# The Life-Cycle Environmental Impact of Recycling of Restaurant Food Waste in Lanzhou, China
## 3 Results and Discussion
### Sensitivity Analysis  
In this section, a sensitivity analysis of environmental impacts was conducted to identify the effect of chosen methods on the results of the LCA. Table 5 shows the results of the sensitivity analysis of food waste recycling, comparing the use of different LCA methods (ReCiPe1.08, IMPACT 2002+, and TRACI 2.1), considering the environmental impacts results from CML 2011 method as a reference. The larger the comparison value is, the more sensitive the method and/or data are to uncertainty in the results [45]. The results were shown to be consistent for the global warming potential category among the four methods. In terms of the acidification potential, CML2001, IMPACT 2002+, and TRACI 2.1 had consistent results. In terms of the photochemical ozone creation potential, CML2001 and IMPACT 2002+ had consistent results. In terms of the eutrophication potential and ecotoxicity potential, different methods produced different results. The main difference was inconsistent normalization units. The different results were mainly attributable to different assessment categories and different normalization values (equivalent units) in the main categories, which resulted in differences among assessment results [24]. These results indicated that the life-cycle assessment results of CML2001 are reasonable. Table 6 shows the results of the sensitivity analysis, aimed at determining the effect of the following factors on the environmental impacts: diesel consumption during the collection and transportation stage, water consumption and electricity consumption during the pre-process stage, aerobic compositing additive during the solid composition stage, and ferric chloride consumption during the wastewater treatment stage. The third column in Table 6 shows the LCA results based on the actual data using the CML2001 model. Columns 4-8 show the results after a 5% increase in the value of the five factors. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Category**} & \multirow{2}{*}{**Unit**} & \multirow{2}{*}{**CML2001**} & **Diesel** & **Water** & **Electricity** & \
\begin{tabular}{c} **Aerobic Compositing** \\ **Additive** \\ \end{tabular} &
\begin{tabular}{c} **Ferric** \\ **Chloride** \\ \end{tabular} \\ \cline{3-6}  & & & **5\%** & **5\%** & **5\%** & **5\%** \\ \hline Acidification potential & kg SO\({}_{2}\)-eq & 0.2 & 0.2 & 0.2 & 0.29 & 0.2 & 0.2 \\ \hline Eutrophication potential & kg phosphate-eq & 0.11 & 0.11 & 0.11 & 0.12 & 0.11 & 0.11 \\ \hline Freshwater aquatic & & & & & & \\ ecotoxicity potential & kg DCB-eq & 0.34 & 0.34 & 0.37 & 0.34 & 0.34 \\ \hline Global warming potential & kg CO\({}_{2}\)-eq & 274.57 & 274.76 & 274.65 & 277.25 & 274.57 & 274.57 \\ \hline Human toxicity potential & kg DCB-eq & 0.6 & 0.61 & 0.6 & 2.49 & 0.6 & 0.6 \\ \hline Marine aquatic & & & & & & \\ ecotoxicity potential & kg DCB-eq & 53.05 & 53.26 & 53.86 & 202.79 & 53.05 & 53.05 \\ \hline Photochemical ozone & & & & & & \\ creation potential & kg ethene-eq & 0.04 & 0.04 & 0.04 & 0.04 & 0.04 & 0.04 \\ \hline Terrestrial ecotoxicity & & & & & & \\ potential & kg DCB-eq & 0.1 & 0.1 & 0.1 & 0.13 & 0.1 & 0.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Sensitivity analysis of key variables.