Application of an organic-mineral biocomposite for sustainable remediation of post-industrial soil contaminated with potentially toxic elements (PTEs).

Numerous technological innovations have been developed for managing post-industrial soils, but assisted phytostabilization-a sustainable and environmentally friendly approach-has attracted significant global interest. This study evaluates the effectiveness of a novel biocomposite, composed of fish waste compost and chalcedonite, in assisting the phytostabilization of soil contaminated with potentially toxic elements (PTEs), using Lolium perenne L. (perennial ryegrass) as a test plant. The results demonstrated that the biocomposite significantly increased soil pH (by 0.19 units), organic carbon content (by 174.3%), improving soil fertility by increasing nutrient availability (available P by 219.6%, and available K by 146.9%), and plant growth. Additionally, it promoted PTE accumulation in the roots while reducing Pb (44%), Zn (24%), Cu (23%), and Ni (14%) concentrations in the aerial parts, as well as Cd (71%), Ni (33%), and Cu (29%) levels in the soil. The biocomposite also altered the fractionation of PTEs, reducing their mobility and bioavailability. Specifically, it decreased the exchangeable fraction (F1) by 45% for Cu, 71% for Cd, 41% for Pb, and 24% for Zn, effectively limiting their environmental risk. Moreover, it promoted the redistribution of Pb and Zn into the reducible fraction (F2), Cu and Pb into the oxidizable fraction (F3), and Cu, Ni, and Cd into the residual fraction (F4), indicating enhanced stabilization. The highest immobilization efficiencies were observed for Cd (53.9%) and Pb (52.3%), confirming the biocomposite's effectiveness in reducing PTE mobility. These findings highlight the potential of biocomposite amendments in remediating PTE-contaminated soil by improving soil physicochemical properties, reducing PTE bioavailability, and enhancing phytostabilization efficiency. This approach supports sustainable waste valorization and circular economy principles, offering a promising strategy for rehabilitating post-industrial lands with high PTE contamination.