Efficient phosphorus removal adsorptive ceramsite as well as preparation method and application thereof

Abstract

The invention discloses efficient phosphorus removal adsorptive ceramsite as well as a preparation method and application thereof, and belongs to the technical field of water treatment. The efficient phosphorus removal adsorptive ceramsite is prepared from the following raw materials in parts by mass: 50 to 65 parts of wet sludge, 20 to 35 parts of cement and 10 to 25 parts of gypsum, the wet sludge contains organic matters. According to the invention, wet sludge containing organic matters is adopted as a raw material, and a low-temperature heat treatment mode is adopted, so that the prepared efficient phosphorus removal adsorptive ceramsite can keep good structural stability, has excellent phosphorus removal capacity, and shows efficient and stable phosphorus removal effect in water bodies with different phosphorus concentrations.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a highly efficient phosphorus removal adsorption ceramic particle, its preparation method, and its application. Background Technology

[0002] Phosphorus is a key factor in eutrophication of water bodies. When the concentration of phosphorus in water exceeds the standard, it promotes the proliferation of algae and other plankton, leading to algal blooms and severely disrupting the ecological balance of the water body. Therefore, achieving effective phosphorus removal is a crucial measure to ensure water quality and achieve compliant wastewater discharge.

[0003] Currently, methods for phosphorus removal from water bodies mainly include chemical precipitation, biological methods, and adsorption. Among these, adsorption has broad application prospects in the field of phosphorus removal due to its simple process, high treatment efficiency, strong adaptability, low operating cost, and lack of secondary pollution. Developing efficient and low-cost adsorption materials is key to the widespread application of adsorption methods.

[0004] On the other hand, China possesses abundant river and lake silt resources, generating massive quantities that can cause serious environmental problems if not properly managed. Utilizing river and lake silt resources, particularly for preparing ceramsite materials with excellent adsorption properties, can not only effectively alleviate the environmental pressure caused by silt accumulation but also provide an economical and effective solution for phosphorus removal from water bodies. Currently, the main technology for preparing ceramsite from river and lake silt is the high-temperature sintering method, but this process is complex, energy-intensive, and causes significant pollution. Therefore, providing a simple method for preparing adsorbent ceramsite to meet the needs of phosphorus removal from water bodies is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a highly efficient phosphorus removal adsorbent ceramsite, its preparation method, and its applications. The highly efficient phosphorus removal adsorbent ceramsite of this invention exhibits good structural stability and adaptability, achieving highly efficient and stable phosphorus removal effects at varying phosphorus concentrations.

[0006] The technical solution of the present invention is as follows: The first aspect of this invention protects a highly efficient phosphorus-removing adsorbent ceramsite, comprising the following raw materials in parts by weight: 50-65 parts wet sludge, 20-35 parts cement, and 10-25 parts gypsum; wherein the wet sludge contains organic matter.

[0007] Preferably, the organic matter content in the wet sludge is 1~10wt%.

[0008] Preferably, the wet silt includes river and lake silt, and the organic matter includes algae.

[0009] Preferably, the water content in the wet sludge is 60-90 wt%.

[0010] The second aspect of this invention protects a method for preparing the highly efficient phosphorus-removing adsorbent ceramsite described in the first aspect, comprising the following steps: S1. The wet sludge of the specified formula is subjected to impurity removal and homogenization treatment; S2. Mix the cement, gypsum and wet sludge treated in step S1 in the specified amounts until a viscous blank is formed. S3. Form the viscous blank into spherical materials; S4. After the spherical material is left to stand and dry, it is immersed in water for primary water curing, and then naturally cured with water retention to obtain primary ceramsite. S5. The primary ceramsite is heat-treated and cooled to obtain highly efficient phosphorus-removing and adsorbent ceramsite.

[0011] Preferably, the specific steps of S3 include: pressing the viscous blank into a cake shape, cutting it into long strips, then making it into granules, and finally rolling it into a spherical shape.

[0012] Preferably, the viscous blank is pressed into a cake shape with a thickness of 8-15mm, then cut into strips with a width of 8-15mm, then made into granules with a diameter of 8-15mm, and finally rolled into a spherical shape in a roller.

[0013] Preferably, in step S4, the static drying time is 20-28 hours; And / or, the static drying is carried out at room temperature; And / or, the immersion time in water is 55-65 hours; And / or, the water retention and natural curing time is 20~30 days.

[0014] Preferably, in step S5, the heat treatment includes: heating the primary ceramsite to 300-500°C at a rate of 5-10°C / min, preheating for 10-30 min, and then holding at that temperature for 0.5-3 h.

[0015] The third aspect of this invention protects the application of a highly efficient phosphorus-removing adsorbent ceramic particle in the treatment of phosphorus-containing water bodies, wherein the highly efficient phosphorus-removing adsorbent ceramic particle includes the highly efficient phosphorus-removing adsorbent ceramic particle described in the first aspect, and / or the highly efficient phosphorus-removing adsorbent ceramic particle prepared by the preparation method described in the second aspect.

[0016] The beneficial technical effects of this invention are as follows: This invention uses wet sludge containing organic matter as raw material and employs low-temperature heat treatment to produce highly efficient phosphorus-removing adsorbent ceramsite. This ceramsite is lightweight and has a porous structure, providing effective adsorption space while maintaining good structural stability. Furthermore, the ceramsite of this invention exhibits excellent phosphorus removal capabilities and demonstrates highly efficient and stable phosphorus removal effects in water bodies with varying phosphorus concentrations. It possesses good stability and adaptability, making it suitable for efficient phosphorus removal treatment in various types of water bodies. Detailed Implementation

[0017] The present invention will now be described in detail with reference to specific embodiments.

[0018] A high-efficiency phosphorus-removing adsorbent ceramsite comprises the following raw materials in parts by weight: 50-65 parts wet sludge, 20-35 parts cement, and 10-25 parts gypsum; wherein the wet sludge contains organic matter.

[0019] In some embodiments, the wet silt includes river and lake silt, and the organic matter includes algae. Preferably, the wet silt is Taihu Lake silt, and the organic matter exists mainly in the form of algae.

[0020] In the following embodiments and comparative examples of the present invention: the wet sludge containing organic matter used is from Taihu Lake; the wet sludge without organic matter used is from Taihu Lake; the cement is commercially available 425R Brandt cement; and the gypsum is ordinary commercially available building gypsum.

[0021] The main chemical components of the silt are SiO2, Al2O3, and Fe2O3; the main chemical components of the cement are SiO2, Al2O3, and CaO.

[0022] A method for preparing highly efficient phosphorus removal adsorbent ceramic particles includes the following steps: S1. The wet sludge of the specified formula is subjected to impurity removal and homogenization treatment; S2. Mix the cement, gypsum and wet sludge treated in step S1 in the specified amounts until a viscous blank is formed. S3. Form the viscous blank into spherical materials; S4. After the spherical material is left to stand and dry, it is immersed in water for primary water curing, and then naturally cured with water retention to obtain primary ceramsite. S5. The primary ceramsite is heat-treated and cooled to obtain highly efficient phosphorus-removing and adsorbent ceramsite.

[0023] In some embodiments, the heat treatment includes: heating the primary ceramsite to 300-500°C at a rate of 5-10°C / min, preheating for 10-30 min, and then holding at that temperature for 0.5-3 h. The heat treatment can be carried out in a muffle furnace.

[0024] In some embodiments, the water-retaining natural curing step is as follows: the naturally cured ceramsite is placed in a curing box and naturally cured at room temperature.

[0025] In the above preparation process, cement and gypsum, as cementing materials, generate hydration products such as ettringite and CSH gel during hydration. These hydration products fill the spaces between raw material particles, forming a dense network structure, thereby improving the strength and stability of the ceramsite.

[0026] During the water retention, natural curing, and heat treatment stages, the inorganic and organic decomposition products, cement hydrates, and other substances contained in the wet sludge undergo further reactions, releasing a large number of cations and forming new mineral phases such as silicate and aluminate minerals. These new mineral phases possess high stability, weather resistance, and strong heavy metal solidification capabilities, effectively fixing heavy metals and other harmful substances and preventing their release into the environment, thereby effectively reducing the risk of environmental pollution.

[0027] During heat treatment at 300–500℃, the organic matter in the wet sludge undergoes thermal decomposition and carbonization, generating a porous carbon framework and introducing various oxygen-containing functional groups, such as carboxyl and hydroxyl groups, onto its surface. These functional groups possess high hydrophilicity and phosphorus affinity, serving as adsorption sites for phosphate ions and enhancing chemisorption capacity. Simultaneously, the oxygen-containing functional groups exhibit a certain complexing ability, forming complexes with phosphate ions to enhance the selectivity and irreversibility of adsorption.

[0028] Low-temperature heat treatment at 300~500℃ not only avoids the complete ablation of organic matter, but also preserves or induces the formation of a more developed porous network structure, significantly improving the specific surface area of ​​the ceramsite and the adsorption capacity of phosphorus.

[0029] The above-mentioned high-efficiency phosphorus-removing adsorbent ceramic particles can be used to adsorb phosphorus in water bodies.

[0030] The adsorption mechanism of phosphorus by the highly efficient phosphorus-removing ceramsite is as follows:

[0031] The adsorption of phosphate on ceramsite mainly includes chemical precipitation and inner layer complexation. Metal cations and oxides present on the surface or in the pores of ceramsite can react chemically with phosphate ions in water to form insoluble precipitates with low solubility, which adhere to the surface of ceramsite or fill the pores, thus fixing phosphorus.

[0032] The functional groups such as hydroxyl groups on the oxides or hydrated gel products on the surface of ceramsite can undergo inner-layer complexation reactions with phosphate ions to form stable complexes, thereby enhancing the irreversible adsorption of phosphorus.

[0033] Example 1 A high-efficiency phosphorus removal adsorbent ceramsite comprises the following raw materials in parts by weight: 55 parts wet sludge, 35 parts cement, and 10 parts gypsum; wherein the wet sludge contains 3-5 wt% organic matter and 80 wt% water.

[0034] A method for preparing highly efficient phosphorus removal adsorbent ceramic particles includes the following steps: S1. The wet sludge of the formula amount is subjected to impurity removal and homogenization treatment.

[0035] S2. Mix the cement, gypsum, and wet sludge treated in step S1 until a viscous blank is formed.

[0036] S3. First, press the blank into a cake shape with a thickness of 10mm, then cut it into strips with a width of 10mm, then make granular ceramic blanks with a diameter of 10mm, and finally place the ceramic blanks into a roller to obtain spherical material.

[0037] S4. The spherical material is left to dry at room temperature for 24 hours, then completely immersed in water for 60 hours, and then placed in a curing box for natural curing at room temperature for 25 days to obtain primary ceramsite. S5. Place the primary ceramsite in a muffle furnace and heat it to 300℃ at a heating rate of 8℃ / min. Preheat for 15 minutes, hold for sintering for 30 minutes, and then cool to obtain highly efficient phosphorus removal and adsorption ceramsite.

[0038] Example 2 A highly efficient phosphorus-removing adsorbent ceramic particle, the raw materials of which are the same as those in Example 1.

[0039] A method for preparing highly efficient phosphorus-removing adsorbent ceramic particles is basically the same as that in Example 1, except that the sintering temperature in step S5 is 400℃.

[0040] Example 3 A high-efficiency phosphorus removal adsorption ceramsite comprises the following raw materials in parts by weight: 55 parts wet sludge, 35 parts cement, and 10 parts gypsum; wherein the organic matter content of the wet sludge is 2-3 wt% and the water content is 80 wt%.

[0041] A method for preparing highly efficient phosphorus-removing adsorbent ceramic particles is the same as in Example 1.

[0042] Comparative Example 1 A highly efficient phosphorus-removing adsorbent ceramic particle, the raw materials of which are the same as those in Example 1.

[0043] A method for preparing highly efficient phosphorus-removing adsorbent ceramic particles is basically the same as that in Example 1, except that the sintering temperature in step S5 is 1000℃.

[0044] Comparative Example 2 A highly efficient phosphorus-removing adsorbent ceramsite comprises the following raw materials in parts by weight: 55 parts wet sludge, 35 parts cement, and 10 parts gypsum; the sludge contains 80 wt% water and no organic matter.

[0045] A method for preparing highly efficient phosphorus-removing adsorbent ceramic particles is the same as in Example 1.

[0046] Comparative Example 3 A highly efficient phosphorus-removing adsorbent ceramsite comprises the following raw materials in parts by weight: 55 parts wet sludge, 35 parts cement, and 10 parts gypsum; the sludge contains 80 wt% water and no organic matter.

[0047] A method for preparing highly efficient phosphorus-removing adsorbent ceramic particles is basically the same as that in Example 1, except that the sintering temperature in step S5 is 400℃.

[0048] Test case 1. The physical properties of the high-efficiency phosphorus removal adsorption ceramsite prepared in Examples 1, 2, 2, and 3 were tested according to the following method. The test results are shown in the table below.

[0049] The testing method is as follows: (1) Bulk density Take an appropriate amount of dry ceramsite and gently put it into the measuring cylinder until the ceramsite is level with the mouth of the measuring cylinder. Fill the depression with ceramsite of smaller diameter to make it full, and calculate the bulk density of the ceramsite according to formula (3-1).

[0050] Equation (3-1) —Bulk density, in g / cm³ 3 m t —The mass of the expanded clay sample and the volumetric cylinder, in grams; m v —The mass of the measuring cylinder, in grams; V v —The volume of the measuring cylinder, in cm³. 3 .

[0051] (2) Particle density In the particle density tests of the ceramsite in each embodiment and comparative example, the number of ceramsite particles in each test group was not less than 15. The perimeter and mass of each ceramsite particle were measured to obtain the particle density of each ceramsite particle.

[0052] Equation (3-2) In the formula: ρ—the particle density of a single ceramsite, in kg / m³ 3 m—mass of a single ceramsite, in kg; d—circumference of a single ceramsite, in m.

[0053] (3) Water absorption rate Take 20-30 g of dried ceramsite prepared in each example and comparative example and place it in a 250 mL beaker. Add deionized water to completely submerge the ceramsite. After 24 h, remove the ceramsite and filter it through a 0.08 mm mesh sieve to remove surface moisture. Wipe away any visible moisture on the surface of the ceramsite with a damp cloth. Weigh the ceramsite at this point and calculate its mass according to formula (3-3).

[0054] Equation (3-3) C x —Water absorption rate, in %; m—Mass of expanded clay aggregate before water absorption, in g; m x —The mass of the expanded clay pellets after absorbing water, in grams.

[0055] (4) The sum of breakage and wear rates Weigh out 100 ± 5 g of ceramsite prepared for each example and comparative example, after washing, drying, and passing it through a 0.5 mm sieve. Place the ceramsite in a metal cylinder with an inner diameter of 50 mm and a height of 150 mm. Add six 8 mm diameter bearing steel balls, tighten the cylinder lid, and vibrate for 15 min on a vibrator with a stroke of 140 mm and a frequency of 150 times / min. Weigh the mass that passes through the 0.5 mm sieve. The sum of the breakage and wear rates is calculated according to formula (3-4).

[0056] Equation (3-4) Cb—the sum of breakage and wear rates, expressed as a percentage, with the result rounded to two decimal places; m b —Sample mass passing through a 0.5 mm sieve, in grams (g); m —Total mass of the ceramic filter media sample, in grams (g).

[0057] Table 1: Physical properties of high-efficiency phosphorus removal adsorption ceramsite

[0058] As shown in Table 1, the bulk density and particle density of the ceramsite prepared in Examples 1 and 2 are significantly lower than those in Comparative Examples 2 and 3. The water absorption rate and the sum of the breakage and wear rate of the ceramsite in Examples 1 and 2 are also less than those in Comparative Examples 2 and 3. This indicates that compared with the preparation of ceramsite using wet sludge containing no organic matter, the ceramsite prepared by the present invention using wet sludge containing organic matter as raw material is lighter and more conducive to achieving good fluid dynamics conditions in water treatment. At the same time, it has a suitable pore structure, which can provide effective adsorption space and maintain good structural stability.

[0059] 2. The phosphorus removal rate of the high-efficiency phosphorus-removing adsorbent ceramic particles prepared in Examples 1-3, Comparative Examples 1 and 2 was tested according to the following method.

[0060] The detection method is as follows: The ceramsite prepared in the examples and comparative examples was added to phosphorus-containing solutions with different initial phosphorus concentrations at a dosage of 20 g / L, and adsorption experiments were conducted under stirring conditions of 35℃ and 130 r / min. Samples were taken periodically to determine the phosphorus concentration in the solution, and the phosphorus removal rate of the ceramsite was calculated.

[0061] Phosphorus removal rate = (Initial phosphate concentration - Phosphorus concentration at adsorption equilibrium) / Initial phosphate concentration Table 2: Phosphorus removal rate of high-efficiency phosphorus-removing adsorbent ceramic particles

[0062] As can be seen from Table 2, the phosphorus removal rate of the ceramsite prepared in Examples 1-3 of this invention is much better than that of Comparative Example 1, indicating that excessively high sintering temperature will significantly reduce the adsorption performance of the ceramsite, which is not conducive to phosphorus removal.

[0063] Table 2 also shows that the phosphorus removal rate of the ceramsite prepared in Examples 1-3 of this invention is better than that of Comparative Example 2. This indicates that compared with ceramsite prepared using wet sludge containing organic matter, the ceramsite prepared using wet sludge containing organic matter as raw material in this application has a higher phosphorus removal rate at different initial phosphorus concentrations. This shows that they are stable in water bodies with different phosphorus concentrations and have good stability and adaptability. As the initial phosphorus concentration increases, the phosphorus removal rate of the ceramsite in the examples remains at a high level. Under high concentration conditions (5 mg / L), the phosphorus removal rate of the ceramsite in Examples 1-3 is still as high as 97% or more, demonstrating excellent phosphorus removal ability.

[0064] In summary, the high-efficiency phosphorus-removing adsorbent ceramsite prepared by sintering wet sludge containing organic matter at a relatively low temperature has a suitable pore structure, good structural stability and adaptability, and can achieve efficient and stable phosphorus removal effect under different phosphorus concentrations. It is applicable to the efficient phosphorus removal treatment of various water bodies.

[0065] The above description is merely a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A high-efficiency phosphorus removal adsorption ceramic particle, characterized in that, The raw materials include the following parts by weight: 50-65 parts wet sludge, 20-35 parts cement, and 10-25 parts gypsum; the wet sludge contains organic matter.

2. The high-efficiency phosphorus removal adsorption ceramic granules according to claim 1, characterized in that, The organic matter content in the wet sludge is 1~10wt%.

3. The high-efficiency phosphorus removal adsorption ceramic granules according to claim 1 or 2, characterized in that, The wet silt includes river and lake silt, and the organic matter includes algae.

4. The high-efficiency phosphorus removal adsorption ceramsite according to claim 1, characterized in that, The water content in the wet sludge is 60-90 wt%.

5. A method for preparing highly efficient phosphorus-removing adsorbent ceramsite according to any one of claims 1-4, characterized in that, Includes the following steps: S1. The wet sludge of the specified formula is subjected to impurity removal and homogenization treatment; S2. Mix the cement, gypsum and wet sludge treated in step S1 in the specified amounts until a viscous blank is formed. S3. Form the viscous blank into spherical materials; S4. After the spherical material is left to stand and dry, it is immersed in water for primary water curing, and then naturally cured with water retention to obtain primary ceramsite. S5. The primary ceramsite is heat-treated and cooled to obtain highly efficient phosphorus-removing and adsorbent ceramsite.

6. The preparation method according to claim 5, characterized in that, The specific steps of S3 include: pressing the viscous blank into a cake shape, cutting it into long strips, then making it into granules, and finally rolling it into a spherical shape.

7. The preparation method according to claim 6, characterized in that, The viscous raw material is pressed into a cake shape with a thickness of 8-15mm, then cut into strips with a width of 8-15mm, then made into granules with a diameter of 8-15mm, and finally rolled into a spherical shape in a roller.

8. The preparation method according to claim 5, characterized in that, In step S4, the static drying time is 20-28 hours; And / or, the static drying is carried out at room temperature; And / or, the immersion time in water is 55-65 hours; And / or, the water retention and natural curing time is 20~30 days.

9. The preparation method according to claim 5, characterized in that, In S5, the heat treatment includes: heating the primary ceramsite to 300-500°C at a rate of 5-10°C / min, preheating for 10-30 min, and then holding at that temperature for 0.5-3 h.

10. The application of a highly efficient phosphorus-removing adsorbent ceramsite in the treatment of phosphorus-containing water, characterized in that, The high-efficiency phosphorus removal adsorption ceramic particles include the high-efficiency phosphorus removal adsorption ceramic particles according to any one of claims 1 to 4, and / or the high-efficiency phosphorus removal adsorption ceramic particles prepared by the preparation method according to any one of claims 5 to 9.

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