Rotary disc system of biofilter based on replaceable composite filler and method for removing nitrogen and phosphorus

Abstract

The application relates to the technical field of sewage treatment, and discloses a biological filter rotating disc system based on replaceable composite fillers and a nitrogen and phosphorus removal method. 2+ The biological filter rotating disc system supports online filler replacement and is suitable for upgrading and reconstruction of sewage plants and advanced treatment of industrial wastewater.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, specifically to a biological filter rotary disc system based on replaceable composite packing material and a method for nitrogen and phosphorus removal. Background Technology

[0002] With the acceleration of urbanization and the expansion of industrial activities, eutrophication of water bodies is becoming increasingly serious, and the excessive discharge of nutrients such as nitrogen and phosphorus has become one of the core problems of global water pollution. Therefore, the development of efficient, energy-saving, and sustainable nitrogen and phosphorus removal technologies has become a research hotspot in the field of water treatment.

[0003] Rotating Biological Contactor (RBC) systems, as a classic biofilm process, are widely used in small to medium-sized wastewater treatment applications due to their advantages such as low energy consumption, ease of maintenance, and strong resistance to shock loads. Their core principle is to use the rotation of the disc to alternately contact the biofilm with wastewater and air, utilizing the microbial community attached to the disc to degrade pollutants. However, existing technologies still have the following drawbacks:

[0004] 1. The packing material is not replaceable: The packing material of traditional biological rotating discs is fixed and cannot be disassembled. After the autotrophic denitrification materials such as pyrite are exhausted, the whole thing needs to be replaced, which is costly.

[0005] 2. Microbial competition inhibition: Heterotrophic denitrification and autotrophic denitrification are not separated, and competition for carbon sources leads to unstable nitrite accumulation;

[0006] 3. Poor activity at low temperatures: Conventional biofilm carriers have low specific surface area, and the activity of anaerobic ammonia oxidizing bacteria decreases by more than 50% at low temperatures (<15℃);

[0007] 4. Limited simultaneous phosphorus removal: The release of iron ions is uncontrollable and easily forms iron salt precipitates that block the carrier pores. Summary of the Invention

[0008] In summary, this application aims to provide a biological filter rotary disc system based on replaceable composite packing material and a method for nitrogen and phosphorus removal. Through the encapsulation of PVDC discs and composite packing material, zoned reaction design, and Fe²⁺ synergistic enhancement mechanism, efficient simultaneous nitrogen and phosphorus removal from wastewater at low temperatures is achieved. The biological filter rotary disc system supports online packing material replacement and is suitable for advanced treatment of municipal wastewater and industrial wastewater, as well as efficient nitrogen and phosphorus removal under low-temperature environments.

[0009] To achieve the above objectives, this application adopts the following technical solution:

[0010] In a first aspect, this application provides a biological filter disc system based on replaceable composite packing material, comprising a disc assembly composed of PVDC discs connected in series, a stainless steel rotating shaft for connecting the PVDC discs in series, a detachable sealing cover plate provided at the edge of the PVDC discs, and a cavity provided inside the PVDC discs; the cavity is filled with sulfur-pyrite-magnetite composite packing material and anaerobic ammonia oxidizing bacteria; the surface of the PVDC discs is loaded with heterotrophic denitrifying bacteria.

[0011] Secondly, this application provides a method for nitrogen and phosphorus removal achieved through the aforementioned biological filter rotating disc system based on replaceable composite packing material, comprising the following steps:

[0012] Pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica are mixed, and silane coupling agent is added dropwise to the mixture while stirring.

[0013] After the silane coupling agent is added, continue stirring the mixture for 5-10 minutes, discharge the material, exhaust the air, seal and store for 20-24 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0014] Open the removable sealing cover plate set on the edge of the PVDC disk and fill the cavity set inside the PVDC disk with sulfur-pyrite-magnetite composite filler;

[0015] The cavity is filled with sulfur-pyrite-magnetite composite packing material, and the filled PVDC discs are connected in series by a stainless steel rotating shaft to form a disc group, thus obtaining a biological filter disc system based on replaceable composite packing material.

[0016] The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0017] When the rotary disc system is started, the wastewater undergoes heterotrophic denitrification on the outer layer of the disc and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the disc, simultaneously removing nitrogen and phosphorus to obtain primary treated water.

[0018] The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0019] The secondary treated water is tested and discharged only after it meets the standards. At the same time, the sulfur-pyrite-magnetite composite packing in the cavity is replaced regularly.

[0020] Compared with the prior art, the beneficial effects of this application include:

[0021] 1. Modular and replaceable design

[0022] The use of hot-pressed PVDC discs and removable sealing covers enables online replacement of the composite packing material, avoiding the need for complete replacement. Furthermore, the high corrosion resistance of PVDC material reduces losses due to corrosion, extending the system's service life. In summary, this can extend the packing replacement cycle of the biological filter rotary disc system to 2-3 years, reduce maintenance costs by 60%, and extend the service life to over 10 years.

[0023] 2. Regional synergistic nitrogen removal mechanism

[0024] Heterotrophic denitrifying bacteria loaded on the surface of PVDC discs utilize organic carbon sources to complete short-cut denitrification (NO3⁻→NO2⁻). Within the cavity, autotrophic denitrification is driven by a sulfur-pyrite-magnetite composite packing material, replenishing nitrite and releasing Fe²⁺. The partitioned design avoids carbon source competition, ensuring a stable nitrite supply. Simultaneously, Fe²⁺ promotes the enrichment of anaerobic ammonia-oxidizing bacteria, enhancing their low-temperature activity and achieving efficient conversion of NH4⁺ and NO2⁻ into N2. This results in a 35%~40% improvement in nitrogen removal efficiency at low temperatures (<15℃) compared to traditional processes.

[0025] 3. Simultaneous chemical phosphorus removal

[0026] The Fe²⁺ / Fe³⁺ released from the reaction of the sulfur-pyrite-magnetite composite packing combines with phosphate to form FePO₄ precipitate; at the same time, the shear force generated by the rotation of the disc prevents the packing from caking, maintains porosity, and avoids clogging. It can achieve a total phosphorus removal rate of ≥95%, maintain porosity of over 90%, reduce energy consumption by 50%~60%, and reduce sludge production by 30%~40%.

[0027] 4. High-performance composite fillers

[0028] In composite packings, elemental sulfur can more easily crosslink with pyrite, magnetite and other components to form a stable network through thiol-containing silane coupling agents, reducing sulfur oxidation or loss, while achieving slow and stable release of sulfur and iron ions. Moreover, the high specific surface area and ordered pores of mesoporous silica can provide a loading platform, regulate the mass transfer efficiency of composite packings, and promote the chemical reactions of nitrogen and phosphorus removal. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the biological filter rotating disc system.

[0030] Figure 2 This is a schematic diagram of the operation process of the nitrogen and phosphorus removal method.

[0031] The meanings of the reference numerals in the attached diagram are as follows: 1. PVDC disk; 2. Turntable assembly; 3. Stainless steel shaft; 4. Removable sealing cover; 5. Cavity. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the application will be further described in detail below with reference to embodiments. However, this should not be construed as limiting the scope of this application to the following examples. All other embodiments obtained by those skilled in the art without creative effort without departing from the above-described methodological spirit of this application are within the scope of protection of this application.

[0033] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be interpreted as indicating or implying relative importance.

[0035] Furthermore, the singular forms “for,” “or,” “a,” “any,” and “the” used in this application and the appended claims are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] Firstly, such as Figure 1 As shown, this application provides a biological filter disc system based on replaceable composite packing material, including a disc group 2 composed of PVDC discs 1 connected in series, a stainless steel rotating shaft 3 for connecting the PVDC discs 1 in series, a detachable sealing cover plate 4 provided at the edge of the PVDC discs 1, and a cavity 5 provided inside the PVDC discs 1; the cavity 5 is filled with sulfur-pyrite-magnetite composite packing material and anaerobic ammonia oxidizing bacteria; the surface of the PVDC discs 1 is loaded with heterotrophic denitrifying bacteria.

[0037] In one possible implementation, the sulfur-pyrite-magnetite composite filler comprises elemental sulfur particles, pyrite particles, magnetite particles, bentonite, mesoporous silica, and a silane coupling agent.

[0038] In one possible implementation, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica and silane coupling agent is (30~60):(10~20):(10~20):(10~20):(5~15):(1~5).

[0039] In one possible implementation, the silane coupling agent comprises any one of γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and 3-thiocyanopropyltriethoxysilane.

[0040] In one possible implementation, the filling rate of the sulfur-pyrite-magnetite composite filler is 30-40% by volume; and the filling density of the sulfur-pyrite-magnetite composite filler is 1.8-2.2 g / cm³.

[0041] In one possible implementation, the turntable assembly 2 includes 30 PVDC disks 1; the thickness of the PVDC disks 1 is 20±2mm; the average width of the cavity 5 is 10~12mm; and the size of the removable sealing cover 4 is 50mm×50mm.

[0042] Secondly, this application provides a method for nitrogen and phosphorus removal achieved through the aforementioned biological filter rotating disc system based on replaceable composite packing material, comprising the following steps:

[0043] Pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica are mixed, and silane coupling agent is added dropwise to the mixture while stirring.

[0044] After the silane coupling agent is added, continue stirring the mixture for 5-10 minutes, discharge the material, exhaust the air, seal and store for 20-24 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0045] Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler;

[0046] The cavity 5 is filled with sulfur-pyrite-magnetite composite packing material, and the filled PVDC discs 1 are connected in series to form a disc group 2 through a stainless steel rotating shaft 3, thus obtaining a biological filter disc system based on replaceable composite packing material.

[0047] The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0048] When the rotary disc system is started, the wastewater undergoes heterotrophic denitrification on the outer layer of the disc and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the disc, simultaneously removing nitrogen and phosphorus to obtain primary treated water.

[0049] The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0050] The secondary treated water is tested and discharged only after it meets the standards. At the same time, the sulfur-pyrite-magnetite composite packing in cavity 5 is replaced regularly.

[0051] In one possible implementation, the hydraulic load of the biological filter rotary disc system is 0.5~1.0 m³ / (m²·d); after the rotary disc system is started, the rotation speed of the PVDC disc 1 in the rotary disc group 2 is 2~4 r / min.

[0052] In one possible implementation, the secondary treated water meets the following standards: NH4⁺-N ≤ 1.2 mg / L; NO3⁻-N ≤ 1.0 mg / L; total phosphorus content TP ≤ 0.15 mg / L.

[0053] In one possible implementation, during the denitrification and phosphorus removal process, the denitrification load is ≥0.4 kg N / (m³·d), and the total phosphorus removal rate is ≥95%.

[0054] The following will describe in detail, with reference to different examples, a rotating biological filter system based on replaceable composite packing provided in this application.

[0055] Example 1:

[0056] like Figure 2 As shown, a method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing includes the following steps:

[0057] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0058] 2. After the silane coupling agent is added, continue stirring the mixture for 5 minutes, discharge the material, exhaust the air, seal and store for 20 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0059] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is 54:10:10:10:15:1.

[0060] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0061] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0062] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0063] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0064] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0065] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0066] Example 2:

[0067] like Figure 2 As shown, a method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing includes the following steps:

[0068] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0069] 2. After the silane coupling agent is added, continue stirring the mixture for 6 minutes, discharge the material, exhaust the air, seal and store for 22 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0070] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is 50:10:15:10:10:5.

[0071] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0072] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0073] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0074] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0075] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0076] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0077] Example 3:

[0078] like Figure 2 As shown, a method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing includes the following steps:

[0079] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0080] 2. After the silane coupling agent is added, continue stirring the mixture for 10 minutes, discharge the material, exhaust the air, seal and store for 24 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0081] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is 60:10:10:10:8:2.

[0082] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0083] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0084] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0085] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0086] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0087] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0088] Example 4:

[0089] like Figure 2 As shown, a method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing includes the following steps:

[0090] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0091] 2. After the silane coupling agent is added, continue stirring the mixture for 7 minutes, discharge the material, exhaust the air, seal and store for 23 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0092] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is 46:15:15:10:12:2.

[0093] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0094] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0095] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0096] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0097] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0098] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0099] Example 5:

[0100] like Figure 2 As shown, a method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing includes the following steps:

[0101] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0102] 2. After the silane coupling agent is added, continue stirring the mixture for 8 minutes, discharge the material, exhaust the air, seal and store for 22 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0103] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is 36:15:20:10:15:4.

[0104] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0105] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0106] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0107] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0108] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0109] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0110] Example 6:

[0111] like Figure 2 As shown, a method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing includes the following steps:

[0112] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0113] 2. After the silane coupling agent is added, continue stirring the mixture for 9 minutes, discharge the material, exhaust the air, seal and store for 21 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0114] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica and silane coupling agent is 42:15:15:15:10:3.

[0115] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0116] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0117] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0118] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0119] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0120] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0121] Comparative Example 1:

[0122] A method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing material includes the following steps:

[0123] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0124] 2. After the silane coupling agent is added, continue stirring the mixture for 5 minutes, discharge the material, exhaust the air, seal and store for 20 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0125] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is 54:10:10:10:15:1.

[0126] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0127] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0128] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0129] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0130] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0131] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0132] Comparative Example 2:

[0133] A method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing material includes the following steps:

[0134] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0135] 2. After the silane coupling agent is added, continue stirring the mixture for 10 minutes, discharge the material, exhaust the air, seal and store for 24 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0136] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is 60:10:10:10:8:2.

[0137] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0138] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0139] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0140] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0141] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0142] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0143] Comparative Example 3:

[0144] A method for nitrogen and phosphorus removal using a rotating disc biofilter system based on replaceable composite packing material includes the following steps:

[0145] 1. Mix pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica, and add silane coupling agent dropwise to the mixture while stirring.

[0146] 2. After the silane coupling agent is added, continue stirring the mixture for 9 minutes, discharge the material, exhaust the air, seal and store for 21 hours to obtain the sulfur-pyrite-magnetite composite filler.

[0147] In steps 1-2, the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica and silane coupling agent is 42:15:15:15:10:3.

[0148] 3. Open the removable sealing cover 4 set on the edge of the PVDC disk 1, and fill the cavity 5 set inside the PVDC disk 1 with sulfur-pyrite-magnetite composite filler.

[0149] 4. The cavity 5 is filled with sulfur-pyrite-magnetite composite filler repeatedly, and the filled PVDC disks 1 are connected in series to form a turntable group 2 through a stainless steel rotating shaft 3.

[0150] 5. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system;

[0151] 6. Start the rotary table system. The wastewater undergoes heterotrophic denitrification on the outer layer of the rotary table and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the rotary table. Nitrogen and phosphorus removal are carried out simultaneously to obtain primary treated water.

[0152] 7. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water;

[0153] 8. Test the secondary treated water and discharge it after it meets the standards. At the same time, replace the sulfur-pyrite-magnetite composite packing in cavity 5 regularly.

[0154] The NH4⁺-N content of wastewater before and after treatment was determined according to HJ 535-2009; the NO3⁻-N content of wastewater before and after treatment was determined according to HJ / T 346-2007; the total phosphorus (TP) content of wastewater before and after treatment was determined according to GB 11893-89; and the COD content of wastewater before and after treatment was determined according to HJ / T 399-2007.

[0155] The actual effect of the nitrogen and phosphorus removal method is demonstrated by detecting the NH4⁺-N content, NO3⁻-N content, total phosphorus (TP) content, and COD content of the wastewater before and after treatment by the biological filter rotary disc system, and calculating the removal rate of the corresponding indicators, as shown in Tables 1 to 4 below.

[0156] Table 1. NH4⁺-N content and NH4⁺-N removal rate of wastewater before and after treatment by the biological filter rotating disc system.

[0157]

[0158] Table 2. NO3-N content and NO3-N removal rate of wastewater before and after treatment by the biological filter rotating disc system.

[0159]

[0160] Table 3. TP content and TP removal rate of wastewater before and after treatment by the biological filter rotating disc system.

[0161]

[0162] Table 4. COD content and COD removal rate of wastewater before and after treatment by the biological filter rotating disc system.

[0163]

[0164] As shown in Tables 1 to 4, the removal rates of NH4⁺-N in Examples 1 to 6 are generally above 95.2%, the removal rates of NO3⁻-N are generally above 96.7%, the removal rates of TP are generally above 97.0%, and the removal rates of COD are generally above 60.0%; and all of the above indicators are much higher than those of Comparative Examples 1 to 3.

[0165] This is because Examples 1-6 achieve the synergistic effect of multiple aspects, including the encapsulation of PVDC discs and composite packing, zoned reaction design, and Fe²⁺ synergistic enhancement mechanism, enabling the biological filter disc system to support online packing replacement, as well as high-efficiency nitrogen and phosphorus removal in deep treatment of industrial wastewater and low-temperature environments.

[0166] In contrast, the composite packing materials in Comparative Example 1 and Comparative Example 2 lacked elemental sulfur particles and magnetite in one case and pyrite and magnetite in the other; both were unable to achieve stable release of sulfur and iron ions, thus significantly affecting the autotrophic denitrification process and resulting in a significant reduction in the effectiveness of subsequent nitrogen and phosphorus removal reactions.

[0167] In Comparative Example 3, no zoned reaction design was implemented. Instead, the sulfur-pyrite-magnetite composite packing, anaerobic ammonia oxidizing bacteria, and heterotrophic denitrifying bacteria were mixed together in cavity 5. This did not avoid competition for carbon sources and made it difficult to stabilize the supply of nitrite. As a result, the subsequent nitrogen removal effect was reduced more severely. Only the phosphorus removal effect was slightly better due to the stable release of iron ions.

[0168] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0169] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, such as producing raw materials for the biochemical industry based on this method or a modified method. All such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A rotating disc biological filter system based on replaceable composite packing material, characterized in that: The device includes a turntable assembly (2) consisting of PVDC discs (1) connected in series, a stainless steel rotating shaft (3) for connecting the PVDC discs (1) in series, a removable sealing cover (4) provided at the edge of the PVDC discs (1), and a cavity (5) provided inside the PVDC discs (1); the cavity (5) is filled with sulfur-pyrite-magnetite composite packing material and anaerobic ammonia-oxidizing bacteria; the surface of the PVDC discs (1) is loaded with heterotrophic denitrifying bacteria; the sulfur-pyrite-magnetite composite packing material includes elemental sulfur. The mixture comprises pyrite particles, magnetite particles, bentonite, mesoporous silica, and a silane coupling agent; wherein the mass ratio of the pyrite particles, elemental sulfur particles, magnetite particles, bentonite, mesoporous silica, and silane coupling agent is (30~60):(10~20):(10~20):(10~20):(5~15):(1~5); and wherein the silane coupling agent comprises any one of γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and 3-thiocyanopropyltriethoxysilane.

2. The biological filter rotating disc system based on replaceable composite packing material according to claim 1, characterized in that: The filling rate of the sulfur-pyrite-magnetite composite filler is 30-40% by volume; the filling density of the sulfur-pyrite-magnetite composite filler is 1.8-2.2 g / cm³.

3. The biological filter rotating disc system based on replaceable composite packing material according to claim 1, characterized in that: The turntable assembly (2) includes 30 PVDC disks (1); the thickness of the PVDC disks (1) is 20±2mm; the average width of the cavity (5) is 10~12mm; the size of the detachable sealing cover (4) is 50mm×50mm.

4. A method for nitrogen and phosphorus removal, implemented using a rotating biological filter system based on replaceable composite packing material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Pyrite particles, elemental sulfur particles, magnetite particles, bentonite, and mesoporous silica are mixed, and silane coupling agent is added dropwise to the mixture while stirring. After the silane coupling agent is added, continue stirring the mixture for 5-10 minutes, discharge the material, exhaust the air, seal and store for 20-24 hours to obtain the sulfur-pyrite-magnetite composite filler. Open the removable sealing cover (4) set on the edge of the PVDC disk (1) and fill the cavity (5) set inside the PVDC disk (1) with sulfur-pyrite-magnetite composite filler; The cavity (5) is filled with sulfur-pyrite-magnetite composite packing repeatedly, and the filled PVDC discs (1) are connected in series to form a disc group (2) through a stainless steel rotating shaft (3), and finally a biological filter disc system based on replaceable composite packing is obtained. The wastewater to be treated is fed into an anoxic tank equipped with the aforementioned biological filter rotating disc system; When the rotary disc system is started, the wastewater undergoes heterotrophic denitrification on the outer layer of the disc and sulfur autotrophic denitrification and phosphorus removal on the inner layer of the disc, simultaneously removing nitrogen and phosphorus to obtain primary treated water. The primary treated water is fed into a sedimentation tank for sedimentation treatment to obtain secondary treated water; The secondary treated water is tested and discharged after meeting the standards. At the same time, the sulfur-pyrite-magnetite composite packing in the cavity (5) is replaced regularly.

5. The nitrogen and phosphorus removal method according to claim 4, characterized in that: The hydraulic load of the biological filter rotary disc system is 0.5~1.0 m³ / (m²·d); after the rotary disc system is started, the rotation speed of the PVDC disc (1) in the rotary disc group (2) is 2~4 r / min.

6. The nitrogen and phosphorus removal method according to claim 4, characterized in that: The standards for the secondary treated water are: NH4⁺-N≤1.2 mg / L; NO3⁻-N≤1.0 mg / L; total phosphorus content TP≤0.15 mg / L.

7. The nitrogen and phosphorus removal method according to claim 4, characterized in that: During the denitrification and phosphorus removal process, the denitrification load is ≥0.4 kg N / (m³·d), and the total phosphorus removal rate is ≥95%.

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