Secondary formation of chlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls, benzenes, and phenols during MSW combustion

The aim of this study was to investigate how the levels and homologue profiles of organic micropollutants (OMPs) were effected by the so-called secondary formation between 650 and 200 degrees C. The combustion experiments were performed in a laboratory scale reactor fed with an artificial municipal solid waste fuel. The predominance of higher chlorinated OMP homologues after the secondary reaction shows that further chlorination reactions of OMPs formed at higher temperature reactions (>650 degrees C) are more important in the lower temperature range than formation through the elements C, H, O, and Cl (de novo synthesis). Most of the dibenzofuran (DF), dibenzo-p-dioxin (DD), and the biphenyl (BP) are formed at temperatures higher than 650 degrees C. Simultaneously flue gas sampling was taken in the convector section of the reactor at 650 and 200 degrees C, respectively. The samples were analyzed for monoto octachlorinated dibenzo-p-dioxins and dibenzofurans, tetra- to decachlorinated biphenyls, di- to hexachlorinated benzenes, and di- to pentachlorinated phenols. In addition to chlorinated OMPs, nonchlorinated DD, DF, and BP were analyzed.