HCB dechlorination combined with heavy metals immobilization in MSWI fly ash by using n-Al/CaO dispersion mixture

Municipal solid waste incineration fly ash (MSWI-FA) has been strictly controlled as hazardous waste globally because it contains various heavy metals and dioxins. This study prepared a nanometallic Al/CaO (n-Al/CaO) dispersion mixture via ball-milling as a reductive stabilization reagent for the simultaneous immobilization of heavy metals and detoxification of POPs like substance in MSWI-FA. Under optimal conditions, Cu, Zn, Cd, Cr, Ni, and Pb had been significantly immobilized (over 99.9 %) and the leaching concentration of Zn, Cd, Cr, Ni, and Pb were below the detectable limit. Simultaneously, 82.43 % of HCB can be destructed into alkanes and amorphous carbon. The porous structure of the fly ash and alkaline surface of n-Al/CaO promoted the adsorption and cracking of HCB. The highly active n-Al/CaO interacted with water as the hydrogen donor to promote the reductive dechlorination process. Hydrocalumite was a new mineral formed from the adsorption and complexation of heavy metal. Therefore, n-Al/CaO can strengthen the control of heavy metals in the S/S treatment of MSWI-FA, effectively detoxify chlorinated organics, and reduce environmental health risks.