title: Guar gum coupled microscale ZVI for in situ treatment of CAHs: continuous-flow column study.
abstract: A column study was performed under in situ conditions to evaluate to which extend the inactivation of the microscale zerovalent iron (mZVI) by guar gum occurs under continuous flow conditions. Five aquifer containing columns were set up under different conditions. Efficient removal of trichloroethene was observed for the column amended by mZVI. Stabilization of the mZVI with guar gum led to slightly reduced activity. More reduced reactivity was observed in the poisoned column containing guar gum stabilized mZVI. This confirms that soil microorganisms can degrade guar gum and that subsequent removal of the oligosaccharides by the groundwater flow (flushing effect) can reactivate the mZVI. After more than six months of continuous operation the columns were dismantled. DNA-based qPCR analysis revealed that mZVI does not significantly affect the bacterial community, while guar gum stabilized mZVI particles can even induce bacterial growth. Overall, this study suggests that the temporarily decreased mZVI reactivity due to guar gum, has a rather limited impact on the performance of in situ reactive zones. The presence of guar gum slightly reduced the reactivity of iron, but also slowed down the iron corrosion rate which prolongs the life time of reactive zone.
authors: Flemish Institute for Technological Research (VITO), Boeretang 200, 2400, Mol, Belgium; University of Antwerp, Department of Bio-Engineering, Groenenborgerlaan 171, 2020 Antwerp, Belgium. Electronic address: milica.velimirovic@vito.be.
authors: Milica
authors: M
authors: Velimirovic
authors: Flemish Institute for Technological Research (VITO), Boeretang 200, 2400, Mol, Belgium. Electronic address: queenie.simons@vito.be.
authors: Queenie
authors: Q
authors: Simons
authors: Flemish Institute for Technological Research (VITO), Boeretang 200, 2400, Mol, Belgium. Electronic address: leen.bastiaens@vito.be.
authors: Leen
authors: L
authors: Bastiaens
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005685:Galactans / Q000737:chemistry* / Q000378:metabolism; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry* / Q000378:metabolism; D053149:Plant Gums / Q000737:chemistry* / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012988:Soil Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry
chemical_list: D005685:Galactans; D006843:Hydrocarbons, Chlorinated; D008351:Mannans; D053149:Plant Gums; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D000255:Adenosine Triphosphate; D007501:Iron; C007894:guar gum
keywords: Chlorinated aliphatic hydrocarbons; Column tests; Guar gum; Microscale zerovalent iron; Reactive zone