Arsenic poisons thousands of people around the world each year when it leaks into drinking water supplies, but Australian scientists and an abandoned mining town in Montana may have the answer.
ANSTO scientists working with the Cooperative Research Centre (CRC) for waste management and pollution control announced that they have successfully demonstrated their arsenic immobilisation process at a demonstration plant in Montana, in the United States.
Trialled in the heart of cowboy country, the invention uses two of Nature's most freely available products, sunlight and air. The CRC Project Leader from ANSTO Dr Ging Khoe, said the work showed that the best things in life are still free.
"We use sunlight (or ultraviolet light) to increase the rate of natural change from the highly poisonous version of arsenic known as arsenic(III) into the less harmful arsenic(V) by 10,000 times. The insoluble arsenic(V) can then be safely removed and stored in cement or landfill sites," he said.
"The common method of removing arsenic from water uses chlorine or ozone. The waste products from it are harmful to people."
Arsenic poisoning of groundwater occurs naturally or as a result of mining.
"More than 200,000 people in India are chronically poisoned each year by naturally occurring arsenic in ground water. In addition, acid mine water containing arsenic is considered a major environmental hazard in the western United States," Dr Khoe said.
Concern about cancer risks has led the World Health Organisation to revise the recommended safe limits for arsenic in drinking water from 50 to 10 parts per billion.
The project to demonstrate the Australian invention is being funded by the United States Environmental Protection Agency's Office of Research and Development in Cincinnati, Ohio, through the US Department of Energy.
The project is being implemented in the US by MSE Technology Applications Inc. MSE Project Manager, Mr Jay McCoskey, said US mining companies and environmental regulators are very interested in the invention.
"This new process could help solve some of our water quality problems in the US," he said. "A large part of our drinking water comes from groundwater, and reliable low cost treatment processes are needed to treat contaminants."
Arsenic is an unwanted by-product of the mining and extraction of metals such as copper, lead, nickeland uranium. Flue dust from the roasting and smelting of these ores contains arsenic and is often kept in temporary storage where it may contaminate nearby groundwater.
The Montana demonstration plant was successful in treating acid mine water and flue dust with the new process in specially made solar troughs and using a commercially available ultraviolet lamp reactor.
An iron compound is used to immobilise the oxidised arsenic for safe disposal in landfill sites. Leaching tests, being carried out at ANSTO, will be completed in January. Dr Khoe said that mining companies, engineering consultants and manufacturers of water treatment systems had expressed interest in the new invention.
"The Montana demonstration is an example of this widespread interest," he said.
"We are confident that the invention will be used world-wide to treat contaminated groundwater used domestically and in agriculture. It will also be used by the mining and metal-producing industries to treat arsenic wastes.
"This new invention could mean millions of export dollars for Australia."
Published: 16/09/1997