Sludge incineration ash phosphorus resource recovery method and system

Abstract

The application discloses a sludge incineration ash phosphorus resource recovery method and system, which comprises the following steps: collecting dewatered sludge cake, placing the dewatered sludge cake in a reaction container, and performing drying, crushing, sieving and calcination to obtain sludge incineration ash; preparing selective lanthanum-based nano adsorbent LDC through a hydrothermal synthesis method; performing component content analysis on the obtained sludge incineration ash, calculating the EDTA addition amount according to the obtained heavy metal content of the sludge incineration ash; placing the sludge incineration ash, EDTA and deionized water in a reaction kettle inner liner, placing a stainless steel hydrothermal reaction kettle in an oven, heating to a target temperature for 1 h, naturally cooling to room temperature, removing unreacted precipitates through centrifugation to obtain a leaching liquor, and adding LDC to perform selective adsorption of phosphates. The application simplifies the optimization process of the hydrothermal reaction experiment, greatly improves the sludge incineration ash leaching efficiency, the prepared LDC adsorbent can separate more than 98% of phosphates in the leaching liquor, has outstanding adsorption capacity and good phosphate selectivity.

Description

Technical Field

[0001] This invention belongs to the field of wastewater resource recovery technology, and more specifically, relates to a method and system for recovering phosphorus resources from sludge incineration ash. Background Technology

[0002] Phosphorus (P) is a non-renewable resource, a constituent element of biological genetic material (DNA and RNA) and adenosine triphosphate (ATP), and an essential element for human life activities and the growth of plants and animals. Phosphorus resources are typically derived from phosphate rock, and phosphorus consumption is closely related to population size, agricultural production, and resource export trade. To alleviate phosphorus shortages, recovering phosphorus from waste and achieving the recycling of phosphorus resources is particularly important. Sewage sludge, a solid waste generated during phosphorus removal in urban wastewater treatment plants, can contain up to 5 wt.% phosphorus, thus it is considered a promising phosphorus-containing solid waste.

[0003] Sludge incineration is a common method for the harmless disposal of sludge. During the incineration process, the volume and weight of the sludge are greatly reduced, and organic matter, bacteria, and insect eggs are oxidized. Phosphorus in the sludge continuously accumulates during this process and eventually combines with heavy metals in the sludge to form complex phosphorus-containing minerals in the sludge incineration ash. Typically, the phosphorus content in sludge incineration ash can reach 4-11.9 wt.%, making it a phosphorus-containing solid waste with great potential for phosphorus recovery.

[0004] Currently, phosphorus recovery from sludge incineration ash mainly falls into two categories: thermochemical methods and wet chemical phosphorus extraction. Thermochemical methods use reagents to solidify or remove heavy metals from sludge incineration ash, but require secondary high-temperature treatment, consuming significant energy and making it difficult to recover pure phosphorus. Wet chemical phosphorus extraction simultaneously leaches phosphorus and heavy metals from sludge incineration ash into the liquid phase, and then separates them using subsequent separation technologies. As a simple, low-requirement, and low-cost phosphorus recovery method, it is widely used. Commonly used leaching agents are mainly strong and moderately strong acids such as sulfuric acid, nitric acid, and hydrochloric acid. However, specific liquid-to-solid ratios and other conditions still need optimization. Insufficient acid content will lead to incomplete phosphorus leaching from the sludge incineration ash. Simultaneously, the metal ions in the leachate are positively charged while the phosphate ions are negatively charged. In this case, secondary precipitation, primarily due to electrostatic attraction, may occur, reducing the amount of phosphorus leached. Secondly, due to the acidic nature and complex composition of the leachate, the selection of separation methods and materials is quite demanding in the subsequent phosphate separation process. In summary, the wet phosphorus extraction process from sludge incineration ash faces several challenges, including incomplete phosphorus leaching, the tendency of phosphorus in the leachate to undergo secondary precipitation with heavy metals, and poor separation efficiency between phosphorus and heavy metals in the leachate. These challenges have become the main limiting factors in the wet phosphorus extraction process from sludge incineration ash. Therefore, designing a wet phosphorus extraction process that uses less extractant, achieves a high phosphorus leaching rate, resists secondary precipitation caused by heavy metal binding, and facilitates phosphorus separation from the leachate is of crucial practical significance for improving the wet chemical phosphorus extraction process from sludge incineration ash.

[0005] Chinese patent application CN101339133B discloses a method for extracting and analyzing the composition of organic phosphorus from calcareous sediments. The method used in this invention employs slightly acidic EDTA (C... 10 H 16 The sediment was rinsed and centrifuged with N2O8 (ethylenediaminetetraacetic acid) solution. Then, using a traditional extraction method, a mixture of NaOH and EDTA solution was used to extract the sediment through shaking and centrifugation. A portion of the NaOH+EDTA extract was then used to determine the total phosphorus content using a spectrometer. However, this invention has the following shortcomings: 1. The extraction rate of total phosphorus from the sediment using the NaOH+EDTA extract is relatively low; 2. It lacks a process for determining and separating the concentrations of other impurity ions in the extraction solution.

[0006] Chinese patent application CN106430136B discloses a method for recovering phosphorus and removing heavy metals from sludge incineration ash. The method uses sulfuric acid dissolution to dissolve heavy metals and phosphorus-containing compounds in the sludge incineration ash into a solution. The mixture is then subjected to solid-liquid separation. NaOH is added to the supernatant to adjust the pH to 8-10, and Na₂S is added to react with the heavy metals in the supernatant to form a precipitate. After centrifugation, the heavy metals are removed. Ca(OH)₂ is added to the supernatant to adjust the pH to 10-12. 2+ With PO4 in solution 3- Calcium phosphate precipitate is formed, and after centrifugation, high-quality calcium phosphate is obtained, achieving the purpose of recovering phosphorus from the solution. However, the shortcomings of this invention are: 1. Sulfuric acid is used as the leaching agent in the leaching process, which requires high corrosion resistance of the reactor; 2. The leaching reaction time is long (10-12 hours), resulting in low leaching efficiency; 3. Strong acids and strong bases are used, involving multiple pH adjustment operations, resulting in large reagent consumption; 4. During the process of adjusting the pH to alkaline, there is a possibility that phosphorus may form secondary precipitates with other metals. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a comprehensive synergistic sludge incineration ash-phosphorus recovery method that utilizes EDTA hydrothermal reaction under certain conditions to achieve ash-phosphorus extraction from sludge incineration, followed by the separation of phosphates from heavy metals using a laboratory-made lanthanide phosphate selective adsorbent LDC (La2CO5, lanthanum carbon dioxide).

[0008] The present invention adopts the following technical solution. The first aspect of the present invention provides a method for recovering phosphorus resources from sludge incineration ash, comprising the following steps:

[0009] Step 1: Collect the dehydrated sludge cake and place it in a reaction vessel for drying, crushing, sieving and calcining to obtain sludge incineration ash;

[0010] Step 2: Selective lanthanum-based nano-adsorbent LDC is prepared by hydrothermal synthesis.

[0011] Step 3: Perform XRF (X-Ray Fluorescence Spectrometer) component content analysis on the sludge incineration ash obtained in Step 1, and calculate the amount of EDTA to be added based on the heavy metal content of the sludge incineration ash obtained from the test.

[0012] Step 4: Place the sludge incineration ash, EDTA and deionized water into the reactor liner, place the stainless steel hydrothermal reactor into the oven, heat to the target temperature for 1 hour, then turn off the power and allow the oven to cool naturally to room temperature.

[0013] Step 5: Transfer the solution obtained in step 4 to a centrifuge tube, centrifuge to remove unreacted precipitate, and obtain an extract. Add the LDC obtained in step 2 to selectively adsorb phosphate.

[0014] Preferably, step 1 includes:

[0015] Step 1.1: Collect dewatered sludge cakes from the wastewater treatment plant and dry them in an oven at 105°C for two days to obtain dried sludge;

[0016] Step 1.2: Mechanically crush and sieve the dried sludge obtained in Step 1.1, and collect samples with a particle size of less than 0.075 mm;

[0017] Step 1.3: The sludge powder obtained in step 1.2 is calcined in a muffle furnace at 800°C for 3 hours. The resulting incineration ash is named SSIA800.

[0018] Preferably, step 2 includes:

[0019] Step 2.1: Dissolve 8.0 mmol La(NO3)3·6H2O and 4.0 mmol disodium ethylenediaminetetraacetate in 100 mL of deionized water and stir magnetically for 30 minutes.

[0020] Step 2.2: Adjust the pH of the above solution to the ideal value using ammonia water, stir for 30 minutes, then add 50 mL of 16 mM cetyltrimethylammonium bromide and stir for 30 minutes.

[0021] Step 2.3: Transfer the stirred liquid to a 250ml hydrothermal reactor and react at 200℃ for 24h.

[0022] Step 2.4: Wash, dry and grind the solid material obtained in step 2.4. Calcine the ground white powder in a muffle furnace at 420°C for 180 minutes to obtain lanthanide nano-phosphate adsorbent LDC.

[0023] Preferably, step 3 includes:

[0024] Step 3.1: Use an XRF instrument to test the sample and obtain the raw data of the composition and content of each metal element;

[0025] Step 3.2: Calculate the mass of all metals contained in the SSIA800 added in the hydrothermal reaction and convert it into moles. Then, based on the complexation ratio of EDTA with each metal, calculate the amount of EDTA added for each metal element. Sum the amounts of EDTA added for all metal elements in the SSIA800 to obtain the total amount of EDTA added in the SSIA800 hydrothermal reaction.

[0026] Preferably, the formula for calculating the amount of EDTA added for each metal element is as follows:

[0027]

[0028] Preferably, step 4 includes:

[0029] Step 4.1: Weigh 2g of sludge incineration ash, 6.7554g of EDTA and 100ml of deionized water into the lining of a 250ml reactor.

[0030] Step 4.2: Place the hydrothermal reactor in an oven and heat it from room temperature to 140°C, then maintain the temperature for 1 hour.

[0031] Step 4.3: After the constant temperature stage is over, turn off the power and wait for the oven to cool naturally to room temperature before taking out the hydrothermal reactor.

[0032] Preferably, the selective adsorption process in step 5 is as follows:

[0033] Add 2.5 ml of the extract to a 50 ml centrifuge tube, add 20 mg of adsorbent LDC and 22.5 ml of deionized water, and perform adsorption at 200 rpm in a constant temperature shaker at 25 °C.

[0034] A second aspect of the present invention provides a sludge incineration ash-phosphorus resource recovery system, comprising the following steps for performing a sludge incineration ash-phosphorus resource recovery method:

[0035] The collection module is used to place the dewatered sludge cake in a reaction vessel for drying, crushing, sieving and calcining to obtain sludge incineration ash;

[0036] A synthesis module for preparing selective lanthanum-based nano-adsorbents (LDC) using a hydrothermal synthesis method;

[0037] The analysis module is used to perform XRF component content analysis and calculate the amount of EDTA added;

[0038] The reaction and adsorption module is used to place sludge incineration ash, EDTA and deionized water in a reactor for reaction, centrifuge to remove precipitate, and add LDC for selective adsorption of phosphate.

[0039] The beneficial effects of this invention are that, compared with the prior art,

[0040] (1) The method proposed in this invention uses XRF to test the elemental content of sludge incineration ash and determines the amount of EDTA to be added for the hydrothermal reaction based on the elemental content of the incineration ash, simplifying the optimization process of the hydrothermal reaction experiment. This greatly improves the leaching efficiency of sludge incineration ash. The added EDTA also forms stable complexes with dissolved heavy metals, reducing the possibility of secondary precipitation of heavy metals and phosphorus. The resulting EDTA leachate also facilitates the selective separation of LDC in the subsequent reaction. Under optimal reaction conditions, the phosphorus leaching rate in sludge incineration ash can reach 96.48%.

[0041] (2) The lanthanide nano-phosphate selective adsorbent (LDC) prepared by the experimental method proposed in this invention has a large phosphate adsorption capacity (theoretical adsorption capacity is 188.68 mg / g), strong phosphate selectivity, simple preparation method, low pollution and relatively low cost. Figure 2 This is a scanning electron microscope image of LDC.

[0042] (3) The method proposed in this invention can release more than 96% of the phosphorus in sludge incineration ash under optimal conditions. During the separation process, the laboratory-prepared LDC adsorbent can separate more than 98% of the phosphate in the leachate, with excellent adsorption capacity and good phosphate selectivity. The corresponding relative adsorption amounts for heavy metals are (Al 16.4%, Fe 0.074%, Mg 0.058%). Table 2 shows the content of each element in the leachate obtained by this invention. Figure 2 This is a refined XRD (X-ray diffraction) image of the LDC adsorbent obtained in this invention. Figure 3 Table 3 shows the thermodynamic and kinetic fitting diagrams for the adsorption of LDC adsorbent, and the kinetic-thermodynamic fitting parameters are presented in Table 3. Figure 4 The concentrations of P and characteristic metals in the extract were measured by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) before and after adsorption. Attached Figure Description

[0043] Figure 1 This is a scanning electron microscope image of the LDC prepared by the method of the present invention;

[0044] Figure 2 This is the refined XRD pattern of LDC obtained by the method of this invention;

[0045] Figure 3 The adsorption isotherm (left) and kinetics (right) of LDC obtained by the method of this invention;

[0046] Figure 4 The concentration changes of major elements in the extract obtained by the method of the present invention before and after LDC adsorption. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0048] Embodiment 1 of the present invention provides a method for recovering phosphorus resources from sludge incineration ash, comprising the following steps:

[0049] Step 1: Collect the dehydrated sludge cake and place it in a reaction vessel for drying, crushing, sieving and calcining to obtain sludge incineration ash.

[0050] In a preferred but non-limiting embodiment of the present invention, step 1 specifically includes:

[0051] Step 1.1: Collect dewatered sludge cakes from the wastewater treatment plant and dry them in an oven at 105°C for two days to obtain dried sludge;

[0052] Step 1.2: Mechanically crush and sieve the dried sludge obtained in Step 1.1, and collect samples with a particle size of less than 0.075 mm (200 mesh);

[0053] Step 1.3: The sludge powder obtained in step 1.2 is calcined in a muffle furnace at 800°C for 3 hours. The resulting incineration ash is named SSIA800.

[0054] Step 2: Selective lanthanum-based nano-adsorbent LDC is prepared by hydrothermal synthesis.

[0055] In a preferred but non-limiting embodiment of the present invention, step 2 specifically includes:

[0056] Step 2.1: Dissolve 8.0 mmol La(NO3)3·6H2O and 4.0 mmol of disodium ethylenediaminetetraacetate (EDTA-2Na) in 100 mL of deionized water and stir magnetically for 30 minutes.

[0057] Step 2.2: Adjust the pH of the above solution to the ideal value using ammonia water, stir for 30 minutes, then add 50 mL of 16 mM hexadecyltrimethylammonium bromide (CTAB) and stir for 30 minutes.

[0058] Step 2.3: Transfer the stirred liquid to a 250ml hydrothermal reactor and react at 200℃ for 24h.

[0059] Step 2.4: Wash, dry, and grind the solid material obtained in Step 2.4. Calcine the ground white powder in a muffle furnace at 420°C for 180 minutes to obtain the lanthanide nano-phosphate adsorbent LDC. Figure 1 , Figure 2 As shown.

[0060] In a preferred but non-limiting embodiment of the present invention, the ideal pH value described in step 2.2 is 7-8, with the best effect achieved at a pH value of 7.3.

[0061] It is worth noting that, in engineering practice, those skilled in the art can use other organic acid chelating agents instead of EDTA in this invention, and can recover other valuable elements by using the hydrothermal extraction method and organic acid addition calculation method proposed in this invention, all of which fall within the scope of this invention.

[0062] It is worth noting that, in engineering practice, any substitution of LDC in the method of this invention with other lanthanide adsorbents by those skilled in the art using the preparation and adsorption methods proposed in this invention falls within the scope of this invention.

[0063] It is worth noting that, such as Figure 3 As shown, in order to highlight the beneficial technical effects that the present invention can achieve, the present invention performs adsorption isotherm and kinetic fitting parameter analysis on the obtained LDC.

[0064] Table 1. LDC adsorption isotherms and kinetic fitting parameters obtained in this invention.

[0065]

[0066]

[0067] Step 3: Perform XRF component content analysis on the generated sludge incineration ash, and calculate the amount of EDTA to be added based on the heavy metal content of the sludge incineration ash obtained from the test.

[0068] In a preferred but non-limiting embodiment of the present invention, step 3 specifically includes:

[0069] Step 3.1: Use an XRF instrument to test the sample and obtain the raw data of the composition and content of each metal element, as shown in Table 2.

[0070] Table 2. Element content of sludge incineration ash obtained by the present invention

[0071]

[0072]

[0073] Step 3.2: Calculate the mass of all metals contained in the SSIA800 added in the hydrothermal reaction and convert it into moles. Then, based on the complexation ratio of EDTA with each metal, calculate the amount of EDTA added for each metal element. Sum the amounts of EDTA added for all metal elements in the SSIA800 to obtain the total amount of EDTA added in the SSIA800 hydrothermal reaction.

[0074] In a preferred but non-limiting embodiment of the present invention, the formula for calculating the amount of EDTA added for each metal element is as follows:

[0075]

[0076] In this embodiment, the amount of SSIA added is specified as 2g. The amount of EDTA added for each metal can be calculated using the above formula, and the sum of these amounts is the total amount of EDTA added.

[0077] Step 4: Place the sludge incineration ash, EDTA and deionized water into the reactor liner, place the stainless steel hydrothermal reactor into the oven, heat to the target temperature for 1 hour, then turn off the power and allow the oven to cool naturally to room temperature.

[0078] In a preferred but non-limiting embodiment of the present invention, step 4 specifically includes:

[0079] Step 4.1: Weigh 2g of sludge incineration ash, 6.7554g of EDTA and 100ml of deionized water into the lining of a 250ml reactor.

[0080] Step 4.2: Place the hydrothermal reactor in an oven and heat it from room temperature to 140°C, then maintain the temperature for 1 hour.

[0081] Step 4.3: After the constant temperature stage is over, turn off the power and wait for the oven to cool naturally to room temperature before taking out the hydrothermal reactor.

[0082] Step 5: Transfer the solution obtained in step 4 to a centrifuge tube, centrifuge to remove unreacted precipitate, and obtain an extract. Add LDC to selectively adsorb phosphate.

[0083] In a preferred but non-limiting embodiment of the present invention, the selective adsorption process is as follows:

[0084] Add 2.5 ml of the extract to a 50 ml centrifuge tube, add 20 mg of adsorbent LDC and 22.5 ml of deionized water, and perform adsorption at 200 rpm in a constant temperature shaker at 25 °C.

[0085] It is worth noting that, as shown in Table 3, in order to highlight the beneficial technical effects that the present invention can achieve, the present invention performs ICP-OES component content analysis on the obtained extract.

[0086] Table 3 Element content of the extract obtained in this invention

[0087]

[0088] It is worth noting that, such as Figure 4 As shown, in order to highlight the beneficial technical effects that the present invention can achieve, the present invention performs ICP-OES component content analysis on the extract before and after adsorption, and obtains the concentration changes of the main elements in the extract before and after LDC adsorption.

[0089] Embodiment 2 of the present invention provides a sludge incineration ash phosphorus resource recovery system, specifically comprising:

[0090] The collection module is used to place the dewatered sludge cake in a reaction vessel for drying, crushing, sieving and calcining to obtain sludge incineration ash;

[0091] A synthesis module for preparing selective lanthanum-based nano-adsorbents (LDC) using a hydrothermal synthesis method;

[0092] The analysis module is used to perform XRF component content analysis and calculate the amount of EDTA added;

[0093] The reaction and adsorption module is used to place sludge incineration ash, EDTA and deionized water in a reactor for reaction, centrifuge to remove precipitate, and add LDC for selective adsorption of phosphate.

[0094] The beneficial effects of this invention are that, compared with the prior art,

[0095] (1) The method proposed in this invention uses XRF to test the elemental content of sludge incineration ash and determines the amount of EDTA to be added for the hydrothermal reaction based on the elemental content of the incineration ash. This simplifies the optimization process of the hydrothermal reaction experiment and greatly improves the leaching efficiency of sludge incineration ash. The added EDTA also forms stable complexes with dissolved heavy metals, reducing the possibility of secondary precipitation of heavy metals and phosphorus. The resulting EDTA leachate also facilitates the selective separation of LDC in the subsequent reaction. Under optimal reaction conditions, the phosphorus leaching rate in sludge incineration ash can reach 96.48%.

[0096] (2) The lanthanide nano-phosphate selective adsorbent (LDC) prepared by the experimental method proposed in this invention has a large phosphate adsorption capacity (theoretical adsorption capacity is 188.68 mg / g), strong phosphate selectivity, simple preparation method, low pollution and relatively low cost. Figure 2 This is a scanning electron microscope image of LDC.

[0097] (3) The method proposed in this invention can release more than 96% of the phosphorus in sludge incineration ash under optimal conditions. During the separation process, the laboratory-prepared LDC adsorbent can separate more than 98% of the phosphate in the leachate, with excellent adsorption capacity and good phosphate selectivity. The corresponding relative adsorption amounts for heavy metals are (Al 16.4%, Fe 0.074%, Mg 0.058%). Table 2 shows the content of each element in the leachate obtained by this invention. Figure 2 This is a refined XRD pattern of the LDC adsorbent obtained in this invention. Figure 3 Table 3 shows the thermodynamic and kinetic fitting diagrams for the adsorption of LDC adsorbent, and the kinetic-thermodynamic fitting parameters are presented in Table 3. Figure 4 The concentrations of P and characteristic metals in the extract were measured by ICP-OES before and after adsorption.

[0098] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for recovering phosphorus resources from sludge incineration ash, characterized in that, Includes the following steps: Step 1: Collect the dehydrated sludge cake and place it in a reaction vessel for drying, crushing, sieving and calcining to obtain sludge incineration ash; Step 2: Selective lanthanum-based nano-adsorbent LDC is prepared by hydrothermal synthesis. Step 2 includes: Step 2.1: Dissolve 8.0 mmol La(NO3)3·6H2O and 4.0 mmol disodium ethylenediaminetetraacetate in 100 mL of deionized water and stir magnetically for 30 minutes. Step 2.2: Adjust the pH of the above solution to 7-8 using ammonia water, stir for 30 minutes, then add 50 mL of 16 mM hexadecyltrimethylammonium bromide and stir for 30 minutes. Step 2.3: Transfer the stirred liquid to a 250ml hydrothermal reactor and react at 200℃ for 24 h. Step 2.4: Wash, dry and grind the solid material obtained in Step 2.

4. Calcine the ground white powder in a muffle furnace at 420°C for 180 minutes to obtain lanthanide nano-phosphate adsorbent LDC. Step 3: Perform XRF component content analysis on the sludge incineration ash obtained in Step 1, and calculate the amount of EDTA to be added based on the heavy metal content of the sludge incineration ash obtained from the test. Step 4: Place the sludge incineration ash, EDTA and deionized water into the reactor liner, place the stainless steel hydrothermal reactor into the oven, heat to the target temperature for 1 hour, then turn off the power and allow the oven to cool naturally to room temperature. Step 5: Transfer the solution obtained in step 4 to a centrifuge tube, centrifuge to remove unreacted precipitate, and obtain an extract. Add the LDC obtained in step 2 to selectively adsorb phosphate.

2. The method for recovering phosphorus resources from sludge incineration ash as described in claim 1, characterized in that, Step 1 includes: Step 1.1: Collect dewatered sludge cakes from the wastewater treatment plant and dry them in an oven at 105°C for two days to obtain dried sludge; Step 1.2: Mechanically crush and sieve the dried sludge obtained in Step 1.1, and collect samples with a particle size of less than 0.075 mm; Step 1.3: The sludge powder obtained in step 1.2 is calcined in a muffle furnace at 800°C for 3 hours. The resulting incineration ash is named SSIA800.

3. The method for recovering phosphorus resources from sludge incineration ash as described in claim 1, characterized in that, Step 3 includes: Step 3.1: Use an XRF instrument to test the sample and obtain the raw data of the composition and content of each metal element; Step 3.2: Calculate the mass of all metals contained in the SSIA800 added in the hydrothermal reaction and convert it into moles. Then, based on the complexation ratio of EDTA with each metal, calculate the amount of EDTA added for each metal element. Sum the amounts of EDTA added for all metal elements in the SSIA800 to obtain the total amount of EDTA added in the SSIA800 hydrothermal reaction.

4. The method for recovering phosphorus resources from sludge incineration as described in claim 3, characterized in that: The formulas for calculating the amount of EDTA added for each metal element are as follows: 。 5. The method for recovering phosphorus resources from sludge incineration ash as described in claim 1, characterized in that, Step 4 includes: Step 4.1: Weigh 2g of sludge incineration ash, 6.7554g of EDTA and 100ml of deionized water into the lining of a 250ml reactor. Step 4.2: Place the hydrothermal reactor in an oven and heat it from room temperature to 140°C, then maintain the temperature for 1 hour. Step 4.3: After the constant temperature stage is over, turn off the power and wait for the oven to cool naturally to room temperature before taking out the hydrothermal reactor.

6. The method for recovering phosphorus resources from sludge incineration ash as described in claim 1, characterized in that, The selective adsorption process in step 5 is as follows: Add 2.5 ml of the extract to a 50 ml centrifuge tube, add 20 mg of adsorbent LDC and 22.5 ml of deionized water, and perform adsorption at 200 rpm in a constant temperature shaker at 25°C.

7. A sludge incineration ash-phosphorus resource recovery system, comprising a sludge incineration ash-phosphorus resource recovery method as described in any one of claims 1 to 6, characterized in that: The collection module is used to place the dewatered sludge cake in a reaction vessel for drying, crushing, sieving and calcining to obtain sludge incineration ash; A synthesis module for preparing selective lanthanum-based nano-adsorbents (LDC) using a hydrothermal synthesis method; The analysis module is used to perform XRF component content analysis and calculate the amount of EDTA added; The reaction and adsorption module is used to place sludge incineration ash, EDTA and deionized water in a reactor for reaction, centrifuge to remove precipitate, and add LDC for selective adsorption of phosphate.

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