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Published on: October 15, 2015
PCB dechlorination enhancement in Anacostia River sediment microcosms
Valdis Krumins1, Joong-Wook Park, Eun-Kyeu Son
1Department of Environmental Sciences, Rutgers-The State University of New Jersey, 14 College Farm Road, New Brunswick, NJ 08901, USA.
Water Research
|September 12, 2009
Summary
Microbial dechlorination offers a promising in situ alternative for treating PCB-contaminated sediments. Biostimulation with specific compounds and bioaugmentation enhanced PCB dechlorination rates and capacity in Anacostia River sediment microcosms.
Area of Science:
- Environmental Science
- Microbiology
- Environmental Chemistry
Background:
- In situ microbial dechlorination is a sustainable alternative to dredging for polychlorinated biphenyl (PCB) contaminated sediments.
- Urban environments often contain low concentrations of weathered PCBs, which may dechlorinate slowly.
- Effective treatment strategies are needed for widespread PCB contamination.
Purpose of the Study:
- To investigate the enhancement of microbial dechlorination of low-concentration PCBs in contaminated sediments.
- To evaluate the effects of biostimulation (electron donors and haloprimers) and bioaugmentation on PCB dechlorination rates and capacity.
Main Methods:
- Microcosms were prepared with Anacostia River sediment containing historical PCBs.
- Treatments included electron donors (butyrate, lactate, propionate, acetate), haloprimers (tetrachlorobenzene, pentachloronitrobenzene, PCB116), and/or bioaugmentation with Dehalococcoides ethenogenes strain 195.
- Dechlorination rates and capacity were assessed over time, with analysis of Dehalococcoides populations.
Main Results:
- Bioaugmentation, pentachloronitrobenzene (PCNB), and PCNB plus bioaugmentation significantly enhanced PCB dechlorination rates.
- Subcultures showed sustained PCB dechlorination capacity in PCNB, PCNB plus bioaugmentation, and tetrachlorobenzene (TeCB) treatments.
- PCNB and TeCB stimulated native Dehalococcoides spp., with PCNB correlating to enhanced dechlorination of weathered PCBs.
- While initial dechlorination was boosted by bioaugmentation with D. ethenogenes strain 195, sustained capacity was linked to enhanced native Dehalococcoides populations.
Conclusions:
- Biostimulation with specific haloprimers, particularly PCNB, can effectively enhance the microbial dechlorination of low-concentration PCBs in contaminated sediments.
- Enhancing native Dehalococcoides populations may be more critical for sustained PCB dechlorination than introducing exogenous strains.
- Optimizing in situ bioremediation strategies requires careful consideration of electron donors, electron acceptors, and native microbial communities.
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