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November 30, 2016

Gradiant Replicates Rain Cycle
for Fresh and Recylable Water

Water Treatment Startup Generates Water Quality to Spec

Bernadette Esposito

Anurag Bajpayee
Founder and CEO
“We like to call ourselves solving the world’s greatest water treatment challenges, which either cannot be solved with current technologies or are prohibitively expensive,” says Anurag Bajpayee, co-founder and CEO of Gradiant, a technology-driven water services company focused on treating the most contaminated industrial waste water. While Gradiant’s technologies are applicable to a wide variety of industry, its first market entry was in U.S. oil and gas. In 2012, when the shale boom was going up and water was the centerpiece discussion, both economically and environmentally, Bajpayee and his colleagues at MIT approached industry regarding the economic, logistical, and regulatory constraints in water treatment. By the end of 2013, they had developed a pilot in the field for their first technology called Carrier Gas Extraction and got the go-ahead to convert it into a commercial facility. That year, Gradiant was awarded the Global Water Intelligence “Technology Idol” award for Carrier Gas Extraction, a desalination technique for turning very contaminated water two to five times more saline than sea water into fresh water quality. Bajpayee describes it as a very simple, but creative solution. “What we were trying do is replicate the rain cycle in a confined space and in a very short period of time.”

Carrier Gas Extraction
The technique uses two unit operations: a humidifier and a bubble column dehumidifier. The water, heated by a low temperature thermal source, rises to the top of the humidifier (a tall tower filled with packing material). As the water drips down, the carrier gas (dry, ambient air) goes up, and they come in contact on the packing material, which provides a surface area for the evaporation process. The air picks up the pure water vapor and leaves behind the salts and other contaminants at the bottom as a saturated brine. By the time the air gets to the top of the humidifier, it’s pure air carrying pure vapor. “We Essentially created the cloud,” says Bajpayee. “Next, we had to create the rain.”

Perforated plates run through the inside of the tower of the multi-staged bubble column dehumidifier. Each of the stages has holes in it, and on top of each of the plates sits a shallow pool of ambient temperature or cold fresh water. As this humid air comes through the bottom of the bubble column, it passes through the holes and starts to bubble through the shallow pools of water. As that bubbling happens, a very rapid heat-transfer and mixing process occurs. The air, then, cools down and condenses the water it had picked up, because it can no longer carry the humidity. “You know how in humid air the temperature reduces and you get dew? That’s exactly what we’re getting,” says Bajpayee. “Because you’re adding more pure water to it, each of these liquid columns continues to increase in height, until the liquid column hits the overflow port and falls to the bottom where it is collected as fresh water.” By the time the air has passed the last stage of the bubble column, it’s cold and dry again, and can either be ejected or recycled in a closed loop.

Selective Chemical Extraction
At that point Gradiant’s customers said, “‘This is great, you’re actually half the cost of the existing solutions, but you’re generating pure water. We don’t always need drinking quality water. Can you give us something that’s lower cost and lower performance, as well?’ And we said, ‘Sure,’” says Bajpayee. He and his team went back to the labs and developed a second product line: Selective Chemical Extraction, a treat to speck water treatment solution, where customers tell Gradiant exactly what they need taken out. “Because if you don’t want drinking quality water, then why pay for it?” asks Bajpayee.

In both technologies one of the important things, Bajpayee noted, is the ability to handle variability. “Industrial waste water as opposed to sea water can vary quite a lot. “Most technologies are designed to work at a steady state, whereas our solutions take feed water that is changing constantly—sometimes hour to hour—and continuously optimize the system to generate product water quality that’s exactly the same every single time.”

Free Radical Disinfection
In addition to the fresh water solution and the recyclable water solution, Gradiant also has a solution that disinfects high amounts of bacteria at extremely high through put rates called Free Radical Disinfection. “This is very specific to the oil and gas industry,” he says. “As the water is going down the well for fracking or drilling purposes, it’s important to disinfect—to take the bugs out—as we say in the industry, so that it doesn’t create complications.”

With these three solutions, Gradiant now has full portfolio of water treatment and management needs of its customers. “Water is a diverse field,” says Bajpayee. “If you want to be a world-leading industrial water treatment company, you need to have a portfolio of technologies and solutions, as opposed to one silver bullet you’re trying hit everywhere.” And even though its solutions are commercial and competitive and in some cases completely revolutionary, Gradiant continues to better them with a team that is very good at taking market feedback, improving current technology, and developing new technologies and products to address other problems.

Currently commercially operating in oil and gas fields in Texas and New Mexico, Gradiant is quickly expanding into other industries including coal power plants, textile mills, leather tanneries as well as internationally. Its next generation systems of the same technology are expected to be lower cost and higher efficiency. In addition to these technologies, it is working on technology called Ion Caging, a closed loop softening system specifically focused on sulfate removals. “We are also working on directional solvent extraction, which is another desalination technology for high salinity water, focused on small scale and space-constrained applications. We are working on novel membrane systems, which promise to increase the efficiency or increase the recovery of standard sea water desalination systems,” he says.

“Technology improvement is never complete, as we know,” says Bajpayee. “At MIT we were always working on newer and better and more efficient, and that’s what we’re doing at Gradiant.” In 2014 Gradiant won the industrial water project of the year which is given to a running, working, profitable commercial project. That was the first time in the history of the organization that Gradiant went from a technology idol to an industrial project of the year globally within one year. “Successful companies and successful technologies adapt and evolve along the way. That’s where Gradiant’s strength lies,” says Bajpayee. “Our customers look at us as a good solution, but they also look at us as a long-term partner, a team that can solve any issue in water that might come their way.”

About STEX25 and MIT’s Industrial Liaison Program (ILP)
STEX25 is a startup accelerator focused on fostering collaboration between MIT-connected startups and member companies of MIT’s Industrial Liaison Program (ILP). STEX25 is managed by MIT Startup Exchange, and its parent, the ILP. The ILP is a key player in making industrial connections for MIT, with over 220 of the world’s leading companies using their ILP memberships to advance research agendas at MIT.