Combined life cycle analysis and material flow analysis as a tool for end of life options of used lubricating oils

Abstract

Used lubricating oils are one of the most significant material flows in the economy. After being used, they are typically contaminated with, e.g., heavy metals, which could harm the environments if they are treated improperly. The used oils should be properly treated by reprocessing or recycling which the recyled products can be used to subsitute the production the new product, as a result a net reduction of the environemental impacts. This study aimed to investigate the waste flow and then evaluate the environmental impacts of waste management options using the Material Flow Analysis (MFA, STAN v.2.6.801) and Life Cycle Assessment (LCA, SimaPro v.8.3.0) as an assessment tool. The functional unit was set as a ton of market demand of petroleum products in Thailand in the calendar year 2017. Five scenarios of waste management were developed into base case or current operation (Option 1), zero-production (Option 2), distillation (Option 3), re-refining by KTI process (Option 4) and re-refining by Revivoil process (Option 5). The MFA results shows that the secondary products obtained from waste treatment method were mainly composed of diesel (68%) followed by asphalt (20%). The LCA results show the emission hotspots of environmental impacts in each waste treatment scenario that KTI process had the least value of global warming potential impact (-1,356 kg CO₂ eq), followed by Revivoil process (-733 kg CO₂ eq), whereas the impact value of the base case was approximately 24 times higher than that of KTI process - which has the least impact option. Therefore, for sustainably used oil management, KTI process is an appropriate technology rather than the current operation.