Precise positioning method for surface water backflow point of municipal pipe network

Abstract

The invention discloses a municipal pipe network surface water backflow point accurate positioning method, and belongs to the technical field of sewage treatment, and the method comprises the steps: S1, carrying out the partitioning of a region in a sewage plant treatment range, carrying out the water quality detection of a sewage pipe network key node of each region, and preliminarily screening out a low-concentration drainage region; s2, collecting a last inspection well, a river, a lake, underground water and resident domestic sewage multi-point water sample before water is fed into a sewage pumping station in the low-concentration drainage area or converged into a sewage plant, detecting microbial diversity, and judging a water source outside the low-concentration drainage area; s3, if the external water source is a river or a lake, stationing sampling is conducted on a sewage pipe network in the low-concentration drainage area, and a sewage concentration mutation pipe section is determined; continuously adding a characteristic tracer to the nearest external water source, collecting all inspection well water samples in the sewage concentration mutation pipe section, and positioning an external water source backward flowing point according to the characteristic tracer in the water samples. According to the invention, time and economic cost consumed by pipeline clearing and detection are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and relates to a sewage pipe network investigation method, and in particular to a method for accurately locating surface water backflow points in a municipal pipe network. Background Art

[0002] In the southern region with dense river networks, since the design bottom elevation of some drainage trunk pipelines is lower than the normal water level of the river, a large amount of river water flows back into the sewage treatment system through potential backflow points such as interception and confluence pipelines, resulting in the long-term low-concentration influent and high-load operation of sewage treatment plants. Typical river water backflow outlets are generally below the normal water level of the river, with high concealment, and it is difficult to accurately locate them with existing investigation technology. The existing municipal pipeline network river water backflow point investigation technology first uses water quality testing to screen low-concentration areas, that is, high-incidence areas of river water backflow, and then uses pipeline closed-circuit television (CCTV) or pipeline periscope (QV) to detect pipelines in low-concentration drainage areas, and visually find pipeline defects and river water backflow points. However, the low-concentration areas screened by water quality testing cannot determine whether the external water source is groundwater or river water. Although CCTV video detection technology and QV detection technology have high accuracy, they have high requirements for the investigation of pipeline networks. Pipeline dredging is required before detection, which is labor-intensive, inefficient, and costly. Summary of the invention

[0003] The present invention provides a method for solving the technical problem that the current method of detecting pipe network defects through pipeline closed-circuit television or periscope to locate the backflow point of river water in the municipal pipe network has high requirements for the pipe network to be checked, large inspection workload and low efficiency.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for accurately locating a surface water backflow point in a municipal pipe network comprises the following steps:

[0006] S1. Zoning the areas within the treatment range of the sewage treatment plant, conducting water quality tests at key nodes of the sewage pipe network in each area, analyzing the sewage concentration distribution, and preliminarily screening out low-concentration drainage areas;

[0007] S2. Collect water samples from multiple locations in the low-concentration drainage area, including the sewage pump station inlet (sewage pump station lifting area) / the last inspection well before entering the sewage treatment plant (gravity self-flow area), rivers, lakes, groundwater and domestic sewage, and test the microbial diversity. Determine the source of water outside the low-concentration drainage area based on the microbial diversity results;

[0008] S3. If the external water source is a river or lake, sampling shall be conducted at the sewage pipe network points in the low-concentration drainage area to conduct water quality testing and determine the pipe section with sudden change in sewage concentration;

[0009] Continuously add characteristic tracers to the external water source closest to the section where sewage concentration suddenly changes, collect water samples from all inspection wells in the section where sewage concentration suddenly changes, and locate the backflow point of the external water source based on the characteristic tracers in the water samples.

[0010] The method of the present invention is a method for locating the backflow point of surface water. Therefore, if the external water source is groundwater, the traditional method is used for investigation and positioning, that is, pipeline closed-circuit television (CCTV) or pipeline periscope (QV) is used to visually find pipeline defects.

[0011] To optimize the above technical solutions, the specific measures taken also include:

[0012] Furthermore, in S1, the zoning method is: according to the way sewage flows into the sewage treatment plant, it is divided into the sewage pumping station lifting area and the gravity flow area. The sewage pumping station lifting area takes the water collection range of a sewage pumping station as an area, and the gravity flow area takes the water collection range of the last gravity pipe in front of the sewage treatment plant as an area.

[0013] Furthermore, in S1, the key nodes include the water inlet of the sewage pumping station, the intersection of the sewage pipes, the node where the intercepting well is connected to the sewage pipe, and the node where the branch pipe is connected to the sewage pipe; the sewage pipes in the present invention are all sewage main pipes.

[0014] Furthermore, in S1, the water quality detection indicator is COD concentration; if the COD concentration is less than 200 mg / L, the area where the key node is located is screened as the low-concentration drainage area.

[0015] Furthermore, in S2, the method for determining the source of external water in the low-concentration drainage area based on the microbial diversity results is: taking the last inspection well before the sewage pump station enters / enters the sewage treatment plant as the sink, and the rivers, lakes, groundwater and domestic sewage entering the pipe network as the source, inputting the detection data of each point into the microbial traceability model FEAST, and determining the source of external water based on the obtained contribution ratio. Specifically, the source with the largest contribution ratio other than domestic sewage is the external water source.

[0016] Furthermore, in S2, the method for acquiring the microbial diversity detection data is: using high-throughput sequencing based on the Illumina MiSeq platform, using the Sliva138 database for species annotation, and obtaining microbial diversity relative abundance sequencing data.

[0017] Furthermore, in S3, the method for determining the pipe section with a sudden change in sewage concentration is: sampling is carried out at denser points every 100m in the sewage pipe to detect the COD concentration; if the COD concentration of a part of the sewage pipe drops significantly, this part of the sewage pipe is determined as the pipe section with a sudden change in sewage concentration.

[0018] Furthermore, in S3, during the process of determining the pipe section with a sudden change in sewage concentration, if the COD concentration sampled from the downstream inspection well is 50% lower than the COD concentration sampled from the upstream inspection well, the COD concentration of the sewage pipe between the downstream inspection well and the upstream inspection well will drop significantly.

[0019] Furthermore, in S3, the method of adding characteristic tracers and collecting water samples is: continuously adding characteristic tracers to the external water source every 15 minutes, and collecting hourly mixed samples using a continuous sampling device to ensure that the characteristic tracers can be detected at the river water backflow point; the hourly mixed sample is a mixed sample collected every 10 minutes.

[0020] Furthermore, in S3, the method for locating the backflow point of the external water source is: if the effective component of the characteristic tracer is detected in the water sample of the downstream inspection well, and the effective component of the characteristic tracer is not detected in the water sample of the upstream inspection well, or if the effective component of the characteristic tracer is detected in both the downstream inspection well and the upstream inspection well, and the concentration of the characteristic tracer detected in the water sample of the downstream inspection well is higher than that of the upstream inspection well, then there is a surface water backflow point in the sewage pipe between the downstream inspection well and the upstream inspection well.

[0021] The characteristics of characteristic tracers are: easily soluble in water, colorless after dissolving in water, no adverse effect on urban water environment, the background concentration of active ingredients in domestic sewage, surface water and groundwater is almost negligible, the minimum concentration limit detected in the laboratory is small (0.05 mg / L), and there is no need to add a large amount of tracers, reducing costs.

[0022] The beneficial effects of the present invention are as follows: the present invention provides a method for accurately locating the surface water backflow point of a municipal pipe network, which combines the sewage concentration detection, microbial diversity analysis and the application of characteristic tracers, aiming to improve the efficiency of troubleshooting the surface water backflow problem, and reduce the reliance on traditional detection methods (such as closed-circuit television camera detection CCTV or periscope detection QV), thereby significantly reducing the time consumption and economic cost of related pipeline dredging operations. Specifically, firstly, low-concentration drainage areas are screened by sewage concentration detection, and then the source of external water is determined by differences in microbial communities, the surface water backflow problem investigation area is narrowed, and finally the surface water backflow point is accurately located using characteristic tracers. The present invention solves the problem of surface water backflow in municipal pipe networks from multiple angles, which not only improves work efficiency but also saves resources, and is of great significance for the maintenance of urban infrastructure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the method for accurately locating the surface water backflow point of the municipal pipe network;

[0024] Figure 2 It is a color scale diagram of sewage concentration in the sewage pipe network of the low-concentration drainage area in the embodiment. DETAILED DESCRIPTION

[0025] Taking a county town in Huai'an City, Jiangsu Province as an example, the present invention is further explained.

[0026] like Figure 1 As shown, this embodiment provides a method for accurately locating a surface water backflow point in a municipal pipe network, comprising the following steps:

[0027] S1. The average monthly COD concentration of the influent of a sewage treatment plant is about 200 mg / L, which does not reach the target value of 260 mg / L for improving the quality and efficiency of sewage treatment in Jiangsu Province. The area within the treatment range of the sewage treatment plant is taken as the research area, and is divided into two areas, north and south, according to the way sewage flows into the sewage treatment plant. The sewage in the southern area is collected to the sewage pumping station, that is, the sewage pumping station lifting area, and the sewage in the northern area flows to the sewage treatment plant through the gravity pipe, that is, the gravity self-flow area. Water samples were collected at the sewage pumping station inlet in the southern area, the last inspection well before the northern area flows into the sewage treatment plant, and the intersection of sewage pipes in the south and north areas, the nodes where the interception wells are connected to the sewage pipes, and the nodes where the branch pipes are connected to the sewage pipes, and their COD concentrations were tested. The test results show that the COD concentrations of the key nodes in the northern area are all above 200 mg / L, and the highest can reach 400 mg / L, while the COD concentrations of the key nodes in the southern area are all below 150 mg / L, and the lowest is only 20 mg / L. Therefore, the southern area is determined to be a low-concentration drainage area.

[0028] S2. Collect water samples from multiple locations of the sewage pump station inlet in the southern area, River 1, River 2, lakes, groundwater and domestic sewage. Collect three parallel water samples at each location. The last inspection well before entering the sewage treatment plant and domestic sewage have rich bacterial flora, and 500mL of water samples are collected from each location. 1000mL of water samples are collected from each location of rivers and lakes. The groundwater flora is relatively small, and 2 to 5L of water samples are collected. Microbial diversity was analyzed by high-throughput sequencing based on the Illumina MiSeq platform, and species annotation was performed using the Sliva138 database to obtain sequencing data of relative abundance of microbial diversity.

[0029] Taking the sewage pump station inlet (P) as the sink, River 1 (R1), River 2 (R2), lake (L), groundwater (G), and domestic sewage (S) as the sources, the relative abundance sequencing data of microbial diversity at each point were input into the microbial traceability model FEAST, and the results are shown in Table 1.

[0030] Table 1 Tracing results of sewage pump station inlet model

[0031] R1 R2 L G S Unknown P-1 0.02 0.01 0.25 0.08 0.56 0.08 P-2 0.01 0.02 0.22 0.05 0.59 0.11 P-3 0.02 0.01 0.23 0.07 0.57 0.1

[0032] The results show that in addition to the contribution of domestic sewage, lakes contribute the largest proportion, so the source of external water in the southern region is lakes.

[0033] S3. Sampling was carried out at denser points every 100 m in the sewage pipe network in the southern area to test the COD concentration. The results are as follows: Figure 2 The results show that the sewage concentration in the sewage pipes around the lake has dropped significantly, and the sections where the sewage concentration changes suddenly are determined to be the west and east sides of the lake.

[0034] Characteristic tracers were added to the east and west sides of the lake, near the sewage concentration mutation pipe section (within a radius of 500m). In order to ensure that the characteristic tracers can be detected at the surface water backflow point, characteristic tracers were continuously added to the lake every 15 minutes, and a continuous sampling device was used to collect hourly mixed samples of all inspection wells in the sewage concentration mutation pipe section (mixed samples were collected every 10 minutes).

[0035] On the east and west sides of the lake, effective components of characteristic tracers were detected in both the downstream inspection wells and the upstream inspection water samples, and the concentration of characteristic tracers detected in the downstream inspection wells was higher than that in the upstream inspection wells, indicating that lake water was backflowing on both the east and west sides of the lake.

[0036] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. In addition, the reagents, materials and operating procedures used herein are reagents, materials and conventional procedures widely used in the corresponding fields.

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for accurately locating the backflow point of surface water in a municipal pipe network, characterized in that: The following steps are involved: S1. Zoning the areas within the treatment range of the sewage treatment plant, conducting water quality tests at key nodes of the sewage pipe network in each area, analyzing the sewage concentration distribution, and preliminarily screening out low-concentration drainage areas; S2. Collect water samples from the last inspection well, rivers, lakes, groundwater and domestic sewage of the sewage pump station in the low-concentration drainage area before it enters the sewage treatment plant, and test the microbial diversity. According to the microbial diversity results, determine the source of water outside the low-concentration drainage area; S3. If the external water source is a river or lake, sampling shall be conducted at the sewage pipe network points in the low-concentration drainage area to conduct water quality testing and determine the pipe section with sudden change in sewage concentration; Continuously add characteristic tracers to the external water source closest to the section where sewage concentration suddenly changes, collect water samples from all inspection wells in the section where sewage concentration suddenly changes, and locate the backflow point of the external water source based on the characteristic tracers in the water samples.

2. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 1 is characterized by: In S1, the zoning method is: according to the way sewage flows into the sewage treatment plant, it is divided into the sewage pump station lifting area and the gravity flow area. The sewage pump station lifting area takes the water collection range of a sewage pump station as an area, and the gravity flow area takes the water collection range of the last gravity pipe in front of the sewage treatment plant as an area.

3. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 1 is characterized by: In S1, the key nodes include the water inlet of the sewage pumping station, the intersection of the sewage pipes, the node where the intercepting well is connected to the sewage pipe, and the node where the branch pipe is connected to the sewage pipe.

4. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 1 is characterized by: In S1, the water quality detection indicator is COD concentration; if the COD concentration is less than 200 mg / L, the area where the key node is located is screened as the low-concentration drainage area.

5. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 1 is characterized by: In S2, the method for determining the source of external water in the low-concentration drainage area based on the microbial diversity results is as follows: the last inspection well before the sewage pump station enters / merges into the sewage treatment plant is taken as the sink, and the rivers, lakes, groundwater and domestic sewage that flow into the pipe network are taken as the source, and the detection data of each point is input into the microbial traceability model FEAST to determine the source of external water.

6. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 5 is characterized by: In S2, the method for acquiring the microbial diversity detection data is: using high-throughput sequencing based on the Illumina MiSeq platform, using the Sliva138 database for species annotation, and obtaining microbial diversity relative abundance sequencing data.

7. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 1 is characterized by: In S3, the method for determining the pipe section with a sudden change in sewage concentration is: sampling is carried out at denser points every 100m in the sewage pipe to detect the COD concentration; if the COD concentration of a part of the sewage pipe drops significantly, this part of the sewage pipe is determined as the pipe section with a sudden change in sewage concentration.

8. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 7 is characterized by: In S3, during the determination of the pipe section with a sudden change in sewage concentration, if the COD concentration sampled from the downstream inspection well is 50% lower than the COD concentration sampled from the upstream inspection well, the COD concentration of the sewage pipe between the downstream inspection well and the upstream inspection well will drop significantly.

9. The method for accurately locating the backflow point of surface water in a municipal pipe network according to claim 1 is characterized by: In S3, the method of adding characteristic tracers and collecting water samples is: continuously adding characteristic tracers to the external water source every 15 minutes, and collecting hourly mixed samples using a continuous sampling device; the hourly mixed samples are mixed samples collected every 10 minutes.

10. The method for accurately locating the backflow point of surface water in the municipal pipe network according to claim 1, characterized in that: In S3, the method for locating the backflow point of the external water source is: if the effective components of the characteristic tracer are detected in the water sample of the downstream inspection well, and the effective components of the characteristic tracer are not detected in the water sample of the upstream inspection well, or if the effective components of the characteristic tracer are detected in the water samples of both the downstream inspection well and the upstream inspection well, and the concentration of the characteristic tracer detected in the water sample of the downstream inspection well is higher than that of the upstream inspection well, then there is a surface water backflow point in the sewage pipe between the downstream inspection well and the upstream inspection well.

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