Superconducting magnetization Fenton technology for sewage and wastewater treatment

Abstract

The invention discloses a superconducting magnetization Fenton technology for sewage and wastewater treatment, and relates to the technical field of sewage treatment, sewage is firstly magnetized by a superconducting magnet, and then acid regulation, dosing, reaction, neutralization, coagulation and precipitation treatment are sequentially carried out. Experimental data show that common Fenton has a certain removal effect on pollutants under specific conditions, and the superconducting magnetization Fenton technology has remarkable advantages. When the pH (Potential of Hydrogen) is 3.0 to 5.5, the COD (Chemical Oxygen Demand) removal rate reaches 54.77 percent to 65.28 percent; when m (H2O2) / m (COD) is 0.5 to 3, the removal rate is 61.54 percent to 71.84 percent; and when the ratio of n (H2O2) to n (Fe < 2 + >) is 2-6, the removal rate is 60.74%-70.80%. Compared with the traditional Fenton technology, the technology has the advantages that the COD (Chemical Oxygen Demand) removal rate is greatly increased, the dosage of chemicals is reduced, the sludge amount is reduced by more than 30%, the reaction rate is increased by 20-40%, the pH reaction range is widened to 2-6, high-salt and high-toxicity wastewater can be effectively treated, and the technology has a wide application prospect in the field of sewage treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically to a superconducting magnetization Fenton technology for sewage and wastewater treatment. Background Art

[0002] The Fenton oxidation technology is an advanced oxidation process (AOPs) based on hydroxyl radicals (·OH). It destroys the organic structure through strong oxidizing radicals to achieve the efficient degradation of refractory pollutants. Its core principle is the Fenton reaction, that is, the catalytic reaction of ferrous ions (Fe 2+ ) and hydrogen peroxide (H2O2) under acidic conditions.

[0003] Traditional Fenton technology (the first generation): Based on homogeneous reaction (Fe 2+ catalyzing H2O2 to generate ·OH), it has the advantages of strong oxidation ability, simple operation, and fast reaction speed. However, due to the high storage and transportation cost of H2O2, narrow pH response range, low COD removal rate, large amount of sludge production, and high requirements for reaction equipment, etc., its application in practical engineering is limited.

[0004] Fluidized bed Fenton technology (the second generation): Introduces heterogeneous reaction (such as FeOOH filler), and improves the production of hydroxyl radicals through solid-liquid interface catalysis, reducing the dosage of chemicals and the amount of sludge. However, the filler needs to be replaced regularly to avoid caking, and the operation and maintenance cost is relatively high.

[0005] Existing technical problems:

[0006] 1. Sludge generation and secondary pollution

[0007] Traditional Fenton reaction generates a large amount of iron sludge (Fe(OH)3), which requires additional sludge treatment equipment, increasing costs; improper disposal of iron sludge is likely to cause secondary pollution.

[0008] Excessive hydrogen peroxide may lead to floating sludge and increased effluent color (such as yellowish-brown).

[0009] 2. High operation cost

[0010] Large chemical consumption: The dosing ratio of H2O2 and Fe 2+ needs to be optimized through experiments, and excessive dosing leads to increased costs.

[0011] Risk of equipment corrosion: Strong acidic conditions (pH < 3) and the strong oxidizing property of H2O2 are likely to corrode the reactor and pipelines, and corrosion-resistant materials need to be used, further driving up the investment cost.

[0012] 3. Harsh operating conditions

[0013] pH control is sensitive: Traditional Fenton requires strict regulation of pH to 3 - 4. If it exceeds the range, it will cause Fe2+ Deactivation affects the reaction efficiency.

[0014] Reaction time and temperature limitations: Low temperature (<15°C) may reduce the reaction rate, while high temperature accelerates the ineffective decomposition of H2O2; the reaction time needs to be adjusted according to the water quality, lacking flexibility.

[0015] 4. Low utilization rate of hydroxyl radicals

[0016] The lifetime of ·OH is extremely short (nanosecond level), and it is easy to react with H2O2 to generate inefficient ·OOH, resulting in waste of oxidants.

[0017] When the pollutant concentration is low (such as COD < 100 mg / L), it is difficult for ·OH to contact the organic matter surrounded by water molecules, and excessive chemical dosing is required.

[0018] 5. Limitations in technical applicability

[0019] The treatment effect on high-salt wastewater fluctuates greatly: salts may inhibit the generation of free radicals or interfere with the reaction path.

[0020] It is difficult to stably meet the effluent COD standard: in the literature, it is often claimed that the COD can be reduced to 0 mg / L, but in actual engineering, it can only be reduced to about 50 mg / L, making it difficult to meet strict discharge standards.

[0021] In view of this, this application is specifically proposed. Summary of the invention

[0022] The purpose of the present invention is to provide a superconducting magnetized Fenton technology for wastewater treatment to solve the problems mentioned in the above background technology.

[0023] To solve the above technical problems, a superconducting magnetized Fenton technology for wastewater treatment provided by the present invention includes the following steps:

[0024] Step 1: Magnetization stage: Open the inlet valve, make the water inlet pipe connected to the water inlet pump pass through the superconducting magnet, magnetize the water, and the magnetization is completed instantaneously (the time is in seconds);

[0025] Step 2: Acid adjustment stage: The magnetized water enters the acid adjustment area of the Fenton device; Start the stirrer in the acid adjustment area, put the pH probe into the wastewater to monitor the pH value in real time, add sulfuric acid to the wastewater to make the pH value drop between 3.0 - 4.5 to ensure the efficient progress of the oxidation reaction and improve the oxidation decomposition efficiency of pollutants; The mixing time should be ≥ 2 min to ensure that the pH regulator in the wastewater can be fully mixed and evenly distributed;

[0026] Step 3: Chemical dosing stage: Weigh an appropriate amount of ferrous sulfate heptahydrate and pre-dissolve it into a solution, and then add it to the wastewater; under continuous stirring, use a pipette or dropper to gradually add hydrogen peroxide solution drop by drop to the wastewater; control the dosing mass ratio of H2O2 to COD to be 1:1 to 3:1; control the molecular weight ratio of H2O2 to ferrous ions (Fe 2+ ) to be 1:1 to 9:1;

[0027] Step 4: Reaction stage: With the assistance of a stirrer, keep the solution mixed evenly to ensure that the oxidation reaction proceeds fully; a constant temperature device can be used to maintain the reaction system at 20 - 25°C, which helps to optimize the reaction efficiency and the generation of products; the reaction time is 10 - 30 min;

[0028] Step 5: Neutralization stage: After the reaction, continue to stir the wastewater and add sodium hydroxide solution drop by drop to the wastewater to gradually raise the pH value to about 7, and then stop adding the alkali; the purpose of this step is to adjust the pH value of the wastewater to neutral to meet specific application requirements or stabilize the chemical properties;

[0029] Step 6: Coagulation stage: Continue to stir the wastewater and add about 2 mg / L of anionic polyacrylamide (PAM); PAM acts as a coagulant, which helps to form flocs and accelerate the sedimentation of suspended solids; continue to stir for several minutes until a large amount of iron flocs are formed and grow;

[0030] Step 7: Sedimentation stage: Stop stirring and let the wastewater stand for sedimentation; the suspended solid particles sink by gravity to achieve the purpose of solid-liquid separation.

[0031] Furthermore, in the said Step 1, the magnetic field generated by the superconducting magnet can change the molecular sequence of pollutants in the sewage, cause the water molecules to rearrange along the direction of the magnetic field lines, and the water molecule clusters disintegrate.

[0032] Furthermore, in the said Step 3, the dosing amounts and ratios of ferrous sulfate heptahydrate and hydrogen peroxide solution are precisely controlled according to the COD content and water quality of the sewage.

[0033] Furthermore, in the said Step 7, the standing sedimentation time of the sewage is adjusted according to the content and properties of the suspended solids in the sewage to ensure full solid-liquid separation.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. For the traditional magnetic Fenton technology, that is, the ordinary permanent magnet (or electromagnetic) technology, the magnetic induction intensity < 1 T. This technical solution uses a superconducting magnetic field with a higher magnetic induction intensity (able to reach 2 - 6 T), a wider range, a greater magnetization effect on water, magnetizes the sewage to change the molecular sequence of pollutants, improves the utilization rate of hydroxyl radicals, and has a better treatment effect on pollutants.

[0036] 2. Reduction of iron sludge: The sludge volume is reduced by more than 30%, effectively reducing the cost of subsequent sludge treatment and the risk of secondary pollution.

[0037] 3. Reduction of chemical dosage: Compared with traditional Fenton, the chemical dosage is reduced by 20%-30%. While reducing the operating cost, it also reduces potential problems caused by excessive chemical dosage.

[0038] 4. Fast reaction rate: It is 20%-40% higher than traditional Fenton, greatly improving the efficiency of sewage treatment.

[0039] 5. Strong adaptability: It is applicable to high-salt and highly toxic wastewater, tolerates complex water quality fluctuations, and can operate stably under different water quality conditions.

[0040] 6. Wide pH reaction range: The pH reaction range is 2-6, while the pH reaction range of traditional Fenton is generally 3-4. The widened pH range makes this technology more flexible in practical applications.

[0041] 7. Energy conservation and environmental protection: Reducing the sludge volume and chemical dosage, reducing secondary pollution, meeting the requirements of environmental protection concepts and sustainable development. Description of the Drawings

[0042] Figure 1 It is a principle block diagram of a superconducting magnetized Fenton technology for sewage and wastewater treatment. Detailed Embodiments

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] Please refer to Figure 1 , the present invention provides a technical solution: a superconducting magnetized Fenton technology for sewage and wastewater treatment, including:

[0045] Experimental Group 1: Treatment effects at different pH values.

[0046] 1. Operating steps:

[0047] Magnetization stage: Open the inlet valve to make the sewage pass through the superconducting magnet through the pipeline connected to the inlet pump to complete magnetization.

[0048] Acidification stage: The magnetized sewage flows into the acidification area of the Fenton device. Turn on the stirrer and use a pH probe for real-time monitoring. Adjust the pH value to 2.5, 3, 3.5, 4, 4.5, 5, 5.5, and 6 respectively. When adjusting each pH value, add sulfuric acid dropwise and ensure that the mixing time is ≥ 2 min.

[0049] Drug addition stage: Control m(H2O2) / m(COD) = 1, n(H2O2) / n(Fe 2+ ) = 3. Weigh the corresponding amount of ferrous sulfate heptahydrate and pre-dissolve it into a solution, then add it to the wastewater, and add the hydrogen peroxide solution drop by drop under continuous stirring.

[0050] Reaction stage: Stir to assist in uniform mixing of the solution. Use a constant temperature device to maintain the reaction system at 20 - 25 °C, and set the reaction time to 20 min.

[0051] Neutralization stage: After the reaction, continue stirring and add sodium hydroxide solution to raise the pH value to about 7.

[0052] Coagulation stage: Continue stirring and add about 2 mg / L of anionic polyacrylamide (PAM) drop by drop until a large amount of iron flocs are formed.

[0053] Precipitation stage: Stop stirring and let the sewage stand for precipitation to achieve solid-liquid separation.

[0054] 2 Experimental data and result analysis:

[0055] m(H2O2) / m(COD) = 1, n(H2O2) / n(Fe 2+ ) = 3, with the COD value calculated as 80 mg / L, the COD removal rates at different pH values are as follows in Table 1:

[0056]

[0057] Table 1: Treatment effects at different pH values.

[0058] From the experimental data, the ordinary Fenton has a better pollutant removal effect when the pH is 3.5 - 4.5, with a removal rate of 55.43% - 57.12%; while the superconducting magnetized Fenton has a better pollutant removal effect when the pH is 3.0 - 5.5, with a removal rate of 54.77% - 65.28%.

[0059] The higher the pH value, the less the dosage of the reagent (acidification reagent). For the ordinary Fenton, the removal rate reaches 55% only when the pH drops to at least 4.5; while for the superconducting magnetized Fenton, the removal rate reaches 65% when the pH drops to 5.5. Not only is the removal rate improved compared to the ordinary Fenton, but the dosage of the added reagent is also significantly reduced.

[0060] Compared with ordinary Fenton, the COD effluent value of superconducting magnetized Fenton decreased by 14.92% - 44.86%.

[0061] This indicates that superconducting magnetized Fenton can maintain good treatment effects within a wider pH value range, and the overall removal rate is higher, proving that the magnetization process broadens the suitable pH range of the reaction and improves the removal ability of pollutants.

[0062] Experimental group two: Treatment effects at different m(H2O2) / m(COD) values.

[0063] 1 Operating steps:

[0064] Magnetization to precipitation stage: The operations in each stage are basically the same as those in Example 1, with the difference being the dosing stage. Fix pH = 4, n(H2O2) / n(Fe 2+ ) = 3, and set the m(H2O2) / m(COD) values to 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 respectively. According to different m(H2O2) / m(COD) values, accurately calculate and add hydrogen peroxide solution and ferrous sulfate heptahydrate.

[0065] 2: Experimental data and result analysis:

[0066] pH = 4, n(H2O2) / n(Fe 2+ ) = 3, with the COD value calculated as 80 mg / L. The COD removal rates at different m(H2O2) / m(COD) values are as shown in Table 2 below:

[0067]

[0068] Table 2: Treatment effects at different m(H2O2) / m(COD) values.

[0069] Ordinary Fenton has better pollutant removal effects when m(H2O2) / m(COD) is 1 - 3, with a removal rate of 50.73% - 55.23%; while superconducting magnetized Fenton has better pollutant removal effects when m(H2O2) / m(COD) is 0.5 - 3, with a removal rate of 61.54% - 71.84%.

[0070] The higher the m(H2O2) / m(COD) value, the more the dosing amount of the reagent (H2O2); it can be seen from the pilot test data that the COD removal rate of superconducting magnetized Fenton is significantly higher than that of ordinary Fenton. Moreover, when the dosing amount of H2O2 in superconducting magnetized Fenton is 0.12 mL / L, the removal rate reaches 64.66%, while when the dosing amount of H2O2 in ordinary Fenton is 0.24 mL / L, the removal rate reaches 55.23%. The dosing amount of the reagent (H2O2) in superconducting magnetized Fenton is 50% lower than that in ordinary Fenton, and the COD removal rate is higher.

[0071] Compared with ordinary Fenton, the COD effluent value of superconducting magnetized Fenton decreased by 12.40% - 37.12%.

[0072] Experimental group three: Treatment effects at different n(H2O2) / n(Fe 2+ ) values.

[0073] 1 Operation steps:

[0074] Magnetization to precipitation stage: The overall process is similar to that of Example 1, but the dosing stage is different. Fix pH = 4, m(H2O2) / m(COD) = 1, and sequentially set n(H2O2) / n(Fe 2+ ) values to 1, 2, 3, 4, 5, 6, 7, 8. Weigh ferrous sulfate heptahydrate accurately and measure hydrogen peroxide solution according to different n(H2O2) / n(Fe 2+ ) values and add them.

[0075] 2 Experimental data and result analysis:

[0076] pH = 4, m(H2O2) / m(COD) = 1, with the COD value calculated as 80 mg / L, COD removal rates at different n(H2O2) / n(Fe 2+ ) values. As shown in Table 3 below:

[0077]

[0078]

[0079] Table 3: Treatment effects at different n(H2O2) / n(Fe 2+ ) values.

[0080] Ordinary Fenton has better pollutant removal effects when n(H2O2) / n(Fe 2+ ) is 2 - 4, with a removal rate of 55.48% - 57.73%; while superconducting magnetized Fenton has better pollutant removal effects when n(H2O2) / n(Fe 2+ ) is 2 - 6, with a removal rate of 60.74% - 70.80%.

[0081] n(H2O2) / n(Fe 2+) The higher the value, the less the dosage of the agent (FeSO4·7H2O); it can be seen from the bench test data that the superconducting magnetized Fenton rate significantly improves the COD removal rate compared with the ordinary Fenton. Moreover, when the dosage of FeSO4·7H2O in the superconducting magnetized Fenton is 0.109 g / L, the removal rate reaches 60.74%, and when the dosage of FeSO4·7H2O is 0.131 g / L, the removal rate reaches 69.6%; while for the ordinary Fenton, when the dosage of FeSO4·7H2O is 0.164 g / L, the removal rate reaches the highest value of 57.73%. The dosage of the superconducting magnetized Fenton agent (FeSO4·7H2O) is reduced by 33.5% compared with the ordinary Fenton, and the COD removal rate is higher.

[0082] Compared with the ordinary Fenton, the COD effluent value of the superconducting magnetized Fenton is reduced by 9.37% - 43.33%.

[0083] It should be noted here that:

[0084] The greatest advantage of the present invention is to improve the COD removal rate and reduce the dosage of the agent.

[0085] To achieve this advantage, the directly influential step is Step 1: Magnetize the wastewater.

[0086] After the wastewater is magnetized, the water molecules are rearranged along the direction of the magnetic field lines, and the water molecule clusters are disintegrated, reducing the collision barrier between the active sites of polar organic substances and the agent molecules, thereby significantly improving the chemical reaction rate and the degree of reaction.

[0087] First of all, the principle of the Fenton reaction is to utilize the catalytic reaction of ferrous ions (Fe 2+ ) and hydrogen peroxide (H2O2) under acidic conditions (Fe 2+ catalyzes H2O2 to generate ·OH).

[0088] Magnetization can change the physical and chemical properties of water and affect processes such as dissolution, crystallization, polymerization, wetting, coagulation, solidification, and precipitation. The super-strong magnetic field can accelerate the generation rate of ·OH, thereby accelerating the reaction process, reducing the reaction time, and saving costs; and a higher magnetic induction intensity can effectively promote the chemical reaction in water, increase molecular dispersibility, and promote the generation of ·OH, thereby promoting the oxidation of organic substances by ·OH in the system and enhancing the removal effect of organic substances.

[0089] In addition, the magnetic field not only has a certain promoting effect on chemical reactions. When the reaction is in an aqueous solution, the magnetization effect of the magnetic field can also reduce the molecular association effect caused by hydrogen bond energy between molecules, thereby greatly increasing the probability of collision and combination between ·OH and organic substances, which is beneficial to the oxidation and decomposition of organic substances by ·OH.

[0090] In summary: As can be seen from the above different embodiments and corresponding experimental data, the superconducting magnetization Fenton technology of the present invention shows obvious advantages in terms of COD removal rate, chemical dosage, sludge production, etc. compared with the traditional Fenton technology under different reaction conditions. It can effectively treat sewage with different characteristics and has good application prospects.

Claims

1. A superconducting magnetization Fenton technology for sewage and wastewater treatment, characterized in that: The following steps are involved: Step 1: Magnetization stage: Open the water inlet valve and pass the water inlet pipe connected to the water inlet pump through the superconducting magnet to magnetize the water. The magnetization is completed instantly. Step 2: Acid adjustment stage: The magnetized water enters the acid adjustment zone of the Fenton device; start the agitator in the acid adjustment zone, put the pH probe into the wastewater to monitor the pH value in real time, and add sulfuric acid to the wastewater to reduce the pH value to between 3.0 and 4.

5. The mixing time should be ≥2 minutes; Step 3: Dosing stage: weigh an appropriate amount of ferrous sulfate heptahydrate and dissolve it in advance into a solution, and then add it to the wastewater; under continuous stirring, use a pipette or dropper to add the hydrogen peroxide solution dropwise into the wastewater; control the addition mass ratio of H2O2 to COD to be 1:1 to 3:1; control the molecular weight ratio of H2O2 to ferrous ions to be 1:1 to 9:1; Step 4: Reaction stage: With the help of a stirrer, keep the solution mixed evenly; use a thermostat to maintain the reaction system at 20-25°C; the reaction time is 10-30 minutes; Step 5: Neutralization stage: After the reaction is completed, continue to stir the wastewater and add sodium hydroxide solution to the wastewater until the pH value gradually rises to about 7, then stop adding alkali; Step 6: Coagulation stage: Continue to stir the wastewater and add about 2 mg / L of anionic polyacrylamide; continue stirring until a large amount of iron flocs are formed and enlarged; Step 7: Sedimentation stage: Stop stirring and let the wastewater settle; the suspended particles are allowed to sink due to gravity, thus achieving the purpose of solid-liquid separation.

2. The superconducting magnetization Fenton technology for sewage and wastewater treatment according to claim 1, characterized in that: In the step 1, the magnetic field generated by the superconducting magnet can change the molecular sequence of pollutants in the sewage, so that the water molecules are rearranged in the direction of the magnetic lines of force and the water molecule clusters are disintegrated.

3. The superconducting magnetization Fenton technology for sewage and wastewater treatment according to claim 1, characterized in that: In the step 3, the dosage and ratio of ferrous sulfate heptahydrate and hydrogen peroxide solution are precisely controlled according to the COD content and water quality of the sewage.

4. The superconducting magnetization Fenton technology for sewage and wastewater treatment according to claim 1, characterized in that: In step seven, the sewage settling time is adjusted according to the content and properties of suspended matter in the sewage to ensure sufficient separation of solid and liquid.

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