Bacteria to clean contaminated leftover water used in fracking
says.
Sponging
It is estimated that frack wastewater contains more than a thousand contaminants; many are organic, and so potential food for bacteria. Biochemistry professor Wackett and microbiology professor Sadowsky, both members of the U’s BioTechnology Institute, teamed up with Aksan to blend their knowledge of bacteria with his expertise in bioencapsulation.
The researchers separate out thousands of chemicals in frack water and identify them. Then, knowing the major sources of carbon in the water, they look for naturally occurring bacteria that will eat the chemicals (spreading genetically engineered bacteria on wastewater ponds or spill sites might result in an uncontrolled release into the environment).
Aksan and postdoc Boris Tong have found a way to embed the bacteria within porous silicon fibers. There they are protected as they absorb oily compounds through the pores in the walls, which are thinner than the bacterial cells.
Wackett likens the spongy material to cotton candy, with bacteria trapped in the strands. A spill on a field could be treated by rolling out and spreading “what looks like a foamy, cottony material” over it,” Wackett says. Treating a body of water would require pumping it through a cylinder with bacteria trapped in sturdier structures: highly porous microscopic beads.
The researchers have filed for a patent on the sponge manufacturing process.
“This work would reduce contamination of water used for industrial purposes and agriculture,” says Wackett. “If it’s to be used for fracking a second well, the interest isn’t so much specific chemicals, but reducing the carbon load. When they inject water, they like pristine water because organic chemicals could promote the growth of bacteria that could quickly clog the operation.”
Much work remains to scale up the technology for commercial use, but the researchers are optimistic.
“I feel very confident that good things will come out of this,” Wackett says. “Fracking is starting in China and elsewhere in the world, so I think it’s important to work on treating and recycling water. If we can find ways that water can be cleaned to the extent it can be re-used in industry, agriculture, or the oil and gas industry, there will be less demand on fresh water.”
After the frack
About 70 percent of the injected water gets left behind in oil- and gas-bearing rock layers after fracking. Chemicals injected with it, plus any natural chemicals released by fracking, have raised concerns about contamination of aquifers used as domestic water sources.
Earth sciences professor Calvin Alexander says: “There is remarkably little documentation of near-surface aquifers being contaminated by current practices. A study in Pennsylvania found no evidence that fracking contaminated drinking water. Many of us believe it’s a real problem, but it’s hard to document. But what if aquifers start going bad in 50 years?”
