Abstract Purpose Food waste management is a critical global concern with significant environmental implications. This study employs Life Cycle Assessment (LCA) to evaluate the environmental impacts of two food waste disposal pathways in the United Kingdom (UK): (1) collection of separated food waste at the kerbside and (2) the use of kitchen food waste disposers (FWDs) discharging to wastewater collection and treatment systems. Methods Using the ReCiPe (2016) method and SimaPro software, impacts across 18 midpoint indicators were assessed for a functional unit of treating 100 kg of food waste, including anaerobic digestion (AD) in both pathways, with biomethane credited via substitution of fossil natural gas. Sensitivity analyses were conducted for variations in waste transportation distances and emissions factors of electricity grids across different UK regions. Results The results revealed that kerbside collection performed worse across 14 of 18 midpoint impact indicators. FWDs contributed to higher global warming potential of 30 kg CO 2 eq versus 17 kg CO 2 eq for kerbside collection, mainly due to greenhouse gas emissions during sewer network transport and wastewater treatment. However, they avoid the transport burdens that dominate key kerbside impacts (e.g. particulate matter and a large share of global warming potential), offering reduced transport emissions and greater convenience in high-density living scenarios. Conclusion These findings highlight the nuanced trade-offs in food waste management and the potential role of FWDs in a comprehensive waste reduction policy in the UK. These findings are not only relevant for UK policy but have implications for cities worldwide facing logistical challenges in separate food waste collection, especially in high-density urban areas.
Ali et al. (2026) studied this question.