Hot rolling sludge incineration: Suppression of PCDD/Fs by spent anion exchange resins

The off-gas released by sludge and resin co-combustion was also monitored and the residue analysed by Energy Dispersive Spectrometer (EDS); the results revealed that the SO2 concentration in the off-gas was higher during co-combustion than when burning HRS only. Likewise, the sulphur content in the combustion residue rises with resin addition. Still, the suggestion that suppression of PCDD/F formation should be ascribed to the poisoning of catalytic metal by S-containing compounds seems to be invalidated by the high initial S/Cl-ratio of HRS, even before SAER addition. These surprising findings were further analysed by a scrutiny of fingerprints obtained at the five distinct dosages tested. The relative amount of 2,3,7,8-PCDD/F was remarkably depressed by inhibitor addition and the relative importance of the chlorophenols route strongly expanded. Several reaction schemes, showing the results of further signature analysis are presented and are expected to throw more light on the mechanism of formation and its suppression.