A three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification and working method

Abstract

This invention discloses a three-layer denitrification tower device and its working method based on sulfur autotrophic-heterotrophic denitrification, belonging to the field of water treatment technology. It includes a raw water tank, a sedimentation tank, and a three-layer denitrification tower. The raw water tank is connected to the inlet at the lower end of the three-layer denitrification tower, and the outlet pipe at the upper end of the three-layer denitrification tower is connected to a degassing tank on one side of the sedimentation tank. The bottom of the degassing tank is connected to the lower end of the sedimentation tank. A sludge discharge port is provided at the lower end of the sedimentation tank, and an outlet is provided at the upper end of the sedimentation tank. The three-layer denitrification tower is arranged sequentially from bottom to top as a carbon fiber denitrification filter layer, a sulfur autotrophic packing layer, and a stirrer. The three-layer denitrification tower of this invention has high denitrification efficiency and strong processing capacity. It combines autotrophic and heterotrophic methods, improving the reactor's denitrification capacity. The carbon fiber filter media and suspended MBBR packing have a large surface area and numerous micropores, greatly increasing the attachment space for denitrifying microorganisms. The suspended MBBR packing has high hydrophilicity and good binding ability with denitrifying microorganisms, resulting in high sulfur autotrophic denitrification efficiency.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification and its working method. Background Technology

[0002] Wastewater discharge from the electroplating industry is one of the most important environmental problems in the world today. The surface of the electroplated parts is covered with a lot of oil stains, which need to be washed with water multiple times to remove the oil stains. During the washing process, a variety of inorganic and organic substances need to be added, resulting in high salt content, total nitrogen and ammonia nitrogen content in the wastewater. The wastewater needs to be denitrified, which is very difficult to treat.

[0003] Denitrification technology can be divided into heterotrophic denitrification and autotrophic denitrification based on whether it requires an organic carbon source. Autotrophic denitrification refers to the process in which denitrifying bacteria use inorganic carbon sources in wastewater as electron donors to reduce nitrogen in nitrates or nitrites to nitrogen gas. Heterotrophic denitrification, on the other hand, relies on external organic matter as an electron donor and usually requires sufficient organic carbon sources in the wastewater for the reaction to proceed. Heterotrophic denitrification produces fewer byproducts and has high nitrogen removal efficiency. However, when the carbon and nitrogen content of the wastewater is low, heterotrophic denitrification requires the addition of external organic carbon sources to support the activity of denitrifying bacteria, which greatly increases operating costs and may lead to the accumulation of nitrite nitrogen and fluctuations in chemical oxygen demand (COD) in the effluent.

[0004] Patent CN116282529A discloses an integrated domestic wastewater treatment device with post-sulfur autotrophic denitrification, consisting of a hydrolysis acidification zone, a contact oxidation zone, a high-efficiency sedimentation zone, and a post-sulfur autotrophic denitrification filter. It requires no external carbon source, is highly efficient, energy-saving, environmentally friendly, and provides stable denitrification. However, this solution is only suitable for wastewater treatment with a low C / N ratio, exhibiting low denitrification efficiency and insufficient denitrification effect.

[0005] Patent CN106396097A discloses an integrated denitrification device and method based on autotrophic / heterotrophic denitrification, consisting of three parts: an autotrophic denitrification zone, a heterotrophic denitrification zone, and a buffer cavity. It utilizes a micro-electrolysis packing layer and a sulfur / limestone packing layer. Inside the heterotrophic denitrification zone, a biomass distiller's grains layer is incorporated to increase the C / N ratio of the wastewater, thus promoting the heterotrophic denitrification process. However, this scheme generates a large amount of sludge during the heterotrophic denitrification process due to the addition of the biomass distiller's grains layer, increasing sludge treatment costs and resulting in high water treatment costs. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated autotrophic-heterotrophic denitrification device and method, which solves the problems of low denitrification efficiency and high cost at low C / N ratios, and how to ensure the coordinated and stable operation of the autotrophic-heterotrophic denitrification process.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes a raw water tank and a sedimentation tank, characterized in that it also includes a three-layer denitrification tower.

[0009] The raw water tank is connected to the inlet at the bottom of the three-layer denitrification tower, and the outlet pipe at the top of the three-layer denitrification tower is connected to the degassing tank on one side of the sedimentation tank. The bottom of the degassing tank is connected to the bottom of the sedimentation tank. A sludge discharge port is set at the bottom of the sedimentation tank, and an outlet is set at the top of the sedimentation tank.

[0010] A sludge discharge pipe is installed on the opposite side of the inlet of the three-layer denitrification tower.

[0011] The three-layer denitrification tower is arranged from bottom to top as follows: a carbon fiber denitrification filter layer, a sulfur autotrophic packing layer, and a stirrer.

[0012] Furthermore, the three-layer denitrification tower is equipped with monitoring instruments, including a pH meter, dissolved oxygen meter, oxidation-reduction potential meter, and electromagnetic flow meter.

[0013] Furthermore, multiple linear steel pipe layers are evenly distributed along the tower wall of the carbon fiber denitrification filter layer, and carbon fiber filter media are sequentially arranged on the linear steel pipe layers. A sludge inlet is set inside the three-layer denitrification tower where the carbon fiber denitrification filter layer is located.

[0014] Furthermore, the sulfur autotrophic packing layer is filled with suspended MBBR packing, and the lower and upper ends of the sulfur autotrophic packing layer are perforated meshes that connect to the carbon fiber denitrification filter layer and the effluent pipe, respectively.

[0015] Furthermore, inclined tube packing is installed in the middle of the sedimentation tank. The inclined tube packing is made of ethylene-propylene copolymer honeycomb inclined tube packing with a pore size of φ80mm.

[0016] A method for operating a three-stage denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes the following steps:

[0017] Step 1: The municipal sludge is subjected to a 14-day acclimation process. Carbon fiber filter media and suspended MBBR packing are added to the carbon fiber denitrification filter layer and the sulfur autotrophic packing layer respectively for acclimation. The microbial acclimation time is 21 days, until the NO3-N content in the effluent is less than 1.5 mg / L.

[0018] Step 2: The raw water tank transports the wastewater to be treated from the inlet to the carbon fiber denitrification filter layer of the three-layer denitrification tower. The wastewater to be treated first passes through the carbon fiber filter media in the linear steel pipe layer to carry out heterotrophic denitrification reaction.

[0019] Step 3: The wastewater to be treated flowing out of the carbon fiber denitrification filter layer enters the sulfur autotrophic packing layer to carry out the autotrophic denitrification process;

[0020] Step 4: The raw water flowing out from the effluent pipe at the top of the three-layer denitrification tower is degassed in the deaeration tank and then enters the sedimentation tank. The inclined tube packing in the sedimentation tank filters the sludge in the raw water. The filtered sludge is discharged through the bottom sludge discharge port and pumped by the return pump to the carbon fiber denitrification filter layer of the three-layer denitrification tower for recycling. Then the water is discharged from the effluent outlet at the top of the sedimentation tank, completing the denitrification treatment.

[0021] Furthermore, the preparation steps for the suspended MBBR packing are as follows:

[0022] S1. In a reaction vessel, FeCl3·6H2O, 2-aminoterephthalic acid, and 2,5-dimercaptoterephthalic acid are dissolved sequentially in DMF. Then, a 0.4M NaOH solution is added, and the mixture is stirred continuously for 15-20 minutes. The mixture is then transferred to a polytetrafluoroethylene-lined reaction vessel and heated at 120-150℃ for 10-15 hours. After filtration and vacuum drying, the coating filler is obtained.

[0023] S2. The coating filler is ultrasonically dispersed in ethanol in a reaction vessel to obtain an ethanol dispersion. Methacrylic acid is ultrasonically dissolved in ethanol and then mixed with an equal volume of the ethanol dispersion. The mixture is heated in a sealed container to 40-50℃ for 6-8 hours. The solvent is removed by rotary evaporation and then vacuum dried to obtain the modified coating filler.

[0024] S3. Add polyethylene filler at 0.2 mol·L⁻¹ -1 After acidification in H2SO4 for 2-3 hours, the polyethylene filler was removed, washed with deionized water until the final washing solution was neutral, and then dried to obtain acidified polyethylene filler.

[0025] S4. In a reaction vessel, ultrasonically disperse the modified coating filler in a 0.01 mol / L tris(hydroxymethyl)aminomethane solution. Add 2-3 wt% polyvinyl alcohol solution to the reaction vessel, then add dopamine hydrochloride. After stirring to dissolve, add the acidified polyethylene filler to the reaction vessel and place it in a constant temperature shaker at 160-180 rpm. -1 The reaction was carried out at 30-40℃ for 6-8 hours. After the reaction was completed, the mixture was washed with deionized water and dried to obtain the suspended MBBR packing.

[0026] Furthermore, the ratio of FeCl3·6H2O, 2-aminoterephthalic acid, 2,5-dimercaptoterephthalic acid, DMF and NaOH solution in S1 is 5-8g: 2-6g: 2-3g: 200-250mL: 30-50mL.

[0027] Furthermore, the ratio of coating filler to ethanol in S2 is 2.5-4.5g:30-50mL; the ratio of methacrylic acid to ethanol is 1.5-2.5g:30-50mL.

[0028] Furthermore, the ratio of modified coating filler, tris(hydroxymethyl)aminomethane solution, polyvinyl alcohol solution, dopamine hydrochloride and acidified polyethylene filler in S4 is 3-5g: 80-100mL: 100-120mL: 0.5-1.5g: 400-600g.

[0029] The beneficial effects of this invention are:

[0030] (1) The three-layer denitrification tower of the present invention has high denitrification efficiency and strong processing capacity. It adopts a combination of autotrophic and heterotrophic methods, which greatly improves the denitrification capacity of the reactor. The carbon fiber filter material and the suspended MBBR packing have a large surface area and many micropores on the surface, which greatly increases the attachment space of denitrifying microorganisms. The suspended MBBR packing has high hydrophilicity and good binding ability with denitrifying microorganisms, and the sulfur autotrophic denitrification efficiency is high.

[0031] (2) This invention uniformly adheres the coating filler to the surface of polyethylene filler, enhances the hydrophilicity of the polyethylene filler surface through polyvinyl alcohol, and introduces thiol and amino groups into the coating filler to improve the binding ability and denitrification ability of the coating filler with denitrifying microorganisms, resulting in high biofilm formation efficiency. Through the click reaction of thiol with methacrylic acid, methacrylic acid is grafted onto the surface of the coating filler. The good compatibility between methacrylic acid and polyvinyl alcohol improves the dispersibility of the coating filler in polyvinyl alcohol, thereby uniformly dispersing the coating filler on the surface of polyethylene filler.

[0032] (3) The equipment of the present invention adopts a combination of multiple processes, occupies a small area, and operates stably. It is equipped with monitoring equipment such as pH meter, dissolved oxygen meter, oxidation-reduction potential meter, and electromagnetic flow meter, which can reflect the equipment operation status at all times. Furthermore, a sedimentation tank, inclined tube packing and sludge return device are configured at the outlet to reduce sludge loss. The sludge is recycled through the return pump, which greatly improves the membrane blockage of biological metabolites. Attached Figure Description

[0033] The invention will now be further described with reference to the accompanying drawings.

[0034] Figure 1 This is a process flow diagram of the present invention;

[0035] In the diagram: 1. Raw water tank; 2. Monitoring instruments; 3. Inlet; 4. Three-layer denitrification tower; 5. Carbon fiber denitrification filter layer; 6. Sulfur autotrophic packing layer; 7. Agitator; 8. Outlet pipe; 9. Sludge discharge pipe; 10. Return pump; 11. Sedimenter; 12. Inclined tube packing; 13. Outlet; 14. Deaeration tank; 15. Deaeration mixer; 16. Sludge discharge port. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1: A three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes a raw water tank 1, a three-layer denitrification tower 4, and a sedimentation tank 11.

[0038] The raw water tank 1 is connected to the inlet 3 at the lower end of the three-layer denitrification tower 4. A sludge discharge pipe 9 is installed on the opposite side of the inlet 3. The outlet pipe 8 at the upper end of the three-layer denitrification tower 4 is connected to the degassing tank 14 on one side of the sedimentation tank 11. A degassing mixer 15 is installed at the top of the degassing tank 14. The bottom of the degassing tank 14 is connected to the lower end of the sedimentation tank 11. A sludge discharge port 16 is installed at the lower end of the sedimentation tank 11. An outlet 13 is installed at the upper end of the sedimentation tank 11.

[0039] The three-layer denitrification tower 4 is equipped with monitoring instruments 2, including a pH meter, dissolved oxygen meter, oxidation-reduction potential meter, and electromagnetic flow meter. The monitoring unit reflects the progress of the chemical reaction in the tower by monitoring the values ​​of each instrument and adjusts it in time to achieve the best reaction conditions.

[0040] The three-layer denitrification tower 4 is arranged from bottom to top as follows: carbon fiber denitrification filter layer 5, sulfur autotrophic packing layer 6, and agitator 7. The agitator 7 is installed at the top of the three-layer denitrification tower 4, penetrating the tower body, and is used for mixing the packing materials and water samples in each part.

[0041] The carbon fiber denitrification filter layer 5 has multiple linear steel pipe layers evenly distributed along the tower wall. Carbon fiber filter media are attached to the linear steel pipe layers in sequence. A sludge inlet is set inside the three-layer denitrification tower 4 where the carbon fiber denitrification filter layer 5 is located, and the sludge is mixed with the carbon fiber filter media.

[0042] The sulfur autotrophic packing layer 6 is filled with suspended MBBR packing. Both the lower and upper ends of the sulfur autotrophic packing layer 6 have perforated meshes that connect to the carbon fiber denitrification filter layer 5 and the outlet pipe 8, respectively.

[0043] A degassing tank 14 is provided on one side of the sedimentation tank 11. The bottom of the degassing tank 14 is connected to the lower side wall of the sedimentation tank 11. An inclined tube packing 12 is provided in the middle of the sedimentation tank 11. The inclined tube packing 12 is made of ethylene propylene copolymer honeycomb inclined tube packing 12 with a pore size of φ80mm. An outlet 13 is provided at the upper end of the sedimentation tank 11. The sludge discharged from the sludge discharge port 16 at the lower end of the sedimentation tank 11 is returned to the carbon fiber denitrification filter layer 5 by the return pump 10.

[0044] A method for operating a three-stage denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes the following steps:

[0045] Step 1: The municipal sludge is subjected to a 14-day fermentation process. Carbon fiber filter media and suspended MBBR packing are added to the carbon fiber denitrification filter layer 5 and the sulfur autotrophic packing layer 6 respectively for acclimatization. The microbial acclimatization time is 21 days, until the NO3-N content in the effluent is lower than 1.5 mg / L.

[0046] Step 2: The raw water tank 1 transports the wastewater to be treated from the inlet 3 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4. The wastewater to be treated first passes through the carbon fiber filter media in the linear steel pipe layer. The carbon fiber filter media provides a large number of pores and specific surface area for the denitrifying bacteria in the sludge to attach. The sludge and organic matter in the wastewater to be treated are used as electron donors, and nitrate nitrogen and nitrite nitrogen are used as electron acceptors to carry out heterotrophic denitrification reaction.

[0047] Step 3: The wastewater to be treated flowing out of the carbon fiber denitrification filter layer 5 enters the sulfur autotrophic packing layer 6, where the sulfur in the suspended MBBR packing is used as an electron donor to carry out the autotrophic denitrification process. Part of the sludge produced by autotrophic denitrification will settle into the carbon fiber denitrification filter layer 5, and part of the sludge will enter the sedimentation tank 11 for sedimentation and then be pumped back to the carbon fiber denitrification filter layer 5 for sludge recycling.

[0048] Step 4: The raw water flowing out from the outlet pipe 8 at the top of the three-layer denitrification tower 4 is degassed in the degassing tank 14 and then enters the sedimentation tank 11. The inclined tube packing 12 in the water of the sedimentation tank 11 filters the sludge in the raw water. The filtered sludge is discharged through the bottom sludge discharge port 16 and pumped by the return pump 10 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4 for recycling. Then the water is discharged from the outlet 13 at the top of the sedimentation tank 11, completing the denitrification treatment.

[0049] Example 2: A three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes a raw water tank 1, a three-layer denitrification tower 4, and a sedimentation tank 11.

[0050] The raw water tank 1 is connected to the inlet 3 at the lower end of the three-layer denitrification tower 4. A sludge discharge pipe 9 is installed on the opposite side of the inlet 3. The outlet pipe 8 at the upper end of the three-layer denitrification tower 4 is connected to the degassing tank 14 on one side of the sedimentation tank 11. A degassing mixer 15 is installed at the top of the degassing tank 14. The bottom of the degassing tank 14 is connected to the lower end of the sedimentation tank 11. A sludge discharge port 16 is installed at the lower end of the sedimentation tank 11. An outlet 13 is installed at the upper end of the sedimentation tank 11.

[0051] The three-layer denitrification tower 4 is equipped with monitoring instruments 2, including a pH meter, dissolved oxygen meter, oxidation-reduction potential meter, and electromagnetic flow meter. The monitoring unit reflects the progress of the chemical reaction in the tower by monitoring the values ​​of each instrument and adjusts it in time to achieve the best reaction conditions.

[0052] The three-layer denitrification tower 4 is arranged from bottom to top as follows: carbon fiber denitrification filter layer 5, sulfur autotrophic packing layer 6, and agitator 7. The agitator 7 is installed at the top of the three-layer denitrification tower 4, penetrating the tower body, and is used for mixing the packing materials and water samples in each part.

[0053] The carbon fiber denitrification filter layer 5 has multiple linear steel pipe layers evenly distributed along the tower wall. Carbon fiber filter media are attached to the linear steel pipe layers in sequence. A sludge inlet is set inside the three-layer denitrification tower 4 where the carbon fiber denitrification filter layer 5 is located, and the sludge is mixed with the carbon fiber filter media.

[0054] The sulfur autotrophic packing layer 6 is filled with suspended MBBR packing. Both the lower and upper ends of the sulfur autotrophic packing layer 6 have perforated meshes that connect to the carbon fiber denitrification filter layer 5 and the outlet pipe 8, respectively.

[0055] A degassing tank 14 is provided on one side of the sedimentation tank 11. The bottom of the degassing tank 14 is connected to the lower side wall of the sedimentation tank 11. An inclined tube packing 12 is provided in the middle of the sedimentation tank 11. The inclined tube packing 12 is made of ethylene propylene copolymer honeycomb inclined tube packing 12 with a pore size of φ80mm. An outlet 13 is provided at the upper end of the sedimentation tank 11. The sludge discharged from the sludge discharge port 16 at the lower end of the sedimentation tank 11 is returned to the carbon fiber denitrification filter layer 5 by the return pump 10.

[0056] A method for operating a three-stage denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes the following steps:

[0057] Step 1: The municipal sludge is subjected to a 14-day fermentation process. Carbon fiber filter media and suspended MBBR packing are added to the carbon fiber denitrification filter layer 5 and the sulfur autotrophic packing layer 6 respectively for acclimatization. The microbial acclimatization time is 21 days, until the NO3-N content in the effluent is lower than 1.5 mg / L.

[0058] Step 2: The raw water tank 1 transports the wastewater to be treated from the inlet 3 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4. The wastewater to be treated first passes through the carbon fiber filter media in the linear steel pipe layer. The carbon fiber filter media provides a large number of pores and specific surface area for the denitrifying bacteria in the sludge to attach. The sludge and organic matter in the wastewater to be treated are used as electron donors, and nitrate nitrogen and nitrite nitrogen are used as electron acceptors to carry out heterotrophic denitrification reaction.

[0059] Step 3: The wastewater to be treated flowing out of the carbon fiber denitrification filter layer 5 enters the sulfur autotrophic packing layer 6, where the sulfur in the suspended MBBR packing is used as an electron donor to carry out the autotrophic denitrification process. Part of the sludge produced by autotrophic denitrification will settle into the carbon fiber denitrification filter layer 5, and part of the sludge will enter the sedimentation tank 11 for sedimentation and then be pumped back to the carbon fiber denitrification filter layer 5 for sludge recycling.

[0060] Step 4: The raw water flowing out from the outlet pipe 8 at the top of the three-layer denitrification tower 4 is degassed in the degassing tank 14 and then enters the sedimentation tank 11. The inclined tube packing 12 in the water of the sedimentation tank 11 filters the sludge in the raw water. The filtered sludge is discharged through the bottom sludge discharge port 16 and pumped by the return pump 10 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4 for recycling. Then the water is discharged from the outlet 13 at the top of the sedimentation tank 11, completing the denitrification treatment.

[0061] Suspended MBBR packing is prepared by the following steps:

[0062] S1. In a reaction vessel, 5g FeCl3·6H2O, 2g 2-aminoterephthalic acid, and 2g 2,5-dimercaptoterephthalic acid were dissolved sequentially in 200mL DMF. Then, 30mL of 0.4M NaOH solution was added, and the mixture was stirred continuously for 15min. The solution was then transferred to a polytetrafluoroethylene-lined reaction vessel and heated at 120℃ for 10h. After filtration and vacuum drying, the coating filler was obtained.

[0063] S2. In a reaction vessel, 2.5g of coating filler was ultrasonically dispersed in 30mL of ethanol to obtain an ethanol dispersion. 1.5g of methacrylic acid was ultrasonically dissolved in 30mL of ethanol and then mixed with an equal volume of the ethanol dispersion. The mixture was heated to 40℃ in a sealed container for 6 hours. After removing the solvent by rotary evaporation, the mixture was vacuum dried to obtain the modified coating filler.

[0064] S3. Add polyethylene filler at 0.2 mol·L⁻¹ -1 After acidification in H2SO4 for 2 hours, the polyethylene filler was removed, washed with deionized water until the final washing solution was neutral, and then dried to obtain acidified polyethylene filler.

[0065] S4. In a reaction vessel, ultrasonically disperse 3g of modified coating filler in 80mL of 0.01mol / L tris(hydroxymethyl)aminomethane solution. Add 100mL of 2wt% polyvinyl alcohol solution to the reaction vessel, then add 0.5g of dopamine hydrochloride. After stirring to dissolve, add 400g of acidified polyethylene filler to the reaction vessel and place it in a constant temperature shaker at 160r·min. -1 The reaction was carried out at 30℃ for 6 hours. After the reaction was completed, the mixture was washed with deionized water and dried to obtain the suspended MBBR packing.

[0066] Example 3: A three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification, including raw water tank 1, three-layer denitrification tower 4 and sedimentation tank 11.

[0067] The raw water tank 1 is connected to the inlet 3 at the lower end of the three-layer denitrification tower 4. A sludge discharge pipe 9 is installed on the opposite side of the inlet 3. The outlet pipe 8 at the upper end of the three-layer denitrification tower 4 is connected to the degassing tank 14 on one side of the sedimentation tank 11. A degassing mixer 15 is installed at the top of the degassing tank 14. The bottom of the degassing tank 14 is connected to the lower end of the sedimentation tank 11. A sludge discharge port 16 is installed at the lower end of the sedimentation tank 11. An outlet 13 is installed at the upper end of the sedimentation tank 11.

[0068] The three-layer denitrification tower 4 is equipped with monitoring instruments 2, including a pH meter, dissolved oxygen meter, oxidation-reduction potential meter, and electromagnetic flow meter. The monitoring unit reflects the progress of the chemical reaction in the tower by monitoring the values ​​of each instrument and adjusts it in time to achieve the best reaction conditions.

[0069] The three-layer denitrification tower 4 is arranged from bottom to top as follows: carbon fiber denitrification filter layer 5, sulfur autotrophic packing layer 6, and agitator 7. The agitator 7 is installed at the top of the three-layer denitrification tower 4, penetrating the tower body, and is used for mixing the packing materials and water samples in each part.

[0070] The carbon fiber denitrification filter layer 5 has multiple linear steel pipe layers evenly distributed along the tower wall. Carbon fiber filter media are attached to the linear steel pipe layers in sequence. A sludge inlet is set inside the three-layer denitrification tower 4 where the carbon fiber denitrification filter layer 5 is located, and the sludge is mixed with the carbon fiber filter media.

[0071] The sulfur autotrophic packing layer 6 is filled with suspended MBBR packing. Both the lower and upper ends of the sulfur autotrophic packing layer 6 have perforated meshes that connect to the carbon fiber denitrification filter layer 5 and the outlet pipe 8, respectively.

[0072] A degassing tank 14 is provided on one side of the sedimentation tank 11. The bottom of the degassing tank 14 is connected to the lower side wall of the sedimentation tank 11. An inclined tube packing 12 is provided in the middle of the sedimentation tank 11. The inclined tube packing 12 is made of ethylene propylene copolymer honeycomb inclined tube packing 12 with a pore size of φ80mm. An outlet 13 is provided at the upper end of the sedimentation tank 11. The sludge discharged from the sludge discharge port 16 at the lower end of the sedimentation tank 11 is returned to the carbon fiber denitrification filter layer 5 by the return pump 10.

[0073] A method for operating a three-stage denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes the following steps:

[0074] Step 1: The municipal sludge is subjected to a 14-day fermentation process. Carbon fiber filter media and suspended MBBR packing are added to the carbon fiber denitrification filter layer 5 and the sulfur autotrophic packing layer 6 respectively for acclimatization. The microbial acclimatization time is 21 days, until the NO3-N content in the effluent is lower than 1.5 mg / L.

[0075] Step 2: The raw water tank 1 transports the wastewater to be treated from the inlet 3 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4. The wastewater to be treated first passes through the carbon fiber filter media in the linear steel pipe layer. The carbon fiber filter media provides a large number of pores and specific surface area for the denitrifying bacteria in the sludge to attach. The sludge and organic matter in the wastewater to be treated are used as electron donors, and nitrate nitrogen and nitrite nitrogen are used as electron acceptors to carry out heterotrophic denitrification reaction.

[0076] Step 3: The wastewater to be treated flowing out of the carbon fiber denitrification filter layer 5 enters the sulfur autotrophic packing layer 6, where the sulfur in the suspended MBBR packing is used as an electron donor to carry out the autotrophic denitrification process. Part of the sludge produced by autotrophic denitrification will settle into the carbon fiber denitrification filter layer 5, and part of the sludge will enter the sedimentation tank 11 for sedimentation and then be pumped back to the carbon fiber denitrification filter layer 5 for sludge recycling.

[0077] Step 4: The raw water flowing out from the outlet pipe 8 at the top of the three-layer denitrification tower 4 is degassed in the degassing tank 14 and then enters the sedimentation tank 11. The inclined tube packing 12 in the water of the sedimentation tank 11 filters the sludge in the raw water. The filtered sludge is discharged through the bottom sludge discharge port 16 and pumped by the return pump 10 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4 for recycling. Then the water is discharged from the outlet 13 at the top of the sedimentation tank 11, completing the denitrification treatment.

[0078] Suspended MBBR packing is prepared by the following steps:

[0079] S1. In a reaction vessel, 6.5g FeCl3·6H2O, 4g 2-aminoterephthalic acid, and 2.5g 2,5-dimercaptoterephthalic acid were dissolved sequentially in 225mL DMF. Then, 40mL of 0.4M NaOH solution was added, and the mixture was stirred continuously for 17min. The solution was then transferred to a polytetrafluoroethylene-lined reaction vessel and heated at 135℃ for 12.5h. After filtration and vacuum drying, the coating filler was obtained.

[0080] S2. In a reaction vessel, 3.5g of coating filler was ultrasonically dispersed in 40mL of ethanol to obtain an ethanol dispersion. 2g of methacrylic acid was ultrasonically dissolved in 40mL of ethanol and then mixed with an equal volume of the ethanol dispersion. The mixture was then heated to 45℃ in a sealed container for 7h. After removing the solvent by rotary evaporation, the mixture was vacuum dried to obtain the modified coating filler.

[0081] S3. Add polyethylene filler at 0.2 mol·L⁻¹ -1 After acidification in H2SO4 for 2.5 hours, the polyethylene filler was removed, washed with deionized water until the final washing solution was neutral, and then dried to obtain acidified polyethylene filler.

[0082] S4. In a reaction vessel, ultrasonically disperse 4g of modified coating filler in 90mL of 0.01mol / L tris(hydroxymethyl)aminomethane solution. Add 110mL of 2.5wt% polyvinyl alcohol solution to the reaction vessel, then add 1g of dopamine hydrochloride. After stirring to dissolve, add 500g of acidified polyethylene filler to the reaction vessel and place it in a constant temperature shaker at 170r·min. -1 The reaction was carried out at 35℃ for 7 hours. After the reaction was completed, the mixture was washed with deionized water and dried to obtain the suspended MBBR packing.

[0083] Example 4: A three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification, including a raw water tank 1, a three-layer denitrification tower 4 and a sedimentation tank 11.

[0084] The raw water tank 1 is connected to the inlet 3 at the lower end of the three-layer denitrification tower 4. A sludge discharge pipe 9 is installed on the opposite side of the inlet 3. The outlet pipe 8 at the upper end of the three-layer denitrification tower 4 is connected to the degassing tank 14 on one side of the sedimentation tank 11. A degassing mixer 15 is installed at the top of the degassing tank 14. The bottom of the degassing tank 14 is connected to the lower end of the sedimentation tank 11. A sludge discharge port 16 is installed at the lower end of the sedimentation tank 11. An outlet 13 is installed at the upper end of the sedimentation tank 11.

[0085] The three-layer denitrification tower 4 is equipped with monitoring instruments 2, including a pH meter, dissolved oxygen meter, oxidation-reduction potential meter, and electromagnetic flow meter. The monitoring unit reflects the progress of the chemical reaction in the tower by monitoring the values ​​of each instrument and adjusts it in time to achieve the best reaction conditions.

[0086] The three-layer denitrification tower 4 is arranged from bottom to top as follows: carbon fiber denitrification filter layer 5, sulfur autotrophic packing layer 6, and agitator 7. The agitator 7 is installed at the top of the three-layer denitrification tower 4, penetrating the tower body, and is used for mixing the packing materials and water samples in each part.

[0087] The carbon fiber denitrification filter layer 5 has multiple linear steel pipe layers evenly distributed along the tower wall. Carbon fiber filter media are attached to the linear steel pipe layers in sequence. A sludge inlet is set inside the three-layer denitrification tower 4 where the carbon fiber denitrification filter layer 5 is located, and the sludge is mixed with the carbon fiber filter media.

[0088] The sulfur autotrophic packing layer 6 is filled with suspended MBBR packing. Both the lower and upper ends of the sulfur autotrophic packing layer 6 have perforated meshes that connect to the carbon fiber denitrification filter layer 5 and the outlet pipe 8, respectively.

[0089] A degassing tank 14 is provided on one side of the sedimentation tank 11. The bottom of the degassing tank 14 is connected to the lower side wall of the sedimentation tank 11. An inclined tube packing 12 is provided in the middle of the sedimentation tank 11. The inclined tube packing 12 is made of ethylene propylene copolymer honeycomb inclined tube packing 12 with a pore size of φ80mm. An outlet 13 is provided at the upper end of the sedimentation tank 11. The sludge discharged from the sludge discharge port 16 at the lower end of the sedimentation tank 11 is returned to the carbon fiber denitrification filter layer 5 by the return pump 10.

[0090] A method for operating a three-stage denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes the following steps:

[0091] Step 1: The municipal sludge is subjected to a 14-day fermentation process. Carbon fiber filter media and suspended MBBR packing are added to the carbon fiber denitrification filter layer 5 and the sulfur autotrophic packing layer 6 respectively for acclimatization. The microbial acclimatization time is 21 days, until the NO3-N content in the effluent is lower than 1.5 mg / L.

[0092] Step 2: The raw water tank 1 transports the wastewater to be treated from the inlet 3 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4. The wastewater to be treated first passes through the carbon fiber filter media in the linear steel pipe layer. The carbon fiber filter media provides a large number of pores and specific surface area for the denitrifying bacteria in the sludge to attach. The sludge and organic matter in the wastewater to be treated are used as electron donors, and nitrate nitrogen and nitrite nitrogen are used as electron acceptors to carry out heterotrophic denitrification reaction.

[0093] Step 3: The wastewater to be treated flowing out of the carbon fiber denitrification filter layer 5 enters the sulfur autotrophic packing layer 6, where the sulfur in the suspended MBBR packing is used as an electron donor to carry out the autotrophic denitrification process. Part of the sludge produced by autotrophic denitrification will settle into the carbon fiber denitrification filter layer 5, and part of the sludge will enter the sedimentation tank 11 for sedimentation and then be pumped back to the carbon fiber denitrification filter layer 5 for sludge recycling.

[0094] Step 4: The raw water flowing out from the outlet pipe 8 at the top of the three-layer denitrification tower 4 is degassed in the degassing tank 14 and then enters the sedimentation tank 11. The inclined tube packing 12 in the water of the sedimentation tank 11 filters the sludge in the raw water. The filtered sludge is discharged through the bottom sludge discharge port 16 and pumped by the return pump 10 to the carbon fiber denitrification filter layer 5 of the three-layer denitrification tower 4 for recycling. Then the water is discharged from the outlet 13 at the top of the sedimentation tank 11, completing the denitrification treatment.

[0095] A method for operating a three-stage denitrification tower device based on sulfur autotrophic-heterotrophic denitrification includes the following steps:

[0096] Step 1: The municipal sludge is subjected to a 14-day fermentation process. Carbon fiber filter media and suspended MBBR packing are added to the carbon fiber denitrification filter layer and the sulfur autotrophic packing layer respectively for acclimatization. The microbial acclimatization time is 21 days, until the NO3-N content in the effluent is lower than 1.5 mg / L.

[0097] Step 2: The raw water tank transports the wastewater to be treated from the inlet to the carbon fiber denitrification filter layer of the three-layer denitrification tower. The wastewater first passes through the carbon fiber filter media in the linear steel pipe layer. The carbon fiber filter media provides a large number of pores and specific surface area for the denitrifying bacteria in the sludge to attach. The sludge and organic matter in the wastewater to be treated act as electron donors, and nitrate nitrogen and nitrite nitrogen act as electron acceptors to carry out heterotrophic denitrification reaction.

[0098] Step 3: The wastewater to be treated flowing out of the carbon fiber denitrification filter layer enters the sulfur autotrophic packing layer, where the sulfur in the suspended MBBR packing material serves as an electron donor for autotrophic denitrification. Part of the sludge produced by autotrophic denitrification will settle into the carbon fiber denitrification filter layer, while the remaining sludge will enter a sedimentation tank and then be pumped back to the carbon fiber denitrification filter layer for sludge recycling.

[0099] Step 4: The raw water flowing out from the effluent pipe at the top of the three-layer denitrification tower is degassed in the deaeration tank and then enters the sedimentation tank. The inclined tube packing in the sedimentation tank filters the sludge in the raw water. The filtered sludge is discharged through the bottom sludge discharge port and pumped by the return pump to the carbon fiber denitrification filter layer of the three-layer denitrification tower for recycling. Then the water is discharged from the effluent outlet at the top of the sedimentation tank, completing the denitrification treatment.

[0100] Suspended MBBR packing is prepared by the following steps:

[0101] S1. In a reaction vessel, 8g FeCl3·6H2O, 6g 2-aminoterephthalic acid, and 3g 2,5-dimercaptoterephthalic acid were dissolved sequentially in 250mL DMF. Then, 50mL of 0.4M NaOH solution was added, and the mixture was stirred continuously for 20min. The solution was then transferred to a polytetrafluoroethylene-lined reaction vessel and heated at 150℃ for 15h. After filtration and vacuum drying, the coating filler was obtained.

[0102] S2. In a reaction vessel, 4.5g of coating filler was ultrasonically dispersed in 50mL of ethanol to obtain an ethanol dispersion. 2.5g of methacrylic acid was ultrasonically dissolved in 50mL of ethanol and then mixed with an equal volume of the ethanol dispersion. The mixture was then heated to 50℃ in a sealed container for 8 hours. After removing the solvent by rotary evaporation, the mixture was vacuum dried to obtain the modified coating filler.

[0103] S3. Add polyethylene filler at 0.2 mol·L⁻¹ -1 After acidification in H2SO4 for 3 hours, the polyethylene filler was removed, washed with deionized water until the final washing solution was neutral, and then dried to obtain acidified polyethylene filler.

[0104] S4. In a reaction vessel, ultrasonically disperse 5g of modified coating filler in 100mL of 0.01mol / L tris(hydroxymethyl)aminomethane solution. Add 120mL of 3wt% polyvinyl alcohol solution to the reaction vessel, then add 1.5g of dopamine hydrochloride. After stirring and dissolving, add 600g of acidified polyethylene filler to the reaction vessel and place it in a constant temperature shaker at 180r·min. -1 The reaction was carried out at 40℃ for 8 hours. After the reaction was completed, the mixture was washed with deionized water and dried to obtain the suspended MBBR packing.

[0105] The carboxyl groups in methacrylic acid and the hydroxyl groups in polyvinyl alcohol can form hydrogen bonds. Taking advantage of the compatibility of methacrylic acid in polyvinyl alcohol, the coating filler is dispersed in polyvinyl alcohol. By mixing polyvinyl alcohol with dopamine hydrochloride and adhering it to the surface of the polyethylene filler, the coating filler is uniformly dispersed on the surface of the polyethylene filler. The coating filler contains amino and mercapto groups. The amino groups are positively charged in water and can attract negatively charged microorganisms. At the same time, the -NH groups can form hydrogen bonds with the -COOH groups, which can improve the binding of the coating filler with denitrifying microorganisms and improve the biofilm efficiency. The sulfur element in the mercapto groups can be utilized by denitrifying bacteria to help fix nitrogen. The iron atoms in the coating filler can also serve as a reduced matrix to improve the efficiency of sulfur autotrophic denitrification.

[0106] Comparative Example 1: The difference from Example 2 is that the suspended MBBR packing is polyethylene packing.

[0107] Comparative Example 2: The difference from Example 2 is that no modified coating filler is added in S4.

[0108] Comparative Example 3: The difference from Example 2 is that in S4, the modified coating filler is replaced with a coating filler.

[0109] Some of the reagents used in the examples and comparative examples came from the following sources:

[0110] The ethylene-propylene copolymer honeycomb inclined tube packing was purchased from Henan Huaxin Environmental Protection Technology Co., Ltd.

[0111] The polyethylene filler was purchased from Gongyi Yiyang Water Treatment Materials Co., Ltd.

[0112] FeCl3·6H2O, 2-aminoterephthalic acid, DMF, methacrylic acid, tris(hydroxymethyl)aminomethane, and polyvinyl alcohol were purchased from Sigma-Aldrich.

[0113] 2,5-Dimercaptoterephthalic acid was purchased from Maclean's Reagent.

[0114] Dopamine hydrochloride (C8H) 11 NO2·HCl was purchased from Sinopharm Reagent.

[0115] Actual operating water quality: pH 6-9, influent nitrate nitrogen <100mg / L, effluent nitrate nitrogen can stably reach 4mg / L

[0116] For Examples 2-4 and Comparative Examples 1-3, water was introduced into the device according to the working method, using a continuous water inlet method, with an inlet flow rate of 40 m³ / h. 3The influent pH was 7, and the nitrate nitrogen content was 100 mg / L. Starting from the second day of continuous influent feeding, samples were taken daily at 9:30 AM. The samples were filtered through 0.45 μm filter paper, and the nitrate nitrogen content at the outlet was tested using an intelligent digester method. Starting from the fifth day of continuous influent feeding, the biofilm content on the MBBR packing material was tested using a gravimetric method. The test results are shown in Table 1.

[0117] Table 1

[0118]

[0119] As shown in Table 1, the three-layer denitrification tower device of the present invention has a good denitrification effect on wastewater. The nitrate nitrogen content at the effluent of Examples 2-4 reaches below 5 mg / L. Comparative Example 1, due to the use of only polyethylene packing, has poor hydrophilicity and poor microbial adhesion, resulting in poor denitrification effect. Comparative Example 2, due to the use of only polyvinyl alcohol to adhere to the surface of polyethylene packing, only improves the hydrophilicity of polyethylene packing and enhances its adhesion to microorganisms, thus the nitrate nitrogen content in the effluent is lower than that of Comparative Example 1. Comparative Example 3, due to the lack of modification of the coating packing, has poor dispersion of the coating packing in polyvinyl alcohol, resulting in low performance enhancement of polyethylene packing, thus the nitrate nitrogen content in the effluent is higher than that of Examples 2-4.

[0120] The suspended MBBR packing material in Examples 2-4 of this invention exhibits good biofilm formation, indicating a large attachment area and good adhesion effect for denitrifying microorganisms. This demonstrates that the suspended MBBR packing material prepared by this invention promotes biofilm formation by denitrifying microorganisms and can improve the efficiency of sulfur autotrophic denitrification. In Comparative Example 1, due to poor microbial adhesion ability, the biofilm weight change is minimal. Comparative Example 2 only improved the hydrophilicity of the polyethylene packing material, thus increasing the biofilm weight change. In Comparative Example 3, due to the aggregation of the coating packing material, the improvement in microbial adhesion ability of the polyethylene packing material is relatively small, therefore the biofilm weight change is slightly higher than that of Comparative Example 2.

[0121] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0122] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for operating a three-stage denitrification tower device based on sulfur autotrophic-heterotrophic denitrification, the device comprising a raw water tank (1) and a sedimentation tank (11), characterized in that, The device also includes a three-layer denitrification tower (4); The raw water tank (1) is connected to the inlet (3) at the bottom of the three-layer denitrification tower (4), and the outlet pipe (8) at the top of the three-layer denitrification tower (4) is connected to the degassing tank (14) on one side of the sedimentation tank (11). The bottom of the degassing tank (14) is connected to the bottom of the sedimentation tank (11). The sedimentation tank (11) is provided with a sludge discharge port (16) at the bottom and an outlet (13) at the top. A sludge discharge pipe (9) is installed on the opposite side of the inlet (3) of the three-layer denitrification tower (4). The three-layer denitrification tower (4) is arranged from bottom to top as follows: carbon fiber denitrification filter layer (5), sulfur autotrophic packing layer (6) and agitator (7); The carbon fiber denitrification filter layer (5) is uniformly distributed with multiple linear steel pipe layers along the tower wall. The carbon fiber filter material is attached to the linear steel pipe layers in sequence. The sludge inlet is set inside the three-layer denitrification tower (4) where the carbon fiber denitrification filter layer (5) is located. The working method includes the following steps: Step 1: The municipal sludge is subjected to 14 days of fermentation and acclimation. Carbon fiber filter media and suspended MBBR packing are added to the carbon fiber denitrification filter layer (5) and the sulfur autotrophic packing layer (6) respectively for acclimation. The microbial acclimation time is 21 days, and the acclimation is carried out until the NO3-N content in the effluent is less than 1.5 mg / L. Step 2: The raw water tank (1) transports the wastewater to be treated from the inlet (3) to the carbon fiber denitrification filter layer (5) of the three-layer denitrification tower (4). The wastewater to be treated first passes through the carbon fiber filter material in the linear steel pipe layer to carry out heterotrophic denitrification reaction. Step 3: The wastewater to be treated flowing out of the carbon fiber denitrification filter layer (5) enters the sulfur autotrophic packing layer (6) to carry out the autotrophic denitrification process; Step 4: The raw water flowing out from the outlet pipe (8) at the top of the three-layer denitrification tower (4) is degassed in the degassing tank (14) and then enters the sedimentation tank (11). The inclined tube packing (12) in the sedimentation tank (11) filters the sludge in the raw water. The filtered sludge is discharged through the bottom sludge discharge port (16) and pumped by the return pump (10) to the carbon fiber denitrification filter layer (5) of the three-layer denitrification tower (4) for recycling. Then the water is discharged from the outlet (13) at the top of the sedimentation tank (11) to complete the denitrification treatment. The preparation steps of the suspended MBBR packing are as follows: S1. FeCl3·6H2O, 2-aminoterephthalic acid, and 2,5-dimercaptoterephthalic acid are dissolved sequentially in DMF in a reaction vessel. Then, a 0.4M NaOH solution is added and the mixture is stirred continuously for 15-20 min. The mixture is then transferred to a polytetrafluoroethylene-lined reaction vessel and heated at 120-150℃ for 10-15 h. After filtration and vacuum drying, the coating filler is obtained. S2. The coating filler is ultrasonically dispersed in ethanol in a reaction vessel to obtain an ethanol dispersion. Methacrylic acid is ultrasonically dissolved in ethanol and then mixed with an equal volume of the ethanol dispersion. The mixture is heated in a sealed container to 40-50℃ for 6-8 hours. The solvent is removed by rotary evaporation and then vacuum dried to obtain the modified coating filler. S3. The polyethylene filler is placed in a solution of 0.2 mol·L⁻¹ -1 After acidification in H2SO4 for 2-3 hours, the polyethylene filler was removed, washed with deionized water until the final washing solution was neutral, and then dried to obtain acidified polyethylene filler. S4. In a reaction vessel, ultrasonically disperse the modified coating filler in a 0.01 mol / L tris(hydroxymethyl)aminomethane solution. Add 2-3 wt% polyvinyl alcohol solution to the reaction vessel, then add dopamine hydrochloride. After stirring and dissolving, add the acidified polyethylene filler to the reaction vessel and place it in a constant temperature shaker at 160-180 rpm. -1 The reaction was carried out at 30-40℃ for 6-8 hours. After the reaction was completed, the mixture was washed with deionized water and dried to obtain the suspended MBBR packing.

2. The operating method of the three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification according to claim 1, characterized in that, The three-layer denitrification tower (4) is equipped with monitoring instruments (2), including a pH meter, dissolved oxygen meter, oxidation-reduction potential meter, and electromagnetic flow meter.

3. The operating method of the three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification according to claim 1, characterized in that, The sulfur autotrophic packing layer (6) is filled with suspended MBBR packing. The lower and upper ends of the sulfur autotrophic packing layer (6) are perforated meshes that connect the carbon fiber denitrification filter layer (5) and the water outlet pipe (8) respectively.

4. The operating method of the three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification according to claim 1, characterized in that, The sedimentation tank (11) is equipped with inclined tube packing (12) in the middle. The inclined tube packing (12) is made of ethylene propylene copolymer honeycomb inclined tube packing (12) with a pore size of φ80mm.

5. The operating method of the three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification according to claim 1, characterized in that, The ratio of FeCl3·6H2O, 2-aminoterephthalic acid, 2,5-dimercaptoterephthalic acid, DMF and NaOH solution used in S1 is 5-8g: 2-6g: 2-3g: 200-250mL: 30-50mL.

6. The operating method of the three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification according to claim 1, characterized in that, The ratio of coating filler to ethanol in S2 is 2.5-4.5g:30-50mL; the ratio of methacrylic acid to ethanol is 1.5-2.5g:30-50mL.

7. The operating method of the three-layer denitrification tower device based on sulfur autotrophic-heterotrophic denitrification according to claim 1, characterized in that, The ratio of the modified coating filler, tris(hydroxymethyl)aminomethane solution, polyvinyl alcohol solution, dopamine hydrochloride and acidified polyethylene filler in S4 is 3-5g: 80-100mL: 100-120mL: 0.5-1.5g: 400-600g.

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