A method for cleaning a water supply pipeline with a double-layer annular modified ice slurry

Abstract

The present invention belongs to the field of pipeline cleaning, and particularly relates to a method for cleaning a water supply pipeline with a double-layer annular modified ice slurry. In order to in-situ remove micro-pollutants in the sediment of the water supply pipeline, the present invention adopts a brand-new idea: adding a single persulfate solution with an annular structure outside the conventional ice slurry for modification. During the cleaning process, near the pipe wall, the single persulfate, Cl<supgt;‑< / supgt; and the released Fe<supgt;2+< / supgt; in the modified ice slurry act together to remove micro-pollutants. The safe and simple operation process of this application reduces the treatment cost and complexity, and saves the treatment time.

Description

Technical Field

[0001] The present invention belongs to the field of pipeline cleaning, and particularly relates to a method for cleaning a water supply pipeline with a double-layer annular modified ice slurry. Background Art

[0002] The safety and quality of drinking water are closely related to public health. As the service life increases, various sediments are likely to adhere to the inner wall of the water supply pipeline, including many particles such as microplastics and kaolinite. These particles have a strong adsorption capacity for organic micro-pollutants (such as ciprofloxacin, bisphenol S, tetracycline, etc.). Under normal hydraulic conditions, these organic micro-pollutants will be stably adsorbed on the pipeline sediments. However, when the hydraulic conditions change (such as when water supply resumes after a water outage or in the case of fire flow), the originally adsorbed micro-pollutants may be released from the sediments, resulting in a significant increase in the concentration of organic micro-pollutants in the drinking water, further posing a potential threat to public health.

[0003] According to existing technical means, if a water supply company wants to remove micro-pollutants from sediments, it often needs to carry out pipeline cleaning work, such as using technologies like one-way flushing, ice slurry cleaning, and gas-water pulse, to make the sediments fall off the pipe wall. By means of the disturbance generated during pipeline cleaning, micro-pollutants are promoted to be released into the discharged wastewater generated by cleaning. After the pipeline cleaning is completed, advanced oxidation treatment or membrane treatment is carried out on the discharged wastewater outside the system. However, this treatment method has two drawbacks: First, the total amount of cleaning wastewater is large. Laying pipelines and building collection ponds are required to collect the cleaning wastewater in a region. The pumping process consumes a lot of energy, and the pipelines to be cleaned are widely distributed, making the collection work difficult. Second, there are many problems in the treatment of cleaning wastewater. For example, a large amount of chemical reagents need to be added, special electrodes and membrane materials need to be prepared, additional energy is consumed, building treatment ponds will increase the floor area and cost a lot, and it is also more complicated to use and maintain. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for cleaning a water supply pipeline with a double-layer annular modified ice slurry, so as to solve the problems existing in the traditional methods for removing micro-pollutants from sediments in water supply pipelines. The operation method of the present invention is simple. During pipeline cleaning, the high-concentration Fe 2+ released when the ice slurry disturbs the sediments can be directly utilized, turning waste into treasure and saving the addition of chemical agents.

[0005] In order to in-situ remove micro-pollutants from sediments in a water supply pipeline, the present invention adopts a new idea: adding a single persulfate solution with a ring structure outside the conventional ice slurry for modification. During the cleaning process, near the pipe wall, the single persulfate, Cl - and the released Fe 2+Act together to remove micropollutants.

[0006] A method for cleaning a water supply pipeline with a double-layered annular modified ice slurry, which uses a double-layered annular modified ice slurry made by adding an annular persulfate solution outside the ice slurry to clean the pipeline. The ice slurry is prepared from a sodium chloride solution. During the cleaning process, persulfate and high-concentration Cl in the double-layered annular modified ice slurry coexist near the pipe wall - , micropollutants released from sediments, and Fe 2 + , Fe 2+ , Cl - activate persulfate together to carry out an advanced oxidation reaction to generate SO4 •- , •OH, 1 O2 and HOCl to remove micropollutants; the reaction is as follows

[0007] Persulfate + Cl - + Fe 2+ →SO4 •- + •OH + 1 O2 + HOCl.

[0008] Specifically, it is carried out according to the following steps:

[0009] S1: Prepare a conventional ice slurry using a sodium chloride solution.

[0010] S2: Isolate the pipeline to be cleaned from other water supply pipelines.

[0011] S3: After the conventional ice slurry is prepared, use a double-layered casing to prepare a double-layered annular modified ice slurry, and at the same time pump the double-layered annular modified ice slurry into the pipeline to be cleaned.

[0012] S4: Use the upstream water pressure to push the double-layered annular modified ice slurry to move downstream in the pipeline to achieve the purpose of cleaning the water supply pipeline and removing micropollutants.

[0013] Furthermore, the specific step S1 is: Prepare an ice slurry using a sodium chloride solution with a mass concentration of 3% - 5%, an ice concentration of 40% - 60%, and store the ice slurry in an ice slurry storage tank for standby.

[0014] Furthermore, the specific step S2 is: Close the valves upstream and downstream of the water supply pipeline to be cleaned and isolate the pipeline to be cleaned from other water supply pipelines.

[0015] Furthermore, the specific step S3 is: After the conventional ice slurry is prepared, 5 - 10 minutes before the ice slurry is used to clean the pipeline, connect the ice slurry transfer pump to the pipeline to be cleaned using a double-layered casing. To the double-layered casing (attached Figure 2Inject ice slurry into the inner tube of the double-layer casing, and inject peroxymonosulfate solution into the outer tube from the water inlet of the double-layer casing to prepare a double-layer annular modified ice slurry. Pump the double-layer annular modified ice slurry from the upstream fire hydrant into the water supply pipeline to be cleaned.

[0016] Among them, the double-layer casing includes an outer tube and an inner tube. The inner tube is a hollow circular tube, and the outer tube is an annular tube sleeved outside the inner tube. One end of the outer tube is sealed and the other end is open. There is a water inlet on the side of the outer tube; the process of preparing the double-layer annular modified ice slurry is: inject ice slurry into the inner tube of the double-layer casing, and inject peroxymonosulfate solution into the outer tube from the water inlet of the double-layer casing.

[0017] Preferably, the range of the difference between the outer diameter of the inner tube and the inner diameter of the outer tube of the double-layer casing is 5-20 mm.

[0018] Preferably, the concentration of the injected peroxymonosulfate solution is 10 μM.

[0019] Furthermore, the specific step S4 is: open the upstream valve of the water supply pipeline to be cleaned, and use the upstream water pressure to push the double-layer annular modified ice slurry to move downstream. During the process of passing through the water supply pipe section to be cleaned, the double-layer annular modified ice slurry can provide a very high wall shear force to peel the sediment from the pipe wall. Under the disturbance of the double-layer annular modified ice slurry, the sediment releases micro-pollutants and high-concentration Fe 2+ . At this time, peroxymonosulfate and high-concentration Cl in the double-layer annular modified ice slurry coexist near the pipe wall - , the micro-pollutants and Fe released by the sediment 2+ , Fe 2+ , Cl - jointly activate peroxymonosulfate to carry out an advanced oxidation reaction to generate SO4 •- , •OH, 1 O2 and HOCl to remove micro-pollutants. Due to the high efficiency of this reaction, the reaction can be completed during the ice slurry cleaning process. Finally, the double-layer annular modified ice slurry mixed with pipe scale and sediment is discharged from the fire hydrant.

[0020] Peroxymonosulfate + Cl - + Fe 2+ → SO4 •- + •OH + 1 O2 + HOCl.

[0021] The double-layer annular modified ice slurry of the present application has a conventional ice slurry on the inner layer and a trace amount of peroxymonosulfate solution on the outer layer. During the process of cleaning the water supply pipeline with ice slurry, the ice slurry can provide a high shear force to disturb the sediment, promoting the release of micro-pollutants (such as carbamazepine, tetracycline, bisphenol A, etc.) therein. Once the micro-pollutants are released, they will immediately come into contact with the annular peroxymonosulfate outside the ice slurry. Peroxymonosulfate cooperates with Cl in the ice slurry- and Fe in the sediment 2+ It can completely remove micropollutants in situ within 0.5 minutes, preventing micropollutants from entering the inner ice slurry and then being discharged with the cleaning wastewater. Since the dosage of persulfate is extremely small, it can be completely consumed during the reaction process without any residue remaining in the pipeline. When cleaning the pipeline with ice slurry, the micropollutants and persulfate are completely consumed near the pipe wall. This process can remove micropollutants in the sediment of the water supply pipeline in situ, accurately and efficiently, without generating chemical residues, with low chemical consumption, and has high practical value in the cleaning and maintenance of water supply pipelines. This method is efficient and environmentally friendly, can reduce the dosage and cost of chemical drugs. Persulfate is non-toxic, the operation is simple, the reaction is fast, and the wastewater can be discharged routinely.

[0022] Advantages of the present invention:

[0023] (1) Efficient and environmentally friendly treatment method

[0024] ① In-situ removal of micropollutants: During the cleaning of the water supply pipeline, the double-layer annular modified ice slurry accurately and in-situ removes micropollutants near the pipe wall. It activates trace amounts of persulfate in the outer layer of the ice slurry by means of Cl⁻ in the inner layer of the ice slurry and Fe²⁺ released from the sediment, thereby effectively removing various micropollutants such as carbamazepine.

[0025] ② Avoiding the drawbacks of traditional treatment: While this process is efficient, it avoids a large number of problems in traditional off-system wastewater treatment, such as the addition, preparation, energy consumption, and land occupation of a large amount of chemical drugs. It reduces the need for additional chemical drugs, lowers costs, and reduces the impact on the environment.

[0026] (2) Safe and simple operation process

[0027] ① Safe additives: The added persulfate has no significant environmental safety problems and is non-toxic, ensuring the safety and reliability of the entire invention. The added persulfate is completely consumed during the reaction process, reducing the risk of chemical residues.

[0028] ② Simple operation process: The operation process is simple, the reaction speed is fast, and the removal reaction can be completed during the cleaning process. There is no need to collect wastewater separately, and the wastewater can be discharged according to the ordinary ice slurry cleaning method. This operation mode reduces the treatment cost and complexity, and saves treatment time. Description of the drawings

[0029] Figure 1 It is a schematic flow chart of cleaning a water supply pipeline with a double-layer annular modified ice slurry according to the present invention.

[0030] Figure 2 It is a schematic diagram of the double-layer sleeve in the present invention.

[0031] Figure 3Removal rate of double-layer annular modified ice slurry on micropollutants in the present invention. Detailed implementation mode

[0032] Combined with the attached Figure 1 , a method for cleaning a water supply pipeline using a double-layer annular modified ice slurry is as follows:

[0033] S1: Prepare a sodium chloride solution with a mass concentration of 3wt%, continuously cool the solution, and prepare a conventional ice slurry with an ice concentration of 50%. The ice slurry is stored in an ice slurry storage tank. Stirring needs to be continuously carried out during the preparation and storage of the ice slurry.

[0034] S2: Close the valves upstream and downstream of the water supply pipeline to be cleaned, isolate the pipeline to be cleaned from other water supply pipelines, and prevent the discharged wastewater during the cleaning process from entering other normally operating pipelines.

[0035] S3: After the conventional ice slurry is prepared, 5-10 minutes before the ice slurry is used to clean the pipeline, connect the A end of the double-layer sleeve to the ice slurry transfer pump, and inject the ice slurry into the inner layer pipe of the double-layer sleeve (attached Figure 2 ). Connect the water inlet of the double-layer sleeve to the pump, and inject a 10 μM monopersulfate solution into the outer layer pipe from the water inlet of the double-layer sleeve. What flows out from the B end of the double-layer sleeve is the double-layer annular modified ice slurry. Connect the B end of the double-layer sleeve to the upstream fire hydrant of the pipeline to be cleaned. Pump the double-layer annular modified ice slurry into the water supply pipeline to be cleaned from the upstream fire hydrant. The volume of the double-layer annular modified ice slurry is 1 / 3 of the volume of the pipeline to be cleaned.

[0036] S4: After the double-layer annular modified ice slurry is injected into the pipeline to be cleaned, open the upstream valve of the water supply pipeline to be cleaned, and use the upstream water pressure to push the double-layer annular modified ice slurry to move downstream. The flow rate of the double-layer annular modified ice slurry is controlled between 0.5-0.6 m / s.

[0037] During the process of passing through the water supply pipe section to be cleaned, the double-layer annular modified ice slurry can provide a very high wall shear force. Under the disturbance of the double-layer annular modified ice slurry, the sediment releases micropollutants and high-concentration Fe 2+ . Once the micropollutants are released, they come into contact with the monopersulfate on the outer layer of the annular ice slurry. At this time, the inner layer conventional ice slurry provides high-concentration Cl - , the sediment releases high-concentration Fe 2+ , plus the outer layer monopersulfate, the three act together to carry out an advanced oxidation reaction near the pipe wall, generating sulfate radicals (SO4 •- ), hydroxyl radicals (•OH), singlet oxygen ( 1 O2) and hypochlorous acid (HOCl), and removing the micropollutants within 0.5-1 minute (attached Figure 3 ). Attached Figure 3The efficiency of removing carbamazepine by the double-layer annular modified ice slurry is shown. The concentration of carbamazepine is detected by a high-performance liquid chromatograph. The initial concentration of carbamazepine is 3 μM and it is completely removed within 1 minute of the reaction. This process has a rapid reaction rate, reducing the possibility of micropollutants entering the inner-layer ice slurry and then being discharged with the cleaning wastewater, thus enhancing the safety of drinking water. Moreover, since the single persulfate is also completely consumed during this process, it will not remain in the pipeline, thereby reducing the risk of chemical residues. This "once released, in-situ removal" method for treating micropollutants not only improves the removal efficiency of micropollutants but also reduces the risk of micropollutants being released outward.

[0038] The single persulfate is a widely used strong oxidant with low toxicity and high safety in the environment. It can effectively kill various bacteria, viruses, and fungi, and remove organic pollutants, algae, and algal toxins in water. It is commonly used in water treatment plants, secondary water supply, etc.

[0039] The double-layer annular modified ice slurry mixed with pipe scale and sediment is discharged from the downstream fire hydrant of the pipeline to be cleaned. During the entire process of cleaning the pipeline, the conductivity of the discharged wastewater is monitored. When the conductivity reaches the same as that of the tap water in the pipeline to be cleaned originally, the cleaning is ended and the water supply is restored.

Claims

1. A method for cleaning a water supply pipeline using a double-layer annular modified ice slurry, characterized in that: The double-layer annular modified ice slurry prepared by a double-layer casing with a monopersulfate solution on the outside and an ice slurry on the inside is used to clean the pipeline. The ice slurry is prepared by a sodium chloride solution. During the cleaning process, the monopersulfate in the double-layer annular modified ice slurry and the high concentration of Cl - , and micropollutants and Fe released from sediments 2+ , Fe 2+ and Cl - Co-activate monopersulfate to undergo advanced oxidation reaction to generate SO4 ·- , OH, 1 O2 and HOCl, remove micropollutants; the reaction is as follows 2. The method according to claim 1, characterized in that: The steps include: S1: conventional ice slurry was prepared using sodium chloride solution; S2: Isolate the pipe to be cleaned from other water supply pipes; S3: using a double-layer casing to prepare a double-layer annular modified ice slurry with a monopersulfate solution on the outside and an ice slurry on the inside, and pumping the double-layer annular modified ice slurry into the pipeline to be cleaned; S4: Use the upstream water pressure to push the double-layer annular modified ice slurry to move downstream in the pipeline, so as to achieve the purpose of cleaning the water supply pipeline and removing micro-pollutants.

3. The method according to claim 2, characterized in that: In the step S1, the mass concentration of the sodium chloride solution used to prepare conventional ice slurry is 3%-5%.

4. The method according to claim 2, characterized in that: The ice concentration of the conventional ice slurry is 40%-60%.

5. The method according to claim 2, characterized in that: In step S2, the pipeline to be cleaned is isolated from other water supply pipelines by closing valves upstream and downstream of the water supply pipeline to be cleaned.

6. The method according to claim 2, characterized in that: In step S3, the double-layer casing is connected to the ice slurry delivery pump and the pipeline to be cleaned, and the monopersulfate solution is injected into the outer tube while delivering the ice slurry. The double-layer annular modified ice slurry is pumped into the upstream of the water supply pipeline to be cleaned, and the volume of the double-layer annular modified ice slurry is 1 / 3 of the volume of the pipeline to be cleaned.

7. The method according to claim 6, characterized in that: The double-layer casing comprises an outer tube and an inner tube, the inner tube is a hollow circular tube, the outer tube is an annular tube sleeved outside the inner tube, one end of the outer tube is sealed and the other end is open, and a water inlet is provided on the side of the outer tube; the process of preparing the double-layer annular modified ice slurry is: injecting ice slurry into the inner tube of the double-layer casing, and at the same time injecting monopersulfate solution into the outer tube from the water inlet of the double-layer casing.

8. The method according to claim 7, characterized in that: The difference between the outer diameter of the inner tube and the inner diameter of the outer tube of the double-layer casing is in the range of 5-20 mm.

9. The method according to claim 6, characterized in that: The concentration of the monopersulfate solution injected into the outer tube from the water inlet of the double-layer casing in step S3 is 10 μM.

10. The method according to claim 2, characterized in that: In step S4, the upstream valve of the water supply pipeline to be cleaned is opened, and the upstream water pressure is used to push the double-layer annular modified ice slurry to move downstream in the pipeline. The flow rate of the double-layer annular modified ice slurry is controlled between 0.5-0.6 m / s.

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