A biological filler and its preparation method and application

Abstract

The present invention belongs to the technical field of sewage treatment, and particularly relates to a biological filler and its preparation method and application. The biological filler of the present invention includes a carrier, a denitrification promoter, and a polyphenol-metal network structure; the carrier has a porous structure; the polyphenol-metal network structure is loaded on the surface and inside of the carrier, and the polyphenol-metal network structure coats the denitrification promoter on the surface of the carrier, the inside of the carrier and the polyphenol-metal network. The phenolic hydroxyl groups in the polyphenols are co-deposited with metal ions, and a polyphenol-metal mesh structure is formed on the surface of the carrier and the surface of the porous structure, and the denitrification promoter is coated on the surface of the carrier, the pore surface of the porous structure and the polyphenol-metal network by the polyphenol-metal network structure, avoiding the loss of raw materials and secondary pollution caused by the dissolution of the denitrification promoter, and increasing the loading amount and loading intensity of the denitrification promoter, enriching the number and type of functional groups on the surface of the carrier, and then the denitrification rate of the biological denitrification process can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a biological filler and a preparation method and application thereof. Background Art

[0002] Denitrification refers to the process in which autotrophic or heterotrophic microorganisms use the electrons provided by the substrate to metabolize and reduce nitrate nitrogen and nitrite nitrogen into nitrogen gas under anaerobic conditions. The essence of biological denitrification is electron transfer. Microorganisms oxidize electron donors to produce electrons, which are then transferred to the substrate through the respiratory chain to complete the reduction of pollutants. The efficiency of denitrification is mainly affected by microbial activity, biofilm stability, and electron transfer efficiency. Under anaerobic conditions, microbial metabolism is slow and electron transfer efficiency is low, so the removal of pollutants often takes a long time. At present, denitrification mostly relies on the addition of organic carbon sources, but traditional organic carbon sources need to be added continuously, which greatly increases the cost of wastewater treatment.

[0003] In recent years, more and more substances that can catalyze and enhance biological denitrification reactions have been discovered by researchers, such as certain nanomaterials, redox mediators, metal ions, oligomers, etc. They can provide electrons for the microbial denitrification process, promote the secretion of microbial extracellular polymers (EPS), and improve electron transfer in the denitrification process. For example, redox mediators can act as electron donors and electron acceptors at the same time, forming a "bridging" effect to reduce the difficulty of electron transfer; cyclodextrin improves the characteristics of biofilms by promoting the production of microbial EPS, increases the activity of the electron transfer system, and thus accelerates the removal efficiency of pollutants. However, these promoters that can catalyze microbial denitrification often have good water solubility, which makes them easy to lose, unable to play a long-term role, and may also cause secondary pollution. Some studies have cross-linked β-cyclodextrin with epichlorohydrin to prepare modified biochar, which enriches the surface hydroxyl groups by acid activation of biochar; β-cyclodextrin and epichlorohydrin are mixed in alkali solution to obtain a cross-linking solution; and the activated biochar is added to the cross-linking solution to obtain β-cyclodextrin modified biochar. This study can increase the denitrification rate under low C / N conditions, while effectively alleviating the problem of nitrite accumulation and achieving more thorough denitrification. However, the process of preparing modified biochar requires the consumption of a large amount of acid, alkali and toxic organic matter, which greatly limits its practical application.

[0004] Therefore, it is of great significance to provide a biofiller that can improve the efficiency of microbial denitrification and is green and environmentally friendly. Summary of the invention

[0005] The present invention aims to solve one or more technical problems existing in the above-mentioned prior art, and at least provide a beneficial option or create conditions. Specifically, the present invention provides a biological filler, which can improve the efficiency of microbial denitrification and is green and environmentally friendly.

[0006] The inventive concept of the present invention is as follows: the biological filler of the present invention comprises a carrier, a denitrification promoter, and a polyphenol-metal network structure; the carrier has a porous structure; the polyphenol-metal network structure is loaded on the surface and inside of the carrier, and the polyphenol-metal network structure coats the denitrification promoter on the surface of the carrier, inside of the carrier, and in the polyphenol-metal network. The polyphenol substance in the polyphenol-metal network structure has good adhesion ability, the phenolic hydroxyl groups in the polyphenol substance co-precipitate and complex with metal ions, and form a polyphenol-metal network structure on the surface and inside of the carrier, and the phenolic hydroxyl groups can capture a large amount of denitrification promoter through bonding, and the denitrification promoter is coated on the surface of the carrier, inside of the carrier, and in the polyphenol-metal network by the polyphenol-metal network structure, thereby avoiding the loss of raw materials and secondary pollution caused by the dissolution of the denitrification promoter, and increasing the loading amount and loading intensity of the denitrification promoter, enriching the number and types of functional groups on the surface of the carrier, thereby improving the electron transfer efficiency in the denitrification process, and improving the denitrification rate in the biological denitrification process.

[0007] Therefore, a first aspect of the present invention provides a biofiller.

[0008] Specifically, the biological filler includes a carrier, a denitrification promoter, and a polyphenol-metal network structure;

[0009] The carrier has a porous structure;

[0010] The polyphenol-metal network structure is loaded on the surface and inside of the carrier, and the polyphenol-metal network structure covers the denitrification promoter on the surface of the carrier, inside of the carrier and in the polyphenol-metal network.

[0011] Specifically, the interior of the carrier refers to the pore surface of the porous structure of the carrier.

[0012] Specifically, the functional groups on the surface of the carrier include hydroxyl functional groups. The presence of hydroxyl functional groups can promote the formation and stability of biofilms, and the hydrophilicity of hydroxyl groups helps microorganisms form a continuous and dense biofilm layer on the surface of the biological filler, which helps to improve the impact resistance and load resistance of the biofilm. At the same time, the hydroxyl functional groups have a certain adsorption capacity and can chemically react or physically adsorb certain pollutants in sewage to remove them from the water. This adsorption effect helps to improve the overall treatment effect of the biological filler.

[0013] Preferably, the carrier comprises at least one of ore materials, carbon-based materials, and porous nanocomposite materials.

[0014] Preferably, the porous nanocomposite material includes at least one of an inorganic porous nanomaterial and an organic porous nanomaterial.

[0015] Preferably, the inorganic porous nanomaterial includes at least one of porous silica and porous hydroxyapatite.

[0016] Specifically, the inorganic porous nanomaterial has good mechanical properties and stability.

[0017] Preferably, the organic porous nanomaterial includes at least one of a porous polymer and a porous carbon material.

[0018] Preferably, the porous polymer comprises at least one of intrinsically microporous polymers (PIMs), hyper-crosslinked polymers (HCPs), and conjugated microporous polymers (CMPs).

[0019] Specifically, the organic porous nanomaterial has good biocompatibility and processability.

[0020] Preferably, the carrier includes at least one of zeolite, kaolinite, biochar, graphene, and carbon nanotubes.

[0021] Preferably, the particle size of the carrier is 1-11 mm; further preferably, the particle size of the carrier is 1-10 mm.

[0022] Preferably, the pore size of the porous structure is 0.1-200 nm; further preferably, the pore size of the porous structure is 1-100 nm.

[0023] Preferably, the denitrification promoter includes at least one of a substance that provides electrons for microbial denitrification and a substance that promotes biological electron transfer efficiency.

[0024] Further preferably, the denitrification promoter includes at least one of cyclodextrin, quinone substances and vitamins.

[0025] Preferably, the cyclodextrin includes at least one of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin.

[0026] Further preferably, the cyclodextrin comprises β-cyclodextrin.

[0027] Preferably, the quinone substance includes at least one of 9,10-anthraquinone, 2-hydroxy-1,4-naphthoquinone, sodium anthraquinone-2-sulfonate, and menadione; further preferably, the quinone substance includes sodium anthraquinone-2-sulfonate.

[0028] Specifically, β-cyclodextrin can promote the synthesis of electron donors (such as nicotinamide adenine dinucleotide (reduced state) (NADH) and energy carriers (such as adenosine triphosphate (ATP)) used in the denitrification process by regulating the carbon metabolism pathway in microorganisms, which helps to improve the supply efficiency of microbial substrate metabolism to denitrification, thereby enhancing the denitrification effect.

[0029] Specifically, as a typical redox mediator, anthraquinone-2-sulfonate sodium can accelerate the electron transfer rate between electron donors and electron acceptors in redox reactions. Anthraquinone-2-sulfonate sodium can alleviate the inhibition of the electron transfer rate by respiratory chain inhibitors, restore part of the intracellular electron transfer (IET), and make nitrate (NO 3 - -N) is more effectively converted into nitrogen. This accelerated electron transfer directly promotes the denitrification reaction.

[0030] Preferably, the vitamins include vitamin B1.

[0031] Preferably, the polyphenols in the polyphenol-metal network structure include at least one of tannic acid, gallic acid, catechin and resveratrol.

[0032] Further preferably, the polyphenols in the polyphenol-metal network structure include tannic acid.

[0033] Preferably, the metal ions in the polyphenol-metal network structure include Fe 2+ , Fe 3+ , Cu 2+ , Mn 2+ 、Zn 2+ , Ca 2+ Mg 2+ At least one of .

[0034] Specifically, the polyphenols in the polyphenol-metal network structure have a large number of phenolic hydroxyl groups and have good adhesion to various surfaces, so that the polyphenols can adhere to the surface of the carrier and the pore surface of the porous structure inside the carrier, and due to the presence of a large number of phenolic hydroxyl groups in the polyphenolic substance and the presence of hydroxyl groups of the denitrification promoter, the polyphenolic substance can capture a large amount of denitrification promoter through bonding, so that the denitrification promoter can be distributed on the surface of the carrier and the pore surface of the porous structure inside the carrier. At the same time, the polyphenolic substance adhered to the surface of the carrier and the pore surface of the porous structure inside the carrier can chelate with metal ions to form a polyphenol-metal network, and the denitrification promoter is coated on the surface of the carrier, the inside of the carrier and the polyphenol-metal network, and finally a biological filler with a specific structure of the present application is obtained.

[0035] The second aspect of the present invention provides a method for preparing the biological filler described in the first aspect of the present invention.

[0036] Specifically, the method for preparing the biological filler comprises the following steps:

[0037] (1) mixing the carrier and solution A to obtain a mixture;

[0038] (2) mixing solution B with the mixture obtained in step (1) to obtain the biofiller;

[0039] The solution A comprises polyphenolic substances and a denitrification promoter; the solution B comprises a metal salt.

[0040] Specifically, the present invention utilizes a biomimetic codeposition method to prepare a biofiller, polyphenols have good adhesion to many surfaces, phenolic hydroxyl groups in the polyphenols are codeposited and complexed with metal ions, a polyphenol-metal network structure is formed on the surface of a carrier and inside the carrier, and the phenolic hydroxyl groups can capture a large amount of denitrification promoters through bonding, the polyphenol-metal network structure can coat the denitrification promoter, thereby increasing the loading amount and loading intensity of the denitrification promoter, and enriching the number and types of functional groups on the surface of the carrier, thereby increasing the electron transfer efficiency in the denitrification process, and increasing the denitrification rate in the biological denitrification process. In addition, under the codeposition of polyphenols and metal ions, the denitrification promoter is coated on the surface of the carrier, inside the carrier, and in the polyphenol-metal network by the polyphenol-metal network structure, thereby avoiding the loss of raw materials and secondary pollution caused by the dissolution of the denitrification promoter, and can play a long-term role, and is green and environmentally friendly. Compared with traditional acid-base modification methods, the modification method based on bionic co-deposition does not use strong acids, strong bases and toxic organic matter. It is easy to operate, green and non-toxic, has good water purification effect, and has good application prospects.

[0041] Preferably, in the solution A, the concentration of the polyphenolic substance is 1.8-90 mM; further preferably, in the solution A, the concentration of the polyphenolic substance is 2-80 mM.

[0042] Preferably, in the solution A, the concentration of the denitrification promoter is 1.8-22 g / L; further preferably, in the solution A, the concentration of the denitrification promoter is 2-20 g / L.

[0043] Preferably, in the solution B, the concentration of the metal salt is 9-270 mM; further preferably, in the solution B, the concentration of the metal salt is 10-250 mM.

[0044] Preferably, the polyphenolic substance includes at least one of tannic acid, gallic acid, catechin and resveratrol.

[0045] Further preferably, the polyphenolic substance includes tannic acid.

[0046] Preferably, the metal salt includes at least one of a divalent iron salt, a trivalent iron salt, a copper salt, a manganese salt, a zinc salt, a calcium salt, and a magnesium salt.

[0047] Further preferably, the metal salt comprises FeSO 4 、MnCl 2 、FeCl3 At least one of .

[0048] Preferably, in step (1), the mixing time is 1-8 h; further preferably, in step (1), the mixing time is 4-6 h.

[0049] Preferably, in step (2), the mixing time is 2-12 hours; further preferably, in step (2), the mixing time is 6-8 hours.

[0050] Preferably, in step (1), the mixing is performed by immersing the carrier into solution A.

[0051] Preferably, in step (2), the mixing is performed by immersing the mixture obtained in step (1) into solution B.

[0052] Specifically, by immersing the carrier into solution A, the carrier fully absorbs the polyphenolic substance and the denitrification promoter in solution A. By immersing the mixture into solution B, the phenolic hydroxyl groups in the polyphenolic substance and the metal ions are co-deposited on the surface of the carrier and the surface of the porous structure to form a polyphenol-metal network structure, and the denitrification promoter is coated on the surface of the carrier, the inside of the carrier and the polyphenol-metal network, thereby increasing the loading amount and loading intensity of the denitrification promoter, thereby increasing the denitrification rate of the biological denitrification process, and avoiding the loss of raw materials and secondary pollution caused by the dissolution of the denitrification promoter.

[0053] Preferably, in step (1), the mixing further includes a filtering process.

[0054] Preferably, in step (2), the mixing further includes filtering, washing and drying processes.

[0055] Preferably, the drying temperature is lower than 100°C, and more preferably, the drying temperature is 50-70°C.

[0056] The third aspect of the present invention provides a use of the biological filler described in the first aspect of the present invention in sewage treatment.

[0057] Preferably, the sewage treatment includes sewage denitrification and denitrification treatment.

[0058] Preferably, during the sewage treatment, the mass ratio of the biological filler to the sludge in the sewage is (0.5-2):10.

[0059] Further preferably, during the sewage treatment, the mass ratio of the biological filler to the sludge in the sewage is (1.0-1.5):10.

[0060] Preferably, during the sewage treatment, the biological filler and sludge are mixed in a manner including free suspension and fixed suspension.

[0061] Preferably, during the sewage treatment, the biological filler and sludge are mixed in a fixed suspension manner.

[0062] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0063] (1) The polyphenols in the polyphenol-metal network structure of the present invention have good adhesion ability, and the phenolic hydroxyl groups in the polyphenols are co-precipitated and complexed with metal ions to form a polyphenol-metal network structure on the surface of the carrier and the pore surface of the porous structure of the carrier. The phenolic hydroxyl groups can capture a large amount of denitrification promoter by bonding, and the denitrification promoter is coated on the surface of the carrier, the pore surface of the porous structure and the polyphenol-metal network by the polyphenol-metal network structure, thereby avoiding the loss of raw materials and secondary pollution caused by the dissolution of the denitrification promoter, increasing the loading amount and loading intensity of the denitrification promoter, enriching the number and types of functional groups on the surface of the carrier, and thus improving the electron transfer efficiency in the denitrification process and the denitrification rate in the biological denitrification process.

[0064] (2) Compared with the traditional acid-base modification method, the modification method of the present invention based on bionic co-deposition to prepare biological fillers does not use strong acids, strong bases and toxic organic matter, is easy to operate, green and non-toxic, has good water purification effect, and has good application prospects. DETAILED DESCRIPTION

[0065] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0066] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0067] Example 1

[0068] A biological filler, comprising a carrier zeolite, a denitrification promoter β-cyclodextrin, and tannic acid-Fe 2+ Network structure; The carrier has a porous structure; Tannic acid-Fe 2+ The network structure is loaded on the surface of zeolite and the pore surface of the porous structure, and the tannic acid-Fe 2+ The network structure encapsulates β-cyclodextrin on the surface of zeolite, the pore surface of the porous structure, and the tannic acid-Fe 2+ In the network structure.

[0069] A method for preparing a biological filler comprises the following steps:

[0070] 2 g of β-cyclodextrin was added to 200 mL of 2 mM tannic acid solution to obtain solution A. 50 g of zeolite with a particle size of 1 mm was immersed in solution A for 2 h and filtered to obtain zeolite loaded with tannic acid and β-cyclodextrin. 2 g of FeSO 4 7H 2 O was dissolved in 200 mL of deionized water to obtain solution B; the zeolite loaded with tannic acid and β-cyclodextrin was immersed in solution B for 4 h. 2+ Co-precipitation occurs to form tannic acid-Fe 2+ The network structure was filtered, rinsed with deionized water for three times, and then placed in an oven and dried at 60°C for 6 h to obtain a modified filler, namely the biofiller.

[0071] Example 2

[0072] A biological filler comprising a carrier zeolite, a denitrification promoter β-cyclodextrin, tannic acid-Mn 2+ Network structure; The carrier has a porous structure; Tannic acid-Mn 2+ The network structure is loaded on the surface of zeolite and the pore surface of the porous structure, and the tannic acid-Mn 2+ The network structure encapsulates β-cyclodextrin on the surface of zeolite, the pore surface of the porous structure, and tannic acid-Mn 2+ In the network structure.

[0073] A method for preparing a biological filler comprises the following steps:

[0074] 4 g of β-cyclodextrin was added to 200 mL of 10 mM tannic acid solution to obtain solution A. 50 g of zeolite with a particle size of 1 mm was immersed in solution A for 6 h and filtered to obtain zeolite loaded with tannic acid and β-cyclodextrin. 2 g of MnCl 2 ·4H 2 O was dissolved in 200 mL of deionized water to obtain solution B; the zeolite loaded with tannic acid and β-cyclodextrin was immersed in solution B for 8 h. 2+ Co-precipitation occurs to form tannic acid-Mn 2+ The network structure was filtered, rinsed with deionized water for three times, and then dried in an oven at 60°C for 6 h to obtain a modified filler, namely a biofiller.

[0075] Example 3

[0076] A biological filler, comprising a carrier biochar, a denitrification promoter β-cyclodextrin, and gallic acid-Fe 3+ Network structure; The carrier has a porous structure; Gallic acid-Fe 3+The network structure is loaded on the surface of biochar and the pore surface of the porous structure, and the gallic acid-Fe 3+ The network structure encapsulates β-cyclodextrin on the surface of biochar, the pore surface of the porous structure, and gallic acid-Fe 3+ In the network structure.

[0077] A method for preparing a biological filler comprises the following steps:

[0078] 4 g of β-cyclodextrin was added to 200 mL of 60 mM gallic acid solution to obtain solution A. 50 g of biochar with a particle size of 3 mm was immersed in solution A for 6 h and filtered to obtain biochar loaded with gallic acid and β-cyclodextrin. 6 g of FeCl 3 Dissolved in 200 mL of deionized water to obtain solution B; the biochar loaded with gallic acid and β-cyclodextrin was immersed in solution B for 8 h. 3+ Co-precipitation occurs to form tannic acid-Fe 3+ The resulting mixture was filtered, rinsed with deionized water for three times, and then dried in an oven at 60°C for 6 h to obtain a modified filler, namely a biofiller.

[0079] Example 4

[0080] A biological filler, comprising a carrier zeolite, a denitrification promoter anthraquinone-2-sodium sulfonate, and tannic acid-Fe 3+ Network structure; The carrier has a porous structure; Tannic acid-Fe 3+ The network structure is loaded on the surface of zeolite and the pore surface of the porous structure, and the tannic acid-Fe 3+ The network structure coats sodium anthraquinone-2-sulfonate on the surface of the zeolite, the pore surface of the porous structure, and the tannic acid-Fe 3+ In the network structure.

[0081] A method for preparing a biological filler comprises the following steps:

[0082] 2 g of sodium anthraquinone-2-sulfonate was added to 200 mL of 2 mM tannic acid solution to obtain solution A. 50 g of zeolite with a particle size of 2 mm was immersed in solution A for 4 h and filtered to obtain zeolite loaded with tannic acid and sodium anthraquinone-2-sulfonate. 2 g of FeCl 3 Dissolved in 200 mL of deionized water to obtain solution B. The zeolite loaded with tannic acid and sodium anthraquinone-2-sulfonate was immersed in solution B for 4 h. Tannic acid and Fe 3+ Co-precipitation occurs to form tannic acid-Fe 3+ The resulting product was filtered, rinsed with deionized water for three times, and dried in an oven at 60 °C for 6 h to obtain a modified filler, namely a biofiller.

[0083] Example 5

[0084] A biological filler, comprising a carrier biochar, a denitrification promoter β-cyclodextrin, and tannic acid-Fe 2+ Network structure; The carrier has a porous structure; Tannic acid-Fe 2+ The network structure is loaded on the surface of biochar and the pore surface of the porous structure, and the tannic acid-Fe 2+ The network structure encapsulates β-cyclodextrin on the surface of biochar, the pore surface of the porous structure, and the tannic acid-Fe 2+ In the network structure.

[0085] A method for preparing a biological filler comprises the following steps:

[0086] 1 g of β-cyclodextrin was added to 200 mL of 2 mM tannic acid solution to obtain solution A. 50 g of biochar with a particle size of 1 mm was immersed in solution A for 2 h and filtered to obtain biochar loaded with tannic acid and β-cyclodextrin. 2 g of FeSO 4 7H 2 O was dissolved in 200 mL of deionized water to obtain solution B. The biochar loaded with tannic acid and β-cyclodextrin was immersed in solution B for 4 h. 2+ Co-precipitation occurs to form tannic acid-Fe 2+ The network structure was filtered, rinsed with deionized water for three times, and dried in an oven at 60°C for 6 h to obtain a modified filler, namely a biofiller.

[0087] Comparative Example 1

[0088] The difference between Comparative Example 1 and Example 1 is that no FeSO was added during the preparation process of Comparative Example 1. 4 7H 2 O, that is, no metal ions are loaded on the carrier, and no polyphenol-metal network structure is formed, and the rest is the same as in Example 1.

[0089] Specifically, the preparation method of the biological filler in Comparative Example 1 comprises the following steps:

[0090] 2 g of β-cyclodextrin was added to 200 mL of a 2 mM tannic acid solution to obtain solution A, 50 g of zeolite with a particle size of 1 mm was immersed in solution A for 2 hours, and the solution was filtered to obtain zeolite loaded with tannic acid and β-cyclodextrin; the zeolite loaded with tannic acid and β-cyclodextrin was rinsed with deionized water for 3 times, and dried in an oven at 60° C. for 6 hours to obtain a biofiller.

[0091] Comparative Example 2

[0092] The difference between Comparative Example 2 and Example 1 is that during the preparation process of Comparative Example 1, an equal amount of pure water is used to replace the tannic acid solution, that is, tannic acid is not loaded on the carrier, and a polyphenol-metal network structure is not formed. The rest is the same as Example 1.

[0093] Specifically, the preparation method of the biological filler in Comparative Example 2 comprises the following steps:

[0094] 2 g of β-cyclodextrin was added to 200 mL of pure water to obtain solution A. 50 g of zeolite with a particle size of 1 mm was immersed in solution A for 2 h and filtered to obtain zeolite loaded with β-cyclodextrin. 2 g of FeSO 4 7H 2 O was dissolved in 200 mL of deionized water to obtain solution B, and the zeolite loaded with β-cyclodextrin was immersed in solution B for 4 h. After filtration, the zeolite loaded with β-cyclodextrin and Fe was obtained. 2+ Zeolite; β-cyclodextrin and Fe 2+ The zeolite was rinsed with deionized water three times, placed in an oven and dried at 60°C for 6 h to obtain a biofiller.

[0095] Comparative Example 3

[0096] The difference between Comparative Example 3 and Example 1 is that no β-cyclodextrin is added in the preparation process of Comparative Example 3, that is, no β-cyclodextrin is loaded on the carrier, and the rest is the same as Example 1.

[0097] Specifically, the preparation method of the biological filler in Comparative Example 3 includes the following steps:

[0098] Tannic acid was prepared into a 200 ml, 2 mM solution to obtain solution A. 50 g of zeolite with a particle size of 1 mm was immersed in solution A for 2 h and filtered to obtain zeolite loaded with tannic acid. 2 g of FeSO 4 7H 2 O was dissolved in 200 mL of deionized water to obtain solution B; the zeolite loaded with tannic acid was immersed in solution B for 4 h. 2+ Co-precipitation occurs to form tannic acid-Fe 2+ The product was filtered, rinsed with deionized water for three times, and then placed in an oven and dried at 60°C for 6 h to obtain a biofiller.

[0099] Comparative Example 4

[0100] The difference between Comparative Example 4 and Example 1 is that no β-cyclodextrin, tannic acid and Fe are added during the preparation process of Comparative Example 4. 2+ , that is, the carrier is not loaded with β-cyclodextrin, tannic acid and Fe 2+ , nor does it form tannic acid-Fe 2+The network structure and other aspects are the same as those in Example 1.

[0101] Specifically, the preparation method of the biological filler in Comparative Example 4 comprises the following steps:

[0102] 50 g of zeolite with a particle size of 1 mm was immersed in 200 ml of pure water for 6 hours. After filtering, the mixture was placed in an oven and dried at 60° C. for 6 hours to obtain a biological filler.

[0103] Performance Testing

[0104] Test 1: The actual sewage was treated with the biological fillers prepared in Examples 1-5 and Comparative Examples 1-4. The sludge concentration in the anoxic tank was 5000 mg / L, the hydraulic retention time was 6 h, the influent total nitrogen concentration was 50 mg / L, and the dosage of the biological fillers in Examples 1-5 and Comparative Examples 1-4 was 0.5 g / L respectively. The biological fillers were directly put into the tank and mixed with the sludge in a free suspension manner. The treatment was run for 3 days, 6 days, 9 days, 12 days, 20 days, and 30 days respectively, and then the total nitrogen concentration was determined, and the denitrification efficiency was calculated.

[0105] Test 2: The biological fillers prepared in Examples 1-5 and Comparative Examples 1-4 were loaded into ball rings and set up in the middle of the anoxic tank, and the other conditions were the same as those in Test Example 1. That is, the sludge concentration in the anoxic tank was 5000 mg / L, the hydraulic retention time was 6 h, the total nitrogen concentration of the influent was 50 mg / L, the dosage of the biological filler was 0.5 g / L, the biological filler was loaded into a ball ring and set up in the middle of the anoxic tank, and the mixing method with the sludge was fixed suspension, and the treatment was run for 3 days, 6 days, 9 days, 12 days, 20 days, and 30 days, and then the total nitrogen concentration was measured, and the denitrification efficiency was calculated.

[0106] The denitrification efficiency (η) can be calculated by the following formula:

[0107]

[0108] Where: η represents the denitrification efficiency;

[0109] C in It indicates the total nitrogen concentration (influent) before treatment on the day, in mg / L;

[0110] C out It indicates the total nitrogen concentration (outlet) after treatment on the day, in mg / L.

[0111] The method for determining total nitrogen concentration refers to (HJ 636-2012) "Determination of total nitrogen in water quality - Alkaline potassium persulfate digestion ultraviolet spectrophotometry".

[0112] The denitrification efficiency of the biofillers prepared in Examples 1-5 and Comparative Examples 1-4 in Test 1 and Test 2 is shown in Table 1.

[0113] Table 1: Denitrification efficiency of biological fillers prepared in Examples 1-5 and Comparative Examples 1-4

[0114]

[0115] It can be seen from Table 1 that after 30 days of operation, the denitrification efficiency of the biological filler of the present invention can basically reach more than 98%. Even when the biological filler and sludge are mixed in a fixed suspension manner, the denitrification efficiency can even reach 99.8%, which has a good denitrification efficiency.

[0116] Comparative Example 1: No FeSO was added 4 7H 2 O, that is, no metal ions are loaded on the carrier, and no polyphenol-metal network structure is formed, so that no matter how the biological filler and sludge of Comparative Example 1 are mixed, its denitrification efficiency is significantly lower than that of Example 1. It shows that in the biological filler, the polyphenol-metal network structure formed by metal ions and polyphenol substances plays an important role in improving the denitrification efficiency, because the polyphenol-metal network structure can coat the denitrification promoter, increase the loading amount and loading intensity of the denitrification promoter, and enrich the number and types of functional groups on the carrier surface, thereby improving the electron transfer efficiency in the denitrification process and improving the denitrification rate in the biological denitrification process.

[0117] In the preparation process of Comparative Example 2, an equal amount of pure water was used to replace the tannic acid solution, that is, no tannic acid was loaded on the carrier, and no polyphenol-metal network structure was formed, so that no matter how the biological filler and sludge of Comparative Example 2 were mixed, the denitrification efficiency was significantly lower than that of Example 1. This shows that the polyphenol-metal network structure in the biological filler plays an important role in improving the denitrification efficiency.

[0118] In the preparation process of Comparative Example 3, β-cyclodextrin was not added, that is, the carrier was not loaded with β-cyclodextrin, so that no matter how the biological filler and sludge of Comparative Example 3 were mixed, the denitrification efficiency was significantly lower than that of Example 1. This shows that the denitrification promoter plays an important role in improving the denitrification efficiency.

[0119] Comparative Example 4 does not add β-cyclodextrin, tannic acid and Fe 2+ , that is, the carrier is not loaded with β-cyclodextrin, tannic acid and Fe 2 + , nor does it form tannic acid-Fe 2+ The network structure makes the denitrification efficiency of the biological filler and the sludge in Comparative Example 4 significantly lower than that in Example 1 regardless of the mixing method. 2+ , Tannic acid-Fe 2+ The combined effect of network structure and denitrification promoter plays an important role in improving denitrification efficiency.

[0120] From the above analysis, it can be seen that in the preparation process of biological fillers, polyphenols, denitrification promoters and metal salts are indispensable. Without any one of the polyphenols or metal salts, the polyphenol-metal network structure cannot be formed, and the denitrification promoter cannot be coated on the surface of the carrier, the pore surface of the porous structure and the polyphenol-metal network, which reduces the loading amount and loading intensity of the denitrification promoter, reduces the electron transfer efficiency in the denitrification process, and thus reduces the denitrification rate of the biological denitrification process.

[0121] In summary, the present invention loads polyphenol substances and denitrification promoters on a carrier, and forms a polyphenol-metal mesh structure by adding metal salts. The polyphenol-metal network structure can coat the denitrification promoter, thereby increasing the loading amount and loading strength of the denitrification promoter, and enriching the number and types of functional groups on the surface of the carrier, thereby increasing the electron transfer efficiency in the denitrification process and increasing the denitrification rate in the biological denitrification process. At the same time, the denitrification promoter is coated on the surface of the carrier, the pore surface of the porous structure, and the polyphenol-metal network by the polyphenol-metal network structure, which can avoid the loss of raw materials and secondary pollution caused by the dissolution of the denitrification promoter, can play a long-term role, and is green and environmentally friendly.

[0122] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A biological filler, characterized in that: It includes a carrier, a denitrification promoter, and a polyphenol-metal network structure; The carrier has a porous structure; The polyphenol-metal network structure is loaded on the surface and inside of the carrier, and the polyphenol-metal network structure covers the denitrification promoter on the surface of the carrier, inside of the carrier and in the polyphenol-metal network; The carrier includes at least one of ore materials, carbon-based materials, and porous nanocomposite materials; The denitrification promoter includes at least one of a substance that provides electrons for microbial denitrification and a substance that promotes biological electron transfer efficiency; The polyphenols in the polyphenol-metal network structure include at least one of tannic acid, gallic acid, catechin and resveratrol; The metal ions in the polyphenol-metal network structure include Fe 2+ , Fe 3+ , Cu 2+ , Mn 2+ 、Zn 2+ , Ca 2+ Mg 2+ At least one of .

2. The biological filler according to claim 1, characterized in that: The particle size of the carrier is 1-11 mm; and / or the pore size of the porous structure is 0.1-200 nm.

3. The method for preparing the biological filler according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) mixing the carrier and solution A to obtain a mixture; (2) mixing solution B and the mixture obtained in step (1) to prepare the biofiller; The solution A comprises polyphenolic substances and a denitrification promoter; the solution B comprises a metal salt.

4. The preparation method according to claim 3, characterized in that: In the solution A, the concentration of the polyphenolic substance is 1.8-90 mM; and / or, in the solution A, the concentration of the denitrification promoter is 1.8-22 g / L; and / or, in the solution B, the concentration of the metal salt is 9-270 mM.

5. The preparation method according to claim 3, characterized in that: The polyphenolic substance includes at least one of tannic acid, gallic acid, catechin and resveratrol; the metal salt includes at least one of divalent iron salt, trivalent iron salt, copper salt, manganese salt, zinc salt, calcium salt and magnesium salt.

6. The preparation method according to claim 3, characterized in that: In step (1), the mixing time is 1-8 hours; and / or, in step (2), the mixing time is 2-12 hours.

7. Use of the biological filler according to any one of claims 1 to 2 in sewage treatment.

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