Biodiesel was produced herein from the oil contained in waste spent bleaching earth (SBE), an environmental pollutant generated through the refining processes of edible oils in oil extraction plants. To further increase waste utilization, waste expanded polystyrene (EPS) was also dissolved in SBE biodiesel (0, 2.5, 5, and 7.5 g/100 ml). Performance parameters and emission characteristics of 5% blend of EPS-SBE biodiesel and diesel were then investigated in a naturally aspirated diesel engine. The results obtained demonstrated that polymer-free SBE-B5 at 1600 rpm and full load led to enhanced brake power and brake mean effective pressure by approximately 1.5%. Moreover, the emitted HC, CO, and smoke were decreased by over 40%, 80%, and 20%, respectively, with polymer inclusion at 2.5 g/100 ml in SBE-B5 at maximum speed of 2600 rpm and full load (280 N m). While the optimal polymer inclusion level of 2.5 g/100 ml had subtle impacts on engine performance parameters. The findings of the present study could be of great interest to waste valorization industries since an integrated strategy was offered to simultaneously handle two environmental pollutants (SBE oil and EPS wastes) while a more environmentally friendly fuel blend (i.e., SBE-B5 containing 2.5 g EPS/100 ml) was also achieved. (C) 2016 Elsevier Ltd. All rights reserved.