Groundwater Remediation with Vitamin B₁₂

Canadians are concerned about the quality of their water, and many depend on a clean supply of groundwater as their only source. Unfortunately, wells and aquifers can be easily contaminated by common groundwater pollutants such as chlorinated solvents—used in dry cleaning, degreasing, chemical processing, and paint stripping. Scientists at Environment Canada's National Water Research Institute (NWRI) have developed a method to decontaminate polluted groundwater while it is still underground using a mixture of non-toxic components.

Research at NWRI showed that a solution of vitamin B₁₂ and titanium citrate injected into a laboratory model of an aquifer and well system effectively dechlorinated contaminants. Environment Canada patented this process and now the United States Army has commissioned a field demonstration at the Aberdeen Proving Grounds in Maryland, where groundwater was contaminated 40 years ago with a complex mixture of chlorinated methanes, ethanes, and ethenes that has not degraded over the years.

The B₁₂ solution is mixed on site and pumped into the contaminated groundwater by means of a recirculation well designed specifically for the site's hydrogeology and installed in the most contaminated area. Several multi-level monitoring wells, situated radially around the recirculation well, are sampled regularly to determine the effect of the treatment in the aquifer.

Results show that chlorinated methanes are degraded in minutes, and that chlorinated ethanes degrade more slowly, followed by biological degradation of second-generation products. Research is ongoing, but early results are encouraging. So far, researchers have found no accumulation of vinyl chloride, a carcinogenic chemical that may be produced when degradation occurs, and they have observed a prolific growth of bacteria in an area where nothing would grow before.

The field demonstration will continue until September, after which the U.S. Army will select the most effective remediation technology tested to treat the entire site. Meanwhile, NWRI researchers are continuing laboratory work to refine the process and solve any problems detected in the field. If all goes well, the new technology could help clean up numerous sites in Canada and abroad—particularly those contaminated with chlorinated solvents in concentrations high enough to be toxic to bacteria, and those needing rapid remediation.

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