Multifunctional immobilized microbial composite material capable of synchronously removing nitrogen and phosphorus as well as preparation method and application of multifunctional immobilized microbial composite material

Abstract

The invention discloses a multifunctional immobilized microbial composite material capable of synchronously removing nitrogen and phosphorus as well as a preparation method and application of the multifunctional immobilized microbial composite material. Firstly, polyethyleneimine (PEI) is used for aminating polyacrylonitrile (PAN) fiber balls, then iron ions are loaded on the PAN fiber balls through chelation, then aerobic denitrifying bacteria are adsorbed on the PAN iron-loaded fiber balls through an adsorption method, then a layer of porous polymer film is coated through a phase inversion method, and the immobilized material is prepared. When the material is added into sewage, chelated iron ions can be rapidly combined with phosphate radicals in the sewage to form stable FePO4 crystals, so that phosphorus in the sewage is removed, meanwhile, nitrogen in the sewage is removed through the denitrification effect of the fixed aerobic denitrifying bacteria, and the dual effects of synchronous phosphorus removal and nitrogen removal are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and relates to a multifunctional immobilized microbial composite material for synchronous nitrogen and phosphorus removal, and a preparation method and application thereof. Background Art

[0002] With the continuous and stable development of the economic society, while people enjoy the convenience brought by economic development, their awareness of environmental protection has gradually increased, and they are actively participating in the practice and exploration of the green and sustainable development path. In the field of sewage treatment, achieving efficient and in-depth nitrogen and phosphorus removal is one of the important topics in the construction of ecological civilization.

[0003] PVDF (polyvinylidene fluoride) materials without added pore-forming agents usually have a relatively low porosity, which significantly limits the diffusion efficiency of nutrients and oxygen to microorganisms, and at the same time hinders the effective discharge of metabolites. This mass transfer limitation not only reduces the activity and metabolic efficiency of microorganisms, but also may cause the activity of microorganisms to decline or even die due to insufficient nutrients and oxygen. In addition, the low porosity will lead to the accumulation of metabolites inside the material, increasing the internal pressure, and then destroying the structure of the PVDF material, affecting the long-term stability of the immobilization system. By adding a pore-forming agent to the PVDF casting solution, the diffusion efficiency of nutrients and oxygen to microorganisms can be improved, so as to achieve the effect of efficient degradation of wastewater by microorganisms.

[0004] Phosphorus in sewage mainly exists in the forms of phosphate, polyphosphate and organic phosphorus. At present, the main phosphorus removal technologies include chemical precipitation method, adsorption method, biological treatment method and membrane treatment method. Among them, the chemical precipitation method has received extensive attention due to its simple operation and high selectivity, but there is a problem of relatively high cost. Iron is a metal element widely present in nature. Due to its strong specific binding effect on phosphate, it has been widely studied in the field of phosphorus removal and has a certain promoting effect on the growth and metabolism of microorganisms.

[0005] Combining the microbial sewage treatment technology with the immobilization technology can immobilize microorganisms on the carrier, provide a relatively ideal living environment for them, enhance their shock resistance, and is conducive to improving the growth rate and denitrification rate of microorganisms, so as to effectively remove nitrogen in sewage.

[0006] At present, the chemical phosphorus removal process is generally set downstream of the microbial denitrification reactor, which has problems such as large equipment floor area and high construction cost; by functionally compounding iron-based materials with microbial immobilization carriers, a composite carrier system with a porous structure is constructed. The carrier optimizes its pore size distribution and porosity through surface pore-forming technology, enabling oxygen in the air to effectively diffuse into the interior of the carrier through the porous outer shell, providing sufficient electron acceptors for microorganisms. In this system, the iron material strengthens the phosphorus removal effect through the iron-phosphorus coprecipitation mechanism. This iron-biological composite system realizes the synchronous and efficient removal of nitrogen and phosphorus pollutants in sewage through the synergistic effect of oxygen mass transfer optimization and microbial metabolism, significantly improving the sewage treatment efficiency. Summary of the Invention

[0007] Aiming at the problem that the chemical phosphorus removal technology and the microbial denitrification technology cannot be combined on the immobilization carrier at present, the present invention provides a multifunctional immobilized microorganism composite material for synchronous denitrification and phosphorus removal, its preparation method and application.

[0008] The present invention first amines polyacrylonitrile (PAN) fiber balls with polyethyleneimine (PEI), secondly loads iron ions on the PAN fiber balls through chelation, then adsorbs aerobic denitrifying bacteria on the iron-loaded PAN fiber balls by adsorption method, and then coats a porous polymer film by phase inversion method to obtain the immobilized material. Among them, the porous polymer film optimizes the pore-forming characteristics of the carrier outer shell by adding a pore-forming agent to the polyvinylidene fluoride (PVDF) casting solution.

[0009] The immobilized material prepared by the present invention can not only form FePO4 crystals with phosphate radicals in sewage through chelated iron ions, but the immobilized aerobic denitrifying bacteria can utilize the oxygen gradient microenvironment formed inside the carrier to efficiently remove nitrogen pollutants in sewage through denitrification under aerobic conditions, so as to achieve the effect of synchronous and efficient denitrification and phosphorus removal.

[0010] The technical solution of the present invention is as follows:

[0011] A multifunctional immobilized microorganism composite material for synchronous denitrification and phosphorus removal: composed of a polyacrylonitrile iron-loaded fiber ball core, aerobic denitrifying bacteria, and a porous polymer film outer layer;

[0012] The polyacrylonitrile iron-loaded fiber ball core is obtained by aminating polyacrylonitrile fiber balls and then loading iron ions through chelation; after the obtained polyacrylonitrile iron-loaded fiber ball core adsorbs aerobic denitrifying bacteria, it is coated with a porous polymer film to obtain the multifunctional immobilized microorganism composite material for synchronous denitrification and phosphorus removal;

[0013] The aerobic denitrifying bacteria can be obtained by regular commercial purchase;

[0014] The outer layer of the porous polymer film is formed by a phase inversion method from a polyvinylidene fluoride casting solution added with a pore-forming agent.

[0015] The preparation method of the multifunctional immobilized microorganism composite material for synchronous denitrification and phosphorus removal according to the present invention comprises the following steps:

[0016] (1) Preparation of aminated polyacrylonitrile fiber balls

[0017] Put polyacrylonitrile fiber balls, polyethyleneimine, and deionized water into a reaction kettle for mixing, react at 120 - 180 °C for 4 - 8 h, cool to room temperature, wash (with deionized water), and dry (40 - 80 °C) to obtain aminated polyacrylonitrile fiber balls;

[0018] The feeding ratio of polyacrylonitrile fiber balls, polyethyleneimine, and deionized water is 1 - 3 g : 1 - 5 g : 10 - 30 mL;

[0019] The polyacrylonitrile fiber balls are obtained as follows: Put polyacrylonitrile fibers into a pulverizer, pulverize them into balls under the conditions of a rated power of 1400 W and a rotation speed of 34000 r / min, then wash with deionized water and dry to obtain them;

[0020] (2) Preparation of polyacrylonitrile iron-loaded fiber balls

[0021] Put the aminated polyacrylonitrile fiber balls obtained in step (1) into an FeCl3 solution, stir at room temperature for 1 - 3 h, then wash (with deionized water) and dry (40 - 80 °C) to obtain polyacrylonitrile iron-loaded fiber balls;

[0022] Preferably, the concentration of the FeCl3 solution is 0.5 - 2 mol / L;

[0023] (3) Adsorption of aerobic denitrifying bacteria

[0024] Put the polyacrylonitrile iron-loaded fiber balls obtained in step (2) into an aerobic denitrifying bacteria solution, and carry out adsorption on a shaker for 3 - 5 h to obtain polyacrylonitrile iron-loaded fiber balls adsorbed with aerobic denitrifying bacteria;

[0025] The aerobic denitrifying bacteria solution is obtained as follows: Use a BTB medium to culture aerobic denitrifying bacteria to the logarithmic phase, centrifuge to obtain an aerobic denitrifying bacteria precipitate, and then resuspend it with simulated wastewater to obtain an aerobic denitrifying bacteria solution;

[0026] The composition of the BTB medium is as follows: KNO3 1000 mg / L, C4H4Na3O2 (succinic acid) 1000 mg / L, KH2PO4 1000 mg / L, FeSO4·7H2O 50 mg / L, CaCl2 200 mg / L, MgSO4·7H2O 1000 mg / L, and the solvent is deionized water;

[0027] The composition of the simulated wastewater is as follows: 35000 mg / L of NaCl, 1000 mg / L of KNO3, 5000 mg / L of C4H4Na3O2 (succinic acid), 1000 mg / L of KH2PO4, 50 mg / L of FeSO4·7H2O, 200 mg / L of CaCl2, 1000 mg / L of MgSO4·7H2O, and the solvent is deionized water;

[0028] Preferably, the concentration of the aerobic denitrifying bacteria solution is 1000 - 3000 mg / L;

[0029] (4) Prepare the casting solution

[0030] Dissolve polyvinylidene fluoride and the pore-forming agent in an organic solvent to obtain the casting solution;

[0031] Preferably, in the casting solution, the mass fraction of polyvinylidene fluoride is 10 - 18%, and the mass fraction of the pore-forming agent is 1 - 5%;

[0032] The pore-forming agent is selected from one or more of PEG, F127, and PVP;

[0033] The organic solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone;

[0034] (5) Coating the porous polymer film

[0035] Coat the casting solution obtained in step (4) on the polyacrylonitrile iron-loaded fiber balls adsorbed with aerobic denitrifying bacteria obtained in step (3), and then place it in deionized water for phase inversion to form a porous polymer film, thereby obtaining the multifunctional immobilized microbial composite material for synchronous nitrogen and phosphorus removal.

[0036] The multifunctional immobilized microbial composite material for synchronous nitrogen and phosphorus removal of the present invention can be used for removing nitrogen and phosphorus pollutants in sewage.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The core of the multifunctional immobilized microbial composite material prepared by the present invention uses PAN fibers, which have chelating ability for metal ions after amination modification, and thus show a high adsorption capacity for iron ions. The chelated iron ions can quickly combine with phosphate radicals in the water body to form stable FePO4 crystals, having high phosphorus removal ability; at the same time, the immobilized aerobic denitrifying bacteria remove nitrogen in the sewage through denitrification.

[0039] The multifunctional immobilized microbial composite material prepared by the present invention can not only form FePO4 crystals with phosphate ions in sewage through chelated iron ions to remove phosphorus from sewage. Moreover, oxygen diffuses into the carrier core through the efficient mass transfer of the porous outer shell, providing sufficient electron acceptors for aerobic denitrifying bacteria, enabling them to convert nitrogen pollutants in sewage into nitrogen gas and remove them through denitrification under aerobic conditions. This porous structure not only optimizes the mass transfer efficiency of oxygen but also provides a stable attachment environment for microorganisms, promoting the enrichment and metabolic activity of aerobic denitrifying bacteria.

[0040] Through the dual effects of phosphorus removal by the material and nitrogen removal by microorganisms, the present invention realizes the efficient synchronous removal of nitrogen and phosphorus pollutants in sewage, significantly improving the sewage treatment efficiency and stability. Description of the Drawings

[0041] Figure 1 : Schematic diagram for the preparation of iron-loaded PAN fiber balls.

[0042] Figure 2 : Degradation effects of the multifunctional immobilized microbial composite material in Experimental Example 1 and Comparative Examples 1-4 on TN in domestic sewage from a certain city in Sichuan.

[0043] Figure 3 : Degradation effects of the multifunctional immobilized microbial composite material in Experimental Example 1 and Comparative Examples 1-4 on TP in domestic sewage from a certain city in Sichuan.

[0044] Figure 4 : Degradation effects of the multifunctional immobilized microbial composite material in Experimental Example 1 and Comparative Examples 1-4 on TN in domestic sewage from a certain rural area.

[0045] Figure 5 : Degradation effects of the multifunctional immobilized microbial composite material in Experimental Example 1 and Comparative Examples 1-4 on TP in domestic sewage from a certain rural area. Detailed Embodiments

[0046] The present invention will be further described below through specific examples, but the protection scope of the present invention is not limited thereto.

[0047] In the following examples,

[0048] Polyacrylonitrile (PAN) fibers were purchased from Huixiang Fibers; polyethyleneimine (PEI) was purchased from Aladdin; polyvinylidene fluoride (PVDF) was purchased from Aladdin; porogen F127 was purchased from Merck; aerobic denitrifying bacteria were purchased from Qiang Microorganisms.

[0049] Example 1

[0050] Step 1: Preparation of iron-loaded PAN fiber balls

[0051] Step 1-1: Preparation of pure polyacrylonitrile (PAN) fiber balls

[0052] Take the PAN fiber to be processed, place it in a pulverizer, and pulverize it into balls under the conditions of a rated power of 1400 W and a rotation speed of 34000 r / min. First, wash it several times with deionized water, and then dry it to obtain pure PAN fiber balls.

[0053] Step 1-2: Preparation of aminated PAN fiber balls

[0054] Mix 1 g of dried PAN fiber balls with 2 g of polyethyleneimine (PEI) and 25 ml of deionized water and put them into a reaction kettle. React at 150 °C for 6 h. After the reaction is completed and cooled to room temperature, wash the fiber balls with deionized water, and then dry them overnight in an oven at 60 °C to obtain aminated PAN fiber balls.

[0055] Step 1-3: Preparation of PAN fiber balls loaded with iron

[0056] Place the aminated PAN fiber balls in a 1 mol / L FeCl3 solution, stir at room temperature for 1.5 h, then wash the iron ions adhering to the surface of the fiber balls with deionized water, and finally dry them overnight in an oven at 60 °C to obtain PAN fiber balls loaded with iron.

[0057] Step 2: Immobilization of aerobic denitrifying bacteria

[0058] Step 2-1: Adsorption of aerobic denitrifying bacteria by PAN fiber balls loaded with iron

[0059] Use BTB medium to culture aerobic denitrifying bacteria to the logarithmic phase, separate them using a centrifuge to obtain aerobic denitrifying bacteria precipitate, and then resuspend them with simulated wastewater to obtain an aerobic denitrifying bacteria solution with a concentration of 2000 mg / L. Place the PAN fiber balls loaded with iron in the aerobic denitrifying bacteria solution and adsorb them on a shaker for 4 h to obtain PAN fiber balls loaded with iron adsorbed with aerobic denitrifying bacteria.

[0060] The composition of BTB medium is as follows: KNO3 1000 mg / L, C4H4Na3O2 (succinic acid) 1000 mg / L, KH2PO4 1000 mg / L, FeSO4·7H2O 50 mg / L, CaCl2 200 mg / L, MgSO4·7H2O 1000 mg / L, and the solvent is deionized water.

[0061] The composition of simulated wastewater is as follows: NaCl 35000 mg / L, KNO3 1000 mg / L, C4H4Na3O2 (succinic acid) 5000 mg / L, KH2PO4 1000 mg / L, FeSO4·7H2O 50 mg / L, CaCl2 200 mg / L, MgSO4·7H2O 1000 mg / L, and the solvent is deionized water.

[0062] Step 2-2: Preparation of Porous Polymer Casting Solution

[0063] Weigh polyvinylidene fluoride (PVDF) and porogen F127, dissolve them in N,N-dimethylformamide, and place them on a magnetic stirrer for stirring until PVDF and porogen F127 are completely dissolved, obtaining a PVDF casting solution added with porogen. Among them, the mass fraction of PVDF is 12%, and the mass fraction of porogen F127 is 2%.

[0064] Step 2-3: Immobilization of Aerobic Denitrifying Bacteria

[0065] Coat the PVDF casting solution on the PAN iron-loaded fiber balls adsorbed with aerobic denitrifying bacteria, and then place them in deionized water for phase inversion for 2 h to form a porous polymer film on the PAN iron-loaded fiber balls, obtaining the PAN iron-loaded fiber balls immobilized with aerobic denitrifying bacteria.

[0066] Comparative Example 1

[0067] Compared with Example 1, the PAN iron-loaded fiber balls with aerobic denitrifying bacteria adsorbed on the inner layer are changed to pure PAN fiber balls. The specific operation steps are as follows:

[0068] Take the PAN fibers to be treated, place them in a crusher, and crush them into balls under the conditions of a rated power of 1400 W and a rotation speed of 34000 r / min; after washing and drying with deionized water, pure PAN fiber balls are obtained.

[0069] Comparative Example 2

[0070] Compared with Example 1, the concentration of FeCl3 solution is 0.5 mol / L. The specific operation steps are as follows:

[0071] Place the aminated PAN fiber balls in a 0.5 mol / L FeCl3 solution, stir at room temperature for 1.5 h, then wash the iron ions adhered to the surface of the fiber balls with deionized water, and finally dry them overnight in an oven at 60 °C to obtain PAN iron-loaded fiber balls.

[0072] Comparative Example 3

[0073] Compared with Example 1, the concentration of the aerobic denitrifying bacteria solution is 1000 mg / L, and the composition and concentration of the BTB medium are the same as those in Example 1. The specific operation steps are as follows:

[0074] Use the BTB medium to culture the aerobic denitrifying bacteria to the logarithmic phase, separate them using a centrifuge to obtain the aerobic denitrifying bacteria precipitate, and then resuspend it with simulated wastewater to obtain an aerobic denitrifying bacteria solution with a concentration of 1000 mg / L.

[0075] Comparative Example 4

[0076] Compared with Example 1, no pore-forming agent is added to the PVDF casting solution, and the specific operation steps are as follows:

[0077] Weigh PVDF according to a mass fraction of 12%, add the solvent N,N-dimethylacetamide, stir magnetically at 50 °C, and after complete dissolution, let the casting solution stand for 12 h to remove bubbles.

[0078] Application Example 1: Degradation of domestic sewage from a certain city in Sichuan by a multifunctional immobilized microorganism composite material for simultaneous nitrogen and phosphorus removal

[0079] Put 25 g of the prepared multifunctional immobilized microorganism composite material into 500 mL of sewage, select Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 for experiments, place it on a shaker and oscillate at a rotation speed of 120 r / min, set three parallel experiments, measure the concentrations of TN and TP in the wastewater every 12 h and calculate the degradation rate, and the experimental results are as Figure 2 、 Figure 3 shown. The concentrations of TN and TP in the domestic sewage from a certain city in Sichuan are shown in Table 1, and the concentrations of TN and TP in the sewage after 48 h of degradation by the multifunctional immobilized microorganism composite material are shown in Table 2.

[0080] Application Example 2: Degradation of domestic sewage from a certain rural area by a multifunctional immobilized microorganism composite material for simultaneous nitrogen and phosphorus removal

[0081] Put 25 g of the prepared multifunctional immobilized microorganism composite material into 500 mL of domestic sewage, select Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 for experiments, place it on a shaker and oscillate at a rotation speed of 120 r / min, set three parallel experiments, measure the concentrations of TN and TP in the wastewater every 12 h and calculate the degradation rate, and the experimental results are as Figure 4 、 Figure 5 shown. The concentrations of TN and TP in the rural domestic sewage are shown in Table 3, and the concentrations of TN and TP in the rural domestic sewage after 48 h of degradation by the multifunctional immobilized microorganism composite material are shown in Table 4.

[0082] Table 1: Initial TN and TP concentrations of domestic sewage from a certain city in Sichuan

[0083] Item TN (mg / L) TP (mg / L) Concentration 17.3 2.68

[0084] Table 2: TN and TP concentrations of domestic sewage from a certain city in Sichuan after 48 h of degradation by the multifunctional immobilized microorganism composite material

[0085] Item TN (mg / L) TP (mg / L) Example 1 3.01 0.47 Comparative Example 1 3.24 1.52 Comparative Example 2 3.75 0.92 Comparative Example 3 6.33 0.98 Comparative Example 4 8.22 1.27

[0086] Table 3: Initial TN and TP concentrations of domestic sewage from a certain rural area

[0087] Item TN (mg / L) TP (mg / L) Concentration 14.51 1.73

[0088] Table 4: Concentrations of TN and TP in a certain rural domestic sewage after 48 h of degradation by the multifunctional immobilized microbial composite material

[0089] Item TN (mg / L) TP (mg / L) Example 1 3.66 0.22 Comparative Example 1 3.45 0.88 Comparative Example 2 3.93 0.78 Comparative Example 3 7.17 0.44 Comparative Example 4 9.45 0.65

[0090] It can be seen from the above results that, compared with Example 1: the PAN fiber balls in Comparative Example 1 were unmodified, and the degradation rate of TP decreased because the inner core PAN fiber balls did not chelate iron ions; after the concentration of the FeCl3 solution in Comparative Example 2 was changed to 0.5 mol / L, the degradation rate of TP decreased because the amount of iron ions chelated by the inner core PAN fiber balls decreased, but it was still higher than that in Comparative Example 1; after the concentration of the aerobic denitrifying bacteria solution in Comparative Example 3 was 1000 mg / L, the degradation rate of TN decreased because the concentration of the loaded aerobic denitrifying bacteria decreased; in Comparative Example 4, due to the absence of a pore-forming agent in the PVDF casting solution, the mass transfer resistance increased, the oxygen diffusion was limited, and the denitrifying activity of the aerobic denitrifying bacteria decreased, resulting in a significant decrease in the degradation rate of TN.

Claims

1. A multifunctional immobilized microorganism composite material for synchronous nitrogen and phosphorus removal, characterized in that, It consists of a polyacrylonitrile-supported iron fiber ball core, aerobic denitrifying bacteria, and a porous polymer film outer layer; The polyacrylonitrile-supported iron fiber ball core is obtained by aminating polyacrylonitrile fiber balls and then loading iron ions through chelation; after the obtained polyacrylonitrile-supported iron fiber ball core adsorbs aerobic denitrifying bacteria, it is then coated with a porous polymer film to obtain the multifunctional immobilized microbial composite material for synchronous nitrogen and phosphorus removal; The porous polymer film outer layer is formed by the phase inversion method from a polyvinylidene fluoride casting solution added with a pore-forming agent.

2. The preparation method of the multifunctional immobilized microorganism composite material for synchronous nitrogen and phosphorus removal according to claim 1, characterized in that It includes the following steps: (1) Prepare aminated polyacrylonitrile fiber balls Add polyacrylonitrile fiber balls, polyethyleneimine, and deionized water into a reaction kettle and mix them. React at 120 - 180 °C for 4 - 8 h, cool to room temperature, wash, and dry to obtain aminated polyacrylonitrile fiber balls; (2) Prepare polyacrylonitrile-supported iron fiber balls Place the aminated polyacrylonitrile fiber balls obtained in step (1) into an FeCl3 solution, stir at room temperature for 1 - 3 h, then wash and dry to obtain polyacrylonitrile-supported iron fiber balls; (3) Adsorb aerobic denitrifying bacteria Place the polyacrylonitrile-supported iron fiber balls obtained in step (2) into an aerobic denitrifying bacteria solution, and adsorb on a shaker for 3 - 5 h to obtain polyacrylonitrile-supported iron fiber balls adsorbed with aerobic denitrifying bacteria; (4) Prepare a casting solution Dissolve polyvinylidene fluoride and a pore-forming agent in an organic solvent to obtain a casting solution; The pore-forming agent is selected from one or more of PEG, F127, and PVP; The organic solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; (5) Coat with a porous polymer film Coat the casting solution obtained in step (4) on the polyacrylonitrile-supported iron fiber balls adsorbed with aerobic denitrifying bacteria obtained in step (3), and then place it into deionized water for phase inversion to form a porous polymer film, obtaining the multifunctional immobilized microbial composite material for synchronous nitrogen and phosphorus removal.

3. The preparation method according to claim 2, characterized in that, In step (1), the polyacrylonitrile fiber balls are obtained as follows: Place polyacrylonitrile fibers in a pulverizer, pulverize them into balls under the conditions of a rated power of 1400 W and a rotation speed of 34000 r / min, and then wash and dry them with deionized water to obtain them.

4. The preparation method according to claim 2, characterized in that, In step (1), the feeding ratio of polyacrylonitrile fiber balls, polyethyleneimine, and deionized water is 1 - 3 g : 1 - 5 g : 10 - 30 mL.

5. The preparation method according to claim 2, characterized in that, In step (2), the concentration of the FeCl3 solution is 0.5 - 2 mol / L.

6. The preparation method according to claim 2, characterized in that, In step (3), the aerobic denitrifying bacteria solution is obtained as follows: Use a BTB medium to culture aerobic denitrifying bacteria to the logarithmic phase, centrifuge to obtain an aerobic denitrifying bacteria precipitate, and then resuspend it with simulated wastewater to obtain an aerobic denitrifying bacteria solution; The composition of the BTB medium is as follows: KNO3 1000 mg / L, C4H4Na3O2 1000 mg / L, KH2PO4 1000 mg / L, FeSO4·7H2O 50 mg / L, CaCl2 200 mg / L, MgSO4·7H2O 1000 mg / L, and the solvent is deionized water; The composition of the simulated wastewater is as follows: 35000 mg / L of NaCl, 1000 mg / L of KNO3, 5000 mg / L of C4H4Na3O2, 1000 mg / L of KH2PO4, 50 mg / L of FeSO4·7H2O, 200 mg / L of CaCl2, 1000 mg / L of MgSO4·7H2O, and the solvent is deionized water.

7. The preparation method according to claim 2, characterized in that, In step (3), the concentration of the aerobic denitrifying bacteria solution is 1000 - 3000 mg / L.

8. The preparation method according to claim 2, characterized in that, In the casting solution of step (4), the mass fraction of polyvinylidene fluoride is 10 - 18%, and the mass fraction of the pore-forming agent is 1 - 5%.

9. The application of the multifunctional immobilized microorganism composite material for synchronous nitrogen and phosphorus removal as claimed in claim 1 in the removal of nitrogen and phosphorus pollutants in sewage.

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