A lightweight permeable material for denitrification and phosphorus removal, and its preparation method and application

Abstract

The present application discloses a lightweight water-permeable material for denitrification and phosphorus removal, and its preparation method and application, which belongs to the technical field of environmental functional materials. Dry mortar is obtained by uniformly mixing cement, enhanced phosphorus removal components, and reinforcing materials; foaming agent is preformed into foam by a foaming machine; and light water-permeable material for denitrification and phosphorus removal is obtained by adding dry mortar to the foam in batches and stirring. The light water-permeable material for denitrification and phosphorus removal of the present invention has the characteristics of good water permeability, high specific surface area, easy microbial biofilm, slow release of calcium and iron ions for phosphorus removal, etc. It can be used as a matrix material for ecological floating beds and ecological floating islands, slope protection materials for rivers and ditches, pollutant interception materials in sponge city construction, filling materials for ecological wetland filter beds and water purification landscape structures, in-situ and ex-situ purification materials for polluted water bodies, microbial biofilm materials, etc., and has a good purification effect on pollutants in water bodies, especially total nitrogen and total phosphorus.

Description

Technical Field

[0001] The present application belongs to the technical field of environmental functional materials, and specifically relates to a lightweight, permeable material for denitrification and dephosphorization, and a preparation method and application thereof. Background Art

[0002] With the rapid development of my country's economy, the disorderly discharge of pollutants such as nitrogen and phosphorus has increased, making water pollution increasingly serious. The continuous accumulation of pollutants such as nitrogen and phosphorus in water bodies will aggravate the eutrophication of water bodies, posing a major threat to the water environment and aquatic ecosystems. With the continuous deepening of current technological research, biodegradation technology has attracted considerable attention. As the name suggests, biological methods use the absorption and degradation of plants and microorganisms to effectively degrade nitrogen and phosphorus in water bodies. However, if the plants are not harvested and cleaned in time after absorption and degradation, the absorbed nitrogen and phosphorus will be released again, causing secondary pollution to the water body. Therefore, microbial degradation technology is widely used, both in the removal of nitrogen and phosphorus in sewage treatment plants and in the removal of nitrogen and phosphorus in natural water bodies.

[0003] However, microbial degradation technology has certain limitations when applied to natural water bodies, requiring a carrier for attachment. Currently, the most commonly used carriers are plastic spheres or bio-ropes. These have the disadvantages of small attachment areas and a narrow scope of engineering applications, making them unsuitable for current major nitrogen and phosphorus pollution scenarios, such as farmland drainage management. Furthermore, their nitrogen removal effectiveness is limited, and their phosphorus removal efficiency is poor.

[0004] Therefore, in engineering applications, porous materials that can remove nitrogen and phosphorus and are easy for microorganisms to attach have always been a technical problem that needs to be solved. Summary of the Invention

[0005] 1. Problem to be solved

[0006] This application addresses the problem that the water purification capacity of traditional permeable materials in the prior art, mainly the nitrogen and phosphorus treatment capacity, cannot meet the requirements of the water environment. It provides a lightweight permeable material for denitrification and phosphorus removal, its preparation method and application. The lightweight permeable material for denitrification and phosphorus removal is formed by using prefabricated foam and multiple batches of spraying gelling material wrapping molding method. The lightweight permeable material contains a large number of interconnected micropores inside. The large number of irregular microporous channels combined with the water permeability formed by the material's own adhesion can greatly improve the adsorption, water storage and water permeability of the permeable material; by strengthening the addition of phosphorus removal components, The special foaming preparation process and the water permeability of the material can enable the material to directly or indirectly release calcium and iron ions, greatly improving the lightweight permeable material's ability to remove phosphorus. In addition, the addition of lanthanum improves the material's coordination adsorption capacity and enhances the material's ability to remove phosphorus. At the same time, the large number of interconnected micropores formed inside the lightweight permeable material can provide a larger attachment space for water microorganisms. The three-dimensional interconnected structure forms a spatial structure with different oxygen contents on the vertical interface, which can form a three-dimensional microbial community structure, thereby effectively removing pollutants such as nitrogen from the water body and improving the water purification ability of the lightweight permeable material.

[0007] 2. Technical solution

[0008] In order to solve the above problems, the technical solutions adopted in this application are as follows:

[0009] The present application provides a lightweight, water-permeable material for denitrification and phosphorus removal, which includes a lightweight, slow-release skeleton structure and water-permeable micropores; the water-permeable micropores are distributed inside the lightweight, slow-release skeleton structure, and the lightweight, slow-release skeleton structure contains an open-pore structure with a water-permeability effect; the lightweight, slow-release skeleton structure is prepared by mixing dry mortar mixed with cement, reinforced phosphorus removal material, and reinforcing material with prefabricated foam in batches to form a porous lightweight mortar, which is then formed.

[0010] Furthermore, the mass percentages of cement, enhanced phosphorus removal material, and reinforcing material in the dry-mixed mortar are 50% to 70% cement, 30% to 47% enhanced phosphorus removal material, and 0% to 3% reinforcing material, respectively.

[0011] Furthermore, the above-mentioned enhanced phosphorus removal material includes the following substances in mass fractions: 15-50% calcium salt, 5-15% iron salt, 5-10% lanthanum salt, 10-60% kaolin, and 10-60% diatomaceous earth.

[0012] Furthermore, the above-mentioned reinforcing material includes inorganic fibers and / or synthetic fibers. The inorganic fiber material can be glass fiber with a length of 3 to 10 mm.

[0013] The present application also provides a method for preparing the above-mentioned lightweight permeable material for denitrification and phosphorus removal, comprising: thoroughly stirring and mixing cement, a reinforced phosphorus removal material, and a reinforcing material to obtain a uniformly mixed dry mortar;

[0014] Diluting the foaming agent by 30 to 50 times and preparing foam at a gas-liquid ratio of 95% to 100%;

[0015] The porous lightweight mortar is prepared by mixing dry mortar and foam in batches;

[0016] The porous lightweight mortar is prepared into a lightweight and permeable material through a molding module.

[0017] Furthermore, the cement, enhanced phosphorus removal material and reinforcing material are fully stirred and mixed at a stirring speed of 30 to 100 r / min, and the stirring time is 30 to 60 s.

[0018] Furthermore, the foaming agent can be a plant protein foaming agent or a synthetic protein foaming agent.

[0019] Furthermore, the above-mentioned preparation of porous lightweight mortar by mixing dry-mixed mortar and foam in batches includes: uniformly spraying dry-mixed mortar into prefabricated foam in batches, and stirring at a uniform speed of 100 to 300 r / min until the mortar and foam are fully fused to obtain porous lightweight mortar.

[0020] Furthermore, the number of batches of uniformly spraying dry mortar is 6 to 13.

[0021] Furthermore, the ratio of the dry-mix mortar to foam is such that the foam volume required for every 100 grams of dry-mix mortar is 0.4 to 0.6 L.

[0022] Furthermore, the above-mentioned forming module includes preparing porous lightweight mortar into modules of different sizes and shapes according to different engineering needs, or performing large-area paving, and a certain period of maintenance is required during the forming period.

[0023] Furthermore, the above-mentioned curing method is to carry out an initial setting period of 2 to 3 days after the porous lightweight mortar enters the mold, and after demoulding, carry out moisturizing curing for 7 days.

[0024] Furthermore, the aforementioned moisturizing curing includes covering with a moisturizing film and periodically spraying with clean water. During subsequent curing, the air humidity is maintained above 70%, with a total curing time of 25 to 30 days. During the initial setting period of the material, the amount of water sprayed for curing should be controlled to avoid reducing the strength and pore-forming effect of the formed material.

[0025] The present application also provides the use of the above-mentioned lightweight permeable material for denitrification and phosphorus removal in the water purification process, which can effectively remove pollutants such as nitrogen and phosphorus in the water.

[0026] Furthermore, the above applications include lightweight permeable materials as matrix materials for ecological floating beds and ecological floating islands, slope protection materials for rivers and ditches, pollutant interception materials in sponge city construction, ecological wetland filter beds and filling materials for water purification landscape structures, in-situ and ex-situ purification materials for polluted water bodies, and / or microbial biofilm materials.

[0027] 3. Beneficial effects

[0028] Compared with the prior art, the present application has the following advantages:

[0029] (1) The present application provides a lightweight permeable material for denitrification and phosphorus removal and a preparation method thereof, which comprises the following steps: uniformly mixing cement, a reinforced dephosphorization material, and a reinforcing material to obtain a dry mortar; using a foaming machine to make a prefabricated foam with the prepared foaming liquid under certain parameter conditions; spraying the dry mortar evenly in batches into the prefabricated foam, stirring, and forming the mortar each time; and forming the mortar into the size and shape required for the project through a mold, and wet curing to obtain the lightweight permeable material for denitrification and phosphorus removal. The lightweight permeable material for denitrification and phosphorus removal provided by the present application has the characteristics of good water permeability, high specific surface area, easy microbial biofilm formation, and slow release of calcium and iron ions for phosphorus removal.

[0030] (2) The present application provides a method for preparing a lightweight, water-permeable material for denitrification and phosphorus removal. By adding dry powder mortar to prefabricated foam in batches, the mortar is gradually formed in the form of particle wrapping, and disordered small holes are formed between the particles, which improves the overall fluffy state of the material and forms it layer by layer, thereby improving the water permeability and water storage performance of the material. The large number of micropores inside the material greatly improve the adsorption performance of the material; at the same time, the open-pore characteristics of the pores inside the lightweight material improve the water seepage effect of the material, so that the material itself has a certain water absorption and water storage function, thereby improving the pollution removal performance of the lightweight, water-permeable material.

[0031] (3) The present application provides a lightweight permeable material for denitrification and phosphorus removal and a preparation method thereof. By adding a component that enhances phosphorus removal, the ability of the lightweight permeable material to slowly release calcium ions and iron ions is improved. At the same time, the addition of lanthanum changes the surface properties of the material and improves the coordination adsorption properties of the material. Combined with the material's own permeability and water storage properties, the phosphorus removal capacity of the material is greatly improved.

[0032] (4) The present application provides a lightweight permeable material for denitrification and phosphorus removal, and its preparation method and application. The preparation process of the lightweight porous material is simple and low-cost. The required materials are basic engineering materials, which are suitable for large-scale production and engineering applications. The material has a high degree of molding and can be made into different shapes and sizes according to engineering needs. It can be used as a paving material for farmland drainage ditches, a bank protection material for river ditches, a water storage material for sponge cities, an artificial wetland filter bed, and a water interception dam. It has a good purification effect on pollutants in water bodies, especially total nitrogen and total phosphorus. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the total nitrogen concentration degradation curve.

[0034] Figure 2 is the degradation curve of total phosphorus concentration.

[0035] Figure 3 It is a lightweight porous and permeable material with a porous surface.

[0036] Figure 4 It is a water permeability experiment of lightweight porous permeable materials.

[0037] Figure 5 It is the degradation curve of total phosphorus concentration in lightweight porous permeable materials.

[0038] Figure 6 This is the degradation curve of total phosphorus concentration of ordinary stirring-formed materials. DETAILED DESCRIPTION

[0039] The present application is further described below with reference to specific embodiments.

[0040] It should be noted that the terms such as "upper", "lower", "left", "right", and "middle" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of this application without substantially changing the technical content.

[0041] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0042] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0043] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement, or value. One skilled in the art can readily determine the degree of flexibility for a particular variable.

[0044] As used herein, the term "at least one of" is intended to be synonymous with "one or more of." For example, "at least one of A, B, and C" explicitly includes only A, only B, only C, and combinations of each thereof.

[0045] Concentration, amount and other numerical data can be presented in range format in this article.Should be understood that such range format is only used for convenience and brevity, and should be flexibly interpreted as not only including the numerical value clearly described as range limit, but also including all independent numerical values ​​or subranges encompassed within the scope, just as each numerical value and subrange are clearly described.For example, the numerical range of about 1 to about 4.5 should be interpreted as not only including the limit value of 1 to about 4.5 clearly described, but also including independent numerals (such as 2,3,4) and subranges (such as 1 to 3,2 to 4 etc.).The same principle is applicable to the scope of only narrating a numerical value, such as "less than about 4.5," which should be interpreted as including all above-mentioned values ​​and scopes.In addition, no matter how the breadth of described scope or feature is, this explanation should be applicable.

[0046] Example 1

[0047] This embodiment provides a lightweight permeable material for denitrification and phosphorus removal and a preparation method thereof, comprising:

[0048] 50-70 parts by weight of a cementitious material (cement), 30-47 parts of an enhanced phosphorus removal material, and 0-3 parts of a fiber material are mixed and stirred uniformly to obtain a dry mortar, with a stirring speed of 30-60 r / min and a stirring time of 30-60 s, wherein the enhanced phosphorus removal material comprises the following substances in mass fractions: 15-50% of calcium salt, 5-15% of iron salt, 5-10% of lanthanum salt, 20-70% of kaolin, and 20-70% of diatomaceous earth;

[0049] A plant protein foaming agent diluted 30 to 50 times is prepared into a foam liquid at a gas-liquid ratio of 95% to 100% (the storage time alone shall not exceed 10 minutes). The foam formed under these parameter conditions is not prone to bubble breakage during the preparation process.

[0050] The dry mortar is sprayed in the foam in batches and stirred at a constant speed of 100 to 300 r / min. The number of sprayings is 6 to 13 times. The foam volume required for every 100 grams of dry mortar is 0.4 to 0.6 L to prepare a porous lightweight mortar.

[0051] Porous lightweight mortar can be prepared into modules of different sizes and shapes according to project needs. The porous lightweight mortar is formed in the mold for 2 to 3 days, demolded, and moisturizing cured for 7 days. The moisturizing measures are to cover the moisturizing mold for maintenance and spray water regularly. In the subsequent maintenance, the air humidity is maintained above 70%. The total curing time is 25 to 30 days.

[0052] Finally, a lightweight permeable material for denitrification and phosphorus removal was prepared. The lightweight permeable material contains a large number of irregular three-dimensional pore structures. The batch bonding makes the material skeleton structure have better water permeability, which is conducive to the release of phosphorus removal components inside the material. The permeability coefficient of the prepared permeable material is not less than 3mm / s.

[0053] It should be noted that in order to ensure that the prepared denitrification and dephosphorization lightweight permeable material is easier to shape, has better permeability and higher strength, the mass ratio of each raw material needs to be controlled within an appropriate range.

[0054] Example 2

[0055] This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal. This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal and its preparation method, with reference to Example 1, specifically:

[0056] The mass fraction ratio of the dry-mixed mortar is: 60% cement, 39% enhanced phosphorus removal material, and 1% fiber material; the mass fraction ratio of the enhanced phosphorus removal material is: 25% kaolin, 25% diatomaceous earth, 32% calcium salt, 13% iron salt, and 5% lanthanum salt.

[0057] The preparation method is specifically as follows:

[0058] Cement, kaolin, diatomaceous earth, calcium salt, iron salt, lanthanum salt and fiber material are mixed and stirred evenly to obtain dry mortar at a stirring speed of 50 r / min and a stirring time of 30 to 60 s;

[0059] The plant protein foaming agent was diluted 40 times and foam was prepared at a gas-liquid ratio of 95% with a foam volume of 500 mL.

[0060] Spray 100g of the mixed dry mortar evenly in 500mL of foam in batches, and stir the foam at a constant speed of 250r / min. Spray the dry mortar in 10 times and stir at a constant speed until the mortar is evenly mixed to obtain a porous lightweight mortar. To ensure the pore-forming effect of the lightweight permeable material, the volume of the mixed mortar should be less than 1 / 2 of the foam volume.

[0061] The stirred porous lightweight mortar is poured into a mold of the required size and shape, and then demolded and cured to form a lightweight permeable material for denitrification and dephosphorization. Specifically, the stirred mixed slurry is poured into a mold with a length, width and height of 100mm×100mm×100mm respectively, and formed in the mold for 2 days. For the first 7 days after demolding, it is covered with a moisturizing film for maintenance, sprayed with water every day, and the air humidity is maintained above 70% during the subsequent maintenance. The total maintenance time is 30 days.

[0062] The prepared lightweight porous permeable material contains a large number of irregular three-dimensional pore structures ( Figure 3 ), bonding in batches makes the skeleton structure of the material have better water permeability, which is conducive to the release of phosphorus removal components inside the material, and the water permeability coefficient reaches 15-25mm / s. The water permeability test is as follows Figure 4 shown.

[0063] Example 3

[0064] This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal. This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal and its preparation method, with reference to Example 1, specifically:

[0065] The mass fraction ratio of the dry-mixed mortar is: 70% cement, 30% enhanced phosphorus removal material, and 0% fiber material; the mass fraction ratio of the enhanced phosphorus removal material is: 20% kaolin, 30% diatomaceous earth, 30% calcium salt, 15% iron salt, and 5% lanthanum salt.

[0066] The preparation method is specifically as follows:

[0067] Cement, kaolin, diatomaceous earth, calcium salt, iron salt and lanthanum salt are mixed and stirred evenly to obtain dry mortar at a stirring speed of 50 r / min and a stirring time of 30 to 60 s;

[0068] The plant protein foaming agent was diluted 40 times and foam was prepared at a gas-liquid ratio of 95% with a foam volume of 600 mL.

[0069] Spray 100g of the mixed dry mortar evenly in 600mL of foam in batches, and stir the foam at a constant speed of 100-250r / min. Spray the dry mortar 10 times and stir at a constant speed until the mortar is evenly mixed to obtain a porous lightweight mortar. To ensure the pore-forming effect of the lightweight permeable material, the volume of the mixed mortar should be less than 1 / 2 of the foam volume.

[0070] The porous lightweight mortar obtained after stirring is poured into a mold of the required size and shape, and then demolded and cured to form a lightweight permeable material for denitrification and dephosphorization. Specifically, the mixed slurry after stirring is poured into a mold with a length, width and height of 100mm×100mm×100mm respectively, and formed in the mold for 2 days. For the first 7 days after demolding, it is covered with a moisturizing film for maintenance, sprayed with water every day, and the air humidity is maintained above 70% during the subsequent maintenance. The total maintenance time is 30 days.

[0071] The prepared lightweight porous permeable material contains a large number of irregular three-dimensional pore structures. The batch bonding makes the material skeleton structure have better water permeability, which is conducive to the release of phosphorus removal components inside the material, and the water permeability coefficient reaches 30-50mm / s.

[0072] Example 4

[0073] This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal. This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal and its preparation method, with reference to Example 1, specifically:

[0074] The mass fraction ratio of the dry-mixed mortar is: 59% cement, 40% enhanced phosphorus removal material, and 1% fiber material; the mass fraction ratio of the enhanced phosphorus removal material is: 30% kaolin, 30% diatomaceous earth, 30% calcium salt, 5% iron salt, and 5% lanthanum salt.

[0075] The preparation method is specifically as follows:

[0076] Cement, kaolin, diatomaceous earth, calcium salt, iron salt, lanthanum salt and fiber material are mixed and stirred evenly to obtain dry mortar at a stirring speed of 50 r / min and a stirring time of 30 to 60 s;

[0077] The plant protein foaming agent was diluted 40 times and foam was prepared at a gas-liquid ratio of 95% with a foam volume of 500 mL.

[0078] Spray 100g of the mixed dry mortar evenly in 500mL of foam in batches, and stir the foam at a constant speed of 100-250r / min. Spray the dry mortar 13 times and stir at a constant speed until the mortar is evenly mixed to obtain a porous lightweight mortar. To ensure the pore-forming effect of the lightweight permeable material, the volume of the mixed mortar should be less than 1 / 2 of the foam volume.

[0079] The stirred porous lightweight mortar is poured into a mold of the required size and shape, and then demolded and cured to form a lightweight permeable material for denitrification and dephosphorization. Specifically, the stirred mixed slurry is poured into a mold with a length, width and height of 100mm×100mm×100mm respectively, and formed in the mold for 2 days. For the first 7 days after demolding, it is covered with a moisturizing film for maintenance, sprayed with water every day, and the air humidity is maintained above 70% during the subsequent maintenance. The total maintenance time is 30 days.

[0080] The prepared lightweight porous permeable material contains a large number of irregular three-dimensional pore structures. The batch bonding makes the material skeleton structure have better water permeability, which is conducive to the release of phosphorus removal components inside the material, and the water permeability coefficient reaches 10 to 20 mm / s.

[0081] Example 5

[0082] This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal. This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal and its preparation method, with reference to Example 1, specifically:

[0083] The mass fraction ratio of the dry-mixed mortar is: 60% cement, 39% enhanced phosphorus removal material, and 1% fiber material; the mass fraction ratio of the enhanced phosphorus removal material is: 25% kaolin, 25% diatomaceous earth, 32% calcium salt, 13% iron salt, and 5% lanthanum salt.

[0084] The preparation method is specifically as follows:

[0085] Cement, kaolin, diatomaceous earth, calcium salt, iron salt, lanthanum salt and fiber material are mixed and stirred evenly to obtain dry mortar at a stirring speed of 50 r / min and a stirring time of 30 to 60 s;

[0086] The plant protein foaming agent was diluted 30 times and foam was prepared at a gas-liquid ratio of 95% with a foam volume of 500 mL.

[0087] Spray 100g of the mixed dry mortar evenly in 500mL of foam in batches, and stir the foam at a constant speed of 250r / min. Spray the dry mortar in 10 times and stir at a constant speed until the mortar is evenly mixed to obtain a porous lightweight mortar. To ensure the pore-forming effect of the lightweight permeable material, the volume of the mixed mortar should be less than 1 / 2 of the foam volume.

[0088] The stirred porous lightweight mortar is poured into a mold of the required size and shape, and then demolded and cured to form a lightweight permeable material for denitrification and dephosphorization. Specifically, the stirred mixed slurry is poured into a mold with a length, width and height of 100mm×100mm×100mm respectively, and formed in the mold for 2 days. For the first 7 days after demolding, it is covered with a moisturizing film for maintenance, sprayed with water every day, and the air humidity is maintained above 70% during the subsequent maintenance. The total maintenance time is 30 days.

[0089] The prepared lightweight porous permeable material contains a large number of irregular three-dimensional pore structures. The batch bonding makes the material skeleton structure have better water permeability, which is conducive to the release of phosphorus removal components inside the material, and the water permeability coefficient reaches 20 to 30 mm / s.

[0090] Example 6

[0091] This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal. This embodiment provides a method for testing the water permeability of a lightweight water-permeable material for denitrification and phosphorus removal and its preparation method, with reference to Example 1, specifically:

[0092] The mass fraction ratio of the dry-mixed mortar is: 59% cement, 40% enhanced phosphorus removal material, and 1% fiber material; the mass fraction ratio of the enhanced phosphorus removal material is: 30% kaolin, 30% diatomaceous earth, 30% calcium salt, 5% iron salt, and 5% lanthanum salt.

[0093] The preparation method is specifically as follows:

[0094] Cement, kaolin, diatomaceous earth, calcium salt, iron salt, lanthanum salt and fiber material are mixed and stirred evenly to obtain dry mortar at a stirring speed of 50 r / min and a stirring time of 30 to 60 s;

[0095] The plant protein foaming agent was diluted 40 times and foam was prepared at a gas-liquid ratio of 95% with a foam volume of 500 mL.

[0096] Spray 100g of the mixed dry mortar evenly in 500mL of foam in batches, and stir the foam at a constant speed of 100-250r / min. Spray the dry mortar in 7 times and stir at a constant speed until the mortar is evenly mixed to obtain a porous lightweight mortar. To ensure the pore-forming effect of the lightweight permeable material, the volume of the mixed mortar should be less than 1 / 2 of the foam volume.

[0097] The stirred porous lightweight mortar is poured into a mold of the required size and shape, and then demolded and cured to form a lightweight permeable material for denitrification and dephosphorization. Specifically, the stirred mixed slurry is poured into a mold with a length, width and height of 100mm×100mm×100mm respectively, and formed in the mold for 2 days. For the first 7 days after demolding, it is covered with a moisturizing film for maintenance, sprayed with water every day, and the air humidity is maintained above 70% during the subsequent maintenance. The total maintenance time is 30 days.

[0098] The prepared lightweight porous permeable material contains a large number of irregular three-dimensional pore structures. The batch bonding makes the material skeleton structure have better water permeability, which is conducive to the release of phosphorus removal components inside the material, and the water permeability coefficient reaches 30-45mm / s.

[0099] Example 7

[0100] This embodiment provides the application of lightweight porous water-permeable materials in water purification processes, including:

[0101] The lightweight porous permeable material test block with a size of 100mm×100mm×100mm obtained in Example 1 was used in the packing layer of the artificial wetland. The nutrient solution was introduced according to the volume ratio of the mixed nutrient solution and the heterotrophic denitrifying bacteria solution of 10:1. After two days, the water body to be purified was slowly introduced. The water sample of the packing layer was taken every day. It was determined that the lightweight permeable material for denitrification and phosphorus removal of this embodiment had a significant effect on the removal of nitrogen and phosphorus in the water body during the in-situ purification process of the artificial wetland, wherein the total nitrogen concentration was degraded from the initial 12mg / L to 1.1mg / L on the 30th day (degradation curve as shown in FIG. Figure 1 The total phosphorus concentration was degraded from the initial 10.5 mg / L to 0.05 mg / L on the 30th day (the degradation curve is shown in Figure 2 As shown), the lightweight porous permeable material is easy to load and replace. Since the replaced material uses cement-based materials, it can be directly used in landscaping and other projects, which is convenient for the promotion and application of the project.

[0102] Comparative Example 1

[0103] This example provides the effects of different dry mortar material and prefabricated foam ratios on water permeability and lightweight properties, with reference to Example 2, specifically:

[0104] The mass fraction ratio of the dry-mixed mortar is: 60% cement, 39% enhanced phosphorus removal material, and 1% fiber material; the mass fraction ratio of the enhanced phosphorus removal material is: 25% kaolin, 25% diatomaceous earth, 32% calcium salt, 13% iron salt, and 5% lanthanum salt.

[0105] The preparation method is:

[0106] Cement, kaolin, diatomaceous earth, calcium salt, iron salt, lanthanum salt and fiber material are mixed and stirred evenly to obtain dry mortar at a stirring speed of 50 r / min and a stirring time of 30 to 60 s;

[0107] Dilute the plant protein foaming agent 40 times and prepare foam at a gas-liquid ratio of 95%, with a foam volume of 300 mL; spray 100 g of the mixed dry mortar evenly in 300 mL of foam in batches, and stir the foam at a stirring speed of 250 r / min. Spray the dry mortar 10 times and stir at a constant speed until the last mortar is evenly mixed to form a porous lightweight mortar. To ensure the pore-forming effect of the lightweight permeable material, the volume of the mixed mortar should be less than 1 / 2 of the foam volume;

[0108] The stirred porous lightweight mortar is poured into a module of the required size and shape, and then demolded and cured according to the method in Example 2. The prepared material is water-impermeable and does not have the characteristics of being porous and lightweight.

[0109] The above results show that the ratio of dry-mix mortar material to prefabricated foam is the key factor affecting the permeability of lightweight porous permeable materials, that is, the ratio of dry-mix mortar to prefabricated foam. The optimal ratio is 400-600 mL of prefabricated foam per 100 g of dry-mix mortar. A larger ratio will lead to worse permeability of the material until it loses its permeability and lightweight properties. A too small ratio will greatly reduce the strength of the material and cause the material to break. Therefore, it is necessary to strictly control the ratio of the two in lightweight porous permeable materials.

[0110] Comparative Example 2

[0111] This example provides the effects of different dry-mix mortar batches on water permeability and lightweight properties, with reference to Example 2, specifically:

[0112] Under the same material ratio conditions as in Example 2, if the batch of dry mortar added to the prefabricated foam is changed to 15 times or more, the prepared lightweight porous permeable material will have poor permeability or even be impermeable and will not have the characteristics of being lightweight and porous.

[0113] Comparative Example 3

[0114] This example provides the effects of moisturizing and curing on water permeability and lightweight properties, referring to Example 2, specifically:

[0115] During the preparation process of Example 2, no moisture retention measures were taken after demoulding and curing, and water was not sprayed regularly. 30 days after the permeable material was formed, the material began to fall off and break. After being placed in a water body for flushing, the permeable material easily clumped and fell off.

[0116] Comparative Example 4

[0117] This embodiment provides the application of lightweight porous water-permeable materials and cement blocks prepared by ordinary mixing of the same material ratio in the water purification process. Specifically:

[0118] The lightweight porous water-permeable material test block with a size of 100mm×100mm×100mm obtained in Example 1 and the test block with a size of 100mm×100mm×100mm formed by ordinary stirring with the same material ratio in Example 1 were placed in 4L of simulated wastewater containing phosphorus. The simulated wastewater was measured regularly. It was found that the lightweight porous water-permeable material test block had a higher removal rate and faster removal effect on phosphorus than the ordinary test block. The total phosphorus degradation curve of the lightweight porous water-permeable material test block is shown as follows: Figure 5 As shown, the total phosphorus degradation curve of the ordinary test block is as follows Figure 6 shown.

Claims

1. A lightweight, water-permeable material for denitrification and dephosphorization, characterized in that: The lightweight water-permeable material comprises a lightweight slow-release skeleton structure and water-permeable micropores; the water-permeable micropores are distributed inside the lightweight slow-release skeleton structure, and the lightweight slow-release skeleton structure contains an open-pore structure inside, which has a water-permeable function; the lightweight slow-release skeleton structure is prepared by mixing a dry mortar made of cement, a reinforced phosphorus removal material, and a reinforcing material with prefabricated foam in batches to form a porous lightweight mortar, which is then formed; The mass percentages of cement, enhanced phosphorus removal material, and reinforcing material in the dry-mix mortar are 50% to 70% cement, 30% to 47% enhanced phosphorus removal material, and 0% to 3% reinforcing material, respectively; the enhanced phosphorus removal material is composed of the following substances by mass: 15% to 50% calcium salt, 5% to 15% iron salt, 5% to 10% lanthanum salt, 10% to 60% kaolin, and 10% to 60% diatomaceous earth; the reinforcing material includes inorganic fiber and / or synthetic fiber; The preparation method of the lightweight water-permeable material for denitrification and phosphorus removal comprises: The cement, the enhanced phosphorus removal material and the reinforcing material are fully stirred and mixed to obtain a uniformly mixed dry mortar; The foaming agent is diluted 30 to 50 times and foam is prepared under the condition of a gas-liquid ratio of 95% to 100%; The porous lightweight mortar is prepared by mixing dry mortar and foam in batches; the dry mortar is evenly sprayed in batches for 6 to 13 times; the ratio of the dry mortar to foam is such that the foam volume required for every 100 grams of dry mortar is 0.4 to 0.6 L; The porous lightweight mortar is prepared into a lightweight and permeable material through a molding module; The step of preparing the porous lightweight mortar by mixing the dry-mixed mortar and the foam in batches comprises: uniformly spraying the dry-mixed mortar in batches into the prefabricated foam, and uniformly stirring at a speed of 100 to 300 r / min until the mortar and the foam are fully fused to obtain the porous lightweight mortar; The molding module includes preparing porous lightweight mortar into modules of different sizes and shapes according to different engineering needs, and a certain period of maintenance is required during the molding period; the maintenance method is to carry out an initial setting period of 2 to 3 days after the porous lightweight mortar enters the mold, and after demolding, moisturizing maintenance is carried out.

2. The lightweight water-permeable material for denitrification and dephosphorization according to claim 1, characterized in that: The cement, enhanced phosphorus removal material and reinforcing material are fully stirred and mixed at a stirring speed of 30 to 100 r / min and a stirring time of 30 to 60 s to obtain a uniformly mixed dry powder mortar.

3. The lightweight water-permeable material for denitrification and dephosphorization according to claim 2, characterized in that: The foaming agent includes a plant protein foaming agent or a synthetic protein foaming agent.

4. The lightweight water-permeable material for denitrification and dephosphorization according to claim 3, characterized in that: The moisturizing maintenance includes covering with a moisturizing film and spraying with clean water regularly, and maintaining the air humidity above 70% during subsequent maintenance. The total maintenance time is 25 to 30 days.

5. Use of a lightweight permeable material for denitrification and dephosphorization according to any one of claims 1 to 4 in a water purification process.

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