Preparation method of sludge biochar material and application of sludge biochar material in urban sewage treatment

Abstract

The invention discloses a preparation method of a sludge biochar material and application of the sludge biochar material in urban sewage treatment. The method comprises the following steps: 1, mixing sludge discharged from an aerobic tank with fly ash, and carrying out anaerobic carbonization treatment to obtain sludge biochar; 2, loading manganese element modified sludge biochar by using a chemical precipitation method; 3, conditioning the sludge, adding cationic polyacrylamide and potassium ferrate, carrying out secondary stirring treatment, and then carrying out pyrolysis; 4, adding aluminum hydroxide and carborane to carry out segmented heat treatment, and carrying out high-temperature heat treatment with copper hydroxide to further improve the pore structure; 5, the final sludge modified biochar material is obtained through ozone activation. The sludge biochar material prepared by the invention has a developed pore structure and high porosity, is especially suitable for constructed wetland devices, and can greatly improve the removal performance of COD, TN and TP in water. The material is suitable for urban sewage treatment, and has important economic value and social significance.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method for preparing a sludge biochar material and application of the material in urban sewage treatment. Background Art

[0002] With the growth of the global population and the accelerated development of industrial activities, water shortage and water pollution problems are becoming increasingly serious. As one of the main sources of water pollution, the effective treatment of urban sewage is crucial to protecting the ecological environment and human health. Although traditional sewage treatment methods such as activated sludge method are widely used in sewage treatment plants, they have disadvantages such as high energy consumption, large land area, and limited treatment efficiency. In addition, a large amount of residual sludge generated during sewage treatment contains rich organic matter, nutrients and other valuable substances. If these residual sludges are directly discharged into the environment, they will cause secondary pollution. Therefore, exploring an effective way to recycle sludge resources will not only help reduce environmental pollution, but also achieve the recycling of resources.

[0003] In recent years, biochar has been widely studied as a new type of environmentally friendly material due to its good physical and chemical properties. Biochar can be prepared by pyrolysis of biomass (such as crop residues, forest waste, urban organic waste, etc.). It has a porous structure and can effectively adsorb heavy metals, organic pollutants and nutrients. In addition, biochar can also be used as a soil conditioner to promote plant growth. Sludge biochar is a biochar product obtained by pyrolysis of residual sludge. Compared with traditional biochar, sludge biochar usually contains more mineral components, which makes it have unique advantages in certain application fields. Although sludge biochar materials have certain application potential, there are still some key issues that restrict its widespread application, such as underdeveloped pore structure, poor adsorption performance, poor stability and complex preparation process. Therefore, it is of great theoretical significance and practical application value to develop a simple and efficient method to prepare high-performance sludge biochar materials and apply them to urban sewage treatment. Summary of the invention

[0004] The invention discloses a method for preparing sludge biochar material, comprising the following steps:

[0005] (1) mixing the sludge discharged from the aerobic tank with fly ash and then subjecting it to anaerobic carbonization treatment to obtain sludge biochar;

[0006] (2) loading manganese element to modify the sludge biochar by chemical precipitation method;

[0007] (3) conditioning the sludge, adding cationic polyacrylamide and potassium ferrate for secondary stirring treatment, and then performing pyrolysis;

[0008] (4) adding aluminum hydroxide and carborane for staged heat treatment and high temperature heat treatment with copper hydroxide to further improve the pore structure;

[0009] (5) The final sludge-modified biochar material is obtained through ozone activation.

[0010] Technical issues

[0011] The present invention aims to provide a method for preparing a simple and low-cost sludge biochar material, and the application of the material in urban sewage treatment to improve sewage treatment efficiency and reduce costs.

[0012] Technical Solution

[0013] In order to solve the above technical problems, the present invention proposes a method for preparing sludge biochar material, comprising the following steps:

[0014] (1) mixing the sludge discharged from the aerobic tank with fly ash and then subjecting it to anaerobic carbonization treatment to obtain sludge biochar;

[0015] (2) loading manganese element to modify the sludge biochar by chemical precipitation method;

[0016] (3) conditioning the sludge, adding cationic polyacrylamide and potassium ferrate for secondary stirring treatment, and then performing pyrolysis;

[0017] (4) adding aluminum hydroxide and carborane for staged heat treatment and high temperature heat treatment with copper hydroxide to further improve the pore structure;

[0018] (5) The final sludge-modified biochar material is obtained through ozone activation.

[0019] Technical effects and advantages:

[0020] In the above technical scheme, the sludge biochar material modified by loading manganese element has a developed pore structure and high porosity, which improves the adsorption performance, especially has a good adsorption effect on pollutants such as COD, TN, TP in sewage. The preparation method proposed in the present invention is simple and efficient, reducing energy consumption and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following will be combined with the accompanying drawings of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Figure 1 It is the surface microstructure diagram of the present invention;

[0023] Figure 2 This is the element distribution diagram of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Embodiment 1:

[0026] This embodiment provides a simple and efficient method for preparing sludge biochar material and its application in urban sewage treatment.

[0027] 1. Preparation of sludge biochar

[0028] 1. Raw material preparation: Collect the residual sludge from the aerobic tank of the sewage treatment plant and prepare fly ash as an additive to improve the physical and chemical properties of sludge biochar.

[0029] 2. Mixing and molding: Mix the remaining sludge and fly ash in a mass ratio of 1:1. Add an appropriate amount of water (about 30% of the dry matter mass) and stir well. Use manual or mechanical methods to knead the mixture into spherical particles with a diameter of about 1 cm.

[0030] 3. Anaerobic carbonization treatment: The formed spherical particles are placed in a sealed container and subjected to anaerobic carbonization treatment at 450°C for 2 hours. After the treatment, the particles are naturally cooled to room temperature to obtain preliminary sludge biochar particles.

[0031] 4. Metal element load:

[0032] Prepare 0.5 mol / L manganese sulfate (MnSO4) solution. Add 5 mL of manganese sulfate solution to each gram of sludge biochar particles, stir evenly and let stand for 24 hours. Wash with deionized water several times until the washing solution is neutral, and then dry at 105°C for 12 hours.

[0033] 5. Conditioning and pyrolysis: Add 0.1 g of cationic polyacrylamide (CPAM) and 0.2 g of potassium ferrate (K2FeO4) to each gram of manganese-loaded sludge biochar and stir evenly. Pyrolyze the mixture at 500°C for 40 minutes.

[0034] 6. Sectional heat treatment and high temperature heat treatment:

[0035] The pyrolyzed material was added to a mixture containing 1% by mass aluminum hydroxide and 0.5% by mass carborane. The mixture was heat treated in stages at 400°C for 30 minutes. Subsequently, 0.5% by mass copper hydroxide (Cu(OH)2) was added, and a high temperature heat treatment was performed at 650°C for 40 minutes.

[0036] 7. Ozone activation:

[0037] The heat-treated material was activated for 1.5 hours under the condition of ozone concentration of 300 mg / L. After activation, it was dried again at 105°C for 12 hours to obtain the finished product.

[0038] Embodiment 2:

[0039] This example is an optimization experiment conducted on the basis of Example 1, the main purpose of which is to further improve the adsorption performance and stability of the material.

[0040] The sludge biochar preparation process is the same as Example 1 except that the stage conditions of segmented heat treatment and high-temperature heat treatment (segmented heat treatment at 450°C for 40 minutes or high-temperature heat treatment at 700°C for 40 minutes) and ozone activation (ozone concentration is 400 mg / L, activation time is 2 hours) are different.

[0041] In summary, the sludge biochar obtained in Example 1 and Example 2 was subjected to performance tests, including: pore structure analysis (determining the specific surface area and pore size distribution of the finished product by nitrogen adsorption method), adsorption performance evaluation (adding the finished product to simulated wastewater containing a certain concentration of pollutants (such as ammonia nitrogen and phosphate) to examine its removal efficiency of pollutants) and stability test (placing the finished product in a simulated wastewater environment to observe its long-term stability)

[0042] By comparing the results of Example 1 and Example 2, the optimal combination of process parameters can be determined to achieve the best adsorption performance and stability.

Claims

1. A method for preparing sludge biochar material, comprising the following steps: (1) mixing the sludge discharged from the aerobic tank with fly ash and then subjecting it to anaerobic carbonization treatment to obtain sludge biochar; (2) loading manganese element to modify the sludge biochar by chemical precipitation method; (3) conditioning the sludge, adding cationic polyacrylamide and potassium ferrate for secondary stirring treatment, and then performing pyrolysis; (4) adding aluminum hydroxide and carborane for staged heat treatment and high temperature heat treatment with copper hydroxide to further improve the pore structure; (5) The final sludge-modified biochar material is obtained through ozone activation.

2. The method for preparing sludge biochar material according to claim 1, characterized in that: The temperature range of the anaerobic carbonization treatment is 400° C. to 600° C., and the duration is 1 to 3 hours.

3. The method for preparing sludge biochar material according to claim 1, characterized in that: The specific process of loading manganese element by chemical precipitation method includes using manganese sulfate solution and sodium carbonate solution to carry out precipitation reaction.

4. The method for preparing sludge biochar material according to claim 1, characterized in that: The concentration of the cationic polyacrylamide is 0.05% to 0.5%, and the concentration of potassium ferrate is 0.1% to 1.0%.

5. The method for preparing sludge biochar material according to claim 1, characterized in that: The pyrolysis temperature is 300° C. to 750° C., and the pyrolysis time is 50 to 70 minutes.

6. The method for preparing sludge biochar material according to claim 1, characterized in that: The temperatures of the staged heat treatment are 300° C. to 500° C. and 600° C. to 750° C., respectively, and the duration of each stage is 30 to 60 minutes.

7. The method for preparing sludge biochar material according to claim 1, characterized in that: The ozone concentration of the ozone activation treatment is 100 mg / L to 500 mg / L, and the activation time is 1 to 2 hours.

8. The use of the sludge biochar material in urban sewage treatment according to any one of claims 1 to 7, characterized in that: The sludge biochar material is used in an artificial wetland device and can significantly improve the removal performance of COD, TN and TP in water quality.

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