Tiny Bubbles Used to Clean Oil-Contaminated Water and Soil
Even small amounts of oil leave a fluorescent sheen on polluted water. This oil sheen is difficult to remove—until now. According to a recently published article in the journal Chemosphere, an inexpensive new method has been developed to remove oil sheen by repeatedly pressurizing and depressurizing ozone gas, creating microscopic bubbles that attack the oil so it can be removed by sand filters.
"We are not trying to treat the entire hydrocarbon content in the water -- to turn it into carbon dioxide and water -- but we are converting it into a form that can be retained by sand filtration, which is a conventional and economical process," says lead author Andy Hong, University of Utah professor of civil and environmental engineering.
Hong says the technology -- for which patents are pending -- could be used to clean a variety of pollutants in water and soil, including:
- Oil-contaminated wastewater discharged into coastal waters
- So-called "produced water" from oil and gas drilling sites on land. "If we have technology to clean it, it could be put into beneficial uses, such as irrigation, especially in arid regions where oil and gas tend to be produced," says Hong.
- Water from mining of tar sands and oil shale
- Refinery wastewater and oil spills at refineries or on waterways
- Groundwater contaminated by MTBE, a gasoline additive that pollutes water due to leaking underground gasoline storage tanks
- Wastewater polluted with medications and personal care products
- Soil contaminated with polychlorinated biphenyls (PCBs, from electrical transformers) or polycyclic aromatic hydrocarbons (PAHs, from fuel)
The study showed that the new method not only removes oil sheen, but also leaves the treated water so that any remaining acids, aldehydes and ketones are more vulnerable to being biodegraded by pollution-eating microbes.
For more information, visit the University of Utah's website: http://www.utah.edu/portal/site/uuhome/