Objective

Removal of polychlorinated biphenyls (PCBs) from contaminated aquatic sediments is a priority because of their ability to enter the food chain and their toxic and carcinogenic properties. Presently, the approved remediation methods mainly include dredging and capping. 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 because of PCB stability, low bioavailability, and the low abundance and activity of naturally occurring PCB-degrading microorganisms. 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 them as a microbial inoculum delivery system provides a novel approach to address PCB contamination.

The objectives of this SERDP Exploratory Development (SEED) project are to (1) demonstrate that biofilms (made up by dense populations of PCB-degrading bacteria) associated with a surface can be utilized to obtain enhanced microbial PCB degradation and (2) develop a delivery system with activated carbon particles covered with an active microbial biofilm inoculum that will sequester PCBs from the surrounding aqueous sedimentary environment as well as enhance PCB degradation.