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Thursday, March 31, 2011

Removing arsenic from drinking water

A team of scientists led by Bhaskar Sen Gupta from Queen’s University Belfast has devised a system to remove arsenic from groundwater. The technology, called Subterranean Arsenic Removal (SAR), has been successfully tested both in West Bengal, India and in the United States.

Effect of Arsenic Poisoning

Arsenic is found naturally in the Earth’s crust. Changes in agricultural processes in rural areas (increased fertilization) causes bacteria to release arsenic from the soil into the groundwater, from whence it finds its way into the drinking water of an estimated 137 million people in 70 countries. At levels as low as 10 ppb (that’s ten parts arsenic per billion parts water), people begin to suffer from a myriad of severe illnesses and may even die. There are ways to remove arsenic, but they tend to be expensive and to produce toxic sludge that must then be dealt with.

Enter SAR, which relies on oxidation and filtration, uses no chemicals and produces no sludge. Simply by aerating the groundwater in an SAR plant, arsenic, iron and manganese are precipitated back into the soil deep underground. The cost of a single plant capable of cleaning 6000 liters of water per day is only about $4000.

After using SAR in rural Bellingham, Northwest Washington State, arsenic levels fell to below the safe limit set by the US Environmental Protection Agency. There are plans to set up new SAR plants in Cambodia, Vietnam and Mexico.