Environmental Risk Assessment, Leaching Behavior, and Sustainability Assessment of MSWI Bottom Ash for Safe Utilization in Cement-Based Materials

Abstract

The increasing generation of municipal solid waste in India has intensified the need for sustainable management strategies for incineration residues, particularly municipal solid waste incineration bottom ash (MSWI-BA). This study presents a comprehensive environmental risk assessment, leaching behavior analysis, and sustainability evaluation of MSWI-BA for its safe utilization in cement-based materials. Processed MSWI-BA was incorporated as a partial fine aggregate replacement in Portland cement concrete, and its environmental performance was assessed through regulatory batch leaching and pH-dependent leaching tests. Heavy metal concentrations (Zn, Pb, Cd, Cr, Cu, and Ni) in leachates were quantified using atomic absorption spectrophotometry and evaluated against Indian and international regulatory limits. The results indicate that raw MSWI-BA exhibits elevated metal leaching under acidic conditions; however, cement-based stabilization significantly reduced metal mobility, achieving a reduction of approximately 70–85% and ensuring full regulatory compliance across a wide pH range. pH-dependent leaching results confirmed effective immobilization of contaminants through chemical binding and encapsulation within cement hydration products. Electrical conductivity and oxidation–reduction potential analyses further demonstrated enhanced chemical stability of the stabilized composites. From a sustainability perspective, the valorization of MSWI-BA contributes to landfill diversion, conservation of natural aggregates, and reduced environmental impact of concrete production. Overall, the findings establish MSWI-BA as an environmentally safe and sustainable material for future concrete manufacturing, supporting circular economy principles and responsible infrastructure development.