With Arizona in drought and cuts likely coming to the state’s allocation of Colorado River water, lots of people are looking for ways to conserve the water we do have.
And that means folks are trying to get creative. Two Arizona State University professors think they’ve figured out a piece of this puzzle.
Behind the university’s MacroTechnology Works building in Tempe in what looks like a very large carport, is a series of pipes, knobs, measurement tools, basins — and water.
The plan at this test facility is to work out how to treat briny water that comes as a result of industrial and manufacturing processes. Basically, how to take the salt out, which leaves water that’s usable for something else — although likely not drinking.
Salt management is critical
"Our goal is to treat wastewater and at the same time producing more fresh water from different industrial wastewater," said Tiezheng Tong, an associate professor of Environmental Engineering at ASU.
He and colleague Shahnawaz Sinha, an associate research professor in Civil and Environmental Engineering at ASU, told The Show more about their work.
Sinha says part of the problem their research is trying to solve is one of geography.
"The water that we usually get is already a little bit salty, like what's coming in from the Colorado River water or from the reservoir. It's a hot, arid region, and when the industries are using municipal tap water," Sinha said.
"But there's many industries who wants to treat this water even more so they can get more purer and more ultra-pure water. But in the process, they're also getting a lot of salt left behind."
Sinha says salt management is one of the most critical issues they’re working on.
Certain industries — think semiconductors or food and beverage — need water for their manufacturing processes. They don’t want to have to keep using new water, but what’s left when they’re done isn’t re-usable as is.
Sinha says that’s where this work comes in.
"We're going to convert this fab wastewater to tap water, that is the feed water for them. And we'll convert the tap water to the ultra-high purity water, and they could use it for chip manufacturing," Sinha said.
"So, we're totally closing the loop. We’re taking the wastewater and we're creating ultra-high purity water. And that could be utilized for chip manufacturing, this is our idea."
Through the filtration and treatment process, Sinha and Tong believe they’ve figured out how to turn that briny water into industry-usable water.
So that solves one problem. But in a sense, it creates another: what to do with all that salt they’ve taken out of the water?
Financial cost of salty water
"If you are in the coastal region, you know, like in Florida or California, you are you're creating a brine and you could easily discharge it to the sea, with some type of safety stuff," Sinha said.
"But people who are in the inland, like places like Arizona, Colorado, and some places they do allow deep well injection, but some places they don't. So, you are left with this briny wastewater and you have to come up with an innovative way of tackling this wastewater."
Sinha acknowledges that’s a concern; a 2006 study from the Bureau of Reclamation found at that time the Colorado, Salt and Verde rivers imported nearly 2 million tons of dissolved salts each year into Maricopa, Pinal and Pima counties. And that salt comes with a financial cost, too: around $30 million each year.
So, while it’s great to remove that salt from the water, Sinha says what happens next is also important. He says, though, there are uses for that salt.
Uses for wastewater salts
"When we were working with the food and beverage industry, the same question they asked, what are you going to do? I think we have to think about in a creative way how to deal with it," Sinha said. "I mean, if you are in the northeast region and other places, you know, you could use this salt for deicing. I just looked at some people were mentioning they also need a briny stuff to for soap manufacturing, so that could be another place, sometime, places like where they could use a briny water for other type of application, say for a cooling tower or other places, they could also have this type of water available."
And Tong says while they’re at it, when they remove the salt from the briny water, they may find some other goodies, as well.
Recovering valuable elements
"So, for this, the pilot scale system, the major focus is to treat the brine. So, basically, we turn the brine into fresh water, but at the same time reduce the problem of water pollution. However, you're right that it's a high potential that we can recover valuable elements from different wastewater," Tong said.
Tong and Sinha say the plan is to put the equipment in trailers that would make it mobile, meaning it could go where it’s needed — turning briny water into usable water and salt along the way.
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