Nitrogen and phosphorus removal material for river and lake water bodies and preparation method of nitrogen and phosphorus removal material

Abstract

The invention relates to the technical field of water treatment, in particular to a nitrogen and phosphorus removal material for river and lake water and a preparation method thereof.The nitrogen and phosphorus removal material for the river and lake water is prepared from, by weight, 60-80 parts of modified biomass charcoal, 16-40 parts of auxiliary materials and 5-15 parts of adhesive, and the modified biomass charcoal is formed by conducting composite modification on an acid compound and inorganic salt. The invention aims to make the prepared material have good permeable rate, and can effectively remove phosphorus, especially low-concentration phosphate, in water, thereby weakening the total phosphorus level, purifying the water and effectively preventing blue-green algae outbreak.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a material for denitrification and dephosphorization of river and lake water bodies and a preparation method thereof. Background Art

[0002] In recent years, with the acceleration of industrialization and urbanization, a large amount of industrial sewage and domestic wastewater have polluted water sources, causing more than half of the water resources in rivers and lakes to be seriously polluted. Nowadays, the requirements for urban sewage treatment are becoming increasingly stringent, especially under the situation of strict control of nitrogen and phosphorus, the effective removal of nitrogen and phosphorus is bound to receive more and more attention.

[0003] Nitrogen and phosphorus in river water are the triggers for algae blooms, and it is difficult to control excessive ammonia nitrogen and total phosphorus in rivers, and the large water area has high treatment costs. In the prior art, phosphorus removal powder is usually spread in the river to remove phosphorus. Although it can reduce the concentration of total phosphorus in the river in the short term, it cannot be eradicated in the long term. Phosphorus is the main limiting factor for biological utilization and energy exchange in water, and controlling its content can effectively inhibit algal blooms. Therefore, there are special phosphorus removal devices that are installed at the bottom of the water body for long-term nitrogen and phosphorus removal (such as Figure 1 As shown in the figure, before removing phosphorus, it is necessary to salvage and filter the impurities in the river water to reduce the impurities and aquatic plants in the water body, thereby extending the service life. However, the phosphorus removal materials on the existing phosphorus removal devices have insufficient water permeability, resulting in a decrease in the overall removal efficiency, and low removal efficiency for low-concentration phosphates, resulting in a high total phosphorus content in the water body, which cannot effectively inhibit the outbreak of algal blooms. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a river and lake water denitrification and phosphorus removal material and a preparation method thereof, which has good water permeability and can effectively remove phosphorus in the water, especially low concentration of phosphate, thereby weakening the total phosphorus level, purifying the water, and effectively preventing the outbreak of blue algae.

[0005] The present invention solves the above technical problems by the following technical means: A material for removing nitrogen and phosphorus from river and lake water comprises the following raw materials in parts by weight: 60 to 80 parts of modified biochar, 16 to 40 parts of auxiliary materials and 5 to 15 parts of adhesive, wherein the modified biochar is formed by composite modification of an acidic compound and an inorganic salt.

[0006] According to the above technical means, by using biochar as the matrix material, which has a porous structure and a high specific surface area, it can adsorb and fix nitrogen, phosphorus, heavy metal ions, and organic pollutants in the water body, and then through modification, it can enhance its coupling ability with low-concentration phosphates in the water body; and then by adding auxiliary materials, the removal of COD, total nitrogen, total phosphorus and organic pollutants in the water body is further enhanced, thereby improving the purification efficiency and effectively delaying the time of material blockage; when the material is in use, it is adhered by an adhesive, which can effectively enhance the polymerization ability of the material to avoid being dispersed when used in the water body, thereby facilitating construction.

[0007] Preferably, the biomass charcoal is at least one of wood charcoal, fruit shell charcoal, reed charcoal, straw charcoal, algae charcoal and straw charcoal.

[0008] More preferably, the biomass charcoal is straw charcoal.

[0009] According to the above technical means, by selecting the by-product of straw biomass power generation as the base biomass carbon material, the main components of this material are more than a dozen minerals and trace elements such as silicon, aluminum, calcium, iron, magnesium, sodium, titanium and manganese, as well as a small amount of unburned carbon. It appears as irregular particles, gray-black in color, porous and light; the specific surface area is 12-15m2 / g, it is resistant to impact loads, easy to adsorb pollutants, and has good biological affinity, strengthens anaerobic, nitrification, and electronic function transfer, and can be used for ecological environmental restoration.

[0010] Preferably, the acidic compound is at least one of sulfuric acid, hydrochloric acid, phosphoric acid, bromic acid, perchloric acid and an organic acid.

[0011] More preferably, the acidic compound is phosphoric acid, and the concentration of the phosphoric acid is 0.1 to 0.9 mol / L.

[0012] According to the above technical means, by using phosphoric acid as a modifier, biochar can be activated. During the activation process, the specific surface area and porosity of the biochar can be increased. Phosphorus-containing functional groups can also be introduced on the surface of the biochar, thereby increasing the affinity for phosphorus in the water and enhancing the adsorption capacity of phosphorus in the water.

[0013] Preferably, the inorganic salt is at least one of zinc chloride, ferric chloride, aluminum chloride and calcium chloride.

[0014] More preferably, the inorganic salt is zinc chloride, the purity of the zinc chloride is above 98.3%, and the concentration of the zinc chloride solution is 0.4 to 1.5 mol / L.

[0015] According to the above technical means, by using zinc chloride as a modifier, biochar can also be activated. During the activation process, it can dissolve the cellulose in the biochar, making it easier to penetrate into the biomass carbon structure. It can also increase the specific surface area and adsorption capacity of biochar to improve the adsorption capacity of nitrogen and phosphorus in water.

[0016] Preferably, the auxiliary material is at least one of bio-enzyme charcoal, ferrite, polymeric denitrification carbon, polymeric dephosphorization material, calcite, zeolite, kaolin, calcium oxide, aluminum oxide, plastic suspension balls, and carbon fiber bionic aquatic plants.

[0017] According to the above technical means, by selecting auxiliary materials for use together with modified biochar, the removal of COD, total nitrogen, total phosphorus and organic pollutants in water bodies can be further enhanced, thereby improving purification efficiency and effectively delaying the time of material blockage to extend the service life of the material.

[0018] Preferably, the binder is at least one of lignin, sodium lignin sulfonate, starch, methyl cellulose, clay and silicate.

[0019] More preferably, the adhesive is a mixture of methyl cellulose and starch, and the ratio of methyl cellulose to starch is (8-10):1.

[0020] According to the above technical means, by using methyl cellulose and starch as adhesives, which have good film-forming and adhesion properties, not only can the biochar be formed and maintained stable after forming, but also the methyl cellulose and starch are controlled during bonding, and the porosity of the biochar is less affected, thereby making the material have a better use effect.

[0021] Preferably, the river and lake water denitrification and phosphorus removal material is in at least one of a lotus root shape, a porous shape, a sponge shape, and a plum blossom shape.

[0022] According to the above-mentioned technical means, by making the material into different shapes, it is conducive to its use in artificial wetland matrices, pre-treatment filter dams at water sources, ecological management fillers for rivers and lakes, ecological floating beds, ecological slope protection, artificial fish reefs, biological filter tanks, etc., making the application scenarios more extensive. The shape can also be adjusted according to the specific usage scenario to make it more practical.

[0023] The present application also discloses a method for preparing a material for denitrification and dephosphorization of river and lake water bodies, using the above-mentioned raw materials, comprising the following steps: S1. Place the biochar in clean water, soak and wash for 20 to 40 minutes, and after washing, dry at 100 to 110° C. to obtain the washed biochar; S2. The washed biochar is placed in a container, an inorganic salt solution is added, and the mixture is immersed for 12 to 24 hours under shaking conditions, and then an acidic compound is added, and the mixture is shaken for 24 to 36 hours under the conditions of 55 to 80° C., and then cooled to room temperature. After cooling, the mixture is washed 2 to 3 times to obtain a modified biochar for standby use; S3. Mix the modified biochar treated in step S2 with auxiliary materials, add a binder, mix well and add into a mold, dry at 100-160° C. to obtain a denitrification and phosphorus removal material for river and lake water.

[0024] According to the above technical means, the biochar is first cleaned to remove impurities to improve subsequent operations; during the modification, the cellulose in the biochar is first activated by inorganic salts to dissolve the cellulose in the biochar, and the specific surface area and adsorption capacity of the biochar are increased. In the process of removing the inorganic salts, acidic compounds are used. On the one hand, inorganic components attached to the biochar during the activation of the biochar by inorganic salts can be dissolved and removed, so that the pores of the biochar are exposed, thereby improving the specific surface area and adsorption capacity of the biochar; on the other hand, the acidic compounds can reactivate the biochar after the inorganic salt activation to form a secondary activation, so that the second activation can further enhance the pore diameter and pore volume of the biochar, increase the specific surface area of ​​the biochar, and further enhance the adsorption capacity; finally, the adsorption capacity of different pollutants is improved by mixing auxiliary materials, and the materials are bonded by adhesives and dried to form denitrification and phosphorus removal materials for river and lake water bodies of different shapes.

[0025] Preferably, in the step S2, during the oscillation of the acidic compound, the acidic compound is replaced at intervals of 8 to 12 hours, and the acidic compound is added again.

[0026] According to the above technical means, by regularly replacing the acidic compounds, on the one hand, the inorganic salts can be thoroughly cleaned to avoid residues, and on the other hand, the activation performance of the acidic compounds on biochar can be enhanced.

[0027] Preferably, in the step S3, the particle size of the auxiliary material is larger than the particle size of the modified biochar, and the addition ratio of the auxiliary material to the modified biochar is (2-5):10.

[0028] According to the above technical means, by controlling the particle size and addition ratio of auxiliary materials and biochar, it is beneficial to the molding of materials and the removal of pollutants in water bodies.

[0029] Further preferably, in the step S3, the auxiliary material is an auxiliary material surface-modified with iron and aluminum.

[0030] Further preferably, the specific steps of surface modification of iron and aluminum materials include: S21. Dissolving ferric chloride and aluminum chloride in deionized water to obtain a mixed solution, adjusting the pH to neutral, and heating to obtain a brown sol solution; S22. Add a solution regulator to the brown sol solution until the pH is neutral, cool to room temperature, add excipients, and then ultrasonically treat for 20 to 40 minutes. After ultrasonication, transfer to a constant temperature water bath to dry; S23. Rinse the dried product, and then dry it in an oven to obtain a surface-modified auxiliary material.

[0031] According to the above-mentioned technical means, by using auxiliary materials modified with iron and aluminum surfaces, the surface properties of the auxiliary materials can be improved, thereby enhancing the adsorption capacity of the auxiliary materials for organic matter, inorganic matter, heavy metal ions, etc., and the adsorption capacity for phosphates. It can also enhance the high-content phosphoric acid in the water body and quickly remove the phosphoric acid. The phosphoric acid can be further removed by modifying the biochar, thereby making the entire material more capable of removing pollutants.

[0032] The present application adopting the above scheme has the following beneficial effects: 1. By using modified biochar and auxiliary materials to cooperate with each other, it can enhance the removal of COD, total nitrogen, total phosphorus and organic pollutants in water, thereby improving purification efficiency and effectively delaying the time of material blockage, especially for low-concentration phosphates. It has a good removal ability, and can effectively weaken the total phosphorus level for a long time. Phosphorus is the main limiting factor for biological utilization and energy exchange in water. Controlling its content can effectively inhibit algal blooms; 2. In the present application, the biochar is first modified with zinc chloride for activation and then modified with phosphoric acid, thereby performing secondary activation modification on the biochar to further increase the specific surface area and adsorption capacity of the biochar, so that it can have good adsorption capacity for low-concentration phosphates of less than 0.5 mg, and the preparation method is simple; 3. In the present application, by using an adhesive that has little effect on the porosity of biochar for bonding, the entire material can be made into different shapes according to different needs, which is conducive to use in artificial wetland matrices, pre-treatment filter dams at water sources, ecological management fillers for rivers and lakes, ecological floating beds, ecological slope protection, artificial fish reefs, biological filter tanks, etc., making the application scenarios more extensive, and the shape can also be adjusted according to the specific usage scenario to make the scope of application wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present application may be further illustrated by non-limiting examples given in the accompanying drawings; Figure 1 It is a schematic diagram of the arrangement of a phosphorus removal device in the background technology; Figure 2 is a schematic diagram of modified biochar in an embodiment of the present application; Figure 3 It is one of the shape diagrams of the denitrification and dephosphorization material in the embodiment of the present application; Figure 4 This is the second shape diagram of the denitrification and dephosphorization material in the embodiment of the present application; Figure 5 This is the third shape diagram of the denitrification and dephosphorization material in the embodiment of the present application; Figure 6 This is the fourth shape diagram of the denitrification and dephosphorization material in the embodiment of the present application; Figure 7 This is the fifth shape diagram of the denitrification and dephosphorization material in the embodiment of the present application; Figure 8 This is the sixth shape diagram of the denitrification and dephosphorization material in the embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention: Example 1

[0035] In this embodiment, the biomass charcoal is straw charcoal with a particle size of 0.5 to 20 mm. In this embodiment, the particle size is 3 to 5 mm. The acidic compound is phosphoric acid with a concentration of 0.6 mol / L. The inorganic salt is zinc chloride with a purity of 98.3% and a concentration of the zinc chloride solution of 1.2 mol / L. The auxiliary material is ferrite with a particle size of 4 to 6 mm. The adhesive is methyl cellulose and starch with a ratio of methyl cellulose to starch of 8:1.

[0036] Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 80 parts by weight of straw charcoal was placed in sufficient water, soaked and washed for 30 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 100 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 24 hours, then add 45 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. Evenly mix the modified biochar treated in step S2 with 16 parts by weight of ferrite, add 15 parts by weight of methyl cellulose and an aqueous solution of starch, stir until it becomes viscous, add it into a mold, and dry it at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 2

[0037] In this embodiment, the biomass charcoal is straw charcoal with a particle size of 3 to 5 mm; the acidic compound is phosphoric acid with a concentration of 0.6 mol / L; the inorganic salt is zinc chloride with a purity of 98.3% and a concentration of the zinc chloride solution of 1.2 mol / L; the auxiliary material is ferrite with a particle size of 4 to 6 mm; the adhesive is methyl cellulose and starch with a ratio of methyl cellulose to starch of 9:1.

[0038] Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 80 parts by weight of straw charcoal was placed in sufficient water, soaked and washed for 30 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 100 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 24 hours, then add 45 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. Evenly mix the modified biochar treated in step S2 with 16 parts by weight of ferrite, add 10.5 parts by weight of methyl cellulose and an aqueous solution of starch, stir until it becomes viscous, add it into a mold, and dry it at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 3

[0039] In this embodiment, the biomass charcoal is straw charcoal with a particle size of 3 to 5 mm; the acidic compound is phosphoric acid with a concentration of 0.6 mol / L; the inorganic salt is zinc chloride with a purity of 98.3% and a concentration of the zinc chloride solution of 1.2 mol / L; the auxiliary material is ferrite with a particle size of 4 to 6 mm; the adhesive is methyl cellulose and starch with a ratio of methyl cellulose to starch of 10:1.

[0040] Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 80 parts by weight of straw charcoal was placed in sufficient water, soaked and washed for 30 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 100 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 24 hours, then add 45 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. Evenly mix the modified biochar treated in step S2 with 16 parts by weight of ferrite, add 5 parts by weight of methyl cellulose and an aqueous solution of starch, stir until it becomes viscous, add it into a mold, and dry it at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 4

[0041] In this embodiment, the biomass charcoal is straw charcoal with a particle size of 3 to 5 mm; the acidic compound is phosphoric acid with a concentration of 0.6 mol / L; the inorganic salt is zinc chloride with a purity of 98.3% and a concentration of the zinc chloride solution of 1.2 mol / L; the auxiliary material is ferrite with a particle size of 4 to 6 mm; the adhesive is methyl cellulose and starch with a ratio of methyl cellulose to starch of 8:1.

[0042] Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 68 parts by weight of straw charcoal were placed in sufficient water, soaked and washed for 25 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 94 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 18 hours, then add 36 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 80 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 80 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. Evenly mix the modified biochar treated in step S2 with 23.8 parts by weight of ferrite, add 15 parts by weight of an aqueous solution of methyl cellulose and starch, stir until it becomes viscous, add it into a mold, and dry it at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 5

[0043] In this embodiment, the raw material composition used is the same as that of Example 4, except that: Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. Place 60 parts by weight of straw charcoal in sufficient water, soak and wash for 20 minutes, and after washing, dry at 105±1°C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 80 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 18 hours, then add 20 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65 ± 1 ° C for 12 hours, then draw out the liquid in the container, add 78 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, draw out the liquid in the container, add 78 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. Evenly mix the modified biochar treated in step S2 with 21 parts by weight of ferrite, add 15 parts by weight of methyl cellulose and an aqueous solution of starch, stir until it becomes viscous, add it into a mold, and dry it at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 6

[0044] In this embodiment, the raw material composition used is the same as that of Example 4, except that: Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 80 parts by weight of straw charcoal was placed in sufficient water, soaked and washed for 30 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 100 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 24 hours, then add 45 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. Evenly mix the modified biochar treated in step S2 with 40 parts by weight of ferrite, add 15 parts by weight of an aqueous solution of methyl cellulose and starch, stir until it becomes viscous, add it into a mold, and dry it at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 7

[0045] In this embodiment, the raw material composition used is the same as that of Example 1, except that the auxiliary material is bio-enzyme charcoal with a particle size of 4 to 6 mm; Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 80 parts by weight of straw charcoal was placed in sufficient water, soaked and washed for 30 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 100 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 24 hours, then add 45 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. The modified biochar treated in step S2 is evenly mixed with 16 parts by weight of bio-enzyme charcoal, and then 15 parts by weight of an aqueous solution of methyl cellulose and starch are added, stirred into a viscous state, and then added into a mold, and dried at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 8

[0046] In this embodiment, the raw material composition used is the same as that of Example 1, except that the auxiliary material is zeolite with a particle size of 4 to 6 mm; Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 80 parts by weight of straw charcoal was placed in sufficient water, soaked and washed for 30 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 100 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 24 hours, then add 45 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S3. Evenly mix the modified biochar treated in step S2 with 16 parts by weight of zeolite, add 15 parts by weight of methyl cellulose and an aqueous solution of starch, stir until it becomes viscous, add it into a mold, and dry it at 110±1°C to obtain a denitrification and dephosphorization material for river and lake water. Example 9

[0047] In this embodiment, the raw material composition used is the same as that of Example 8, except that: Preparation of materials for nitrogen and phosphorus removal from river and lake water S1. 80 parts by weight of straw charcoal was placed in sufficient water, soaked and washed for 30 min, and then dried at 105 ± 1 ° C to obtain washed straw charcoal; S2. Place the cleaned straw charcoal in a container, add 100 parts by weight of zinc chloride solution, immerse in an oscillator with a working frequency of 40 to 50 Hz for 24 hours, then add 45 parts by weight of phosphoric acid solution, oscillate in an oscillator with a working frequency of 40 to 50 Hz at 65±1°C for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 12 hours, oscillate for 12 hours, extract the liquid in the container, add 100 parts by weight of phosphoric acid solution again, continue to oscillate for 6 hours, and then cool to room temperature. After cooling, wash with soft water 2 to 3 times, dry, and obtain modified biochar for standby use; S21. Dissolve 5 parts by weight of ferric chloride and 5 parts by weight of aluminum chloride in deionized water to obtain a mixed solution, and then add 0.6 mol / L of strong sodium oxide to adjust the pH to neutral, and heat at 60 ± 1 ° C to obtain a brown sol solution; S22. Add 0.6 mol / L of dilute hydrochloric acid to the brown sol solution until the pH is neutral, cool to room temperature, add 16 parts by weight of zeolite, and then ultrasonically treat for 30 min at a power of 500 W. After ultrasonication, transfer to a constant temperature water bath at 75±2°C and dry; S23. Rinse the dried product with deionized water, and then dry it in an oven at 80±1°C to obtain an iron-aluminum surface-modified zeolite.

[0048] S3. Evenly mix the modified biochar treated in step S2 with 16 parts by weight of zeolite, add 15 parts by weight of an aqueous solution of methyl cellulose and starch, stir until it becomes viscous, add it into a mold, and dry it at 110°C to obtain a denitrification and dephosphorization material for river and lake water.

[0049] The modified biochar prepared in Examples 1 to 9 was tested for specific surface area, porosity, compressive strength, hydrochloric acid solubility, and friction loss rate. The specific surface area was tested using GB / T 7702.20-2008, the porosity was tested using GB / T 14684-2011, the compressive strength was tested using GB / T 1431, the friction loss rate was tested using GB / T40398.1, and the hydrochloric acid solubility test method was to place the material to be tested in a 1 mol / L hydrochloric acid solution, soak for 2 hours, then remove it, dry it, and test the loss; the test results are shown in Table 1 below: Table 1 Test results of biochar index

[0050] According to the data in Table 1, in the embodiment of the present application, by activating the biochar twice, the specific surface area of ​​the biochar can be increased, thereby enhancing the adsorption capacity of the biochar, and the biochar has good porosity and compressive strength, and has good resistance to hydrochloric acid. Compared with pure biochar, the physical and chemical properties are increased, indicating that the physical and chemical properties of the biochar are not reduced by the two activations, but are beneficial. The friction loss rate proves that the modified biochar has good structural strength, that is, it is first activated by zinc chloride and then activated by phosphoric acid, which can increase the specific surface area, compressive strength and structural strength of the straw charcoal, which is beneficial to the use of the modified biochar in water bodies.

[0051] The modified biochar was then tested for its ability to remove ammonia nitrogen, total phosphorus (TP), and oxygen-consuming organic pollutants (COD). The test method was to place the modified biochar in an artificially configured water body with a total ammonia nitrogen concentration of 8.2 mg•L -1 ; Total phosphorus concentration is 10 mg•L -1 ; COD concentration is 85mg•L -1; pH 7.2; placed at 30℃, 160 r•min -1 The test results were shown in Table 2 below: Table 2 Adsorption performance results of modified biochar for ammonia nitrogen, total phosphorus and COD

[0052] According to the data in Table 2, the modified biochar has good removal capabilities for ammonia nitrogen, total phosphorus, and COD, especially in the initial 12-24 hours, it can quickly remove ammonia nitrogen, total phosphorus, and COD in the water body. In 24-48 hours, it can further remove ammonia nitrogen and total phosphorus in the water body, but the removal efficiency of COD is reduced. In terms of total phosphorus removal, it can not only effectively remove high-concentration total phosphorus, but also has a good removal effect on total phosphorus below 0.5 mg / L.

[0053] The denitrification and phosphorus removal materials for river and lake water prepared in Examples 1 to 9 were tested for compressive strength, water permeability, ammonia nitrogen, total phosphorus, and COD. The test methods for ammonia nitrogen, total phosphorus, and COD were the same as those for modified biochar. The test results are shown in Tables 3-4 below: Table 3 Compressive strength and water permeability of denitrification and phosphorus removal materials

[0054] According to the data in Table 3, the materials prepared in Examples 1 to 9 of the present application all have good compressive properties and water permeability. In Examples 1 to 3, different proportions of methyl cellulose and starch have little effect on the compressive strength and water permeability of the materials; in Examples 4 to 6, when adding different proportions of auxiliary materials, the larger the proportion of auxiliary materials, the more obvious the effect on the compressive strength and water permeability of the materials. When the ratio of auxiliary materials to modified biochar is 3.5:10, the compressive strength and water permeability are the best; in Examples 7 to 9, when adding different types of auxiliary materials, when adding bioenzyme charcoal and zeolite, the compressive strength of zeolite as an auxiliary material is better, and the water permeability is not much different. After the surface modification of zeolite, although the compressive strength increases, the water permeability decreases.

[0055] Table 4 Ammonia nitrogen, total phosphorus and COD results of denitrification and phosphorus removal materials

[0056] According to the data in Table 4, the material has good removal capacity for ammonia nitrogen, total phosphorus and COD, and has a significant improvement relative to modified biochar, that is, after adding auxiliary materials, the material can enhance the removal capacity of ammonia nitrogen, total phosphorus and COD. In Examples 1 to 3, different amounts of modified biochar, with the same amount of auxiliary materials, can slightly enhance the material's ability to remove ammonia nitrogen, total phosphorus and COD, while different amounts of adhesives have little effect on the removal of pollutants in water bodies; in Examples 4 to 6, by combining auxiliary materials with modified biochar in different proportions, the material's ability to remove ammonia nitrogen, total phosphorus and COD can be enhanced; in Examples 7 to 9, by adding different auxiliary materials, the material has different effects on the removal capacity of ammonia nitrogen, total phosphorus and COD, among which zeolite has a better effect than bioenzyme charcoal, and by surface modification of zeolite with iron and aluminum, the removal capacity of ammonia nitrogen, total phosphorus and COD can be further enhanced.

[0057] The river and lake water denitrification and phosphorus removal materials in this application can be prepared as follows Figure 3-8 The shape shown can be applied to artificial wetland matrix, pre-treatment filter dam at water source, ecological management filler for river and lake water, ecological floating bed, ecological slope protection, artificial fish reef, biological filter, etc. Its surface is rough and porous, with high porosity, slow release alkalinity, easy for the growth and reproduction of microorganisms, and contains a variety of trace elements that are beneficial to the growth of aquatic plant roots. It can react with phosphates in water to form phosphate precipitates, thereby reducing the phosphate concentration in the water body, and can also make inorganic pollutants settle to the bottom of the bed, and with the water flow flushing to the water outlet, it can delay the time when the wetland filler is blocked.

[0058] The above is a detailed introduction to a river and lake water denitrification and phosphorus removal material and a preparation method thereof provided by the present invention. The description of the specific embodiment is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0059] It should be noted that if no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be purchased commercially.

[0060] The above examples are intended to provide a better understanding of the present invention, and are not intended to be limiting of the best implementation mode described herein, nor are they intended to limit the content and protection scope of the present invention. Any product identical or similar to the present invention that is derived by anyone under the inspiration of the present invention or by combining the present invention with features of other prior arts shall fall within the protection scope of the present invention.

Claims

1. A material for denitrification and phosphorus removal from river and lake water, characterized in that: The invention comprises the following raw materials in parts by weight: 60 to 80 parts of modified biochar, 16 to 40 parts of auxiliary materials and 5 to 15 parts of adhesives, wherein the modified biochar is formed by composite modification of an acidic compound and an inorganic salt.

2. The denitrification and phosphorus removal material for river and lake water according to claim 1, characterized in that: The biomass charcoal is at least one of wood charcoal, fruit shell charcoal, reed charcoal, straw charcoal, algae charcoal and straw charcoal.

3. The material for denitrification and phosphorus removal from river and lake water according to claim 1, characterized in that: The acidic compound is at least one of sulfuric acid, hydrochloric acid, phosphoric acid, bromic acid, perchloric acid and organic acid.

4. The denitrification and phosphorus removal material for river and lake water according to claim 1, characterized in that: The inorganic salt is at least one of zinc chloride, ferric chloride, aluminum chloride and calcium chloride.

5. The material for denitrification and dephosphorization of river and lake water according to claim 1, characterized in that: The auxiliary material is at least one of bio-enzyme charcoal, ferrite, polymeric denitrification carbon, polymeric dephosphorization material, calcite, zeolite, kaolin, calcium oxide, aluminum oxide, plastic suspension balls, and carbon fiber bionic water plants.

6. The material for denitrification and dephosphorization of river and lake water according to claim 1, characterized in that: The binder is at least one of lignin, sodium lignin sulfonate, starch, methyl cellulose, clay and silicate.

7. The material for denitrification and dephosphorization of river and lake water according to claim 1, characterized in that: The river and lake water denitrification and phosphorus removal material is in at least one of a lotus root shape, a porous shape, a sponge shape, and a plum blossom shape.

8. A method for preparing a material for denitrification and dephosphorization of river and lake water, characterized in that: The method of using the river and lake water denitrification and phosphorus removal material according to any one of claims 1 to 7 further comprises the following steps: S1. Place the biochar in clean water, soak and wash for 20 to 40 minutes, and after washing, dry at 100 to 110° C. to obtain the washed biochar; S2. The washed biochar is placed in a container, an inorganic salt solution is added, and the mixture is immersed for 12 to 24 hours under shaking conditions, and then an acidic compound is added, and the mixture is shaken for 24 to 36 hours under the conditions of 55 to 80° C., and then cooled to room temperature. After cooling, the mixture is washed 2 to 3 times to obtain a modified biochar for standby use; S3. Mix the modified biochar treated in step S2 with auxiliary materials, add a binder, mix well and add into a mold, dry at 100-160° C. to obtain a denitrification and phosphorus removal material for river and lake water.

9. The preparation method according to claim 8, characterized in that: In the step S2, during the oscillation of the acidic compound, the acidic compound is replaced at intervals of 8 to 12 hours, and the acidic compound is added again.

10. The preparation method according to claim 8, characterized in that: In the step S3, the particle size of the auxiliary material is larger than the particle size of the modified biochar, and the addition ratio of the auxiliary material to the modified biochar is (2-5):10.

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