Analysis of the Characteristics of Fly Ash from Hospital Solid Waste Incinerations

With the popularization of the centralized incineration of hospital solid waste in many metropolises of China, a large amount of hospital solid waste incinerator (HSWI) fly ash has generated. Heavy metals and dioxins condensed on fly ash have been posing serious threat to the environment. In order to evaluate the environmental hazards of HSWI fly ash and explore a safety and effective technique, the chemical composition, thermal property, mineralogy, morphology, metal contents and leaching behavior of fly ash etc had been respectively analyzed. The results show that fly ash has higher loss on ignition (LOI) with high content of activated carbon, and they have high contents of chloride, sulphate, alkalis metal which the major crystalline phases are CaSO₄ and NaCl. Moreover, The leaching concentrations of Cd, Zn and Pb in the fly ash exceed the landfill regulatory thresholds of the hazardous waste, the leaching behavior of heavy metals is possibly related to morphology of the irregular sponge-like porous particles with smaller spheres. The HSWI fly ash should be pretreated prior to land in hazardous waste landfill sites.