Enrichment of heavy metals in fine particles of municipal solid waste incinerator (MSWI) fly ash and associated health risk

During the pretreatment and recycling processes, the re-suspended dust from municipal solid waste incinerator (MSWI) fly ash might pose a significant health risk to onsite workers due to its toxic heavy metal content. In this work, the morphological and mineralogical characteristics of fly ash in different particle sizes are presented. The concentrations of seven trace elements (Zn, Pb, Cu, Cd, Cr, Fe and Mn) in these samples were determined. The results show that volatile metals, such as Zn, Pb, Cu and Cd, were easily concentrated in the fine particles, especially in Dp2.5-1 and Dp1, with soluble and exchangeable substances as the main chemical species. The health risk assessment illustrated that the cumulative hazard indexes for non-carcinogenic metals in Dp10-5, Dp5-2.5, Dp2.5-1, and Dp1 were 1.69, 1.41, 1.78 and 2.64, respectively, which were higher than the acceptable threshold values (1.0). The cumulative carcinogenic risk was also higher than the threshold value (10−6). For the onsite workers, the relatively apparent non-carcinogenic and carcinogenic effects were from Pb and Cr, respectively. The above findings suggest that fine-grained fly ash contained a considerable amount of heavy metals and exhibited a great health risk.