Estimation of the dioxin emission (PCDD/FI-TEQ) from the concentration of low chlorinated aromatic compounds in the flue and stack gas of a hazardous waste incinerator

The concentrations of hexa- and pentachlorobenzene in the flue gases of waste incinerators are known to be strongly correlated with the emission of polychlorinated dibenzo-p-dioxins/furans PCDD/F, measured in international toxicity equivalents, I-TEQ. In this work it was investigated whether polychlorinated benzenes (PCBz) with a lower degree of chlorination and mono- and dichlorinated dibenzo-p-dioxins/furans can be used for estimation of the dioxin emission (I-TEQ) in the flue gases of hazardous waste incinerators (HWI). The HWI process consists of a primary oxidative pyrolysis step in a rotary kiln followed by a post-combustion of the pyrolysis gases. The investigation indicated, that lower chlorinated PCDD/F homologues are very weakly correlated with the dioxin emission (I-TEQ) and thus are probably not useful as indicator parameters. In contrast to this finding, mono- to trichlorobenzenes are present in relatively high amounts in flue and stack gases and are correlated with the PCDD/F I-TEQ value. The mono- to dichlorinated benzenes can be readily detected by a laser mass spectrometric technique (REMPI-TOFMS) and thus are candidates for a direct on-line measurement in the flue gas and a continuous, indirect monitoring of the dioxin emission. (C) 1999 Elsevier Science B.V. All rights reserved.