Comprehensive assessment of precious metal concentration, distribution, and recovery potential in municipal solid waste incineration residues from northern Vietnam

Abstract

The incineration process of municipal solid waste produces residues which serve as valuable secondary resources for extracting precious metals including Ag, Au, Pt, Pd, and Rh. The research delivers the initial full dataset about metal concentrations and distribution and recovery potential in three residue types which include fine particulate matter (PM₁₀), and fly ash (FA), and bottom ash (BA) from incineration facilities in northern Vietnam. The analysis of all samples occurred through ICP-MS to determine the metal content. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) was used to characterize particle morphology and elemental associations in the samples. Statistical correlation analysis was applied to identify relationships among metals and to determine how their potential sources differed across municipal, mixed, and industrial waste streams. The metal concentrations showed average values between 1.92 and 10.8 µg Nm⁻³ in PM10, 0.055 and 8.52 mg kg⁻¹ in FA, and between 0.097 and 10.7 mg kg⁻¹ in BA with Ag showing the highest levels. These concentrations were higher than that of many incineration plants in Japan and Poland, and significantly higher than mean crustal compositions. Among the analysed elements, Ag contributed the largest proportion (17–95%), followed by Au (5–57%), Pd (0–44%), Pt (2–41%), and Rh (<10%). Metal distribution patterns varied with waste composition: Ag was prevalent across all feedstocks, whereas Au was enriched in municipal and mixed waste, and Pt, Pd, and Rh were mainly associated with industrial residues. Strong Pearson correlations (r = 0.64–0.94) among Ag/Pd/Pt, Au/Pt, and Pt/Pd/Rh pairs indicate potential co-occurrence and a shared origin. Two economic recovery models demonstrated that both fly ash and bottom ash constitute feasible sources for precious-metal recycling. The results provide a scientific basis for waste valorisation, resource recovery, and circular-economy strategies for MSWI residues in Vietnam.