Scrubbing Bubbles
A new technology uses ozone gas to treat polluted sediments in situ.

Challenge
Sediment pollution from toxic organic chemicals such as polychlorinated biphenyls (PCBs) is a widespread problem, impacting hundreds of estuaries and coastal harbors around the United States. The traditional approach to remediation involves dredging—a costly process that can disperse pollutants into the water column and creates the challenge of how to move and where to place the polluted sediment. In many cases, treating the problem in situ may be a better alternative, but few viable technologies are available to sediment and water quality managers.

Response
With a grant from CICEET, researchers from the University of Utah are developing an in situ ozonator, a system that combines ozone gas with the metabolic appetite of microbes to treat sediments contaminated by toxic chemicals. Early bench-scale tests involving samples from around the country have shown promise in treating sediment polluted by PCBs, as well as other organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) and insecticides like DDT.

The researchers are currently designing a prototype system to take this process from the lab bench to the field. In this system, a floating vessel will provide the power to move the ozonator over the sediment substrate. As it moves, the instrument will take in batches of contaminated sediment and infuse them with ozone gas. The ozone acts like a chemical sledgehammer, breaking the pollutants down into by-products that bacteria can access. Depending on the type of pollutant, the system will then add amendments such as carbon or oxygen to encourage the growth of native bacteria that can consume these by-products as food. Once the batch has been processed and any excess ozone removed, the treated sediment is released, the toxic chemicals no longer a threat to bottom-dwelling animals.

Impact
Though the process is currently in the research and development phase, the researchers envision a flexible system that sediment and water quality managers could adapt to fit the profile of the polluted sediment they want to treat. In areas of heavy contamination, the instrument would move more slowly and use more ozone, achieving higher rates of degradation. In less polluted areas, it could move more quickly, saving time and money. If successful, the technology has potential to support sediment remediation throughout the coastal U.S.

Learn More
Researchers are seeking sediment samples with exceptionally high levels of toxic organic pollutants on which to test this process. If you are interested in participating in this project, please contact:

Dr. Andrew Hong
University of Utah
T: 801.581.7232
E: hong@civil.utah.edu

Dr. Donald Hayes
University of Utah
T: 801.581.7110
E: hayes@civil.utah.edu

Related Projects
In Situ Treatment of PCB-Contaminated Sediments Using Zero-Valent Iron [Bulletin]

Reusing Contaminated Dredged Sediments to Manufacture Cement [Bulletin]

Renourishing Marshes with Dredge Spoil [Bulletin]

Patented Technology for Stabilizing Metals in Dredged Sediment [Bulletin]

Development and Demonstration of Low Pressure Control Zone Contaminated Sediment Dredging Technology [Final Report]

Hydrogen-enhanced Remediation of Capped and Natural Sediments [Progress Report]

Enclosed Excavator for Contaminated Sediment Removal from Coastal Aquatic Environments [Progress Report]

Polychlorinated Biphenyl Remediation in Sediments: Pilot Scale Demonstration [Progress Report]

In Situ Remediation of PAH Contaminated Sediment [Progress Report]