Chlorophenols, as precursors of PCDD/Fs in incineration processes: Correlations, PLS modeling, and reaction mechanisms

Emissions of organic chlorinated compounds from municipal waste incineratio n, in particular polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofuran s (PCDFs), have been a cause of public concern for many years because of th e high toxicity of these compounds. PCDD/F formation in incineration proces ses is being studied widely using lab-scale apparatus, but pilot-plant inve stigations are quite rare. The correlation between TEQ-related PCDD/Fs and chlorophenols (CIPhs) was studied here using a pilot-scale plant. The resul ts suggest that almost all the CIPh isomers correlate strongly with PCDD/Fs in the gas phase, but only certain isomers, in particular 2,3,4,6- and 2,3 ,4,5,6-CIPh, are of importance in the particle phase. The relationship of T EQ-related PCDD/Fs to CIPhs is so close that even predictive partial least- squares (PLS) modeling is feasible. In view of our results, some aspects of the mechanism of PCDD/F formation are discussed. From a practical point of view, the results suggest that CIPhs may be a good surrogate of TEQ-relate d PCDD/Fs in different incineration processes.