New Mexico Governor Bill Richardson (left),announcing the grant award and Dr. Gregory Miller, VP R&D Subsurface Technologies Inc. (right) developer of the STAR arsenic removal technology being interviewed at the press conference.

Wednesday, October 19, 2005

Technology uses rust to remove arsenic in water
Town will receive control of system in 2007

Argen Duncan El Defensor Chieftain reporter

A recent state grant to a private company has put San Antonio on a track to have a cost-efficient removal of arsenic from drinking water by May 2006.
Subsurface Technologies Inc. received a grant of $860,000 in September from the New Mexico Gov. Richardson's Water Innovation II Grant Initiative to continue to develop and implement belowground technology that uses rust to remove arsenic from water without creating waste.
"I really hope that this technology will reduce the cost and make it easier for the small communities in New Mexico to deal with the new arsenic regulations," said Subsurface Technologies scientist Gregory Miller. "And I thank all the groups that have funded this project in the past and present."
He also said the development would not have come as far without cooperation from the San Antonio Mutual Domestic Water Users Association.
Miller said half the grant is to be used for building the system, called Subsurface Treatment for Arsenic Removal, and the other half for monitoring its performance and operating it for a year. He said the technology will operate on a newly drilled well.
Miller said he hopes to start design and construction in November and finish in April 2006, with the technology operational by the next month. San Antonio is to receive control of the system in early 2007.
Water Users Association Operations Manager Fred Hollis said San Antonio is now using a well that provides enough water for winter needs but not for summer.
The technology's cost will depend on the amount of arsenic but will probably be $500,000 to $750,000, he said.
Although Miller hasn't yet tested the well, he said that area of the aquifer has 17 parts per billion of arsenic, as opposed to the maximum of 10 parts per billion that regulations mandate.
Hollis said STAR looks like a good technology. With aboveground systems, operators must dispose of filter material.
"But by using this underground technology, you don't have any filter media to get rid of," Hollis said.
Miller said he thinks the system will become widespread.
"It won't work everywhere, but we believe it to be very competitive where it will work," he said, adding that places around the nation and world have the right conditions.
The system requires more knowledge of the aquifer but has the same capital costs as other technologies on wells of similar sizes, Miller said. It has no expense for waste management and doesn't waste water. He also believes the cost of operation is less.
"The biggest cost of the technology is drilling wells around the well that's producing water," he said, adding that his system is not cost-efficient if wells must be very deep.
The technology uses a ring of wells around the water-providing well to introduce oxygen, and iron if necessary, into the aquifer to form rust to create a subsurface renewable filter.
"We know that arsenic likes to stick to iron oxides, various kinds of rust," Miller said.
With the technology, arsenic bonds to the rust, and the attached chemicals coat grains of soil and gravel in the aquifer. This removes iron, a water-quality problem itself, and arsenic from the water.
Miller said the system also removes undesirable manganese from the water.
Some well water already has enough iron to treat the arsenic, he said. In these cases, operators would add oxygen to form rust.
If the soil did not contain enough iron, they would add it in pulses before introducing oxygen, he said.
The chemicals going into soil will not cause problems, he said.
"We know that these iron-oxides, once formed, are stable for long periods of time," Miller said. "It would take really dramatic changes in the aquifer conditions to cause them to re-dissolve."
Every time operators add more iron, he said, a new layer of rust bonded with arsenic coats the particles in the aquifer, so the substances encapsulate themselves, which keeps them from posing a threat.
Miller also said the concentration of arsenic in the filter material isn't significantly different from what naturally occurs in New Mexico soils.