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| Titel |
Field injection of microscale zerovalent iron for groundwater remediation |
| VerfasserIn |
Rajandrea Sethi, Tiziana Tosco, Michela Luna, Francesca Gastone, Milica Velimirovic, Johan Gemoets, Rob Muyshond, Hans Sapion, Norbert Klaas, Leen Bastiaens |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094683
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| Publikation (Nr.) |
 EGU/EGU2014-10111.pdf |
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| Zusammenfassung |
| In the framework of the research project AQUAREHAB (FP7 - G. A. Nr. 226565), a pilot
injection test of guar gum stabilized microsized zerovalent iron has been designed and
performed under low pressure in a CAHs contaminated site in Belgium, characterized by fine
sand (hydraulic conductivity in the order of 2-
10-5m/s) and an effective velocity equal to
0.005 m/day (1). The field application was aimed to overcome those critical aspects which
hinder mZVI particles field injection, mainly due to ZVI-based colloidal suspensions
instability. A shear thinning guar gum solution (2 g/l) was selected as an environmentally
friendly stabilizer.
The relevant properties of the iron slurry (iron particles size and concentration,
polymeric stabilizer type and concentration, slurry viscosity) were designed in the
laboratory based on several tests (namely iron reactivity tests towards contaminants,
sedimentation tests and rheological measurements).The slurry preparation was
successfully up-scaled to the field application, allowing a fast preparation of large
volumes (1 m3 at a time) of slurry with good dissolution of guar gum and effective
dispersion of mZVI. Since the injection regime of iron slurries depends on subsurface
geotechnical parameters, aquifer hydraulic conductivity, and fluid properties, a specific
injection well and monitoring strategy have been developed in order to achieve
high discharge rates and radii of influence, and a more homogeneous distribution
of the iron particles through low pressure injection. The injection well has been
designed and sealed in order to sustain average to high discharge rates, preventing the
daylighting of the product. Moreover the well has been hydraulically tested by means
of innovative water and guar gum step rate tests in order to determine the most
suitable injection rate for the iron slurry. The injection of 50 kg of microsized iron
particles (BASF, Germany), dispersed in 5 m3 of a 2 g/l guar gum suspension, was
performed at a discharge rate of 1.5 m3/h. The monitoring of the process has been
conducted measuring injection rate and pressure as well as iron concentration by
means of a magnetic susceptometer. After the injection, the iron distribution in the
subsurface was determined through liners extraction and the iron concentration
measured both via non-invasive magnetic susceptibility measurements and chemical
analysis.
Even if the field test was specifically designed to inject in a permeation regime, or on the
threshold between permeation and fracturing, the results of monitoring injection pressure and
iron distribution proved that particles migration in the porous medium occurred via
preferential flow. Results will be presented as well as considerations about critical aspects
related to injection via permeation.
References
1. Luna, M.; Gastone, F.; Tosco, T.; Sethi, R.; Velimirovic, M.; Bastiaens, L.;
Gemoets, J.; Muyshond, R.; Sapion, H.; Klaas, N. Pilot injection of guar gum stabilized
microscale zerovalent iron in a shallow aquifer via pressurized well. (in preparation). |
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