Barron and his colleagues designed a long, tubular filter with pores a fifth of a micron wide — a few millionths of an inch. That screens out most contaminants, but they would tend to build up in the pores and clog them.
But coating the filter with cysteic acid creates a surface that draws a microscopically thin layer of water to cover the pores. That prevents oily fluids from building up and clogging the filter, he said.
The filters themselves are tubular structures about a meter (3.25 feet) long and about 5 centimeters (2 inches) across, filled with small passages. At the drill site, they would be bundled together in arrays up to the size of a shipping container. Water is pumped into the tubes, with the treated product emerging from the sides. The remaining concentrated mix of contaminants can also be sent to a refinery to extract the oil products inside, he said.
“Your disposal becomes a fraction of what you had before, and the hydrocarbon has a value,” Barron said, adding that the filter he developed is an economically viable solution, with a commercial unit under construction “as we speak.”
RELATED: Watch Swarms of Earthquakes Sweep Across Oklahoma
The findings were published this week in the research journal Scientific Reports. Barron said the filtered water remains too salty to be drinkable, but it’s clean enough to be re-used at the well — and if treated further through reverse osmosis to remove the salt, it would be safe for human consumption. “We have demonstrated that’s possible,” he said.
Currently, most wastewater is disposed of by injecting it deep underground, far below the water table. But in the southern Great Plains, particularly in Oklahoma, the practice has been blamed for a surge of hundreds of small to moderate earthquakes a year. Barron said the process his team developed could reduce the amount of wastewater enough to calm those shakes.
“Essentially you would get to the point where you wouldn’t need to do deep-well injection,” he said.