Composite dephosphorizing agent and use method thereof
By using a combination of compound dephosphorizing agents, the problems of poor total phosphorus treatment effect and biosafety in existing technologies are solved, achieving efficient and safe water purification effect, which is suitable for a variety of water environments.
Patent Information
- Application Number
- CN202511420820.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-01-09
AI Technical Summary
Existing metal-modified materials are ineffective in treating water bodies with total phosphorus concentrations greater than 0.5 mg/L and pose secondary pollution and biosafety issues, making it difficult to effectively solve the problem of eutrophication.
A composite dephosphorizing agent is used, which is composed of polyaluminum chloride, attapulgite, and attapulgite@graphene oxide@active metal ion composite material. Through ion exchange and chelation, it synergistically improves the adsorption effect of phosphorus, and utilizes the catalytic effect of graphene to decompose recalcitrant organic matter and ammonia nitrogen.
It achieves efficient treatment of water bodies with total phosphorus greater than 0.5 mg/L, has high biological safety, lower cost than traditional methods, can maintain water purification effect for a long time, and is suitable for various water environments.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment, specifically to a composite dephosphorizing agent and its application method. Background Technology
[0002] Phosphorus (P) is a double-edged sword: its presence is essential for various life forms and plays a crucial role in water bodies such as ponds, lakes, and reservoirs. However, excessive phosphorus concentrations in these water bodies lead to a series of aquatic environmental problems, the most prominent being eutrophication. Eutrophication not only causes turbidity and foul odors in the water and mass fish deaths, but also affects the quality of drinking water for people's production and daily life, and the health of residents. Therefore, controlling phosphorus in water bodies is urgently needed.
[0003] In recent years, metal-modified materials (such as aluminum-based, lanthanum-based, and iron-based materials) have been introduced into many lakes around the world to adsorb phosphorus, thereby addressing eutrophication. However, these materials are less effective at treating water bodies with total phosphorus concentrations greater than 0.5 mg / L, and their large-scale use could introduce other substances that pollute the water or pose secondary pollution and biosafety risks. Summary of the Invention
[0004] This invention provides a composite dephosphorizing agent and its application method. The composite dephosphorizing agent of this invention is effective in treating water bodies with total phosphorus greater than 0.5 mg / L and has high biological safety.
[0005] This invention provides a composite dephosphorizing agent, comprising the following components by mass fraction: Polyaluminum chloride 10-75%, attapulgite 15-89%, and attapulgite@graphene oxide@active metal ion composite material 1-10%; The attapulgite@graphene oxide@active metal ion composite material includes attapulgite clay modified with active metal ions and graphene oxide loaded on the attapulgite clay modified with active metal ions. The active metal ions in the modified attapulgite include ferric ions or ferrous ions.
[0006] Preferably, the mass fraction of graphene oxide in the attapulgite@graphene oxide@active metal ion composite material is 0.1~10%.
[0007] Preferably, the preparation method of the attapulgite@graphene oxide@active metal ion composite material includes the following steps: (1) Mix attapulgite clay with water to obtain a slurry; (2) The ferric salt or ferrous salt is mixed with the slurry to modify it, thereby obtaining a system containing modified attapulgite. (3) The system containing modified attapulgite is mixed with the dispersion of graphene oxide and then dried to obtain the attapulgite@graphene oxide@active metal ion composite material.
[0008] Preferably, the mass fraction of attapulgite in the slurry is 5-40%; the particle size of the attapulgite is 320-500 mesh.
[0009] Preferably, the anions in the ferric and ferrous salts include chloride ions and / or sulfate ions.
[0010] Preferably, the mass ratio of the iron salt or ferrous salt to the attapulgite in step (1) is 1~5:100, based on the iron ions in the iron salt or ferrous ions in the ferrous salt.
[0011] Preferably, the volume ratio of the system containing modified attapulgite to the dispersion of graphene oxide is 1:0.2~20.
[0012] Preferably, the drying includes vacuum spray drying, wherein the vacuum degree of the vacuum spray drying is not higher than 20 Pa, the temperature is not higher than 100°C, and the time is 30~240 min.
[0013] The present invention also provides a method for using the composite dephosphorizing agent described in the above technical solution, characterized by comprising the following steps: The composite dephosphorizing agent described in the above technical solution is added to phosphorus-containing wastewater.
[0014] Preferably, the pH value of the phosphorus-containing wastewater is 6 to 9.
[0015] This invention cleverly combines the properties of graphene with those of attapulgite to enhance the properties of graphene. At the same time, the ion exchange and ion chelation properties of the composite attapulgite are further improved by the modification of attapulgite with active metal ions, which can endow attapulgite with phosphorus pollution removal properties.
[0016] The attapulgite@graphene oxide@active metal ion composite material of the present invention, when combined with polyaluminum chloride (PAC), can synergistically form a better safe and environmentally friendly water treatment agent, and significantly reduce the amount of PAC used (by more than 80%), reduce the environmental impact of chloride ions, and due to the reduction in the amount of PAC used, the composite dephosphorizing agent and corresponding application technology of the present invention save more than 60% of the cost compared with traditional PAC and other water treatment technologies.
[0017] Furthermore, attapulgite is a natural mineral with a high specific surface area. When it sinks to the bottom of the water, it can improve the structure of the sediment, creating a favorable environment for the growth of indigenous microorganisms. This promotes the growth of indigenous microorganisms, enhances the self-purification capacity of the water body, and thus helps maintain water quality for a longer period. The composite dephosphorizing agent of this invention typically maintains its properties for more than 30 days in closed water bodies, and can maintain its properties for 60-90 days in winter or when there is no large amount of pollutant entering.
[0018] Since attapulgite is a natural mineral that can be used as a food additive, and the attapulgite@graphene oxide@active metal ion composite material has also passed the biotoxicity assessment and is non-toxic and safe, the composite dephosphorizing agent and corresponding application technology of this invention are more biosafe than traditional water treatment technologies such as sodium hypochlorite and other strong oxidants, and reduce the impact on the natural environment.
[0019] The composite dephosphorizing agent of this invention is a product modified with graphene from natural mineral materials. It utilizes the huge specific surface area of solid microparticles and the ion exchange that occurs at the liquid interface to adsorb and fix pollutants. It can adsorb and fix the total phosphorus in wastewater into the adsorbent through ion exchange and chelation in a short time, thereby rapidly reducing the total phosphorus concentration in wastewater. It has the characteristics of fast reaction speed, wide applicability, and no need to change the treatment process. It is suitable for polluted water bodies with a total phosphorus concentration of less than 3 mg / L.
[0020] The composite dephosphorizing agent of this invention uses chemically inert, pollution-free, and environmentally friendly natural mineral materials. Combined with the catalytic effect of modified graphene materials, through synergistic oxidation, it ultimately decomposes recalcitrant organic matter (COD) and ammonia nitrogen into carbon dioxide, water, and nitrogen, reducing nitrogen and phosphorus levels in eutrophic water bodies to a low level and inhibiting the proliferation of various algae. Furthermore, attapulgite, a natural mineral with a high specific surface area, sinks to the bottom and improves the sediment structure, creating a favorable environment for the growth of indigenous microorganisms, thus promoting their growth. This stimulation of indigenous microorganism growth also enhances the water body's self-purification capacity, contributing to the long-term maintenance of water quality and ultimately resolving the eutrophication problem. Attached Figure Description
[0021] Figure 1 The images show a comparison of the treatment process before and after the treatment in Example 1 of the project. Figure 2 This is a comparison image of the treatment process before and after the treatment in Example 2 of the project; Figure 3 This is a comparison image of the treatment process before and after the treatment in Example 3 of the project. Detailed Implementation
[0022] This invention provides a composite dephosphorizing agent, comprising the following components by mass fraction: Polyaluminum chloride 10-75%, attapulgite 15-89%, and attapulgite@graphene oxide@active metal ion composite material 1-10%; The attapulgite@graphene oxide@active metal ion composite material includes attapulgite clay modified with active metal ions and graphene oxide loaded on the attapulgite clay modified with active metal ions. The active metal ions in the modified attapulgite include ferric ions or ferrous ions.
[0023] The composite dephosphorizing agent provided by the present invention comprises 10-75% polyaluminum chloride by mass fraction, and in specific embodiments of the present invention, it can be 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%.
[0024] The composite dephosphorizing agent provided by the present invention comprises 15-89% attapulgite by mass fraction, and in specific embodiments of the present invention, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or 85%.
[0025] The composite dephosphorizing agent provided by the present invention comprises 1-10% attapulgite@graphene oxide@active metal ion composite material by mass fraction, which can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 9% in specific embodiments of the present invention; the attapulgite@graphene oxide@active metal ion composite material comprises modified attapulgite clay and graphene oxide loaded on the modified attapulgite clay; the mass fraction of graphene oxide in the attapulgite@graphene oxide@active metal ion composite material is preferably 0.1-10%, which can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 9% in specific embodiments of the present invention; the modified attapulgite clay preferably comprises attapulgite clay modified with ferrous ions or ferrous ions.
[0026] In this invention, the preparation method of the attapulgite@graphene oxide@active metal ion composite material preferably includes the following steps: Attapulgite clay is mixed with water to obtain a slurry; The slurry is modified by mixing ferric salts or ferrous salts to obtain a system of modified attapulgite containing active metal ions. The system containing active metal ions modified attapulgite was mixed with a dispersion of graphene oxide and then dried to obtain the attapulgite@graphene oxide@active metal ion composite material.
[0027] This invention involves mixing attapulgite clay with water to obtain a slurry.
[0028] In this invention, the particle size of the attapulgite is preferably 320-500 mesh, and in specific embodiments of this invention, it can be 350 mesh, 380 mesh, 400 mesh, 420 mesh, 450 mesh, or 480 mesh; the mass fraction of the attapulgite in the slurry is preferably 5-40%, and in specific embodiments of this invention, it can be 10%, 15%, 20%, 25%, 30%, or 35%.
[0029] After obtaining the slurry, the present invention modifies it by mixing ferric salts or ferrous salts with the slurry to obtain a system containing modified attapulgite.
[0030] In this invention, the mass ratio of the iron salt or ferrous salt to attapulgite is preferably 1 to 5:100, based on the iron ions in the iron salt or ferrous salt. In specific embodiments of this invention, it can be 2:100, 3:100 or 4:100. The anions in the iron salt and ferrous salt preferably include chloride ions and / or sulfate ions.
[0031] In this invention, the modification is preferably carried out under stirring conditions, and the modification time is preferably ≥60 min, more preferably 90~240 min.
[0032] Natural attapulgite contains metal ions such as aluminum, magnesium, and iron. Due to its special silicate structure, these metals lack ionic activity. The purpose of modification is to improve the activity of these types of ions, so that in applications, ion exchange, chelation, and adsorption can be achieved to form insoluble salts and insoluble minerals.
[0033] After obtaining the system containing modified attapulgite, the present invention mixes the system containing modified attapulgite with a dispersion of graphene oxide and then dries it to obtain the attapulgite@graphene oxide@active metal ion composite material.
[0034] In this invention, the volume ratio of the system containing modified attapulgite to the dispersion of graphene oxide is preferably 1:0.2~20. In specific embodiments of this invention, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, or 1:19. The concentration of graphene oxide in the dispersion is preferably ≤10 mg / mL, and in specific embodiments of this invention, it can be 1 mg / mL. The concentrations are L, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, or 9 mg / mL; the preferred diameter of the graphene oxide is 400~1200 nm, and the monolayer ratio is >90%. In specific embodiments of the present invention, the diameter of the graphene oxide can be 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, or 1100 nm, and the monolayer ratio can be 92%, 94%, 96%, or 98%; the dispersant in the dispersion preferably includes water.
[0035] In this invention, the drying preferably includes vacuum spray drying, wherein the vacuum degree of the vacuum spray drying is preferably not higher than 20 Pa, the temperature is preferably not higher than 100 °C, and the time is preferably 30~240 min. In specific embodiments of this invention, the vacuum degree is preferably 2 Pa, 4 Pa, 6 Pa, 8 Pa, 10 Pa, 12 Pa, 15 Pa, or 18 Pa, the temperature can be 20 °C, 40 °C, 60 °C, or 80 °C, and the time can be 50 min, 80 min, 100 min, 120 min, 150 min, 180 min, 200 min, or 220 min.
[0036] The present invention does not impose any special limitations on the preparation method of the composite dephosphorizing agent; the components can be mixed evenly.
[0037] The composite dephosphorizing agent of this invention can be used in natural water bodies without affecting aquatic organisms.
[0038] The present invention also provides a method for using the composite dephosphorizing agent described in the above technical solution, comprising the following steps: The composite dephosphorizing agent described in the above technical solution is added to phosphorus-containing wastewater.
[0039] In this invention, the pH value of the phosphorus-containing wastewater is preferably 6 to 9.
[0040] The present invention does not have a special limitation on the amount of the composite dephosphorizing agent; it can be determined based on experimental results.
[0041] The preferred input methods include direct addition or addition via water pump after dissolving and stirring evenly.
[0042] The following detailed description of the composite dephosphorizing agent and its application method provided by the present invention, in conjunction with specific examples, should not be construed as limiting the scope of protection of the present invention.
[0043] The water samples taken in the examples and comparative examples were all from rivers.
[0044] Example The particle size of attapulgite is 320~500 mesh.
[0045] Preparation of 5 mg / mL graphene oxide dispersion: (1) Add 2g of 500-mesh high-purity flake graphite and 2g of sodium nitrate to 100mL of concentrated sulfuric acid, cool to 0℃ and stir continuously, keep warm at 0℃ for 2h; (2) Then slowly add 12g of potassium permanganate. During the addition of potassium permanganate, the temperature is kept at 0~5℃, and stirring is continued for 90 minutes. (3) Then raise the temperature to 40℃ and continue stirring for 2 hours; (4) Stop heating and continue stirring. Slowly add 80 mL of deionized water, making sure the temperature does not exceed 80 °C. (5) After adding water, add 10 mL of 30% hydrogen peroxide while keeping the temperature below 80℃, stir for 10 minutes and then remove. (6) The obtained graphene oxide was repeatedly washed with deionized water until neutral and separated. Then, the content of graphene oxide in the water was measured and metered pure water was added to obtain a graphene oxide dispersion with a concentration of 5 mg / mL.
[0046] The graphene oxide dispersion contains graphene sheets with a diameter of 400~1200nm and a monolayer ratio of >90%; the graphene oxide purity is >99%, the dispersion is pure water, the graphene oxide concentration is 5mg / mL, and it does not contain any dispersants or other non-graphene substances; the band gap is 1.71~5.0eV, corresponding to an intrinsic absorption wavelength limit of 245~725nm, and it has broad absorption in the ultraviolet and visible light range.
[0047] Preparation of attapulgite@graphene oxide@active metal ion composite materials: (1) Pulping: Add 10g of attapulgite clay to 10mL of water in a high-speed disperser and mix evenly (stirring speed 300r / min) to obtain slurry; (2) Metal ion activation modification: Under medium speed stirring, 0.2g or 0.4g of ferric sulfate (calculated as iron ions) is added to the slurry and stirred for 180min to obtain a system containing active metal ions modified attapulgite. (3) Graphene oxide aging modification: Increase the stirring speed of the disperser and maintain it (rotation speed of 800 r / min). Add 100 mL of 5 mg / mL graphene oxide dispersion to the slurry in step (2) and mix it evenly in the mixer.
[0048] (4) Drying: The drying process adopts vacuum spray drying process with a vacuum degree of 20 Pa, a drying temperature of 80 ℃, and a drying time of 45 min. The attapulgite is ground and pulverized to obtain attapulgite@5%GO@2%Fe(III) or attapulgite@5%GO@4%Fe(III) (attapulgite@5%GO@2%Fe(III) is prepared when the amount of ferric sulfate based on iron ions is 0.2 g; attapulgite@5%GO@4%Fe(III) is prepared when the amount of ferric sulfate based on iron ions is 0.4 g).
[0049] Table 1. Composition and wastewater purification effect of Examples 1-6
[0050] As shown in Table 1: (1) After treatment in Examples 1 to 6, all Class IV surface water can be purified to Class III surface water according to national standards; (2) The GO content in the water purification agent has little impact on the COD purification effect in a short period of time; (3) The content of active ferric ions in the water purification agent affects the dephosphorization effect. The higher the content of active ferric ions, the higher the dephosphorization efficiency. When the content of active ferric ions is the same, increasing the content of PAC is beneficial to dephosphorization.
[0051] Table 2 Composition and Wastewater Purification Effect of Examples 7-12
[0052] As shown in Table 2: (1) Examples 7-12 can all purify Class IV surface water to Class III surface water according to national standards; (2) The GO content in the water purification agent has little impact on the water purification effect in a short period of time; (3) The content of active ferric ions in the water purification agent affects the dephosphorization effect. The higher the content of active ferric ions, the higher the dephosphorization efficiency. When the content of active ferric ions is the same, increasing the content of PAC is beneficial to dephosphorization.
[0053] Table 3. Composition and wastewater purification effect of Examples 13-15 and Comparative Examples 1-2
[0054] As shown in Table 3: (1) Examples 13, 14 and 15 can all purify Class IV surface water to Class III surface water according to national standards; (2) The GO content in the water purification agent has a significant impact on the long-term effect of water purification. The higher the GO concentration, the better the water purification effect and the better the water quality retention. (3) In Comparative Examples 1 and 2, PAC can purify water quality. When the concentration is 1 / 1000, it can purify Class IV surface water to Class III surface water according to national standards. However, when the concentration is 2 / 10000, the effect is not significant and it can no longer purify Class III water. (4) In Comparative Examples 1 and 2, PAC can purify water quality but cannot maintain it for a long time. After seven days, the water quality returns to Class IV.
[0055] Table 4. Composition and wastewater purification effect of Examples 16-22
[0056] As shown in Table 4: (1) Examples 16-22 can purify Class V water to Class III and Class IV water according to national standards, and purify Class V surface water to Class III water according to national standards; (2) For Class V water with COD greater than 50 mg / L, a single preliminary purification can bring it up to Class IV surface water according to national standards.
[0057] Table 5. Composition and wastewater purification effect of Examples 14 and Comparative Examples 3-5
[0058] As shown in Table 5: (1) The preparation methods of attapulgite@5%GO@2%Al in Comparative Example 3, attapulgite@5%GO@2%Mg in Comparative Example 4 and attapulgite@5%GO@2%La(III) in Comparative Example 5 are basically the same as those of attapulgite@5%GO@2%Fe(III). The difference is that when the aluminum sulfate or aluminum chloride is 0.2g based on aluminum ions, attapulgite@5%GO@2%Al is prepared; when the magnesium sulfate or magnesium chloride is 0.2g based on magnesium ions, attapulgite@5%GO@2%Mg is prepared; when the lanthanum chloride is 0.2g based on lanthanum ions (III), attapulgite@5%GO@2%La(III) is prepared. (2) Examples 14 and Comparative Examples 3-5 can all purify Class IV surface water to Class III surface water according to national standards; (3) Although the dephosphorizing agent obtained by magnesium ion activated modified attapulgite composite material can also be used to remove soluble phosphate from water, magnesium phosphate still has a certain solubility and there is a risk of secondary redissolution over a long period of time. (4) The dephosphorizing agent obtained by lanthanum ion (III) activated modified attapulgite composite material can be used to remove soluble phosphate from water. A large number of literature reports and engineering practices show that the dephosphorizing effect is not good for water with total phosphorus greater than 0.5 mg / L, and it is difficult to meet the requirements of the national standard for surface water (III). (5) In engineering practice, iron salts and aluminum salts have good dephosphorization effects on attapulgite, especially trivalent iron salts.
[0059] (6) Aluminum-based, lanthanum-based, and iron-based materials have been extensively studied and are used in many lakes around the world. Compared with materials such as aluminum and lanthanum, iron is more environmentally friendly, affordable, and readily available.
[0060] Engineering Example 1 In the southwest area of a certain ancient city, covering an area of approximately 40,000 square meters with an average depth of 3 meters and a catchment area of 2.31 square kilometers, there is a population of 15,900. Before 2023, the surrounding sewage pipe network was severely damaged, resulting in direct discharge of domestic sewage into the lake area, causing the water to become black and smelly, and the aquatic ecological environment to deteriorate continuously, drawing strong complaints from surrounding residents. Rainwater and sewage separation was completed in this area in 2024, but the water quality in the lake still does not meet standards, classified as below Grade V, with some areas exhibiting black and smelly conditions. A pilot project was selected in the western part of the lake, covering an area of approximately 10,000 square meters with an average depth of 2 meters, a maximum depth of 3.8 meters, a water volume of approximately 30,000 cubic meters, and a transparency of 0.65 meters. The water quality is Grade V, with the main pollutant exceeding the standard being total phosphorus (concentration around 0.101 mg / L). The pilot project was launched on March 16, 2025, and has been underway for nearly 50 days. The water transparency increased from 0.65 meters to 1.4 meters, and the water quality improved from below Grade V to Grade III surface water.
[0061] Figure 1 This is a comparison image of the treatment process before and after the treatment in Example 1 of the project.
[0062] Table 6. Water parameters, construction conditions, and wastewater purification effects in Project Example 1
[0063] Note: The total phosphorus test data in the lake was obtained from the local environmental protection department.
[0064] As shown in Table 6: (1) The composite dephosphorization agent of the present invention can completely purify the water quality in eutrophic water with excessive total phosphorus, and purify Class V surface lake water to Class III surface lake water according to national standards. (2) The composite dephosphorizing agent of the present invention can completely purify the water quality in eutrophic water with excessive total phosphorus, and can remain in closed water bodies for a long time.
[0065] Engineering Example 2 A lake in a certain area experienced continuous deterioration of its aquatic ecosystem, consistently classified as Class V surface water since 2021. Aquatic vegetation coverage was low, accounting for only 12% of the lake's area. A pilot project was selected, measuring approximately 160 meters long, 50-70 meters wide, covering an area of about 10,000 square meters, with an average depth of 1.5 meters and a water volume of approximately 15,000 cubic meters. Water transparency ranged from 0.2 to 0.25 meters. The water quality was classified as worse than Class V, with total phosphorus (concentration around 0.18 mg / L) being the main pollutant exceeding standards. At the request of relevant departments, a two-week remediation program was implemented, which lasted 17 days. Water transparency improved from 0.25 meters to 1 meter, and the water quality improved from worse than Class V to Class III surface water.
[0066] Figure 2 This is a comparison image of the treatment process before and after the treatment in Example 2 of the project.
[0067] Table 7. Water parameters, construction conditions, and wastewater purification effects in Project Example 2
[0068] Note: The total phosphorus test data in the lake was obtained from the local environmental protection department. As shown in Table 7: (1) The composite dephosphorization agent of the present invention can completely purify the water quality in eutrophic water with excessive total phosphorus, and purify Class V surface lake water to Class III surface lake water according to national standards. (2) The composite dephosphorizing agent of the present invention can completely purify the water quality in eutrophic water with excessive total phosphorus, and can remain in closed water bodies for a long time.
[0069] Engineering Example 3 A lake in a certain area has an area of approximately 47.9 hectares, an average depth of 2 meters, and a transparency of about 0.35 meters. Before water quality treatment, it was classified as below Grade V, with total phosphorus being the main pollutant exceeding standards, at a concentration between 0.2 mg / L and 0.3 mg / L. There are three main reasons for the lake's water quality exceeding standards: First, pollution from pig farming. Several pig farms, with a total of nearly 5,000 pigs, were originally located around the lake. After government guidance, all farms have been relocated, but the original pollutants have accumulated in the lake, forming an endogenous source of pollution. Second, pollution from fish farming. The remaining farm area was contracted out to private individuals for fish farming, causing pollution to the lake. Third, a lack of environmental infrastructure. There is no sewage collection network along Qinggang Lake, indicating a significant deficiency in infrastructure. Domestic sewage from surrounding residents and industrial wastewater are discharged directly into the lake without effective treatment. Currently, preliminary pollution source control and interception work has been completed, with the closure and elimination of pig farms and aquaculture operations, and the improvement of sewage collection pipelines along the river. External pollution input has been effectively controlled. However, the lake still contains about one meter of aquaculture sediment, and endogenous pollution continues to be released. Therefore, this invention selects a portion of Qinggang Lake as a pilot area to implement a graphene photoecological water quality improvement project, promoting the pilot application and effect verification of the new technology.
[0070] The graphene photo-ecological water quality improvement pilot project is divided into two areas: shallow water area A and deep water area B, with phased treatment. Shallow water area A has a water area of approximately 2000 square meters and a depth of approximately 0.5-1.1 meters. Treatment began in early October 2024, and after about one week, the water transparency increased from 0.35 meters to 0.80 meters (virtually revealing the bottom); the water quality improved from below Grade V to Grade III surface water. Deep water area B has a water area of 1800 square meters and a depth of approximately 1.0-2.0 meters. Treatment began in early November 2024, and after one week, the water transparency increased from 0.35 meters to approximately 1.8 meters; the water quality improved from below Grade V to Grade III surface water.
[0071] Figure 3 This is a comparison image of the treatment process before and after the treatment in Example 3 of the project.
[0072] Table 8. Water parameters, construction conditions, and wastewater purification effects in Project Example 3
[0073] Note: The total phosphorus test data in the lake was obtained from the local environmental protection department. As shown in Table 8: (1) The composite dephosphorizing agent of the present invention can completely purify the water quality in eutrophic water with excessive total phosphorus, and use a dephosphorizing agent with high iron content to purify the inferior Class V water of surface lakes to Class III water of surface lakes according to national standards. (2) The composite dephosphorizing agent of the present invention can completely purify the water quality in eutrophic water with excessive total phosphorus, and can be kept in closed water bodies for a long time. It has been stored for more than 90 days.
[0074] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A composite dephosphorizing agent, characterized in that, By mass fraction, it includes the following components: Polyaluminum chloride 10-75%, attapulgite 15-89%, and attapulgite@graphene oxide@active metal ion composite material 1-10%; The attapulgite@graphene oxide@active metal ion composite material includes attapulgite clay modified with active metal ions and graphene oxide loaded on the attapulgite clay modified with active metal ions. The active metal ions in the modified attapulgite include ferric ions or ferrous ions.
2. The composite dephosphorizing agent according to claim 1, characterized in that, The mass fraction of graphene oxide in the attapulgite@graphene oxide@active metal ion composite material is 0.1~10%.
3. The composite dephosphorizing agent according to claim 1, characterized in that, The preparation method of the attapulgite@graphene oxide@active metal ion composite material includes the following steps: (1) Mix attapulgite clay with water to obtain a slurry; (2) The ferric salt or ferrous salt is mixed with the slurry to modify it, thereby obtaining a system containing modified attapulgite. (3) The system containing modified attapulgite is mixed with the dispersion of graphene oxide and then dried to obtain the attapulgite@graphene oxide@active metal ion composite material.
4. The composite dephosphorizing agent according to claim 3, characterized in that, The mass fraction of attapulgite in the slurry is 5-40%; the particle size of the attapulgite is 320-500 mesh.
5. The composite dephosphorizing agent according to claim 3, characterized in that, The anions in the ferric and ferrous salts include chloride ions and / or sulfate ions.
6. The composite dephosphorizing agent according to claim 3, characterized in that, Based on the iron ions in the iron salt or the ferrous ions in the ferrous salt, the mass ratio of the iron salt or ferrous salt to the attapulgite in step (1) is 1~5:
100.
7. The composite dephosphorizing agent according to claim 3, characterized in that, The volume ratio of the system containing modified attapulgite to the dispersion of graphene oxide is 1:0.2~20.
8. The composite dephosphorizing agent according to claim 3, characterized in that, The drying process includes vacuum spray drying, wherein the vacuum degree of the vacuum spray drying is not higher than 20 Pa, the temperature is not higher than 100℃, and the time is 30~240 min.
9. The method of using the composite dephosphorizing agent according to any one of claims 1 to 8, characterized in that, Includes the following steps: The composite dephosphorizing agent according to any one of claims 1 to 8 is added to phosphorus-containing wastewater.
10. The method of use according to claim 9, characterized in that, The pH value of the phosphorus-containing wastewater is 6-9.