A medium-quality filter material for denitrification biological filter and its manufacturing method

Abstract

The application provides a medium filter material for a denitrification biofilter and a manufacturing method. The medium filter material comprises the following raw material components in parts by weight: 100 parts of epoxy resin, 10-30 parts of curing agent, 5-15 parts of diluent, 5-15 parts of modifier, 10-30 parts of filler and 1-5 parts of coupling agent. The medium filter material has an average particle size of 3-5 mm, a density of 1.0-1.5 g / cm 3 , a porosity of 40-50%, and a specific surface area of greater than 1500 m 2 / m 3 . The manufacturing method comprises uniformly mixing the epoxy resin, the curing agent, the diluent, the modifier, the filler and the coupling agent, and then curing and forming and shearing. The medium filter material has good physical properties and chemical stability, improves the filter treatment efficiency and the service life of the filter material, and reduces the operation cost of the filter.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and particularly relates to a medium-quality filter material for a denitrification biological filter and a manufacturing method thereof. Background Art

[0002] To reduce total nitrogen concentrations and achieve standard wastewater discharge, many sewage treatment plants are undergoing upgrades and installing denitrification filter systems. Filter media is undoubtedly the core and most critical component of a denitrification filter system. It not only influences the rate at which biofilms form and the growth of the biofilm, thus affecting treatment efficiency, but also affects backwash energy consumption. Therefore, optimizing and upgrading filter media is crucial for improving the quality and efficiency of denitrification filter systems, both from a technological and operational perspective.

[0003] Depending on the type of denitrification filter, the filter media commonly used are also different. Light filter media filters generally use polystyrene light filter media with a density of 0.45-0.55g / cm 3 During normal operation, the filter media floats on the water surface, so it is necessary to install an upper filter plate to prevent the filter media from flowing out with the outlet water. At the same time, since the lightweight filter media floats on the water surface, the lightweight filter media filter tank adopts gravity water washing. Due to the characteristics of lightweight filter media, the construction of lightweight filter media filter tanks is difficult, and the filter media is easy to flow out with the backwash water. General upflow denitrification filters and denitrification deep bed filters mostly use heavy filter media such as ceramsite, zeolite, coke, quartz sand, activated carbon, etc., but these filter media also have many problems, such as the filter media density is large, resulting in high backwash energy consumption, the filter media strength decreases after long-term immersion and erosion, the wear rate and breakage rate increase, and some types of filter media need to be sintered at high temperature, which has high production costs and will cause environmental pollution. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a medium-quality filter material for a denitrification biological filter and a manufacturing method. The medium-quality filter material of the present invention has the characteristics of both light-weight filter material and heavy-weight filter material, and through optimization and improvement, overcomes the respective limitations of light-weight filter material and heavy-weight filter material, providing a new idea for the selection of filter material for denitrification filters.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a medium-quality filter material comprising the following raw material components in parts by weight: 100 parts epoxy resin, 10-30 parts curing agent, 5-15 parts diluent, 5-15 parts modifier, 10-30 parts filler, and 1-5 parts coupling agent. The medium-quality filter material has an average particle size of 3-5 mm and a density of 1.0-1.5 g / cm 3 , porosity is 40-50%, specific surface area is greater than 1500m2 / m 3 .

[0007] Furthermore, in order to ensure the strength and effect of the epoxy resin, the epoxy value of the epoxy resin is greater than 0.4.

[0008] Furthermore, since the epoxy value of the selected epoxy resin is greater than 0.4, the brittleness of the epoxy resin is relatively high. In order to make the epoxy resin have a certain hardness and facilitate later shearing or use as a filter material, a certain proportion of a curing agent is added, and the curing agent is a room temperature curing agent or a high temperature curing agent; the room temperature curing agent includes one or more of alicyclic polyamines and amidoamine room temperature curing agents, and the high temperature curing agent is an aromatic polyamine high temperature curing agent, such as one or more of meta-phenylenediamine, meta-phenylenediamine, DDM, DDS, etc.

[0009] Furthermore, to reduce the viscosity of the thermosetting resin, both to facilitate mixing after the subsequent addition of fillers and to prevent adhesion of the filter media after fabrication, a certain amount of diluent is added. Because the action of inert diluents is difficult to control, reactive diluents are selected, including one or more of propylene oxide butyl ether 660, propylene oxide phenyl ether 690, dipropylene oxide ethyl ether 669, and tripropylene oxide propyl ether 662. The use of epoxy diluents allows the added curing agent to react with epoxy groups, forming a cross-linked network structure, further improving the stability of the filter media and providing more attachment points for the added fillers.

[0010] Furthermore, in order to further improve the performance of epoxy resin, reduce the brittleness of epoxy resin, improve its strength, corrosion resistance and other properties, and at the same time increase the bonding performance of epoxy resin, a certain amount of modifier is added, and the modifier includes one or more of nitrile rubber, polyvinyl butyral, urea-formaldehyde melamine resin, phenolic resin, etc.

[0011] Furthermore, in order to reduce the brittleness of the epoxy resin, enhance the hardness, toughness, wear resistance and hydrophilicity of the epoxy resin, accelerate the film formation, and improve the film formation efficiency and quantity, various fillers can be added, including one or more of quartz powder, iron powder, corundum, graphite powder, talcum powder, porcelain powder, asbestos fiber, glass fiber, starch, flour, calcium carbonate, etc.

[0012] Furthermore, in order to avoid excessive aggregation of fillers in the epoxy resin and to ensure better uniform distribution, it is necessary to control the particle size of the added fillers to 0.1-10 μm or the fiber length to 2-20 μm.

[0013] Furthermore, in order to enhance the dispersibility and adhesion of the added filler in the epoxy resin and improve the compatibility between the filler and the epoxy resin, a small amount of coupling agent is added, and the coupling agent includes a silane coupling agent and / or a titanate coupling agent.

[0014] In a second aspect, the present application also provides a method for preparing the medium filter material for the denitrification biofilter:

[0015] The method comprises the following steps: after the epoxy resin, the curing agent, the diluent and the modifier are mixed sufficiently, the fillers and the coupling agent are added and stirred uniformly, the uniform mixed solution is obtained, and then the solidification is performed by crushing, ball milling and filtering to obtain the epoxy resin medium filter material with a size of 3-5 mm.

[0016] Further, when the room temperature type curing agent is selected, the mixing temperature of the epoxy resin, the curing agent, the diluent and the modifier is 30-50 DEG C, and when the high temperature type curing agent is selected, the mixing temperature of the epoxy resin, the curing agent, the diluent and the modifier is 120-180 DEG C; and the solidification time is 1-12 h.

[0017] More specifically, the method for preparing the medium filter material for the denitrification biofilter comprises the following steps: in the first step, after the epoxy resin, the curing agent, the diluent and the modifier are mixed, they are placed in a water bath kettle or a high temperature reaction furnace at a proper temperature and stirred uniformly, if the room temperature type curing agent is selected, the reaction is performed in the water bath kettle at 30-50 DEG C, and if the high temperature type curing agent is selected, the reaction is performed in the high temperature reaction furnace at 120-180 DEG C;

[0018] In the second step, after the mixed solution obtained in the first step is stirred sufficiently for 30-60 min, the fillers and the coupling agent are added respectively and continue to be stirred uniformly;

[0019] In the third step, after the mixed solution obtained in the second step is stirred sufficiently for 30-60 min, the solidification is performed for 1-12 h;

[0020] In the fourth step, the solid epoxy resin obtained in the third step is crushed into the epoxy resin particles with a size of 10-15 mm by a crusher, an extruder or a granulator respectively;

[0021] In the fifth step, the epoxy resin particles with a size of 15-20 mm obtained in the fourth step are polished into the epoxy resin particles with a size of 3-5 mm by a ball mill;

[0022] In the sixth step, the epoxy resin particles obtained in the fifth step are screened by 3 mm and 5 mm filtering screens respectively and then dried to obtain the epoxy resin medium filter material with uniform size.

[0023] The epoxy resin medium filter material provided by the present application has the following beneficial effects compared with the prior art:

[0024] (1) The preparation process of the medium filter material is safe and simple, and high temperature firing is not needed;

[0025] (2) The medium filter material has moderate density, and the density is between 1.0-1.5 g / cm 3It will not flow out with the outlet water, and there is no need to set up an interception filter plate, which can also reduce backwash energy consumption and lower operating costs;

[0026] (3) The medium-quality filter material has high strength, high hardness, and higher wear resistance, and will not increase the wear rate due to long-term immersion;

[0027] (4) The medium-quality filter material has biological affinity activity and high hydrophilicity, which accelerates the biofilm formation speed, increases the biofilm formation amount, and improves the reaction efficiency. DETAILED DESCRIPTION

[0028] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the embodiments. Example 1

[0029] This embodiment provides a medium-quality filter material for a denitrification biological filter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 20 parts room-temperature curing agent, 10 parts reactive diluent, 5 parts modifier, 10 parts filler, and 1 part silane coupling agent. The room-temperature curing agent is selected from one or more alicyclic polyamines, the reactive diluent is selected from one or both of propylene oxide butyl ether 660 and propylene oxide phenyl ether 690, the modifier is selected from nitrile rubber, and the filler is selected from one or more of quartz powder, corundum, and porcelain powder.

[0030] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0031] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a 50℃ water bath and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 60 minutes, and let it stand and cure for 4 hours to obtain solid epoxy resin;

[0032] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 2

[0033] This embodiment provides a medium-quality filter material for a denitrification biological filter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 20 parts room-temperature curing agent, 5 parts reactive diluent, 10 parts modifier, 15 parts filler, and 1 part titanate coupling agent. The room-temperature curing agent is selected from one or more amidoamines, the reactive diluent is dipropylene oxide ethyl ether 669, the modifier is polyvinyl butyral, and the filler is selected from asbestos fiber or glass fiber, or a mixture thereof.

[0034] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0035] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a 45°C water bath and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 60 minutes, and let it stand and cure for 8 hours to obtain solid epoxy resin;

[0036] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 3

[0037] This embodiment provides a medium-quality filter material for a denitrification biofilter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 25 parts room-temperature curing agent, 10 parts reactive diluent, 10 parts modifier, 20 parts filler, and 2 parts titanate coupling agent. The room-temperature curing agent is selected from one or more alicyclic polyamines or amidoamines, the reactive diluent is tripropylene oxide propyl ether 662, the modifier is selected from one or more phenolic resins or urea-formaldehyde melamine resins, and the filler is selected from one or a mixture of starch, flour, or calcium carbonate.

[0038] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0039] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a 30℃ water bath and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 30 minutes, and let it stand and cure for 8 hours to obtain solid epoxy resin;

[0040] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 4

[0041] This embodiment provides a medium-quality filter material for a denitrification biological filter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 20 parts room-temperature curing agent, 10 parts reactive diluent, 10 parts modifier, 15 parts filler, and 2 parts silane coupling agent. The room-temperature curing agent is a mixture of alicyclic polyamines or amidoamines, the reactive diluent is a mixture of epoxy ethers, the modifier is a mixture of rubbers, resins, and aldehydes, and the filler is a mixture of minerals, fibers, or nutrients such as starch.

[0042] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0043] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a 50℃ water bath and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 60 minutes, and let it stand and cure for 8 hours to obtain solid epoxy resin;

[0044] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 5

[0045] This embodiment provides a medium-quality filter material for a denitrification biological filter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 15 parts high-temperature curing agent, 10 parts reactive diluent, 10 parts modifier, 25 parts filler, and 5 parts titanate coupling agent. The high-temperature curing agent is selected from one or more aromatic polyamines, the reactive diluent is selected from one or both of propylene oxide butyl ether 660 and propylene oxide phenyl ether 690, the modifier is selected from polyvinyl butyral, and the filler is selected from one or a mixture of starch, flour, or calcium carbonate.

[0046] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0047] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a high temperature reactor at 120°C and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 30 minutes, and let it stand and cure for 8 hours to obtain solid epoxy resin;

[0048] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 6

[0049] This embodiment provides a medium-quality filter material for a denitrification biological filter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 20 parts high-temperature curing agent, 5 parts reactive diluent, 5 parts modifier, 15 parts filler, and 2 parts silane coupling agent. The high-temperature curing agent is selected from one or more aromatic polyamines, the reactive diluent is selected from dipropylene oxide ethyl ether 669, the modifier is selected from one or more phenolic resins or urea-formaldehyde melamine resins, and the filler is selected from one or more of quartz powder, corundum, and porcelain powder.

[0050] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0051] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a high temperature reactor at 170°C and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 60 minutes, and let it stand and cure for 10 hours to obtain solid epoxy resin;

[0052] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 7

[0053] This embodiment provides a medium-quality filter material for a denitrification biological filter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 20 parts high-temperature curing agent, 10 parts reactive diluent, 10 parts modifier, 10 parts filler, and 2 parts silane coupling agent. The high-temperature curing agent is one or more aromatic polyamines, the reactive diluent is tripropylene oxide propyl ether 662, the modifier is nitrile rubber, and the filler is either asbestos fiber or glass fiber, or a mixture thereof.

[0054] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0055] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a high temperature reactor at 150°C and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 60 minutes, and let it stand and cure for 10 hours to obtain solid epoxy resin;

[0056] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 8

[0057] This embodiment provides a medium-quality filter material for a denitrification biological filter, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 15 parts high-temperature curing agent, 10 parts reactive diluent, 10 parts modifier, 20 parts filler, and 5 parts titanate coupling agent. The high-temperature curing agent is a mixture of several aromatic polyamines, the reactive diluent is a mixture of several epoxy ethers, the modifier is a mixture of several rubbers, resins, and aldehydes, and the filler is a mixture of several nutrients such as minerals, fibers, or starch.

[0058] The manufacturing method of the above-mentioned medium-quality filter material is as follows:

[0059] (1) After mixing epoxy resin, curing agent, diluent and modifier, place in a high temperature reactor at 160°C and stir evenly for 30 minutes, add filler and coupling agent and continue to stir evenly for 60 minutes, and let it stand and cure for 8 hours to obtain solid epoxy resin;

[0060] (2) The solid epoxy resin is crushed and ground by a crusher, an extruder or a granulator, and a ball mill, and then screened through 3 mm and 5 mm filter screens and dried to obtain epoxy resin medium-quality filter material of uniform size. Example 9

[0061] The physical indexes of the medium-quality filter materials obtained in Examples 1 to 8 were tested. The eight medium-quality filter materials were all approximately spherical, with an average particle size of 3-5 mm and a density of 1.0-1.5 g / cm 3 , porosity is 40-50%, specific surface area is greater than 1500m 2 / m 3 , the filter material dissolution does not contain trace elements harmful to the human body. In view of the good performance of the medium-quality filter materials prepared in Examples 1-8, the medium-quality filter materials prepared in Examples 4 and 8 were used for experimental exploration.

[0062] The test was conducted on domestic sewage from a Nanjing wastewater treatment plant after secondary treatment. The test operating parameters are shown in Table 1. During the performance study of the medium-quality filter media, the influent and effluent COD indicators were not considered, and sufficient carbon source was added. The main monitoring measures were the medium-quality filter media's TN removal efficiency and SS filtration and retention capacity during and after biofilm formation.

[0063] Table 1 Medium filter media test operating parameters

[0064]

[0065] (1) Filter film start-up

[0066] During the filter biofilm formation startup period, TN and SS in the inlet and outlet water were monitored. After two days of continuous water inflow, the TN removal rates of Examples 4 and 8 began to steadily increase. After five days of continuous water inflow, the TN removal rates of both reached 70%. Starting from the seventh day, the SS and TN removal rates of Examples 4 and 8 stabilized at approximately 86% and 74% and 88% and 73%, respectively. It can be considered that the filter biofilm formation startup was successful. The faster biofilm formation speed and higher TN removal rate also indicate that the medium-quality filter media has good biological adhesion.

[0067] Table 2 Treatment effect during the filter film formation start-up period

[0068]

[0069] (2) Normal operation of the filter

[0070] After successful biofilm formation, the filter entered normal operation. Regular monitoring of the inlet and outlet TN and SS parameters was used to determine the stability of the filter treatment and, by extension, the biofilm formation performance of the medium-quality filter media. The operating parameters during normal filter operation were consistent with those during the biofilm formation startup phase. Specific test results are shown in Table 3.

[0071] Table 3 Treatment effect during normal operation of the filter

[0072]

[0073] As shown in Table 3, after long periods of continuous operation, the medium-quality filter media of Examples 4 and 8 achieved stable treatment effects. The SS removal rates for both media were stable at over 85%, and the effluent SS was consistently below 3 mg / L, indicating that the medium-quality filter media had good filtration and retention capabilities, and that the microbial film growth on the medium-quality filter media was good. Furthermore, the TN removal rates for the medium-quality filter media of Examples 4 and 8 during continuous operation were both stable at over 70%, and the number of TN removed was stable at over 10. Even after several backwashes during filter operation, the TN removal rate remained above 60% after each backwash. This indicates that the medium-quality filter media exhibited good biofilm formation and a fast biofilm formation rate, and that some microbial film that had fallen off after backwashing could be quickly restored.

[0074] In summary, the experimental results demonstrate that the medium-quality filter media exhibits excellent bioadhesion properties, rapid biofilm formation, high biofilm production, and rapid recovery after backwash shock, thereby ensuring stable and efficient filter treatment efficiency. During stable operation, the TN and SS removal rates for Examples 4 and 8 reached a maximum of 77% and 87%, and 73% and 88%, respectively. The TN and SS concentrations in the effluent from both medium-quality filter media remained stable below 5 mg / L and 3 mg / L.

[0075] The above embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A medium filter material for a denitrification biological filter, characterized in that: The medium-quality filter material comprises the following raw materials in parts by weight: 100 parts of epoxy resin, 10-30 parts of curing agent, 5-15 parts of diluent, 5-15 parts of modifier, 10-30 parts of filler, and 1-5 parts of coupling agent; the average particle size of the medium-quality filter material is 3-5 mm, and the density is 1.0-1.5 g / cm 3 , porosity is 40-50%, specific surface area is greater than 1500m 2 / m 3 ; The epoxy value of the epoxy resin is greater than 0.4; The curing agent is a room temperature curing agent or a high temperature curing agent; the room temperature curing agent includes one or more of alicyclic polyamines and amidoamine room temperature curing agents, and the high temperature curing agent is one or more of m-phenylenediamine, m-xylenediamine, DDM, and DDS; The filler includes one or more of quartz powder, iron powder, corundum, graphite powder, talc, porcelain powder, asbestos fiber, glass fiber, starch, flour, and calcium carbonate; the filler particle size range is 0.1-10 μm or the fiber length range is 2-20 μm.

2. The medium filter material for denitrification biological filter according to claim 1, characterized in that: The diluent is a reactive diluent, including one or more of propylene oxide butyl ether 660, propylene oxide phenyl ether 690, dipropylene oxide ethyl ether 669, and tripropylene oxide propyl ether 662.

3. The medium filter material for denitrification biological filter according to claim 1, characterized in that: The modifier includes one or more of nitrile rubber, polyvinyl butyral, urea-formaldehyde melamine resin, and phenolic resin.

4. The medium filter material for a denitrification biological filter according to claim 1, wherein: The coupling agent is a silane coupling agent and / or a titanate coupling agent.

5. A method for producing a medium-quality filter material for a denitrification biological filter according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: fully mixing epoxy resin, curing agent, diluent and modifier, adding filler and coupling agent and stirring evenly, leaving the mixed solution to stand and solidify, crushing, ball milling and filtering to obtain 3-5 mm epoxy resin medium-quality filter material; When a room temperature curing agent is selected, the mixing temperature of epoxy resin, curing agent, diluent and modifier is 30-50℃. When a high temperature curing agent is selected, the mixing temperature of epoxy resin, curing agent, diluent and modifier is 120-180℃; the static curing time is 1-12h.

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