Verification of dioxin formation in a catalytic oxidizer

Emissions and inlet concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) have been measured from a catalytic oxidizer and a thermal oxidizer. The catalyst inlet temperature was 427 °C. The thermal oxidizer operating temperature was 791 °C. Data of the toxic dioxin and furan congeners are reported. Important results of this field study are: (1) the catalytic oxidizer in this study produced an increase in PCDD/PCDF congener concentration of almost 10-fold from the inlet to the outlet (stack), thus verifying results of a previous study that evaluated only PCDD/PCDF emissions. All congeners increased from inlet to the stack. (2) The thermal oxidizer had little effect on PCDD/PCDF levels. There was a decrease in four of the congeners and an increase in 13 congeners. (3) Ambient air was the main source of PCDD/PCDFs in the stack emissions of the thermal oxidizer in this study.Laboratory investigations are needed to understand how PCDD/PCDFs are formed (and emitted) under conditions of this study.