A method for efficient phosphorus removal from phosphorus-containing wastewater

Abstract

This invention discloses a highly efficient phosphorus removal method for phosphorus-containing wastewater. It addresses the technical problems of high operating and maintenance costs, complex operation, and byproduct generation associated with existing electrocoagulation and magnetic coagulation phosphorus removal methods. The method utilizes acid-modified sponge iron and steel slag as the upper layer of a percolation bed, with quartz sand as the lower layer, to construct a continuous flow phosphorus removal percolation bed. A mixture of reduced iron powder, activated carbon, and standard sand is then used as packing material to fill the PRB adsorption wall, forming a dynamic PRB adsorption wall. The phosphorus-containing wastewater is pumped to the top inlet of the phosphorus removal percolation bed using a peristaltic pump. The effluent from the bottom of the percolation bed is then pumped upflow into the bottom inlet of the dynamic PRB adsorption column using another peristaltic pump. The hydraulic retention time (HRT) is controlled at 1–1.5 hours to complete the treatment of the phosphorus-containing wastewater. This method achieves a total phosphorus removal rate of 100%–75% in the treated effluent within 42 days and can be used for phosphorus-containing wastewater treatment in phosphate mining areas.

Description

Technical Field

[0001] This invention relates to a method for treating phosphorus-containing wastewater. Background Technology

[0002] In areas with phosphate mining, phosphate chemical, and phosphogypsum enterprises, rainwater runoff carries phosphorus and other pollutants, causing particularly severe pollution to surface and groundwater. Phosphate mine and phosphogypsum storage facilities release large amounts of phosphorus, fluorine, and other elements into nearby water systems through rainwater runoff, mine water inflow, and leaching, leading to serious non-point source pollution. To address these issues, current rainwater runoff pollution control measures in phosphate-producing areas mainly employ strategies such as rainwater storage tanks combined with specially designed phosphorus adsorption materials. However, the construction of storage tanks is limited by the size of urban land parcels, and their centralized collection capacity is also limited.

[0003] Currently, phosphorus removal in wastewater from phosphate mining areas is mainly achieved through electrocoagulation and magnetic coagulation technologies. While these technologies are highly effective, they have the following drawbacks and limitations:

[0004] First, the operating costs are high. Electrocoagulation and magnetic coagulation equipment and operations are expensive, requiring specialized equipment such as electrolytic cells, electrodes and power supplies, or magnetic field generators and magnetic poles, which significantly increases the costs of equipment purchase, daily maintenance and energy consumption.

[0005] Secondly, there are issues with electrical energy and electrode contamination. In electrocoagulation, the electrodes may become contaminated due to the deposition of substances in the water, leading to reduced efficiency and maintenance difficulties. Hydrogen gas may also be generated during electrolysis, requiring treatment to prevent safety issues.

[0006] Third, the operation and control of electrocoagulation and magnetic coagulation are relatively complex, requiring precise parameter control and monitoring. For example, electrocoagulation requires adjusting parameters such as current density, electrode spacing, and electrolysis time, while magnetic coagulation requires controlling the strength and direction of the magnetic field to achieve the best results.

[0007] Fourth, the applicability of electrocoagulation and magnetic coagulation is limited by water quality characteristics. The salinity, particulate matter, and organic matter content of the water may affect the effectiveness of electrocoagulation and magnetic coagulation. In particular, these technologies are less efficient for water bodies with high turbidity and high organic matter content.

[0008] Fifth, electrocoagulation and magnetic coagulation processes generate some byproducts, such as precipitates or gases. These byproducts need to be properly treated to reduce environmental impact and resource waste. Summary of the Invention

[0009] This invention aims to address the technical problems of high operating and maintenance costs, complex operation, and byproduct generation in existing electrocoagulation and magnetic coagulation phosphorus removal methods, and provides a highly efficient phosphorus removal method for phosphorus-containing wastewater. This method replaces electrocoagulation and magnetic coagulation technologies with a highly efficient infiltration coupled with an iron-based permeable reactive barrier system. This avoids the purchase of electromagnetic equipment, pollution and byproducts generated by electrical electrodes, reduces system operation and maintenance difficulty, saves costs, solves the problem of limited water quality characteristics, enhances the system's ecological benefits, combines phosphorus pollution control with ecological restoration, and improves the recycling of water resources.

[0010] The method for efficient phosphorus removal from phosphorus-containing wastewater according to the present invention comprises the following steps:

[0011] I. Preparation of percolation bed packing material: The dried sponge iron is soaked in a dilute H2SO4 solution with a mass percentage concentration of 5% to 6% and stirred to remove surface oxides. Then the sponge iron is taken out and rinsed with deionized water until the pH of the washing solution is neutral. After drying, acid-modified sponge iron is obtained.

[0012] II. Construction of a continuous flow dephosphorization percolation bed: Use 15-20cm thick quartz sand as the lower layer of the percolation bed, and then use a mixture of acid-modified sponge iron and steel slag at a volume ratio of 1:(1-1.2) as the upper layer of the percolation bed to obtain a continuous flow dephosphorization percolation bed.

[0013] III. Preparation of PRB Adsorption Wall Filler: Reduced iron powder with an average particle size of 40-50 μm and activated carbon were mixed evenly at a mass ratio of (1.7-2.3):1 and placed in a planetary ball mill. High-purity argon gas was introduced into the mill to prevent oxidation of the reduced iron powder. The mixture was ball-milled for 8-10 hours at a speed of 300-500 r / min. After ball milling, a mixed powder was obtained. The mixed powder was washed with ethanol to improve the hydrophilicity of the material. Then, it was immersed in a dilute HNO3 solution and stirred to expose the active sites and oxidize some of the zero-valent iron. After acid treatment, the material was washed with pure water until neutral and then vacuum dried to obtain a mixed material of reduced iron powder and activated carbon.

[0014] IV. Construction of dynamic PRB adsorption wall: Mix reduced iron powder and activated carbon with standard sand at a mass ratio of 1:(5~6) and fill the PRB adsorption wall with the mixture as filler to obtain dynamic PRB adsorption wall.

[0015] V. Phosphorus Removal System Operation: Phosphorus-containing wastewater is transported to the top inlet of the phosphorus removal percolation bed via a peristaltic pump. Then, the effluent from the bottom of the percolation bed is pumped into the bottom inlet of the dynamic PRB adsorption wall in an upflow manner using a peristaltic pump. The hydraulic retention time (HRT) is controlled to be 1–1.5 h to complete the treatment of phosphorus-containing wastewater.

[0016] Furthermore, the stirring described in step one shall be carried out for 20 to 30 minutes.

[0017] Furthermore, the thickness of the upper layer in the continuous flow phosphorus removal percolation bed described in step two is 65–70 cm.

[0018] Furthermore, in step three, the mass percentage concentration of the dilute HNO3 solution used to soak the mixed powder is 4%–5%, and the stirring time is 30–40 minutes.

[0019] Furthermore, the average diameter of the standard sand described in step four is 2–3 mm.

[0020] Furthermore, the packing height of the packing material in the PRB adsorption column described in step four is 80–100 cm.

[0021] Furthermore, to prevent filler loss as described in step four, standard sand is filled above and below the filler of the PRB adsorption wall, with a filling thickness of 5-10 cm.

[0022] Furthermore, the temperature of the phosphorus-containing wastewater described in step five is 20–30°C.

[0023] The phosphorus removal principle of this invention: Sponge iron, also known as direct reduced iron oxide, has a loose and porous surface. Its main component is elemental iron, and it also contains substances such as Fe3C, Fe3O4, Fe2O3, and Fe2CO3. The iron or ferrous ions precipitated from the corrosion of elemental iron react with phosphates to form insoluble iron salts, namely ferric phosphate or ferrous phosphate. Simultaneously, the sponge iron oxidizes in the air, forming iron oxides and hydroxyl oxides on its surface. These react with phosphate ions through ion exchange, complexation precipitation, and electrostatic adsorption, removing phosphorus from the water. Acid modification removes the aged passivation layer on the surface of the sponge iron, forming Fe ions with stronger phosphate adsorption activity, iron oxides with lower crystallinity, and iron hydroxides. Steel slag is an industrial waste with low cost. Because it contains a certain amount of Ca, Mg, Fe, and other elements, it also has good phosphorus adsorption performance. By using acid-modified sponge iron and steel slag as percolation bed packing, the steel slag surface is very rough, with small adsorption pore size, large specific surface area, and large pore volume. Not only does it possess high phosphorus adsorption efficiency, but its large specific surface area and pore volume also help improve the air permeability and water flow permeability of the packing. When steel slag is mixed with acid-modified sponge iron, these properties of the steel slag can effectively reduce the adhesion and aggregation between sponge iron particles, thus effectively alleviating the caking problem during the operation of the sponge iron infiltration bed.

[0024] Zero-valent iron (ZVFe) possesses excellent reducing properties and efficient adsorption capacity, enabling it to reduce phosphate ions in water to insoluble phosphate salt precipitates or adsorb onto its surface. Activated carbon provides a large surface area and abundant pore structure, enhancing phosphorus adsorption capacity and the stability of the packing material. This composite material utilizes the synergistic effect of ZVFe and activated carbon to effectively remove phosphorus pollutants from water while maintaining the long-term stability and high efficiency of the packing material.

[0025] After treatment by the ecological infiltration phosphorus removal unit with adsorption and interception as its core, the phosphorus content in the wastewater is greatly reduced, but a small amount of phosphorus remains. The effluent from the infiltration bed is then pumped into the PRB adsorption column for secondary treatment, achieving efficient, stable and continuous removal of low-concentration phosphorus at the end of the system.

[0026] The method of the present invention has the following advantages:

[0027] First, the high-efficiency infiltration system uses mixed packing material to absorb or degrade organic matter and remove phosphorus, which has low energy consumption and chemical reagent use, has little environmental impact, low cost, and meets the requirements of sustainable development.

[0028] Secondly, it avoids the frequent parameter adjustments and monitoring required in electrocoagulation and magnetic coagulation. Once stable, the high-efficiency percolation coupled with an iron-based percolation reactive barrier system can maintain high phosphorus removal capacity for a long period, achieving a total phosphorus removal rate of 100%–75% in the treated effluent within 42 days. It has lower requirements for system operation and maintenance, making it suitable for long-term operation and large-scale applications. Furthermore, unlike electrocoagulation and magnetic coagulation, which are limited by water quality characteristics, the high-efficiency percolation coupled with an iron-based percolation reactive barrier system can be adjusted and optimized according to different water quality characteristics, adapting to different wastewater sources and treatment requirements, thus exhibiting high applicability.

[0029] The high-efficiency percolation coupled iron-based percolation reaction wall system of this invention combines the adsorption of mixed packing materials and the iron-based percolation reaction mechanism, effectively removing phosphorus from water, especially showing good treatment effect for recalcitrant organic phosphorus forms, achieving multi-stage high-efficiency phosphorus removal. The method of this invention can be applied to the treatment of phosphorus-containing wastewater in phosphate mining areas. Attached Figure Description

[0030] Figure 1 This is the curve showing the relationship between the total phosphorus removal rate and the reaction time in Example 1.

[0031] Figure 2 This is the curve showing the relationship between the total phosphorus removal rate and reaction time in Comparative Example 1.

[0032] Figure 3 This is the curve showing the relationship between the total phosphorus removal rate and the amount of magnetic seed added in Comparative Example 2.

[0033] Figure 4This is a comparison chart of the total phosphorus removal rates of Example 1 and Comparative Example 3, with reaction times ranging from 0 days to 42 days.

[0034] Figure 5 This is a comparison chart of the total phosphorus removal rates of Example 1 and Comparative Example 4, with reaction times ranging from 0 days to 42 days.

[0035] Figure 6 This is a comparison chart of the total phosphorus removal rates of Example 1 and Comparative Example 5, with reaction times ranging from 0 days to 42 days.

[0036] Figure 7 This is a comparison chart of the total phosphorus removal rates of Example 1 and Comparative Example 6, with reaction times ranging from 0 days to 42 days.

[0037] Figure 8 This is a comparison chart of the total phosphorus removal rates of Example 1 and Comparative Example 7, with reaction times ranging from 0 days to 42 days. Detailed Implementation

[0038] The beneficial effects of the present invention will be verified using the following examples.

[0039] Example 1: The method for efficient phosphorus removal from phosphorus-containing wastewater in phosphate mining areas in this example is carried out according to the following steps:

[0040] I. Preparation of percolation bed packing material: The dried sponge iron was soaked in a 6% (w / w) dilute H2SO4 solution and stirred for 30 min to remove surface oxides. Then the sponge iron was taken out and rinsed with deionized water until the pH of the washing solution was neutral. Then it was placed in an oven at 105℃ and dried for 10 h to obtain acid-modified sponge iron.

[0041] II. Construction of a continuous flow phosphorus removal percolation bed: The phosphorus removal percolation bed is constructed using plexiglass columns with an inner diameter of 10cm and a height of 100cm. A 15cm thick layer of quartz sand is used as the lower layer of the percolation bed. A mixture of acid-modified sponge iron and steel slag in a volume ratio of 1:1 is used as the upper layer of the percolation bed, with a thickness of 65cm, resulting in a continuous flow phosphorus removal percolation bed with an effective volume of 4.0L.

[0042] III. Preparation of PRB Adsorption Column Packing Material: Reduced iron powder with an average particle size of 45 μm and activated carbon were mixed evenly at a mass ratio of 2:1 and placed in a planetary ball mill. High-purity argon gas was introduced into the mill to prevent oxidation of the reduced iron powder. The mixture was ball-milled for 8 hours at a speed of 375 r / min. After ball milling, a mixed powder was obtained. The mixed powder was washed with ethanol to improve the hydrophilicity of the material. Then, it was immersed in a 5% HNO3 solution and stirred for 40 minutes to expose the active sites and oxidize some of the zero-valent iron. After acid treatment, the material was washed with pure water until neutral and then placed in a vacuum drying oven at 60℃ for 2 hours to obtain a mixed material of reduced iron powder and activated carbon, denoted as ZVI-AC.

[0043] IV. Construction of a Dynamic PRB Adsorption Column: An acrylic glass column is used to simulate the PRB reaction wall. The acrylic glass column is 100cm high and has an inner diameter of 10cm. 680g of reduced iron powder and activated carbon mixture is mixed evenly with 3400g of standard sand with an average particle size of 2mm and then used as filler to fill the PRB adsorption column. The filling height of the filler is 80cm. Standard sand with a thickness of 5cm is filled above and below the filler to prevent filler loss, thus obtaining a dynamic PRB adsorption column. This PRB adsorption column can maintain good hydraulic conditions of the system and effectively prevent the occurrence of system blockage.

[0044] V. Phosphorus Removal System Operation: Simulated phosphorus-containing wastewater with a phosphorus content of 10 mg / L was prepared using KH₂PO₄. This simulated wastewater was pumped to the top inlet of the phosphorus removal percolation bed via a peristaltic pump. The effluent from the bottom of the percolation bed was then pumped upflow into the bottom inlet of the dynamic PRB adsorption column. The system was operated at 25°C, with a hydraulic retention time (HRT) of 1 hour to complete the treatment of the phosphorus-containing wastewater. Effluent was periodically collected from the upper sampling port of the PRB adsorption column and immediately analyzed after filtration through a 0.45 μm filter membrane. The total phosphorus removal rate changes from 0 days to 42 days as shown below. Figure 1 As shown.

[0045] Comparative Example 1: This comparative example uses electrocoagulation to treat simulated phosphorus-containing wastewater. The steps are as follows:

[0046] The electrodes were fixed in place using an electrode holder and placed on a 1L beaker. Each electrode had a contact area of ​​10cm × 8cm with the solution, and the electrode spacing was 1.0cm. To simulate the phosphorus removal performance of a high-phosphorus-concentration infiltration filter in nature, this comparative example used a high influent phosphorus load. Simulated phosphorus-containing wastewater with a phosphorus content of 10mg / L was prepared by adding KH₂PO₄ to tap water. 500mL of this simulated phosphorus-containing wastewater was added to the beaker at once, and the solution was thoroughly mixed using a magnetic stirrer. The mixture was then subjected to a temperature of 25℃, an electrode spacing of 1.0cm, a pH of 6.70, and a current density of 4.01mA / cm².2 Under the conditions of power-on operation for phosphorus removal; the change in total phosphorus removal rate as the reaction time is extended from 5 min to 40 min is as follows: Figure 2 As shown.

[0047] Comparative Example 2: This comparative example uses magnetic coagulation to treat simulated phosphorus-containing wastewater. The steps are as follows:

[0048] To simulate the phosphorus removal performance of a high-phosphorus-concentration infiltration filter bed in nature, this experiment employed a relatively high influent phosphorus load. Simulated phosphorus-containing wastewater with a phosphorus concentration of 10 mg / L was prepared by adding KH₂PO₄ to tap water. The solution was kept at 25℃. 500 ml of the prepared simulated phosphorus-containing wastewater was added to a 1 L beaker and placed on a stirrer, then powered on and ready for operation. Polyaluminum chloride (PAC) with an alumina content of 30% was prepared as a 2 g / L solution for later use. Anionic polyacrylamide (PAM) with a relative molecular mass of 300 × 10⁻⁶ was used. 4 Prepare a 0.1 g / L solution for later use; prepare industrial grade Fe3O4 magnetic seeds with a particle size of 48 μm;

[0049] The coagulation was carried out using a six-unit mixer at room temperature. First, magnetic seed and PAC (60 mg / L) were added, and the mixture was rapidly stirred at 300 rpm for 1 min. Then, PAM (1 mg / L) was added, and the mixture was stirred at a medium speed of 120 rpm for 3 min. Finally, the mixture was stirred slowly at 60 rpm for 5 min. After coagulation, the mixture was allowed to settle for 5 min, and the supernatant was collected 2 cm below the surface for water quality analysis. The change in total phosphorus removal rate as the magnetic seed dosage increased from 0 g / L to 5 g / L is shown in the figure. Figure 3 As shown.

[0050] Compared with Comparative Examples 1 and 2, Example 1 has less dependence on electricity. Electrocoagulation and magnetic coagulation require a large amount of electricity to maintain system operation, while the high-efficiency infiltration coupled iron-based infiltration reactive wall system only needs to increase the power consumption of the pump. At the same time, it avoids the large-scale use of chemical agents such as PAM and PAC in magnetic coagulation, reducing the environmental impact and operating costs.

[0051] In Comparative Example 1, it is necessary to monitor the current density, electrode spacing, and electrolysis time at all times, and strictly control the electrode spacing and losses. In Comparative Example 2, it is necessary to monitor the stirring rate and chemical consumption at all times, and frequently adjust the stirring time and rate. However, Example 1 only requires adjusting the packing ratio, without too many complicated operations, and can maintain a high phosphorus removal capacity for a long time after stable operation, solving the problems of complex system operation and high maintenance difficulty.

[0052] Comparative Examples 1 and 2 are limited by a large number of parameters and are only suitable for treating phosphorus-containing wastewater with a single water quality characteristic. In contrast, Example 1 has lower requirements for wastewater source and water quality characteristics and can be adjusted and optimized according to different water quality characteristics, making it more adaptable.

[0053] Comparative Examples 1 and 2 both involved single-stage treatment, achieving a total phosphorus removal rate of approximately 70% in the treated effluent, but they could not guarantee stable compliance with standards. In contrast, Example 1 utilized both biodegradation and iron-based osmosis to achieve multi-stage, highly efficient phosphorus removal, achieving a total phosphorus removal rate of 100%–75% in the treated effluent within 42 days. Furthermore, the multiple treatment processes ensured stable compliance with standards for the treated effluent.

[0054] Comparative Example 3: This comparative example differs from Example 1 in that the operation in step two is replaced by the following operation:

[0055] 2. A phosphorus removal percolation bed was constructed using an organic glass column with an inner diameter of 10 cm and a height of 100 cm. A 15 cm thick layer of quartz sand was used as the lower layer of the percolation bed. A mixture of acid-modified sponge iron and steel slag in a volume ratio of 1:2 was used as the upper layer of the percolation bed with a thickness of 65 cm, resulting in a continuous flow phosphorus removal percolation bed with an effective volume of 4.0 L.

[0056] The other steps and parameters are the same as in Example 1.

[0057] The total phosphorus removal rate of the treated effluent in Comparative Example 3 was worse than that in Example 1 over 42 days. The total phosphorus removal rate was 83.12% on the first day, but decreased to 63.49% on the 42nd day as the operating time increased. The reduced iron content of the acid-modified sponge, which played a major adsorption role, significantly reduced the total phosphorus removal rate. A comparison of the total phosphorus removal rates of Example 1 and Comparative Example 3 from 0 days to 42 days is provided. Figure 4 As shown.

[0058] Comparative Example 4: This comparative example differs from Example 1 in that the operation in step two is replaced by the following operation:

[0059] 2. A phosphorus removal percolation bed was constructed using an organic glass column with an inner diameter of 10 cm and a height of 100 cm. A 15 cm thick layer of quartz sand was used as the lower layer of the percolation bed. A mixture of acid-modified sponge iron and steel slag at a volume ratio of 1:0.5 was used as the upper layer of the percolation bed, with a thickness of 65 cm, resulting in a continuous flow phosphorus removal percolation bed with an effective volume of 4.0 L.

[0060] The other steps and parameters are the same as in Example 1.

[0061] The total phosphorus removal rate of the treated effluent in Comparative Example 4 was worse than that in Example 1 over 42 days. The total phosphorus removal rate was 85.33% on the first day, but dropped to 65.87% on the 42nd day as the operating time increased. The reduced steel slag content and the caking problem of the acid-modified sponge iron affected the phosphorus removal effect, resulting in a significant decrease in the total phosphorus removal rate of the effluent.

[0062] A comparison of the total phosphorus removal rates in Example 1 and Comparative Example 4, with reaction times ranging from 0 days to 42 days. Figure 5 As shown.

[0063] Comparative Example 5: This comparative example differs from Example 1 in that the operation in step two is replaced by the following operation:

[0064] 2. An organic glass column was used to construct a phosphorus removal percolation bed with an inner diameter of 10 cm and a height of 100 cm. A 15 cm thick layer of quartz sand was used as the lower layer of the percolation bed. A mixture of sponge iron and steel slag in a volume ratio of 1:1 was used as the upper layer of the percolation bed. The thickness of the upper layer of the packing was 65 cm, resulting in a continuous flow phosphorus removal percolation bed with an effective volume of 4.0 L.

[0065] The other steps and parameters are the same as in Example 1.

[0066] The total phosphorus removal rate of the treated effluent in Comparative Example 5 was worse than that in Example 1 over 42 days. The total phosphorus removal rate was 82.12% on the first day, but decreased to 59.25% on the 42nd day as the operating time increased. An aged passivation layer forms on the surface of the unmodified sponge iron, reducing the content of Fe ions (for phosphate adsorption), iron oxides (with lower crystallinity), and iron hydroxides, thus affecting the phosphorus removal effect and significantly decreasing the total phosphorus removal rate. A comparison of the total phosphorus removal rates of Example 1 and Comparative Example 5 from 0 days to 42 days is provided. Figure 6 As shown.

[0067] Comparative Example 6: This comparative example differs from Example 1 in that the reduced iron powder with an average particle size of 40-50 μm and activated carbon in step three are in a mass ratio of 3:1. The other steps and parameters are the same as in Example 1.

[0068] In Comparative Example 6, excessive reduced iron powder content reduces the pore structure of the composite material and decreases the adsorption capacity of the activated carbon. A high proportion of reduced iron powder also leads to iron ion dissolution, generating ferric phosphate precipitates that clog pores and reduce material permeability. Accumulated precipitates can clog the percolation filter media, hindering water flow and affecting the normal operation and long-term stability of the system, thus reducing overall treatment efficiency. A comparison of the total phosphorus removal rates in Example 1 and Comparative Example 6 from 0 days to 42 days is provided. Figure 7 As shown.

[0069] Comparative Example 7: This comparative example differs from Example 1 in that the reduced iron powder with an average particle size of 40-50 μm and activated carbon in step three are in a mass ratio of 1:1. The other steps and parameters are the same as in Example 1.

[0070] In Comparative Example 7, insufficient reduced iron powder content in the composite material leads to decreased reduction performance and affects the effective reduction of phosphate ions. It also reduces the composite material's adsorption capacity for phosphate ions, lowering phosphorus removal efficiency. Furthermore, a high activated carbon content may alter the material's mechanical strength, affecting the packing's structural stability and service life. A comparison of the total phosphorus removal rates in Example 1 and Comparative Example 7, with reaction times ranging from 0 days to 42 days, is provided. Figure 8 As shown.

Claims

1. A method for efficient phosphorus removal from phosphorus-containing wastewater, characterized in that... This method is performed in the following steps: I. Preparation of percolation bed packing material: The dried sponge iron was soaked in a dilute H2SO4 solution with a mass percentage concentration of 5%~6% and stirred to remove surface oxides. Then the sponge iron was taken out and rinsed with deionized water until the pH of the washing solution was neutral. After drying, acid-modified sponge iron was obtained. II. Construction of a continuous flow dephosphorization percolation bed: Use 15-20cm thick quartz sand as the lower layer of the percolation bed, and then use a mixture of acid-modified sponge iron and steel slag at a volume ratio of 1:(1-1.2) as the upper layer of the percolation bed to obtain a continuous flow dephosphorization percolation bed. III. Preparation of PRB Adsorption Wall Filler: Reduced iron powder with an average particle size of 40~50μm and activated carbon were mixed evenly at a mass ratio of (1.7~2.3):1 and placed in a planetary ball mill. High-purity argon gas was introduced into the mill to prevent oxidation of the reduced iron powder. The mixture was ball-milled for 8~10 hours at a speed of 300~500 r / min. After ball milling, a mixed powder was obtained. The mixed powder was washed with ethanol to improve the hydrophilicity of the material. Then it was immersed in dilute HNO3 solution and stirred to expose the active sites and oxidize some of the zero-valent iron. After acid treatment, the material was washed with pure water until neutral and then vacuum dried to obtain a mixed material of reduced iron powder and activated carbon. The mass percentage concentration of the dilute HNO3 solution used to soak the mixed powder is 4%~5%, and the stirring time is 30~40 min; IV. Construction of dynamic PRB adsorption wall: Mix reduced iron powder and activated carbon with standard sand at a mass ratio of 1: (5~6) and fill the PRB adsorption wall with the mixture as filler to obtain dynamic PRB adsorption wall. V. Phosphorus Removal System Operation: Phosphorus-containing wastewater is transported to the top inlet of the phosphorus removal percolation bed via a peristaltic pump. Then, the effluent from the bottom of the percolation bed is pumped into the bottom inlet of the dynamic PRB adsorption wall in an upflow manner using a peristaltic pump. The hydraulic retention time (HRT) is controlled to be 1~1.5h to complete the treatment of phosphorus-containing wastewater.

2. The method for efficient phosphorus removal from phosphorus-containing wastewater according to claim 1, characterized in that, The stirring described in step one shall be carried out for 20 to 30 minutes.

3. A method for efficient phosphorus removal from phosphorus-containing wastewater according to claim 1 or 2, characterized in that, The thickness of the upper layer in the continuous flow phosphorus removal percolation bed described in step two is 65~70cm.

4. A method for efficient phosphorus removal from phosphorus-containing wastewater according to claim 1 or 2, characterized in that, The average diameter of the standard sand mentioned in step four is 2~3mm.

5. A method for efficient phosphorus removal from phosphorus-containing wastewater according to claim 1 or 2, characterized in that, The filling height of the packing material in the PRB adsorption wall described in step four is 80~100cm.

6. A method for efficient phosphorus removal from phosphorus-containing wastewater according to claim 1 or 2, characterized in that, The temperature of the phosphorus-containing wastewater mentioned in step five is 20~30℃.

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