Environmental Impacts of Construction and Demolition Waste Fine Residues from Material Recovery Facilities in NSW, Australia

<p dir="ltr">Construction and Demolition Waste (C&DW) fine residues from Material Recovery Facilities (MRFs) present significant environmental risks due to their complex composition and potential for contamination. This research investigates the physicochemical properties, leaching behavior, and ecotoxicological effects of C&DW fine residues, with specific focus on heavy metal content and interactions with gypsum and organic matter. A multi-faceted methodological approach was employed, integrating a systematic literature review, laboratory-based column-leaching experiments, and ecotoxicity assessments, which provides a comprehensive evaluation of the environmental implications of these materials.</p><p dir="ltr">Findings reveal that C&DW fine residues contain hazardous contaminants, including chromium (Cr), cadmium (Cd), arsenic (As), and lead (Pb), which exhibit notable leaching potential under landfill conditions. A two-phase leaching pattern was identified, with an initial surge in metal release followed by stabilization. The presence of gypsum was found to enhance the mobility of heavy metals, particularly zinc (Zn) and arsenic (As), raising concerns over its role in waste management practices. Ecotoxicity assessments demonstrated severe phytotoxic and reproductive effects, with plant growth suppression observed at residue concentrations above 25% and significant harm to earthworm reproduction at levels exceeding 10%.</p><p dir="ltr">The study concludes that C&DW fine residues should not be considered inert and underscores the necessity for stringent disposal regulations and treatment interventions to mitigate the environmental risks. Key recommendations include enhanced waste segregation at source, stricter regulatory frameworks, and further research into stabilization techniques to mitigate heavy metal mobility. Moreover, studies focusing on long-term field assessments to validate laboratory findings and explore sustainable reuse options for these materials are encouraged.</p><p dir="ltr">By addressing critical knowledge gaps and offering data-driven insights, this research contributes to the development of more sustainable C&DW management practices. The findings provide valuable guidance for policymakers, industry stakeholders, and environmental scientists, aiding in the formulation of strategies to minimize ecological harm and improve resource recovery in the construction sector.</p>