Formation pathways, migration characteristics, and inhibition mechanism of polychlorinated dibenzo-p-dioxins and dibenzofurans in hazardous waste incinerators: A comprehensive pilot-scale study.

Recent studies on hazardous waste incinerators (HWIs) and municipal solid waste incinerators (MSWIs) indicate that HWs have a greater impact on the variability of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuran (PCDD/F) emissions than MSWs. Scholars have reported excessive PCDD/F emission in many HWIs, with divergent views on the dominant PCDD/F formation mechanisms. However, studies addressing PCDD/F formation mechanisms and migration characteristics from different HW materials in HWIs remains limited. This study incinerated various HWs in a pilot-scale HWI, providing insights into the formation pathways and migration characteristics of PCDD/Fs in HWIs. De novo synthesis, chlorophenol pathways, dibenzo-p-dioxin chlorination, and chlorobenzene pathways were identified as dominant PCDD/F formation mechanisms in HWIs, with precursor synthesis playing a key role in excessive emissions. A notable memory effect, marked by the absorption of low-chlorinated PCDD/Fs, was observed. The extensive formation and deposition of PCDD/Fs, along with the memory effect, can exacerbate the pressure of PCDD/F emission in HWIs. NaSCN and CaO effectively inhibited precursor synthesis in HWIs, reducing emissions. This study identified key factors influencing PCDD/F formation and migration in HWIs and proposed effective strategies for low emissions, aiding HWI operations.