A denitrification and phosphorus removal composite filter tank

Abstract

The present invention discloses a denitrification and phosphorus removal composite filter, which relates to the technical field of sewage treatment. The composite filter sequentially includes an electrolysis layer, a supporting layer, a first ceramsite layer, a second ceramsite layer, a sulfur autotrophic filter media layer, a denitrification layer, a reflux layer, and a sand layer from bottom to top, wherein the sulfur autotrophic filter media layer is composed of modified filter media. By modifying the filter media in the sulfur autotrophic filter media layer, reasonably setting the order and filling height of the packing layers of the composite filter, and controlling the particle size of the packing, the present invention can effectively remove phosphorus and nitrogen elements in sewage, achieve the effect of denitrification and phosphorus removal, and is provided with a plurality of air washing devices in the filter to accurately air wash the packing in the filter and effectively control the clogging situation.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and specifically relates to a denitrification and phosphorus removal composite filter tank. Background Art

[0002] The up-to-standard treatment of sewage is an important part of environmental improvement. With the increasingly strict national sewage discharge standards, the requirements for total nitrogen, COD, and total phosphorus in sewage discharge wastewater are also getting higher and higher. It is difficult to meet the requirements of low-content total nitrogen and total phosphorus simultaneously by using traditional sewage treatment means.

[0003] For example, in China, the nitrification-denitrification biological nitrogen removal (i.e., A / O) process is used for nitrogen removal treatment. Generally, it undergoes three processes: ammonification, nitrification, and denitrification for removal. This method has a certain effect on nitrogen removal, but the denitrification process requires the consumption of organic carbon sources. The organic carbon concentration in the wastewater is relatively low and cannot meet the denitrification requirements, so an external carbon source needs to be added, increasing the investment cost.

[0004] For the nitrogen removal process using a sulfur autotrophic denitrification filter, its basic principle is that sulfur autotrophic microorganisms attached to the surface of sulfur use sulfur as an electron donor to drive the conversion of nitrate to nitrogen gas to achieve nitrogen removal. Its advantages are that no organic carbon source needs to be added and the wall investment cost is low. At the same time, the elemental sulfur has a relatively high electron equivalent and has obvious advantages in operating costs. However, its main problem is that corrosive acids are generated during the sulfur autotrophic denitrification process. Generally, it is mixed with limestone for use to maintain the acid-base balance, while limestone itself cannot be used as an electron donor to drive the denitrification process. Therefore, it occupies the filter bed area to form a "dead zone" for the denitrification reaction, and the overall nitrogen removal efficiency is relatively low. For example, Chinese Patent CN107176702A discloses a sewage treatment method for enhancing the synchronous nitrogen and phosphorus removal during the sulfur autotrophic denitrification process. This method uses pyrite, sulfur, and siderite to strengthen the denitrification process of wastewater and improve the synchronous nitrogen and phosphorus removal effect. It has a certain nitrogen and phosphorus removal effect and the characteristics of low cost. However, the sulfur autotrophic filter material prepared by this invention has a long sewage treatment time and requires 12 days of treatment to achieve the nitrogen and phosphorus removal effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a denitrification and phosphorus removal composite filter tank to solve at least one of the problems and defects mentioned in the above background art.

[0006] Specifically as follows:

[0007] The present invention provides a denitrification and phosphorus removal composite filter tank, which sequentially includes an electrolysis layer, a support layer, a first ceramsite layer, a second ceramsite layer, a sulfur autotrophic filter material layer, a denitrification layer, a reflux layer, and a sand layer from bottom to top;

[0008] The sulfur autotrophic filter material layer is composed of modified filter materials;

[0009] The modified filter media includes the following preparation steps:

[0010] S1. Electrolytically copper-plate the sulfur-containing particles to obtain copper-plated particles;

[0011] S2. Add the copper-plated particles to an iron-containing solution for modification;

[0012] The current density of the electrolysis is 1 A / dm 2 ~3 A / dm 2 .

[0013] According to one technical solution in the technical solution of the denitrification and phosphorus removal composite filter tank of the present invention, it has at least the following beneficial effects:

[0014] By modifying the sulfur-containing particles, the present invention can obtain modified filter media for sulfur autotrophic denitrification. Since corrosive acids are generated during the sulfur autotrophic denitrification process, the present invention attaches elemental copper to the surface of the filter media particles based on the principle of electrolysis, which can improve the corrosion resistance of the filter media, extend its service life, and through modification with an iron-containing solution, part of the copper coating is etched, increasing the specific surface area of the filter media, effectively controlling the reaction intensity of the sulfur autotrophic filter media, and cooperating with the composite filter tank provided by the present invention, thereby improving the denitrification and phosphorus removal rate.

[0015] By controlling the current density during the electrolytic copper plating of the sulfur-containing particles, the thickness of the copper plating is controlled to achieve the effects of corrosion resistance of the filter media and improvement of the denitrification and phosphorus removal rate. If the current density is too small, the copper plating thickness is too thin to achieve the corrosion resistance effect and the service life is not long. If the current density is too large, the copper plating thickness is too thick, and the iron solution is difficult to effectively etch the copper coating, failing to achieve the effect of increasing the specific surface area, resulting in a slow sulfur autotrophic denitrification process and ultimately affecting the denitrification and phosphorus removal rate.

[0016] After the sewage is preliminarily dephosphorized by electrolysis, the present invention preliminarily removes the influent water through the first ceramsite layer, mainly adsorbing larger suspended solids in the sewage and filtering out the precipitates generated by electrolytic dephosphorization to achieve the dephosphorization effect. Then, through the second ceramsite layer, the suspended solids and insoluble substances in the sewage are further filtered out, reducing the impact on the blockage of the sulfur autotrophic filter media. Then, through the sulfur autotrophic filter media layer and the denitrification layer, the sulfur autotrophic denitrification process is carried out. The sulfur autotrophic filter media with a large specific surface area can provide a comfortable growth environment for Thiobacillus denitrificans, enabling Thiobacillus denitrificans to use reduced sulfur as an electron donor to complete the denitrification and phosphorus removal process and remove the total nitrogen and total phosphorus in the sewage.

[0017] The composite filter tank provided by the present invention is provided with a reflux layer, which can mix the sewage after filtration treatment, stabilize the water quality, reduce the water quality fluctuation, and at the same time dilute the influent concentration and improve the filtration efficiency of the filter tank.

[0018] The supporting layer of the present invention can bear the filter media above the supporting layer without leaking the packing material. In front of the water outlet of the present invention, there is a sand layer, which can filter the sewage after advanced treatment to remove suspended solids, so as to achieve the standard discharge. In addition, it can reduce the loss of sulfur autotrophic and denitrifying filter bricks and save costs.

[0019] In some specific embodiment schemes of the present invention, the modified filter media specifically includes the following preparation steps;

[0020] S1. Crush the sulfur-containing particles and soak them in an aqueous sodium hydroxide solution, then filter and remove the slag;

[0021] S2. Use elemental copper as the anode and the filter media as the cathode in the electrolyte for electroplating copper;

[0022] S3. Soak the copper-plated filter media in a heated iron solution for modification, then filter and dry to obtain the modified filter media.

[0023] In some specific embodiment schemes of the present invention, the concentration of the aqueous sodium hydroxide solution is 0.5 mol / L to 1.0 mol / L.

[0024] In the present invention, the aqueous sodium hydroxide solution can remove other impurity components on the surface of the packing particles to ensure the purity of the packing material. In addition, it dissolves the natural oxide film of the metal inside the packing, improves the conductivity of the packing, and can improve the efficiency of subsequent electroplating.

[0025] In some specific embodiment schemes of the present invention, the concentration of the plating solution is 0.8 mol / L to 1.5 mol / L.

[0026] In some specific embodiment schemes of the present invention, the heating temperature is 60°C to 90°C.

[0027] In some specific embodiment schemes of the present invention, the drying temperature is 450°C to 550°C.

[0028] In some specific embodiment schemes of the present invention, the drying time is 0.5 h to 1.5 h.

[0029] In some specific embodiment schemes of the present invention, the sulfur-containing particles are at least two of pyrite, sulfur, siderite and pyrite.

[0030] In some specific embodiment schemes of the present invention, the electroplating time for copper plating is 20 min to 45 min.

[0031] In some specific embodiment schemes of the present invention, the particle size of the sulfur-containing particles is 4 mm to 10 mm.

[0032] In some specific embodiments of the present invention, the iron-containing solution is at least one of ferric chloride solution, ferric sulfate solution and ferric nitrate solution.

[0033] In some specific embodiments of the present invention, the concentration of the iron-containing solution is 0.8 mol / L to 1.5 mol / L.

[0034] In some specific embodiments of the present invention, the plating solution for electrolysis is copper sulfate solution or copper pyrophosphate solution.

[0035] In some specific embodiments of the present invention, the modification time in step S2 is 8 h to 14 h.

[0036] In some specific embodiments of the present invention, the modification temperature in step S2 is 60 °C to 90 °C.

[0037] In some specific embodiments of the present invention, the anode of the electrolytic layer is an iron anode or an aluminum anode;

[0038] The cathode of the electrolytic layer is graphite.

[0039] The present invention adopts an external power supply to form an electrolytic circuit in the electrolytic layer. Under the conditions of electrolysis, the anode will dissolve, lose electrons to form metal cations, and form precipitates with phosphate radicals in the sewage, so as to achieve the purpose of reducing total phosphorus. The following is the phosphorus removal principle:

[0040] Al 3+ +PO4 3- →AlPO4↓;

[0041] Fe 3+ +PO4 3- →FePO4↓.

[0042] In the electrolytic layer of the present invention, the iron plate or aluminum plate of the anode undergoes an oxidation reaction, loses electrons to produce iron ions or aluminum ions, and reacts with phosphate radicals in the sewage to produce precipitates, thereby achieving the effect of phosphorus removal.

[0043] In some specific embodiments of the present invention, air washing pipes and pressure sensors are provided in the first ceramsite layer, the second ceramsite layer, the denitrification layer and the sand layer.

[0044] The present invention is provided with a partition air washing device in the first ceramsite layer, the second ceramsite layer, the sand layer and the denitrification layer to perform backwashing on the packing layer. At the same time, the pressure sensor can monitor the blockage situation in the packing layer to achieve precise backwashing.

[0045] In some specific embodiments of the present invention, the height of the sulfur autotrophic filter material layer is 600 mm to 850 mm.

[0046] In some specific embodiments of the present invention, the denitrification layer is composed of denitrification filter bricks.

[0047] In some specific embodiments of the present invention, the denitrification filter bricks are filled with silica sand.

[0048] In some specific embodiments of the present invention, the particle size of the silica sand is 2 mm to 4 mm.

[0049] The filling of silica sand in the denitrification bricks of the present invention can provide a growth environment for denitrifying bacteria.

[0050] In some specific embodiments of the present invention, the first ceramsite layer is composed of coarse ceramsite.

[0051] In some specific embodiments of the present invention, the particle size of the coarse ceramsite is 11 mm to 15 mm.

[0052] The present invention selects coarse-particle-size ceramsite for the first ceramsite layer to preliminarily filter sewage, adsorb and filter suspended solids in the sewage, and reduce the risk of blockage in subsequent treatment.

[0053] In some specific embodiments of the present invention, the height of the first ceramsite layer is 180 mm to 220 mm.

[0054] In some specific embodiments of the present invention, the second ceramsite layer is composed of fine ceramsite.

[0055] In some specific embodiments of the present invention, the particle size of the fine ceramsite is 8 mm to 10 mm.

[0056] The present invention selects fine-particle-size ceramsite for the second ceramsite layer to further filter sewage, and can adsorb and filter the fine suspended solids that escape from the first ceramsite layer.

[0057] In some specific embodiments of the present invention, the height of the second ceramsite layer is 130 mm to 170 mm.

[0058] In some specific embodiments of the present invention, the sand layer is composed of sand grains.

[0059] The present invention finally arranges a sand layer in the composite filter tank to perform in-depth treatment on the sewage finally.

[0060] In some specific embodiments of the present invention, the particle size of the sand grains is 1 mm to 2 mm.

[0061] The present invention controls the particle size of the sand grains to achieve the effect of in-depth treatment of sewage. If the particle size is too small, the effluent flow rate will be reduced and it is easy to be blocked. If the particle size is too large, the effect of in-depth treatment cannot be achieved, and at the same time, the effect of reducing the loss of filter tank packing cannot be achieved.

[0062] In some specific embodiments of the present invention, the height of the sand grain layer is 450 mm to 560 mm.

[0063] In some specific embodiments of the present invention, the height of the reflux layer is 300 mm to 600 mm.

[0064] The composite filter tank of the present invention is provided with a reflux layer. After the sewage is subjected to sulfur autotrophic denitrification treatment, it is evenly mixed through the reflux layer to stabilize the water quality.

[0065] In some specific embodiments of the present invention, the reflux ratio is 100% to 150%.

[0066] The present invention sets a reasonable reflux ratio, returns the sewage to perform denitrification and phosphorus removal treatment again before sulfur autotrophic denitrification treatment, and improves the removal rates of phosphorus and nitrogen elements.

[0067] In some specific embodiments of the present invention, a reflux pipe is connected to the bottom of the sulfur autotrophic filter material layer and the reflux layer.

[0068] In some specific embodiments of the present invention, the position of the water inlet is set to be lower.

[0069] In some specific embodiments of the present invention, the position of the water outlet is set to be upper.

[0070] Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention:

[0071] 1. The present invention attaches elemental copper to the surface of filter material particles by means of electrolysis, which can improve the corrosion resistance of the filter material and extend its service life. At the same time, the etching of the iron-containing solution increases the specific surface area of the filter material, which can effectively control the reaction intensity of the sulfur autotrophic filter material. Combined with the composite filter tank provided by the present invention, the denitrification and phosphorus removal rate can be improved.

[0072] 2. The present invention effectively removes phosphorus and nitrogen elements in sewage and achieves the effect of denitrification and phosphorus removal by reasonably setting the order of the filler layers of the composite filter tank and setting the filling thickness of each filler layer and the particle size of the filler. At the same time, the filter tank is also provided with a reflux layer and a reflux pipe, which can perform deep denitrification and phosphorus removal treatment on the sewage.

[0073] 3. The present invention performs air washing zoning on the first ceramsite layer, the second ceramsite layer, the sand grain layer and the denitrification layer in the composite filter tank. An air washing pipe and a pressure sensor are arranged in each air washing area in the filler layer, which can monitor the blockage condition of the air washing area in each filler layer at any time and achieve the purpose of accurate backwashing. It can not only relieve the blockage condition of the filter tank, but also save energy and reduce consumption to a certain extent. Brief Description of the Drawings

[0074] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the accompanying drawings.

[0075] Figure 1 It is a sectional view of the denitrification and phosphorus removal composite filter for the embodiment.

[0076] Figure 2 It is a plan view of the air washing device in the embodiment.

[0077] Reference numerals:

[0078] 100, electrolytic layer; 101, supporting layer; 102, first ceramsite layer; 103, second ceramsite layer; 104, sulfur autotrophic filter media layer; 105, denitrification layer; 106, reflux layer; 107, sand grain layer; 108, reflux pipe; 109, water inlet; 110, water outlet; 111, electrode; 112, power supply.

[0079] 113, air washing pipe; 114, pressure sensor. Detailed implementation manners

[0080] The concept of the present invention and the technical effects produced will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0081] In the description of the present invention, the description of reference terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0082] For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0083] The specific embodiments of the present invention will be described in detail below.

[0084] In the present invention, the test of the total phosphorus and total nitrogen contents refers to the pollutant discharge standard for urban sewage treatment plants GB18918 - 2002.

[0085] Example 1

[0086] This embodiment is a denitrifying and phosphorus-removing composite filter, as Figure 1 shown. The composite filter successively includes an electrolysis layer 100, a supporting layer 101, a first ceramsite layer 102, a second ceramsite layer 103, a sulfur autotrophic filter media layer 104, a denitrification layer 105, a reflux layer 106, and a sand layer 107 from bottom to top.

[0087] In this embodiment, an iron plate is used as the anode and graphite as the cathode in the electrolysis layer. The supporting layer 102 uses a 304 stainless steel mesh (mesh size 6 mm) with square steel as the supporting skeleton. The first ceramsite layer 102 uses ceramsite with a particle size of 13 mm, and the packing height of the first ceramsite layer 102 is 200 mm. The second ceramsite layer 103 uses ceramsite with a particle size of 9 mm, and the packing height of the second ceramsite layer 103 is 150 mm. The particle size of the filter media in the sulfur autotrophic filter media layer 104 is 4 mm to 10 mm. The denitrification filter brick has a length, width, and height of 500 mm, 250 mm, and 200 mm respectively, and is filled with silica sand with a particle size of 2 mm inside. The packing height of the denitrification layer 105 is 400 mm, the height of the reflux layer 106 is 500 mm, the sand layer 107 uses sand with a particle size of 2 mm, and the packing height of the sand layer 107 is 500 mm.

[0088] Air washing pipes 113 and pressure sensors 114 are provided in the first ceramsite layer 102, the second ceramsite layer 103, the denitrification layer 105, and the sand layer 107. The relative positions of the air washing pipes 113 and the pressure sensors 114 are as Figure 2 .

[0089] In this embodiment, the sulfur autotrophic filter media layer 104 is composed of modified filter media, and the modified filter media is composed of the following steps:

[0090] S1. Crush sulfur and screen it successively through sieves with specifications of 10 mesh and 5 mesh, and take the particulate matter intercepted by the 10-mesh sieve for use. Then crush pyrite and screen it successively through sieves with specifications of 20 mesh and 60 mesh, and take the particulate matter intercepted by the 60-mesh sieve. Mix the sulfur particles and pyrite particles in a mass ratio of 1:1 to obtain a particle mixture;

[0091] S2. Grind and granulate the particle mixture to obtain original filter media particles with a particle size of 5 mm. Then soak the original filter media particles in a 0.6 mol / L sodium hydroxide aqueous solution for 3 h, and filter and remove the residue;

[0092] S3. In a 1.0 mol / L copper sulfate aqueous solution, use elemental copper as the anode and the filter media as the cathode, and set the current density to 2 A / dm 2 for electrolytic copper plating. The electrolysis time is 30 min. Soak the copper-plated filter media in a heated 1.0 mol / L ferric chloride aqueous solution at a heating temperature of 80 °C for 10 h, and then filter.

[0093] S4. Dry the filtered filter media particles in an oxygen-free environment at 500 °C, and finally perform vacuum cooling to obtain the modified filter media.

[0094] Using the denitrification and phosphorus removal composite filter tank of this embodiment to treat sewage, the sewage influent flow rate is 100 m 3 / d, set the reflux ratio to 100%, repeat the experiment for 5 days, record the total phosphorus and total nitrogen contents of the influent sewage and the treated sewage every day, and calculate the phosphorus removal rate and denitrification rate every day.

[0095] Example 2

[0096] The difference between this embodiment and Example 1 is that pyrite is replaced with siderite, and the iron plate is replaced with an aluminum plate.

[0097] Example 3

[0098] The difference between this embodiment and Example 1 is that the height of the first ceramsite layer is 190 mm, the height of the second ceramsite layer is 160 mm, and the height of the sand layer is 450 mm.

[0099] Comparative Example 1

[0100] The difference between this comparison and Example 1 is that the granular mixture is directly used as the filter media of the sulfur autotrophic filter layer, and the granular mixture is not subjected to subsequent modification treatment.

[0101] Comparative Example 2

[0102] The difference between this comparison and Example 1 is that the current density is set to 5 A / dm 2 .

[0103] Comparative Example 3

[0104] The difference between this comparison and Example 1 is that the existing sewage treatment process is used to treat sewage. The existing process flow is: the sewage is passed through a coarse grid, a fine grid, an aerated grit chamber, a segmented A 2 O tank, a secondary sedimentation tank, a high-density sedimentation tank, a V-shaped filter tank and ultraviolet chlorine addition composite disinfection treatment to obtain the treated sewage.

[0105] Test the total phosphorus content values after sewage treatment in Examples 1-3 and Comparative Examples 1-3. The results are shown in Table 1.

[0106] Obtain the phosphorus removal rates after sewage treatment in Examples 1-3 and Comparative Examples 1-3. The results are shown in Table 2.

[0107] Test the total nitrogen content values after sewage treatment in Examples 1-3 and Comparative Examples 1-3. The results are shown in Table 3.

[0108] The denitrification rates after sewage treatment in Examples 1 to 3 and Comparative Examples 1 to 3 were obtained, and the results are shown in Table 4.

[0109] Table 1 Results of total phosphorus content values after sewage treatment in Examples 1 to 3 and Comparative Examples 1 to 3

[0110]

[0111]

[0112] Table 2 Results of phosphorus removal rates after sewage treatment in Examples 1 to 3 and Comparative Examples 1 to 3

[0113]

[0114] Table 3 Results of total nitrogen content values after treatment in Examples 1 to 3 and Comparative Examples 1 to 3

[0115]

[0116] Table 4 Results of denitrification rates after sewage treatment in Examples 1 to 3 and Comparative Examples 1 to 3

[0117]

[0118]

[0119] As can be seen from Table 1, Table 2, Table 3 and Table 4, under the condition of the same sewage inlet, in Comparative Example 1, the traditional filter material was used, that is, the particle mixture in the present invention was not subjected to subsequent modification treatment, and the phosphorus removal rate and denitrification rate were significantly lower than the phosphorus removal rate of Example 1; in Comparative Example 2, the current density of electroplating copper was increased, and the overall phosphorus removal rate and denitrification rate also decreased. This was mainly because the copper plating thickness was too thick, which would block the micropores on the surface of sulfur-containing particles, thereby slowing down the rate of sulfur autotrophic denitrification process and ultimately affecting the phosphorus removal rate and denitrification rate; in Comparative Example 3, the traditional sewage treatment process was used, and the phosphorus removal rate and denitrification rate were significantly lower than those of the filter tank provided by the present invention.

[0120] In summary, by using electrolysis to attach elemental copper to the surface of filter media particles, the present invention can improve the corrosion resistance of the filter media, extend its service life, and effectively control the reaction intensity of sulfur autotrophic filter media. In combination with the composite filter tank provided by the present invention, the denitrification and phosphorus removal rate can be further improved. By reasonably setting the order of the filler layers of the composite filter tank and setting the filling thickness of each filler layer and the particle size of the filler, the present invention can effectively remove phosphorus and nitrogen elements in sewage, achieving the effect of denitrification and phosphorus removal. At the same time, the filter tank is also provided with a reflux layer and a reflux pipe for deep denitrification and phosphorus removal treatment of sewage. The present invention performs air washing zoning in the first ceramsite layer, the second ceramsite layer, the sand grain layer, and the denitrification layer in the composite filter tank. An air washing pipe and a pressure sensor are provided in each air washing area in the filler layer to monitor the blockage condition of the air washing area in each filler layer at any time, achieving the purpose of precise backwashing. This can not only relieve the blockage condition of the filter tank but also achieve energy conservation and consumption reduction to a certain extent.

[0121] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A denitrification and phosphorus removal composite filter tank, characterized in that, The composite filter tank sequentially includes an electrolysis layer (100), a supporting layer (101), a first ceramsite layer (102), a second ceramsite layer (103), a sulfur autotrophic filter material layer (104), a denitrification layer (105), a reflux layer (106) and a sand grain layer (107) from bottom to top; The sulfur autotrophic filter material layer (104) is composed of modified filter materials; The modified filter materials include the following preparation steps: S1. Electrolytically copper-plate sulfur-containing particles to obtain copper-plated particles; S2. Add the copper-plated particles to an iron-containing solution for modification; The current density of the electrolysis described in step S1 is 1 A / dm 2 ~3 A / dm 2 ; The sulfur-containing particles are at least two of pyrite, sulfur, siderite and pyrite.

2. The composite filter for nitrogen and phosphorus removal according to claim 1, characterized in that The time for electrolytic copper plating is 20 min to 45 min.

3. The denitrification and phosphorus removal composite filter tank according to claim 1, wherein The particle size of the sulfur-containing particles is 4 mm to 10 mm.

4. The composite filter for nitrogen and phosphorus removal according to claim 1, wherein, The iron-containing solution is at least one of ferric chloride solution, ferric sulfate solution and ferric nitrate solution.

5. The denitrification and phosphorus removal composite filter tank according to claim 1, characterized in that, The concentration of the iron-containing solution is 0.8 mol / L to 1.5 mol / L.

6. The denitrification and phosphorus removal composite filter tank according to claim 1, wherein The plating solution for electrolysis is copper sulfate solution or pyrophosphate copper solution.

7. The composite filter for nitrogen and phosphorus removal according to claim 1, characterized in that The time for modification in step S2 is 8 h to 14 h.

8. The composite filter for denitrification and phosphorus removal according to claim 1, characterized in that, The temperature for modification in step S2 is 60 °C to 90 °C.

9. The composite filter for nitrogen and phosphorus removal according to claim 1, characterized in that, The anode of the electrolysis layer (100) is an iron anode or an aluminum anode; The cathode of the electrolysis layer (100) is a graphite cathode.

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