Characteristics and resource availability of Zinc-rich fly ash generated from medical waste through rotary and plasma thermal treatment

Abstract

Fly ash from medical waste (MW) thermochemical treatment is disposed of in concrete landfills due to its well-known pollution property, while its recycling potential is ignored. This study is the first to explore the environmental characteristics, resource availability, and recovery method of medical waste incineration fly ash (MW-IFA) and medical waste plasma vitrification fly ash (MW-PFA) in China. Features of high chloride levels (28.27–42.89%) and richness in Zn (3.15–7.53%) were observed in all fly ash samples. Notably, low-calcium MW-IFA and MW-PFA may posed higher environmental risks due to much higher zinc leaching concentrations (1621.83–5163.97 mg/L) than high-calcium MW-IFA (2.58–5.02 mg/L). Moreover, the resource availability of Zn measured by water washing, acid leaching and thermal treatment was similar, with the range of 20.69–96.84%, 60.89–90.57%, 60.17–96.82%. Hence, considering avoiding excessive energy consumption, the MW fly ash dissolution and recovery (MWFADR) technology, combining water washing and acid leaching processes, was proposed for ZnO and crystal salt production. The results of this work highlight the recovery potential of Zn and Cl in MW fly ash and propose an environmentally and economically sound solution.