Method and device for simultaneous denitrification and phosphorus removal of sewage

Abstract

The present application belongs to the technical field of sewage treatment, and relates to a method and device for simultaneous nitrogen and phosphorus removal in sewage treatment. A surface modified three-dimensional mesh PVDC fiber loaded with modified sulfur autotrophic particles is filled in the sewage treatment device. Based on the synergistic effect of sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonia oxidation, efficient, low-consumption and sustainable nitrogen and phosphorus removal of low carbon-nitrogen ratio tail water in a sewage treatment plant is realized, and simultaneous nitrogen and phosphorus removal is realized.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and particularly to a method and apparatus for simultaneous nitrogen and phosphorus removal wastewater treatment. Background Technology

[0002] With the development of social industrialization and the gradual improvement of people's living standards, human activities generate a large amount of pollutants containing various elements such as C, N, and P, which are discharged into rivers, disrupting the balance of the ecosystem, leading to eutrophication of water bodies, and gradually deteriorating water quality. This results in water resource shortages.

[0003] Traditional wastewater treatment technologies face challenges such as low nitrogen and phosphorus removal efficiency, strong carbon source dependence, and high sludge production. Current mainstream processes include biological methods, chemical precipitation, and adsorption, which suffer from high costs and the risk of secondary pollution. Emerging technologies such as sulfur autotrophic denitrification, anaerobic ammonia oxidation, and biochar / mineral-based adsorption materials have become research hotspots due to their low-carbon, high-efficiency, and sustainable characteristics. They are particularly suitable for treating wastewater with low carbon-to-nitrogen ratios, driving the development of advanced nitrogen and phosphorus removal technologies for wastewater.

[0004] Chinese patent application CN 102923853 A discloses a wastewater treatment method involving coupled sulfur autotrophic denitrification and anaerobic ammonia oxidation for sulfur and nitrogen removal. This method utilizes sulfur autotrophic denitrifying bacteria under anaerobic conditions to reduce nitrates to nitrites, while simultaneously oxidizing sulfides to elemental sulfur. Nitrites and ammonia nitrogen undergo autotrophic denitrification under the action of anaerobic ammonia-oxidizing bacteria, generating nitrogen gas. An EGSB reactor is selected, inoculated with heterotrophic granular methanogenic bacteria or denitrifying bacteria, and the temperature is controlled between 25 and 35°C. The method involves gradually acclimating anaerobic granular sludge with coupled sulfur autotrophic denitrification and anaerobic ammonia oxidation (AAO). First, an EGSB reactor is started with low-COD wastewater. Anaerobic AAO bacteria are initially enriched in the reactor using nitrite and ammonia nitrogen as influent. Then, sulfur autotrophic denitrifying bacteria are gradually enriched using sulfide, nitrate, and ammonia nitrogen as influent. The reaction type is guided by controlling the ratio of sulfide to nitrate nitrogen (i.e., the sulfur-nitrogen molar ratio), ensuring the products are elemental sulfur and nitrite, thus achieving coupling with AAO. This coupling of sulfur autotrophic denitrification and AAO is achieved through the regulation of the reaction substrate and process conditions. However, this method has a long acclimation period, carries the risk of nitrite accumulation, and the high upflow velocity may lead to the loss of fine sludge. Summary of the Invention

[0005] This invention aims to provide a method and apparatus for simultaneous nitrogen and phosphorus removal in wastewater treatment. The method and apparatus utilize surface-modified three-dimensional mesh PVDC packing to load modified sulfur autotrophic particles, achieving simultaneous nitrogen and phosphorus removal through sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonia oxidation. This method is suitable for upgrading and retrofitting effluent from low C / N ratio wastewater treatment plants and for protecting drinking water sources.

[0006] To achieve the above objectives, the present invention provides a device for simultaneous nitrogen and phosphorus removal wastewater treatment, comprising an influent mixing unit, an influent distributor, an upflow reactor, a backwashing unit, and a sludge thickening tank; the influent mixing unit is connected to the upflow reactor via the influent distributor; the backwashing unit is disposed between the influent distributor and the surface-modified three-dimensional mesh PVDC packing; the surface-modified three-dimensional mesh PVDC packing comprises surface-modified three-dimensional mesh PVDC fibers and modified sulfur autotrophic particles loaded on the surface-modified three-dimensional mesh PVDC fibers.

[0007] Preferably, the upper part of the upflow reactor is provided with a first drain valve, and the drain outlet of the first drain valve is provided with a screen with an aperture of 1 to 2 mm.

[0008] Preferably, the first drain valve is connected to the first inlet at the top of the sludge thickening tank via a pipe.

[0009] Preferably, the upper part of the sludge thickening tank is provided with a second drain valve, which is connected to the second water inlet at the lower part of the water inlet mixing unit, and the bottom of the sludge thickening tank is provided with a sludge discharge pipe.

[0010] Preferably, the upflow reactor is provided with an outlet at the top.

[0011] The preparation method of the surface-modified three-dimensional mesh PVDC fiber includes:

[0012] Step S1: Blend the dried polyvinylidene chloride, hydrophilic modifier, crosslinking agent, and pore-forming agent, and premix with heat stabilizer and lubricant to obtain a premix;

[0013] Step S2: The premix is ​​melt-reacted under nitrogen protection, extruded and granulated to obtain PVDC particles, and the PVDC particles are melt-spun under nitrogen protection to obtain PVDC fibers.

[0014] Step S3: After PVDC fibers are impregnated in chitosan solution, they are crosslinked to obtain surface-modified PVDC fibers. The surface-modified PVDC fibers are then bonded with glue to obtain surface-modified three-dimensional network PVDC fibers.

[0015] Preferably, in step S1, the hydrophilic modifier is any one or more of methacrylic acid, hydroxyethyl methacrylate, and polyethylene glycol methacrylate.

[0016] Preferably, in step S1, the crosslinking agent is any one or more of dicumyl peroxide, ethylene glycol diglycidyl ether, and azobisisobutyronitrile.

[0017] Preferably, in step S1, the pore-forming agent is polyethylene glycol-6000.

[0018] Preferably, in step S1, the heat stabilizer is a calcium-zinc stabilizer.

[0019] Preferably, in step S1, the lubricant is any one or more of calcium stearate and stearic acid.

[0020] Preferably, in step S1, the premixing time is 0.5 to 1.5 hours.

[0021] Preferably, in step S1, the mass ratio of polyvinylidene chloride, hydrophilic modifier, crosslinking agent, pore-forming agent, heat stabilizer, and lubricant is 1:(0.1-0.15):(0.015-0.1):(0.05-0.1):(0.01-0.02):(0.001-0.005).

[0022] Preferably, in step S2, the temperature of the melting reaction is 120–160°C, and the melting reaction time is 1–4 hours.

[0023] Preferably, in step S2, the process of melt spinning the PVDC particles is as follows: melting the PVDC particles at 170-180°C and selecting a shaped spinneret with an aperture of 0.5-2 mm.

[0024] Preferably, in step S3, the chitosan solution is prepared by dissolving chitosan in an aqueous acetic acid solution with a volume ratio of 1% to prepare a chitosan solution with a mass-volume ratio of 5% to 10%.

[0025] Preferably, in step S3, the crosslinking method is: placing the PVDC fiber coated with chitosan solution in glutaraldehyde vapor for 30-40 minutes.

[0026] The method for preparing the modified sulfur autotrophic particles includes:

[0027] Step A1: Sulfur powder and pyrite powder are melt-mixed and loaded onto biochar, calcite powder and graphene are added and mixed, and granulated under inert gas protection to obtain sulfur autotrophic particles.

[0028] Step A2: Disperse the sulfur autotrophic particles in water, add the first coupling agent and the second coupling agent, and after the first reaction, add the enzyme solution, and after the second reaction, add glycine to block the unreacted sites. Wash to obtain the modified sulfur autotrophic particles.

[0029] Preferably, in step A1, the biochar is any one or more of bamboo charcoal, coconut shell charcoal, and walnut shell charcoal.

[0030] Preferably, in step A1, the mixing and granulation temperature is 100-120°C, and the mixing and granulation time is 20-30 minutes.

[0031] Preferably, in step A1, the mass ratio of biochar, pyrite powder, sulfur powder, calcite powder, and graphene is 1:(0.1-0.3):(0.1-0.3):(0.05-0.1):(0.0055-0.01).

[0032] Preferably, in step A2, the first coupling agent is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0033] Preferably, in step A2, the second coupling agent is N-hydroxysuccinimide.

[0034] Preferably, in step A2, the enzyme solution is a thiooxidase.

[0035] Preferably, in step A2, the concentration of glycine is (0.1-0.3) M.

[0036] Preferably, in step A2, the concentration of the enzyme solution is (1-5) mg / mL.

[0037] Preferably, in step A2, the washing solvent is PBS buffer solution.

[0038] Preferably, in step A2, the temperature of the first reaction is 4-6°C, and the reaction time is 1-2 hours.

[0039] Preferably, in step A2, the temperature of the second reaction is 4-6°C, and the reaction time is 10-12 hours.

[0040] Preferably, in step A2, the mass ratio of the sulfur autotrophic particles, water, first coupling agent, second coupling agent, enzyme solution, and glycine is 1:(1-2):(0.05-0.1):(0.005-0.01):(0.0015-0.0052):(0.0005-0.001).

[0041] The present invention also provides a method for simultaneous nitrogen and phosphorus removal wastewater treatment, implemented based on the above-mentioned simultaneous nitrogen and phosphorus removal wastewater treatment device, comprising:

[0042] Surface-modified three-dimensional network PVDC fibers were fixed inside a culture tank containing anaerobic ammonia-oxidizing bacteria. Modified sulfur autotrophic particles and sulfur autotrophic denitrifying bacteria were attached to the surface-modified three-dimensional network PVDC fibers to obtain surface-modified three-dimensional network PVDC filler.

[0043] Surface-modified three-dimensional network PVDC packing was filled into an upflow reactor;

[0044] In the influent preparation unit, the anoxic tank mixed liquor and effluent are mixed at a volume ratio of 1:(3-5) to make NH4+... + / NO3 - The molar ratio was maintained between 0.8 and 1.2, the water temperature was controlled between 10 and 35°C, and the hydraulic load was maintained between 0.6 and 1.2 m. 3 / (m 2 The water is introduced into the upflow reactor from bottom to top through the inlet distributor, with a hydraulic retention time of 1 to 2 hours.

[0045] The treated water is discharged from the top outlet of the upflow reactor and enters the sedimentation tank or filtration unit. It is discharged after the effluent test indicators meet the standards.

[0046] The backwash water is collected from the first drain valve and settled in the sludge thickening tank. The supernatant is returned to the influent mixing unit from the second drain valve, and the sludge enters the recycling unit through the sludge discharge pipe at the bottom of the sludge thickening tank.

[0047] Compared with the prior art, the beneficial effects of this application include:

[0048] (1) Based on the synergistic effect of sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation, this application can achieve efficient, low-consumption, and sustainable nitrogen and phosphorus removal in wastewater treatment plant effluent with low carbon-to-nitrogen ratio. In the process of sulfur autotrophic denitrification, sulfides act as electron donors to reduce nitrates to nitrogen gas, and sulfur is oxidized to sulfate. In the sulfate-type anaerobic ammonium oxidation process, sulfate acts as an oxidant to oxidize ammonia to nitrogen gas. At the same time, ferrous ions released from pyrite react with phosphate in wastewater to form ferrous phosphate precipitate, and the phosphate removal rate is as high as 85% or more. Iron, as an essential nutrient element for the growth and metabolism of anaerobic ammonium oxidation bacteria, can also significantly improve the activity of anaerobic ammonium oxidation bacteria.

[0049] (2) In the device for treating wastewater by synergistic action of sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation, the carrier for loading sulfur autotrophic particles is a surface-modified three-dimensional network PVDC fiber. The PVDC fiber is grafted with highly hydrophilic substances such as polyvinylpyrrolidone, acrylic acid, and hydroxyethyl methacrylate to improve its hydrophilicity and water permeability. Polyethylene glycol-6000 is used as a pore-forming agent. Polyethylene glycol-6000 has a moderate molecular weight, which can form a gradient pore structure of "micropore-macropore", which is suitable for the attachment of sulfur autotrophic bacteria and sulfate-type anaerobic ammonium oxidizing bacteria, as well as the mass transfer of substrate, without causing pore collapse due to excessive molecular weight. Finally, chitosan solution and glutaraldehyde are used to modify the surface of PVDC fiber. Through electrostatic adsorption and chemical cross-linking, the bacterial contact area is expanded, and the initial attachment rate of bacteria on the fiber surface is improved, which can reduce biological loss during the backwashing process.

[0050] (3) The modified sulfur autotrophic particles used in the device for synergistic treatment of wastewater by sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonia oxidation of the present invention first load sulfur powder and pyrite powder onto biochar, mix with calcite powder and graphene for granulation. The high specific surface area of ​​biochar can prevent the agglomeration of sulfur powder and pyrite powder and improve dispersibility. The conductivity of biochar and graphene can promote electron transfer between microorganisms and sulfur and FeS2. At the same time, sulfur oxidase is loaded on the surface of biochar to accelerate the oxidation of sulfur to sulfate by enzyme-catalyzed reaction, thereby improving treatment efficiency. Attached Figure Description

[0051] Figure 1 A schematic diagram of a device for simultaneous nitrogen and phosphorus removal wastewater treatment.

[0052] Figure 2 This is a flowchart illustrating the preparation process of surface-modified three-dimensional mesh PVDC fibers.

[0053] Figure 3 This is a flowchart of the preparation process for modified sulfur autotrophic particles.

[0054] Figure 4 This is a physical image of a surface-modified three-dimensional network PVDC filler.

[0055] Meaning of the reference numerals in the attached drawings: 1. Inlet water distribution unit; 2. Inlet water distributor; 3. Backwashing unit; 4. Upflow reactor; 5. Sludge thickening tank; 6. Surface-modified three-dimensional mesh PVDC packing; 7. First drain valve; 8. Screen; 9. First inlet; 10. Second drain valve; 11. Second inlet; 12. Sludge discharge pipe; 13. Outlet. Detailed Implementation

[0056] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0057] like Figure 1 As shown, the present invention provides a device for simultaneous nitrogen and phosphorus removal wastewater treatment, including an influent mixing unit 1, an influent distributor 2, a backwashing unit 3, an upflow reactor 4, and a sludge thickening tank 5; the influent mixing unit 1 is connected to the upflow reactor 4 through the influent distributor 2; the backwashing unit 3 is disposed between the influent distributor 2 and the surface-modified three-dimensional mesh PVDC packing 6, the surface-modified three-dimensional mesh PVDC packing 6 including surface-modified three-dimensional mesh PVDC fibers and modified sulfur autotrophic particles loaded on the surface-modified three-dimensional mesh PVDC fibers.

[0058] The upper part of the upflow reactor 4 is provided with a first drain valve 7, and the drain outlet of the first drain valve 7 is provided with a screen 8 with a pore size of 1-2 mm; the first drain valve 7 is connected to the first inlet 9 at the top of the sludge thickening tank 5 through a pipe; the upper part of the sludge thickening tank 5 is provided with a second drain valve 10, which is connected to the second inlet 11 at the bottom of the water inlet mixing unit 1, and the bottom of the sludge thickening tank 5 is provided with a sludge discharge pipe 12; the top of the upflow reactor 4 is provided with an outlet 13.

[0059] Unless otherwise specified, all reagents and equipment used in the following examples were purchased from commercial sources.

[0060] Example 1

[0061] A method for simultaneous nitrogen and phosphorus removal wastewater treatment includes the following steps:

[0062] like Figure 2 As shown, surface-modified three-dimensional network PVDC fibers were prepared:

[0063] Step S1: 100g of dried polyvinylidene chloride, 10g of methacrylic acid, 1.5g of dicumyl peroxide and 5g of polyethylene glycol-6000 are mixed together, and 1g of calcium zinc stabilizer and 0.1g of calcium stearate are added and premixed for 0.5h to obtain a premix.

[0064] Step S2: The premix is ​​melted and reacted at 160°C for 1 hour under nitrogen protection, then extruded and granulated to obtain PVDC particles. The PVDC particles are melted at 170°C under nitrogen protection, and PVDC fibers are obtained by spinning using a shaped spinneret with an aperture of 0.5 mm.

[0065] Step S3: Dissolve 50g of chitosan in 950g of acetic acid aqueous solution with a volume ratio of 1% to prepare a chitosan solution; immerse PVDC fibers in the chitosan solution for coating, and then place them in glutaraldehyde vapor for crosslinking for 30min to obtain surface-modified PVDC fibers; use glue to bond the surface-modified PVDC fibers to obtain surface-modified three-dimensional network PVDC fibers.

[0066] like Figure 3 As shown, modified sulfur autotrophic particles were prepared:

[0067] Step A1: 10g of sulfur powder and 10g of pyrite powder are melt-mixed and loaded onto 100g of bamboo charcoal powder. 5g of calcite powder and 0.55g of graphene are added. The mixture is granulated at 100℃ for 30min to obtain sulfur autotrophic particles.

[0068] Step A2: Disperse 100g of sulfur autotrophic particles in 100g of water, add 5g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.5g of N-hydroxysuccinimide, react at 4℃ for 2h, add 0.15g of sulfur oxidase at a concentration of 1mg / mL, react at 4℃ for 12h, add 0.05g of glycine at a concentration of 0.1M to block unreacted sites, wash with PBS buffer solution to obtain modified sulfur autotrophic particles.

[0069] Surface-modified three-dimensional network PVDC fibers were fixed inside a culture tank containing dispersed anaerobic ammonia-oxidizing bacteria. Modified sulfur autotrophic particles and sulfur autotrophic denitrifying bacteria were then attached to the surface-modified three-dimensional network PVDC fibers to obtain surface-modified three-dimensional network PVDC filler 6. Figure 4 As shown.

[0070] Surface-modified three-dimensional mesh PVDC packing 6 was filled into the upflow reactor 4.

[0071] In the influent mixing unit 1, the anoxic tank mixed liquor and the effluent are mixed at a volume ratio of 1:3 to make NH4+... + / NO3 - The molar ratio was maintained between 0.8 and 0.8, the water temperature was controlled at 15℃, and the hydraulic load was maintained at 0.6m. 3 / (m 2 The water is fed into the upflow reactor 4 from bottom to top through the inlet distributor 2, with a hydraulic retention time of 2 hours.

[0072] The treated water is discharged from the outlet 13 at the top of the upflow reactor 4 and enters the sedimentation tank or filtration unit. The water is discharged after the effluent test indicators meet the standards.

[0073] The backwashing unit 3 enters the upflow reactor 4 from bottom to top for rinsing. The backwash water is collected from the first drain valve 7 and settled in the sludge thickening tank 5. The supernatant is returned to the influent mixing unit 1 from the second drain valve 10. The sludge enters the recycling unit through the sludge discharge pipe 12.

[0074] Example 2

[0075] A method for simultaneous nitrogen and phosphorus removal wastewater treatment includes the following steps:

[0076] like Figure 2 As shown, surface-modified three-dimensional network PVDC fibers were prepared:

[0077] Step S1: 100g of dried polyvinylidene chloride, 15g of hydroxyethyl methacrylate, 5g of ethylene glycol diglycidyl ether, and 7.5g of polyethylene glycol-6000 are blended together, and 1.5g of calcium-zinc stabilizer and 0.3g of stearic acid are added and premixed for 1 hour to obtain a premix.

[0078] Step S2: Under nitrogen protection, the premix is ​​melted and reacted at 140°C for 4 hours, then extruded and granulated to obtain PVDC particles. The PVDC particles are then melted under nitrogen protection at 175°C, and PVDC fibers are obtained by spinning using a shaped spinneret with a 1mm aperture.

[0079] Step S3: Dissolve 75g of chitosan in 925g of acetic acid aqueous solution with a volume ratio of 1% to prepare chitosan solution; immerse PVDC fibers in chitosan solution for coating, and then place them in glutaraldehyde vapor for crosslinking for 35min to obtain surface-modified PVDC fibers; bond the surface-modified PVDC fibers with glue to obtain surface-modified three-dimensional network PVDC fibers.

[0080] like Figure 3 As shown, modified sulfur autotrophic particles were prepared:

[0081] Step A1: 20g of sulfur powder and 20g of pyrite powder are melt-mixed and loaded onto 100g of walnut shell carbon powder. 7.5g of calcite powder and 0.85g of graphene are added. The mixture is granulated at 110℃ for 25min to obtain sulfur autotrophic particles.

[0082] Step A2: Disperse 100g of sulfur autotrophic particles in 150g of water, add 7.5g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.75g of N-hydroxysuccinimide, react at 5℃ for 1.5h, add 0.36g of sulfur oxidase at a concentration of 3mg / mL, react at 5℃ for 10h, add 0.075g of glycine at a concentration of 0.2M to block unreacted sites, wash with PBS buffer solution to obtain modified sulfur autotrophic particles.

[0083] Surface-modified three-dimensional network PVDC fibers were fixed inside a culture tank containing dispersed anaerobic ammonia-oxidizing bacteria. Modified sulfur autotrophic particles and sulfur autotrophic denitrifying bacteria were then attached to the surface-modified three-dimensional network PVDC fibers to obtain surface-modified three-dimensional network PVDC filler 6. Figure 4 As shown.

[0084] Surface-modified three-dimensional mesh PVDC packing 6 was filled into the upflow reactor 4.

[0085] In the influent mixing unit 1, the anoxic tank mixed liquor and the effluent are mixed at a volume ratio of 1:4 to make NH4+... + / NO3 - The molar ratio was maintained between 1.0 and 1.0, the water temperature was controlled at 25℃, and the hydraulic load was maintained at 0.8m. 3 / (m 2 The water is fed into the upflow reactor 4 from bottom to top through the inlet distributor 2, with a hydraulic retention time of 1.5 h.

[0086] The treated water is discharged from the outlet 13 at the top of the upflow reactor 4 and enters the sedimentation tank or filtration unit. The water is discharged after the effluent test indicators meet the standards.

[0087] The backwashing unit 3 enters the upflow reactor 4 from bottom to top for rinsing. The backwash water is collected from the first drain valve 7 and settled in the sludge thickening tank 5. The supernatant is returned to the influent mixing unit 1 from the second drain valve 10. The sludge enters the recycling unit through the sludge discharge pipe 12.

[0088] Example 3

[0089] A method for simultaneous nitrogen and phosphorus removal wastewater treatment includes the following steps:

[0090] like Figure 2 As shown, surface-modified three-dimensional network PVDC fibers were prepared:

[0091] Step S1: 100g of dried polyvinylidene chloride, 10g of polyethylene glycol methacrylate, 10g of azobisisobutyronitrile, and 10g of polyethylene glycol-6000 are blended together, and 2g of calcium-zinc stabilizer and 0.5g of calcium stearate are added and premixed for 1.5h to obtain a premix.

[0092] Step S2: The premix is ​​melted and reacted at 120°C for 2 hours under nitrogen protection, then extruded and granulated to obtain PVDC particles. The PVDC particles are melted at 180°C under nitrogen protection, and PVDC fibers are obtained by spinning using a shaped spinneret with a 2mm aperture.

[0093] Step S3: Dissolve 100g of chitosan in 900g of acetic acid aqueous solution with a volume ratio of 1% to prepare chitosan solution; immerse PVDC fibers in chitosan solution for coating, and then place them in glutaraldehyde vapor for crosslinking for 40min to obtain surface-modified PVDC fibers; bond the surface-modified PVDC fibers with glue to obtain surface-modified three-dimensional network PVDC fibers.

[0094] like Figure 3 As shown, modified sulfur autotrophic particles were prepared:

[0095] Step A1: 30g of sulfur powder and 30g of pyrite powder are melt-mixed and loaded onto 100g of coconut shell carbon powder. 10g of calcite powder and 1g of graphene are added. The mixture is granulated at 120℃ for 20min to obtain sulfur autotrophic particles.

[0096] Step A2: Disperse 100g of sulfur autotrophic particles in 200g of water, add 10g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1g of N-hydroxysuccinimide, react at 6℃ for 1h, add 0.52g of sulfur oxidase at a concentration of 5mg / mL, react at 6℃ for 10h, add 0.1g of glycine at a concentration of 0.3M to block unreacted sites, wash with PBS buffer solution to obtain modified sulfur autotrophic particles.

[0097] Surface-modified three-dimensional network PVDC fibers were fixed inside a culture tank containing dispersed anaerobic ammonia-oxidizing bacteria. Modified sulfur autotrophic particles and sulfur autotrophic denitrifying bacteria were then attached to the surface-modified three-dimensional network PVDC fibers to obtain surface-modified three-dimensional network PVDC filler 6. Figure 4 As shown.

[0098] Surface-modified three-dimensional mesh PVDC packing 6 was filled into the upflow reactor 4.

[0099] In the influent mixing unit 1, the anoxic tank mixed liquor and the effluent are mixed at a volume ratio of 1:5 to make NH4+... + / NO3 - The molar ratio was maintained between 1.2 and 1.2, the water temperature was controlled at 35℃, and the hydraulic load was maintained at 1.2m. 3 / (m 2 The water is fed into the upflow reactor 4 from bottom to top through the inlet distributor 2, with a hydraulic retention time of 1 hour.

[0100] The treated water is discharged from the outlet 13 at the top of the upflow reactor 4 and enters the sedimentation tank or filtration unit. The water is discharged after the effluent test indicators meet the standards.

[0101] The backwashing unit 3 enters the upflow reactor 4 from bottom to top for rinsing. The backwash water is collected from the first drain valve 7 and settled in the sludge thickening tank 5. The supernatant is returned to the influent mixing unit 1 from the second drain valve 10. The sludge enters the recycling unit through the sludge discharge pipe 12.

[0102] Comparative Example 1

[0103] A wastewater treatment method based on simultaneous nitrogen and phosphorus removal through sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation differs from Example 3 in that polyethylene glycol methacrylate is not added in step S1.

[0104] Comparative Example 2

[0105] A wastewater treatment method based on simultaneous nitrogen and phosphorus removal through sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation, differs from Example 3 in that polyethylene glycol-6000 is not added in step S1.

[0106] Comparative Example 3

[0107] A wastewater treatment method based on simultaneous nitrogen and phosphorus removal through sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation differs from Example 3 in that the PVDC fibers in step S3 are not surface modified.

[0108] Comparative Example 4

[0109] A wastewater treatment method based on simultaneous nitrogen and phosphorus removal through sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation, differs from Example 3 in that coconut shell carbon powder is not added in step A1.

[0110] Comparative Example 5

[0111] A wastewater treatment method based on simultaneous nitrogen and phosphorus removal through sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation, differs from Example 3 in that graphene is not added in step A1.

[0112] Comparative Example 6

[0113] A wastewater treatment method based on simultaneous nitrogen and phosphorus removal through sulfur autotrophic short-cut denitrification and sulfate-type anaerobic ammonium oxidation differs from Example 3 in that the sulfur autotrophic particles are not modified with enzyme solution in step A2.

[0114] By detecting NH4 in wastewater before and after treatment + -N content (HJ 535-2009), NO3 - The removal rates of the corresponding indicators were calculated based on the content of -N (HJ / T346-2007) and the contents of total phosphorus (TP) and total nitrogen (TN) (HJ 636-2012), and the treatment effect was evaluated.

[0115] Table 1 NH4 content in wastewater influent and effluent + -N content and NH4 + -N removal rate

[0116]

[0117] Table 2 NO3 in wastewater influent and effluent - -N content and NO3 - -N removal rate

[0118]

[0119]

[0120] Table 3 Total phosphorus (TP) content and removal rate of wastewater influent and effluent

[0121] Sample number Influent TP content (mg / L) TP content in effluent (mg / L) TP removal rate (%) Example 1 1.2 0.13 89.17 Example 2 1.2 0.15 87.50 Example 3 1.2 0.12 90.00 Comparative Example 1 1.2 0.19 84.17 Comparative Example 2 1.2 0.25 79.17 Comparative Example 3 1.2 0.37 69.17 Comparative Example 4 1.2 0.18 85.00 Comparative Example 5 1.2 0.21 82.5 Comparative Example 6 1.2 0.36 70.00

[0122] Table 4 Total Nitrogen (TN) Content and Removal Rate of Wastewater Influent and Effluent

[0123] Sample number TN content in influent (mg / L) TN content in effluent (mg / L) TN removal rate (%) Example 1 30 2.57 91.43 Example 2 30 2.48 91.73 Example 3 30 2.16 92.80 Comparative Example 1 30 3.16 89.47 Comparative Example 2 30 4.26 85.80 Comparative Example 3 30 4.77 84.10 Comparative Example 4 30 3.86 87.13 Comparative Example 5 30 5.11 82.97 Comparative Example 6 30 4.25 85.83

[0124] According to Tables 1 to 4, the NH4+ in the effluent from the wastewater treated by the packing materials prepared in Examples 1 to 3 + -N content, NO3 - The NH4+ content, total phosphorus (TP) content, and total nitrogen (TN) content were all lower than those of the wastewater treated by the packing materials prepared in Comparative Examples 1 to 6. + -N, NO3 - The removal rates of -N, total phosphorus, and total nitrogen were all higher than those of the wastewater treated by the packing materials prepared in Comparative Examples 1 to 6.

[0125] In Comparative Example 1, no hydrophilic modifier was added to the PVDC fibers used in the preparation process. As a result, the PVDC fibers had poor water permeability, which hindered substrate diffusion. The hydrophobic surface was not conducive to the initial adhesion of microorganisms, resulting in slow biofilm formation and uneven biofilm thickness. The biofilm was prone to local detachment, which affected long-term stability.

[0126] In Comparative Example 2, the PVDC fibers used in the apparatus were not prepared using the pore-forming agent polyethylene glycol-6000, which was not conducive to the attachment of sulfur autotrophic bacteria and sulfate-type anaerobic ammonia-oxidizing bacteria, as well as substrate mass transfer.

[0127] In Comparative Example 3, the PVDC fibers used in the apparatus were not surface-modified using a chitosan impregnation followed by glutaraldehyde cross-linking. Unmodified PVDC fibers have poor hydrophilicity, leading to uneven distribution of sulfur autotrophic particles and reduced bacterial adhesion to the fiber surface. 2+ The release rate is unstable, and particulate matter is easily lost during backwashing.

[0128] In Comparative Example 4, the sulfur autotrophic particles filled in PVDC fibers did not use coconut shell carbon powder as a carrier to load sulfur powder and pyrite. In Comparative Example 5, the sulfur autotrophic particles filled in PVDC fibers did not contain graphene. The high specific surface area of ​​biochar can prevent the agglomeration of sulfur powder and pyrite powder and improve dispersibility. Without biochar as a carrier, when sulfur powder and pyrite are directly stacked, electron transfer relies on physical contact, which is prone to particle agglomeration or surface passivation, leading to a decrease in sulfur utilization, pH fluctuations, and the risk of by-product accumulation. Without the addition of graphene, the electron transfer efficiency is significantly reduced, which will also lead to a decrease in sulfur utilization. Biochar and graphene can synergistically improve the electron transfer rate between microorganisms and sulfur and FeS2, and accelerate the denitrification rate. In Comparative Example 6, the sulfur autotrophic particles filled in PVDC fibers did not load sulfur oxidase. The high conductivity of coconut shell carbon powder and graphene can act as an electron bridge to accelerate the extracellular electron transfer of microorganisms. At the same time, the enzymatic reaction can accelerate the oxidation of sulfur to sulfate, thereby improving the treatment efficiency. Therefore, the NH4 in the wastewater effluent treated in Comparative Examples 4 to 6 + -N content, NO3 - The content of -N, total phosphorus (TP) and total nitrogen (TN) were significantly higher than those in Examples 1 to 3.

[0129] In summary, the experiments have demonstrated that the surface-modified three-dimensional mesh PVDC fiber-loaded modified sulfur autotrophic particles prepared according to Examples 1 to 3 of this invention can effectively remove nitrogen and phosphorus in the reactor through short-cut denitrification and anaerobic ammonia oxidation, thereby improving water quality.

[0130] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A device for simultaneous nitrogen and phosphorus removal wastewater treatment, comprising an influent mixing unit (1), an influent distributor (2), a backwashing unit (3), an upflow reactor (4), and a sludge thickening tank (5); the influent mixing unit (1) is connected to the upflow reactor (4) via the influent distributor (2); the upflow reactor (4) is filled with surface-modified three-dimensional network PVDC packing (6); the backwashing unit (3) is disposed between the influent distributor (2) and the surface-modified three-dimensional network PVDC packing (6), the surface-modified three-dimensional network PVDC packing (6) comprising surface-modified three-dimensional network PVDC fibers and modified sulfur autotrophic particles loaded on the surface-modified three-dimensional network PVDC fibers; The preparation method of the surface-modified three-dimensional mesh PVDC fiber includes: Step S1: Blend the dried polyvinylidene chloride, hydrophilic modifier, crosslinking agent, and pore-forming agent, and premix with heat stabilizer and lubricant to obtain a premix; The hydrophilic modifier is any one or more of methacrylic acid, hydroxyethyl methacrylate, and polyethylene glycol methacrylate; the crosslinking agent is any one or more of dicumyl peroxide, ethylene glycol diglycidyl ether, and azobisisobutyronitrile; the porogen is polyethylene glycol-6000; the heat stabilizer is calcium zinc stabilizer; the lubricant is any one or more of calcium stearate and stearic acid; the premixing time is 0.5~1.5 h; the mass ratio of polyvinylidene chloride, hydrophilic modifier, crosslinking agent, porogen, heat stabilizer, and lubricant is 1:0.1~0.15:(0.015~0.1):(0.05~0.1):(0.01~0.02):(0.001~0.005). Step S2: The premix is ​​melted and reacted under nitrogen protection, then extruded and granulated to obtain PVDC particles. The PVDC particles are then melted and spun under nitrogen protection to obtain PVDC fibers. Step S3: After PVDC fibers are impregnated in chitosan solution, they are crosslinked to obtain surface-modified PVDC fibers. The surface-modified PVDC fibers are then bonded with glue to obtain surface-modified three-dimensional network PVDC fibers. The method for preparing the modified sulfur autotrophic particles includes: Step A1: Sulfur powder and pyrite powder are melt-mixed and loaded onto biochar, calcite powder and graphene are added and mixed, and granulated under inert gas protection to obtain sulfur autotrophic particles. The biochar is any one or more of bamboo charcoal, coconut shell charcoal, and walnut shell charcoal; the granulation temperature is 100~120℃, and the granulation time is 20~30 min; the mass ratio of biochar, pyrite powder, sulfur powder, calcite powder, and graphene is 1:(0.1~0.3):(0.1~0.3):(0.05~0.1):(0.0055~0.01). Step A2: Disperse sulfur autotrophic particles in water, add the first coupling agent and the second coupling agent, and after the first reaction, add enzyme solution, and after the second reaction, add glycine to block unreacted sites, wash, and obtain modified sulfur autotrophic particles; The first coupling agent is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; the second coupling agent is N-hydroxysuccinimide; the enzyme solution is sulfur oxidase; the concentration of glycine is (0.1~0.3) M; the concentration of the enzyme solution is (1~5) mg / mL; the washing solvent is PBS buffer solution; the temperature of the first reaction is 4~6℃, and the time of the first reaction is 1~2 h; the temperature of the second reaction is 4~6℃, and the time of the second reaction is 10~12 h; the mass ratio of sulfur autotrophic particles, water, the first coupling agent, the second coupling agent, the enzyme solution, and glycine is 1:(1~2):(0.05~0.1):(0.005~0.01):(0.0015~0.0052):(0.0005~0.001).

2. The device for simultaneous nitrogen and phosphorus removal wastewater treatment according to claim 1, characterized in that, The upper part of the upflow reactor (4) is provided with a first drain valve (7), and the drain outlet of the first drain valve (7) is provided with a screen (8) with a hole diameter of 1~2 mm; the first drain valve (7) is connected to the first inlet (9) at the top of the sludge thickening tank (5) through a pipe; the upper part of the sludge thickening tank (5) is provided with a second drain valve (10), which is connected to the second inlet (11) at the bottom of the water inlet mixing unit (1), and the bottom of the sludge thickening tank (5) is provided with a sludge discharge pipe (12); the top of the upflow reactor (4) is provided with an outlet (13).

3. The device for simultaneous nitrogen and phosphorus removal wastewater treatment according to claim 1, characterized in that, In step S2, the melting reaction temperature is 120~160℃ and the melting reaction time is 1~4 h; the PVDC particle melt spinning process is as follows: PVDC particles are melted at 170~180℃, and a shaped spinneret with an aperture of 0.5~2 mm is selected.

4. The device for simultaneous nitrogen and phosphorus removal wastewater treatment according to claim 1, characterized in that, In step S3, the chitosan solution is prepared by dissolving chitosan in an aqueous acetic acid solution with a volume ratio of 1% to prepare a chitosan solution with a mass-volume ratio of 5% to 10%; the crosslinking method is to place the PVDC fibers coated with the chitosan solution in glutaraldehyde vapor for 30 to 40 minutes.

5. A method for simultaneous nitrogen and phosphorus removal wastewater treatment, implemented based on the apparatus for simultaneous nitrogen and phosphorus removal wastewater treatment according to any one of claims 1 to 4, characterized in that, include: The surface-modified three-dimensional network PVDC fiber was fixed inside a culture tank containing anaerobic ammonia-oxidizing bacteria. Modified sulfur autotrophic particles and sulfur autotrophic denitrifying bacteria were attached to the surface-modified three-dimensional network PVDC fiber to obtain the surface-modified three-dimensional network PVDC filler (6). Surface-modified three-dimensional network PVDC filler (6) was filled into the upflow reaction (4); In the influent mixing unit (1), the anoxic tank mixed liquor and the effluent are mixed at a volume ratio of 1:(3~5) to make NH4 + / NO3 - The molar ratio was maintained between 0.8 and 1.2, the water temperature was controlled between 10 and 35°C, and the hydraulic load was maintained between 0.6 and 1.2 m. 3 / (m 2 ·h), through the inlet distributor (2), it is fed into the upflow reactor (4) from bottom to top, with a hydraulic residence time of 1~2 h; The treated water is discharged from the top outlet (13) of the upflow reactor (4) and enters the sedimentation tank or filtration unit. The water is discharged after the effluent test indicators meet the standards. The backwash water is collected from the first drain valve (7) and settled in the sludge thickening tank (5). The supernatant is returned to the inlet water mixing unit (1) from the second drain valve (10). The sludge enters the recycling unit through the sludge discharge pipe (12) at the bottom of the sludge thickening tank (5).

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