Comprehensive chloride and dioxins removal of fly ash by water washing and low-temperature catalytic degradation...

Incineration is a pivotal technique for solid waste management, yet it generates fly ash laden with chlorides and dioxins, posing significant environmental and operational challenges. This study proposes and validates a two-stage detoxification strategy: water washing to remove chlorides, followed by low-temperature catalytic degradation of dioxins. Primary and secondary water washing achieved an 81% chloride elution efficiency. Regarding dioxin degradation, the CaO-Ca₂SiO₄ catalyst demonstrated superior performance compared to conventional Ca-based catalysts, achieving near-complete dechlorination (∼100%) of hexachlorobenzene (HCB). Applied to real-scenario fly ash, dioxin concentrations were reduced from 240 ng-TEQ/kg to 2.7 ng-TEQ/kg in grate furnace ash and from 300 ng-TEQ/kg to 25 ng-TEQ/kg in fluidized bed ash, and both outcomes comply with the threshold for resource utilization. This work advances foundational insights into fly ash pretreatment, offering a scalable and effective framework for waste management.