title: Evaluation of peat and sawdust as permeable reactive barrier materials for stimulating in situ biodegradation of trichloroethene.
abstract: Two low cost solid organic materials, sawdust and peat, were tested in laboratory batch microcosm and flow-through column experiments to determine their suitability for application in permeable reactive barriers (PRBs) supporting biodegradation of trichloroethene (TCE). In microcosms with peat, TCE (∼30μM) was sequentially and completely degraded to cis-dichloroethene (cDCE), vinyl chloride, and ethene through reductive dechlorination. In microcosms with sawdust, reductive dechlorination of TCE stopped at cDCE and high methane production (up to 3000μM) was observed. 16S rRNA gene copy numbers of Dehalobacter and Archaea were higher (1000 and 10 times, respectively) in sawdust microcosms than those in peat microcosms. Dehalococcoides and vcrA gene copy numbers were 10 times higher in peat microcosms than in sawdust microcosms. These gene copy number differences are consistent with the extent of TCE degradation and production of methane in the microcosms. Flow-through column experiments showed that hydraulic conductivity reduction with time was consistently greater in the sawdust column compared to the peat column. The greater conductivity reduction was likely due to biofouling and methane gas bubble formation. The experimental observations indicate that peat has potential to be a better solid organic material than sawdust to support reductive dechlorination of TCE in PRB applications.
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Pulin K
authors.initials: PK
authors.lastname: Mondal
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Glaucia
authors.initials: G
authors.lastname: Lima
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Zhang
authors.affiliation: BioZone, University of Toronto, 200 College Avenue, Toronto, Ontario M5S 3E5, Canada.
authors.forename: Line
authors.initials: L
authors.lastname: Lomheim
authors.affiliation: Pinchin Ltd., 2470 Milltower Court, Mississauga, Ontario L5 N 7W5, Canada.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Tossell
authors.affiliation: Pinchin Ltd., 2470 Milltower Court, Mississauga, Ontario L5 N 7W5, Canada.
authors.forename: Paresh
authors.initials: P
authors.lastname: Patel
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada. Electronic address: sleep@ecf.utoronto.ca.
authors.forename: Brent E
authors.initials: BE
authors.lastname: Sleep
mesh_terms: D001105:Archaea; D001673:Biodegradation, Environmental; D005798:Genes, Bacterial; D010459:Peptococcaceae; D012336:RNA, Ribosomal, 16S; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D014241:Trichloroethylene / Q000378:metabolism*; D014934:Wood / Q000737:chemistry*
chemical_list: D012336:RNA, Ribosomal, 16S; D012987:Soil; D014241:Trichloroethylene
keywords: Bioremediation; In-situ treatment; Permeable reactive barriers; Reductive dechlorination; Solid organic materials; Trichloroethene