Sulfur autotrophic denitrification nitrogen removal filler and preparation method thereof

Abstract

The application provides a sulfur autotrophic denitrification filler and a preparation method thereof, and belongs to the technical field of water treatment. The sulfur autotrophic denitrification filler comprises the following components in parts by weight: sulfur powder 40-50 parts, titanium white waste residue 20-30 parts, MOR molecular sieve 5-15 parts, sodium bicarbonate 1-5 parts, polyvinyl alcohol 1-5 parts, sodium alginate 5-10 parts and crosslinking agent 1-3 parts. The sulfur powder, the titanium white waste residue and the MOR molecular sieve are uniformly dispersed and coated in the porous gel network structure, so that the imbalance of the acid-base degree in the autotrophic denitrification process is avoided, the removal rate of nitrate nitrogen and ammonia nitrogen is effectively improved, phosphorus is effectively removed, and the scouring resistance and the strength of the filler are ensured.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a sulfur autotrophic denitrification packing and its preparation method. Background Technology

[0002] Wastewater treatment denitrification technologies primarily rely on traditional biological denitrification, with weaknesses remaining in advanced treatment stages. In recent years, some demonstration projects have attempted combined processes such as MBR+RO and biofilters, but these have encountered problems such as high energy consumption and operational complexity. The development of novel biological denitrification technologies focuses on short-cut nitrification-denitrification, anaerobic ammonium oxidation, and simultaneous nitrification-denitrification. Simultaneously, research and development of autotrophic denitrification technology is also emphasized. Unlike heterotrophic denitrification, autotrophic denitrifying bacteria can utilize inorganic carbon (such as CO3). 2- HCO3 - Synthetic cells, inorganic substances (such as S) 2- S2O3 2- Fe, Fe 2+ H2, NH4 + (e.g., NH3-N) acts as an electron donor for nitrate reduction, thus completing the denitrification process. The entire autotrophic denitrification process requires no external organic carbon source. Novel biological nitrogen removal technologies control the nitrification reaction at the nitrite stage, achieving short-cut nitrification and denitrification; or they use NH3-N as an electron donor and NO2-N as an electron acceptor to achieve anaerobic ammonia oxidation, thereby shortening the N conversion pathway and reducing the need for DO and carbon sources during nitrogen removal.

[0003] Patent CN116854246A discloses a method for preparing sulfur-autotrophic denitrification packing and its application. This method uses natural components from pyrite tailings slag to replace the traditional sulfur source, providing iron and sulfur as dual electron donors for autotrophic denitrifying bacteria, thus achieving nitrogen and phosphorus removal. The method provides the microorganisms with an attachment surface solely through pyrite tailings and sulfur, and also addresses the issue of NH4+. + The adsorption of sulfur has limitations. Patent CN117185467A discloses a sulfur autotrophic denitrification and phosphorus removal packing material prepared at room temperature. It achieves efficient and stable nitrogen and phosphorus removal by forming a three-dimensional network structure of S-Fe-Ca crosslinking. This method requires the dissolution of iron in iron-rich sludge to provide electron donors. Although iron-rich sludge has a high specific surface area, its pore structure is disordered and irregular, resulting in problems such as reduced adhesion rate and easy clogging. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a sulfur autotrophic denitrification packing material and its preparation method. The purpose of this invention is to improve the pore regularity and uniformity of the packing material by uniformly dispersing sulfur powder, titanium dioxide waste, and MOR molecular sieves within a porous gel network structure. This increases the attachment sites for sulfur autotrophic denitrifying bacteria, promotes nitrogen and phosphorus removal, and enhances the adsorption capacity of NH4.+ This will further reduce the concentration of ammonia nitrogen.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: On the one hand, the present invention provides a sulfur autotrophic denitrification packing material, comprising the following components in parts by weight: 40-50 parts sulfur powder, 20-30 parts titanium dioxide waste residue, 5-15 parts MOR molecular sieve, 1-5 parts sodium bicarbonate, 1-5 parts polyvinyl alcohol, 5-10 parts sodium alginate, and 1-3 parts crosslinking agent.

[0006] This invention constructs a sulfur-iron dual-electron donor system using sulfur powder and titanium dioxide waste. During sulfur autotrophic denitrification, the sulfur powder converts nitrate into nitrogen gas. The introduced titanium dioxide waste stably releases iron ions, enabling iron autotrophic denitrification without microbial activation, and also converts phosphate into precipitate for removal. Furthermore, the MOR molecular sieve enhances mass transfer efficiency and promotes denitrification. The MOR molecular sieve also adsorbs NH4+. + This process, while achieving simultaneous nitrogen and phosphorus removal, further reduces ammonia nitrogen content. Sulfate autotrophic denitrification generates a significant amount of H₂. + Sodium bicarbonate can significantly impact microbial growth. It not only provides an inorganic carbon source for microorganisms but also prevents acid-base imbalances caused by sulfur autotrophic denitrification and iron autotrophic denitrification. This invention utilizes polyvinyl alcohol and sodium alginate to construct a porous gel network, providing a high specific surface area. This network, in synergy with MOR molecular sieves that have a regular pore structure, provides microorganisms with more attachment surface and more uniformly distributed pores.

[0007] Preferably, the mass ratio of titanium dioxide waste residue to sulfur powder is 1:(1-2.5); the titanium dioxide waste residue has a particle size of 50-100μm and a free acid concentration of 0.1-3%. The FeSO4 content in the titanium dioxide waste residue is ≥60%. The titanium dioxide waste residue has a certain strength, which can provide good mechanical property support for the filler.

[0008] Preferably, the MOR molecular sieve has a particle size of 50-100 μm and a specific surface area of ​​500-1000 m². 2 / g.

[0009] Preferably, the mass ratio of polyvinyl alcohol to sodium alginate is (0.1-1):1. This invention improves the water resistance, swelling resistance, and mechanical strength of the filler by using polyvinyl alcohol and sodium alginate.

[0010] Preferably, the total amount of sulfur powder, titanium dioxide waste residue, MOR molecular sieve, and sodium bicarbonate in the components is in a ratio of (7-9):1 to the total amount of polyvinyl alcohol and sodium alginate. This invention, by controlling the ratio of the total amount of sulfur powder, titanium dioxide waste residue, MOR molecular sieve, and sodium bicarbonate to the total amount of polyvinyl alcohol and sodium alginate, ensures that the three-dimensional cross-linked network formed by polyvinyl alcohol and sodium alginate encapsulates the powder, preventing powder loss.

[0011] Preferably, the crosslinking agent is one or more of calcium chloride and boric acid. This invention promotes gel curing and improves the filler's erosion resistance and strength by crosslinking the crosslinking agent with the carboxyl and hydroxyl groups in polyvinyl alcohol and sodium alginate.

[0012] On the other hand, the present invention provides a method for preparing the above-mentioned sulfur autotrophic denitrification packing, comprising the following steps: S1: Add polyvinyl alcohol to deionized water, heat and stir until dissolved, cool, add sodium alginate and stir to mix to obtain adhesive solution; S2: Add sulfur powder, titanium dioxide waste residue, MOR molecular sieve, and sodium bicarbonate to the binder solution, mix well, and obtain a gel suspension. S3: The gel suspension is dropped into a crosslinking agent solution dissolved in deionized water, solidified, filtered, washed, and dried at room temperature to obtain the sulfur autotrophic denitrification packing.

[0013] Preferably, in step S1, polyvinyl alcohol is added to deionized water, heated to 80-90°C, stirred until dissolved, cooled to 50-60°C, and sodium alginate is added and stirred to mix.

[0014] Preferably, in step S2, the mixing speed is 500-700 rpm and the mixing time is 10-30 min.

[0015] Preferably, the curing temperature of S3 is 0-5℃ and the curing time is 12-24h.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention introduces titanium dioxide waste residue, which can stably release iron ions without microbial activation, forming a dual-electron donor system with sulfur to improve denitrification efficiency and simultaneously remove phosphorus. Sodium bicarbonate provides an inorganic carbon source for microorganisms, balancing pH fluctuations during autotrophic denitrification and effectively preventing significant pH drops that could affect microbial growth and denitrification. Furthermore, this invention utilizes a porous gel network constructed with polyvinyl alcohol and sodium alginate, synergistically with MOR molecular sieves and titanium dioxide waste residue, to enhance mass transfer efficiency and improve the mechanical properties and water resistance of the packing material. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0018] General Implementation Examples A sulfur-autotrophic denitrification packing material comprises the following components in parts by weight: 40-50 parts sulfur powder, 20-30 parts titanium dioxide waste residue, 5-15 parts MOR molecular sieve, 1-5 parts sodium bicarbonate, 1-5 parts polyvinyl alcohol, 5-10 parts sodium alginate, and 1-3 parts crosslinking agent.

[0019] In some preferred embodiments of the present invention, the mass ratio of titanium dioxide waste residue to sulfur powder is 1:(1-2.5); the titanium dioxide waste residue has a particle size of 50-100μm and a free acid concentration of 0.1-3%.

[0020] In some preferred embodiments of the present invention, the FeSO4 content in the titanium dioxide waste residue is ≥60%.

[0021] In some preferred embodiments of the present invention, the MOR molecular sieve has a particle size of 50-100 μm and a specific surface area of ​​500-1000 m². 2 / g.

[0022] In some preferred embodiments of the present invention, the mass ratio of polyvinyl alcohol to sodium alginate is (0.1-1):1.

[0023] In some preferred embodiments of the present invention, the total amount of sulfur powder, titanium dioxide waste residue, MOR molecular sieve, and sodium bicarbonate in the components is in the ratio of the total amount of polyvinyl alcohol and sodium alginate to (7-9):1.

[0024] In some preferred embodiments of the present invention, the crosslinking agent is one or more of calcium chloride and boric acid.

[0025] A method for preparing the above-mentioned sulfur autotrophic denitrification packing material includes the following steps: S1: Add polyvinyl alcohol to deionized water, heat and stir until dissolved, cool, add sodium alginate and stir to mix to obtain adhesive solution; S2: Add sulfur powder, titanium dioxide waste residue, MOR molecular sieve, and sodium bicarbonate to the binder solution, mix well, and obtain a gel suspension. S3: The gel suspension is dropped into a crosslinking agent solution dissolved in deionized water, solidified, filtered, washed, and dried at room temperature to obtain the sulfur autotrophic denitrification packing.

[0026] In some preferred embodiments of the present invention, in step S1, polyvinyl alcohol is added to deionized water, heated to 80-90°C, stirred until dissolved, cooled to 50-60°C, and sodium alginate is added and stirred to mix.

[0027] In some preferred embodiments of the present invention, the mixing speed of step S2 is 500-700 rpm and the mixing time is 10-30 min.

[0028] In some preferred embodiments of the present invention, the curing temperature of S3 is 0-5℃ and the curing time is 12-24h.

[0029] The sulfur autotrophic denitrification packing of the present invention has a size of 8-10 mm and a compressive strength of over 1.2 MPa. Example 1

[0030] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 5 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 5 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 50 parts by weight of sulfur powder, 20 parts by weight of titanium dioxide waste residue, 10 parts by weight of MOR molecular sieve, and 3 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 2

[0031] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 4 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 8 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 50 parts by weight of sulfur powder, 30 parts by weight of titanium dioxide waste residue, 15 parts by weight of MOR molecular sieve, and 5 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm, and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm, and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 3 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 3

[0032] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 4 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 8 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 50 parts by weight of sulfur powder, 25 parts by weight of titanium dioxide waste residue, 13 parts by weight of MOR molecular sieve, and 4 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm, and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm, and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 3 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 4

[0033] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 5 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 5 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 45 parts by weight of sulfur powder, 30 parts by weight of titanium dioxide waste residue, 10 parts by weight of MOR molecular sieve, and 5 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 5

[0034] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 3 parts by weight of polyvinyl alcohol to deionized water, heat to 80°C, stir until dissolved, cool to 50°C, add 7 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution; S2: Add 45 parts by weight of sulfur powder, 20 parts by weight of titanium dioxide waste residue, 15 parts by weight of MOR molecular sieve, and 5 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 700 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 3 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 6

[0035] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 4 parts by weight of polyvinyl alcohol to deionized water, heat to 85°C, stir until dissolved, cool to 55°C, add 6 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 45 parts by weight of sulfur powder, 25 parts by weight of titanium dioxide waste residue, 10 parts by weight of MOR molecular sieve, and 3 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 500 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 7

[0036] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 5 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 5 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 40 parts by weight of sulfur powder, 30 parts by weight of titanium dioxide waste residue, 10 parts by weight of MOR molecular sieve, and 3 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 8

[0037] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 4 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 5 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 40 parts by weight of sulfur powder, 20 parts by weight of titanium dioxide waste residue, 5 parts by weight of MOR molecular sieve, and 1 part by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 700 rpm for 10 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm, and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm, and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 1 part by weight of boric acid, drop the gel suspension into a boric acid solution dissolved in deionized water, solidify at 0℃ for 12 h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 9

[0038] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 4 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 6 parts by weight of sodium alginate, stir and mix to obtain adhesive solution; S2: Add 40 parts by weight of sulfur powder, 25 parts by weight of titanium dioxide waste residue, 5 parts by weight of MOR molecular sieve, and 5 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 650 rpm for 20 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm, and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm, and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 3℃ for 12h, filter and wash 3 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing. Example 10

[0039] A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 5 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 6 parts by weight of sodium alginate, stir and mix to obtain adhesive solution; S2: Add 40 parts by weight of sulfur powder, 25 parts by weight of titanium dioxide waste residue, 15 parts by weight of MOR molecular sieve, and 5 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 3 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 5°C for 24 hours, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing.

[0040] Comparative Example 1 A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 5 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 5 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 50 parts by weight of sulfur powder, 10 parts by weight of MOR molecular sieve, and 3 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein the particle size of the MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing.

[0041] Comparative Example 2 A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 4 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 8 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 50 parts by weight of sulfur powder, 30 parts by weight of titanium dioxide waste residue, and 5 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein the particle size of the titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; S3: Weigh 3 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing.

[0042] Comparative Example 3 A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 5 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 5 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 45 parts by weight of sulfur powder, 30 parts by weight of titanium dioxide waste residue, and 10 parts by weight of MOR molecular sieve to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing.

[0043] Comparative Example 4 A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 5 parts by weight of polyvinyl alcohol to deionized water, heat to 90°C, stir until dissolved, cool to 60°C, add 5 parts by weight of sodium alginate, stir and mix to obtain an adhesive solution. S2: Add 45 parts by weight of sulfur powder, 45 parts by weight of titanium dioxide waste residue, 10 parts by weight of MOR molecular sieve, and 5 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm, and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm, and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing.

[0044] Comparative Example 5 A method for preparing a sulfur-autotrophic denitrification packing material includes the following steps: S1: Add 10 parts by weight of sodium alginate to deionized water, heat to 60°C, and stir until dissolved to obtain an adhesive solution; S2: Add 45 parts by weight of sulfur powder, 25 parts by weight of titanium dioxide waste residue, 10 parts by weight of MOR molecular sieve, and 3 parts by weight of sodium bicarbonate to the binder solution, stir and mix at a stirring speed of 600 rpm for 30 min to obtain a gel suspension; wherein, the particle size of titanium dioxide waste residue is 50-100 μm, and the free acid concentration is 0.1-3%; the particle size of MOR molecular sieve is 50-100 μm, and the specific surface area is 500-1000 m². 2 / g; S3: Weigh 2 parts by weight of calcium chloride, drop the gel suspension into a calcium chloride solution dissolved in deionized water, solidify at 0℃ for 12h, filter and wash 5 times, and dry at room temperature to obtain sulfur autotrophic denitrification denitrification packing.

[0045] The present invention tested the nitrate nitrogen removal rate, ammonia nitrogen removal rate, and total phosphorus removal rate of the sulfur autotrophic denitrification packing materials obtained in Examples 1-10 and Comparative Examples 1-5. The test results are shown in Table 1.

[0046] Table 1 According to the test results, the sulfur self-trophic denitrification denitrification packing of the present invention can effectively improve the removal rate of nitrate nitrogen and ammonia nitrogen, and effectively remove phosphorus at the same time; the nitrate nitrogen removal rate can reach 94.2-98.3%, the ammonia nitrogen removal rate can reach 44.8-53.0%, and the total phosphorus removal rate can reach 73.7-80.7%.

[0047] Compared to Example 1, Comparative Example 1 did not add titanium dioxide waste residue, and the iron-sulfur dual-electron donor system was not formed, resulting in a significant decrease in phosphorus removal efficiency. Compared to Example 2, Comparative Example 2 did not use MOR molecular sieves, and the nitrogen and phosphorus removal efficiency was significantly reduced. MOR molecular sieves, with their high specific surface area and pore structure, promote mass transfer efficiency, reduce pore blockage rate, and provide a large number of adsorption sites, enabling them to adsorb NH4+. + The combined structure of the outer gel interpenetrating network of the packing material has a uniform pore distribution, which can promote microbial biofilm formation and effectively remove nitrate nitrogen while further improving the removal rate of ammonia nitrogen. In Comparative Example 3, compared to Example 4 which did not add sodium bicarbonate, the acid produced during autotrophic denitrification was difficult to neutralize, leading to a decrease in water pH and creating an environment unsuitable for the growth of denitrifying bacteria. Furthermore, the reduction in the inorganic carbon source also inhibited bacterial growth and metabolism, resulting in a significant decrease in nitrate nitrogen removal rate, ammonia nitrogen removal rate, and total phosphorus removal rate. Comparative Example 4, compared to Example 4, used excessive titanium dioxide waste, leading to a decrease in the removal rates of nitrate nitrogen and ammonia nitrogen. Excessive iron ions affected pH changes during autotrophic denitrification, exceeding the adjustment range of sodium bicarbonate. Comparative Example 5, compared to Example 6 which only used sodium alginate, did not utilize polyvinyl alcohol and sodium alginate to form an interpenetrating cross-linked network structure, resulting in a decrease in the compressive strength and erosion resistance of the packing material, weakening its effectiveness.

Claims

1. A sulfur-autotrophic denitrification packing material, characterized in that, It includes the following components by weight: 40-50 parts sulfur powder, 20-30 parts titanium dioxide waste residue, 5-15 parts MOR molecular sieve, 1-5 parts sodium bicarbonate, 1-5 parts polyvinyl alcohol, 5-10 parts sodium alginate, and 1-3 parts crosslinking agent.

2. The sulfur-autotrophic denitrification packing material according to claim 1, characterized in that, The mass ratio of the titanium dioxide waste residue to sulfur powder is 1:(1-2.5); The titanium dioxide waste residue has a particle size of 50-100μm and a free acid concentration of 0.1-3%.

3. The sulfur-autotrophic denitrification packing material according to claim 1 or 2, characterized in that, The MOR molecular sieve has a particle size of 50-100 μm and a specific surface area of ​​500-1000 m². 2 / g.

4. The sulfur autotrophic denitrification packing material according to claim 1 or 2, characterized in that, The mass ratio of polyvinyl alcohol to sodium alginate is (0.1-1):

1.

5. A sulfur-autotrophic denitrification packing material according to claim 1 or 2, characterized in that, In the components, the total amount of sulfur powder, titanium dioxide waste residue, MOR molecular sieve, and sodium bicarbonate is in the ratio of the total amount of polyvinyl alcohol and sodium alginate to (7-9):

1.

6. The sulfur autotrophic denitrification packing material according to claim 1 or 2, characterized in that, The crosslinking agent is one or more of calcium chloride and boric acid.

7. A method for preparing a sulfur autotrophic denitrification packing material according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Add polyvinyl alcohol to deionized water, heat and stir until dissolved, cool, add sodium alginate and stir to mix to obtain adhesive solution; S2: Add sulfur powder, titanium dioxide waste residue, MOR molecular sieve, and sodium bicarbonate to the binder solution, mix well, and obtain a gel suspension. S3: The gel suspension is dropped into a crosslinking agent solution dissolved in deionized water, solidified, filtered, washed, and dried at room temperature to obtain the sulfur autotrophic denitrification packing.

8. The method for preparing a sulfur-autotrophic denitrification packing material according to claim 7, characterized in that, In step S1, polyvinyl alcohol is added to deionized water, heated to 80-90°C, stirred until dissolved, cooled to 50-60°C, and sodium alginate is added and stirred to mix.

9. The method for preparing a sulfur-autotrophic denitrification packing material according to claim 8, characterized in that, The mixing speed of S2 is 500-700 rpm, and the mixing time is 10-30 min.

10. The method for preparing a sulfur-autotrophic denitrification packing material according to claim 7, characterized in that, The curing temperature of S3 is 0-5℃, and the curing time is 12-24h.

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