Stabilized materials from contaminated waste recycling : characterization, immobilization, and leaching of contaminants

The contamination of soils, sediments, and industrial wastes from both heavy metals and organic pollutants is recognised as a very important environmental problem, highlighting the need to improve or develop effective remediation techniques to support sustainable management strategies. In particular, the High Performance Solidification/Stabilization process is a S/S treatment specifically addressed to the production of a granular material reusable as building material. In this context, it is fundamental to understand the mechanisms involved in the retention and leaching of potentially hazardous contaminants from the granular material produced, to both improve their performances and develop new processes for the sustainable management of contaminated matrixes. This Ph.D. thesis focuses on the characterization of several stabilized granular materials obtained from the application HPSS® process by means of analytical techniques such as Inductively Coupled Plasma Mass and Optical Emission Spectrometry (ICP-MS and ICP-OES), Ultraviolet–Visible spectroscopy (UV-Vis), Gas Chromatography (GC), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The results obtained were helpful to elucidate the mechanisms, mineralogical phases, and key parameters regulating the solidification/stabilization performances of the different binders used in the treatment of different contaminated matrixes. Moreover, a new integrated process for heavy metals’ recovery from stabilized matrixes through alkaline soil washing, nanofiltration and heavy metals’ chemical precipitation was developed and tested. The overall experimental activity led to the draft of four manuscripts that are discussed in detail in this thesis.