Methods for combining magnetic powder with hydroxyl-coated surfaces with activated sludge

Abstract

The application discloses a method for combining magnetic powder with surface-attached hydroxyl groups and activated sludge, and comprises the following steps: treating the magnetic powder with a hydroxyl donor to obtain magnetic powder with surface-attached hydroxyl groups; mixing the magnetic powder with surface-attached hydroxyl groups with activated sludge, and mechanically stirring for 15-20 minutes; adding the obtained magnetic sludge mixture into an activated sludge aerobic tank system; detecting the concentration of the magnetic powder in the activated sludge after one cycle; the method takes advantage of the easy combination of the magnetic powder with surface-attached hydroxyl groups and the activated sludge, reduces the loss caused by incomplete combination of the magnetic powder, and makes the magnetic powder and the activated sludge better combined, so that the operation process of the combination of the magnetic powder and the activated sludge is optimized; meanwhile, the process of attaching the hydroxyl groups to the surface of the magnetic powder is relatively simple, only needs to add hydrogen peroxide solution or sodium hydroxide solution, and the hydrogen peroxide has the self-decomposition characteristic or the sodium hydroxide is easy to dissolve in water, so that the washing process of the magnetic powder is simplified.

Description

Technical Field

[0001] This invention relates to the field of magnetic sludge mixing technology, specifically to a method for combining magnetic powder with hydroxyl groups attached to its surface with activated sludge. Background Technology

[0002] Currently, most traditional methods of combining magnetic powder with activated sludge employ mechanical stirring, with a few adding chemicals to promote mixing during the mechanical stirring process. However, traditional methods suffer from drawbacks such as insufficient mixing of the magnetic sludge, complex stirring processes, and the risk of insufficiently mixed magnetic sludge settling and being lost from the aerobic tank, thus affecting the experimental progress and duration.

[0003] To address this issue, this invention researched and developed a method for combining magnetic powder with surface-attached hydroxyl groups with activated sludge. First, the attachment process of surface hydroxyl groups is relatively simple, and the magnetic powder is easy to wash clean. Second, the attachment of surface hydroxyl groups on the magnetic powder allows for a more thorough bonding between the magnetic powder and the activated sludge. Finally, it reduces stirring time, minimizes the loss of magnetic powder in the aerobic tank, and reduces operating costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for bonding magnetic powder with hydroxyl groups attached to its surface to activated sludge. This invention utilizes hydroxyl groups to enhance the bonding between magnetic powder and activated sludge; other methods for increasing the hydroxyl groups on the surface of magnetic powder are similar.

[0005] The technical solution of the present invention is as follows:

[0006] A method for combining magnetic powder with hydroxyl groups attached to its surface with activated sludge includes:

[0007] Step 1: Treat the magnetic powder with a hydroxyl donor to obtain magnetic powder with hydroxyl groups attached to its surface;

[0008] The magnetic powder is selected from iron oxide magnetic powder or iron-silicon-aluminum magnetic powder;

[0009] The hydroxyl donor is selected from hydrogen peroxide solution or sodium hydroxide solution;

[0010] When the hydroxyl donor is hydrogen peroxide solution, the specific treatment method is as follows: Mix the magnetic powder and hydrogen peroxide solution, soak for 3-7 days, stirring for 1-2 minutes every 2-3 days during the soaking period. After soaking, wash with water to obtain magnetic powder with hydroxyl groups attached to the surface; preferably, the mass fraction of hydrogen peroxide solution is 30%; preferably, the mass ratio of magnetic powder to hydrogen peroxide solution is 1:0.5-1:1; after soaking, wash the strong oxidant on the surface of the magnetic powder with water, the specific method is as follows: add water to the magnetic powder, stir, precipitate, pour out the washing solution, repeat washing until no bubbles are generated when manganese dioxide is added to the washing solution, to obtain magnetic powder with hydroxyl groups attached to the surface;

[0011] When the hydroxyl donor is sodium hydroxide solution, the specific processing method is as follows: First, heat the sodium hydroxide solution to 50-60℃, then add magnetic powder, maintain the temperature and soak for 6-8 hours. After soaking, wash with water to obtain magnetic powder with hydroxyl groups attached to the surface; preferably, the mass fraction of sodium hydroxide solution is 10%; preferably, the mass ratio of magnetic powder to sodium hydroxide solution is 1:0.5-1:1; after soaking, wash the strong alkali on the surface of the magnetic powder with water, the specific method is as follows: add water to the magnetic powder, stir, precipitate, pour out the washing liquid, repeat washing until the pH of the washing liquid is neutral, to obtain magnetic powder with hydroxyl groups attached to the surface;

[0012] Step 2: Mix the magnetic powder with hydroxyl groups attached to its surface with the activated sludge and mechanically stir for 15-20 minutes. Add the resulting magnetic sludge mixture to the activated sludge aerobic tank system. After one cycle of operation, test the concentration of magnetic powder in the activated sludge.

[0013] The specific operation and testing methods are as follows: the aerobic tank system temperature is 20-40℃, and the activated sludge aerobic tank volume is 27m³. 3 The dissolved oxygen (DO) level in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 / h, using actual wastewater, AO process (anaerobic-aerobic process), first facultative tank, then aerobic tank, and finally secondary sedimentation tank; after the aerobic tank system has been running for 7 days, take 1-3L of activated sludge from the aerobic tank, shear it in multiple batches in a shearing machine, then recover it with a 3000GS magnet, then filter and wash it with filter paper, finally dry it, weigh it, and calculate the magnetic powder concentration in the activated sludge. Repeat the above steps 2-3 times and calculate the average value.

[0014] The beneficial effects of this invention are:

[0015] Compared to traditional methods of mixing magnetic powder and activated sludge, this invention utilizes the advantage of magnetic powder with surface hydroxyl groups, which readily binds to activated sludge. This reduces losses due to incomplete bonding of magnetic powder, resulting in better integration between the two materials and optimizing the bonding process. Furthermore, the process of hydroxyl group adhesion on the magnetic powder surface is relatively simple, requiring only the addition of hydrogen peroxide or sodium hydroxide solution. The self-decomposing properties of hydrogen peroxide and the water-soluble nature of sodium hydroxide further simplify the washing process of the magnetic powder. Attached Figure Description

[0016] Figure 1 : Flowchart of the method for combining magnetic powder with hydroxyl groups attached to the surface of the present invention with activated sludge.

[0017] Figure 2 Infrared spectrum of hydroxyl groups on the surface of magnetic powder (hydrogen peroxide) in this invention.

[0018] Figure 3 Infrared spectrum of hydroxyl groups on the surface of magnetic powder (sodium hydroxide) in this invention. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0020] In the following embodiments,

[0021] The ferric oxide magnetic powder comes from Jinan 58 Research Metals and has a particle size of 100 micrometers.

[0022] The iron-silicon-aluminum magnetic powder comes from Shijiazhuang Liangfeng Alloy Coating Powder, with a particle size of 100 micrometers;

[0023] The activated sludge comes from the Sanyuan Group's centralized wastewater treatment center;

[0024] The actual wastewater comes from the Sanyuan Group's centralized wastewater treatment center.

[0025] Example 1:

[0026] (1) Add 5kg of ferric oxide magnetic powder to a 30L plastic bucket. Add the magnetic powder and 30% hydrogen peroxide solution at a mass ratio of 1:0.5. Soak for 3 days, and then stir until no large amount of bubbles are generated.

[0027] (2) After soaking, wash the magnetic powder, add 5L of water to the magnetic powder, stir, let it settle, pour out the washing liquid, and repeat the washing until no bubbles are generated when 0.5g of manganese dioxide is added to the washing liquid, and 5kg of pretreated magnetic powder is obtained.

[0028] (3) Add 5kg of pretreated magnetic powder to a plastic bucket containing 500L of activated sludge, stir mechanically for 15 minutes, and then add it evenly to the aerobic tank.

[0029] (4) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The system uses actual wastewater and an AO process, consisting of an anaerobic tank, an aerobic tank, and a secondary sedimentation tank. After 7 days of operation, 3L of activated sludge from the aerobic tank is taken and sheared multiple times in a shear mill. The sludge is then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder in the activated sludge is calculated. This process is repeated three times, and the average value is calculated. The actual concentration of magnetic powder in the activated sludge is compared with the theoretically added concentration to determine the binding effect between the magnetic powder and the activated sludge.

[0030] Comparative Example 1:

[0031] (1) Add 5 kg of magnetic powder that has not been pretreated with hydrogen peroxide to a plastic bucket containing 500 L of activated sludge, stir mechanically for 15 min, and then add it evenly to the aerobic tank.

[0032] (2) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The wastewater was treated using the actual AO process, consisting of an anaerobic tank, an aerobic tank, and a secondary sedimentation tank. After the aerobic tank system had been running for 7 days, 3L of activated sludge was taken from the aerobic tank and sheared in multiple batches using a shear mill. The sludge was then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder before and after its addition was calculated. This process was repeated three times, and the average value was calculated.

[0033] The magnetic powder concentrations are shown in Table 1.

[0034] Table 1

[0035]

[0036] Example 2:

[0037] (1) Add 5kg of ferric oxide magnetic powder to a 30L plastic bucket. Add the magnetic powder and 30% hydrogen peroxide solution in a mass ratio of 1:1. Soak for 3 days, and then stir until no large amount of bubbles are generated.

[0038] (2) After soaking, wash the magnetic powder, add 5L of water to the magnetic powder, stir, let it settle, pour out the washing liquid, and repeat the washing until no bubbles are generated when 0.5g of manganese dioxide is added to the washing liquid, and 5kg of pretreated magnetic powder is obtained.

[0039] (3) Add 5kg of pretreated magnetic powder to a plastic bucket containing 500L of activated sludge, stir mechanically for 15 minutes, and then add it evenly to the aerobic tank.

[0040] (4) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The wastewater was treated using the actual AO process, with a sequence of facultative anaerobic tank, aerobic tank, and secondary sedimentation tank. After 7 days of operation of the aerobic tank system, 3L of activated sludge was taken from the aerobic tank and sheared in multiple batches using a shear mill. The sludge was then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder in the activated sludge was calculated. This process was repeated three times, and the average value was calculated.

[0041] Comparative Example 2:

[0042] The steps are the same as in Example 2, with the mechanical stirring time in step (3) being 45 min as a comparison.

[0043] The magnetic powder concentrations are shown in Table 2.

[0044] Table 2

[0045]

[0046] Example 3:

[0047] (1) Add 5kg of ferric oxide magnetic powder to a 30L plastic bucket. Add the magnetic powder and 30% hydrogen peroxide solution at a mass ratio of 1:0.5. Soak for 7 days, and then stir until no large amount of bubbles are generated.

[0048] (2) After soaking, wash the magnetic powder, add 5L of water to the magnetic powder, stir, let it settle, pour out the washing liquid, and repeat the washing until no bubbles are generated when 0.5g of manganese dioxide is added to the washing liquid, and 5kg of pretreated magnetic powder is obtained.

[0049] (3) Add 5kg of pretreated magnetic powder to a plastic bucket containing 500L of activated sludge, stir mechanically for 15 minutes, and then add it evenly to the aerobic tank.

[0050] (4) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The wastewater was treated using the actual AO process, with a sequence of facultative anaerobic tank, aerobic tank, and secondary sedimentation tank. After 7 days of operation of the aerobic tank system, 3L of activated sludge was taken from the aerobic tank and sheared in multiple batches using a shear mill. The sludge was then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder in the activated sludge was calculated. This process was repeated three times, and the average value was calculated.

[0051] Comparative Example 3:

[0052] The steps are the same as in Example 3, except that the magnetic powder is replaced with iron-silicon-aluminum magnetic powder for comparison.

[0053] The magnetic powder concentrations are shown in Table 3.

[0054] Table 3

[0055]

[0056] Example 4:

[0057] (1) Magnetic powder and 10% sodium hydroxide aqueous solution are added at a mass ratio of 1:0.5. First, the sodium hydroxide solution is heated to 50°C, and then 5 kg of ferric oxide magnetic powder is added. The temperature is maintained and the solution is soaked for 6 hours.

[0058] (2) After soaking, wash the magnetic powder, add 5L of water to the magnetic powder, stir, let it settle, pour out the washing liquid, and repeat the washing until the pH of the washing liquid is neutral, and obtain 5kg of pretreated magnetic powder.

[0059] (3) Add 5kg of pretreated magnetic powder to a plastic bucket containing 500L of activated sludge, stir mechanically for 15 minutes, and then add it evenly to the aerobic tank.

[0060] (4) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The system uses actual wastewater and an AO process, consisting of an anaerobic tank, an aerobic tank, and a secondary sedimentation tank. After 7 days of operation, 3L of activated sludge from the aerobic tank is taken and sheared multiple times in a shear mill. The sludge is then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder in the activated sludge is calculated. This process is repeated three times, and the average value is calculated. The actual concentration of magnetic powder in the activated sludge is compared with the theoretically added concentration to determine the binding effect between the magnetic powder and the activated sludge.

[0061] Comparative Example 4:

[0062] (1) Add 5 kg of magnetic powder that has not been pretreated with sodium hydroxide solution to a plastic bucket containing 500 L of activated sludge, stir mechanically for 15 min, and then add it evenly to the aerobic tank.

[0063] (2) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The wastewater was treated using the actual AO process, consisting of an anaerobic tank, an aerobic tank, and a secondary sedimentation tank. After the aerobic tank system had been running for 7 days, 3L of activated sludge was taken from the aerobic tank and sheared in multiple batches using a shear mill. The sludge was then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder before and after its addition was calculated. This process was repeated three times, and the average value was calculated.

[0064] The magnetic powder concentrations are shown in Table 4.

[0065] Table 4

[0066]

[0067] Example 5:

[0068] (1) Add magnetic powder and 10% sodium hydroxide aqueous solution in a mass ratio of 1:1. First, heat the sodium hydroxide solution to 50°C, then add 5 kg of ferric oxide magnetic powder and maintain the temperature for soaking for 6 hours.

[0069] (2) After soaking, wash the magnetic powder, add 5L of water to the magnetic powder, stir, let it settle, pour out the washing liquid, and repeat the washing until the pH of the washing liquid is neutral, and obtain 5kg of pretreated magnetic powder.

[0070] (3) Add 5kg of pretreated magnetic powder to a plastic bucket containing 500L of activated sludge, stir mechanically for 15 minutes, and then add it evenly to the aerobic tank.

[0071] (4) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The wastewater was treated using the actual AO process, with a sequence of facultative anaerobic tank, aerobic tank, and secondary sedimentation tank. After 7 days of operation of the aerobic tank system, 3L of activated sludge was taken from the aerobic tank and sheared in multiple batches using a shear mill. The sludge was then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder in the activated sludge was calculated. This process was repeated three times, and the average value was calculated.

[0072] Comparative Example 5:

[0073] The steps are the same as in Example 5, with the mechanical stirring time in step (3) being 45 min as a comparison.

[0074] The magnetic powder concentrations are shown in Table 5.

[0075] Table 5

[0076]

[0077]

[0078] Example 6:

[0079] (1) Add magnetic powder and 10% sodium hydroxide aqueous solution at a mass ratio of 1:0.5. First, heat the sodium hydroxide solution to 50°C, then add 5 kg of ferric oxide magnetic powder and maintain the temperature for soaking for 8 hours.

[0080] (2) After soaking, wash the magnetic powder, add 5L of water to the magnetic powder, stir, let it settle, pour out the washing liquid, and repeat the washing until the pH of the washing liquid is neutral, and obtain 5kg of pretreated magnetic powder.

[0081] (3) Add 5kg of pretreated magnetic powder to a plastic bucket containing 500L of activated sludge, stir mechanically for 15 minutes, and then add it evenly to the aerobic tank.

[0082] (4) The temperature of the aerobic tank system is 20℃-40℃, and the volume of the activated sludge aerobic tank is 27m³. 3 The DO value in the aerobic tank is maintained at 2-3 mg / L, and the influent flow rate is 1 m³ / L. 3 The wastewater was treated using the actual AO process, with a sequence of facultative anaerobic tank, aerobic tank, and secondary sedimentation tank. After 7 days of operation of the aerobic tank system, 3L of activated sludge was taken from the aerobic tank and sheared in multiple batches using a shear mill. The sludge was then recovered using a 3000GS magnet, filtered through filter paper, washed, dried, and weighed. The concentration of magnetic powder in the activated sludge was calculated. This process was repeated three times, and the average value was calculated.

[0083] Comparative Example 6:

[0084] The steps were the same as in Example 6, except that the magnetic powder was replaced with iron-silicon-aluminum magnetic powder for comparison.

[0085] The magnetic powder concentrations are shown in Table 6.

[0086] Table 6

[0087]

Claims

1. A method for combining surface hydroxyl-attached magnetic powder with activated sludge, characterized by, The method comprises: Step 1, treating the magnetic powder with a hydroxyl donor to obtain magnetic powder with surface-attached hydroxyl groups; Step 2, mixing the magnetic powder with surface-attached hydroxyl groups with activated sludge, mechanically stirring for 15-20 min, adding the obtained magnetic sludge mixture into an activated sludge aerobic tank system, detecting the concentration of the magnetic powder in the activated sludge after running for a cycle.

2. The method for binding the surface-attached hydroxyl group-containing magnetic powder to the activated sludge according to claim 1, wherein In step 1, the magnetic powder is selected from ferroferric oxide magnetic powder or iron-silicon-aluminum magnetic powder.

3. The method of claim 1, wherein the surface-attached hydroxyl group magnetic powder is combined with activated sludge. In step 1, the hydroxyl donor is selected from hydrogen peroxide solution or sodium hydroxide solution.

4. The method of claim 3, wherein the surface-attached hydroxyl group magnetic powder is combined with activated sludge. When the hydroxyl donor is hydrogen peroxide solution, the method for treating the magnetic powder with the hydroxyl donor is as follows: mixing the magnetic powder with the hydrogen peroxide solution, soaking for 3-7 days, stirring for 1-2 min every 2-3 days during the soaking period, washing the magnetic powder with water after the soaking is completed to obtain the magnetic powder with surface-attached hydroxyl groups. The mass fraction of the hydrogen peroxide solution is 30%. The mass ratio of the magnetic powder to the hydrogen peroxide solution is 1:0.5-1:

1. After the soaking is completed, the strong oxidant on the surface of the magnetic powder is washed with water, and the method is as follows: adding water to the magnetic powder, stirring, precipitating, pouring out the washing liquid, repeating the washing until no bubbles are generated when manganese dioxide is added to the washing liquid, and obtaining the magnetic powder with surface-attached hydroxyl groups.

5. The method of claim 3, wherein the surface-attached hydroxyl group magnetic powder is combined with activated sludge. When the hydroxyl donor is sodium hydroxide solution, the method for treating the magnetic powder with the hydroxyl donor is as follows: first heating the sodium hydroxide solution to 50-60℃, then adding the magnetic powder, maintaining the temperature for 6-8 h, and washing the magnetic powder with water after the soaking is completed to obtain the magnetic powder with surface-attached hydroxyl groups. The mass fraction of the sodium hydroxide solution is 10%. The mass ratio of the magnetic powder to the sodium hydroxide solution is 1:0.5-1:

1. After the soaking is completed, the strong base on the surface of the magnetic powder is washed with water, and the method is as follows: adding water to the magnetic powder, stirring, precipitating, pouring out the washing liquid, repeating the washing until the pH of the washing liquid is neutral, and obtaining the magnetic powder with surface-attached hydroxyl groups.

6. The method of claim 1, wherein the surface-attached hydroxyl group magnetic powder is combined with activated sludge. In step 2, the detection method is as follows: the temperature of aerobic tank system is 20-40℃, the volume of activated sludge aerobic tank is 27m 3 , the DO value of aerobic tank is maintained at 2-3mg / L, the influent quantity is 1m 3 / h, the actual wastewater is used, the AO process is used, the facultative tank is used first, then the aerobic tank, and finally the secondary sedimentation tank; after the aerobic tank system runs for 7 days, 1-3L of activated sludge in the aerobic tank is taken, cut into multiple times in the shearing machine, recovered by a 3000GS magnet, filtered and washed by filter paper, finally dried, weighed, and the concentration of magnetic powder in the activated sludge is calculated, and the above step 2-3 is repeated to obtain the average value.

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