A magnetic pyrite filler and its application in sewage denitrification and phosphorus removal

Abstract

The present invention belongs to the field of wastewater denitrification and phosphorus removal, and specifically relates to a novel magnetic pyrite filler and its application in wastewater denitrification and phosphorus removal. The invention comprises the following components by weight: 15-25 parts of pyrite powder, 12-15 parts of modified powder, 1-3 parts of calcium sulfide, 5-8 parts of sodium lignin sulfonate, 100-120 parts of deionized water, and 150-200 parts of mixed bacterial solution. The invention comprises the following steps: mixing the pyrite powder with the modified powder and calcium sulfide, stirring, adding sodium lignin sulfonate and deionized water, stirring, granulating, drying, heating to 350-400°C, and keeping warm for 1-3 hours to obtain a mixed filler; immersing the mixed filler in the mixed bacterial solution, oscillating and culturing, filtering, and drying to obtain a novel magnetic pyrite filler; the obtained novel magnetic pyrite filler has both excellent mechanical stability and efficient nitrogen and phosphorus removal efficiency, and achieves efficient removal of nitrogen and phosphorus pollutants in wastewater through the synergistic effect of physical adsorption and biodegradation.

Description

Technical Field

[0001] The invention belongs to the field of sewage denitrification and phosphorus removal, and particularly relates to a novel magnetic pyrite filler and application thereof in sewage denitrification and phosphorus removal. Background Art

[0002] With the acceleration of urbanization and the surge in industrial wastewater discharge, eutrophication of water bodies has become an environmental issue of global concern. Among wastewater denitrification and phosphorus removal technologies, the biological filler method has become one of the core processes for municipal sewage treatment plants and high-concentration industrial wastewater treatment due to its high treatment efficiency and economy. The current mainstream biological denitrification and phosphorus removal technologies rely on activated sludge or traditional fillers, but they have problems such as low biofilm attachment efficiency, poor synergy of functional bacterial communities, and weak resistance to shock loads. Although physical and chemical methods can quickly remove pollutants, they consume a lot of reagents and are prone to secondary pollution.

[0003] As a naturally occurring sulfur-containing iron mineral, pyrite possesses semiconductor properties and redox activity, theoretically enabling it to provide electrons or trace elements for microbial metabolism. However, single pyrite suffers from defects such as a monolithic pore structure, insufficient biocompatibility, and low electron transfer efficiency, limiting its application in wastewater purification. Developing new fillers with high surface area, electrochemical activity, and microbial affinity is crucial for improving the efficiency of nitrogen and phosphorus removal in wastewater. Summary of the Invention

[0004] In order to solve the above problems, the present invention proposes a new type of magnetic pyrite filler and its application in wastewater denitrification and phosphorus removal.

[0005] The present invention provides a novel magnetic pyrite filler, comprising the following components in parts by mass:

[0006] 15-25 parts of pyrite powder, 12-15 parts of modified powder, 1-3 parts of calcium sulfide, 5-8 parts of sodium lignin sulfonate, 100-120 parts of deionized water, and 150-200 parts of mixed bacterial solution.

[0007] Preferably, the modified powder is prepared by the following method:

[0008] The coconut shell activated carbon and egg shell are mixed, stirred, crushed, sieved, polyhydroxyalkanoate solution and modified carbon nanotubes are added, stirred, granulated, dried, heated to 700-800°C, and kept warm for 2-3 hours to obtain modified powder.

[0009] Preferably, the following components are included in parts by mass: 10-15 parts of coconut shell activated carbon, 4-6 parts of eggshell, 30-40 parts of polyhydroxyalkanoate solution, and 5-8 parts of modified carbon nanotubes.

[0010] Preferably, the modified carbon nanotubes are prepared by the following method:

[0011] Ferric chloride and ferrous chloride are added to deionized water, ultrasonically dispersed, manganese chloride is added, dispersed, carbon nanotubes and hexadecyltrimethylammonium bromide are added, stirred, ammonium nitrate is added, pH is adjusted, heated and stirred, allowed to stand for aging, centrifuged, the precipitate is collected, washed three times with ethanol, dried, and then the precipitate is calcined under nitrogen, cooled in the furnace, ground and sieved to obtain modified carbon nanotubes.

[0012] Preferably, the composition comprises the following components in parts by mass: 1-2 parts of ferric chloride, 2-4 parts of ferrous chloride, 3-4 parts of manganese chloride, 12-16 parts of carbon nanotubes, 0.05-0.1 parts of hexadecyltrimethylammonium bromide, 0.4-0.6 parts of ammonium nitrate, and 60-70 parts of deionized water.

[0013] A method for preparing a novel magnetic pyrite filler comprises the following steps:

[0014] S1. Weigh the raw materials in parts by mass, mix the pyrite powder with the modified powder and calcium sulfide, stir, add sodium lignin sulfonate and deionized water, stir, granulate, dry, heat to 350-400° C., and keep warm for 1-3 hours to prepare a mixed filler;

[0015] S2. Immerse the mixed filler in the mixed bacterial solution, culture under shaking for 48-60 hours, filter, and dry to obtain a new type of magnetic pyrite filler.

[0016] Preferably, in step S2, the mixed bacterial solution is prepared by the following method:

[0017] Agar and deionized water are mixed and stirred, glucose is added and stirred, and then Pseudomonas alcaligenes, Stenotrophomonas maltophilia and alkaline phosphatase are added, the pH is adjusted, the temperature is controlled at 28-32° C., and stirred to prepare a mixed bacterial solution.

[0018] Preferably, the composition comprises the following components in parts by mass: 3-5 parts of agar, 1-2 parts of glucose, 0.5-0.8 parts of Pseudomonas alcaligenes, 1-2 parts of Stenotrophomonas maltophilia, 0.1-0.2 parts of alkaline phosphatase, and 80-100 parts of deionized water.

[0019] The present invention also provides an application of a novel magnetic pyrite filler in denitrification and dephosphorization of sewage.

[0020] The present invention has the following beneficial effects:

[0021] The present invention reacts ferric chloride, ferrous chloride and manganese chloride with carbon nanotubes, and then undergoes a calcination process to successfully produce modified carbon nanotubes, which have a high specific surface area and can adsorb nitrogen and phosphorus pollutants. The ferrosoferric oxide and manganese elements on its surface form numerous active sites that can participate in the redox reactions of nitrogen and phosphorus and accelerate the reaction process. The carbon nanotubes themselves have good electronic conductivity, which enables rapid electron transfer within the material, provides an electron channel for the redox reaction, and increases the reaction rate. The modified carbon nanotubes form a three-dimensional interwoven network structure with other raw materials, which enhances the overall structural stability of the filler, prevents the material from breaking and pulverizing during use, and also optimizes the pore structure of the filler, ensuring efficient mass transfer of pollutants and ensuring that the material maintains stable processing performance during long-term operation.

[0022] Coconut shell activated carbon and eggshells are mixed, crushed, and then composited with polyhydroxyalkanoate and modified carbon nanotubes to produce a modified powder with a multi-dimensional synergistic effect. The coconut shell activated carbon, with its rich pore structure and high specific surface area, efficiently enriches nitrogen- and phosphorus-containing pollutants through a physical adsorption mechanism. The ferroferric oxide and manganese-based active components loaded on the surface of the modified carbon nanotubes react specifically with nitrogen and phosphorus substances through chemical adsorption and coordination complexation, stably fixing them on the material surface. The iron in the pyrite powder can also form insoluble iron phosphates with phosphorus, thereby achieving chemical fixation of phosphorus and establishing an efficient pollutant retention system. The ferroferric oxide / manganese redox system on the surface of the modified carbon nanotubes forms a functional coupling with the high electrical conductivity of the carbon nanotubes. During the denitrification and dephosphorization processes, this system can rapidly transfer electrons, significantly reducing the activation energy of the reaction and accelerating the nitrogen and phosphorus conversion reaction process. Polyhydroxyalkanoate, as a biodegradable high-molecular carbon source, can induce the recovery and growth of microorganisms with denitrification and phosphorus removal functions under trace moisture or suitable environmental stimulation. After these microorganisms form a biofilm on the surface of the material, the enzymes produced by the microbial metabolic activities can catalyze the nitrogen and phosphorus conversion reactions. The adsorption and catalytic properties of the material provide a stable nutrient source and reaction site for the microorganisms, resulting in a synergistic effect. A multi-stage synergistic denitrification and phosphorus removal system is constructed under anhydrous or low-moisture conditions, significantly improving the treatment efficiency and stability.

[0023] The present invention thoroughly mixes pyrite powder, modified powder, and calcium sulfide, then adds sodium lignin sulfonate and deionized water and continues stirring. The mixture is then granulated, dried, and calcined at high temperature to produce a mixed filler. This mixed filler further reacts with a mixed bacterial solution to produce a novel magnetic pyrite filler. During the oscillation culture phase, Pseudomonas alcaligenes, Stenotrophomonas maltophilia, and alkaline phosphatase in the mixed bacterial solution gradually adhere to the filler surface, forming a richly structured biofilm. This biofilm has a large specific surface area, providing ample living space for microorganisms and creating an efficient interface with pollutants in wastewater, enabling more efficient capture and degradation of various pollutants. The biofilm firmly secures the microorganisms to the filler, effectively preventing their loss with water and significantly improving their retention and stability in the wastewater treatment system. The manganese ions and ferroferric oxide loaded on the carbon nanotube surface significantly influence the physicochemical properties of the filler surface, altering the surface charge distribution and optimizing the pore structure. These changes create a more suitable living environment for microorganisms, greatly promoting their attachment and growth on the filler surface. Furthermore, manganese ions and ferroferric oxide have strong redox activity, allowing them to undergo redox reactions with microbial metabolites, further accelerating the conversion of pollutants and enhancing the overall effectiveness of the new magnetic pyrite filler in wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram of an autotrophic denitrification device for testing filler performance in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0025] Pyrite was purchased from Lingshou County Chenyang Mineral Products Co., Ltd. and crushed through a 300-mesh sieve before use; coconut shell activated carbon was purchased from Henan Weilan Environmental Protection Engineering Co., Ltd., 60 mesh; carbon nanotubes were purchased from Shanghai Gaibang Industrial Co., Ltd., product number: XT-CNTs, particle size 8 nm; Pseudomonas alcaligenes was purchased from Wuhan Huizao Biotechnology Co., Ltd. Hangzhou Branch, product number: HZB115066, freeze-dried powder; Stenotrophomonas maltophilia was purchased from Ningbo Mingzhou Biotechnology Co., Ltd., product number: BMZ106708, freeze-dried powder; alkaline phosphatase was purchased from Hubei Jianchu Biotechnology Co., Ltd., CAS number: 9001-78-9, active ingredient content: 99%; calcium sulfide was purchased from Wuhan Jiyesheng Chemical Co., Ltd., powder.

[0026] Example 1

[0027] A novel magnetic pyrite filler comprises the following components in parts by weight:

[0028] 15 parts of pyrite powder, 12 parts of modified powder, 1 part of calcium sulfide, 5 parts of sodium lignin sulfonate, 100 parts of deionized water, and 150 parts of mixed bacterial liquid.

[0029] The modified powder is prepared by the following method:

[0030] Coconut shell activated carbon and eggshell are mixed, mixed at 200 rpm for 30 minutes, crushed, passed through a 100-mesh sieve, polyhydroxyalkanoate solution and modified carbon nanotubes are added, stirred at 200 rpm for 20 minutes, granulated, and the particle size is controlled to 2 mm. The mixture is dried at 40°C for 12 hours; heated to 400°C at a rate of 5°C / min, kept warm for 1 hour, then heated to 700°C at a rate of 2°C / min, kept warm for 2 hours, and cooled with the furnace to obtain a mixed powder; the mixed powder comprises 10 parts of coconut shell activated carbon, 4 parts of eggshell, 30 parts of polyhydroxyalkanoate solution, and 5 parts of modified carbon nanotubes; the polyhydroxyalkanoate is dispersed in acetone and stirred at 100 rpm for 10 minutes to obtain a polyhydroxyalkanoate solution with a mass fraction of 15%.

[0031] The modified carbon nanotubes are prepared by the following method:

[0032] Ferric chloride and ferrous chloride are added to deionized water, ultrasonically dispersed at 20kHz for 5 minutes, manganese chloride is added, dispersed for 10 minutes, carbon nanotubes and hexadecyltrimethylammonium bromide are added, stirred at 100rpm for 10 minutes, ammonium nitrate is added, the pH is adjusted to 9, heated to 60°C, stirred at 100rpm for 3 hours, allowed to stand for aging at room temperature for 8 hours, centrifuged at 4000rpm for 10 minutes, the precipitate is collected, washed with ethanol 3 times, dried at 60°C for 6 hours, and then the precipitate is calcined under nitrogen, heated to 280°C at a rate of 5°C / min, kept warm for 2 hours, then heated to 400°C at a rate of 2°C / min, kept warm for 1 hour, cooled with the furnace, and ground through a 100-mesh sieve to obtain modified carbon nanotubes; wherein, ferric chloride is 1 part, ferrous chloride is 2 parts, manganese chloride is 3 parts, carbon nanotubes are 12 parts, hexadecyltrimethylammonium bromide is 0.05 parts, ammonium nitrate is 0.4 parts, and deionized water is 60 parts.

[0033] A method for preparing a novel magnetic pyrite filler comprises the following steps:

[0034] S1. Weigh the raw materials in parts by mass, mix the pyrite powder with the modified powder and calcium sulfide, stir at 200 rpm for 15 min, add sodium lignin sulfonate and deionized water, stir for 8 min, granulate, control the particle size to 3 mm, dry at 60 ° C for 4 h, heat to 350 ° C at a rate of 5 ° C / min, keep warm for 1 h, and cool with the furnace to obtain a mixed filler;

[0035] S2. Immerse the mixed filler in the mixed bacterial solution, shake and culture at 150 rpm for 48 hours, filter, and dry at 25°C for 24 hours to obtain a new magnetic pyrite filler; wherein, the mixed bacterial solution is prepared by the following method: mix agar and deionized water, stir, add glucose, stir, then add Pseudomonas alcaligenes, Stenotrophomonas maltophilia and alkaline phosphatase, adjust the pH to 7.5, control the temperature to 28°C, and stir at 100 rpm for 15 minutes to obtain; wherein, 3 parts of agar, 1 part of glucose, 0.5 parts of Pseudomonas alcaligenes, 1 part of Stenotrophomonas maltophilia, 0.1 parts of alkaline phosphatase, and 80 parts of deionized water.

[0036] Application of a new type of magnetic pyrite filler in wastewater denitrification and phosphorus removal.

[0037] Example 2

[0038] A novel magnetic pyrite filler comprises the following components in parts by weight:

[0039] 25 parts of pyrite powder, 15 parts of modified powder, 3 parts of calcium sulfide, 8 parts of sodium lignin sulfonate, 120 parts of deionized water, and 200 parts of mixed bacterial liquid.

[0040] The modified powder is prepared by the following method:

[0041] Coconut shell activated carbon and eggshell are mixed, mixed at 300 rpm for 40 minutes, crushed, passed through a 150 mesh sieve, polyhydroxyalkanoate solution and modified carbon nanotubes are added, stirred at 300 rpm for 30 minutes, granulated, and the particle size is controlled to 4 mm. The mixture is dried at 50°C for 24 hours; heated to 500°C at a rate of 8°C / min, kept warm for 2 hours, then heated to 800°C at a rate of 3°C / min, kept warm for 3 hours, and cooled with the furnace to obtain a mixed powder; the mixed powder comprises 15 parts of coconut shell activated carbon, 6 parts of eggshell, 40 parts of polyhydroxyalkanoate solution, and 8 parts of modified carbon nanotubes; the polyhydroxyalkanoate is dispersed in acetone and stirred at 150 rpm for 20 minutes to obtain a polyhydroxyalkanoate solution with a mass fraction of 15%.

[0042] The modified carbon nanotubes are prepared by the following method:

[0043] Ferric chloride and ferrous chloride are added to deionized water, ultrasonically dispersed at 30kHz for 8 minutes, manganese chloride is added, dispersed for 15 minutes, carbon nanotubes and hexadecyltrimethylammonium bromide are added, stirred at 150rpm for 15 minutes, ammonium nitrate is added, the pH is adjusted to 11, heated to 70℃, stirred at 200rpm for 4 hours, allowed to stand for aging at room temperature for 12 hours, centrifuged at 5000rpm for 15 minutes, the precipitate is collected, washed with ethanol 3 times, dried at 80℃ for 8 hours, and then calcined under nitrogen, heated to 350℃ at a rate of 8℃ / min, kept warm for 3 hours, then heated to 450℃ at a rate of 4℃ / min, kept warm for 2 hours, cooled with the furnace, and ground through a 150-mesh sieve to obtain modified carbon nanotubes; wherein, ferric chloride 2 parts, ferrous chloride 4 parts, manganese chloride 4 parts, carbon nanotubes 16 parts, hexadecyltrimethylammonium bromide 0.1 parts, ammonium nitrate 0.6 parts, and deionized water 70 parts.

[0044] A method for preparing a novel magnetic pyrite filler comprises the following steps:

[0045] S1. Weigh the raw materials in parts by mass, mix the pyrite powder with the modified powder and calcium sulfide, stir at 300 rpm for 20 min, add sodium lignin sulfonate and deionized water, stir for 15 min, granulate, control the particle size to 4 mm, dry at 70 ° C for 6 h, heat to 400 ° C at a rate of 7 ° C / min, keep warm for 3 h, and cool with the furnace to obtain a mixed filler;

[0046] S2. Immerse the mixed filler in the mixed bacterial solution, shake and culture at 200 rpm for 60 hours, filter, and dry at 30°C for 36 hours to obtain a new magnetic pyrite filler; wherein, the mixed bacterial solution is prepared by the following method: mix agar and deionized water, stir, add glucose, stir, then add Pseudomonas alcaligenes, Stenotrophomonas maltophilia and alkaline phosphatase, adjust the pH to 7.5, control the temperature to 32°C, and stir at 200 rpm for 20 minutes to obtain; wherein, 5 parts of agar, 2 parts of glucose, 0.8 parts of Pseudomonas alcaligenes, 2 parts of Stenotrophomonas maltophilia, 0.2 parts of alkaline phosphatase, and 100 parts of deionized water.

[0047] Application of a new type of magnetic pyrite filler in wastewater denitrification and phosphorus removal.

[0048] Example 3

[0049] A novel magnetic pyrite filler comprises the following components in parts by weight:

[0050] 20 parts of pyrite powder, 14 parts of modified powder, 2 parts of calcium sulfide, 6 parts of sodium lignin sulfonate, 110 parts of deionized water, and 180 parts of mixed bacterial liquid.

[0051] The modified powder is prepared by the following method:

[0052] Coconut shell activated carbon and eggshell were mixed at 260 rpm for 35 minutes, crushed, passed through a 130 mesh sieve, polyhydroxyalkanoate solution and modified carbon nanotubes were added, stirred at 260 rpm for 25 minutes, granulated, and the particle size was controlled to 3 mm. The mixture was dried at 45°C for 18 hours; heated to 450°C at a rate of 6°C / min, kept warm for 1.5 hours, then heated to 750°C at a rate of 3°C / min, kept warm for 2.5 hours, and cooled in the furnace to obtain a mixed powder; the mixed powder contained 12 parts of coconut shell activated carbon, 5 parts of eggshell, 35 parts of polyhydroxyalkanoate solution, and 7 parts of modified carbon nanotubes; the polyhydroxyalkanoate was dispersed in acetone and stirred at 120 rpm for 15 minutes to obtain a polyhydroxyalkanoate solution with a mass fraction of 15%.

[0053] The modified carbon nanotubes are prepared by the following method:

[0054] Ferric chloride and ferrous chloride were added to deionized water, ultrasonically dispersed at 25 kHz for 7 minutes, manganese chloride was added, dispersed for 13 minutes, carbon nanotubes and hexadecyltrimethylammonium bromide were added, stirred at 130 rpm for 12 minutes, ammonium nitrate was added, the pH was adjusted to 10, heated to 65 ° C, stirred at 150 rpm for 3.5 hours, allowed to stand at room temperature for 10 hours, centrifuged at 4500 rpm for 13 minutes, the precipitate was collected, washed with ethanol three times, and then The mixture was dried at 70°C for 7 hours, and then the precipitate was calcined under nitrogen, heated to 330°C at a rate of 7°C / min, kept warm for 2.5 hours, and then heated to 430°C at a rate of 3°C / min, kept warm for 1.5 hours, cooled with the furnace, and ground through a 130-mesh sieve to obtain modified carbon nanotubes; wherein, the mixture contained 1.5 parts of ferric chloride, 3 parts of ferrous chloride, 3.5 parts of manganese chloride, 14 parts of carbon nanotubes, 0.08 parts of hexadecyltrimethylammonium bromide, 0.5 parts of ammonium nitrate, and 65 parts of deionized water.

[0055] A method for preparing a novel magnetic pyrite filler comprises the following steps:

[0056] S1. Weigh the raw materials in parts by mass, mix the pyrite powder with the modified powder and calcium sulfide, stir at 260 rpm for 18 min, add sodium lignin sulfonate and deionized water, stir for 13 min, granulate, control the particle size to 3.5 mm, dry at 65 ° C for 5 h, heat to 380 ° C at a rate of 6 ° C / min, keep warm for 2 h, and cool with the furnace to obtain a mixed filler;

[0057] S2. Immerse the mixed filler in the mixed bacterial solution, shake and culture at 180 rpm for 54 hours, filter, and dry at 28°C for 30 hours to obtain a new magnetic pyrite filler; wherein, the mixed bacterial solution is prepared by the following method: mix agar and deionized water, stir, add glucose, stir, then add Pseudomonas alcaligenes, Stenotrophomonas maltophilia and alkaline phosphatase, adjust the pH to 7.5, control the temperature to 30°C, and stir at 150 rpm for 18 minutes to obtain; wherein, 4 parts of agar, 1.5 parts of glucose, 0.7 parts of Pseudomonas alcaligenes, 1.5 parts of Stenotrophomonas maltophilia, 0.2 parts of alkaline phosphatase, and 90 parts of deionized water.

[0058] Application of a new type of magnetic pyrite filler in wastewater denitrification and phosphorus removal.

[0059] Comparative Example 1

[0060] Comparative Example 1 is the same as Example 1, except that the preparation method of the modified powder is different, as follows:

[0061] The modified powder was prepared by the following method:

[0062] The eggshells were crushed and passed through a 100-mesh sieve. A polyhydroxyalkanoate solution and modified carbon nanotubes were added. The mixture was stirred at 200 rpm for 20 minutes, granulated, and the particle size was controlled to be 2 mm. The mixture was dried at 40°C for 12 hours. The mixture was heated to 400°C at a rate of 5°C / min, kept warm for 1 hour, and then heated to 700°C at a rate of 2°C / min, kept warm for 2 hours, and cooled in the furnace to obtain a mixed powder. The mixed powder consisted of 14 parts of eggshells, 30 parts of polyhydroxyalkanoate solution, and 5 parts of modified carbon nanotubes. The polyhydroxyalkanoate was dispersed in acetone and stirred at 100 rpm for 10 minutes to obtain a polyhydroxyalkanoate solution with a mass fraction of 15%.

[0063] Comparative Example 2

[0064] Comparative Example 2 is the same as Example 1, except that the preparation method of the modified powder is different, as follows:

[0065] The modified powder was prepared by the following method:

[0066] Coconut shell activated carbon and eggshell are mixed, mixed at 200rpm for 30min, crushed, passed through a 100-mesh sieve, modified carbon nanotubes and deionized water are added, stirred at 200rpm for 20min, granulated, the particle size is controlled to be 2mm, and dried at 40°C for 12h; heated to 400°C at a rate of 5°C / min, kept warm for 1h, then heated to 700°C at a rate of 2°C / min, kept warm for 2h, and cooled with the furnace to obtain a mixed powder; wherein, the mixed powder comprises 10 parts of coconut shell activated carbon, 4 parts of eggshell, 30 parts of deionized water, and 5 parts of modified carbon nanotubes.

[0067] Comparative Example 3

[0068] Comparative Example 3 is the same as Example 1, except that the preparation method of the modified carbon nanotubes is different, as follows:

[0069] Modified carbon nanotubes are prepared by the following method:

[0070] Manganese chloride was added to deionized water, ultrasonically dispersed at 20 kHz for 5 minutes, carbon nanotubes and hexadecyltrimethylammonium bromide were added, stirred at 100 rpm for 10 minutes, ammonium nitrate was added, the pH was adjusted to 9, heated to 60°C, stirred at 100 rpm for 3 hours, allowed to stand and aged at room temperature for 8 hours, centrifuged at 4000 rpm for 10 minutes, the precipitate was collected, washed 3 times with ethanol, and dried at 60°C for 6 hours. The precipitate was then calcined under nitrogen, heated to 280°C at a rate of 5°C / min, kept warm for 2 hours, then heated to 400°C at a rate of 2°C / min, kept warm for 1 hour, cooled with the furnace, and ground through a 100-mesh sieve to obtain modified carbon nanotubes; wherein, manganese chloride was 6 parts, carbon nanotubes were 12 parts, hexadecyltrimethylammonium bromide was 0.05 parts, ammonium nitrate was 0.4 parts, and deionized water was 60 parts.

[0071] Comparative Example 4

[0072] Comparative Example 4 is the same as Example 1, except that the preparation method of the modified carbon nanotubes is different, as follows:

[0073] Modified carbon nanotubes are prepared by the following method:

[0074] Ferric chloride and ferrous chloride are added to deionized water, ultrasonically dispersed at 20kHz for 5 minutes, carbon nanotubes and hexadecyltrimethylammonium bromide are added, stirred at 100rpm for 10 minutes, ammonium nitrate is added, the pH is adjusted to 9, heated to 60°C, stirred at 100rpm for 3 hours, allowed to stand and age at room temperature for 8 hours, centrifuged at 4000rpm for 10 minutes, the precipitate is collected, washed with ethanol 3 times, dried at 60°C for 6 hours, and then the precipitate is calcined under nitrogen, heated to 280°C at a rate of 5°C / min, kept warm for 2 hours, then heated to 400°C at a rate of 2°C / min, kept warm for 1 hour, cooled with the furnace, and ground through a 100-mesh sieve to obtain modified carbon nanotubes; wherein, ferric chloride 2 parts, ferrous chloride 4 parts, carbon nanotubes 12 parts, hexadecyltrimethylammonium bromide 0.05 parts, ammonium nitrate 0.4 parts, and deionized water 60 parts.

[0075] Comparative Example 5

[0076] Comparative Example 5 is the same as Example 1, except that the preparation method of the mixed bacterial solution is different, specifically:

[0077] The mixed bacterial solution was prepared by the following method:

[0078] Agar and deionized water are mixed and stirred, glucose is added and stirred, and then Pseudomonas alcaligenes and alkaline phosphatase are added. The pH is adjusted to 7.5, the temperature is controlled at 28° C., and stirring is carried out at 100 rpm for 15 minutes to obtain a preparation comprising 3 parts of agar, 1 part of glucose, 1.5 parts of Pseudomonas alcaligenes, 0.1 part of alkaline phosphatase, and 80 parts of deionized water.

[0079] Comparative Example 6

[0080] Comparative Example 6 is the same as Example 1, except that the preparation method of the mixed bacterial solution is different, specifically:

[0081] The mixed bacterial solution was prepared by the following method:

[0082] Agar and deionized water are mixed and stirred, glucose is added and stirred, and then Stenotrophomonas maltophilia and alkaline phosphatase are added. The pH is adjusted to 7.5, the temperature is controlled at 28° C., and stirring is carried out at 100 rpm for 15 minutes to obtain a preparation comprising 3 parts of agar, 1 part of glucose, 1.5 parts of Stenotrophomonas maltophilia, 0.1 part of alkaline phosphatase, and 80 parts of deionized water.

[0083] Comparative Example 7

[0084] Comparative Example 7 is the same as Example 1, except that the preparation method of the mixed bacterial solution is different, specifically:

[0085] The mixed bacterial solution was prepared by the following method:

[0086] Agar and deionized water are mixed and stirred, glucose is added and stirred, and then Pseudomonas alcaligenes and Stenotrophomonas maltophilia are added, the pH is adjusted to 7.5, the temperature is controlled at 28° C., and stirring is carried out at 100 rpm for 15 minutes to obtain a preparation comprising 3 parts of agar, 1 part of glucose, 0.55 parts of Pseudomonas alcaligenes, 1.05 parts of Stenotrophomonas maltophilia, and 80 parts of deionized water.

[0087] Performance Testing

[0088] The following performance tests were performed on the new magnetic pyrite fillers prepared in Examples 1-3 and Comparative Examples 1-7:

[0089] like Figure 1 The apparatus shown in the figure was used to construct two identical upflow anaerobic fixed-bed reactors with an inner diameter of 6.6 cm and a height of 40 cm, namely B1 and B2. At the same time, porous plastic suspension fillers were filled to reduce the filtration resistance of the system. The porous plastic suspension fillers and the new magnetic pyrite fillers were filled in layers. The reactor was operated in a constant temperature water tank at 28°C for 10 days. The NO 3- The removal efficiency of N and PO 3- The removal efficiency of P in B1 is 3-The removal rate of N in the water was 72.41%, and the removal rate of PO 3- The removal rate of P in the medium was 84.45%;

[0090] Compressive strength test: The compressive strength test of each embodiment and comparative example was carried out using a servo multifunctional high and low temperature control testing machine. Three groups of tests were conducted on each sample, and the average value was taken.

[0091] The test results are shown in Table 1.

[0092] Table 1 Performance test results

[0093]

[0094] The performance data of Example 1 and Comparative Examples 1-2 show that coconut shell activated carbon, with its developed pore structure and excellent specific surface area, can achieve efficient enrichment and retention of nitrogen-phosphorus pollutants such as ammonia nitrogen, nitrate nitrogen, and phosphate through physical adsorption mechanisms such as van der Waals forces, electrostatic effects, and pore screening, providing a material basis for subsequent biochemical transformations; polyhydroxyalkanoate, as a biodegradable polymer carbon source, can induce the colonization and proliferation of denitrification and phosphorus removal functional bacteria under trace moisture or environmental stimulation, prompting them to form a biofilm with high metabolic activity on the surface of the material. The biofilm constructs a synergistic removal system through the functional enzymes secreted by microorganisms. The combined introduction of coconut shell activated carbon and polyhydroxyalkanoate significantly improves the denitrification and phosphorus removal efficiency of the filler under complex water conditions by enhancing the pollutant retention efficiency and activating the microbial metabolic pathway.

[0095] According to the test results of Example 1 and Comparative Examples 3-4, the ferroferric oxide and the manganese-based active components constructed on the surface of carbon nanotubes form a heterostructure with redox activity, and the Fe²⁺ / Fe³⁺ and Mn²⁺ / Mn²⁺ exposed on the surface 4 ⁺ Isoelectric pairs form abundant catalytically active sites. These sites significantly accelerate the redox reaction kinetics of nitrogen and phosphorus pollutants by reducing the reaction activation energy. Furthermore, the inherent high conductivity of carbon nanotubes, combined with their one-dimensional nanostructure, creates efficient electron transport channels within the material, enabling the directional and rapid migration of electrons during redox reactions. This electron conduction property, synergistic with the catalytic function of the surface active sites, effectively improves the electron utilization efficiency and material conversion rate of nitrogen and phosphorus conversion reactions, thereby significantly enhancing the filler's denitrification and dephosphorization performance.

[0096] According to the test results of Example 1 and Comparative Examples 5-7, the mixed bacterial liquid made of Pseudomonas alcaligenes, Stenotrophomonas maltophilia and alkaline phosphatase will gradually adhere to the surface of the filler during the oscillation culture stage, and then form a layer of biofilm with rich structure. Through the multiple effects of microbial surface adsorption and biofilm pore interception, the capture efficiency of nitrogen and phosphorus pollutants and organic substrates in sewage is significantly enhanced, and the catalytic action of the microbial intracellular enzyme system is combined to achieve efficient degradation and conversion of various pollutants; alkaline phosphatase catalyzes the hydrolysis of organophosphorus compounds and converts them into inorganic phosphorus forms that can be directly utilized by microorganisms. The inorganic phosphorus generated in this process can be taken up by Pseudomonas alcaligenes and Stenotrophomonas maltophilia through active transport mechanism, and synthesized into polyphosphate storage under the action of intracellular polyphosphate kinase, thereby significantly enhancing the enrichment efficiency of the filler surface biofilm for phosphorus. In addition, alkaline phosphatase effectively addresses the problem of treatment efficiency fluctuation caused by fluctuations in phosphorus forms in wastewater through its continuous catalytic effect, especially in high-proportion organic phosphorus pollution scenarios, it can achieve efficient targeted regulation of phosphorus.

[0097] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A magnetic pyrite filler, characterized in that: The composition comprises the following components in parts by weight: 15-25 parts of pyrite powder, 12-15 parts of modified powder, 1-3 parts of calcium sulfide, 5-8 parts of sodium lignin sulfonate, 100-120 parts of deionized water, and 150-200 parts of mixed bacterial solution; The modified powder is prepared by the following method: Mix coconut shell activated carbon and eggshell, stir, crush, sieve, add polyhydroxyalkanoate solution and modified carbon nanotubes, stir, granulate, dry, heat to 700-800℃, keep warm for 2-3h to obtain modified powder; The modified carbon nanotubes are prepared by the following method: Ferric chloride and ferrous chloride are added to deionized water, ultrasonically dispersed, manganese chloride is added, dispersed, carbon nanotubes and hexadecyltrimethylammonium bromide are added, stirred, ammonium nitrate is added, pH is adjusted, heated and stirred, allowed to stand for aging, centrifuged, a precipitate is collected, washed three times with ethanol, dried, and then the precipitate is calcined under nitrogen, cooled in the furnace, ground and sieved to obtain modified carbon nanotubes; The mixed bacterial solution is prepared by the following method: Agar and deionized water are mixed and stirred, glucose is added and stirred, and then Pseudomonas alcaligenes, Stenotrophomonas maltophilia and alkaline phosphatase are added, the pH is adjusted, the temperature is controlled at 28-32° C., and stirred to prepare a mixed bacterial solution.

2. A magnetic pyrite filler according to claim 1, characterized in that, The raw materials for preparing the modified powder are as follows: 10-15 parts by mass of coconut shell activated carbon, 4-6 parts by mass of eggshell, 30-40 parts by mass of polyhydroxyalkanoate solution, and 5-8 parts by mass of modified carbon nanotubes.

3. A magnetic pyrite filler according to claim 1, characterized in that, The raw materials for preparing the modified carbon nanotubes are as follows: by mass, 1-2 parts of ferric chloride, 2-4 parts of ferrous chloride, 3-4 parts of manganese chloride, 12-16 parts of carbon nanotubes, 0.05-0.1 parts of hexadecyltrimethylammonium bromide, 0.4-0.6 parts of ammonium nitrate, and 60-70 parts of deionized water.

4. A method for preparing the magnetic pyrite filler according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Weigh the raw materials in parts by mass, mix the pyrite powder with the modified powder and calcium sulfide, stir, add sodium lignin sulfonate and deionized water, stir, granulate, dry, heat to 350-400° C., and keep warm for 1-3 hours to prepare a mixed filler; S2. Immerse the mixed filler in the mixed bacterial solution, culture under shaking for 48-60 hours, filter, and dry to obtain the magnetic pyrite filler.

5. The method for preparing a magnetic pyrite filler according to claim 4, wherein: The raw materials for preparing the mixed bacterial solution in step S2 are as follows: 3-5 parts of agar, 1-2 parts of glucose, 0.5-0.8 parts of Pseudomonas alcaligenes, 1-2 parts of Stenotrophomonas maltophilia, 0.1-0.2 parts of alkaline phosphatase, and 80-100 parts of deionized water, calculated by mass.

6. Use of the magnetic pyrite filler according to any one of claims 1 to 3 in denitrification and dephosphorization of sewage.

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