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

如果对报废货物（固体废物）处理不当，货物中的重金属将扩散到环境中。这将最终导致（1）高环境风险和（2）宝贵资源的损失。因此，在固体废物管理系统中应给予重金属更高的优先地位。固体废弃物的处理和回收过程是商品生命周期的最后阶段，也是决定重金属是否释放到环境中的关键阶段。因此，选择何种工艺进行固体废物处理具有重要意义。本研究以估算固体废弃物管理系统中的重金属流量、定量评价重金属的环境负荷和可回收性为目的，调查了日本常用的固体废弃物回收处理工艺。（1）热处理工艺（焚烧、灰熔融、气化熔融）：通过分析底灰、飞灰、炉渣等产出物，明确了各设施中重金属的行为。（2）回收工艺（RDF、堆肥、生物气化设施）：研究了各设施中重金属在产品和残渣中的分配比例。（3）材料回收工艺（可回收物的分离回收设施、家电产品的回收设施、大宗废弃物的材料回收设施）：通过对产出物成分的分析，明确回收成分和分离残渣中的重金属。（4）根据上述调查结果，计算可燃性废弃物、不可燃性废弃物和食品废弃物中的重金属含量。并且，通过将每种生活垃圾成分的金属含量乘以排放量来估算重金属的流量。(5)To评价了各处理设施对环境的影响，并对各处理设施的产出物进行了重金属浸出试验。估算了生活垃圾管理各方案的重金属流量和环境效应。

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.