Microscopic Ozone Bubbles Attack Oil Sheen Pollution


Image credit: timparkinson/Flickr
Oil sheen, the scummy film that forms on the top of polluted bodies of water, is incredibly difficult to remove. Even common filtering practices, like aeration and sand filters, have trouble removing the small amount of oil that leaves neon swirls on the water's surface. Now, a scientist at the University of Utah has developed a new technology, combining and adapting some existing methods, to address oil sheen pollution.

Using an inexpensive pump to repeatedly pressurize and depressurize ozone gas, the system creates microscopic bubbles that attack oil sheen and allow it to be captured by a conventional sand filter.Rather than trying to completely breakdown the hydrocarbon, or oil, molecules in the water, the new process simply converts them to a form that is easier to capture. Through lab experiments Professor Andy Hong demonstrated that his method could effectively remove oil sheen from wastewater before it's released into coastal systems.

Microbubbles Make a Difference

Image credit: David Purser/Flickr

Ozone aeration is not a new idea; in fact, it is already a common part of many filter systems. Typically, ozone is pumped into polluted water but the comparatively large bubbles are not very reactive.

In Professor Hong's system, the polluted water is repeatedly pressurized with ozone, and then depressurized. The water becomes saturated with ozone during the pressurization phase, and the gas expends to form microbubbles when depressurized. The result is a foamy mess similar to an overactive carbonated beverage.

Having many small bubbles increases the surface area available for ozone to react with the oil. What oil doesn't react tends to clump together, making it easy to capture in a sand filter.

Taking it to the Real World

Image credit: Diego Cupolo/Flickr

Having demonstrated success in the lab, Professor Hong now plans to test his process in the real world. Larger-scale tests will be conducted at a facility in China, where a desktop-sized device will be built to treat an estimated 52 gallons of wastewater at once.

If the process scales up, Hong believes it can be used to clean a variety of contaminants including MTBE, prescription medications, and even heavy metals and PCBs from soil.

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Tags: Pollution | Water Conservation

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