A phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant, and its preparation method and application

Abstract

A phosphorus removal adsorbent based on the nitrogen-doped aluminum sludge from a water plant, as well as its preparation method and application, belongs to the field of solid waste resource technology. The specific steps are as follows: the aluminum sludge from the water plant after dehydration is dried and cooled, then ground into powder, and sieved to obtain the aluminum sludge powder from the water plant; melamine and the aluminum sludge powder are mixed, deionized water is added to obtain a solid-liquid mixture, and ultrasonically mixed; the solid-liquid mixture is thermally dried after ultrasonication, and then wrapped with tin foil for co-pyrolysis, and then ground and sieved to obtain a phosphorus removal adsorbent based on the nitrogen-doped aluminum sludge from the water plant. The present invention significantly improves the removal effect of phosphorus-containing wastewater and can be used for deep phosphorus removal of sewage plant tail water. At the same time, the resource utilization of aluminum sludge from the water plant can save sludge disposal costs and can be used to solve the increasingly serious problems of sludge resource outlet difficulties and excessive phosphorus in sewage plant tail water.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant, and a preparation method and application thereof. Background Art

[0002] As my country's urbanization process accelerates, the number of water plants continues to increase, and the amount of aluminum sludge generated by water plants is growing exponentially. Large amounts of aluminum sludge are simply treated and discharged into the natural environment, causing serious aluminum pollution problems. How to resource-treat the rapidly growing aluminum sludge from water plants is an urgent environmental issue. Unlike the sludge produced by sewage treatment plants, aluminum sludge from water plants has a simple composition, less harmful effects, and potential commercial value. It is a resource that can be fully recycled. However, the resource utilization of aluminum sludge from water plants is not common at home and abroad. Most existing disposal methods include dehydration, landfilling, ocean dumping, coagulant regeneration, land utilization, and building material utilization. However, these methods generally have problems such as high cost, land occupation, secondary pollution, and low economic efficiency. Therefore, it is urgent to find a disposal method that has less environmental harm and can resource-reuse aluminum sludge from water plants.

[0003] Conventional water treatment plants generally utilize coagulation processes. New coagulants such as polyaluminium chloride have gradually replaced aluminum sulfate and ferric chloride. Large amounts of aluminum ions ultimately deposit in the water treatment plant's aluminum sludge, giving it a strong adsorption capacity for phosphorus. The amorphous aluminum ions in the sludge can adsorb phosphorus from wastewater, exchanging ligand ions and solidifying soluble phosphorus in the wastewater. Therefore, utilizing aluminum sludge from water treatment plants as a resource for phosphorus removal is a theoretically feasible method. Currently, phosphorus concentrations in wastewater treatment plant tailwater are high. For example, the phosphorus content of direct effluent from secondary sedimentation tanks ranges from approximately 0.7 to 5.4 mg / L. While the total phosphorus (TP) standard for wastewater treatment plants in some regions has been raised from the national Class A standard (0.50 mg / L) to the new local standard (0.30 mg / L), phosphorus concentrations in tailwater still fall short of these standards. Therefore, direct discharge of tailwater is a major contributor to excessive phosphorus levels in the aquatic environment. In order to further reduce the phosphorus content in tail water and control the eutrophication problem of the water environment, the resource utilization of aluminum sludge from water plants is a good research direction, and it also provides a research idea for deep phosphorus removal in water plant tail water.

[0004] In the field of adsorption of aluminum sludge doped with carbon nitride in water plants, an oxidation-adsorption system is often used. This involves oxidizing the valence state of the substance with lower aluminum sludge adsorption to a valence state with higher aluminum sludge adsorption capacity, thereby leveraging the catalytic oxidation ability of carbon nitride and the adsorption capacity of aluminum sludge. Therefore, it is feasible to develop a method for preparing a nitrogen-doped powder material for water plant aluminum sludge to remove phosphorus from water. Modification of aluminum sludge can also save sludge treatment costs, reduce environmental pollution, and achieve resource utilization, harmlessness, and reduction of aluminum sludge. This is of great significance for conserving water resources, improving the ecological environment, and promoting the sustainable development of solid waste disposal. Summary of the Invention

[0005] Technical problems to be solved: In view of the problems of resource disposal of aluminum sludge from water plants and deep treatment of phosphorus in tail water of sewage plants in the existing technology, the present invention provides a phosphorus removal adsorbent based on nitrogen-doped modified aluminum sludge from water plants, as well as a preparation method and application thereof, which can save sludge treatment costs and reduce environmental pollution. The modified aluminum sludge can be used for deep phosphorus removal in tail water of sewage treatment plants, generating economic benefits, thereby realizing the resource utilization, harmlessness and reduction of aluminum sludge from water plants.

[0006] Technical solution: A method for preparing a phosphorus removal adsorbent based on the nitrogen-doped aluminum sludge from a water supply plant, the steps are as follows:

[0007] Step 1. The aluminum content of 6-8 wt% of the water plant aluminum sludge is dried, naturally cooled and ground into a powder, and sieved to obtain the water plant aluminum sludge powder;

[0008] Step 2. Mix the melamine and aluminum sludge powders, add deionized water to obtain a solid-liquid mixture, and mix by ultrasonic mixing;

[0009] Step 3. After ultrasonication, the solid-liquid mixture is thermally dried, and then the dried material is wrapped with tin foil, and the tin foil is evenly perforated to allow the material to be co-pyrolyzed. After cooling, the material is ground and sieved.

[0010] Preferably, in step 1, the aluminum sludge from the water supply plant with an aluminum content of 6-8 wt% comes from a water supply plant using aluminum salts (such as aluminum sulfate, polyaluminum sulfate, aluminum chloride, polyaluminum chloride, etc.) as coagulants, has a moisture content of 50%-60%, and after drying, has a moisture content of less than 10%.

[0011] Preferably, in step 1, the drying conditions are as follows: drying in a blast dryer at a drying temperature of 105° C.; and passing the powder through a 100-mesh sieve.

[0012] Preferably, in the step 2, the mass ratio of melamine to aluminum sludge powder is (0.2-1):1, and the ratio of aluminum sludge powder to deionized water is 10 g:100 mL.

[0013] Preferably, in step 2, the ultrasonic mixing conditions are: constant temperature ultrasonic treatment at 25-30° C. for 20-40 min, ultrasonic frequency of 40 KHZ, and ultrasonic input power of 300 W.

[0014] Preferably, in step 3, the thermal drying conditions are: drying at 105° C. for 24 to 36 hours; the co-pyrolysis conditions are: pyrolysis at 400 to 600° C. for 3 to 5 hours; and after cooling, grinding through a 100-mesh sieve.

[0015] The above-mentioned method for preparing a phosphorus removal adsorbent based on the modification of aluminum sludge doped with nitrogen from a water supply plant is used to prepare a phosphorus removal adsorbent based on the modification of aluminum sludge doped with nitrogen from a water supply plant.

[0016] Based on the above-mentioned application of a phosphorus removal adsorbent based on the nitrogen-doped modified aluminum sludge from a water plant in removing phosphorus from sewage.

[0017] Preferably, the specific steps are as follows: adding the water plant aluminum sludge nitrogen-modified phosphorus removal adsorbent to the phosphorus-containing wastewater to be treated, adjusting the wastewater pH to 6.0-9.0, and reacting for 1-7 days.

[0018] Preferably, the phosphorus-containing wastewater to be treated is water plant tail water, and the added concentration of the phosphorus removal adsorbent is 1-5 g / L.

[0019] Beneficial effects:

[0020] (1) Nitrogen-doped modified aluminum sludge has a better phosphorus removal effect than unmodified aluminum sludge. The nitrogen-doped modified aluminum sludge obtained by the method of the present invention has an aluminum content of 11 wt%. Compared with the unmodified aluminum sludge with an aluminum content of 6 wt% in the present invention, under the same reaction time conditions, the phosphorus adsorption capacity of the modified aluminum sludge is significantly improved; compared with the unmodified aluminum sludge with an aluminum content of 7.6 wt% in the paper "Study on the Adsorption and Removal of Phosphorus in Water by Dehydrated Aluminum Sludge in Waterworks" (China Water and Wastewater. 2011, 27(23)), the phosphorus adsorption capacity of the modified sludge of the present invention is 0.4575 mg / g, which is much greater than the adsorption capacity of 0.0995 mg / g of the unmodified aluminum sludge in the paper, and the adsorption capacity is 4.6 times that of the unmodified aluminum sludge;

[0021] (2) Nitrogen-doped modified aluminum sludge has a higher phosphorus removal effect than the polyferric sulfate flocculant in the paper "Optimization Design of Iron Salt Coagulant Dosage in Deep Phosphorus Removal" (Industrial Water and Wastewater, 2015, 46(04)). When both coagulants are used for deep phosphorus removal, the phosphorus adsorption capacity of nitrogen-doped modified aluminum sludge is 0.4575 mg / g, while the phosphorus adsorption capacity of polyferric sulfate flocculant is 0.1096 mg / g. The modified aluminum sludge prepared by the present invention has a higher phosphorus adsorption capacity.

[0022] (3) Nitrogen-doped modified aluminum sludge can be used for deep treatment of phosphorus in wastewater plant tailwater. At pH 6.0, this material can reduce the phosphorus concentration in wastewater to 0.085 mg / L. Furthermore, within a wide operating range of pH 6.0-8.5, the residual phosphorus concentration can be kept below 0.5 mg / L, meeting the primary phosphate discharge standard of 0.5 mg / L in the Integrated Wastewater Discharge Standard.

[0023] (4) The preparation process of nitrogen-doped modified aluminum sludge powder from water plants is simple to operate and can be completed through simple steps such as drying, grinding, sieving, and mixing. It is easy to implement and more easily promoted and used;

[0024] (5) The modified phosphorus removal material prepared by the present invention is mainly made of aluminum sludge from water plants. It not only saves the cost of aluminum sludge treatment and reduces environmental pollution, but also the modified material can deeply remove phosphorus from the tail water of sewage plants, generate economic benefits, and realize the resource utilization, harmlessness and reduction of aluminum sludge, which has far-reaching significance for promoting the sustainable development of solid waste disposal. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a bar / line graph showing the relationship between the ratio of nitrogen-doped powder in aluminum sludge and the phosphorus concentration and removal rate in water in Example 1. Figure 1 In the figure, the bar graph shows the relationship between the residual phosphorus concentration in the wastewater and the doping ratio when the mass ratio of melamine to aluminum sludge in Example 1 is 0, 0.2, 0.4, 0.6, 0.8, and 1.0, respectively, the reaction time t=5 d, the initial phosphorus concentration C0=1 mg / L, the reaction temperature 30°C, the oscillation speed 120 rpm, the pH=6.0, and the sludge concentration 2 g / L; The figure shows the relationship between the doping ratio of melamine and aluminum sludge from a water supply plant and the phosphorus removal rate in Example 1.

[0026] Figure 2 This is a bar / line graph showing the relationship between the dosage of nitrogen-doped modified aluminum sludge and the phosphorus concentration and removal rate in the water body in Example 2. Figure 2 The bar graph shows the relationship between the residual phosphorus concentration in the wastewater and the dosage of the nitrogen-doped modified aluminum sludge in Example 2 under the following conditions: mass ratio m(melamine):m(water plant aluminum sludge powder) = 0.6, reaction time t = 5 d, initial phosphorus concentration C0 = 1 mg / L, reaction temperature 30°C, oscillation speed 120 rpm, and pH = 6.0. It shows the relationship between the dosage of nitrogen-doped modified aluminum sludge and the phosphorus removal rate in Example 2.

[0027] Figure 3The bar graph or line graph shows the relationship between the reaction time of the nitrogen-doped aluminum sludge and the phosphorus concentration and removal rate in the water body in Example 3. Figure 3 The middle bar graph shows the relationship between the residual phosphorus concentration in the wastewater and the reaction time when the reaction time of the nitrogen-doped modified aluminum sludge in Example 3 is 1, 2, 3, 4, 5, 6, and 7 days, respectively, with a mass ratio of m(melamine):m(aluminum sludge powder from the water supply plant) = 0.6, an initial phosphorus concentration C0 = 1 mg / L, a reaction temperature of 30°C, an oscillation speed of 120 rpm, a pH of 6.0, and a sludge concentration of 2 g / L; The figure shows the relationship between the reaction time of nitrogen-doped modified aluminum sludge and the phosphorus removal rate in Example 3.

[0028] Figure 4 This is a bar graph / broken line graph showing the relationship between different pH conditions of nitrogen-doped modified aluminum sludge and phosphorus concentration and removal rate in water. Figure 4 In the figure, the bar graph shows the relationship between the residual phosphorus concentration in water and the pH value when the dosage of the nitrogen-doped modified aluminum sludge in Example 4 is 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, and 9.0, the mass ratio m(melamine):m(aluminum sludge powder from the water supply plant) = 0.6, the reaction time t = 5 d, the initial phosphorus concentration C0 = 1 mg / L, the reaction temperature 30°C, the oscillation speed 120 rpm, and the sludge concentration 2 g / L. The figure shows the relationship between different pH conditions of nitrogen-doped modified aluminum sludge and phosphorus removal rate in Example 4.

[0029] Figure 5 This is the energy dispersive spectrum (EDS) diagram of the nitrogen-doped modified aluminum sludge from the water plant in Example 5.

[0030] Figure 6 This is a scanning electron microscope (SEM) image of the nitrogen-doped modified aluminum sludge from the water plant in Example 6 at a scale of 5 μm. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] The present invention provides a method for preparing a phosphorus removal adsorbent based on the nitrogen-doped modified aluminum sludge from a water supply plant, comprising the following steps:

[0033] Step 1. Dry the aluminum sludge from the water supply plant with an aluminum content of 6 to 8 wt%, grind it into a powder after natural cooling, and sieve the aluminum sludge powder from the water supply plant;

[0034] Step 2. Mix the melamine and aluminum sludge powders, add deionized water to obtain a solid-liquid mixture, and mix by ultrasonic mixing;

[0035] Step 3. After ultrasonication, the solid-liquid mixture is thermally dried, and then the dried material is wrapped with tin foil and evenly pierced with holes to allow the material to co-pyrolyze. After cooling, the material is ground and sieved.

[0036] The above-mentioned method for preparing a phosphorus removal adsorbent based on the nitrogen-doped modified aluminum sludge of a water supply plant is a phosphorus removal adsorbent modified by nitrogen doping of aluminum sludge from a water supply plant.

[0037] Based on the above-mentioned application of a phosphorus removal adsorbent based on the nitrogen-doped modified aluminum sludge from a water plant in removing phosphorus from sewage.

[0038] As one of the preferred solutions, the aluminum sludge from the water supply plant with an aluminum content of 6-8 wt% in the embodiments of this specification comes from a water supply plant using aluminum salt as a coagulant, has a moisture content of 50%-60%, and has a moisture content of less than 10% after drying.

[0039] As one of the preferred solutions, in step 1, the drying conditions are as follows: drying in a blast dryer at a drying temperature of 105° C.; and passing the powder through a 100-mesh sieve.

[0040] As one of the preferred solutions, in the step 2, the mass ratio of melamine to aluminum sludge powder is (0.2-1):1, and the ratio of aluminum sludge powder to deionized water is 10 g:100 mL.

[0041] As one of the preferred solutions, the conditions for ultrasonic mixing in step 2 are: constant temperature ultrasonic treatment at 25-30°C for 20-40 min, ultrasonic frequency of 40 KHZ, and ultrasonic input power of 300 W.

[0042] As one of the preferred solutions, the thermal drying conditions in step 3 are: drying at 105° C. for 24 to 36 hours; the co-pyrolysis conditions are: co-pyrolysis at 400-600° C. for 3 to 5 hours; and after cooling, grinding through a 100-mesh sieve.

[0043] As one preferred embodiment, the phosphorus removal adsorbent based on water plant aluminum sludge modified by nitrogen doping is used to remove phosphorus from wastewater. The specific steps are as follows: adding the phosphorus removal adsorbent based on water plant aluminum sludge modified by nitrogen doping to the phosphorus-containing wastewater to be treated, adjusting the wastewater pH to 6.0-9.0, and reacting for 1-7 days.

[0044] As one of the preferred solutions, the phosphorus-containing wastewater to be treated is water plant tail water, and the added concentration of the phosphorus removal adsorbent is 1-5 g / L.

[0045] Example 1: Effect of the ratio of nitrogen-doped powder in aluminum sludge on phosphorus removal in water

[0046] The aluminum sludge used in this material comes from the Nanjing Beihekou Water Plant. It is obtained by dewatering sludge from the inclined tube sedimentation tank and the balance tank. The sludge contains 6 wt% aluminum and no nitrogen.

[0047] The method of using nitrogen-doped modified aluminum sludge from water plants for deep phosphorus removal in water has the following specific steps:

[0048] 1) Aluminum sludge with an aluminum content of 6 wt% was placed in a blast dryer and dried at 105°C until the moisture content was less than 10%. After natural cooling, the sludge was ground into powder and passed through a 100-mesh sieve to obtain water plant aluminum sludge powder.

[0049] 2) Six portions of aluminum sludge powder (10 g each) were prepared. Melamine (2 g, 4 g, 6 g, 8 g, and 10 g) was then mixed with each portion of aluminum sludge at different mass ratios (mass ratios of 0, 0.2, 0.4, 0.6, 0.8, and 1, respectively). 100 mL of deionized water was added to each portion to form a solid-liquid mixture. The mixture was then ultrasonically treated in a beaker at 30°C for 30 min. The mixture was then dried in a dryer at 105°C for 24 h. A crucible was then wrapped in tinfoil and punctured uniformly. The mixture was then co-pyrolyzed at 550°C for 4 h. After cooling, the mixture was ground and sieved to obtain nitrogen-doped aluminum sludge powders with six different doping ratios.

[0050] 3) Pour 100 mL of KH2PO4 solution with a total phosphorus concentration of 1 mg / L into 6 conical flasks respectively, and add nitrogen-doped modified water plant aluminum sludge powder with a mass ratio of melamine to aluminum sludge of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 respectively to make the sludge concentration 2 g / L and adjust the sewage pH to 6.0.

[0051] 4) Shake the conical flask in a full-temperature oscillator at 30°C and 120 rpm. After a reaction time of t = 5 d, remove 10 mL of the supernatant and filter it through a 0.45 µm microfiltration membrane. Determine and calculate the total phosphorus content in the solution. Analyze the effect of nitrogen doping on the phosphorus removal efficiency of aluminum sludge from the water supply plant.

[0052] Changing the nitrogen doping ratio, the effect of different nitrogen doping ratios on the phosphorus concentration and removal rate of aluminum sludge materials in water is as follows: Figure 1 As shown in the figure, the phosphorus concentration after treatment first decreases and then increases with the doping ratio. For pure aluminum sludge, the removal efficiency is 68%. When the doping ratio is 0.6, the phosphorus concentration after treatment reaches 0.085 mg / L, and the removal efficiency is 91.5%, achieving the highest removal efficiency. The figure shows that doping and modification of aluminum sludge from water plants achieves better phosphorus removal.

[0053] Example 2: Effect of different dosages of nitrogen-doped aluminum sludge on phosphorus removal in water

[0054] The same as Example 1, except that, under the conditions of m(melamine):m(aluminum sludge powder from water supply plant)=0.6, initial phosphorus concentration C0=1 mg / L, sewage pH=6.0, reaction temperature 30°C, oscillation speed 120 rpm, and reaction time t=5 d, the addition amount of nitrogen-doped modified aluminum sludge from water supply plant (hereinafter referred to as modified aluminum sludge) was changed. The effects of the addition amount of different sludge materials (i.e., sludge concentrations of 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L, respectively) on the phosphorus concentration and removal rate in sewage are shown in the following table. Figure 2 shown.

[0055] The figure shows that as the dosage of nitrogen-doped aluminum sludge increases, phosphorus concentration gradually decreases and phosphorus removal rate in the water increases. When the dosage of modified aluminum sludge is 1 g / L, the phosphorus removal rate in the wastewater is as low as 83.5%. When the dosage is 4 g / L, the phosphorus removal rate reaches 89%, gradually stabilizing. When the dosage is 5 g / L, the phosphorus removal rate reaches a maximum of 92.5%. Residual phosphorus concentrations under all operating conditions are below 0.5 mg / L, indicating stable operation.

[0056] Example 3: Effect of nitrogen-doped aluminum sludge on phosphorus removal in water at different reaction times

[0057] The same as Example 1, except that, under the conditions of m(melamine):m(aluminum sludge powder from water supply plant)=0.6, initial phosphorus concentration C0=1 mg / L, sludge concentration 2 g / L, sewage pH=6.0, reaction temperature 30°C, and oscillation speed 120 rpm, the reaction time of the nitrogen-doped modified aluminum sludge from water supply plant and sewage was changed. The effects of the reaction time of different aluminum sludge materials on the phosphorus concentration and removal rate in water are shown in the figure. Figure 3 shown.

[0058] The figure shows that as the reaction time of the nitrogen-doped aluminum sludge from the water plant increases, the phosphorus concentration gradually decreases and the phosphorus removal rate in the water increases. After one day of reaction, the post-treatment phosphorus concentration reached 0.56 mg / L, and the phosphorus removal rate in the wastewater was the lowest, at 44%. After five days of reaction, the post-treatment phosphorus concentration reached 0.39 mg / L, and the removal rate stabilized at 61%. After seven days of reaction, the post-treatment phosphorus concentration reached 0.36 mg / L, and the phosphorus removal rate reached its highest point, at 64%. When the reaction time exceeded two days, the residual phosphorus concentration remained below 0.5 mg / L, indicating stable operation.

[0059] Example 4: Effect of nitrogen-doped aluminum sludge on phosphorus removal in water under different pH conditions

[0060] The same as Example 1, except that, under the conditions of m(melamine):m(aluminum sludge powder from water supply plant)=0.6, initial phosphorus concentration C0=1 mg / L, sludge concentration 2 g / L, reaction temperature 30°C, oscillation speed 120 rpm, and reaction time t=5 d, the pH of the environment in which the nitrogen-doped modified aluminum sludge from water supply plant is reacted is changed. The effects of aluminum sludge materials on phosphorus concentration and removal rate in water under different pH conditions are shown in FIG. Figure 4 shown.

[0061] The graph shows that as the pH increases, the phosphorus concentration in the wastewater gradually rises, while the phosphorus removal rate decreases. The best phosphorus removal was achieved at pH 6.0, with a post-treatment phosphorus concentration of 0.13 mg / L and a phosphorus removal rate of 87%. The worst phosphorus removal was achieved at pH 9.0, with a post-treatment phosphorus concentration of 0.55 mg / L and a phosphorus removal rate of 45%. At pH 6-8.5, the residual phosphorus concentration remained below 0.5 mg / L across all operating conditions, indicating stable operation.

[0062] Example 5: EDS characterization analysis of nitrogen-doped aluminum sludge material

[0063] The same as Example 1, except that the modified aluminum sludge sample with m(melamine):m(aluminum sludge powder from water supply plant)=0.6 was analyzed by EDS spectrometer. Figure 5 The data and images clearly show elements such as Si, Al, Fe, O, and N. The elemental composition of aluminum sludge in the water supply plant is complex, and the peak areas of Si, Al, and Fe are significantly larger than those of other elements, indicating that the substance that plays the main role in dephosphorization in the modified aluminum sludge sample is still aluminum sludge; the modified sludge contains 5.90% N and 11.50% Al, while the original aluminum sludge contains no N and 6% Al, indicating that the aluminum content in the used sludge is relatively low. The main reason for the improvement in dephosphorization efficiency is the effectiveness of nitrogen modification.

[0064] Example 6: Scanning electron microscopy characterization analysis of nitrogen-doped aluminum sludge materials

[0065] The same as Example 1, except that the nitrogen-doped modified aluminum sludge material sample was observed by scanning electron microscopy under the conditions of mass ratio m (melamine): m (aluminum sludge powder from a water supply plant) = 0.6, initial phosphorus concentration C0 = 1 mg / L, sludge concentration 2 g / L, sewage pH = 6.0, reaction temperature 30°C, oscillation speed 120 rpm, and reaction time t = 5 d. Figure 6 This is a scanning electron microscope image of a nitrogen-doped aluminum sludge sample at a 5 µm scale. Figure 6It can be clearly seen that the nitrogen-doped aluminum sludge samples all have slightly smooth, irregular, aggregated microparticles with a compact structure and a slightly molten state. At a 5 µm scale, the tiny particles of nitrogen-doped aluminum sludge have small crystals, numerous intergranular gaps, and dense active sites, demonstrating excellent adsorption.

[0066] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the foregoing descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Any modifications, additions, and the like made without departing from the intended scope of the present invention shall be included within the scope of protection of the present invention.

Claims

1. Application of a phosphorus removal adsorbent based on the nitrogen-doped modified aluminum sludge from a water supply plant in removing phosphorus from sewage, characterized in that: The preparation method of the phosphorus removal adsorbent based on the nitrogen-doped modified aluminum sludge from the water supply plant comprises the following steps: Step 1. The aluminum content of 6-8 wt% of the water plant aluminum sludge is dried, naturally cooled, ground into a powder, and sieved to obtain the water plant aluminum sludge powder; Step 2. Mix the melamine and aluminum sludge powders, add deionized water to obtain a solid-liquid mixture, and ultrasonically mix, wherein the mass ratio of melamine to aluminum sludge powder is 0.6:1; Step 3. After ultrasonication, the solid-liquid mixture is thermally dried, and then the dried material is wrapped in tin foil. The tin foil is evenly perforated to allow the material to co-pyrolyze. After cooling, the mixture is ground and sieved to produce a phosphorus removal adsorbent based on the water supply plant aluminum sludge modified by nitrogen doping.

2. The use of a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant in removing phosphorus from sewage according to claim 1, characterized in that: The specific steps are as follows: adding the phosphorus removal adsorbent based on the nitrogen-doped aluminum sludge of the water supply plant to the phosphorus-containing sewage to be treated, adjusting the pH of the sewage to 6.0-9.0, and the reaction time is 1-7 days.

3. The use of a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant in removing phosphorus from sewage according to claim 2, characterized in that: The phosphorus-containing wastewater to be treated is tail water from a sewage treatment plant, and the dosage of the phosphorus removal adsorbent is 1-5 g / L.

4. The use of a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant in removing phosphorus from sewage according to claim 1, characterized in that: In the step 1, the aluminum sludge from the water supply plant with an aluminum content of 6-8 wt% comes from a water supply plant using aluminum salt as a coagulant, has a moisture content of 50% to 60%, and has a moisture content of less than 10% after drying.

5. The use of a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant in removing phosphorus from sewage according to claim 1, characterized in that: In the step 1, the drying conditions are as follows: drying in a blast dryer at a drying temperature of 105° C.; and passing the powder through a 100-mesh sieve.

6. The use of a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant in removing phosphorus from sewage according to claim 1, characterized in that: In the step 2, the ratio of aluminum sludge powder to deionized water is 10 g:100 mL.

7. The use of a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant in removing phosphorus from sewage according to claim 1, characterized in that: In the step 2, the ultrasonic mixing conditions are: constant temperature ultrasonic treatment at 25-30° C. for 20-40 min, a frequency of 40 kHz, and a power of 300 W.

8. The use of a phosphorus removal adsorbent based on nitrogen-doped aluminum sludge from a water supply plant in removing phosphorus from sewage according to claim 1, characterized in that: In the step 3, the thermal drying conditions are: drying at 105° C. for 24 to 36 hours; the co-pyrolysis conditions are: co-pyrolysis at 400-600° C. for 3 to 5 hours; and after cooling, grinding through a 100-mesh sieve.

Images