Recycling of construction and demolition waste fines for decentralized stormwater filtration: Environmental leaching and life-cycle cost assessment

• CDW fines reused as circular materials for stormwater filtration. • Leaching tests confirm environmental safety of recycled filters. • LCCA identifies most cost-efficient waste-processing pathways. • CDW fines offer highest economic and circular value. • Filer design supports sustainable urban water management. Rapid urbanization and climate change are intensifying pressures on water resources and urban drainage systems, underscoring the urgent need for sustainable stormwater management solutions. This study presents the development and evaluation of a novel construction and demolition waste (CDW)-based agglomerated filtration system designed for stormwater purification. The system integrates locally sourced CDW materials into a circular, low-cost treatment solution currently under development. Leaching analyses revealed low concentrations of heavy metals and metalloids, indicating excellent chemical stability and minimal risk of secondary contamination. The limited dissolution of matrix-forming elements confirmed strong structural integrity of the agglomerates under aqueous exposure. A comprehensive life cycle cost analysis (LCCA) was performed to assess the economic feasibility of the system across its entire lifespan. Results showed that operation and maintenance costs constituted over 80% of the total expenditure, with recycling via casting identified as the most cost-effective end-of-life scenario. Compared with conventional stormwater filtration systems, the CDW-based filters demonstrated up to 80% lower life-cycle costs per cubic meter of water treated, while maintaining favorable environmental performance. Overall, the results highlight the potential of CDW-based agglomerated filters as a sustainable and economically viable option for next-generation stormwater infrastructure, contributing to circular water resource management in urban environments.