| Having the advantages of volume-reduction, weight-reduction and energy-recovery, incineration plays an important role in the disposal and utilization of municipal solid waste (MSW) and has been widely used abroad. Nowadays this technology is being popularized gradually in our country. However, the release of toxic substances such as heavy metals from MSWI fly ash will bring environmental problems. So MSWI fly ash should be treated before being landfilled.The emphasis of this study is on the fundamental experiment of the leaching behavior of heavy metals from fly ash which is from co-firing coal with MSW(municipal solid waste) in fluidized bed incinerator, and solidification in treating MSWI fly ash by mixing with asphalt and additives (S and NaOH).TCLP experiments have been performed to study the relationships between liquid-to-solid ratio (L/S), initial pH value, extraction time and leaching characteristics of heavy metals (Pb, Cr, Cd, Ni, Cu, Zn) in fly ash.The influence of mAs/mpA on the immobilization of heavy metals (Pb, Cr, Cd, Ni, Cu, Zn, Hg) was investigated. In addition, potential application of MSWI fly ash in asphalt concrete was studied simply.Considering the effect of solidification, the volume-change and the cost of disposal, the mixture (mAs/mFA =0.2) was further studied. For studying the effect of additives on immobilization, different mass of additives (sulfur and sodium hydroxide) were mixed with mixture of fly ash and asphalt based on the typical proportion. In order to evaluate the effect of solidification to fly ash in different leaching condition, the further leaching experiments about the fly ash mixture #l(mAs/mFA-0.2 , ms/mAS+FA=0.067 , mNaOH/ms=1.2) and the fly ash mixture #2 (mAs/mFA=0..2 , ms/mAs+FA =0.1? niNaOH/ms =1.2) were performed. Moreover, the comparison between heavy metals leachability from fly ash, the mixture of fly ash and asphalt (mAs/rnFA=0.2) and the fly ash mixture #1 and #2 was made. |
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