In situ fixation of metals and metalloids using iron-rich co-products

The present work focuses on the use of Fe-rich co-products, originating from different industrial processes, as fixing agents for heavy metals and metalloids. A series of experiments were performed in microcosms to establish the potential of several coproducts, including red-mud, red gypsum and water sludge, to immobilise heavy metals and arsenic. Several chemical methods were used to determine the mobility of metals with special attention to metal concentration and speciation in soil solution and metal fluxes. Furthermore, the effect of these treatments on various biological endpoints (plants and microorganisms) was investigated in order to assess whether the remediation treatment satisfies the legislative requirements in terms of effects on environmental receptors.