A method for preparing a redox-active polymer and a method for preparing a biological carrier and applications thereof

Abstract

The invention discloses a method for preparing a redox-active polymer and a method for preparing a bio-carrier and its application. The steps for preparing the polymer are as follows: after mixing meta-cresol, isoquinoline, toluene, 2,6-diaminoanthraquinone and pyromellitic dianhydride for reaction, the solid is placed in boiling DMF, and the mixture is repeatedly stirred and filtered until the washing liquid is colorless; the product is washed and dried to obtain a product. The polymer carrier is soaked in a coating liquid containing the above polymer, and then soaked in a sodium hydroxide solution to obtain a bio-carrier. According to C DON , C TDN and C COD Data, select different loading amounts of biological carriers to construct denitrification bioreactors, and operate denitrification bioreactors to achieve the reduction control of dissolved organic nitrogen in sewage. This method can effectively enhance the utilization of dissolved organic nitrogen by microorganisms and reduce the production of dissolved organic nitrogen derived from microorganisms, reduce the organic nitrogen concentration level in sewage, and improve the effluent quality of sewage treatment plants.

Description

Technical Field

[0001] The invention relates to a redox active polymer and its preparation and application, in particular to a method for preparing a redox active polymer and its biological carrier and its application in the reduction control of soluble organic nitrogen in sewage. Background Art

[0002] At present, the limit value of total nitrogen in the effluent discharge standards of most sewage treatment plants is already lower than 10 mg / L. The total nitrogen in the effluent of sewage treatment plants includes dissolved inorganic nitrogen and dissolved organic nitrogen. Most of the dissolved inorganic nitrogen is effectively removed by the tertiary denitrification unit, resulting in dissolved organic nitrogen eventually becoming a non-negligible part of the total nitrogen in the effluent. It is reported that the dissolved organic nitrogen in low total nitrogen effluent can account for 20-85% of the total dissolved nitrogen. Not only that, compared with dissolved inorganic nitrogen, the eutrophication potential of dissolved organic nitrogen is even higher. Therefore, controlling the level of dissolved organic nitrogen in sewage to reduce the nitrogen concentration and eutrophication risk of effluent discharge is of great significance to achieving sewage discharge standards and ecological security.

[0003] There are two main sources of dissolved organic nitrogen in sewage. One is the dissolved organic nitrogen contained in the influent that is difficult to be utilized by microorganisms. The other is the microbially derived dissolved organic nitrogen produced by microbial utilization and transformation during the biological treatment process. The latter is often an important component of dissolved organic nitrogen in sewage, accounting for more than 50% of the total dissolved nitrogen. Although many sewage treatment plants currently use a three-stage denitrification process to meet strict nitrogen emission standards, dissolved organic nitrogen is difficult to remove in conventional biological treatment processes. Redox-active substances can improve the removal effect of biological systems on difficult-to-degrade nitrogen-containing organic compounds and can regulate the potential of microbial nitrogen metabolism. Therefore, they have great application potential in achieving the reduction control of dissolved organic nitrogen in sewage.

[0004] Chinese patent CN116605989A discloses a device and method for deep denitrification of urban sewage by coupling redox mediator with in-situ fermentation and enhanced denitrification. The method achieves deep denitrification by adding redox mediator sodium anthraquinone-2-sulfonate to the anoxic zone and coupling the microorganisms on the polyurethane biological carrier to carry out denitrification. However, the method requires continuous addition of sodium anthraquinone-2-sulfonate to the anoxic zone, which has high requirements for dosage control and relatively expensive operating costs. In addition, due to the loss of sodium anthraquinone-2-sulfonate, the method fails to fully utilize the regulatory effect of the redox mediator on the microorganisms on the biological carrier to achieve the reduction control of dissolved organic nitrogen. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for preparing a redox-active polymer, and to solve the problem of how to prepare a polymer that can promote the degradation of soluble organic nitrogen in sewage; the second purpose of the present invention is to propose a method for preparing a biological carrier using a redox-active polymer, and to solve the problem of how to immobilize the redox-active polymer. The third purpose of the present invention is to provide an application of a biological carrier in the reduction control of soluble organic nitrogen in sewage, and to solve the problem of how to use the biological carrier to degrade soluble organic nitrogen in sewage.

[0006] Technical solution: The method for preparing a redox-active polymer according to the present invention comprises the following steps:

[0007] (1) adding a mixed solid of 2,6-diaminoanthraquinone and pyromellitic acid dianhydride to a mixed solution of m-cresol, isoquinoline and toluene to obtain a mixed reaction system; the solid-liquid ratio of the mixed solid to the mixed liquid is: 1.30-4.57 g: 3.43-12.1 mL; the volume ratio of the m-cresol, isoquinoline and toluene is 20-70: 0.3-1: 14-50; the molar ratio of the 2,6-diaminoanthraquinone and pyromellitic acid dianhydride is 1-2: 1-2;

[0008] (2) heating the mixed reaction system to react, cooling after the reaction, filtering, taking the solid powder and placing it in boiling N,N-dimethylformamide, repeating the stirring and filtering procedures until the washing liquid is colorless; the heating reaction conditions are heating at 150-250° C. for 3-7 hours;

[0009] (3) The solid powder is then washed with methanol and propanol and dried to obtain a redox active polymer.

[0010] Preferably, in step (1), the volume ratio of m-cresol, isoquinoline and toluene is 70:1:50; the molar ratio of 2,6-diaminoanthraquinone and pyromellitic dianhydride is 1:1; in step (2), the heating reaction condition is heating at 200°C for 5 hours; in step (3), the drying method is to air-dry the washed solid powder and then further dry it in a vacuum drying oven.

[0011] The present invention prepares a redox active polymer according to the preparation method, and the redox active polymer utilizes the abundant redox sites of the redox active polymer to promote the extracellular electron transfer rate of microorganisms, enhance the utilization of exogenous soluble organic nitrogen and reduce the production of microbial derived soluble organic nitrogen.

[0012] The present invention prepares a biological carrier based on the above-mentioned redox active polymer, and the preparation method of the biological carrier comprises the following steps:

[0013] (1) soaking the polymer carrier in a sodium hydroxide solution, then taking it out, cleaning it and drying it;

[0014] (2) adding a redox active polymer to a mixed solution of N,N-dimethylamide and diethylenetriamine and ultrasonically treating the mixed solution to obtain a coating solution;

[0015] (3) transferring the polymer carrier dried in step (1) to a coating solution for immersion, transferring the polymer carrier after immersion in the coating solution to a sodium hydroxide solution for immersion, taking out the polymer carrier after immersion, washing and drying it to obtain a biological carrier.

[0016] The present invention fixes the redox active polymer load on the polymer carrier, which not only enables the redox active polymer on the surface to fully contact the microorganisms and sewage, but also effectively avoids the problem of easy loss of redox active substances in sewage, and is also beneficial to the subsequent filling operation in the denitrification bed.

[0017] Preferably, in step (1), the polymer carrier has a porosity of 95-98% and an effective specific surface area of ​​not less than 9000 m 2 / m 3 , specific gravity is 1.0-1.2g / cm 3 The polyurethane carrier, the concentration of sodium hydroxide solution is 1-2 mol / L, and the soaking time is 1-3h;

[0018] Preferably, in step (2), the solid-liquid ratio of the redox-active polymer to the mixed solution is 0.1-10 g / 1L, and the volume ratio of N,N-dimethylamide to diethylenetriamine in the mixed solution is 90-110:1.

[0019] Preferably, in step (3), the method of soaking in the coating solution is: adjusting the pH to 9-11 with sodium hydroxide solution and soaking at 20-40°C for 0.5-1.5h; the method of soaking in the sodium hydroxide solution is: soaking in 2M sodium hydroxide solution at 60-80°C for 0.5-1.5h.

[0020] The present invention further applies the above-mentioned biological carrier to the reduction control of dissolved organic nitrogen in sewage.

[0021] Furthermore, the method for reducing the amount of dissolved organic nitrogen in sewage comprises the following steps:

[0022] (1) Determine the concentration of dissolved organic nitrogen, dissolved total nitrogen and chemical oxygen demand in sewage respectively;

[0023] (2) Based on the data of dissolved organic nitrogen concentration, dissolved total nitrogen concentration and chemical oxygen demand, bio-carriers with different redox active polymer loadings were selected to construct denitrification bioreactors;

[0024] (3) Operate the denitrification bioreactor to achieve the reduction control of dissolved organic nitrogen in sewage.

[0025] Preferably, in step (1), the concentration of dissolved organic nitrogen in the sewage is obtained by measuring and calculating the concentration difference between dissolved total nitrogen and dissolved inorganic nitrogen.

[0026] Preferably, in step (2), the biocarriers with different redox-active polymer loadings include PUF@PIAQ 低 PUF@PIAQ 中 and PUF@PIAQ 高 , the PUF@PIAQ 低 PUF@PIAQ 中 and PUF@PIAQ 高 The mass ratio of redox active polymer to polymer carrier is PUF@PIAQ 低 <PUF@PIAQ 中 <PUF@PIAQ 高 ; The denitrification bioreactor comprises a denitrification bed, a raw water feed subsystem and a backwash subsystem; The method for selecting bio-carriers with different redox active polymer loading amounts to construct a denitrification bioreactor is:

[0027] When the COD / TDN concentration in sewage is >4, use PUF@PIAQ 低 Filling denitrification beds;

[0028] When the chemical oxygen demand / dissolved total nitrogen concentration in the sewage is ≤4 and the dissolved organic nitrogen concentration / dissolved total nitrogen concentration is less than 10%, PUF@PIAQ is used. 中 Filling denitrification beds;

[0029] When the chemical oxygen demand / dissolved total nitrogen concentration in the sewage is ≤4 and the dissolved organic nitrogen concentration / dissolved total nitrogen concentration is greater than 10%, PUF@PIAQ is used. 高 Fill the denitrification bed.

[0030] In some embodiments, the PUF@PIAQ 低 PUF@PIAQ 中 and PUF@PIAQ 高 The mass ratios of redox-active polymer and polymer carrier were 1:10, 1:5 and 2:5, respectively.

[0031] Preferably, in step (3), the operation process of the denitrification bioreactor is to pass the sewage through the denitrification bioreactor at a flow rate of at least 2.0 BV / h, and the backwashing mode is air-water backwashing; the chemical oxygen demand / dissolved total nitrogen concentration in the sewage should be not less than 2. If the chemical oxygen demand in the sewage is insufficient, an appropriate amount of sodium acetate is preferably added as an external carbon source. Sodium acetate is the most commonly used organic carbon source in existing sewage treatment plants, and has the advantages of being easy to store, easy to be used by microorganisms, and having a good denitrification effect.

[0032] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0033] (1) The redox active polymer in the present invention has abundant redox sites, which can promote the extracellular electron transfer system of microorganisms and regulate the nitrogen metabolism pathway, and can effectively improve the degradation effect of microorganisms on soluble organic nitrogen in sewage.

[0034] (2) The present invention fixes a redox-active polymer on a polymer carrier to prepare a bio-carrier, which is a new type of bio-carrier suitable for upgrading and transforming existing sewage denitrification bioreactors and has the advantages of being difficult to lose and being reusable.

[0035] (3) The present invention provides a method for reducing the amount of soluble organic nitrogen in sewage. Based on the previous experiments, the optimal applicable water quality conditions for redox-active polymer-type biological carriers with different loading amounts are obtained, which not only enables the present invention to better adapt to various water qualities, but also reduces the cost of sewage treatment. This method can not only achieve the removal effect of soluble inorganic nitrogen that can be removed by conventional sewage biological treatment processes, but also achieve the reduction control of soluble organic nitrogen in sewage that is difficult to achieve by conventional sewage biological treatment processes, which is beneficial to the compliance of sewage discharge and water ecological safety, and has the advantages of low operating costs and convenient operation and management. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a carbon nuclear magnetic resonance spectrum of the redox-active polymer synthesized in the present invention;

[0037] Figure 2 is a SEM image of the redox-active polymer biocarrier prepared in the present invention;

[0038] Figure 3 This is a graph showing the average concentration change of dissolved organic nitrogen before and after sewage treatment in the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0040] Example 1: A redox-active polymer is prepared by heating and precipitating m-cresol, isoquinoline, toluene, 2,6-diaminoanthraquinone and pyromellitic dianhydride as raw materials.

[0041] The specific preparation steps of the above redox active polymer are as follows:

[0042] 1. Mix 7 mL of m-cresol, 0.1 mL of isoquinoline and 5 mL of toluene, and add 2.39 g of 2,6-diaminoanthraquinone and 2.18 g of pyromellitic dianhydride to the mixed solution.

[0043] 2. Heat the above mixed system at 200°C for 5 hours. After cooling to room temperature, filter, place the obtained solid powder in boiling N,N-dimethylformamide, and repeat the stirring and filtering procedures 3 times until the washing liquid becomes colorless.

[0044] 3) washing the solid powder obtained with methanol and propanol, air-drying it, and further drying it in a vacuum drying oven to obtain the redox polymer.

[0045] The synthesized redox-active polymer was characterized by carbon NMR spectroscopy. Figure 1 shown.

[0046] Example 2: The preparation method of the redox active polymer is as follows:

[0047] 1) 3.5 mL of m-cresol, 0.05 mL of isoquinoline and 2.5 mL of toluene were mixed, and 1.20 g of 2,6-diaminoanthraquinone and 1.09 g of pyromellitic dianhydride were added to the mixed solution;

[0048] 2) The mixed system was heated at 200°C for 5 hours. After cooling to room temperature, the mixture was filtered and the obtained solid powder was placed in boiling N,N-dimethylformamide. The stirring and filtering procedures were repeated 3 times until the washing liquid was colorless.

[0049] 3) washing the solid powder obtained with methanol and propanol, air-drying it, and further drying it in a vacuum drying oven to obtain the redox polymer.

[0050] Example 3: The preparation method of the redox active polymer is as follows:

[0051] 1) 2 mL of m-cresol, 0.03 mL of isoquinoline and 1.4 mL of toluene were mixed, and 0.68 g of 2,6-diaminoanthraquinone and 0.62 g of pyromellitic dianhydride were added to the mixed solution.

[0052] 2) The mixed system was heated at 200°C for 5 hours. After cooling to room temperature, the mixture was filtered and the obtained solid powder was placed in boiling N,N-dimethylformamide. The stirring and filtering procedures were repeated 3 times until the washing liquid was colorless.

[0053] 3) washing the solid powder obtained with methanol and propanol, air-drying it, and further drying it in a vacuum drying oven to obtain the redox polymer.

[0054] Example 4: The redox-active polymer prepared in Example 1 is used to prepare a biological carrier, and the specific steps are as follows:

[0055] 1) Cut 5g of polyurethane carrier into cubes and wash them with deionized water several times. After drying, soak them in 2mol / L sodium hydroxide solution for 2 hours, take them out, wash them with deionized water and dry them. The polyurethane carrier can also be replaced with other commonly used polymer foaming materials. The porosity of the polyurethane carrier is 95%, and the effective specific surface area is 9000m 2 / m 3 , specific gravity is 1.2g / cm 3 .

[0056] 2) 2 g of the redox-active polymer synthesized in Example 1 was added to 1 L of a mixed solution containing N,N-dimethylamide and diethylenetriamine (the volume ratio of the two was 100:1) and ultrasonicated for 1 hour; the polyurethane carrier soaked in 2 mol / L sodium hydroxide solution was transferred to the ultrasonicated solution, the pH was adjusted to 10 with sodium hydroxide solution and soaked at 30°C for 1 hour; the soaked polyurethane carrier was taken out and transferred to 2 mol / L sodium hydroxide solution again, and soaked at 70°C for 1 hour; the polyurethane carrier was taken out, washed with deionized water and dried to obtain a high-load redox-active polymer-type biocarrier PUF@PIAQ 高 PUF@PIAQ 高 The mass ratio of the redox-active polymer to the polyurethane carrier is 2:5.

[0057] The prepared redox-active polymer biocarrier PUF@PIAQ 高 Scanning electron microscopy was performed and the results were as follows Figure 2 As shown in Figure A.

[0058] Example 5: The redox-active polymer prepared in Example 2 is used to prepare a biological carrier, and the specific steps are as follows:

[0059] 1) 5g of polyurethane carrier was cut into cubes and washed with deionized water several times, dried and soaked in 2mol / L sodium hydroxide solution for 2 hours, washed with deionized water and dried; the porosity of the polyurethane carrier was 97% and the effective specific surface area was 9300m 2 / m 3 , specific gravity is 1.1g / cm 3 .

[0060] 2) 1 g of the redox-active polymer synthesized in Example 2 was added to 1 L of a mixed solution containing N,N-dimethylamide and diethylenetriamine (the volume ratio of the two was 100:1) and ultrasonicated for 1 hour; the polyurethane carrier soaked in 2 mol / L sodium hydroxide solution was transferred to the ultrasonicated solution, the pH was adjusted to 10 with sodium hydroxide solution and soaked at 30°C for 1 hour; the soaked polyurethane carrier was taken out and transferred to 2 mol / L sodium hydroxide solution again, and soaked at 70°C for 1 hour; the polyurethane carrier was taken out, washed with deionized water and dried to obtain a redox-active polymer-type biocarrier PUF@PIAQ containing a medium load. 中 ,PUF@PIAQ 中 The mass ratio of the redox-active polymer to the polyurethane carrier is 1:5.

[0061] The prepared redox-active polymer biocarrier PUF@PIAQ 中 Scanning electron microscopy was performed and the results were as follows Figure 2 As shown in Figure B.

[0062] Example 6: The redox-active polymer prepared in Example 3 is used to prepare a biological carrier, and the specific steps are as follows:

[0063] 1) 5g of polyurethane carrier was cut into cubes and washed with deionized water several times, dried and soaked in 2mol / L sodium hydroxide solution for 2 hours, washed with deionized water and dried; the porosity of the polyurethane carrier was 98% and the effective specific surface area was 9500m 2 / m 3 , specific gravity is 1.0g / cm 3 .

[0064] 2) 0.5 g of the redox-active polymer synthesized in Example 3 was added to 1 L of a mixed solution containing N,N-dimethylamide and diethylenetriamine (the volume ratio of the two was 100:1) and ultrasonicated for 1 hour; the polyurethane carrier soaked in 2 mol / L sodium hydroxide solution was transferred to the ultrasonicated solution, the pH was adjusted to 10 with sodium hydroxide solution and soaked at 30°C for 1 hour; the soaked polyurethane carrier was taken out and transferred to 2 mol / L sodium hydroxide solution again, and soaked at 70°C for 1 hour; the polyurethane carrier was taken out, washed with deionized water and dried to obtain a low-load redox-active polymer-type biocarrier PUF@PIAQ 低 PUF@PIAQ 低 The mass ratio of the redox-active polymer to the polyurethane carrier is 1:10.

[0065] The prepared redox-active polymer biocarrier PUF@PIAQ 低Scanning electron microscopy was performed and the results were as follows Figure 2 As shown in Figure C.

[0066] Embodiment 7:

[0067] The sewage treated in this embodiment is the actual secondary effluent of a municipal sewage treatment plant. The average chemical oxygen demand in the sewage is 23.5 mg / L, the average dissolved total nitrogen concentration is 16.5 mg / L, and the average dissolved organic nitrogen concentration is 2.2 mg / L.

[0068] The above-mentioned sewage was treated using the biological carrier prepared in Example 4, and the specific steps are as follows:

[0069] (1) Determination of the concentration of dissolved organic nitrogen and dissolved total nitrogen in sewage: The collected sewage was first filtered with a 0.45 μm PES membrane. The dissolved total nitrogen was determined by potassium persulfate oxidation-ultraviolet spectrophotometry. The nitrate nitrogen, nitrite nitrogen and ammonia nitrogen in the dissolved inorganic nitrogen were determined by ultraviolet spectrophotometry, N-(1-naphthyl)-ethylenediamine spectrophotometry and Nessler's reagent method, respectively, and were recorded as C DIN The chemical oxygen demand is determined by potassium dichromate method. The result is C TDN =16.5mg / L, C DIN =14.3mg / L,C DON =C TDN -C DIN =2.2mg / L, C COD =23.5mg / L, due to C COD / C TDN If the concentration of sodium acetate is 33 mg / L, C DON / C TDN greater than 10%, so the biocarrier PUF@PIAQ with a higher redox-active polymer loading was selected 高 As filler for denitrification bioreactor.

[0070] (2) The denitrification bioreactor includes a denitrification bed, a raw water feed subsystem, and a backwash subsystem. PUF@PIAQ 高 Fill the denitrification bed and select the activated sludge from the anoxic process section of the sewage plant to PUF@PIAQ 高 The reactor was aerated for 48 hours, followed by continuous water inflow. The hydraulic retention time of the denitrification reactor was 2 hours, and the backwashing mode was air-water backwashing. No air-water backwashing was performed in the first week to ensure the smooth growth of the biofilm, and the effluent indicators were monitored every day.

[0071] (3) The concentration of dissolved organic nitrogen in the effluent of the denitrification bioreactor is as follows: Figure 3As shown in the figure, the concentration of dissolved organic nitrogen in the effluent of the denitrification bioreactor (control group) filled with a carrier without redox active polymer is 2.1 mg / L, which is equivalent to the dissolved organic nitrogen content in the influent, indicating that it is difficult to achieve the reduction control of dissolved organic nitrogen in sewage with conventional biological treatment processes. In this example, the redox active polymer biological carrier PUF@PIAQ 高 The dissolved organic nitrogen in the effluent of the filled denitrification bioreactor (experimental group) was 0.8 mg / L, and the dissolved organic nitrogen in the sewage was well reduced and controlled.

[0072] Embodiment 8:

[0073] The sewage treated in this embodiment is the effluent from the nitrifying biofilter of a municipal sewage plant in Jiangsu Province. The average chemical oxygen demand in the sewage is 40.0 mg / L, the average dissolved total nitrogen concentration is 21.4 mg / L, and the average dissolved organic nitrogen concentration is 2.0 mg / L.

[0074] The above-mentioned sewage was treated using the biological carrier prepared in Example 5, and the specific steps are as follows:

[0075] (1) Determination of the concentration of dissolved organic nitrogen and dissolved total nitrogen in sewage: The collected sewage was first filtered with a 0.45 μm PES membrane. The dissolved total nitrogen was determined by potassium persulfate oxidation-ultraviolet spectrophotometry. The nitrate nitrogen, nitrite nitrogen and ammonia nitrogen in the dissolved inorganic nitrogen were determined by ultraviolet spectrophotometry, N-(1-naphthyl)-ethylenediamine spectrophotometry and Nessler's reagent method, respectively, and were recorded as C DIN The chemical oxygen demand is determined by potassium dichromate method. The result is C TDN =21.4mg / L, C DIN =19.4mg / L,C DON =C TDN -C DIN =2.0mg / L, C COD =53.2mg / L, due to C COD / C TDN Less than 4 and greater than 2, no additional carbon source is needed, C DON / C TDN is less than 10%, so the biocarrier PUF@PIAQ with a moderate redox-active polymer loading was selected 中 As filler for denitrification bioreactor.

[0076] (2) Using PUF@PIAQ 中 Fill the denitrification bed and select the activated sludge from the anoxic process section of the sewage plant to PUF@PIAQ 中The reactor was aerated for 48 hours, followed by continuous water inflow. The hydraulic retention time of the denitrification reactor was 2 hours, and the backwashing mode was air-water backwashing. No air-water backwashing was performed in the first week to ensure the smooth growth of the biofilm, and the effluent indicators were monitored every day.

[0077] (3) The concentration of dissolved organic nitrogen in the effluent of the denitrification bioreactor is as follows: Figure 3 As shown in the figure, the concentration of dissolved organic nitrogen in the effluent of the denitrification bioreactor filled with a carrier without redox active polymer (control group) is 1.6 mg / L, which is basically equivalent to the dissolved organic nitrogen content in the influent, indicating that conventional biological treatment processes cannot achieve the reduction control of dissolved organic nitrogen in sewage. In this example, the redox active polymer biological carrier PUF@PIAQ 中 The dissolved organic nitrogen in the effluent of the filled denitrification bioreactor (experimental group) was 0.5 mg / L, and the dissolved organic nitrogen in the sewage was well reduced and controlled.

[0078] Embodiment 9:

[0079] The sewage treated in this embodiment is the actual secondary effluent of an industrial sewage plant in Jiangsu Province. The average chemical oxygen demand in the sewage is 115.6 mg / L, the average dissolved total nitrogen concentration is 28.3 mg / L, and the average dissolved organic nitrogen concentration is 6.8 mg / L. The dissolved organic nitrogen content is relatively high.

[0080] The above-mentioned sewage was treated using the biological carrier prepared in Example 6, and the specific steps are as follows:

[0081] (1) Determination of the concentration of dissolved organic nitrogen and dissolved total nitrogen in sewage: The collected sewage was first filtered with a 0.45 μm PES membrane. The dissolved total nitrogen was determined by potassium persulfate oxidation-ultraviolet spectrophotometry. The nitrate nitrogen, nitrite nitrogen and ammonia nitrogen in the dissolved inorganic nitrogen were determined by ultraviolet spectrophotometry, N-(1-naphthyl)-ethylenediamine spectrophotometry and Nessler's reagent method, respectively, and were recorded as C DIN The chemical oxygen demand is determined by potassium dichromate method. The result is C TDN =28.3mg / L, C DIN =21.5mg / L,C DON =C TDN -C DIN =6.8mg / L, C COD =115.6mg / L, due to C COD / C TDN is greater than 4, so the biocarrier PUF@PIAQ with a lower redox-active polymer loading is selected 低 As filler for denitrification bioreactor.

[0082] (2) Using PUF@PIAQ低 Fill the denitrification bed and select the activated sludge from the anoxic process section of the sewage plant to PUF@PIAQ 低 The reactor was aerated for 48 hours, followed by continuous water inflow. The hydraulic retention time of the denitrification reactor was 2 hours, and the backwashing mode was air-water backwashing. No air-water backwashing was performed in the first week to ensure the smooth growth of the biofilm, and the effluent indicators were monitored every day.

[0083] (3) The concentration of dissolved organic nitrogen in the effluent of the denitrification bioreactor is as follows: Figure 3 As shown in the figure, the concentration of dissolved organic nitrogen in the effluent of the denitrification bioreactor filled with a carrier without redox active polymer (control group) is 5.3 mg / L, while in this example, the redox active polymer biocarrier PUF@PIAQ 低 The dissolved organic nitrogen in the effluent of the filled denitrifying bioreactor (experimental group) was 2.2 mg / L, and the dissolved organic nitrogen in the sewage was significantly reduced.

Claims

1. A method for preparing a biocarrier using a redox-active polymer, characterized in that: The following steps are involved: (1) Soaking the polymer carrier in a sodium hydroxide solution, taking it out, cleaning it and drying it; (2) adding a mixed solid of 2,6-diaminoanthraquinone and pyromellitic acid dianhydride to a mixed solution of m-cresol, isoquinoline and toluene to obtain a mixed reaction system; the solid-liquid ratio of the mixed solid to the mixed liquid is: 1.30-4.57 g: 3.43-12.1 mL; the volume ratio of m-cresol, isoquinoline and toluene is 20-70: 0.3-1: 14-50; the molar ratio of 2,6-diaminoanthraquinone and pyromellitic acid dianhydride is 1-2: 1-2; The mixed reaction system is heated to react, cooled after the reaction, filtered, and the solid powder is placed in boiling N,N-dimethylformamide, and the stirring and filtering procedures are repeated until the washing liquid is colorless; the heating reaction conditions are heating at 150-250° C. for 3-7 hours; The solid powder is then washed with methanol and propanol and dried to obtain a redox active polymer; adding a redox-active polymer into a mixed solution of N,N-dimethylamide and diethylenetriamine and subjecting the mixed solution to ultrasonic treatment to obtain a coating solution; (3) The polymer carrier dried in step (1) is transferred to a coating solution for immersion, the polymer carrier after the coating solution is transferred to a sodium hydroxide solution for immersion, and the polymer carrier after the immersion is taken out for washing and drying to obtain a biological carrier.

2. The method for preparing a biological carrier according to claim 1, wherein in step (1), the polymer carrier has a porosity of 95-98% and an effective specific surface area of ​​not less than 9000 m 2 / m 3 , specific gravity is 1.0-1.2 g / cm 3 Polyurethane carrier.

3. According to the method for preparing a biocarrier according to claim 1, in step (2), the solid-liquid ratio of the redox-active polymer to the mixed solution is 0.1-10 g / 1L, and the volume ratio of N,N-dimethylamide and diethylenetriamine in the mixed solution is 90-110:

1.

4. According to the method for preparing a biological carrier according to claim 1, in step (3), the method of soaking in the coating liquid is: adjusting the pH to 9-11 with sodium hydroxide solution and soaking at 20-40°C for 0.5-1.5h; the method of soaking in the sodium hydroxide solution is: soaking in 2M sodium hydroxide solution at 60-80°C for 0.5-1.5h.

5. Use of the biological carrier obtained according to claim 1 in the reduction control of dissolved organic nitrogen in sewage.

6. The use according to claim 5, characterized in that: The method of the application comprises the following steps: (1) Determine the concentration of dissolved organic nitrogen, dissolved total nitrogen and chemical oxygen demand in sewage respectively; (2) Based on the data of dissolved organic nitrogen concentration, dissolved total nitrogen concentration and chemical oxygen demand, bio-carriers with different redox active polymer loadings were selected to construct denitrification bioreactors; (3) Operate the denitrifying bioreactor to achieve the reduction of dissolved organic nitrogen in sewage.

7. The use according to claim 6, characterized in that: In step (1), the concentration of dissolved organic nitrogen in the wastewater is obtained by measuring and calculating the concentration difference between dissolved total nitrogen and dissolved inorganic nitrogen.

8. The use according to claim 6, characterized in that: In step (2), the bio-carriers with different redox-active polymer loadings include PUF@PIAQ 低 PUF@PIAQ 中 and PUF@PIAQ 高 , the PUF@PIAQ 低 PUF@PIAQ 中 and PUF@PIAQ 高 The mass ratio of redox active polymer to polymer carrier is PUF@PIAQ 低 <PUF@PIAQ 中 <PUF@PIAQ 高 ; The denitrification bioreactor comprises a denitrification bed, a raw water feed subsystem and a backwash subsystem; The method for selecting bio-carriers with different redox active polymer loading amounts to construct a denitrification bioreactor is: When the COD / TDN concentration in sewage is >4, use PUF@PIAQ 低 Filling denitrification beds; When the chemical oxygen demand / dissolved total nitrogen concentration in the sewage is ≤4 and the dissolved organic nitrogen concentration / dissolved total nitrogen concentration is less than 10%, use PUF@PIAQ 中 Filling denitrification beds; When the chemical oxygen demand / dissolved total nitrogen concentration in the sewage is ≤4 and the dissolved organic nitrogen concentration / dissolved total nitrogen concentration is greater than 10%, use PUF@PIAQ 高 Fill the denitrification bed.

9. The use according to claim 6, characterized in that: In step (3), the operation process of the denitrification bioreactor is to pass the sewage through the denitrification bioreactor at a flow rate of at least 2.0 BV / h, and the backwashing mode is air-water backwashing; the chemical oxygen demand / dissolved total nitrogen concentration in the sewage should be not less than 2. If the chemical oxygen demand in the sewage is insufficient, an appropriate amount of sodium acetate is added as an external carbon source.

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