Method for judging key area of inflow of water outside drainage pipe network, evaluating rationality of sewage plant and estimating effect of pipe network repair project

Abstract

The invention discloses a drainage pipe network external water inflow key area discrimination, sewage plant rationality evaluation and pipe network repair engineering effect estimation method, and belongs to the technical field of water supply and drainage and municipal engineering. The distinguishing method comprises the following steps: step 1, dividing the drainage pipe network into a plurality of areas; 2, listing an equation set for the districts; 3, measuring and calculating background flow Qb and background concentration Cb; 4, measuring and calculating the total external water concentration Cw; 5, measuring and calculating the total effluent concentration Ct; sixthly, the total transfer water flow Qz and the total transfer water concentration Cz are measured and calculated; step 7, solving the value of Qw / Qt; and 8, completing the judgment of the drainage pipe network external water inflow key area. According to the invention, areas with serious inflow of external water can be checked in a targeted manner, the checking cost is reduced, and the checking efficiency is improved.

Description

Technical Field

[0001] The invention relates to a method for distinguishing key areas of external water inflow in a drainage network, evaluating the rationality of a sewage plant and predicting the effect of a network repair project, and belongs to the technical field of water supply and drainage and municipal engineering. Background Art

[0002] For the in-depth inspection and repair projects of drainage pipe networks, it is of great significance to identify key areas of external water inflow based on water quantity and quality data. However, there are few studies and applications on how to use water quality and quantity data to analyze external water inflow.

[0003] The Chinese patent document with the publication number CN115577506A discloses a method for pre-diagnosis and accurate investigation of sewage pipe network problems. It conducts systematic research around the analysis of sewage system collection efficiency, investigation and construction of municipal pipe network topology, water quality and quantity monitoring, pipe network pre-diagnosis analysis, pipe network investigation, and inspection results acceptance, and establishes a set of pre-diagnosis and investigation methods that effectively reduce the scope of pipe network investigation and diagnosis and treatment problems and accurately screen out key areas of external water infiltration in sewage pipe networks. However, this method has the following shortcomings: First, the amount of information that needs to be collected is large, including regional population data, surface water system maps with historical evolution and river and lake water level and quality, as well as regional water supply quantity data, etc.; second, the workload is large, including investigation and construction of municipal pipe network topology, monitoring of water quality and quantity, pre-diagnosis analysis of pipe networks, etc.; third, the efficiency is low, the implementation is difficult, and it is not easy to promote.

[0004] The Chinese patent document with the publication number CN118071002A discloses a method for positioning, qualitative and quantitative analysis of external water intrusion into the municipal sewage pipe network. By selecting multiple sampling points, the sewage ammonia nitrogen concentration at each sampling point is detected. Since the external water invading or flowing into the sewage pipe network is at a relatively low ammonia nitrogen concentration level, and the ammonia nitrogen value is not affected by the pipe sediment, ammonia nitrogen is used as an indicative analysis factor for external water intrusion. By analyzing the ammonia nitrogen concentration at the sampling point, the abnormal change area of ​​ammonia nitrogen concentration lower than the upstream sampling point or the surrounding pipe network is identified, thereby analyzing the specific pipe section invaded by external water. The positioning method is not affected by objective conditions on site such as pipe water level, siltation, and sediment. However, this method has the following shortcomings: First, the drainage pipe network is relatively complex, and it is inevitable that the sampling points selected only by relying on the experience of engineering personnel lack systematicity; second, the data collected from the sampling points need to be compared with the data of the same year or different years, which makes the method limited, time-consuming and inefficient. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for identifying key areas of external water inflow into a drainage network, evaluating the rationality of a sewage treatment plant, and predicting the effect of a network repair project.

[0006] The present invention is achieved through the following technical solutions: A method for identifying key areas of external water inflow in a drainage network comprises the following steps: Step 1: Divide the drainage network into multiple areas; Step 2: According to the flow balance and pollutant balance, each area has the following equations: , , In the formula, , , , Corresponding to the total outflow flow, background flow, total external water flow, and total water transfer flow of the area, the unit is m 3 / d, , , , The corresponding values ​​are the total outflow concentration, background concentration, total external water concentration, and total transferred water concentration of the area, in mg / L; Step 3: Calculate background flow and background concentration ; Step 4: Calculate the total external water concentration ; Step 5: Calculate the total outflow concentration ; Step 6: Calculate the total water transfer flow and total transfer water concentration ; Step 7: Use the equations in step 2 to solve for the total outflow rate and total external water flow ,and / The value of Step 8: Repeat steps 3 to 7 to get all the areas / and compare them. / The larger the value is, the more serious the external water inflow into the area is, and the key areas of external water inflow in the drainage network can be identified.

[0007] After the drainage network is divided into multiple areas in step 1, the networks of all areas are relatively independent, that is, all sewage in any area comes from the sewage source of the area, and no sewage from other areas flows into the area.

[0008] In the process of dividing the areas in step 1, if an area cannot drain the sewage from another area, the two areas are merged into one area; or, if the number of points where the sewage from another area flows into this area does not exceed 5, and the total transfer flow of the sewage from another area into this area can be independently measured, and total transfer water concentration , they can also be divided into two areas.

[0009] The total outflow concentration , background concentration , total external water concentration and total transfer water concentration It refers to the characteristic water quality indicators of sewage, which are the COD concentration, ammonia nitrogen concentration, total nitrogen concentration or total phosphorus concentration of sewage.

[0010] The background flow and background concentration It refers to the flow rate and concentration of all sewage generated by sewage sources in a certain area when there is no inflow of external water.

[0011] The area is composed of various types of drainage units, including residential areas, urban villages, commercial areas, public buildings, catering areas, industrial areas or schools. The background flow of sewage in the area is calculated by taking advantage of the fact that the water quality and quantity discharge patterns of drainage units of the same type are similar. and background concentration , specifically including the following steps: Step 1: When the drainage unit is a residential area, urban village, commercial area, public building or catering area, calculate the unit area flow of the drainage unit according to the following formula: , In the formula, the flow rate per unit area is The unit is m 3 / d / m 2 , n is the number of representative drainage outlet points selected in the drainage unit, i For the i The drainage outlet represents the point. For the i The sewage flow rate measured at each outlet represents a For the i The area of ​​sewage source received by each drainage outlet representative point; Then, the pollutant concentration of the drainage unit is calculated as follows: , In the formula, For the iPollutant concentration measured at representative points of each drainage outlet; Step 2: When the type of drainage unit is an industrial area or a school, directly measure its sewage flow and pollutant concentration; Step 3: Calculate the background flow of sewage in the area and background concentration : In the formula, m is the number of drainage units in the area excluding industrial areas and schools, 、 、 The corresponding area is the area except for industrial areas and schools. i The area, flow rate per unit area, and pollutant concentration of the drainage unit. , Corresponding to the sewage flow of schools and industrial areas in the area, , This corresponds to the pollutant concentration in schools and industrial areas within the area; Solving the equations, we can get the background flow of sewage in the area. and background concentration .

[0012] The unit area flow rate of the drainage unit in step 1 and pollutant concentrations These are the values ​​calculated on the same day; The area of ​​the drainage unit in step 3 By measuring on satellite maps.

[0013] The total external water concentration in step 4 Direct measurement method is used for calculation: groundwater is sampled at any number of points in the area, and the average pollutant concentration of the groundwater is taken as the total external water concentration. .

[0014] The total external water concentration in step 4 Obtained through local groundwater quality monitoring data: In areas where groundwater quality monitoring is available, the monitored groundwater pollutant concentration is directly used as the total external water concentration. If the groundwater pollutant concentration fluctuates, the groundwater pollutant concentration in the same period of the previous year shall be taken as the total external water concentration. If there are multiple groundwater quality monitoring points, the average groundwater pollutant concentration monitored by all monitoring points is taken as the total external water concentration. .

[0015] The total external water concentration in step 4 Use the water quality of adjacent rivers instead: If the groundwater data in the area is difficult to measure and there is no historical data, the pollutant concentration of the river adjacent to the area is used as the total external water concentration .

[0016] The total outflow concentration is calculated in step 5 The method is: select 5 or more sewage outlets in the area to measure the pollutant concentration, and then calculate the average value as the total outflow concentration of the area. .

[0017] A method for evaluating the rationality of a sewage treatment plant is provided. The drainage network within the water collection range of the sewage treatment plant is divided into zones, and the following set of equations exists: In the formula, , Corresponding to the influent flow and influent concentration of the sewage treatment plant in one day, , Corresponding to i The total outflow and total water transfer flow of the area, , Corresponding to i Total outflow concentration and total transfer water concentration of the area; Calculate the daily inflow flow of sewage treatment plant using relative error method The rationality value , and the reasonable value of the total amount of pollutants in the sewage plant's water per day , A method for estimating the effect of a sewage treatment plant pipe network repair project, wherein the drainage pipe network within the water collection range of the sewage treatment plant is divided into areas, and the method for estimating the effect of a sewage treatment plant pipe network repair project comprises the following steps: Step A: Assuming that the sewage treatment plant network is repaired, i Areas can be excluded The flow of external water, For the i The pipeline network repair effect index of each area, For the i Total external water flow in each area; Step B, select the area where the pipe network is to be repaired, that is, select N areas with a large total external water flow from all the areas within the water collection range of the sewage treatment plant to repair the pipe network; Step C: Calculate the estimated sewage plant inflow flow after the pipe network repair is completed and estimate the influent concentration of the sewage treatment plant , In the formula, is the actual inflow flow of the current sewage treatment plant, is the actual influent concentration of the current sewage treatment plant, For the i The total external water concentration in the area, i ≤N; Step D: Estimated sewage plant inflow flow The actual water flow rate of the current sewage treatment plant Calculate the difference and estimate the sewage plant influent concentration Compared with the actual influent concentration of the current sewage plant Calculate the difference, and then estimate the effect of the sewage plant pipe network repair project based on the difference.

[0018] The said i Pipeline network repair effect index for each area The value of is 1, 0.8, 0.6, 0.4 or 0.2.

[0019] The beneficial effects of the present invention are: 1. Divide the drainage network into multiple areas, and then calculate the severity characterization data of external water inflow in each area. / The value of can then be compared to visually identify areas where external water inflow is more serious, so that these areas can be checked in a targeted manner, reducing the cost of checking the drainage network and significantly improving the efficiency of the check.

[0020] 2. Compared with the prior art, the present invention has the following technical effects: First, the amount of information that needs to be collected is significantly reduced. It is only necessary to collect information such as the drainage network, water flow and concentration in each area, and the type of drainage unit in each area, without collecting regional population data, surface water system maps containing historical evolution, and river and lake water levels in the prior art; Second, the workload is reduced, and there is no need to carry out pre-diagnosis analysis of the network in the prior art; Third, the scheme is simple, highly feasible, and easy to promote; Fourth, the drainage network is first divided into multiple areas, and then the areas are divided into multiple types of drainage units, and water quality is sampled and tested in a targeted manner, so that the characterization data of the severity of external water inflow in each area can be calculated. / The value of , and then through comparison, the area where the external water inflow is more serious can be intuitively obtained, which has strong systematicity; fifthly, the collected data does not need to be compared with the data of the same year or different years, which is highly practical, time-saving and efficient.

[0021] 3. For the sewage treatment plant pipe network repair project, it is usually necessary to answer a question: how much can the sewage treatment plant inlet water concentration be improved after the completion of the pipe network repair project. In the present invention, since the total external water flow and total external water concentration of each area have been calculated through the key area identification method of external water inflow of the drainage pipe network, the sewage treatment plant pipe network repair project effect estimation method is used to calculate the value of the sewage treatment plant inlet water concentration that can be improved by the pipe network repair project, and the problem is quantitatively answered. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0023] The present invention provides a method for distinguishing key areas of water inflow from outside of a drainage network, comprising the following steps: Step 1: Divide the drainage network into multiple areas; Step 2: According to the flow balance and pollutant balance, each area has the following equations: , , In the formula, , , , Corresponding to the total outflow flow, background flow, total external water flow, and total water transfer flow of the area, the unit is m 3 / d, , , , The corresponding values ​​are the total outflow concentration, background concentration, total external water concentration, and total transferred water concentration of the area, in mg / L; Step 3: Calculate background flow and background concentration ; Step 4: Calculate the total external water concentration ; Step 5: Calculate the total outflow concentration ; Step 6: Calculate the total water transfer flow and total transfer water concentration ; Step 7: Use the equations in step 2 to solve for the total outflow rate and total external water flow ,and / The value of Step 8: Repeat steps 3 to 7 to get all the areas / and compare them. / The larger the value, the more serious the external water inflow into the area, and the key areas of external water inflow in the drainage network can be identified. When using it, first divide the drainage network into multiple areas, and then calculate the characterization data of the severity of external water inflow in each area. / The value of can then be compared to visually identify areas where external water inflow is more serious, so that these areas can be checked in a targeted manner, reducing the cost of checking the drainage network and significantly improving the efficiency of the check.

[0024] Compared with the prior art with publication number CN115577506A, the present invention has the following technical effects: First, the amount of information that needs to be collected by the present invention is significantly reduced. It only needs to collect information such as the drainage network, water flow and concentration in each area, and the type of drainage unit in each area. There is no need to collect regional population data, surface water system maps including historical evolution, river and lake water levels, and other information in the prior art.

[0025] Second, the workload is reduced, and there is no need to carry out pre-diagnosis analysis of the pipeline network as in existing technologies.

[0026] Third, the plan is simple, highly feasible and easy to promote.

[0027] Compared with the prior art with publication number CN118071002A, the present invention has the following technical effects: First, the drainage network is divided into multiple areas, and then the areas are divided into multiple types of drainage units. The water quality is tested by sampling in a targeted manner, and the characterization data of the severity of external water inflow in each area can be calculated. / The value of , and then by comparison, we can intuitively get the area where the external water inflow is more serious, which has strong systematicity.

[0028] Second, the collected data does not need to be compared with data from the same year or different years. It is highly practical, time-saving and efficient.

[0029] After the drainage network is divided into multiple areas in step 1, the networks of all areas are relatively independent, that is, all sewage in any area comes from the sewage source of the area, and no sewage from other areas flows into the area.

[0030] In the process of dividing the areas in step 1, if an area cannot drain the sewage from another area, the two areas are merged into one area; or, if the number of points where the sewage from another area flows into this area does not exceed 5, and the total transfer flow of the sewage from another area into this area can be independently measured, and total transfer water concentration , they can also be divided into two areas. In step 1, the drainage network is divided into multiple areas to facilitate subsequent measurement. While ensuring the accuracy of the measurement results, it is easy to quickly find the areas with more serious external water inflow, so as to reduce the cost of investigation and improve the efficiency of investigation.

[0031] The total outflow concentration , background concentration , total external water concentration and total transfer water concentration Refers to the characteristic water quality index of sewage, which is the COD concentration, ammonia nitrogen concentration, total nitrogen concentration or total phosphorus concentration of sewage. When using it, you can choose to test the COD concentration, ammonia nitrogen concentration, total nitrogen concentration or total phosphorus concentration of sewage as the total outflow concentration according to the test conditions and the relatively inert characteristic water quality indicators of the target area. , background concentration , total external water concentration and total transfer water concentration .

[0032] The background flow and background concentration It refers to the flow rate and concentration of all sewage generated by sewage sources in a certain area when there is no inflow of external water.

[0033] The area is composed of various types of drainage units, including residential areas, urban villages, commercial areas, public buildings, catering areas, industrial areas or schools. The background flow of sewage in the area is calculated by taking advantage of the fact that the water quality and quantity discharge patterns of drainage units of the same type are similar. and background concentration , specifically including the following steps: Step 1: When the drainage unit is a residential area, urban village, commercial area, public building or catering area, calculate the unit area flow of the drainage unit according to the following formula: , In the formula, the flow rate per unit area is The unit is m 3 / d / m 2 , n is the number of representative drainage outlet points selected in the drainage unit, i For the i The drainage outlet represents the point. For the i The sewage flow rate measured at each outlet represents a For the i The drainage outlet represents the area of ​​sewage source received by the point, for example, i The representative point of the drainage outlet is the total drainage outlet of a certain community, then Indicates the area of ​​this community; Then, the pollutant concentration of the drainage unit is calculated as follows: , In the formula, For the i Pollutant concentration measured at representative points of each drainage outlet; Step 2: When the type of drainage unit is an industrial area or a school, directly measure its sewage flow and pollutant concentration; Step 3: Calculate the background flow of sewage in the area and background concentration : In the formula, m is the number of drainage units in the area excluding industrial areas and schools, 、 、 The corresponding area is the area except for industrial areas and schools. i The area, flow rate per unit area, and pollutant concentration of the drainage unit. , Corresponding to the sewage flow of schools and industrial areas in the area, , This corresponds to the pollutant concentration in schools and industrial areas within the area; Solving the equations, we can get the background flow of sewage in the area. and background concentration .

[0034] Background flow of sewage in the area and background concentration It is extremely important for the subsequent analysis of the severity of external water inflow and infiltration. In step 1, when the type of drainage unit is residential area, urban village, commercial area, public building or catering area, it is difficult to obtain data due to the wide distribution of buildings. Therefore, the drainage unit is selected n The sewage flow and area at the representative points of the drainage outlets are measured, and then the sewage flow is normalized by the area. Finally, the average value is calculated to obtain the unit area flow of the drainage unit. , which is convenient for the implementation and promotion of the scheme. In step 2, since industrial areas and schools are relatively concentrated, and the number of drainage outlets is relatively small compared to the number of drainage outlets in other drainage units, independent measurements can be made without the need to normalize the data.

[0035] n is the number of representative drainage outlet points selected in the drainage unit The unit area flow rate of the drainage unit in step 1 and pollutant concentrations These are the values ​​calculated on the same day; The area of ​​the drainage unit in step 3 By measuring on satellite maps. To ensure the reliability of the data, the unit area flow of the drainage unit in step 1 is and pollutant concentrations These are values ​​calculated on the same day.

[0036] The total external water concentration in step 4 Direct measurement method is used for calculation: groundwater is sampled at any number of points in the area, and the average pollutant concentration of the groundwater is taken as the total external water concentration. . Direct measurement method to calculate total external water concentration The difficulty is relatively high, but the information obtained is more accurate.

[0037] The total external water concentration in step 4 Obtained through local groundwater quality monitoring data: In areas where groundwater quality monitoring is available, the monitored groundwater pollutant concentration is directly used as the total external water concentration. If the groundwater pollutant concentration fluctuates, the groundwater pollutant concentration in the same period of the previous year shall be taken as the total external water concentration. If there are multiple groundwater quality monitoring points, the average groundwater pollutant concentration monitored by all monitoring points is taken as the total external water concentration. . Obtain total external water concentration through local groundwater quality monitoring data This method is easy to obtain data and accurate information, but it has high geographical requirements.

[0038] The total external water concentration in step 4 Use the water quality of adjacent rivers instead: If the groundwater data in the area is difficult to measure and there is no historical data, the pollutant concentration of the river adjacent to the area is used as the total external water concentration It is worth noting that after the river water passes through the soil and reaches the drainage pipe, it will be purified to a certain extent, so the actual external water concentration It should be lower than the pollutant concentration in rivers. External water is usually composed of river water, lake water, and groundwater. The total external water concentration is In most cases, it is far lower than the sewage concentration, so the inflow of external water will cause the sewage treatment plant influent concentration to be low. You can use one of the above three methods to detect the total external water concentration .

[0039] When in use, the entire drainage network uses the same total external water concentration , therefore, the total external water concentration Only for total external water flow It has an impact on the absolute value of the area, but has no impact on the ranking of the severity of inflow in the area.

[0040] The total outflow concentration is calculated in step 5 The method is: select 5 or more sewage outlets in the area to measure the pollutant concentration, and then calculate the average value as the total outflow concentration of the area. When in use, a region usually has a large number of sewage outlets, and the total outflow rate Difficult to measure, but the total outflow concentration The pollutant concentration can be estimated by measuring the average value of multiple sewage outlets. The sewage outlet here refers to the well location before the area merges into the main pipe.

[0041] A method for evaluating the rationality of a sewage treatment plant is provided. The drainage network within the water collection range of the sewage treatment plant is divided into zones, and the following set of equations exists: In the formula, , Corresponding to the influent flow and influent concentration of the sewage treatment plant in one day, , Corresponding to i The total outflow and total water transfer flow of the area, , Corresponding to i The total outflow concentration and total transfer water concentration of the area. and total transfer water concentration It is not actually generated in this area, so it needs to be subtracted when calculating the influent flow and influent concentration of the sewage treatment plant.

[0042] Calculate the daily inflow flow of sewage treatment plant using relative error method The rationality value , and the reasonable value of the total amount of pollutants in the sewage plant's water per day , The present invention does not provide the daily water flow rate of the sewage treatment plant. The rationality value , and the reasonable value of the total amount of pollutants in the sewage plant's water per day The specific threshold value can be determined according to the actual project.

[0043] A method for estimating the effect of a sewage treatment plant pipe network repair project, wherein the drainage pipe network within the water collection range of the sewage treatment plant is divided into areas, and the method for estimating the effect of a sewage treatment plant pipe network repair project comprises the following steps: Step A: Assuming that the sewage treatment plant network is repaired, i Areas can be excluded The flow of external water, For the i The pipeline network repair effect index of each area, For the i Total external water flow in each area; Step B, select the area where the pipe network is to be repaired, that is, select N areas with a large total external water flow from all the areas within the water collection range of the sewage treatment plant to repair the pipe network; Step C: Calculate the estimated sewage plant inflow flow after the pipe network repair is completed and estimate the influent concentration of the sewage treatment plant , In the formula, is the actual inflow flow of the current sewage treatment plant, is the actual influent concentration of the current sewage treatment plant, For the i The total external water concentration in the area, i ≤N; Step D: Estimated sewage plant inflow flow The actual water flow rate of the current sewage treatment plant Calculate the difference and estimate the sewage plant influent concentration Compared with the actual influent concentration of the current sewage plant Calculate the difference, and then estimate the effect of the sewage treatment plant network repair project based on the difference. Current actual water flow of the sewage treatment plant And the actual influent concentration of the current sewage treatment plant Can be measured directly.

[0044] The said i Pipeline network repair effect index for each area The value of can be 1, 0.8, 0.6, 0.4 or 0.2. Substitute different values ​​of into the above equations for sensitivity calculation to obtain the value by which the pipeline network repair can increase the sewage plant inlet concentration, so as to estimate the effect of the sewage plant pipeline network repair project; or estimate the project effect based on the investment amount.

Claims

1. A method for identifying key areas of water inflow from outside a drainage network, characterized in that: The following steps are involved: Step 1: Divide the drainage network into multiple areas; Step 2: According to the flow balance and pollutant balance, each area has the following equations: Q t =Q b +Q w +Q z , Q t C t =Q b C b +Q w C w +Q z C z , In the formula, Q t , Q b , Q w , Q z Corresponding to the total outflow flow, background flow, total external water flow, and total water transfer flow of the area, the unit is m 3 / d,C t , C b , C w , C z The corresponding values ​​are the total outflow concentration, background concentration, total external water concentration, and total transferred water concentration of the area, in mg / L; Step 3: Calculate the background flow Q b and background concentration C b ; Step 4: Calculate the total external water concentration C w ; Step 5: Calculate the total outflow concentration C t ; Step 6: Calculate the total water transfer flow Q z and total transfer water concentration C z ; Step 7: Use the equations in step 2 to solve for the total outflow rate Q t and the total external water flow Q w , and Q w / Q t The value of Step 8: Repeat steps 3 to 7 to get all the regions Q w / Q t The value of Q w / Q t The larger the value is, the more serious the external water inflow into the area is, and the key areas of external water inflow in the drainage network can be identified.

2. The method for distinguishing key areas of water inflow from outside the drainage network according to claim 1, characterized in that: After the drainage network is divided into multiple areas in step 1, the networks of all areas are relatively independent, that is, all sewage in any area comes from the sewage source of the area, and no sewage from other areas flows into the area.

3. The method for distinguishing key areas of water inflow from outside the drainage network according to claim 2, characterized in that: In the process of area division in step 1, if a certain area cannot exclude sewage from another area flowing into it, the two areas are merged into one area; or, if the number of points where another area flows into this area does not exceed 5, and the total transfer flow rate Q of another area flowing into this area can be independently measured z and total transfer water concentration C z , they can also be divided into two areas.

4. The method for identifying key areas of water inflow from outside the drainage network according to claim 1, characterized in that: The total outflow concentration C t , background concentration C b , total external water concentration C w and total transfer water concentration C z It refers to the characteristic water quality indicators of sewage, which are the COD concentration, ammonia nitrogen concentration, total nitrogen concentration or total phosphorus concentration of sewage.

5. The method for identifying key areas of water inflow from outside the drainage network according to claim 1, characterized in that: The background flow Q b and background concentration C b It refers to the flow rate and concentration of all sewage generated by sewage sources in a certain area when there is no inflow of external water.

6. The method for identifying key areas of water inflow from outside the drainage network according to claim 1, characterized in that: The area is composed of various types of drainage units, including residential areas, urban villages, commercial areas, public buildings, catering areas, industrial areas or schools. The background flow rate Q of sewage in the area is calculated by taking advantage of the fact that the water quality and quantity discharge patterns of drainage units of the same type are similar. b and background concentration C b , specifically including the following steps: Step 1: When the drainage unit is a residential area, urban village, commercial area, public building or catering area, calculate the unit area flow rate q of the drainage unit according to the following formula: 单元 , In the formula, the flow rate per unit area q 单元 The unit is m 3 / d / m 2 , n is the number of drainage outlet representative points selected in the drainage unit, i is the i-th drainage outlet representative point, Q i is the sewage flow measured at the representative point of the i-th drainage outlet, S i is the area of ​​sewage source received by the representative point of the i-th drainage outlet; Then, the pollutant concentration C of the drainage unit is calculated as follows: 单元 , In the formula, C i is the pollutant concentration measured at the representative point of the i-th drainage outlet; Step 2: When the type of drainage unit is an industrial area or a school, directly measure its sewage flow and pollutant concentration; Step 3: Calculate the background flow rate Q of sewage in the area b and background concentration C b : Where m is the number of drainage units in the area excluding industrial areas and schools, A i ,q i , C i It corresponds to the area, unit area flow, and pollutant concentration of the i-th type of drainage unit in the area except for industrial areas and schools, Q 学校 , Q 工业 Corresponding to the sewage flow of schools and industrial areas in the area, C 学校 , C 工业 This corresponds to the pollutant concentration in schools and industrial areas within the area; Solving the equations, we can get the background flow rate Q of sewage in the area. b and background concentration C b .

7. The method for identifying key areas of water inflow from outside the drainage network according to claim 6, characterized in that: The unit area flow rate q of the drainage unit in step 1 单元 and pollutant concentration C 单元 These are the values ​​calculated on the same day; The area A of the drainage unit in step 3 i By measuring on satellite maps.

8. The method for identifying key areas of water inflow from outside the drainage network according to claim 1, characterized in that: The total external water concentration C in step 4 w Direct measurement method is used for calculation: sampling of groundwater at multiple points in the area is performed, and then the average pollutant concentration of groundwater is taken as the total external water concentration C. w .

9. The method for identifying key areas of water inflow from outside the drainage network according to claim 1, characterized in that: The total external water concentration C in step 4 w Obtained through local groundwater quality monitoring data: In areas where groundwater quality monitoring is available, the monitored groundwater pollutant concentration is directly used as the total external water concentration C w If the groundwater pollutant concentration fluctuates, the groundwater pollutant concentration in the same period of the previous year shall be taken as the total external water concentration C w If there are multiple groundwater quality monitoring points, the average groundwater pollutant concentration monitored by all monitoring points is taken as the total external water concentration C w .

10. The method for identifying key areas of water inflow from outside the drainage network according to claim 1, characterized in that: The total external water concentration C in step 4 w Use the water quality of the adjacent river as a substitute: If the groundwater data in the area is difficult to measure and there is no historical data, the pollutant concentration of the river adjacent to the area is used as the total external water concentration C w .

11. The method for identifying key areas of water inflow from outside the drainage network according to claim 1, characterized in that: In step 5, the total outflow concentration C is calculated. t The method is: select 5 or more sewage outlets in the area to measure the pollutant concentration, and then calculate the average value as the total outflow concentration C of the area. t .

12. A method for evaluating the rationality of a sewage treatment plant, characterized by: The drainage network within the water collection range of the sewage treatment plant is divided into areas according to any one of claims 1 to 11, and the following set of equations exists: Q ww =∑(Q t，i -Q z，i ), Q ww C ww =∑(Q t，i C t，i -Q z，i C z，i ), In the formula, Q ww , C ww Corresponding to the daily influent flow and influent concentration of the sewage treatment plant, Q t，i , Q z，i Corresponding to the total outflow and total transfer flow of the ith area, C t，i , C z，i The corresponding values ​​are the total outflow concentration and total transfer water concentration of the ith area; Calculate the daily inflow flow rate Q of the sewage treatment plant using the relative error method ww The rationality value ε q , and the rationality value of the total amount of pollutants in the sewage plant's water per day ε qc , 13. A method for estimating the effect of a sewage treatment plant pipe network repair project, characterized in that: The drainage pipe network within the water collection range of the sewage treatment plant is divided into areas as described in any one of claims 1 to 11, and the sewage treatment plant pipe network repair project effect estimation method comprises the following steps: Step A: Assume that after the sewage treatment plant network is repaired, the i-th area can exclude λ i Q w，i Flow rate of external water, λ i is the pipeline network repair effect index of the ith area, Q w，i is the total external water flow of the ith area; Step B, select the area where the pipe network is to be repaired, that is, select N areas with a large total external water flow from all the areas within the water collection range of the sewage treatment plant to repair the pipe network; Step C: Calculate the estimated sewage plant inflow flow Q' after the pipe network repair is completed ww And estimate the sewage treatment plant influent concentration C′ ww , Q′ ww =Q ww -∑λ i Q w，i , In the formula, Q ww is the actual inflow flow of the current sewage treatment plant, C ww is the actual influent concentration of the current sewage treatment plant, C w，i is the total external water concentration of the i-th area, i≤N; Step D: Estimated sewage plant inflow flow Q' ww The actual inflow flow rate Q of the current sewage treatment plant ww Calculate the difference and estimate the sewage plant influent concentration C′ ww Compared with the actual influent concentration C of the current sewage plant ww Calculate the difference, and then estimate the effect of the sewage plant pipe network repair project based on the difference.

14. The method for predicting the effect of sewage treatment plant pipe network repair project according to claim 13, characterized in that: The pipeline network repair effect index λ of the i-th area i The value of is 1, 0.8, 0.6, 0.4 or 0.2.

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