With very little natural metal resource, Taiwan imports most of the metal minerals for industrial uses and that is obviously unsustainable from a regional perspective. In order to use resource efficiently and reduce the demand of importing metals, recycling or recovering these metals from waste is a necessary and promising practice. Unlike most investigations that focus on toxic effects of heavy metals released from incinerators, this study assesses the recovery potential of metals commonly used and valuable for industries. The partitioning of iron, aluminum, copper, zinc, cadmium, chromium and lead between bottom ash and fly ash was investigated in three large municipal solid waste (MSW) incinerators located in the three largest cities, Taipei, Taichung and Kaohsiung, respectively in Taiwan. The flux of metals that pass through MSW incinerators was then estimated and the potential of metal recovery in MSW incinerators is assessed. The results show that these metals in our investigation can be divided into three groups based on concentration levels: iron and aluminum are the highest in concentration, copper, zinc, and lead are in the middle, and cadmium and chromium are the lowest. There are six metals in our investigation which tend to concentrate in bottom ash except for cadmium. The factors that might affect the distributions, like recycling rate, operation parameters and trash compositions, are discussed as well to explore if there is any regional difference. It is found that there is no obvious regional difference and recycling rates of plastics, rubbers and batteries are highly related to concentration of lead and zinc in fly ash as well as lead and copper in bottom ash. In conclusion, lead and zinc are the potential metals to develop further recovery policy when both concentrations in ash and technological feasibility are considered.

bottom ash and fly ash ,the potential of metal recovery in MSW incinerators