Integration of ecotoxicity index and carboxylic of MSW incineration bottom ashes.

In France, MSW incineration bottom ash disposal calls for physico-chemical tests and depending on the results the bottom ashes are sorted into different classes allowing the reuse or not. However this study shows that there is no direct correlation between the physico-chemical testings, like leaching, soluble fraction and heavy metal content, and the environmental impact, in terms of biological toxicity. Based on the results of several ecotoxicity testings and their biotest response we define an "ecotoxicity index" and demonstrate there is a correlation between the carboxylic acids amount and the ecotoxicologic index for the bottom ashes. This clearly shows that at least organic carbon characterisation in the bottom ash is needed in addition to leaching and physico-chemical testings if one wants to have a coherent sorting procedure for the bottom ashes.