PCDD F IN FLUE-GAS AND IN BOTTOM ASH OF LIGNITE DOMESTIC COMBUSTION AND THE ROLE OF THE SALT CONTENT OF THE BURNED BRIQUETTES/

Lignite briquettes with different salt contents (''normal''-coal: 300 ppm w/w, ''salt''-coal: 2000 ppm w/w) were burned in a common type of a house heating facility. The content of polychlorodibenzodioxins and furans (PCDD/F) in the flue gas and in the bottom ash were determined. The values calculated from the homologue sums were significantly high er for the ''salt''-coal briquettes regarding their flue gas concentra tions and slightly increased in respect to the bottom ashes. Taking in account a wide variety of additional analytical parameters and consid ering mechanistic aspects, our assumtion was proved that the higher ch lorine content of the ''salt''-coal briquettes is responsible for thes e increased values. The evaluation of the homologue profiles and the i somer distribution shows that the mechanism of the formation of PCDD/F in the flue gas is similar for both coal sorts; whereas, however, the formation of these compounds in the bottom ashes occurs under differe nt conditions. Based on the quantitative results, an assessment of lig nite domestic heating as source of PCDD/F is given. (C) 1997 Elsevier Science Ltd.