Preparation method of filter material, filter material and application of filter material

Abstract

The invention discloses a preparation method of a filter material, the filter material and application of the filter material. The preparation method of the filter material comprises the following steps: obtaining agricultural wastes and forestry wastes; the method comprises the following steps: pre-treating agricultural wastes and forestry wastes, and uniformly mixing to obtain a mixed raw material; performing high-temperature pyrolysis on the mixed raw material to obtain a pyrolysis product; screening and washing the pyrolysis product to obtain a target filter material; wherein the agricultural wastes are selected from at least one of straws, fiber crops, shells, tea residues and food processing wastes; the forestry waste is selected from at least one of wood waste, trees, stumps, bamboo waste and forestry byproducts. The filter material prepared by the preparation method provided by the invention is beneficial to decomposition of fish excrement, can promote growth of aquatic plants, also has a purification effect on water quality, is beneficial to reproduction of nitrifying bacteria, and is high in compressive strength and relatively good in removal capacity on water pollutants; pores are uniform, and the water flow velocity can be adjusted.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a preparation method of a filter material, the filter material and applications thereof. Background Art

[0002] In the process of breeding aquatic animals and plants in fish tanks or water plant tanks, the filtration system is a very important component. It can help maintain the cleanliness of water and provide a healthy living environment for aquatic animals and plants. The filtration system of the fish tank usually includes two parts: the filter and the machine-made material. The machine-made material is also called the filter material. At the same time, most filters also achieve the filtration effect by setting the filter material.

[0003] Existing filter materials mainly include filter cotton, magic carpet, biochemical cotton, ceramic ring, glass ring, bacterial house, biochemical beads / biochemical balls, activated carbon, ammonia absorbing stone, coral sand, volcanic ring, medical stone. However, these filter materials all have their own shortcomings. For example, filter cotton, magic carpet, activated carbon and biochemical cotton are often disposable filter materials, which cannot be washed or regenerated, and most of them have a single function and cannot provide other benefits for the survival of animals and plants; for another example, filter materials such as ceramic rings, glass rings, bacterial houses and biochemical beads / biochemical balls can provide a place for bacteria to survive and other beneficial conditions, but their pressure resistance is weak, they are easy to be damaged or powdered, and their service life is short; for another example, filter materials such as ammonia absorbing stone, coral sand, volcanic ring and medical stone are natural filter materials, energy-saving and environmentally friendly, but they often have uneven porosity, insufficient hardness, easy to break, unstable performance, etc. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a preparation method of a filter material, a filter material and applications thereof, which can provide a new type of filter material that is energy-saving, environmentally friendly and has good performance.

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a filter material, comprising the following steps: obtaining agricultural waste and forestry waste; pre-treating the agricultural waste and forestry waste, and mixing them evenly to obtain a mixed raw material; performing high-temperature pyrolysis on the mixed raw material to obtain a pyrolysis product; screening and washing the pyrolysis product to obtain a target filter material; wherein the agricultural waste is selected from at least one of straw, fiber crops, fruit shells, tea residues and food processing waste; and the forestry waste is selected from at least one of wood waste, trees, stumps, bamboo waste and forestry by-products.

[0006] In a feasible implementation, the agricultural waste is food processing residues, and the forestry waste is bamboo waste and forestry by-products; the total organic carbon mass fraction of the obtained mixed raw materials is ≥60%, and the moisture content is ≤5%.

[0007] In a feasible implementation, the mass ratio of the food processing residues, bamboo waste and forestry by-products is (4-3):3:(3-4).

[0008] In a feasible implementation, the pyrolysis condition is 500° C. to 700° C. in an air atmosphere for 20 seconds to 40 seconds.

[0009] In a feasible implementation, the screening and washing operation includes the following steps: screening and sorting the pyrolysis product to obtain a screened product; washing the screened product with water to obtain a washed product; disc screening the washed product to obtain a target filter material; the particle size of the screened product is 3 mm to 5 mm.

[0010] In a feasible implementation, the preparation method further includes: placing the target filter material into a die-casting mold to obtain a filter material of a target shape.

[0011] Correspondingly, the present invention also provides a filter material prepared by the above-mentioned preparation method.

[0012] In a feasible implementation, the filter material has a particle size of 0 to 5 mm, a porosity of 40% to 60%, and a specific surface area (1.4×10 5 ~2.3×10 5 )cm 2 / g.

[0013] In a feasible implementation, the compressive strength of the filter material is greater than 20 MPa.

[0014] Correspondingly, the present application also provides the use of the above-mentioned filter material as a machine material for a fish tank or a filter material for a fish tank.

[0015] The implementation of the present invention has the following beneficial effects:

[0016] The preparation method of the filter material provided in the embodiment of the present application produces a new filter material by pyrolyzing agricultural waste, food processing residues and forestry byproduct waste. The raw materials are energy-saving and environmentally friendly, and the preparation process is simple. The filter material prepared by the preparation method of the filter material provided in the embodiment of the application is conducive to the decomposition of fish excrement when used as a machine material, can promote the growth of aquatic plants, and can also be made into various landscape products according to the mold form, and also has the effect of purifying water quality; when the prepared filter material is used as a filter material, it is conducive to the reproduction of nitrifying bacteria, has high compressive strength, and has a good ability to remove water pollutants; at the same time, the pores are uniform, which is conducive to regulating the flow rate of water. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an exemplary flow chart of the method for preparing the filter material shown in some embodiments of the present application. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0020] This embodiment of the application provides a method for preparing a filter material. Figure 1 , the preparation method of the filter material comprises the following steps:

[0021] S110. Obtain agricultural waste and forestry waste;

[0022] The agricultural waste is selected from at least one of straw, fiber crops, fruit shells, tea residues and food processing waste; the forestry waste is selected from at least one of wood waste, trees, stumps, bamboo waste and forestry by-products.

[0023] In a feasible embodiment, the agricultural waste is selected from at least one of straw, fiber crops, fruit shells, tea residues and food processing waste. Among them, the total organic carbon mass fraction of wheat straw is about 47.1%, and the total organic carbon mass fraction of corn straw is about 43.3%; the moisture content of wheat and corn straw is about 10.6% and 11.2%. Fiber crops refer to a type of crop that uses its fiber as an industrial raw material. Among agricultural waste, the carbon content of fiber crops is about 36.2% to 42.1%; the moisture content standard of cotton fiber is 7-10%. The moisture content standard of flax fiber is 12-14%. The moisture content standard of wool fiber is 12-18%. The moisture content standard of silk fiber is 11-15%. Hemp fiber: The moisture content standard of hemp fiber is 10-15%. The overall moisture content of fiber crops is about 7% to 15%. Using the agricultural waste as raw material can not only reduce environmental pollution, but also realize the recycling of resources. Optionally or preferably, the agricultural waste is food processing residue. Food processing residue refers to byproducts or waste generated during food processing, which are usually not part of the final product. According to different processing processes and raw material types, food processing residues can be very diverse, mainly including peels, cores, etc. left after fruit processing (such as apple juice and orange juice production); the remaining parts after vegetable processing (such as slicing and peeling), such as leaves, roots, etc.; shells and bran produced during grain processing (such as rice and wheat); bones, viscera, etc. produced during slaughtering and processing meat and fish; byproducts produced during dairy production, such as whey produced during cheese production; oil byproducts, such as oil residue or cake residue left after oil extraction. Among them, the organic matter content of tofu residue is 98.54%, and the moisture content of fresh tofu residue is about 82% to 89%. After the tofu residue is treated with near-critical water, the moisture content of the filter residue is about 30% to 50%. The moisture content of okra pods is 90.27%. The moisture content of corn cobs is 15.43%. The moisture content of seed pumpkin flesh and skin is 94.99%. The organic carbon content in tea residue is about 28.11%. The moisture content (SCR) of tea residue is about 60.41%. Choosing food processing residue as raw material can reuse waste resources, save energy consumption for processing food processing residue, promote resource recycling, maintain ecological balance, and reduce damage to the natural environment. At the same time, using food processing residue as raw material can also reduce the cost of raw material procurement and improve production efficiency.

[0024] In a feasible embodiment, the forestry waste is selected from at least one of wood waste, trees, stumps, bamboo waste and forestry by-products. Using the forestry waste as raw materials can not only reduce environmental pollution, but also realize the recycling of resources. Optionally or preferably, the forestry waste is bamboo waste and forestry by-products. Bamboo waste refers to waste and by-products generated during bamboo processing. These wastes generally include bamboo processing, waste generated when making bamboo products (such as furniture, flooring, bamboo sticks, etc.); bamboo shoot processing: waste generated during bamboo shoot picking and processing, such as bamboo shoot shells; bamboo fiber extraction: waste generated when bamboo fiber is extracted for textiles or composite materials; bamboo papermaking: waste generated during bamboo papermaking. Bamboo grows fast and is a renewable resource. Its waste also has the advantage of sustainable utilization. The reuse of bamboo waste helps to reduce carbon emissions and meets environmental protection requirements. Forestry by-products refer to waste and by-products generated during the processing of wood and other forest products. These byproducts usually include bark produced during tree peeling; small fragments and powder produced during wood cutting, grinding, planing and other processing; branches and leaves produced during tree pruning and felling; larger pieces of wood produced during wood processing; and tree roots left over during tree felling. Using forestry byproducts as raw materials can reduce environmental pollution; convert waste into valuable resources and reduce dependence on primary resources; promote sustainable use of resources and extend the forestry industry chain. Among them, the carbon content of wood waste is about 76% to 85%, and the moisture content is about 8% to 15%; the carbon content of trees is about 41% to 43%, and the moisture content is about 70% to 80%. The carbon content of tree stumps is about 40% to 60%, and the moisture content is about 60% to 70%; the carbon content of bamboo waste is about 40% to 50%, and the moisture content is about 5% to 8%; the carbon content of forestry byproducts is about 50% to 60%, and the moisture content is about 10% to 20%.

[0025] In a feasible implementation, the agricultural waste is food processing residues, and the forestry waste is bamboo waste and forestry byproducts. In this way, the food processing residues, bamboo waste and forestry byproducts are mixed as raw materials, and the prepared filter material has better various properties through the coordination of different raw material components.

[0026] S120, pre-treating the agricultural waste and forestry waste, and mixing them evenly to obtain a mixed raw material.

[0027] Among them, the uniform mixing method can be mechanical stirring and mixing. For example, using a device such as a stirrer or a mixer, the materials are fully mixed through mechanical movement (such as rotation, shaking, vibration, etc.). Such a mixing method is easy to operate, has a good mixing effect, and is suitable for large-scale production. The uniform mixing method can also be air flow mixing. For example, using devices such as an air flow mixer and a fluidized bed mixer, the materials are suspended and mixed uniformly using a high-speed airflow. Such a mixing method has a fast mixing speed and a high mixing uniformity.

[0028] In a feasible implementation, the pretreatment of the agricultural waste and forestry waste may include dehydration and drying treatment and molding treatment. Among them, the dehydration and drying treatment may be a natural drying dehydration and drying treatment, using natural conditions (such as sunlight and wind) to evaporate the water in the material. Such dehydration has low cost and simple operation. It can also be hot air drying, by blowing hot air on the surface of the material to accelerate the evaporation of water. In this way, the drying speed is fast, the operation is flexible, and it is suitable for large-scale production. Disadvantages: high energy consumption, temperature-sensitive materials may affect the quality. It can also be vacuum drying, in a low-pressure environment, the boiling point of water is reduced, thereby accelerating the evaporation of water. It can also be centrifugal dehydration, using centrifugal force to separate water from the material. It can also be dehydration by filtration, separating water from the material by a filter medium (such as filter cloth, filter screen), and using a filter press for dehydration and drying. Among them, the dehydration and drying treatment can also be a mixture of the above-mentioned dehydration methods, such as first performing natural drying and dehydration treatment, then placing it in a filter press for dehydration treatment, and then drying it by hot air. This can save a certain amount of energy consumption and improve drying efficiency. The drying process can be to put the agricultural waste and forestry waste that have been dehydrated and dried into a high-temperature furnace for drying. Among them, the molding process can be to process the material according to a specific shape and size, which can be formed by extrusion molding, die-casting molding, stamping molding, compression molding or thermoforming. For example, the agricultural waste and forestry waste that have been dried are placed in a spiral molding machine for molding. The molding process can facilitate production and processing, raw material classification, and transportation, and can accurately control the size and shape of the product to ensure the consistency of each product.

[0029] In a feasible implementation, the total organic carbon mass fraction of the obtained mixed raw material is ≥60%, and the moisture content is ≤5%. Such raw materials are easy to pyrolyze, and the prepared filter material has good comprehensive performance.

[0030] In a feasible implementation, the mass ratio of the food processing residues, bamboo waste and forestry by-products is (4-3):3:(3-4) 。Such a ratio setting can make the prepared filter material conducive to the decomposition of fish excrement, promote the growth of aquatic plants, and can also be made into various landscape products according to the mold form, which also has the effect of purifying water quality; when the prepared filter material is used as a filter material, it is conducive to the reproduction of nitrifying bacteria, has high compressive strength, and has a good ability to remove water pollutants; at the same time, the pores are uniform, which is conducive to regulating the flow rate of water. The organic matter in fish excrement mainly comes from the decomposition of residual feed and excrement of aquaculture organisms. The concentration of organic matter is usually measured in chemical oxygen demand (COD). Microorganisms will quickly degrade organic matter when COD and dissolved oxygen (DO) are sufficient. The nitrogen in aquaculture wastewater mainly comes from residual feed and excrement of aquaculture organisms. Nitrogen and phosphorus are the main factors of eutrophication of water bodies. Controlling their discharge helps to reduce eutrophication of water bodies, thereby indirectly promoting the decomposition of fish excrement. Ammonia nitrogen and nitrite are important indicators in water bodies. Their presence is directly toxic to fish. Controlling these indicators within an appropriate range helps maintain water quality and promote the decomposition of fish excrement. Among them, the range of chemical oxygen demand (COD) of fish farming water quality varies according to different fish and breeding environments. Here are some specific ranges: For high-yield fish ponds such as grass carp, the appropriate COD value is generally 10-20mg / L; for ponds of fish species such as silver carp and tilapia, the optimal COD range is 25-30mg / L. These ranges provide suitable COD content for different fish to ensure that the water quality is suitable for fish growth. Too high COD values ​​may indicate that the water body has a high content of organic matter, which may have an adverse effect on fish health and growth. Therefore, controlling the COD of the fish tank water within these suitable ranges is conducive to maintaining water quality and promoting the healthy growth of fish.

[0031] The control ranges of nitrogen and phosphorus in fish farming water are as follows: According to the Fishery Water Quality Standard (GB11607-1989), the limit value of total nitrogen (TN) is no more than 1.00 mg / L, and the limit value of total phosphorus (TP) is no more than 0.20 mg / L. These standards provide specific control ranges for the nitrogen and phosphorus content in fish farming water to ensure that the water quality is suitable for fish growth and meets environmental protection requirements. The control ranges of ammonia nitrogen and nitrite in fish farming water are as follows: According to the Fishery Water Quality Standard, the ammonia nitrogen content should generally not exceed 2 mg / L. When it exceeds 2.00 mg / L, fish will show symptoms of ammonia nitrogen poisoning. For precious fish, ammonia nitrogen should be controlled below 0.5 mg / L. The content of nitrite should be controlled below 0.2 mg / L. The excellent standard, the nitrite content should be less than 0.1 mg / L. For the normal value of nitrite in fish ponds, it is usually between 0 and 0.1 mg / L. These ranges provide guidance for safe concentrations of ammonia nitrogen and nitrite in fish culture water to ensure that the water quality is suitable for fish growth and to prevent toxic effects on fish.

[0032] The growth of hydroponic plants requires the following key conditions:

[0033] 1. pH value: In the growth environment of hydroponic plants, the pH value has an important influence on the efficiency of plant absorption of nutrients. The suitable pH value range is usually 5.5-6.5.

[0034] 2. Electrical conductivity (EC): The conductivity reflects the concentration of dissolved salts in the nutrient solution. Too high or too low will inhibit plant growth. Generally, it is maintained at 1 to 3 dSm -1 .

[0035] According to the test, after one week of cultivating the water body, the pH value and conductivity of the fish tank filter material provided in the embodiment of the present application meet the above requirements, which is beneficial to the growth of animals and plants and optimizes the growth environment of animals and plants.

[0036] S130, performing high-temperature pyrolysis on the mixed raw material to obtain a pyrolysis product;

[0037] In a feasible implementation, the pyrolysis condition is 500°C to 700°C for 20 to 40 seconds in an air atmosphere. Such pyrolysis conditions can better decompose the mixed raw materials, decompose the organic matter and extract valuable products to the maximum extent, convert most of the organic matter into useful products, reduce the generation of waste, and make the final filter material have better performance.

[0038] S140, screening and washing the pyrolysis product to obtain a target filter material.

[0039] In a feasible implementation, the screening and washing operation comprises the following steps:

[0040] S141, sieving and sorting the pyrolysis product to obtain a sieved product;

[0041] S142, washing the sieved product with water to obtain a washed product;

[0042] S143, performing disc screening on the washed product to obtain a target filter material;

[0043] The particle size of the sieved product is 3 mm to 5 mm.

[0044] In a feasible implementation, the preparation method further comprises:

[0045] Step S150: Evenly mix the target filter material and the binder, and put them into a die-casting mold to obtain a filter material of a target shape.

[0046] In a feasible implementation, step S150 can be a separate process. Specifically, the target filter material after the pyrolysis screening is used as a raw material, mixed with a certain proportion of a binder, and shaped by a die-casting process under a specific mold. Furthermore, the ratio of the target filter material to the binder is 7:3 to 8:2. Among them, the binder can be a cement-based material, which can be cement or a cement substrate with similar properties to cement materials.

[0047] In this way, by manufacturing different forms of die-casting molds, different forms of fish tank landscaping ornaments can be pressed, which can realize the landscaping function while realizing the function of the filter material.

[0048] Correspondingly, the present application also provides a filter material, which is prepared by the above-mentioned preparation method.

[0049] The filter material provided in the embodiment of the present application is produced by pyrolyzing agricultural waste, food processing residues and forestry byproduct waste, and a new filter material is produced. The raw materials are energy-saving and environmentally friendly, and the preparation process is simple. The filter material prepared by the preparation method of the filter material provided in the embodiment of the application is conducive to the decomposition of fish excrement when used as a machine material, can promote the growth of aquatic plants, and can also be made into various landscape products according to the mold form, and also has the effect of purifying water quality; when the prepared filter material is used as a filter material, it is conducive to the reproduction of nitrifying bacteria, has high compressive strength, and has a good ability to remove water pollutants; at the same time, the pores are uniform, which is conducive to regulating the flow rate of water.

[0050] In a feasible implementation, the filter material has a porosity of 50% to 65%, a void ratio of 50.5%, a wear rate of 34.15%, and a specific surface area of ​​1.51×105cm 2 / g. Such filter materials, due to their large porosity, can reach 50% to 65%, which is conducive to the biofilm formation of microorganisms and the reproduction of nitrifying bacteria; the wear rate is low, the filter material is wear-resistant, not easy to pulverize, and has a long service life. Specific surface area refers to the total surface area per unit mass of material. Materials with high specific surface area can adsorb more gas or liquid molecules and increase adsorption capacity. Materials with high specific surface area can provide more active sites, which are conducive to the biofilm formation of microorganisms and the reproduction of nitrifying bacteria.

[0051] In a feasible implementation, the compressive strength of the filter material is greater than 20 MPa, and its compressive strength can reach 20 MPa, which is much higher than the common ceramic materials on the market. Materials with high compressive strength can withstand greater loads and improve the stability and safety of the structure. When subjected to external pressure, materials with high compressive strength deform less and maintain the integrity and function of the structure. Materials with high compressive strength are not easily damaged during long-term use, which extends the service life of materials and structures. The frequency of repairs and replacements caused by material damage is reduced, and maintenance costs are reduced. Materials with high compressive strength can reduce material usage, reduce resource consumption, and meet the requirements of sustainable development. The material has a long service life, reduces waste generated by replacement and maintenance, and reduces pollution to the environment.

[0052] Correspondingly, the present application also provides the application of the filter material as a machine material for fish tanks or a filter material for fish tanks. The filter material provided in the embodiment of the present application can be used as a machine material or as a filter material for a filter. It has the following three characteristics when used as a machine material: 1) It is conducive to the decomposition of fish excrement; 2) It can promote the growth of aquatic plants; 3) It can be made into various landscape products according to the mold form, and it also has the effect of purifying water quality. The use of the material as a filter material can have the following characteristics: 1) Because the material has a large porosity, its porosity can reach 50% to 65%, which is conducive to the biofilm of microorganisms and the reproduction of nitrifying bacteria; 2) It has a certain strength, and its compressive strength can reach 20mpa, which is much higher than the common ceramic materials on the market; 3) It has the ability to remove water pollutants. After culturing the water body for one week, it was tested that the suspended matter content in the water was SS <0.6 (NUT), the dissolved oxygen concentration in the water was DO>5.5mg / L, the total phosphorus TP <0.1mg / L, and the ammonia nitrogen NH4 + <0.9ml / L, total organic carbon index TOC<3.5mg / L. 4) The pores are uniform, which is conducive to regulating the water flow rate.

[0053] With reference to the above implementation contents, in order to make the technical solution of the present application more specific, clear and easy to understand, the technical solution of the present application is now exemplified. However, it should be noted that the contents to be protected by the present application are not limited to the following embodiments.

[0054] Example 1

[0055] Access to food processing residues, bamboo waste and forestry by-products, specifically straw, bamboo waste and forestry by-products;

[0056] Pre-treating food processing residues, bamboo waste and forestry by-products in a mass ratio of 4:3:3 and mixing them evenly to obtain a mixed raw material, wherein the total organic carbon mass fraction of the mixed raw material is 80% and the moisture content of the mixed raw material is 3%;

[0057] Pyrolyzing the mixed raw material at a high temperature of 600° C. for 30 seconds to obtain a pyrolysis product;

[0058] The pyrolysis products are screened to keep the material with a particle size of 3 to 5 mm;

[0059] After washing with water to remove the residue on the surface, the target filter material with regular particle size is obtained after passing through a disc sieve.

[0060] Example 2

[0061] The method is substantially the same as Example 1, except that the mass ratio of food processing residues, bamboo waste and forestry by-products is 3:3:4.

[0062] Example 3

[0063] The method is basically the same as Example 1, except that the moisture content of the mixed raw material is 5%.

[0064] Example 4

[0065] It is basically the same as Example 1, except that the raw materials used are straw, fruit shells and forestry by-products, and the mass ratio of straw: fruit shells: forestry by-products is 4:3:3.

[0066] Example 5

[0067] The method is basically the same as Example 1, except that the high temperature pyrolysis conditions are 700° C. and 20 seconds in air atmosphere.

[0068] Example 6

[0069] The method is basically the same as Example 1, except that the high temperature pyrolysis conditions are 500° C. and 40 seconds in air atmosphere.

[0070] Comparative Example 1

[0071] A volcanic rock filter material on the market

[0072] Comparative Example 2

[0073] Commercially available bacterial house filter material

[0074] Comparative Example 3

[0075] A ceramic ring filter material on the market

[0076] Performance Testing

[0077] 1. Porosity detection

[0078] The porosity of the filter materials of the embodiment and the comparative example was tested according to the CJ-T299-2008 standard;

[0079] 2. Specific surface area detection

[0080] The specific surface areas of the filter materials of the embodiments and comparative examples were measured using the BET method;

[0081] 3. Wear rate detection

[0082] Weigh about 100g of the washed, dried and retained sample in the filter material with a pore size of 0.5mm, place it in a metal cylinder with an inner diameter of 50mm and a height of 150mm, add 6 bearing steel balls with a diameter of 8mm, cover the cylinder tightly, and oscillate on an oscillator with a stroke of 140mm and a frequency of 150 times / min for 15min, and weigh the mass of the sample that passes through the test sieve with a pore size of 0.5mm.

[0083] The wear amount is calculated by measuring the percentage change in the mass of the filter material before and after wear.

[0084] 4. Compressive strength test

[0085] The compressive strength test was carried out using an electronic universal mechanical testing machine.

[0086] 5. Detection of harmful heavy metal components

[0087] Take the filter material sample prepared in Example 1 and test the harmful heavy metal components of the filter material sample. Testing standard: "National Hazardous Waste Identification Standard - Toxic Substance Content Identification" (GB5085.6-2007); Comparison standard: "Soil Environmental Quality Standard" (GB15618-1995).

[0088] The results are as follows:

[0089] Number Cr Mn Ni Cu Zn As Cd Pb Unit ug / L ug / L ug / L ug / L ug / L ug / L ug / L ug / L 1 566 9426 298 1226 8045 282 40.1 801 2 567 8855 285 1152 7654 273 39.1 834 3 519 8412 269 1139 7288 261 37.4 836 4 531 8735 299 1138 7631 272 40.2 877 5 519 8590 277 1092 7399 269 38.5 863 6 502 8235 287 1089 7239 250 39.1 871 7 609 6422 151 175 3950 249 3.70 293 8 589 6240 143 177 3884 239 4.66 294 9 652 6380 157 179 3829 237 4.72 323

[0090] 6. Water decontamination capacity test

[0091] After one week of culturing the water, the suspended solids content NUT, dissolved oxygen concentration mg / L, total phosphorus mg / L, ammonia nitrogen ml / L, total organic carbon index mg / L; pH value and conductivity ECdSm -1 .

[0092] The above test results are shown in Tables 1 to 3.

[0093] Table 1: Physical properties test results, including porosity, specific surface area, wear rate and compressive strength.

[0094]

[0095] Table 2: Related parameters of fish tank filter media in water:

[0096]

[0097] Table 3: Parameters related to the growth conditions of hydroponic plants in the water body of the fish tank filter:

[0098]

[0099] It can be seen from the above test results that 1) the filter material provided by Examples 1 to 6 of the present application has a large porosity, which can reach 50% to 65%, which is conducive to the biofilm of microorganisms and the reproduction of nitrifying bacteria; the pores are uniform, which is conducive to regulating the flow rate of water. 2) It has a certain strength, and its compressive strength can reach 20mpa, which is much higher than the filter material provided by Comparative Examples 1 and 3; 3) It has the ability to remove water pollutants. After culturing the water body for one week, it was tested that the suspended matter content in the water was SS <0.6 (NUT), the dissolved oxygen concentration in the water was DO>5.5mg / L, the total phosphorus TP <0.1mg / L, the ammonia nitrogen NH4+ <0.9ml / L, and the total organic carbon index TOC <3.5mg / L, which meets the industry standards and is conducive to the purification of the water body. 4) The pH value and conductivity of the fish tank filter material provided by the present application embodiment are more conducive to the growth of aquatic plants than the filter material provided by Comparative Examples 1-3.

[0100] Among them, the filter material provided in Example 1 has the best comprehensive performance and is conducive to wide application.

[0101] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to this specification. Such modifications, improvements and corrections are suggested in this specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of this specification.

[0102] At the same time, this specification uses specific words to describe the embodiments of this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this specification can be appropriately combined.

[0103] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this specification, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this specification.

[0104] Similarly, it should be noted that in order to simplify the description disclosed in this specification and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this specification, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0105] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0106] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this specification are hereby incorporated by reference in their entirety. Except for application history documents that are inconsistent with or conflicting with the contents of this specification, documents that limit the broadest scope of the claims of this specification (currently or later attached to this specification) are also excluded. It should be noted that if the descriptions, definitions, and / or use of terms in the materials attached to this specification are inconsistent or conflicting with the contents described in this specification, the descriptions, definitions, and / or use of terms in this specification shall prevail.

[0107] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A method for preparing a filter material, characterized in that: The following steps are involved: Acquisition of agricultural and forestry wastes; Pre-treating the agricultural waste and forestry waste, and mixing them evenly to obtain a mixed raw material; Performing high-temperature pyrolysis on the mixed raw material to obtain a pyrolysis product; Screening and washing the pyrolysis products to obtain target filter materials; Wherein, the agricultural waste is selected from at least one of straw, fiber crops, fruit shells, tea residues and food processing waste; The forestry waste is selected from at least one of wood waste, trees, stumps, bamboo waste and forestry by-products.

2. The preparation method according to claim 1, characterized in that: The agricultural waste is food processing residues, The forestry waste is bamboo waste and forestry by-products; The total organic carbon mass fraction of the obtained mixed raw material is ≥60%, and the moisture content is ≤5%.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the food processing residues, bamboo waste and forestry by-products is (4-3):3:(3-4).

4. The preparation method according to claim 1, characterized in that: The high temperature pyrolysis conditions are 500° C. to 700° C. and a time of 20 to 40 seconds in an air atmosphere.

5. The preparation method according to claim 1, characterized in that: The screening and washing operation comprises the following steps: Screening and sorting the pyrolysis product to obtain a screened product; washing the sieved product with water to obtain a washed product; The washed product is subjected to disc screening to obtain a target filter material; The particle size of the sieved product is 3 mm to 5 mm.

6. The preparation method according to claim 1, characterized in that: The preparation method further comprises: The target filter material and the binder are evenly mixed and placed into a die-casting mold to obtain a filter material of a target shape.

7. A filter material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.

8. The filter material according to claim 7, characterized in that The particle size of the filter material is 0-5 mm, the porosity is 40%-60%, and the specific surface area (1.4×10 5 ~2.3×10 5 )cm 2 / g.

9. The filter material according to claim 7, characterized in that The compressive strength of the filter material is greater than 20 MPa.

10. Use of the filter material according to claims 7 to 9 as a machine material for fish tanks or a filter material for fish tanks.

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