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Application of Biofilm Covered Activated Carbon Particles as a Microbial Inoculum Delivery System for Enhanced Bioaugmentation of PCBs in Contaminated Sediment

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Final rept., phase 1

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Objectives The objectives in SERDP project ER-2135 addressed the SERDP Exploratory Development 201SEED202 Statement of Need ERSEED-11-01 In situ remediation of contaminated aquatic sediments. Removal of the class of persistent organic pollutants, polychlorinated biphenyls 201PCBs202, from contaminated aquatic sediments is a priority due to their ability to enter the food chain and their potent toxic and carcinogenic properties. Presently, the approved remediation methods mainly include dredging and capping. However, these techniques are not only expensive, but also result in increased PCB concentrations in the water phase due to resuspension of contaminated sediment particles. While in situ microbial degradation of PCBs would represent a significant improvement in remediation efforts, previous attempts have failed due to PCB stability, low bioavailability and the low abundance and activity of naturally occurring PCB-degrading microorganisms. In order to overcome these negative aspects of microbial degradation, this project evaluated an approach, where anaerobically dechlorinating biofilms were added to sediment as a delivery system either by utilizing bacteria localized and concentrated onto activated carbon surfaces in active biofilm communities or by applying enriched wastewater sludge biofilms. The enhanced effect of biofilms on bioaugmentation was examined in a subsequent mesocosm experiment, where these biofilm communities were applied to PCB contaminated sediment. The high efficiency of activated carbon to quickly adsorb and sequester PCBs from aquatic sediments has previously been demonstrated. Co-localizing PCB-degrading microbes onto the surfaces of activated carbon in the form of biofilms and utilizing it as a microbial inoculum delivery system provides a number of benefits. First, the sequestering capacity of activated carbon further lowers aqueous concentration of PCBs that have leached from sediment. Second, by providing a large population of PCB-

Subject Categories:

  • Inorganic Chemistry
  • Organic Chemistry

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