# Life Cycle Assessment of Different Waste Lubrication Oil Management Options in Serbia
## 4 Discussion of the Impact Assessment
\begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline  & **ReR1** & **ReR2** & **ReR3** & **ReR4** & **ReR5** & **CemK** & **Inc1** & **Inc2** & **Unit** \\ \hline
**Midpoint impact categories** & & & & & & & & & \\ Freshwater eutrophication & 0.62 & 0.15 & 0.088 & 0.17 & 0.12 & \(-\)0.023 & \(-\)1.7 & 0.18 & kg p eq \\ Freshwater ecotiosity & 21 & \(-\)1.1 & \(-\)0.36 & 1.5 & \(-\)2.7 & \(-\)2.8 & \(-\)72 & 6.1 & kg 14-DC8 \\ Stratospheric ozone depletion & \(-\)0.001 & \(-\)8.9 \(\times\) 10\({}^{-4}\) & \(-\)8.6 \(\times\) 10\({}^{-4}\) & \(-\)8.8 \(\times\) 10\({}^{-4}\) & \(-\)9.1 \(\times\) 10\({}^{-4}\) & \(-\)7.0 \(\times\) 10\({}^{-4}\) & \(-\)5.5 \(\times\) 10\({}^{-4}\) & \(1.1\times\) 10\({}^{-5}\) & kg Crelli eq \\ Marine ecotoxicity & 24 & \(-\)3.6 & \(-\)2.3 & 0.022 & \(-\)6.3 & \(-\)5.3 & \(-\)94 & 8.4 & kg 14-DC8 \\ Human non-carcinomic & 380 & 6.6 & \(-\)8.2 & 46 & \(-\)25 & \(-\)69 & \(-\)1300 & 160 & kg 14-DCB \\ toxicity & & & & & & & & \\ Marine eutrophication & 0.040 & 0.0025 & \(-\)0.0011 & 0.004 & 00027 & \(-\)0.003 & \(-\)0.11 & 5.4 \(\times\) 10\({}^{-4}\) & kg N eq \\ Fossil resource scarcity & \(-\)1100 & \(-\)1000 & \(-\)1000 & \(-\)980 & \(-\)1000 & \(-\)900 & \(-\)840 & 5 & kg N eq \\ Global warming & \(-\)530 & \(-\)460 & \(-\)460 & \(-\)540 & \(-\)600 & \(-\)1100 & 150 & 2800 & kg CO\({}_{2}\) eq \\ Ionizing radiation & \(-\)18 & \(-\)21 & \(-\)22 & \(-\)22 & \(-\)26 & \(-\)24 & \(-\)57 & 0.78 & kg CO\({}_{2}\) eq \\ Fine particulate matter & \(-\)0.6 & \(-\)1.5 & \(-\)1.5 & \(-\)1.4 & \(-\)1.3 & \(-\)1.2 & \(-\)4.9 & 0.084 & kg Mg\({}_{2}\) eq \\ Human carcinogenic toxicity & 11 & \(-\)15 & \(-\)15 & \(-\)12 & \(-\)18 & \(-\)20 & \(-\)99 & 29 & kg I4-DCB \\ Mineral resource scarcity & \(-\)0.24 & \(-\)1.1 & \(-\)0.53 & \(-\)0.79 & \(-\)1.2 & \(-\)0.45 & \(-\)1.3 & 0.2 & kg Cu eq \\ Ozone formation, Human health & \(-\)1.9 & \(-\)1  
The aggregated endpoint results obtained (Figures 4-6) clearly indicate that the choice of the most or least environmentally advantageous waste management process is ambivalent and depends greatly on the environmental aspects considered. Re-refining is evidently favoured in terms of fossil resource savings. However, the combustion of used oil in cement kilns (i.e., the substitution of petroleum coke) exerts the most beneficial effects on ecosystem quality. On the other hand, the combustion of used oil in hazardous-waste management is not a significant effect on the development of the ecosystem quality. Figure 4: Impact of different WLO treatment technologies on human health (per 1000 kg WLO). Figure 5: Impact of different WLO treatment technologies on the ecosystem (per 1000 kg WLO). Figure 6: Impact of different WLO treatment technologies on resource availability (per 1000 kg WLO). incinerators with energy recovery is the best option provided the protection of human health is the highest priority. Another important observation is that the results obtained are very dependent on the assumptions made regarding the substituted processes. In this study, all the systems have been credited for the products that they generate (materials and energy) assuming that each product can be fully utilized. However, the lack of demand for such products in declining markets could lead to their underutilization, indicating that they are used only partially or not at all [47]. If the generated product is not fully utilized, any additional supply would go to waste depositing as the market is already oversupplied [48]. Consequently, no credits would be given for such product because the LCA does not consider the environmental impacts associated with the disposal process. Figures 7-9 show the potential environmental benefits of implementing various WLO management options in RSerb on an annual basis. The ReRavg process represents the average environmental impact of the five re-refining processes (ReR1-5) considered in the study.