Yunnan red soil-based composite porous ceramsite, and preparation method and application thereof

Abstract

The application provides a Yunnan red soil-based composite porous ceramsite and a preparation method and application thereof, and the preparation method of the Yunnan red soil-based composite porous ceramsite comprises the following steps: mixing Yunnan red soil particles, sepiolite powder and biomass powder to obtain a mixture; granulating the obtained mixture into balls after stirring the mixture uniformly with water to obtain green balls; and drying and calcining the obtained green balls at high temperature to obtain the composite porous ceramsite. The Yunnan red soil, sepiolite and biomass are mixed and granulated, and then calcined into the ceramsite, the ceramsite has the advantages of a large specific surface area, a high porosity, good adhesion of microorganisms on the surface and a high bacterial abundance, and can achieve a good denitrification effect; and the high-calcium minerals contained in the ceramsite are beneficial to combination with phosphorus to generate precipitates with a smaller solubility product, and the ceramsite also has a good phosphorus removal effect; therefore, when the composite porous ceramsite is used for sewage treatment, not only is the treatment effect good and the purification efficiency high, but also the wastewater can be discharged up to the standard, and the composite porous ceramsite has high practicability.

Description

A Yunnan red clay-based composite porous ceramsite, its preparation method and application Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and particularly relates to a Yunnan red clay-based composite porous ceramsite, its preparation method, and its application. Background Technology

[0002] Nitrogen and phosphorus are crucial indicators for evaluating the reuse of urban domestic wastewater. Efficiently and stably purifying nitrogen and phosphorus from urban domestic wastewater to achieve reuse standards is a highly challenging problem. However, the low concentration of pollutants in the effluent from urban wastewater treatment plants is insufficient to sustain microbial growth, leading to a predicament in biological nitrogen and phosphorus removal technology. With the continuous increase in urban domestic water consumption, the use of chemical agents is not only costly but also inefficient in nitrogen and phosphorus removal.

[0003] Currently, the main methods for nitrogen and phosphorus removal from wastewater include biological methods, coagulation sedimentation, ion exchange, electrodialysis, and air flotation. However, these methods are costly to operate, cumbersome, and prone to secondary pollution, and are difficult to remove trace amounts of nitrogen and phosphorus from wastewater. Aerated biological filters are a type of biofilm process, mainly composed of filter media, a water distribution system, an aeration system, a drainage system, and a backwashing system. This treatment system has a small footprint and high efficiency, making it the most preferred process for nitrogen and phosphorus removal. Its core technology utilizes a biofilm formed on the surface of the filter media, containing different dominant species (mostly nitrifying and denitrifying bacteria), to remove ammonia and nitrate nitrogen from the water, followed by physical adsorption and chemical precipitation to remove phosphates. Here, the filter media, as the core component of the aerated biological filter, has a rough surface and porous structure that facilitates microbial attachment, thus efficiently removing pollutants. Therefore, the quality of the filter media is crucial to the success of the biological filter; furthermore, the investment in filter media is relatively high, and finding cost-effective and high-quality fillers has been a topic of research for many scholars.

[0004] Ceramsite, as a novel filter media, boasts a large specific surface area, high porosity, and large pore size. This allows for increased volumetric loading in aerated biological filters and a significantly improved degradation rate. Furthermore, this product is lightweight, high-strength, abrasion-resistant, washout-resistant, and does not release toxic or harmful substances into the water. It possesses excellent physical, chemical, and hydraulic properties, making it suitable for various wastewater purification requirements. Modern water treatment processes fully utilize these characteristics, making it the preferred filter media for water treatment, particularly wastewater and water supply filtration technologies.

[0005] The main mineral components of Yunnan red clay are hydrous calcium aluminum silicate minerals such as quartz and zeolite, with a porosity generally greater than 1 and a viscosity as high as 3.00 g / cm³. 3The above-mentioned materials generally exhibit cohesion between 13-60 kPa, possess excellent shear strength, and are suitable for use as artificial ceramsite filter media in water treatment. Sepiolite, on the other hand, is a magnesium-rich fibrous silicate clay mineral, widely distributed, inexpensive, and readily available, with a large specific surface area (≈300 m²). 2 Yunnan red clay and sepiolite ( / g) possess excellent adsorption, rheological, and catalytic properties. Furthermore, their natural nanoporous structure enables them to adsorb both polar and low-polar substances, making them suitable for use as artificial ceramsite filter media in water treatment. Therefore, using Yunnan red clay and sepiolite to prepare ceramsite and applying it as filter media in aerated biological filters for wastewater treatment holds great potential. Summary of the Invention

[0006] To address the aforementioned technical issues, this invention provides a Yunnan red clay-based composite porous ceramsite, its preparation method, and its application. The ceramsite is prepared by mixing and granulating Yunnan red clay, sepiolite, and biomass, followed by calcination. This ceramsite possesses advantages such as a large specific surface area, high porosity, good surface microbial adhesion, and high bacterial abundance, resulting in excellent denitrification. Furthermore, its high-calcium mineral content facilitates phosphorus binding, forming precipitates with smaller solubility products, thus also effectively removing phosphorus. Therefore, when the composite porous ceramsite is used for wastewater treatment, it not only achieves good treatment results and high purification efficiency but also ensures that wastewater meets discharge standards, demonstrating strong practicality.

[0007] The present invention proposes a method for preparing Yunnan red clay-based composite porous ceramsite, comprising the following steps:

[0008] S1. Mix Yunnan red clay particles, sepiolite powder and biomass powder to obtain a mixture;

[0009] S2. After mixing the mixture obtained in step S1 with water and stirring evenly, granulate it into balls to obtain raw material balls;

[0010] S3. After drying the raw material balls obtained in step S2, calcine them at high temperature to obtain the composite porous ceramic particles.

[0011] Preferably, the Yunnan red soil particles are particles made from crushed red soil from Honghe Hani and Yi Autonomous Prefecture, with a particle size of 0.1-10 mm, preferably 1-2 mm; the sepiolite powder is natural sepiolite mineral powder, with a powder particle size of 0.1-1 mm, preferably 0.3-0.85 mm; and the biomass powder is powder made from crushed tree bark or leaves, with a powder particle size not greater than 0.1 mm.

[0012] Preferably, the mass ratio of the Yunnan red clay particles, sepiolite powder, and biomass powder is 10:2-3:1-3.

[0013] Preferably, the raw material balls have a particle size of 1-10 mm, and more preferably 4.5-7.5 mm.

[0014] Preferably, the drying temperature is 90-120℃, and the product is dried to a constant weight.

[0015] Preferably, the calcination temperature is 600-800℃ and the time is 2-4 hours;

[0016] Preferably, the calcination is carried out in air or oxygen.

[0017] Preferably, the method further includes step S4: adding the composite porous ceramsite obtained in step S3 into an organic acid, soaking it at 50-80°C for 3-6 hours, taking it out, adding it into an aqueous solution containing plant fiber and shaking and mixing for 0.1-0.3 hours, taking it out and drying it to obtain biocompatible composite porous ceramsite.

[0018] In this invention, organic acids are used to acidify and activate the composite porous ceramic particles, thereby incorporating carboxylic acid groups into the composite porous ceramic particles. After mixing with an aqueous solution containing plant fibers, hydrogen bonds can be formed between the plant fibers and the composite porous ceramic particles with carboxylic acid groups. This results in a stable and long-lasting hydrophilic and biophilic coating layer on the surface of the composite porous ceramic particles, which not only effectively improves the biofilm formation rate and amount on the surface of the ceramic particles, but also improves its nitrogen and phosphorus removal efficiency.

[0019] Preferably, the organic acid is at least one of malic acid, oxalic acid, lactic acid or tartaric acid, and the plant fiber is at least one of jute fiber, flax fiber, ramie fiber, sisal fiber or bamboo fiber.

[0020] The present invention also proposes a Yunnan red clay-based composite porous ceramsite prepared by the above preparation method.

[0021] This invention also proposes an application of the above-mentioned Yunnan red clay-based composite porous ceramsite in wastewater treatment.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention uses natural Yunnan red clay minerals, natural sepiolite minerals and biomass mixed for granulation and calcination. Natural Yunnan red clay minerals will enhance the crystallinity of crystals and improve the compressive strength of materials when calcined at high temperature. Sepiolite will decompose at high temperature to generate CO2 and CaO, which can not only act as a binder, but also form hydrated calcium silicate with silicon oxides at high temperature to promote the calcination of mineral powders. After calcination, biomass will increase the porosity of materials, which is conducive to the attachment of microorganisms and physical interception. Finally, the above three raw materials are granulated and then calcined with oxygen. After high temperature calcination, the adsorbed water, crystal water and structural water of the raw materials will also be decomposed and vaporized at high temperature, and finally trapped in the liquid phase to form nanostructured spherical metal porous composite ceramic particles with porous structure characteristics.

[0024] (2) The composite porous ceramic particles obtained by this invention have a diameter of approximately 4.5-7.5 mm and a compressive strength of 1.7 MPa. Their interior is mainly composed of clustered expanded particles with nano- to submicron crystal sizes and interwoven fibrous rods, exhibiting a nano- to micron-sized porous structure. They are rough and porous with a large specific surface area (reaching 56.69 × 10⁻⁶). 4 cm 2 When used as filter media in aerated biological filters (above g), the scouring effect of air and water on the biofilm on the surface of the ceramsite is enhanced during rinsing in a fluidized state. The surface biofilm is not easy to detach, which can promote the shedding of old biofilm and maintain the thickness of new biofilm, thus enhancing biological activity. Therefore, it can effectively remove nitrogen and phosphorus elements from water. Through simulation of urban domestic sewage, it was found that it has a good removal efficiency for low concentrations of nitrogen and phosphorus.

[0025] (3) The raw materials of this invention are non-toxic and harmless, with no secondary pollution. The resulting ceramsite has high purification efficiency, the method is simple and easy to operate, requires few types of materials, and is inexpensive. It is an environmentally friendly functional material. This invention ultimately provides a method for preparing porous ceramsite that is convenient to produce, inexpensive, and has high specific surface area, high porosity, and high compressive strength. Attached Figure Description

[0026] Figure 1 shows the XRD patterns of Yunnan red clay-based composite porous ceramsite obtained in Example 1 of the present invention and calcined Yunnan red clay and sepiolite; where a corresponds to the XRD curve of calcined Yunnan red clay, b corresponds to the XRD curve of calcined sepiolite, and c corresponds to the XRD curve of Yunnan red clay-based composite porous ceramsite obtained in Example 1.

[0027] Figure 2 is a SEM image of the Yunnan red clay after calcination according to the present invention; wherein, Figures 2a-d correspond to different scales;

[0028] Figure 3 is a SEM image of the calcined sepiolite of the present invention; wherein, Figures 3a-d correspond to different scales;

[0029] Figure 4 is a SEM image of the Yunnan red clay-based composite porous ceramsite obtained in Example 1 of the present invention; wherein, Figures 4a-d correspond to different scales;

[0030] Figure 5 shows the XRD patterns of Yunnan red clay-based composite porous ceramsite obtained in Comparative Example 1 of the present invention, as well as Yunnan red clay and sepiolite; where a corresponds to the XRD curve of Yunnan red clay, b corresponds to the XRD curve of sepiolite, and c corresponds to the XRD curve of Yunnan red clay-based composite porous ceramsite obtained in Comparative Example 1.

[0031] Figure 6 is a SEM image of the Yunnan red soil of the present invention; wherein, Figures 6a-d correspond to different scales;

[0032] Figure 7 is a SEM image of the sepiolite of the present invention; wherein, Figures 7a-d correspond to different scales;

[0033] Figure 8 is a schematic diagram of the operation of the Yunnan red clay-based composite porous ceramsite obtained in this invention in an aerated biological filter. Detailed Implementation

[0034] The present invention will now be described in detail through specific embodiments. However, these embodiments are clearly provided for illustrative purposes and are not intended to limit the scope of the present invention.

[0035] Example 1

[0036] This embodiment presents a Yunnan red clay-based composite porous ceramsite, which is prepared by the following method:

[0037] (1) After crushing natural Yunnan red clay minerals (from Honghe Hani and Yi Autonomous Prefecture, whose main chemical components are SiO2 and hydrated calcium aluminum silicate) to obtain fine particles with a particle size of 1-2 mm; after crushing bark and leaves into powder using a small crusher and passing them through a 200-mesh sieve to obtain biomass powder; after crushing natural sepiolite minerals (whose main chemical components are magnesium-rich fibrous silicate) into powder to obtain sepiolite powder with a particle size of 0.3-0.85 mm;

[0038] (2) Add the above Yunnan red clay particles, sepiolite powder and biomass powder to a mixer at a mass ratio of 10:3:1 and mix evenly; then add water to the resulting mixture and stir evenly, and put it into a small granulator to granulate into irregular spheres with a particle size of 4.5-7.5mm; then place the spheres in an oven at 105℃ and dry them until they are at constant weight and light yellow-brown in color, and then put them into a muffle furnace and calcine them at 700℃ for 3 hours, and then cool them naturally to room temperature to obtain the target product - Yunnan red clay-based composite porous ceramsite.

[0039] Yunnan laterite and sepiolite were placed in a muffle furnace and calcined at 700℃ for 3 hours to obtain calcined Yunnan laterite and sepiolite. X-ray diffraction tests were performed on the Yunnan laterite-based composite porous ceramsite obtained in Example 1 and the calcined Yunnan laterite and sepiolite, resulting in Figure 1. Figure 1 shows the XRD patterns of the Yunnan laterite-based composite porous ceramsite obtained in Example 1 and the calcined Yunnan laterite and sepiolite, where a corresponds to the XRD curve of the calcined Yunnan laterite, b corresponds to the XRD curve of the calcined sepiolite, and c corresponds to the XRD curve of the Yunnan laterite-based composite porous ceramsite obtained in Example 1. As can be seen from curve a, the characteristic diffraction peaks of Yunnan laterite (main chemical component SiO2) after high-temperature calcination, such as 2θ = 20.9°, 26.6°, and 50.1° (JCPDS No. 46-1045), are significantly enhanced. This is due to the fact that the characteristic diffraction peaks of Yunnan laterite (main chemical component CaAl2Si4O2) after high-temperature calcination are significantly enhanced. 12The characteristic diffraction peaks of dolomite (2θ = 21.3°, JCPDS No. 26-1047) and calcium silicate (2θ = 26.7°) gradually disappear. Curve b shows that after high-temperature calcination, dolomite gradually decomposes into a mixture of carbon dioxide, calcium oxide, and magnesium oxide. Curve c shows that the characteristic diffraction peak of calcium silicate (2θ = 29.4°, JCPDS No. 29-0380) was also observed at the diffraction angle. It is the main form of calcium silicate hydrate (CSH) and acts as a solid binder.

[0040] Figure 2 shows the SEM image of the calcined Yunnan red clay of the present invention; where Figures 2a-d correspond to different scales. Referring to Figure 2, it can be seen that due to the high surface temperature, the crystal water and adsorbed water of the calcined Yunnan red clay vaporize, causing the particle surface to expand and increasing the specific surface area. Figure 3 shows the SEM image of the calcined sepiolite of the present invention. Referring to Figure 3, it can be seen that the rod-shaped fibrous structure of the calcined sepiolite is partially destroyed, and the overall structure presents a fibrous structure with alternating polyhedral pore walls and channels. Figure 4 shows the SEM image of the Yunnan red clay-based composite porous ceramsite obtained in Example 1 of the present invention; referring to Figure 4, it can be seen that the interior of the Yunnan red clay-based composite porous ceramsite consists of fibrous rod-shaped sepiolite particles and irregularly shaped particles connected together. Under high-temperature molten conditions, a porous and irregular overall structure is formed, which facilitates the attachment, fixation, and biofilm formation of microorganisms.

[0041] Example 2

[0042] This embodiment presents a Yunnan red clay-based composite porous ceramsite, which is prepared by the following method:

[0043] (1) After crushing natural Yunnan red clay minerals (from Honghe Hani and Yi Autonomous Prefecture, whose main chemical components are SiO2 and hydrated calcium aluminum silicate) to obtain fine particles with a particle size of 1-2 mm; after crushing bark and leaves into powder using a small crusher and passing them through a 200-mesh sieve to obtain biomass powder; after crushing natural sepiolite minerals (whose main chemical components are magnesium-rich fibrous silicate) into powder to obtain sepiolite powder with a particle size of 0.3-0.85 mm;

[0044] (2) Add the above Yunnan red clay particles, sepiolite powder and biomass powder to a mixer at a mass ratio of 10:2:3 and mix evenly; then add water to the mixture and stir evenly, and put it into a small granulator to granulate into irregular spheres with a particle size of 4.5-7.5mm; then put the spheres into an oven at 120℃ and dry them until they are at constant weight and light yellow-brown in color, and then put them into a muffle furnace and calcine them at 600℃ for 4 hours, and then cool them naturally to room temperature to obtain the target product - Yunnan red clay-based composite porous ceramsite.

[0045] Example 3

[0046] This embodiment presents a Yunnan red clay-based composite porous ceramsite, which is prepared by the following method:

[0047] (1) After crushing natural Yunnan red clay minerals (from Honghe Hani and Yi Autonomous Prefecture, whose main chemical components are SiO2 and hydrated calcium aluminum silicate) to obtain fine particles with a particle size of 1-2 mm; after crushing bark and leaves into powder using a small crusher and passing them through a 200-mesh sieve to obtain biomass powder; after crushing natural sepiolite minerals (whose main chemical components are magnesium-rich fibrous silicate) into powder to obtain sepiolite powder with a particle size of 0.3-0.85 mm;

[0048] (2) Add the above Yunnan red clay particles, sepiolite powder and biomass powder to a mixer at a mass ratio of 10:3:1 and mix evenly; then add water to the mixture and stir evenly, and put it into a small granulator to granulate into irregular spheres with a particle size of 4.5-7.5mm; then place the spheres in a 90℃ oven to dry until they are at constant weight and light yellow-brown in color, and then put them into a muffle furnace and calcine them at 800℃ for 2 hours, and then cool them naturally to room temperature to obtain the target product—Yunnan red clay-based composite porous ceramsite.

[0049] Example 4

[0050] This embodiment presents a Yunnan red clay-based composite porous ceramsite, which is prepared by the following method:

[0051] (1) After crushing natural Yunnan red clay minerals (from Honghe Hani and Yi Autonomous Prefecture, whose main chemical components are SiO2 and hydrated calcium aluminum silicate) to obtain fine particles with a particle size of 1-2 mm; after crushing bark and leaves into powder using a small crusher and passing them through a 200-mesh sieve to obtain biomass powder; after crushing natural sepiolite minerals (whose main chemical components are magnesium-rich fibrous silicate) into powder to obtain sepiolite powder with a particle size of 0.3-0.85 mm;

[0052] (2) Add the above Yunnan red clay particles, sepiolite powder and biomass powder to a mixer at a mass ratio of 10:3:1 and mix evenly; then add water to the mixture and stir evenly, and put it into a small granulator to granulate into irregular spheres with a particle size of 4.5-7.5mm; then put the spheres into an oven at 105℃ and dry them until they are at constant weight and light yellow-brown in color; then put them into a muffle furnace and calcine them at 700℃ for 3 hours, and let them cool naturally to room temperature to obtain Yunnan red clay-based composite porous ceramsite.

[0053] (3) Add the above-mentioned Yunnan red clay-based composite porous ceramsite to lactic acid, soak it at 60°C for 4 hours, filter it out, add it to an aqueous solution containing 6wt% jute fiber powder, place it in a vortex shaker and shake for 15 minutes, filter it out, dry it, and you will get biocompatible Yunnan red clay-based composite porous ceramsite.

[0054] Comparative Example 1

[0055] This embodiment presents a Yunnan red clay-based composite porous ceramsite, which is prepared by the following method:

[0056] (1) After crushing natural Yunnan red clay minerals (from Honghe Hani and Yi Autonomous Prefecture, whose main chemical components are SiO2 and hydrated calcium aluminum silicate) to obtain fine particles with a particle size of 1-2 mm; after crushing bark and leaves into powder using a small crusher and passing them through a 200-mesh sieve to obtain biomass powder; after crushing natural sepiolite minerals (whose main chemical components are magnesium-rich fibrous silicate) into powder to obtain sepiolite powder with a particle size of 0.3-0.85 mm;

[0057] (2) Add the above Yunnan red clay particles, sepiolite powder and biomass powder to a mixer at a mass ratio of 10:3:1 and mix evenly; then add water to the mixture and stir evenly, and put it into a small granulator to granulate into irregular spheres with a particle size of 4.5-7.5mm; then place the spheres in a 105℃ oven and dry them until they are at constant weight and the color is light yellowish brown, thus obtaining the target product - Yunnan red clay-based composite porous ceramsite.

[0058] Figure 5 shows the XRD patterns of the Yunnan laterite-based composite porous ceramsite obtained in Comparative Example 1 of this invention, as well as Yunnan laterite and sepiolite; where a corresponds to the XRD curve of Yunnan laterite, b corresponds to the XRD curve of sepiolite, and c corresponds to the XRD curve of the Yunnan laterite-based composite porous ceramsite obtained in Comparative Example 1. As can be seen from curve a, the main mineral component of Yunnan laterite is quartz, and there are also a considerable amount of metallic silicates; as can be seen from curve b, the main mineral component of sepiolite is dolomite; as can be seen from curve c, without calcination, the characteristic peaks of quartz and dolomite in the ceramsite obtained by combining Yunnan laterite and sepiolite, i.e., the Yunnan laterite-based composite porous ceramsite obtained in Comparative Example 1, are obvious, and the crystallinity is good.

[0059] Figure 6 shows the SEM image of the Yunnan red clay of this invention; where Figures 6a-d correspond to different scales. Referring to Figure 6, it can be seen that the natural Yunnan red clay minerals have nano-sized clustered particles, which are interconnected and irregularly arranged. Figure 7 shows the SEM image of the sepiolite of this invention. Referring to Figure 7, it can be seen that the natural sepiolite mineral is composed of numerous intersecting fibrous rods, and contains a small amount of aggregates and nanoporous structures.

[0060] Comparative Example 2

[0061] This embodiment presents a type of ceramsite, which is prepared by the following method:

[0062] (1) The bark and leaves are crushed into powder using a small crusher and then passed through a 200-mesh sieve to obtain biomass powder; natural sepiolite mineral (the main chemical component is magnesium-rich fibrous silicate) is crushed into powder to obtain sepiolite powder with a particle size of 0.3-0.85mm.

[0063] (2) Add the above sepiolite powder and biomass powder to a mixer at a mass ratio of 13:1 and mix evenly; then add water to the resulting mixture and stir evenly, and put it into a small pellet mill to granulate into irregular spheres with a particle size of 4.5-7.5mm; then place the spheres in a 105℃ oven to dry until they are at constant weight, and then put them into a muffle furnace and calcine them at 700℃ for 3 hours, and then let them cool naturally to room temperature to obtain the target product - ceramsite.

[0064] Test case

[0065] By preparing solutions of COD, total phosphorus, ammonia nitrogen, and total nitrogen at certain concentrations to simulate urban domestic wastewater, the nitrogen and phosphorus removal performance of the aforementioned Yunnan red clay-based composite porous ceramsite in water treatment was tested. Specifically, the inner diameter of the aerated biological filter column was 30 cm, and the packing height was 100 cm. The Yunnan red clay-based composite porous ceramsite obtained in Example 1 was used as packing material and loaded into it (21.51 kg). Simulated influent (COD: 80 mg / L, ammonia nitrogen: 10 mg / L, total nitrogen: 10 mg / L, phosphorus: 0.5 mg / L) was placed in the influent tank. The influent method adopted was an upflow method, that is, water was pumped into the inlet at the lower end of the filter column by a peristaltic pump, flowed through the packing material, and then flowed out from the outlet at the upper end of the filter column. The hydraulic residence time was changed by controlling the speed of the peristaltic pump, and the aeration rate was changed by controlling the air count value. Samples were taken every 24 hours to determine the COD, nitrogen, and phosphorus contents.

[0066] The same mass of porous ceramsite described in Example 4 and Comparative Examples 1-2 was packed into filter columns of the same size and operated with the same process parameters. Influent and effluent data were recorded. The prepared domestic wastewater was then fed into the aerated biological filter in the same manner, with only support stones added to the filter column. Influent and effluent data were recorded, and this was designated as a blank example. Specific test results are shown in Tables 1-4 below:

[0067] Table 1. Comparison of COD removal effects of expanded clay particles obtained in the examples and comparative examples.

[0068]

[0069] Table 2. Comparison of total phosphorus removal effects of ceramic particles obtained in the examples and comparative examples.

[0070]

[0071] Table 3. Comparison of ammonia nitrogen removal effects of the expanded clay particles obtained in the examples and comparative examples.

[0072]

[0073] Table 4. Comparison of total nitrogen removal efficiency of ceramsite obtained in the examples and comparative examples.

[0074]

[0075] As can be seen from the results in Tables 1-4 above, the Yunnan red clay-based composite porous ceramsite obtained by the embodiments of the present invention can meet the Class A standard of GB18918-2002 for the removal of COD, ammonia nitrogen, total nitrogen and phosphorus. It also has a high removal rate (90%) for low concentration phosphorus (0.5 mg / L), which is of great significance for deep phosphorus removal from sewage and for sewage reuse.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing Yunnan red clay-based composite porous ceramsite, characterized in that, The process includes the following steps: S1, mixing Yunnan red clay particles, sepiolite powder, and biomass powder to obtain a mixture; S2, adding water to the mixture obtained in step S1, stirring evenly, and then granulating into balls to obtain raw material balls; S3, drying the raw material balls obtained in step S2 and then calcining them at high temperature to obtain the composite porous ceramsite; and further includes step S4, adding the composite porous ceramsite obtained in step S3 to organic acid, soaking it at 50-80℃ for 3-6 hours, taking it out, adding it to an aqueous solution containing plant fiber, shaking and mixing for 0.1-0.3 hours, taking it out, and then drying it to obtain biocompatible composite porous ceramsite.

2. The preparation method of Yunnan red clay-based composite porous ceramsite according to claim 1, characterized in that, The Yunnan red soil particles are particles made from crushed red soil from Honghe Hani and Yi Autonomous Prefecture, with a particle size of 0.1-10mm; the sepiolite powder is natural sepiolite mineral powder with a powder particle size of 0.1-1mm; the biomass powder is powder made from crushed tree bark or leaves, with a powder particle size of no more than 0.1mm.

3. The preparation method of Yunnan red clay-based composite porous ceramsite according to claim 1 or 2, characterized in that, The mass ratio of Yunnan red clay particles, sepiolite powder, and biomass powder is 10:2-3:1-3.

4. The method for preparing Yunnan red clay-based composite porous ceramsite according to any one of claims 1-3, characterized in that, The raw material balls have a particle size of 1-10 mm.

5. The method for preparing Yunnan red clay-based composite porous ceramsite according to any one of claims 1-4, characterized in that, The drying temperature is 90-120℃, and the product is dried to a constant weight.

6. The method for preparing Yunnan red clay-based composite porous ceramsite according to any one of claims 1-5, characterized in that, The calcination temperature is 600-800℃, and the time is 2-4 hours; the calcination is carried out in air or oxygen.

7. The preparation method of Yunnan red clay-based composite porous ceramsite according to claim 1, characterized in that, The organic acid is at least one of malic acid, oxalic acid, lactic acid or tartaric acid, and the plant fiber is at least one of jute fiber, flax fiber, ramie fiber, sisal fiber or bamboo fiber.

8. A Yunnan red clay-based composite porous ceramsite prepared by the preparation method according to any one of claims 1-7.

9. The application of the Yunnan red clay-based composite porous ceramsite as described in claim 8 in wastewater treatment.

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