A process to make hydraulic fracturing, or fracking water-neutral, by making treating and recycling contaminated oilfield water more economical, is under development by MIT spinout Gradiant Corporation.
MIT News reports that Gradiant says the cost-effective water treatment system will save millions of gallons of water — and millions of dollars — annually.
Launched in 2012 with help from MIT’s industry-connected ecosystem, Gradiant has erected two 12,000-barrel-per-day plants in the Permian Basin of Texas, partnering with two drilling clients who treat about 10,000 barrels daily there.
The plants each use separate technologies that treat varying infeed water, which can be adjusted to customer specifications. Carrier gas extraction (CGE), a humidification and dehumidification (HDH) technique developed by the Gradiant co-founders at MIT, heats produced water into vapor, and condenses it back into water, without contaminants. This yields freshwater and saturated brine, commonly used in drilling and completion processes.
Selective chemical extraction (SCE) is a cost-effective version of standard chemical-precipitation techniques — where chemical reactions remove specific contaminants to produce clean brine. Both systems employ custom control algorithms that minimize operator intervention and chemical consumption, while continuously adjusting the process to account for varying feed water quality.
Thanks to several design innovations, these systems can treat water with higher levels of contamination using less energy and at lower costs than competing treatment methods, according to Gradiant.
Reverse osmosis, for example, treats water with a maximum contamination level of around 7 percent, while legacy thermal desalination reaches about 20 to 22 percent. But Gradiant’s technology uses even less energy to treat water beyond 25 percent, broadening the range of water that can be treated, the company says.
Photo Credit: Gradiant