Application of pyrogenic carbonaceous product for immobilisation of potentially toxic elements in railway sleepers and polluted soil

In the last decades, there is a growing concern about soils polluted with potentially toxic elements (PTE) and their negative impact on the ecosystems. In the recent year, biochar is intensively investigated not only for carbon sequestration or soil productivity enhancement but also like a new sorbent for polluted soils' remediation. The aim of this work is: (1) to assess the effect of two pine wood biochar types (produced at 450 and 700 degrees C temperatures) on the PTE mobility in the solution of the former sewage sludge soil; (2) to make risk assessment of pyrogenic carbonaceous product made from railway sleepers and (3) to assess pine wood biochar (700 degrees C) impact on the PTE uptake to oat (Avena sativa L.). Three different experiments were done: (1) incubation; (2) leaching and (3) bioaccumulation. Incubation experiment showed that both pine wood biochar types showed good immobilisation efficiency in the case of Cd (>85%), but lower temperature biochar (450 degrees C) had higher efficiency used in the immobilisation of Zn (78%) and Cu (76%) in multi-polluted soil. Leaching experiment showed that both biochar types well retained Pb (>99%), but lower temperature biochar had greater retention efficiency in the case of Cu (93%).