The Effect of Inorganic Chlorides on the Speciation and Distribution of Heavy Metals in Simulated Municipal Solid Waste Combustion System

• Main Authors: Lin, Fang Ling, 林芳玲
• Other Authors: Wang Kuen-Sheng
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/76134343464833584703

碩士 === 國立中央大學 === 環境工程學系 === 84 === The effect of inorganic chloride mainly resulting from sodium chloride in food wastes of Municipal Solid Wastes (MSW) has been studied on the speciation and distribution of metal compounds during the process of combustion. The experiments were conducted, using a tube incinerator and a modular incinerator at various incineration temperatures ranged from 650℃ to 900℃ with sodium chloride concentrations varied from 0% to 8% by weight of the simulated wastes. The resultant bottom ash, flyash, and flue gas analyzed to determine the total metal concentrations of As, Cd, Cr, Cu, Hg, Pb, and Zn. The ashes were also subject to the X-Ray Diffraction (XRD) analysis and Scanning Electron Microscopy (SEM) investigation.The results show that Cr, Cu, Pb, and Zn remain in the bottom ash after burning, while Cd goes onto the flyash; and approximately 100% of Hg volatilized into the incinerator exhaust. However, Arsenic is found both in bottom ash and flyash. The partition of metals among incinerator ashes and flue gas depend on the incineration temperature and the concentration of sodium chloride in the wastes. An increase in incineration temperature and/or concentration of sodium chloride will both increase the partition ratio in the flyash, thus relatively decreasing the partition in the bottom ash. The difference in metal contents of the MSW, however, shows little effect on the partition among ashes and the incinerator exhaust. The metal speciation and surface structural characteristics identified by XRD and SEM indicates that most metal compounds are formed as oxides other than chlorides. The existence of potassium chloride in bottom ash and flyash suggests that the competition occurs among potassium and other metals tested in this study.