Zero valent iron remediation of a mixed brominated ethene contaminated groundwater Elizabeth L. Cohen a,b , Bradley M. Patterson a, ⁎, Allan J. McKinley b , Henning Prommer a,c a CSIRO Land and Water, Private Bag No. 5, Wembley WA 6913, Australia b School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia c School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia article info abstract Article history: Received 1 July 2008 Received in revised form 15 September 2008 Accepted 19 September 2008 Available online 30 September 2008 The suitability of a granulated zero valent iron (ZVI) permeable reactive barrier (PRB) remediation strategy was investigated for tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2- dibromoethene (t-DBE) and vinyl bromide (VB), via batch and large-scale column experiments that were subsequently analysed by reactive transport modelling. The brominated ethenes in both batch and large-scale column experiments showed rapid (compared to controls and natural attenuation) degradation in the presence of ZVI. In the large- scale column experiment, degradation half-lives were 0.35 days for TriBE, 0.50 days for c-DBE, 0.31 days for t-DBE and 0.40 days for VB, under site groundwater flow conditions, resulting in removal of brominated ethenes within the first 0.2 m of a 1.0 m thick ZVI layer, indicating that a PRB groundwater remediation strategy using ZVI could be used successfully. In the model simulations of the ZVI induced brominated ethene degradation, assuming a dominant reductive β-elimination pathway via bromoacetylene and acetylene production, simulated organic compound concentrations corresponded well with both batch and large-scale column experimental data. Changes of inorganic reactants were also well captured by the simulations. The similar ZVI induced degradation pathway of TriBE and TCE suggests that outcomes from research on ZVI induced TCE remediation could also be applied to TriBE remediation. © 2008 Elsevier B.V. All rights reserved. Keywords: Groundwater Tribromoethene cis 1,2-dibromoethene trans 1,2-dibromoethene Vinyl bromide 1,1,2,2-tetrabromoethane Permeable reactive barrier Zero valent iron PHT3D 1. Introduction Although extensive research has been undertaken regard- ing methods to remediate trichloroethene (TCE), the bromi- nated analogue tribromoethene (TriBE) has been largely ignored as a soil and groundwater contaminant and to date very little information exists on potential remediation strategies. This limited research is largely due to the small number of cases of environmental contamination by bromi- nated ethane and ethenes reported. Brominated ethane and ethenes contamination has been reported at two ground- water locations (Heitz et al., 1997; Thomas et al., 2004; Patterson et al., 2007) and one terrestrial water location (Grigoriadoua et al., 2008). At one groundwater site, a 230 m long mixed brominated ethene contaminant groundwater plume consist- ing of TriBE, cis-1,2-dibromoethene (c-DBE), trans-1,2-dibro- moethene (t-DBE) and vinyl bromide (VB) that is potentially discharging into a creek, has been reported (Thomas et al., 2004; Patterson et al., 2007). The length of the contaminant plume was reported to be a combined result of the brominated ethene's low retardation coefficients and limited natural attenuation (Patterson et al., 2007). Laboratory and site investigations have shown that the mixed brominated ethene plume is a result of dissolution of the dense non- aqueous phase liquid (DNAPL) 1,1,2,2-tetrabromoethane (TBA) at the presumed source zone, which degraded rapidly (half-life of 0.2 days) to form TriBE (Patterson et al., 2007). TriBE has been shown to be toxic to algae, crustaceans and fish (Canton and Wegman,1983). While there are currently no World Health Organization (WHO) drinking water guidelines for TriBE, limited studies (HSDB, 2004) on human toxicity have Journal of Contaminant Hydrology 103 (2009) 109–118 ⁎ Corresponding author. Tel.: +61 8 93336276; fax: +61 8 9333 6211. E-mail address: bradley.patterson@csiro.au (B.M. Patterson). 0169-7722/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jconhyd.2008.09.010 Contents lists available at ScienceDirect Journal of Contaminant Hydrology journal homepage: www.elsevier.com/locate/jconhyd