Sludge hydrothermal carbonization slurry water treatment carrier as well as preparation method and application thereof

Abstract

The invention relates to the field of environmental management, in particular to a sludge hydrothermal carbonization slurry water treatment carrier as well as a preparation method and application thereof. The method comprises the following steps: taking sludge hydrothermal carbonization slurry as a base material, adding active magnesium oxide, uniformly stirring, carrying out ultrasonic treatment, and dividing into two paths, one path flowing into an anaerobic system and the other path flowing into an anoxic system. According to the invention, the municipal sludge is directly subjected to hydrothermal carbonization modification to generate the charcoal slurry, and the charcoal has a porous structure and good microbial affinity and can be used as a good microbial immobilized fluidized bed carrier, so that the microbial activity and the water treatment efficiency are improved. The method is simple in technical operation, can be directly embedded into a traditional water treatment process, reduces the sludge yield, realizes in-situ resource utilization of the sludge, and is suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of environmental remediation, and in particular to a sludge hydrothermal carbonization slurry water treatment carrier, its preparation method, and its application. Background Technology

[0002] With the continuous expansion of wastewater treatment scale, sludge production is constantly increasing, and its treatment and disposal have become industry challenges. Traditional sludge disposal methods such as landfill and incineration suffer from high costs, resource waste, and secondary pollution. On the other hand, biological wastewater treatment processes (such as A...) 2 In systems such as septic tank reactors (SBR) and bioreactors (SBR), the performance of the microbial carrier directly affects the system's treatment efficiency, stability, and sludge production. Currently used carriers, such as ceramsite, activated carbon, and synthetic fillers, suffer from problems such as high cost, insufficient microbial affinity, and limited functionality.

[0003] Hydrothermal carbonization technology can convert sludge into biochar rich in porous structures, which has good adsorption performance and microbial affinity. However, there is currently little research on directly applying hydrothermal carbonization products of sludge as biological carriers to activated sludge systems, especially regarding how to couple them with existing processes and how to optimize carrier performance to improve the system's nitrogen and phosphorus removal efficiency and reduce excess sludge production. Systematic technologies and methods are lacking in these areas.

[0004] Therefore, developing a technology that uses sludge hydrothermal carbonization slurry as the core, prepares high-performance microbial carriers through modification, and integrates them into traditional biological treatment processes is of great significance for realizing sludge resource utilization, improving wastewater treatment efficiency, and reducing operating costs. Summary of the Invention

[0005] This invention provides a sludge hydrothermal carbonization slurry water treatment carrier, its preparation method, and its application. This technology combines sludge hydrothermal carbonization slurry with activated magnesium oxide and prepares a multifunctional carrier with physical adsorption, chemical enhancement, and biocompatibility through ultrasonic treatment. The carrier is then added to the anaerobic and anoxic zones of wastewater treatment in a specific ratio to enhance system performance and achieve in-situ sludge reduction and resource utilization.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry, comprising the following steps: Sludge hydrothermal carbonization slurry and activated magnesium oxide are mixed and ultrasonically treated to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0007] In some specific embodiments, the preparation of the sludge hydrothermal carbonization slurry includes: The sludge undergoes a hydrothermal carbonization reaction under an acidic catalyst to obtain a hydrothermal carbonization slurry.

[0008] In some specific embodiments, the sludge has a water content of 75% to 90%.

[0009] In some specific embodiments, the organic matter content in the sludge is 30% to 80%.

[0010] In some specific embodiments, the hydrothermal carbonization reaction is carried out in a closed reaction vessel.

[0011] In some specific embodiments, the temperature of the hydrothermal carbonization reaction is 160~220℃, the pressure of the hydrothermal carbonization reaction is 1~3MPa, and the time of the hydrothermal carbonization reaction is 2~6h.

[0012] In some specific embodiments, the acidic catalyst for the hydrothermal carbonization reaction is at least one of sulfuric acid, hydrochloric acid, oxalic acid, and citric acid.

[0013] In some specific embodiments, the mass ratio of the sludge to the acidic catalyst is 100:(1~5).

[0014] In some specific embodiments, the mass ratio of the sludge hydrothermal carbonization slurry to the activated magnesium oxide is 100:(0.1~1).

[0015] In some specific embodiments, the particle size of the active magnesium oxide is 100-500 mesh.

[0016] In some specific embodiments, the frequency of the ultrasonic treatment is 20~100Hz, and the duration of the ultrasonic treatment is 10~30min.

[0017] A second aspect of the present invention also provides a sludge hydrothermal carbonization slurry water treatment carrier prepared by the above-mentioned method.

[0018] A third aspect of the present invention also provides the application of the above-mentioned sludge hydrothermal carbonization slurry water treatment carrier in wastewater treatment.

[0019] In some specific embodiments, the application includes the following steps: The sludge hydrothermal carbonization slurry water treatment carrier was added to the anaerobic reaction zone and the anoxic reaction zone of the wastewater treatment system, respectively. The wastewater treatment system is a biological nitrogen and phosphorus removal process with anaerobic, anoxic, and aerobic zones.

[0020] In some specific embodiments, the dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anaerobic reaction zone is 0.05‰ to 0.5‰ of the influent volume of the wastewater treatment system.

[0021] In some specific embodiments, the dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anoxic reaction zone is 0.01‰ to 0.1‰ of the influent volume of the wastewater treatment system.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The municipal sludge is directly converted into a high-value-added water treatment carrier, realizing the in-situ and resource utilization of sludge. At the same time, the sludge production in the system can be reduced by 15-30%, reducing the sludge disposal pressure from the source.

[0023] (2) The porous structure of sludge biochar provides a huge specific surface area and abundant microbial attachment sites; ultrasonic treatment improves dispersibility and breaks down macromolecular chains, thereby improving biochemical properties; the addition of activated magnesium oxide not only regulates the microenvironment on the carrier surface, but also slowly releases Mg 2+ It can also form precipitates with phosphates and ammonium salts, enhancing the denitrification and phosphorus removal effects, while providing a weakly alkaline buffering effect.

[0024] (3) The liquid in the treated biochar slurry can be used as a supplementary carbon source. The solid biochar carrier has good microbial affinity and can enrich functional microorganisms (such as polyphosphate-accumulating bacteria and denitrifying bacteria) to form a highly active biofilm, which significantly improves the nitrogen and phosphorus removal efficiency of the system. Experiments show that under the same conditions, the removal rates of COD, total nitrogen and total phosphorus in the system can be increased by 5-15%.

[0025] (4) This technology can be directly embedded into the anaerobic and anoxic sections of existing sewage treatment processes without large-scale infrastructure modifications. It is simple to operate, easy to manage, and suitable for large-scale promotion and application.

[0026] (5) The main raw material is sludge, the amount of auxiliary materials is small, the preparation process is simple, the overall cost is much lower than that of commercial carriers, and it has significant economic benefits. Detailed Implementation

[0027] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the following embodiments, conditions and methods known in the art can be used for processing.

[0028] This invention provides a method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry, comprising the following steps: Sludge hydrothermal carbonization slurry and activated magnesium oxide are mixed and ultrasonically treated to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0029] In some embodiments, the preparation of the sludge hydrothermal carbonization slurry includes: The sludge undergoes a hydrothermal carbonization reaction under an acidic catalyst to obtain a hydrothermal carbonization slurry.

[0030] In some embodiments, the sludge has a moisture content of 75% to 90%. As an example, the moisture content of the sludge can be 75%, 78%, 80%, 85%, 88%, and 90%, etc.

[0031] In some embodiments, the organic matter content in the sludge is 30% to 80%. As an example, the organic matter content in the sludge can be 30%, 40%, 50%, 60%, 70%, and 80%, etc.

[0032] In some embodiments, the hydrothermal carbonization reaction is carried out in a closed reactor.

[0033] In some embodiments, the temperature of the hydrothermal carbonization reaction is 160~220℃, the pressure of the hydrothermal carbonization reaction is 1~3MPa, and the time of the hydrothermal carbonization reaction is 2~6h. As an example, the temperature of the hydrothermal carbonization reaction can be 160℃, 170℃, 180℃, 200℃, 210℃, and 220℃, etc.; the time can be 2h, 3h, 4h, 5h, and 6h, etc.; and the pressure can be 1MPa, 1.5MPa, 2MPa, 2.5MPa, and 3MPa, etc.

[0034] In some embodiments, the acidic catalyst for the hydrothermal carbonization reaction is at least one of sulfuric acid, hydrochloric acid, oxalic acid, and citric acid.

[0035] The mass ratio of the sludge to the acidic catalyst is 100:(1~5).

[0036] As an example, the preparation of sludge hydrothermal carbonization slurry specifically includes the following steps: Mix 100g of sludge with a moisture content of 75%~90% and an organic matter content of 30%~80% with 1~5g of acidic catalyst, and carry out hydrothermal carbonization reaction in a closed container at 160~220℃ and 1~3MPa for 2~6h.

[0037] In some embodiments, the mass ratio of the sludge hydrothermal carbonization slurry to the activated magnesium oxide is 100:(0.1~1). As examples, the mass ratio of the sludge hydrothermal carbonization slurry to activated magnesium oxide can be 100:0.1, 100:0.3, 100:0.5, 100:0.6, 100:0.8, and 100:1, etc. In this invention, the addition of activated magnesium oxide can both adsorb and treat pollutants such as ammonia nitrogen and phosphate, providing a weakly alkaline buffering effect, and simultaneously synergistically enhance the water treatment capacity by supporting microorganisms in the sludge biochar. If the proportion of activated magnesium oxide added is too high, the cost is high and the microbial loading capacity is reduced; if the proportion of activated magnesium oxide added is too low, the adsorption and treatment performance of pollutants such as ammonia nitrogen and phosphate is weak, increasing the pollutant load on the water, and the pH of the sludge hydrothermal carbonization slurry is low, reducing the activity of microorganisms in water treatment.

[0038] In some embodiments, the particle size of the activated magnesium oxide is 100-500 mesh. As an example, the particle size of the activated magnesium oxide can be 100 mesh, 150 mesh, 200 mesh, 300 mesh, 350 mesh, 400 mesh, and 500 mesh, etc.

[0039] In some embodiments, the frequency of the ultrasonic treatment is 20-100 Hz, and the duration of the ultrasonic treatment is 10-30 min. As an example, the frequency of the ultrasonic treatment can be 20, 30, 40, 50, 60, 80, and 100 Hz, and the duration of the ultrasonic treatment can be 10 min, 15 min, 20 min, 25 min, and 30 min, etc.

[0040] A second aspect of the present invention also provides a sludge hydrothermal carbonization slurry water treatment carrier prepared by the above-mentioned method.

[0041] A third aspect of the present invention also provides the application of the above-mentioned sludge hydrothermal carbonization slurry water treatment carrier in wastewater treatment.

[0042] In some embodiments, the application includes the following steps: The sludge hydrothermal carbonization slurry water treatment carrier was added to the anaerobic reaction zone and the anoxic reaction zone of the wastewater treatment system, respectively. The wastewater treatment system is a biological nitrogen and phosphorus removal process with anaerobic, anoxic, and aerobic zones.

[0043] In some embodiments, the dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anaerobic reaction zone is 0.05‰ to 0.5‰ of the influent volume of the wastewater treatment system. As an example, the dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anaerobic reaction zone can be 0.05‰, 0.1‰, 0.2‰, 0.3‰, 0.4‰, and 0.5‰ of the influent volume of the wastewater treatment system, etc.

[0044] In some embodiments, the dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anoxic reaction zone is 0.01‰ to 0.1‰ of the influent volume of the wastewater treatment system. As an example, the dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anoxic reaction zone can be 0.01‰, 0.03‰, 0.05‰, 0.06‰, 0.08‰, and 0.1‰ of the influent volume of the wastewater treatment system, etc.

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] The influent to each reactor was simulated urban sewage, and its water quality is shown in Table 1.

[0047] Table 1 Water quality of simulated urban wastewater

[0048] The materials used in the following embodiments are sourced from: Sludge: Dewatered sludge taken from a municipal wastewater treatment plant in Chuzhou City, with a moisture content of 80% and an organic matter content of 55%.

[0049] Activated magnesium oxide: Industrial grade, specific surface area approximately 120 m² 2 / g.

[0050] Commercial carrier: Commercially available polyethylene suspension packing (specific surface area approximately 500 m²) 2 / m 3 ).

[0051] The wastewater treatment system is a biological nitrogen and phosphorus removal process with anaerobic, anoxic, and aerobic zones.

[0052] Example 1 A method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry includes the following steps: 200g of sludge and 3g of sulfuric acid catalyst were mixed and hydrothermally carbonized at 200℃ and 2MPa for 3h in a closed environment to obtain sludge hydrothermal carbonization slurry. 100 parts of sludge hydrothermal carbonization slurry and 0.3 parts of activated magnesium oxide (300 mesh particle size) were mixed and ultrasonically treated at 50 Hz for 20 min to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0053] The sludge hydrothermal carbonization slurry water treatment carrier is added to the anaerobic reaction zone and the anoxic reaction zone of the sewage treatment system, respectively; wherein the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anaerobic reaction zone is 0.1‰ of the influent volume of the sewage treatment system, and the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anoxic reaction zone is 0.03‰ of the influent volume of the sewage treatment system.

[0054] The test results showed that the COD removal rate was 94.2%, the TN removal rate was 84.1%, the TP removal rate was 96.5%, and the sludge reduction rate was 19%.

[0055] Example 2 A method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry includes the following steps: 200g of sludge and 3g of sulfuric acid catalyst were mixed and hydrothermally carbonized at 200℃ and 2MPa for 3h in a closed environment to obtain sludge hydrothermal carbonization slurry. 100 parts of sludge hydrothermal carbonization slurry and 0.8 parts of activated magnesium oxide (particle size 500 mesh) were mixed and ultrasonically treated at 80 Hz for 25 min to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0056] The sludge hydrothermal carbonization slurry water treatment carrier is added to the anaerobic reaction zone and the anoxic reaction zone of the sewage treatment system, respectively; wherein the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anaerobic reaction zone is 0.3‰ of the influent volume of the sewage treatment system, and the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anoxic reaction zone is 0.08‰ of the influent volume of the sewage treatment system.

[0057] The test results showed that the COD removal rate was 95.1%, the TN removal rate was 88.3%, the TP removal rate was 98.8%, and the sludge reduction rate was 27%.

[0058] Example 3 A method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry includes the following steps: 200g of sludge and 3g of sulfuric acid catalyst were mixed and hydrothermally carbonized at 160℃ and 2MPa for 6 hours in a closed environment to obtain sludge hydrothermal carbonization slurry. 100 parts of sludge hydrothermal carbonization slurry and 0.2 parts of activated magnesium oxide (particle size 200 mesh) were mixed and ultrasonically treated at 40 Hz for 30 min to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0059] The sludge hydrothermal carbonization slurry water treatment carrier is added to the anaerobic reaction zone and the anoxic reaction zone of the sewage treatment system, respectively; wherein the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anaerobic reaction zone is 0.08‰ of the influent volume of the sewage treatment system, and the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anoxic reaction zone is 0.02‰ of the influent volume of the sewage treatment system.

[0060] The test results showed that the COD removal rate was 92.5%, the TN removal rate was 82.0%, the TP removal rate was 93.8%, and the sludge reduction rate was 15%.

[0061] Example 4 A method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry includes the following steps: 200g of sludge and 3g of sulfuric acid catalyst were mixed and hydrothermally carbonized at 200℃ and 2MPa for 3h in a closed environment to obtain sludge hydrothermal carbonization slurry. 100 parts of sludge hydrothermal carbonization slurry and 1 part of activated magnesium oxide (particle size 400 mesh) were mixed and ultrasonically treated at 100 Hz for 30 min to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0062] The sludge hydrothermal carbonization slurry water treatment carrier is added to the anaerobic reaction zone and the anoxic reaction zone of the sewage treatment system, respectively; wherein the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anaerobic reaction zone is 0.4‰ of the influent volume of the sewage treatment system, and the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anoxic reaction zone is 0.1‰ of the influent volume of the sewage treatment system.

[0063] The test results showed that the COD removal rate was 95.8%, the TN removal rate was 89.5%, the TP removal rate was 99.2%, and the sludge reduction rate was 30%.

[0064] Example 5 A method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry includes the following steps: 200g of sludge and 3g of sulfuric acid catalyst were mixed and hydrothermally carbonized at 200℃ and 2MPa for 3h in a closed environment to obtain sludge hydrothermal carbonization slurry. 100 parts of sludge hydrothermal carbonization slurry and 0.3 parts of activated magnesium oxide were mixed and ultrasonically treated at 50 Hz for 20 min to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0065] The sludge hydrothermal carbonization slurry water treatment carrier is added to the anaerobic reaction zone of the wastewater treatment system, but not to the anoxic zone; wherein the amount of sludge hydrothermal carbonization slurry water treatment carrier added to the anaerobic reaction zone is 0.2‰ of the influent volume of the wastewater treatment system.

[0066] The test results showed that the COD removal rate was 93.5%, the TN removal rate was 78.2%, the TP removal rate was 94.6%, and the sludge reduction rate was 17%.

[0067] Example 6 A method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry includes the following steps: 200g of sludge and 3g of sulfuric acid catalyst were mixed and hydrothermally carbonized at 200℃ and 2MPa for 3h in a closed environment to obtain sludge hydrothermal carbonization slurry. 100 parts of sludge hydrothermal carbonization slurry and 0.3 parts of activated magnesium oxide were mixed and ultrasonically treated at 50 Hz for 20 min to obtain sludge hydrothermal carbonization slurry water treatment carrier.

[0068] The sludge hydrothermal carbonization slurry water treatment carrier is added to the SBR process; wherein the amount of sludge hydrothermal carbonization slurry water treatment carrier added is 0.15‰ of the influent volume per cycle.

[0069] The test results showed that the COD removal rate was 93.8%, the TN removal rate was 83.5%, the TP removal rate was 96.0%, and the sludge reduction rate was 20%.

[0070] Comparative Example 1 Carrier type: No external loading body.

[0071] Operational results: COD removal rate 87.2%, TN removal rate 71.8%, TP removal rate 77.5%, sludge reduction rate 0%. Comparative Example 2 The difference from Example 1 is that the water treatment carrier of the sludge hydrothermal carbonization slurry is replaced with commercially available polyethylene suspension filler with a filling rate of 15%, while the rest are the same as in Example 1.

[0072] The test results showed that the COD removal rate was 90.8%, the TN removal rate was 77.5%, the TP removal rate was 79.2%, the sludge reduction rate was -3%, and the sludge volume increased slightly.

[0073] Comparative Example 3 The difference from Example 1 is that the water treatment carrier of the sludge hydrothermal carbonization slurry is replaced with the same sludge hydrothermal carbonization slurry as in Example 1, while the rest is the same as in Example 1.

[0074] The test results showed that the COD removal rate was 89.5%, the TN removal rate was 75.2%, the TP removal rate was 80.1%, and the sludge reduction rate was 5%.

[0075] Comparative Example 4 The difference from Example 1 is that active magnesium oxide is replaced with magnesium hydroxide, and everything else is the same as in Example 1.

[0076] The test results showed that the COD removal rate was 90.2%, the TN removal rate was 76.8%, the TP removal rate was 82.5%, and the sludge reduction rate was 8%.

[0077] The test results and comprehensive evaluation of the products obtained after running in the examples and comparative examples are shown in Table 2.

[0078] Table 2. Test results and comprehensive evaluation of wastewater treatment after operation in the examples and comparative examples.

[0079] Systematic analysis of the examples and comparative examples demonstrates that the technology of this invention has significant comprehensive advantages. Under standard conditions (Example 1), the system achieved COD, TN, and TP removal rates of 94.2%, 84.1%, and 96.5%, respectively, with a sludge reduction of 19%, comprehensively outperforming the carrier-free control (Comparative Example 1) and commercially available packing materials (Comparative Example 2). Under high-feed enhanced conditions (Examples 2 and 4), the TP removal rate approached 99%, and the sludge reduction reached 30%, highlighting the outstanding effect of the carrier in deep phosphorus removal and sludge source reduction.

[0080] The technological advantage stems from a triple synergistic mechanism of "physical adsorption-chemical enhancement-biological immobilization": the porous structure of biochar provides a carrier for microbial attachment; activated magnesium oxide slowly releases Mg. 2+ The chemical denitrification and phosphorus removal processes were enhanced, and the pH was buffered. Ultrasonic treatment improved dispersibility and biocompatibility. Compared with the unmodified slurry (Comparative Example 3) and the magnesium hydroxide alternative (Comparative Example 4), the introduction of active magnesium oxide is the key innovation.

[0081] The carrier of this invention can be directly added to anaerobic / anoxic zones without process modification, and combines technical feasibility, economic efficiency and engineering applicability, providing an efficient integrated solution for sludge resource utilization and wastewater upgrading.

[0082] Although preferred embodiments of the invention have been shown and described, it is conceivable that those skilled in the art can devise various modifications to the invention within the spirit and scope of the appended claims.

Claims

1. A method for preparing a water treatment carrier for sludge hydrothermal carbonization slurry, characterized in that, Includes the following steps: Sludge hydrothermal carbonization slurry and activated magnesium oxide are mixed and ultrasonically treated to obtain sludge hydrothermal carbonization slurry water treatment carrier.

2. The method for preparing the sludge hydrothermal carbonization slurry water treatment carrier according to claim 1, characterized in that, The preparation of the sludge hydrothermal carbonization slurry includes: The sludge undergoes a hydrothermal carbonization reaction under an acidic catalyst to obtain a hydrothermal carbonization sludge slurry. The sludge has a moisture content of 75% to 90%. The organic matter content in the sludge is 30% to 80%; The hydrothermal carbonization reaction is carried out in a closed reactor; the temperature of the hydrothermal carbonization reaction is 160~220℃, the pressure of the hydrothermal carbonization reaction is 1~3MPa, and the time of the hydrothermal carbonization reaction is 2~6h. The acidic catalyst for the hydrothermal carbonization reaction is at least one of sulfuric acid, hydrochloric acid, oxalic acid, and citric acid. The mass ratio of the sludge to the acidic catalyst is 100:(1~5).

3. The method for preparing the sludge hydrothermal carbonization slurry water treatment carrier according to claim 1, characterized in that, The mass ratio of the sludge hydrothermal carbonization slurry to the activated magnesium oxide is 100:(0.1~1).

4. The method for preparing the sludge hydrothermal carbonization slurry water treatment carrier according to claim 1, characterized in that, The particle size of the active magnesium oxide is 100~500 mesh.

5. The method for preparing the sludge hydrothermal carbonization slurry water treatment carrier according to claim 1, characterized in that, The frequency of the ultrasonic treatment is 20~100Hz, and the duration of the ultrasonic treatment is 10~30min.

6. A sludge hydrothermal carbonization slurry water treatment carrier prepared by the method of any one of claims 1 to 5.

7. The application of the sludge hydrothermal carbonization slurry water treatment carrier as described in claim 6 in wastewater treatment.

8. The application of the sludge hydrothermal carbonization slurry water treatment carrier according to claim 7 in wastewater treatment, characterized in that, The application includes the following steps: The sludge hydrothermal carbonization slurry water treatment carrier was added to the anaerobic reaction zone and the anoxic reaction zone of the wastewater treatment system, respectively. The wastewater treatment system is a biological nitrogen and phosphorus removal process with anaerobic, anoxic, and aerobic zones.

9. The application of the sludge hydrothermal carbonization slurry water treatment carrier according to claim 8 in wastewater treatment, characterized in that, The dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anaerobic reaction zone is 0.05‰~0.5‰ of the influent volume of the wastewater treatment system.

10. The application of the sludge hydrothermal carbonization slurry water treatment carrier according to claim 8 in wastewater treatment, characterized in that, The dosage of the sludge hydrothermal carbonization slurry water treatment carrier in the anoxic reaction zone is 0.01‰ to 0.1‰ of the influent volume of the wastewater treatment system.

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