Thermal removal of PCDD/Fs from medical waste incineration fly ash – Effect of temperature and nitrogen flow rate

The fly ash used in this study was collected from a bag filter in a medical waste rotary kiln incineration system, using lime and activated carbon injection followed by their collection as mixed fly ash. Experiments were conducted on fly ash in a quartz tube, heated in a laboratory-scale horizontal tube furnace, in order to study the effect of temperature and nitrogen flow rate on the removal of PCDD/Fs. Results indicated that in this study PCDD/Fs in the fly ash mostly were removed and desorbed very little into the flue gas under thermal treatment especially when the heating temperature was higher than 350 °C, and dechlorination and destruction reactions took important part in the removal of PCDD/Fs. However, in terms of flow rate, when flow rate was higher than 4 cm s−1, destruction efficiency of PCDD/Fs decreased dramatically and the main contributors were P5CDF, H6CDF and H7CDF desorbed to flue gas, the PCDD/Fs in the fly ash decreased with enhanced flow rate.

Research highlights
► PCDD/Fs in fly ash are mostly be removed in this study.
► Dechlorination and destruction reactions take important part in PCDD/Fs removal.
► Removal efficiency of the PCDD/Fs decreased when flow rate is high at 4 cm s−1.