| Accelerated economic development and enhanced living standards in China have led to the generation of more municipal solid wastes (MSW). The application proportion of incineration technology has been increased year by year because of its advantages such as volume reduction, mass reduction and toxicity reduction. However, incineration also has its problems such as PCDD/Fs emission, which are toxic compounds produced from MSW incineration. So it has been the key problem which restricted the development of incineration in China.This dissertation launched a series of experimental study, which aims at the formation mechanism and inhibition technologies of PCDD/Fs produced from MSW incineration. The objectives of the current research involved as follows:(1) The method of the PCDD/Fs pretreatment and detect based on high resolution gas chromatograph /high resolution mass spectrum has been built up.(2) The heterogeneous catalyzed reaction in fly ash with two typical precursors, which is pentachlorophenol (PCP) and tri-chlorinated benzene (TrCB), has been studied in a tubular furnace. The PCDD/Fs emission characteristic and several influence factors were discussed detailedly. Compared with PCP, TrCB was the less active precursor for PCDD/Fs.(3) The de novo synthesis reaction was studied with fly ash which has been treated with different method. Results of these experiments showed that the organic chlorine in inextractable C-Cl bonds was the most effective chlorine, the organic chlorine was the secondly chlorine and the total chlorine was the least chlorine for PCDD/Fs formation. The correlations between the physical and chemical properties of fly ash and PCDD/Fs were analyzed by using the principal component analysis (PCA). The results of PCA showed there was a positive correlation between PCDD/Fs levels with its I-TEQ, the surface area of fly ash and chlorine content. The ph value, the iron and zinc content of fly ash were founded a negative correlation with PCDD/Fs. However, carbon and copper in fly ash did not have a noticeable relationship with PCDD/Fs levels in fly ash.(4) The different destruction technologies were used for PCDD/Fs in solid, liquid and gas phases. The effects of temperature, atmosphere, time and the species of fly ash on PCDD/Fs distribution in fly ash were studied in a tubular oven under low temperature. It was shown that the destruction rate of PCDFs was higher than PCDDs. It was necessary to take measures for removal of PCDD/Fs in gas phase when treated fly ash containing high levels dioxins during Hagenmaier process. The destruction rate of PCDD/Fs levels and I-TEQ values in fly ash were 91.70%, 98.84 % respectively when fly ash was heated in a sealed tube. The photolysis of OCDD and OCDF by Ultraviolet was studied by using multi-functional photochemical reactor. The experimental results showed the photolysis rate of OCDD and OCDF in n-hexane solvent fit a first-order reaction . The preferential loss of the chlorine atoms on the OCDD were the Iateral(2,3,7,and 8)... |
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