Abstract

Urban organic waste represents a significant environmental challenge while simultaneously offering opportunities for carbon sequestration and soil improvement through circular economy principles. This study evaluated the carbon footprint reduction potential of integrating food waste compost, yard trimmings, and biosolids into urban soil systems across five metropolitan areas. Life cycle assessment (LCA) methodology quantified greenhouse gas emissions from waste processing, transportation, and soil application compared to conventional waste disposal. Results demonstrated substantial carbon footprint reductions of 2.8-4.1 kg CO₂-eq per kg of organic waste diverted from landfills. Soil organic carbon increased by 0.8-1.2% annually in amended urban soils, representing long-term carbon storage of 15-22 t CO₂-eq ha⁻¹ yr⁻¹. Urban park soils amended with organic waste showed improved water retention (35% increase), nutrient availability, and plant growth compared to conventional management. Economic analysis revealed net benefits of $180-320 per tonne CO₂-eq avoided through reduced waste disposal costs and enhanced urban ecosystem services. Microbial community diversity increased by 40-60% in organic waste-amended soils, indicating improved soil health and ecosystem functioning. The integrated approach achieved 65% diversion of organic waste from landfills while creating valuable soil carbon sinks in urban environments. These findings demonstrate that circular economy approaches to urban waste management can simultaneously address waste disposal challenges, climate change mitigation, and urban soil degradation through integrated organic matter recycling systems.