After four years of experimentation, a group of researchers in Texas have successfully used a type of virus — used to combat bacterial infections in medicine — to kill bacteria in wastewater from fracking.
This wastewater, which can come with radioactive, cancer-causing materials, and yes, bacteria, often gets shoved back underground for storage. But increasingly, Colorado and other states are looking at ways to clean the wastewater enough that it can be used in other mining operations instead of fresh water. It’s an intriguing idea in Colorado, where fresh water supplies have been strained by a two-decade megadrought.
Could viruses really help? The potential is there — but so are big questions about practicality, researchers say.
“It’s outside-the-box science. We knew that,” said Zacariah Hildenbrand, part of the six-person University of Texas research team that published a study on the viruses in April. “But I mean, necessity is the mother of all innovation here, and we need to find some novel technologies.”
Wastewater, called produced water, is the major waste stream generated by oil and gas production, according to the group’s research published in the peer-reviewed journal Water. The research was funded by Biota Solutions, a Texas-based research company founded to develop viruses to kill bacteria in produced water.
Oil and natural gas can be thousands of feet below the ground’s surface, where it mixes with brackish water. At that depth, the water can include naturally occurring carcinogenic compounds and radioactive materials. It’s so salty that, if used for irrigation, it could kill plants.
During the fracking process, companies pump a mixture of fresh water, sand and chemicals underground where it mixes with oil, gas and the brackish water. It returns to the surface and is separated from the oil and gas. The result is produced water, which can not be used for drinking or irrigation, per state regulations.
In Colorado, water used for fracking averaged about 26,000 acre-feet per year from 2011 to 2020, or about 0.17% of the water used in the state, according to the Colorado Division of Water Resources. One acre-foot roughly equals the annual water used by two to three households.
The highest volumes of water used for hydraulic fracturing are used within the counties along the Front Range in Denver-Julesburg Basin.
“In an arid state like Colorado, where we’re worried about how much water is getting down the Colorado River, that rubs a lot of people the wrong way. And it should,” said Joseph Ryan, an environmental engineering professor at the University of Colorado.
Attack of the viral “spiders”
The complex cocktail of produced water also comes with another ingredient: bacteria.
Some of the bacteria can corrode pipes while others sour the gas, which makes it stinkier and requires more processing. Both can cost oil and gas companies money, Hildebrand said.
Transmission electron micrograph of multiple bacteriophages attached to a bacterial cell wall. (Graham Beards via Wikimedia, Contributed)
Historically, companies have treated these bacteria with disinfectants, like chlorine and hydrogen peroxide. But over time, the bacteria can become more resistant. To protect themselves, they change their membrane structure to become less permeable — like putting on a raincoat in a storm, he said.
Some companies end up using twice as many chemicals to kill the same amount of bacteria, which is more costly and less environmentally sustainable, he said.
So the researchers set out to test another technology: The bacteriophage.
Bacteriophages are viruses that infect specific bacteria. They’re like the spiders in the “Starship Troopers” movie, Hildebrand said. Once the phage finds its host bacteria, it hooks into the surface of the cell, injects its DNA into the center of the bacteria, and hijacks the bacteria’s replication mechanisms.
Then it reproduces until the bacteria explodes.
The process allows the virus to multiply exponentially and infect more cells. But Hildebrand stressed the virus targets only its specific host bacteria, not any other type of cell.
Bacteriophages have been used for decades in medicine to treat issues like skin infections, indigestion and food poisoning caused by E. coli.
“Under the microscope, at the atomic scale, it’s scary. It’s an all-out civil war between bacteria and viruses,” he said. “But from the human perspective, it’s totally innocuous.”
Is the virus enough?
The researchers’ study showed that bacteriophages successfully deactivated two strains of bacteria found in produced water — but there are some key hurdles that would need to be addressed for the technique to be used by oil and gas operators.
Produced water could include tens of thousands of bacterial strains, which means researchers would need far more strains of viruses to disinfect the produced water. And right now, there aren’t enough commercially available bacteriophage strains to make it happen, Hildebrand said.
“The goal is, we just learn enough from all of the basins that ultimately I build a 200-phage cocktail that’s kind of a kill-all, if you will. It’s a belt-and-suspenders approach,” he said. “Once I build it initially, it will renew itself in the environment.”
After the up-front costs, the bacteriophage technique would cost less than a penny per barrel because the virus renews itself, Hildebrand said based on his economic estimates.
Ryan of CU Boulder has doubts, big ones.
When it comes to reusing produced water, corroding pipes are a small problem compared to the radioactivity, salinity and carcinogenic compounds, he said.
There are so many microorganisms in the water that it would be difficult to affordably find enough bacteriophages to completely disinfect it. There’s no way fixing the minor problems caused by bacteria would be worth the effort and cost, he said.
“It’s a questionable solution to a problem that just doesn’t seem at the top of the list of importance if you’re trying to do something with produced water,” Ryan said.
Hildebrand acknowledged that disinfection alone is not enough to clean produced water to a reusable level, but it would help, especially if the bacteria have become resistant to other disinfection methods.
Ryan is one of 31 people on the Colorado Produced Water Consortium, which includes industry, state, federal and environmental representatives. (He emphasized he was not speaking for the group.)
In 2023, the Colorado legislature created the consortium to study how to reuse and recycle wastewater from fracking. The group is set to publish its fourth study on produced water Aug. 1 — one of nine that will be presented to legislators and state agencies.
Hope Dalton, the consortium’s director, declined to comment on the fresh-out-of-the-lab research.
“Generally speaking, bench-level research is innovative and new and hasn’t been tested,” she said. “Then you go out to industry and use it on the larger, pilot scale. Once it’s proven at the larger, pilot scale, then it can be implemented as practice.”
That’s the next step for the Texas researchers, Hildebrand said.
“Yes, it’s very early stages, but considering how effectively it works … how robust the phages are and how cheap they are to produce, I think it provides a really unique solution moving forward,” he said.
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