Bio-treatment of municipal solid waste incineration fly ash: A sustainable path for recyclability

This study investigates the impact of bio-treatment on Municipal Solid Waste Incineration Fly Ash (MSWIFA), comparing bio-treated MSWIFA (BFA) to raw MSWIFA (RFA). BFA exhibited a larger particle size and the presence of microbial-induced calcium carbonate precipitation (MICP) gels. Both RFA and BFA maintained highly alkaline pH levels, with mineral analysis showing reduced chlorine content in BFA and the presence of Monocarboaluminate (Mc), suggesting potential concrete strength improvements. Bio-treatment effectively reduced polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) levels, meeting standards. Biominer-alization stabilized heavy metals in MSWIFA, reducing leaching concentrations and meeting national standards. Blending BFA with magnesium phosphate cement (MPC) improved compressive strength, especially in early stages, further enhanced by calcium acetate. SEM images confirmed MICP gels on paste surfaces, contributing to increased strength. Analytical techniques (X-ray diffraction, Fourier transform infrared, and thermal gravimetric analysis) supported superior performance in hydration and strength. SEM-EDS analysis showed effective solidification/stabilization of heavy metals, reduced chlorine content, and enhanced biomineralization. Leaching tests confirmed reduced heavy metal concentrations in leachate. In summary, bio-treatment enhances the properties and environmental impact of MSWIFA, offering sustainable waste management opportunities.