Inhibition of element sulfur and calcium oxide on the formation of PCDD/Fs during co-combustion experiment of municipal solid waste

Abstract

In order to investigate the effect of element sulfur (S) and calcium oxide (CaO) on the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) during municipal solid waste (MSW) combustion process, MSW was incinerated with S or CaO in a laboratory-scale incinerator and heated in the flow of N2-O2 gas mixture at 800°C. It can be concluded that 25% of oxygen concentration is the best condition for the following inhibitors experiments through a series of oxygen variation experiments. With adding S and CaO in MSW incineration, seventeen kinds of 2, 3, 7, 8-substituted PCDD/Fs congeners were analysed with high-resolution chromatography and mass spectrometry method. The results show that S and CaO obviously suppress PCDD/Fs formation. Comparing inhibition effect of S with that of CaO, the inhibitory effect of S on HpCDD/Fs formation was most remarkable, of around 88.1%; while CaO could inhibit the formation of HxCDD/Fs more evidently than sulfur and the inhibition was 85.1%. PCDFs were the main components of dioxins produced from MSW incineration in the experiments, and S and CaO were unable to change the dominating generation route of PCDD/Fs. S and CaO could mainly consume chlorine sources or weaken the chlorination in the PCDD/Fs formation process to restrain the PCDFs formation, but the inhibition mechanisms were different. In addition, some dioxins or precursors might be decomposed by S and CaO.