A method for cultivating anaerobic ammonium oxidation granular sludge with polydopamine-modified biochar-loaded Fe-Cu sodium alginate microsphere core

Abstract

The present invention discloses a method for cultivating anaerobic ammonia oxidation granular sludge with polydopamine-modified biochar loaded Fe-Cu sodium alginate microsphere inner core, comprising the following steps: biochar is modified with polydopamine, and then Fe-Cu ion loading is performed, and finally sodium alginate microspheres are prepared, and the prepared sodium alginate microspheres are used as inner cores, and co-cultured with activated Bacillus DMF-4 in an anaerobic environment. After continuous cultivation for 3 weeks, gravity sedimentation or centrifugation is used to collect, and anaerobic ammonia oxidation granular sludge with sodium alginate microsphere inner cores is obtained. Sodium alginate microspheres as inner cores provide greater density and good morphological support for sludge particles, avoid sludge swelling problems, and improve sedimentation performance. The sludge anti-shear performance is improved, and the iron ions that are slowly released and continuously released are enhanced, and the adsorption capacity of organic matter, ammonia nitrogen and heavy metals is enhanced, thereby improving the effect of sewage treatment. At the same time, it is a biodegradable material and will not cause secondary pollution during use.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to a method for cultivating anaerobic ammonia oxidation granular sludge having a polydopamine-modified biochar-loaded Fe-Cu sodium alginate microsphere inner core. Background Art

[0002] When using the anaerobic ammonium oxidation (ANAMMOX) process to treat nitrogen-containing wastewater, ANAMMOX bacteria produce a large amount of N₂ that cannot be released. This forms air pockets within the granular sludge or adheres to its surface, reducing its density and causing it to float. This air pocket then disappears with the effluent, increasing the concentration of suspended solids in the effluent and compromising treatment effectiveness, even causing the system to crash. Furthermore, the ANAMMOX process produces approximately 11% nitrate as a byproduct, impacting the process's ability to meet emission standards. These factors have severely hampered the large-scale application of the ANAMMOX process.

[0003] There are many studies on the characteristics of anaerobic ammonium oxidation granular sludge and the removal of nitrate byproducts in the prior art. For example, the existing patent CN201510640931.2 discloses a method for cultivating anaerobic ammonium oxidation granular sludge with a hydroxyapatite core. By adding calcium ions and high concentrations of phosphate ions to the influent, granular sludge with a hydroxyapatite core and good sedimentation performance, high mechanical strength, large particle size, and dense bacterial load can be cultivated, which can achieve efficient retention of anaerobic ammonium oxidizing bacteria at high flow rates. However, it requires the addition of calcium chloride and a high concentration of phosphate during the cultivation process. Excessive phosphate concentrations can easily cause inhibition of anaerobic ammonium oxidizing bacteria, and the process does not involve the deep removal of nitrate byproducts.

[0004] Although there are public documents that disclose the use of zero-valent iron powder in anaerobic ammonium oxidation processes to remove nitrate byproducts, there are also some disadvantages and challenges: (1) Excessive release of iron ions may have a toxic effect on the microbial community, inhibit the activity of some microorganisms, and affect the biodegradation efficiency of the system. In particular, some sensitive bacteria (such as nitrifying bacteria and denitrifying bacteria) have low tolerance to high concentrations of iron ions, which may cause the failure of important biological processes in the system. (2) The chemical properties of Fe powder in sewage may be unstable and prone to oxidation reactions, forming iron hydroxide or other insoluble substances, affecting its long-term stability and effect in the particles. The dissolution and migration of iron may cause the particle structure to be destroyed, resulting in the disintegration or loosening of sludge particles. (3) Although the introduction of iron powder can improve sedimentation performance to a certain extent, it may induce sludge bulking problems under certain conditions, especially when the iron ion concentration is high, which may cause the sludge flocs to become loose and the particle structure to be unstable. Excessive iron salts may cause the sludge to settle faster, but at the same time reduce the flexibility of the particles, making the particles fragile. In summary, although Fe powder can bring certain performance improvements in the activated granular sludge process, its introduction needs to be reasonably designed and controlled to avoid adverse effects on the system's biodegradation function, sedimentation performance and subsequent sludge disposal. Summary of the Invention

[0005] In order to solve at least one of the above problems, the present invention provides a method for cultivating anaerobic ammonium oxidation granular sludge having a core of polydopamine-modified biochar loaded with Fe-Cu sodium alginate microspheres.

[0006] In order to achieve the above object, the present invention adopts the following technical means:

[0007] The first aspect of the present invention provides a method for cultivating anaerobic ammonium oxidation granular sludge having a core of polydopamine-modified biochar-loaded Fe-Cu sodium alginate microspheres, comprising the following steps:

[0008] S1. Preparation of sodium alginate microspheres, steps are as follows:

[0009] S1-1. Preparation of biochar: using biomass materials, carbonizing them at high temperature under nitrogen or inert gas environment, naturally cooling them, crushing them, screening them with mesh, and drying them;

[0010] S1-2. Polydopamine synthesis: Disperse biochar powder in Tris buffer and disperse it evenly by ultrasound; add dopamine in a ratio of 100 mL: 1-2 g to deionized water and stir until completely dissolved; adjust the pH to 8.5-9.0 with sodium hydroxide to obtain a dopamine solution; gradually add the dopamine solution dropwise to the biochar, stir at room temperature for 12-24 hours, and expose to air for oxidation; the color gradually changes from light yellow to dark brown, indicating that polymerization is complete, and the dopamine is gradually deposited on the surface of the biochar powder to form a polydopamine coating, thereby obtaining polydopamine-modified biochar;

[0011] S1-3, Fe-Cu ion loading: soak the polydopamine-modified biochar in FeCl3 solution and CuCl2 solution at a ratio of 1-2 g: 20 mL and stir thoroughly; wash with deionized water and dry to obtain Fe-Cu loaded polydopamine-modified biochar;

[0012] S1-4. Preparation of sodium alginate microspheres: Sodium alginate was dissolved in deionized water at a ratio of 1-2 g:50 mL, and polydopamine-modified biochar and sodium alginate solution were evenly mixed at a ratio of 1-2 g:100 mL; the mixture was dripped into the hardening solution at a rate of 1.5-2.5 mL / min to form microspheres; the microspheres were allowed to stand in the hardening solution until they were completely hardened, and then removed from the hardening solution and rinsed with water to obtain polydopamine-modified biochar-loaded Fe-Cu sodium alginate microspheres;

[0013] S2. Cultivate anaerobic ammonium oxidation granular sludge, the steps are as follows:

[0014] S2-1. Take the cultured ANAMMOX bacteria and activate them by culturing them in anaerobic medium at 30°C for 1-2 weeks;

[0015] S2-2. In an anaerobic environment, the activated ANAMMOX bacteria were inoculated into the culture medium at a volume fraction of 5-6%, and 8-10% by mass volume fraction of polydopamine-modified biochar loaded with Fe-Cu sodium alginate microspheres were added;

[0016] S2-3. The polydopamine-modified biochar loaded with Fe-Cu sodium alginate microspheres, sludge, and water in step S2-2 are cultured and monitored in an anaerobic continuous stirred reactor. After continuous culture for 3 weeks, the anaerobic ammonia oxidation granular sludge is collected by gravity sedimentation or centrifugation to obtain a sodium alginate microsphere core.

[0017] In some embodiments of the present invention, in step S1-1, the biomass material is waste sludge or agricultural and forestry waste biomass, such as sawdust, coconut shells, straw and other agricultural and forestry waste biomass materials.

[0018] In some embodiments of the present invention, in step S1-3, the concentrations of the FeCl3 solution and the CuCl2 solution are 0.1-0.2M.

[0019] In some embodiments of the present invention, in step S1-4, the hardening liquid is a 25-30 g / L calcium chloride solution.

[0020] In some embodiments of the present invention, in step S1-4, the drop distance of the mixed solution into the hardening solution to form microspheres is maintained at 3-5 cm.

[0021] In some embodiments of the present invention, in step S1-1 and step S1-3, the drying temperature is 50-80°C, and the drying time is 10-15 hours.

[0022] In some embodiments of the present invention, in step S2-1 and step S2-2, the culture medium contains NH4Cl: 1000 mg / L, NaNO3: 500 mg / L, KH2PO4: 50 mg / L, KCl: 50 mg / L, NaHCO3: 100 mg / L and trace element solution; in some embodiments of the present invention, the trace element solution is 2 mL / L, and the trace elements include H3BO3, MnC12, ZnSO4, Na3MoO4, and H2SeO3.

[0023] In some embodiments of the present invention, in step S2-3, the culture conditions in the reactor are: the reactor is kept at a constant temperature of 25-30°C, and the reactor is filled with nitrogen to completely eliminate oxygen.

[0024] In some embodiments of the present invention, in step S2-3, the reactor detection conditions are: weekly detection, control of NH4 + Concentration 100-1000 mg / L, NO3 - Concentration within 50-300 mg / L.

[0025] The second aspect of the present invention provides anaerobic ammonium oxidation granular sludge prepared by the method described in the first aspect of the present invention. Using sodium alginate microspheres prepared by polydopamine-modified activated carbon loaded with iron-copper (Fe-Cu) powder as the core of the activated granular sludge (AGS) significantly improves the sludge's structural stability, adsorption properties, and biocompatibility, while also providing a slow-release iron ion effect and preventing microbial toxicity.

[0026] The third aspect of the present invention also provides the use of the anaerobic ammonium oxidation granular sludge prepared by the method described in the first aspect of the present invention in sewage treatment; the prepared anaerobic ammonium oxidation granular sludge is applied to sewage treatment to effectively remove ammonia nitrogen, nitrate nitrogen, COD, phosphorus and heavy metal ions.

[0027] Beneficial effects of the present invention

[0028] Compared with the existing technology, the present invention has the following beneficial effects: the present invention uses polydopamine (PDA)-modified activated carbon loaded with iron-copper (Fe-Cu) powder to make sodium alginate (SA) microspheres, and uses them as the core of activated granular sludge (AGS), fully combining the characteristics of multiple materials, which helps to improve the structure, performance and pollutant removal ability of sludge.

[0029] (1) Improving the structural stability of granular sludge

[0030] The sodium alginate microspheres securely encapsulate the activated carbon and iron powder, providing a stable core support structure and minimizing core material loss. The polydopamine coating enhances the adhesion between the materials, preventing the internal components of the microspheres from falling off, improving the shear resistance of the granular sludge and preventing sludge disintegration.

[0031] (2) Provide sustained release effect and reduce microbial toxicity

[0032] The polydopamine modification and sodium alginate encapsulation allow the iron-copper particles to slowly release iron ions, avoiding the inhibition of microbial activity due to excessive iron concentration; the continuous slow release of iron ions helps maintain good phosphorus removal performance, improve the operating stability of the system, and prevent the secondary release of phosphorus.

[0033] (3) Improve the attachment and growth environment of microorganisms

[0034] The biocompatibility of polydopamine promotes the rapid attachment and growth of microbial communities on the surface of the microspheres, accelerating the maturation of granular sludge; the porous structure of the microsphere surface provides more attachment sites for microorganisms, promotes the formation of biofilms, and improves the organic matter degradation efficiency of the system.

[0035] (4) Improve the adsorption and pollutant removal capabilities of sludge

[0036] The porous structure of activated carbon enhances its adsorption capacity for organic matter, ammonia nitrogen, and heavy metals, improving wastewater treatment effectiveness. The polydopamine-coated iron-copper particles catalyze redox reactions, enhancing COD degradation and phosphorus precipitation.

[0037] (5) Improve the settling performance of granular sludge

[0038] The sodium alginate microspheres as the core provide greater density and good morphological support for the sludge particles, avoiding sludge swelling problems and improving sedimentation performance; this helps to form compact and stable sludge particles, increasing the sludge settling rate and separation efficiency.

[0039] (6) Enhance the system's ability to withstand shock loads

[0040] The core structure of polydopamine-activated carbon-loaded iron-copper microspheres makes the granular sludge more tolerant and able to cope with sudden fluctuations in organic load or pollutant concentration in wastewater treatment; this enhanced particle stability helps to extend the operating cycle of the sludge system and reduce the frequency of shutdown maintenance.

[0041] (7) Promote the simultaneous removal of nitrogen and phosphorus

[0042] The catalytic effect of the iron-copper particles effectively promotes electron transfer during denitrification, improving nitrogen removal efficiency. The synergistic effect of polydopamine and activated carbon enhances phosphorus removal, ensuring simultaneous removal of nitrogen and phosphorus, and improving effluent quality.

[0043] (8) Green, environmentally friendly and biodegradable

[0044] Sodium alginate and polydopamine are both biodegradable materials that will not cause secondary pollution during sludge aging or disposal, which is conducive to environmental protection; the core material will not remain in the environment for a long time and has high recycling and regeneration potential, which meets the requirements of sustainable development.

[0045] (9) Easy to recycle and regenerate

[0046] The microspheres' structure facilitates recovery through sedimentation or screening after wastewater treatment, minimizing core material loss. Recovered microspheres can be regenerated through simple treatments (such as acid washing or sintering) to restore their adsorption capacity, further reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A picture of Fe-Cu loaded polydopamine modified biochar in Example 1 of the present invention is shown;

[0048] Figure 2 Shows pictures of Fe-Cu sodium alginate microspheres loaded with polydopamine-modified biochar of different particle sizes in Example 1 of the present invention;

[0049] Figure 3 The SEM image of the porous structure of the surface of Fe-Cu sodium alginate microspheres loaded with polydopamine-modified biochar in Example 1 of the present invention is shown;

[0050] Figure 4 The XDR image of Fe-Cu sodium alginate microspheres loaded with polydopamine-modified biochar in Example 1 of the present invention is shown;

[0051] Figure 5 The structure diagram of the anaerobic continuous stirred reactor in Example 2 of the present invention is shown; wherein: 1. stirring reaction chamber; 2. motor; 3. stirring shaft; 4. stirring fan blade; 5. water inlet pipe; 6. water outlet pipe; 7. nitrogen pipe;

[0052] Figure 6A comparison chart showing the average regeneration rates of the sodium alginate microspheres treated in Example 2 of the present invention under different regeneration treatment methods is shown;

[0053] Figure 7 The results show the removal effect of ammonia nitrogen after the stable activated granular sludge is formed in the reactor in Example 3;

[0054] Figure 8 The results show the nitrate-nitrogen removal effect after the stable activated granular sludge is formed in the reactor in Example 3;

[0055] Figure 9 A picture showing the anaerobic activated granular sludge recovered after sewage treatment in Example 3. DETAILED DESCRIPTION

[0056] The following examples are provided to illustrate preferred embodiments of the present invention. Those skilled in the art will appreciate that the techniques disclosed in the following examples represent techniques discovered by the inventors that can be used to practice the present invention and, therefore, can be considered preferred embodiments of the present invention. However, those skilled in the art will appreciate from this disclosure that many modifications may be made to the specific embodiments disclosed herein while still achieving the same or similar results without departing from the spirit or scope of the present invention.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention belongs, and the disclosures herein and the materials they cite are hereby incorporated by reference. Those skilled in the art will recognize or be able to ascertain, through routine experimentation, many technical equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims.

[0058] The technical solution of the present application will be further described in detail below in conjunction with specific implementation methods.

[0059] Example 1 Preparation of Sodium Alginate Microspheres

[0060] The preparation steps of sodium alginate microspheres are as follows:

[0061] (1) Preparation of biochar: Use biomass material, such as waste sludge, in a tubular furnace or high-temperature furnace under a nitrogen or inert gas environment to prevent combustion. Raise the furnace temperature to 500°C and maintain it for 3 hours to ensure complete carbonization of the biomass. Cool it naturally to room temperature. Grind the prepared biochar and sieve it with a mesh to obtain biochar powder with a particle size of 0.5-1 mm to ensure uniformity. Dry it at 60°C for 12 hours to remove moisture.

[0062] (2) Polydopamine coating: The biochar powder obtained in (1) was dispersed in Tris buffer and uniformly dispersed by ultrasound to obtain a biochar particle suspension; 100 mL of deionized water was added to a 250 mL beaker, and 1 g of dopamine was added and stirred until completely dissolved; sodium hydroxide was used to adjust the pH to 8.5-9.0; the dopamine solution was gradually added dropwise to the biochar and monitored with a pH meter to ensure the suitability of the reaction environment; stirring was maintained for 24 hours and the mixture was exposed to air for oxidation; when the color gradually changed from light yellow to dark brown, the polymerization was completed and the mixture was gradually deposited on the surface of the biochar particles to form a polydopamine coating, thereby obtaining polydopamine-modified biochar.

[0063] (3) Loading of Fe-Cu ions: 10 g of polydopamine-modified biochar was immersed in 200 mL of a mixed solution of 0.1 M FeCl3 and 0.1 M CuCl2, stirred at 300 rpm for 2 h; washed with deionized water three times to remove unbound metal ions, and then dried at 60 °C for 12 h to obtain polydopamine-modified biochar loaded with Fe-Cu, as shown in FIG. Figure 1 shown.

[0064] (4) Preparation of sodium alginate microspheres: Dissolve 2 g of sodium alginate in 100 mL of deionized water and stir until completely dissolved. Mix 1 g of Fe-Cu loaded polydopamine-modified biochar with the sodium alginate solution and stir thoroughly until uniform; use a dropper to drop the mixture into a hardening solution with a concentration of 30 g / L calcium chloride at a rate of 2 mL / min, with the drop distance maintained at 3-5 cm to form microspheres. Let it stand in the hardening solution for 30 minutes to ensure that the microspheres are completely hardened. Remove the hardened microspheres from the calcium chloride solution and wash them three times in deionized water to remove excess sodium alginate and calcium ions. Dry the washed microspheres at 60°C for 12 hours until the microspheres are completely dry. Thus, polydopamine-modified biochar loaded with Fe-Cu sodium alginate microspheres are obtained.

[0065] The prepared sodium alginate microspheres of different particle sizes are as follows Figure 2 As shown in the SEM image of the porous structure of the sodium alginate microspheres Figure 3 As shown; XDR images of sodium alginate microspheres are shown Figure 4 shown.

[0066] The sodium alginate microspheres prepared in this example were used to perform adsorption tests on ammonia nitrogen, nitric nitrogen, chlorobenzene, phosphorus, chromium ions, and lead ions. The results are shown in Table 1 below.

[0067] Table 1 Results of ammonia nitrogen adsorption and nitric nitrogen adsorption by sodium alginate microspheres

[0068]

[0069] Example 2 Cultivation of Anaerobic Ammonium Oxidation Granular Sludge

[0070] The steps for cultivating anaerobic ammonium oxidation granular sludge are as follows:

[0071] (1) Take the ANAMMOX strain: Bacillus DMF-4 (which was deposited in China Center for Type Culture Collection on April 11, 2022 and has the deposit number CGTCC No. M2022413) Bacillus sp. DMF-4) and activated by culturing in anaerobic medium at 30°C for 1-2 weeks; the anaerobic medium contains: 1000 mg / L NH4Cl, 500 mg / L NaNO3, 50 mg / L KH2PO4, 50 mg / L KCl, 100 mg / L NaHCO3, and 2 mL / L trace element solution, including the following trace elements: H3BO3, MnC12, ZnSO4, Na3MoO4, and H2SeO3.

[0072] (2) In an anaerobic environment, activate the ANAMMOX bacteria: Bacillus DMF-4 ( Bacillus sp. DMF-4 was inoculated at a 5% volume fraction into a culture medium containing 1000 mg / L NH4Cl, 500 mg / L NaNO3, 50 mg / L KH2PO4, 50 mg / L KCl, 100 mg / L NaHCO3, and a trace element solution. Polydopamine-modified biochar-loaded Fe-Cu alginate microspheres prepared in Example 1 were added at a 10% weight volume fraction.

[0073] (3) The sodium alginate microspheres, sludge and water obtained in step (2) were cultured and monitored in an anaerobic continuous stirred reactor. During the culture process, the reactor was kept at a constant temperature of 30°C and a nitrogen closed system was used to prevent air from entering, so that the reactor remained in an anoxic state. The airtightness of the reactor was checked regularly and nitrogen was added when necessary to maintain an anaerobic environment. The NH4 in the culture medium was tested weekly. + and NO3 - concentration, ensuring it is within the range of 100-1000 mg / L and 50-300 mg / L; ensure that the reactor temperature is stable and avoid fluctuations.

[0074] After continuous cultivation for 3 weeks, the anaerobic ammonium oxidation granular sludge with a sodium alginate microsphere core is obtained by collecting the sludge by gravity sedimentation or centrifugation.

[0075] Anaerobic continuous stirred reactors such as Figure 5 As shown, it includes a stirring reaction chamber 1, a motor 2, a stirring shaft 3 connected to the motor 2, a stirring fan blade 4 is installed at the end of the stirring shaft 3, and a water inlet pipe 5, a water outlet pipe 6, and a nitrogen pipe 7 are connected to the wall of the stirring reaction chamber 1.

[0076] The sludge particles had a settling ratio of approximately 30%, a settling time of approximately 6 minutes, and a granulation degree of 91%. A series of characterization analyses were conducted on the sludge particles, including metal element distribution, metal valence, surface phase and crystal structure, specific surface area, and magnetic saturation intensity. The metal element distribution is shown in Table 2 below. The distribution of each element is relatively uniform, indicating good loading.

[0077] Table 2 Distribution of metal elements in granular sludge

[0078]

[0079] XRD analysis was performed and it was found that the metals and compounds were mainly FeS, CuFe2S3, (Cu,Fe)S2, FeS 2， Cu et al.

[0080] The specific surface area of ​​sludge particles is 331 m 3 g-1, total pore volume 1.72 cm 3 g-1, micropore volume 1.09 cm 3 g-1, average pore size 32 nm.

[0081] The sludge particles were characterized by hysteresis loops, and the saturation magnetization intensity was found to be 15.62 emu g-1. The material is magnetic and has magnetic separation capabilities, and can be easily recycled in other water treatment processes. The microspheres after sewage treatment are recovered by sedimentation or screening, and the recovered microspheres are then regenerated to restore their adsorption capacity. The average regeneration rate of the microspheres after different treatment methods such as acid washing, alkali washing, high temperature, cross-linking, and elution is as follows: Figure 6 shown.

[0082] The results showed that the regeneration rate reached about 90% through acid washing, alkali washing, high temperature, cross-linking and other methods of regeneration. The regeneration rate of elution method was slightly lower, at about 70%.

[0083] Example 3 Treatment Effect of Anaerobic Ammonium Oxidation Granular Sludge on Wastewater in an Anaerobic Continuous Stirred Reactor

[0084] The anaerobic ammonium oxidation granular sludge cultured in Example 2 was inoculated into Figure 3 In the stirred reaction chamber of the anaerobic continuous stirred reactor shown in the figure, sewage is connected to the reactor through the water inlet pipe. The sewage inlet indicators are ammonia nitrogen: 35-60 mg / L, nitrate nitrogen: 18-23 mg / L. The motor is started to stir the anaerobic ammonium oxidation granular sludge in the stirred reaction chamber to react with the sewage. During the 60 days of the reaction, sewage is taken out of the water pipe every day for testing. The results are as follows Figure 7 and Figure 8 shown.

[0085] The results showed that within 60 days after the sewage was treated with anaerobic ammonium oxidation granular sludge, the average removal rate of ammonia nitrogen was 91.9%; the average removal rate of nitrate nitrogen was 89%.

[0086] Anaerobic activated granular sludge recovered after sewage treatment Figure 9 shown.

[0087] Example 4 Application of Anaerobic Ammonium Oxidation Granular Sludge in Sewage Treatment

[0088] The sewage treatment plant in an industrial park mainly receives high-ammonia nitrogen wastewater discharged by chemical companies in the park, and uses the above-mentioned anaerobic ammonium oxidation granular sludge for treatment. Influent indicators: Chemical oxygen demand (COD): 200-600 mg / L, ammonia nitrogen (NH4 + -N): 300-800 mg / L, total nitrogen (TN): 400-1,000 mg / L. Key parameters are shown in the table. After three months of stable operation, the effluent ammonia nitrogen concentration is ≤5 mg / L, the total nitrogen removal rate is 90%, and the COD removal rate is 70%.

[0089]

[0090] This case study demonstrates the enormous potential of anaerobic ammonium oxidation (ANAMMOX) granular sludge in the treatment of high-ammonia nitrogen wastewater, and is suitable for the denitrification needs of industrial and municipal wastewater, providing a reference and inspiration for similar projects. This case study demonstrates the enormous potential of ANAMMOX granular sludge in the treatment of high-ammonia nitrogen wastewater, and is suitable for the denitrification needs of industrial and municipal wastewater, providing a reference and inspiration for similar projects.

[0091] All documents mentioned in this application are incorporated herein by reference, just as if each document were incorporated herein by reference individually. It should also be understood that after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and that such equivalents also fall within the scope of the present application.

Claims

1. A method for cultivating anaerobic ammonium oxidation granular sludge with a core of polydopamine-modified biochar-loaded Fe-Cu sodium alginate microspheres, characterized in that: The steps include: S1. Preparation of sodium alginate microspheres, steps are as follows: S1-1. Preparation of biochar: using biomass materials, carbonizing them in a nitrogen or inert gas environment at a temperature of 450-600°C, naturally cooling them and then crushing them, sieving them through a sieve to obtain biochar powder with a particle size of 0.5-1 mm, and drying them for later use; S1-2. Polydopamine coating: Biochar powder is dispersed in Tris buffer and uniformly dispersed by ultrasound to obtain a biochar particle suspension; a 1-2% by weight by volume dopamine solution is gradually added dropwise to the biochar, stirred at room temperature for 12-24 hours, and exposed to air for oxidation. When the color gradually changes from light yellow to dark brown, indicating that polymerization is complete, the dopamine coating is gradually deposited on the surface of the biochar particles to obtain a polydopamine-modified biochar; S1-3. Loading of Fe-Cu ions: Soak the polydopamine-modified biochar in a mixed solution of FeCl3 and CuCl2 at a ratio of 1-2 g: 20 mL and stir thoroughly; wash with deionized water and dry to obtain polydopamine-modified biochar loaded with Fe-Cu; S1-4. Preparation of sodium alginate microspheres: The Fe-Cu loaded polydopamine-modified biochar and a 2-4% sodium alginate solution by mass volume are uniformly mixed at a ratio of 1-2 g:100 mL; the mixed solution is dripped into a hardening solution at a rate of 1.5-2.5 mL / min to form microspheres; the microspheres are allowed to stand in the hardening solution for 30 minutes, and after hardening, are removed from the hardening solution and rinsed with water to obtain polydopamine-modified biochar loaded with Fe-Cu sodium alginate microspheres; S2. Cultivate anaerobic ammonium oxidation granular sludge, the steps are as follows: S2-1. Take the ANAMMOX strain (Bacillus DMF-4) with the accession number CGTCC No. M2022413 and culture it in anaerobic medium at 30°C for 1-2 weeks for activation; S2-2. In an anaerobic environment, the activated ANAMMOX strain: Bacillus DMF-4 is inoculated into an anaerobic culture medium at a volume fraction of 5-6%, and 8-10% by mass volume fraction of polydopamine-modified biochar loaded with Fe-Cu sodium alginate microspheres is added; S2-3. The polydopamine-modified biochar loaded with Fe-Cu sodium alginate microspheres, sludge, and water in step S2-2 are cultured and monitored in an anaerobic continuous stirred reactor. After continuous culture for 3 weeks, the anaerobic ammonia oxidation granular sludge is collected by gravity sedimentation or centrifugation to obtain a sodium alginate microsphere core.

2. The culture method according to claim 1, wherein In step S1-1, the biomass material is waste sludge or agricultural and forestry waste biomass.

3. The culture method according to claim 1, wherein In step S1-3, the mixed solution of FeCl3 and CuCl2 is prepared by mixing a FeCl3 solution with a concentration of 0.1-0.2M and a CuCl2 solution with a concentration of 0.1-0.2M.

4. The culture method according to claim 1, wherein In step S1-4, the hardening liquid is a 25-30 g / L calcium chloride solution.

5. The culture method according to claim 1, wherein In step S1-4, the drop distance of the mixed solution into the hardening solution to form microspheres is maintained at 3-5 cm.

6. The culture method according to claim 1, wherein In step S1-1 and step S1-3, the drying temperature is 50-80°C and the drying time is 10-15 hours.

7. The culture method according to claim 1, wherein In step S2-3, the culture conditions of the reactor are: maintaining the reactor in a nitrogen environment and a temperature of 25-30°C.

8. The culture method according to claim 1, wherein In step S2-3, the reactor detection conditions are: weekly detection, control of NH4 + Concentration 100-1000 mg / L, NO3 - Concentration within 50-300 mg / L.

9. Use of the anaerobic ammonium oxidation granular sludge prepared according to the method according to any one of claims 1 to 8 in sewage treatment.

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