PCB dechlorination enhancement in Anacostia River sediment microcosms |
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Authors: | Valdis Krumins Joong-Wook Park Eun-Kyeu Son Lisa A Rodenburg Lee J Kerkhof Max M Hggblom Donna E Fennell |
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Affiliation: | aDepartment of Environmental Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, NJ 08901, USA;bDepartment of Biochemistry and Microbiology, Biotechnology Center for Agriculture and the Environment, Rutgers, The State University of New Jersey, 76 Lipman Drive, New Brunswick, NJ 08901, USA;cInstitute of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Road, New Brunswick, NJ 08901, USA |
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Abstract: | In situ treatment of PCB contaminated sediments via microbial dechlorination is a promising alternative to dredging, which may be reserved for only the most contaminated areas. Reductive dechlorination of low levels of weathered PCB mixtures typical of urban environments may occur at slow rates. Here, we report that biostimulation and bioaugmentation enhanced dechlorination of low concentration (2.1 mg PCBs/kg dry weight) historical PCBs in microcosms prepared with Anacostia River, Washington, DC, sediment. Treatments included electron donors butyrate, lactate, propionate and acetate (1 mM each); alternate halogenated electron acceptors (haloprimers) tetrachlorobenzene (TeCB, 25 μM), pentachloronitrobenzene (PCNB, 25 μM), or 2,3,4,5,6-PCB (PCB116, 2.0 μM); and/or bioaugmentation with a culture containing Dehalococcoides ethenogenes strain 195 (3 × 106 cells/mL). Dechlorination rates were enhanced in microcosms receiving bioaugmentation, PCNB and PCNB plus bioaugmentation, compared to other treatments. Microcosm subcultures generated after 415 days and spiked with PCB116 showed sustained capacity for dechlorination of PCB116 in PCNB, PCNB plus bioaugmentation, and TeCB treatments, relative to other treatments. Analysis of Chloroflexi 16S rRNA genes showed that TeCB and PCNB increased native Dehalococcoides spp. from the Pinellas subgroup; however this increase was correlated to enhanced dechlorination of low concentration weathered PCBs only in PCNB-amended microcosms. D. ethenogenes strain 195 was detected only in bioaugmented microcosms and decreased over 281 days. Bioaugmentation with D. ethenogenes strain 195 increased PCB dechlorination rates initially, but enhanced capacity for dechlorination of a model congener, PCB116, after 415 days occurred only in microcosms with enhanced native Dehalococcoides spp. |
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Keywords: | Polychlorinated biphenyls Biostimulation Bioaugmentation Dehalococcoides |
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