Garbage-classification policy changes characteristics of municipal-solid-waste fly ash in China

Policy is a powerful tool determining solid-waste treatment and disposal. In 2019, China carried out the “garbage-classification policy” in 46 cities. So-called dry garbage is then separated from municipal solid waste and treated alone by incineration. This work investigated the influence of the policy on contents and leaching characterizations of municipal solid waste incineration fly ash. Median value of Cl was significantly increased from 17.43 wt% to 28.63 wt%. Median content of CaO maintained a similar value (51.21 wt% and 47.27 wt%). Ten year ago, CaClOH was not generally observed in fly ash. However, this phase was widely detected nowadays. Median value of heavy-metal (Zn, Pb, Cu, Cd, Cr, and Ni) was decreased from 9007.69 mg/kg to 7652.72 mg/kg. Thus, the policy also positively affected hazardous-waste collection. Heavy-metal leaching concentrations were decreased and chemical speciation became more stable because CaClOH supplied more alkalinity and binding ability for heavy metals. Therefore, fly-ash treatment technologies and their running parameters should be regulated to adapt above new characterizations after the garbage-classification policy. [Display omitted] •Garbage-classification policy changed components of fly ash.•Median value of Cl was increased from 17.43 wt% to 28.63 wt%.•Total amount of heavy metals was decreased from 9 g/kg to 7.65 g/kg.•CaClOH became the main chlorine-containing phase.•Leaching risk of Zn was decreased from 89.49 mg/L to 21.44 mg/L.