ArcGIS-based method for rapid calculation of effluent concentration at end of sewage collection system

Abstract

The application discloses a sewage collection system end effluent water quality concentration rapid calculation method based on ArcGIS, relates to the urban sewage collection system quality improvement and efficiency enhancement technical field, the method not only considers the influence of the spatial distribution of the drainage unit on the end effluent pollutant concentration, but also saves the huge workload of constructing a sewage collection system quantitative model based on a traditional model software, simply and quickly realizes the whole process of the sewage collection system end effluent water quality calculation, and has strong replicability and generalization, and can be used for the quantitative evaluation of the urban sewage collection system quality improvement and efficiency enhancement; the disclosed calculation method can be used for rapidly and conveniently constructing the spatial topological relation of the sewage collection system and the drainage unit, and simply and quantitatively calculating the target accessibility of the sewage collection system quality improvement and efficiency enhancement, and can provide a reference for similar research work and engineering practice.

Description

Technical Field

[0001] This invention relates to the field of improving the quality and efficiency of urban sewage collection systems, specifically to a method for rapidly calculating the concentration of effluent at the end of a sewage collection system based on ArcGIS. Background Technology

[0002] Urban sewage collection pipe network system is a large-scale and complex network system, including different drainage systems such as sewage pipe network and combined sewer network. At present, in the planning and design schemes for improving the quality and efficiency of sewage treatment, the quantitative analysis of BOD5 concentration in sewage treatment plant influent is mostly calculated directly by weighting the water quantity and water quality of drainage units or by constructing a sewage collection system model based on pipe network modeling software for quantitative simulation calculation. The former does not consider the impact of the spatial distribution differences of drainage units on the sewage collection system on the calculation results; the latter is rarely used in the achievability of planning and design scheme objectives due to the large workload of model construction and simulation analysis, and the difficulty in model value calibration and verification. In summary, both quantitative calculation methods have significant limitations and are not suitable for quickly and accurately quantitatively assessing and analyzing the BOD5 concentration value of the effluent at the end of the sewage collection system.

[0003] ArcGIS software is now widely used in the field of drainage systems for data management, querying, processing, analysis, and display. It can not only analyze the spatial relationships of different elements such as pipe networks, manholes, and drainage units in drainage systems, but also analyze and calculate the attribute data of each element. Therefore, ArcGIS can be used as an important technical means for analyzing the quality improvement and efficiency enhancement schemes of sewage collection systems. Thus, a rapid calculation method for the effluent water quality concentration at the end of a sewage collection system based on ArcGIS can be designed to solve the defects of the two methods mentioned above in the existing technology. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a rapid calculation method for the concentration of effluent at the end of a wastewater collection system based on ArcGIS. This method involves the rapid analysis and calculation of the entire process, from the collection, analysis, and processing of data on the wastewater collection network and drainage unit system, to the spatial topological relationship between the wastewater network and drainage units, the calculation of pollutant attenuation along the flow path, and the analysis of the attainability of the effluent concentration at the end of the system. This provides a technical approach for supporting the attainability of pollutant concentration targets and the optimization of solutions for improving the quality and efficiency of wastewater collection systems.

[0005] To achieve the above-mentioned technical effects, the objective of this invention is as follows: a rapid calculation method for the concentration of effluent at the end of a wastewater collection system based on ArcGIS, comprising the following steps:

[0006] S1: Select the wastewater collection area of ​​the wastewater collection system;

[0007] S2: Wastewater collection network data collection and processing; establishing a wastewater collection system topology diagram in ArcGIS:

[0008] S201, Collect current status survey data of sewage collection pipe network within the water collection range of sewage collection system, and the attribute information of the data includes information that can accurately describe the spatial distribution of sewage collection pipe network;

[0009] S202, Based on the pipeline network data obtained in S201, sort out the main pipes, trunk pipes and branch pipes of the sewage collection pipeline network, as well as the attribute information of manholes and pipelines; among them, the attribute information of manholes includes coordinates and manhole numbers; the attribute information of pipelines includes the manhole numbers connected to the upstream and downstream pipelines and the pipeline length.

[0010] S203: Use ArcGIS to construct two layers and attribute lists for inspection wells and pipelines respectively; and enter the attribute information in S202 into the corresponding attribute table to form a map of the spatial topology of the sewage collection pipeline network.

[0011] S3: Collection and processing of sewage discharge and pollutant data for drainage units; creation of basic data information map of drainage units in ArcGIS;

[0012] S301, investigate and collect the drainage unit types within the sewage collection system's water intake area, classify them according to land use type, import the drainage unit data and scope into ArcGIS to generate shp format data, and create an attribute table. The attribute information includes pollution source type, area, water consumption, and sewage volume.

[0013] S302, determine the average daily sewage volume of each drainage unit within the sewage collection area of ​​the sewage collection system. The sewage volume of each drainage unit can generally be indirectly calculated by the water consumption of the drainage unit and the conversion factor between water consumption and sewage volume.

[0014] S303, determine the daily average concentration of target pollutants in the sewage collected by each drainage unit within the sewage collection area of ​​the sewage collection system;

[0015] S304. Import each drainage unit into ArcGIS and generate a spatial distribution map of each drainage unit. Calculate the input pollution source attribute information, including sewage volume and sewage quality index values, according to the above method.

[0016] S4: Spatial connection between the drainage unit and the sewage collection system:

[0017] S401. Based on the survey data of the current status of the sewage collection pipe network within the sewage collection system's water intake area, sort out the spatial relationship between the outlet water of each drainage unit and the municipal sewage inspection well.

[0018] S402, based on the spatial relationship between the outflow pipes of each drainage unit and the municipal sewage inspection well, the drainage unit is associated with the nearest inspection well;

[0019] S5, Analyze and calculate the transport distance from each drainage unit to the outlet at the end of the pipe network:

[0020] Based on ArcGIS spatial analysis, the transport distance from the access manhole of each drainage unit to the end outlet of the sewage collection pipeline network was calculated.

[0021] S6, determine the pollutant attenuation coefficient of the pipe network, and calculate the pollutant attenuation along the flow path in the effluent of each drainage unit:

[0022] S7. The weighted calculation of pollutant concentration in the effluent at the end of the pipe network is performed based on the sewage discharge volume of each drainage unit and the concentration of pollutants converted to the terminal outlet.

[0023] S8: Analyze the achievability of the target for improving the quality and efficiency of the sewage collection system. If the target is not met, return to S3 and adjust the water volume and water quality data of the drainage unit according to the sewage quality improvement and efficiency enhancement plan until the concentration value of the effluent at the end of the pipe network meets the assessment target requirements.

[0024] Preferably, the specific method for step S8 is as follows: The specific method for step S6 is as follows:

[0025] S601, determine the pollutant attenuation coefficient of the pipeline network. On a map of the drainage pipeline network topology, select representative inspection wells along the pipeline to monitor and analyze the concentration of target pollutants in the water. Based on the changes in concentration along the pipeline, calculate the average value of the pollutant attenuation coefficient along the pipeline.

[0026] S602, calculate the target pollutant attenuation coefficient for each drainage unit based on the transport distance from the inspection well connected to each drainage unit to the end outlet of the sewage collection pipeline network;

[0027] S603 calculates the concentration of target pollutants discharged from each drainage unit that are transported to the end outlet of the sewage collection network.

[0028] Preferably, the specific method for step S8 is as follows: The specific method for step S7 is as follows:

[0029] S701, calculate the target pollutant load of the effluent at the end of the pipe network based on the sewage discharge volume of each drainage unit and the concentration of pollutants converted to the end outlet;

[0030] S702, calculate the average concentration of the target pollutant at the outlet based on the total water volume at the end of the sewage collection pipeline network and the total target pollution load.

[0031] Preferably, the specific method of step S8 above is as follows:

[0032] Compare the average concentration of the target pollutant at the outlet with the target concentration for improving the efficiency of the wastewater collection system. Analyze the achievability of the target of the wastewater collection system improvement plan. If the target is not met, repeat steps S3 to S8 to optimize and adjust the wastewater improvement plan and perform rapid analysis and calculation until the calculated value of the target pollutant concentration at the terminal outlet meets the assessment target requirements.

[0033] Furthermore, in steps S201 and S401, the sewage collection network includes sewage pipes and combined sewer pipes.

[0034] Furthermore, in step S302, when the actual water consumption of a drainage unit is limited, the water consumption indicators for different land use categories provided in the specifications can be used as a reference. Combined with the area of ​​each drainage unit, the average daily water consumption of each drainage unit can be calculated and repeatedly verified and adjusted against the average daily water sales volume within the sewage collection area. The average daily sewage volume of each drainage unit is then calculated using the conversion coefficient between water consumption and sewage volume.

[0035] Furthermore, in step S303, when the acquisition of target pollutant concentration data for a drainage unit is limited, representative pollution sources can be screened according to the land use type of the drainage unit, and samples can be taken for pollutant concentration detection to determine the target pollutant concentration values ​​for each type of drainage unit; when the detection of target pollutants in a drainage unit is limited, relevant literature or existing target pollutant concentration values ​​in similar areas can be referenced.

[0036] The beneficial effects of the rapid calculation method for the effluent concentration at the end of a wastewater collection system based on ArcGIS provided by this invention are as follows:

[0037] 1. This invention proposes a rapid calculation method for the effluent quality of wastewater collection systems based on ArcGIS. The system systematically introduces the detailed calculation process for quickly constructing the spatial topology of wastewater collection systems and drainage units using ArcGIS, and simplifies the quantitative calculation of the achievability of wastewater collection system quality improvement and efficiency enhancement goals. This calculation method enables simple and rapid quantitative calculation of pollutant concentrations in the effluent of wastewater collection systems, providing quantitative support for the evaluation and analysis of wastewater quality improvement and efficiency enhancement schemes.

[0038] 2. In ArcGIS software, this invention fully considers the spatial distribution of different types of drainage unit sources and their connection with the sewage collection network. Based on the transport distance from each drainage unit to the end outlet of the sewage collection network, the attenuation coefficient of the target pollutants of each drainage unit is determined. Therefore, it can more accurately quantify and calculate the concentration value of the target pollutants discharged from each drainage unit at the end outlet, as well as calculate the average concentration of the target pollutants at the end outlet.

[0039] 3. This method not only considers the impact of the spatial distribution of drainage units on the concentration of pollutants in the final effluent, but also saves the huge workload of building a quantitative model of the sewage collection system based on traditional model software. It can realize the whole process of calculating the water quality of the final effluent of the sewage collection system simply and quickly, and has strong replicability and scalability. It can be used for quantitative evaluation of improving the quality and efficiency of urban sewage collection systems. Attached Figure Description

[0040] Figure 1 This is a flowchart of the present invention;

[0041] Figure 2 This is a schematic diagram of the topology of the wastewater collection system of the present invention;

[0042] Figure 3 A diagram showing the spatial topology of the sewage collection pipe network in the example;

[0043] Figure 4 This is a spatial connection diagram of the sewage collection network and drainage unit in the example. Detailed Implementation

[0044] Example 1:

[0045] like Figure 2 As shown, the topological diagram of the sewage collection system in this invention includes a drainage unit ① within the sewage collection area, a connection pipe ② between the drainage unit and the municipal sewage inspection well, a sewage inspection well ③, a municipal sewage branch pipe ④, a municipal sewage trunk pipe ⑤, and a sewage collection network outlet ⑥.

[0046] like Figure 1 As shown, the process of this invention is as follows:

[0047] A rapid method for calculating the concentration of effluent at the end of a wastewater collection system based on ArcGIS includes the following steps:

[0048] S1: Select the wastewater collection area of ​​the wastewater collection system;

[0049] Specifically, based on the achievability analysis of the sewage collection system's quality improvement and efficiency enhancement goals, and combined with the sewage zoning, sewage and combined sewer distribution, and drainage unit distribution of the sewage collection system, the sewage collection system's water intake range is selected.

[0050] S2, Wastewater collection network data collection and processing: Creating a wastewater collection system topology diagram in ArcGIS:

[0051] S201, Collect current status survey data of sewage collection pipe network within the water collection range of sewage collection system, and the attribute information of the data includes information that can accurately describe the spatial distribution of sewage collection pipe network;

[0052] S202, Based on the pipeline network data obtained in S201, sort out the main pipes, branch pipes and branch pipes of the sewage collection pipeline network, as well as the attribute information of manholes and pipelines; among them, the attribute information of manholes includes X and Y coordinates and manhole number; the attribute information of pipelines includes the manhole numbers connected to the upstream and downstream and the pipeline length.

[0053] like Figure 3 As shown in S203, create a point-like shapefile layer for manholes and a current shapefile layer for pipelines in ArcGIS. Create attribute lists according to the attribute information in S202, and enter the attribute information of manholes and pipelines into the corresponding attribute tables to form a map of the spatial topology of the sewage collection pipeline network.

[0054] S3: Collection and processing of sewage discharge and pollutant data for drainage units; creation of basic data information map of drainage units in ArcGIS;

[0055] S301, investigate and collect the drainage unit types within the sewage collection system's water intake area, classify them according to land use type, import the drainage unit data and scope into ArcGIS to generate shp format data, and create an attribute table. The attribute information includes pollution source type, area, water consumption, and sewage volume.

[0056] Specifically, the investigation focused on the basic types and spatial distribution of drainage units. Based on remote sensing imagery, existing land use maps, and on-site surveys, the investigation collected information on the types and spatial distribution of drainage units within the wastewater collection system's catchment area, and categorized them according to land use type, such as residential communities, commercial buildings, public buildings, and industrial buildings.

[0057] Specifically, a spatial distribution map of drainage units is generated in ArcGIS. The drainage unit data and its extent are imported into ArcGIS to generate shapefile format data, and an attribute table is created. The attribute information includes, but is not limited to, pollution source type, area, water consumption, wastewater volume, and target pollutant concentration.

[0058] S302, determine the average daily sewage volume of each drainage unit within the sewage collection area of ​​the sewage collection system. The sewage volume of each drainage unit can generally be indirectly calculated by the water consumption of the drainage unit and the conversion factor between water consumption and sewage volume.

[0059] Specifically, the average daily sewage volume of each drainage unit within the sewage collection system's catchment area is determined. Priority is given to collecting actual water consumption data for each drainage unit. When obtaining actual water consumption data for a drainage unit is limited, it can be converted using water consumption indicators for different land use categories provided in the specifications. Specifically: 1) The area of ​​each drainage unit is statistically analyzed using geometric calculations in ArcGIS; 2) Water consumption indicators for different land use categories are selected from the "Urban Water Supply Engineering Planning Specification" (GB50282-2016) to calculate the average daily water consumption of each drainage unit, and this is repeatedly verified and adjusted against the average daily water supply within the sewage collection area; 3) The average daily sewage volume q of each drainage unit is calculated according to the conversion coefficient between water consumption and sewage volume (between 0.8 and 0.9). i ;

[0060] S303, determine the daily average concentration of target pollutants in the sewage collected by each drainage unit within the sewage collection area of ​​the sewage collection system;

[0061] Specifically, the average daily concentration of target pollutants in the sewage collected by each drainage unit within the sewage collection system's catchment area is determined. Priority is given to collecting existing target pollutant concentration test results from the effluent of each drainage unit. If obtaining target pollutant concentration data for a drainage unit is limited, representative pollution sources can be selected according to the drainage unit type, and effluent samples and target pollutant concentration tests can be conducted separately for each drainage unit to determine the target pollutant concentration values ​​for each type of drainage unit. If the detection of target pollutant concentrations in the effluent of a drainage unit is limited, relevant literature or existing target pollutant concentration values ​​(C) in similar areas are referenced. 0，i The target pollutant concentrations for each drainage unit were determined using the method described above and entered into the corresponding attribute list in ArcGIS.

[0062] S304. Import each drainage unit into ArcGIS and generate a spatial distribution map of each drainage unit. Calculate the input pollution source attribute information, including sewage volume and sewage quality index values, according to the above method.

[0063] Specifically, in ArcGIS, the wastewater discharge volume and target pollutant water quality concentration attribute values ​​of each drainage unit are determined, and a map of basic data information of the drainage unit is generated.

[0064] S4: Spatial connection between the drainage unit and the sewage collection system:

[0065] S401. Based on the survey data of the current status of the sewage collection pipe network within the sewage collection system's water intake area, sort out the spatial relationship between the outlet water of each drainage unit and the municipal sewage inspection well.

[0066] S402, based on the spatial relationship between the outflow pipes of each drainage unit and the municipal sewage inspection well, the drainage unit is associated with the nearest inspection well;

[0067] like Figure 4 As shown, specifically, in ArcGIS, according to the spatial relationship of each drainage unit's outlet pipe connecting to the municipal sewage inspection well, each drainage unit is connected to the sewage collection pipe network spatial topology map.

[0068] S5, Analyze and calculate the transport distance from each drainage unit to the outlet at the end of the pipe network:

[0069] The transport distance from each drainage unit to the outlet of the pipe network was analyzed and calculated. Based on ArcGIS spatial analysis functions, the pipe network length L from the inspection well to the outlet of the sewage collection pipe network connected to each drainage unit was statistically calculated. i ;

[0070] S6, determine the pollutant attenuation coefficient of the pipe network, and calculate the pollutant attenuation along the flow path in the effluent of each drainage unit:

[0071] S7. The weighted calculation of pollutant concentration in the effluent at the end of the pipe network is performed based on the sewage discharge volume of each drainage unit and the concentration of pollutants converted to the terminal outlet.

[0072] S8: Analyze the achievability of the target for improving the quality and efficiency of the sewage collection system. If the target is not met, return to S3 and adjust the water volume and water quality data of the drainage unit according to the sewage quality improvement and efficiency enhancement plan until the concentration value of the effluent at the end of the pipe network meets the assessment target requirements.

[0073] Preferably, the specific method for step S8 is as follows: The specific method for step S6 is as follows:

[0074] S601, determine the pollutant attenuation coefficient of the pipeline network. On a map of the drainage pipeline network topology, select representative inspection wells along the pipeline to monitor and analyze the concentration of the target pollutant in the water. Based on the change of concentration along the pipeline, calculate the average value of the pollutant attenuation coefficient k (1 / km).

[0075] S602, based on the transport length L from the inspection well to the end outlet of the sewage collection network connected to each drainage unit. i (km), calculate the target pollutant attenuation coefficient for each drainage unit, i.e., k i =k×L i .

[0076] S603, calculates the concentration of target pollutants discharged from each drainage unit transported to the end outlet of the sewage collection network, i.e., C1. i =C 0，i ×(1-k i ).

[0077] Preferably, the specific method for step S8 is as follows: The specific method for step S7 is as follows:

[0078] S701, based on the sewage discharge volume of each drainage unit and the pollutant concentration converted to the terminal outlet concentration, calculate the target pollutant load of the effluent at the end of the pipe network, i.e.

[0079] S702, based on the total water volume at the end of the sewage collection network outlet and the total target pollution load, calculate the average concentration of the target pollutant at the outlet, i.e.

[0080] Preferably, the specific method of step S8 above is as follows:

[0081] Analyze the achievability of the goals for improving the quality and efficiency of the wastewater collection system. Compare the average concentrations of target pollutants at the outlet. With the target concentration C for improving the quality and efficiency of the sewage collection system 目标 ,like If the standard is not met, repeat steps 3-8 to optimize the wastewater quality improvement and efficiency enhancement plan, and adjust the water volume and quality data of the drainage unit accordingly. Quickly analyze and calculate the target pollutant concentration at the end of the wastewater collection network outlet until the target concentration is achieved. That is, to meet the assessment target requirements.

[0082] Furthermore, in steps S201 and S401, the sewage collection network includes sewage pipes and combined sewer pipes.

[0083] Furthermore, in step S302, when the actual water consumption of a drainage unit is limited, the water consumption indicators for different land use categories provided in the specifications can be used as a reference. Combined with the area of ​​each drainage unit, the average daily water consumption of each drainage unit can be calculated and repeatedly verified and adjusted against the average daily water sales volume within the sewage collection area. The average daily sewage volume of each drainage unit is then calculated using the conversion coefficient between water consumption and sewage volume.

[0084] Furthermore, in step S303, when the acquisition of target pollutant concentration data for a drainage unit is limited, representative pollution sources can be screened according to the land use type of the drainage unit, and samples can be taken for pollutant concentration detection to determine the target pollutant concentration values ​​for each type of drainage unit; when the detection of target pollutants in a drainage unit is limited, relevant literature or existing target pollutant concentration values ​​in similar areas can be referenced.

[0085] Example 2:

[0086] Taking a typical urban sewage collection system in the Yangtze River Economic Belt as an example, this paper examines the current sewage collection system. Due to its early construction, the system suffers from severe structural and functional defects, including misconnections and indiscriminate discharge of sewage. This results in low BOD5 concentrations at the end of the sewage collection system, significantly hindering the efficiency improvement of downstream sewage treatment plants. To effectively evaluate the impact of sewage quality improvement and efficiency enhancement schemes on increasing BOD5 concentration at the end of the sewage collection system, this invention proposes a rapid calculation method for effluent concentration at the end of the sewage collection system based on ArcGIS. This method quickly and conveniently constructs the spatial topology of the sewage collection system and drainage units, and simplifies the quantitative calculation of effluent concentration values ​​at the end of the pipe network under the sewage collection system quality improvement and efficiency enhancement planning and design scheme. The first two steps of the implementation process are the collection of the system's water intake area, the collection and processing of basic data for the sewage collection pipe network, and the general process of generating a single map of the spatial topology of the sewage collection pipe network using ArcGIS software, which will not be elaborated here. Starting from step 3, establish the basic information map of the drainage unit, the spatial connection between the drainage unit and the sewage collection system, calculate the transport distance of the drainage unit to the end outlet of the pipeline network, calculate the attenuation of pollutants along the flow path in the effluent of the drainage unit, calculate the concentration of pollutants in the end effluent, and analyze the achievability of the quality improvement and efficiency enhancement goals:

[0087] Step 3: Collect and process wastewater discharge and pollutant data of the drainage unit, and create a basic data information map of the drainage unit in ArcGIS;

[0088] Step 3.1, based on remote sensing imagery, existing maps, and on-site surveys, investigate and collect information on the wastewater collection system's catchment area, drainage unit types, and spatial distribution. Figure 4 As shown. Drainage unit types include residential areas, commercial land, educational land, cultural land, public facilities, social welfare land, etc., totaling approximately 36 drainage units.

[0089] Step 3.2: Import the drainage unit data and its scope into ArcGIS to generate shapefile format data. At the same time, create an attribute table. The attribute information includes, but is not limited to, drainage unit type, area, water consumption, sewage volume, and target pollutant water quality concentration. The drainage unit area can be quickly obtained through ArcGIS's geometric calculation function.

[0090] Step 3.3: Due to the large number of drainage unit types and data volume in the sewage collection area, collecting actual water usage data for each drainage unit is quite difficult. Based on the current water usage indicators for various land use types, a conversion factor of 0.85 between water usage and sewage volume is used. The average daily sewage generation q of each pollution source is directly calculated in the drainage unit attribute list in ArcGIS based on the drainage unit area, water usage indicators, and conversion factor. i .

[0091] Step 3.4: Due to the large number of drainage unit types and data volume in the sewage collection area, it is difficult to collect actual water usage data for each drainage unit. In addition, representative pollution sources are selected for BOD5 concentration testing. At the same time, referring to literature and water quality index values ​​of pollution sources in similar areas of the Yangtze River Basin, the BOD5 water quality indexes for various pollution sources are determined as follows: residential areas 120 mg / L, commercial land 90 mg / L, educational land 125 mg / L, cultural land 110 mg / L, public facilities 115 mg / L, and social welfare land 80 mg / L. The BOD5 concentration of the effluent from each drainage unit is then entered into the corresponding attribute list in ArcGIS.

[0092] Step 3.5: In ArcGIS, determine the wastewater discharge volume and target pollutant concentration attributes for each drainage unit, and generate basic data information for the drainage units. Figure 1 open.

[0093] Step 4: Spatially connect the drainage units to the sewage collection system. In ArcGIS, according to the spatial relationship between the effluent from each drainage unit and the municipal sewage inspection well, connect each drainage unit to the sewage collection network spatial topology map, as shown below. Figure 4 As shown, the spatial connection between the drainage unit and the sewage collection system is established.

[0094] Step 5: Analyze and calculate the transport distance from each drainage unit to the outlet of the pipe network. Based on ArcGIS spatial analysis functions, calculate the pipe network lengths L1, L2, L3, ... L from the inspection well to the outlet of the sewage collection pipe network connected to each drainage unit. i ,like Figure 2 As shown.

[0095] Step 6: Determine the pollutant attenuation coefficient of the pipeline network and calculate the attenuation of pollutants along the flow path in the effluent of each drainage unit.

[0096] Step 6.1: On a map of the spatial topology of the sewage collection pipe network, select representative inspection wells along the main pipe to monitor and analyze the changes in BOD5 concentration; based on the changes in BOD5 concentration along the pipeline, calculate its average attenuation coefficient along the pipeline, which is approximately 0.10 (1 / km).

[0097] Step 6.2, based on the transport length L from the municipal inspection well to the end outlet of the sewage collection network for each drainage unit. i Calculate the target pollutant attenuation coefficient, i.e., k, for each drainage unit. i =0.10L i (1 / km).

[0098] Step 6.3: Calculate the concentration of the target pollutants discharged from each drainage unit at the end of the sewage collection network outlet, i.e., C.1，i =C 0，i ×(1-k i If the length of the drainage pipeline from the manhole to the outlet in a residential community is 800 meters, then the concentration of BOD5 discharged to the outlet is C. 1，1 =120×(1-0.10×800 / 1000)=110.4mg / L, and the calculation for other drainage units is similar.

[0099] Step 7: Calculate the weighted pollutant concentration at the end of the pipe network by calculating the wastewater discharge volume of each drainage unit and the concentration of pollutants converted to the terminal outlet.

[0100] Step 7.1: Based on the wastewater discharge volume of each drainage unit and its pollutant concentration converted to the final outlet concentration, calculate the target pollutant load of the effluent at the end of the pipe network, i.e.

[0101] Step 7.2: Based on the total water volume at the outlet of the wastewater collection network and the total target pollution load, calculate the average concentration of the target pollutant at the outlet, i.e. Based on the above calculation method, the average concentration at the end outlet of the sewage collection network in the implementation case area is...

[0102] Step 8: Analyze the achievability of the goals for improving the quality and efficiency of the wastewater collection system. Compare the average BOD5 concentration at the outlet of the pipeline terminal. With the target concentration C for improving the quality and efficiency of the sewage collection system 目标 =100mg / L, The assessment targets are met.

[0103] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The embodiments and features described in these embodiments can be arbitrarily combined without conflict. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A rapid calculation method for effluent water quality concentration at the end of a wastewater collection system based on ArcGIS, characterized by: Includes the following steps: S1: Select the wastewater collection area of ​​the wastewater collection system; S2: Wastewater collection network data collection and processing; establishing a wastewater collection system topology diagram in ArcGIS: S201, Collect current status survey data of sewage collection pipe network within the water collection range of sewage collection system, and the attribute information of the data includes information that can accurately describe the spatial distribution of sewage collection pipe network; S202, Based on the pipeline network data obtained in S201, sort out the main pipes, branch pipes and branch pipes of the sewage collection system, as well as the attribute information of manholes and pipelines; among them, the attribute information of manholes includes coordinates and manhole numbers; the attribute information of pipelines includes the manhole numbers connected to the upstream and downstream and the pipeline length. S203: Use ArcGIS to construct two layers and attribute lists for inspection wells and pipelines respectively; and enter the attribute information in S202 into the corresponding attribute table to form a map of the spatial topology of the sewage collection pipeline network. S3: Collection and processing of sewage discharge and pollutant data for drainage units; creation of basic data information map of drainage units in ArcGIS; S301, Investigate the drainage unit types within the wastewater collection system and classify them according to land use type. Import the drainage unit data and scope into ArcGIS to generate shp format data. At the same time, create an attribute table with attribute information including pollution source type, area, water consumption, and wastewater volume. S302, determine the average daily sewage volume of each drainage unit within the sewage collection area of ​​the sewage collection system. The sewage volume of each drainage unit is indirectly calculated by using the water consumption of the drainage unit and the conversion factor between water consumption and sewage volume. S303, determine the daily average concentration of target pollutants in the sewage collected by each drainage unit within the sewage collection area of ​​the sewage collection system; S304. Import each drainage unit into ArcGIS and generate a spatial distribution map of each drainage unit. Calculate the input pollution source attribute information, including wastewater volume and target pollutant concentration, according to the above method. S4: Spatial connection between the drainage unit and the sewage collection system: S401. Based on the survey data of the current status of the sewage collection pipe network within the sewage collection system's water intake area, sort out the spatial relationship between the outlet water of each drainage unit and the municipal sewage inspection well. S402, based on the spatial relationship between the outflow pipes of each drainage unit and the municipal sewage inspection well, the drainage unit is associated with the nearest inspection well; S5: Analyze and calculate the transport distance from each drainage unit to the outlet at the end of the pipe network: Based on ArcGIS spatial analysis, the transport distance from the access manhole of each drainage unit to the end outlet of the sewage collection pipeline network was calculated. S6: Determine the pollutant attenuation coefficient of the pipe network and calculate the pollutant attenuation along the flow path in the effluent of each drainage unit. S601, determine the pollutant attenuation coefficient of the pipeline network. On a map of the drainage pipeline network topology, select representative inspection wells along the pipeline to monitor and analyze the concentration of the target pollutant in the water. Based on the change of concentration along the pipeline, calculate the average value of the pollutant attenuation coefficient k along the pipeline. S602, based on the transport distance from the inspection well connected to each drainage unit to the end outlet of the sewage collection pipe network. Calculate the target pollutant attenuation coefficient for each drainage unit separately. ; S603, calculate the concentration of target pollutants discharged from each drainage unit that are transported to the end outlet of the sewage collection network. , Indicates the first The average daily concentration of the target pollutant in the sewage discharged into the sewer system for each drainage unit; S7: Calculate the target pollutant concentration in the effluent at the end of the pipe network by weighting the concentration of pollutants in the wastewater discharged from each drainage unit and their pollutant concentrations converted to the terminal outlet. S701, calculate the target pollutant load of the effluent at the end of the pipe network based on the sewage discharge volume of each drainage unit and the pollutant concentration converted to the terminal outlet. ; S702, Calculate the average concentration of the target pollutant at the outlet based on the total water volume at the end of the sewage collection network and the total target pollution load. ; This represents the average daily sewage volume of the i-th drainage unit; S8: Analyze the achievability of the wastewater collection system's quality improvement and efficiency enhancement targets. If the targets are not met, return to S3 and adjust the drainage unit's water volume and quality data according to the wastewater quality improvement and efficiency enhancement plan until the target pollutant concentration value of the effluent at the end of the pipe network meets the assessment target requirements. Specifically: Compare the average concentration of target pollutants at the outlet. With the target concentration for improving the quality and efficiency of the sewage collection system ,like If the standard is not met, repeat steps S3-S8 to optimize the wastewater quality improvement and efficiency enhancement plan, and adjust the water volume and quality data of the drainage unit accordingly. Quickly analyze and calculate the target pollutant concentration at the end of the wastewater collection network outlet until the target concentration is achieved. This means meeting the assessment target requirements.

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