title: Biodegradation of naphthenic acids in oils sands process waters in an immobilized soil/sediment bioreactor.
abstract: Aqueous extraction of bitumen in the Alberta oil sands industry produces large volumes of oil sands process water (OSPW) containing naphthenic acids (NAs), a complex mixture of carboxylic acids that are acutely toxic to aquatic organisms. Although aerobic biodegradation reduces NA concentrations and OSPW toxicity, treatment times are long, however, immobilized cell reactors have the potential to improve NA removal rates. In this study, two immobilized soil/sediment bioreactors (ISBRs) operating in series were evaluated for treatment of NAs in OSPW. A biofilm was established from microorganisms associated with sediment particles from an OSPW contaminated wetland on a non-woven textile. At 16 months of continuous operation with OSPW as the sole source of carbon and energy, 38±7% NA removal was consistently achieved at a residence time of 160 h at a removal rate of 2.32 mg NAs L(-1)d(-1). The change in NA profile measured by gas chromatography-mass spectrometry indicated that biodegradability decreased with increasing cyclicity. These results indicate that such treatment can significantly reduce NA removal rates compared to most studies, and the treatment of native process water in a bioreactor has been demonstrated. Amplification of bacterial 16S rRNA genes and sequencing using Ion Torrent sequencing characterized the reactors' biofilm populations and found as many as 235 and 198 distinct genera in the first and second bioreactor, respectively, with significant populations of ammonium- and nitrite-oxidizers.
authors.affiliation: Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada.
authors.forename: Natalie
authors.initials: N
authors.lastname: McKenzie
authors.affiliation: Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada.
authors.forename: Siqing
authors.initials: S
authors.lastname: Yue
authors.affiliation: Psychiatry, Queen's University, Kingston, ON K7L 3N6, Canada.
authors.forename: Xudong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Polyferm Canada Inc., RR1, Harrowsmith, ON K0H 1V0, Canada.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Ramsay
authors.affiliation: Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada. Electronic address: juliana.ramsay@chee.queensu.ca.
authors.forename: Juliana A
authors.initials: JA
authors.lastname: Ramsay
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D002264:Carboxylic Acids / Q000032:analysis / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D019015:Geologic Sediments / Q000737:chemistry* / Q000382:microbiology; D056186:Metagenomics; D061329:Oil and Gas Fields; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D017423:Sequence Analysis, RNA; D012988:Soil Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D002264:Carboxylic Acids; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; C046170:naphthenic acid
keywords: Biodegradation; Biofilm community; Naphthenic acids; Oil sand process water