# Life Cycle Assessment of Different Waste Lubrication Oil Management Options in Serbia
## 2 Description of the WLO Management in Serbia  
The model used to assess the WLO recycling process in Serbia was developed by combining the existing solutions [14; 15] with the models developed by the authors depending on the current situation in the country. Employing LCA software for the waste oil treatment in Serbia enabled a more in-depth analysis of the impact of waste oils on humans and the environment regarding GHG emissions, acidity, ecotoxicity, etc. Figure 1 shows a potential model for management, collection, separation, processing, and disposal of waste lubricating oil in Serbia developed by the authors. Approximately 5.7 Mt of lubricant are consumed annually in EU countries [16]. At least half of this amount, i.e., about 2.7 Mt, can be collected for further processing. The proper management of WLO, which consists of the proper collection, transport, processing, and disposal of WLO, represents a significant amount of valuable and useful raw material [17; 18]. According to qualifications, waste lubricant oils (WLO) belong to hazardous waste. In addition to environmental problems, WLOs pose a great danger to human health because they contain harmful pollutants in the form of heavy metals, polycyclic aromatic  
Figure 1: Waste lubricant oil treatment. The purple squares of dashed lines indicate potential scenarios for WLO treatment. ReR1 \(\div\) ReR5—WLO treatment by the re-refining process (Cyclon, Evergreen, HyLube, MRD, and Viscolube), Inc1 and Inc2—WLO treatment by incineration, CemK—WLO treatment in cement kilns. hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) [13]. PAHs naturally occur in mineral oil and are removed by vacuum processing. However, the use of mineral oils as engine oils increases oil PAH* concentrations due to fuel combustion. The ratio of PAHs in used oil can be three times higher than that in virgin oil [19]. PCBs are mainly found in transformer oil in the form of organochloride. The ban on PCBs' production and use due to their toxic and extremely stable properties was passed in the 1980s. However, by testing waste oils, certain amounts of PCBs can still be found [20]. Figure 1 shows all possible ways of treating waste oil depending on the technology available to certain countries or economies. From the energy point of view, waste oils can be considered a valuable resource because their burning can generate energy, whereas the process of waste oil refining can result in a valuable base or oil suitable for further use [21]. According to the previous studies of [PERSON] and [PERSON] [22], a total of 1.6 L of recycled waste oil can be used to produce 1 L of engine oil. Furthermore, [PERSON] et al. [23] obtained 40 MJ/kg of energy by burning 1 kg of WLO in their study on waste oil processing. When recycling WLOs by the pyrolytic process, higher energy values are obtained per one kilogram of waste oil. For such oils, 45.7 MJ/kg were obtained, indicating the values of pure diesel fuel [24]. The advantages of this procedure are manifested in the increase of processed oil energy value by 12% relative to waste oil, processing of 84-88% of waste into pure pyrolytic oil, creation of low compounds of PCBs and PAHs in the oil, low emission of waste gases, and small pollution impacts on the environment [25]. According to the Fuchs data for 2018, oils are mainly classified into the following categories: engine, industrial, process, and lubricating oils for marine engines. Of the total amount sold in 2017, engine oils accounted for 57% [26]. Accordingly, the authors wanted to present all the possible ways of treating and managing WLO. The authors have developed a model for waste oil collection, management and treatment in Serbia (Figure 2) which illustrates the actual oil collection situation from 2015 to 2020. The data used for the LCA analysis performed refer to the period from 2015 to 2019. The data for 2017 are not available.