Rural household garbage management mode optimization design method based on collection and transportation index and carbon emission

Abstract

The invention discloses a rural household garbage management mode optimization design method based on collection and transportation indexes and carbon emission. The method comprises the following steps: (1) constructing a rural household garbage collection and transportation index evaluation system from four aspects of landform, traffic transportation conditions, garbage characteristics and economic level; (2) calculating a rural household garbage collection and transportation index, and carrying out zoning and spatial correlation analysis on the collection and transportation index; (3) three collection and transportation modes of concentration, dispersion and mixing of the rural household garbage are constructed, the collection and transportation adaptability of the rural household garbage is partitioned, and carbon emission in the collection and transportation process is calculated; (4) calculating the carbon emission based on two-classification or three-classification treatment modes of landfill, incineration, pyrolysis, composting, anaerobic fermentation, comprehensive utilization and the like; and (5) designing a rural household garbage management mode based on the collection and transportation index and the carbon emission, providing an optimal management strategy, reducing secondary pollution and cost, providing a scientific basis for rural household garbage management and carbon emission reduction, and assisting construction of livable and livable and beautiful villages.

Description

[0001] manual Technical Field

[0002] The present invention relates to a rural domestic waste collection and transportation mode comparison design and a carbon emission method, in particular to a rural domestic waste management mode optimization design method based on collection and transportation index and carbon emission. Background Art

[0003] At present, the management of rural domestic waste in my country is relatively weak, with a single model and lack of overall consideration and arrangement. The front-end collection and transportation system of rural domestic waste is still imperfect, the number of collection and transportation facilities lags far behind that of cities, and the population is relatively scattered; the terminal treatment method is random and simple, resulting in high collection and transportation costs, great difficulty in collection and transportation, large accumulation of waste, and low recycling rate of rural domestic waste. The rapid increase in the amount of domestic waste generated will not only cause serious environmental pollution, but also cause a large amount of CO2 to be generated during the collection and transportation and treatment of rural domestic waste. 2 , CH 4 and N 2 Greenhouse gases affect global climate change. According to the World Bank, greenhouse gases emitted during the collection, transportation and treatment of global domestic waste account for 5% of the total global greenhouse gases.

[0004] Therefore, under the background of beautiful countryside construction and dual carbon, it is urgent to establish a scientific and reasonable rural domestic waste optimization management model based on the characteristics of my country's rural areas and achieve carbon emission reduction in the whole process of rural domestic waste management. Summary of the invention

[0005] The purpose of this invention is to construct an evaluation index system for the collection and transportation of rural domestic waste according to factors such as the economic level, population density, topography, and traffic conditions in my country's rural areas, and to evaluate the adaptability of different collection and transportation modes; and based on the carbon emissions of garbage collection and transportation and treatment technology, propose the optimal rural domestic waste management model and strategy suitable for different rural areas in my country, reduce secondary pollution and carbon emissions, provide a scientific basis for rural domestic waste management and carbon emission reduction, and help build livable, business-friendly and beautiful villages.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for optimizing the rural domestic waste management model based on collection and transportation index and carbon emissions, including:

[0008] S1. Construct a rural domestic waste collection and transportation index evaluation system from four aspects: landform, transportation conditions, waste characteristics, and economic level;

[0009] S2. Calculate the rural domestic waste collection and transportation index, and conduct zoning and spatial correlation analysis on the collection and transportation index;

[0010] S3. Based on the rural domestic waste collection and transportation index and spatial correlation analysis, three collection and transportation modes of rural domestic waste, namely centralized, decentralized and mixed, are constructed. The adaptability of rural domestic waste collection and transportation is divided into different zones, and the carbon emissions of the collection and transportation process are calculated.

[0011] S4. Calculate the carbon emissions of the treatment process based on two or three treatment methods such as landfill, incineration, pyrolysis, composting, anaerobic fermentation, and comprehensive utilization;

[0012] S5. Based on the collection and transportation index, and carbon emissions from the entire collection and transportation and treatment process, optimize the design of rural domestic waste management model and propose the optimal management model.

[0013] Furthermore, the method of constructing a rural domestic waste collection and transportation index evaluation index system in step S1 includes:

[0014] S101. Determine six collection and transportation index factors based on landform, transportation conditions, garbage characteristics, and economic level, including altitude, terrain undulation, road network density, straight-line distance from township to city, garbage collection density, and per capita disposable income of rural residents;

[0015] S102. Calculate the subjective weight using entropy weight method, independence weight coefficient method, variation coefficient method, rough set method, discrete coefficient method, negative correlation coefficient method, principal component analysis method, or CRITIC method; calculate the objective weight using Delphi method, analytic hierarchy process, expert survey method, or chain score method; calculate the comprehensive weight W of various index factors of rural domestic waste collection and transportation by combining subjective and objective methods such as multiplication synthesis normalization method, game method, BWM method, or additive combination weighting method. i .

[0016] Furthermore, step S2 calculates the rural domestic waste collection and transportation index, and the method of zoning and spatial correlation analysis of the collection and transportation index includes:

[0017] S201. Construct a dataset of six collection and transportation index factors: altitude, terrain undulation, road network density, straight-line distance from township to city, garbage collection density, and per capita disposable income of rural residents. ij ;

[0018] S202. Use the extreme value method to standardize the data. The formula is as follows:

[0019] Positive indicators:

[0020] Contrarian Indicators:

[0021] Where: X i ' jis the standardized value of the i-th exponential factor of the j-th township; X i is the original data of the exponential factor; X max , X min are the maximum and minimum values ​​under index i;

[0022] S203, use the linear weighted method to calculate the rural domestic waste collection and transportation index (RI)

[0023]

[0024] Where: RI is the collection and transportation index of the ith township; W i is the comprehensive weight of the i-th index factor; X i ' j is the standardized value of the ith indicator in the jth township;

[0025] S204. Using ArcGIS software, the natural breakpoint method is used to zonal the rural domestic waste collection and transportation index;

[0026] S205. Using GeoDa software, Moran's I index was used to conduct spatial autocorrelation analysis on the rural domestic waste collection and transportation index;

[0027] Furthermore, step S205 is spatial autocorrelation analysis, and the specific steps are as follows:

[0028] Global spatial autocorrelation, calculated as follows:

[0029]

[0030] Where: I is the Global Moran's I index; n is the number of towns; ω ij is the spatial weight of township i and j; RI i , RI j is the collection and transportation index of townships i and j; is the mean of all township collection and transportation indexes; S 2 is the sample variance; is the sum of all spatial weights;

[0031] Local spatial autocorrelation, calculated as follows:

[0032]

[0033] Where: I i is the Local Moran's I index of the ith township; n is the number of townships; RI i , RI j is the collection and transportation index of townships i and j; is the mean of all township collection and transportation indexes; ωij is the spatial weight of towns i and j.

[0034] Furthermore, step S3 constructs three collection and transportation modes of rural domestic waste: centralized, decentralized and mixed, divides the adaptability of rural domestic waste collection and transportation into different zones, and calculates the carbon emissions of the collection and transportation process, including:

[0035] S301. Construct centralized, decentralized, and mixed collection and transportation modes. The centralized collection and transportation mode is that rural residents place domestic garbage at designated garbage collection points in villages and towns, and then transport it to town transfer stations, and finally transport it to districts (counties) for treatment by garbage collection and transportation vehicles; the decentralized collection and transportation mode is to classify domestic garbage at the source and divert the process, and rural residents directly classify and collect chaotic and disordered garbage according to its properties. The mixed collection and transportation mode is a mixed mode of centralized and decentralized, including: decentralized-centralized, decentralized-mobile. Among them, the mobile collection and transportation mode is that the responsible entity relies on skid-mounted heat treatment equipment to carry out garbage treatment at a fixed time and point at a temporary storage point;

[0036] S302. Analyze the adaptability of domestic waste collection and transportation in different rural areas, and compare the three collection and transportation modes of rural domestic waste: centralized, decentralized and mixed, as shown in the following table:

[0037]

[0038]

[0039] S303. Using the IPCC guidelines, calculate the carbon emissions of the three collection and transportation modes: centralized, decentralized and mixed. The calculation formula is as follows:

[0040]

[0041] F=l×e×p×n (3-2)

[0042]

[0043] Where: n is the number of vehicles required for domestic waste collection and transportation (vehicles); Q d is the amount of domestic waste removed (t); M rated is the rated load of a single vehicle (t / vehicle); F is the fuel consumption (kg); l is the distance of domestic waste collection and transportation (km); e is the fuel consumption per unit mileage of the vehicle (L / 100km); ρ is the density of the fuel (kg / L); is the carbon emission in the process of domestic waste transportation (kg); N is the calorific value of the fuel (GJ / kg); C is the carbon content per unit calorific value of the fuel (kg / GJ); O is the oxidation factor of the fuel; 44 / 12 is the ratio of carbon dioxide to carbon molecular weight.

[0044] Furthermore, step S4 calculates the carbon emissions of the treatment process based on two or three treatment methods such as landfill, incineration, pyrolysis, composting, anaerobic fermentation, and comprehensive utilization. The specific steps are as follows:

[0045] S401. Based on the three collection and transportation modes of centralized, decentralized and mixed, and the treatment methods of landfill, incineration, pyrolysis, anaerobic fermentation, and aerobic composting, 12 treatment methods are proposed, including method 1 (centralized incineration), method 2 (centralized landfill), method 3 (composting + landfill), method 4 (composting + pyrolysis), method 5 (anaerobic + landfill), method 6 (anaerobic + pyrolysis), method 7 (composting + resource recovery + landfill), method 8 (composting + resource recovery + pyrolysis), method 9 (anaerobic + resource recovery + landfill), method 10 (anaerobic + resource recovery + pyrolysis), method 11 (mobile incineration), and method 12 (mobile pyrolysis);

[0046] S402, carbon emissions from landfill, incineration, and aerobic composting are calculated according to the calculation formula for carbon emissions from waste recommended in Volume 5 of the IPCC Guidelines; carbon emissions from by-product (leachate, slag, fly ash) treatment during incineration, pyrolysis, and anaerobic fermentation are calculated according to the following calculation formula:

[0047] Carbon emissions from by-product treatment during waste incineration:

[0048] E 3 =E sly +E lz +E fh (4-1)

[0049] In the formula, E sly is the carbon emission from leachate treatment during incineration, Gg / yr; E lz is the carbon emission from slag treatment during incineration, Gg / yr; E fh Carbon emissions from fly ash treatment during incineration, Gg / yr;

[0050]

[0051] In the formula, I CH4 CH 4 Carbon emission factor, kgCH 4 / t Trash; I N2O N 2 0 Carbon emission factor, kgN 2 O / t waste; GWP CH4 CH 4 Greenhouse gases global warming potential within 100 years, kgCO 2 / kgCH 4 ; GWP N2O N 2O greenhouse gas global warming potential within 100 years, kg CO 2 / kgN 2 O;

[0052] E lz =MSW·η LZ ·η lz (4-3)

[0053] Where η lz is the slag generation rate, t slag / t garbage; I lz is the slag carbon emission factor, tCO 2 e / t;

[0054] E fh =MSW·η fh I fh (4-4)

[0055] Where η fh is the generation rate of fly ash, tfly ash / twaste; I fh is the fly ash carbon emission factor, tCO 2 e / t;

[0056] Carbon emissions during pyrolysis:

[0057]

[0058] Where G is the total conversion efficiency of the pyrolysis process of domestic waste, which is 0.85; the values ​​of other parameters are the same as those of incineration;

[0059] Carbon emissions during anaerobic fermentation:

[0060]

[0061] Where: E a is the carbon emission from anaerobic fermentation of food waste (t); MSW a is the mass of anaerobic fermentation of kitchen waste (t); MCF a is the methane correction factor for anaerobic fermentation; DOC a DOC is the degradable organic carbon content in kitchen waste (%); fa is the proportion of DOC degraded in food waste (%); F a is the proportion of methane in biogas (%); EF leak is the leakage rate of methane in biogas (%);

[0062] S403. The calculation formulas for carbon storage during landfill treatment by incineration of landfill gas for power generation, carbon storage during incineration by replacing fossil fuels for thermal power generation, carbon storage during aerobic composting, carbon storage during anaerobic fermentation, and carbon storage during the utilization of recyclable waste resources are as follows:

[0063] Carbon storage from landfill gas incineration for electricity generation:

[0064]

[0065] Where: E cs-ladfill is the carbon storage from landfill gas power generation (t); It is landfill 4 Recycling volume (t); Yes CH 4 Calorific value (kJ / kg); η 1 Yes CH 4 Power generation efficiency (%); ξ L EF is the landfill's self-consumption rate (%); e is the carbon emission factor of electricity (tCO 2 / MWh);

[0066] Carbon storage during incineration treatment when incineration power generation replaces fossil fuels for thermal power generation:

[0067]

[0068] Where: E cs-Incinerate is the carbon storage generated by incineration for power generation (t); MSW I is the amount of rural domestic waste incineration (t); LHV I is the lower calorific value of domestic waste (kJ / kg); η 2 is the thermal efficiency of the incineration system (%); ξ I is the rate of self-use electricity of the incineration site (%);

[0069] Carbon storage during aerobic composting:

[0070] E cs-compost =MSW c ×EF cs-c (4-9)

[0071] Where: E cs-compost is the carbon storage of compost products (t); MSW c is the amount of kitchen waste compost (t); EF cs-compos is the carbon reduction factor of the compost product;

[0072] Carbon storage during anaerobic digestion:

[0073]

[0074] Where: E cs-biogas is the carbon storage of anaerobic fermentation biogas (t); It is anaerobic fermentation CH 4 The mass recovered (t); ξ C is the self-consumption rate of electricity in anaerobic fermentation (%);

[0075] Carbon storage from recyclable waste resources:

[0076]

[0077] Where: E rec is the amount of recycled carbon storage (t); M i is the mass of recyclable component i (t); EF i is the carbon reduction factor of recyclable component i;

[0078] S404. Calculate the net carbon emissions of 12 different treatment methods, that is, the difference between the carbon emissions and carbon storage generated during the treatment process.

[0079] Furthermore, step S5 is a method for optimizing the rural domestic waste management model based on the collection and transportation index and carbon emissions, including:

[0080] S501. Calculate the carbon emissions during the collection and transportation process and the treatment process of rural domestic waste under different modes, that is, the sum of the carbon emissions during the collection and transportation process and the net carbon emissions during the treatment process;

[0081] S502. Based on the collection and transportation index and carbon emissions, the management model of rural domestic waste is optimized according to the principles in the following table, as shown in the following table:

[0082]

[0083] BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 Flowchart of comprehensive weight calculation of indicator factors

[0085] Figure 2 Altitude and terrain relief data processing flow

[0086] Figure 3 Town road network density data processing flow

[0087] Figure 4 Data processing flow of the straight-line distance from township to Chengguan town

[0088] Figure 5 Schematic diagram of the results of the altitude of towns in my country provided by the present invention as an implementation case

[0089] Figure 6 Schematic diagram of the topographic undulation results of the town area in my country provided by the present invention as an implementation case

[0090] Figure 7 Schematic diagram of the road network density results of the town area in my country provided by the present invention as an implementation case

[0091] Figure 8 A schematic diagram of the straight-line distance results from a township to a city in my country provided by the present invention as an implementation case

[0092] Fig. 9 Schematic diagram of the results of per capita disposable income of rural residents in my country provided by the present invention as an implementation case

[0093] Fig.10 Schematic diagram of the collection density of rural domestic garbage in towns in my country provided by the present invention as an implementation case

[0094] Fig.11 Schematic diagram of the results of the Lisa clustering of the rural domestic garbage collection and transportation index provided by the present invention as an implementation case

[0095] Fig.12 Schematic diagram of the carbon emission distribution results of the centralized collection and transportation mode of rural domestic waste in counties in my country provided by the present invention as an implementation case

[0096] Fig.13 Schematic diagram of the carbon emission results of the decentralized collection and transportation of recyclable garbage provided by the present invention as an implementation case

[0097] Fig.14 Schematic diagram of carbon emissions, carbon storage and net carbon emission rate results during the centralized landfill treatment of rural domestic waste in my country's provinces provided by the present invention as an implementation case

[0098] Fig.15 Schematic diagram of carbon emissions, carbon storage and net carbon emission rate results during the centralized incineration of rural domestic waste in my country's provinces provided by the present invention as an implementation case DETAILED DESCRIPTION

[0099] The present invention is further described below in conjunction with specific embodiments to help understand the content of the present invention. It is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0100] The embodiment of the present invention discloses a method for optimizing the rural domestic waste management mode based on the collection and transportation index and carbon emissions, comprising the following steps:

[0101] S1. According to Figure 1The evaluation index system of rural domestic waste collection and transportation index is constructed from four aspects: landform, transportation conditions, waste characteristics, and economic level. The specific steps are as follows:

[0102] S101, from the four aspects of landform, transportation conditions, and economic level, six collection and transportation index factors were determined, namely, altitude, terrain undulation, road network density, straight-line distance from township to city, garbage collection density, and per capita disposable income of rural residents;

[0103] Table 1 Evaluation system of rural domestic waste collection and transportation index

[0104]

[0105] S102. Determine the subjective weight using the analytic hierarchy process (AHP) and the objective weight using the independent weight coefficient method. Calculate the comprehensive weight W of the rural domestic waste collection and transportation index by using the multiplication synthesis normalization method. i , the results are shown in Table 2.

[0106] Table 2 Weight values ​​of rural domestic waste collection and transportation index factors

[0107]

[0108] S2. Calculate the rural domestic waste collection and transportation index, and divide the collection and transportation index into different areas and perform spatial correlation analysis. The specific steps are as follows;

[0109] S201. Construct a dataset of six collection and transportation index factors: altitude, terrain undulation, road network density, straight-line distance from township to city, garbage collection density, and per capita disposable income of rural residents. ij :

[0110] according to Figure 2 The steps are as follows. Using ArcGIS software, 30M resolution digital elevation data across the country, and the administrative boundaries of towns and villages, the average elevation of the town area and the maximum and minimum elevation of the town area are calculated. The average elevation of the town is used as the altitude of the town, and the difference between the maximum and minimum values ​​is used as the terrain undulation of the town. The results are as follows Figure 5 , Figure 6 As shown;

[0111] according to Figure 3 The steps were followed. Using ArcGIS software, 1:250,000 road network data (including national roads, provincial roads, county roads, township roads, etc.), and township administrative boundaries, the area of ​​each township was obtained through the calculation of geometric area tools and the town road network density was calculated. The results are as follows Figure 7 ;

[0112] The collection and transportation distance is simplified to the straight-line distance from the township to the Chengguan Town where the county government is located. Figure 4The steps were followed to use ArcGIS software to measure the straight-line distances between all towns in the county and Chengguan Town. The results are as follows: Figure 8 As shown;

[0113] The per capita disposable income of rural residents is from the 2021 Statistical Yearbook of each city (county). The results are as follows: Fig. 9 ;

[0114] Garbage collection density (i.e. per unit land area km 2 The collection and transportation quality of garbage on the road t). The per capita garbage production of rural domestic garbage is derived from the field survey data of 580 farmers in 18 counties, 59 villages in 6 western provinces and the statistical analysis of literature data of 31 provinces (cities) across the country as of 2022 (a total of 593 samples), and the administrative area and registered population of townships are derived from the "China County Statistical Yearbook 2021 (Township Volume)". Considering that rural areas refer to the administrative management areas under the jurisdiction of townships (except Chengguan Town), and the administrative village management areas under the jurisdiction of Chengguan Town, they are excluded; at the same time, townships with uncounted people and townships without road network density in the yearbook are excluded. Finally, a total of 28,264 townships were screened out, and the 28,264 townships with calculated garbage density were spatially associated with the administrative division map of the township boundary using ArcGIS software, and Kriging interpolation was performed to draw the rural domestic garbage collection density map of the town, as shown in the figure. Fig.10 .

[0115] S202, using extreme value method to standardize the data;

[0116] S203, using a linear weighted method to calculate the rural domestic waste collection and transportation index (RI);

[0117] S204. Using ArcGIS software, the 28,264 towns were divided into five levels using the natural breakpoint method: high index (0.80-0.55), relatively high index (0.54-0.47), medium index (0.46-0.43), relatively low index (0.42-0.39), and low index (0.38-0.11);

[0118] S205. Using GeoDa software, we selected Moran's I index to conduct spatial autocorrelation analysis on the rural domestic waste collection and transportation index. For global autocorrelation, we selected Queen spatial adjacency matrix, and obtained the Global Moran's I index of rural domestic waste collection and transportation adaptability of 28,264 towns, which was 0.936, approaching 1, indicating that the adaptability of rural domestic waste collection and transportation in my country is positively correlated in space, and the spatial aggregation effect is significant, that is, it has an assimilation effect on the surrounding areas; for local autocorrelation, we calculated the Local Moran's I index and drew the Lisa aggregation map, and intuitively analyzed the spatial aggregation type and range within the adaptability of rural domestic waste collection and transportation in my country. The results are as follows: Fig.11 shown.

[0119] S3. Based on the rural domestic waste collection and transportation index and spatial correlation analysis, three collection and transportation modes of rural domestic waste, namely centralized, decentralized and mixed, are constructed. The adaptability of rural domestic waste collection and transportation is divided into different zones, and the carbon emissions of the collection and transportation process are calculated, including:

[0120] S301. Construct centralized, decentralized, and mixed collection and transportation modes. The centralized collection and transportation mode is that rural residents place domestic garbage at designated garbage collection points in villages and towns, and then transport it to town transfer stations, and finally transport it to districts (counties) for treatment by garbage collection and transportation vehicles; the decentralized collection and transportation mode is to classify domestic garbage at the source and divert the process, and rural residents directly classify and collect chaotic and disordered garbage according to its properties. The mixed collection and transportation mode is a mixed mode of centralized and decentralized, including: decentralized-centralized, decentralized-mobile. Among them, the mobile collection and transportation mode is that the responsible entity relies on skid-mounted heat treatment equipment to carry out garbage treatment at a fixed time and point at a temporary storage point;

[0121] S302. Based on the rural domestic waste collection and transportation index and spatial correlation analysis, the adaptability of domestic waste collection and transportation in rural areas of the province is analyzed, and three collection and transportation modes of rural domestic waste, namely, centralized, decentralized and mixed, are selected, as shown in Table 3;

[0122] Table 3 Analysis of adaptability of rural domestic waste collection and transportation modes

[0123]

[0124] S303. Using the IPCC guidelines, calculate the carbon emissions of the three collection and transportation modes: centralized, decentralized and mixed. The specific operations are as follows:

[0125] (1) Under centralized collection and transportation mode:

[0126] A self-loading garbage compactor with a rated load of 8t is selected. Its maximum gross mass is 18t, its empty mass is about 10t, its fuel type is diesel, and its exhaust emissions can meet the standards of "Emission Limits and Measurement Methods of Pollutants for Heavy-Duty Diesel Vehicles (China Phase VI)" (GB 17691-2018). The fuel value of garbage collection and transportation vehicles refers to the fuel consumption of dump trucks in the "Limits of Fuel Consumption for Heavy-Duty Commercial Vehicles" (GB 30510-2018). The relevant parameter values ​​are shown in Table 4.

[0127] All rural domestic waste is transported to the district (county) for treatment. The amount of waste collected and transported is derived from the per capita waste production and rural population in the collection characteristic conditions. The transportation distance of the centralized collection and transportation mode is simplified to the straight-line distance from the township to the town, which is the straight-line distance from the township to the town in the transportation condition. The calculation results are as follows: Fig.12 As shown;

[0128] Table 4 Carbon emission calculation parameters for centralized collection and transportation of rural domestic waste

[0129]

[0130] (2) Under decentralized collection and transportation mode:

[0131] Rural domestic waste is treated by two-classification and three-classification. The two-classification is divided into kitchen waste and other categories. It does not involve the resource utilization of recyclable waste. Rural domestic waste is treated on-site in towns and villages. The collection and transportation distance between towns is zero, and the carbon emissions generated in the collection and transportation stage are zero; the three-classification is divided into recyclable waste, kitchen waste and other waste. Usually, kitchen waste and other waste are treated on-site in a decentralized manner, and recyclable waste with utilization value is transported from villages and towns to districts (counties) for recycling resources through a centralized collection and transportation mode. The garbage components in various provinces in my country are derived from the mathematical statistics of literature surveys (2004-2022) (a total of 399 samples), see Table 5. The number of transport vehicles and transportation distances of recyclable components under the decentralized collection and transportation mode are the same as those in the centralized mode. The calculation results are as follows Fig.13 shown.

[0132] Table 5 Characteristics of rural domestic waste components (unit: %)

[0133]

[0134]

[0135] S4. Calculate the carbon emissions from the treatment process in two or three categories, including landfill, incineration, pyrolysis, composting, anaerobic fermentation, and comprehensive utilization, including:

[0136] S401. Based on the three collection and transportation modes of centralized, decentralized and mixed, and the treatment methods of landfill, incineration, pyrolysis, anaerobic fermentation, and aerobic composting, 12 treatment methods are proposed, including method 1 (centralized incineration), method 2 (centralized landfill), method 3 (composting + landfill), method 4 (composting + pyrolysis), method 5 (anaerobic + landfill), method 6 (anaerobic + pyrolysis), method 7 (composting + resource recovery + landfill), method 8 (composting + resource recovery + pyrolysis), method 9 (anaerobic + resource recovery + landfill), method 10 (anaerobic + resource recovery + pyrolysis), method 11 (mobile incineration), and method 12 (mobile pyrolysis);

[0137] S402. In order to compare the carbon emissions under different treatment methods of rural domestic waste in my country, the carbon emission rate is used for analysis, that is, the carbon emissions per unit mass of domestic waste (tMSW) (tCO 2 e) In the study of greenhouse gas emissions, for the convenience of statistics and comparison, it is customary internationally to convert different greenhouse gases into CO according to their 100-year global warming potential. 2 The greenhouse effect is multiplied by CO2 carbon dioxide equivalent,CO 2 e), and referred to as carbon emissions. According to the IPCC report, CH 4 The GWP of CO 2 28 times, N 2 The GWP of O is CO 2 265 times;

[0138] The carbon emissions of the entire chain of rural domestic waste disposal include carbon emissions and carbon storage generated during the waste treatment process. The specific operations are as follows:

[0139] (1) Carbon emissions from landfill treatment were calculated using the mass balance method specified by the IPCC. The moisture content of rural domestic waste in my country is shown in Table 6, and the values ​​of related parameters are shown in Tables 7 and 8.

[0140] Table 6 Statistics of moisture content and calorific value of domestic garbage in rural areas of my country

[0141]

[0142]

[0143] Table 7 Chemical properties of typical components of rural domestic waste in my country

[0144]

[0145] Table 8 Calculation coefficients of carbon emissions in rural domestic waste treatment

[0146]

[0147] (2) During incineration, carbon in domestic waste is oxidized, producing greenhouse gas CO 2 ; The CO generated during the incineration of rubber, plastic, textile and paper components containing mineral carbon 2 It is considered as a net emission and included in greenhouse gas emissions; CO2 produced by food waste, wood and bamboo containing biochar is 2 It is only used as a reference value and is not included in the greenhouse gas emission inventory. At present, most of my country's incineration plants use grate furnaces, which do not require the addition of combustion aids during normal operation. Only a small amount of fossil fuels need to be added during ignition; therefore, the carbon emissions generated by the addition of combustion aids are not considered;

[0148] (3) Calculate carbon emissions from incineration according to the emission factor method in the IPCC guidelines. The calorific value of rural domestic waste in my country is shown in Table 6, and the values ​​of related parameters are shown in Tables 7 and 8;

[0149] (4) Calculate the carbon emissions from the by-product (leachate, slag, fly ash) treatment stage during the waste incineration process according to formulas (4-1), (4-2), (4-3), and (4-4) (the following formula numbers are all referenced to the formula numbers in the patent specification). The relevant parameter values ​​are shown in Table 8;

[0150] (5) Calculate the carbon emissions during pyrolysis according to formula (4-5), where the calorific value of rural domestic waste in my country is shown in Table 6, and the values ​​of related parameters are shown in Tables 7 and 8;

[0151] (6) Carbon emissions from aerobic composting were calculated according to the default value method in the IPCC guidelines. The relevant parameter values ​​are shown in Tables 7 and 8;

[0152] (7) Calculate the carbon emissions during anaerobic fermentation according to formula (4-6). The relevant parameter values ​​are shown in Table 7 and Table 8;

[0153] (8) Carbon storage during landfill treatment:

[0154] CH generated by rural domestic waste landfill treatment 4 After being collected, it is used for power generation, and CH 4 The collection rate is 50%; the dispersed treatment method CH 4 The collection rate is 0, and methane recovery power generation is not considered. The carbon storage generated by the net power generation of landfill gas minus the power consumption of the landfill itself is calculated by formula (4-7); the carbon emission factor of electricity is shown in Table 9, among which the default value of the electricity emission factor in Tibet is taken from the Northwest Regional Power Grid, and the values ​​of other parameters are shown in Table 10;

[0155] Table 9 Carbon emission factors of regional electricity in my country

[0156]

[0157] Table 10 Carbon storage calculation coefficients in rural domestic waste treatment

[0158]

[0159]

[0160] (9) Carbon storage during incineration:

[0161] The carbon storage generated by the net electricity generated by the waste incineration plant after deducting the self-used electricity is calculated by formula (4-8). The relevant parameter values ​​are shown in Table 10;

[0162] (10) Carbon storage during pyrolysis:

[0163] When pyrolysis of domestic waste is carried out in rural areas, the product reuse and energy recovery are relatively small, so the carbon storage brought by the recovery of waste heat to produce electricity during the pyrolysis process is not considered;

[0164] (11) Carbon storage during aerobic composting:

[0165] The carbon storage generated by compost products is calculated by formula (4-9), and the relevant parameter values ​​are shown in Table 10;

[0166] (12) Carbon storage during anaerobic fermentation:

[0167] The anaerobic fermentation process of kitchen waste is calculated by formula (4-10) after deducting the self-generated electricity consumption, CH 4 Carbon storage generated by power generation, the relevant parameter values ​​are shown in Table 10;

[0168] (13) Carbon storage using recyclable waste resources:

[0169] The main recyclable components include plastics, paper, glass, textiles and metals. The carbon storage achieved by the resource utilization of recyclable waste is calculated by formula (4-11). The relevant parameter values ​​are shown in Table 10.

[0170] S403. Calculate the net carbon emissions of different treatment methods, that is, the difference between carbon emissions and carbon storage generated during the treatment process:

[0171] The calculation results of carbon emissions, carbon storage and net carbon emission rates in the process of rural domestic waste collection and treatment in my country are as follows: Fig.14 , Fig.15 ; The calculation results of carbon emissions, carbon storage and net carbon emission rate in the decentralized treatment process are shown in Table 11.

[0172] Table 11 Carbon emissions, carbon storage and net carbon emission rates in the decentralized treatment of rural domestic waste in my country's provinces (unit: tCO2e / tMSW)

[0173]

[0174]

[0175]

[0176]

[0177] S5. Based on the collection and transportation index and carbon emissions, the rural domestic waste management model is optimized and designed. There are 2,411 counties in my country that are suitable for the decentralized management model of anaerobic + pyrolysis + resource utilization; 201 counties are suitable for the centralized incineration management model; and only 5 counties are suitable for the decentralized management model of anaerobic + pyrolysis, see Table 12.

[0178] Table 12 Analysis of adaptability of rural domestic waste management models in my country's counties

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[0180]

Claims

1. A method for optimizing the management mode of rural domestic waste based on collection and transportation index and carbon emissions, the steps are as follows: (1) Construct a rural domestic waste collection and transportation index evaluation system based on four aspects: landform, transportation conditions, waste characteristics, and economic level; (2) Calculate the rural domestic waste collection and transportation index, divide the collection and transportation index into different regions, and analyze the spatial correlation; (3) Based on the rural domestic waste collection and transportation index and spatial correlation analysis, three rural domestic waste collection and transportation modes, namely centralized, decentralized and mixed, were constructed. The adaptability of rural domestic waste collection and transportation was divided into different regions, and the carbon emissions of the collection and transportation process were calculated. (4) Calculate the carbon emissions of the treatment process based on two or three treatment methods such as landfill, incineration, pyrolysis, composting, anaerobic fermentation, and comprehensive utilization; (5) Based on the collection and transportation index and carbon emissions from the entire collection, transportation and treatment process, the rural domestic waste management model is optimized and the optimal management model is proposed.

2. The method for optimizing the rural domestic waste management model based on the collection and transportation index and carbon emissions according to claim 1, characterized in that: In step (1), the method for constructing a rural domestic waste collection and transportation index evaluation system is as follows: (2-1) From the four aspects of landform, transportation conditions, garbage characteristics, and economic level, six collection and transportation index factors were determined, including altitude, terrain undulation, road network density, straight-line distance from township to city, garbage collection density, and per capita disposable income of rural residents; (2-2) The subjective weight is calculated by using entropy weight method, independence weight coefficient method, variation coefficient method, rough set method, discrete coefficient method, negative correlation coefficient method, principal component analysis method or CRITIC method; the objective weight is calculated by using Delphi method, hierarchical analysis method, expert survey method or chain score method; the comprehensive weight W of various index factors of rural domestic waste collection and transportation is calculated by using a combination of subjective and objective methods such as multiplication synthesis normalization method, game method, BWM method or additive combination weighting method. i .

3. The method for optimizing the rural domestic waste management model based on collection and transportation index and carbon emissions according to claim 1, characterized in that: In step (2), the rural domestic waste collection and transportation index is calculated, and the method for zoning and spatial correlation analysis of the collection and transportation index is as follows: (3-1) Construct a dataset X of six collection and transportation index factors: altitude, terrain undulation, road network density, straight-line distance from township to city, garbage collection density, and per capita disposable income of rural residents. ij ; (3-2) The extreme value method is used to standardize the data. The formula is as follows: Positive indicators: Contrarian Indicators: Where: X i ' j is the standardized value of the i-th exponential factor of the j-th township; X i is the original data of the exponential factor; X max , X min are the maximum and minimum values ​​under index i; (3-3) Calculate the rural domestic waste collection and transportation index (RI) using the linear weighted method Where: RI is the collection and transportation index of the ith township; W i is the comprehensive weight of the i-th index factor; X' ij is the standardized value of the ith indicator in the jth township; (3-4) Using ArcGIS software, the natural breakpoint method was used to zonal the rural domestic waste collection and transportation index; (3-5) Using GeoDa software, Moran's I index was used to conduct spatial autocorrelation analysis on the rural domestic waste collection and transportation index. The steps are as follows: First, calculate the global spatial autocorrelation, the calculation formula is as follows: Where: I is the Global Moran's I index; n is the number of towns; ω ij is the spatial weight of township i and j; RI i , RI j is the collection and transportation index of townships i and j; is the mean of all township collection and transportation indexes; S 2 is the sample variance; is the sum of all spatial weights; Secondly, calculate the local spatial autocorrelation, the calculation formula is as follows: Where: I i is the Local Moran's I index of the ith township; n is the number of townships; RI i , RI j is the collection and transportation index of townships i and j; is the mean of all township collection and transportation indexes; ω ij is the spatial weight of towns i and j.

4. The method for optimizing the rural domestic waste management model based on the collection and transportation index and carbon emissions according to claim 1, characterized in that: In step (3), three collection and transportation modes of rural domestic waste, namely centralized, decentralized and mixed, are constructed, the adaptability of rural domestic waste collection and transportation is divided into different zones, and the carbon emissions of the collection and transportation process are calculated, including: (4-1) Establish centralized, decentralized, and mixed collection and transportation modes. The centralized collection and transportation mode is that rural residents place domestic waste at designated waste collection points in villages and towns, and then transport it to town transfer stations, and finally transport it to districts (counties) for treatment by waste collection and transportation vehicles; the decentralized collection and transportation mode is to classify domestic waste at the source and divert the process, and rural residents directly classify and collect chaotic and disordered waste according to its properties. The mixed collection and transportation mode is a mixed mode of centralized and decentralized, including: decentralized-centralized, decentralized-mobile. Among them, the mobile collection and transportation mode is that the responsible entity relies on skid-mounted heat treatment equipment to carry out garbage treatment at a fixed time and point at a temporary storage point; (4-2) Analyze the adaptability of domestic waste collection and transportation in different rural areas, and compare the three collection and transportation modes of rural domestic waste: centralized, decentralized and mixed, as shown in the following table: (4-3) The 2006 IPCC Guidelines for National Greenhouse Gas Inventories (hereinafter referred to as the IPCC Guidelines) are used to calculate the carbon emissions from the collection and transportation process of the three collection and transportation modes: centralized, decentralized and mixed. The calculation formula is as follows: F=l×e×p×n (4-2) Where: n is the number of vehicles required for domestic waste collection and transportation (vehicles); Q d is the amount of domestic waste removed (t); M rated is the rated load of a single vehicle (t / vehicle); F is the fuel consumption (kg); l is the distance of domestic waste collection and transportation (km); e is the fuel consumption per unit mileage of the vehicle (L / 100km); ρ is the density of the fuel (kg / L); is the carbon emission in the process of domestic waste transportation (kg); N is the calorific value of the fuel (GJ / kg); C is the carbon content per unit calorific value of the fuel (kg / GJ); O is the oxidation factor of the fuel; 44 / 12 is the ratio of carbon dioxide to carbon molecular weight.

5. The method for optimizing the rural domestic waste management model based on the collection and transportation index and carbon emissions according to claim 1, characterized in that: In step (4), the carbon emissions of the treatment process are calculated based on two or three treatment methods, such as landfill, incineration, pyrolysis, composting, anaerobic fermentation, and comprehensive utilization; (5-1) Based on the three collection and transportation modes of centralized, decentralized and mixed, and the treatment methods of landfill, incineration, pyrolysis, anaerobic fermentation, and aerobic composting, 12 treatment methods are proposed, including method 1 (centralized incineration), method 2 (centralized landfill), method 3 (composting + landfill), method 4 (composting + pyrolysis), method 5 (anaerobic + landfill), method 6 (anaerobic + pyrolysis), method 7 (composting + resource recovery + landfill), method 8 (composting + resource recovery + pyrolysis), method 9 (anaerobic + resource recovery + landfill), method 10 (anaerobic + resource recovery + pyrolysis), method 11 (mobile incineration), and method 12 (mobile pyrolysis); (5-2) Carbon emissions from landfill, incineration and aerobic composting are calculated according to the carbon emission calculation formula for waste recommended in Volume 5 of the IPCC Guidelines; carbon emissions from by-product (leachate, slag, fly ash) treatment during incineration, pyrolysis and anaerobic fermentation are calculated according to the following calculation formula: Carbon emissions from by-product treatment during waste incineration: E3=E sly +E lz +E fh (5-1) In the formula, E sly is the carbon emission from leachate treatment during incineration, Gg / yr; E lz is the carbon emission from slag treatment during incineration, Gg / yr; E fh Carbon emissions from fly ash treatment during incineration, Gg / yr; In the formula, I CH4 is the CH4 carbon emission factor, kgCH4 / t garbage; I N2O is the N2O carbon emission factor, kgN2O / t waste; GWP CH4 The global warming potential of CH4 greenhouse gas within 100 years, kg CO2 / kgCH4; GWP N2O The global warming potential of N2O greenhouse gas within 100 years, kgCO2 / kgN2O; E lz =MSW·η lz ·AND l from (5-3) Where η lz is the slag generation rate, t slag / t garbage; I lz is the emission factor of slag carbon emissions, tCO2e / t; THAT fh =MSW·η fh ·I fh (5-4) Where η fh is the generation rate of fly ash, tfly ash / twaste; I fh is the fly ash carbon emission factor, tCO2e / t; Carbon emissions during pyrolysis: Where G is the total conversion efficiency of the pyrolysis process of domestic waste, which is 0.85; the values ​​of other parameters are the same as those of incineration; Carbon emissions during anaerobic fermentation: Where: E a is the carbon emission from anaerobic fermentation of food waste (t); MSW a is the mass of anaerobic fermentation of kitchen waste (t); MCF a is the methane correction factor for anaerobic fermentation; DOC a DOC is the degradable organic carbon content in kitchen waste (%); fa is the proportion of DOC degraded in food waste (%); F a is the proportion of methane in biogas (%); EF leak is the leakage rate of methane in biogas (%); (5-3) The calculation formulas for carbon storage during landfill treatment by incineration of landfill gas for power generation, carbon storage during incineration by replacing fossil fuels for thermal power generation, carbon storage during aerobic composting, carbon storage during anaerobic fermentation, and carbon storage during the utilization of recyclable waste resources are as follows: Carbon storage from landfill gas incineration for electricity generation: Where: E cs-ladfill is the carbon storage from landfill gas power generation (t); is the amount of CH4 recovered from landfill (t); is the calorific value of CH4 (kJ / kg); η1 is the power generation efficiency of CH4 (%); ξ L EF is the landfill's self-consumption rate (%); e is the carbon emission factor of electricity (tCO2 / MWh); Carbon storage during incineration treatment when incineration power generation replaces fossil fuels for thermal power generation: Where: E cs-Incinerate is the carbon storage generated by incineration for power generation (t); MSW I is the amount of rural domestic waste incineration (t); LHV I is the lower calorific value of domestic waste (kJ / kg); η2 is the thermal efficiency of the incineration system (%); ξ I is the rate of self-use electricity of the incineration site (%); Carbon storage during aerobic composting: <h2 style=";text-align:left;direction:ltr">E<h2 style=";text-align:left;direction:ltr"> cs-compost <h2 style=";text-align:left;direction:ltr"> (MSW)<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> ×EF<h2 style=";text-align:left;direction:ltr"> cs-c <h2 style=";text-align:left;direction:ltr"> (5-9) Where: E cs-compost is the carbon storage of compost products (t); MSW c is the amount of food waste compost (t); EF cs-compos is the carbon reduction factor of the compost product; Carbon storage during anaerobic digestion: Where: E cs-biogas is the carbon storage of anaerobic fermentation biogas (t); is the mass of CH4 recovered from anaerobic fermentation (t); ξ C is the self-consumption rate of electricity in anaerobic fermentation (%); Carbon storage from recyclable waste resources: Where: E rec is the amount of recycled carbon storage (t); M i is the mass of recyclable component i (t); EF i is the carbon reduction factor of recyclable component i; (5-4) Calculate the net carbon emissions of the 12 different treatment methods in (5-1), that is, the difference between the carbon emissions generated during the treatment process and the carbon storage.

6. The method for optimizing the rural domestic waste management model based on collection and transportation index and carbon emissions according to claim 1, characterized in that: The method for optimizing the rural domestic waste management model based on the collection and transportation index and carbon emissions in step (5) includes: (6-1) Calculate the carbon emissions from the collection and transportation process and the treatment process of rural domestic waste under different modes, that is, the sum of the carbon emissions from the collection and transportation process and the net carbon emissions from the treatment process; (6-2) Based on the collection and transportation index and carbon emission calculation results, the management model of rural domestic waste (5-1) is optimized according to the principles in the following table, as shown in the following table:

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