Heavy Metal Flow in Solid Waste Management System and Evaluation of Environmental Effect

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Heavy metals in goods will be dispersed to the environment if end-of-life goods (solid waste) are treated inadequately. This will eventually result in (1)high environmental risk and (2)valuable resource loss. Heavy metals should therefore be given higher priority in solid waste management system. Treatment and recycling process of solid waste is last stage in goods' life cycle and also critical stage to determine whether heavy metals are released to the environment or not. So, it is significant which process is selected for solid waste management. This study aimed to estimate heavy metal flow in solid waste management system and to evaluate quantitatively environmental burden and recyclability of heavy metals.All recycling and treatment processes of solid waste commonly used in Japan were investigated. (1)Thermal treatment processes (incineration, ash-melting, gasification-melting) : Behavior of heavy metal in each facility was identified clearly by analyzing outputs such as bottom ash, fly ash, and slag. (2)Recycling processes (RDF, composting, bio-gasification facility) : Distribution ratio of heavy metals to products and residues in each facility was investigated. (3)Material recovery processes (separation and recovery facility of recyclable waste, recycling facility of home electrical appliances, material recovery facility of bulky waste) : Heavy metals in recovered component and separation residues were clarified through analysis of output component (4)Based on the results obtained in the above investigation, heavy metal content in combustible waste, incombustible waste, and food waste was calculated. And, the flow of heavy metals was estimated by multiplying metal content of each household waste composition by discharge amount. (5)To evaluate environmental effect, leaching test of heavy metal from outputs of each treatment facility was performed. The heavy metal flow and environmental effect for each scenario of household waste management was estimated.