Abstract: The effects of electric current density, ratio of liquid to solid and treatment time on the removal of heavy metals from the leaching solution of hospital solid waste incineration (HSWI) fly ash by electrodialysis were studied. The characteristics of HSWI fly ash before and after electrodialysis were analyzed. The results show that 11.1% of Pb, 42.3% of Zn, 56.7% of Cd, 38.7% of Cu and 7.5% of Cr were removed from the raw fly ash by optimizing the electrodialytic parameters at the current density 0.8 mA/cm2, ratio of liquid to solid 10 and treatment time 14 d. Under these conditions, the chlorine level decreased from 20.43% in the raw fly ash to 0.78% in the residual ash, loss on ignition of fly ash increased from 11.1% to 34.3% due to the solubilization of soluble compounds like NaCl after electrodialysis. Although some initially existent heavy metals had been removed from the ash during the electrodialysis, the content of heavy metals actually increased due to mineral dissolution and adsorption of activated carbon powder. The exchangeable fraction and carbonate fraction of these heavy metals in the residual ash decreased, but their leaching concentration was above regulatory thresholds of waste landfill.

Key words: incineration fly ash, leaching solution, heavy metal, electrodialysis, separation

摘要： 采用电渗析法分离医疗垃圾焚烧飞灰浸出液中重金属，考察了电流密度、液固比、处理时间等参数对重金属移除的影响，并分析了电渗析处理对飞灰特性、重金属形态及其浸出毒性的影响. 结果表明，电流密度0.8 mA/cm2、液固比10(w)和处理时间14 d条件下飞灰浸出液中重金属分离效果最好，11.1% Pb, 42.3% Zn, 56.7% Cd, 38.7% Cu, 7.5% Cr被移除，飞灰中大量NaCl被移除，氯含量从20.43%降低到0.78%，热灼减率从11.1%升高到34.3%，可溶态和碳酸盐态重金属含量降低，飞灰基质减少及不可溶态重金属存在导致残灰中重金属含量增加，Pb和Cd浸出浓度仍超过生活垃圾填埋场的阈值.

关键词: 焚烧飞灰, 浸出液, 重金属, 电渗析, 分离