The Study On Transfer And Control Mechanism Of Heavy Metals In Hazardous Waste Incineration

Having the advantages of remarkable volume-reduction, weight-reduction, small floor area and energy recovery, disposing of Municipal Solid Waste (MSW) and Hazardous Waste by incineration has been widely used abroad, especially applied by those developed countries which are facing the insufficiency of land and energy. This technology is also being popularized in our country in recent years. The heavy metals in municipal solid waste and hazardous waste will be distributed and transformed in the course of incineration without being destroyed. The total amount will be sent out of the furnace as much as that is contained in raw waste. The fly ash and bottom after incineration still contain harmful concentrated heavy metals. Since the metals are water leachable, the fly ash and bottom ash which are usually defined as hazardous waste must be treated.Focused on the fact that the study concerned with the hazardous waste is only on its initial step, this paper, gets started with the definition of hazardous waste, and introduces and analyzes in details such aspects as the source and harm of heavy medals in hazardous waste, the transfer and conversion characteristics of heavy medals while disposing of hazardous waste by incineration, as well as the impact factors. This thesis also gives an investigation about the physical-chemical property, leaching characteristic of heavy metals and the stabilization method of fly ash and bottom ash of Medical Waste. It offered useful reference for people to deepen the correct treatment and its importance of disposing the hazardous waste and established a firm bases on reducing the toxicity of heavy metals in hazardous waste incineration.The physical and mechanical property, heavy metals content and the distribution of particle size of Medical Waste fly ash and bottom ash are analyzed at first by Scanning Electron Microscope, Energy Dispersive X-ray Detector, X-ray Diffraction and Atom Absorbing Spectrum respectively. The results indicate the fly ash has complex component and also includes a lot of chlorine. The content of heavy metals in fly ash and bottom ash were more, and need to be further properly treated. Then, the leaching characteristics of Medical Waste fly ash and bottom ash were studied and the effect of single variable leachate situation is also considered. To sum up, the leaching characteristics of fly ash and bottom ash also indicate a similar trend, and the leaching rate of Cd was very higher. The leaching of heavy medals was furthest influenced by pH, and in the alkalescent environment the leaching of heavy medals was less. Besides, the leaching rate and the content of heavy medals have no obvious relation.In the foundation of comparing with the current stabilization method and based on the particularity of Medical Waste fly ash and bottom ash, the thermal melting process was adopt to solidify the Medical Waste fly ash and bottom ash. The leachate after solidification all reduce a little, and attained the GB totally, which had a little...