Characterization and carbonation potential of RDF bottom ash from the incineration of anaerobic digestate of municipal solid waste

• New ash material investigated from anaerobic digestate energy recovery. • Fine fraction < 2 mm nearly twice that of conventional MSW IBA. • Abundant unreactive melilite group minerals (∼14–29 wt%) • Fast carbonation with uptakes ranging from 60 to 115 gCO 2 /kg IBA. • Cu, Zn, Fe, Al, and detectable Ag indicate recoverable metal potential. Refuse-Derived Fuel (RDF) incineration is an emerging route to enhance energy recovery. At the Trifyl renewable energy hub (France), RDF is produced from a solid anaerobic digestate (12–14 MJ/kg), generating a distinctive bottom ash (IBA). This study investigates the valorization potential of this novel RDF-IBA through mineral carbonation for CO 2 sequestration and stabilization. Four monthly IBA samples were collected within the ASHES academia–industry program. Thirty-two aqueous carbonation tests were performed on fine IBA fractions (< 0.25 mm, 0.25–0.5 mm, 0.5–1 mm, and 1–2 mm), including crushed samples. Comprehensive characterization (XRF, QXRPD, optical microscopy, SEM-EDS, chromatography, ICP-MS) was conducted, and carbonation was monitored by gas flow sensors. The RDF-derived IBA was finer (56–70 wt% < 2 mm), poorer in metals, richer in melilite (14–29 wt%), and exhibited considerably lower Cl − and SO 4 2- leaching than conventional MSW IBA. Temporal variability among the four consecutive monthly samples was low, indicating strong potential for consistent advanced treatment. CO 2 uptake ranged from 60 to 115 g CO 2 /kg IBA , depending on particle size and milling. Beyond conventional metals (Cu, Zn, Pb, Sn, Sb), Ag was also identified. Carbonation reduced cationic (Ni, Zn, Pb) and oxyanionic (Cr, As) leaching, while Sb remained above reuse thresholds despite high removal efficiency. Overall, RDF-IBA shows strong potential for landfill diversion via integrated metal recovery and carbonation.