Method for expanding specific surface area of autotrophic denitrification filler

Abstract

The present application relates to water treatment filler technical field, and disclose a kind of autotrophic denitrification filler specific surface area amplification method, comprising the following steps: composite matrix material, iron-containing substance, inorganic carbon source and binder are mixed, stirring is mixed, and mixed material is obtained;Mixed material is added to deionized water, stirring, after extruding granulation, drying, and composite filler is obtained;Composite filler is modified using dopamine surface, and then mixed with ferrocene to obtain autotrophic denitrification filler.Manganese dioxide is synthesized in the pore of activated carbon, the adsorption and fixation of substrate material sulfur is enhanced, and the migration and precipitation of substrate material sulfur is avoided;The activated carbon loaded with manganese dioxide serves as the support skeleton of substrate material sulfur, improving the strength of sulfur autotrophic filler;Amino group is loaded on the surface of activated carbon of substrate material, forming spherical particles with crosslinked network structure, increasing the specific surface area of autotrophic denitrification filler, and thus improving the denitrification efficiency.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of water treatment fillers, in particular to a specific surface area amplification method of autotrophic denitrification fillers. BACKGROUND

[0002] Nitrogen-containing pollutants are one of the main water environment ecological problems at present, and the main sources of nitrogen pollution are non-point source pollution in the nitrogen fertilizer application process, point source pollution caused by domestic sewage and industrial nitrogen-containing wastewater discharge, a large amount of nitrogen-containing wastewater discharged into water bodies will cause water eutrophication, cause aquatic organisms to die, and destroy biodiversity, among them, nitrate is an important factor endangering the health of water environment, and nitrate pollution in water bodies will not only affect the water environment, but also endanger human health, therefore, it is necessary to effectively remove nitrogen from sewage.

[0003] The main role of the autotrophic denitrification filler is to degrade total nitrogen and ammonia nitrogen, realize deep nitrogen and phosphorus removal, and it can reduce nitrate nitrogen in water to nitrogen without adding organic carbon source, so as to achieve the purpose of removing nitrate nitrogen, but the autotrophic denitrification filler has weak hydraulic impact resistance of sulfur, low mechanical strength, and the mutual collision of the autotrophic denitrification filler in the sewage treatment process causes the filler to break in the running process, affects the denitrification efficiency of the autotrophic denitrification filler, and the sulfur in the autotrophic denitrification filler is easy to migrate and precipitate, which affects the denitrification efficiency. SUMMARY

[0004] The application provides a specific surface area amplification method of autotrophic denitrification fillers, which solves the problems of weak hydraulic impact resistance of sulfur in the autotrophic denitrification filler and easy migration and precipitation.

[0005] The technical scheme of the application is as follows:

[0006] A specific surface area amplification method of autotrophic denitrification fillers, the method comprises the following steps:

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

[0008] S2, the mixture is added to deionized water, stirred at 500-600 rpm for 15-20 min, and then stirred at 40-50 DEG C for 15-20 min, extruded, dried, and then a composite filler is obtained;

[0009] S3, the composite filler is surface-modified by dopamine, and then mixed with ferrocene to obtain an autotrophic denitrification filler;

[0010] The composite matrix material is prepared by mixing reaction of the coupling agent modified composite activated carbon loaded substrate material, sodium alginate, polyvinyl alcohol and calcium chloride solution, and then dried.

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

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

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

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

[0015] Further, 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] Further, in step S2, the pressure for extrusion granulation is 2-2.5 MPa; and the ratio of the amount of the mixture to the amount of deionized water is (50-60) g:(20-30) mL.

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

[0018] A1. The composite filler is added to Tris-HCl buffer solution, stirred uniformly, dopamine is added, stirred and reacted for 3-4 h, filtered, washed and dried to obtain a polydopamine-modified composite filler;

[0019] A2. The polydopamine-modified composite filler and ferrocene are added to deionized water, stirred at 800-1000 r / min for 20-30 min, and after standing, filtered, washed and dried to obtain an autotrophic denitrification filler.

[0020] Further, in the above A1 reaction process, dopamine can self-polymerize on the surface of the composite filler to form polydopamine in the Tris-HCl buffer solution, 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] Further, in the above A2 reaction process, the polydopamine-modified composite filler has excellent adhesion and contains a large number of phenolic hydroxyl groups, which can be combined with ferrocene through a chemical bond, so that ferrocene adheres to the surface of the polydopamine-modified composite filler to form an autotrophic denitrification filler.

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

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

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

[0025] B1. Potassium permanganate and sodium nitrite are added to deionized water, stirred uniformly, an aqueous solution of sulfuric acid is added, stirred uniformly, activated carbon is added, stirred uniformly, and after standing for 1-2 h, it is placed in a reaction kettle and stirred at 160-180℃ for 10-12 h, cooled to room temperature, filtered, washed, and dried to obtain manganese dioxide loaded activated carbon;

[0026] B2. The matrix material is added to carbon disulfide, stirred uniformly, manganese dioxide loaded activated carbon is added, stirred at 500-600 r / min for 8-10 min, and after standing for 20-30 min, the solid is collected by filtration, and after drying, the matrix material loaded composite activated carbon is obtained;

[0027] B3. The matrix material loaded composite activated carbon is added to ethanol and deionized water, stirred uniformly, a coupling agent is added, stirred and reacted at 70-90℃ for 4-5 h, cooled to room temperature, filtered, washed, and dried to obtain amino-loaded matrix material loaded composite activated carbon;

[0028] B4. Sodium alginate and polyvinyl alcohol are added to deionized water, stirred at 90-100℃ for 2-3 h, cooled to room temperature, the amino-loaded matrix material loaded composite activated carbon is added, stirred at 300-400 r / min for 20-30 min, an aqueous calcium chloride solution is added, and stirring is continued for 20-30 min, filtered, and dried to obtain the composite matrix material.

[0029] Further, in the above B1 reaction process, the 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, has excellent adsorption performance, can adsorb the mixture of potassium permanganate and sodium nitrite into the pores of the activated carbon, after adding sulfuric acid, potassium permanganate acts as an oxidizing agent and sodium nitrite acts as a reducing agent, and a hydrothermal reaction is carried out at 160-180℃, so that the potassium permanganate and sodium nitrite undergo an oxidation-reduction reaction to form manganese dioxide crystals, and as the reaction proceeds, the manganese dioxide crystals grow to form nanometer manganese dioxide, and further synthesis of nanometer manganese dioxide with a size of 1-2 μm in the pores of the activated carbon is realized.

[0030] Further, in the above-mentioned B2 reaction process, the substrate material sulfur is dissolved in carbon disulfide, and the substrate material sulfur molecules are converted from a ring shape to a chain shape, greatly reducing the steric hindrance effect. In addition, the activated carbon loaded with manganese dioxide has excellent adsorption performance, so that the substrate material sulfur can more smoothly enter the pore channels of the activated carbon loaded with manganese dioxide to form a composite activated carbon loaded with a substrate material.

[0031] Further, in the above-mentioned B3 reaction process, the silicon hydroxyl generated by the hydrolysis of the coupling agent can be combined with the hydroxyl on the surface of the composite activated carbon loaded with a substrate material through a chemical bond, so that the coupling agent is grafted on the surface of the composite activated carbon loaded with a substrate material to form an amino-loaded composite activated carbon loaded with a substrate material.

[0032] Further, in the above-mentioned B4 reaction process, calcium chloride as a crosslinking agent can be combined with the hydroxyl in sodium alginate and polyvinyl alcohol through a chemical bond to form spherical particles with a crosslinked network structure. In addition, the amine group on the surface of the amino-loaded activated carbon loaded with a substrate material can also be combined with the hydroxyl in sodium alginate and polyvinyl alcohol through a chemical bond, so that the spherical particles with a crosslinked network structure are attached to the surface of the amino-loaded activated carbon loaded with a substrate material to form a composite substrate material.

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

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

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

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

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

[0038] Further, the substrate material is sulfur.

[0039] Further, the coupling agent is gamma-aminopropyl triethoxysilane.

[0040] The present application has the following advantages:

[0041] (1) In the technical scheme of the present application, the activated carbon has a high specific surface area and an ordered mesoporous pore structure, and can improve the dispersity of the matrix material sulfur and facilitate the adhesion and growth of the bacterial population, thereby improving the biomass in the system and the denitrification efficiency; the 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, avoiding the migration and precipitation of the matrix material sulfur, and affecting the denitrification performance of the autotrophic denitrification filler, on the other hand, the synthesized manganese dioxide can participate in the electron transfer in the microbial denitrification process, and the microorganisms can use the manganese dioxide as a terminal electron acceptor to reduce NH 4+ to NO 3- , and the reduced Mn 2+ can also act as an effective inorganic electron donor in the denitrification process, thereby facilitating the improvement of the denitrification rate and realizing the transformation and removal of nitrogen.

[0042] (2) In the technical scheme of the present application, the matrix material sulfur is dissolved in carbon disulfide, and the matrix material sulfur molecules are converted from a ring shape to a chain shape, thereby greatly reducing the steric hindrance effect; and the activated carbon loaded with manganese dioxide has excellent adsorption performance, so that the matrix material sulfur can enter the pores of the activated carbon loaded with manganese dioxide more smoothly, the formed filler has good impact load resistance, can adapt to the fluctuation of water quality conditions, and maintains stable denitrification effect; the activated carbon loaded with manganese dioxide serves as a support skeleton for the matrix material sulfur, thereby improving the strength of the sulfur autotrophic filler and prolonging the service life of the autotrophic denitrification filler.

[0043] (3) In the technical scheme of the present application, the gamma-aminopropyl triethoxysilane is grafted on the surface of the matrix material loaded composite activated carbon, thereby endowing the matrix material loaded composite activated carbon with reactive groups of amine groups, facilitating the formation of spherical particles with crosslinked network structure on the surface of the matrix material loaded composite activated carbon, increasing the mechanical strength, and having a large surface area and increasing the specific surface area; the sodium alginate, polyvinyl alcohol and calcium chloride solution form spherical particles with crosslinked network structure on the surface of the aminated matrix material loaded activated carbon, on the one hand, the formed crosslinked network structure can absorb and reduce the stress generated by the fluctuation of water quality, thereby further improving the mechanical strength of the autotrophic denitrification filler, on the other hand, the spherical particles with crosslinked network structure are attached to the surface of the aminated matrix material loaded activated carbon, thereby improving the surface roughness, having a large surface area, increasing the specific surface area of the autotrophic denitrification filler, and further improving the denitrification efficiency.

[0044] (4) In the technical scheme of the present application, ferrocene is adhered to the surface of the polydopamine modified composite filler to form a autotrophic denitrification filler. On the one hand, the polydopamine modified composite filler surface is loaded with ferrocene to form a concave-convex structure, which can fix the detached matrix material sulfur, and the active carbon enhances the force on the matrix material sulfur. On the other hand, the ferrocene is loaded on the surface of the polydopamine modified composite filler, which further increases the specific surface area of the autotrophic denitrification filler, improves the adhesion and growth of microorganisms, and further improves the removal rate of total nitrogen. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0046] The raw materials used in the embodiments of the present application are shown below, and all the reagents used are analytical grade.

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

[0048] The inorganic carbon source is sodium carbonate.

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

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

[0051] The matrix material is sulfur.

[0052] The coupling agent is gamma-aminopropyl triethoxysilane.

[0053] The ferrocene is purchased from Jinan Qida New Material Co., Ltd.

[0054] Embodiment 1

[0055] A specific surface area amplification method of autotrophic denitrification filler, comprising the following steps:

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

[0057] S2, adding the mixture into deionized water, stirring at 500 rpm for 15 min, continuing to stir at 40℃ for 15 min, placing in a granulating extruder, and after extrusion granulation and drying, obtaining a composite filler;

[0058] S3, adopting dopamine surface modification composite filler, and then mixing with ferrocene to obtain 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 mixing material and deionized water are in a ratio of 50 g:20 mL.

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

[0063] A1. 4g of the composite filler is added to 40mL of Tris-HCl buffer with pH 8.5, stirred uniformly, 0.2g of dopamine is added, stirred for 3h, filtered, washed with deionized water for 3 times, dried in a 70℃ oven for 10min, to obtain polydopamine modified composite filler;

[0064] A2. 4g of the polydopamine modified composite filler and 0.5g of ferrocene are added to 25mL of deionized water, stirred at 800r / min for 20min, and then left for 1h, filtered, washed with deionized water for 3 times, dried in a 70℃ oven for 10min, to obtain autotrophic denitrification filler.

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

[0066] B1. 4g of potassium permanganate and 7g of sodium nitrite are added to 35mL of deionized water, stirred uniformly, 1mL of 0.5mol / L sulfuric acid aqueous solution is added, stirred uniformly, 8g of activated carbon is added, stirred uniformly, left for 1h, placed in a reaction kettle, stirred at 160℃ for 10h, cooled to room temperature, filtered, washed with deionized water for 3 times, washed with ethanol for 3 times, dried in a 60℃ oven for 10min, to obtain manganese dioxide loaded activated carbon;

[0067] B2. 2g of sulfur is added to 8g of carbon disulfide, stirred uniformly, 18g of the manganese dioxide loaded activated carbon is added, stirred at 500r / min for 8min, left for 20min, the solid is collected by filtration, and the solid is dried in a 50℃ oven for 2h, to obtain the composite activated carbon loaded with the matrix material;

[0068] B3. 5 g of the composite activated carbon of the loading matrix material was added into 35 mL of ethanol and 8 mL of deionized water, stirred uniformly, 1 g of γ-aminopropyl triethoxysilane was added, stirred and reacted at 70°C for 4 h, cooled to room temperature, filtered, washed with ethanol for 3 times, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain the composite activated carbon of the aminated loading matrix material;

[0069] B4. 1 g of sodium alginate and 2 g of polyvinyl alcohol were added into 45 mL of deionized water, stirred at 90°C for 2 h, cooled to room temperature, 8 g of the composite activated carbon of the aminated loading matrix material was added, stirred and mixed at 300 r / min for 20 min, 0.3 g of 2% calcium chloride aqueous solution was added, continued to stir for 20 min, filtered, dried at -4°C for 10 h, to obtain the composite matrix material.

[0070] Example 2

[0071] A method for expanding the specific surface area of an autotrophic denitrification filler, comprising the following steps:

[0072] S1. The composite matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose were mixed, and stirred and mixed at 550 rpm for 40 min to obtain a mixture;

[0073] S2. The mixture was added into deionized water, stirred at 550 rpm for 18 min, continued to stir at 45°C for 18 min, placed in a granulating extruder, after extrusion granulation, dried to obtain the composite filler;

[0074] S3. The composite filler was surface modified by dopamine, and then mixed with ferrocene to obtain the autotrophic denitrification filler;

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

[0076] In step S2, the pressure for extrusion granulation was 2.3 MPa;

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

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

[0079] A1. 5 g of the composite filler was added into 45 mL of Tris-HCl buffer solution with pH of 8.5, stirred uniformly, 0.3 g of dopamine was added, stirred and reacted for 3.5 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain the composite filler modified by polydopamine;

[0080] A2. 5 g of polydopamine modified composite filler and 1 g of ferrocene were added to 30 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, washed with deionized water for 3 times, and dried in an oven at 70℃ for 10 min to obtain the autotrophic denitrification filler.

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

[0082] B1. 5 g of potassium permanganate and 7.5 g of sodium nitrite were added to 40 mL of deionized water, stirred uniformly, 2 mL of 0.5 mol / L sulfuric acid aqueous solution was added, stirred uniformly, 10 g of activated carbon was added, stirred uniformly, and after standing for 1.5 h, it was placed in a reaction kettle and stirred at 170℃ for 11 h, cooled to room temperature, filtered, washed with deionized water for 3 times, washed with ethanol for 3 times, and dried in an oven at 60℃ for 10 min to obtain manganese dioxide loaded activated carbon;

[0083] B2. 2.5 g of sulfur was added to 10 g of carbon disulfide, stirred uniformly, 20 g of manganese dioxide loaded activated carbon was added, stirred and mixed at 550 r / min for 9 min, and after standing for 25 min, the solid was collected by filtration, and the solid was dried in an oven at 50℃ for 2 h to obtain composite activated carbon loaded with 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 uniformly, 1.5 g of γ-aminopropyltriethoxysilane was added, and stirred and reacted at 80℃ for 4.5 h, cooled to room temperature, filtered, washed with ethanol for 3 times, washed with deionized water for 3 times, and dried in an oven at 70℃ for 10 min to obtain composite activated carbon loaded with aminated matrix material;

[0085] B4. 1.5 g of sodium alginate and 2.5 g of polyvinyl alcohol were added to 50 mL of deionized water, stirred at 95℃ for 2.5 h, cooled to room temperature, 10 g of composite activated carbon loaded with aminated matrix material was added, stirred and mixed at 350 r / min for 25 min, 0.5 g of 2% calcium chloride aqueous solution was added, and stirred for another 25 min, filtered, and dried at -4℃ for 10 h to obtain the composite matrix material.

[0086] Example 3

[0087] A method for expanding the specific surface area of an autotrophic denitrification filler, the method comprising the following steps:

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

[0089] S2, the mixture is added to deionized water, stirred at 600 rpm for 20 min, continue to stir at 50℃ for 20 min, put into a granulating extruder, after extrusion granulation, drying, to get a composite filler;

[0090] S3, the composite filler is surface modified by dopamine, and then mixed with ferrocene to obtain a autotrophic denitrification filler;

[0091] In step S1, the mass ratio of 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 amount ratio of the mixture and deionized water is 60g:30mL.

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

[0095] A1. 6g of the composite filler is added to 50mL of Tris-HCl buffer with pH 8.5, stirred uniformly, 0.4g of dopamine is added, stirred for 4h, filtered, washed with deionized water for 3 times, dried in a 70℃ oven for 10min, to get a polydopamine modified composite filler;

[0096] A2. 6g of the polydopamine modified composite filler and 1.5g of ferrocene are added to 35mL of deionized water, stirred at 1000r / min for 30min, stand for 1h, filtered, washed with deionized water for 3 times, dried in a 70℃ oven for 10min, to get an autotrophic denitrification filler.

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

[0098] B1. 6g of potassium permanganate and 8g of sodium nitrite are added to 45mL of deionized water, stirred uniformly, 3mL of 0.5mol / L sulfuric acid aqueous solution is added, stirred uniformly, 12g of activated carbon is added, stirred uniformly, stand for 2h, put into a reaction kettle, stirred at 180℃ for 12h, cooled to room temperature, filtered, washed with deionized water for 3 times, washed with ethanol for 3 times, dried in a 60℃ oven for 10min, to get a manganese dioxide loaded activated carbon;

[0099] B2. 3g of sulfur is added to 12g of carbon disulfide, stirred uniformly, 22g of the manganese dioxide loaded activated carbon is added, stirred and mixed at 600r / min for 10min, stand for 30min, filter to collect the solid, the solid is dried in a 50℃ oven for 2h, to get a composite activated carbon loaded with matrix material;

[0100] B3. 7 g of the composite activated carbon of the supporting matrix material was added into 45 mL of ethanol and 12 mL of deionized water, stirred uniformly, 2 g of γ-aminopropyl triethoxysilane was added, stirred and reacted at 90 °C for 5 h, cooled to room temperature, filtered, washed with ethanol for 3 times, washed with deionized water for 3 times, dried in an oven at 70 °C for 10 min, to obtain the composite activated carbon of the aminated supporting matrix material;

[0101] B4. 2 g of sodium alginate and 3 g of polyvinyl alcohol were added into 55 mL of deionized water, stirred at 100 °C for 3 h, cooled to room temperature, 12 g of the composite activated carbon of the aminated supporting matrix material was added, stirred and mixed at 400 r / min for 30 min, 0.7 g of 2% calcium chloride aqueous solution was added, continued to stir for 30 min, filtered, dried at -4 °C for 10 h, to obtain the composite supporting matrix material.

[0102] Comparative Example 1

[0103] A method for expanding the specific surface area of an autotrophic denitrification filler, comprising the following steps:

[0104] S1. The composite supporting matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose were mixed, and stirred and mixed at 600 rpm for 50 min, to obtain a mixture;

[0105] S2. The mixture was added into deionized water, stirred at 600 rpm for 20 min, continued to stir at 50 °C for 20 min, placed in a granulating extruder, after extrusion granulation, dried, to obtain the composite filler;

[0106] S3. The composite filler was surface modified by dopamine, and then mixed and reacted with ferrocene, to obtain the autotrophic denitrification filler;

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

[0108] In step S2, the pressure for extrusion granulation was 2.5 MPa;

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

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

[0111] A1. 6 g of the composite filler was added into 50 mL of Tris-HCl buffer solution with pH of 8.5, stirred uniformly, 0.4 g of dopamine was added, stirred and reacted for 4 h, filtered, washed with deionized water for 3 times, dried in an oven at 70 °C for 10 min, to obtain the composite filler modified by polydopamine;

[0112] A2. 6 g of polydopamine modified composite filler and 1.5 g of ferrocene were added to 35 mL of deionized water, stirred at 1000 r / min for 30 min, and after standing for 1 h, filtered, washed with deionized water for 3 times, and dried in an oven at 70 °C for 10 min to obtain the autotrophic denitrification filler.

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

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

[0115] B2. 7 g of the activated carbon loaded with the matrix material was added to 45 mL of ethanol and 12 mL of deionized water, stirred uniformly, 2 g of γ-aminopropyltriethoxysilane was added, stirred and reacted at 90 °C for 5 h, cooled to room temperature, filtered, washed with ethanol for 3 times, washed with deionized water for 3 times, and dried in an oven at 70 °C for 10 min to obtain the activated carbon loaded with the aminated matrix material;

[0116] B3. 2 g of sodium alginate and 3 g of polyvinyl alcohol were added to 55 mL of deionized water, stirred at 100 °C for 3 h, cooled to room temperature, 12 g of the activated carbon loaded with the aminated matrix material was added, stirred and mixed at 400 r / min for 30 min, 0.7 g of 2% calcium chloride aqueous solution was added, continued to stir for 30 min, filtered, and dried at -4 °C for 10 h to obtain the composite matrix material.

[0117] Comparative Example 2

[0118] A method for expanding the specific surface area of an autotrophic denitrification filler, comprising the following steps:

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

[0120] S2. The mixture was added to deionized water, stirred at 600 rpm for 20 min, and continued to stir at 50 °C for 20 min, then was placed in a granulating extruder, extruded and granulated, and dried to obtain the composite filler;

[0121] S3. The composite filler was surface modified by dopamine, and then was mixed and reacted with ferrocene to obtain the autotrophic denitrification filler;

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

[0123] The pressure of the extrusion granulation in step S2 is 2.5 MPa;

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

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

[0126] A1. 6 g of the composite filler is added to 50 mL of Tris-HCl buffer with a pH of 8.5, stirred uniformly, 0.4 g of dopamine is added, stirred for 4 h, filtered, washed with deionized water for 3 times, and dried in a 70℃ oven for 10 min to obtain a polydopamine modified composite filler;

[0127] A2. 6 g of the polydopamine modified composite filler and 1.5 g of ferrocene are added to 35 mL of deionized water, stirred at 1000 r / min for 30 min, and left to stand for 1 h, then filtered, washed with deionized water for 3 times, and dried in a 70℃ oven for 10 min to obtain the autotrophic denitrification filler.

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

[0129] B1. 6 g of potassium permanganate and 8 g of sodium nitrite are added to 45 mL of deionized water, stirred uniformly, 3 mL of 0.5 mol / L sulfuric acid aqueous solution is added, stirred uniformly, 12 g of activated carbon is added, stirred uniformly, left to stand for 2 h, placed in a reaction kettle, stirred at 180℃ for 12 h, cooled to room temperature, filtered, washed with deionized water for 3 times, washed with ethanol for 3 times, and dried in a 60℃ oven for 10 min to obtain manganese dioxide loaded activated carbon;

[0130] B2. 3 g of sulfur is added to 12 g of carbon disulfide, stirred uniformly, 22 g of the manganese dioxide loaded activated carbon is added, stirred and mixed at 600 r / min for 10 min, left to stand for 30 min, the solid is collected by filtration, and the solid is dried in a 50℃ oven for 2 h to obtain composite activated carbon loaded with matrix material;

[0131] B3. 2 g of sodium alginate and 3 g of polyvinyl alcohol are added to 55 mL of deionized water, stirred at 100℃ for 3 h, cooled to room temperature, 12 g of the composite activated carbon loaded with matrix material is added, stirred and mixed at 400 r / min for 30 min, 0.7 g of 2% calcium chloride aqueous solution is added, stirred for another 30 min, filtered, and dried at -4℃ for 10 h to obtain the composite matrix material.

[0132] Comparative Example 3

[0133] A method for expanding the specific surface area of an autotrophic denitrification filler, the method comprising the following steps:

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

[0135] S2, the mixture is added to deionized water, stirring is carried out at 600 rpm for 20 min, and stirring is continued at 50℃ for 20 min, and then the mixture is placed in a granulating extruder, extrusion granulation is carried out, and then drying is carried out to obtain a composite filler;

[0136] S3, the composite filler is mixed with ferrocene to obtain a 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 for extrusion granulation is 2.5 MPa;

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

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

[0141] 6g of the composite filler and 1.5g of ferrocene are added to 35mL of deionized water, stirring is carried out at 1000r / min for 30min, and then the mixture is left to stand for 1h, filtration is carried out, the mixture is washed with deionized water for 3 times, and then drying is carried out in a 70℃ oven for 10min to obtain the autotrophic denitrification filler.

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

[0143] B1. 6g of potassium permanganate and 8g of sodium nitrite are added to 45mL of deionized water, stirring is carried out, 3mL of sulfuric acid aqueous solution with a concentration of 0.5mol / L is added, stirring is carried out, 12g of activated carbon is added, stirring is carried out, the mixture is left to stand for 2h, the mixture is placed in a reaction kettle, stirring is carried out at 180℃ for 12h, the mixture is cooled to room temperature, filtration is carried out, the mixture is washed with deionized water for 3 times, the mixture is washed with ethanol for 3 times, and then drying is carried out in a 60℃ oven for 10min to obtain manganese dioxide loaded activated carbon;

[0144] B2. 3g of sulfur is added to 12g of carbon disulfide, stirring is carried out, 22g of the manganese dioxide loaded activated carbon is added, stirring is carried out at 600r / min for 10min, the mixture is left to stand for 30min, the solid is collected by filtration, and then the solid is dried in a 50℃ oven for 2h to obtain a composite activated carbon loaded with the matrix material;

[0145] B3. 7 g of the composite activated carbon of the supporting matrix material was added into 45 mL of ethanol and 12 mL of deionized water, stirred uniformly, 2 g of γ-aminopropyl triethoxysilane was added, stirred and reacted at 90 °C for 5 h, cooled to room temperature, filtered, washed with ethanol for 3 times, washed with deionized water for 3 times, dried in an oven at 70 °C for 10 min, to obtain the composite activated carbon of the aminated supporting matrix material;

[0146] B4. 2 g of sodium alginate and 3 g of polyvinyl alcohol were added into 55 mL of deionized water, stirred at 100 °C for 3 h, cooled to room temperature, 12 g of the composite activated carbon of the aminated supporting matrix material was added, stirred and mixed at 400 r / min for 30 min, 0.7 g of 2% calcium chloride aqueous solution was added, continued to stir for 30 min, filtered, dried at -4 °C for 10 h, to obtain the composite supporting matrix material.

[0147] Comparative Example 4

[0148] A specific surface area amplification method of an autotrophic denitrification filler, the method comprising the following steps:

[0149] S1. The composite supporting matrix material, nano-iron, sodium carbonate and carboxymethyl cellulose were mixed, and stirred and mixed at 600 rpm for 50 min, to obtain a mixture;

[0150] S2. The mixture was added into deionized water, stirred at 600 rpm for 20 min, continued to stir at 50 °C for 20 min, placed in a granulating extruder, after extrusion granulation, dried, to obtain the composite filler;

[0151] S3. The composite filler was surface modified by dopamine, to obtain the autotrophic denitrification filler;

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

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

[0154] The dosage ratio of the mixture and deionized water was 60 g:30 mL.

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

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

[0157] The composite supporting matrix material was prepared by the following steps:

[0158] B1. 6 g of potassium permanganate and 8 g of sodium nitrite were added to 45 mL of deionized water, stirred uniformly, 3 mL of 0.5 mol / L sulfuric acid aqueous solution was added, stirred uniformly, 12 g of activated carbon was added, stirred uniformly, and then placed in a reaction kettle for stirring reaction at 180℃ for 12 h. After cooling to room temperature, filtration was performed, deionized water was used for washing 3 times, ethanol was used for washing 3 times, and drying was performed in an oven at 60℃ for 10 min to obtain manganese dioxide loaded activated carbon;

[0159] B2. 3 g of sulfur was added to 12 g of carbon disulfide, stirred uniformly, 22 g of manganese dioxide loaded activated carbon was added, stirring and mixing was performed at 600 r / min for 10 min, and then standing for 30 min. The solid was collected by filtration and dried in an oven at 50℃ for 2 h to obtain a composite activated carbon loaded with matrix material;

[0160] B3. 7 g of the composite activated carbon loaded with matrix material was added to 45 mL of ethanol and 12 mL of deionized water, stirred uniformly, 2 g of γ-aminopropyltriethoxysilane was added, stirring reaction was performed at 90℃ for 5 h, and then cooling to room temperature. Filtration was performed, ethanol was used for washing 3 times, deionized water was used for washing 3 times, and drying was performed in an oven at 70℃ for 10 min to obtain a composite activated carbon loaded with aminated matrix material;

[0161] B4. 2 g of sodium alginate and 3 g of polyvinyl alcohol were added to 55 mL of deionized water, stirring was performed at 100℃ for 3 h, and then cooling to room temperature. 12 g of the composite activated carbon loaded with aminated matrix material was added, stirring and mixing was performed at 400 r / min for 30 min, 0.7 g of 2% calcium chloride aqueous solution was added, stirring was continued for 30 min, and then filtration was performed. Drying was performed at -4℃ for 10 h to obtain a composite matrix material.

[0162] The autotrophic denitrification fillers prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance detection.

[0163] Mechanical strength test: The compressive strength was tested by using a DL3 type intelligent particle strength tester according to the standard of HG / T 3927-2007 “Industrial activated alumina”.

[0164] Specific surface area test of the autotrophic denitrification filler: The specific surface area was tested by using a JW-BK100 specific surface analyzer according to the method in GB / T 19587-2017 “Gas adsorption BET method for measuring specific surface area of solid substances”.

[0165] Denitrification performance detection: The autotrophic denitrification fillers prepared above were used for actual continuous flow sewage and wastewater treatment. The hydraulic retention time of the biological filter was 2 h, the total nitrogen concentration of the influent was 15 mg / L, and the total nitrogen concentration of the effluent after treatment by 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 detection of autotrophic denitrification fillers prepared in Examples 1-3 and Comparative Examples 1-4

[0168]

[0169]

[0170] As can be seen from the data in Table 1, 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 manganese dioxide-loaded activated carbon is replaced by the autotrophic denitrification filler prepared from activated carbon, and the denitrification performance and mechanical strength thereof decrease, proving that the synthesis of manganese dioxide in the pore channel of activated carbon can enhance the adsorption and fixation of substrate material sulfur, and enhance the denitrification efficiency; the manganese dioxide-loaded activated carbon serves as a support skeleton for substrate material sulfur, improving the strength of the sulfur autotrophic filler and prolonging the service life of the autotrophic denitrification filler.

[0172] In Comparative Example 2, the autotrophic denitrification filler prepared from the composite activated carbon loaded with substrate material is replaced by the composite activated carbon loaded with substrate material, and the mechanical strength, specific surface area and denitrification performance thereof decrease, proving that the amine group, a reactive group, is given to the composite activated carbon loaded with substrate material, which is beneficial to the formation of a cross-linked network structure of spherical particles on the surface of the composite activated carbon loaded with substrate material, increases the mechanical strength, has a large surface area, increases the specific surface area, and further improves the denitrification efficiency.

[0173] In Comparative Example 3, the autotrophic denitrification filler prepared from the composite filler modified by polydopamine is replaced by the composite filler, and the mechanical strength, specific surface area and denitrification performance thereof decrease, proving that the composite filler modified by polydopamine has excellent adhesion, and can load ferrocene on the surface of the composite filler modified by polydopamine to form a concave-convex structure, increase the specific surface area of the autotrophic denitrification filler, and further improve the removal rate of total nitrogen.

[0174] In Comparative Example 4, the autotrophic denitrification filler prepared without adding ferrocene has decreased mechanical strength, specific surface area and denitrification performance, proving that the ferrocene adheres to the surface of the composite filler modified by polydopamine to form a concave-convex structure, can fix the detached substrate material sulfur, enhances the force of the active carbon on the substrate material sulfur, increases the specific surface area of the autotrophic denitrification filler, improves the adhesion and growth of microorganisms, and improves the removal rate of total nitrogen.

[0175] In the description, references to "one embodiment," "an example," "certain examples" etc. mean that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of an item in various examples or embodiments is not necessarily indicative of a frequency of occurrence in the various examples or embodiments. Moreover, descriptions of well-known methods associated are omitted so as not to obscure the disclosure.

[0176] The foregoing merely illustrates the principles of the application. Various modifications and adaptations will occur to those skilled in the art after consideration of the preceding description. All such modifications and adaptations employing the principles of the application are intended to be within the scope of the claims.

Claims

1. A method for expanding the specific surface area of an autotrophic denitrifying filler, characterized in that, The method comprises the following steps: S1. Mix the composite matrix material, iron-containing substance, inorganic carbon source and binder, stir and mix at 500-600 rpm for 30-50 min to obtain a mixture; S2. Add the mixture into deionized water, stir at 500-600 rpm for 15-20 min, continue to stir at 40-50℃ for 15-20 min, extrude and granulate, dry to obtain a composite filler; S3. The composite filler is modified by dopamine, and then mixed with ferrocene to obtain a autotrophic denitrification filler; The composite matrix material is prepared by mixing and reacting the coupling agent modified composite activated carbon loaded substrate material with sodium alginate, polyvinyl alcohol and calcium chloride solution, and then drying; The composite activated carbon loaded substrate material is prepared by mixing and reacting activated carbon, potassium permanganate and sodium nitrite, and then mixing with the substrate material; The composite matrix material is prepared by the following steps: B1. Add potassium permanganate and sodium nitrite into deionized water, stir until uniform, add aqueous sulfuric acid solution, stir until uniform, add activated carbon, stir until uniform, stand for 1-2 h, place in a reaction kettle, stir and react at 160-180℃ for 10-12 h, cool to room temperature, filter, wash and dry to obtain activated carbon loaded with manganese dioxide; B2. Add the substrate material into carbon disulfide, stir until uniform, add activated carbon loaded with manganese dioxide, stir and mix at 500-600 r / min for 8-10 min, stand for 20-30 min, filter and collect the solid, dry the solid to obtain composite activated carbon loaded with substrate material; B3. Add the composite activated carbon loaded with substrate material into ethanol and deionized water, stir until uniform, add coupling agent, stir and react at 70-90℃ for 4-5 h, cool to room temperature, filter, wash and dry to obtain amino-loaded composite activated carbon loaded with substrate material; B4. Add sodium alginate and polyvinyl alcohol into deionized water, stir at 90-100℃ for 2-3 h, cool to room temperature, add the amino-loaded composite activated carbon loaded with substrate material, stir and mix at 300-400 r / min for 20-30 min, add calcium chloride aqueous solution, continue to stir for 20-30 min, filter and dry to obtain the composite matrix material.

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

3. The specific surface area amplification method of the autotrophic denitrification filler according to claim 1, characterized in that, In step S3, the autotrophic denitrification filler is prepared by the following steps: A1. Add the composite filler into Tris-HCl buffer solution, stir until uniform, add dopamine, stir and react for 3-4 h, filter, wash and dry to obtain polydopamine modified composite filler; A2. The polydopamine modified composite filler and ferrocene were added to deionized water, stirred at 800-1000 r / min for 20-30 min, and after standing, filtered, washed, and dried to obtain the autotrophic denitrification filler.

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

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

6. The specific surface area amplification method of an autotrophic denitrification filler according to claim 1, characterized in that, In step B2, the mass ratio of the matrix material, carbon disulfide and manganese dioxide loaded activated carbon was (2-3):(8-12):(18-22).

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

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

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