Environmental Life Cycle Assessment of Industrial Hazardous Waste Incineration: The Case of Kocaeli, Türkiye

Abstract This study evaluates the environmental performance of a hazardous waste incinerator with integrated electricity generation using a life cycle assessment (LCA) approach. The aim is to quantify the environmental impacts of hazardous waste incineration with energy recovery and to assess improvement options based on circular economy principles. Three systems were examined: the current situation (CS), a scenario including the beneficial reuse of incineration bottom ash (S1), and a carbon capture and utilization scenario involving CO₂-based methanol production (S2). The assessment followed a consequential LCA framework with system expansion to address multifunctionality by crediting avoided environmental impacts. The system boundary was defined as gate-to-grave, covering operational inputs, emissions to air and water, electricity generation, and final disposal of residues. Electricity produced from the Waste-to-Energy (WtE) plant was credited through substitution of the average Turkish electricity mix. The functional unit was set as 1 ton of waste entering the facility. Foreground data were obtained from a large-scale operating hazardous waste incinerator, while background processes were modelled using the Ecoinvent 3.7 database within SimaPro 9.2 Results show that electricity consumption is the major contributor to environmental burdens in the CS, with a climate change impact of 921 kg CO₂-eq per ton of waste. This impact decreased to 856 kg CO₂-eq/ton in S1 and to 51 kg CO₂-eq/ton in S2. Although S2 achieved the lowest impacts in most categories due to CO₂ capture and conversion, it exhibited higher particulate matter formation and freshwater ecotoxicity linked to steam use. S1 performed best in freshwater ecotoxicity through bottom ash reuse and metal recovery. Overall, the findings demonstrate that circular economy strategies and CO₂ capture technologies can significantly enhance the environmental sustainability of hazardous waste management.