Used Cooked Oils in Sewage and Wastewater System: Qualitative Characterisation and Environmental Impacts Assessment in Different Discharge and Recovery Pathways

Abstract Nowdays only 30% of domestic used vegetable oil is currently recovered, with significant quantities discharged into sewer systems, strongly contributing to environmental degradation. Converting used cooked oil (UCO) into biodiesel is the most suitable approach to minimize environmental impacts and exploit the potentiality of a valuable resource. Although biodiesel is widely recognized as a promising technology for clean electricity production, the environmental impacts and its advantages in terms of carbon footprint remain partially unclear in the territorial framework. This study investigates and quantifies the technical and environmental impacts associated with the production, consumption and recovery of used cooking oil in Italy and Europe through life cycle assessments (LCA) approach. Different Scenarios, considering partial oil recovery, partial discharge in the sewage system and total oil recovery for biodiesel production, were investigated. Real data were collected by a territorial company in central Italy. LCA results reveals the transition from the Scenarios, resulting in a significant improvements in terms of environmental indicators especially, in order of prorioty, as climate change, freshwater eutrophication and terrestrial acidification. Overall, considering the total oil recovered and biodiesel production, the carbon footprint mitigation shows 14–27% reduction in CO 2 (carbon dioxide) emissions in respect to the Scenario where the oil is partially recovered, equivalent to an environmental impact of 48–199 Pey −1 (people equivalent per year). Graphical Abstract