Carbonation pretreatment enhance the hydrothermal detoxification of municipal solid waste incineration fly ash

Abstract

A combined carbonation-hydrothermal method is proposed here for the harmless treatment of water-washed municipal solid waste incineration fly ash (WMSWI-FA). This study investigates the effect of temperature on the hydrothermal detoxification of dioxins and assesses the effect of carbonation pretreatment on the detoxification of dioxins and the stabilization of heavy metals in WMSWI-FA. The results demonstrate that elevated temperatures benefit the detoxification of dioxins, with detoxification efficiencies improving from -31.16% to 81.54% as temperatures increase from 180°C to 260°C. After carbonation pretreatment, dioxin concentrations were decreased from 36.31 ng-TEQ/kg to 30.62 ng-TEQ/kg and detoxification efficiency increased from 81.54% to 82.41%. It is primarily attributed to pH changes caused by carbonation pretreatment, which significantly affect the dechlorination reaction of dioxins. Additionally, carbonation pretreatment effectively stabilizes heavy metals such as Pb, Zn, and As through precipitation and physical encapsulation. This study concludes that combining carbonation pretreatment with hydrothermal treatment offers a promising strategy for the safe and effective treatment of WMSWI-FA.