Method for cleaning water supply pipeline through double-layer annular modified ice slurry

Abstract

The invention belongs to the field of pipeline cleaning, and particularly relates to a method for cleaning a water supply pipeline through double-layer annular modified ice slurry. In order to remove the micro-pollutants in the sediments of the water supply pipeline in situ, a brand new thought is adopted: a monopersulfate solution with an annular structure is added to the outer side of conventional ice slurry for modification. In the cleaning process, monopersulfate and Cl <-> in the modified ice slurry jointly act with released Fe < 2 + > near the pipe wall, so that micro-pollutants are removed. According to the invention, the operation process is safe and simple, the processing cost and complexity are reduced, and the processing time is saved.

Description

Technical Field

[0001] The invention belongs to the field of pipeline cleaning, and in particular 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 years of use continue to increase, various sediments are easily attached to the walls of water supply pipes, including microplastics, kaolinite and other particles, which have a strong adsorption capacity for organic micropollutants (such as ciprofloxacin, bisphenol S, tetracycline, etc.). Under normal hydraulic conditions, these organic micropollutants will be stably adsorbed on the pipe sediments, but when the hydraulic conditions change (such as water supply after water outage or fire flow), the originally adsorbed micropollutants may be released from the sediments, resulting in a significant increase in the concentration of organic micropollutants in drinking water, further posing a potential threat to public health.

[0003] According to existing technical means, if water supply companies want to remove micropollutants in sediments, they often need to carry out pipeline cleaning work, such as using one-way flushing, ice slurry cleaning, gas-water pulse and other technologies to make sediments fall off the pipe wall. With the help of the disturbance generated during pipeline cleaning, micropollutants are released into the discharged wastewater generated by cleaning. After the pipeline is cleaned, the discharged wastewater is subjected to advanced oxidation treatment or membrane treatment outside the system. However, this treatment method has two disadvantages: first, the total amount of cleaning wastewater is large. Collecting cleaning wastewater in a region requires laying pipelines and building collection pools. The pumping process consumes a lot of energy, and the pipelines that need to be cleaned are widely distributed, making the collection work difficult. Secondly, the treatment of cleaning wastewater faces many difficulties. For example, a large amount of chemical reagents need to be added, special materials such as electrodes and membranes need to be prepared, and additional energy is consumed. The construction of treatment pools will expand the floor area, increase costs, and the use and maintenance management are also more complicated. Summary of the invention

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

[0005] In order to remove micro-pollutants in the sediment of water supply pipes in situ, the present invention adopts a new idea: adding a ring-shaped monopersulfate solution to the outside of the conventional ice slurry for modification. During the cleaning process, near the pipe wall, the monopersulfate, Cl - The released Fe 2+Working together to remove micro pollutants.

[0006] A method for cleaning a water supply pipeline with a double-layer annular modified ice slurry, wherein an annular monopersulfate solution is added to the outer side of the ice slurry to prepare a double-layer annular modified ice slurry to clean the pipeline, wherein the ice slurry is prepared from a sodium chloride solution, and during the cleaning process, the monopersulfate in the double-layer annular modified ice slurry and a high concentration of Cl in the double-layer annular modified ice slurry coexist near the pipe wall. - , micropollutants released from sediments and Fe 2 + , Fe 2+ , Cl - Co-activate monopersulfate to undergo advanced oxidation reaction to generate SO4 •- ,•OH, 1 O2 and HOCl, remove micropollutants; the reaction is as follows Monopersulfate + Cl - +Fe 2+ →SO4 •- +•OH+ 1 O2+HOCl.

[0007] Follow these steps: S1: Conventional ice slurry was prepared using sodium chloride solution.

[0008] S2: Isolate the pipe to be cleaned from other water supply pipes.

[0009] S3: After the conventional ice slurry is prepared, a double-layer annular modified ice slurry is prepared using a double-layer casing, and the double-layer annular modified ice slurry is pumped into the pipeline to be cleaned.

[0010] 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.

[0011] Furthermore, the step S1 is specifically as follows: preparing ice slurry with a sodium chloride solution having a mass concentration of 3%-5%, and an ice concentration of 40%-60%, and storing the ice slurry in an ice slurry storage tank for standby use.

[0012] Furthermore, the step S2 specifically includes: closing valves upstream and downstream of the water supply pipe to be cleaned, and isolating the pipe to be cleaned from other water supply pipes.

[0013] Further, the step S3 is specifically as follows: after the conventional ice slurry preparation is completed, 5-10 minutes before the ice slurry is used to clean the pipeline, the ice slurry delivery pump is connected to the pipeline to be cleaned using a double-layer casing. Figure 2 ) and injecting ice slurry into the inner tube of the double-layer casing, and injecting monopersulfate solution into the outer tube from the water inlet of the double-layer casing to make a double-layer annular modified ice slurry. The double-layer annular modified ice slurry is pumped from the upstream fire hydrant into the water supply pipeline to be cleaned.

[0014] 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 injecting monopersulfate solution into the outer tube from the water inlet of the double-layer casing.

[0015] Preferably, 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.

[0016] Preferably, the concentration of the injected monopersulfate solution is 10 μM.

[0017] Furthermore, step S4 is specifically as follows: open the upstream valve of the water supply pipe to be cleaned, and use the upstream water pressure to push the double-layer annular modified ice slurry to move downstream. In 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 off the sediment from the pipe wall. Under the disturbance of the double-layer annular modified ice slurry, the sediment releases micropollutants and high-concentration Fe 2+ At this time, there are monopersulfate and high concentration Cl in the double-layer ring-shaped modified ice slurry near the tube wall. - , micropollutants released from sediments and Fe 2+ , Fe 2+ , Cl - Co-activate monopersulfate to undergo advanced oxidation reaction to generate SO4 •- ,•OH, 1 O2 and HOCl, remove micro pollutants. Due to the high efficiency of the reaction, the reaction can be completed during the ice slurry cleaning process. Finally, a double-layer annular modified ice slurry mixed with pipe scale and sediment is discharged from the fire hydrant.

[0018] Monopersulfate + Cl - +Fe 2+ →SO4 •- +•OH+ 1 O2+HOCl.

[0019] The double-layered annular modified ice slurry of the present application has a conventional ice slurry as the inner layer and a trace monopersulfate solution as the outer layer. When using ice slurry to clean water supply pipes, the ice slurry can provide high shear force to disturb the sediment, causing the micro-pollutants (such as carbamazepine, tetracycline, bisphenol A, etc.) in the sediment to be released. Once the micro-pollutants are released, they will immediately come into contact with the annular monopersulfate on the outer side of the ice slurry. The monopersulfate cooperates with the Cl in the ice slurry to - and Fe in sediments 2+It can completely remove micropollutants in situ within 0.5 minutes, thereby preventing micropollutants from entering the inner ice slurry and then being discharged with the cleaning wastewater. Since the amount of monopersulfate used is extremely small, it can be completely consumed during the reaction process, and no residue will remain in the pipeline. When the ice slurry is used to clean the pipeline, the micropollutants and monopersulfate 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, and will not produce chemical residues. The chemical consumption is low, and it has high practical value in the cleaning and maintenance of water supply pipelines. This method is efficient and environmentally friendly, can reduce the amount and cost of chemicals, monopersulfate is non-toxic, easy to operate, and has a fast reaction, and the wastewater can be discharged conventionally.

[0020] Beneficial effects of the present invention: (1) Efficient and environmentally friendly treatment method ① In-situ removal of micro-pollutants: During the cleaning of water supply pipes, the double-layer annular modified ice slurry can accurately and in-situ remove micro-pollutants near the pipe wall. It uses the Cl⁻ in the inner layer of ice slurry and the Fe²⁺ released by the sediment to activate the trace monopersulfate in the outer layer of ice slurry, thereby effectively removing a variety of micro-pollutants such as carbamazepine.

[0021] ②Avoid the drawbacks of traditional treatment: This process is highly efficient and avoids the problems of adding a large number of chemicals, preparation, energy consumption, and land occupation in traditional wastewater treatment systems. It reduces the demand for additional chemicals, reduces costs, and mitigates the impact on the environment.

[0022] (2) Safe and easy operation process ① Safe additives: The added monopersulfate has no significant environmental safety issues and is non-toxic, ensuring the safety and reliability of the entire invention. The added monopersulfate is completely consumed during the reaction process, reducing the risk of chemical residues.

[0023] ②Simple operation process: The operation process is simple and the reaction speed is fast. The removal reaction can be completed during the cleaning process. There is no need to collect wastewater separately. The wastewater can be discharged according to the ordinary ice slurry cleaning method. This operation mode reduces the processing cost and complexity, and saves processing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic diagram of a process of cleaning a water supply pipeline with a double-layered annular modified ice slurry.

[0025] Figure 2 It is a schematic diagram of the double-layer casing in the present invention.

[0026] Figure 3 It is the removal rate of micro pollutants by the double-layer annular modified ice slurry in the present invention. DETAILED DESCRIPTION

[0027] Combined with Figure 1 The method of using double-layer annular modified ice slurry to clean water supply pipes is as follows: S1: Prepare a sodium chloride solution with a mass concentration of 3wt%, continuously cool the solution to prepare a conventional ice slurry with an ice concentration of 50%, and store the ice slurry in an ice slurry storage tank. Continuous stirring is required during the preparation and storage of the ice slurry.

[0028] S2: Close the valves upstream and downstream of the water supply pipe to be cleaned, isolate the pipe to be cleaned from other water supply pipes, and prevent the wastewater discharged during the cleaning process from entering other normally operating pipes.

[0029] S3: After completing the routine ice slurry preparation, 5-10 minutes before the ice slurry is used to clean the pipeline, connect the A end of the double-layer casing to the ice slurry delivery pump and feed the double-layer casing (attached Figure 2 ) Inject ice slurry into the inner tube of the double-layer casing. Connect the water inlet of the double-layer casing to the pump, and inject a monopersulfate solution with a concentration of 10 μM into the outer tube from the water inlet of the double-layer casing. What flows out from the B end of the double-layer casing is the double-layer annular modified ice slurry. Connect the B end of the double-layer casing to the upstream fire hydrant of the pipeline to be cleaned. Pump the double-layer annular modified ice slurry from the upstream fire hydrant into the water supply pipeline to be cleaned. The volume of the double-layer annular modified ice slurry is 1 / 3 of the volume of the pipeline to be cleaned.

[0030] S4: After the double-layer annular modified ice slurry is injected into the pipeline to be cleaned, 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. The flow rate of the double-layer annular modified ice slurry is controlled between 0.5-0.6m / s.

[0031] In the process of passing through the cleaned water supply pipe section, the double-layer annular modified ice slurry can provide a 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 released, the micropollutants come into contact with the monopersulfate in the outer layer of the annular ice slurry. At this time, the inner layer of conventional ice slurry provides a high concentration of Cl - , the sediment releases high concentrations of Fe 2+ , plus the outer layer of monopersulfate, the three work together to produce an advanced oxidation reaction near the tube wall, generating sulfate radicals (SO4 •- ), hydroxyl radical (•OH), singlet oxygen ( 1 O2) and hypochlorous acid (HOCl), and removes micropollutants within 0.5-1 minute (with Figure 3 ). Figure 3The efficiency of double-layer annular modified ice slurry in removing carbamazepine was demonstrated. The concentration of carbamazepine was detected by high-performance liquid chromatography. The initial concentration of carbamazepine was 3μM, and it was completely removed within 1 minute of reaction. The process reacts quickly, reducing the possibility of micropollutants entering the inner ice slurry and then being discharged with the cleaning wastewater, thereby improving the safety of drinking water. In addition, since monopersulfate is also completely consumed in the process, it will not remain in the pipeline, thereby reducing the risk of chemical residues. This "once released, in-situ removal" method of treating micropollutants not only improves the removal efficiency of micropollutants, but also reduces the risk of micropollutants being released externally.

[0032] The monopersulfate is a widely used strong oxidant with low toxicity and high safety in the environment. It can effectively kill a variety of bacteria, viruses and fungi, remove organic pollutants, algae and algal toxins in water, and is often used in water plants, secondary water supply, etc.

[0033] The double-layer annular modified ice slurry mixed with pipe scale and sediment is discharged from the downstream fire hydrant of the cleaned pipeline. During the entire process of cleaning the pipeline, the conductivity of the discharged wastewater is monitored. When the conductivity reaches the same conductivity as the tap water in the original cleaned pipeline, the cleaning is terminated 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 is prepared by adding an annular monopersulfate solution to the outside of the ice slurry to clean the pipeline. The ice slurry is prepared by 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 Monopersulfate + Cl - +Fe 2+ →SO4 •- +•OH+ 1 O2+HOCl.

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 the 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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