler surface and cure it at 120℃ for 1.0h to obtain the composite biological filler of this embodiment.

[0062] Compare with Example 1 (corresponding to filler D in table). Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 6:1. Polyethylene terephthalate (PET) short fibers accounting for 20wt% of the total mass of the PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 3.0 to obtain composite filament.

[0063] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:16 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0064] S3 Structure Fixation: Spray a silica sol-alumina binder (SiO2:Al2O3=1:1) with a solid content of 30% onto the filler surface and cure it at 120℃ for 2 hours to obtain the composite biological filler of this embodiment.

[0065] Compare with Example 2 (corresponding to filler E in table). Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 1:6. Polyethylene terephthalate (PET) short fibers accounting for 20wt% of the total mass of PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 3.0 to obtain composite filament.

[0066] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:24 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0067] S3 Structure Fixation: Spray a silica sol-alumina binder (SiO2:Al2O3=1:3) with a solid content of 30% onto the filler surface and cure it at 120℃ for 2 hours to obtain the composite biological filler of this embodiment.

[0068] Compare with Example 3 (corresponding to filler F in table). Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 9:1. Polyethylene terephthalate (PET) short fibers accounting for 20wt% of the total mass of the PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 3.0 to obtain composite filament.

[0069] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:32 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0070] S3 yields the composite biological filler of this embodiment, without the addition of silica sol-alumina binder.

[0071] Compare with Example 4 (corresponding to filler G in the table) Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 1:9. Polyethylene terephthalate (PET) short fibers accounting for 20wt% of the total mass of the PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 3.0 to obtain composite filament.

[0072] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:48 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0073] S3 yields the composite biological filler of this embodiment, without the addition of silica sol-alumina binder.

[0074] Compare with Example 5 (corresponding to filler H in the table) Preparation of S1 composite filament: Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) were weighed at a mass ratio of 12:1. Polyethylene terephthalate (PET) short fibers accounting for 20wt% of the total mass of the PLA / PBAT matrix were added. After mixing evenly, the mixture was placed in a forced-air drying oven and dried at 80℃ for 6 hours. The dried raw material was added to a twin-screw extruder. The barrel temperature zones were set as follows: feed section 120℃, mixing section 260℃, die section 200℃, and screw speed controlled at 120rpm. After melting and mixing evenly, the mixture was cooled and pelletized to obtain composite granules. The composite granules were added to a melt spinning machine and spun at 250℃ with a draw ratio controlled at 3.0 to obtain composite filament.

[0075] S2 packing weaving: The prepared composite filaments are mixed with basalt continuous fibers at a mass ratio of 1:96 and woven to form a three-dimensional interlaced seaweed-like structure packing carrier.

[0076] S3 yields the composite biological filler of this embodiment, without the addition of silica sol-alumina binder.

[0077] The comparative example is a commercially available traditional elastic biological filler, which is designed without a slow-release carbon source.

[0078] Verification tests were conducted on the physical properties of the composite biological packing material: Experimental wastewater: shoe material dyeing wastewater (mainly containing azo dyes and disperse dyes), with initial water quality parameters of: COD=800±50mg / L, ammonia nitrogen=40±5mg / L, TN=80±10mg / L, pH=5.5±0.5, and temperature=25±4℃.

[0079] Experimental setup: Continuous flow reactor (CSTR) with an effective volume of 40L, a packing rate of 32% for each group, a hydraulic retention time (HRT) of 24h, dissolved oxygen maintained at 2.5-4.0mg / L in the aerobic stage and 0.2-0.5mg / L in the anoxic stage. The system was acclimatized for 5 days before operation to stabilize the activated sludge MLSS at 2500±200mg / L. Various indicators were tested after 20 days of continuous operation. The following standards are used for testing: COD determination: according to the "Determination of Chemical Oxygen Demand in Water - Dichromate Method" (GB 11914-2019); Ammonia nitrogen determination: according to "Determination of Ammonia Nitrogen in Water Quality - Nessler's Reagent Spectrophotometric Method" (HJ 535-2009); Total nitrogen determination: according to "Determination of total nitrogen in water quality by alkaline potassium persulfate digestion ultraviolet spectrophotometry" (HJ636-2012); Biofilm formation performance: Record the time when biofilm formation begins to appear in each group of packing materials, and weigh the dry weight of biofilm formation on packing materials of the same length after 3 days.

[0080] The test results are as follows:

[0081]

[0082] Verification conclusions by comparing with examples To determine the optimal ratio and structural parameters of the composite biological filler of this application, control examples 1-5 were set up, and the mass ratio of PLA to PBAT, the mass ratio of composite filaments to basalt fibers, and the inorganic binder coating process were adjusted respectively to verify the influence of key parameters on the filler performance: I. Optimization principles for the PLA / PBAT quality ratio: (1) When the PLA ratio is too high (>3:1), the degradation rate is too fast, the mechanical strength is lost rapidly, the packing material disintegrates prematurely, and the system stability collapses. The COD removal rates of comparative examples 1, 3, and 4 dropped to 39.78%, 29.47%, and 15.24%, respectively, showing a precipitous decline.

[0083] (2) When the proportion of PBAT is too high (>1:3), the degradation rate is too slow, the carbon source supply is insufficient, and the denitrification reaction is limited. The COD removal rate of Comparative Example 2 is only 37.82%, which is close to that of Comparative Example 1, but the mechanism is different - the former is "insufficient carbon source", while the latter is "structural collapse".

[0084] (3) When PLA:PBAT=1:1, the degradation kinetics of the two are complementary: PBAT dominates the rapid start-up in the early stage, while PLA dominates the stable supply in the middle stage, and together they achieve the optimal treatment efficiency.

[0085] II. Optimization principles of composite filament / basalt mass ratio (1) When the ratio is 1:4, the composite filament bundles form a secondary network of moderate density on the basalt skeleton, which ensures both carbon source supply and structural permeability, and the amount of film attached reaches a peak of 2.25g.

[0086] (2) When the ratio drops to below 1:12, the density of the composite filament bundle is insufficient, the carbon source supply and the microbial attachment sites decrease simultaneously, and the biofilm amount and treatment efficiency decrease linearly.

[0087] III. Critical Effect of Inorganic Binders Without the binder (Comparative Examples 3, 4, and 5), the COD removal rate dropped to below 29.47%. This demonstrates that the inorganic binder layer is not a simple "fixation aid," but rather achieves chemical reinforcement of the inorganic-organic interface through a Si-O-Al bonded network, which is a necessary condition for maintaining the long-term stable operation of the three-dimensional seaweed-like network structure.

[0088] In summary, this application constructs a composite biological filler system that combines "slow-release properties, structural integrity, and stability" through triple parameter coupling regulation—kinetic matching of biodegradable components, optimization of fiber network spatial configuration, and chemical anchoring at the inorganic-organic interface.

[0089] Experiments showed that the COD removal rates of Examples 1, 2, and 3 of this invention reached 73.57%, 62.52%, and 50.62%, respectively; the ammonia nitrogen removal rates reached 89.81%, 77.62%, and 63.36%, respectively; and the total nitrogen removal rates reached 76.29%, 63.47%, and 49.94%, respectively, all significantly higher than those of traditional elastic packing materials. Among them, Example 1 (PLA / PBAT=1:1, composite filament / basalt=1:4) showed the best treatment effect, with a COD removal rate increased by 34.31%, an ammonia nitrogen removal rate increased by 48.87%, and a total nitrogen removal rate increased by 34.91% compared with traditional elastic packing materials, demonstrating significant improvements in the removal of recalcitrant organic matter and nitrogen.

[0090] In addition, the biofilm formation time in Example 1 of this invention is only 1.5 days, and the biofilm formation amount in 3 days is 2.25g; the biofilm formation speed and biofilm formation amount in Examples 2 and 3 are also far superior to those of traditional elastic packing materials, proving that slow-release carbon sources and three-dimensional structures can significantly accelerate microbial attachment and shorten the system start-up cycle. Finally, the optimal ratio of PLA / PBAT = 1:1, composite filament / basalt = 1:4, and SiO2:Al2O3 = 5:1 is achieved, which balances carbon source release and structural strength, thus realizing the invention's objective.

[0091] Any aspects of this invention not described in detail are well-known to those skilled in the art.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A composite biological packing material, characterized in that: The packing body includes a packing backing plate (1) and a mixed fiber bundle (2). The mixed fiber bundle (2) is uniformly woven on the surface of the packing backing plate (1) to form a three-dimensional seaweed-like network structure. The mixed fiber bundle (2) is made of basalt fiber (21) and composite filament (22). The composite filament (22) is made of a biodegradable polymer matrix by melt spinning. The biodegradable polymer matrix is ​​a blend of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT). The mass ratio of PLA to PBAT is 1:3-3:

1. The biodegradable polymer matrix can degrade and release small organic molecules in an aquatic environment, serving as a slow-release carbon source in the biological treatment of wastewater. The mass ratio of the composite filament (22) to basalt fiber (21) is 1:3-1:

12.

2. The composite biological packing material as described in claim 1, characterized in that: The composite filaments (22) within the mixed fiber bundle (2) are twisted and twisted to form a spiral composite filament bundle (23).

3. The composite biological packing material as described in claim 1, characterized in that: The composite filament (22) also includes reinforcing fibers, which are polyethylene terephthalate (PET) staple fibers and / or polypropylene terephthalate (PTT) fibers, to increase the strength of the filler and make the filler less susceptible to damage.

4. The composite biological packing material as described in claim 3, characterized in that: The amount of reinforcing fiber added is 10-30 wt% of the mass of the PLA / PBAT matrix.

5. The composite biological packing material as described in claim 4, characterized in that: The surface of the packing body is also coated with an inorganic binder layer, which is used to further fix the packing backing plate (1) and the mixed fiber bundle (2).

6. The composite biological packing material as described in claim 5, characterized in that: The inorganic binder layer is a silica sol-alumina system with a solid content of 10-30%, wherein the mass ratio of SiO2 to Al2O3 is 1:1-5:

1.

7. The composite biological packing material as described in claim 1, characterized in that: The filler back plate (1) is formed by interlacing mutually perpendicular warp yarns (11) and weft yarns (12), with gaps formed between the warp yarns (11) and weft yarns (12) for the mixed fiber bundles (2) to pass through.

8. A method for preparing a composite biological packing material, characterized in that: Includes the following steps: S1: Preparation of composite filament (22): The biodegradable polymer matrix is ​​melt-spun to obtain composite filament (22); the biodegradable polymer matrix can degrade and release small organic molecules in an aqueous environment, serving as a slow-release carbon source in the biological treatment of wastewater; the biodegradable polymer matrix is ​​a blend of polylactic acid (PLA) and poly(butylene adipate / terephthalate) (PBAT), with a mass ratio of 1:3-3:1; S2: Packing weaving: The composite filaments (22) and basalt fibers (21) are mixed in proportion and woven on one side of the packing back plate (1) to form a packing body with a three-dimensional seaweed network structure, thus obtaining the composite biological packing.

9. The method for preparing a composite biological filler as described in claim 8, characterized in that: In step S1, the preparation of the composite filament (22) is specifically as follows: PLA and PBAT are mixed in proportion, dried and then added to a twin-screw extruder for melt blending, and then cooled and pelletized to obtain composite particles; the composite particles are spun and drawn in a melt spinning machine to obtain composite filament (22).

10. The method for preparing a composite biological filler as described in claim 9, characterized in that: The drying temperature is 40-110℃, and the drying time is 4-12h.

11. The method for preparing a composite biological filler as described in claim 10, characterized in that: The barrel temperature zones of the twin-screw extruder are set as follows: 110-130℃ in the feeding section, 240-290℃ in the mixing section, and 190-210℃ in the die section; the screw speed is 10-600 rpm.

12. The method for preparing a composite biological filler as described in claim 10, characterized in that: The spinning temperature of the melt spinning machine is 240-270℃, and the draw ratio is 2.5-3.

5.

13. The method for preparing a composite biological filler as described in claim 8, characterized in that: In step S2, the composite filaments (22) are twisted and twisted to form a spiral composite filament bundle (23), and then woven together with basalt fibers (21) onto the surface of the filler backing plate (1).

14. The method for preparing a composite biological filler as described in claim 8, characterized in that: In step S2, the mass ratio of composite filament (22) to basalt fiber (21) is 1:3-1:

12.

15. The method for preparing a composite biological filler as described in claim 9, characterized in that: In step S1, reinforcing fibers are added to the biodegradable polymer matrix, and composite filaments (22) are obtained by melt blending and spinning. The reinforcing fibers are polyethylene terephthalate (PET) short fibers and / or polypropylene terephthalate (PTT) fibers, and the amount added is 10-30 wt% of the mass of the PLA / PBAT matrix.

16. The method for preparing a composite biological filler as described in claim 8, characterized in that: After step S2, step S3, structural fixation, is also included: an inorganic binder is coated on the surface of the filler body, which is used to further fix the filler backing plate (1) and the mixed fiber bundle (2). After coating and curing, structural fixation is completed.

17. The method for preparing a composite biological filler as described in claim 16, characterized in that: The inorganic binder is a silica sol-alumina system with a solid content of 10-30%, wherein the mass ratio of SiO2 to Al2O3 is 1:1-5:1; after coating, it is cured at 120℃ for 1-2 hours or naturally cooled to complete the fixation.

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