Microbe spots arsenic contamination

Scientists have found a microbe living in the extreme conditions of  a sub-arctic mine capable of neutralizing highly toxic arsenic.

The researchers from University College London in the United Kingdom said the team had found these hearty extremophiles living on the walls of Giant Mine in northwestern Canada. The bacteria are able to consume arsenic compounds contained in polluted water seeping into the mine.

The scientists were optimistic about the potential to isolate the enzyme from these strains of bacteria and thus create an arsenic biosensor for use in cold climates. The biosensor could warn officials of arsenic traces in the water from mines, labs or industrial chemical facilities.

The researchers think these arsenic biosensors could also be used to help test newly drilled wells in countries such as Bangladesh with known arsenic contamination.

"Microbes have been used to remove nitrates from water in the past," Tom Lorg, research engineer at the Environmental Protection Agency (EPA) told the Cleantech Group. "The idea of using microbes to remove arsenic is certainly feasible."

The University College scientists say until now there’s been no isolated bacteria that can thrive in cold temperatures and deal with arsenic decontamination. The microbes can function at temperatures from 20 degrees Celsius to 4 degrees Celsius.

Arsenic enters drinking water supplies from natural deposits in the earth or from industrial and agricultural pollution, according to the National Resources Defense Council (NRDC).

Long term exposure to arsenic in drinking water is known to cause bladder, lung and skin cancer, and may cause kidney and liver cancer, according to the National Academy of Sciences. It may cause birth defects and reproductive problems (see New all-in-one disaster relief system).

Arsenic contamination is a byproduct of copper smelting, mining and coal burning. Each year, U.S. industries release thousands of pounds of arsenic into the environment. 

The Giant Mine, known for its large gold reserves, is one of the most polluted places on Earth, according to researchers, who released their findings at the Society for General Microbiology's meeting at Trinity College, Dublin. The mine contains over 237,000 tonnes (U.K.) of arsenic-containing dust produced during the gold-roasting process. The dust is water-soluble and contains 60 percent arsenic.

Lorg said there are about 4,000 utilities in the western U.S. using natural well water where there’s arsenic contamination that needs to be removed. Some of these large well-water systems are in El Paso, Texas; Albuquerque, N.M.; and Scottsdale and Phoenix, Ariz.

Most of the technology developed for arsenic removal comes from Germany and the U.K., Lorg said. The systems typically utilize an absorptive, granular material in a tank through which contaminated water passes (see EnviroMetal licenses water remediation technology).

There are several challenges in getting a microbe treatment technology readied for commercial use, he added. First, the water would probably have to be filtered before treatment with the microbe.  One would also have to know how long the microbe took to remove the arsenic from the water. That’s because water flows into and out of systems relatively quickly.

The NRDC analyzed data collected by the U.S. EPA on arsenic contamination in the drinking water from 25 states. The organization said it is likely that as many as 56 million people in those 25 states have been drinking water with arsenic at unsafe levels.

The World Health Organization says reliable data on arsenic exposure and health effects is not available. Many countries in the world, however, have problems with arsenic in drinking water, exceeding the safe concentration level of 0.01 miligrams per liter. Those countries include Argentina, Australia, Bangladesh, Chile, China, Hungary, India, Mexico, Peru, Thailand, and the United States, said the WHO.

According to the National Academy of Sciences, one out of 100 people who drink water containing 50 parts-per-billion of arsenic will get cancer (based on drinking two liters of water per day over the course of a lifetime).