Chlorophenols as Precursors of PCDD/Fs in Incineration Processes:  Correlations, PLS Modeling, and Reaction Mechanisms

Emissions of organic chlorinated compounds from municipal waste incineration, in particular polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), have been a cause of public concern for many years because of the high toxicity of these compounds. PCDD/F formation in incineration processes is being studied widely using lab-scale apparatus, but pilot-plant investigations are quite rare. The correlation between TEQ-related PCDD/Fs and chlorophenols (ClPhs) was studied here using a pilot-scale plant. The results suggest that almost all the ClPh 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-ClPh, are of importance in the particle phase. The relationship of TEQ-related PCDD/Fs to ClPhs 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 ClPhs may be a good surrogate of TEQ-related PCDD/Fs in different incineration processes.