Remediation of potentially toxic elements in contaminated soils

Abstract

This chapter aims to offer an overview of the main remediation methods of potentially toxic elements in contaminated soils, mainly heavy metals, metalloids and radionuclides, focusing on their essential characteristics, advantages and limitations. It consists of two main groups of technologies: the first group dealing with containment and confinement, minimizing their toxicity, mobility and bioavailability. Containment measures include covering, sealing, encapsulation and immobilization through solidification (cement-based, polyethylene and resine binders, bituminization or asphalt batching and vitrification or glassification) and stabilization with inorganic and organic amendments. The second group, remediation with decontamination is based on the remotion, clean up and/or destruction of contaminants. This group includes mechanical procedures (excavation, transport and disposal to landfills), physical separations, chemical technologies such as soil washing with leaching or precipitation of potentially toxic elements, soil flushing, thermal treatments (desorption, pyrometallurgical processes and incineration) and electrokinetic technologies (electromigration, electroosmosis, electrophoresis and combinations of electrokinetics with other techniques). There are also two approaches of biological nature: bioremediation (biosorption, bioreduction, biomineralization and bioleaching-with some examples from Korea) and phytoremediation (phytoextraction, including chelate-assisted phytoextraction, phytostabilization, phytoremediation in mining activities -with examples from Portugal, Spain, Ecuador, Peru and Chile mainly-, phytovolatilisation and phytomining).