焚烧飞灰卫生填埋共处置的螯合稳定化技术研究

对4种垃圾焚烧飞灰的性质进行了分析,其主要元素以Si、Ca、Al、Cl等为主,此外还含有相当数量的重金属如Pb、Zn、Cu、Cr、Cd等,存在很大的环境风险.而飞灰进入卫生填埋场进行共处置是现实可行的出路,为保证共处置的安全性,针对共处置情景制订的浸出毒性浸出方法提高了浸取液酸强度(0.3 mol·L-1,以H 计),此浸出方法已于2007-05-01日开始执行.采用二硫代氨基甲酸盐(dithiocarbamate)类螯合剂对焚烧飞灰进行了稳定化处理工艺实验,结果表明,DTC类螯合剂通过螯合反应作用于飞灰中的重金属,当DTC类螯合剂投加量为3%(质量分数)时,4种飞灰中重金属的浸出值均能达到在卫生填埋场和垃圾进行共处置的要求.

Chelating Stabilization of Heavy Metals in Fly Ash from Municipal Solid Waste Incinerators for Co-disposal in Sanitary Landfill

The characteristics and leaching behavior of heavy metals in fly ash, sampled from 4 MSWI plants, were investigated in this study. The results indicated that the main elements of fly ash were Si, Ca, Al, Cl, and heavy metals such as lead, zinc, copper, chromium and cadmium were enriched in fly ash which had great environmental risk. However, co-disposal of fly ash in sanitary landfill was an available and practical resolvent. For disposal security, the leaching procedure of toxicity basing on co-disposal scenario, which had been implemented from 1st May 2007, had increased the acidity of leachant to 0.3 mol x L(-1). The experiments of chelating stabilization technology using dithiocarbamate were carried out for MSWI fly ash treatment. The results indicated that heavy metals in fly ash were fixed by DTC in manner of chelating reaction. With the amount of additive reaching 3% (mass fraction), the concentrations of heavy metals in leachate of these fly ash samples could meet the demand of co-disposal in sanitary landfill.