ENVIRONMENTAL DECHLORINATION OF PCBs

Brown, J. F.; Wagner, Robert E.; Feng, Helen; Bedard, Donna L.; Brennan, Michael J.; Carnahan, James C.; May, Ralph J.

doi:10.1897/1552-8618(1987)6[579:edop]2.0.co;2

Cited by 90 publications

(181 citation statements)

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“…In general, this microbial process effects the preferential removal of meta and para chlorines, resulting in a depletion of highly chlorinated PCB congeners with corresponding increases in lower chlorinated, ortho-substituted PCB congeners. The altered congener distribution of residual PCB contamination observed in several aquatic sediments was the earliest evidence of the anaerobic dechlorination of PCBs (11)(12)(13). This same activity has been observed in the laboratory (14)(15)(16), where the selective removal of meta and para chlorines was also noted.…”

Section: Pcb Biodegradationmentioning

confidence: 54%

Aerobic and anaerobic PCB biodegradation in the environment.

Abramowicz

1995

Environ Health Perspect

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Studies have identified two distinct biological processes capable of biotransforming polychlorinated biphenyls (PCBs): aerobic oxidative processes and anaerobic reductive processes. It is now known that these two complementary activities are occurring naturally in the environment. Anaerobic PCB dechlorination, responsible for the conversion of highly chlorinated PCBs to lightly chlorinated ortho-enriched congeners, has been documented extensively in the Hudson River and has been observed at many other sites throughout the world. The products from this anaerobic process are readily degradable by a wide range of aerobic bacteria, and it has now been shown that this process is occurring in surficial sediments in the Hudson River. The widespread anaerobic dechlorination of PCBs that has been observed in many river and marine sediments results in reduction of both the potential risk from and potential exposure to PCBs. The reductions in potential risk include reduced dioxinlike toxicity and reduced carcinogenicity. The reduced PCB exposure realized upon dechlorination is manifested by reduced bioaccumulation in the food chain and by the increased anaerobic degradability of these products. -Environ Health Perspect 103(Suppl 5): 97-99 (1995)

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Section: Pcb Biodegradationmentioning

confidence: 54%

Aerobic and anaerobic PCB biodegradation in the environment.

Abramowicz

1995

Environ Health Perspect

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“…However, metals become mobilised again when sediments are resuspended in aerobic surface water. Biodegradation rates of highly halogenated organic compounds, like polychlorinated biphenyls and hexachlorobenzenes, are higher in anaerobic organic rich sediments compared with degradation under aerobic conditions (Brown et al 1987;Mohn and Tiedje 1992). Therefore, storage and natural attenuation (naturally occurring biodegradation) of these halogenated compounds in anaerobic sediments can reduce their bioavailability and concentration, respectively.…”

Section: Introductionmentioning

confidence: 99%

Nonylphenol mass transfer from field-aged sediments and subsequent biodegradation in reactors mimicking different river conditions

et al. 2009

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Purpose Sediments can function as secondary source for water pollution of aerobically biodegradable nonhalogenated organic compounds, which are persistent in anaerobic sediments. The mass transfer of compounds from sediment to bulk water depends on hydraulic conditions. In this study, desorption, mass transfer and biodegradation are investigated under settled and resuspended sediment conditions for branched nonylphenol (NP), which was used as model compound for aerobically biodegradable and anaerobic persistent compounds. Materials and methods Continuous flow through reactor experiments were performed in duplicate with aged NP polluted sediment under sterile and non-sterile conditions to investigate the mass transfer and combined mass transfer and biodegradation. Results and discussion The mass transfer of NP from the sediment bed to the bulk water decreased from 5.1± 0.6 μg d -1 to a stable value of 0.3±0.02 μg d -1 . The desorbed NP in the non-sterile reactors was biodegraded in the first 20 days of the experiment. At the end of the settled sediment conditions, the biodegradation became very limited, and the mass transfer was comparable to the mass transfer under sterile conditions. Upon resuspension, the NP concentration in the bulk water increased instantaneously in all reactors with a factor of 100. This immediate, increased mass transfer of NP from the sediment was larger than the amount that can be biodegraded under optimal conditions. Under non-sterile conditions, a second increase in the mass transfer was observed. However, the amount of desorbing NP during this second increase in mass transfer can be biodegraded under optimal environmental conditions. Conclusions NP desorbs continuously at low concentrations from the sediment bed into the bulk water, which can almost be completely biodegraded. Resuspension of NP-polluted sediment initially led to an increase in the desorbing NP concentrations and can be followed by a subsequent reduction of the concentrations due to biodegradation under environmental conditions where biodegradation of NP can occur.

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“…One of the more promising PCB bioremediation strategies is sequential anaerobicaerobic treatment (1). Under anoxic conditions, highly chlorinated congeners can often be reductively dechlorinated (8,25), resulting in congeners that can potentially be degraded by aerobic bacteria. The lightly chlorinated congeners (one to five chlorines) remaining after reductive dechlorination can be either utilized as an aerobic growth substrate (12,16) or cometabolically degraded in the presence of biphenyl (9,14).…”

mentioning

confidence: 99%

Microbial Growth on Dichlorobiphenyls Chlorinated on Both Rings as a Sole Carbon and Energy Source

Sang-Goo

Picardal

2001

Appl Environ Microbiol

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We have isolated bacterial strains capable of aerobic growth on ortho-substituted dichlorobiphenyls as sole carbon and energy sources. During growth on 2,2-dichlorobiphenyl and 2,4-dichlorobiphenyl strain SK-4 produced stoichiometric amounts of 2-chlorobenzoate and 4-chlorobenzoate, respectively. Chlorobenzoates were not produced when strain SK-3 was grown on 2,4-dichlorobiphenyl.Although bioremediation is an effective cleanup strategy for many contaminants, efforts to engineer bioremediation systems for polychlorinated biphenyl (PCB)-contaminated soils or sludges have been largely ineffective. One of the more promising PCB bioremediation strategies is sequential anaerobicaerobic treatment (1). Under anoxic conditions, highly chlorinated congeners can often be reductively dechlorinated (8,25), resulting in congeners that can potentially be degraded by aerobic bacteria. The lightly chlorinated congeners (one to five chlorines) remaining after reductive dechlorination can be either utilized as an aerobic growth substrate (12, 16) or cometabolically degraded in the presence of biphenyl (9,14).With few exceptions (5, 10), anaerobic PCB dechlorination rarely occurs at the ortho positions and generally results in accumulation of ortho-or ortho-and para-substituted congeners (19,21,27,28). Interestingly, ortho substitution of a PCB also greatly reduces aerobic biodegradability (4, 13). As reported by Furukawa (11), PCB isomers with two ortho chlorines, such as 2,2Ј-dichlorobiphenyl (2,2Ј-CB) or 2,6-CB, are rarely susceptible to aerobic cometabolic degradation. As a consequence, limited aerobic degradation of ortho-substituted congeners is a weak link in the development of effective anaerobic-aerobic PCB bioremediation strategies. Possible accumulation of ortho-substituted congeners such as 2,2Ј-CB may also have ecological and human health implications (7,22).Although numerous reports have shown that monochlorobiphenyls can serve as growth substrates (2,3,6,17,18,23), reports of unambiguous growth by natural isolates on CBs has been demonstrated only for Burkholderia sp. strain LB400 (20). To the best of our knowledge, growth on a di-ortho-substituted CB has not been demonstrated. Here we report the isolation and characterization of unique bacteria capable of using as growth substrates ortho-substituted CB congeners with chlorine substituents on both rings, including an isolate able to utilize 2,2Ј-CB.The CB-degrading bacteria were isolated from PCB-contaminated, tertiary lagoon sludge as previously described (16). One isolate (SK-3) was selected based on its ability to grow on both 4-chlorobiphenyl and 4-chlorobenzoic acid (4-CBA) (16). Another isolate (SK-4) was ultimately enriched and selected based on an ability to grow on 2,2Ј-CB.Cell growth and biotransformation of CBs were studied in Balch tubes sealed with Teflon-coated stoppers as reported previously (16). Experiments were done in a mineral salts medium (16) which was amended with 5 or 10 l of a solution of a single PCB congener dissolved in heptamethylnonane (...

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ENVIRONMENTAL DECHLORINATION OF PCBs

Cited by 90 publications

References 0 publications

Aerobic and anaerobic PCB biodegradation in the environment.

Aerobic and anaerobic PCB biodegradation in the environment.

Nonylphenol mass transfer from field-aged sediments and subsequent biodegradation in reactors mimicking different river conditions

Microbial Growth on Dichlorobiphenyls Chlorinated on Both Rings as a Sole Carbon and Energy Source

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