Method for amplifying specific surface area of autotrophic nitrogen removal filler

Abstract

The invention relates to the technical field of water treatment fillers, and discloses a specific surface area amplification method of an autotrophic nitrogen removal filler, which comprises the following steps: mixing a composite matrix material, an iron-containing substance, an inorganic carbon source and an adhesive, stirring and mixing to obtain a mixture; adding the mixture into deionized water, stirring, extruding and granulating, and drying to obtain a composite filler; the autotrophic nitrogen removal filler is obtained by modifying the surface of a composite filler with dopamine and then mixing and reacting with ferrocene. Manganese dioxide is synthesized in pores of the activated carbon, so that adsorption and fixation of the matrix material sulfur are enhanced, and migration and precipitation of the matrix material sulfur are avoided; the activated carbon loaded with manganese dioxide is used as a supporting framework of a matrix material sulfur, so that the strength of the sulfur autotrophic filler is improved; spherical particles with a cross-linked network structure are formed on the surface of the activated carbon loaded with the aminated matrix material, so that the specific surface area of the autotrophic nitrogen removal filler is increased, and the nitrogen removal efficiency is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment fillers, in particular to a method for amplifying the specific surface area of ​​an autotrophic denitrification filler. Background Art

[0002] Nitrogen-containing pollutants are one of the main ecological problems in the water environment. The main sources of nitrogen pollution are non-point source pollution during the application of nitrogen fertilizers, point source pollution caused by domestic sewage and industrial nitrogen-containing wastewater discharge. A large amount of nitrogen-containing wastewater discharged into the water body will cause eutrophication of the water body, cause the death of aquatic organisms, and destroy biodiversity. Among them, nitrate is an important factor that endangers the health of the water environment. Nitrate pollution in water bodies will not only affect the water environment, but also endanger people's health. Therefore, it is necessary to effectively denitrify sewage.

[0003] The main function of autotrophic denitrification filler is to degrade total nitrogen and ammonia nitrogen to achieve deep nitrogen and phosphorus removal. It can reduce nitrate nitrogen in water to nitrogen gas without the need for an external organic carbon source, thereby achieving the purpose of removing nitrate nitrogen. However, the sulfur in the autotrophic denitrification filler has weak resistance to hydraulic shock and low mechanical strength. During the sewage treatment process, the mutual collision of the autotrophic denitrification fillers causes the filler to break during operation, affecting the denitrification efficiency of the autotrophic denitrification filler. In addition, the sulfur in the autotrophic denitrification filler is easy to migrate and precipitate, affecting the denitrification efficiency. Summary of the Invention

[0004] The invention provides a method for increasing the specific surface area of ​​an autotrophic denitrification filler, which solves the problem that sulfur in the autotrophic denitrification filler has weak hydraulic shock resistance and is easy to migrate and precipitate.

[0005] The technical solution of the present invention:

[0006] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0007] S1. Mixing the composite matrix material, the iron-containing substance, the inorganic carbon source, and the binder, stirring and mixing at 500-600 rpm for 30-50 min to obtain a mixture;

[0008] S2. Add the mixture to deionized water, stir at 500-600 rpm for 15-20 min, continue stirring at 40-50° C. for 15-20 min, granulate by extrusion, and dry to obtain a composite filler;

[0009] S3, using dopamine to modify the surface of the composite filler, and then mixing it with ferrocene to react and obtain an autotrophic denitrification filler;

[0010] The composite matrix material is prepared by modifying the composite activated carbon loaded with the matrix material with a coupling agent, and then reacting the composite activated carbon with sodium alginate, polyvinyl alcohol and calcium chloride solution, and drying the composite matrix material.

[0011] The composite activated carbon loaded with matrix material is obtained by mixing activated carbon, potassium permanganate and sodium nitrite, and then mixing with the matrix material.

[0012] Furthermore, the iron-containing substance is nano-iron with a particle size of 40-60nm.

[0013] Furthermore, the inorganic carbon source is selected from sodium carbonate or calcium carbonate.

[0014] Furthermore, the binder is selected from one or more of diatomaceous earth, starch, polyvinyl alcohol and carboxymethyl cellulose.

[0015] Furthermore, in step S1, the mass ratio of the composite matrix material, the iron-containing substance, the inorganic carbon source and the binder is (60-80):(8-10):(20-50):(5-8).

[0016] Furthermore, in step S2, the pressure of the extrusion granulation is 2-2.5 MPa; and the ratio of the mixture to deionized water is (50-60) g: (20-30) mL.

[0017] Furthermore, in step S3, the autotrophic denitrification filler is specifically prepared by the following steps:

[0018] A1. The composite filler was added to Tris-HCl buffer, stirred evenly, dopamine was added, and the reaction was stirred for 3-4 hours. The mixture was filtered, washed, and dried to obtain a polydopamine-modified composite filler.

[0019] A2. Add the polydopamine-modified composite filler and ferrocene to deionized water, stir at 800-1000 r / min for 20-30 min, let it stand, filter, wash, and dry to obtain an autotrophic denitrification filler.

[0020] Furthermore, during the above reaction A1, in the Tris-HCl buffer, dopamine can self-polymerize on the surface of the composite filler to form polydopamine, thereby forming a polydopamine-modified composite filler, so that the composite filler carries a large number of phenolic hydroxyl groups, which is conducive to the adhesion of ferrocene on the surface of the composite filler.

[0021] Furthermore, during the above-mentioned A2 reaction process, the polydopamine-modified composite filler has excellent adhesion and contains a large number of phenolic hydroxyl groups, which can be chemically bonded with ferrocene, so that ferrocene adheres to the surface of the polydopamine-modified composite filler to form an autotrophic denitrification filler.

[0022] Furthermore, in step A1, the ratio of the composite filler, Tris-HCl buffer and dopamine is (4-6) g: (40-50) mL: (0.2-0.4) g.

[0023] Furthermore, in step A2, the ratio of the polydopamine-modified composite filler, ferrocene and deionized water is (4-6) g: (0.5-1.5) g: (25-35) mL.

[0024] Furthermore, the composite matrix material is specifically prepared by the following steps:

[0025] B1. Potassium permanganate and sodium nitrite were added to deionized water and stirred evenly. Aqueous sulfuric acid solution was added and stirred evenly. Activated carbon was added and stirred evenly. After standing for 1-2 hours, the mixture was placed in a reaction vessel and stirred at 160-180°C for 10-12 hours. The mixture was cooled to room temperature, filtered, washed, and dried to obtain activated carbon loaded with manganese dioxide.

[0026] B2. The matrix material was added to carbon disulfide, stirred, and activated carbon loaded with manganese dioxide was added, stirred and mixed at 500-600 r / min for 8-10 min, allowed to stand for 20-30 min, and the solid was collected by filtration. After the solid was dried, a composite activated carbon loaded with the matrix material was obtained;

[0027] B3. The composite activated carbon loaded with the matrix material was added to ethanol and deionized water, stirred evenly, a coupling agent was added, and the reaction was stirred at 70-90 ° C for 4-5h, cooled to room temperature, filtered, washed, and dried to obtain an amino-loaded matrix material composite activated carbon;

[0028] B4. Add sodium alginate and polyvinyl alcohol to deionized water, stir at 90-100°C for 2-3 hours, cool to room temperature, add the amino-loaded composite activated carbon matrix material, stir and mix at 300-400 r / min for 20-30 minutes, add calcium chloride aqueous solution, continue stirring for 20-30 minutes, filter, and dry to obtain a composite matrix material.

[0029] Furthermore, in the above-mentioned B1 reaction process, activated carbon is mixed with potassium permanganate and ammonium chloride for reaction. The activated carbon has a high specific surface area and a porous structure, and has excellent adsorption properties. It can adsorb the potassium permanganate and sodium nitrite mixture into the pores of the activated carbon. After adding sulfuric acid, potassium permanganate is used as an oxidant and sodium nitrite is used as a reducing agent. A hydrothermal reaction is carried out at 160-180°C, so that potassium permanganate and sodium nitrite undergo an oxidation-reduction reaction to form manganese dioxide crystals. As the reaction proceeds, the manganese dioxide crystals grow to form nano-manganese dioxide, thereby realizing the synthesis of nano-manganese dioxide with a size of 1-2 μm in the pores of the activated carbon.

[0030] Furthermore, during the above-mentioned B2 reaction process, the matrix material sulfur is dissolved in carbon disulfide, and the matrix material sulfur molecules are converted from rings to chains, which greatly reduces the steric hindrance effect. In addition, the activated carbon loaded with manganese dioxide has excellent adsorption properties, so that the matrix material sulfur can enter the pores of the activated carbon loaded with manganese dioxide relatively smoothly, forming a composite activated carbon loaded with the matrix material.

[0031] Furthermore, during the above-mentioned B3 reaction process, the silanol groups generated by the hydrolysis of the coupling agent can be chemically bonded to the hydroxyl groups on the surface of the composite activated carbon loaded with the matrix material, so that the coupling agent is grafted onto the surface of the composite activated carbon loaded with the matrix material to form an amino-loaded composite activated carbon loaded with the matrix material.

[0032] Furthermore, during the above-mentioned B4 reaction process, calcium chloride, as a cross-linking agent, can be chemically bonded to the hydroxyl groups in sodium alginate and polyvinyl alcohol to form spherical particles with a cross-linked network structure, and the amino groups on the surface of the activated carbon of the amino-loaded matrix material can also be chemically bonded to the hydroxyl groups in sodium alginate and polyvinyl alcohol, so that the spherical particles with a cross-linked network structure are attached to the surface of the activated carbon of the amino-loaded matrix material to form a composite matrix material.

[0033] Furthermore, in step B1, the ratio of potassium permanganate, sodium nitrite, deionized water, aqueous sulfuric acid solution and activated carbon is (4-6) g: (7-8) g: (35-45) mL: (1-3) mL: (8-12) g.

[0034] Furthermore, in step B2, the mass ratio of the matrix material, carbon disulfide and manganese dioxide-loaded activated carbon is (2-3):(8-12):(18-22).

[0035] Furthermore, in step B3, the ratio of the composite activated carbon, ethanol, deionized water and coupling agent used in the loaded matrix material is (5-7) g: (35-45) mL: (8-12) mL: (1-2) g.

[0036] Furthermore, in step B4, the ratio of the sodium alginate, polyvinyl alcohol, deionized water, composite activated carbon loaded with amino matrix material and calcium chloride aqueous solution is (1-2) g: (2-3) g: (45-55) mL: (8-12) g: (0.3-0.7) g.

[0037] Furthermore, the activated carbon has a particle size of 5-8 mm, a pore size of 20-50 μm, and a specific surface area of ​​800-1200 m 2 / g.

[0038] Furthermore, the matrix material is sulfur.

[0039] Furthermore, the coupling agent is γ-aminopropyltriethoxysilane.

[0040] The present invention has the following beneficial effects:

[0041] (1) In the technical solution of the present invention, the activated carbon has a high specific surface area and an ordered mesoporous channel structure. As a carrier of the matrix material sulfur, it can improve the dispersion of the matrix material sulfur and is conducive to the attachment and growth of the bacterial community, thereby increasing the biomass in the system and improving the denitrification efficiency. Manganese dioxide is synthesized in the pores of the activated carbon. On the one hand, the synthesized manganese dioxide is randomly distributed in the pores of the activated carbon, thereby enhancing the adsorption and fixation of the matrix material sulfur and avoiding the migration and precipitation of the matrix material sulfur, which affects the denitrification performance of the autotrophic denitrification filler. On the other hand, the synthesized manganese dioxide can participate in the transfer of electrons in the denitrification process of microorganisms, and the microorganisms can use manganese dioxide as a terminal electron acceptor to convert NH 4+ Oxidation to generate NO 3- , the reduced Mn 2+ It can also serve as an effective inorganic electron donor in the denitrification process, which is beneficial to improving the denitrification rate and realizing the conversion and removal of nitrogen.

[0042] (2) In the technical solution of the present invention, the matrix material sulfur is dissolved in carbon disulfide, and the matrix material sulfur molecules are converted from rings to chains, which greatly reduces the steric hindrance effect. In addition, the activated carbon loaded with manganese dioxide has excellent adsorption properties, so that the matrix material sulfur can enter the pores of the activated carbon loaded with nano manganese dioxide relatively smoothly. The formed filler has good impact load resistance, can adapt to fluctuations in water quality conditions, and maintain a stable denitrification effect. The activated carbon loaded with manganese dioxide serves as the supporting skeleton of the matrix material sulfur, improves the strength of the sulfur autotrophic filler, and extends the service life of the autotrophic denitrification filler.

[0043] (3) In the technical solution of the present invention, γ-aminopropyltriethoxysilane is grafted onto the surface of the composite activated carbon of the loaded matrix material, giving the composite activated carbon of the loaded matrix material reactive amino groups, which is conducive to the formation of spherical particles with a cross-linked network structure on the surface of the composite activated carbon of the loaded matrix material, increasing the mechanical strength, and having a larger surface area, thereby increasing the specific surface area; sodium alginate, polyvinyl alcohol and calcium chloride solution form spherical particles with a cross-linked network structure on the surface of the activated carbon of the amino loaded matrix material. On the one hand, the formed cross-linked network structure can absorb and reduce the stress caused by water quality fluctuations, further improving the mechanical strength of the autotrophic denitrification filler; on the other hand, the spherical particles with a cross-linked network structure are attached to the surface of the activated carbon of the amino loaded matrix material, thereby increasing the surface roughness, having a larger surface area, increasing the specific surface area of ​​the autotrophic denitrification filler, and thereby improving the denitrification efficiency.

[0044] (4) In the technical solution of the present invention, ferrocene adheres to the surface of the composite filler modified with polydopamine to form an autotrophic denitrification filler. On the one hand, ferrocene is loaded on the surface of the composite filler modified with polydopamine to form a concave-convex structure, which can fix the detached matrix material sulfur and enhance the force of the activated carbon on the matrix material sulfur. On the other hand, ferrocene is loaded on the surface of the composite filler modified with polydopamine, further increasing the specific surface area of ​​the autotrophic denitrification filler, improving the attachment and growth of microorganisms, and further improving the removal rate of total nitrogen. DETAILED DESCRIPTION

[0045] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] The raw materials used in the examples of the present invention are as follows, and all reagents used are of analytical grade.

[0047] Among them, the iron-containing substance is nano-iron with CAS number 7439-89-6 and particle size of 50nm, produced by Zhongke Leiming (Beijing) Technology Co., Ltd.

[0048] The inorganic carbon source is sodium carbonate.

[0049] The binder is carboxymethyl cellulose, Shandong Guohua Chemical Co., Ltd.

[0050] The activated carbon particle size is 7 mm and the pore size is 35 μm.

[0051] The matrix material is sulfur.

[0052] The coupling agent is γ-aminopropyltriethoxysilane.

[0053] Ferrocene was purchased from Jinan Qida New Materials Co., Ltd.

[0054] Example 1

[0055] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0056] S1. Mixing the composite matrix material, nano-iron, sodium carbonate, and carboxymethyl cellulose, and stirring at 500 rpm for 30 minutes to obtain a mixture;

[0057] S2. Add the mixture to deionized water, stir at 500 rpm for 15 min, continue stirring at 40° C. for 15 min, place in a granulation extruder, extrude and granulate, and dry to obtain a composite filler;

[0058] S3, using dopamine to modify the surface of the composite filler, and then mixing it with ferrocene to react and obtain an autotrophic denitrification filler;

[0059] In step S1, the mass ratio of the composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose is 60:8:20:5;

[0060] In step S2, the pressure of extrusion granulation is 2 MPa;

[0061] The ratio of the mixture to deionized water is 50 g:20 mL.

[0062] The autotrophic denitrification filler is specifically prepared by the following steps:

[0063] A1. 4 g of the composite filler was added to 40 mL of Tris-HCl buffer (pH 8.5), stirred evenly, and 0.2 g of dopamine was added. The mixture was stirred for 3 h, filtered, washed three times with deionized water, and dried in a 70°C oven for 10 min to obtain a polydopamine-modified composite filler.

[0064] A2. Add 4 g of polydopamine-modified composite filler and 0.5 g of ferrocene to 25 mL of deionized water, stir at 800 rpm for 20 min, let stand for 1 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain an autotrophic denitrification filler.

[0065] The composite matrix material is specifically prepared by the following steps:

[0066] B1. Add 4g of potassium permanganate and 7g of sodium nitrite to 35mL of deionized water and stir evenly. Add 1mL of 0.5mol / L aqueous sulfuric acid solution and stir evenly. Add 8g of activated carbon and stir evenly. After standing for 1h, place in a reactor and stir at 160°C for 10h. Cool to room temperature, filter, wash three times with deionized water and three times with ethanol, and dry in a 60°C oven for 10min to obtain activated carbon loaded with manganese dioxide.

[0067] B2. 2 g of sulfur was added to 8 g of carbon disulfide, stirred, and 18 g of manganese dioxide-loaded activated carbon was added. The mixture was stirred at 500 rpm for 8 min, allowed to stand for 20 min, and the solid was collected by filtration. The solid was dried in an oven at 50 ° C for 2 h to obtain a composite activated carbon loaded with a matrix material.

[0068] B3. 5 g of the composite activated carbon loaded with the matrix material was added to 35 mL of ethanol and 8 mL of deionized water, stirred evenly, and 1 g of γ-aminopropyltriethoxysilane was added. The mixture was stirred at 70 ° C for 4 h, cooled to room temperature, filtered, washed three times with ethanol, washed three times with deionized water, and dried in an oven at 70 ° C for 10 min to obtain the composite activated carbon loaded with the matrix material.

[0069] B4. Add 1 g of sodium alginate and 2 g of polyvinyl alcohol to 45 mL of deionized water, stir at 90°C for 2 h, cool to room temperature, add 8 g of amino-loaded composite activated carbon matrix material, stir and mix at 300 r / min for 20 min, add 0.3 g of 2% calcium chloride aqueous solution, continue stirring for 20 min, filter, and dry at -4°C for 10 h to obtain a composite matrix material.

[0070] Example 2

[0071] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0072] S1. Mixing the composite matrix material, nano-iron, sodium carbonate, and carboxymethyl cellulose, and stirring at 550 rpm for 40 minutes to obtain a mixture;

[0073] S2. Add the mixture to deionized water, stir at 550 rpm for 18 min, continue stirring at 45° C. for 18 min, place in a granulation extruder, extrude and granulate, and dry to obtain a composite filler;

[0074] S3, using dopamine to modify the surface of the composite filler, and then mixing it with ferrocene to react and obtain an autotrophic denitrification filler;

[0075] In step S1, the mass ratio of the composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose is 70:9:30:6;

[0076] In step S2, the pressure of extrusion granulation is 2.3 MPa;

[0077] The ratio of the mixture to deionized water is 55g:25mL.

[0078] The autotrophic denitrification filler is specifically prepared by the following steps:

[0079] A1. 5 g of the composite filler was added to 45 mL of Tris-HCl buffer (pH 8.5), stirred evenly, and 0.3 g of dopamine was added. The mixture was stirred for 3.5 h, filtered, washed three times with deionized water, and dried in a 70°C oven for 10 min to obtain a polydopamine-modified composite filler.

[0080] A2. Add 5 g of polydopamine-modified composite filler and 1 g of ferrocene to 30 mL of deionized water, stir at 900 rpm for 25 min, let stand for 1 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain an autotrophic denitrification filler.

[0081] The composite matrix material is specifically prepared by the following steps:

[0082] B1. Add 5g of potassium permanganate and 7.5g of sodium nitrite to 40mL of deionized water and stir evenly. Add 2mL of 0.5mol / L aqueous sulfuric acid solution and stir evenly. Add 10g of activated carbon and stir evenly. After standing for 1.5h, place in a reactor and stir at 170°C for 11h. Cool to room temperature, filter, wash three times with deionized water and three times with ethanol, and dry in a 60°C oven for 10min to obtain activated carbon loaded with manganese dioxide.

[0083] B2. 2.5 g of sulfur was added to 10 g of carbon disulfide, stirred, and 20 g of manganese dioxide-loaded activated carbon was added. The mixture was stirred at 550 rpm for 9 min, allowed to stand for 25 min, and the solid was collected by filtration. The solid was dried in an oven at 50 ° C for 2 h to obtain a composite activated carbon loaded with a matrix material.

[0084] B3. 6 g of composite activated carbon loaded with matrix material was added to 40 mL of ethanol and 10 mL of deionized water, stirred evenly, 1.5 g of γ-aminopropyltriethoxysilane was added, and the reaction was stirred at 80 ° C for 4.5 h, cooled to room temperature, filtered, washed three times with ethanol, washed three times with deionized water, and dried in an oven at 70 ° C for 10 min to obtain an amino-loaded matrix material composite activated carbon;

[0085] B4. Add 1.5 g of sodium alginate and 2.5 g of polyvinyl alcohol to 50 mL of deionized water, stir at 95 °C for 2.5 h, cool to room temperature, add 10 g of amino-loaded composite activated carbon matrix material, stir and mix at 350 r / min for 25 min, add 0.5 g of 2% calcium chloride aqueous solution, continue stirring for 25 min, filter, and dry at -4 °C for 10 h to obtain a composite matrix material.

[0086] Example 3

[0087] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0088] S1. Mixing the composite matrix material, nano-iron, sodium carbonate, and carboxymethyl cellulose, and stirring at 600 rpm for 50 min to obtain a mixture;

[0089] S2. Add the mixture to deionized water, stir at 600 rpm for 20 min, continue stirring at 50° C. for 20 min, place in a granulation extruder, extrude and granulate, and dry to obtain a composite filler;

[0090] S3, using dopamine to modify the surface of the composite filler, and then mixing it with ferrocene to react and obtain an autotrophic denitrification filler;

[0091] In step S1, the mass ratio of the composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose is 80:10:50:8;

[0092] In step S2, the pressure of extrusion granulation is 2.5 MPa;

[0093] The ratio of the mixture to deionized water is 60g:30mL.

[0094] The autotrophic denitrification filler is specifically prepared by the following steps:

[0095] A1. Add 6 g of the composite filler to 50 mL of Tris-HCl buffer (pH 8.5) and stir until evenly mixed. Then add 0.4 g of dopamine and stir for 4 h. The mixture is filtered, washed three times with deionized water, and dried in a 70°C oven for 10 min to obtain a polydopamine-modified composite filler.

[0096] A2. Add 6 g of polydopamine-modified composite filler and 1.5 g of ferrocene to 35 mL of deionized water, stir at 1000 rpm for 30 min, let stand for 1 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain an autotrophic denitrification filler.

[0097] The composite matrix material is specifically prepared by the following steps:

[0098] B1. Add 6g of potassium permanganate and 8g of sodium nitrite to 45mL of deionized water and stir evenly. Add 3mL of 0.5mol / L aqueous sulfuric acid solution and stir evenly. Add 12g of activated carbon and stir evenly. After standing for 2h, place in a reactor and stir at 180°C for 12h. Cool to room temperature, filter, wash three times with deionized water and three times with ethanol, and dry in a 60°C oven for 10min to obtain activated carbon loaded with manganese dioxide.

[0099] B2. 3 g of sulfur was added to 12 g of carbon disulfide, stirred, and 22 g of manganese dioxide-loaded activated carbon was added. The mixture was stirred at 600 rpm for 10 min, allowed to stand for 30 min, and the solid was collected by filtration. The solid was dried in an oven at 50 ° C for 2 h to obtain a composite activated carbon loaded with a matrix material.

[0100] B3. 7 g of composite activated carbon loaded with matrix material was added to 45 mL of ethanol and 12 mL of deionized water, stirred evenly, and 2 g of γ-aminopropyltriethoxysilane was added. The mixture was stirred at 90 ° C for 5 h, cooled to room temperature, filtered, washed three times with ethanol, washed three times with deionized water, and dried in an oven at 70 ° C for 10 min to obtain an amino-loaded matrix material composite activated carbon;

[0101] B4. Add 2 g of sodium alginate and 3 g of polyvinyl alcohol to 55 mL of deionized water, stir at 100°C for 3 h, cool to room temperature, add 12 g of amino-loaded composite activated carbon matrix material, stir and mix at 400 r / min for 30 min, add 0.7 g of 2% calcium chloride aqueous solution, continue stirring for 30 min, filter, and dry at -4°C for 10 h to obtain a composite matrix material.

[0102] Comparative Example 1

[0103] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0104] S1. Mixing the composite matrix material, nano-iron, sodium carbonate, and carboxymethyl cellulose, and stirring at 600 rpm for 50 min to obtain a mixture;

[0105] S2. Add the mixture to deionized water, stir at 600 rpm for 20 min, continue stirring at 50° C. for 20 min, place in a granulation extruder, extrude and granulate, and dry to obtain a composite filler;

[0106] S3, using dopamine to modify the surface of the composite filler, and then mixing it with ferrocene to react and obtain an autotrophic denitrification filler;

[0107] In step S1, the mass ratio of the composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose is 80:10:50:8;

[0108] In step S2, the pressure of extrusion granulation is 2.5 MPa;

[0109] The ratio of the mixture to deionized water is 60g:30mL.

[0110] The autotrophic denitrification filler is specifically prepared by the following steps:

[0111] A1. Add 6 g of the composite filler to 50 mL of Tris-HCl buffer (pH 8.5) and stir until evenly mixed. Then add 0.4 g of dopamine and stir for 4 h. The mixture is filtered, washed three times with deionized water, and dried in a 70°C oven for 10 min to obtain a polydopamine-modified composite filler.

[0112] A2. Add 6 g of polydopamine-modified composite filler and 1.5 g of ferrocene to 35 mL of deionized water, stir at 1000 rpm for 30 min, let stand for 1 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain an autotrophic denitrification filler.

[0113] The composite matrix material is specifically prepared by the following steps:

[0114] B1. 3 g of sulfur was added to 12 g of carbon disulfide, stirred, and 22 g of activated carbon was added. The mixture was stirred at 600 rpm for 10 min, allowed to stand for 30 min, and the solid was collected by filtration. The solid was dried in an oven at 50 ° C for 2 h to obtain activated carbon loaded with the matrix material.

[0115] B2. 7 g of activated carbon loaded with matrix material was added to 45 mL of ethanol and 12 mL of deionized water, stirred, and 2 g of γ-aminopropyltriethoxysilane was added. The mixture was stirred at 90 ° C for 5 h, cooled to room temperature, filtered, washed three times with ethanol, washed three times with deionized water, and dried in an oven at 70 ° C for 10 min to obtain amino-loaded matrix material activated carbon;

[0116] B3. Add 2 g of sodium alginate and 3 g of polyvinyl alcohol to 55 mL of deionized water, stir at 100°C for 3 h, cool to room temperature, add 12 g of amino-loaded activated carbon, stir and mix at 400 r / min for 30 min, add 0.7 g of 2% calcium chloride aqueous solution, continue stirring for 30 min, filter, and dry at -4°C for 10 h to obtain a composite matrix material.

[0117] Comparative Example 2

[0118] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0119] S1. Mixing the composite matrix material, nano-iron, sodium carbonate, and carboxymethyl cellulose, and stirring at 600 rpm for 50 min to obtain a mixture;

[0120] S2. Add the mixture to deionized water, stir at 600 rpm for 20 min, continue stirring at 50° C. for 20 min, place in a granulation extruder, extrude and granulate, and dry to obtain a composite filler;

[0121] S3, using dopamine to modify the surface of the composite filler, and then mixing it with ferrocene to react and obtain an autotrophic denitrification filler;

[0122] In step S1, the mass ratio of the composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose is 80:10:50:8;

[0123] In step S2, the pressure of extrusion granulation is 2.5 MPa;

[0124] The ratio of the mixture to deionized water is 60g:30mL.

[0125] The autotrophic denitrification filler is specifically prepared by the following steps:

[0126] A1. Add 6 g of the composite filler to 50 mL of Tris-HCl buffer (pH 8.5) and stir until evenly mixed. Then add 0.4 g of dopamine and stir for 4 h. The mixture is filtered, washed three times with deionized water, and dried in a 70°C oven for 10 min to obtain a polydopamine-modified composite filler.

[0127] A2. Add 6 g of polydopamine-modified composite filler and 1.5 g of ferrocene to 35 mL of deionized water, stir at 1000 rpm for 30 min, let stand for 1 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain an autotrophic denitrification filler.

[0128] The composite matrix material is specifically prepared by the following steps:

[0129] B1. Add 6g of potassium permanganate and 8g of sodium nitrite to 45mL of deionized water and stir evenly. Add 3mL of 0.5mol / L aqueous sulfuric acid solution and stir evenly. Add 12g of activated carbon and stir evenly. After standing for 2h, place in a reactor and stir at 180°C for 12h. Cool to room temperature, filter, wash three times with deionized water and three times with ethanol, and dry in a 60°C oven for 10min to obtain activated carbon loaded with manganese dioxide.

[0130] B2. 3 g of sulfur was added to 12 g of carbon disulfide, stirred, and 22 g of manganese dioxide-loaded activated carbon was added. The mixture was stirred at 600 rpm for 10 min, allowed to stand for 30 min, and the solid was collected by filtration. The solid was dried in an oven at 50 ° C for 2 h to obtain a composite activated carbon loaded with a matrix material.

[0131] B3. Add 2 g of sodium alginate and 3 g of polyvinyl alcohol to 55 mL of deionized water, stir at 100°C for 3 h, cool to room temperature, add 12 g of composite activated carbon loaded with matrix material, stir and mix at 400 r / min for 30 min, add 0.7 g of 2% calcium chloride aqueous solution, continue stirring for 30 min, filter, and dry at -4°C for 10 h to obtain a composite matrix material.

[0132] Comparative Example 3

[0133] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0134] S1. Mixing the composite matrix material, nano-iron, sodium carbonate, and carboxymethyl cellulose, and stirring at 600 rpm for 50 min to obtain a mixture;

[0135] S2. Add the mixture to deionized water, stir at 600 rpm for 20 min, continue stirring at 50° C. for 20 min, place in a granulation extruder, extrude and granulate, and dry to obtain a composite filler;

[0136] S3, mixing the composite filler with ferrocene to obtain an autotrophic denitrification filler;

[0137] In step S1, the mass ratio of the composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose is 80:10:50:8;

[0138] In step S2, the pressure of extrusion granulation is 2.5 MPa;

[0139] The ratio of the mixture to deionized water is 60g:30mL.

[0140] The autotrophic denitrification filler is specifically prepared by the following steps:

[0141] 6 g of composite filler and 1.5 g of ferrocene were added to 35 mL of deionized water, stirred at 1000 r / min for 30 min, allowed to stand for 1 h, filtered, washed with deionized water three times, and dried in an oven at 70° C. for 10 min to obtain an autotrophic denitrification filler.

[0142] The composite matrix material is specifically prepared by the following steps:

[0143] B1. Add 6g of potassium permanganate and 8g of sodium nitrite to 45mL of deionized water and stir evenly. Add 3mL of 0.5mol / L aqueous sulfuric acid solution and stir evenly. Add 12g of activated carbon and stir evenly. After standing for 2h, place in a reactor and stir at 180°C for 12h. Cool to room temperature, filter, wash three times with deionized water and three times with ethanol, and dry in a 60°C oven for 10min to obtain activated carbon loaded with manganese dioxide.

[0144] B2. 3 g of sulfur was added to 12 g of carbon disulfide, stirred, and 22 g of manganese dioxide-loaded activated carbon was added. The mixture was stirred at 600 rpm for 10 min, allowed to stand for 30 min, and the solid was collected by filtration. The solid was dried in an oven at 50 ° C for 2 h to obtain a composite activated carbon loaded with a matrix material.

[0145] B3. 7 g of composite activated carbon loaded with matrix material was added to 45 mL of ethanol and 12 mL of deionized water, stirred evenly, and 2 g of γ-aminopropyltriethoxysilane was added. The mixture was stirred at 90 ° C for 5 h, cooled to room temperature, filtered, washed three times with ethanol, washed three times with deionized water, and dried in an oven at 70 ° C for 10 min to obtain an amino-loaded matrix material composite activated carbon;

[0146] B4. Add 2 g of sodium alginate and 3 g of polyvinyl alcohol to 55 mL of deionized water, stir at 100°C for 3 h, cool to room temperature, add 12 g of amino-loaded composite activated carbon matrix material, stir and mix at 400 r / min for 30 min, add 0.7 g of 2% calcium chloride aqueous solution, continue stirring for 30 min, filter, and dry at -4°C for 10 h to obtain a composite matrix material.

[0147] Comparative Example 4

[0148] A method for increasing the specific surface area of ​​an autotrophic denitrification filler comprises the following steps:

[0149] S1. Mixing the composite matrix material, nano-iron, sodium carbonate, and carboxymethyl cellulose, and stirring at 600 rpm for 50 min to obtain a mixture;

[0150] S2. Add the mixture to deionized water, stir at 600 rpm for 20 min, continue stirring at 50° C. for 20 min, place in a granulation extruder, extrude and granulate, and dry to obtain a composite filler;

[0151] S3, using dopamine to modify the surface of the composite filler to obtain an autotrophic denitrification filler;

[0152] In step S1, the mass ratio of the composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose is 80:10:50:8;

[0153] In step S2, the pressure of extrusion granulation is 2.5 MPa;

[0154] The ratio of the mixture to deionized water is 60g:30mL.

[0155] The autotrophic denitrification filler is specifically prepared by the following steps:

[0156] 6 g of the composite filler was added to 50 mL of Tris-HCl buffer with a pH of 8.5, stirred evenly, 0.4 g of dopamine was added, stirred and reacted for 4 h, filtered, washed with deionized water 3 times, and dried in an oven at 70°C for 10 min to obtain an autotrophic denitrification filler.

[0157] The composite matrix material is specifically prepared by the following steps:

[0158] B1. Add 6g of potassium permanganate and 8g of sodium nitrite to 45mL of deionized water and stir evenly. Add 3mL of 0.5mol / L aqueous sulfuric acid solution and stir evenly. Add 12g of activated carbon and stir evenly. After standing for 2h, place in a reactor and stir at 180°C for 12h. Cool to room temperature, filter, wash three times with deionized water and three times with ethanol, and dry in a 60°C oven for 10min to obtain activated carbon loaded with manganese dioxide.

[0159] B2. 3 g of sulfur was added to 12 g of carbon disulfide, stirred, and 22 g of manganese dioxide-loaded activated carbon was added. The mixture was stirred at 600 rpm for 10 min, allowed to stand for 30 min, and the solid was collected by filtration. The solid was dried in an oven at 50 ° C for 2 h to obtain a composite activated carbon loaded with a matrix material.

[0160] B3. 7 g of composite activated carbon loaded with matrix material was added to 45 mL of ethanol and 12 mL of deionized water, stirred evenly, and 2 g of γ-aminopropyltriethoxysilane was added. The mixture was stirred at 90 ° C for 5 h, cooled to room temperature, filtered, washed three times with ethanol, washed three times with deionized water, and dried in an oven at 70 ° C for 10 min to obtain an amino-loaded matrix material composite activated carbon;

[0161] B4. Add 2 g of sodium alginate and 3 g of polyvinyl alcohol to 55 mL of deionized water, stir at 100°C for 3 h, cool to room temperature, add 12 g of amino-loaded composite activated carbon matrix material, stir and mix at 400 r / min for 30 min, add 0.7 g of 2% calcium chloride aqueous solution, continue stirring for 30 min, filter, and dry at -4°C for 10 h to obtain a composite matrix material.

[0162] The performance of the autotrophic denitrification fillers prepared in Examples 1-3 and Comparative Examples 1-4 was tested.

[0163] Mechanical strength test: The compressive strength was tested using a DL3 intelligent particle strength tester in accordance with the HG / T3927-2007 "Industrial Activated Alumina" standard.

[0164] Specific surface area test of autotrophic denitrification filler: The test was carried out using JW-BK100 specific surface analyzer in accordance with the method in GB / T19587-2017 "Determination of the specific surface area of ​​solid substances by gas adsorption BET method".

[0165] Denitrification performance test: The autotrophic denitrification filler prepared above was used for actual continuous flow wastewater treatment. The hydraulic retention time of the biological filter was 2h, the influent total nitrogen concentration was 15mg / L, and the effluent total nitrogen concentration after treatment with the autotrophic denitrification filler was recorded to calculate the total nitrogen removal rate.

[0166] The test results are shown in Table 1 below.

[0167] Table 1 Performance test of autotrophic denitrification fillers prepared in Examples 1-3 and Comparative Examples 1-4

[0168]

[0169]

[0170] It can be seen from the data in Table 1 that the autotrophic denitrification fillers prepared in Examples 1-3 have high mechanical strength and specific surface area, and have good denitrification performance.

[0171] In Comparative Example 1, the activated carbon loaded with manganese dioxide was replaced with an autotrophic denitrification filler prepared from activated carbon, and its denitrification performance and mechanical strength decreased, which proved that the synthesis of manganese dioxide in the pores of activated carbon can enhance the adsorption and fixation of the matrix material sulfur and enhance the denitrification efficiency; the activated carbon loaded with manganese dioxide serves as the supporting skeleton of the matrix material sulfur, improves the strength of the sulfur autotrophic filler, and extends the service life of the autotrophic denitrification filler.

[0172] In Comparative Example 2, the autotrophic denitrification filler prepared by replacing the composite activated carbon of the amino-loaded matrix material with the composite activated carbon of the loaded matrix material has decreased in mechanical strength, specific surface area and denitrification performance, which proves that giving the composite activated carbon of the loaded matrix material reactive groups of amino groups is beneficial to the formation of spherical particles with a cross-linked network structure on the surface of the composite activated carbon of the loaded matrix material, increasing the mechanical strength, and having a larger surface area, increasing the specific surface area, and thus improving the denitrification efficiency.

[0173] In Comparative Example 3, the polydopamine-modified composite filler was replaced with an autotrophic denitrification filler prepared by a composite filler, and its mechanical strength, specific surface area and denitrification performance decreased, proving that the polydopamine-modified composite filler has excellent adhesion, and can load ferrocene on the surface of the polydopamine-modified composite filler to form a concave-convex structure, thereby increasing the specific surface area of ​​the autotrophic denitrification filler and further improving the removal rate of total nitrogen.

[0174] In Comparative Example 4, the autotrophic denitrification filler prepared without adding ferrocene had decreased mechanical strength, specific surface area and denitrification performance, which proved that ferrocene adhered to the surface of the polydopamine-modified composite filler to form a concave-convex structure, which could fix the detached matrix material sulfur, and enhance the force of the activated carbon on the matrix material sulfur, thereby increasing the specific surface area of ​​the autotrophic denitrification filler, improving the attachment and growth of microorganisms, and improving the removal rate of total nitrogen.

[0175] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0176] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for increasing the specific surface area of ​​an autotrophic denitrification filler, characterized in that: The method comprises the following steps: S1. Mixing the composite matrix material, the iron-containing substance, the inorganic carbon source, and the binder, stirring and mixing at 500-600 rpm for 30-50 min to obtain a mixture; S2. Add the mixture to deionized water, stir at 500-600 rpm for 15-20 min, continue stirring at 40-50° C. for 15-20 min, granulate by extrusion, and dry to obtain a composite filler; S3, using dopamine to modify the surface of the composite filler, and then mixing it with ferrocene to react and obtain an autotrophic denitrification filler; The composite matrix material is prepared by modifying the composite activated carbon loaded with the matrix material with a coupling agent, and then reacting the composite activated carbon with sodium alginate, polyvinyl alcohol and calcium chloride solution, and drying the composite matrix material. The composite activated carbon loaded with matrix material is obtained by mixing activated carbon, potassium permanganate and sodium nitrite, and then mixing with the matrix material.

2. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 1, wherein: In step S1, the mass ratio of the composite matrix material, the iron-containing substance, the inorganic carbon source and the binder is (60-80):(8-10):(20-50):(5-8); In step S2, the pressure of the extrusion granulation is 2-2.5 MPa; the ratio of the mixture to deionized water is (50-60) g: (20-30) mL.

3. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 1, wherein: In step S3, the autotrophic denitrification filler is specifically prepared by the following steps: A1. The composite filler was added to Tris-HCl buffer, stirred evenly, dopamine was added, and the reaction was stirred for 3-4 hours. The mixture was filtered, washed, and dried to obtain a polydopamine-modified composite filler. A2. Add the polydopamine-modified composite filler and ferrocene to deionized water, stir at 800-1000 r / min for 20-30 min, let it stand, filter, wash, and dry to obtain an autotrophic denitrification filler.

4. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 3, wherein: In step A1, the ratio of the composite filler, Tris-HCl buffer and dopamine is (4-6) g: (40-50) mL: (0.2-0.4) g; In step A2, the ratio of the polydopamine-modified composite filler, ferrocene and deionized water is (4-6) g: (0.5-1.5) g: (25-35) mL.

5. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 1, wherein: The composite matrix material is specifically prepared by the following steps: B1. Potassium permanganate and sodium nitrite were added to deionized water and stirred evenly. Aqueous sulfuric acid solution was added and stirred evenly. Activated carbon was added and stirred evenly. After standing for 1-2 hours, the mixture was placed in a reaction vessel and stirred at 160-180°C for 10-12 hours. The mixture was cooled to room temperature, filtered, washed, and dried to obtain activated carbon loaded with manganese dioxide. B2. The matrix material was added to carbon disulfide, stirred, and activated carbon loaded with manganese dioxide was added, stirred and mixed at 500-600 r / min for 8-10 min, allowed to stand for 20-30 min, and the solid was collected by filtration. After the solid was dried, a composite activated carbon loaded with the matrix material was obtained; B3. The composite activated carbon loaded with the matrix material was added to ethanol and deionized water, stirred evenly, a coupling agent was added, and the reaction was stirred at 70-90 ° C for 4-5h, cooled to room temperature, filtered, washed, and dried to obtain an amino-loaded matrix material composite activated carbon; B4. Add sodium alginate and polyvinyl alcohol to deionized water, stir at 90-100°C for 2-3 hours, cool to room temperature, add the amino-loaded composite activated carbon matrix material, stir and mix at 300-400 r / min for 20-30 minutes, add calcium chloride aqueous solution, continue stirring for 20-30 minutes, filter, and dry to obtain a composite matrix material.

6. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 5, characterized in that: In step B1, the ratio of potassium permanganate, sodium nitrite, deionized water, aqueous sulfuric acid solution and activated carbon is (4-6) g: (7-8) g: (35-45) mL: (1-3) mL: (8-12) g.

7. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 5, characterized in that: In step B2, the mass ratio of the matrix material, carbon disulfide and activated carbon loaded with manganese dioxide is (2-3):(8-12):(18-22).

8. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 5, characterized in that: In step B3, the ratio of the composite activated carbon, ethanol, deionized water and coupling agent used in the loaded matrix material is (5-7) g: (35-45) mL: (8-12) mL: (1-2) g.

9. The method for increasing the specific surface area of ​​an autotrophic denitrification filler according to claim 5, characterized in that: In step B4, the ratio of the sodium alginate, polyvinyl alcohol, deionized water, composite activated carbon loaded with amino matrix material and calcium chloride aqueous solution is (1-2) g: (2-3) g: (45-55) mL: (8-12) g: (0.3-0.7) g.

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