Stabilization/solidification of contaminated sediments: challenges and novelties
Résumé
Sediments contamination by organic and inorganic pollutants presents a serious risk to human health, fauna and flora. Stabilization/solidification (S/S) is one of the most used technics for the management of contaminated sediments. It aims to improve the mechanical and geochemical properties of contaminated sediments by adding cementitious materials. Cement hydration enhances workability, mechanical resistance, cohesion and decrease the permeability of contaminated sediments. Consequently, the inorganic contaminants (e.g. heavy metals) are physically immobilized by decreasing: i) the available surface area of reactive grains and ii) decreasing the contact time between oxidizing agents and reactive grains (enhancing surface runoff). Moreover, the contaminants are also chemically immobilized by: i) their uptake during cement hydration and ii) their precipitation as low-solubility secondary products (e.g. oxyhydroxides). However, contaminants can be remobilized if: i) the physical properties of stabilized sediments are altered due to climatic conditions and/or ii) the geochemical conditions become acidic which may lead to the dissolution of the precipitated contaminants-bearing phases. The efficiency of S/S technology may vary from laboratory to field scale.
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