Harnessing Bacteria to Battle Pollution

A new NRC technology is set to help clean-up decades of environmental contamination.

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Since the 1940s, millions of tons of cancer-causing chlorinated solvents have been dumped, poured, buried or leaked into soil and water in North America. Every year, thousands of tons still follow this route, eventually making their way into groundwater. The question is what to do with this toxic contamination? Researchers at the NRC Biotechnology Research Institute (NRC-BRI) have a solution: turn it into harmless carbon dioxide and water.

Their unique technology for the bioremediation of groundwater contaminated with chlorinated solvents recently received two-thumbs up from a distinguished panel of business and scientific leaders. The judges awarded their technology, eMaMoc, first prize in the new technologies available for licensing category of the NRC Business Case Challenge 2006.

Bioremediation is a technique that stimulates Mother Nature to clean-up our mess. The process relies on the fact that among the world's amazingly diverse range of bacteria, there's almost certain to be one or more that will eat, and thus safely transform, any pollutant in question, including chlorinated solvents. The market for bioremediation services in the U.S. alone is estimated to hit $1 billion by 2010.

Chlorinated solvents are a broad group of chlorine-based chemicals that are used as a degreasing agent, primarily for machinery. They're widely used in industries from the automotive to the semiconductor sector, and also in dry cleaning.

The problem is they're toxic. And for the past 60 years they've been disposed of in ways, including buried in barrels that rust and leak, that have contaminated soil and groundwater. There are at least 150,000 such contaminated sites in the United States, and thousands more in Canada.

The NRC-BRI technology uses a patented two-in-one bioremediation technique that almost completely removes chlorinated solvents from the treated water. Presently, bioremediation techniques on the market use either aerobic (oxygen using) or anaerobic (without oxygen) bacteria, alone, or consecutively. The technology capitalises on the insight that under just the right conditions, these bacteria can work together synergistically.

Graphical representation of the bioremediation method of wastewater by utilizing coupled anaerobic and aerobic biological treatment, more specifically, methanogenic (strictly anaerobic) and methanotrophic (strictly aerobic) microbial populations, in combination with a supply of in-situ generated water-dissolved oxygen and hydrogen.

"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, such as biogranules," says Dr. Serge Guiot, Head of the NRC-BRI Environmental Bioengineering Group.

Biogranules are naturally occurring microscopic aggregations of bacteria. 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-less 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 only by-products of this tag-team digestion are carbon dioxide, water, and harmless chloride salts.

The patented NRC technology stimulates and accelerates this natural biodegradation by using electrolysis of water (or 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 digestion of the end-products of the anaerobic breakdown.

EMaMoc Prototype, NRC's tool for the bioremediation of chlorinated organic chemicals.

In pilot-scale tests, the technology has demonstrated that the technique reduces 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."

The NRC team is currently negotiating partially-exclusive licensing arrangements with two Canadian environmental clean-up companies. Both licenses would involve initial large-scale field installations of the chlorinated solvent technology at well-known contaminated sites in Quebec.

The technology, more than five years in development, benefits from a diverse and experienced NRC team. This includes researcher Dr. Boris Tartakovsky, and technical officers Ruxandra Cimpoia, Michelle-France Manuel, Marie-Josée Lévesque and Jérôme Breton.

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

Once on the market, Dr. Guiot believes their technology will quickly find a rapidly growing niche of its own.

"The NRC-BRI bioremediation technology will have a competitive edge over other bioremediation technologies. It will be less expensive and yet effective on a wider range of chemicals than other technologies," he says.

The NRC technology can also be used with almost all existing bioremediation techniques including bioreactive deep wells and subsurface permeable biological barriers.

Recommended Links :

• Doing Business with NRC
• NRC's Areas of Research: Biotechnology
• NRC Biotechnology Research Institute
  

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