The leaching behavior of incinerator bottom ash as affected by accelerated ageing

Different artificial ageing treatments were applied to fresh incinerator bottom ash with the aim of promoting/accelerating the natural reactions occurring over time on the mineral phases in the material. The weathering treatments included accelerated carbonation, treatment with air and treatment with nitrogen gas. Both fresh and treated bottom ashes were characterized for their mineralogical composition, acid neutralization capacity and leaching behavior of metals. The results were compared to those obtained from similar characterization of bottom ash samples weathered under atmospheric conditions for 4 years. The findings from the experimental campaign indicated that both the release of metals and the type of solubility-controlling solid phases varied as a function of the duration and type of ageing treatment. The most appreciable influence on mineralogy, acid neutralization behavior and metal leaching was observed for the 48 h carbonation treatment. It was also observed that 4-day aeration of bottom ash was capable of producing similar buffering behavior to that displayed by naturally aged bottom ash. (C) 2004 Published by Elsevier B.V.