| MW (medical wastes) have rapidly increased in recent years due to the development of the healthcare facilities, and the rise of people's medical service demands. Therefore the disposal of MW has aroused more and more widespread concern. As MW include infectious wastes, Among current available medical waste disposal technologies, pyrolysis-incineration has been found to be the most effective way to destroy the infectious and toxic components, and provide volume and weight reduction. At present, physical and chemical characteristics of MW in China are limited, and incineration technology is not satisfactory. Based on this research background, this paper carried out a basic study on the physical-chemical and pyrolysis-incineration characteristics of medical wastes, expecting to provide valuable reference to further study.In this paper, the physical and chemical characteristics of MW including generation rate, volume density, physical composition and Cl, F content were studied. The influence of hospital types and sizes on the composition of MW was discussed based on the survey in different hospitals. A initial database of medical waste characteristics was established to serve related researches and the MW managemen, such as the selection of medical supplies, the collection and disposal of MW.With the application of TG-FTIR, the thermogravimetric behavior and gas production characteristics of typical medical waste components were analyzed in both pyrolysis and burning condition. Specifically for PVC-containing plastics, the influence from the atmosphere, composition, gas flow rate, heating rate:and other factors was discussed. From the study, an in-depth understanding about pyrolysis-incineration characteristics of MW was obtained.In order to determine the effect of components and chlorine contents of medical waste on the distribution of PCDD/Fs, the medical waste pyrolysis-combustion experiment on single component, two components, and different chlorine contents was conducted in this paper. The study on the distribution characteristics of PCDD/Fs indicates that plastics containing different chlorine contents are different in both the generation of PCDD/Fs and the concentration of chlorinated congeners. The formation of PCDD/Fs is enhanced and the higher chlorinated congener get a noticeable increase when PVC and fiber combusted together, and the influence is different for the different PVC. The amounts of HxCDF, HpCDF, and OCDF increase when the chlorine level raise. And there is no significant correlation between the total chlorine level in the fuel and the emission level of PCDD/Fs. But when the chlorine content is up to 1.73%, the yield of PCDD/Fs has a conspicuous increase. Furthermore, when PVC is different in the medical wastes combusted, the formation characteristics of PCDD/Fs is different though the chlorine content in the wastes is the same. |
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