Leachability of elements in municipal, sewage sludge and industrial incineration ashes using a sequential extraction method

A stable supply of raw materials required for industrial development and production of everyday goods is one of the major challenges for economies nowadays. EU countries are highly dependent on supplies which currently are extracted in only a few countries worldwide. It is also expected that the prices of industrially important raw materials will fluctuate, depending on the supplier policies. Growing concerns of mineral resources supplies on one hand, and the sustainable economy, where protection of natural resources is one of the key goals on the other hand, force us to search for alternative sources of economically important elements. For this reason, waste stream materials: municipal waste incineration ashes, sewage sludge incineration ashes and industrial incineration ashes were studied. The rational use of incineration wastes as a source of economically important materials requires detailed mineralogical and chemical characterization and evaluation of their recovery and leaching potential since they might contain both, important and potentially toxic for the environment elements. To maximize the extraction rates of valuable elements such as phosphorus and/or to minimize the leachability of potentially hazardous elements (e.g. As, Cr, Cd, Cu, Pb, Zn) a three-step sequential extraction procedure in accordance with the Community Bureau of Reference (BCR; Standards, Measurements and Testing Program) was implemented to characterize the content of trace elements and heavy metals, bonds and potential bioavailability of studied ashes. Leachates were analyzed using ICP methods. Mineralogical methods (XRD and SEM-EDS) were applied to study the composition of starting materials and post extraction solid samples. Efficiency of the proposed extraction method was strongly dependent on incineration technology, types of incinerated waste, bulk chemical composition and mineralogy of ashes that influenced their solubility and thus leaching efficacy.

Acknowledgment. This publication has been funded from the Anthropocene Priority Research Area budget under the program "Excellence Initiative – Research University" at the Jagiellonian University.