The degradation of PCDD/Fs in fly ash using dielectric barrier discharge in a lab-scale reactor

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash emitted by municipal solid waste (MSW) incinerators are harmful to human health and the environment. Based on the degradation efficiency and application potential of non-thermal plasma (NTP) for gaseous pollutants, a typical lab-scale dielectric barrier discharge (DBD) module was adopted to generate plasma and degrade the PCDD/Fs present in fly ash. In this study, the degradation characteristics of 17 kinds of PCDD/Fs congeners were studied, and the effects of input energy, discharge time and moisture content of fly ash on PCDD/Fs removal efficiency were also discussed in detail. The results indicated that the degradation efficiency of 2378-tetrachlorodibenzo-p-dioxin (2378-TCDD) was the highest among 17 kinds of PCDD/Fs congeners at the same operating condition, and the total degradation efficiency of PCDDs was higher than that of PCDFs. The highest degradation efficiencies of 2378-TCDD, PCDDs and PCDFs acquired in this study could be up to 92%, 83%, and 55%, respectively. A long time of electric discharge was not beneficial to the decomposition of PCDD/Fs, and the moisture content of fly ash affected the degradation of PCDDs more obviously than that of PCDFs. Also, the degradation mechanisms of PCDD/Fs were discussed further. It was discovered from results that the decomposition of PCDFs was mainly attributed to the dissociation of the C-Cl bond, while for that of PCDDs, the dissociation of the C-O bond played a dominant role rather than that of the C-Cl bond.