| Summary: | 碩士 === 逢甲大學 === 環境工程與科學所 === 90 === Recognizing that waste-derived chlorine and sulfur can enhance heavy metal emissions by forming volatile metallic chlorides or sulfides during simulated municipal solid waste (MSW) incineration. This study thus investigated the effect of activated carbon fiber (ACF) on the adsorption of heavy metals in a fixed-bed incineration system. The results of the chloride and sulfide effects indicated that the potential for the metals chloride and sulfide formation show an increasing tendency. Based on the effectiveness of metals adsorption by ACF, the capture efficiency of refractory volatile metals (Cu and Cr) was high by ACF, and the amount of adsorption increases with waste-derived chlorine and sulfur content. In the case of without chlorine and sulfur, the adsorption rates of Pb, Zn and Cd may achieve to 65%, respectively. However, the adsorption rate of tested metals will decrease significantly as the waste-derived chlorine and sulfur content increased. On the other hand, the volatile metals, As and Hg, were captured in the most part to the fly ash. The capture efficiencies of Hg and As were 50% and 100%, respectively.
Due to the characteristics of ACF, the removal mechanisms of heavy metals using ACF included capture, sieve, and adsorption. Comparison with the removal efficiency between the ACF and quartz fiber (QF), the results of metals removal efficiency indicated that the ACF was better than QF. In the case of Zn, the capture efficiency of ACF increased 83.3 fold than QF. For the zinc chloride and sulfide, the ACF，s capture efficiency also achieved 17~25 fold than QF，s. The removal efficiency of highly volatile Cd increased above 5.4 fold under the any tested conditions. With regard to the heavy metals with a refractory volatility, such as Cu and Cr, were hard to capture using ACF. Therefor, the removal effectiveness only increased 0.6 to 10.1 fold.
To assess the reutilization /regeneration of ACF, the heavy metal evaporation in the ACF, at 150℃~250℃, was determined. In this study, experiments at 150℃ show that about 86.4% of the Cd was deadsorbed. The deadsorption efficiency of Zn (90.6%) was also better than other tested metals at temperature 250℃. The deadsorption efficiency of Cu and Cr was found that an increase in temperature from 150℃ to 250℃ will increase the deadsorption efficiency ranging from 50% to 60%. However, the variation of deadsorption efficiency for medium volatile metal (Pb) was significant. The Pb deadsorption efficiency was increased (ranging from 50% to 80%) with temperature increased (from 150℃ to 250℃). As a result of the removal and deadsorption efficiency, ACF was shown to enhance feasibility of adsorption material for the removal of heavy metals from incineration flue gas.
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