## 2 Materials and Methods
### Estimation Method  
#### 2.4.1 GHG Emissions from Transportation  
In the MSW transportation process, the main source of GHG emissions is consumption of diesel fuel. In addition, because of the large number of harmful substances in automobile exhaust, (including CO, nitrogen oxides, hydrocarbons, and solid suspended particles), the vehicle is equipped with an exhaust purification device, which uses catalysts to convert CO, nitrogen oxides, and hydrocarbons in exhaust into non-toxic and harmless CO\({}_{2}\), H\({}_{2}\)O, and N\({}_{2}\) and thus control the emission quality of exhaust. Therefore, GHG emissions will also be produced in the exhaust disposal process. According to the guidance given by the IPCC and in combination with the _Guidelines for Calculation and Reporting of GHG Emissions from Land Transportation Enterprises of China_, the calculation of GHG emissions from vehicles is as follows:  
\[E_{t}=E_{d}+E_{u} \tag{1}\]  
where \(E_{t}\) is the GHG emissions during transportation, \(E_{d}\) is the GHG emissions caused by fuel consumption of vehicles, and \(E_{u}\) is the GHG emissions in the exhaust-purification process. \(E_{d}\) is estimated via the following equation:  
\[E_{d}=E_{\text{CO}_{2}}^{d}+E_{\text{CH}_{4}}^{d}+E_{N_{2}O}^{d} \tag{2}\]  
where \(E_{\text{CO}_{2}}^{d}\) is the CO\({}_{2}\) emissions caused by fossil fuel consumption during transportation, \(E_{\text{CH}_{4}}^{d}\) is the CH\({}_{4}\) emissions caused by fossil fuel consumption during transportation, and \(E_{N_{2}O}^{d}\) is the N\({}_{2}\)O emissions caused by fossil fuel consumption during transportation. They were calculated as follows:  
\[E_{\text{CO}_{2}}^{d}=FC_{d}*\kappa_{d}*CC_{d}*OF_{d}*\frac{44}{12} \tag{3}\]  
\[E_{\text{CH}_{4}}^{d}=d*EF_{\text{CH}_{4}}^{d}*GWP_{\text{CH}_{4}}*10^{-9} \tag{4}\]  
\[E_{N_{2}O}^{d}=d*EF_{N_{2}O}^{d}*GWP_{N_{2}O}*10^{-9} \tag{5}\]  
where \(FC_{d}\) is the amount of diesel consumption, \(\kappa_{d}\) is the low heating value of diesel with the typical value of 42.652 \(G\)/\(t\)[57], \(CC_{d}\) is the carbon content per unit heating value of diesel, and \(OF_{d}\) is the oxidation factor of diesel consumption. The recommended values were shown in Beijing local standard DB11/T 1416-2017 [53]. In the Equations (4) and (5), \(d\) is the driving distance of a vehicle, \(EF\) is the CH\({}_{4}\) (or N\({}_{2}\)O) emission factor of a certain type of fuel consumed by a given vehicle type under given emission standards, which typical values could be found in the _Guidelines for Calculation and Reporting \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Waste Composition** & **Scenario 1** & **Scenario 2** & **Scenario 3** & **Scenario 4** & **Scenario 5** \\ \hline Kitchen waste (\%) & 47.85 & 31.45 & 31.45 & 44.80 & 44.80 \\ Ash and brick (\%) & 3.48 & 4.57 & 4.57 & 6.52 & 6.52 \\ Wood (\%) & 3.33 & 4.38 & 4.38 & 6.24 & 6.24 \\ Paper (\%) & 20.83 & 27.38 & 27.38 & 19.50 & 19.50 \\ Textile (\%) & 2.34 & 3.08 & 3.08 & 2.19 & 2.19 \\ Plastics (\%) & 20.74 & 27.26 & 27.26 & 19.42 & 19.42 \\ Glass (\%) & 1.23 & 1.62 & 1.62 & 1.15 & 1.15 \\ Metal (\%) & 0.2 & 0.26 & 0.26 & 0.19 & 0.19 \\ \hline Heat value on dry basis (_M_//_) & 9407 & 10952 & 10952 & 9427 & 9427 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Waste component and heat value of residual mixed waste in five scenarios. of GHG Emissions from Land Transportation Enterprises of China. GWP is the global warming potential of CH\({}_{4}\) (or N\({}_{2}\)O). According to the IPCC recommendations, the GWP of CH\({}_{4}\) and N\({}_{2}\)O converted to CO\({}_{2}\) is 21 and 310 at a 100-year scale, respectively [41]. The number of \(10^{-9}\) is the conversion coefficient from milligram to ton. The GHG emissions from exhaust treatment, \(E_{u}\), is calculated as follows:  
\[E_{u}=M_{1}*\frac{12}{60}*L*\frac{44}{12}*10^{-3} \tag{6}\]  
where \(M_{1}\) is the mass of urea additive consumed by catalytic converter, and its value is related to the road conditions and speed of the vehicle.