Trace element leaching from contaminated willow and poplar biomass - A laboratory study of potential risks

Despite the advantages of phytoextraction, serious risks can be caused by the produced contaminated biomass. Currently, there is a lack of research on the potential risk of storing and handling this biomass. The aim of our study was to verify the losses of potential risk elements (Cd, Cu, Fe, Mn, Pb, Zn) via leaching of short rotation coppice biomass in laboratory batch tests. Harvested woody and leafy biomass was chipped and/or kept compact. The fresh and/or dried biomass was then leached by two types of leachate to simulate rainfalls-neutral water and/or acidified water. Chipped wood was characterised by the highest element release in comparison to whole branches. The leaves were considered more risky from the point of view of element losses. A similar trend of leaching was observed for all elements, except iron. More iron was leached from fresh wood biomass, whilst in the case of the leaves, iron was leached more from dry biomass. Lead was released by 1.4-7.2% from the biomass. Cadmium was leached by 2% from woody biomass, but up to 39% from leaves. The potential losses of these elements during storage and pre-processing should be taken into account in the development of methodologies for the storage and handling of contaminated biomass before its' processing.