A method for calculating greenhouse gas emissions from drainage pipe network systems

Abstract

The present invention discloses a method for calculating greenhouse gas emissions of a drainage pipe network system, and relates to the technical field of water supply and drainage gas measurement. The method comprises: determining the emission factor and emission data of the drainage pipe network system within a boundary range; calculating all greenhouse gas emission intensities according to the emission factor and the emission data, and adding all greenhouse gas emission intensities to obtain the total greenhouse gas emission intensity within the boundary range. The present invention can improve the accuracy and completeness of greenhouse gas emission accounting of the drainage pipe network system.

Description

Technical Field

[0001] The present invention relates to the technical field of water supply and drainage gas measurement, and in particular to a method for calculating greenhouse gas emissions from a drainage pipe network system. Background Art

[0002] The urban drainage pipe network system is not only an important means of collecting and transporting pollutants in the process of urban water environment governance, but also a key link in the urban water resource cycle. The development of China's urbanization and the improvement of pipe network facilities have made the role of the urban drainage pipe network system in the entire water system more and more important. With the advancement of my country's "carbon peak" and "carbon neutrality" strategies, greenhouse gas emissions from water systems have become a hot topic of social concern. Initially, the drainage pipe network system was often classified as a collection system outside the study of greenhouse gas emissions from urban sewage treatment systems. However, current research has found that in urban sewage pipes, greenhouse gases such as methane (CH4) and nitrous oxide (N2O) are produced due to the physical, chemical and biological effects of microorganisms attached to the pipe wall. And the emission of greenhouse gases in the pipe network (only considering CH4) is equivalent to 20% of the greenhouse gases emitted by sewage treatment plants due to energy consumption. Therefore, in order to support the joint carbon reduction of the entire water system, it is a very important step for the urban sewage pipe network system to establish an accurate carbon emission accounting method. Currently, the technical solutions for quantifying greenhouse gas emissions from sewage treatment facilities have technical issues that have not been fully considered for the characteristics of the drainage network system itself, such as pipeline leakage and the lack of pump station data for gravity pipelines that rely on gravity flow.

[0003] Based on the above basic information, it is urgent to build a reasonable greenhouse gas emission quantification method based on the characteristics of the drainage network system. For the drainage network system, the pipeline leakage rate and pollutant collection rate are two important indicators, reflecting the drainage network system's ability to collect sewage itself and the pollutants therein. On the one hand, considering that the generation of greenhouse gases is closely related to the environmental conditions, the greenhouse gas emissions generated by the biochemical reactions of pollutants seeping out of the pipeline need to be distinguished from the calculation method inside the pipeline. On the other hand, unlike the pressure pump water delivery of the water supply system, the gravity pipelines that rely on gravity flow account for a large proportion in the drainage network system. Therefore, since gravity pipelines do not require pumping stations, the availability of data such as pollutant inlet concentration and sewage flow rate becomes poor. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating greenhouse gas emissions from a drainage pipe network system, which can improve the accuracy and completeness of the calculation of greenhouse gas emissions from the drainage pipe network system.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for calculating greenhouse gas emissions from a drainage network system, comprising:

[0007] Determine the emission factors and emission data of the drainage network system within the boundary; the emission factors include: CH4 direct emission factor, N2O direct emission factor, CH4 leakage emission factor, N2O leakage emission factor, electricity emission factor, fuel emission factor, pipe emission factor and manhole cover emission factor; the emission data include: sewage generation, sewage plant inflow, initial average total nitrogen concentration, terminal average total nitrogen concentration, initial average COD concentration, terminal average COD concentration, total electricity consumption in the evaluation year, vehicle fuel outbound volume data, pipe outbound length data and manhole cover outbound quantity data;

[0008] All greenhouse gas emission intensities are calculated according to the emission factors and the emission data, and all greenhouse gas emission intensities are added together to obtain the total greenhouse gas emission intensity within the boundary range; the greenhouse gas emission intensity includes: CH4 direct emission intensity, N2O direct emission intensity, CH4 leakage emission intensity, N2O leakage emission intensity, emission intensity generated by electricity consumption, emission intensity generated by transportation fuel consumption, emission intensity generated by pipe replacement and emission intensity generated by manhole cover replacement.

[0009] Optionally, the determining of the emission factors and emission data of the drainage pipe network system within the boundary range includes:

[0010] Defining the data collection boundary of the target area; the target area is the urban drainage pipe network system;

[0011] The emission factors and emission data of the drainage pipe network system within the boundary are determined according to the data collection boundary.

[0012] Optionally, all greenhouse gas emission intensities are calculated according to the emission factors and the emission data, and all greenhouse gas emission intensities are added together to obtain a total greenhouse gas emission intensity within the boundary, including:

[0013] According to the sewage generation, sewage treatment plant inflow, initial total nitrogen average concentration, terminal total nitrogen average concentration, initial COD average concentration and terminal COD average concentration, the regional total nitrogen collection rate and regional COD collection rate are calculated respectively;

[0014] The CH4 direct emission intensity of the drainage pipe system was calculated based on the initial COD average concentration, regional total nitrogen collection rate, regional COD collection rate and CH4 direct emission factor;

[0015] Calculate the direct N2O emission intensity of the drainage pipe system based on the sewage generation, sewage plant inflow, and N2O direct emission factor;

[0016] The CH4 leakage emission intensity of the drainage pipe system was calculated based on the initial COD average concentration, regional total nitrogen collection rate and CH4 leakage emission factor;

[0017] The N2O leakage emission intensity of the drainage pipe system is calculated based on the initial average total nitrogen concentration, regional total nitrogen collection rate and N2O leakage emission factor;

[0018] Calculate the emission intensity of electricity consumption based on the total electricity consumption, sewage generation and electricity emission factor of the assessment area during the assessment year;

[0019] Based on the vehicle fuel outbound volume data, pipe outbound length data, manhole cover outbound quantity data, sewage generation, fuel emission factor, pipe emission factor and manhole cover emission factor, the emission intensity generated by transportation fuel consumption, pipe replacement and manhole cover replacement during operation are calculated respectively;

[0020] All greenhouse gas emission intensities are added together to obtain the total greenhouse gas emission intensity within the boundary. Optionally, the calculation formula for the regional total nitrogen collection rate and the regional COD collection rate is:

[0021] R TN =(Q w ×TN e ) / (Q×TN0)

[0022] R TCOD =(Q w ×TCOD e ) / (Q×TCOD0)

[0023] Among them, R TN is the regional total nitrogen collection rate; R TCOD is the regional COD collection rate; Q w is the water inflow of the sewage treatment plant; TN e is the average concentration of total nitrogen at the end; TN0 is the average concentration of total nitrogen at the initial stage; TCOD e is the average terminal COD concentration; TCOD0 is the average initial COD concentration.

[0024] Optionally, the calculation formula for the CH4 direct emission intensity is:

[0025] C CH4 =EF CH4 ×TCOD0×(R TN -R TCOD )×28

[0026] Among them, EF CH4 is the direct emission factor of CH4; TCOD0 is the average initial COD concentration; R TN is the regional total nitrogen collection rate; RTCOD is the regional COD collection rate.

[0027] Optionally, the calculation formula for the N2O direct emission intensity is:

[0028] C N20 =EF N20 ×265×Q w / Q

[0029] Among them, EF N2O is the direct emission factor of N2O; Q w is the water inflow of the sewage treatment plant; Q is the amount of sewage generated.

[0030] Optionally, the calculation formula for the CH4 leakage emission intensity is:

[0031] C CH4′ =EF CH4′ ×TCOD0×(1-R TN )×28

[0032] Among them, EF CH4′ is the CH4 leakage emission factor; TCOD0 is the initial COD average concentration; R TN is the regional total nitrogen collection rate.

[0033] Optionally, the calculation formula for the N2O leakage emission intensity is:

[0034] C N20′ =EF N20′ ×TN0×(1-R TN )×22 / 14×265

[0035] Among them, EF N20′ is the N2O leakage emission factor; TN0 is the initial average total nitrogen concentration R TN is the regional total nitrogen collection rate.

[0036] Optionally, the calculation formula for the emission intensity generated by the electricity consumption is:

[0037] C d =(E d ×·EF d ) / Q

[0038] Among them, E d To evaluate the total electricity consumption in a year; EF d Electricity emission factor; Q is the amount of sewage generated.

[0039] Optionally, the calculation formulas for the emission intensity generated by the transportation fuel consumption, the emission intensity generated by the pipe replacement, and the emission intensity generated by the manhole cover replacement are respectively:

[0040] C ys =∑ i (V i ×EF ys，i ) / Q

[0041] C gc =∑ i (L i ×EF gc，i ) / Q

[0042] C jg =∑ i (G i ×EF jg，i ) / Q

[0043] Among them, C ys Emission intensity of transportation fuel consumption; C gc Emission intensity caused by pipe replacement; C jg Emission intensity caused by pipe replacement; EF ys，i is the fuel emission factor; EF gc，i is the pipe emission factor; EF jg，i is the manhole cover emission factor; V i The volume data of vehicle fuel out of the warehouse; L i G is the length data of the pipe out of the warehouse; i is the quantity of manhole covers shipped out; Q is the amount of sewage generated.

[0044] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0045] The present invention discloses a method for calculating greenhouse gas emissions of a drainage pipe network system, the method comprising determining the emission factor and emission data of the drainage pipe network system within a boundary range; calculating all greenhouse gas emission intensities according to the emission factor and the emission data, and adding all greenhouse gas emission intensities to obtain the total greenhouse gas emission intensity within the boundary range. The present invention can improve the accuracy and completeness of greenhouse gas emission accounting of the drainage pipe network system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0047] Figure 1 A schematic flow chart of a method for calculating greenhouse gas emissions from a drainage pipe network system of the present invention;

[0048] Figure 2This is a logical diagram of the greenhouse gas emission accounting method in this embodiment. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The purpose of the present invention is to provide a method for calculating greenhouse gas emissions from a drainage pipe network system, which can improve the accuracy and completeness of the calculation of greenhouse gas emissions from the drainage pipe network system.

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] like Figure 1 As shown, the present invention provides a method for calculating greenhouse gas emissions of a drainage pipe network system, comprising:

[0053] Step 100: Determine the emission factors and emission data of the drainage pipe network system within the boundary range; the emission factors include: CH4 direct emission factor, N2O direct emission factor, CH4 leakage emission factor, N2O leakage emission factor, electricity emission factor, fuel emission factor, pipe emission factor and manhole cover emission factor; the emission data include: sewage generation, sewage plant inflow, initial average total nitrogen concentration, terminal average total nitrogen concentration, initial average COD concentration, terminal average COD concentration, total electricity consumption in the evaluation year, vehicle fuel outbound volume data, pipe outbound length data and manhole cover outbound quantity data;

[0054] Step 200: Calculate all greenhouse gas emission intensities according to the emission factors and the emission data, and add up all greenhouse gas emission intensities to obtain the total greenhouse gas emission intensity within the boundary range; the greenhouse gas emission intensity includes: CH4 direct emission intensity, N2O direct emission intensity, CH4 leakage emission intensity, N2O leakage emission intensity, emission intensity generated by electricity consumption, emission intensity generated by transportation fuel consumption, emission intensity generated by pipe replacement and emission intensity generated by manhole cover replacement.

[0055] Based on the above solution, a specific implementation method is provided.

[0056] S1: Define the data collection boundary for urban drainage pipe network system accounting, and analyze the greenhouse gas emission activities of the drainage pipe network system. The default greenhouse gas emission activities of the drainage pipe network system in the present invention are shown in the following table:

[0057]

[0058] Among them, the indicators and units that need to be collected for the original data are shown in the following table:

[0059]

[0060] S2: Based on the sewage generation (Q) within the boundary range obtained in step S1, the sewage treatment plant inflow (Q W ), the average total nitrogen concentration at the initial stage within the boundary range (TN0), the average total nitrogen concentration at the end of the boundary range (TN e ), the average initial COD concentration within the boundary range (TCOD0), the average terminal COD concentration within the boundary range (TCOD e ) Calculate the regional total nitrogen collection rate (R TN ) and regional COD collection rate (R TCOD ). The calculation formula is as follows:

[0061] R TN =(Q w ×TN e ) / (Q×TN0)

[0062] R TCOD =(Q w ×TCOD e ) / (Q×TCOD0)

[0063] Among them, R TN is the regional total nitrogen collection rate; R TCOD is the regional COD collection rate; Q w is the water inflow of the sewage treatment plant; TN e is the average concentration of total nitrogen at the end; TN0 is the average concentration of total nitrogen at the initial stage; TCOD e is the average terminal COD concentration; TCOD0 is the average initial COD concentration.

[0064] Furthermore, the initial average concentration of total nitrogen within the boundary range and the initial average concentration of COD within the boundary range are calculated as follows:

[0065] TN0=PL inTN ×0.001

[0066] TCOD0=PL inCOD ×0.001

[0067]

[0068] The significance of calculating the regional total nitrogen collection rate and regional COD collection rate in S2:

[0069] Since COD is easily biodegradable in pipelines, this method assumes that the degradation rate of total nitrogen in pipelines is very low when considering leakage emissions. The pollutant infiltration rate can be calculated by the regional total nitrogen collection rate. Therefore, for the regional total nitrogen collection rate, the regional pollutant infiltration rate (R Ex ), regional COD collection rate, regional COD biodegradation rate in pipelines (R D )Assume the following formula:

[0070] R TN +R Ex =1

[0071] R TCOD +R Ex +R D =1

[0072] Therefore, the regional pollutant infiltration rate R Ex =1-R TN , regional COD biodegradation rate in pipeline R D =1-R Ex -R TCOD =R TN -R TCOD . Based on this, this method uses the method of "initial COD average concentration x biodegradation rate in the COD pipeline of the area" as the activity level data when calculating the direct emission intensity of CH4, and uses "initial COD average concentration x area pollutant infiltration rate" and "initial total nitrogen average concentration x area pollutant infiltration rate" as the activity level data when calculating the CH4 leakage emission intensity and N2O leakage emission intensity. For the direct emission intensity of N2O, since the available emission factors correspond to the influent water volume of the sewage treatment plant, the activity level data corresponding to the direct emission intensity of N2O in this method is the influent water volume of the regional sewage treatment plant.

[0073] S3: Calculate the CH4 direct emission intensity of the drainage pipe system based on the regional total nitrogen collection rate and regional COD collection rate obtained in step S2, combined with the CH4 direct emission factor and the initial COD average concentration within the boundary range obtained in step S1. The calculation formula is as follows:

[0074] C CH4 =EF CH4 ×TCOD0×(R TN -R TCOD )×28

[0075] Among them, EF CH4 is the direct emission factor of CH4; TCOD0 is the average initial COD concentration; R TN is the regional total nitrogen collection rate R TCODis the regional COD collection rate. 28 in the formula is the global warming potential of CH4, in kg CO2 / kg CH4.

[0076] CH4 direct emission factor (EF CH4 )

[0077]

[0078] η T =η 20 ε T-20

[0079]

[0080] The calculation formula of average hydraulic retention time t is as follows:

[0081] t=Q / V

[0082]

[0083] S4: Calculate the direct N2O emission intensity of the drainage pipe system based on the sewage generation within the boundary range obtained in step S1, the water inflow of the sewage treatment plant within the boundary range, and the direct N2O emission factor. The calculation formula is as follows:

[0084] C N20 =EF N20 ×265×Q w / Q

[0085] Among them, EF N2O is the direct emission factor of N2O; Q w is the water inflow of the sewage treatment plant; Q is the sewage generation. 265 in the formula is the global warming potential of N2O, in kg CO2 / kg N2O.

[0086] Determination of direct N2O emission factors. The direct N2O emission factors have the following references:

[0087]

[0088] S5: Calculate the CH4 leakage emission intensity of the drainage pipe system based on the total nitrogen collection rate within the boundary range obtained in step S2, combined with the CH4 leakage emission factor and the initial COD average concentration within the boundary range obtained in step S1. The calculation formula is as follows:

[0089] C CH4′ =EF CH4′ ×TCOD0×(1-R TN )×28

[0090] Among them, EF CH4′is the CH4 leakage emission factor; TCOD0 is the initial COD average concentration R TN is the regional total nitrogen collection rate. Determination of CH4 leakage emission factor:

[0091] Refer to the CH4 emission factor discharged into natural water bodies in IPCC2019, which is 0.028kgCH4 / kg COD.

[0092] S6: Calculate the N2O leakage emission intensity of the drainage pipe system based on the total nitrogen collection rate within the boundary range obtained in step S2, combined with the N2O leakage emission factor and the initial total nitrogen average concentration within the boundary range obtained in step S1. The calculation formula is as follows:

[0093] C N20′ =EF N20′ ×TN0×(1-R TN )×22 / 14×265

[0094] Among them, EF N20′ is the N2O leakage emission factor; TN0 is the initial average total nitrogen concentration R TN is the regional total nitrogen collection rate. Determination of N2O leakage emission factor:

[0095] Refer to the N2O emission factor discharged into natural water bodies in IPCC2019, which is 0.005kgN2O / kg TN.

[0096] S7: Calculate the emission intensity of electricity consumption based on the total electricity consumption in the evaluation year and the amount of sewage generated within the boundary range obtained in step S1, combined with the electricity emission factor of the evaluation area. The calculation formula is as follows:

[0097] C d =(E d ×·EF d ) / Q

[0098] Among them, Ed is the total electricity consumption in the evaluation year; EF d Electricity emission factor; Q is the amount of sewage generated. Determination of electricity emission factor:

[0099] Referring to the latest national electricity carbon emission factor of the Ministry of Ecology and Environment, 0.5810kgCO2 / (kW·h) is taken.

[0100] S8: Based on the vehicle fuel outbound volume data, pipe outbound length data, manhole cover outbound quantity data and sewage generation within the boundary range obtained in step S1, combined with the fuel emission factor, pipe emission factor and manhole cover emission factor, calculate the emission intensity generated by transportation fuel consumption during operation, the emission intensity generated by pipe replacement and the emission intensity generated by manhole cover replacement. The calculation formula is as follows:

[0101] C ys =∑ i (V i ×EF ys，i ) / Q

[0102] C gc =∑ i (L i ×EF gc，i ) / Q

[0103] C jg =∑ i (G i ×EF jg，i ) / Q

[0104] Among them, C ys Emission intensity of transportation fuel consumption; C gc Emission intensity caused by pipe replacement; C jg Emission intensity caused by pipe replacement; EF ys,i is the fuel emission factor; EF gc,i is the pipe emission factor; EF jg，i is the manhole cover emission factor; V i The volume data of vehicle fuel out of the warehouse; L i G is the length data of the pipe out of the warehouse; i is the quantity of manhole covers shipped out; Q is the amount of sewage generated.

[0105] S9: Add all greenhouse gas emission intensity results calculated in steps S3 to S8 to obtain the total greenhouse gas emission intensity (C T ). The calculation formula is as follows:

[0106] C T =C CH4 +C N20 +C CH4′ +C N20′ +C d +C ys +C gc +C jg

[0107] It can be seen from the above embodiments that the water supply volume and pollution coefficient, pipeline leakage rate, pollutant collection rate and other indicators are used in combination with different emission factors to calculate the direct greenhouse gas emissions and leakage emissions in the pipeline, as well as the indirect emissions caused by electricity consumption, transportation fuel consumption, and material replacement.

[0108] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0109] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for calculating greenhouse gas emissions from a drainage network system, characterized in that: include: Determine the emission factors and emission data of the drainage network system within the boundary; The emission factors include: CH4 direct emission factor, N2O direct emission factor, CH4 leakage emission factor, N2O leakage emission factor, electricity emission factor, fuel emission factor, pipe emission factor and manhole cover emission factor; the emission data include: sewage generation, sewage plant inflow, initial average total nitrogen concentration, terminal average total nitrogen concentration, initial average COD concentration, terminal average COD concentration, total electricity consumption in the evaluation year, vehicle fuel outbound volume data, pipe outbound length data and manhole cover outbound quantity data; Calculate all greenhouse gas emission intensities according to the emission factors and the emission data, and add up all greenhouse gas emission intensities to obtain the total greenhouse gas emission intensity within the boundary; the greenhouse gas emission intensity includes: CH4 direct emission intensity, N2O direct emission intensity, CH4 leakage emission intensity, N2O leakage emission intensity, emission intensity generated by electricity consumption, emission intensity generated by transportation fuel consumption, emission intensity generated by pipe replacement and emission intensity generated by manhole cover replacement; Calculate all greenhouse gas emission intensities based on the emission factors and the emission data, and add up all greenhouse gas emission intensities to obtain the total greenhouse gas emission intensity within the boundary, including: According to the sewage generation, sewage treatment plant inflow, initial total nitrogen average concentration, terminal total nitrogen average concentration, initial COD average concentration and terminal COD average concentration, the regional total nitrogen collection rate and regional COD collection rate are calculated respectively; The CH4 direct emission intensity of the drainage pipe system was calculated based on the initial COD average concentration, regional total nitrogen collection rate, regional COD collection rate and CH4 direct emission factor; Calculate the direct N2O emission intensity of the drainage pipe system based on the sewage generation, sewage plant inflow, and N2O direct emission factor; The CH4 leakage emission intensity of the drainage pipe system was calculated based on the initial COD average concentration, regional total nitrogen collection rate and CH4 leakage emission factor; The N2O leakage emission intensity of the drainage pipe system is calculated based on the initial average total nitrogen concentration, regional total nitrogen collection rate and N2O leakage emission factor; Calculate the emission intensity of electricity consumption based on the total electricity consumption, sewage generation and electricity emission factor of the assessment area during the assessment year; Based on the vehicle fuel outbound volume data, pipe outbound length data, manhole cover outbound quantity data, sewage generation, fuel emission factor, pipe emission factor and manhole cover emission factor, the emission intensity generated by transportation fuel consumption, pipe replacement and manhole cover replacement during operation are calculated respectively; Add up all greenhouse gas emission intensities to obtain the total greenhouse gas emission intensity within the boundary.

2. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The emission factors and emission data for the drainage network system within the boundary range shall include: Defining the data collection boundary of the target area; the target area is the urban drainage pipe network system; The emission factors and emission data of the drainage pipe network system within the boundary are determined according to the data collection boundary.

3. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The calculation formulas for the regional total nitrogen collection rate and the regional COD collection rate are: R TN =(Q w ×TN e ) / (Q×TN0) R TCOD =(Q w ×TCOD e ) / (Q×TCOD0) Among them, R TN is the regional total nitrogen collection rate; R TCOD is the regional COD collection rate; Q w is the water inflow of the sewage treatment plant; TN e is the average concentration of total nitrogen at the end; TN0 is the average concentration of total nitrogen at the initial stage; TCOD e is the average terminal COD concentration; TCOD0 is the average initial COD concentration.

4. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The calculation formula for the CH4 direct emission intensity is: C CH4 =EF CH4 ×TCOD0×(R TN -R TCOD )×28 Among them, EF CH4 is the direct emission factor of CH4; TCOD0 is the average initial COD concentration; R TN is the regional total nitrogen collection rate; R TCOD is the regional COD collection rate.

5. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The calculation formula for the direct N2O emission intensity is: C N2O =EF N2O ×265×Q w / Q Among them, EF N2O is the direct emission factor of N2O; Q w is the water inflow of the sewage treatment plant; Q is the amount of sewage generated.

6. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The calculation formula for the CH4 leakage emission intensity is: C CH4′ =EF CH4′ ×TCOD0×(1-R TN )×28 Among them, EF CH4′ is the CH4 leakage emission factor; TCOD0 is the initial COD average concentration; R TN is the regional total nitrogen collection rate.

7. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The calculation formula for the N2O leakage emission intensity is: C N2O′ =EF N2O′ ×TN0×(1-R TN )×22 / 14×265 Among them, EF N2O′ is the N2O leakage emission factor; TN0 is the initial average concentration of total nitrogen; R TN is the regional total nitrogen collection rate.

8. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The calculation formula for the emission intensity generated by the electricity consumption is: C d =(Ed×·EF d ) / Q Among them, E d To evaluate the total electricity consumption in a year; EF d Electricity emission factor; Q is the amount of sewage generated.

9. The greenhouse gas emission accounting method of the drainage pipe network system according to claim 1 is characterized in that: The calculation formulas for the emission intensity generated by the transportation fuel consumption, the emission intensity generated by the pipe replacement, and the emission intensity generated by the manhole cover replacement are: C ys =∑ i (V i ×EF ys，i ) / Q C gc =∑ i (L i ×EF gc，i ) / Q C jg =∑ i (G i ×EF jg，i ) / Q Among them, C ys Emission intensity of transportation fuel consumption; C gc Emission intensity caused by pipe replacement; C jg Emission intensity caused by pipe replacement; EF ys，i is the fuel emission factor; EF gc，i is the pipe emission factor; EF jg，i is the manhole cover emission factor; V i The volume data of vehicle fuel out of the warehouse; L i G is the length data of the pipe out of the warehouse; i is the quantity of manhole covers shipped out; Q is the amount of sewage generated.

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