Natural and anthropogenic nanoparticles are widely spread into the environment, and in particular in groundwater, representing a concrete risk for human health. On the other hand, injections into the subsurface of reactive suspensions of engineered micro- and nanoparticles (e.g. zerovalent iron, iron oxides, etc) have been studied in recent years for the remediation of contaminated aquifers. Consequently, understanding and modelling transport and deposition of colloidal particles in saturated porous media is a key aspect in both short-term (design of a field-scale injection) and long-term (spreading in the environment) prediction of particle distribution. Nanoparticle transport in porous media is usually described by a modified advection-dispersion equation that takes into account the mass exchanges between liquid and solid phase due to physical and physico-chemical interactions. The interaction kinetics, resulting in particle deposition onto and release from the solid matrix, have been proven to be strongly influenced by both operative, e.g. injection flow-rate [1, 6], and natural conditions, e.g. pore-water ionic strength [3, 4]. These parameters can substantially vary according to the field of application and the involved subsurface formations (e.g. NZVI injected in contaminated aquifers, nanoparticles released leachate from a landfill, nanoparticles injected in a reservoir for enhanced oil recovery, etc.). Up to date, modelling of colloid transport in the presence of such complex interaction phenomena has been mainly faced in one-dimensional Cartesian coordinates for the simulation of laboratory column tests [4], or at larger scales in simplified radial domains [5]. A numerical solution to 1D Cartesian and radial colloid transport equations was implemented by the authors in MNMs (www.polito.it/groundwater/software/MNMs.php). In this work the modeling tool MNM3D is developed for the simulation of nanoparticle injection and transport in more complex scenarios. MNM3D is a modified version of the well-known transport model RT3D [2], in which the colloid transport equations and the dependencies of the attachment and detachment kinetic coefficients on transients in pore water ionic strength and velocity have been implemented. The approach is validated comparing the simulation results of MNMs and MNM3D run on one-dimensional and 2D (radial symmetry) domains. Finally the simulation of an hypothetical spill of wastewater containing graphene oxide nanoparticles is presented to show an example of the long-term evaluation of the final fate of particles in the environment using MNM3D. The work is co-funded by the FP7 EU projects AQUAREHAB (g.a. 226565) and NANOREM (g.a. 309517).

Modelling the injection and the long-term fate of nanoparticle suspensions in groundwater / Bianco, Carlo; Tosco, TIZIANA ANNA ELISABETTA; Sethi, Rajandrea. - STAMPA. - (2016). (Intervento presentato al convegno XI Convegno Nazionale del Gruppo di Geoscienze e Tecnologie Informatiche tenutosi a Torino nel 13-15 giugno 2016).

Modelling the injection and the long-term fate of nanoparticle suspensions in groundwater

BIANCO, CARLO;TOSCO, TIZIANA ANNA ELISABETTA;SETHI, RAJANDREA
2016

Abstract

Natural and anthropogenic nanoparticles are widely spread into the environment, and in particular in groundwater, representing a concrete risk for human health. On the other hand, injections into the subsurface of reactive suspensions of engineered micro- and nanoparticles (e.g. zerovalent iron, iron oxides, etc) have been studied in recent years for the remediation of contaminated aquifers. Consequently, understanding and modelling transport and deposition of colloidal particles in saturated porous media is a key aspect in both short-term (design of a field-scale injection) and long-term (spreading in the environment) prediction of particle distribution. Nanoparticle transport in porous media is usually described by a modified advection-dispersion equation that takes into account the mass exchanges between liquid and solid phase due to physical and physico-chemical interactions. The interaction kinetics, resulting in particle deposition onto and release from the solid matrix, have been proven to be strongly influenced by both operative, e.g. injection flow-rate [1, 6], and natural conditions, e.g. pore-water ionic strength [3, 4]. These parameters can substantially vary according to the field of application and the involved subsurface formations (e.g. NZVI injected in contaminated aquifers, nanoparticles released leachate from a landfill, nanoparticles injected in a reservoir for enhanced oil recovery, etc.). Up to date, modelling of colloid transport in the presence of such complex interaction phenomena has been mainly faced in one-dimensional Cartesian coordinates for the simulation of laboratory column tests [4], or at larger scales in simplified radial domains [5]. A numerical solution to 1D Cartesian and radial colloid transport equations was implemented by the authors in MNMs (www.polito.it/groundwater/software/MNMs.php). In this work the modeling tool MNM3D is developed for the simulation of nanoparticle injection and transport in more complex scenarios. MNM3D is a modified version of the well-known transport model RT3D [2], in which the colloid transport equations and the dependencies of the attachment and detachment kinetic coefficients on transients in pore water ionic strength and velocity have been implemented. The approach is validated comparing the simulation results of MNMs and MNM3D run on one-dimensional and 2D (radial symmetry) domains. Finally the simulation of an hypothetical spill of wastewater containing graphene oxide nanoparticles is presented to show an example of the long-term evaluation of the final fate of particles in the environment using MNM3D. The work is co-funded by the FP7 EU projects AQUAREHAB (g.a. 226565) and NANOREM (g.a. 309517).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2674397
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