Inhibition of PCDD/F by adding sulphur compounds to the feed of a hazardous waste incinerator

State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou, Zhejiang Province 310027, China.
Chemosphere (Impact Factor: 3.34). 11/2011; 86(4):361-7. DOI: 10.1016/j.chemosphere.2011.10.016
Source: PubMed


Sulphur compounds, including (NH(4))(2)SO(4) and pyrite, were tested as suppressants in a hazardous waste incineration facility. The test results suggested that adding sulphur compounds only slightly reduced PCDD/F stack emissions; this restricted effect was attributed to the release of fly ash in large amounts during the sulphur adding experiments, i.e., it was due to a malfunctioning of the baghouse filter. Nevertheless, for the combined flow of flue gas+fly ash a reduction of more than 50% was achieved for the total PCDD/F concentrations and the total toxic concentrations, and an even higher inhibition capability was observed for PCDD. Also, a simulation of the thermodynamic equilibrium conditions by sulphur dioxide was conducted in the domain of experimental interest. Deactivation of catalysts, which promote PCDD/F formation, was found to be the dominant inhibition mechanism in low temperature PCDD/F formation. SO(2) could also inhibit the formation of molecular Cl(2) via the Deacon reaction, but that was not the main reason for inhibition.

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    • "Remarkably, during the two tests with a joint injection of 500 ppm NH 3 and 500 ppm SO 2 a negative reduction for the sum PCDD/Fs was observed. Although a clear decrease in the concentrations of PCDD/Fs occurred when either 500 ppm NH 3 or 500 ppm SO 2 was injected (Ruokojärvi et al., 1998; Ke et al., 2010; Wu et al., 2012), only 0.3% of PCDD/Fs reduction was achieved in these experiments when they were injected together. The experiments were conducted in duplicate and the results were well reproducible, with values for the standard variation of 11% for PCDD, 8%% for PCDF and 16% for I-TEQ. "

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