Indicator parameters for PCDD/PCDF from electric arc furnaces
Öberg, T.
Chemometrics and Intelligent Laboratory Systems 73, 29-35 (2004)
Abstract
The unintentional formation and release of persistent organic pollutants (POP)
from industrial sources is of environmental concern and efforts are now made to
reduce these emissions [The Stockholm Convention on persistent organic
pollutants; United Nations Environment Programme: Geneva, 2001]. The emissions
of chlorinated trace organics from electric arc furnaces (EAF) have been
monitored on a regular basis in Sweden since the 1980s. Most analyses have
encompassed not only polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans
(PCDF), but also chlorinated benzenes and phenols. Emissions of
2,3,7,8-substituted PCDD/PCDF from municipal solid waste incinerators (MSWI) can
be modelled and predicted from analyses of chlorinated benzenes and phenols,
which are suspected to be precursors in the formation process. The purpose of
this investigation was to extend and update previously reported models with new
samples from EAF, to describe the main sources of variation and to compare
multivariate calibration with univariate regression. The measurement data
consisted of 27 samples collected between 1987 and 2002 and analysed by two
different laboratories. A general multivariate calibration model was able to
describe 96% of the variation in the toxic equivalent quantity (TEQ) value over
five orders of magnitude. Univariate regression models cannot account for
changes in the congener pattern and thus gave a poorer performance. In
plant-specific applications, the univariate approach did, however, perform
equally well. It was therefore concluded that both multivariate and univariate
regression models can be used in process optimisation studies, but that
multivariate models are better suited for emission monitoring and evaluation of
removal efficiencies in the off-gas cleaning systems.
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