Distribution of dioxins, furans and coplanar PCBs in solid products generated from the pyrolysis and melting of automobile shredder residues

Polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) and coplanar PCBs in slag and char from automobile shredder residue (ASR) were analyzed to observe any changes in characteristics and distribution of their congeners by the pyrolysis and melting process. In char, solid product from ASR pyrolysis, lack of air caused a higher concentration of PCDFs than that of PCDDs, and a large quantity of Co-PCB existed in low chlorinated isomers. The concentration of PCDDs/PCDFs in char was 0.542ng/g, and the toxicity equivalent concentration was 0.072 ng-TEQ/g, and those of Co-PCBs were 0.869 ng/g and 1.579 pg-TEQ/g, respectively. The melted slag of char was fabricated by different cooling methods: water quenching, air cooling and slow cooling. Concentration distributions of PCDDs/PCDFs. were 1.513, 1.376, 2.432 pg-TEQ/g, respectively, and those of Co-PCBs were 0.004, 0.005, 0.010 pg-TEQ/g, respectively. There was only a slight change in the distribution of congeners between the different cooling methods. By the melting procedure of char, the concentration of PCDDs/PCDFs was reduced by 95.3 % and their TEQ concentration was reduced by 97.9 %. Thus, we could confirm that the melting process is an efficient way of ensuring almost free PCDDs/PCDFs.