Correlation of PCDD/F and PCB at combustion experiments using wood and hospital waste. Influence of (NH4)2SO4 as additive on PCDD/F and PCB emissions

Abstract

The objectives of this work were to study the emissions of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/F) and polychlorinated biphenyl (PCB) during the combustion of wood, wood and hospital waste as well as wood, hospital waste and (NH4)2SO4 in a pilot plant and to determine the relation of the toxic emissions to the fuel properties. The presence of PVC (experiments b and c) increases PCDD/F and PCB formation compared to burning only eco-farm wood (a). However, analysis and quantification of PCDD/F and PCB showed that the amount of 5% of (NH4)2SO4 in the fuel mixture significantly impacted the dioxins emissions and suppressed it by approximately 50%. In addition, longer duration of the combustion experiment by using (NH4)SO4 resulted in a stronger inhibition of the toxic emissions. Overall, the lowest values were observed during the combustion of the fuel blends containing wood only. Relationships of PCDD/F (WHO-TEQ) and individual congeners of WHO-PCDD/F, WHO-PCB and six PCB indicator congeners were also found. As a result, all single PCB congeners were identified as PCDD/F (WHO-TEQ) surrogates in the flue gas. Furthermore, the correlation between PCDD/F and PCB congeners was examined by statistical methods such as cluster analysis (CA). Closely neighboured pairs on the dendrogram were additionally confirmed by a high linear coefficient of determination (R2). (NH4)2SO4-containing samples did not affect the correlations between PCDD/F and PCB at the concentrations given.