title: Concentration effects on biotic and abiotic processes in the removal of 1,1,2-trichloroethane and vinyl chloride using carbon-amended ZVI.
abstract: A permeable reactive barrier, consisting of both zero valent iron (ZVI) and a biodegradable organic carbon, was evaluated for the remediation of 1,1,2-trichloroethane (1,1,2-TCA) contaminated groundwater. During an 888 day laboratory column study, degradation rates initially stabilized with a degradation half-life of 4.4±0.4 days. Based on the accumulation of vinyl chloride (VC) and limited production of 1,1-dichloroethene (1,1-DCE) and 1,2-dichloroethane (1,2-DCA), the dominant degradation pathway was likely abiotic dichloroelimination to form VC. Degradation of VC was not observed based on the accumulation of VC and limited ethene production. After a step reduction in the influent concentration of 1,1,2-TCA from 170±20 mg L(-1) to 39±11 mg L(-1), the degradation half-life decreased 5-fold to 0.83±0.17 days. The isotopic enrichment factor of 1,1,2-TCA also changed after the step reduction from -14.6±0.7‰ to -0.72±0.12‰, suggesting a possible change in the degradation mechanism from abiotic reductive degradation to biodegradation. Microbiological data suggested a co-culture of Desulfitobacterium and Dehalococcoides was responsible for the biodegradation of 1,1,2-TCA to ethene.
authors.affiliation: CSIRO Land and Water Flagship, Private Bag No. 5, Wembley, WA 6913, Australia; School of Chemistry and Biochemistry, University of Western Australia, Crawley, WA 6009, Australia. Electronic address: bradley.patterson@csiro.au.
authors.forename: Bradley M
authors.initials: BM
authors.lastname: Patterson
authors.affiliation: Centre for Marine Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Lee
authors.affiliation: CSIRO Land and Water Flagship, Private Bag No. 5, Wembley, WA 6913, Australia.
authors.forename: Trevor P
authors.initials: TP
authors.lastname: Bastow
authors.affiliation: Scissortail Environment Solutions, LLC. Ada, OK 74821, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Wilson
authors.affiliation: CSIRO Land and Water Flagship, Private Bag No. 5, Wembley, WA 6913, Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Donn
authors.affiliation: CSIRO Land and Water Flagship, Private Bag No. 5, Wembley, WA 6913, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Furness
authors.affiliation: Goodwin Remediation Consulting, Victoria 3018, Australia.
authors.forename: Bryan
authors.initials: B
authors.lastname: Goodwin
authors.affiliation: Centre for Marine Bio-Innovation, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Mike
authors.initials: M
authors.lastname: Manefield
mesh_terms: D001673:Biodegradation, Environmental; D002244:Carbon / Q000737:chemistry*; D041862:Chloroflexi / Q000254:growth & development; D045858:Desulfitobacterium / Q000254:growth & development; D060587:Groundwater / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D014240:Trichloroethanes / Q000032:analysis*; D014752:Vinyl Chloride / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D014240:Trichloroethanes; D014874:Water Pollutants, Chemical; C024567:1,1,2-trichloroethane; D002244:Carbon; D007501:Iron; D014752:Vinyl Chloride
keywords: 1,1,2-TCA; Biodegradation; Chlorinated solvent; PRB; Remediation