Ultrafast electrothermal stabilization of heavy metals in municipal solid waste incineration fly ash by flash Joule heating.

With the widespread adoption of municipal solid waste incineration (MSWI), the harmless treatment of its hazardous byproduct, fly ash, has emerged as an urgent environmental challenge. Conventional thermal stabilization technologies are effective but are hindered by high energy consumption and prolonged processing times. Here, we develop an ultrafast electrothermal stabilization of heavy metals in MSWI fly ash based on flash Joule heating (FJH) induced sintering and vitrification. Without water-washing pretreatment, FJH treatment at 1250°C for only 10 s reduced the leachate concentrations of Cd, Pb, Cr, Zn, and Cu below the stringent limits specified in the Chinese national standard GB 16889-2024, achieving stabilization rates > 99.9%. The FJH treatment temperature is the dominant factor governing heavy metal stabilization. The electrothermal stabilization is achieved through the combined effects of rapid sintering, mineral reconstruction, and selective volatilization of a small fraction of heavy metals. The FJH strategy exhibits broad applicability to fly ashes with diverse compositions and heavy metal contents, and initial scale-up tests showed reduced specific energy consumption by > 70%. This work establishes FJH as a rapid, energy-efficient strategy for fly ash treatment, providing a promising pathway toward electrified and sustainable hazardous waste management. SYNOPSIS: Ultrafast electrothermal treatment of municipal solid waste incineration fly ash by flash Joule heating reduces heavy metal leaching and supports safe management of hazardous wastes in environmental systems.