Distribution characteristics and formation mechanisms of PCDD/Fs during pyrolysis and gasification of municipal solid waste.

Pyrolysis gasification (PG) technology is a promising waste disposal technology, which is more efficient and cleaner compared with incineration technology. However, few work has studied the generation characteristics of polychlorinated dibenzo-p-dioxin and furans (PCDD/Fs) and the influencing factors in the PG process. This study investigates the effects of air ratio (AR) and gasification temperature on the generation and distribution of PCDD/Fs during the PG process of municipal solid waste (MSW). PCDD/Fs mainly distribute in the gas- and oil-phase. PCDD/Fs are generated highest levels at 0.3-AR and 700 °C (477.0 ng/g MSW and 44.4 ng I-TEQ/g MSW), which could be attributed to the generation of PCDD/F precursors enhanced by the promotion of oxidation reactions. Gasification temperature positively correlates with PCDD/F generation and generates the highest concentrations of PCDD/Fs at 0.2-AR and 800 °C (57.6 ng/g MSW and 5.0 ng I-TEQ/g MSW). In addition, the increased temperature promotes the generation of high-chlorinated congeners through the chlorination pathway. By adjusting the key parameters of temperature and AR, the inhibition and distribution of PCDD/F generation in the MSW PG process can be effectively regulated.