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New water treatment technology holds many possibilities
A new water treatment technology has applications ranging from purification in African and Indian coastal slums, to decontamination of water produced in gas and oil wells.
Gradiant, a company born at MIT, is now courting some of the giants in the U.S. gas and oil markets with one promise: they can purify contaminated water for less than it costs to dispose of it.
“We use very simple materials and construction to make the devices, the energy consumption is much lower than other thermal techniques,” says Anurag Bajpayee, a Gradiant co-founder. “The treatment here is indeed cheaper. We’re very confident that we can come in under the price point of disposal.”
Bajpayee says their technology has been tested with water from the field and it’s able to purify up to 90 percent of the water volume to drinking quality.
The other ten percent, he says, still has to be disposed of but at far less economic and environmental costs.
“In the case of sea-water desalinization, the typical recovery ratios are 40-50 percent," Bajpayee explains.
"Anything you don’t recover forms a brine which just gets tossed back to the ocean," he continues. "Here, anything you don’t recover still has to be trucked away at a very high price point. So there is a premium on both an environmental and economic reason to further treat the water and get more and more fresh water. We can get very high recoveries on that," he said.
“The water we actually get out is very, very high quality water," he adds. "So, in fact in our water, it’s better than Boston’s water supply.”
Bajpayee says the company is in talks with several partners in the gas and oil industry and they hope to have a field pilot of the system up and running in the near future. But that’s not all Gradiant is about, he says.
“To be honest with you, we’re very much a water treatment and environmental company, but we’re only going to make this work if we’re economical," Bajpayee explained.
“We are focusing on the oil and gas market because there is sort of a desperate need over there, it is a large economic proposition. But, sort of the Holy Grail is to do small scale distributed sea water desalination and municipal water treatment so we can get this clean water to people who don’t have it or who are paying very high prices for it.”
Bajpayee says some of the poorest slums in India and Africa just don’t have the infrastructure to get clean water, but they are often located close to the coast. He says he would love to see the company addressing those problems, but Gradiant needs to make the system more economical before they can begin to work with communities like that.
The technology is based on a low energy, carrier gas extraction system.
“We have a gas stream that’s in a closed loop and that’s going around, picking up the water at one end in a humidifier and then condensing the water out at the other end in a de-humidifier, and we do it at a fairly low temperature so we don’t have to take the water to boiling point.”
Bajpayee says their system could be suitable for deployment in small communities in developing countries or in larger industrial applications because it can operate efficiently over many different scales.