River sewage draining exit improvement priority evaluation method

Abstract

The invention provides a method for evaluating the improvement priority of a sewage draining exit of a river. The method comprises the following steps: establishing a river water quality mathematical model; calculating the influence contribution coefficient and the influence contribution index of the drainage of the river-entering drain outlet on the water quality of the control section; and calculating a corresponding index improvement difficulty index, an in-river sewage draining exit improvement difficulty index and in-river sewage draining exit improvement priority. According to the method, a calculation model of the influence contribution index of the river sewage draining exit to the control section water quality and the improvement difficulty index of the river sewage draining exit is established according to the water draining quantity, the water quality, the influence contribution to the control section water quality, the water collecting range, the water draining partition pipe network coverage, the problem type and the type of the river sewage draining exit; and utilizing the influence contribution index and the improvement difficulty index to establish the improvement priority of the sewage draining exit into the river. And the corresponding river sewage outlet is treated according to the treatment priority, so that the sewage treatment efficiency and key point are improved, and the problem of river pollution caused by inaccurate treatment is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of river sewage discharge assessment, in particular to a method for assessing the priority of river sewage outlet regulation. Background Art

[0002] River outfalls are key points where land-based pollutants enter river waters within a river basin, making their remediation a crucial component of water pollution prevention and control. Rivers typically have industrial outfalls, urban sewage treatment plant outfalls, agricultural outfalls, and other types of outfalls with varying discharge volumes and pollutant concentrations. These outfalls have varying impacts on river water quality and pose varying challenges to remediation. Therefore, addressing the numerous and diverse river outfalls requires the development of scientific, organized, and efficient remediation plans.

[0003] Currently, most approaches to remediation focus on various types of sewage outlets, with priorities often determined based on the designers' experience. However, this empirically based order of remediation often overlooks the importance of each outlet's remediation for achieving water quality standards at the controlled section, as well as the human and material resources required to remediate each outlet. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a method for evaluating the priority of river sewage outlet remediation. The present invention gives higher priority to the remediation of river sewage outlets, thereby improving the efficiency of sewage discharge remediation.

[0005] The technical solution of the present invention is: a method for evaluating the priority of river sewage outlet remediation, comprising the following steps:

[0006] S1) Establish a river water quality mathematical model based on the river hydrological conditions and the water volume, water quality and spatial distribution of the sewage outlets into the river;

[0007] S2) Calculate the contribution coefficient of the sewage discharge into the river to the water quality of the control section based on the river water quality mathematical model;

[0008] S3) Calculate the impact contribution index of each sewage outlet into the river based on the discharge volume, water quality and contribution coefficient of each sewage outlet into the river to the water quality control section;

[0009] S4) Calculate the corresponding index of difficulty of remediation based on the amount of water discharged from the sewage outlet into the river, the water collection range of the sewage outlet, the coverage of the drainage network in the drainage area where the sewage outlet is located, the type of sewage outlet problem, and the type of sewage outlet;

[0010] S5) Calculate the difficulty index of the sewage outlet remediation into the river based on the remediation difficulty index;

[0011] S6) Calculate the priority of river discharge outlet remediation based on the river discharge outlet impact contribution index and river discharge outlet remediation difficulty index.

[0012] Preferably, in step S1), the expression of the river water quality mathematical model is:

[0013]

[0014] Where C i represents the water quality concentration of the downstream control section of the i-th river; C0 is the water quality concentration of the inflow water of the upstream control section of the river; C0 is the inflow flow of the upstream control section; K is the pollutant attenuation coefficient; x0 is the distance between the upstream control section and the downstream control section; u is the average flow velocity of the river; C j is the water quality concentration of the jth sewage outlet into the river; Q j is the discharge flow of the jth sewage outlet into the river; x j is the distance between the jth sewage outlet into the river and the downstream control section; m is the total number of sewage outlets into the river.

[0015] Preferably, in step S2), it is assumed that the river has a sewage outlet A and a water quality control section L. If the concentration of the water quality control section L increases by a unit for every unit of pollutant discharged from the sewage outlet A, then a is defined as the pollution contribution coefficient of the sewage outlet A to the control section L.

[0016] Preferably, in step S2), each time a certain sewage outlet into the river is set to discharge 1 unit load, and the other sewage outlets are not discharged. The concentration of each water quality control section in this case is calculated using the river water quality mathematical model, which is the contribution coefficient of the sewage outlet to each water quality control section, that is:

[0017]

[0018] Where a ij is the pollution contribution coefficient of the unit load of the jth sewage outlet to the i-th water quality control section; C0 is the water quality concentration of the upstream control section of the river, Q0 is the water flow of the upstream control section; K is the pollutant attenuation coefficient; x0 is the distance between the upstream control section and the downstream control section; u is the average flow velocity of the river; x j is the distance between the jth sewage outlet into the river and the downstream control section.

[0019] As a preferred method, in step S3), the actual discharge volume of the j-th river discharge outlet changes the water quality concentration of the i-th water quality control section C ij for:

[0020] C ij =L j ×a ij ;

[0021] Where, L j is the actual discharge load of the jth sewage outlet into the river; a ij It is the pollution contribution coefficient of the unit load of the j-th sewage outlet into the river to the i-th water quality control section.

[0022] As a preferred method, in step S3), the change value C of the water quality concentration of the i-th water quality control section for all sewage outlets into the river is ai Expressed as:

[0023]

[0024] Where n is the number of sewage outlets.

[0025] As a preference, in step S3), the impact contribution index IE of a single sewage outlet into the river ij It is expressed as the proportion of the concentration change value caused by the sewage outlet into the river to the concentration change value caused by all sewage outlets into the river, that is:

[0026]

[0027] Where C ij C is the change in water quality concentration at the i-th water quality control section caused by the actual discharge volume of the j-th sewage outlet into the river; imin is the minimum change value of water quality concentration in the i-th water quality control section; C imax is the maximum change value of water quality concentration in the i-th water quality control section.

[0028] Preferably, in step S5), the calculation formula for the difficulty index ID of the sewage outlet into the river is:

[0029]

[0030] Where, I i Represents the difficulty index of regulation of the i-th indicator.

[0031] Preferably, in step S6), the impact contribution index of the sewage outlet into the river and the difficulty index of the sewage outlet into the river remediation are divided into the following categories according to the dichotomy method: sewage outlet into the river with small remediation difficulty and large impact, small remediation difficulty and small impact, large remediation difficulty and large impact, and large remediation difficulty and small impact.

[0032] The beneficial effects of the present invention are:

[0033] 1. The present invention uses the analytic hierarchy process to construct a calculation method for the priority index of river outlet remediation. The target layer is the river outlet remediation priority index, the criterion layer includes the river outlet impact (IE) and the river outlet remediation difficulty (ID), and the indicator layer includes the river outlet impact index and the difficulty index determined by five variables: the daily discharge volume of the outlet, the water collection range of the outlet, the coverage of the drainage zone pipe network, the outlet problem type, and the outlet type. This allows for a more intuitive construction of a sewage remediation system.

[0034] 2. The present invention proposes a calculation model for the contribution index of the discharge of river sewage outlets to the water quality of the control section and the difficulty index of the river sewage outlet remediation based on the water volume and quality of the river sewage outlets and their contribution to the water quality of the control section, as well as the discharge volume of the river sewage outlets, water collection range, coverage of the drainage sub-area pipe network, problem type, and river sewage outlet type. A river sewage outlet remediation priority calculation model is established using the river sewage outlet impact contribution index and the remediation difficulty index. The river sewage outlet remediation priority calculation model can be used to evaluate the remediation priority of river sewage outlets and formulate a batch remediation list of river sewage outlets. The application of the river sewage outlet remediation priority assessment method can promote the remediation of river sewage outlets in a more scientific, orderly, and efficient manner.

[0035] 3. The present invention can regulate the corresponding sewage outlets into the river according to the regulation priority, thereby improving the efficiency and focus of sewage regulation and avoiding river pollution problems caused by inaccurate regulation;

[0036] 4. The present invention divides the sewage outlets into three types: those with low difficulty in remediation but high impact, those with low difficulty in remediation but low impact, those with high difficulty in remediation but high impact, and those with high difficulty in remediation but low impact. This can achieve more scientific, orderly and efficient remediation of sewage outlets into rivers, thereby improving the effect of remediation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the process of the present invention;

[0038] Figure 2 Schematic diagram of the framework of the method of the present invention. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0040] Example 1

[0041] like Figure 1 and 2 As shown, this embodiment provides a method for evaluating the priority of river sewage outlet remediation, including the following steps:

[0042] S1) Establish a river water quality mathematical model based on the river hydrological conditions and the water volume, water quality and spatial distribution of the sewage outlet into the river; the expression of the river water quality mathematical model is:

[0043]

[0044] Where C i represents the water quality concentration of the downstream control section of the i-th river; C0 is the water quality concentration of the inflow water of the upstream control section of the river; Q0 is the inflow flow of the upstream control section; K is the pollutant attenuation coefficient; x0 is the distance between the upstream control section and the downstream control section; u is the average flow velocity of the river; C j is the water quality concentration of the jth sewage outlet into the river; Q j is the discharge flow of the jth sewage outlet into the river; x j is the distance between the jth sewage outlet into the river and the downstream control section; m is the total number of sewage outlets into the river.

[0045] S2) Calculate the contribution coefficient of the sewage discharge into the river to the water quality of the control section based on the river water quality mathematical model;

[0046] In this embodiment, it is assumed that the river has a sewage outlet A and a water quality control section L. If the concentration of the water quality control section L increases by a unit for every unit of pollutant discharged from the sewage outlet A, then a is defined as the pollution contribution coefficient of the sewage outlet A to the control section L.

[0047] In this embodiment, a certain sewage outlet into the river is set to discharge 1 unit load each time, and the other sewage outlets are not discharged. The concentration of each water quality control section in this case is calculated using the river water quality mathematical model, which is the contribution coefficient of the sewage outlet to each water quality control section, that is:

[0048]

[0049] Where a ij is the pollution contribution coefficient of the unit load of the jth sewage outlet to the i-th water quality control section; C0 is the water quality concentration of the upstream control section of the river, Q0 is the water flow of the upstream control section; K is the pollutant attenuation coefficient; x0 is the distance between the upstream control section and the downstream control section; u is the average flow velocity of the river; x j is the distance between the jth sewage outlet into the river and the downstream control section.

[0050] S3) Calculate the impact contribution index of each sewage outlet into the river based on the discharge volume, water quality and contribution coefficient of each sewage outlet into the river to the water quality control section;

[0051] In this embodiment, the actual discharge volume of the jth sewage outlet into the river changes the water quality concentration of the i-th water quality control section C ij for:

[0052] C ij =L j ×a ij ;

[0053] Where, L j is the actual discharge load of the jth sewage outlet into the river; a ij It is the pollution contribution coefficient of the unit load of the j-th sewage outlet into the river to the i-th water quality control section.

[0054] In this embodiment, all the sewage outlets into the river have a change in the water quality concentration of the i-th water quality control section b ai Expressed as:

[0055]

[0056] Where n is the number of sewage outlets.

[0057] Impact contribution index IE of a single sewage outlet into the river ij It is expressed as the proportion of the concentration change value caused by the sewage outlet into the river to the concentration change value caused by all sewage outlets into the river, that is:

[0058]

[0059] Where, is the contribution index of the jth sewage outlet into the river to the i-th water quality control section when all sewage outlets discharge sewage according to the actual situation, C ij C is the change in water quality concentration at the i-th water quality control section caused by the actual discharge volume of the j-th sewage outlet into the river; imin is the minimum change value of water quality concentration in the i-th water quality control section; C imax is the maximum change value of water quality concentration in the i-th water quality control section.

[0060] S4) Calculate the corresponding index of difficulty of remediation according to the amount of water discharged from the sewage outlet into the river, the water collection range of the sewage outlet, the coverage of the drainage network in the drainage area where the sewage outlet is located, the type of sewage outlet problem, and the type of sewage outlet; as shown in Table 1:

[0061] Table 1 Comparison table of index of difficulty in regulation

[0062]

[0063]

[0064] S5) Calculate the difficulty index of the river discharge outlet regulation according to the indicator regulation difficulty index; the calculation formula of the river discharge outlet regulation difficulty index ID is:

[0065]

[0066] Where, I i Represents the difficulty index of regulation of the i-th indicator.

[0067] S6) Calculate the priority of river discharge outlet remediation based on the river discharge outlet impact contribution index and river discharge outlet remediation difficulty index.

[0068] In this embodiment, the impact contribution index of the sewage outlets into rivers and the difficulty index of the sewage outlets into rivers are divided into the following categories according to the dichotomy method: sewage outlets into rivers with small difficulty of remediation and large impact, small difficulty of remediation and small impact, large difficulty of remediation and large impact, and large difficulty of remediation and small impact.

[0069] Example 2

[0070] This embodiment takes a tributary of the upper reaches of a river basin where a national examination section is located in the south as an example. There are 16 sewage outlets in this river section. A river water quality mathematical model is established based on the river hydrological conditions and the water volume, water quality and spatial distribution of the sewage outlets. The contribution coefficients of the drainage of the 16 sewage outlets to the water quality pollution of the national examination section are calculated respectively, and the impact contribution index of the sewage outlets is calculated based on the water volume and water quality of the 16 sewage outlets and the contribution coefficients to the water quality of the national examination section, as shown in Table 2; the corresponding remediation difficulty index is calculated based on the drainage volume of the 16 sewage outlets, the water collection range of the sewage outlets, the coverage of the drainage network in the drainage area where the sewage outlets are located, the problem type of the sewage outlet, and the type of sewage outlet; the remediation difficulty index of the sewage outlets is calculated based on the difficulty index of the above indicators, as shown in Table 3; the impact and difficulty are divided into three categories of sewage outlets: small remediation difficulty and small impact, large remediation difficulty and large impact, and large remediation difficulty and small impact, and the priority of the remediation of the sewage outlets is proposed, as shown in Table 4.

[0071] Table 2 Impact index of sewage outlets into a river in the south

[0072] Serial number Name of sewage outlet longitude latitude IE 1 Sewage outlet 1 116.5283683 23.62039732 1 2 Sewage outlet 2 116.546738 23.633313 0.08 3 Sewage outlet 3 116.5550445 23.64296605 0.3 4 Sewage outlet 4 116.5606339 23.66783922 0 5 Sewage outlet 5 116.534963 23.62484353 0.13 6 Sewage outlet 6 116.5277221 23.69366321 0 7 Sewage outlet 7 116.5278788 23.69355522 0.02 8 Sewage outlet 8 116.5433174 23.62939647 0.09 9 Sewage outlet 9 116.5453261 23.63205034 0.08 10 Sewage outlet 10 116.5516787 23.63710621 0.07 11 Sewage outlet 11 116.551821 23.63830724 0.07 12 Sewage outlet 12 116.5597659 23.66592527 0.04 13 Sewage outlet 13 116.5557385 23.64624851 0.05 14 Sewage outlet 14 116.5587345 23.66291601 0.04 15 Sewage outlet 15 116.544828 23.631351 0.08 16 Sewage outlet 16 116.4641723 23.73320506 0.06

[0073] Table 3 Difficulty index of the remediation of a river outlet in the south

[0074]

[0075] Table 4 Priority list for the remediation of sewage outlets into a river in the south

[0076] Serial number Name of sewage outlet longitude latitude Priority Classification Rectification batch 1 Sewage outlet 1 116.52837 23.620397 High difficulty, low impact 3 2 Sewage outlet 2 116.54674 23.633313 Difficulty and impact 2 3 Sewage outlet 3 116.55504 23.642966 High difficulty, low impact 3 4 Sewage outlet 4 116.56063 23.667839 Low difficulty and low impact 1 5 Sewage outlet 5 116.53496 23.624844 High difficulty, low impact 3 6 Sewage outlet 6 116.52772 23.693663 Low difficulty and low impact 1 7 Sewage outlet 7 116.52788 23.693555 Low difficulty and low impact 1 8 Sewage outlet 8 116.54332 23.629396 High difficulty, low impact 3 9 Sewage outlet 9 116.54533 23.63205 High difficulty, low impact 3 10 Sewage outlet 10 116.55168 23.637106 Low difficulty and low impact 1 11 Sewage outlet 11 116.55182 23.638307 High difficulty, low impact 3 12 Sewage outlet 12 116.55977 23.665925 Low difficulty and low impact 1 13 Sewage outlet 13 116.55574 23.646249 Low difficulty and low impact 1 14 Sewage outlet 14 116.55873 23.662916 Low difficulty and low impact 1 15 Sewage outlet 15 116.54483 23.631351 High difficulty, low impact 3 16 Sewage outlet 16 116.46417 23.733205 Low difficulty and low impact 1

[0077] The above embodiments and descriptions are only for explaining the principles and best embodiments of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, which shall fall within the scope of the invention to be protected.

Claims

1. A method for evaluating the priority of river sewage outlet remediation, characterized in that: The following steps are involved: S1) Establish a river water quality mathematical model based on the river hydrological conditions and the water volume, water quality and spatial distribution of the sewage outlets into the river; S2) Calculate the contribution coefficient of the sewage discharge into the river to the water quality of the control section based on the river water quality mathematical model; S3) Calculate the impact contribution index of each sewage outlet into the river based on the discharge volume, water quality and contribution coefficient of each sewage outlet into the river to the water quality control section; S4) Calculate the corresponding index of difficulty of remediation based on the amount of water discharged from the sewage outlet into the river, the water collection range of the sewage outlet, the coverage of the drainage network in the drainage area where the sewage outlet is located, the type of sewage outlet problem, and the type of sewage outlet; S5) Calculate the difficulty index of the sewage outlet remediation into the river based on the remediation difficulty index; S6) Calculate the priority of river discharge outlet remediation based on the river discharge outlet impact contribution index and river discharge outlet remediation difficulty index.

2. The method for evaluating the priority of river sewage outlet remediation according to claim 1, characterized in that: In step S1), the expression of the river water quality mathematical model is: Where C i represents the water quality concentration of the downstream control section of the i-th river; C0 is the water quality concentration of the inflow water of the upstream control section of the river; Q0 is the inflow flow of the upstream control section; K is the pollutant attenuation coefficient; x0 is the distance between the upstream control section and the downstream control section; u is the average flow velocity of the river; C j is the water quality concentration of the jth sewage outlet into the river; Q j is the discharge flow of the jth sewage outlet into the river; x j is the distance between the jth sewage outlet into the river and the downstream control section; m is the total number of sewage outlets into the river.

3. The method for evaluating the priority of river sewage outlet remediation according to claim 2, characterized in that: In step S2), it is assumed that the river has a sewage outlet A and a water quality control section L. If the pollutant concentration in the water quality control section L increases by a units for every unit of pollutant discharged from the sewage outlet A, then a is defined as the pollution contribution coefficient of the sewage outlet A to the control section L.

4. A method for evaluating the priority of river sewage outlet remediation according to claim 3, characterized in that: In step S2), each time a certain sewage outlet into the river is set to discharge 1 unit load, and the other sewage outlets are not discharged. The concentration of each water quality control section in this case is calculated using the river water quality mathematical model, which is the contribution coefficient of the sewage outlet to each water quality control section, that is: Where a ij is the pollution contribution coefficient of the unit load of the jth sewage outlet to the i-th water quality control section; C0 is the water quality concentration of the upstream control section of the river, Q0 is the water flow of the upstream control section; K is the pollutant attenuation coefficient; x0 is the distance between the upstream control section and the downstream control section; u is the average flow velocity of the river; x j is the distance between the jth sewage outlet into the river and the downstream control section.

5. The method for evaluating the priority of river sewage outlet remediation according to claim 1, characterized in that: In step S3), the actual discharge volume of the j-th river discharge outlet changes the water quality concentration of the i-th water quality control section C ij for: C ij =L j ×a ij ; Where, L j is the actual discharge load of the jth sewage outlet into the river; a ij It is the pollution contribution coefficient of the unit load of the j-th sewage outlet into the river to the i-th water quality control section.

6. A method for evaluating the priority of river sewage outlet remediation according to claim 5, characterized in that: In step S3), the change value C of the water quality concentration of the i-th water quality control section for all sewage outlets into the river is ai Expressed as: Where n is the number of sewage outlets.

7. A method for evaluating the priority of river sewage outlet remediation according to claim 6, characterized in that: In step S3), the impact contribution index IE of a single sewage outlet into the river ij It is expressed as the proportion of the concentration change value caused by the sewage outlet into the river to the concentration change value caused by all sewage outlets into the river, that is: Where C ij C is the change in water quality concentration at the i-th water quality control section due to the actual discharge volume of the j-th sewage outlet into the river; imin is the minimum change value of water quality concentration in the i-th water quality control section; C imax is the maximum change value of water quality concentration in the i-th water quality control section.

8. The method for evaluating the priority of river sewage outlet remediation according to claim 1, characterized in that: In step S5), the calculation formula of the difficulty index ID of the sewage outlet into the river is: Where, I i Represents the difficulty index of regulation of the i-th indicator.

9. The method for evaluating the priority of river sewage outlet remediation according to claim 1, characterized in that: In step S6), the impact contribution index of the river discharge outlet and the difficulty index of the river discharge outlet remediation are divided into the following categories according to the dichotomy method: river discharge outlets with small remediation difficulty and large impact, small remediation difficulty and small impact, large remediation difficulty and large impact, and large remediation difficulty and small impact.

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