Speciation Analysis Of Heavy Metal In Municipal Solid Waste Incineration Fly Ash

In the present city life garbage disposal methods, burning down becomes the main method for that it could be able to better realize the reducing of volume, harmless and turning to resources. In our country, garbage was not precisely sorted which contained much harmful heavy metal matter. The end products of the incineration are ash (bottom ash and fly ash) and flue gas. The fly ash is the primary carrier of the heavy metals and their compounds. The final disposal of the fly ash is to landfill or to be used as construction material. The side effect is that by corrade and erode action, the metals especially the volatilizable ones would stand a good chance to re-enter the environment and then do harm to the balance of the nature.The sequential chemical extraction (SCE) method is one effective method for cognition of environment behavior of metals. Using this method, the metal toxicity of municipal solid waste incineration (MSWI) fly ash will not only depend on their total content, but also relate to transferring and transforming behavior of different forms of metals in the environment. Based on results of SCE, different existing forms of metals in MSWI fly ash can be understood to provide scientific basis for the treatment and utilization of MSWI ashes.This paper takes incinerator flash ash of Jinan harmless processing factory as sample. A research of microwave digestion process of municipal solid waste incineration fly ash sample is developed. The purpose of the research is to improve the reagent selection and microwave heating process. The improved reagent is HNO₃: HF: HClO₄=3: 4: 1 and the improved microwave heating process is 3min (5×101kPa), 3min (10×101kPa), 4min (15×101kPa), 6min (20×101kPa). The RSD of this method is 1.2%-4.5% and the recovery is 95.9%-103.7%. The results indicated that the improved method could be used in municipal solid waste incineration fly ash samples and yielded highly desirable results.This paper use BCR method to extract different fraction of heavy metal, analyses heavy metal fraction in MSWI ashes. The results shows that the contents of extracted heavy metal Cu,Pb,Zn,Mn and Fe in fly ash are higher than these in bottom ash,flue ash and acid cleaning ash, the contents of extracted heavy metal Cr in bottom ash is higher than its in flue ash,acid cleaning ash and fly ash.The result of analysis on the contents of heavy metals in various size fraction of MSWI fly ash shows that, the contents of heavy metal Cr have only a little relativity with various size fraction in MSWI fly ash. In bottom ash samples, the contents of heavy metals Cu,Pb,Zn and Mn have an increasing trend with the size reduction, the contents of heavy metal Fe have only a little relativity with various size fraction. In flue ash samples, the contents of heavy metals Cu and Fe have an increasing trend with the size increase, the contents of heavy metal Pb,Zn and Mn have only a little relativity with various size fraction. In acid cleaning ash, the contents of heavy metals Pb and Fe have an increasing trend with the size increase, the contents of heavy metal Cu,Zn and Mn have only a little relativity with various size fraction. In fly ash, the contents of heavy metals Zn have an increasing trend with the size reduction, the contents of heavy metal Cu,Pb,Mn and Fe have only a little relativity with various size fraction.