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Microbe munchers take bite out of nitrate

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May 10, 1995 Share This!

RICHLAND, Wash. — Vegetable oil is great for cooking french fries. But it is even better for energizing microbes. Scientists at the Department of Energy's Pacific Northwest Laboratory believe vegetable oil may provide an inexpensive and effective way of stimulating microbes to eat toxic contaminants in water.

PNL, in conjunction with the U.S. Department of Agriculture, successfully demonstrated in the laboratory that microbes energized by vegetable oil can filter nitrate from simulated underground aquifers. Nitrate is considered one of the most pervasive groundwater contaminants in the United States.

PNL's patented process works by injecting vegetable oil into the earth around the base of a well. As it enters the earth's subsurface, the oil becomes trapped in pockets between the various layers of sediment. The nitrate filtration takes place as the contaminated water flows past a zone of naturally occurring microbes that use the carbon in the oil as an energy source. The microbes metabolize the nitrate and transform it into nitrogen gas, which is absorbed into the water. The water then can be pumped from the earth free of the nitrate. The microbes remain underground until they die.

Nitrate in groundwater often is associated with agricultural practices such as the leaching of excess fertilizer, animal manure, etc. It also is found in urban waterways by way of septic systems and secondary water treatment systems. Although generally not considered a major health threat, high levels of nitrate in children can result in a blood condition where the oxygen level is lowered to possible life-threatening levels.

Many underground wells contain nitrate levels that greatly exceed the U.S. standard for drinking water. Until all nitrate sources are identified and reduced, water will need to be treated to reduce nitrate to levels that are safe for human consumption. PNL's process has reduced nitrate levels as high as 180 parts per million to a level well below the drinking water standard of 10 parts per million. PNL's technology can be an attractive alternative to current filtering methods, such as reverse osmosis, because vegetable oil is nontoxic, biodegradable, available in abundant supply and inexpensive. In addition to nitrate, PNL's technology also may remove toxic organic solutions such as gasoline and solvents.

PNL is looking for a commercial partner to perform a large-scale field test. For more information on commercial partnerships with PNL, contact Glendon Gee at (509) 372-6096 or Jim Fredrickson at (509) 375-3908.

Tags: Energy, Technology Transfer and Commercialization

PNNL LogoInterdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,400 staff and has an annual budget of nearly $1 billion. It is managed and operated by Battelle for the U.S. Department of Energy's Office of Science. As the single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information on PNNL, visit the PNNL News Center, or follow PNNL on Facebook, Google+, Instagram, LinkedIn and Twitter.

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