From Waste to Resource: Carbon, Nitrogen, and Energy Routing in End-of-Life Tires and MSW-Derived Refuse Fuel

End-of-life tires (ELTs) and refuse-derived fuel (RDF) produced from municipal solid waste (MSW) contain recoverable carbon (C), nitrogen (N), and chemical energy. This study evaluated pyrolysis as a resource-routing approach by comparing ELT and RDF under a common 500 °C batch condition. Product yields, elemental routing, energy retention, and downstream utilization potential were assessed across char, liquid, and gas streams. ELT retained 82.6% of feed carbon and 86.2% of feed energy in char and liquid products, whereas RDF retained 62.4% of feed carbon and 44.6% of feed energy in these condensed streams and produced a larger apparent gas fraction. Nitrogen routing also differed markedly: ELT distributed N relatively evenly between char and liquid, while RDF retained 61.3% of its initial N in char despite containing approximately seven times more N per unit mass of prepared feedstock. ELT produced carbon-rich char and an energy-dense liquid requiring upgrading, while RDF showed greater carbon and nitrogen retention in char and generated a predominantly aqueous condensate. Screening against published utilization studies and relevant product criteria identified plausible material, chemical, and energy-recovery pathways. Overall, the findings highlight the importance of feedstock-specific elemental routing and product quality in evaluating resource recovery, providing a practical basis for integrating thermochemical conversion into circular waste-management systems.