Heavy Metals Leaching from the Incinerator Bottom Ash Used for Road Pavement

Abstract

This study analyzed the bonding strength of each kind of heavy metals by simulating the influence of pressure and acid rain when recycling incineration bottom ash from real factory as road building materials. Experimental results indicated that total leach quantity of heavy metals gradually reduced over time. After contrasting results of sequential extraction, it can be found that bonding forms of most heavy metals are organic matter state and residue state which are difficult to be leached, while the first three states are easy to be leached. The quantity of leach increased at the beginning due to the metal bonding of the first three states. In addition, compared with heavy metals in high pH value (2.88), leach quantity of all heavy metals is the largest in low pH value (1.1). However, different operating pressures have little effect on the leach of heavy metals. But if the aggregate size of bottom ash changes, it can be found that the large specific surface area of bottom ash with fine aggregate size is beneficial for the bottom ash to contact with filter liquor. Hence, leach concentration of heavy metals is higher than the bottom ash with coarse aggregate.