John F. Kennedy Space Center, Florida A number of NASA centers have used polychlorinated biphenyl (PCB)-containing materials that have subsequently ended up in surrounding sediment systems. Each center is evaluating remediation technologies that may have application to their environmental problems; however, there are only limited options available for application to sediments containing PCBs. Currently, the most utilized option is dredging followed by disposal in a Toxic Substances Control Act (TSCA)-regulated landfill. This is an expensive option with long-term liability implications for simply enacting a waste transfer remedy (as opposed to a waste destruction alternative), as well as possible contaminant re-introduction into the water table. PCB contamination in sediment systems is a global issue, posing ecological and human health risks.
This technology is a new and novel method for the removal and destruction of PCBs found in sediment systems. The concept is a redeployable polymer blanket that attracts and adsorbs PCBs to the blanket in situ. The blanket is hollow, and is filled with ethanol. After a period of exposure (four weeks, for example), the blanket is removed and all components and alcohol interior to the blanket are exposed to acidified ethanol and magnesium reactant mixture. In this mixture, the PCBs are degraded.
Sediments were tested in the lab using a waste destruction method that is composed of magnesium, acidifying agents, and environmentally green solvents capable of proton donation (e.g., alcohols, ethanol, and/or other long-chain alcohols). Various amphiphilic (hydrophobic/hydrophilic ends) bio degradable polymers and co-polymers such as polylactic acid (PLA) and polyethylenimine (PEI) were tested for their affinity and ability to transport PCBs across their matrix and into the alcohol center. The general concept is a two-phased approach that attracts PCBs to the polymer surface, transports them across the polymer thickness, and concentrates the PCBs in an ethanol or other alcohol interior. The polymer blanket system is then removed from the sediments and exposed to the PCB degrading reactants (magnesium in an acidified ethanol solution) ex situ to the sediments.
The PCB-treating polymer blanket system for application to PCB-contaminated sediments offers a unique product that combines a two-step approach for PCB degradation. The steps include: (1) disassociation of PCBs from a sediment particle, adsorption onto a polymer (e.g., polyethylene), transport across the polymer thickness, and concentration in an ethanol interior; and (2) treatment of the captured PCBs ex situ to the sediments using acidified ethanol and magnesium reactants in a system washing bath.
This technology has global commercial potential. PCB contamination in sediments exists at every major harbor and in every major river/waterway in the United States, and every industrialized country has similar issues.
This work was done by Jacqueline Quinn of Kennedy Space Center; Robert DeVor and James Captain of ASRC Aerospace; and Cherie Geiger and Christian Clausen of Scientific Specialists. For more information, contact the Kennedy Space Center Technology Transfer Office at 321-867-5033. KSC-13579