Pollution Properties Of Heavy Metals In Municipal Solid Waste Incineration Fly Ash In Chongqing

With the development of economy, the improvement of people's life level, and the acceleration of city tenor, the environment and cities developmet suffer tremendous pressure and harm due to flood tide municipal solid waste(MSW) landfill. Effective treatment of MSW becomes an important tache in the area of environmental protection. Incineration of MSW landfill is the most direct and the most effective way among all methods of MSW landfill treatments and disposals. It is applied in China more and more widely. But the environmental problem caused by incineration catches extensive attention. The thesis studies pollution properties of nine heavy metals Cd, Cr, Cu, Pb, Zn, Ni, Mn, As, Hg in Chongqing MSWI fly ash, which include distribution, leaching toxicity and effect factors, chemical speciation and so on.Through the study, a series of valuable results are obtained as follow:1. MSWI fly ash in Chongqing exists mainly as less than 75μm grain, and they occupy a half of total mass. Big grain(>250μm) occupy about 3-6%.2. Contents of Pb,Mn in Chongqing MSWI fly ash is much more than other heavy metals. Contents of all heavy metals are higher than soil background value, environmental quality standard for soils and control standards for urban wastes for agricultural use. Chongqing MSWI fly ash has potential danger, and should not to be deposited arbitrarily.3. Heavy metals are easy to be enriched on small grain fly ash. For<250μm fly ash,with the decreasing of grain size, the concentration of heavy metals is increasing. For >250μm fly ash,the concentration of heavy metals also increases. But the distribution of zinic is contrary with above metals. The distribution of Ni has not obvious rule.4. Chongqing MSWI fly ash has not causticity, but has higer basicity.5. Chongqing MSWI fly ash has leaching toxicity. The leaching properties are influenced by pH value, liquid/solid ratio, leaching time. Generally, with the increasing of acidity, the leaching content of heavy metals increases. The leaching content of arsenic is nearly nothing in the condition of acidic, while the leaching is easier in condition of alkalization. With the increasing of liquid/solid ratio, the leaching content of most heavy metals increase;With the increasing of leaching time, the leaching content of Cr, Pb, Mn show ascending trend, while Cd, Ni, Hg show descending trend. 6. Cr, Ni, Mn, Zn in fly ash exist as organic combinative phase and residual phase. Arsenic in fly ash exist as organic combinative phase and Fe-Mn combinative phase. Content of carbonate phase of Cd is high and unstable phase occupy over 80%.7. Content, distribution , leaching properties, chemical speciation of heavy metals in fly ash of different seasons show otherness. But seasonal diversity is not significant, their rules is similar.