Bamboo coarse fiber-based iron-lanthanum modified biofilm filler and preparation method thereof

Abstract

The application relates to the technical field of sewage treatment biological membrane carrier fillers, and particularly discloses a bamboo coarse fiber-based iron-lanthanum modified biological membrane filler and a preparation method thereof. The filler comprises natural bamboo coarse fiber bundles which are shaped by being axially and centrally bundled by a central bundling piece, and iron and lanthanum composite active components loaded in the internal pores and surfaces of the bamboo coarse fiber bundles. The filler is obtained through a preparation process of "shaping first -> oxygen-free high-temperature pore-forming carbonization -> slow cooling -> iron-lanthanum impregnation -> low-temperature drying", and can obtain single-particle morphology and continuous integrated string morphology through switching of a shaping process, and is respectively suitable for MBBR (moving bed biofilm reactor) and biological contact oxidation fixed bed. An axial strengthening component is further arranged for the string morphology and is synchronously bundled and fixed with a tightening section of each basic unit to form a composite bearing structure. The application takes natural bamboo coarse fiber as a base material, conforms to the "bamboo instead of plastic" orientation, and through process sequence design, structural stability and functional modification activity are considered, and the application can be applied to the field of sewage biochemical treatment.

Description

Technical Field

[0001] This invention relates to the field of biofilm carrier packing technology for wastewater treatment, and particularly to a bamboo coarse fiber-based iron-lanthanum modified biofilm packing and its preparation method. Background Technology

[0002] The biofilm process is an aerobic biological wastewater treatment technology that has developed in parallel with the activated sludge process. It involves allowing microorganisms to attach and grow on packing materials or carriers, forming a film-like activated sludge (biofilm). When wastewater comes into contact with the biofilm, pollutants are transferred from the water to the membrane, thus treating the wastewater. The biofilm packing material is the core carrier in the biofilm wastewater treatment process, and its performance directly determines the abundance and activity of the microbial community, as well as the hydraulic conditions and mass transfer efficiency of the entire treatment system. Existing wastewater treatment biofilm packing materials mainly suffer from the following problems: 1. The base materials of mainstream MBBR suspension packing and fixed bed suspension packing are high molecular plastics such as polyethylene and polypropylene. During use, they are prone to aging, breakage, and microplastic pollution, which does not conform to the green and low-carbon industrial orientation of "replacing plastic with bamboo". 2. Among the publicly disclosed bamboo-based or plant fiber-based water treatment packing materials, those without surface and pore metal active component loading have a slower biofilm formation rate, insufficient biocompatibility, and lower treatment efficiency. 3. When bamboo fiber or wood fiber is directly carbonized at high temperature, the fiber structure is prone to embrittlement, shrinkage, and deformation, making it difficult to balance structural integrity and the formation of a multi-level porous structure. Existing processes often use carbonization before molding, which results in a high breakage rate of finished products and difficulty in shaping the structure. 4. For suspended string packing for fixed beds, the main fiber bundles have insufficient load-bearing capacity and are prone to tensile breakage or deformation after the biofilm attaches and increases in weight. Their service life is limited under conditions of deep water and high load biochemical treatment. Summary of the Invention

[0003] To address the problems mentioned in the background section, this invention provides a bamboo coarse fiber-based iron-lanthanum modified biofilm packing material and its preparation method, thereby solving the technical problems of insufficient biofilm formation efficiency, poor structural stability, and difficulty in compatibility with various biochemical treatment conditions in existing bamboo-based water treatment packing materials.

[0004] This invention discloses the following technical solution: a bamboo coarse fiber-based iron-lanthanum modified biofilm packing material, comprising: Natural bamboo coarse fiber bundles are axially centered and bound to form a blank; The filler is obtained by loading an iron-lanthanum composite active component into the internal and surface pores of the preform, which is subjected to oxygen-free high-temperature pore-forming carbonization treatment, and then impregnated with an iron-lanthanum composite impregnation solution and dried and cured after slow cooling in an oxygen-free environment.

[0005] Furthermore, the central binding element is any one of basalt fiber thread, stainless steel wire, or high-silica fiber thread. The central binding element is resistant to temperature ≥500℃ and acid and alkali corrosion. A 0.05mm to 1.0mm expansion gap is reserved between the central binding element and the natural bamboo coarse fiber bundle.

[0006] Furthermore, the blank body can be in the form of a single grain or a string. In the form of a single grain, the coarse bamboo fiber bundles are centrally tied at a single point along the axial center to form a single-grain structure with a tightened centrally tied section in the middle and symmetrical fluffy parts at both ends. In the form of a string, continuous natural bamboo coarse fiber bundles are axially tied at multiple points along the length direction by the centrally tied member at constant intervals to form several continuously arranged basic units, constituting a continuous integrated string structure.

[0007] Furthermore, the total length of the single structure is 15mm to 35mm, the diameter of the central binding section is 8mm to 20mm, the maximum outer diameter of the fluffy portions at both ends is 15mm to 30mm, and the center-to-center distance between adjacent basic units of the string structure is 10mm to 30mm.

[0008] Furthermore, the string-shaped blank is provided with an axial reinforcing component, which is arranged parallel to the continuous natural bamboo coarse fiber bundle along its length and is synchronously bound and fixed to the tightening section of the corresponding basic unit at each central binding member, thus forming a composite load-bearing structure together with the continuous natural bamboo coarse fiber bundle; the axial reinforcing component is any one or a combination of basalt fiber rope, glass fiber rope, and stainless steel wire rope, and the diameter of the axial reinforcing component is 0.8mm to 4.0mm, and the number is 1 to 3.

[0009] A method for preparing a bamboo coarse fiber-based iron-lanthanum modified biofilm filler includes the following steps: S1. Pretreatment of bamboo coarse fiber: Take natural bamboo coarse fiber, remove impurities, open, comb, and dry it, controlling the moisture content to 8% to 18%; S2, Directional feeding: The continuous bamboo coarse fiber bundles are conveyed directionally at a constant speed; when preparing string-type fillers, the axial reinforcing components are conveyed synchronously and aligned parallel to the bamboo coarse fiber bundles. S3. Centered binding at fixed intervals: Along the axial direction of the continuous bamboo coarse fiber bundles, single-point center binding is performed at a set interval to form a continuous basic unit; when preparing the string-shaped filler, the center binding component simultaneously binds the bamboo coarse fiber bundles and the axial reinforcing components. S4. Molding: Based on the finished product shape, mold it using one of the following methods: Method A: Cut along the total length of the basic unit to obtain a single blank; Method B: Without cutting, the material is continuously shaped to a set length to obtain a continuous, integral string-type blank; S5. Oxygen-free high-temperature pore-forming carbonization: The entire blank is placed under a nitrogen, argon or carbon dioxide protective atmosphere and kept at 260℃~350℃ for 30min~120min to form pores and solidify the structure. S6. Oxygen-free slow cooling: Maintain an oxygen-free atmosphere and slowly cool to room temperature at a rate of ≤5℃ / min. S7. Iron-lanthanum impregnation: The cooled billet is impregnated in an iron-lanthanum composite impregnation solution at room temperature for 15 min to 60 min. S8. Low-temperature drying: Dry at 50℃~90℃ for 45min~150min to obtain filler with uniformly loaded iron and lanthanum active components on the surface and internal pores.

[0010] Furthermore, the iron-lanthanum composite impregnation solution comprises, by mass percentage: 4%–12% ferric chloride, 0.5%–4% lanthanum nitrate, and the balance being deionized water, with a pH value of 6.0–8.0.

[0011] Furthermore, steps S5 to S8 are performed as a whole, that is, the billet is carbonized, slowly cooled, impregnated and dried as a whole, without splitting the billet or performing additional connecting processes in the middle of the process.

[0012] Furthermore, the dry specific gravity of the filler is 0.92 to 0.99, and the specific gravity after film attachment is 0.98 to 1.05. The specific gravity of the filler is controlled by one or more of the following methods: adjusting the carbonization temperature and holding time in step S5; adjusting the impregnation solution concentration and impregnation time in step S7; and adjusting the binding tightness in step S3.

[0013] Furthermore, the packing material can be used in any one of a moving bed biofilm reactor, a biological contact oxidation fixed bed, or an aerated biological filter.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Using natural bamboo coarse fiber as the sole base material, it complies with the green and low-carbon industrial policy of "replacing plastic with bamboo"; the filler is biodegradable, reducing microplastic pollution caused by plastic fillers.

[0015] 2. The process sequence of "first shaping → then oxygen-free high-temperature pore-forming carbonization → then iron-lanthanum composite impregnation modification" avoids the embrittlement, shrinkage and breakage problems caused by directly carbonizing the unshaped fiber at high temperature; at the same time, the active components of iron and lanthanum are uniformly loaded on the surface and internal pores of the fiber after pore-forming and activation, which improves biocompatibility and biofilm performance.

[0016] 3. For string-type packing, the axial reinforcing components and bamboo fiber bundles are synchronously fixed at each binding position by synchronous binding to form a composite load-bearing structure, which can effectively reduce the longitudinal tensile stress of the string body after the film attaches and increases its weight, and improve its long-term stability under deep water conditions.

[0017] 4. With the same substrate and the same process route, two forms of single suspended filler and continuous string suspended filler can be obtained by simply switching the molding process, which is convenient for large-scale production. Attached Figure Description

[0018] Figure 1 This is a flowchart of the preparation method of the present invention; Figure 2 This is a schematic diagram of the morphology of a single blank in this invention; Figure 3 This is a schematic diagram of the string-type morphology of the billet of the present invention; Figure 4 This is a schematic cross-sectional view of the packing material of the present invention; In the diagram: 1- Natural bamboo coarse fiber bundle, 2- Centered binding component, 3- Axial reinforcement component. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] A bamboo coarse fiber-based iron-lanthanum modified biofilm packing material, comprising: A natural bamboo coarse fiber bundle 1 is axially centered and bound into a blank using a central binding member 2. The central binding member 2 is any one of basalt fiber thread, stainless steel wire, or high-silica fiber thread. The central binding member 2 is resistant to temperatures ≥500℃ and acid / alkali corrosion. A 0.05mm–1.0mm expansion gap is reserved between the central binding member 2 and the natural bamboo coarse fiber bundle 1. The blank can be in single-piece or string form. In the single-piece form, the natural bamboo coarse fiber bundle is axially centered and bound at a single point, forming a single-piece structure with a tightened central binding section and symmetrical, fluffy ends. Figure 2 As shown, it can be used as a suspension packing material for an MBBR moving bed; the string-type configuration consists of continuous natural bamboo coarse fiber bundles 1 tied axially at multiple points along their length by the central binding member 2 at constant intervals, forming several continuously arranged basic units, constituting a continuous integrated string structure, such as... Figure 3As shown, it can be used as a suspended packing material for biological contact oxidation fixed beds. The string-shaped blank is made from a single continuous bundle of natural bamboo coarse fibers, without any subsequent splicing or threading processes.

[0021] The filler is obtained by loading an iron-lanthanum composite active component into the internal and surface pores of the preform, which undergoes oxygen-free high-temperature pore-forming carbonization treatment, followed by oxygen-free slow cooling, impregnation with an iron-lanthanum composite impregnation solution, and drying and curing. Figure 4 This is a schematic diagram of the packing material's cross-section. The treated packing material has a porous bamboo fiber structure, including mesopores to increase the specific surface area and facilitate microbial attachment, macropores to serve as mass transfer channels, and micropores for adsorption and enrichment. The internal flow channels of the packing material facilitate water exchange and pollutant diffusion. The total length of each individual structure is 15mm to 35mm, and the diameter of the centrally bound section is 8mm to 20mm. The maximum outer diameter of the fluffy portions at both ends is 15mm to 30mm. The center-to-center distance between adjacent basic units of the string structure is 10mm to 30mm. The string-shaped blank is provided with an axial reinforcing component 3. The axial reinforcing component 3 is arranged parallel to the continuous natural bamboo coarse fiber bundle 1 along the length direction, and is synchronously bound and fixed with the tightening section of the corresponding basic unit at each of the central binding members 2, forming a composite load-bearing structure together with the continuous natural bamboo coarse fiber bundle 1. The axial reinforcing component 3 is any one or a combination of basalt fiber rope, glass fiber rope, and stainless steel wire rope. The diameter of the axial reinforcing component 3 is 0.8mm to 4.0mm, and the number is 1 to 3.

[0022] A method for preparing a bamboo coarse fiber-based iron-lanthanum modified biofilm filler, such as... Figure 1 As shown, it includes the following steps: S1. Pretreatment of bamboo coarse fiber: Take natural bamboo coarse fiber, remove impurities, open, comb, and dry it, controlling the moisture content to 8% to 18%; S2, Directional feeding: The continuous bamboo coarse fiber bundles are conveyed directionally at a constant speed; when preparing string-type fillers, the axial reinforcing components are conveyed synchronously and aligned parallel to the bamboo coarse fiber bundles. S3. Centered binding at fixed intervals: Along the axial direction of the continuous bamboo coarse fiber bundles, single-point center binding is performed at a set interval to form a continuous basic unit; when preparing the string-shaped filler, the center binding component simultaneously binds the bamboo coarse fiber bundles and the axial reinforcing components. S4. Molding: Based on the finished product shape, mold it using one of the following methods: Method A: Cut along the total length of the basic unit to obtain a single blank; Method B: Without cutting, the material is continuously shaped to a set length to obtain a continuous, integral string-type blank; S5. Oxygen-free high-temperature pore-forming carbonization: The entire blank is placed under a nitrogen, argon or carbon dioxide protective atmosphere and kept at 260℃~350℃ for 30min~120min to form pores and solidify the structure. S6. Oxygen-free slow cooling: Maintain an oxygen-free atmosphere and slowly cool to room temperature at a rate of ≤5℃ / min. S7. Iron-lanthanum impregnation: The cooled billet is impregnated in an iron-lanthanum composite impregnation solution at room temperature for 15 min to 60 min. S8. Low-temperature drying: Dry at 50℃~90℃ for 45min~150min to obtain a filler with uniformly loaded iron and lanthanum active components on the surface and internal pores. The iron-lanthanum composite impregnation solution includes, by mass percentage: 4%~12% iron chloride, 0.5%~4% lanthanum nitrate, and the balance of deionized water, with a pH value of 6.0~8.0.

[0023] Steps S5 to S8 are performed as a whole, that is, the green body is carbonized, slowly cooled, impregnated, and dried as a whole without splitting or additional connecting processes in the middle of the process; the specific gravity of the filler in the dry state is 0.92 to 0.99, and the specific gravity after coating is 0.98 to 1.05. The specific gravity of the filler is controlled by one or more of the following methods: adjusting the carbonization temperature and holding time in step S5; adjusting the impregnation solution concentration and impregnation time in step S7; adjusting the binding tightness in step S3.

[0024] The packing material is used in any one of moving bed biofilm reactors, biological contact oxidation fixed beds, and aerated biofilters. Example

[0025] S1. Take coarse fiber from 3-year-old natural bamboo, remove impurities, loosen, comb, and then dry it with hot air to a moisture content of 12%; S2. The continuous bamboo coarse fiber bundle is conveyed in a constant direction at a speed of 5m / min; S3. Bundle the bamboo coarse fiber bundles at a 25mm interval, with the diameter of the bundling section controlled at 13mm. Leave a 0.3mm expansion gap between the bundling piece and the bamboo fiber bundle. The bundling piece is made of basalt fiber thread. S4. Cut the blank into units of 25mm in total length to obtain a single blank. S5. Place the single billet into a nitrogen protective atmosphere furnace, heat it to 300℃, and hold it for 70 minutes. S6. Maintain a nitrogen protective atmosphere and slowly cool to room temperature at a rate of 3℃ / min; S7. Prepare the iron-lanthanum impregnation solution: 7% ferric chloride, 2% lanthanum nitrate, and 91% deionized water. Adjust the pH to 7.0. Immerse the cooled billet at room temperature for 30 minutes. S8. Dry with hot air at 70℃ for 90 minutes.

[0026] The resulting packing has a dry specific gravity of 0.95 and exhibits a single-particle structure that is compacted in the middle and fluffy at both ends, making it suitable for use as a suspension packing for MBBR. Example

[0027] Steps S1 to S2 are the same as in Example 1, but in step S2, a basalt fiber reinforcing rope with a diameter of 1.5 mm is simultaneously conveyed as an axial reinforcing component, which is aligned parallel to the bamboo fiber bundle. S3. The CNC equipment performs axial centering binding at 20mm intervals and 25mm unit total lengths, and the binding component simultaneously binds the bamboo fiber bundle and the axial reinforcement component. S4. A continuous, uncut, 2.0m long monolithic billet; S5-S8, refer to the corresponding steps in Example 1; S9. Cut to a standard length of 2.0m and remove any unqualified parts at both ends.

[0028] The resulting packing material is a continuous, integrated string structure, with a base unit made of bamboo fiber and reinforcing rope tied together every 20mm, which can be suspended in a fixed-bed biochemical tank. Example

[0029] Except for the following changes, the rest were the same as in Example 1: the carbonization temperature was adjusted to 280℃ and the holding time was 45 min; the impregnation time was adjusted to 20 min; and the other conditions were the same. The resulting filler had a dry specific gravity of 0.94, which was lower than that in Example 1, but the specific surface area was increased.

[0030] Effect verification The biofilm formation effect of the packing material obtained in Example 1 was compared with that of conventional polyethylene MBBR packing material of the same size and dosage under the same biological treatment tank conditions. The results showed that the biofilm formation amount and biofilm adhesion stability of the packing material of the present invention were better than those of the control packing material in the first 14 days. When treating simulated wastewater containing ammonia nitrogen, the ammonia nitrogen removal rate was improved compared with the control packing material.

[0031] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A bamboo coarse fiber-based iron-lanthanum modified biofilm packing material, characterized in that: include: Natural bamboo coarse fiber bundles are axially centered and bound to form a blank; The filler is obtained by loading an iron-lanthanum composite active component into the internal and surface pores of the preform, which is subjected to oxygen-free high-temperature pore-forming carbonization treatment, and then impregnated with an iron-lanthanum composite impregnation solution and dried and cured after slow cooling in an oxygen-free environment.

2. The bamboo coarse fiber-based iron-lanthanum modified biofilm packing material according to claim 1, characterized in that: The central binding element is any one of basalt fiber, stainless steel wire, or high-silica fiber. The central binding element is resistant to temperature ≥500℃ and acid and alkali corrosion. A 0.05mm to 1.0mm expansion gap is reserved between the central binding element and the natural bamboo coarse fiber bundle.

3. The bamboo coarse fiber-based iron-lanthanum modified biofilm packing material according to claim 1, characterized in that: The blank body can be in the form of a single grain or a string. In the form of a single grain, the coarse bamboo fiber bundles are centrally tied at a single point along the axial center to form a single-grain structure with a tightened centrally tied section and symmetrical fluffy parts at both ends. In the form of a string, continuous natural bamboo coarse fiber bundles are axially tied at multiple points along the length direction by the centrally tied member at constant intervals to form several continuously arranged basic units, which constitute a continuous integrated string structure.

4. The bamboo coarse fiber-based iron-lanthanum modified biofilm packing material according to claim 3, characterized in that: The total length of a single structure is 15mm to 35mm, the diameter of the central binding section is 8mm to 20mm, the maximum outer diameter of the fluffy portions at both ends is 15mm to 30mm, and the center-to-center distance between adjacent basic units of the string structure is 10mm to 30mm.

5. The bamboo coarse fiber-based iron-lanthanum modified biofilm packing material according to claim 3, characterized in that: The string-shaped blank is provided with an axial reinforcing component. The axial reinforcing component is arranged parallel to the continuous natural bamboo coarse fiber bundle along its length direction, and is synchronously bound and fixed to the tightening section of the corresponding basic unit at each central binding member, forming a composite load-bearing structure together with the continuous natural bamboo coarse fiber bundle. The axial reinforcing component is any one or more combinations of basalt fiber rope, glass fiber rope, and stainless steel wire rope. The diameter of the axial reinforcing component is 0.8mm to 4.0mm, and the number is 1 to 3.

6. A method for preparing a bamboo coarse fiber-based iron-lanthanum modified biofilm filler, characterized in that: Includes the following steps: S1. Pretreatment of bamboo coarse fiber: Take natural bamboo coarse fiber, remove impurities, open, comb, and dry it, controlling the moisture content to 8% to 18%; S2, Directional feeding: The continuous bamboo coarse fiber bundles are conveyed directionally at a constant speed; when preparing string-type fillers, the axial reinforcing components are conveyed synchronously and aligned parallel to the bamboo coarse fiber bundles. S3. Centered binding at fixed intervals: Along the axial direction of the continuous bamboo coarse fiber bundles, single-point center binding is performed at a set interval to form a continuous basic unit; when preparing the string-shaped filler, the center binding component simultaneously binds the bamboo coarse fiber bundles and the axial reinforcing components. S4. Molding: Based on the finished product shape, mold it using one of the following methods: Method A: Cut along the total length of the basic unit to obtain a single blank; Method B: Without cutting, the material is continuously shaped to a set length to obtain a continuous, integral string-type blank; S5. Oxygen-free high-temperature pore-forming carbonization: The entire blank is placed under a nitrogen, argon or carbon dioxide protective atmosphere and kept at 260℃~350℃ for 30min~120min to form pores and solidify the structure. S6. Oxygen-free slow cooling: Maintain an oxygen-free atmosphere and slowly cool to room temperature at a rate of ≤5℃ / min. S7. Iron-lanthanum impregnation: The cooled billet is impregnated in an iron-lanthanum composite impregnation solution at room temperature for 15 min to 60 min. S8. Low-temperature drying: Dry at 50℃~90℃ for 45min~150min to obtain filler with uniformly loaded iron and lanthanum active components on the surface and internal pores.

7. The preparation method of bamboo coarse fiber-based iron-lanthanum modified biofilm filler according to claim 6, characterized in that: The iron-lanthanum composite impregnation solution comprises, by mass percentage: 4%–12% ferric chloride, 0.5%–4% lanthanum nitrate, and the balance being deionized water, with a pH value of 6.0–8.

0.

8. The preparation method of bamboo coarse fiber-based iron-lanthanum modified biofilm filler according to claim 6, characterized in that: Steps S5 to S8 are performed as a whole, that is, the billet is carbonized, slowly cooled, impregnated and dried as a whole, without splitting the billet or performing additional connecting processes in the middle of the process.

9. The preparation method of the bamboo coarse fiber-based iron-lanthanum modified biofilm filler according to claim 6, characterized in that: The specific gravity of the filler in its dry state is 0.92 to 0.99, and its specific gravity after film attachment is 0.98 to 1.

05. The specific gravity of the filler is controlled by one or more of the following methods: adjusting the carbonization temperature and holding time in step S5; adjusting the concentration of the impregnation solution and the impregnation time in step S7; and adjusting the tightness of the binding in step S3.

10. The method for preparing bamboo coarse fiber-based iron-lanthanum modified biofilm filler according to claim 6, characterized in that: The packing material is used in any one of moving bed biofilm reactors, biological contact oxidation fixed beds, and aerated biofilters.

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