A process greenhouse gas emission assessment method suitable for sewage treatment plants

Abstract

The application provides a process greenhouse gas emission evaluation method suitable for a sewage treatment plant, comprising the following steps: determining process sections of the sewage treatment plant and types of pollutants generated; being divided into liquid, solid and gaseous accounting; accounting process, calculating annual COD reduction of a pretreatment section, a biochemical treatment section and a deep treatment section, calculating annual TN reduction of the biochemical treatment section and the deep treatment section; calculating annual existing dry sludge amount of the deep treatment section; step two, removing CH4 generated by removing COD in sewage, and converting into E COD ; removing N2O generated by removing TN in sewage, and converting into E TN ; removing CH4 generated by removing TN in sludge, and converting into E 污泥 ; CO2 emission equivalent E 电力 generated by annual power consumption of sewage treatment equipment operation; greenhouse gas net emission reduction amount accounting is represented as: E=E COD +E TN +E 污泥 +E 电力 .

Description

Technical Field

[0001] This invention relates to the field of greenhouse gas emission assessment, and in particular to a method for assessing greenhouse gas emissions from processes in wastewater treatment plants. Background Technology

[0002] Current technologies often use the entire wastewater treatment plant as the accounting object without calculating step-by-step according to the process flow, resulting in vague and unclear data sources. Clearly defining the greenhouse gas emissions from wastewater treatment plants offers several advantages: First, it allows for a clear analysis of carbon emissions throughout the entire process, enabling precise calculation of greenhouse gas production at each stage. Second, it allows for the determination of collection or other treatment methods based on the greenhouse gas production at each stage. Third, since upgrading and renovation to further reduce carbon and nitrogen content in effluent will lead to increased carbon and nitrogen content in emissions, clearly defining the greenhouse gas emissions at each process stage facilitates an analysis of the relationship between greenhouse gas emissions and the benefits of upgrading and renovation of wastewater treatment plants. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for assessing greenhouse gas emissions from wastewater treatment plant processes.

[0004] This invention provides a method for assessing greenhouse gas emissions from wastewater treatment plant processes, comprising:

[0005] Step 1: Calculate the amount of carbon and nitrogen in both liquid and solid states.

[0006] 1) Determine the process stages of the wastewater treatment plant and the types of pollutants generated, among which,

[0007] Pretreatment section: coarse screen, lift pump station, fine screen and vortex grit chamber

[0008] Biochemical treatment section: hydrolysis acidification tank, oxidation ditch, secondary sedimentation tank

[0009] Advanced treatment section: secondary booster pump station, sedimentation tank, filter, contact tank

[0010] Pollutant types: methane, chemical oxygen demand, total nitrogen, sludge;

[0011] 2) Accounting Method

[0012] Accounting is divided into liquid, solid, and gaseous states.

[0013] Liquid accounting: Accounting for the reduction of pollutants in influent and effluent.

[0014] Solid-state accounting: Accounting for the reduction of sludge generated.

[0015] Gaseous accounting: Calculating the amount of gas produced

[0016] 3) Accounting process

[0017] Preprocessing section

[0018] ① Annual COD reduction:

[0019] COD 核减量1 =Q*(COD) 进水 -COD1)*d*10 -9 (1)

[0020] In the formula, Q represents the average daily wastewater treatment volume per year; COD 进水 COD1 is the annual average daily influent chemical oxygen demand of the wastewater treatment plant; COD1 is the annual average daily effluent chemical oxygen demand of the vortex grit chamber outlet; d is the number of operating days per year.

[0021] ②Annual TN reduction:

[0022] TN 核减量1 =Q*(TN) 进水 -TN1)*d*10 -9 (2)

[0023] In the formula, Q represents the average daily wastewater treatment volume per year; TN 进水 TN1 is the annual average daily influent total nitrogen of the wastewater treatment plant; TN2 is the annual average daily effluent total nitrogen at the vortex grit chamber outlet; d is the number of operating days per year.

[0024] Biochemical treatment section

[0025] ① Annual COD reduction

[0026] COD 核减量2 =(Q*COD1*d+M COD *VQ*COD2*d)*10 -9 (3)

[0027] In the formula, Q is the average daily wastewater treatment volume; COD1 is the average daily chemical oxygen demand (COD) at the outlet of the vortex grit chamber; COD2 is the average daily COD at the outlet of the oxidation ditch; M COD The COD equivalent is calculated for different carbon sources; V is the annual carbon source input; d is the number of operating days per year.

[0028] ② Annual TN reduction

[0029] TN 核减量2 =(Q*TN1*d+M TN *VQ*TN2*d)*10 -9 (4)

[0030] In the formula, Q is the average daily wastewater treatment volume; TN1 is the average daily total nitrogen at the outlet of the vortex grit chamber; TN2 is the average daily total nitrogen at the outlet of the oxidation ditch; MTN The carbon source is introduced, and the value varies depending on the carbon source; V is the annual carbon source addition; d is the number of operating days per year;

[0031] Deep processing segment

[0032] ① Annual COD reduction:

[0033] COD 核减量3 =Q*(COD2-COD 出水 )*d*10 -9 (5)

[0034] In the formula, Q is the average daily wastewater treatment volume per year; COD2 is the average daily chemical oxygen demand at the oxidation ditch outlet per year; COD 出水 d represents the average daily chemical oxygen demand (COD) of the wastewater treatment plant; d represents the number of operating days per year.

[0035] ②Annual TN reduction:

[0036] TN 核减量3 =Q*(TN2-TN 出水 )*d*10 -9 (6)

[0037] In the formula, Q is the average daily wastewater treatment volume per year; TN2 is the average daily total nitrogen at the oxidation ditch outlet per year; TN 出水 d represents the average daily total nitrogen in the wastewater effluent from the wastewater treatment plant; d represents the number of operating days per year.

[0038] ③ The annual amount of dry sludge in the factory area:

[0039] M 干污泥量 =Q*f*da*(1-W) 含水率 )*d1 (7)

[0040] In the formula, Q is the average daily wastewater treatment volume; f is the dry mass of sludge generated daily by the wastewater treatment plant; a is the average daily sludge removal volume; W 含水率 Different desliming methods result in different moisture contents, generally between 60-80%; d represents the number of operating days per year; d1 represents the number of days for desliming.

[0041] Step two: Estimate greenhouse gas emissions using liquid and solid carbon and nitrogen elements.

[0042] ① The annual emission of CH4 produced by removing COD from wastewater, converted to carbon dioxide equivalent:

[0043] E COD = (COD 核减量 -M 干污泥量 *ρ)*EF CH4 *GWP CH4 (8)

[0044] In the formula, COD 核减量 For the annual COD reduction; M 干污泥量 ρ represents the annual amount of dry sludge present in the plant area; ρ represents the organic matter content in the dry sludge; EF CH4 The CH4 emission factor, TCH4 / TCOD, ranges from 0 to 0.25; GWP CH4 The global warming potential value for CH4 is set to 21.

[0045] COD 核减量 The data is obtained through formula (1) + (3) + (5) in step one, M 干污泥量 The data is obtained through formula (7) in step one, and ρ is obtained through actual measurement of data from the sewage treatment plant.

[0046] ② The annual N2O generated from removing TN from wastewater, converted to carbon dioxide equivalent:

[0047] E TN =TN 核减量 *EF N2O *C N2O / N2 *GWP N2O (9)

[0048] In the formula, TN 核减量 For annual TN reduction; EF N2O The amount of nitrogen that can be converted into nitrous oxide per unit mass of nitrogen in wastewater is represented by a value of 0 for the aerobic zone and 0.005 for the anoxic zone; C N2O / N2 The ratio of N2O / N2 molecular weight is 44 / 28; GWP N2O The global warming potential value for N2O is set to 310.

[0049] TN 核减量 The data is obtained through formula (2) + (4) + (6) in step one;

[0050] ③ The annual emissions of CH4 produced during sludge removal, converted to carbon dioxide equivalent:

[0051] E 污泥 =M 干污泥量 *ρ*DOC f *MCF*F*C CH4 / C *GWP CH4 (10)

[0052] In the formula, M 干污泥量 ρ represents the annual dry sludge volume in the plant area; ρ represents the organic matter content in the dry sludge; DOC fThe percentage of biodegradable organic carbon in the dry matter of sludge is 50%; MCF is the CH4 correction factor, with a value of 1 for completely anaerobic conditions and 0 for completely aerobic conditions; F is the proportion of carbon in the biodegradable organic carbon that can produce CH4, with a value of 50%; C CH4 / C The ratio of CH4 to C molecular weight is 16 / 12; GWP CH4 The global warming potential value for CH4 is set to 21.

[0053] M 干污泥量 The data is obtained through formula (7) in step one, and ρ is obtained through actual measurement of data from the sewage treatment plant.

[0054] ④ CO2 emission equivalent generated by the annual electricity consumption of wastewater treatment equipment:

[0055] E 电力 =EH*EF CO2 *GWP CO2 (11)

[0056] In the formula, EH represents the annual power consumption of the plant's wastewater treatment equipment; EF CO2 CO2 emission factor for electricity; GWP CO2 The global warming potential for CO2 is set to 1; EH data is obtained from electricity invoices and electricity ledgers of wastewater treatment plants during the accounting period; emission factors are determined by actual measurement or by using recommended emission factor values.

[0057] Step 3, calculation of net greenhouse gas emission reductions, expressed as follows:

[0058] E=E COD +E TN +E 污泥 +E 电力 (12)

[0059] In the formula: E COD The annual emission of CH4 generated from the removal of COD from wastewater, converted to carbon dioxide equivalent; E TN The annual N2O emissions generated from the removal of TN from wastewater, converted to carbon dioxide equivalent; E 污泥 Annual emissions of CH4 generated from sludge removal, converted to carbon dioxide equivalent; E 电力 CO2 emission equivalent generated by the annual electricity consumption of wastewater treatment equipment.

[0060] This invention has outstanding substantive effects and significant progress compared with the prior art. Specifically, this invention combines the actual situation of wastewater treatment plants and simultaneously considers the COD equivalent data of carbon sources and the COD of influent to calculate greenhouse gas emissions, making the calculation results more accurate. Detailed Implementation

[0061] This embodiment proposes a method for assessing greenhouse gas emissions from wastewater treatment plant processes, including:

[0062] Step 1: Calculate the amount of carbon and nitrogen in both liquid and solid states.

[0063] 1) Determine the process stages of the wastewater treatment plant and the types of pollutants generated, among which,

[0064] Pretreatment section: coarse screen, lift pump station, fine screen and vortex grit chamber

[0065] Biochemical treatment section: hydrolysis acidification tank, oxidation ditch, secondary sedimentation tank

[0066] Advanced treatment section: secondary booster pump station, sedimentation tank, filter, contact tank

[0067] Pollutant types: methane, chemical oxygen demand, total nitrogen, sludge;

[0068] 2) Accounting Method

[0069] Accounting is divided into liquid, solid, and gaseous states.

[0070] Liquid accounting: Accounting for the reduction of pollutants in influent and effluent.

[0071] Solid-state accounting: Accounting for the reduction of sludge generated.

[0072] Gaseous accounting: Calculating the amount of gas produced

[0073] 3) Accounting process

[0074] Preprocessing section

[0075] ① Annual COD reduction:

[0076] COD 核减量1 =Q*(COD) 进水 -COD1)*d*10 -9 (1)

[0077] In the formula, Q represents the average daily wastewater treatment volume per year; COD 进水 COD1 is the annual average daily influent chemical oxygen demand of the wastewater treatment plant; COD1 is the annual average daily effluent chemical oxygen demand of the vortex grit chamber outlet; d is the number of operating days per year.

[0078] ②Annual TN reduction:

[0079] TN 核减量1 =Q*(TN) 进水 -TN1)*d*10 -9 (2)

[0080] In the formula, Q represents the average daily wastewater treatment volume per year; TN 进水TN1 is the annual average daily influent total nitrogen of the wastewater treatment plant; TN2 is the annual average daily effluent total nitrogen at the vortex grit chamber outlet; d is the number of operating days per year.

[0081] Biochemical treatment section

[0082] ① Annual COD reduction

[0083] COD 核减量2 =(Q*COD1*d+M COD *VQ*COD2*d)*10 -9 (3)

[0084] In the formula, Q is the average daily wastewater treatment volume; COD1 is the average daily chemical oxygen demand (COD) at the outlet of the vortex grit chamber; COD2 is the average daily COD at the outlet of the oxidation ditch; M COD The COD equivalent is calculated for different carbon sources; V is the annual carbon source input; d is the number of operating days per year.

[0085] ② Annual TN reduction

[0086] TN 核减量2 =(Q*TN1*d+M TN *VQ*TN2*d)*10 -9 (4)

[0087] In the formula, Q is the average daily wastewater treatment volume; TN1 is the average daily total nitrogen at the outlet of the vortex grit chamber; TN2 is the average daily total nitrogen at the outlet of the oxidation ditch; M TN The carbon source is introduced, and the value varies depending on the carbon source; V is the annual carbon source addition; d is the number of operating days per year;

[0088] Deep processing segment

[0089] ① Annual COD reduction:

[0090] COD 核减量3 =Q*(COD2-COD 出水 )*d*10 -9 (5)

[0091] In the formula, Q is the average daily wastewater treatment volume per year; COD2 is the average daily chemical oxygen demand at the oxidation ditch outlet per year; COD 出水 d represents the average daily chemical oxygen demand (COD) of the wastewater treatment plant; d represents the number of operating days per year.

[0092] ②Annual TN reduction:

[0093] TN 核减量3 =Q*(TN2-TN 出水 )*d*10 -9 (6)

[0094] In the formula, Q is the average daily wastewater treatment volume per year; TN2 is the average daily total nitrogen at the oxidation ditch outlet per year; TN 出水 d represents the average daily total nitrogen in the wastewater effluent from the wastewater treatment plant; d represents the number of operating days per year.

[0095] ③ The annual amount of dry sludge in the factory area:

[0096] M 干污泥量 =Q*f*da*(1-W) 含水率 )*d1 (7)

[0097] In the formula, Q is the average daily wastewater treatment volume; f is the dry mass of sludge generated daily by the wastewater treatment plant; a is the average daily sludge removal volume; W 含水率 Different desliming methods result in different moisture contents, generally between 60-80%; d represents the number of operating days per year; d1 represents the number of days for desliming.

[0098] Step two: Estimate greenhouse gas emissions using liquid and solid carbon and nitrogen elements.

[0099] ① The annual emission of CH4 produced by removing COD from wastewater, converted to carbon dioxide equivalent:

[0100] E COD = (COD 核减量 -M 干污泥量 *ρ)*EF CH4 *GWP CH4 (8)

[0101] In the formula, COD 核减量 For the annual COD reduction; M 干污泥量 ρ represents the annual amount of dry sludge present in the plant area; ρ represents the organic matter content in the dry sludge; EF CH4 The CH4 emission factor, TCH4 / TCOD, ranges from 0 to 0.25; GWP CH4 The global warming potential value for CH4 is set to 21.

[0102] COD 核减量 The data is obtained through formula (1) + (3) + (5) in step one, M 干污泥量 The data is obtained through formula (7) in step one, and ρ is obtained through actual measurement of data from the sewage treatment plant.

[0103] ② The annual N2O generated from removing TN from wastewater, converted to carbon dioxide equivalent:

[0104] E TN =TN 核减量 *EF N2O *C N2O / N2 *GWP N2O (9)

[0105] In the formula, TN 核减量 For annual TN reduction; EF N2O The amount of nitrogen that can be converted into nitrous oxide per unit mass of nitrogen in wastewater is represented by a value of 0 for the aerobic zone and 0.005 for the anoxic zone; C N2O / N2 The ratio of N2O / N2 molecular weight is 44 / 28; GWP N2O The global warming potential value for N2O is set to 310.

[0106] TN 核减量 The data is obtained through formula (2) + (4) + (6) in step one;

[0107] ③ The annual emissions of CH4 produced during sludge removal, converted to carbon dioxide equivalent:

[0108] E 污泥 =M 干污泥量 *ρ*DOC f *MCF*F*C CH4 / C *GWP CH4 (10)

[0109] In the formula, M 干污泥量 ρ represents the annual dry sludge volume in the plant area; ρ represents the organic matter content in the dry sludge; DOC f The percentage of biodegradable organic carbon in the dry matter of sludge is 50%; MCF is the CH4 correction factor, with a value of 1 for completely anaerobic conditions and 0 for completely aerobic conditions; F is the proportion of carbon in the biodegradable organic carbon that can produce CH4, with a value of 50%; C CH4 / C The ratio of CH4 to C molecular weight is 16 / 12; GWP CH4 The global warming potential value for CH4 is set to 21.

[0110] M 干污泥量 The data is obtained through formula (7) in step one, and ρ is obtained through actual measurement of data from the sewage treatment plant.

[0111] ④ CO2 emission equivalent generated by the annual electricity consumption of wastewater treatment equipment:

[0112] E 电力 =EH*EF CO2 *GWP CO2 (11)

[0113] In the formula, EH represents the annual power consumption of the plant's wastewater treatment equipment; EF CO2 CO2 emission factor for electricity; GWP CO2The global warming potential for CO2 is set to 1; EH data is obtained from electricity invoices and electricity ledgers of wastewater treatment plants during the accounting period; emission factors are determined by actual measurement or by using recommended emission factor values.

[0114] Table 1 Recommended values ​​for emission factors

[0115] power grid province Emission factors North China Beijing, Tianjin, Hebei, Shanxi, Shandong, and Inner Mongolia Autonomous Region 0.8843 northeast Liaoning Province, Jilin Province, Heilongjiang Province, Inner Mongolia Autonomous Region 0.7769 East China Shanghai, Jiangsu, Zhejiang, Anhui, Fujian 0.7035 Central China Henan Province, Hubei Province, Hunan Province, Jiangxi Province, Sichuan Province, Chongqing Municipality 0.5257 northwest Shaanxi Province, Gansu Province, Qinghai Province, Ningxia Hui Autonomous Region, and Xinjiang Uygur Autonomous Region 0.6671 south Guangdong Province, Guangxi Zhuang Autonomous Region, Yunnan Province, Guizhou Province, and Hainan Province 0.5271

[0116] Step 3, calculation of net greenhouse gas emission reductions, expressed as follows:

[0117] E=E COD +E TN +E 污泥 +E 电力 (12)

[0118] In the formula: E COD The annual emission of CH4 generated from the removal of COD from wastewater, converted to carbon dioxide equivalent; E TN The annual N2O emissions generated from the removal of TN from wastewater, converted to carbon dioxide equivalent; E 污泥 Annual emissions of CH4 generated from sludge removal, converted to carbon dioxide equivalent; E 电力 CO2 emission equivalent generated by the annual electricity consumption of wastewater treatment equipment.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for assessing greenhouse gas emissions from wastewater treatment plant processes, characterized in that, include: Step 1: Calculate the amount of carbon and nitrogen in both liquid and solid states. 1) Determine the process stages of the wastewater treatment plant and the types of pollutants generated, among which, Pretreatment section: coarse screen, lift pump station, fine screen and vortex grit chamber Biochemical treatment section: hydrolysis acidification tank, oxidation ditch, secondary sedimentation tank Advanced treatment section: secondary booster pump station, sedimentation tank, filter, contact tank Pollutant types: methane, chemical oxygen demand, total nitrogen, sludge; 2) Accounting Method Accounting is divided into liquid, solid, and gaseous states. Liquid accounting: Accounting for the reduction of pollutants in influent and effluent. Solid-state accounting: Accounting for the reduction of sludge generated. Gaseous accounting: Calculating the amount of gas produced 3) Accounting process Preprocessing section ① Annual COD reduction: CODE 核减量1 =Q*(CODE 进水 -CODE1)*d*10 -9 (1) In the formula, Q represents the average daily wastewater treatment volume per year; COD 进水 COD1 is the annual average daily influent chemical oxygen demand of the wastewater treatment plant; COD1 is the annual average daily effluent chemical oxygen demand of the vortex grit chamber outlet; d is the number of operating days per year. ②Annual TN reduction: TN 核减量1 =Q*(TN 进水 -TN1)*d*10 -9 (2) In the formula, Q represents the average daily wastewater treatment volume per year; TN 进水 TN1 is the annual average daily influent total nitrogen of the wastewater treatment plant; TN2 is the annual average daily effluent total nitrogen at the vortex grit chamber outlet; d is the number of operating days per year. Biochemical treatment section ① Annual COD reduction COD 核减量2 =(Q*COD1*d+M COD *V-Q*COD2*d)*10 -9 (3) In the formula, Q is the average daily wastewater treatment volume; COD1 is the average daily chemical oxygen demand (COD) at the outlet of the vortex grit chamber; COD2 is the average daily COD at the outlet of the oxidation ditch; M COD The COD equivalent is calculated for different carbon sources; V is the annual carbon source input; d is the number of operating days per year. ② Annual TN reduction TN 核减量2 =(Q*TN1*d+M TN *V-Q*TN2*d)*10 -9 (4) In the formula, Q is the average daily wastewater treatment volume; TN1 is the average daily total nitrogen at the outlet of the vortex grit chamber; TN2 is the average daily total nitrogen at the outlet of the oxidation ditch; M TN The carbon source is introduced, and the value varies depending on the carbon source; V is the annual carbon source addition; d is the number of operating days per year; Deep processing segment ① Annual COD reduction: CODE 核减量3 =Q*(CODE2-CODE) 出水 )*d*10 -9 (5) In the formula, Q is the average daily wastewater treatment volume per year; COD2 is the average daily chemical oxygen demand at the oxidation ditch outlet per year; COD 出水 d represents the average daily chemical oxygen demand (COD) of the wastewater treatment plant; d represents the number of operating days per year. ②Annual TN reduction: TN 核减量3 =Q*(TN2-TN 出水 )*d*10 -9 (6) In the formula, Q is the average daily wastewater treatment volume per year; TN2 is the average daily total nitrogen at the oxidation ditch outlet per year; TN 出水 d represents the average daily total nitrogen in the wastewater effluent from the wastewater treatment plant; d represents the number of operating days per year. ③ The annual amount of dry sludge in the factory area: M 干污泥量 =Q*f*d-a*(1-W 含水率 )*d1 (7) In the formula, Q is the average daily wastewater treatment volume; f is the dry mass of sludge generated daily by the wastewater treatment plant; a is the average daily sludge removal volume; W 含水率 The moisture content varies depending on the sludge removal method, ranging from 60% to 80%; d represents the number of operating days per year; d1 represents the number of sludge removal days. Step two: Estimate greenhouse gas emissions using liquid and solid carbon and nitrogen elements. ① The annual emission of CH4 produced by removing COD from wastewater, converted to carbon dioxide equivalent: AND COD =(COD 核减量 -M 干污泥量 *ρ)*EF CH4 *GWP CH4 (8) In the formula, COD 核减量 For the annual COD reduction; M 干污泥量 ρ represents the annual amount of dry sludge present in the plant area; ρ represents the organic matter content in the dry sludge; EF CH4 The CH4 emission factor, TCH4 / TCOD, ranges from 0 to 0.25; GWP CH4 The global warming potential value for CH4 is set to 21. COD 核减量 The data is obtained through formula (1) + (3) + (5) in step one, M 干污泥量 The data is obtained through formula (7) in step one, and ρ is obtained through actual measurement of data from the sewage treatment plant. ② The annual N2O generated from removing TN from wastewater, converted to carbon dioxide equivalent: E TN =TN 核减量 *EF N2O *C N2O / N2 *GWP N2O (9) In the formula, TN 核减量 For annual TN reduction; EF N2O The amount of nitrogen that can be converted into nitrous oxide per unit mass of nitrogen in wastewater is represented by a value of 0 for the aerobic zone and 0.005 for the anoxic zone; C N2O / N2 The ratio of N2O / N2 molecular weight is 44 / 28; GWP N2O The global warming potential value for N2O is set to 310. TN 核减量 The data is obtained through formula (2) + (4) + (6) in step one; ③ The annual emissions of CH4 produced during sludge removal, converted to carbon dioxide equivalent: AND 污泥 =M 干污泥量 *ρ*DOC f *MCF*F*C CH4 / C *GWP CH4 (10) In the formula, M 干污泥量 ρ represents the annual dry sludge volume in the plant area; ρ represents the organic matter content in the dry sludge; DOC f The percentage of biodegradable organic carbon in the dry matter of sludge is 50%; MCF is the CH4 correction factor, with a value of 1 for completely anaerobic conditions and 0 for completely aerobic conditions; F is the proportion of carbon in the biodegradable organic carbon that can produce CH4, with a value of 50%; C CH4 / C The ratio of CH4 to C molecular weight is 16 / 12; GWP CH4 The global warming potential value for CH4 is set to 21. M 干污泥量 The data is obtained through formula (7) in step one, and ρ is obtained through actual measurement of data from the sewage treatment plant. ④ CO2 emission equivalent generated by the annual electricity consumption of wastewater treatment equipment: ITS 电力 =EH*EF CO2 *GWP CO2 (11) In the formula, EH represents the annual power consumption of the plant's wastewater treatment equipment; EF CO2 CO2 emission factor for electricity; GWP CO2 The global warming potential for CO2 is set to 1; EH data is obtained from electricity invoices and electricity ledgers of wastewater treatment plants during the accounting period; emission factors are determined by actual measurement or by using recommended emission factor values. Step 3, calculation of net greenhouse gas emission reductions, expressed as follows: E=E COD +E TN +E 污泥 +E 电力 (12) In the formula: E COD The annual emission of CH4 generated from the removal of COD from wastewater, converted to carbon dioxide equivalent; E TN The annual N2O emissions generated from the removal of TN from wastewater, converted to carbon dioxide equivalent; E 污泥 Annual emissions of CH4 generated from sludge removal, converted to carbon dioxide equivalent; E 电力 CO2 emission equivalent generated by the annual electricity consumption of wastewater treatment equipment.