A method for assessing carbon emissions from rural sewage pipe networks

Abstract

The present invention provides a carbon emission assessment method for rural sewage pipe networks, which mainly includes: determining the rural sewage treatment method; obtaining relevant data; constructing a carbon emission assessment model for rural areas according to different treatment methods; inputting the data into the rural carbon emission calculation formula to calculate the carbon emission intensity of rural areas. In view of the fact that the current existing methods fail to fully consider the characteristics of rural sewage and the complex factors in the treatment process, the present invention starts from the different rural sewage treatment methods, accurately calculates the carbon emissions of sewage from collection to treatment, and thus obtains the total emissions of the rural pipe network system. Accurate control of carbon emissions in rural areas is achieved, and effective support is provided for achieving carbon emission reduction goals.

Description

Technical Field

[0001] The invention relates to a rural sewage carbon emission assessment method, belonging to the technical field of carbon emission measurement. Background Art

[0002] Against the backdrop of global climate change, accurate measurement and effective control of carbon emissions have become key tasks for environmental protection and sustainable development. With the development of the rural economy and the improvement of residents' living standards, the amount of rural sewage is also increasing. However, there is currently a lack of accurate and effective measurement methods for carbon emissions in the rural sewage treatment process.

[0003] Traditional carbon emission measurement is mainly focused on the industrial and urban sectors, with relatively little attention paid to the specific area of ​​rural sewage. Rural sewage comes from a variety of sources, including domestic sewage, small-scale aquaculture wastewater, and agricultural non-point source pollution, and its composition and treatment methods are significantly different from those of urban sewage. Some existing measurement methods have failed to keep up with demand and have failed to fully consider the characteristics of rural sewage and the complex factors in the treatment process. For example, in rural areas, due to geographical and economic factors, sewage treatment facilities are usually small in scale and simpler in process, but their operation mode and energy consumption are unique. At the same time, the impact of different seasons and climatic conditions on sewage generation and treatment effects cannot be ignored.

[0004] Therefore, there is an urgent need for a carbon emission measurement method and technology specifically for rural sewage, so as to achieve accurate assessment and effective control of carbon emissions in rural areas and provide strong technical support for rural ecological environmental protection and sustainable development.

[0005] The Chinese patent application "Rural Rainwater and Sewage Low-carbon Treatment and High-standard Farmland Resource Integrated Circulation System" with application number CN202310433425.0 includes a rural decentralized sewage treatment device, a rainwater and sewage collection pipeline, a farmland water storage pipe tank system, a farmland water and fertilizer integrated automatic irrigation system and a black water digestion tank; the rural decentralized sewage treatment device is composed of multiple sewage treatment units, and the sewage treatment unit includes a purification tank, a gray water collection pipeline, a solar photovoltaic system, a rainwater collection port, a rainwater collection pipeline, a septic tank, a black water collection pipeline and a fecal suction vehicle; the farmland water and fertilizer integrated automatic irrigation system includes a water pump, a fertilizer suction pipeline, a water and fertilizer integrated machine and a fertilizer storage tank. Irrigation and fertilization are combined to implement synchronous management, and effective resources are reasonably utilized. Rainwater and treated gray water are uniformly collected through rainwater and sewage collection pipelines, and the water supply is relatively stable, with higher application value. However, it does not involve the differences in rural sewage treatment methods in different regions and the calculation of carbon emissions.

[0006] The Chinese patent application "A method and system for analyzing carbon emissions from farmland" with application number CN202311135291.0 obtains the regional basic information of the target farmland, and constructs a three-dimensional farmland model based on the regional basic information; obtains the monitoring image and remote sensing image of the target farmland, and identifies and analyzes the crops in the target farmland based on the microscopic and macroscopic dimensions and combines the farmland image big data for comparison to obtain crop planting information; based on the crop planting information and fertilization information, combines the farmland model to perform regional carbon emission prediction and analysis to obtain carbon emission prediction data; based on the carbon emission prediction data, the target farmland is subjected to regional carbon emission distribution analysis, and a carbon emission monitoring scheme is generated. Through the present invention, it is possible to make full use of big data technology and agricultural field data, accurately evaluate the carbon emissions of farmland, realize accurate analysis and prediction of carbon emissions, and provide a reliable basis for environmental impact assessment of agricultural production. However, this patent only involves the calculation of carbon emissions from farmland, and does not involve the calculation of carbon emissions from rural sewage pipe networks.

[0007] The Chinese patent application "A Sewage Treatment Device for Collaborative Pollution Reduction and Carbon Reduction" with application number CN202311459992.X includes a sewage treatment mechanism, which includes an aeration tank and a trustee base. The aeration tank is set on the ground, and the trustee base is fixedly connected to the ground. The number of trustee bases is two; through the blockage monitoring mechanism, the sewage treatment device for collaborative pollution reduction and carbon reduction can monitor the permeability of the tubular aerator in real time. When the tubular aerator is seriously blocked, the blockage monitoring mechanism will trigger the positioning mechanism, and the installation pan can be released by the triggered positioning mechanism. The upward lifting force can be applied to the installation pan through the water outlet mechanism, so that the installation pan can move out of the sewage with the blocked tubular aerator, so that the staff can timely and accurately find which tubular aerator is blocked, and there is no need to check the tubular aerator, which saves time and effort, and improves the practicality of the sewage treatment device for collaborative pollution reduction and carbon reduction. However, the patent only focuses on pollution reduction and carbon reduction measures, and does not involve the calculation of carbon emissions in rural areas. Summary of the invention

[0008] Purpose of the invention: In view of the fact that the existing methods fail to fully consider the characteristics of rural sewage and the complex factors in the treatment process, the present invention provides a rural sewage carbon emission assessment method, which mainly includes: determining the rural sewage treatment method and obtaining relevant data; constructing a rural sewage carbon emission assessment model; and calculating the rural sewage carbon emission according to different sewage treatment methods. In this way, accurate carbon emission assessment can be carried out for the diverse drainage methods in rural areas.

[0009] Technical solution: In order to achieve the above-mentioned invention object, the present invention adopts the following technical solution:

[0010] A method for assessing carbon emissions from a rural sewage pipe network comprises the following steps:

[0011] Step 1: Determine the rural sewage treatment method, centralized or decentralized;

[0012] The centralized treatment mentioned above refers to the collection of domestic sewage and agricultural wastewater from rural residents, which is transported to sewage treatment plants through sewage pipes or ditches; its carbon emissions are the carbon emissions generated in the sewage pipe network and the carbon emissions generated during the centralized treatment process of the sewage plant. The decentralized treatment mentioned above refers to the treatment of sewage generated by a single or multiple farmers in rural areas with the help of small, independent treatment equipment and systems; selected from small artificial wetlands or septic tanks.

[0013] Step 2: Obtain relevant data, including sewage pipe network topology, pipe length, pipe diameter, starting and ending point burial depth, starting and ending point number, node number, node burial depth, ground elevation, flow direction, slope, and sewage treatment method;

[0014] Step 3: Construct a carbon emission assessment model for rural areas based on different treatment methods;

[0015] The steps for building a carbon emission calculation model for sewage pipe networks in rural areas are as follows:

[0016] 1. ① Calculate the solid, liquid and gas three-phase areas at the cross section of the sewage pipe:

[0017] For gas in the pipeline network,

[0018]

[0019] Among them, A 气i is the gas area at the cross section of the sewage pipe i, m 2 ;

[0020] D i is the diameter of sewage pipe i, m;

[0021] H i is the design water depth of sewage pipe i, m;

[0022] For liquid in the pipe network,

[0023]

[0024] Among them, h i is the thickness of the sediment in pipe i, m;

[0025] For solids in the pipe network,

[0026]

[0027] ② Calculate the volume of solid, liquid and gas phases in the sewage pipe network:

[0028] For gas in the pipeline network,

[0029] V 气 =V 管道 +V 检查井

[0030]

[0031] Among them, V 气 is the gas volume in the pipe network system, m 3 ;

[0032] V 管道 is the total volume of gas in the sewage pipes in the pipe network system, m 3 ; V 检查井 is the total gas volume of the inspection wells in the pipe network system, m 3 ; R j is the radius of inspection well j, m;

[0033] H wj is the depth of inspection well j, m;

[0034] For liquid in the pipe network,

[0035]

[0036] Among them, V 液 is the volume of liquid in the pipe network system, m 3 ;

[0037] For solids in the pipe network,

[0038]

[0039] Among them, V 固 is the solid volume in the pipe network system, m 3 ;

[0040] ③Calculate the carbon emissions of the sewage pipe network system:

[0041]

[0042] in, is the CO2 emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0043]

[0044] in, is the CH4 emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0045]

[0046] in, is the N2O emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0047] but

[0048] 2. Centralized treatment: The calculation steps for carbon emissions from sewage treatment plants are as follows:

[0049] For CO2 emissions:

[0050]

[0051] in, is the CO2 emission intensity of fossil sources for wastewater treatment, kg CO2-eq / m 3 ; MFCF is the proportion of CO2 emissions from fossil sources, %;

[0052] B in is the average influent BOD5 concentration of the sewage treatment plant, mg BOD5 / L;

[0053] B ex is the additional carbon source added artificially during operation, mg BOD5 / L;

[0054] K d is the attenuation coefficient, d -1 ;

[0055] SRT is the mean residence time of biosolids, d;

[0056] HRT is the hydraulic retention time of the bioreactor, d;

[0057] MLVSS is the average concentration of volatile suspended solids in the biological pool mixed liquor, mg MLVSS / L;

[0058] TKN in is the average total Kjeldahl nitrogen concentration in the sewage treatment plant influent, mg N / L;

[0059] TKN ef is the average total Kjeldahl nitrogen concentration in the effluent of the sewage treatment plant, mg N / L;

[0060] FCF is the proportion of fossil organic matter in the influent of the sewage treatment plant, which can be 5% to 20%, and is generally 10%; T b is the water temperature, ℃.

[0061] For CH4 emissions:

[0062]

[0063] in, is the CH4 emission intensity from fossil sources in wastewater treatment, kg CO2-eq / m 3 ;

[0064] is the CH4 emission factor of the sewage treatment unit, usually ranging from 0.000336 to 0.0117;

[0065] Amount of CH4 gas removed for recovery or treatment, kg CH4 / m 3 ;

[0066] For N2O emissions:

[0067]

[0068] in, is the N2O emission intensity from fossil sources in wastewater treatment, kg CO2-eq / m 3 ;

[0069] TN in is the average influent total nitrogen concentration of the sewage treatment plant, mg N / L;

[0070] N2O emission factor in the biological wastewater treatment process, usually ranging from 0 to 0.0093;

[0071] Amount of N2O gas removed for recovery or treatment, kg CH4 / m 3 ;

[0072] but Among them, CES ww is the carbon emission intensity of the sewage treatment plant, kg CO2-eq / m 3 ;

[0073] 3. The calculation steps for carbon emissions from decentralized sewage treatment plants are as follows:

[0074] (1) Small artificial wetlands

[0075] For CO2 emissions:

[0076]

[0077] in, is the CO2 emission intensity of fossil sources in artificial wetlands, kg CO2-eq / m 3 ;

[0078] B in ′ is the average influent BOD5 concentration of the constructed wetland, mg BOD5 / L;

[0079] For CH4 emissions:

[0080]

[0081] in, is the CH4 emission intensity from fossil sources in artificial wetlands, kg CO2-eq / m 3 ;

[0082] is the CH4 emission factor in artificial wetlands, usually ranging from 0.042 to 0.078;

[0083] For N2O emissions:

[0084]

[0085] in, is the N2O emission intensity from fossil sources in artificial wetlands, kg CO2-eq / m 3 ;

[0086] TN eff ′ is the average total nitrogen concentration of the constructed wetland influent, mg N / L;

[0087] is the N2O emission factor of artificial wetlands, usually ranging from 0.0079 to 0.00023;

[0088] but

[0089] Among them, CES wL is the carbon emission intensity of artificial wetlands, kg CO2-eq / m 3 ;

[0090] (2) Septic tank

[0091] For CH4 emissions:

[0092]

[0093] in, is the CH4 carbon emission intensity of septic tank, kg CO2-eq / m 3 ;

[0094] EF PE is the CH4 emission equivalent of septic tank, kg CO2-eq / (person·a), 85kg CO2-eq / (person·a);

[0095] Q PE is the per capita sewage discharge, m 3 / (person·d), it is recommended to select the value according to the size of the town, and the "Water Supply and Drainage Design Manual" can be referred to;

[0096] For CO2 emissions:

[0097] The amount of CO2 produced is 5 to 20 times the amount of CH4 produced.

[0098]

[0099] in, is the CO2 carbon emission intensity of the septic tank, kg CO2-eq / m 3 ;

[0100] For N2O emissions:

[0101] Normally, the amount of N2O produced may be only 0.01 to 0.1 times the amount of CH4 produced.

[0102]

[0103] in, is the carbon emission intensity of N2O from septic tanks, kg CO2-eq / m 3 ;

[0104] but

[0105] Among them, CES hfc is the carbon emission intensity of septic tank, kg CO2-eq / m 3 ;

[0106] Step 4: Input the data into the rural carbon emission calculation formula to calculate the rural carbon emission intensity;

[0107] Centralized carbon emissions processing is CES Gw +CES ww ;

[0108] Distributed processing has different algorithms depending on the processing method:

[0109] When it is treated by artificial wetlands, its carbon emissions are CES Gw +CES wL ;

[0110] When treated in a septic tank, the carbon emissions are CES Gw +CES hfc ;

[0111] Compared with the prior art, the advantages of the present invention are:

[0112] (1) Accurate assessment: It can accurately assess carbon emissions for the diverse drainage methods in rural areas. It takes into account the differences in sewage collection, transportation and treatment between different sewage treatment methods, thereby providing more accurate and detailed carbon emission data, avoiding the general and inaccurate assessments in the past.

[0113] (2) Comprehensive consideration: The entire cycle from sewage discharge to treatment is systematically considered, including sewage collection, treatment process and other links, thus providing a comprehensive perspective for optimizing the entire sewage treatment system.

[0114] (3) Wide scope of application: It can adapt to the changing development conditions and drainage mode adjustments in rural areas. With the development of rural economy and improvement of infrastructure, drainage mode may change. The system and method can update and adjust the evaluation parameters in time to ensure the timeliness and effectiveness of the evaluation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] Figure 1 A schematic diagram of a rural wastewater carbon emission assessment method;

[0116] Figure 2 This is a cross-sectional view of a sewage pipe;

[0117] Figure 3 This is a cross-section diagram of the sewage pipe network.

[0118] Among them: 1-sewage pipe; 2-inspection well; 3-ground; 4-sediment in the pipe network; 5-sewage. DETAILED DESCRIPTION

[0119] Example 1

[0120] Step 1: Determine the rural sewage treatment method, which is centralized treatment.

[0121] Step 2: Obtain relevant data, including sewage pipe network topology, pipe length, pipe diameter, starting and ending point burial depth, starting and ending point number, node number, node burial depth, ground elevation, flow direction, slope, and sewage treatment method;

[0122] Step 3: Construct a carbon emission assessment model for rural areas;

[0123] The steps for building a carbon emission calculation model for sewage pipe networks in rural areas are as follows: ① Calculate the solid, liquid and gas three-phase areas at the cross-section of the sewage pipe: For the gas in the pipe network,

[0124]

[0125] Among them, A 气i is the gas area at the cross section of the sewage pipe i, m 2 ;D i is the diameter of sewage pipe i, m;

[0126] H i is the design water depth of sewage pipe i, m;

[0127] For liquid in the pipe network,

[0128]

[0129] Among them, h i is the thickness of the sediment in pipe i, m;

[0130] For solids in the pipe network,

[0131]

[0132] ② Calculate the volume of solid, liquid and gas phases in the sewage pipe network:

[0133] For gas in the pipeline network,

[0134] V 气 =V 管道 +V 检查井

[0135]

[0136] Among them, V 气 is the gas volume in the pipe network system, m 3 ;

[0137] V 管道 is the total volume of gas in the sewage pipes in the pipe network system, m 3 ;

[0138] V 检查井 is the total gas volume of the inspection wells in the pipe network system, m 3 ;

[0139] R j is the radius of inspection well j, m;

[0140] H wj is the depth of inspection well j, m;

[0141] For liquid in the pipe network,

[0142]

[0143] Among them, V 液 is the volume of liquid in the pipe network system, m 3 ;

[0144] For solids in the pipe network,

[0145]

[0146] Among them, V固 is the solid volume in the pipe network system, m 3 ;

[0147] ③Calculate the carbon emissions of the sewage pipe network system:

[0148]

[0149] in, is the CO2 emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0150]

[0151] in, is the CH4 emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0152]

[0153] in, is the N2O emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0154] but The steps for calculating carbon emissions from a sewage treatment plant are as follows:

[0155] For CO2 emissions:

[0156]

[0157] in, is the CO2 emission intensity of fossil sources for wastewater treatment, kg CO2-eq / m 3 ;

[0158] MFCF is the proportion of CO2 emissions from fossil sources, %;

[0159] B in is the average influent BOD5 concentration of the sewage treatment plant, mg BOD5 / L;

[0160] B ex is the additional carbon source added artificially during operation, mg BOD5 / L;

[0161] K d is the attenuation coefficient, d -1 ;

[0162] SRT is the mean residence time of biosolids, d;

[0163] HRT is the hydraulic retention time of the bioreactor, d;

[0164] MLVSS is the average concentration of volatile suspended solids in the biological pool mixed liquor, mg MLVSS / L;

[0165] TKN in is the average total Kjeldahl nitrogen concentration in the sewage treatment plant influent, mg N / L;

[0166] TKN ef is the average total Kjeldahl nitrogen concentration in the effluent of the sewage treatment plant, mg N / L;

[0167] FCF is the proportion of fossil organic matter in the influent of the sewage treatment plant, which can be 5% to 20%, and is generally 10%; T b is the water temperature, ℃.

[0168] For CH4 emissions:

[0169]

[0170] in, is the CH4 emission intensity from fossil sources in wastewater treatment, kg CO2-eq / m 3 ;

[0171] is the CH4 emission factor of the sewage treatment unit, usually ranging from 0.000336 to 0.0117;

[0172] Amount of CH4 gas removed for recovery or treatment, kg CH4 / m 3 ;

[0173] For N2O emissions:

[0174]

[0175] in, is the N2O emission intensity from fossil sources in wastewater treatment, kg CO2-eq / m 3 ;

[0176] TN in is the average influent total nitrogen concentration of the sewage treatment plant, mg N / L;

[0177] N2O emission factor in the biological wastewater treatment process, usually ranging from 0 to 0.0093;

[0178] Amount of N2O gas removed for recovery or treatment, kg CH4 / m 3 ;

[0179] but

[0180] Among them, CESww is the carbon emission intensity of the sewage treatment plant, kg CO2-eq / m 3 ;

[0181] Step 4: Input the data into the rural carbon emission calculation formula to calculate the rural carbon emission intensity;

[0182] Its carbon emissions are CES Gw +CES ww .

[0183] Example 2

[0184] Step 1: Determine the rural sewage treatment method, which is decentralized septic tank treatment.

[0185] Step 2: Obtain relevant data, including sewage pipe network topology, pipe length, pipe diameter, starting and ending point burial depth, starting and ending point number, node number, node burial depth, ground elevation, flow direction, slope, and sewage treatment method;

[0186] Step 3: Construct a carbon emission assessment model for rural areas;

[0187] The steps for building a carbon emission calculation model for sewage pipe networks in rural areas are as follows:

[0188] ① Calculate the solid, liquid and gas three-phase areas at the cross section of the sewage pipe:

[0189] For gas in the pipeline network,

[0190]

[0191] Among them, A 气i is the gas area at the cross section of the sewage pipe i, m 2 ;D i is the diameter of sewage pipe i, m;

[0192] H i is the design water depth of sewage pipe i, m;

[0193] For liquid in the pipe network,

[0194]

[0195] Among them, h i is the thickness of the sediment in pipe i, m;

[0196] For solids in the pipe network,

[0197]

[0198] ② Calculate the volume of solid, liquid and gas phases in the sewage pipe network:

[0199] For gas in the pipeline network,

[0200] V 气 =V 管道 +V 检查井

[0201]

[0202] Among them, V 气 is the gas volume in the pipe network system, m 3 ; V 管道 is the total volume of gas in the sewage pipes in the pipe network system, m 3 ;

[0203] V 检查井 is the total gas volume of the inspection wells in the pipe network system, m 3 ;

[0204] R j is the radius of inspection well j, m;

[0205] H wj is the depth of inspection well j, m;

[0206] For liquid in the pipe network,

[0207]

[0208] Among them, V 液 is the volume of liquid in the pipe network system, m 3 ;

[0209] For solids in the pipe network,

[0210]

[0211] Among them, V 固 is the solid volume in the pipe network system, m 3 ;

[0212] ③Calculate the carbon emissions of the sewage pipe network system:

[0213]

[0214] in, is the CO2 emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0215]

[0216] in, is the CH4 emission intensity of the sewage network, kg CO2-eq / m 3 ;

[0217]

[0218] in, is the N2O emission intensity of the sewage network, kg CO2-eq / m 3 ;but The steps to calculate carbon emissions from septic tanks are as follows:

[0219] For CH4 emissions:

[0220]

[0221] in, is the CH4 carbon emission intensity of septic tank, kg CO2-eq / m 3 ;

[0222] EF PE is the CH4 emission equivalent of septic tank, kg CO2-eq / (person·a), 85kg CO2-eq / (person·a);

[0223] Q PE is the per capita sewage discharge, m 3 / (person·d), it is recommended to select the value according to the size of the town, and the "Water Supply and Drainage Design Manual" can be referred to;

[0224] For CO2 emissions:

[0225] The amount of CO2 produced is 5 to 20 times the amount of CH4 produced.

[0226]

[0227] in, is the CO2 carbon emission intensity of the septic tank, kg CO2-eq / m 3 ;

[0228] For N2O emissions:

[0229] Normally, the amount of N2O produced is only 0.01 to 0.1 times the amount of CH4 produced.

[0230]

[0231] in, is the carbon emission intensity of N2O from septic tanks, kg CO2-eq / m 3 ;

[0232] but

[0233] Among them, CES hfc is the carbon emission intensity of septic tank, kg CO2-eq / m 3 ;

[0234] Step 4: Input the data into the rural carbon emission calculation formula to calculate the carbon emission intensity of the rural area; then its carbon emission is CES Gw +CES hfc .

[0235] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for assessing carbon emissions from rural sewage pipe networks, characterized in that: The following steps are involved: Step 1: Determine the rural sewage treatment method, centralized or decentralized; Step 2: Obtain relevant data, including sewage pipe network topology, pipe length, pipe diameter, starting and ending point burial depth, starting and ending point number, node number, node burial depth, ground elevation, flow direction, slope, and sewage treatment method; Step 3: Construct a carbon emission assessment model for sewage pipe networks in rural areas based on different sewage treatment methods; The steps for constructing the carbon emission assessment model for sewage pipe networks in rural areas are as follows: ① Calculate the solid, liquid and gas three-phase areas at the cross section of the sewage pipe: For gas in the pipeline network, Among them, A 气i is the gas area at the cross section of the sewage pipe i, m 2 ; D i is the diameter of sewage pipe i, m; H i is the design water depth of sewage pipe i, m; For liquid in the pipe network, Among them, h i is the thickness of the sediment in pipe i, m; For solids in the pipe network, ② Calculate the volume of solid, liquid and gas phases in the sewage pipe network: For gas in the pipeline network, V 气 =V 管道 +V 检查井 Among them, V 气 is the gas volume in the pipe network system, m 3 ; V 管道 is the total volume of gas in the sewage pipes in the pipe network system, m 3 ; V 检查井 is the total volume of gas in the inspection wells in the pipe network system, m 3 ; R j is the radius of inspection well j, m; H wj is the depth of inspection well j, m; For liquid in the pipe network, Among them, V 液 is the volume of liquid in the pipe network system, m 3 ; For solids in the pipe network, Among them, V 固 is the solid volume in the pipe network system, m 3 ; ③Calculate the carbon emissions of the sewage pipe network system CES Gw : in, is the CO2 emission intensity of the sewage network, kg CO2-eq / m 3 ; is the CH4 emission intensity of the sewage network, kg CO2-eq / m 3 ; is the N2O emission intensity of the sewage network, kg CO2-eq / m 3 ; Step 4: Input the relevant data from step 2 into the rural carbon emission assessment model to calculate the carbon emission intensity of rural areas.

2. A rural sewage pipe network carbon emission assessment method according to claim 1, characterized in that: In step one, the centralized treatment is to collect rural domestic sewage and agricultural wastewater, and transport them to sewage treatment stations through sewage pipes or ditches; its carbon emissions are the carbon emissions generated in the sewage pipe network and the carbon emissions generated during the centralized treatment of the sewage plant.

3. A rural sewage pipe network carbon emission assessment method according to claim 1, characterized in that: In step one, the decentralized treatment refers to treating sewage generated by a single or multiple farmers in rural areas with the help of small, independent treatment equipment and systems; selected from small artificial wetlands or septic tanks.

4. A rural sewage pipe network carbon emission assessment method according to claim 1, characterized in that: In centralized treatment, the steps for calculating carbon emissions from sewage treatment plants are as follows: (1) For CO2 emissions: in, is the CO2 emission intensity of fossil sources for wastewater treatment, kg CO2-eq / m 3 ; MFCF is the proportion of CO2 emissions from fossil sources, %; B in is the average influent BOD5 concentration of the sewage treatment plant, mg BOD5 / L; B ex is the additional carbon source added artificially during operation, mg BOD5 / L; K d is the attenuation coefficient, d -1 ; SRT is the mean residence time of biosolids, d; HRT is the hydraulic retention time of the bioreactor, d; MLVSS is the average concentration of volatile suspended solids in the mixed liquor of the biological pool, mg MLVSS / L; TKN in is the average total Kjeldahl nitrogen concentration in the sewage treatment plant influent, mg N / L; TKN ef is the average total Kjeldahl nitrogen concentration in the effluent of the sewage treatment plant, mg N / L; FCF is the proportion of fossil organic matter in the influent of the sewage treatment plant, %, ranging from 5% to 20%; T b is water temperature, °C; (2) For CH4 emissions: in, is the CH4 emission intensity from fossil sources in wastewater treatment, kg CO2-eq / m 3 ; is the CH4 emission factor of the sewage treatment unit, ranging from 0.000336 to 0.0117; Amount of CH4 gas removed for recovery or treatment, kg CH4 / m 3 ; (3) For N2O emissions: in, is the N2O emission intensity from fossil sources in wastewater treatment, kg CO2-eq / m 3 TN in is the average influent total nitrogen concentration of the sewage treatment plant, mg N / L; is the N2O emission factor in the biological wastewater treatment process; Amount of N2O gas removed for recovery or treatment, kg CH4 / m 3 ; Then the carbon emission intensity of the sewage treatment plant CES ww Obtained according to the following formula, unit: kg CO2-eq / m 3 :

5. A rural sewage pipe network carbon emission assessment method according to claim 1, characterized in that: (1) The steps for calculating carbon emissions from a sewage station in a small artificial wetland are as follows: (1.1) For CO2 emissions: in, is the CO2 emission intensity of fossil sources in artificial wetlands, kg CO2-eq / m 3 ; B in ′ is the average influent BOD5 concentration of the constructed wetland, mg BOD5 / L; (1.2) For CH4 emissions: in, is the CH4 emission intensity from fossil sources in artificial wetlands, kg CO2-eq / m 3 ; is the CH4 emission factor in artificial wetlands, ranging from 0.042 to 0.078; (1.3) For N2O emissions: in, is the N2O emission intensity from fossil sources in artificial wetlands, kg CO2-eq / m 3 ; TN eff ′ is the average total nitrogen concentration of the constructed wetland influent, mg N / L; is the N2O emission factor of artificial wetlands, ranging from 0.00023 to 0.0079; but Among them, CES wL is the carbon emission intensity of artificial wetlands, kg CO2-eq / m 3 ; (2) The steps for calculating carbon emissions from septic tank sewage treatment plants are as follows: (2.1) For CH4 emissions: in, is the CH4 carbon emission intensity of septic tank, kg CO2-eq / m 3 ; EF PE is the CH4 emission equivalent of septic tank, kg CO2-eq / (person·a), 85kg CO2-eq / (person·a); Q PE is the per capita sewage discharge, m 3 / (person·d); (2.2) For CO2 emissions: The amount of CO2 produced is 5 to 20 times the amount of CH4 produced; in, is the CO2 carbon emission intensity of the septic tank, kg CO2-eq / m 3 ; (2.3) For N2O emissions: The amount of N2O produced is only 0.01 to 0.1 times the amount of CH4 produced; in, is the carbon emission intensity of N2O from septic tanks, kg CO2-eq / m 3 ;but Among them, CES hfc is the carbon emission intensity of septic tank, kg CO2-eq / m 3 .

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