Superfund Research Program
Development of an Innovative Approach for In Situ Treatment of PCB Impacted Sediments by Microbial Bioremediation
Project Leader: Craig Bennett Amos
Grant Number: R43ES032365
Funding Period: Phase I: July 2020 - June 2021
Polychlorinated biphenyls (PCBs) are one of the most problematic of legacy contaminants. Persistent and mobile in the environment, PCBs are largely ubiquitous in depositional sediments of aquatic systems in industrial regions of the United States. Their relatively high toxicity and bioaccumulation potential cause elevated risk to both human and ecological receptors. As such, PCBs are often the primary risk driver at impacted sediment sites. Common practices for remediating PCB-impacted sediments are costly, often involving the physical removal of surficial sediments, capping the sediments or dredge depression with a multi-layered engineered cap, and disposal of the contaminated sediments in a confined landfill. An emerging strategy for effectively removing PCBs from sediments in-situ is the use of bioamended activated carbon (AC), which inoculates AC pellets with enriched cultures of PCB-degrading microbes.
Members of this research team have performed the fundamental research behind the use of bioamended AC for remediation of PCBs from sediment and have developed and patented commercially-viable methods for growing, inoculating, and delivering the inoculated AC pellets to sediments. However, during the performance of pilot-scale studies using the bioamended AC, two factors that would limit the ready use of this technology for large, multi-acre sites were identified: 1) the large-scale growth, storage, and transport of anaerobic PCB degrading bacteria, and; 2) large-scale methods for inoculating AC pellets during application. This research is addressing these limitations.
The researchers are testing methods of culturing these organisms using time-release growth media and developing and testing storage vessels that maintain optimal environmental conditions for the long-term viability of the anaerobic organisms. These advances will ultimately allow for the delivery of large volumes of PCB degrading microorganisms for large-scale projects. The researchers are also developing and testing methods for the continuous, uniform inoculation of high volumes of AC pellets with the PCB-degrading microorganisms, which allows for cost-effective application at multi-acre PCB-impacted sites. Coupled together, the research is anticipated to result in a direct transfer of this technology from pilot-scale to full commercial viability.