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 -clas-sification 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 munic-ipal 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 be-came 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.

Automated summary

Policy has a significant influence on the contents and leaching characterizations of municipal solid waste incineration fly ash. The implementation of garbage-classification policy led to changes in the content of chloride and heavy metals. The presence of calcium chloride hydroxide (CaClOH) resulted in a decrease in heavy metal leaching concentrations and more stable chemical speciation. Therefore, adjustments in fly ash treatment technologies and running parameters are necessary after the implementation of the garbage-classification policy.