Modelling the Transport in Porous Media of Iron Micro and Nanoparticles for Groundwater Remediation

Event

Macdonald Engineering Building Room 497, 817 rue Sherbrooke Ouest, Montreal, QC, H3A 0C3, CA
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In the framework of groundwater remediation, the injection of nanoscale and microscale zerovalent iron particles (NZVI and MZVI, respectively) for the generation of reactive zones represents a promising remediation technology for the treatment of contamination sources and dissolved plumes. To improve colloidal stability and mobility in the subsurface, the use of biopolymers is usually required. Polymers are dosed in low concentrations to modify surface properties and increase particle-particle repulsion (mainly for NZVI) or in high concentration to form shear-thinning fluids preventing particle sedimentation and improve delivery (mainly for MZVI). Nanoparticle (NP) transport in porous media is controlled by particle-particle and particle-collector interactions, typically modelled with kinetic terms of deposition onto the porous medium and corresponding release. Ionic strength, flow rate and fluid viscosity all play a major role in determine the interactions between particles and porous medium, and therefore deposition and release mechanisms and kinetics. This talk presents a modelling approach to simulate NP transport in porous media at laboratory and field scale, under space- and time-variable ionic strength and flow velocity. The key aspects considered here are the influence of salt concentration on attachment and detachment kinetics, clogging phenomena, and the rheological properties of the carrier fluid. The model was derived using a semi-empirical approach, based on laboratory results (colloidal stability, rheological characterization of the slurries, column transport tests) and up-scaled for the simulation of large-scale scenarios. Applications to the analysis of laboratory transport tests, to the preliminary design of NP-based remediation intervention, and to the prediction of long-term fate of NPs in the environment will be presented.