Characterization of Dioxins and Heavy Metals in Chelated Fly Ash

Municipal solid waste incineration (MSWI) fly ash contains highly toxic heavy metals and polychlorinated dibenzo dioxins/furans (PCDD/Fs), which are a type of hazardous waste. The pollution characteristics of fly ash have changed with the development of stoker grate incinerators and the fly ash treatment technology; however, no research has been focused on this in recent years. In this study, 12 fly ash samples were collected from 9 grate power plants in southeastern China, and their PCDD/Fs and heavy metal concentrations were determined and compared to previous fly ash data. The PCDD/Fs concentration in fly ash was in the range of 0.002-0.051 ngI-TEQ/g, with an average of 0.027 ngI-TEQ/g. Furthermore, 1,2,3,4,6,7,8-HpCDD and OCDD made the most significant contributions to PCDDs. The distribution of 10 dioxins exhibited bimodal, unimodal, and normal characteristics. Linear fitting demonstrated a strong correlation between toxicity and 1,2,3,7,8-PentaCDD, 1,2,3,7,8-PentaCDF, and 2,3,4,7,8-PentaCDF. Concerning heavy metals, Pb poses a significant environmental risk. This is the first time that fly ash treated with a chelating agent has been thoroughly analyzed, which is vital for understanding the pollution level and treatment of fly ash derived from current power plants.