A composite fiber mesh active microorganism carrier for treating nitrogen-containing wastewater and a preparation method and application thereof

Abstract

The application discloses a composite fiber mesh active microorganism carrier for treating nitrogen-containing wastewater and a preparation method and application thereof. The active microorganism carrier is woven by titanium wire, rock wool wire, iron-carbon twisted wire and PLA wire, has strong biological affinity and high specific surface area, and maintains high mechanical strength, can promote efficient biofilm formation of denitrification sludge, and can promote rapid start of the reactor and improve denitrification effect after successful biofilm formation. The application responds to the requirements of "plastic reduction and prohibition", replaces traditional plastic biological filler, solves the technical pain point of releasing microplastic particles due to degradation during use, meets the green development demand, and has significant economic and ecological environmental value. The iron wire and carbon fiber wire in the iron-carbon twisted wire form a primary cell in the reactor to spontaneously accelerate the controllable dissolution of iron ions, which is not dependent on external potential driving, and conforms to the concept of low carbon and environmental protection; the PLA wire reduces the additional carbon source addition, and further conforms to the concept of low carbon and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of microbial wastewater denitrification technology, and more specifically, to a composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater, its preparation method, and its application. Background Technology

[0002] Low-carbon nitrogen removal technology for wastewater is a research hotspot in the field of water environment and water resources. In recent years, anaerobic ammonia oxidation nitrogen removal technology has received much attention. Compared with traditional nitrification and denitrification processes, this type of anaerobic nitrogen removal technology not only has high nitrogen removal efficiency, but also does not require aeration and has a low demand for organic carbon sources. Therefore, it has significant advantages such as low energy consumption, low sludge production, and low carbon emissions.

[0003] However, anaerobic ammonia oxidation microorganisms face technical challenges in application, namely slow microbial proliferation, poor aggregation performance, and large losses within the reactor. Currently, there are two commonly used solutions. One is sludge granulation technology, which, with the addition of flocculant minerals and the use of agitation, causes the flocculent sludge in the reactor to clump together under hydraulic shear stress. However, this method has high requirements for the construction of the anaerobic reactor, and the degree of sludge granulation is difficult to control. The other is the biofilm method, which introduces a carrier into the reactor to provide attachment sites for the suspended flocculent sludge. Through a circulating biofilm method, the flocculent sludge is efficiently converted into a biofilm form and fixed on the carrier.

[0004] Compared to sludge granulation technology, traditional biofilm methods have advantages such as lower start-up sludge requirements and simpler reactor construction. However, traditional biofilm carriers are mostly made of organic plastics, which have poor hydrophilicity and physicochemical properties. Prolonged contact with high-salt solutions can lead to surface aging, cracking, or brittleness, reducing their effectiveness. During use, microplastics and other micro-pollutants are generated, inhibiting microbial growth and causing secondary pollution when discharged with the effluent. Furthermore, the frequency of replacement and operating costs are high. Secondly, plastic carriers have a small specific surface area and limited loading capacity. Thirdly, traditional biofilm carriers are inefficient in microbial biofilm formation, especially for anaerobic ammonia oxidation microorganisms, with a biofilm formation period of 7-14 days. Moreover, the start-up time for the reactor to achieve efficient denitrification after successful biofilm formation of anaerobic ammonia oxidation sludge is even longer, lasting 15-30 days.

[0005] The technologies for efficient biofilm formation of environmentally friendly anaerobic ammonia oxidation sludge, as well as the rapid reactor start-up technology after successful biofilm formation, have not yet been disclosed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this application is to prepare an environmentally friendly anaerobic microbial carrier that can promote efficient biofilm formation in anaerobic ammonia oxidation denitrification sludge, and can also rapidly promote reactor start-up and improve denitrification effect after successful biofilm formation, as well as its preparation method and application.

[0007] More specifically, in a first aspect, this application provides a composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater, which is composed of titanium wire, rock wool wire, iron-carbon stranded wire, and PLA wire, wherein the iron-carbon stranded wire is formed by twisting iron wire and carbon fiber wire.

[0008] Preferably, the diameter of the titanium wire is 500-1000μm, the diameter of the rock wool wire is 200-300μm, the diameter of the iron-carbon stranded wire is 400-600μm, and the diameter of the PLA wire is 100-150μm.

[0009] Rock wool, also known as basalt wool, is an inorganic mineral wool with an extremely high specific surface area. When used as a filter bed medium, rock wool exhibits a typical fibrous network structure with a porosity (void) ratio of approximately 97%, and possesses a "dual-pore / dual-flow" characteristic (macropores between fibers + micropores within fiber bundles), which is advantageous for biofilm formation and hydraulic retention. This structure brings two advantages to the application of rock wool fibers as microbial carriers: first, the rough fiber surface and entanglement interface facilitate cell and EPS anchoring; second, even if there is a small amount of dissolved oxygen in the influent, the thick biofilm and the limited diffusion within the pores make it easier to consume dissolved oxygen, leading to anoxic / anaerobic conditions internally. Further surface modification of rock wool fibers, increasing the number of cations on its surface, will enhance its adsorption capacity for negatively charged microorganisms. Since the structural strength of rock wool will significantly decrease under long-term immersion, pressure (self-weight, overlying filler, frame clamping), or repeated hydraulic scouring, this application uses a highly stable frame to fix the rock wool fibers.

[0010] Titanium, as a biocompatible inert metal, possesses high structural toughness. Furthermore, a titanium oxide passivation layer forms on its surface, giving it corrosion resistance. Therefore, carrier skeletons made of titanium wire offer the advantage of reusability and facilitate mechanical cleaning, disassembly, and maintenance.

[0011] In view of the advantages of rock wool and titanium wire mentioned above, this application utilizes rock wool wire and titanium wire to weave a base wire mesh. The base wire has been tested and found to have extremely high yield strength per unit width, i.e. structural strength, and also has a large specific surface area, which makes it easy for microorganisms to attach.

[0012] Iron-carbon stranded filaments are made by twisting two iron wires and carbon fiber filaments together in a spiral. These filaments provide a stable source of released iron for the biofilm carrier of active microorganisms. The principle is that the iron and carbon fiber filaments, immersed in nitrogenous wastewater, form numerous tiny galvanic cells at their contact points. This releases ferrous ions stably, eliminates dissolved oxygen in the solution, and provides alkalinity to balance the acidity produced during anaerobic denitrification. The trace amounts of available ferrous ions promote the synthesis of heme in anaerobic ammonia oxidation cells, thereby increasing anaerobic ammonia oxidation activity and promoting denitrification efficiency. Simultaneously, the low dissolved oxygen reducing environment created by the release of ferrous ions significantly shortens the reactor start-up time after successful biofilm formation by anaerobic ammonia oxidation microorganisms, which is of great significance for the application and promotion of anaerobic ammonia oxidation biofilm reactors. Since the release of ferrous ions is related to the contact points between iron and carbon fiber filaments, controlling the mass ratio of iron to carbon fiber filaments in the iron-carbon stranded wire to 1-2:1 and the stranding pitch to 0.5-3mm can effectively control the release rate of ferrous ions to 1-10 mg Fe g. -1 d -1 This release range is generally applicable to denitrification scenarios in anaerobic ammonia oxidation reactors. It is evident that in this application, the iron and carbon fiber filaments spontaneously accelerate the controllable dissolution of iron ions by forming a galvanic cell within the reactor. This eliminates the risk of uncontrolled iron dissolution and is not dependent on external current, aligning perfectly with the low-carbon concept.

[0013] The introduction of PLA (polylactic acid) organic carbon source filaments provides a controllable, minimally situ-released organic carbon source for the web-woven active microbial carrier, promoting the activity of denitrifying bacteria in the biofilm and consuming nitrate byproducts from the anaerobic ammonia oxidation process, thereby further improving the reactor's denitrification efficiency. The diameter of the PLA organic carbon source filaments is controlled at 100-150 μm because the diameter of the PLA filaments affects their specific surface area / mass ratio. Under the action of anaerobic ammonia oxidizing bacteria, the COD release rate per unit mass of PLA organic carbon source filaments with a diameter of 100-150 μm was consistently 5-10 mg COD·g. - ¹·d - ¹ PLA filaments release a slow-release carbon source in situ, reducing the need for additional carbon source addition during reactor operation, further aligning with the low-carbon environmental protection concept.

[0014] Preferably, the permeability coefficient of the composite fiber mesh activated microbial carrier used for treating nitrogen-containing wastewater is 10. -4 -10 - 2 m / s.

[0015] Secondly, this application provides a method for preparing the above-mentioned composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater, comprising the following steps:

[0016] S1. Titanium wires are interwoven into a two-dimensional mesh structure to obtain a titanium mesh skeleton. Rock wool fibers are woven into the titanium mesh skeleton by passing through the mesh openings to obtain a base mesh. The mass ratio of titanium wires to rock wool fibers is 100:1-5, and the mesh size of the titanium mesh skeleton is 25mm. 2 -100mm 2 .

[0017] S2. Immerse the substrate mesh in a mixed solution of polyethyleneimine and cationic nutrients, wherein the concentration of polyethyleneimine is 0.3-0.7% w / v, and the composition and concentration of cationic nutrients are as follows: K2SO4 400-600mg / L, MgSO4 100-140mg / L, CaCl2 150-250mg / L, FeNaEDTA 10-20mg / L, Na2MoO4 1.5-3.5mg / L;

[0018] S3. Iron-carbon stranded wire is woven into the first region of the base wire mesh by passing through the mesh openings, and PLA wire is woven into the second region of the base wire mesh by passing through the mesh openings.

[0019] In step S1, the method of interlacing titanium wires into a two-dimensional mesh structure can refer to existing technologies. The shape of the resulting mesh can be square, circular, rhomboid, hexagonal, or other regular or irregular shapes. The mesh size is closely related to the permeability coefficient of the active microbial carrier. Through experimental testing, a mesh size of 25 mm is preferred. 2 -100mm 2 Subsequently, rock wool fibers are woven into the titanium mesh skeleton by passing through the mesh openings to obtain the base mesh, for example, woven at equal intervals parallel to the titanium wires or parallel to the diagonals of the titanium wires. The preferred mass ratio of titanium wires to rock wool fibers is 100:1-5, which ensures that the permeability coefficient of the active microbial carrier meets the requirements of practical applications. An excessively high proportion of rock wool fibers will result in a too low permeability coefficient during actual application after biofilm attachment; while an excessively low proportion of rock wool fibers will reduce the effective load of anaerobic ammonia-oxidizing microorganisms, thus reducing the denitrification efficiency of the biofilm.

[0020] In step S2, the substrate fibers are immersed in a mixed solution of polyethyleneimine and cationic nutrients. This process serves two purposes: firstly, it modifies the substrate fibers by cationic surface activation, increasing the number of active cations on the surface and further enhancing its adsorption effect on microorganisms; secondly, it provides the trace elements necessary for the growth of anaerobic ammonia-oxidizing microorganisms. Specifically, immersion in the polyethyleneimine solution effectively allows ammonium ions to attach to the substrate fibers, giving them a positive charge, thereby attracting negatively charged microorganisms. Immersion in the nutrient solution not only loads the substrate fibers with more cations but also provides the trace elements necessary for the growth of anaerobic ammonia-oxidizing bacteria, improving denitrification efficiency.

[0021] In step S3, the mass ratio of titanium wire to iron-carbon stranded wire and PLA wire is 100:5-10:1-5. This step involves weaving PLA wire and iron-carbon stranded wire into separate sections, creating a heterotrophic zone (second region) and an autotrophic zone (first region) on a woven active microbial carrier. This eliminates substrate competition between anaerobic ammonia oxidation and denitrification microorganisms. When the woven active microbial carrier is placed vertically, the first region is the lower region, and the second region is the upper region. Preferably, the volume ratio of the first region to the second region is 1-3:1. An excessively large proportion of heterotrophic zone will lead to substrate competition between denitrifying bacteria and anaerobic ammonia oxidation bacteria, while an excessively large proportion of autotrophic zone will inhibit the ecological niche of denitrifying bacteria, thus failing to completely remove nitrate nitrogen byproducts from anaerobic ammonia oxidation and preventing the reactor from achieving a high total nitrogen removal rate. The weaving method in step 3 can be parallel to the titanium wire or parallel to the diagonal of the titanium wire, passing through each mesh of the first and second regions of the substrate mesh.

[0022] Thirdly, this application provides a method for preparing an anaerobic ammonia oxidation biofilm, which uses the composite fiber mesh active microbial carrier described above for treating nitrogen-containing wastewater to attach the biofilm to anaerobic ammonia oxidation sludge.

[0023] Fourthly, this application provides an anaerobic ammonia oxidation biofilm reactor comprising the aforementioned composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater.

[0024] Fifthly, this application provides a method for treating nitrogen-containing wastewater, comprising passing the nitrogen-containing wastewater into the aforementioned anaerobic ammonia oxidation biofilm reactor.

[0025] Sixthly, this application provides the application of the composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater in the treatment of nitrogen-containing wastewater.

[0026] The technical solution of this application achieves the following technical effects:

[0027] 1. The active microbial carrier formed by interweaving titanium wire, rock wool wire, iron-carbon stranded wire, and PLA wire in this application has high mechanical strength while possessing both strong biocompatibility and high specific surface area. It can promote efficient biofilm formation of denitrification sludge and promote rapid reactor start-up and improve denitrification effect after successful biofilm formation. It is applicable to denitrification in long-term anaerobic ammonia oxidation reactors.

[0028] 2. The woven active microbial carrier of this application replaces the traditional plastic biological filler, avoiding the generation of microplastics during product use and degradation from the source. It provides a scalable technical solution for ecological and environmental protection, solves the technical pain point of releasing microplastic particles due to degradation during the use of existing plastic biological fillers, meets the needs of green development, and has significant economic and ecological environmental value.

[0029] 3. This application introduces iron-carbon stranded filaments during the weaving process, forming numerous tiny galvanic cells on the active microbial carrier. This releases trace amounts of ferrous ions and alkalinity, helping to maintain the anaerobic environment and promoting the growth and metabolism of anaerobic denitrifying microorganisms such as anaerobic ammonia-oxidizing bacteria. This significantly shortens the reactor start-up time and reduces denitrification efficiency after successful biofilm formation. The galvanic cells formed by the iron and carbon fibers within the reactor spontaneously accelerate the controllable dissolution of iron ions, eliminating the risk of uncontrolled iron dissolution and eliminating reliance on an external potential, perfectly aligning with the low-carbon concept.

[0030] 4. This application introduces PLA filaments to add a slow-release carbon source to the active microbial carrier, broadening its application scenarios. By controlling the mass ratio of PLA filaments to titanium filaments, the release of the slow-release carbon source can be precisely regulated, reducing the need for additional carbon source addition during reactor operation and further aligning with the low-carbon and environmentally friendly concept. The partitioned weaving of PLA filaments and iron-carbon stranded filaments prevents competition among denitrifying microorganisms and promotes denitrification, further achieving highly efficient nitrogen removal.

[0031] 5. This invention has outstanding advantages such as low cost, simple preparation, few process steps, and strong versatility. The release rate of iron and the permeability coefficient can be controlled by adjusting the mass ratio of rock wool fibers, iron wires, PLA fibers and carbon fiber fibers in the active microbial carrier, so as to adapt to the hydraulic retention time required for denitrification processes in various microbial reactors.

[0032] The following will further explain the concept, specific structure and technical effects of this application in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of this application. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the iron-carbon stranded wire of this application.

[0034] Figure 2 A schematic diagram of the composite fiber mesh active microbial carrier used to treat nitrogen-containing wastewater in Example 1 from a 45° angle.

[0035] Figure 3 This is a front view of the composite fiber mesh active microbial carrier used to treat nitrogen-containing wastewater in Example 1.

[0036] Figure 4This is a diagram showing the denitrification effect of the anaerobic ammonia oxidation biofilm reactor constructed in Example 1.

[0037] Figure 5 A schematic diagram of the composite fiber mesh active microbial carrier used to treat nitrogen-containing wastewater in Example 2, viewed from a 45° angle.

[0038] Figure 6 This is a front view of the composite fiber mesh active microbial carrier used to treat nitrogen-containing wastewater in Example 2.

[0039] Figure 7 This is a diagram showing the denitrification effect of the anaerobic ammonia oxidation biofilm reactor constructed in Example 2.

[0040] Figure 8 A schematic diagram from a 45° angle of the composite fiber mesh active microbial carrier used to treat nitrogen-containing wastewater in Example 3.

[0041] Figure 9 This is a front view of the composite fiber mesh active microbial carrier used for treating nitrogen-containing wastewater in Example 3.

[0042] Figure 10 This is a diagram showing the denitrification effect of the anaerobic ammonia oxidation biofilm reactor constructed in Example 3. Detailed Implementation

[0043] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0044] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. Therefore, the illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0045] Some exemplary embodiments of this application have been described for illustrative purposes. It should be understood that this application may be implemented in other ways not specifically shown in the accompanying drawings.

[0046] This application provides a low-carbon source wastewater treatment device. As an example, this application provides a specific structure and lists specific dimensions in the description. It should be understood that this is only for a more complete and detailed understanding of this application, and does not constitute a limitation of this application. The specific structure and dimensions can be adjusted according to the actual situation.

[0047] Example 1

[0048] Step 1: Preparation of composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater

[0049] Step 1.1

[0050] Pure titanium wires with a diameter of 500μm were woven in a crisscross pattern to form a two-dimensional mesh. The mesh was 32cm long and 20cm wide, with a total weight of 45g. The resulting square mesh had a size of 100mm. 2 Next, rock wool fibers with a diameter of 200μm are woven at equal intervals onto a pure titanium wire skeleton. The rock wool fibers pass through each mesh opening of the titanium mesh skeleton parallel to the titanium wires to obtain the base mesh. The mass ratio of pure titanium wire to rock wool fiber is 100:1.

[0051] Step 1.2

[0052] The substrate mesh obtained in step 1 was immersed in a mixed solution of polyethyleneimine and cationic nutrients and allowed to stand for 1 hour. The concentration of polyethyleneimine was 0.5% w / v, and the composition and concentration of the cationic nutrients were as follows: K2SO4 (400 mg / L), MgSO4 (100 mg / L), CaCl2 (150 mg / L), FeNaEDTA (10 mg / L), and Na2MoO4 (1.5 mg / L).

[0053] Step 1.3

[0054] Iron wire and carbon fiber filaments at a mass ratio of 2:1 are twisted together to form an iron-carbon stranded filament with a diameter of 400 μm (reference). Figure 1 The stranding pitch is 3 mm, and PLA wire with a diameter of 100 μm passes through each mesh of the lower and upper half of the substrate mesh in a parallel manner with the titanium wire. The mass ratio of pure titanium wire to iron-carbon stranded wire and PLA wire is 100:5:1, and the volume ratio of the lower and upper half is 2:1.

[0055] Performance testing:

[0056] The specific structure of the composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater prepared in this application is as follows: Figure 2 and Figure 3 As shown in the figure, the tested structure of this woven active microbial carrier exhibits high strength, with a yield tensile strength per unit width of approximately 7.97 kN / m and an iron ion release rate of 1 mg Fe g.-1 d -1 The permeability coefficient is 1*10 -2 m / s.

[0057] It should be understood that Figure 2 and Figure 3 Although the specific structure and dimensions of the woven mesh active microbial carrier in this embodiment are shown, they do not constitute a limitation of this application. Those skilled in the art can adjust the size, mesh shape, mesh size, etc. of the woven mesh active microbial carrier according to the actual situation.

[0058] Step 2: Biofilm formation in anaerobic ammonia oxidation activated sludge

[0059] This embodiment constructs a biofilm attachment chamber, in which the composite fiber mesh active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater is efficiently attached. The biofilm attachment chamber is constructed as follows: the chamber is assembled from acrylic panels, with a length, width, and height of 20cm, 10cm, and 40cm respectively, and an effective volume of 6L; an inlet pipe is located 2cm from the bottom center of the left side wall of the reactor, and an outlet pipe is located 10cm from the top center of the right side wall of the reactor, with an inlet and outlet pipe diameter of 8mm; the biofilm attachment chamber has good overall sealing performance and the top plate is removable; a slot is provided at the bottom centerline of the reactor for fixing the composite fiber mesh active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater. After the composite fiber mesh active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater is locked into the slot, the top plate is closed to achieve a seal.

[0060] The sludge-water mixture of flocculent anaerobic ammonia oxidation activated sludge used for biofilm formation totaled 10 L, taken from an anaerobic ammonia oxidation (UASB) reactor that had been operating in the laboratory for over one year. The MLVSS of the sludge-water mixture was 3120 mg / L. The sludge-water mixture was pumped into the inlet pipe via a circulation pump, flowed through the composite fiber-woven active microbial carrier prepared in step 1 for treating nitrogenous wastewater, and then overflowed from the effluent, passing through the circulation pump again before flowing back into the inlet pipe. Table 1 shows the changes in attached biomass load and scour resistance retention rate of the composite fiber-woven active microbial carrier prepared in step 1 for treating nitrogenous wastewater after 24 hours of biofilm formation. The data in the table show that the composite fiber-woven active microbial carrier for treating nitrogenous wastewater of this application can achieve an attached biomass load greater than 30 g VSS·m³ after 20 hours of circulating biofilm formation. - ², compared to traditional microbial carriers, the biofilm formation time is significantly shortened (3-7 days). Simultaneously, the adhesion retention rate is high, reaching 92.5% after 96 hours. Therefore, the composite fiber mesh active microbial carrier of this application possesses the dual advantages of high biofilm formation efficiency and high erosion resistance retention rate.

[0061] Table 1. Changes in attached biomass load and erosion resistance retention rate of the web-woven active microbial carrier in Example 1

[0062]

[0063] Step 3: Low-carbon treatment of high-nitrogen-load wastewater

[0064] This embodiment provides a method for treating high-nitrogen-load wastewater with low carbon emissions, including the construction of an anaerobic ammonia oxidation biofilm reactor. The reactor has the following structure: it is assembled from acrylic panels, with a length, width, and height of 60cm, 20cm, and 40cm respectively, and an effective volume of 36L; an inlet pipe is located 2cm from the bottom center of the left side wall of the reactor, and an outlet pipe is located 10cm from the top center of the right side wall of the reactor; the reactor has good overall sealing performance and the top plate is removable; there are 9 slots inside the reactor, spaced 6cm apart, for fixing the woven active microbial carriers.

[0065] After the biofilm formation in step 2 is completed, the nine woven mesh active microbial carriers are secured in the slots, and the top plate is closed to ensure a tight seal. Simulated wastewater is pumped in through the inlet pipe using a peristaltic pump, and overflows from the outlet pipe. The simulated wastewater composition is as follows: NH4Cl (573 mg / L), NaNO2 (960 mg / L), CaCl2 (50 mg / L), MgSO4 (50 mg / L), KH2PO4 (50 mg / L), and NaHCO3 (200 mg / L). The hydraulic retention time is controlled at 24 hours. Figure 4 This graph shows the change in nitrogen removal efficiency of the anammox biofilm reactor in this embodiment over time. The data in the graph shows that the anammox biofilm reactor with the biofilm-forming active microbial carriers after biofilm formation starts up extremely quickly, achieving almost 100% removal of ammonia nitrogen and nitrite nitrogen on the second day of operation. After 5 days of operation, the COD release rate of the PLA filaments stabilizes at 5 mg COD·g. - ¹·d - ¹ A stable, slow-release carbon source drives the activity of denitrifying bacteria, further removing nitrate byproducts from the anaerobic ammonia oxidation process, achieving an ultra-efficient nitrogen removal rate of 99% after 16 days. Simultaneously, the applicant measured the heme C content within the anaerobic ammonia oxidizing bacteria in the reactor. The results are shown in Table 2. It can be seen that the heme C content continuously increased during reactor operation, and after 20 days, the heme C content significantly increased by 48.7% and then stabilized, indicating a significant improvement in the activity of the anaerobic ammonia oxidizing bacteria.

[0066] Table 2. Heme C content of anaerobic ammonia-oxidizing bacteria in Example 1

[0067]

[0068] Example 2

[0069] Step 1: Preparation of composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater

[0070] Step 1.1

[0071] Pure titanium wires with a diameter of 1000μm were woven in a crisscross pattern to form a two-dimensional mesh. The mesh was 32cm long and 20cm wide, with a total weight of 180g. The resulting square mesh had a size of 25mm. 2 Next, rock wool fibers with a diameter of 300μm are woven at equal intervals onto a pure titanium wire skeleton. The rock wool fibers pass through each mesh opening of the titanium mesh skeleton parallel to the diagonal of the titanium mesh to obtain the base mesh. The mass ratio of pure titanium wire to rock wool fiber is 100:5.

[0072] Step 1.2

[0073] The substrate mesh obtained in step one was immersed in a mixed solution of polyethyleneimine and cationic nutrients and allowed to stand for 1 hour. The concentration of polyethyleneimine was 0.7% w / v, and the composition and concentration of the cationic nutrients were as follows: K2SO4 (600 mg / L), MgSO4 (140 mg / L), CaCl2 (250 mg / L), FeNaEDTA (20 mg / L), and Na2MoO4 (3.5 mg / L).

[0074] Step 1.3

[0075] Iron wire and carbon fiber filaments at a mass ratio of 1:1 are twisted together to form an iron-carbon stranded filament with a diameter of 600 μm (reference). Figure 1 The stranding pitch is 1 mm, and PLA wire with a diameter of 150 μm passes through each mesh of the lower and upper half of the substrate wire mesh in a parallel manner to the titanium wire. The mass ratio of pure titanium wire to iron-carbon stranded wire and PLA wire is 100:10:5, and the volume ratio of the lower and upper half is 1:1.

[0076] Performance testing:

[0077] The specific structure of the composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater prepared in this application is as follows: Figure 5 and Figure 6 As shown in the figure, the tested structure of this woven active microbial carrier exhibits high strength, with a yield tensile strength per unit width of approximately 21.6 kN / m and an iron ion release rate of 10 mg Fe g. -1 d -1 The permeability coefficient is 1*10 -4 m / s.

[0078] It should be understood that Figure 5 and Figure 6Although the specific structure and dimensions of the woven mesh active microbial carrier in this embodiment are shown, they do not constitute a limitation of this application. Those skilled in the art can adjust the size, mesh shape, mesh size, etc. of the woven mesh active microbial carrier according to the actual situation.

[0079] Step 2: Biofilm formation in anaerobic ammonia oxidation activated sludge

[0080] This embodiment constructs a biofilm attachment chamber, in which the composite fiber mesh active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater is efficiently attached. The biofilm attachment chamber is constructed as follows: the chamber is assembled from acrylic panels, with a length, width, and height of 20cm, 10cm, and 40cm, and an effective volume of 6L. An inlet pipe is located 2cm from the bottom center of the left side wall of the reactor, and an outlet pipe is located 10cm from the top center of the right side wall of the reactor, with a diameter of 8mm. The biofilm attachment chamber has good overall sealing performance, and the top plate is removable. A slot is located at the bottom centerline of the reactor for fixing the composite fiber mesh active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater. After the composite fiber mesh active microbial carrier prepared in step 1 is engaged in the slot, the top plate is closed to achieve a seal.

[0081] The sludge-water mixture of flocculent anammox activated sludge used for biofilm formation totaled 10 L, taken from an anammox UASB reactor that had been operating in the laboratory for over a year. The MLVSS of the sludge-water mixture was 3120 mg / L. The sludge-water mixture was pumped into the inlet pipe via a circulation pump, flowed through the composite fiber-woven activated microbial carrier prepared in step 1 for treating nitrogenous wastewater, and then overflowed from the effluent, passing through the circulation pump again before flowing back into the inlet pipe. Table 3 shows the changes in attached biomass load and scour resistance retention rate of the composite fiber-woven activated microbial carrier prepared in step 1 after 24 hours of biofilm formation. The data in the table show that the composite fiber-woven activated microbial carrier for treating nitrogenous wastewater of this application can achieve an attached biomass load greater than 30 g VSS·m³ after 16 hours of circulating biofilm formation. - ², compared to traditional microbial carriers, the biofilm formation time is significantly shortened (3-7 days). Simultaneously, the adhesion retention rate is high, reaching 94.8% after 96 hours. Therefore, the composite fiber mesh active microbial carrier of this application possesses the dual advantages of high biofilm formation efficiency and high erosion resistance retention rate.

[0082] Table 3. Changes in attached biomass load and erosion resistance retention rate of the web-woven active microbial carrier in Example 2.

[0083]

[0084] Step 3: Low-carbon treatment of high-nitrogen-load wastewater

[0085] This embodiment provides a method for treating high-nitrogen-load wastewater with low carbon emissions, including the construction of an anaerobic ammonia oxidation biofilm reactor. The reactor has the following structure: it is assembled from acrylic panels, with a length, width, and height of 60cm, 20cm, and 40cm respectively, and an effective volume of 36L; an inlet pipe is located 2cm from the bottom center of the left side wall of the reactor, and an outlet pipe is located 10cm from the top center of the right side wall of the reactor; the reactor has good overall sealing performance and the top plate is removable; there are 9 slots inside the reactor, spaced 6cm apart, for fixing the woven active microbial carriers.

[0086] After the biofilm formation in step 2 is completed, the nine woven mesh active microbial carriers are secured in the slots, and the top plate is closed to ensure a tight seal. Simulated wastewater is pumped in through the inlet pipe using a peristaltic pump, and overflows from the outlet pipe. The simulated wastewater composition is as follows: NH4Cl (764 mg / L), NaNO2 (1280 mg / L), CaCl2 (50 mg / L), MgSO4 (50 mg / L), KH2PO4 (50 mg / L), and NaHCO3 (200 mg / L). The hydraulic retention time is controlled at 24 hours. Figure 7 The graph shows the change in nitrogen removal efficiency of the anaerobic ammonia oxidation biofilm reactor over time. The data in the graph shows that the anaerobic ammonia oxidation biofilm reactor with a web of active microbial carriers after biofilm formation has extremely rapid start-up. Furthermore, by the fourth day of reactor operation, it achieves a near 100% removal efficiency for ammonia nitrogen and nitrite nitrogen in simulated wastewater with a high nitrogen load. After 6 days of operation, the COD release rate of the PLA filaments stabilizes at 10 mg COD·g. - ¹·d - ¹ The stable, slow-release carbon source provided by PLA filaments drives the activity of denitrifying bacteria, further removing nitrate byproducts from the anaerobic ammonia oxidation process. On day 18, ultra-efficient denitrification of simulated wastewater under high nitrogen load was achieved, with a total nitrogen removal rate as high as 99%. Simultaneously, the applicant measured the heme C content within the anaerobic ammonia oxidizing bacteria in the reactor. The results are shown in Table 4. It can be seen that the heme C content continuously increased during reactor operation. After 20 days, the heme C content significantly increased by 46.6% and then stabilized, indicating a significant improvement in the activity of the anaerobic ammonia oxidizing bacteria.

[0087] Table 4. Heme C content of anaerobic ammonia-oxidizing bacteria in Example 2

[0088]

[0089] Example 3

[0090] Step 1: Preparation of composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater

[0091] Step 1.1

[0092] Pure titanium wires with a diameter of 800μm were woven in a crisscross pattern to form a two-dimensional mesh. The mesh was 32cm long and 20cm wide, with a total weight of 125g. The resulting square mesh had a size of 64mm. 2 Next, rock wool fibers with a diameter of 250μm are woven at equal intervals onto a pure titanium wire skeleton. The rock wool fibers pass through each mesh opening of the titanium mesh skeleton parallel to the diagonal of the titanium mesh to obtain the base mesh. The mass ratio of pure titanium wire to rock wool fiber is 100:2.5.

[0093] Step 1.2

[0094] The substrate mesh obtained in step one was immersed in a mixed solution of polyethyleneimine and cationic nutrients and allowed to stand for 1 hour. The concentration of polyethyleneimine was 0.3% w / v, and the composition and concentration of the cationic nutrients were as follows: K2SO4 (500 mg / L), MgSO4 (120 mg / L), CaCl2 (200 mg / L), FeNaEDTA (15 mg / L), and Na2MoO4 (2 mg / L).

[0095] Step 1.3

[0096] Iron wire and carbon fiber filaments at a mass ratio of 1.5:1 are twisted together to form an iron-carbon stranded filament with a diameter of 500 μm (reference). Figure 1 The stranding pitch is 2 mm, and PLA wire with a diameter of 120 μm passes through each mesh of the lower and upper halves of the substrate mesh in a parallel manner with the titanium wire. The mass ratio of pure titanium wire to iron-carbon stranded wire and PLA wire is 100:7:1, and the volume ratio of the lower and upper halves is 2:1.

[0097] Performance testing:

[0098] The specific structure of the composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater prepared in this application is as follows: Figure 8 and Figure 9 As shown in the figure, the tested woven microbial carrier structure exhibits high structural strength, with a yield tensile strength per unit width of approximately 15.6 kN / m and an iron ion release rate of 5 mg Fe g. -1 d -1 The permeability coefficient is 5*10 -3 m / s.

[0099] It should be understood that Figure 8 Although the specific structure and size of the woven mesh active microbial carrier in this embodiment are shown, they do not constitute a limitation of this application. Those skilled in the art can adjust the size, mesh shape, mesh size, etc. of the woven mesh active microbial carrier according to the actual situation.

[0100] Step 2: Biofilm formation in anaerobic ammonia oxidation activated sludge

[0101] This embodiment constructs a biofilm attachment chamber, in which the composite fiber mesh active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater is efficiently attached. The biofilm attachment chamber is constructed as follows: the chamber is assembled from acrylic panels, with a length, width, and height of 20cm, 10cm, and 40cm, and an effective volume of 6L. An inlet pipe is located 2cm from the bottom center of the left side wall of the reactor, and an outlet pipe is located 10cm from the top center of the right side wall of the reactor, with a diameter of 8mm. The biofilm attachment chamber has good overall sealing performance, and the top plate is removable. A slot is located at the bottom centerline of the reactor for fixing the composite fiber mesh active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater. After the composite fiber mesh active microbial carrier prepared in step 1 is engaged in the slot, the top plate is closed to achieve a seal.

[0102] The sludge-water mixture of flocculent anaerobic ammonia oxidation activated sludge used for biofilm formation totaled 10 L, taken from an anaerobic ammonia oxidation (UASB) reactor that had been operating in the laboratory for over a year. The MLVSS of the sludge-water mixture was 3120 mg / L. The sludge-water mixture was pumped into the inlet pipe via a circulation pump, flowed through the composite fiber-woven active microbial carrier prepared in step 1 for treating nitrogen-containing wastewater, and then overflowed from the effluent, passing through the circulation pump again before flowing back into the inlet pipe. Table 5 shows the changes in attached biomass load and erosion resistance retention rate of the composite fiber-woven active microbial carrier prepared in step 1 after 24 hours of biofilm formation. The data in the table show that the composite fiber-woven active microbial carrier for treating nitrogen-containing wastewater of this application can achieve an attached biomass load greater than 30 g VSS·m³ after 16 hours of circulating biofilm formation. - ², compared to traditional microbial carriers, the biofilm formation time is significantly shortened (3-7 days). Simultaneously, the adhesion retention rate is high, reaching 95.0% after 96 hours. Therefore, the composite fiber mesh active microbial carrier of this application possesses the dual advantages of high biofilm formation efficiency and high erosion resistance retention rate.

[0103] Table 5. Changes in attached biomass load and erosion resistance retention rate of the web-woven active microbial carrier in Example 3.

[0104]

[0105] Step 3: Low-carbon treatment of high-nitrogen-load wastewater

[0106] This embodiment provides a method for treating high-nitrogen-load wastewater with low carbon emissions, including the construction of an anaerobic ammonia oxidation biofilm reactor. The reactor has the following structure: it is assembled from acrylic panels, with a length, width, and height of 60cm, 20cm, and 40cm respectively, and an effective volume of 36L; an inlet pipe is located 2cm from the bottom center of the left side wall of the reactor, and an outlet pipe is located 10cm from the top center of the right side wall of the reactor; the reactor has good overall sealing performance and the top plate is removable; there are 9 slots inside the reactor, spaced 6cm apart, for fixing the woven active microbial carriers.

[0107] After the biofilm formation in step 2 is completed, the nine woven mesh active microbial carriers are secured in the slots, and the top plate is closed to ensure a tight seal. Simulated wastewater is pumped in through the inlet pipe using a peristaltic pump, and overflows from the outlet pipe. The simulated wastewater composition is as follows: NH4Cl (573 mg / L), NaNO2 (960 mg / L), CaCl2 (50 mg / L), MgSO4 (50 mg / L), KH2PO4 (50 mg / L), and NaHCO3 (200 mg / L). The hydraulic retention time is controlled at 24 hours. Figure 10 The graph shows the change in nitrogen removal efficiency of the anaerobic ammonia oxidation biofilm reactor over time. The data in the graph shows that the anaerobic ammonia oxidation biofilm reactor with a web of active microbial carriers after biofilm formation starts up extremely quickly, achieving almost 100% removal of ammonia and nitrite nitrogen by the fourth day of operation. After 7 days of operation, the COD release rate of the PLA filaments stabilizes at 7.5 mg COD·g. - ¹·d - ¹ A stable, slow-release carbon source drives the activity of denitrifying bacteria, further removing nitrate byproducts from the anaerobic ammonia oxidation process, achieving an ultra-efficient nitrogen removal rate of 99% after 15 days. Simultaneously, the applicant measured the heme C content within the anaerobic ammonia oxidizing bacteria in the reactor. The results are shown in Table 6. It can be seen that the heme C content continuously increased during reactor operation, and after 20 days, the heme C content significantly increased by 58.0% and then stabilized, indicating a significant improvement in the activity of the anaerobic ammonia oxidizing bacteria.

[0108] Table 6. Heme C content of anaerobic ammonia-oxidizing bacteria in Example 3

[0109]

[0110] This application utilizes titanium wire, rock wool wire, iron-carbon stranded wire, and PLA wire to weave together to form a web-like active microbial carrier. This carrier possesses both strong biocompatibility and high specific surface area while maintaining high mechanical strength. It can promote efficient biofilm formation in denitrification sludge and, after successful biofilm formation, facilitate rapid reactor start-up and improve denitrification efficiency. It is suitable for denitrification in long-term anaerobic ammonia oxidation reactors.

[0111] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A composite fiber-woven active microbial carrier for treating nitrogen-containing wastewater, characterized in that, The composite fiber woven active microbial carrier is woven from titanium wire, rock wool wire, iron-carbon stranded wire, and PLA wire, wherein the iron-carbon stranded wire is formed by twisting iron wire and carbon fiber wire. The composite fiber web-woven active microbial carrier is prepared through the following steps: S1. Titanium wires are interwoven into a two-dimensional mesh structure to obtain a titanium mesh skeleton. Rock wool fibers are woven into the titanium mesh skeleton by passing through the mesh openings to obtain a base mesh. The mass ratio of titanium wires to rock wool fibers is 100:1-5, and the mesh size of the titanium mesh skeleton is 25mm. 2 -100mm 2 ; S2. Immerse the substrate mesh in a mixed solution of polyethyleneimine and cationic nutrients, wherein the concentration of polyethyleneimine is 0.3-0.7% w / v, and the composition and concentration of cationic nutrients are as follows: K2SO4 400-600mg / L, MgSO4 100-140mg / L, CaCl2 150-250mg / L, FeNaEDTA 10-20mg / L, Na2MoO4 1.5-3.5mg / L; S3. Iron-carbon stranded wire is woven into the first region of the base wire mesh by passing through the mesh openings, and PLA wire is woven into the second region of the base wire mesh by passing through the mesh openings.

2. The composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater as described in claim 1, characterized in that, Titanium wire has a diameter of 500-1000μm, rock wool wire has a diameter of 200-300μm, iron-carbon stranded wire has a diameter of 400-600μm, and PLA wire has a diameter of 100-150μm.

3. The composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater as described in claim 1, characterized in that, The iron ion release rate of the composite fiber web-woven active microbial carrier is 1-10 mg Fe g. -1 d -1 The COD release rate is 5-10 mg COD·g - ¹·d - ¹, with a permeability coefficient of 10 -4 -10 -2 m / s.

4. A method for preparing a composite fiber-woven active microbial carrier for treating nitrogen-containing wastewater as described in claim 1, characterized in that, Includes the following steps: S1. Titanium wires are interwoven into a two-dimensional mesh structure to obtain a titanium mesh skeleton. Rock wool fibers are woven into the titanium mesh skeleton by passing through the mesh openings to obtain a base mesh. The mass ratio of titanium wires to rock wool fibers is 100:1-5, and the mesh size of the titanium mesh skeleton is 25mm. 2 -100mm 2 ; S2. Immerse the substrate mesh in a mixed solution of polyethyleneimine and cationic nutrients, wherein the concentration of polyethyleneimine is 0.3-0.7% w / v, and the composition and concentration of cationic nutrients are as follows: K2SO4 400-600mg / L, MgSO4 100-140mg / L, CaCl2 150-250mg / L, FeNaEDTA 10-20mg / L, Na2MoO4 1.5-3.5mg / L; S3. Iron-carbon stranded wire is woven into the first region of the base wire mesh by passing through the mesh openings, and PLA wire is woven into the second region of the base wire mesh by passing through the mesh openings.

5. The preparation method according to claim 4, characterized in that, In step S3, the mass ratio of iron wire to carbon fiber wire in the iron-carbon stranded wire is 1-2:1, and the stranding pitch of the iron-carbon stranded wire is 0.5-3mm.

6. The preparation method according to claim 4, characterized in that, The mass ratio of titanium wire to iron-carbon stranded wire and PLA wire is 100:5-10:1-5, and the volume ratio of the first region to the second region is 1-3:

1.

7. A method for preparing an anaerobic ammonia oxidation biofilm, characterized in that, The composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater as described in any one of claims 1-3 is used to attach biofilms to anaerobic ammonia oxidation sludge.

8. An anaerobic ammonia oxidation biofilm reactor, characterized in that, It includes the composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater as described in any one of claims 1-3.

9. A method for treating nitrogen-containing wastewater, characterized in that, This includes passing the nitrogen-containing wastewater into the anaerobic ammonia oxidation biofilm reactor as described in claim 8.

10. The application of the composite fiber mesh active microbial carrier for treating nitrogen-containing wastewater as described in any one of claims 1-3 in the treatment of nitrogen-containing wastewater.

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