ARCHIVED - Unique Bacterial Tag Team Fights Chlorinated Solvent Pollution

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April 07, 2007— Ottawa, Ontario

Scientists have long understood that microorganisms – naturally occurring bacteria – can be used in a process called environmental bioremediation to clean up contaminated sites, particularly those poisoned by chlorinated solvents. But until recently, most bioremediation processes have been either too costly, not entirely effective, or both.

Now, NRC has engineered an innovative approach to employing pollution-hungry bacteria that overcomes both the cost and efficacy shortcomings of traditional techniques, giving Canada a decided advantage in the burgeoning field of bioremediation.

A portable unit for on-site treating of a contaminated site by biostimulation
A portable unit for on-site treating of a contaminated site by biostimulation

Developed by environmental bio-engineers at the NRC Biotechnology Research Institute (NRC-BRI), this unique technology permits a greener approach to cleansing groundwater contaminated with chlorinated solvents because the by-products ― carbon dioxide, water and chloride salts ― are relatively benign compared to those generated by traditional methods.

For their efforts, the NRC team earned top honours in the new technologies available for licensing category of the NRC Business Case Challenge 2006.

Since then, NRC has licensed the technology, under a partially exclusive arrangement, to Sanexen Environmental Services, a specialist in PCB management and contaminated site characterization and remediation. The Quebec-based company will demonstrate the technology at a well-known, contaminated site in the province.

As NRC's solution moves into full-scale commercialization, the market is ripe. In the United States alone, the bioremediation segment of the overall soil and groundwater remediation business is set to double to over US$1.3 billion by 2010. And in Canada, the federal government has committed $3.5 billion over 10 years to clean up contaminated sites.

The NRC technology uses a two-in-one bioremediation technique that almost completely removes chlorinated solvents from the treated water. Presently, bioremediation techniques on the market use either aerobic or anaerobic bacteria — alone, or consecutively. Normally, these bacteria can't co-exist because one requires oxygen while the other requires an oxygen-free environment.

The NRC technology capitalizes on the insight that under just the right conditions, these bacteria can work together synergistically, as opposed to sequentially.

"Although at first glance it's counter-intuitive, our technology is based on the fact that aerobic and strict anaerobic microorganisms can grow together in a single natural habitat," says Dr. Serge Guiot, Head of the NRC-BRI Environmental Bioengineering Group.

"Biogranules" are naturally occurring microscopic aggregations of bacteria that form a biofilm. What Dr. Guiot's team discovered is that these granules provide a natural tag-team environment for aerobic and anaerobic bacteria. The aerobic bacteria live on the oxygen-rich surface of the granule, while anaerobic ones live in the oxygen-free core.

This means that for bioremediation, the biogranules deliver a one-two punch that's the basis of the technology, notes Dr. Guiot. The anaerobic bacteria begin the break down of the chlorinated solvents and the aerobic bacteria finish the job, digesting the by-products of their cousins' work.

The patented NRC technology stimulates and accelerates this natural biodegradation by using electrolysis of water (electrically splitting H2O) to fuel the various bacteria with oxygen and hydrogen. The hydrogen is used by anaerobic methanogenic bacteria to dechlorinate the solvents and to produce methane. In turn, the methane and oxygen energize the aerobic decomposition of the end-products of the anaerobic breakdown.

In pilot tests, this technology reduced chlorinated-solvent contamination in moderately and highly contaminated water to levels below regulatory guidelines.

"We're excited about the effectiveness of the technology we've shown in the lab," says Dr. Guiot. "We've demonstrated proof-of-concept and the technology is now ready for full-scale field trials."

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