title: Pressure-controlled injection of guar gum stabilized microscale zerovalent iron for groundwater remediation.
abstract: The paper reports a pilot injection test of microsized zerovalent iron (mZVI) dispersed in a guar gum shear thinning solution. The test was performed in the framework of the EU research project AQUAREHAB in a site in Belgium contaminated by chlorinated aliphatic hydrocarbons (CAHs). The field application was aimed to overcome those critical aspects which hinder mZVI field injection, mainly due to the colloidal instability of ZVI-based suspensions. The iron slurry properties (iron particles size and concentration, polymeric stabilizer type and concentration, slurry viscosity) were designed in the laboratory based on several tests (reactivity tests towards contaminants, sedimentation tests and rheological measurements). The particles were delivered into the aquifer through an injection well specifically designed for controlled-pressure delivery (approximately 10 bars). The well characteristics and the critical pressure of the aquifer (i.e. the injection pressure above which fracturing occurs) were assessed via two innovative injection step rate tests, one performed with water and the other one with guar gum. Based on laboratory and field preliminary tests, a flow regime at the threshold between permeation and preferential flow was selected for mZVI delivery, as a compromise between the desired homogeneous distribution of the mZVI around the injection point (ensured by permeation flow) and the fast and effective injection of the slurry (guaranteed by high discharge rates and injection pressure, resulting in the generation of preferential flow paths). A monitoring setup was designed and installed for the real-time monitoring of relevant parameters during injection, and for a fast determination of the spatial mZVI distribution after injection via non-invasive magnetic susceptibility measurements.
authors.affiliation: Dipartimento di Ingegneria dell'Ambiente, del Territorio e delle Infrastrutture-Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Luna
authors.affiliation: Dipartimento di Ingegneria dell'Ambiente, del Territorio e delle Infrastrutture-Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Gastone
authors.affiliation: Dipartimento di Ingegneria dell'Ambiente, del Territorio e delle Infrastrutture-Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Tosco
authors.affiliation: Dipartimento di Ingegneria dell'Ambiente, del Territorio e delle Infrastrutture-Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy. Electronic address: rajandrea.sethi@polito.it.
authors.forename: R
authors.initials: R
authors.lastname: Sethi
authors.affiliation: VITO, Boeretang 200, 2400 Mol, Belgium; Department of Environmental Geosciences, University of Wien, Althanstrasse 14, 1090 Wien, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Velimirovic
authors.affiliation: VITO, Boeretang 200, 2400 Mol, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Gemoets
authors.affiliation: VITO, Boeretang 200, 2400 Mol, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Muyshondt
authors.affiliation: SAPION, Oude Bevelsesteenweg 51, 2560 Nijlen, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Sapion
authors.affiliation: VEGAS, University of Stuttgart, Pfaffenwaldring 61, 70569 Stuttgart, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Klaas
authors.affiliation: VITO, Boeretang 200, 2400 Mol, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Bastiaens
mesh_terms: D001530:Belgium; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005685:Galactans / Q000737:chemistry*; D060587:Groundwater; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry*; D053149:Plant Gums / Q000737:chemistry*; D011312:Pressure; D012212:Rheology / Q000379:methods; D012996:Solutions; D014783:Viscosity; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D005685:Galactans; D006843:Hydrocarbons, Chlorinated; D008351:Mannans; D053149:Plant Gums; D012996:Solutions; D014874:Water Pollutants, Chemical; D007501:Iron; C007894:guar gum
keywords: Chlorinated aliphatic hydrocarbons; Field scale mZVI injection; Guar gum; Low pressure injection; Microscale zerovalent iron (mZVI); Monitoring setup