Activated Carbon (AC) has been used to remediate hydrophobic organic contaminants (HOCs) in sediment by reducing their bioavailability as an alternative to traditional methods such as dredging. While numerous work has confirmed the proof-of-concept and the in-situ field application of AC to reduce bioavailability of HOCs, AC has not yet been used to treat high concentrations of HOCs with high loading rates of HOCs on AC. The loading capacity of HOCs on AC is of interest because it can inform the ability of in-situ AC to provide long-term treatment effectiveness as well as assimilation capacity against site recontamination. This study shows that AC may be effectively used to treat sediment contaminated with dichlorodiphenyltrichloroethane (DDT) and other HOCs concentrated 10-100x more than previously tested with similar effectiveness. Sediment used in this study was retrieved from the United Heckathorn Superfund Site at Lauritzen Channel, CA and contained high concentrations of DDT (~2,000 ppm ΣDDT), dieldrin, chlordane, PAHs, and PCBs. AC was added to sediment in 2%, 4%, and 8% by weight doses and pore water concentrations of DDT were monitored using passive sampling of polyethylene (PE). Even a low dose scenario (2% AC, 75-300 um grain size) reduced the ΣDDT contaminant availability more than 80% from sediment with extremely high DDT contamination after 7 months of AC-sediment contact while a high dose scenario (8% AC) reduced ΣDDT contaminant availability more than 98% after 7 months of contact time. Benefits of the AC amendment toward concurrent contaminants dieldrin, chlordane, PCBs, and PAHs were similarly strong, showing 82-99 % reductions within 6 months of contact.

Activated carbon amendment for treatment of sediment contaminated with DDT and other hydrophobic organic pollutants concentrated 10-100x more than prior studies

256th National Meeting (2018)

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