Superfund Research Program
Integrating Microbial Biostimulation and Electrolytic Aeration to Degrade POPs
Project Leader: Harold D. May
Grant Number: R01ES016197
Funding Period: 2008-2011
Integrating Microbial Biostimulation and Electrolytic Aeration to Degrade Persistent Organic Pollutants (POPs) was aimed at developing new and novel ways to degrade POPs, in this case polychlorinated biphenyls or PCBs, in sediment. PCBs are a notoriously recalcitrant mixture of pollutants and this is often due to a lack of the pertinent microbial catalysts, electron donor and electron acceptor. To effectively achieve a high degree of degradation, a combination of anaerobic dechlorinating and aerobic degrading microorganisms are required. The Principal Investigators (PIs) had proposed to determine which combination of anaerobic and aerobic (or microaerophilic) microbial catalysts would be most suitable, whether the microbes could successfully be bioaugmented to the sediment, and how to deliver sufficient electron donor and acceptor to these microbial catalysts within the sediment. For the latter the PIs proposed to examine the use of electrolysis to deliver electron donor and acceptor to the microorganisms within the sediment. Experiments were conducted with sediment from Baltimore and Charleston Harbors but also from Superfund Sites including that of Fox River in Wisconsin.
Overall the suitable PCB degrading microorganisms were identified, bioaugmentation tests proved successful, in situ monitoring tools were successfully used to monitor the microbial catalysts, and electrolysis was successfully employed to deliver electron donor and acceptor to the microorganisms. In fact, both the bioaugmentation and electrolysis studies resulted in 60 to 80% removal of weathered PCBs from Superfund sediments within a few months, an unprecedented level of PCB degradation under in situ conditions. The work has been published or is in the process of being published and some of the technology is being applied to in situ tests to actually treat PCB contaminated sediment.